WO2015059779A1 - Positive electrode material for lithium ion secondary batteries, and lithium ion secondary battery - Google Patents

Positive electrode material for lithium ion secondary batteries, and lithium ion secondary battery Download PDF

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WO2015059779A1
WO2015059779A1 PCT/JP2013/078641 JP2013078641W WO2015059779A1 WO 2015059779 A1 WO2015059779 A1 WO 2015059779A1 JP 2013078641 W JP2013078641 W JP 2013078641W WO 2015059779 A1 WO2015059779 A1 WO 2015059779A1
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positive electrode
ion secondary
lithium ion
secondary battery
electrode material
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PCT/JP2013/078641
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French (fr)
Japanese (ja)
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小西　宏明
章 軍司
達哉 遠山
孝亮 馮
翔 古月
豊隆 湯浅
小林　満
所　久人
秀一 高野
崇 中林
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株式会社日立製作所
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Priority to PCT/JP2013/078641 priority Critical patent/WO2015059779A1/en
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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
    • H01M4/48—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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/40—Nickelates
    • C01G53/42—Nickelates containing alkali metals, e.g. LiNiO2
    • C01G53/44—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese
    • C01G53/50—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese of the type [MnO2]n-, e.g. Li(NixMn1-x)O2, Li(MyNixMn1-x-y)O2
    • 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
    • H01M4/362—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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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
    • 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 positive electrode material for a lithium ion secondary battery and a lithium ion secondary battery containing the positive electrode material.
  • Lithium ion secondary batteries have a higher energy density per weight than secondary batteries such as nickel metal hydride batteries and lead batteries. Therefore, application to electric vehicles and power storage systems is expected. However, in order to meet the demands of electric vehicles, it is necessary to further increase the energy density. In order to realize a high energy density of the battery, it is necessary to increase the energy density of the positive electrode and the negative electrode.
  • the layered solid solution represented by Li 2 MnO 3 —LiMO 2 (M is an element such as Ni, Co, Mn, Fe, Ti, Zr, Al, Mg, Cr, V, etc.) has a high capacity, Energy density can be expected.
  • the layered solid solution can also be expressed as a composition Li 1 + x M 1-x O 2 enriched in Li of the layered oxide-based positive electrode active material.
  • Patent Document 1 describes a positive electrode material in which a positive electrode active material composition such as a layered solid solution is coated with a vanadium oxide such as VO x or V 2 O 5 .
  • the layered solid solution can be expected to have a high capacity, there is a problem that a high output cannot be obtained because the resistance is high in a region where the SOC is low.
  • the electron conductivity is improved by coating the positive electrode active material with vanadium oxide, but the resistance is further reduced in a low SOC region for higher output. Is desired.
  • an object of the present invention is to provide a lithium ion secondary battery that maintains a high capacity and has a high output.
  • Positive electrode material for a lithium ion secondary battery the composition formula Li x Ni a Mn 0.8-a -b M b O 2 + ⁇ (0.95 ⁇ x ⁇ 1.2,0.2 ⁇ a ⁇ 0 .4, 0 ⁇ b ⁇ 0.02, ⁇ 1 ⁇ ⁇ ⁇ 1, and M is at least one element selected from Mo, W, Zr, Nb, Ti, Fe, and Cu.
  • Lithium transition metal oxide and lithium vanadium oxide in a mixed state, and the atomic ratio of vanadium to Ni, Mn, and M (V / (Ni + Mn + M)) is 0.01 / 0.8 or more and 0.06 / It is less than 0.8.
  • the layered solid solution positive electrode material of the present invention it is possible to provide a lithium ion secondary battery with high capacity and high output.
  • ⁇ Positive electrode material> When a lithium ion secondary battery is employed in an electric vehicle and a plug-in hybrid vehicle, a high capacity is required, a long traveling distance per charge, a low resistance, and a high output are required.
  • FIG. 1 the result of the DC resistance measurement of a general layered solid solution is shown in FIG. 1, 1 indicates a DC resistance measured while changing the SOC in the discharging direction, and 2 indicates a DC resistance measured while changing the SOC in the charging direction.
  • the direct current resistance is high in a low SOC region.
  • the direct current resistance is measured while changing the SOC (State of Charge) in the charging direction, and the direct current resistance is measured while changing the SOC in the discharging direction.
  • the resistance is different, and particularly when the measurement is performed while changing the SOC in the discharge direction, the resistance is high.
  • the increase in resistance at the end of discharge becomes a big problem. Therefore, in order to improve the output, it is necessary to suppress an increase in resistance in a region where the SOC is low.
  • the range of usable SOC is expanded by reducing the resistance in the low-SOC region.
  • a portion with a high DC resistance value is not used so much because a high output cannot be obtained. Therefore, by reducing the resistance in the low SOC region, the usable SOC range can be expanded and the effective capacity can be improved.
  • the inventors have found that the resistance in a low SOC region can be reduced by using a layered solid solution and a lithium vanadium oxide that absorbs and releases Li at about 3.5 V in the positive electrode material.
  • Lithium vanadium oxide reacts with Li near 3.5V. Therefore, by mixing lithium vanadium oxide into a layered solid solution, lithium vanadium oxide and Li can react in a region where the SOC is low, so that the resistance at the end of discharge can be reduced. As a result, a high output lithium ion secondary battery can be provided.
  • the positive electrode material for a lithium ion secondary battery according to the present invention has a composition formula Li x Ni a Mn 0.8-ab M b O 2 + ⁇ (0.95 ⁇ x ⁇ 1.2, 0.2 ⁇ a ⁇ 0.4). , 0 ⁇ b ⁇ 0.02, ⁇ 1 ⁇ ⁇ ⁇ 1, and M is at least one element selected from Mo, W, Zr, Nb, Ti, Fe, and Cu. It contains transition metal oxide and lithium vanadium oxide in a mixed state.
  • X in the composition formula represents the amount of Li, and if it is less than 0.95, the amount of Li contributing to the reaction is reduced and a high capacity cannot be obtained. On the other hand, if it is larger than 1.2, the crystal lattice becomes unstable and the discharge capacity decreases.
  • a in the composition formula indicates the amount of Ni, and if it is less than 0.2, the amount of Ni contributing to the reaction decreases and a high capacity cannot be obtained. On the other hand, when it is larger than 0.4, the valence of Ni increases, the charge / discharge capacity involving Ni decreases, and a high capacity cannot be obtained.
  • ⁇ in the composition formula represents the amount of oxygen. This value is determined in accordance with the ratio of Li, Ni, and Mn, but may have some non-stoichiometry.
  • M in the composition formula is an additive or impurity that is appropriately added within a range not affecting the present invention, and is at least one element selected from Mo, W, Zr, Nb, Ti, Fe, and Cu.
  • the lithium transition metal oxide is mainly composed of Li, Ni, and Mn, it has an advantage that the cost is lower than that of the positive electrode active material containing a large amount of Co.
  • the atomic ratio of V to Ni, Mn, and M (V / (Ni + Mn + M)) in the positive electrode material is preferably 0.01 / 0.8 or more and less than 0.06 / 0.8.
  • V / (Ni + Mn + M) By setting V / (Ni + Mn + M) to less than 0.06 / 0.8, it is possible to maintain a high capacity and suppress an increase in resistance at the end of discharge.
  • V / (Ni + Mn + M) is 0.06 / 0.8 or more, the amount of lithium that reacts with vanadium increases, the capacity of the positive electrode may decrease, and the resistance may increase.
  • the electrode density can be improved by using a positive electrode material containing a lithium transition metal oxide and a lithium vanadium oxide in a mixed state. This is because the particle size of the lithium vanadium oxide is smaller than that of the lithium transition metal oxide, and particles having different particle sizes can be mixed.
  • primary particles of lithium transition metal oxide and lithium vanadium oxide are preferably mixed. Furthermore, the lithium vanadium oxide is preferably fixed to the primary particle surface of the lithium transition metal oxide. By mixing primary particles of lithium transition metal oxide and lithium vanadium oxide, electronic conduction between the lithium transition metal oxide particles can be enhanced. On the other hand, when secondary particles of lithium transition metal oxide and lithium vanadium oxide are mixed, an electron conduction path between the secondary particles and the conductive material can be constructed, but the lithium transition metal oxide particles inside the secondary particles The electronic conduction between them cannot be increased.
  • the particle state of the positive electrode material can be confirmed by a scanning electron microscope-energy dispersive X-ray analysis (SEM-EDX).
  • the positive electrode material according to the present invention can be produced by a method generally used in the technical field to which the present invention belongs. For example, after preparing a lithium transition metal oxide by mixing a compound containing each of Li, Ni, and Mn at an appropriate ratio and firing, a compound containing V is appropriately added to the obtained lithium transition metal oxide. It can be produced by mixing at a ratio and firing at 850 to 1050 ° C. The composition of the positive electrode material can be appropriately adjusted by changing the ratio of the compound to be mixed. Moreover, you may produce by mixing the compound containing each of Li, Ni, Mn, and V in a suitable ratio, and baking.
  • the lithium transition oxide does not contain Co
  • vanadium is almost dissolved in the lithium transition metal oxide even if it is prepared by mixing and firing the vanadium compound at the stage of mixing the lithium transition metal oxide raw material. This was confirmed by X-ray diffraction measurement.
  • Examples of the compound containing Li include lithium acetate, lithium nitrate, lithium carbonate, lithium hydroxide, and lithium oxide.
  • Examples of the Ni-containing compound include nickel acetate, nickel nitrate, nickel carbonate, nickel sulfate, and nickel hydroxide.
  • Examples of the compound containing Mn include manganese acetate, manganese nitrate, manganese carbonate, manganese sulfate, manganese oxide, and the like.
  • Examples of the compound containing V include vanadium oxide, vanadium nitride, and vanadium boride.
  • composition of the lithium transition metal oxide in the positive electrode material and the amount of V in the positive electrode material can be determined by elemental analysis by, for example, inductively coupled plasma method (ICP).
  • ICP inductively coupled plasma method
  • a lithium ion secondary battery according to the present invention includes the above positive electrode material. By using the above positive electrode material for the positive electrode, a high capacity lithium ion secondary battery can be maintained while maintaining a high capacity.
  • the lithium ion secondary battery according to the present invention can be preferably used for, for example, an electric vehicle.
  • the positive electrode active material occludes and releases lithium ions by charging and discharging. Since all lithium ions released from the positive electrode active material do not return to the positive electrode, the composition of the positive electrode active material after charge / discharge is expected to be different from that before charge / discharge.
  • the layered compound positive electrode active material represented by LiMO 2 has a Li composition ratio of about 0.75 in a fully discharged state (2.5 V) when used in a potential range of 2.5 to 4.3 V. I know that When considered similarly to the layered compound, it is estimated that the amount of Li after charge / discharge of the layered solid solution is also reduced by about 15 to 30% in the full discharge state compared to before charge / discharge.
  • the layered solid solution positive electrode active material is not fully charged (at 2.5 V).
  • the composition is assumed to be Li x Ni a Mn 0.8-a-b M b O 2 + ⁇ (0.80 ⁇ x ⁇ 1.2, 0.2 ⁇ a ⁇ 0.4, ⁇ 1 ⁇ ⁇ ⁇ 1). it can. That is, the lithium transition metal oxide after charge / discharge according to the present invention satisfies 0.090 ⁇ Li / metal element ⁇ 1.5.
  • a lithium ion secondary battery includes a positive electrode including a positive electrode material, a negative electrode including a negative electrode material, a separator, an electrolytic solution, an electrolyte, and the like.
  • the negative electrode material is not particularly limited as long as it is a substance that can occlude and release lithium ions.
  • Substances generally used in lithium ion secondary batteries can be used as the negative electrode material.
  • graphite, a lithium alloy, etc. can be illustrated.
  • separator those generally used in lithium ion secondary batteries can be used.
  • examples thereof include polyolefin microporous films and nonwoven fabrics such as polypropylene, polyethylene, and a copolymer of propylene and ethylene.
  • electrolytic solution and the electrolyte those generally used in lithium ion secondary batteries can be used.
  • diethyl carbonate, dimethyl carbonate, ethylene carbonate, propylene carbonate, vinylene carbonate, methyl acetate, ethyl methyl carbonate, methyl propyl carbonate, dimethoxyethane and the like can be exemplified as the electrolytic solution.
  • a lithium ion secondary battery 12 includes a positive electrode 3 in which a positive electrode active material is applied on both sides of a current collector, a current collector The electrode group which has the negative electrode 4 which apply
  • the negative electrode 6 is electrically connected to the battery can 6 through the negative electrode lead piece 8.
  • a sealing lid 9 is attached to the battery can 6 via a packing 10.
  • the positive electrode 3 is electrically connected to the sealing lid 9 via the positive electrode lead piece 7.
  • the wound body is insulated by the insulating plate 11.
  • the electrode group may not be the wound body shown in FIG. 2, but may be a laminated body in which the positive electrode 3 and the negative electrode 4 are laminated via the separator 5.
  • the positive electrode materials of Examples 1 to 7 and Comparative Example 2 were produced by the following method. Lithium carbonate, nickel carbonate, manganese carbonate, and vanadium oxide were mixed with a ball mill, and the resulting mixture was baked in the atmosphere at 500 ° C. for 12 hours to obtain a lithium transition metal oxide. The obtained lithium transition metal oxide was pelletized and then fired at 850 to 1050 ° C. for 12 hours in the air. The fired pellets were pulverized in an agate mortar and classified with a 45 ⁇ m sieve to obtain a positive electrode material. It was confirmed by X-ray diffraction analysis that the obtained positive electrode material contained a lithium transition metal oxide containing Li, Ni, and Mn and a lithium vanadium oxide containing Li and V.
  • the positive electrode materials of Comparative Examples 1 and 6 to 9 were prepared in the same manner as in Example 1 except that the compound containing the additive element was not mixed.
  • the positive electrode material of Comparative Example 3 was prepared in the same manner as in Example 1 except that vanadium oxide was changed to magnesium oxide. From the X-ray diffraction measurement, it was confirmed that the additive element magnesium was dissolved in the lithium transition metal oxide.
  • the positive electrode material of Comparative Example 4 was prepared in the same manner as in Example 1 except that vanadium oxide was changed to aluminum oxide. By X-ray diffraction measurement, it was confirmed that aluminum as an additive element was dissolved in the lithium transition metal oxide.
  • the positive electrode material of Comparative Example 5 was produced by the following method. Lithium carbonate, nickel carbonate, and manganese carbonate were mixed with a ball mill, and the resulting mixture was fired at 500 ° C. for 12 hours in the air to obtain a lithium transition metal oxide. The obtained lithium transition metal oxide was pelletized and then fired at 850 to 1050 ° C. for 12 hours in the air. The fired pellets were pulverized in an agate mortar and classified with a 45 ⁇ m sieve. Thereafter, a lithium transition metal oxide was added to an aqueous citric acid solution in which vanadium oxide was dissolved, and water was evaporated while stirring at 120 ° C. Then, the positive electrode material which vanadium oxide coat
  • the positive electrode materials used in the examples and comparative examples are shown in Tables 1 to 5.
  • the composition of the lithium transition metal oxide was expressed as Li x Ni a Mn 0.8-a- b MbO 2 + ⁇ .
  • a positive electrode slurry, a conductive agent, and a binder were mixed uniformly to prepare a positive electrode slurry.
  • the positive electrode slurry was applied onto an aluminum current collector foil having a thickness of 20 ⁇ m, dried at 120 ° C., and compression-molded with a press so that the electrode density was 2.2 g / cm 3 to obtain an electrode plate. Thereafter, the electrode plate was punched into a disk shape having a diameter of 15 mm to produce a positive electrode.
  • the negative electrode was produced using metallic lithium.
  • a solution obtained by dissolving LiPF 6 at a concentration of 1.0 mol / L in a mixed solvent of ethylene carbonate and dimethyl carbonate having a volume ratio of 1: 2 was used.
  • the charge / discharge test was performed as follows. The prototype battery was charged and discharged at a current equivalent to 0.05 C with an upper limit voltage of 4.6 V, and discharged at a current equivalent to 0.05 C with a lower limit voltage of 2.5 V. The discharge capacity obtained in the range of 4.6-3.4V was defined as the rated capacity. These discharge capacities are shown in Tables 1 to 5.
  • the DC resistance was determined for the prototype battery as follows. The prototype battery was charged and discharged at a current equivalent to 0.05C with an upper limit voltage of 4.6V, and discharged at a current equivalent to 0.05C with a lower limit voltage of 2.5V. Was the rated capacity. The prototype battery after 2 cycles was charged to 4.6 V, and then 70% of the rated capacity was discharged. Thereafter, a current of 1.2 mA was applied for 10 seconds, and the direct current resistance when the SOC was 30% was measured. A value obtained by dividing the potential difference before applying the current and after applying the current for 10 seconds by the applied current value (1.2 mA) was defined as the DC resistance value. These DC resistances are shown in Tables 1-5.
  • FIG. 3 shows a graph showing the relationship between the SOC and the DC resistance value in Example 1 and Comparative Example 1 when the SOC is changed in the discharge direction.
  • 13 is a plot of the DC resistance value against the SOC of Example 1
  • 14 is a plot of the DC resistance value against the SOC of Comparative Example 1. From FIG. 3, it can be seen that in Example 1 including lithium transition metal oxide and lithium vanadium oxide, the DCR is lower than that in Comparative Example 1 where only the lithium transition metal oxide is present in the SOC range of 20 to 40%. I understood. From this result, it was found that the resistance at the end of discharge can be reduced by using a positive electrode material containing a lithium transition metal oxide and a lithium vanadium oxide in a mixed state. Also, the same graphs as in Example 1 were obtained for Examples 2 to 7. Therefore, by using the positive electrode materials of Examples 1 to 7, the output can be improved while maintaining the high capacity of the lithium ion secondary battery.
  • Comparative Examples 3 and 4 since the added element was Mg or Al not involved in the reaction and was dissolved in the lithium transition metal oxide, the discharge capacity and the direct current resistance were increased. In Comparative Example 5, there was no significant change in both discharge capacity and DC resistance. This is because the positive electrode material of Comparative Example 5 was prepared by mixing vanadium oxide after the synthesis of the lithium transition metal oxide and coating at a low heating temperature, and vanadium oxide was isolated in the positive electrode and did not participate in the reaction. is there.
  • the decrease in discharge capacity was small, and the DC resistance was 40 ⁇ or less. This is because in the positive electrode materials of Examples 1 and 2, the atomic ratio of vanadium to Ni, Mn, and M was 0.02 / 0.8 or less.
  • the atomic ratio of vanadium to Ni, Mn, and M in the positive electrode material including the lithium transition metal oxide and the lithium vanadium oxide is 0.01 / 0.8 or more and less than 0.06 / 0.8.
  • the lithium transition metal oxide represented by the composition formula Li 1.2 Ni 0.2 Mn 0.6 O 2 is also mixed with lithium vanadium oxide to suppress the decrease in discharge capacity to within 2%, and the DC resistance is reduced. It was found that it can be reduced.
  • the lithium transition metal oxide represented by the composition formula Li 1.1 Ni 0.25 Mn 0.55 O 2 is also mixed with lithium vanadium oxide, thereby suppressing the decrease in discharge capacity to within 3% and reducing the DC resistance. It was found that it can be reduced.
  • the lithium transition metal oxide represented by the composition formula LiNi 0.35 Mn 0.45 O 2 can also suppress the decrease in discharge capacity to within 3% and reduce the DC resistance by mixing lithium vanadium oxide. I understood.
  • the lithium transition metal oxide represented by the composition formula Li 0.95 Ni 0.4 Mn 0.4 O 2 is also mixed with lithium vanadium oxide to suppress the decrease in discharge capacity within 3%, and the DC resistance is reduced. Reduced.
  • Examples 1, 4 to 7, Examples 1, 5, and 6 have a high discharge capacity of 175 Ah / kg or more and a low DCR of 40 ⁇ or less. This is because the composition of the lithium transition metal oxide contained in the positive electrode materials of Examples 1, 5, and 6 satisfies 0.25 ⁇ a ⁇ 0.35. By adjusting the composition ratio of Ni and Mn of the lithium transition metal oxide, a positive electrode material having a higher discharge capacity and a lower DCR can be obtained.
  • a positive electrode material of less than 0.06 / 0.8 the decrease in discharge capacity was suppressed to within 5%, and the direct current resistance at the end of discharge was reduced compared to the positive electrode material made of only lithium transition metal oxide. As a result, it is possible to provide a lithium ion secondary battery with high output while maintaining discharge capacity.

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Abstract

The present invention addresses the problem of providing a positive electrode material which is able to achieve a high capacity and has a low resistance in the final stage of discharge. This problem can be solved by a positive electrode material for lithium ion secondary batteries, which is characterized by containing a lithium transition metal oxide represented by composition formula LixNiaMn0.8-a-bMbO2+δ (wherein 0.95 ≤ x ≤ 1.2, 0.2 ≤ a ≤ 0.4, 0 ≤ b < 0.02, -1 ≤ δ ≤ 1, and M represents at least one element selected from among Mo, W, Zr, Nb, Ti, Fe and Cu) and a lithium vanadium oxide in a mixed state, and which is also characterized in that the atomic ratio of vanadium to Ni, Mn and M (V/(Ni + Mn + M)) is 0.01/0.8 or more but less than 0.06/0.8.

Description

リチウムイオン二次電池用正極材料およびリチウムイオン二次電池Positive electrode material for lithium ion secondary battery and lithium ion secondary battery
　本発明は、リチウムイオン二次電池用の正極材料、及び前記正極材料を含むリチウムイオン二次電池に関する。 The present invention relates to a positive electrode material for a lithium ion secondary battery and a lithium ion secondary battery containing the positive electrode material.
　近年、地球温暖化の防止や化石燃料の枯渇への懸念から、走行に必要となるエネルギーが少ない電気自動車に期待が集まっている。しかしながら、電気自動車には、駆動用電池のエネルギー密度が低く、一充電での走行距離が短いという課題がある。そこで、安価で高エネルギー密度をもつ二次電池が求められている。 In recent years, due to concerns about global warming prevention and fossil fuel depletion, there are high expectations for electric vehicles that require less energy to travel. However, the electric vehicle has a problem that the energy density of the driving battery is low and the traveling distance in one charge is short. Therefore, there is a need for a secondary battery that is inexpensive and has a high energy density.
　リチウムイオン二次電池は、ニッケル水素電池や鉛電池等の二次電池に比べて重量当たりのエネルギー密度が高い。そのため、電気自動車や電力貯蔵システムへの応用が期待されている。しかし、電気自動車の要請に応えるためには、さらなる高エネルギー密度化が必要である。電池の高エネルギー密度化を実現するためには、正極及び負極のエネルギー密度を高める必要がある。 Lithium ion secondary batteries have a higher energy density per weight than secondary batteries such as nickel metal hydride batteries and lead batteries. Therefore, application to electric vehicles and power storage systems is expected. However, in order to meet the demands of electric vehicles, it is necessary to further increase the energy density. In order to realize a high energy density of the battery, it is necessary to increase the energy density of the positive electrode and the negative electrode.
　Ｌｉ2ＭｎＯ3－ＬｉＭＯ2（ＭはＮｉ、Ｃｏ、Ｍｎ、Ｆｅ、Ｔｉ、Ｚｒ、Ａｌ、Ｍｇ、Ｃｒ、Ｖ等の元素である）で示される層状固溶体は、高容量が得られるため、高エネルギー密度化が期待できる。層状固溶体は、層状酸化物系の正極活物質のＬｉを富化した組成Ｌｉ1+xＭ1-xＯ2として表すこともできる。 Since the layered solid solution represented by Li 2 MnO 3 —LiMO 2 (M is an element such as Ni, Co, Mn, Fe, Ti, Zr, Al, Mg, Cr, V, etc.) has a high capacity, Energy density can be expected. The layered solid solution can also be expressed as a composition Li 1 + x M 1-x O 2 enriched in Li of the layered oxide-based positive electrode active material.
　特許文献１には、層状固溶体等の正極活物質組成物をＶＯxやＶ2Ｏ5等のバナジウム酸化物で被覆した正極材料が記載されている。 Patent Document 1 describes a positive electrode material in which a positive electrode active material composition such as a layered solid solution is coated with a vanadium oxide such as VO x or V 2 O 5 .
特開２００９－７６４４６号公報JP 2009-76446 A
　層状固溶体は、高容量が期待できるが、ＳＯＣが低い領域で抵抗が高く、高出力が得られないという課題がある。特許文献１に記載の正極材料では、正極活物質をバナジウム酸化物で被覆することにより電子伝導性を改善しているが、高出力化のためにはＳＯＣが低い領域でさらに抵抗を低減することが望まれる。 Although the layered solid solution can be expected to have a high capacity, there is a problem that a high output cannot be obtained because the resistance is high in a region where the SOC is low. In the positive electrode material described in Patent Document 1, the electron conductivity is improved by coating the positive electrode active material with vanadium oxide, but the resistance is further reduced in a low SOC region for higher output. Is desired.
　そこで、本発明は、高容量維持するとともに、出力の高いリチウムイオン二次電池を提供することを目的とする。 Therefore, an object of the present invention is to provide a lithium ion secondary battery that maintains a high capacity and has a high output.
　本発明に係るリチウムイオン二次電池用正極材料は、組成式ＬｉxＮｉaＭｎ0.8-a―bＭbＯ2+δ（０．９５≦ｘ≦１．２、０．２≦ａ≦０．４、０≦ｂ≦０．０２、－１≦δ≦１、Ｍは、Ｍｏ、Ｗ、Ｚｒ、Ｎｂ、Ｔｉ、Ｆｅ、Ｃｕから選択される少なくともいずれかの元素である。）で表されるリチウム遷移金属酸化物と、リチウムバナジウム酸化物とを混合状態で含み、Ｎｉ、Ｍｎ、Ｍに対するバナジウムの原子比（Ｖ／（Ｎｉ＋Ｍｎ＋Ｍ））が、０．０１／０．８以上０．０６／０．８未満であることを特徴とする。 Positive electrode material for a lithium ion secondary battery according to the present invention, the composition formula Li x Ni a Mn 0.8-a -b M b O 2 + δ (0.95 ≦ x ≦ 1.2,0.2 ≦ a ≦ 0 .4, 0 ≦ b ≦ 0.02, −1 ≦ δ ≦ 1, and M is at least one element selected from Mo, W, Zr, Nb, Ti, Fe, and Cu. Lithium transition metal oxide and lithium vanadium oxide in a mixed state, and the atomic ratio of vanadium to Ni, Mn, and M (V / (Ni + Mn + M)) is 0.01 / 0.8 or more and 0.06 / It is less than 0.8.
　本発明の層状固溶体正極材料によれば、高容量で、かつ、出力の高いリチウムイオン二次電池を提供することができる。 According to the layered solid solution positive electrode material of the present invention, it is possible to provide a lithium ion secondary battery with high capacity and high output.
層状固溶体を正極に用いたモデル電池において、電位を充電方向および放電方向に充電状態（ＳＯＣ）を変化させながら測定した直流抵抗値の結果である。It is the result of the direct current | flow resistance value which measured the potential, changing the charge condition (SOC) in the charge direction and the discharge direction in the model battery using the layered solid solution for the positive electrode. リチウムイオン二次電池の構造を模式的に示す断面図である。It is sectional drawing which shows the structure of a lithium ion secondary battery typically. 実施例１と比較例１における充電状態（ＳＯＣ）と直流抵抗の関係を示す図である。It is a figure which shows the relationship between the charge condition (SOC) in Example 1 and the comparative example 1, and DC resistance.
　＜正極材料＞
　リチウムイオン二次電池を電気自動車およびプラグインハイブリッド自動車に採用する場合、高容量が得られ、一充電当たりの走行距離が長いこと、および抵抗が低く、高出力が得られることが要求される。ここで、一般的な層状固溶体の直流抵抗測定の結果を図１に示す。図１において、１は放電方向にＳＯＣを変化させながら測定した直流抵抗、２は充電方向にＳＯＣを変化させながら測定した直流抵抗を示す。層状固溶体では、ＳＯＣの低い領域で直流抵抗が高い。また、層状固溶体では、充電方向にＳＯＣ（Ｓｔａｔｅ　ｏｆ　ｃｈａｒｇｅ）を変化させながら直流抵抗（ＤＣＲ）を測定した場合と、放電方向にＳＯＣを変化させながら直流抵抗を測定した場合では、同じＳＯＣにおいても抵抗が異なり、特に放電方向にＳＯＣを変化させながら測定した場合において、抵抗が高い。実際に電池を使用する場合は、放電方向にＳＯＣを変化させる場合が多いため、放電末期の抵抗上昇が大きな問題となる。したがって、出力を向上させるためには、ＳＯＣが低い領域の抵抗上昇を抑制する必要がある。 <Positive electrode material>
When a lithium ion secondary battery is employed in an electric vehicle and a plug-in hybrid vehicle, a high capacity is required, a long traveling distance per charge, a low resistance, and a high output are required. Here, the result of the DC resistance measurement of a general layered solid solution is shown in FIG. In FIG. 1, 1 indicates a DC resistance measured while changing the SOC in the discharging direction, and 2 indicates a DC resistance measured while changing the SOC in the charging direction. In the layered solid solution, the direct current resistance is high in a low SOC region. In the case of a layered solid solution, the direct current resistance (DCR) is measured while changing the SOC (State of Charge) in the charging direction, and the direct current resistance is measured while changing the SOC in the discharging direction. The resistance is different, and particularly when the measurement is performed while changing the SOC in the discharge direction, the resistance is high. When a battery is actually used, since the SOC is often changed in the discharge direction, the increase in resistance at the end of discharge becomes a big problem. Therefore, in order to improve the output, it is necessary to suppress an increase in resistance in a region where the SOC is low.
　抵抗が高いＳＯＣが低い領域の抵抗を低減することによって、使用できるＳＯＣの範囲が広がる。リチウムイオン二次電池では、直流抵抗値が高い部分は、高出力が得られないため、あまり使用されない。したがって、ＳＯＣの低い領域の抵抗を低減することによって、使用できるＳＯＣの範囲を広げ、実効的な容量を向上できる。 The range of usable SOC is expanded by reducing the resistance in the low-SOC region. In a lithium ion secondary battery, a portion with a high DC resistance value is not used so much because a high output cannot be obtained. Therefore, by reducing the resistance in the low SOC region, the usable SOC range can be expanded and the effective capacity can be improved.
　発明者らは、正極材料中に、層状固溶体と、３．５Ｖ程度でＬｉを吸蔵、放出するリチウムバナジウム酸化物を、ともに用いることで、ＳＯＣが低い領域の抵抗を低減できることを見出した。リチウムバナジウム酸化物は、３．５Ｖ付近でＬｉと反応する。したがって、リチウムバナジウム酸化物を層状固溶体に混合することにより、ＳＯＣが低い領域でリチウムバナジウム酸化物とＬｉとが反応できるため、放電末期の抵抗を低減できる。その結果、出力の高いリチウムイオン二次電池を提供できる。 The inventors have found that the resistance in a low SOC region can be reduced by using a layered solid solution and a lithium vanadium oxide that absorbs and releases Li at about 3.5 V in the positive electrode material. Lithium vanadium oxide reacts with Li near 3.5V. Therefore, by mixing lithium vanadium oxide into a layered solid solution, lithium vanadium oxide and Li can react in a region where the SOC is low, so that the resistance at the end of discharge can be reduced. As a result, a high output lithium ion secondary battery can be provided.
　本発明に係るリチウムイオン二次電池用正極材料は、組成式ＬｉxＮｉaＭｎ0.8-a-bＭbＯ2+δ（０．９５≦ｘ≦１．２、０．２≦ａ≦０．４、０≦ｂ＜０．０２、－１≦δ≦１、Ｍは、Ｍｏ、Ｗ、Ｚｒ、Ｎｂ、Ｔｉ、Ｆｅ、Ｃｕから選択される少なくともいずれかの元素である。）で表されるリチウム遷移金属酸化物と、リチウムバナジウム酸化物とを、混合状態で含むことを特徴とする。 The positive electrode material for a lithium ion secondary battery according to the present invention has a composition formula Li x Ni a Mn 0.8-ab M b O 2 + δ (0.95 ≦ x ≦ 1.2, 0.2 ≦ a ≦ 0.4). , 0 ≦ b <0.02, −1 ≦ δ ≦ 1, and M is at least one element selected from Mo, W, Zr, Nb, Ti, Fe, and Cu. It contains transition metal oxide and lithium vanadium oxide in a mixed state.
　組成式におけるｘはＬｉ量を示し、０．９５未満であると、反応に寄与するＬｉの量が減り高容量が得られない。一方、１．２より大きいと、結晶格子が不安定になり放電容量が低下する。 X in the composition formula represents the amount of Li, and if it is less than 0.95, the amount of Li contributing to the reaction is reduced and a high capacity cannot be obtained. On the other hand, if it is larger than 1.2, the crystal lattice becomes unstable and the discharge capacity decreases.
　組成式におけるaはＮｉ量を示し、０．２未満であると、反応に寄与するＮｉの量が減り高容量が得られない。一方、０．４より大きいと、Ｎｉの価数が高くなり、Ｎｉが関与した充放電容量が低減し、高容量が得られない。 A in the composition formula indicates the amount of Ni, and if it is less than 0.2, the amount of Ni contributing to the reaction decreases and a high capacity cannot be obtained. On the other hand, when it is larger than 0.4, the valence of Ni increases, the charge / discharge capacity involving Ni decreases, and a high capacity cannot be obtained.
　組成式におけるδは、酸素量を示す。本値は、Ｌｉ、Ｎｉ、Ｍｎの比が決まると、それに合わせて決まるが、多少の不定比性があっても良い。 Δ in the composition formula represents the amount of oxygen. This value is determined in accordance with the ratio of Li, Ni, and Mn, but may have some non-stoichiometry.
　組成式におけるＭは、本発明に影響のない範囲で適宜加えられる添加物や不純物であり、Ｍｏ、Ｗ、Ｚｒ、Ｎｂ、Ｔｉ、Ｆｅ、Ｃｕから選択される少なくともいずれかの元素である。 M in the composition formula is an additive or impurity that is appropriately added within a range not affecting the present invention, and is at least one element selected from Mo, W, Zr, Nb, Ti, Fe, and Cu.
　リチウム遷移金属酸化物は主にＬｉ、Ｎｉ、及びＭｎから構成されているため、Ｃｏを多く含んでいる正極活物質より低コストであるという利点を有する。 Since the lithium transition metal oxide is mainly composed of Li, Ni, and Mn, it has an advantage that the cost is lower than that of the positive electrode active material containing a large amount of Co.
　正極材料中のＮｉ、Ｍｎ、Ｍに対するＶの原子比（Ｖ／（Ｎｉ＋Ｍｎ＋Ｍ））は、０．０１／０．８以上０．０６／０．８未満であることが好ましい。Ｖ／（Ｎｉ＋Ｍｎ＋Ｍ）を０．０６／０．８未満とすることによって、高容量化を維持し、かつ放電末期での抵抗上昇を抑制することができる。Ｖ／（Ｎｉ＋Ｍｎ＋Ｍ）が０．０６／０．８以上となると、バナジウムと反応するリチウム量が多くなり、正極の容量が低下し、かつ抵抗が上昇するおそれがある。また、高い放電容量を維持するためには、Ｖ／（Ｎｉ＋Ｍｎ＋Ｍ）を０．０２／０．８以下とすることが好ましい。 The atomic ratio of V to Ni, Mn, and M (V / (Ni + Mn + M)) in the positive electrode material is preferably 0.01 / 0.8 or more and less than 0.06 / 0.8. By setting V / (Ni + Mn + M) to less than 0.06 / 0.8, it is possible to maintain a high capacity and suppress an increase in resistance at the end of discharge. When V / (Ni + Mn + M) is 0.06 / 0.8 or more, the amount of lithium that reacts with vanadium increases, the capacity of the positive electrode may decrease, and the resistance may increase. In order to maintain a high discharge capacity, it is preferable to set V / (Ni + Mn + M) to 0.02 / 0.8 or less.
　また、リチウム遷移金属酸化物とリチウムバナジウム酸化物を混合状態で含む正極材料を用いることで、電極密度を向上できる。これは、リチウムバナジウム酸化物の粒子径がリチウム遷移金属酸化物と比べて小さく、粒子径の異なる粒子を混合できるためである。 Moreover, the electrode density can be improved by using a positive electrode material containing a lithium transition metal oxide and a lithium vanadium oxide in a mixed state. This is because the particle size of the lithium vanadium oxide is smaller than that of the lithium transition metal oxide, and particles having different particle sizes can be mixed.
　粒子状態については、リチウム遷移金属酸化物の一次粒子とリチウムバナジウム酸化物が混合していることが好ましい。さらに、リチウムバナジウム酸化物は、リチウム遷移金属酸化物の一次粒子表面に固着していることが好ましい。リチウム遷移金属酸化物の一次粒子とリチウムバナジウム酸化物とが混合することによって、リチウム遷移金属酸化物粒子間の電子伝導を高めることができる。一方、リチウム遷移金属酸化物の二次粒子とリチウムバナジウム酸化物とを混合した場合、二次粒子と導電材の間の電子伝導パスを構築できるが、二次粒子内部のリチウム遷移金属酸化物粒子同士の電子伝導を高めることはできない。なお、正極材料の粒子状態は、走査型電子顕微鏡－エネルギー分散型Ｘ線分析（ＳＥＭ－ＥＤＸ）にて確認できる。 Regarding the particle state, primary particles of lithium transition metal oxide and lithium vanadium oxide are preferably mixed. Furthermore, the lithium vanadium oxide is preferably fixed to the primary particle surface of the lithium transition metal oxide. By mixing primary particles of lithium transition metal oxide and lithium vanadium oxide, electronic conduction between the lithium transition metal oxide particles can be enhanced. On the other hand, when secondary particles of lithium transition metal oxide and lithium vanadium oxide are mixed, an electron conduction path between the secondary particles and the conductive material can be constructed, but the lithium transition metal oxide particles inside the secondary particles The electronic conduction between them cannot be increased. The particle state of the positive electrode material can be confirmed by a scanning electron microscope-energy dispersive X-ray analysis (SEM-EDX).
　本発明に係る正極材料は、本発明の属する技術分野において一般的に使用されている方法で作製することができる。例えば、Ｌｉ、Ｎｉ、Ｍｎをそれぞれ含む化合物を適当な比率で混合し、焼成することによりリチウム遷移金属酸化物を作製した後、得られたリチウム遷移金属酸化物に、Ｖを含む化合物を適当な比率で混合し、８５０～１０５０℃で焼成することにより作製できる。混合する化合物の比率を変化させることにより、正極材料の組成を適宜調節することができる。また、Ｌｉ、Ｎｉ、Ｍｎ及びＶをそれぞれ含む化合物を適当な比率で混合し、焼成することにより作製してもよい。リチウム遷移酸化物がＣｏを含まない場合は、リチウム遷移金属酸化物の原料を混合する段階でバナジウム化合物を混合し、焼成することにより作製しても、バナジウムはリチウム遷移金属酸化物にほとんど固溶していないことがＸ線回折測定により確認できた。 The positive electrode material according to the present invention can be produced by a method generally used in the technical field to which the present invention belongs. For example, after preparing a lithium transition metal oxide by mixing a compound containing each of Li, Ni, and Mn at an appropriate ratio and firing, a compound containing V is appropriately added to the obtained lithium transition metal oxide. It can be produced by mixing at a ratio and firing at 850 to 1050 ° C. The composition of the positive electrode material can be appropriately adjusted by changing the ratio of the compound to be mixed. Moreover, you may produce by mixing the compound containing each of Li, Ni, Mn, and V in a suitable ratio, and baking. When the lithium transition oxide does not contain Co, vanadium is almost dissolved in the lithium transition metal oxide even if it is prepared by mixing and firing the vanadium compound at the stage of mixing the lithium transition metal oxide raw material. This was confirmed by X-ray diffraction measurement.
　Ｌｉを含有する化合物としては、例えば、酢酸リチウム、硝酸リチウム、炭酸リチウム、水酸化リチウム、酸化リチウム等を挙げることができる。Ｎｉを含有する化合物としては、例えば、酢酸ニッケル、硝酸ニッケル、炭酸ニッケル、硫酸ニッケル、水酸化ニッケル等を挙げることができる。Ｍｎを含有する化合物としては、例えば、酢酸マンガン、硝酸マンガン、炭酸マンガン、硫酸マンガン、酸化マンガン等を挙げることができる。Ｖを含有する化合物としては、例えば、酸化バナジウム、窒化バナジウム、ほう化バナジウム等を挙げることができる。 Examples of the compound containing Li include lithium acetate, lithium nitrate, lithium carbonate, lithium hydroxide, and lithium oxide. Examples of the Ni-containing compound include nickel acetate, nickel nitrate, nickel carbonate, nickel sulfate, and nickel hydroxide. Examples of the compound containing Mn include manganese acetate, manganese nitrate, manganese carbonate, manganese sulfate, manganese oxide, and the like. Examples of the compound containing V include vanadium oxide, vanadium nitride, and vanadium boride.
　正極材料中のリチウム遷移金属酸化物の組成、正極材料中のＶの量は、例えば誘導結合プラズマ法（ＩＣＰ）等による元素分析により決定することができる。 The composition of the lithium transition metal oxide in the positive electrode material and the amount of V in the positive electrode material can be determined by elemental analysis by, for example, inductively coupled plasma method (ICP).
　＜リチウムイオン二次電池＞
　本発明に係るリチウムイオン二次電池は、上記の正極材料を含むことを特徴とする。上記の正極材料を正極に使用することにより、高容量を維持し、出力の高いリチウムイオン二次電池とすることができる。本発明に係るリチウムイオン二次電池は、例えば、電気自動車に対して好ましく使用することができる。 <Lithium ion secondary battery>
A lithium ion secondary battery according to the present invention includes the above positive electrode material. By using the above positive electrode material for the positive electrode, a high capacity lithium ion secondary battery can be maintained while maintaining a high capacity. The lithium ion secondary battery according to the present invention can be preferably used for, for example, an electric vehicle.
　正極活物質は、充放電により、リチウムイオンを吸蔵放出する。正極活物質から放出されたリチウムイオンはすべて正極に戻るわけではないため、充放電後における正極活物質の組成は、充放電前とは異なることが予想される。例えば、ＬｉＭＯ2で表される層状化合物の正極活物質は、２．５～４．３Ｖの電位範囲で使用したときに、満放電状態（２．５Ｖ）でＬｉの組成比が０．７５程度となることが分かっている。層状化合物と同様に考えると、層状固溶体の充放電後のＬｉの量も、充放電前と比較して満放電状態で１５～３０％程度減少していると推測される。したがって、本発明に係る正極活物質を用いてリチウム二次電池を作製し、４．６から２．５Ｖで充放電した場合、満放電（２．５Ｖにおける）状態では、層状固溶体正極活物質の組成は、ＬｉxＮｉaＭｎ0.8-a―bＭbＯ2+δ（０．８０≦ｘ≦１．２、０．２≦ａ≦０．４、－１≦δ≦１）となると想定できる。したがって、つまり、本発明に係る充放電後のリチウム遷移金属酸化物は、０．０９０＜Ｌｉ／金属元素＜１．５を満たす。 The positive electrode active material occludes and releases lithium ions by charging and discharging. Since all lithium ions released from the positive electrode active material do not return to the positive electrode, the composition of the positive electrode active material after charge / discharge is expected to be different from that before charge / discharge. For example, the layered compound positive electrode active material represented by LiMO 2 has a Li composition ratio of about 0.75 in a fully discharged state (2.5 V) when used in a potential range of 2.5 to 4.3 V. I know that When considered similarly to the layered compound, it is estimated that the amount of Li after charge / discharge of the layered solid solution is also reduced by about 15 to 30% in the full discharge state compared to before charge / discharge. Therefore, when a lithium secondary battery is manufactured using the positive electrode active material according to the present invention and charged and discharged at 4.6 to 2.5 V, the layered solid solution positive electrode active material is not fully charged (at 2.5 V). The composition is assumed to be Li x Ni a Mn 0.8-a-b M b O 2 + δ (0.80 ≦ x ≦ 1.2, 0.2 ≦ a ≦ 0.4, −1 ≦ δ ≦ 1). it can. That is, the lithium transition metal oxide after charge / discharge according to the present invention satisfies 0.090 <Li / metal element <1.5.
　リチウムイオン二次電池は、正極材料を含む正極、負極材料を含む負極、セパレータ、電解液、電解質等から構成される。 A lithium ion secondary battery includes a positive electrode including a positive electrode material, a negative electrode including a negative electrode material, a separator, an electrolytic solution, an electrolyte, and the like.
　負極材料は、リチウムイオンを吸蔵放出することができる物質であれば特に限定されない。リチウムイオン二次電池において一般的に使用されている物質を負極材料として使用することができる。例えば、黒鉛、リチウム合金等を例示することができる。 The negative electrode material is not particularly limited as long as it is a substance that can occlude and release lithium ions. Substances generally used in lithium ion secondary batteries can be used as the negative electrode material. For example, graphite, a lithium alloy, etc. can be illustrated.
　セパレータとしては、リチウムイオン二次電池において一般的に使用されているものを使用することができる。例えば、ポリプロピレン、ポリエチレン、プロピレンとエチレンとの共重合体等のポリオレフィン製の微孔性フィルムや不織布等を例示することができる。 As the separator, those generally used in lithium ion secondary batteries can be used. Examples thereof include polyolefin microporous films and nonwoven fabrics such as polypropylene, polyethylene, and a copolymer of propylene and ethylene.
　電解液及び電解質としては、リチウムイオン二次電池において一般的に使用されているものを使用することができる。例えば、電解液として、ジエチルカーボネート、ジメチルカーボネート、エチレンカーボネート、プロピレンカーボネート、ビニレンカーボネート、メチルアセテート、エチルメチルカーボネート、メチルプロピルカーボネート、ジメトキシエタン等を例示することができる。また、電解質として、ＬｉＣｌＯ4、ＬｉＰＦ6、ＬｉＢＦ4、ＬｉＡｓＦ6、ＬｉＳｂＦ6、ＬｉＣＦ3ＳＯ3、ＬｉＣ4Ｆ9ＳＯ3、ＬｉＣＦ3ＣＯ2、Ｌｉ2Ｃ2Ｆ4（ＳＯ3）2、ＬｉＮ（ＣＦ3ＳＯ2）2、ＬｉＣ（ＣＦ3ＳＯ2）3等を例示することができる。 As the electrolytic solution and the electrolyte, those generally used in lithium ion secondary batteries can be used. For example, diethyl carbonate, dimethyl carbonate, ethylene carbonate, propylene carbonate, vinylene carbonate, methyl acetate, ethyl methyl carbonate, methyl propyl carbonate, dimethoxyethane and the like can be exemplified as the electrolytic solution. Further, as the electrolyte, LiClO 4 , LiPF 6 , LiBF 4 , LiAsF 6 , LiSbF 6 , LiCF 3 SO 3 , LiC 4 F 9 SO 3 , LiCF 3 CO 2 , Li 2 C 2 F 4 (SO 3 ) 2 , LiN Examples thereof include (CF 3 SO 2 ) 2 and LiC (CF 3 SO 2 ) 3 .
　本発明に係るリチウムイオン二次電池の構造の一実施形態を、図２を用いて説明するリチウムイオン二次電池１２は、集電体の両面に正極活物質を塗布した正極３と、集電体の両面に負極材料を塗布した負極４と、セパレータ５とを有する電極群を備える。正極３及び負極４は、セパレータ５を介して捲回され、捲回体の電極群を形成している。この捲回体は電池缶６に挿入される。 An embodiment of the structure of a lithium ion secondary battery according to the present invention will be described with reference to FIG. 2. A lithium ion secondary battery 12 includes a positive electrode 3 in which a positive electrode active material is applied on both sides of a current collector, a current collector The electrode group which has the negative electrode 4 which apply | coated the negative electrode material on both surfaces of the body, and the separator 5 is provided. The positive electrode 3 and the negative electrode 4 are wound through a separator 5 to form a wound electrode group. This wound body is inserted into the battery can 6.
　負極６は、負極リード片８を介して、電池缶６に電気的に接続される。電池缶６には、パッキン１０を介して、密閉蓋９が取り付けられる。正極３は、正極リード片７を介して、密閉蓋９に電気的に接続される。捲回体は、絶縁板１１によって絶縁される。 The negative electrode 6 is electrically connected to the battery can 6 through the negative electrode lead piece 8. A sealing lid 9 is attached to the battery can 6 via a packing 10. The positive electrode 3 is electrically connected to the sealing lid 9 via the positive electrode lead piece 7. The wound body is insulated by the insulating plate 11.
　なお、電極群は、図２に示す捲回体でなくてもよく、セパレータ５を介して正極３と負極４とを積層した積層体でもよい。 The electrode group may not be the wound body shown in FIG. 2, but may be a laminated body in which the positive electrode 3 and the negative electrode 4 are laminated via the separator 5.
　以下、実施例及び比較例を用いて本発明をより詳細に説明するが、本発明の技術的範囲はこれに限定されるものではない。 Hereinafter, the present invention will be described in more detail using examples and comparative examples, but the technical scope of the present invention is not limited thereto.
　＜正極材料の作製＞
　実施例１～７、比較例２の正極材料を以下の方法で作製した。炭酸リチウム、炭酸ニッケル、炭酸マンガン及び、酸化バナジウムをボールミルで混合し、得られた混合物を大気中において５００℃で１２時間焼成し、リチウム遷移金属酸化物を得た。得られたリチウム遷移金属酸化物をペレット化した後、大気中において８５０～１０５０℃で１２時間焼成した。焼成したペレットをメノウ乳鉢で粉砕し、４５μｍのふるいで分級し、正極材料とした。得られた正極材料には、Ｌｉ、Ｎｉ、Ｍｎを含むリチウム遷移金属酸化物と、Ｌｉ、Ｖを含むリチウムバナジウム酸化物とが含まれていることがＸ線回折分析により確認された。 <Preparation of positive electrode material>
The positive electrode materials of Examples 1 to 7 and Comparative Example 2 were produced by the following method. Lithium carbonate, nickel carbonate, manganese carbonate, and vanadium oxide were mixed with a ball mill, and the resulting mixture was baked in the atmosphere at 500 ° C. for 12 hours to obtain a lithium transition metal oxide. The obtained lithium transition metal oxide was pelletized and then fired at 850 to 1050 ° C. for 12 hours in the air. The fired pellets were pulverized in an agate mortar and classified with a 45 μm sieve to obtain a positive electrode material. It was confirmed by X-ray diffraction analysis that the obtained positive electrode material contained a lithium transition metal oxide containing Li, Ni, and Mn and a lithium vanadium oxide containing Li and V.
　比較例１、６～９の正極材料は、添加元素を含む化合物を混合しなかったこと以外は、実施例１と同様に作製した。 The positive electrode materials of Comparative Examples 1 and 6 to 9 were prepared in the same manner as in Example 1 except that the compound containing the additive element was not mixed.
　比較例３の正極材料は、酸化バナジウムを酸化マグネシウムに変更したこと以外は、実施例１と同様に作製した。Ｘ線回折測定により、添加元素であるマグネシウムは、リチウム遷移金属酸化物中に固溶していることが確認できた。 The positive electrode material of Comparative Example 3 was prepared in the same manner as in Example 1 except that vanadium oxide was changed to magnesium oxide. From the X-ray diffraction measurement, it was confirmed that the additive element magnesium was dissolved in the lithium transition metal oxide.
　比較例４の正極材料は、酸化バナジウムを酸化アルミニウムとしたこと以外は、実施例１と同様に作製した。Ｘ線回折測定により、添加元素であるアルミニウムは、リチウム遷移金属酸化物中に固溶していることが確認できた。 The positive electrode material of Comparative Example 4 was prepared in the same manner as in Example 1 except that vanadium oxide was changed to aluminum oxide. By X-ray diffraction measurement, it was confirmed that aluminum as an additive element was dissolved in the lithium transition metal oxide.
　比較例５の正極材料は、以下の方法で作製した。炭酸リチウム、炭酸ニッケル、及び炭酸マンガンをボールミルで混合し、得られた混合物を大気中において５００℃で１２時間焼成し、リチウム遷移金属酸化物を得た。得られたリチウム遷移金属酸化物をペレット化した後、大気中において８５０～１０５０℃で１２時間焼成した。焼成したペレットをメノウ乳鉢で粉砕し、４５μｍのふるいで分級した。その後、酸化バナジウムを溶解させた、クエン酸水溶液中にリチウム遷移金属酸化物を加え、１２０℃で攪拌しながら水分を蒸発させた。その後、２００℃で加熱することで、リチウム遷移金属酸化物にバナジウム酸化物が被覆した正極材料を得た。 The positive electrode material of Comparative Example 5 was produced by the following method. Lithium carbonate, nickel carbonate, and manganese carbonate were mixed with a ball mill, and the resulting mixture was fired at 500 ° C. for 12 hours in the air to obtain a lithium transition metal oxide. The obtained lithium transition metal oxide was pelletized and then fired at 850 to 1050 ° C. for 12 hours in the air. The fired pellets were pulverized in an agate mortar and classified with a 45 μm sieve. Thereafter, a lithium transition metal oxide was added to an aqueous citric acid solution in which vanadium oxide was dissolved, and water was evaporated while stirring at 120 ° C. Then, the positive electrode material which vanadium oxide coat | covered the lithium transition metal oxide was obtained by heating at 200 degreeC.
　各実施例及び比較例において使用した正極材料を表１～５に示す。なお、リチウム遷移金属酸化物の組成はＬｉxＮｉaＭｎ0.8-a―bＭbＯ2+δで表記した。 The positive electrode materials used in the examples and comparative examples are shown in Tables 1 to 5. The composition of the lithium transition metal oxide was expressed as Li x Ni a Mn 0.8-a- b MbO 2 + δ .
　＜試作電池の作製＞
　各実施例及び比較例の正極材料を用い、上述のように作製した１６種類の正極材料を用いて正極を作製し、１６種類の試作電池を作製した。 <Production of prototype battery>
Using the positive electrode materials of the examples and comparative examples, positive electrodes were manufactured using 16 types of positive electrode materials prepared as described above, and 16 types of prototype batteries were manufactured.
　正極材料と導電剤とバインダとを均一に混合して正極スラリーを作製した。正極スラリーを厚み２０μｍのアルミ集電体箔上に塗布し、１２０℃で乾燥し、プレスにて電極密度が２．２ｇ／ｃｍ3になるように圧縮成形して電極板を得た。その後、電極板を直径１５ｍｍの円盤状に打ち抜き、正極を作製した。 A positive electrode slurry, a conductive agent, and a binder were mixed uniformly to prepare a positive electrode slurry. The positive electrode slurry was applied onto an aluminum current collector foil having a thickness of 20 μm, dried at 120 ° C., and compression-molded with a press so that the electrode density was 2.2 g / cm 3 to obtain an electrode plate. Thereafter, the electrode plate was punched into a disk shape having a diameter of 15 mm to produce a positive electrode.
　負極は金属リチウムを用いて作製した。非水電解液としては、体積比１：２のエチレンカーボネートとジメチルカーボネートとの混合溶媒に、ＬｉＰＦ6を１．０ｍｏｌ／Ｌの濃度で溶解させたものを用いた。 The negative electrode was produced using metallic lithium. As the non-aqueous electrolyte, a solution obtained by dissolving LiPF 6 at a concentration of 1.0 mol / L in a mixed solvent of ethylene carbonate and dimethyl carbonate having a volume ratio of 1: 2 was used.
　＜充放電試験＞
　充放電試験は、以下のように行った。試作電池に対し、充電は０．０５Ｃ相当の電流で上限電圧を４．６Ｖ、放電は０．０５Ｃ相当の電流で下限電圧を２．５Ｖとした充放電試験を２サイクル行い、２サイクル目における４．６－３．４Ｖの範囲で得られた放電容量を、定格容量と定義した。これらの放電容量を表１～５に示す。 <Charge / discharge test>
The charge / discharge test was performed as follows. The prototype battery was charged and discharged at a current equivalent to 0.05 C with an upper limit voltage of 4.6 V, and discharged at a current equivalent to 0.05 C with a lower limit voltage of 2.5 V. The discharge capacity obtained in the range of 4.6-3.4V was defined as the rated capacity. These discharge capacities are shown in Tables 1 to 5.
　＜直流抵抗（ＤＣＲ）の測定＞
　試作電池に対して、以下のように直流抵抗を求めた。試作電池に対し、充電は０．０５Ｃ相当の電流で上限電圧を４．６Ｖ、放電は０．０５Ｃ相当の電流で下限電圧を２．５Ｖとした充放電試験を行い、２サイクル目の放電容量を定格容量とした。２サイクル後の試作電池を４．６Ｖまで充電し、その後、定格容量の７０％の容量を放電した。その後、１．２ｍＡの電流を１０秒間印加し、ＳＯＣ３０％のときの直流抵抗を測定した。電流印加前と電流を１０秒間印加した後の電位差を、印加した電流値（１．２ｍＡ）で割った値を直流抵抗値と定義した。これらの直流抵抗を表１～５に示す。 <Measurement of direct current resistance (DCR)>
The DC resistance was determined for the prototype battery as follows. The prototype battery was charged and discharged at a current equivalent to 0.05C with an upper limit voltage of 4.6V, and discharged at a current equivalent to 0.05C with a lower limit voltage of 2.5V. Was the rated capacity. The prototype battery after 2 cycles was charged to 4.6 V, and then 70% of the rated capacity was discharged. Thereafter, a current of 1.2 mA was applied for 10 seconds, and the direct current resistance when the SOC was 30% was measured. A value obtained by dividing the potential difference before applying the current and after applying the current for 10 seconds by the applied current value (1.2 mA) was defined as the DC resistance value. These DC resistances are shown in Tables 1-5.
　図３に、放電方向にＳＯＣを変化させたときの、実施例１と比較例１におけるＳＯＣと直流抵抗値の関係を表すグラフを示す。図３において、1３は実施例１のＳＯＣに対する直流抵抗値をプロットしたものであり、１４は比較例１のＳＯＣに対する直流抵抗値をプロットしたものである。図３より、リチウム遷移金属酸化物とリチウムバナジウム酸化物とを含む実施例１では、ＳＯＣが２０～４０％の領域で、リチウム遷移金属酸化物のみの比較例１よりもＤＣＲが低くなることが分かった。この結果より、リチウム遷移金属酸化物とリチウムバナジウム酸化物を混合状態で含む正極材料を用いることにより、放電末期の抵抗を低減できることが分かった。また、実施例２～７についても、実施例１と同様なグラフが得られた。したがって、実施例１～７の正極材料を用いることによって、リチウムイオン二次電池の高容量を維持したまま出力を向上できる。 FIG. 3 shows a graph showing the relationship between the SOC and the DC resistance value in Example 1 and Comparative Example 1 when the SOC is changed in the discharge direction. In FIG. 3, 13 is a plot of the DC resistance value against the SOC of Example 1, and 14 is a plot of the DC resistance value against the SOC of Comparative Example 1. From FIG. 3, it can be seen that in Example 1 including lithium transition metal oxide and lithium vanadium oxide, the DCR is lower than that in Comparative Example 1 where only the lithium transition metal oxide is present in the SOC range of 20 to 40%. I understood. From this result, it was found that the resistance at the end of discharge can be reduced by using a positive electrode material containing a lithium transition metal oxide and a lithium vanadium oxide in a mixed state. Also, the same graphs as in Example 1 were obtained for Examples 2 to 7. Therefore, by using the positive electrode materials of Examples 1 to 7, the output can be improved while maintaining the high capacity of the lithium ion secondary battery.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１に示すように、比較例１と比較して、実施例１～３では放電容量の低下を５％以内に抑え、ＳＯＣ３０％における直流抵抗を低減できた。一方、比較例２では、比較例１と比して、放電容量が９％低下し、直流抵抗が上昇した。これは、正極材料中のＮｉ、Ｍｎ、Ｍに対するバナジウムの原子比が０．０６／０．８と高いために、放電容量が低下し、また、大量のバナジウムとＬｉが反応したことで正極材料中からＬｉが引き抜かれ抵抗が増加したためであると考えられる。比較例３、４では、実施例１～３と比して、放電容量が低下し、直流抵抗が上昇した。比較例３、４では、添加した元素が反応に関与しないＭｇまたはＡｌであり、かつ、リチウム遷移金属酸化物中に固溶したために、放電容量の低下、直流抵抗の上昇を招いた。比較例５では、放電容量、直流抵抗ともに大きな変化がなかった。これは、比較例５の正極材料がリチウム遷移金属酸化物の合成後に酸化バナジウムを混合し、低い加熱温度で被覆したものであり、正極内で酸化バナジウムが孤立して反応に関与しなかったためである。 As shown in Table 1, compared with Comparative Example 1, in Examples 1 to 3, the decrease in discharge capacity was suppressed to within 5%, and the DC resistance at SOC 30% could be reduced. On the other hand, in Comparative Example 2, compared to Comparative Example 1, the discharge capacity was reduced by 9% and the DC resistance was increased. This is because the atomic ratio of vanadium to Ni, Mn, and M in the positive electrode material is as high as 0.06 / 0.8, so that the discharge capacity is reduced, and a large amount of vanadium and Li are reacted to produce the positive electrode material. This is probably because Li was pulled out from the inside and the resistance increased. In Comparative Examples 3 and 4, compared with Examples 1 to 3, the discharge capacity decreased and the DC resistance increased. In Comparative Examples 3 and 4, since the added element was Mg or Al not involved in the reaction and was dissolved in the lithium transition metal oxide, the discharge capacity and the direct current resistance were increased. In Comparative Example 5, there was no significant change in both discharge capacity and DC resistance. This is because the positive electrode material of Comparative Example 5 was prepared by mixing vanadium oxide after the synthesis of the lithium transition metal oxide and coating at a low heating temperature, and vanadium oxide was isolated in the positive electrode and did not participate in the reaction. is there.
　特に実施例１、２では放電容量の低下が小さく、直流抵抗が４０Ω以下であった。これは、実施例１、２の正極材料が、Ｎｉ、Ｍｎ、Ｍに対するバナジウムの原子比が０．０２／０．８以下であったためである。 Particularly in Examples 1 and 2, the decrease in discharge capacity was small, and the DC resistance was 40Ω or less. This is because in the positive electrode materials of Examples 1 and 2, the atomic ratio of vanadium to Ni, Mn, and M was 0.02 / 0.8 or less.
　以上のように、リチウム遷移金属酸化物と、リチウムバナジウム酸化物を含み、正極材料中のＮｉ、Ｍｎ、Ｍに対するバナジウムの原子比が０．０１／０．８以上０．０６／０．８未満である正極材料を用いることにより、高い放電容量を維持し、かつＳＯＣが低い領域における直流抵抗を低減できる。その結果、高容量かつ高出力のリチウムイオン二次電池を提供できる。 As described above, the atomic ratio of vanadium to Ni, Mn, and M in the positive electrode material including the lithium transition metal oxide and the lithium vanadium oxide is 0.01 / 0.8 or more and less than 0.06 / 0.8. By using the positive electrode material, it is possible to maintain a high discharge capacity and reduce DC resistance in a region where the SOC is low. As a result, a high-capacity and high-power lithium ion secondary battery can be provided.
　リチウム遷移金属酸化物の組成がＬｉ1.1Ｎｉ0.3Ｍｎ0.5Ｏ2とは異なる場合について、表２～５を用いて説明する。 The case where the composition of the lithium transition metal oxide is different from that of Li 1.1 Ni 0.3 Mn 0.5 O 2 will be described with reference to Tables 2 to 5.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表２より、組成式Ｌｉ1.2Ｎｉ0.2Ｍｎ0.6Ｏ2で表されるリチウム遷移金属酸化物についても、リチウムバナジウム酸化物を混合することによって、放電容量の低下を２％以内に抑え、直流抵抗を低減できることが分かった。 From Table 2, the lithium transition metal oxide represented by the composition formula Li 1.2 Ni 0.2 Mn 0.6 O 2 is also mixed with lithium vanadium oxide to suppress the decrease in discharge capacity to within 2%, and the DC resistance is reduced. It was found that it can be reduced.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　表３より、組成式Ｌｉ1.1Ｎｉ0.25Ｍｎ0.55Ｏ2で表されるリチウム遷移金属酸化物についても、リチウムバナジウム酸化物を混合することによって、放電容量の低下を３％以内に抑え、直流抵抗を低減できることが分かった。 From Table 3, the lithium transition metal oxide represented by the composition formula Li 1.1 Ni 0.25 Mn 0.55 O 2 is also mixed with lithium vanadium oxide, thereby suppressing the decrease in discharge capacity to within 3% and reducing the DC resistance. It was found that it can be reduced.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　表４より、組成式ＬｉＮｉ0.35Ｍｎ0.45Ｏ2で表されるリチウム遷移金属酸化物についても、リチウムバナジウム酸化物を混合することによって、放電容量の低下を３％以内に抑え、直流抵抗を低減できることが分かった。 From Table 4, the lithium transition metal oxide represented by the composition formula LiNi 0.35 Mn 0.45 O 2 can also suppress the decrease in discharge capacity to within 3% and reduce the DC resistance by mixing lithium vanadium oxide. I understood.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
　表５より、組成式Ｌｉ0.95Ｎｉ0.4Ｍｎ0.4Ｏ2で表されるリチウム遷移金属酸化物についても、リチウムバナジウム酸化物を混合することによって、放電容量の低下を３％以内に抑え、直流抵抗を低減できた。 From Table 5, the lithium transition metal oxide represented by the composition formula Li 0.95 Ni 0.4 Mn 0.4 O 2 is also mixed with lithium vanadium oxide to suppress the decrease in discharge capacity within 3%, and the DC resistance is reduced. Reduced.
　また、実施例１、４～７を比較すると、実施例１、５、６は、放電容量が１７５Ａｈ／ｋｇ以上と高く、ＤＣＲが４０Ω以下と低い。これは、実施例１、５、６の正極材料に含まれるリチウム遷移金属酸化物の組成が０．２５≦ａ≦０．３５を満たすためである。リチウム遷移金属酸化物のＮｉ、Ｍｎの組成比を調整することによって、より放電容量が高く、ＤＣＲの低い正極材料とすることができる。 Further, comparing Examples 1, 4 to 7, Examples 1, 5, and 6 have a high discharge capacity of 175 Ah / kg or more and a low DCR of 40 Ω or less. This is because the composition of the lithium transition metal oxide contained in the positive electrode materials of Examples 1, 5, and 6 satisfies 0.25 ≦ a ≦ 0.35. By adjusting the composition ratio of Ni and Mn of the lithium transition metal oxide, a positive electrode material having a higher discharge capacity and a lower DCR can be obtained.
　以上のように、組成式ＬｉxＮｉaＭｎ0.8-a―bＭbＯ2+δ（０．９５≦ｘ≦１．２、０．２≦ａ≦０．４、０≦ｂ＜０．０２、－１≦δ≦１）で表されるリチウム遷移金属酸化物と、リチウムバナジウム酸化物とを混合状態で含み、Ｎｉ、Ｍｎ、Ｍに対するバナジウムの原子比が０．０１／０．８以上０．０６／０．８未満である正極材料を用いることにより、リチウム遷移金属酸化物のみの正極材料に対し、放電容量の低下を５％以内に抑え、放電末期の直流抵抗を低減できた。その結果、放電容量を維持するとともに、出力の高いリチウムイオン二次電池を提供できる。 As described above, the composition formula Li x Ni a Mn 0.8-a -b M b O 2 + δ (0.95 ≦ x ≦ 1.2,0.2 ≦ a ≦ 0.4,0 ≦ b <0. 02, −1 ≦ δ ≦ 1) and a lithium vanadium oxide in a mixed state, and the atomic ratio of vanadium to Ni, Mn, and M is 0.01 / 0.8 or more By using a positive electrode material of less than 0.06 / 0.8, the decrease in discharge capacity was suppressed to within 5%, and the direct current resistance at the end of discharge was reduced compared to the positive electrode material made of only lithium transition metal oxide. As a result, it is possible to provide a lithium ion secondary battery with high output while maintaining discharge capacity.
　１　放電方向にＳＯＣを変化させたときの層状固溶体の直流抵抗値
　２　充電方向にＳＯＣを変化させたときの層状固溶体の直流抵抗値
　３　正極
　４　負極
　５　セパレータ
　６　電池缶
　７　正極リード片
　８　負極リード片
　９　密閉蓋
　１０　パッキン
　１１　絶縁板
　１２　リチウムイオン二次電池
　１３　実施例１の直流抵抗値とＳＯＣの関係
　１４　比較例１の直流抵抗値とＳＯＣの関係 1 DC resistance value of layered solid solution when SOC is changed in discharge direction 2 DC resistance value of layered solid solution when SOC is changed in charge direction 3 Positive electrode 4 Negative electrode 5 Separator 6 Battery can 7 Positive electrode lead piece 8 Negative electrode lead Piece 9 Sealing lid 10 Packing 11 Insulating plate 12 Lithium ion secondary battery 13 Relationship between DC resistance value and SOC of Example 1 14 Relationship between DC resistance value and SOC of Comparative Example 1

Claims (9)

  1. 　組成式ＬｉxＮｉaＭｎ0.8-a―bＭbＯ2+δ（０．９５≦ｘ≦１．２、０．２≦ａ≦０．４、０≦ｂ＜０．０２、－１≦δ≦１、Ｍは、Ｍｏ、Ｗ、Ｚｒ、Ｎｂ、Ｔｉ、Ｆｅ、Ｃｕから選択される少なくともいずれかの元素である。）で表されるリチウム遷移金属酸化物と、リチウムバナジウム酸化物とを混合状態で含み、
    　Ｎｉ、Ｍｎ、Ｍに対するバナジウムの原子比（Ｖ／（Ｎｉ＋Ｍｎ＋Ｍ））は、０．０１／０．８以上０．０６／０．８未満であることを特徴とするリチウムイオン二次電池用正極材料。     The composition formula Li x Ni a Mn 0.8-a -b M b O 2 + δ (0.95 ≦ x ≦ 1.2,0.2 ≦ a ≦ 0.4,0 ≦ b <0.02, -1 ≦ δ ≦ 1, M is at least one element selected from Mo, W, Zr, Nb, Ti, Fe, and Cu.) and a lithium vanadium oxide Including in a mixed state,
    A positive electrode material for a lithium ion secondary battery, wherein the atomic ratio of vanadium to Ni, Mn, and M (V / (Ni + Mn + M)) is 0.01 / 0.8 or more and less than 0.06 / 0.8 .
  2. 　請求項１に記載のリチウムイオン二次電池用正極材料であって、
    　Ｎｉ、Ｍｎ、Ｍに対するバナジウムの原子比（Ｖ／（Ｎｉ＋Ｍｎ＋Ｍ））は、０．０２／０．８以下であることを特徴とするリチウムイオン二次電池用正極材料。     The positive electrode material for a lithium ion secondary battery according to claim 1,
    A positive electrode material for a lithium ion secondary battery, wherein the atomic ratio of vanadium to Ni, Mn, and M (V / (Ni + Mn + M)) is 0.02 / 0.8 or less.
  3. 　請求項１に記載のリチウムイオン二次電池用正極材料であって、
    　０．２５≦ａ≦０．３５を満たすことを特徴とするリチウムイオン二次電池用正極材料。     The positive electrode material for a lithium ion secondary battery according to claim 1,
    The positive electrode material for lithium ion secondary batteries characterized by satisfying 0.25 ≦ a ≦ 0.35.
  4. 　請求項１に記載のリチウムイオン二次電池用正極材料であって、
    　Ｌｉを含む化合物と、Ｎｉを含む化合物と、Ｍｎを含む化合物と、Ｖを含む化合物とを混合した後、焼成することによって製造されることを特徴とするリチウムイオン二次電池用正極材料。     The positive electrode material for a lithium ion secondary battery according to claim 1,
    A positive electrode material for a lithium ion secondary battery, which is produced by mixing a compound containing Li, a compound containing Ni, a compound containing Mn, and a compound containing V and then firing.
  5. 　請求項１ないし４のいずれかに記載のリチウムイオン二次電池用正極材料を含むリチウムイオン二次電池用正極。 A positive electrode for a lithium ion secondary battery comprising the positive electrode material for a lithium ion secondary battery according to any one of claims 1 to 4.
  6. 　リチウムイオンを吸蔵放出する正極材料を含む正極と、
    　リチウムイオンを吸蔵放出する負極材料を含む負極と、を備えるリチウムイオン二次電池であって、
    　前記正極材料は、組成式ＬｉxＮｉaＭｎ0.8-a―bＭbＯ2+δ（０．８０≦ｘ≦１．２、０．２≦ａ≦０．４、０≦ｂ＜０．０２、－１≦δ≦１、Ｍは、Ｍｏ、Ｗ、Ｚｒ、Ｎｂ、Ｔｉ、Ｆｅ、Ｃｕから選択される少なくともいずれかの元素である。）で表されるリチウム遷移金属酸化物と、リチウムバナジウム酸化物とを混合状態で含み、Ｎｉ、Ｍｎ、Ｍに対するバナジウムの原子比（Ｖ／（Ｎｉ＋Ｍｎ＋Ｍ））は、０．０１／０．８以上０．０６／０．８未満であることを特徴とするリチウムイオン二次電池。     A positive electrode comprising a positive electrode material that occludes and releases lithium ions;
    A negative electrode including a negative electrode material that occludes and releases lithium ions, and a lithium ion secondary battery comprising:
    The positive electrode material, the composition formula Li x Ni a Mn 0.8-a -b M b O 2 + δ (0.80 ≦ x ≦ 1.2,0.2 ≦ a ≦ 0.4,0 ≦ b <0. 02, −1 ≦ δ ≦ 1, M is at least one element selected from Mo, W, Zr, Nb, Ti, Fe, and Cu.) It contains vanadium oxide in a mixed state, and the atomic ratio of vanadium to Ni, Mn, and M (V / (Ni + Mn + M)) is 0.01 / 0.8 or more and less than 0.06 / 0.8. Lithium ion secondary battery.
  7. 　請求項６に記載のリチウムイオン二次電池であって、
    　前記正極材料中のＮｉ、Ｍｎ、Ｍに対するバナジウムの原子比（Ｖ／（Ｎｉ＋Ｍｎ＋Ｍ））は、０．０２／０．８以下であることを特徴とするリチウムイオン二次電池。     The lithium ion secondary battery according to claim 6,
    The lithium ion secondary battery, wherein an atomic ratio (V / (Ni + Mn + M)) of vanadium to Ni, Mn, and M in the positive electrode material is 0.02 / 0.8 or less.
  8. 　請求項６に記載のリチウムイオン二次電池であって、
    　前記リチウム遷移金属酸化物は、０．２５≦ａ≦０．３５を満たすことを特徴とするリチウムイオン二次電池。     The lithium ion secondary battery according to claim 6,
    The lithium transition metal oxide satisfies 0.25 ≦ a ≦ 0.35, wherein the lithium ion secondary battery.
  9. 　請求項６ないし８のいずれかに記載のリチウムイオン二次電池であって、
    　２．５Ｖ～４．６Ｖの電位範囲で使用されることを特徴とするリチウムイオン二次電池。     A lithium ion secondary battery according to any one of claims 6 to 8,
    A lithium ion secondary battery characterized by being used in a potential range of 2.5 V to 4.6 V.
PCT/JP2013/078641 2013-10-23 2013-10-23 Positive electrode material for lithium ion secondary batteries, and lithium ion secondary battery WO2015059779A1 (en)

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