WO2021153401A1 - リチウムイオン電池 - Google Patents
リチウムイオン電池 Download PDFInfo
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- WO2021153401A1 WO2021153401A1 PCT/JP2021/001964 JP2021001964W WO2021153401A1 WO 2021153401 A1 WO2021153401 A1 WO 2021153401A1 JP 2021001964 W JP2021001964 W JP 2021001964W WO 2021153401 A1 WO2021153401 A1 WO 2021153401A1
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- negative electrode
- active material
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- binder
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- 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
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/387—Tin or alloys based on tin
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- 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
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- 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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/134—Electrodes based on metals, Si or alloys
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- 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
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
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- 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
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- 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
- H01M2004/027—Negative electrodes
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- 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
- a positive electrode having a positive electrode mixture layer containing a positive electrode active material, a negative electrode having a negative electrode mixture layer containing a negative electrode active material, and charging / discharging are performed by moving lithium ions between the positive electrode and the negative electrode.
- a positive electrode having a positive electrode mixture layer containing a positive electrode active material, a negative electrode having a negative electrode mixture layer containing a negative electrode active material, and charging / discharging are performed by moving lithium ions between the positive electrode and the negative electrode.
- lithium-ion batteries Regarding lithium-ion batteries.
- Lithium-ion batteries in which charging and discharging are performed by moving lithium ions (Li ions) between the negative electrode and the positive electrode, are widely used.
- a graphite-based material is often used as the negative electrode active material of the negative electrode mixture layer in this lithium ion battery.
- the graphite-based negative electrode active material may be used together with Si, in which case the volume change during charging and discharging is large, the capacity retention characteristics are likely to deteriorate, and the cost is relatively high.
- Patent Document 1 describes that an alloy having a La 3 Co 2 Sn 7 type crystal structure is used as the negative electrode active material.
- Patent Document 2 describes that the content of the binder is 0.5% by mass or more and 5.0% by mass.
- Patent Document 1 polyvinylidene fluoride (PVDF) is used as the binder, but as a result of the experiment, when La 3 Ni 2 Sn 7 is used as the active material and PVDF is used as the binder, the negative electrode is caused by the reaction of both. It was found that the mixture slurry used for forming the mixture layer gels, which makes coating difficult. In order to reduce the reactivity of La 3 Ni 2 Sn 7 and PVDF and enable coating, it is necessary to increase the particle size of the negative electrode active material. However, when the particle size of the negative electrode active material is increased, the reactivity between the negative electrode active material and Li decreases, and the capacity tends to decrease.
- PVDF polyvinylidene fluoride
- lithium ions move between a positive electrode having a positive electrode mixture layer containing a positive electrode active material, a negative electrode having a negative electrode mixture layer containing a negative electrode active material, and the positive electrode and the negative electrode.
- the negative electrode mixture is a lithium ion battery that is charged and discharged by the general formula M 3 Me 2 X 7 (in the formula, M contains at least one of La and Ca, and Me is Mn, Ni, Fe. , Co, and X contains at least one of Ge, Si, Sn, and Al).
- the ratio of the binder in the agent layer is 0.5% by mass or more and 7.0% by mass or less.
- the negative electrode active material a negative electrode active material represented by the general formula M 3 Me 2 X 7 and a binder containing a cyano group are used, and the amount of the binder added is 0.5% by mass or more 7 It should be 0.0% by mass or less.
- the negative electrode mixture layer can be coated, and the amount of the binder added can be relatively small to suppress the decrease in volume.
- FIG. 2 is a graph showing the initial efficiency of Examples 1 to 5 and Comparative Example 1. It is a graph about the initial discharge capacity about Examples 1-5.
- the negative electrode mixture slurry gels, which makes it difficult to coat the negative electrode mixture layer. Further, if gelation is suppressed by increasing the particle size of the binder, the battery reaction may be inhibited.
- gelation of the negative electrode mixture slurry is suppressed by using a binder containing a cyano group, for example, polyacrylonitrile (PAN).
- PAN polyacrylonitrile
- the amount of the binder added to the negative electrode mixture layer can be 2.0% by mass or more and 5.0% by mass or less.
- FIG. 1 is a vertical cross-sectional view of a cylindrical secondary battery 10 which is an example of an embodiment.
- the electrode body 14 and the non-aqueous electrolyte are housed in the exterior body 15.
- the electrode body 14 has a winding structure in which the positive electrode 11 and the negative electrode 12 are wound around the separator 13.
- the non-aqueous solvent (organic solvent) of the non-aqueous electrolyte carbonates, lactones, ethers, ketones, esters and the like can be used, and two or more of these solvents can be mixed and used. ..
- a mixed solvent containing a cyclic carbonate and a chain carbonate For example, ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC) and the like can be used as the cyclic carbonate, and dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (diethyl carbonate) can be used as the chain carbonate. DEC) and the like can be used.
- DEC dimethyl carbonate
- EMC ethyl methyl carbonate
- diethyl carbonate diethyl carbonate
- electrolyte salt of the non-aqueous electrolyte LiPF 6 , LiBF 4 , LiCF 3 SO 3, etc. and a mixture thereof can be used.
- the amount of the electrolyte salt dissolved in the non-aqueous solvent can be, for example, 0.5 to 2.0 mol / L.
- the sealing body 16 side will be referred to as “top” and the bottom side of the exterior body 15 will be referred to as “bottom”.
- the inside of the secondary battery 10 is sealed by closing the opening end of the exterior body 15 with the sealing body 16.
- Insulating plates 17 and 18 are provided above and below the electrode body 14, respectively.
- the positive electrode lead 19 extends upward through the through hole of the insulating plate 17 and is welded to the lower surface of the filter 22 which is the bottom plate of the sealing body 16.
- the cap 26, which is the top plate of the sealing body 16 electrically connected to the filter 22, serves as the positive electrode terminal.
- the negative electrode lead 20 extends to the bottom side of the exterior body 15 through the through hole of the insulating plate 18 and is welded to the inner surface of the bottom portion of the exterior body 15.
- the exterior body 15 serves as a negative electrode terminal.
- the negative electrode lead 20 passes through the outside of the insulating plate 18 and extends to the bottom side of the exterior body 15 and is welded to the inner surface of the bottom portion of the exterior body 15.
- the exterior body 15 is, for example, a bottomed cylindrical metal exterior can.
- a gasket 27 is provided between the exterior body 15 and the sealing body 16 to ensure the internal airtightness of the secondary battery 10.
- the exterior body 15 has a grooved portion 21 that supports the sealing body 16 and is formed by pressing, for example, a side surface portion from the outside.
- the grooved portion 21 is preferably formed in an annular shape along the circumferential direction of the exterior body 15, and the sealing body 16 is supported on the upper surface thereof via the gasket 27.
- the sealing body 16 has a filter 22, a lower valve body 23, an insulating member 24, an upper valve body 25, and a cap 26, which are laminated in order from the electrode body 14 side.
- Each member constituting the sealing body 16 has, for example, a disk shape or a ring shape, and each member except the insulating member 24 is electrically connected to each other.
- the lower valve body 23 and the upper valve body 25 are connected to each other at their central portions, and an insulating member 24 is interposed between the peripheral portions thereof.
- the positive electrode 11, the negative electrode 12, and the separator 13 constituting the electrode body 14 will be described, and in particular, the negative electrode active material constituting the negative electrode 12 will be described.
- the positive electrode 11 has a positive electrode core body and a positive electrode mixture layer provided on the surface of the positive electrode core body.
- a metal foil stable in the potential range of the positive electrode 11 such as aluminum, a film in which the metal is arranged on the surface layer, or the like can be used.
- the thickness of the positive electrode core is, for example, 10 ⁇ m to 30 ⁇ m.
- the positive electrode mixture layer contains a positive electrode active material, a binder, and a conductive material, and is preferably provided on both sides of the positive electrode core body excluding the portion to which the positive electrode lead 19 is connected.
- a positive electrode mixture slurry containing a positive electrode active material, a binder, a conductive material, and the like is applied to the surface of a positive electrode core, the coating film is dried, and then compressed to form a positive electrode mixture layer. It can be manufactured by forming it on both sides of the core body.
- the positive electrode active material contains lithium transition metal oxide as a main component.
- the positive electrode active material may be substantially composed of only lithium transition metal oxide, and is one in which inorganic compound particles such as aluminum oxide and lanthanoid-containing compound are adhered to the particle surface of the lithium transition metal oxide. May be good.
- One type of lithium transition metal oxide may be used, or two or more types may be used in combination.
- Metal elements contained in the lithium transition metal oxide include nickel (Ni), cobalt (Co), manganese (Mn), aluminum (Al), boron (B), magnesium (Mg), tantalum (Ti), and vanadium. (V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), gallium (Ga), strontium (Sr), zirconium (Zr), niobium (Nb), indium (In), tin (Sn), tantalum (Ta), tungsten (W) and the like can be mentioned.
- lithium transition metal oxide is the general formula: Li ⁇ Ni x M (1-x) O 2 (0.1 ⁇ ⁇ ⁇ 1.2, 0.3 ⁇ x ⁇ 1, where M is Co, Mn. , Containing at least one of Al).
- M is Co, Mn. , Containing at least one of Al.
- NCA in which a part of nickel is replaced with cobalt and aluminum is added is used.
- Examples of the conductive material contained in the positive electrode mixture layer include carbon materials such as carbon black, acetylene black, ketjen black, carbon nanotubes, carbon nanofibers, and graphite.
- Examples of the binder contained in the positive electrode mixture layer include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyimide resins, acrylic resins, and polyolefin resins. .. These resins may be used in combination with cellulose derivatives such as carboxymethyl cellulose (CMC) or salts thereof, polyethylene oxide (PEO) and the like.
- the negative electrode 12 has a negative electrode core body and a negative electrode mixture layer provided on the surface of the negative electrode core body.
- a metal foil stable in the potential range of the negative electrode 12 such as copper, a film in which the metal is arranged on the surface layer, or the like can be used.
- the thickness of the negative electrode core is, for example, 5 ⁇ m to 15 ⁇ m.
- the negative electrode mixture layer contains a negative electrode active material and a binder, and is preferably provided on both sides of the negative electrode core body excluding the portion to which the negative electrode lead 20 is connected, for example.
- a negative electrode mixture slurry containing a negative electrode active material and a binder is applied to the surface of the negative electrode core body, the coating film is dried, and then compressed to form a negative electrode mixture layer on both sides of the negative electrode core body. It can be produced by forming in. Further, a conductive material may be added to the negative electrode mixture slurry. The conductive material can make the conductive path uniform. Further, the negative electrode mixture layer may contain a conductive material such as acetylene black, similarly to the positive electrode mixture layer.
- the negative electrode mixture layer contains at least one of the general formula M 3 Me 2 X 7 (in the formula, M is La and Ca, and Me is at least one of Mn, Ni, Fe and Co) as the negative electrode active material.
- X includes an intermetallic compound (alloy of M 3 Me 2 X 7 type crystal) represented by Ge, Si, Sn, Al).
- suitable negative electrode active materials include La 3 Co 2 Sn 7 , La 3 Mn 2 Sn 7 , and La 3 Ni 2 Sn 7 . Among them, from the viewpoint of increasing the capacity, La 3 Co 2 Sn 7 or La 3 Ni 2 Sn 7 is preferable, and La 3 Ni 2 Sn 7 is particularly preferable.
- the particle size of the negative electrode active material M 3 Me 2 X 7 is preferably 1 to 30 ⁇ m, more preferably 2 to 20 ⁇ m, and particularly preferably 2 to 10 ⁇ m. If the particle size of M 3 Me 2 X 7 becomes too large, the reactivity with Li decreases, the contact area between particles becomes small, and the resistance increases. On the other hand, if the particle size becomes too small, it is assumed that the packing density of the negative electrode active material decreases and the capacity decreases.
- the average particle size of M 3 Me 2 X 7 is, for example, 3 to 15 ⁇ m, or 5 to 10 ⁇ m.
- the particle size of the M 3 Me 2 X 7 is measured as the diameter of the circumscribed circle of the M 3 Me 2 X 7 particles in the cross-sectional image of the negative electrode mixture layer observed by a scanning electron microscope (SEM).
- the average particle size is calculated by averaging the particle sizes of 100 arbitrary particles.
- the intermetallic compound represented by M 3 Me 2 X 7 can be formed by arc melting, and it is preferable to anneal after arc melting. Further, M may be replaced with La in an amount of up to about 50%. For example, in the case of La in which about 40% is replaced with Ca, a large charge / discharge capacity (initial charge capacity 301 mAh / g, initial discharge capacity 223 mAh / g (1718 mAh / cc)) and a small volume change rate (0.5). % Or less) was obtained.
- the negative electrode active material may contain M 3 Me 2 X 7 as a main component (the component having the highest mass ratio) and may be substantially composed of only M 3 Me 2 X 7.
- the negative electrode active material may be used in combination with other active materials such as an intermetallic compound other than M 3 Me 2 X 7 , a carbon-based active material such as graphite, or a Si-based active material containing Si.
- the content of graphite may be 50 to 90% by mass with respect to the mass of the negative electrode active material.
- a compound containing a cyano group is used as the binder contained in the negative electrode mixture layer.
- the negative electrode active material when a commonly used binder such as polyvinylidene fluoride (PVDF) is used, the negative electrode mixture slurry gels and the slurry is coated.
- PVDF polyvinylidene fluoride
- the binder containing a cyano group improves the dispersibility of the negative electrode active material and suppresses gelation of the slurry.
- the binder containing a cyano group has a high affinity for M 3 Me 2 X 7 and functions sufficiently as a binder even in a small amount.
- the binder containing a cyano group examples include polyacrylonitrile (PAN), polymethacrylonitrile, poly- ⁇ -chloroacrylonitrile, poly- ⁇ -ethylacrylonitrile, and the like. Among them, PAN or polymethaclonitrile is preferable, and PAN is particularly preferable.
- the cyano group-containing binder is synthesized, for example, by polymerizing a cyano group-containing monomer having 5 or less carbon atoms, but contains a copolymerization component that does not contain a cyano group to the extent that the object of the present disclosure is not impaired. You may. Further, as the binder containing a cyano group, only one type may be used, or two or more types may be used in combination.
- the mass ratio of the binder containing a cyano group in the negative electrode mixture layer is 0.5% by mass to 7.0% by mass. If the content of the binder exceeds 7.0% by mass, the initial charge / discharge efficiency is greatly reduced. On the other hand, if the content of the binder is less than 0.5% by mass, it becomes difficult to secure the binding force between the active material particles and the binding force between the active material particles and the core body.
- An example of a suitable content is 1.0% by mass to 5.0% by mass, or 2.0% by mass to 3.0% by mass.
- the negative electrode mixture layer may contain a binder containing no cyano group as long as the object of the present disclosure is not impaired.
- a porous sheet having ion permeability and insulating property is used as the separator 13.
- the porous sheet include a microporous membrane, a woven fabric, a non-woven fabric and the like.
- olefin resin such as polyethylene and polypropylene, cellulose and the like are suitable.
- the separator 13 may have either a single-layer structure or a laminated structure.
- a heat-resistant layer containing a heat-resistant material may be formed on the surface of the separator 13. Examples of the heat-resistant material include polyamide resins such as aliphatic polyamides and aromatic polyamides (aramid), and polyimide resins such as polyamideimide and polyimide.
- Example 1 [Preparation of negative electrode] La 3 Ni 2 Sn 7 having a particle size of 2 to 20 ⁇ m was used as the negative electrode active material, polyacrylonitrile (PAN) was used as the binder, and acetylene black was used as the conductive material. The negative electrode active material, the binder, and the conductive material are mixed at a mass ratio of 96: 3: 1, and N-methyl-2-pyrrolidone (NMP) is used as a dispersion medium to prepare a negative electrode mixture slurry. Prepared. Next, a negative electrode mixture slurry was applied onto a negative electrode core made of copper foil, the coating film was dried and compressed, and then cut to a predetermined electrode size to obtain a negative electrode.
- NMP N-methyl-2-pyrrolidone
- the negative electrode and the positive electrode made of lithium metal foil were arranged to face each other via a separator to form an electrode body, and the electrode body was housed in a coin-shaped outer can. After injecting a predetermined non-aqueous electrolyte solution into the outer can, the outer can was sealed to obtain a coin-shaped test cell (non-aqueous electrolyte secondary battery).
- the test cell was the same as in Example 1 except that the amount of the binder added, the type of the binder, and the particle size of the negative electrode active material were changed as shown in Table 1.
- the binder polyimide (PI) was used instead of PAN in Comparative Example 2, and polyvinylidene fluoride (PVDF) was used instead of PAN in Comparative Example 3.
- Table 1 is a diagram showing the charge / discharge test results of Examples 1 to 5 and Comparative Examples 1 to 4.
- FIG. 2 is a graph showing the initial efficiency of Examples 1 to 5 and Comparative Example 1. As described above, in Comparative Example 1, the initial efficiency is much lower than that in Examples 1 to 5. It is considered that this is because the amount of the binder is too large to sufficiently transfer Li to the active material.
- FIG. 3 is a graph of the initial discharge capacity for Examples 1 to 5.
- the discharge capacity of Example 5 is smaller than that of Examples 1 to 4. Therefore, it can be seen that the amount of the binder is more preferably 1% by mass to 5% by mass than 1% by mass to 7% by mass.
- La 3 Ni 2 Sn 7 is used as the negative electrode active material
- PAN is used as the binder
- the amount of PAN is 1% by mass to 7% by mass (more preferably 1% by mass to 5% by mass). It has been found that a suitable non-aqueous electrolyte secondary battery can be obtained.
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Abstract
Description
リチウムイオン電池の負極材料は、高エネルギー密度、低膨張を満たす材料が好ましい。そこで、各種の研究開発が行われており、負極活物質として、La3Ni2Sn7などのM3Me2X7(M=La,Ca、Me=Mn,Ni,Fe,Co、X=Ge,Si,Sn,Al)で表される金属間化合物を用いることが提案されている。このような金属間化合物は、インターカレーション反応によりLiの吸蔵放出を行うため、低膨張率であり、長寿命化が図れると考えられる。
図1は、実施形態の一例である円筒型の二次電池10の縦方向断面図である。図1に示す二次電池10は、電極体14および非水電解質が外装体15に収容されている。電極体14は、正極11および負極12がセパレータ13を介して巻回されてなる巻回型の構造を有する。非水電解質の非水溶媒(有機溶媒)としては、カーボネート類、ラクトン類、エーテル類、ケトン類、エステル類等を用いることができ、これらの溶媒は2種以上を混合して用いることができる。2種以上の溶媒を混合して用いる場合、環状カーボネートと鎖状カーボネートを含む混合溶媒を用いることが好ましい。例えば、環状カーボネートとしてエチレンカーボネート(EC)、プロピレンカーボネート(PC)、ブチレンカーボネート(BC)等を用いることができ、鎖状カーボネートとしてジメチルカーボネート(DMC)、エチルメチルカーボネート(EMC)、およびジエチルカーボネート(DEC)等を用いることができる。非水電解質の電解質塩としては、LiPF6、LiBF4、LiCF3SO3等およびこれらの混合物を用いることができる。非水溶媒に対する電解質塩の溶解量は、例えば0.5~2.0mol/Lとすることができる。なお、以下では、説明の便宜上、封口体16側を「上」、外装体15の底部側を「下」として説明する。
正極11は、正極芯体と、正極芯体の表面に設けられた正極合剤層とを有する。正極芯体には、アルミニウムなどの正極11の電位範囲で安定な金属の箔、当該金属を表層に配置したフィルム等を用いることができる。正極芯体の厚みは、例えば10μm~30μmである。正極合剤層は、正極活物質、結着剤、および導電材を含み、正極リード19が接続される部分を除く正極芯体の両面に設けられることが好ましい。正極11は、例えば正極芯体の表面に正極活物質、結着剤、および導電材等を含む正極合剤スラリーを塗布し、塗膜を乾燥させた後、圧縮して正極合剤層を正極芯体の両面に形成することにより作製できる。
負極12は、負極芯体と、負極芯体の表面に設けられた負極合剤層とを有する。負極芯体には、銅などの負極12の電位範囲で安定な金属の箔、当該金属を表層に配置したフィルム等を用いることができる。負極芯体の厚みは、例えば5μm~15μmである。負極合剤層は、負極活物質および結着剤を含み、例えば負極リード20が接続される部分を除く負極芯体の両面に設けられることが好ましい。負極12は、例えば負極芯体の表面に負極活物質および結着剤等を含む負極合剤スラリーを塗布し、塗膜を乾燥させた後、圧縮して負極合剤層を負極芯体の両面に形成することにより作製できる。また、負極合剤スラリーに導電材を添加してもよい。導電材によって、導電パスを均一化することができる。また、負極合剤層には、正極合剤層と同様に、アセチレンブラック等の導電材が含まれていてもよい。
セパレータ13には、イオン透過性および絶縁性を有する多孔性シートが用いられる。多孔性シートの具体例としては、微多孔膜、織布、不織布等が挙げられる。セパレータ13の材質としては、ポリエチレン、ポリプロピレン等のオレフィン樹脂、セルロースなどが好適である。セパレータ13は、単層構造、積層構造のいずれであってもよい。セパレータ13の表面には、耐熱性材料を含む耐熱層が形成されていてもよい。耐熱性材料としては、脂肪族系ポリアミド、芳香族系ポリアミド(アラミド)等のポリアミド樹脂、ポリアミドイミド、ポリイミド等のポリイミド樹脂などが例示できる。
以下、実施例により本開示をさらに説明するが、本開示はこれらの実施例に限定されるものではない。
[負極の作製]
負極活物質として、粒子径2~20μmのLa3Ni2Sn7を、結着剤として、ポリアクリロニトリル(PAN)を、導電材として、アセチレンブラックをそれぞれ用いた。負極活物質と、結着剤とを、導電材とを、96:3:1の質量比で混合し、分散媒としてN-メチル-2-ピロリドン(NMP)を用いて、負極合剤スラリーを調製した。次に、銅箔からなる負極芯体上に負極合剤スラリーを塗布し、塗膜を乾燥、圧縮した後、所定の電極サイズに切断して負極を得た。
セパレータを介して上記負極とリチウム金属箔からなる正極を対向配置して電極体を構成し、コイン形の外装缶に電極体を収容した。外装缶に所定の非水電解液を注入した後、外装缶を封止してコイン形の試験セル(非水電解質二次電池)を得た。
得られた試験セルを、常温環境下、0.15Cの定電流で電池電圧4.5VまでCC充電した後、0.15Cの定電流で電池電圧2.5VまでCC放電を行った。この充放電サイクルを3回繰り返し、各サイクルにおいて充電容量および放電容量を測定した。評価結果は、負極活物質の粒径、負極合剤スラリーの塗工の可否、および結着剤の種類と添加量とともに、表1に示した。
負極合剤スラリーの調製において、表1に示すように結着剤の添加量、結着剤の種類、および負極活物質の粒径を変更したこと以外は、実施例1と同様にして試験セルを作製し、充放電試験を行った。なお、結着剤として、比較例2ではPANの代わりにポリイミド(PI)を用い、比較例3ではPANの代わりにポリフッ化ビニリデン(PVDF)を用いた。
表1は、実施例1~5および比較例1~4の充放電試験結果を示す図である。
11 正極
12 負極
13 セパレータ
14 電極体
15 外装体
16 封口体
17,18 絶縁板
19 正極リード
20 負極リード
21 溝入部
22 フィルタ
23 下弁体
24 絶縁部材
25 上弁体
26 キャップ
26a 開口部
27 ガスケット
Claims (4)
- 正極活物質を含む正極合剤層を有する正極と、負極活物質を含む負極合剤層を有する負極と、前記正極と前記負極間をリチウムイオンが移動することにより充放電が行われるリチウムイオン電池であって、
前記負極合剤層は、一般式M3Me2X7(式中、MはLa,Caの少なくとも1つを含み、MeはMn,Ni,Fe,Coの少なくとも1つを含み、XはGe,Si,Sn,Alの少なくとも1つを含む)で表される負極活物質と、
シアノ基を含有する結着剤と、
を含み、
前記負極合剤層における前記結着剤の比率が0.5質量%以上7.0質量%以下である、
リチウムイオン電池。 - 前記シアノ基を含有する結着剤はポリアクリロニトリルであり、
ポリアクリロニトリルの比率が1.0質量%以上5.0質量%以下である、
請求項1に記載のリチウムイオン電池。 - ポリアクリロニトリルの比率が2.0質量%以上3.0質量%以下である、
請求項2に記載のリチウムイオン電池。 - 前記一般式M3Me2X7での負極活物質は、La3Ni2Sn7である、
請求項1~3のいずれか1つに記載のリチウムイオン電池。
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| EP21747475.8A EP4099433A4 (en) | 2020-01-30 | 2021-01-21 | LITHIUM ION BATTERY |
| US17/794,076 US20230141498A1 (en) | 2020-01-30 | 2021-01-21 | Lithium ion battery |
| JP2021574685A JP7702660B2 (ja) | 2020-01-30 | 2021-01-21 | リチウムイオン電池 |
| CN202180010732.7A CN115023824B (zh) | 2020-01-30 | 2021-01-21 | 锂离子电池 |
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| US20140004412A1 (en) * | 2012-06-29 | 2014-01-02 | Semiconductor Energy Laboratory Co., Ltd. | Secondary battery |
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| WO2015177665A1 (en) * | 2014-05-23 | 2015-11-26 | Semiconductor Energy Laboratory Co., Ltd. | Negative electrode active material and power storage device |
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| JP2005310739A (ja) * | 2004-03-23 | 2005-11-04 | Toshiba Corp | 非水電解質二次電池 |
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| EP4099433A1 (en) | 2022-12-07 |
| US20230141498A1 (en) | 2023-05-11 |
| CN115023824A (zh) | 2022-09-06 |
| EP4099433A4 (en) | 2024-07-24 |
| CN115023824B (zh) | 2025-09-23 |
| JP7702660B2 (ja) | 2025-07-04 |
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