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  • C01B25/00—Phosphorus; Compounds thereof
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  • C01B25/45—Phosphates containing plural metal, or metal and ammonium
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  • C01G45/00—Compounds of manganese
  • C01G45/12—Complex oxides containing manganese and at least one other metal element
  • C01G45/1221—Manganates or manganites with trivalent manganese, tetravalent manganese or mixtures thereof
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  • C01G51/40—Complex oxides containing cobalt and at least one other metal element
  • C01G51/42—Complex oxides containing cobalt and at least one other metal element containing alkali metals, e.g. LiCoO2
  • C01G51/44—Complex oxides containing cobalt and at least one other metal element containing alkali metals, e.g. LiCoO2 containing manganese
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  • C01G53/00—Compounds of nickel
  • C01G53/40—Complex oxides containing nickel and at least one other metal element
  • C01G53/42—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2
  • C01G53/44—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2 containing manganese
• • 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
• • 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
  • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
• • H—ELECTRICITY
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  • 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
  • H01M4/362—Composites
  • H01M4/364—Composites as mixtures
• • 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
  • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
  • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
• • C—CHEMISTRY; METALLURGY
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  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G23/00—Compounds of titanium
  • C01G23/003—Titanates
• • C—CHEMISTRY; METALLURGY
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  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2002/00—Crystal-structural characteristics
  • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
  • C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/40—Electric properties
• • 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
  • H01M4/624—Electric conductive fillers
  • H01M4/625—Carbon or graphite
• • 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 embodiments of the present invention relate to lithium secondary batteries, more specifically, to a composite compound having a mixed crystalline structure that can be used as a cathode material for lithium secondary batteries.
• Lithium secondary batteries are widely used in various devices such laptops, cameras, camcorders, PDAs, cell phones, iPods and other portable electronic devices. These batteries are also growing in popularity for defense, automotive and aerospace applications because of their high energy density.
• Lithium phosphate-based cathode materials for secondary battery have long been known in the battery industry. People have used metal intercalation compound to improve the electrical property of lithium phosphate.
• One popular intercalation compound is lithium iron phosphate (LiFePO 4 ). Because of its non-toxicity, excellent thermal stability, safety characteristics and good electrochemical performance, there is a growing demand for rechargeable lithium secondary batteries with LiFePO 4 as the cathode material.
• LiFePO 4 has its problems as a cathode material, however. Compared with other cathode materials such as lithium cobaltate, lithium nicklate, and lithium magnate, LiFePO 4 has much lower conductance and electrical density. The current invention solves the problem by producing a mixed crystal structure to significantly enhance the electrical properties of LiFePO 4 .
• a mixed crystal can sometimes be referred to as a solid solution. It is a crystal containing a second constituent, which fits into and is distributed in the lattice of the host crystal. See IUPAC Compendium of Chemical Terminology 2nd Edition (1997). Mixed crystals have been used in semiconductors for enhancing light output in light emitting diodes (LEDs). They have also been used to produce sodium-based electrolyte for galvanic elements.
• the current invention is the first time that a mixed crystal has been successfully prepared for lithium metal intercalation compounds such as LiFePO 4 . It is also the first time that a mixed crystalline structure has been used as a cathode material for lithium secondary batteries.
• the new cathode material disclosed in the present invention has significantly better electrical properties than traditional LiFePO 4 cathode materials.
• a first embodiment of the present invention discloses a substance comprising at least one lithium compound and at least one metal compound, wherein the metal compound is distributed into the lithium compound to form a composite compound with enhanced electrical properties.
• the composite compound has a mixed crystalline structure.
• the lithium compound is a metal intercalation compound that has the general formula LiM 3 N b XO c , wherein M is a first-row transition metal including Fe, Mn, Ni, V, Co and Ti; N is a metal selected from the group Fe, Mn, Ni, V, Co, Ti, Mg, Ca, Cu, Nb, Zr and rare-earth metals; X is selected from elements P, Si, S, V and Ge; and a, b and c have respective values that would render said metal intercalation compound charge-neutral.
• M is a first-row transition metal including Fe, Mn, Ni, V, Co and Ti
• N is a metal selected from the group Fe, Mn, Ni, V, Co, Ti, Mg, Ca, Cu, Nb, Zr and rare-earth metals
• X is selected from elements P, Si, S, V and Ge; and a, b and c have respective values that would render said metal intercalation compound charge-neutral.
• the metal compound has the general formula M c N d , wherein M is metal selected from IA 1 IIA, IMA, IVA, VA, 1MB, IVB and VB groups in the periodic table; N is selected from O, N, H, S, SO 4 , PO 4 , OH, Cl, F; and 0 ⁇ c ⁇ 4 and 0 ⁇ d ⁇ 6.
• the metal compounds may include one or more members selected from the group consisting of MgO, SrO, AI 2 O 3 , SnO 2 , Sb 2 O 3 , Y 2 O 3 , TiO 2 and V 2 O 5 .
• the lithium compound has the general formula LiM a N b XOc, wherein: M is a first-row transition metal including Fe, Mn, Ni, V, Co and Ti; N is a metal selected from the group Fe, Mn, Ni, V, Co, Ti, Mg, Ca, Cu, Nb, Zr and rare-earth metals; X is selected from elements P, Si, S, V and Ge; and a, b and c have respective values that would render said lithium compound charge-neutral.
• M is a first-row transition metal including Fe, Mn, Ni, V, Co and Ti
• N is a metal selected from the group Fe, Mn, Ni, V, Co, Ti, Mg, Ca, Cu, Nb, Zr and rare-earth metals
• X is selected from elements P, Si, S, V and Ge; and a, b and c have respective values that would render said lithium compound charge-neutral.
• the lithium compound has the general formula Li a Ai -y B y (XO 4 )b, wherein: A is a first-row transition metal including Fe, Mn, Ni, V, Co and Ti; B is a metal selected from the group Fe, Mn, Ni, V, Co, Ti, Mg, Ca, Cu, Nb, Zr and rare-earth metals; X is selected from elements P, Si, S, V and Ge; and 0 ⁇ a ⁇ 1 , O ⁇ y ⁇ O.5 and 0 ⁇ b ⁇ 1.
• a second embodiment of the invention calls for a mixed crystal compound with the general formula LiaAi -y By(XO 4 )b/McNd, wherein: A is a first-row transition metal including Fe, Mn, Ni, V, Co and Ti; B is a metal selected from the group Fe, Mn, Ni, V, Co, Ti, Mg, Ca, Cu, Nb, Zr and rare-earth metals; X is selected from elements P, Si, S, V and Ge; M is metal selected from groups IA , MA, IMA, IVA, VA, IMB, IVB and VB of the periodic table; N is selected from O, N, H, S, SO 4 , PO 4 , OH, Cl, F; and wherein 0 ⁇ a ⁇ 1 , O ⁇ y ⁇ O.5, 0 ⁇ b ⁇ 1 , 0 ⁇ c ⁇ 4 and 0 ⁇ d ⁇ 6.
• a third embodiment of the invention discloses a cathode material for lithium secondary batteries that comprises at least one lithium iron phosphate compound and at least one metal compound, wherein the metal compound is distributed within the lithium iron phosphate compound to form a composite compound.
• the metal compound is distributed within the lithium iron phosphate compound to form a mixed crystal.
• the lithium iron phosphate compound and the metal compound are able to provide molar ratios of about 1 to 0.001 -0.1.
• the cathode material may include carbon, the carbon capable of providing the cathode material with 1 - 15 % of carbon by weight.
• the raw material of carbon includes one or more members selected from the group consisting of carbon black, acetylene black, graphite and carbohydrate compound.
• a fourth embodiment discloses a cathode material for lithium secondary batteries that comprises at least one first crystalline compound and at least one second crystalline compound.
• the first crystalline compound is distributed within the second crystalline compound to form a composite compound that exhibits better electrical properties including better electrical conductance, capacitance and recyclability.
• the first crystalline compound can be prepared by heating a combination of at least one lithium source, at least one iron source, and at least one phosphate source while the second crystalline compound can be prepared by heating at least two metal compounds.
• the second crystalline compound can also include one or more members selected from groups IA, MA, INA, IVA, VA, IMB, IVB and VB of the periodic table.
• the lithium source, iron source, phosphate source and second crystalline compound are able to provide Li : Fe : P : second crystalline compound molar ratios of about 1 : 1 : 1 : 0.001 -0.1. In other embodiments, various Li : Fe : P : second crystalline compound molar ratios may be adopted.
• the lithium source includes one or more members selected from the group consisting of lithium carbonate, lithium hydroxide, lithium oxalate, lithium acetate, lithium fluoride, lithium chloride, lithium bromide, lithium iodide and lithium dihydrogen phosphate.
• the iron source includes one or more members selected from the group consisting of ferrous oxalate, ferrous acetate, ferrous chloride, ferrous sulfate, iron phosphate, ferrous oxide, ferric oxide, iron oxide and ferric phosphate.
• the phosphate source includes one or more members selected from the group consisting of ammonium, ammonium phosphate, ammonium dihydrogen phosphate, iron phosphate, ferric phosphate and lithium hydrogen phosphate.
• a fifth embodiment of the present invention discloses a method of preparing a composite compound comprising: mixing a lithium compound and a metal oxide; heating the mixture to a first temperature to form a composite compound with enhanced electrical conductance.
• the composite compound has a mixed crystalline structure.
• the lithium compound is a metal intercalation compound that has the general formula LiM a NbXO c , wherein M is a first- row transition metal including Fe, Mn, Ni, V, Co, and Ti; N is a metal selected from the group Fe, Mn, Ni, V, Co, Ti, Mg, Ca, Cu, Nb, Zr and rare-earth metals; X is selected from elements P, Si, S, V and Ge; and a, b and c have respective values that would render said metal intercalation compound charge-neutral.
• the metal oxide includes one or more members selected from groups IA 1 IIA, IMA, IVA, VA, 1MB, IVB and VB of the period table.
• the first and second metal oxides may include one or more members selected from the group consisting of MgO, SrO, AI 2 O 3 , SnO 2 , Sb 2 O 3 , Y 2 O 3 , TiO 2 and V 2 O 5 .
• batteries may be manufactured using the cathode materials as described in the previously disclosed embodiments.
• Figs. 1 -4 illustrate structural relationships of a mixed crystal, specifically, between a lithium iron phosphate compound and a composite metal compound
• Figs. 5 illustrate x-ray diffraction (XRD) patterns of composite compounds according to embodiments of the presently disclosed invention.
• a cathode material for lithium secondary batteries can be provided by combining at least one lithium metal compound with at least one mixed metal crystal, wherein the lithium metal compound has an olivine structure and the mixed metal crystal includes a mixture of metal elements and metal oxides.
• a general formula for a mixed crystal compound can be expressed as:
• A includes one or more transition metals from the first row including without limitation Fe, Mn, Ni, V, Co and Ti;
• B includes one or more doped metals including without limitation Fe, Mn, Ni, V,
• X includes one or more members of P, Si, S, V and Ge;
• M includes one or more metals selected from groups IA, MA, IMA, IVA, VA, IMB,
• N includes one or more members of O, N, H, S, SO 4 , PO 4 ,OH, Cl, fluorine related elements;
• the mixed crystal compound includes a lithium compound [Li a Ai -y B y (XO 4 )b] portion and a metal compound M c N d portion having a mixed crystalline relationship, with the lithium compound serving as the backbone or main building block of the cathode material.
• the metal compound can be distributed into the lithium compound to provide a composite compound or a mixed crystal.
• the cathode material may also include doped carbon additives, e.g., the mixed crystal compound Li a Ai -y B y (XO 4 )b / M c N d may be doped with carbon scattered between grain boundaries or coated on the grain surfaces.
• doped carbon additives e.g., the mixed crystal compound Li a Ai -y B y (XO 4 )b / M c N d may be doped with carbon scattered between grain boundaries or coated on the grain surfaces.
• the microstructure of the mixed crystal compound which is capable of being utilized as a cathode material, includes the lithium compound and the metal compound having a mixed-crystalline structure with mixed crystal lattices.
• the cathode material can come in at least three possible forms: smaller crystals residing within a larger crystal lattice, smaller crystal residing in between grain boundaries of large crystals, or smaller crystals residing on the exterior grain surfaces of a large crystal.
• the mixed crystal 10 includes a mixture of a lithium compound [Li a Ai -y B y (XO 4 )b] 12 and a mixed metal crystal or metal compound [M c N d ] 14.
• the lithium compound 12 has a larger crystal lattice while the metal compound 14 has a smaller crystal lattice.
• the metal compound 14, having a smaller crystal lattice 14, may be received or distributed within the lithium compound 12 having the larger crystal lattice 12 as best illustrated in Fig. 1.
• the metal compound 14 can be received or distributed between two or more large crystal lattices 12 as best illustrated in Fig. 2.
• the metal compound 14 can reside within grain boundaries of the lithium compound 12 as best illustrated in Fig. 3.
• the metal compound 14 may be dispersed about the exterior grain surfaces of the lithium compound 12 as best illustrated in Fig. 4.
• lithium ion migration serves as a bridge either within a crystal lattice or in between two or more crystal lattices, wherein lithium ions can be fully released for enhanced electrical properties including electrical conductance, capacitance and recyclability.
• the mixed crystal may also provide enhanced electrochemical properties.
• the mixed crystal 10 may take on mixed crystalline forms. In other words, during formation of the metal compound 14 by mixing at least two metal oxides, a large number of crystal defects may be introduced within the intermediary or composite crystals such that the electronic states and formation of the metal oxides are altered or changed.
• the metal compound 14 with its mixed crystalline structure therefore, contains a large number of oxygen vacancies and missing oxygen atoms. The oxygen vacancies can facilitate carrier conduction thereby enhancing the conductivity of the mixed crystal 10.
• the formation of the metal compound 14 having two or more metal oxides will become more apparent in subsequent discussion.
• the metal compound 14 can be received between the grain boundaries or on the exterior crystal lattices of the lithium compound 12 in forming the mixed crystal 10 as described above.
• the metal compound 14 and the lithium compound 12 may be heated or sintered at about 600-900 0 C in an inert gas or reducing gas atmosphere for at least 2 hours.
• the resulting mixed crystal 10 provides an enhanced active material with improved electrical properties including conductivity and electrochemical properties thereby enhancing conductivity and charging capacity of a lithium secondary battery.
• the lithium compound has the general formula LiM a NbXO c , wherein: M is a first-row transition metal including Fe, Mn, Ni, V, Co and Ti; N is a metal selected from the group Fe, Mn, Ni, V, Co, Ti, Mg, Ca, Cu, Nb, Zr and rare-earth metals; X is selected from elements P, Si, S, V and Ge; and a, b and c have respective values that would render said lithium compound charge-neutral.
• the lithium compound can include a metal intercalation compound having a similar general formula.
• the lithium compound has the general formula Li a Ai -y B y (XO 4 )b, wherein: A is a first-row transition metal including Fe, Mn, Ni, V, Co and Ti; B is a metal selected from the group Fe, Mn, Ni, V, Co, Ti, Mg, Ca, Cu, Nb, Zr and rare-earth metals; X is selected from elements P, Si, S and Ge; and 0 ⁇ a ⁇ 1 , O ⁇ y ⁇ O.5 and 0 ⁇ b ⁇ 1.
• the metal compound has the general formula M c Nd, wherein M is metal selected from IA, MA, IMA, IVA, VA, IMB, IVB and VB groups in the periodic table; N is selected from O, N, H, S, SO 4 , PO 4 , , OH, Cl, F; and 0 ⁇ c ⁇ 4 and 0 ⁇ d ⁇ 6.
• a cathode material for lithium secondary batteries can be provided by sintering lithium iron phosphate (LiFePO 4 ) with a mixture compound, the cathode material capable of providing LiFePO 4 : mixture compound molar ratios of 1 : 0.001 -0.1.
• the mixture compound can be formed of two or more metal oxides wherein the metal can be selected from groups IA, NA, IMA, IVA, VA, INB, IVB and VB of the periodic table.
• the weight of a first metal oxide is about 0.5-20 % of the weight of a second metal oxide.
• the mixture of metal oxides can take on a mixed crystal configuration. Based on mixed crystal formation theory, mixing of two or more metal oxides can form a composite mixed metal crystal such that a plurality of crystal defects are introduced to the crystal structure and lattice. The electronic states of the metal oxides are altered or changed thereby producing a large number of oxygen atom vacancies. These vacancies facilitate electronic carrier conductions thus producing a highly conductive mixed metal crystal.
• the metal mixture compound having a mixed crystalline configuration, can be coupled to the crystal lattices of LiFePO 4 by a heating or sintering process.
• the mixed metal crystal can be coupled to the crystal lattices of LiFePO 4 to provide a lithium iron phosphate cathode material with a mixed crystal structure and configuration.
• the resulting mixed crystal structure can effectively improve the conductivity, electrochemical properties, and greatly enhance the charge capacity of the lithium secondary battery.
• the lithium iron phosphate cathode material can further include carbon coating on the exterior surfaces of the sintered product, the amount of carbon material added being capable of providing the final product with 1 -15 % of carbon by weight.
• the types of carbon material that can be utilized include without limitation one or more of carbon black, acetylene black, graphite and carbohydrate compound.
• the invention also includes batteries made from the new cathode materials described in other embodiments.
• a method of preparing a mixed crystal lithium iron phosphate cathode material includes evenly mixing at least one LiFePO 4 compound with a mixture compound and heating the resulting mixture to 600-900 0 C in an inert gas or reducing gas atmosphere for between 2-48 hours.
• the mixture compound includes two or more metal oxides wherein the metal can be selected from groups IA, MA, IMA, IVA, VA, 1MB, IVB and VB of the periodic table.
• the mixture compound provides a mixed crystalline structure, wherein a method of preparing the mixture compound with the corresponding mixed crystalline structure includes mixing metal oxides from groups IA, MA, IMA, IVA, VA, 1MB, IVB and VB, and heating the mixture to 600-1200 0 C for between 2-48 hours.
• the LiFePO 4 compound may be prepared by providing lithium, iron and phosphate sources to provide Li, Fe and P atoms with Li : Fe : P molar ratios of 1 : 1 : 1. In other embodiments, different Li : Fe : P molar ratios may be adopted.
• the mixture can accordingly be grinded in a ball mill for 2-48 hours, dried between 40-80 0 C or stirred until dry, and heated to 600-900 0 C in an inert gas or reducing gas atmosphere for between 2-48 hours.
• carbon additives can be provided to the resulting mixture and sintered to facilitate carbon coating.
• the amount of carbon additives is capable of providing the resulting lithium iron phosphate cathode material with 1 -15 % of carbon by weight.
• the types of carbon material that can be utilized include without limitation one or more of carbon black, acetylene black, graphite and carbohydrate compound.
• the carbon coating process further enhances the electrical conductivity of the cathode material.
• Another method of preparing a mixed crystal cathode material includes evenly mixing lithium, iron and phosphate sources and heat to 600-900 0 C in an inert gas or reducing gas atmosphere for at least 2 hours.
• the resulting mixture can then be combined with a mixed metal compound having a combination of two or more metal oxides selected from groups IA, MA, IMA, IVA, VA, IMB, IVB and VB of the periodic table.
• the lithium source, iron source, phosphate source and mixed metal compound are capable of providing Li : Fe : P : mixed metal compound molar ratios of 1 : 1 : 1 : 0.001- 0.1.
• different Li : Fe : P mixed metal compound molar ratios may be adopted.
• at least one carbon source can be added to the resulting mixture, the carbon source including one or more of the following without limitation: carbon black, acetylene black, graphite and carbohydrate compound. The amount of carbon added to the resulting mixture should be able to provide the final product with 1 -15 % of carbon by weight.
• lithium sources capable of being used in preparing the cathode material include one or more of the following compounds without limitation: lithium carbonate, lithium hydroxide, lithium oxalate, lithium acetate, lithium fluoride, lithium chloride, lithium bromide, lithium iodide and lithium dihydrogen phosphate.
• iron sources include one or more of the following compounds without limitation: ferrous oxalate, ferrous acetate, ferrous chloride, ferrous sulfate, iron phosphate, ferrous oxide, ferric oxide, iron oxide and ferric phosphate.
• phosphorous sources include one or more of the following compounds without limitation: ammonium, ammonium phosphate, ammonium dihydrogen phosphate, iron phosphate, ferric phosphate and lithium hydrogen phosphate.
• one or more solvents may be introduced including ethanol, Dl water and acetone. In other embodiments, other mixing media and solvents may be utilized. In addition, the mixture can be dried between 40-80 0 C or stirred until dry.
• inert gases include helium, neon, argon, krypton, xenon, radon and nitrogen. Additionally, reducing gases including hydrogen and carbon monoxide can also be incorporated. Other suitable gases may also be adopted.
• lithium, iron, phosphorous and carbon sources may be utilized along with suitable solvents, inert gases and reducing gases as will be appreciated by one skilled in the art.
• EXAMPLE 1 [0051 ] Mix LiFePO 4 with [Y 2 O 3 and Sb 2 O 3 (mass ratio 0.2 : 1 )] to provide [LiFePO 4 : (Y 2 O 3 and Sb 2 O 3 )] molar ratio of [1 : (0.04)], add carbon-containing acetylene black (amount of carbon capable of providing 10 % by weight of carbon content in the final product), grind the mixture in a ball mill for 15 hours, remove and dry at 60 0 C. Heat the resulting powder in a nitrogen atmosphere at 650 0 C for 5 hours to provide a LiFePO 4 composite cathode material. [0052] EXAMPLE 2
• LiFePO 4 composite cathode material 750 0 C for 20 hours to provide a LiFePO 4 composite cathode material.
• Nb 2 O 5 and TiO 2 molar ratio of 1 : 1 : 1 : 0.01 , wherein Nb 2 O 5 is 5 % of TiO 2 by mass, carbon-containing sucrose (amount of carbon capable of providing 5 % by weight of carbon content in the final product), grind the mixture in a ball mill for 20 hours, remove and dry at 65 0 C. Heat the resulting powder in a nitrogen atmosphere at 750 0 C for 15 hours to provide a LiFePO 4 composite cathode material.
• PVDF polyvinyl acrylate
• NMP N- methylpyrrolidone
• Initial specific capacity Initial discharge capacity (milliampere hour) / weight of cathode active material (grams).
• Figs. 5 illustrating x-ray diffraction (XRD) patterns of two composite compounds according to embodiments of the presently disclosed invention having olivine-type crystal structure and good crystal growth and development.

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