WO2024120983A1 - Composition de suspension pour cathode aqueuse destinée à une cathode de batterie - Google Patents

Composition de suspension pour cathode aqueuse destinée à une cathode de batterie Download PDF

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Publication number
WO2024120983A1
WO2024120983A1 PCT/EP2023/083862 EP2023083862W WO2024120983A1 WO 2024120983 A1 WO2024120983 A1 WO 2024120983A1 EP 2023083862 W EP2023083862 W EP 2023083862W WO 2024120983 A1 WO2024120983 A1 WO 2024120983A1
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WIPO (PCT)
Prior art keywords
acid
slurry composition
alkali metal
binder
cathode
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PCT/EP2023/083862
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English (en)
Inventor
Prasad Mangesh KORDE
Parth Omprakash DAYAMA
Anna SEMENOVA
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Northvolt AB
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Northvolt AB
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Priority claimed from SE2251414A external-priority patent/SE546429C2/en
Priority claimed from SE2350467A external-priority patent/SE547030C2/en
Application filed by Northvolt AB filed Critical Northvolt AB
Publication of WO2024120983A1 publication Critical patent/WO2024120983A1/fr
Anticipated expiration legal-status Critical
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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a cathode slurry composition, and its preparation, for use in a cathode, a cathode comprising the composition and a lithium-ion cell including the cathode.
  • NMP N-methyl-2-pyrrolidone
  • PVDF Polyvinylidene fluoride
  • NMP as the solvent
  • PVDF suffers from several drawbacks, such as low binding affinity, poor electrochemical and thermal stability, poor processability in water and potential toxicity. Fluorinated polymers can be harmful to both the environment and human health, and proposals are underway for the broad restriction of per- and polyfluoroalkyl substances (PFAS) in the EU. As a result, there is interest in identifying more stable, cheaper and more environmentally friendly alternatives to PVDF.
  • PFAS per- and polyfluoroalkyl substances
  • High voltage lithium-ion batteries may offer advantages such as high energy density and capacity, longer lifespan, rapid charging capability and wide compatibility with devices.
  • High-nickel cathode materials are also commercially attractive due to the improved performance in relation to cost.
  • high-nickel cathode materials are prone to adverse phase transitions, nickel leaching and deterioration in battery performance when run at high voltage.
  • cycling under high voltage conditions may result in oxidation and/or decomposition of binder materials. Therefore, there is a need for electrodes and lithium-ion batteries with prolonged cycle stability, such as electrochemical and/or mechanical stability, which may be manufactured using an environmentally friendly process.
  • This disclosure relates to a novel electrode slurry composition, a method of preparation of such slurry, and electrodes and cell assemblies formed from this slurry.
  • a slurry composition comprising: a cathode active material; a binder system; a dispersing medium; and optionally a conductive agent, wherein the binder system comprises: a binder polymer, an alkali metal salt of an acidic polysaccharide, and an acid or salt thereof.
  • a method for forming a slurry composition comprising the steps of: a. providing a composition comprising a cathode active material, an acid, an alkali metal salt of an acidic polysaccharide, a binder polymer, optionally a conductive agent, and optionally a dispersing medium; and b.
  • the method comprises adding said acrylic polymer, optionally together with dispersing medium, to an intermediate slurry composition having solids content of from 65 wt% to 85 wt%, and mixing to provide a slurry composition having a solids content of from 60 wt% to 80 wt%.
  • an electrode comprising: a cathode active material; a binder system; and optionally a conductive agent, wherein the binder system comprises: a binder polymer, an alkali metal salt of an acidic polysaccharide, and an acid or salt thereof.
  • a binder system for an electrode comprising: a binder polymer, an alkali metal salt of an acidic polysaccharide, and an acid or salt thereof.
  • Figure 1 shows the voltage and capacity for the half-cell of Example 1 during its formation cycle.
  • Figure 2 shows the voltage and capacity for the half-cell of Example 2 during its formation cycle.
  • Figure 3 shows the peel strength of cathodes prepared from Examples 1 to 4 and Comparative Example 1.
  • Figure 4 shows the peel strength of cathodes prepared from Example 1 using water or NMP as the dispersing media.
  • Figure 5 shows the pH of a slurry composition according to Example 2, for a period of 0 to 7 days after its preparation.
  • Figure 6 shows the pH of a comparative slurry composition not comprising an alkali metal salt of an acidic polysaccharide or an acid, for a period of 0 to 7 days after its preparation.
  • Figure 7 shows a shear rate sweep test of slurry compositions according to Example 2 using water or NMP as the dispersing media.
  • Figure 8 shows the gas (CO2) evolution of slurry compositions according to Example 2 using water or NMP as the dispersing media.
  • the binder system of the disclosure comprises a binder polymer, an alkali metal salt of an acidic polysaccharide, and an acid or salt thereof. These components combine to provide a binder system that allows cathode active materials to be processed in an aqueous media.
  • the binder system comprises about 5 to 50 wt% of a binder polymer, about 10 to 60 wt% of an alkali metal salt of an acidic polysaccharide and about 10 to 75 wt% of an acid or salt thereof, based on the weight of the non-volatile content of the binder system.
  • the binder system comprises about 10 to 40 wt% of a binder polymer, about 15 to 55 wt% of an alkali metal salt of an acidic polysaccharide and about 20 to 65 wt% of an acid or salt thereof, based on the weight of the non-volatile content of the binder system.
  • the binder system comprises about 10 to 40 wt% of a binder polymer, about 20 to 55 wt% of an alkali metal salt of an acidic polysaccharide and about 25 to 55 wt% of an acid or salt thereof, based on the weight of the nonvolatile content of the binder system.
  • the binder polymer is the binder polymer is selected from an acrylic polymer, an acrylamide copolymer or mixtures thereof.
  • the binder system comprises about 10 to 50 wt% of an acrylamide copolymer, about 10 to 50 wt% of an alkali metal salt of an acidic polysaccharide and about 10 to 55 wt% of an acid or salt thereof, based on the weight of the non-volatile content of the binder system.
  • the binder system comprises about 25 to 40 wt% of an acrylamide copolymer, about 15 to 30 wt% of an alkali metal salt of an acidic polysaccharide and about 20 to 50 wt% of an acid or salt thereof, based on the weight of the non-volatile content of the binder system.
  • the binder system comprises about 25 to 40 wt% of an acrylamide copolymer, about 20 to 35 wt% of an alkali metal salt of an acidic polysaccharide and about 25 to 50 wt% of an acid or salt thereof, based on the weight of the non-volatile content of the binder system.
  • the binder system comprises about 10 to 20 wt% of an acrylic polymer, about 40 to 50 wt% of an alkali metal salt of an acidic polysaccharide and about 45 to 55 wt% of an acid or salt thereof, based on the weight of the nonvolatile content of the binder system.
  • the pH control of the slurry composition is important for maintaining the stability of the slurry, in addition to having a suitable viscosity for coating (and avoids corrosion of) the conductive foil (i.e. aluminium foil). Therefore, the selection of components for the binder system is critical for providing a stable and processable slurry composition which may be manufactured into a cathode. Furthermore, the resulting cathode and cell should be capable of being operated under high voltage conditions while maintaining electrochemical and/or mechanical stability.
  • the acid component is believed to interact with any lithium ions that may leach from the cathode active material when it is exposed to a dispersing medium such as water. It is proposed that the acidic groups of the acid component in the binder system may react with the lithium ions of the cathode active material, which can result in a coating of the acid or salt thereof on the surface of the cathode active material. This coating may then protect the cathode active material against any further degradation. Highly acidic solutions may impact the electrode active material, and therefore an alkali metal salt of an acidic polysaccharide is used to buffer the system when in slurry form, typically to pH 6-10. The acidic polysaccharide provides the additional benefit that it can coat the electrode active material, acting as a binder as well as increasing viscosity of the slurry.
  • the alkali metal salt of the acidic polysaccharide is used in the preparation of the slurry composition without any acid, lithium may react with water and form unwanted by-products. Therefore, the acid is able to balance the pH of the aqueous cathode slurry, form a complex with the lithium ions and protect degradation of the cathode active material.
  • the binder system additionally comprises a binder polymer which acts as a binder to the dried composition, providing flexibility and strength to the electrode formed from the slurry.
  • the binder polymer additionally improves adhesion of the electrode to the foil.
  • the resultant electrodes have excellent cycle life, rate capacity, as well as flexibility, allowing them to be rolled for incorporation into a cell, such as a cylindrical cell, prismatic cell, pouch cell, or coin cell.
  • the binder polymer is not added to the binder system, and the binder system contains only an alkali metal salt of an acidic polysaccharide and an acid, then this may result in a cathode which lacks flexibility. This can subsequently result in degradation of the cathode during cell operation, and poor life cycle stability.
  • the peel strength of a cathode may be from about 10 to 18 N/m, for instance from about 12 to 15 N/m.
  • the peel strength may be measured in accordance with ASTM D3330.
  • the peel strength test may be carried out on a Universal Testing Machine (e.g. Instron 3345), for example, using an electrode sample having a width of 25 mm.
  • Each of the electrode plates in which the coating layers were located on both surfaces of the current collectors may be cut to a size of 25 mmxl50 mm.
  • the peel strength may be an average of 20 samples.
  • the binder polymer is optimal for use in the cathode of a lithium-ion cell, since it has excellent electrochemical stability during cell operation and under the conditions to which the cathode is subjected during charge and discharge cycling.
  • Other common binder materials such as styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), hydrogenated butadiene rubber (HBR), and other rubbers, may be suitable for use in the anode, but are incompatible for use in the cathode due to the likelihood of electrochemical oxidation if used in the cathode.
  • SBR styrene butadiene rubber
  • CMC carboxymethyl cellulose
  • HBR hydrogenated butadiene rubber
  • binders may have poor stability when used in the electrode of a cell operating at high voltage. If a cell is run at or above 4.2 V, there may be decomposition of the binder and/or delamination of the electrode.
  • high-nickel cathode materials are considered to be promising cathode candidates due to advantages of high capacity, low cost and/or good cycle performance.
  • high-nickel cathode materials allow for a reduced amount of cobalt (or even cobalt-free) in the cathode active material, and therefore a reduced cost.
  • High-nickel cathode active materials may show improved capacity compared to those having a lower Ni-content. Therefore, a binder system allowing for the use of high-nickel cathode materials, for example that may be run at high voltage, while maintaining electrochemical and/or mechanical stability and/or performance, is of particular interest.
  • the alkali metal salt of an acidic polysaccharide may be particularly suitable for stabilising high-nickel cathode materials and prevent nickel and/or manganese leaching.
  • the salt of an acidic polysaccharide e.g. alginate
  • the driver for gel formation is replacement of the alkali metal cation with the divalent cation leached from the cathode active material.
  • the binder system of the disclosure therefore provides the protective coating on the CAM where and when it is needed.
  • the slurry composition does not comprise an alkali metal salt of an acidic polysaccharide in the binder system, then this leads to a slurry composition with a pH that is too acidic. This subsequently leads to dissolution of transition metal from the cathode active material, and as a result leads to an inferior cathode and respective cell when said slurry composition is used in the cathode and cell.
  • the cell capacity is lower for a cell comprising a cathode that is prepared using a slurry composition which is too acidic.
  • the alkali metal salt of the acidic polysaccharide is required in the binder system and the slurry composition in order to act as a buffer (neutralising agent) and increase the pH of the slurry composition.
  • a slurry composition comprising the alkali metal salt of the acidic polysaccharide will result in the slurry composition being less acidic, and therefore can result in a cathode and subsequent cell comprising said cathode that displays a higher charge and discharge capacity.
  • the alkali metal salt of an acidic polysaccharide may also function as a rheological modifier in the slurry composition. This can be useful for enhancing the viscosity of the slurry, particularly when other components in the binder system have a low molecular weight. For example, if the binder system comprises an acid which has a low molecular weight, then the viscosity of the slurry can be increased by using an alkali metal salt of an acidic polysaccharide. This may subsequently be desirable for maintaining the preferred properties of the slurry composition, such as good stability and coating ability (see e.g. Figure 7).
  • the cathode does not comprise an alkali metal salt of an acidic polysaccharide (i.e. alginate) in the binder system, this may result in uncontrolled leaching of transition metal (e.g. Ni and/or Mn) from the cathode active material, which may lead to an inferior cathode and respective cell while in use.
  • transition metal e.g. Ni and/or Mn
  • the binder system is present in an amount of from about 0.2 to 8 wt%, for example about 0.5 to 6 wt%, for example about 1 to 4 wt%, for example about 1.5 to 3.5 wt%, for example about 2 to 3 wt%, based on the total weight of the dry composition (i.e. the slurry composition excluding the dispersing medium, or alternatively the electrode).
  • the acid may be a molecular organic acid, a polymeric organic acid or a mineral acid.
  • the acid has a pKa of from 2 to 10, more preferably from 2 to 6.
  • the acid may comprises a molecular organic acid, such as a molecular carboxylic acid.
  • the acid may be a compound selected from one or more of the following malonic acid, acetic acid, citric acid, oxalic acid, formic acid, benzoic acid, carbonic acid, glycolic acid, glyoxylic acid, propanoic acid, acrylic acid, propiolic acid, lactic acid, glyceric acid, pyruvic acid, tartronic acid, mesoxalic acid, glycidic acid, butanoic acid, isobutanoic acid, succinic acid, fumaric acid, maleic acid, malic acid, tartaric acid, valeric acid, pivalic acid, glutaric acid, hexanoic acid, adipic acid, pimelic acid, salicylic acid, heptanoic acid, terephthalic acid, caprylic acid, and mixtures thereof.
  • the acid is selected from malonic acid, acetic acid, citric acid, oxalic acid, gluconic acid, or mixtures thereof. More preferably, the acid is selected from malonic acid, acetic acid, citric acid, or mixtures thereof.
  • the acid does not comprise a group 13 element, such as boron, for example boric acid and/or boronic acid.
  • the acid may comprise a polymeric organic acid, such as a polymer comprising carboxylic acid groups.
  • the acid may be selected from one or more of polyacrylic acid (PAA), polymethacrylic acid (PMAA), polyethylacrylic acid, poly-4-carboxystyrene, polymaleic acid, alginic acid, carboxymethyl cellulose, and mixtures thereof.
  • the acid is selected from polyacrylic acid, polymethacrylic acid (PMAA), alginic acid, carboxymethyl cellulose, or mixtures thereof. More preferably, the acid is selected from polyacrylic acid or alginic acid.
  • the polymeric acid when it is polyacrylic acid, it may have a number average molecular weight (M n ) of from about 300,000 to about 2,000,000 g/mol, for example from about 400,000 to about 1,500,000 g/mol.
  • M n number average molecular weight
  • the polymeric acid when it is alginic acid, it may have a number average molecular weight (M n ) of from about 10,000 to about 500,000 g/mol, for example from about 15,000 to about 300,000 g/mol.
  • M n number average molecular weight
  • the molecular weight of the polymeric organic acid will affect the viscosity of a solution or a slurry containing the polymeric organic acid.
  • a polymeric organic acid with a high molecular weight will result in a solution or a slurry with a high viscosity, which can consequently affect other properties such as the dispersion stability of the slurry and the coating ability of the slurry, when coating the cathode slurry composition onto the conductive foil. Therefore, the amount of polymeric organic acid may be varied to tune the rheological properties of the aqueous cathode slurry.
  • the polymeric organic acid may therefore act as a rheological modifier as well as an acid in the aqueous cathode slurry.
  • the acid may comprise a mineral acid, for example a compound selected from one or more of the following phosphoric acid, phosphonic acid, and mixtures thereof.
  • the acid may comprise a compound containing phosphorus.
  • phosphoric acid or an organophosphorus compound such as an organophosphate, phosphonate or an ester of phosphoric acid.
  • Suitable examples include a compound selected from one or more of the following H3PO4, H2RPO4, HR.2PO4, HRR'PC , and mixtures thereof, wherein R and R' represent organic groups.
  • the acid is phosphoric acid.
  • the acid is preferably selected from one or more of malonic acid, acetic acid, citric acid, oxalic acid, polyacrylic acid, alginic acid, carboxymethyl cellulose, phosphoric acid, and mixtures thereof.
  • the acid is selected from one or more of malonic acid, acetic acid, citric acid, polyacrylic acid, alginic acid, phosphoric acid, and mixtures thereof.
  • the amount of acid in the composition depends on the pKa value of the acid. If the acid has a high pKa value, for example if the acid is weak, then more acid may be required to reduce the pH of the slurry composition. If the acid has a low pKa value, for example if the acid is strong, then less acid may be needed to reduce the pH of the slurry composition.
  • the acid may be present in an amount of from about 0.03 to about 5 wt%, such as from about 0.05 to about 4 wt%, for example from about 0.05 to about 2 wt%, for example from about 0.1 to about 3 wt%, preferably from about 0.2 to about 1 wt% based on the total weight of the dry composition (i.e. the slurry composition excluding the dispersing medium, or alternatively the electrode).
  • the acid may be present in the system in the form of its salt, which is typically formed by reaction with lithium or by reaction with the alkali metal salt of the acidic polysaccharide.
  • the salt of the acid is therefore typically an alkali metal salt, such as a lithium or sodium salt, preferably a lithium salt.
  • an “acidic polysaccharide” is a polysaccharide having carboxyl groups.
  • the acidic polysaccharide is a compound selected from one or more of alginic acid, xanthan gum, and combinations thereof.
  • the acidic polysaccharide is alginic acid.
  • the acidic polysaccharide has a molecular weight that allows coating of the cathode active material, yet is not so high that the viscosity of the slurry composition becomes too high to allow the composition to be coated onto a foil.
  • Typical number average molecular weights are from about 10,000 to about 500,000 g/mol, for example from about 15,000 to about 300,000 g/mol, based on the acid (i.e. not the alkali metal salt of the acid polysaccharide)
  • the acidic polysaccharide when it is alginic acid, it may have a number average molecular weight (M n ) of from about 10,000 to about 500,000 g/mol, for example from about 15,000 to about 300,000 g/mol, based on the acid (i.e. not the alkali metal salt of the acid polysaccharide).
  • M n number average molecular weight
  • the acidic polysaccharide is present as an alkali metal salt.
  • the acidic groups in the acidic polysaccharide are preferably all in salt form, i.e. the acidic polysaccharide preferably does not contain any free acid groups.
  • the alkali metal may be selected from lithium, sodium, potassium, or mixtures thereof. Preferably, the alkali metal is selected from lithium or sodium.
  • the alkali metal salt of an acidic polysaccharide is selected from lithium alginate, sodium alginate, or a combination thereof.
  • lithium and sodium alginate provide several desirable properties. Lithium and sodium alginates have good solubility in water, can act as rheological modifiers and can also act as buffering agents which can balance the pH of the slurry composition. Therefore, lithium alginate or sodium alginate may act both as a viscosity modifier and a neutralising agent.
  • Lithium and sodium alginate are therefore preferable over other alkali metal salts of acidic polysaccharides since they may enhance the viscosity of the slurry composition and act as a neutralising agent.
  • Other acidic polysaccharides such as sodium carboxymethyl cellulose, may only form neutral or weakly alkaline solutions and therefore cannot act effectively as neutralising agents, whereas lithium and sodium alginate form more alkaline solutions and therefore are more effective as neutralising agents.
  • Acidic polysaccharides are a good material to use since they are relatively low cost and are often sourced from natural products. Furthermore, they are also biodegradable.
  • Alginates or alginic acid also provide good properties in the final electrode, since they can have a supramolecular self-healing ability which allows them to accommodate large volume changes of the electrode (which may occur during charge and discharge cycling). This ability prevents the electrode from cracking, or losing contact with other cell components, during charge and discharge cycling when used in the cell. As a result, the cell capacity may be retained during cell usage.
  • some (or all) of the alkali metal salt of an acidic polysaccharide may be in the form of a metal salt of an acidic polysaccharide (e.g. a transition metal salt of an acidic polysaccharide), for example due to reaction with the cathode active material (e.g. the transition metal).
  • a metal salt of an acidic polysaccharide e.g. a transition metal salt of an acidic polysaccharide
  • the cathode active material e.g. the transition metal
  • the alkali metal salt of an acidic polysaccharide may be present in an amount of from about 0.01 to about 3 wt%, such as from about 0.03 to about 2 wt%, for example from about 0.05 to about 1 wt%, preferably from about 0.5 to about 1 wt%, based on the total weight of the dry composition (i.e. the slurry composition excluding the dispersing medium, or alternatively the electrode).
  • the alkali metal salt of acidic polysaccharide may be soluble in a solvent, such as water.
  • a solvent such as water
  • the alkali metal salt of acidic polysaccharide may be a water-soluble alkali metal salt of acidic polysaccharide.
  • the alkali metal salt of the acidic polysaccharide may be formed by reacting an acidic polysaccharide with a suitable alkali metal hydroxide, such as lithium hydroxide or sodium hydroxide, in a solvent such as water.
  • a suitable alkali metal hydroxide such as lithium hydroxide or sodium hydroxide
  • the binder polymer provides flexibility to the electrode, improves adhesion of the electrode to the foil, and reduces unwanted side reactions in the slurry prior to formation of the electrode.
  • the binder polymer is present in an amount of from about 0.05- 5 wt%, such as from about 0.1-4 wt%, for example from about 0.1-3 wt%, such as about 0.1-1.5 wt%, for example from about 0.1-0.7 wt%, based on the total weight of the dry composition (i.e. the slurry composition excluding the dispersing medium, or alternatively the electrode).
  • the binder polymer has a number average molecular weight (M n ) of from about 300,000-2,000,000 g/mol, for example from about 400,000-1,500,000 g/mol.
  • the number average molecular weight is between 500,000- 1,000,000 g/mol, for example between 600,000-900,000 g/mol.
  • the binder polymer typically has a pH (when dispersed in water) of from 5-10, for example from 6-10, preferably from 7-9.
  • the binder polymer particularly an acrylic polymer, may have a glass transition temperature of from about -80 to about 65 °C, for example from about -60 to about 45 °C, such as from about -40 to about 25 °C.
  • a glass transition temperature within this range may help to improve the electrode flexibility, which can subsequently lead to better cycle life performance and rate capacity of the cell.
  • the binder polymer comprises or consists of an acrylic polymer, an acrylamide copolymer, or a mixture thereof.
  • acrylamide copolymer is meant a polyacrylamide copolymer, or in other words a polymer formed from different monomers wherein one of the monomers is chosen from the group of acrylamide monomer.
  • the acrylamide monomer may be selected from one or more of the following acrylamide, methacrylamide, or mixtures thereof.
  • the acrylamide copolymer comprises 20-80 wt% (meth)acrylamide.
  • (meth)acrylamide is meant acrylamide or methacrylamide, i.e. the parenthesis indicate that the methyl group may or may not be present.
  • the acrylamide copolymer typically comprises (meth)acrylamide and at least one acidic comonomer, preferably (meth)acrylamide and at least one comonomer selected from a carboxylic acid, a sulfonic acid, or mixtures thereof.
  • the acrylamide copolymer thus typically further comprises the inclusion of monomers of unsaturated organic acids selected from the group consisting of unsaturated carboxylic acids and unsaturated sulfonic acids and/or the alkali metal salt thereof.
  • unsaturated carboxylic acids include (meth)acrylic acid, crotonic acid, maleic acid, fumaric acid and itaconic acid.
  • unsaturated sulfonic acids include o,B-ethylenically unsaturated sulfonic acid, such as vinylsulfonic acid, styrenesulfonic acid, (meth)allylsulfonic acid; meth)acrylamide t-butylsulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, 2-(meth)acrylamide-2-hydroxypropanesulfonic acid,
  • Preferred unsaturated acid monomers include (meth)acrylic acid and (meth)allyl sulfonic acid.
  • the acrylamide copolymer comprises 5-50 wt% unsaturated organic acids and/or the alkali metal salt thereof, more preferably from 10 to 40 wt%.
  • the acid component is typically present in a mixture of the acid and alkali metal salt form, for instance wherein from 20% to 80% of the acid groups are present as the alkali metal salt, preferably from 25% to 75%.
  • Suitable alkali metals are selected from lithium, sodium or potassium, with lithium and sodium being preferred and lithium being particularly preferred.
  • the acrylamide copolymer comprises the inclusion of monomers of hydroxyl group containing vinyl compounds.
  • the hydroxyl group containing vinyl compound may be a hydroxyl containing vinyl ether.
  • the acrylamide copolymer comprises 0-75 wt% hydroxyl group containing vinyl compounds.
  • the acrylamide copolymer is delivered as an aqueous solution comprising from 10 to 15 wt% acrylamide copolymer.
  • the acrylamide copolymer content in the aqueous solution is from 13 to 14 wt%, such as approximately 13.5 wt%.
  • the acrylamide copolymer preferably has a pH (in water) from 5 to 10. Preferably, from 7 to 9.
  • the pH of the acrylamide copolymer can be altered by varying the amount of acid and metal salt thereof.
  • the acrylamide copolymer in an aqueous solution has a viscosity from 10,000-30,000 mPa-s, for example from 15,000-25,000 mPa-s, preferably from 17,000-23,000 mPa-s.
  • the viscosity is measured by a B-type viscometer such as "B-type Viscometer Model BM" (product name) by Toki Sangyo Co., Ltd.
  • a B-type viscometer such as "B-type Viscometer Model BM” (product name) by Toki Sangyo Co., Ltd.
  • the acrylamide copolymer content in the aqueous solution is approximately 13.5 wt% during viscosity measurement.
  • the acrylamide copolymer has a number average molecular weight (M n ) of from about 300,000-2,000,000 g/mol, for example from about 400,000- 1,500,000 g/mol, such as between 500,000-1,000,000 g/mol, for example between 600,000-900,000 g/mol.
  • M n number average molecular weight
  • the acrylamide copolymer is present in an amount of from about 0.05-5 wt%, for example from about 0.05-2 wt%, such as from about 0.1 to about 1 wt%, preferably about 0.1 to about 0.7 wt%, based on the total weight of the dry composition (i.e. the slurry composition excluding the dispersing medium, or alternatively the electrode).
  • the binder polymer in particular the acrylic polymer, is in the form of a non-ionic polymer and/or non-acidic polymer.
  • the acrylic polymer does not comprise free acid groups, such as carboxylic acid groups. In this way, the pH of the slurry composition does not become too acidic, thereby avoiding dissolution of transition metal from the cathode active material and/or precipitation of components of the slurry.
  • acrylic polymer is meant a polyacrylate polymer, or in other words a polymer formed from acrylic acid alkyl ester monomers, for example an acrylate alkyl ester monomer.
  • the acrylic polymer is a polyacrylate polymer wherein the acrylic groups are in the form of esters.
  • the acrylic polymer does not comprise an acidic group, such as a carboxylic acid group.
  • the acrylic polymer may be selected from one or more of the following poly(methyl methacrylate), poly(methyl acrylate), poly(ethyl acrylate), poly(butyl acrylate), poly(2-ethylhexyl acrylate), and mixtures thereof.
  • the acrylic polymer may be a copolymer formed from two or more of methyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, or 2-ethylhexyl acrylate.
  • the acrylic polymer typically has a pH (when dispersed in water) of from 6 to 10, for example from 6 to 9 and preferably from 8 to 9.
  • the acrylic polymer has a number average molecular weight (M n ) of from about 300,000 to about 2,000,000 g/mol, for example from about 400,000 to about 1,500,000 g/mol.
  • the acrylic polymer is present in an amount of from about 0.05- to about 5 wt%, such as from about 0.1 to about 4 wt%, for example from about 0.2 to about 3 wt%, preferably about 0.5 to about 1.5 wt%, based on the total weight of the dry composition (i.e. the slurry composition excluding the dispersing medium, or alternatively the electrode).
  • the slurry composition comprises a dispersing medium.
  • the dispersing media may include N-methyl pyrrolidone (NMP), water, or mixtures thereof.
  • NMP N-methyl pyrrolidone
  • the dispersing medium comprises water.
  • Other solvents may also be used in combination with water, such as organic solvents that are miscible with water may be used.
  • the dispersing medium consists of water.
  • aqueous solvents are preferred, since this can help to reduce costs by avoiding the use of a humidity-controlled environment and dry room conditions during cathode manufacture. Furthermore, the cost of the aqueous solvent itself may be cheaper compared to solvents such as NMP.
  • the cathode active material may comprise a suitable material for use as an electrochemically active material in the cathode of a cell, particularly a lithium ion cell.
  • electrochemically active material is to be understood as an electrochemical species which can be oxidised and reduced in a system which enables a cell to produce electric energy during discharge.
  • the role of the cathode active material is to reversibly store, convert and/or alloy with lithium, e.g. via intercalation (or otherwise binding) ions (such as lithium ions) during cell charge and discharge cycles.
  • the cathode active material may comprise an intercalation material, such as a lithium intercalation material, for example a lithium metal oxide which may include lithium and a transition metal.
  • a lithium intercalation material for example a lithium metal oxide which may include lithium and a transition metal.
  • the cathode active material may comprise any one or a mixture of two or more of lithium manganese oxide, lithium nickel oxide, lithium cobalt oxide, lithium nickel manganese oxide (LNMO), lithium nickel cobalt oxide, lithium nickel manganese cobalt (NMC) oxide, lithium iron phosphate (LFP), lithium nickel manganese phosphate (NiMP), lithium iron manganese phosphate (LFMP) and lithium nickel cobalt aluminium oxide (NCA).
  • the cathode active material may comprise any one or a mixture of two or more of lithium manganese oxide, lithium nickel oxide, lithium cobalt oxide, lithium nickel manganese oxide (LNMO), lithium nickel cobalt oxide, lithium nickel manganese cobalt (NMC) oxide, lithium iron phosphate (LFP), lithium iron manganese phosphate (LFMP) and lithium nickel cobalt aluminium oxide (NCA).
  • LNMO lithium nickel manganese oxide
  • NMC lithium nickel manganese cobalt oxide
  • NMC lithium nickel manganese cobalt oxide
  • LFP lithium iron phosphate
  • LFMP lithium iron manganese phosphate
  • NCA lithium nickel cobalt aluminium oxide
  • the cathode active material is an NMC material, i.e. a lithium nickel manganese cobalt oxide. Even more preferably, the cathode active material is an NMC material intercalated with lithium or an "Li-NMC" material.
  • the cathode active material may comprise 80 mol% or more Ni, based on the total amount of non-lithium metals in the cathode active material, such as from about SO- 98 mol% Ni, for example from about 90-95 mol% Ni, such as from about 85-95 mol% Ni, such as from about 88-92 mol% Ni, based on the total amount of non-lithium metals in the cathode active material.
  • Exemplary cathode active materials include nickel-manganese-cobalt (NMC) composite oxides and lithium NMC (Li-NMC) composite oxides or lithium nickel manganese cobalt (NMC) oxides (LiNii- x y CoxMn y C>2 (0 ⁇ x+y ⁇ 0.2)).
  • NMC nickel-manganese-cobalt
  • Li-NMC lithium NMC
  • NMC lithium nickel manganese cobalt oxides
  • the cathode active material may comprise lithium nickel cobalt manganese oxides (NMC) (LibNii- x-y -zCoxMn y A z O2 (0 ⁇ x+y+z ⁇ 0.2)), where A is an element other than Li, Ni, Co, Mn or O and wherein 0 ⁇ z ⁇ 0.05, preferably 0 ⁇ z ⁇ 0.03, more preferably 0.001 ⁇ z ⁇ 0.01, and wherein 0.9 ⁇ b ⁇ 1.2.
  • A is one or more chosen from the group Al, B, Zr, Ba, Ca, Ti, Mg, Ta, Nb, V, Fe, Ru, Re, Pt and Mo.
  • A is chosen from the group Al and Zr.
  • the NMC cathode materials may be defined as LibNii- x-y -zCoxMn y AzC>2, wherein 0 ⁇ x+y+z ⁇ 0.2, preferably 0 ⁇ x+y+z ⁇ 0.15, more preferably 0 ⁇ x+y+z ⁇ 0.12, and wherein 0 ⁇ z ⁇ 0.05, preferably 0.002 ⁇ z ⁇ 0.03, more preferably 0.001 ⁇ z ⁇ 0.01, and wherein 0.9 ⁇ b ⁇ l.l.
  • A is one or more chosen from the group Al, B, Zr, Ba, Ca, Ti, Mg, Ta, Nb, V, Fe, Ru, Re, Pt and Mo.
  • A is chosen from the group Al and Zr.
  • the cathode active material may comprise a lithium metal oxide material that is coated with another material.
  • a lithium metal oxide may be coated with a different lithium metal oxide, carbon, graphene, or a combination thereof.
  • the coating material may have been coated using atomic layer deposition (ALD) as a non-limiting example.
  • the cathode active material may be present in an amount of from about 80 to about 99 wt%, for example from about 85 to about 99 wt%, such as from about 90 wt% to about 98 wt%, for example from about 95 to about 97 wt%, based on the total weight of the dry composition (i.e. the slurry composition excluding the dispersing medium, or alternatively the electrode).
  • the role of the conductive agent is to improve the electronic properties of the cathode and to provide an electrical connection between the particles of cathode active material in the cathode. As it is present merely to improve conductivity, it is optional as the inherent conductivity of the cathode active material may be sufficient.
  • the conductive agent may comprise carbon black, acetylene black, graphene, graphite, mesocarbon microbead (MCMB), pitch-based carbon, coke powders, single-walled, thin-walled and/or multi-walled carbon nanotubes, metallic powders, or a combination thereof.
  • Preferred conductive agents are selected from carbon black, acetylene black, carbon nanotubes, or a combination thereof.
  • the conductive agent may be present in an amount of from about 0 wt% to about 6 wt%, for example from 0 wt% to about 4 wt%, such as from about 0 wt% to about 3 wt%, preferably from about 0.1 wt% to 2 wt%, or from about 0.3 wt% to 2 wt%, based on the total weight of the dry composition (i.e. the slurry composition excluding the dispersing medium, or alternatively the electrode).
  • the slurry composition is formulated to a suitable viscosity to allow it to be processed into a cathode, for example by slot-die coating.
  • the slurry composition may display a shear-thinning non-Newtonian behaviour.
  • the slurry composition typically has a dynamic viscosity of from about 0.5-50 Pa.s at a shear rate of about 10 s -1 , such as from about 1-40 Pa.s, for instance from about 2 to about 40 Pa.s, for instance from about 2-25 Pa.s, as measured at 25°C.
  • the slurry composition typically contains from about 60 to 80 wt% solids, such as from about 65 to 75 wt% solids, preferably from about 68 to 73 wt% solids, more preferably from about 70 to 72 wt% solids, with the remainder being dispersing medium.
  • the method of formation of the slurry composition is not critical, and once formed it is typically stable at room temperature for at least one day, preferably at least one week.
  • stable in this context is meant that the solid particles do not settle.
  • the components of the binder system i.e. the binder polymer, alkali metal salt of an acidic polysaccharide and acid or salt thereof
  • the binder polymer i.e. the binder polymer, alkali metal salt of an acidic polysaccharide and acid or salt thereof
  • the components of the binder system may be added at different steps during the preparation of the slurry composition.
  • slurry composition by combining the ingredients in any order, best results are obtained when following the method of the disclosure which comprises the steps of: a. providing a composition comprising cathode active material, an acid, an alkali metal salt of an acidic polysaccharide, a binder polymer, optionally a conductive agent, and optionally a dispersing medium; b.
  • the method comprises adding said acrylic polymer, optionally together with dispersing medium, to an intermediate slurry composition having a solids content of from 65 wt% to 85 wt%, and mixing to provide a slurry composition having a solids content of from 60 wt% to 80 wt%.
  • the intermediate slurry composition is prepared by adding dispersing medium to the composition of step a. and mixing.
  • the cathode active material and conductive agent may be dry mixed.
  • the conductive agent when present is typically provided as a dispersion to aid in its processing.
  • the first mixing step may therefore have small amounts of dispersing medium, which is typically water.
  • acid and/or alkali metal salt of acidic polysaccharide may also be provided as dispersions, to aid in their processing.
  • the binder polymer is added as a dispersion to aid in its mixing into the composition.
  • the composition has a pH of from 5 to 8 after step a., for instance from about pH 6 to 7.
  • dispersing medium is typically done stepwise, but may be continuous.
  • the overall process is typically done at a rate which ensures even and thorough mixing of the dispersing medium into the composition.
  • the alkali metal salt of the acidic polysaccharide may begin to coat the cathode active material.
  • the pH of the composition after step b. is typically from pH 6 to 10, for instance from about pH 6 to 8 or from pH 6 to 7. In some embodiments, the pH of the composition after step b. may be 7 to 10, for example from pH 7.5 to 9, preferably from pH 8 to 9.
  • composition comprising cathode active material, acrylamide copolymer, an acid, an alkali metal salt of an acidic polysaccharide, optionally a conductive agent, and optionally a dispersing medium; 2. adding dispersing medium to the composition and mixing to provide a slurry composition having a solids content of from 60 wt% to 80 wt%.
  • Step 1 of the method comprises forming a mixture of cathode active material, acrylamide copolymer, (optional) conductive agent, acid and alkali metal salt of acidic polysaccharide. These agents may be combined in any order, and may be dry mixed.
  • step 1. comprises: forming a mixture of cathode active material and optional conductive agent; adding acrylamide copolymer, acid and alkali metal salt of acidic polysaccharide and mixing, optionally in the presence of a dispersing medium.
  • the cathode active material and conductive agent may be dry mixed.
  • the conductive agent when present is typically provided as a dispersion to aid in its processing.
  • the first mixing step may therefore have small amounts of dispersing medium, which is typically water.
  • acid and/or alkali metal salt of acidic polysaccharide may also be provided as dispersions, to aid in their processing.
  • the acrylamide copolymer is added as a dispersion to aid in its mixing into the composition.
  • step 1. typically comprises providing a composition comprising cathode active material, acrylamide copolymer, an acid, an alkali metal salt of an acidic polysaccharide, a dispersing medium, and optionally a conductive agent, said composition having above 85 wt% solid content.
  • the composition has a pH of from 5 to 8 after step a., for instance from about pH 6 to 7.
  • Step 2. comprises adding dispersing medium and mixing to decrease the solids content of the composition. During this step, the composition transitions through a clay-like solid to a free-flowing slurry having a solids content of from 60 to 80 wt%.
  • dispersing medium is typically done stepwise but may be continuous.
  • the overall process is typically done at a rate which ensures even and thorough mixing of the dispersing medium into the composition.
  • the alkali metal salt of the acidic polysaccharide may begin to coat the cathode active material.
  • the pH of the slurry composition after step 2. is typically from pH 6 to 10, for instance from pH 7 to 10, for example from pH 7.5 to 9, preferably from pH 8 to 9.
  • the binder polymer is an acrylic polymer
  • the method of the disclosure comprises the steps of: i. providing a composition comprising cathode active material, an acid, an alkali metal salt of an acidic polysaccharide, optionally a conductive agent, and optionally a dispersing medium; ii. adding dispersing medium to the composition and mixing to provide an intermediate slurry composition having a solids content of from 65 wt% to 85 wt%; and iii. adding an acrylic polymer and optionally dispersing medium to the intermediate slurry composition to provide a slurry composition having a solids content of from 60 wt% to 80 wt%.
  • Step i. of the method comprises forming a mixture of cathode active material, (optional) conductive agent, acid and alkali metal salt of acidic polysaccharide. These agents may be combined in any order, and may be dry mixed.
  • step i. comprises: forming a mixture of cathode active material and optional conductive agent; adding acid and alkali metal salt of acidic polysaccharide and mixing, optionally in the presence of a dispersing medium.
  • the cathode active material and conductive agent may be dry mixed.
  • the conductive agent when present is typically provided as a dispersion to aid in its processing.
  • the first mixing step may therefore have small amounts of dispersing medium, which is typically water.
  • step i. typically comprises providing a composition comprising cathode active material, an acid, an alkali metal salt of an acidic polysaccharide, a dispersing medium, and optionally a conductive agent, said composition having above 85 wt% solid content.
  • the composition has a pH of from 5 to 8 after step i., for instance from about pH 6 to 7.
  • Step ii comprises adding dispersing medium and mixing to decrease the solids content of the composition. During this step, the composition transitions through a clay-like solid to a free-flowing slurry.
  • dispersing medium is typically done stepwise, but may be continuous.
  • the overall process is typically done at a rate which ensures even and thorough mixing of the dispersing medium into the composition.
  • the alkali metal salt of the acidic polysaccharide may begin to coat the cathode active material.
  • the pH of the composition after step ii. is typically from pH 6 to 8, for instance from about pH 6 to 7.
  • Step iii. comprises adding the acrylic polymer typically with dispersing medium under mixing to provide the final slurry composition.
  • the acrylic polymer is added as a dispersion to aid in its mixing into the composition.
  • the pH of the slurry composition after step c. is typically from pH 6 to 10, for instance from pH 7 to 10, for example from pH 7.5 to 9, preferably from pH 8 to 9.
  • Adding the acrylic polymer too early in the process may lead to poor coating properties and formation of bubbles. Additionally, if the acrylic polymer is exposed to very low pH compositions, it may precipitate resulting in poor integration into the slurry composition.
  • the slurry composition comprises at least 90 wt% cathode active material, based on the total weight of the dry composition (i.e. the slurry composition excluding the dispersing medium, or alternatively the electrode).
  • the slurry composition may be used to form a cathode in a cell using standard methodologies, such as by slot-die coating a conductive foil and drying the composition to form a cathode.
  • the cathode according to the disclosure i.e. those containing the binder system of the disclosure, or formed from the slurry composition of the disclosure) display improved cycle life, good flexibility, and good adhesion to the conductive foil.
  • the cell of the disclosure may comprise a first and second conductive foil. Said current foils act as one of a cathode or an anode current collector.
  • the first conductive foil acts as the cathode current collector and the second conductive foil acts as the anode current collector.
  • the cathode current collector may comprise a metal, such as aluminium, nickel or stainless steel.
  • the positive current collector is an aluminium foil.
  • the anode current collector may comprise a metal, such as copper, nickel or stainless steel.
  • the negative current collector is a copper foil.
  • the conductive foil may have a coating such as a carbon coating, which can improve conductivity at the interface with the electrode active material.
  • the coating may also improve the peel strength (or adhesive properties) of layers coated thereon, reducing delamination of the electrode.
  • the cell may comprise an anode.
  • the anode may comprise an anode active material, such as metallic lithium, lithium/aluminium alloys, lithium/tin alloys, carbon, graphite, black lead, silicon, silicon/silicon composite, or a combination thereof.
  • the anode may further comprise a conductive agent and a binder.
  • the role of the anode active material is to reversibly bind the lithium.
  • the mechanism of binding will vary, and may be by intercalation/deintercalation (for instance with graphite), alloying/dealloying (for instance with silicon), or by plating/stripping (for instance with metallic lithium), or combinations thereof.
  • the anode comprises carbon and/or silicon.
  • Suitable anode active materials are selected from silicon, SiOx, silicon-carbon composites, prelithiated silicon or its composites and oxides.
  • the anode active material, conductive agent and binder may be coated on the second conductive foil (e.g. the copper foil).
  • the anode active material, conductive agent and binder may be coated on the inner and outer sides of the second conductive foil.
  • the cell of the disclosure further comprises an electrolyte.
  • the electrolyte used in the cell according to the present disclosure may be a liquid electrolyte comprising at least one salt (particularly at least one lithium salt) and at least one or more solvents selected from the group consisting of carbonate solvents and their fluorinated equivalents, diCl-4 ethers and their fluorinated equivalents and ionic liquids.
  • the electrolyte may be a solid electrolyte.
  • the lithium salt is preferably one or more selected from the group consisting of lithium hexafluorophosphate (LiPFe), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium
  • LiFTFSI fluorosulfonyl(trifluoromethanesulfonyl)imide
  • LiBETI lithium bis(pentafluoroethanesulfonyl)imide
  • LiPTFSI lithium trifluoromethanesulfonate
  • LiBOB lithium bis(oxalato)borate
  • LiDFOB lithium difluoro(oxalato)borate
  • LiDFOP lithium difluorobis(oxalato)phosphate
  • LiTFOP lithium tetrafluoro(oxalato)phosphate
  • IJBF4 lithium tetrafluoroborate
  • LiNCh lithium 2-trifluoromethyl-4,5-dicyanoimidazole
  • the solvent is selected from the group consisting of 1,2- dimethoxyethane (DME), N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (PYR13-FSI), N-propyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR13-TFSI), 1-butyl-l-methylpyrrolidinium bis(fluorosulfonyl)imide (PYR14-FSI), 1- butyl-l-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14-TFSI), 1- ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIM-FSI), l-ethyl-3- methylimidazolium bis(trifluoromethanesulfonyl)imide (EMIM-TFSI), di
  • the cell of the disclosure may comprise one or more separators disposed between the anode and the cathode.
  • the function of these separators is to prevent electrical contact between the cathode and the anode, whilst allowing the passage of ions.
  • Any separator suitable for use in a cylindrical/pouch/prismatic/coin(e.g. lithium-ion) cell may be used.
  • the separator may be made from a material such as glass fiber, polyester, Teflon, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), or a combination thereof, and may be in the form of a nonwoven fabric or a woven fabric.
  • a material such as glass fiber, polyester, Teflon, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), or a combination thereof, and may be in the form of a nonwoven fabric or a woven fabric.
  • the separator is an integrated separator.
  • the separator may be integrated with a composite electrode to form an integrated electrode-separator (IES).
  • IES integrated electrode-separator
  • the cell may include at least a cathode, an anode and an electrolyte, wherein the cathode comprises the binder system described herein.
  • the cell may include a separator.
  • the cell may be a cylindrical, prismatic, coin cell or pouch cell.
  • the cell may be a lithium-ion cell, such as a secondary lithium-ion cell.
  • the cell is a cylindrical secondary lithium-ion cell.
  • the cell may be combined with other cells to form a battery system (i.e. an array of cells).
  • the disclosure also relates to a vehicle comprising the cell and/or battery system of the disclosure.
  • vehicle is preferably an electric vehicle, such as a car, truck, bus, scooter, motorbike, bicycle, boat, plane or the like, preferably a car, truck or bus.
  • Example 1 A coin half-cell was prepared using a cathode formed from the slurry composition described herein. Slurry compositions were prepared using either water or NMP as dispersing media. A nickel rich NMC cathode active material was used as cathode active material. Malonic acid was used as the acid, and sodium alginate was used as the alkali metal salt of an acidic polysaccharide in the binder system. An acrylamide copolymer was used as the binder polymer.
  • the slurry composition comprised from about 90 to 98 wt% cathode active material, from about 0 to about 3 wt% conductive agent, from about 0.05 to 2 wt% acid or salt thereof, from about 0.1 to 3 wt% alkali metal salt of an acidic polysaccharide and from about 1 to 5 wt% acrylamide copolymer, based on the total weight of the dry composition (i.e. the slurry composition excluding the dispersing medium, or alternatively the electrode).
  • the anode used in the coin half-cell was lithium.
  • a ceramic-coated separator was used to separate the anode and cathode.
  • Stainless steel was used for the positive and negative casing elements of the cell.
  • the formation cycle results of the coin half-cell prepared using the water-based slurry composition were similar to the coin half-cell prepared using an NMP-based slurry composition (Table 1).
  • the voltage vs. capacity for the formation cycle of the coin half-cell is shown in Figure 1.
  • the Figure shows a difference in properties of the electrodes formed from either water or NMP during the charge cycle, with similar properties on the discharge cycle.
  • the direct current internal resistance (DCIR) was measured at 100% state of charge. A low value indicates that a large current can be delivered with minimal voltage drop.
  • the DCIR results of the coin half-cell prepared using the water-based slurry composition were similar to the coin half-cell prepared using an NMP-based slurry composition (Table 2).
  • a coin half-cell was prepared using a cathode formed from the slurry composition described herein.
  • Slurry compositions were prepared using either water or NMP as dispersing media. Malonic acid was used as the acid and sodium alginate was used as the alkali metal salt of an acidic polysaccharide in the binder system. An acrylic polymer was used as the binder polymer.
  • the slurry composition comprised from about 95 to 99 wt% cathode active material, from about 0 to about 3 wt% conductive agent, from about 0.4 to 5 wt% acid or salt thereof, from about 0.1 to 3 wt% alkali metal salt of an acidic polysaccharide and from about 0.4 to 5 wt% acrylic polymer, based on the total weight of the dry composition (i.e. the slurry composition excluding the dispersing medium, or alternatively the electrode).
  • the anode used in the coin half-cell was lithium.
  • a ceramic-coated separator from celgard was used to separate the anode and cathode.
  • Stainless steel was used for the positive and negative casing elements of the cell.
  • the formation cycle results of the coin half-cell prepared using the water-based slurry composition were similar to the coin half-cell prepared using an NMP-based slurry composition (Table 3).
  • the voltage vs. capacity for the formation cycle of the coin half-cell is shown in Figure 2.
  • the Figure shows a difference in properties of the electrodes formed from either water or NMP during the charge cycle, with merged properties on the discharge cycle.
  • the coin half-cell prepared using the water-based cathode slurry composition displayed better capacity retention after 50 cycles (1C/1C) compared to the coin half-cell prepared using the NMP-based cathode slurry composition (Table 4).
  • a cathode was prepared from the slurry composition described herein using water as dispersing media.
  • a high-nickel NMC cathode active material was used as cathode active material comprising from about 90 to 95 mol% Ni, from about 1 to 5 mol% Mn and from about 0 to 5 mol% Co, based on the total amount of non-lithium metals in the cathode active material.
  • Malonic acid was used as the acid, and sodium alginate was used as the alkali metal salt of an acidic polysaccharide in the binder system.
  • An acrylamide copolymer was used as the binder polymer.
  • the slurry composition comprised from about 90 to 98 wt% cathode active material, from about 0 to about 3 wt% conductive agent, from about 0.05 to 2 wt% acid or salt thereof, from about 0.1 to 3 wt% alkali metal salt of an acidic polysaccharide and from about 1 to 5 wt% acrylamide copolymer, based on the total weight of the dry composition (i.e. the slurry composition excluding the dispersing medium, or alternatively the electrode).
  • a cathode was prepared from the slurry composition described herein using water as dispersing media.
  • a high-nickel NiMP cathode active material was used as cathode active material comprising from about 85 to 95 mol% Ni and from about 1 to 20 mol% Mn, based on the total amount of non-lithium metals in the cathode active material.
  • Malonic acid was used as the acid
  • sodium alginate was used as the alkali metal salt of an acidic polysaccharide in the binder system.
  • An acrylamide copolymer was used as the binder polymer.
  • the slurry composition comprised from about 90 to 98 wt% cathode active material, from about 0 to about 3 wt% conductive agent, from about 0.05 to 2 wt% acid or salt thereof, from about 0.1 to 3 wt% alkali metal salt of an acidic polysaccharide and from about 1 to 5 wt% acrylamide copolymer, based on the total weight of the dry composition (i.e. the slurry composition excluding the dispersing medium, or alternatively the electrode).
  • a cathode was prepared from a slurry composition described herein using the same method as Example 2 and with water as dispersing media, but without any binder (i.e. acrylic) polymer.
  • the peel strength was measured using the peel strength test according to the method as described herein.
  • a slurry composition was prepared according to Example 2 and using water as the dispersing media.
  • a comparative slurry composition was prepared using a conventional binder system, comprising an acrylic polymer and carboxymethyl cellulose as binder, but without an alkali metal salt of an acidic polysaccharide or an acid.
  • the pH of the slurry compositions was measured over a period of 0 to 7 days. The results are plotted in Figures 5 and 6. It is clearly visible that the comparative slurry composition without an alkali metal salt of an acidic polysaccharide or acid reaches a pH greater than the limit for Al corrosion (10.5) within 1 day of preparation, whereas the slurry composition of the disclosure has a pH below this limit for up to 6 days after preparation.
  • Slurry compositions were prepared using according to Example 2 using either water (water-based) or NMP (NMP-based) as dispersing media.
  • the viscosity of the slurry compositions was measured using a standard shear rate sweep test and the results are plotted in Figure 7. There are clear differences in both the low shear and high shear regions, indicating a difference in the rheological behaviour of the slurry compositions.
  • the higher viscosity for the waterbased composition in the low shear region compared to the NMP-based composition may indicate a yield stress type behaviour and/or greater stability during storage (for example, due to sedimentation).
  • the lower viscosity for the water-based composition in the high shear region compared to the NMP-based composition may indicate more favourable properties for manufacturing of the cathode (e.g. less force required for screen printing).
  • Cells were prepared using a cathode formed from the slurry compositions according to Example 2 using either water (water-based) or NMP (NMP-based) as dispersing media. Gas analysis is carried out on the cell using online electrochemical mass spectroscopy (OEMS).
  • OEMS online electrochemical mass spectroscopy
  • a coin cell was prepared with a similar design to Example 2, but using graphite as the anode. The cell showed 80% capacity retention after 800 cycles.
  • the term “comprises” will take its usual meaning in the art, namely indicating that the component includes but is not limited to the relevant features (i.e. including, among other things). As such, the term “comprises” will include references to the component consisting essentially of the relevant substance(s).

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Abstract

La présente divulgation concerne un système de liant destiné à une électrode, une composition de suspension comprenant ladite composition de liant destinée à être utilisée dans la formation d'électrodes, ainsi que des électrodes formées à partir de celle-ci. Le système de liant contient un polymère liant, un sel de métal alcalin d'un polysaccharide acide, et un acide ou un sel de celui-ci. Les électrodes formées à l'aide du système de liant présentent une excellente durée de vie de cycle, une bonne flexibilité et une bonne adhérence.
PCT/EP2023/083862 2022-12-05 2023-12-01 Composition de suspension pour cathode aqueuse destinée à une cathode de batterie Ceased WO2024120983A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
SE2251414A SE546429C2 (en) 2022-12-05 2022-12-05 Aqueous slurry composition comprising polyacrylate and alginic acid for cell cathode
SE2251414-5 2022-12-05
SE2350467-3 2023-04-19
SE2350467A SE547030C2 (en) 2023-04-19 2023-04-19 Aqueous cathode slurry composition for cell cathode

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3073555A2 (fr) * 2015-03-26 2016-09-28 Automotive Energy Supply Corporation Batterie secondaire à électrolyte non aqueux
EP3758116A1 (fr) * 2018-02-19 2020-12-30 Zeon Corporation Composition de liant pour électrode de pile rechargeable à électrolyte non aqueux, composition de suspension épaisse pour électrode de pile rechargeable à électrolyte non aqueux, électrode pour pile rechargeable à électrolyte non aqueux, et pile rechargeable à électrolyte non aqueux
CN112968177A (zh) * 2021-03-01 2021-06-15 广州鹏辉能源科技股份有限公司 水基正极浆料组合物、水基正极浆料及制备方法、正极片、锂离子电池和用电设备

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3073555A2 (fr) * 2015-03-26 2016-09-28 Automotive Energy Supply Corporation Batterie secondaire à électrolyte non aqueux
EP3758116A1 (fr) * 2018-02-19 2020-12-30 Zeon Corporation Composition de liant pour électrode de pile rechargeable à électrolyte non aqueux, composition de suspension épaisse pour électrode de pile rechargeable à électrolyte non aqueux, électrode pour pile rechargeable à électrolyte non aqueux, et pile rechargeable à électrolyte non aqueux
CN112968177A (zh) * 2021-03-01 2021-06-15 广州鹏辉能源科技股份有限公司 水基正极浆料组合物、水基正极浆料及制备方法、正极片、锂离子电池和用电设备

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