WO2014155709A1 - Positive electrode material for lithium ion secondary batteries, positive electrode for lithium ion secondary batteries, and lithium ion secondary battery - Google Patents

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

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WO2014155709A1
WO2014155709A1 PCT/JP2013/059633 JP2013059633W WO2014155709A1 WO 2014155709 A1 WO2014155709 A1 WO 2014155709A1 JP 2013059633 W JP2013059633 W JP 2013059633W WO 2014155709 A1 WO2014155709 A1 WO 2014155709A1
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ion secondary
lithium ion
positive electrode
secondary battery
ocv
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PCT/JP2013/059633
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French (fr)
Japanese (ja)
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小西　宏明
章 軍司
孝亮 馮
翔 古月
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株式会社日立製作所
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Priority to PCT/JP2013/059633 priority Critical patent/WO2014155709A1/en
Priority to TW103103938A priority patent/TWI523304B/en
Publication of WO2014155709A1 publication Critical patent/WO2014155709A1/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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/52—Removing gases inside the secondary cell, e.g. by absorption
    • 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
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a positive electrode material for lithium ion secondary battery, a positive electrode for lithium ion secondary battery using the positive electrode material for lithium ion secondary battery, and a lithium ion secondary battery using the positive electrode for lithium ion secondary battery About.
  • Patent Document 1 discloses a lithium using a positive electrode material in which a lithium-containing transition metal oxide having a hexagonal layered rock salt type crystal structure belonging to the space group R-3m and a lithium manganese oxide having a spinel structure are mixed. An ion secondary battery is described.
  • the lithium ion secondary battery using the positive electrode material shown in Patent Document 1 can be expected to have a high capacity.
  • the inventors of the present invention have studied lithium ion secondary batteries using the positive electrode material of Patent Document 1 when charging from the full discharge state to the full charge state and when discharging from the full charge state to the full discharge state. It was found that there is a large difference in OCV (Open Circuit Voltage: Open Circuit Voltage) with respect to the state of charge (SOC). That is, since a large hysteresis exists in the lithium ion secondary battery using the positive electrode material of Patent Document 1, it is difficult to accurately detect the remaining capacity of the battery from the voltage.
  • OCV Open Circuit Voltage: Open Circuit Voltage
  • the positive electrode material for a lithium ion secondary battery of the present invention has a composition formula: Li 1.15 + x Ni 0.3 + y Mn 0.5-y O 2 [Wherein, x and y have the following relationship: -0.1 ⁇ x ⁇ 0.05, -0.1 ⁇ y ⁇ 0.1 Which is a parameter that satisfies
  • the positive electrode material for a lithium ion secondary battery of the present invention it is possible to provide a lithium ion secondary battery having a high capacity and capable of detecting a remaining capacity from a voltage with high accuracy.
  • FIG. 1 is a cross-sectional view schematically illustrating the structure of a lithium ion secondary battery.
  • FIG. 2 is a list showing the compositions of Examples and Comparative Examples.
  • FIG. 3 is a view showing measured values of OCV in the charging process and the discharging process of Example 1 and Comparative Example 1.
  • FIG. 4 is a list showing values of the discharge capacity ratio and the OCV ratio obtained for the example and the comparative example.
  • ⁇ Positive material for lithium ion secondary battery> When using a lithium ion secondary battery for an electric vehicle, it is required that the capacity is high and the distance that can be traveled by one charge is long. Further, in order to detect the remaining capacity of the battery from the voltage, it is desirable that the difference between the OCV in the charging process and the OCV in the discharging process be small. The smaller the difference between the OCV in the charging process and the OCV in the discharging process, the smaller the error in detecting the residual capacity of the battery from the OCV.
  • the positive electrode material for a lithium ion secondary battery according to the present invention has a composition formula: Li 1.15 + x Ni 0.3 + y Mn 0.5-y O 2 [Wherein, x and y have the following relationship: -0.1 ⁇ x ⁇ 0.05, -0.1 ⁇ y ⁇ 0.1 Which is a parameter that satisfies
  • x is a parameter indicating the range of the content ratio of Li (atomic weight ratio). If x is less than -0.1, a high capacity battery can not be obtained. It is considered that this is because the amount of Li contributing to the reaction is relatively small. Conversely, if x is greater than 0.05, the discharge capacity of the battery is reduced. It is considered that this is because the amount of Li relatively increases and the crystal lattice becomes unstable.
  • Y in the composition formula is a parameter indicating the range of the content ratio of Ni (atomic weight ratio).
  • y is ⁇ 0.1 or less, the difference between the OCV in the charging process and the OCV in the discharging process becomes large. This is considered to be due to the high contribution of oxygen to the charge and discharge reaction. Conversely, if y is larger than 0.1, high capacity can not be obtained. It is considered that this is because the contribution of Ni to the charge and discharge capacity decreases as the valence of Ni increases.
  • x and y in the above composition formula have the following relationship: ⁇ 0.1 ⁇ x ⁇ 0.05, ⁇ 0.1 ⁇ y ⁇ 0.05, It is preferable to satisfy
  • the positive electrode material for a lithium ion secondary battery of the present invention basically contains three elements of Li, Ni and Mn as a transition metal, and does not contain expensive Co. Since the positive electrode material for a lithium ion secondary battery of the present invention does not contain Co, it has an advantage of low cost. In addition, an additive etc. may be included in the positive electrode material in the range which does not affect this invention.
  • the positive electrode material for a lithium ion secondary battery 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, it can produce by mixing and baking the compound which each contains Li, Ni, and Mn in a suitable ratio.
  • the composition of the positive electrode material for a lithium ion secondary battery can be appropriately adjusted by changing the mixing ratio of the above compounds.
  • Examples of the compound containing Li include lithium acetate, lithium nitrate, lithium carbonate, lithium hydroxide, lithium oxide and the like.
  • Examples of the compound containing Ni include nickel acetate, nickel nitrate, nickel carbonate, nickel sulfate, nickel hydroxide and the like.
  • As a compound containing Mn, manganese acetate, manganese nitrate, manganese carbonate, manganese sulfate, manganese oxide etc. can be mentioned, for example.
  • composition of the positive electrode material for a lithium ion secondary battery can be analyzed by, for example, X-ray diffraction (XRD) or inductively coupled plasma (ICP).
  • XRD X-ray diffraction
  • ICP inductively coupled plasma
  • the positive electrode for a lithium ion secondary battery according to the present invention is manufactured using the above-described positive electrode material for a lithium ion secondary battery. As a result, the difference between the OCV in the charging process and the OCV in the discharging process is reduced, and the accuracy in detecting the battery remaining amount from the value of the OCV can be enhanced.
  • the lithium ion secondary battery according to the present invention is manufactured using the above-described positive electrode material for a lithium ion secondary battery. As a result, since the difference between the OCV in the charging process and the OCV in the discharging process is reduced, the lithium ion secondary battery with high accuracy of detecting the remaining capacity of the battery from the value of the OCV is obtained. It can be done.
  • the lithium ion secondary battery according to the present invention can be preferably used, for example, in electric vehicles and plug-in hybrid vehicles. It can also be used in power storage systems, power tools, toys, medical devices and the like.
  • the lithium ion secondary battery is composed of a positive electrode containing a positive electrode material, a negative electrode containing 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 capable of inserting and extracting lithium ions.
  • Materials generally used in lithium ion secondary batteries can be used as the negative electrode material.
  • graphite, lithium alloy and the like can be exemplified.
  • a separator those generally used in lithium ion secondary batteries can be used.
  • a microporous film or non-woven fabric made of a polyolefin such as polypropylene, polyethylene, and a copolymer of propylene and ethylene can be exemplified.
  • the electrolytic solution and the electrolyte those generally used in lithium ion secondary batteries can be used.
  • the electrolytic solution 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.
  • 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 (CF 3 SO 2) 2, LiC (CF 3 SO 2) can be exemplified 3 or the like.
  • the lithium ion secondary battery 12 includes an electrode group including a positive electrode 3 having a positive electrode material coated on both sides of a current collector, a negative electrode 4 having a negative electrode material coated on both sides of the current collector, and a separator 5.
  • the positive electrode 3 and the negative electrode 4 are wound via the separator 5 to form a wound electrode group.
  • the wound body is inserted into the battery can 6.
  • the negative electrode 4 is electrically connected to the battery can 6 via 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 through the positive electrode lead piece 7.
  • the wound body is insulated from the battery can 6 and the sealing lid 9 by the insulating plate 11.
  • the electrode group may not be a wound body shown in FIG. 1, and may be a laminate in which the positive electrode 3 and the negative electrode 4 are stacked via the separator 5.
  • Lithium carbonate, nickel carbonate and manganese carbonate were mixed in a ball mill to obtain a precursor.
  • the obtained precursor was calcined 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 crushed in an agate mortar, and classified using a 45 ⁇ m mesh sieve to prepare a positive electrode material for a lithium ion secondary battery.
  • the composition is adjusted by variously changing the mixing ratio of lithium carbonate, nickel carbonate and manganese carbonate to obtain a plurality of positive electrode materials represented by the composition formula Li 1.15 + x Ni 0.3 + y Mn 0.5-y O 2 Obtained.
  • Each of the 19 types of positive electrode materials for lithium ion secondary batteries, a conductive agent and a binder were uniformly mixed to prepare a positive electrode slurry for lithium ion secondary batteries.
  • a positive electrode slurry for a lithium ion secondary battery is coated on a 20 ⁇ m thick aluminum current collector foil, dried at 120 ° C., and compression molded so that the electrode density is 2.2 g / cm 3 with a pressing device. I got a board. Thereafter, the electrode plate was punched into a disk shape having a diameter of 15 mm to prepare a positive electrode for a lithium ion secondary battery.
  • the negative electrode was produced using metallic lithium.
  • a non-aqueous electrolytic solution one in which LiPF 6 was dissolved at a concentration of 1.0 mol / L in a mixed solvent of ethylene carbonate and dimethyl carbonate at a volume ratio of 1: 2 was used.
  • the difference between the charge and discharge OCVs> The OCV of the charging process and the OCV of the discharging process were determined in the following procedure for the above-mentioned 19 types of trial lithium ion secondary batteries in total.
  • the above charge / discharge test was performed for two cycles on a prototype lithium ion secondary battery, and a rated capacity was obtained at the second cycle of discharge capacity.
  • the circuit was opened and allowed to stand for 5 hours, and then the OCV was measured. That is, the voltage after waiting for 5 hours was defined as OCV.
  • the circuit was left open and allowed to stand for 5 hours, and then the OCV was measured. Thereafter, in the same manner, the SOC was measured at 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100% (rated capacity).
  • the circuit was opened and allowed to stand for 5 hours, and then the OCV was measured.
  • the circuit was left open and allowed to stand for 5 hours, and then the OCV was measured. Thereafter, the SOC was measured at 70%, 60%, 50%, 40%, 30%, 20%, 10% and 0% by the same procedure.
  • FIG. 3 shows the measurement results of OCV in Example 1 and Comparative Example 1.
  • 1 is the measurement result of OCV of Example 1
  • 2 is the measurement result of OCV of Comparative Example 1.
  • the vertical axis represents OCV (open circuit voltage: V) and the horizontal axis represents SOC (state of charge:%).
  • the voltage measured in the charging process is the upper side, and the voltage measured in the discharging process is the lower. Shown on the side.
  • Comparing 1 and 2 in Figure 3 shows that the difference between the OCV in the charge process and the OCV in the discharge process in 1 is much smaller than the difference between the OCV in the charge process and the OCV in the discharge process in 2 .
  • the lithium ion secondary battery using the positive electrode material according to the present invention has an OCV at the time of charging from the full discharge state to the full charge state, as compared with the lithium ion secondary battery using the conventional positive electrode material capable of obtaining high capacity. And the difference between the OCV at the time of discharging from the fully charged state to the fully discharged state is small. As a result, the remaining capacity of the battery can be detected more accurately from the voltage.
  • the OCV at the time of charge from the fully discharged state to 50% of the rated capacity and waiting for 5 hours is discharged from the fully charged state to 50% of the rated capacity and then the voltage is discharged after waiting for 5 hours. It was defined as OCV.
  • a value obtained by dividing the difference between the OCV at the time of charge and the OCV at the time of discharge by the difference between the OCV at the time of charge and the OCV at the time of discharge in Comparative Example 1 was defined as the OCV ratio. That is, the OCV ratio is normalized by the difference between the OCV at the time of charge and the OCV at the time of discharge in Comparative Example 1. The result is shown in FIG. 4 as a list.
  • the discharge capacity ratio is larger than in Comparative Examples 1 to 5. That is, in Examples 1 to 14, higher capacities can be realized as compared with Comparative Examples 1 to 5.
  • the OCV ratio is smaller than that of Comparative Example 1 in Examples 1-14. That is, the difference between the OCV during charging and the OCV during discharging is small.
  • the value of the same level as an Example is realized about OCV ratio about comparative examples 2, 3, and 5, about discharge capacity ratio as mentioned above, it is small compared with an example.
  • the positive electrode material satisfying the following condition: ⁇ 0.1 ⁇ x ⁇ 0.05, ⁇ 0.1 ⁇ y ⁇ 0.1 in the composition formula: Li 1.15 + x Ni 0.3 + y Mn 0.5 ⁇ y O 2
  • a lithium ion secondary battery having a high capacity and a small difference between the OCV in the charging process and the OCV in the discharging process can be realized.
  • the OCV ratio is large. It is considered that this is because the contribution of oxygen in the charge and discharge reaction is increased due to the small content of Ni.
  • the discharge capacity ratio is small. This is considered to be because the crystal lattice became unstable due to the high content of Li.
  • the discharge capacity ratio is small. It is considered that this is because the amount of Li that can be involved in the reaction is reduced due to the low content of Li.
  • the discharge capacity ratio is small. It is considered that this is because the content rate of Ni is high and the content rate of Mn is low, so that the valence number of Ni is increased and the charge and discharge capacity associated with Ni is decreased.
  • Examples 1 to 13 when focusing on the discharge capacity ratio, Examples 1 to 13 have larger values than Example 14. That is, according to the positive electrode material satisfying the following condition: ⁇ 0.1 ⁇ x ⁇ 0.05, ⁇ 0.1 ⁇ y ⁇ 0.05 in the composition formula: Li 1.15 + x Ni 0.3 + y Mn 0.5 ⁇ y O 2 For example, it can be understood that a lithium ion secondary battery with higher capacity can be realized.
  • the capacity is high, the difference between the OCV in the charging process and the OCV in the discharging process is small, and the remaining capacity of the battery is detected from the voltage.
  • the positive electrode material for lithium ion secondary batteries with high accuracy and the lithium ion secondary battery using the same can be provided.

Abstract

A positive electrode material for lithium ion secondary batteries is represented by the compositional formula: Li1.15+xNi0.3+yMn0.5-yO2 [in the formula, x and y are parameters which satisfy the following relationships: -0.1≤x≤0.05 and -0.1<y≤0.1].

Description

リチウムイオン二次電池用正極材料、リチウムイオン二次電池用正極、及びリチウムイオン二次電池Positive electrode material for lithium ion secondary battery, positive electrode 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正極材料、そのリチウムイオン二次電池用正極材料を用いたリチウムイオン二次電池用正極、及びそのリチウムイオン二次電池用正極を用いた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 lithium ion secondary battery, a positive electrode for lithium ion secondary battery using the positive electrode material for lithium ion secondary battery, and a lithium ion secondary battery using the positive electrode for lithium ion secondary battery About.
　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。電気自動車の駆動用二次電池に用いられるリチウムイオン二次電池には、より高容量であることが期待されている。 In recent years, expectations for electric vehicles with less energy required for driving have been increasing from the prevention of global warming and concern about the exhaustion of fossil fuels. Higher capacity is expected for lithium ion secondary batteries used for driving secondary batteries of electric vehicles.
　特許文献１には、空間群Ｒ－３ｍに属する六方晶系の層状岩塩型の結晶構造を有するリチウム含有遷移金属酸化物とスピネル構造を有するリチウムマンガン酸化物とを混合した正極材料を用いたリチウムイオン二次電池について記載されている。 Patent Document 1 discloses a lithium using a positive electrode material in which a lithium-containing transition metal oxide having a hexagonal layered rock salt type crystal structure belonging to the space group R-3m and a lithium manganese oxide having a spinel structure are mixed. An ion secondary battery is described.
日本国特開２００７－２００８６５号公報Japanese Patent Application Publication No. 2007-200865
　特許文献１に示されている正極材料を用いたリチウムイオン二次電池は高容量を期待できる。しかしながら、本発明者らは、特許文献１の正極材料を用いたリチウムイオン二次電池の、満完全放電状態から満充電状態まで充電する際と、満充電状態から満放電状態まで放電する際の、充電状態（ＳＯＣ：State of Charge）に対するＯＣＶ（開回路電圧：Open Circuit Voltage）には、大きな差があることを見出した。即ち、特許文献１の正極材料を用いたリチウムイオン二次電池には大きなヒステリシスが存在するため、電圧から電池の残存容量を正確に検知することが困難である。 The lithium ion secondary battery using the positive electrode material shown in Patent Document 1 can be expected to have a high capacity. However, the inventors of the present invention have studied lithium ion secondary batteries using the positive electrode material of Patent Document 1 when charging from the full discharge state to the full charge state and when discharging from the full charge state to the full discharge state. It was found that there is a large difference in OCV (Open Circuit Voltage: Open Circuit Voltage) with respect to the state of charge (SOC). That is, since a large hysteresis exists in the lithium ion secondary battery using the positive electrode material of Patent Document 1, it is difficult to accurately detect the remaining capacity of the battery from the voltage.
　本発明のリチウムイオン二次電池用正極材料は、組成式：
Ｌｉ１．１５＋ｘＮｉ０．３＋ｙＭｎ０．５－ｙＯ２
［式中、ｘ及びｙは、次の関係：
－０．１≦ｘ≦０．０５、－０．１＜ｙ≦０．１
を満たすパラメータである］で表される。 The positive electrode material for a lithium ion secondary battery of the present invention has a composition formula:
Li 1.15 + x Ni 0.3 + y Mn 0.5-y O 2
[Wherein, x and y have the following relationship:
-0.1 ≦ x ≦ 0.05, -0.1 <y ≦ 0.1
Which is a parameter that satisfies
　本発明のリチウムイオン二次電池用正極材料を用いることによって、高容量であり、かつ、電圧から残存容量を高い精度で検知可能なリチウムイオン二次電池を提供できる。 By using the positive electrode material for a lithium ion secondary battery of the present invention, it is possible to provide a lithium ion secondary battery having a high capacity and capable of detecting a remaining capacity from a voltage with high accuracy.
図１は、リチウムイオン二次電池の構造を模式的に説明する断面図である。FIG. 1 is a cross-sectional view schematically illustrating the structure of a lithium ion secondary battery. 図２は、実施例及び比較例の組成を示す一覧表である。FIG. 2 is a list showing the compositions of Examples and Comparative Examples. 図３は、実施例１と比較例１の充電過程と放電過程のＯＣＶの測定値を示す図である。FIG. 3 is a view showing measured values of OCV in the charging process and the discharging process of Example 1 and Comparative Example 1. 図４は、実施例及び比較例に対して求めた、放電容量比及びＯＣＶ比の値を示す一覧表である。FIG. 4 is a list showing values of the discharge capacity ratio and the OCV ratio obtained for the example and the comparative example.
＜リチウムイオン二次電池用正極材料＞
　リチウムイオン二次電池を電気自動車に採用する場合、高容量であって、一回の充電で走行できる距離が長いことが要求される。また、電圧から電池の残存容量を検知するために、充電過程でのＯＣＶと放電過程でのＯＣＶとの差が小さいことが望ましい。充電過程でのＯＣＶと放電過程でのＯＣＶの差が小さいほど、ＯＣＶから電池の残存容量を検知する際の誤差が低減できるからである。 <Positive material for lithium ion secondary battery>
When using a lithium ion secondary battery for an electric vehicle, it is required that the capacity is high and the distance that can be traveled by one charge is long. Further, in order to detect the remaining capacity of the battery from the voltage, it is desirable that the difference between the OCV in the charging process and the OCV in the discharging process be small. The smaller the difference between the OCV in the charging process and the OCV in the discharging process, the smaller the error in detecting the residual capacity of the battery from the OCV.
　リチウムイオン二次電池において、充電過程でのＯＣＶと放電過程でのＯＣＶの差の大きさは、正極材料の組成と密接な関係がある。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：
Ｌｉ１．１５＋ｘＮｉ０．３＋ｙＭｎ０．５－ｙＯ２
［式中、ｘ及びｙは以下の関係：
－０．１≦ｘ≦０．０５、－０．１＜ｙ≦０．１
を満たすパラメータである］で表される。 In the lithium ion secondary battery, the magnitude of the difference between the OCV in the charging process and the OCV in the discharging process is closely related to the composition of the positive electrode material. The positive electrode material for a lithium ion secondary battery according to the present invention has a composition formula:
Li 1.15 + x Ni 0.3 + y Mn 0.5-y O 2
[Wherein, x and y have the following relationship:
-0.1 ≦ x ≦ 0.05, -0.1 <y ≦ 0.1
Which is a parameter that satisfies
　上記の組成を満たす正極材料を用いることによって、高容量であり、かつ、充電過程でのＯＣＶと放電過程でのＯＣＶとの差が小さいリチウムイオン二次電池を得ることができる。その結果、ＯＣＶから残存容量を検知する際の精度を高めることができる。 By using a positive electrode material satisfying the above composition, it is possible to obtain a lithium ion secondary battery having a high capacity and a small difference between the OCV in the charging process and the OCV in the discharging process. As a result, it is possible to enhance the accuracy in detecting the remaining capacity from the OCV.
　組成式におけるｘは、Ｌｉの含有比率（原子量比率）の範囲を示すパラメータである。ｘが－０．１未満であると高容量の電池が得られない。これは、反応に寄与するＬｉの量が相対的に少なくなるためと考えられる。逆に、ｘが０．０５より大きいと電池の放電容量が低下する。これは、Ｌｉの量が相対的に多くなって結晶格子が不安定になるためと考えられる。 In the composition formula, x is a parameter indicating the range of the content ratio of Li (atomic weight ratio). If x is less than -0.1, a high capacity battery can not be obtained. It is considered that this is because the amount of Li contributing to the reaction is relatively small. Conversely, if x is greater than 0.05, the discharge capacity of the battery is reduced. It is considered that this is because the amount of Li relatively increases and the crystal lattice becomes unstable.
　組成式におけるｙは、Ｎｉの含有比率（原子量比率）の範囲を示すパラメータである。ｙが－０．１以下であると充電過程でのＯＣＶと放電過程でのＯＣＶとの差が大きくなる。これは、充放電反応に対する酸素の寄与が高くなるためと考えられる。逆に、ｙが０．１より大きいと高容量が得られない。これは、Ｎｉの価数が高くなると充放電容量へのＮｉの関与が減ることによるものと考えられる。 Y in the composition formula is a parameter indicating the range of the content ratio of Ni (atomic weight ratio). When y is −0.1 or less, the difference between the OCV in the charging process and the OCV in the discharging process becomes large. This is considered to be due to the high contribution of oxygen to the charge and discharge reaction. Conversely, if y is larger than 0.1, high capacity can not be obtained. It is considered that this is because the contribution of Ni to the charge and discharge capacity decreases as the valence of Ni increases.
　さらに高容量であって、かつ、充電過程でのＯＣＶと放電過程でのＯＣＶとの差をさらに小さくするためには、上記組成式におけるｘ及びｙが以下の関係：
－０．１≦ｘ≦０．０５、－０．１＜ｙ≦０．０５、
を満たすことが好ましい。 In order to further reduce the difference between the OCV in the charging process and the OCV in the discharging process, x and y in the above composition formula have the following relationship:
−0.1 ≦ x ≦ 0.05, −0.1 <y ≦ 0.05,
It is preferable to satisfy
　本発明のリチウムイオン二次電池用正極材料は、遷移金属としては、基本的にＬｉ、Ｎｉ、及びＭｎの３種類の元素を含み、高価なＣｏは含まない。本発明のリチウムイオン二次電池用正極材料はＣｏを含まないため、低コストであるという利点を有する。なお、正極材料には、本発明に影響を与えない範囲で添加物等を含んでいても良い。 The positive electrode material for a lithium ion secondary battery of the present invention basically contains three elements of Li, Ni and Mn as a transition metal, and does not contain expensive Co. Since the positive electrode material for a lithium ion secondary battery of the present invention does not contain Co, it has an advantage of low cost. In addition, an additive etc. may be included in the positive electrode material in the range which does not affect this invention.
　本発明に係るリチウムイオン二次電池用正極材料は、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、及び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作製することができる。上記化合物の混合比率を変化させることにより、リチウムイオン二次電池用正極材料の組成を適宜調節することができる。 The positive electrode material for a lithium ion secondary battery 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, it can produce by mixing and baking the compound which each contains Li, Ni, and Mn in a suitable ratio. The composition of the positive electrode material for a lithium ion secondary battery can be appropriately adjusted by changing the mixing ratio of the above compounds.
　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。 Examples of the compound containing Li include lithium acetate, lithium nitrate, lithium carbonate, lithium hydroxide, lithium oxide and the like. Examples of the compound containing Ni include nickel acetate, nickel nitrate, nickel carbonate, nickel sulfate, nickel hydroxide and the like. As a compound containing Mn, manganese acetate, manganese nitrate, manganese carbonate, manganese sulfate, manganese oxide etc. can be mentioned, for example.
　リチウムイオン二次電池用正極材料の組成は、例えば、Ｘ線回折（ＸＲＤ）や誘導結合プラズマ法（ＩＣＰ）等により解析することができる。 The composition of the positive electrode material for a lithium ion secondary battery can be analyzed by, for example, X-ray diffraction (XRD) or inductively coupled plasma (ICP).
＜リチウムイオン二次電池用正極＞
　本発明に係るリチウムイオン二次電池用正極は、上記のリチウムイオン二次電池用正極材料を用いて作製される。これにより、高容量であって、かつ、充電過程でのＯＣＶと放電過程でのＯＣＶとの差が低減されるため、ＯＣＶの値から電池残量を検知する精度を高めることが可能となる。 <Positive electrode for lithium ion secondary battery>
The positive electrode for a lithium ion secondary battery according to the present invention is manufactured using the above-described positive electrode material for a lithium ion secondary battery. As a result, the difference between the OCV in the charging process and the OCV in the discharging process is reduced, and the accuracy in detecting the battery remaining amount from the value of the OCV can be enhanced.
＜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、上記のリチウムイオン二次電池用正極材料を用いて作製される。これにより、高容量であって、かつ、充電過程でのＯＣＶと放電過程でのＯＣＶとの差が低減されるため、ＯＣＶの値から電池の残存容量を検知する精度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、電気自動車及びプラグインハイブリッド自動車に好ましく使用することができる。また、電力貯蔵システム、電動工具、玩具、医療機器等にも使用できる。 <Lithium ion secondary battery>
The lithium ion secondary battery according to the present invention is manufactured using the above-described positive electrode material for a lithium ion secondary battery. As a result, since the difference between the OCV in the charging process and the OCV in the discharging process is reduced, the lithium ion secondary battery with high accuracy of detecting the remaining capacity of the battery from the value of the OCV is obtained. It can be done. The lithium ion secondary battery according to the present invention can be preferably used, for example, in electric vehicles and plug-in hybrid vehicles. It can also be used in power storage systems, power tools, toys, medical devices and the like.
　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。 The lithium ion secondary battery is composed of a positive electrode containing a positive electrode material, a negative electrode containing 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 capable of inserting and extracting lithium ions. Materials generally used in lithium ion secondary batteries can be used as the negative electrode material. For example, graphite, lithium alloy and the like can be exemplified.
　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から作製された微孔性フィルムや不織布等を例示することができる。 As a separator, those generally used in lithium ion secondary batteries can be used. For example, a microporous film or non-woven fabric made of a polyolefin such as polypropylene, polyethylene, and a copolymer of propylene and ethylene can be exemplified.
　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, as the electrolytic solution, 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. 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 (CF 3 SO 2) 2, LiC (CF 3 SO 2) can be exemplified 3 or the like.
　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について図１を用いて説明する。図１において、左側はリチウムイオン二次電池の断面構造を表している。リチウムイオン二次電池１２は、集電体の両面に正極材料を塗布した正極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。 One embodiment of a structure of a lithium ion secondary battery according to the present invention will be described with reference to FIG. In FIG. 1, the left side represents the cross-sectional structure of the lithium ion secondary battery. The lithium ion secondary battery 12 includes an electrode group including a positive electrode 3 having a positive electrode material coated on both sides of a current collector, a negative electrode 4 having a negative electrode material coated on both sides of the current collector, and a separator 5. The positive electrode 3 and the negative electrode 4 are wound via the separator 5 to form a wound electrode group. The wound body is inserted into the battery can 6.
　負極４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によって電池缶６及び密閉蓋９に対して絶縁される。 The negative electrode 4 is electrically connected to the battery can 6 via 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 through the positive electrode lead piece 7. The wound body is insulated from the battery can 6 and the sealing lid 9 by the insulating plate 11.
　なお、電極群は、図１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 a wound body shown in FIG. 1, and may be a laminate in which the positive electrode 3 and the negative electrode 4 are stacked via the separator 5.
＜リチウムイオン二次電池用正極材料の作製＞
　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て前駆体を得た。得られた前駆体を大気中において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、目開き４５μｍのふるいで分級し、リチウムイオン二次電池用正極材料を作製した。炭酸リチウム、炭酸ニッケル、及び炭酸マンガンの混合比率を種々に変化させることで組成を調節し、組成式Ｌｉ１．１５＋ｘＮｉ０．３＋ｙＭｎ０．５－ｙＯ２で表わされる複数の正極材料を得た。 <Fabrication of positive electrode material for lithium ion secondary battery>
Lithium carbonate, nickel carbonate and manganese carbonate were mixed in a ball mill to obtain a precursor. The obtained precursor was calcined 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 crushed in an agate mortar, and classified using a 45 μm mesh sieve to prepare a positive electrode material for a lithium ion secondary battery. The composition is adjusted by variously changing the mixing ratio of lithium carbonate, nickel carbonate and manganese carbonate to obtain a plurality of positive electrode materials represented by the composition formula Li 1.15 + x Ni 0.3 + y Mn 0.5-y O 2 Obtained.
　各実施例及び比較例で使用した正極材料のｘとｙの値を図２に示す。 The values of x and y of the positive electrode material used in each example and comparative example are shown in FIG.
＜試作リチウムイオン二次電池の作製＞
　作製した正極材料を用いて１９種類の試作リチウムイオン二次電池を次の手順で作製した。 <Fabrication of trial manufacture lithium ion secondary battery>
Nineteen types of trial lithium ion secondary batteries were manufactured in the following procedure using the manufactured positive electrode material.
　上記１９種類のリチウムイオン二次電池用正極材料のそれぞれと導電剤とバインダとを均一に混合してリチウムイオン二次電池用正極スラリーを作製した。厚み２０μｍのアルミ集電体箔上にリチウムイオン二次電池用正極スラリーを塗布し、１２０℃で乾燥し、プレス装置にて電極密度が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の円板状に打ち抜き、リチウムイオン二次電池用正極を作製した。 Each of the 19 types of positive electrode materials for lithium ion secondary batteries, a conductive agent and a binder were uniformly mixed to prepare a positive electrode slurry for lithium ion secondary batteries. A positive electrode slurry for a lithium ion secondary battery is coated on a 20 μm thick aluminum current collector foil, dried at 120 ° C., and compression molded so that the electrode density is 2.2 g / cm 3 with a pressing device. I got a board. Thereafter, the electrode plate was punched into a disk shape having a diameter of 15 mm to prepare a positive electrode for a lithium ion secondary battery.
　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 a non-aqueous electrolytic solution, one in which LiPF 6 was dissolved at a concentration of 1.0 mol / L in a mixed solvent of ethylene carbonate and dimethyl carbonate at a volume ratio of 1: 2 was used.
＜充放電試験＞
　上記の１９種類の試作リチウムイオン二次電池に対して、次の要領で充放電試験を行った。 <Charge / discharge test>
The charge / discharge test was performed on the above 19 types of trial lithium ion secondary batteries in the following manner.
　試作リチウムイオン二次電池に対し、充電は０．０５Ｃ相当の電流で上限電圧を４．６Ｖとし、４．６Ｖに達した後、電流が０．００５Ｃ以下になるまで、定電圧充電した。放電は０．０５Ｃ相当の電流で下限電圧を２．５Ｖとして充放電試験を行った。その際、高出力が得られる４．６～３．３Ｖの領域における放電容量の値を各実施例及び比較例について求めた。次いで、比較例１の放電容量に対する、実施例及び比較例それぞれの放電容量の比を求め、これらの値を放電容量比とした。即ち、放電容量比とは、比較例１の放電容量で規格化したものである。その結果を一覧表として図４に示す。 With respect to the prototype lithium ion secondary battery, charging was performed at a current of 0.05 C at an upper limit voltage of 4.6 V, and after reaching 4.6 V, constant voltage charging was performed until the current was 0.005 C or less. For the discharge, a charge / discharge test was performed with a current of 0.05 C and a lower limit voltage of 2.5 V. At that time, the value of the discharge capacity in the region of 4.6 to 3.3 V where high output was obtained was determined for each example and comparative example. Subsequently, the ratio of the discharge capacity of each of the example and the comparative example to the discharge capacity of the comparative example 1 was determined, and these values were defined as the discharge capacity ratio. That is, the discharge capacity ratio is normalized by the discharge capacity of Comparative Example 1. The result is shown in FIG. 4 as a list.
＜充電側と放電側のＯＣＶの差＞
　上記の合計１９種類の試作リチウムイオン二次電池について、充電過程のＯＣＶと放電過程のＯＣＶとを次の手順で求めた。 <The difference between the charge and discharge OCVs>
The OCV of the charging process and the OCV of the discharging process were determined in the following procedure for the above-mentioned 19 types of trial lithium ion secondary batteries in total.
　試作リチウムイオン二次電池に対し、上記充放電試験を２サイクルさせ、２サイクル目の放電容量をした定格容量とした。 The above charge / discharge test was performed for two cycles on a prototype lithium ion secondary battery, and a rated capacity was obtained at the second cycle of discharge capacity.
　続いて、０．０５Ｃ相当の電流で定格容量の１０％（ＳＯＣ＝１０％）まで充電した後、回路を開放状態にして５時間放置してからＯＣＶを測定した。即ち、５時間待機した後の電圧をＯＣＶと定義した。次に、さらに定格容量の２０％まで充電した後、回路を開放状態にして５時間放置してからＯＣＶを測定した。以降、同様の手順で、ＳＯＣが、３０％、４０％、５０％、６０％、７０％、８０％、９０％、および１００％（定格容量）におけるＯＣＶを測定した。 Subsequently, after charging to 10% of the rated capacity (SOC = 10%) with a current equivalent to 0.05 C, the circuit was opened and allowed to stand for 5 hours, and then the OCV was measured. That is, the voltage after waiting for 5 hours was defined as OCV. Next, after further charging to 20% of the rated capacity, the circuit was left open and allowed to stand for 5 hours, and then the OCV was measured. Thereafter, in the same manner, the SOC was measured at 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100% (rated capacity).
　次に、ＳＯＣ９０％まで放電した後、回路を開放状態にして５時間放置してからＯＣＶを測定した。次に、ＳＯＣ８０％まで放電した後、回路を開放状態にして５時間放置してからＯＣＶを測定した。以降、同様の手順で、ＳＯＣが、７０％、６０％、５０％、４０％、３０％、２０％、１０％、および０％におけるＯＣＶを測定した。 Next, after discharging to 90% of SOC, the circuit was opened and allowed to stand for 5 hours, and then the OCV was measured. Next, after discharging to SOC 80%, the circuit was left open and allowed to stand for 5 hours, and then the OCV was measured. Thereafter, the SOC was measured at 70%, 60%, 50%, 40%, 30%, 20%, 10% and 0% by the same procedure.
　図３は、実施例１と比較例１のＯＣＶの測定結果である。図３の１は実施例１のＯＣＶの測定結果、２は比較例１のＯＣＶの測定結果である。図３において、縦軸はＯＣＶ（開回路電圧：Ｖ）、横軸はＳＯＣ（充電状態：％）を表しており、充電過程で測定された電圧は上側、放電過程で測定された電圧は下側に示される。 FIG. 3 shows the measurement results of OCV in Example 1 and Comparative Example 1. In FIG. 3, 1 is the measurement result of OCV of Example 1, and 2 is the measurement result of OCV of Comparative Example 1. In FIG. 3, the vertical axis represents OCV (open circuit voltage: V) and the horizontal axis represents SOC (state of charge:%). The voltage measured in the charging process is the upper side, and the voltage measured in the discharging process is the lower. Shown on the side.
　図３の１と２を比較すると、２における充電過程のＯＣＶと放電過程のＯＣＶとの差に比べて、１における充電過程のＯＣＶと放電過程のＯＣＶとの差は、はるかに小さいことがわかる。ＳＯＣが５０％（定格容量の１／２）となるときの充電過程のＯＣＶと放電過程のＯＣＶの差を比較すると、実施例１では充電過程のＯＣＶと放電過程のＯＣＶの差は０．３Ｖ以下となるのに対し、比較例１では充電過程のＯＣＶと放電過程のＯＣＶの差は０．３Ｖを超えることがわかる。本発明に係る正極材料を用いたリチウムイオン二次電池は、従来の高容量が得られる正極材料を用いたリチウムイオン二次電池に比べて、満放電状態から満充電状態まで充電する際のＯＣＶと、満充電状態から満放電状態まで放電する際のＯＣＶとの差が小さい。その結果、電圧から電池の残存容量をより正確に検知できる。 Comparing 1 and 2 in Figure 3 shows that the difference between the OCV in the charge process and the OCV in the discharge process in 1 is much smaller than the difference between the OCV in the charge process and the OCV in the discharge process in 2 . Comparing the difference between the OCV in the charging process and the OCV in the discharging process when the SOC is 50% (1/2 of the rated capacity), in Example 1, the difference between the OCV in the charging process and the OCV in the discharging process is 0.3V. It turns out that the difference of OCV of a charge process and the OCV of a discharge process exceeds 0.3V by the comparative example 1 although it becomes the following. The lithium ion secondary battery using the positive electrode material according to the present invention has an OCV at the time of charging from the full discharge state to the full charge state, as compared with the lithium ion secondary battery using the conventional positive electrode material capable of obtaining high capacity. And the difference between the OCV at the time of discharging from the fully charged state to the fully discharged state is small. As a result, the remaining capacity of the battery can be detected more accurately from the voltage.
　また、完全放電状態から定格容量の５０％まで充電して５時間待機した後の電圧を充電時のＯＣＶ、満充電状態から定格容量の５０％まで放電して５時間待機した後の電圧を放電時のＯＣＶと定義した。各実施例及び比較例において、充電時のＯＣＶと放電時のＯＣＶとの差を、比較例１の充電時のＯＣＶと放電時のＯＣＶとの差で除した値をＯＣＶ比とした。即ち、ＯＣＶ比とは、比較例１における充電時のＯＣＶと放電時のＯＣＶとの差で規格化したものである。その結果を一覧表として図４に示す。 In addition, the OCV at the time of charge from the fully discharged state to 50% of the rated capacity and waiting for 5 hours is discharged from the fully charged state to 50% of the rated capacity and then the voltage is discharged after waiting for 5 hours. It was defined as OCV. In each of the examples and the comparative examples, a value obtained by dividing the difference between the OCV at the time of charge and the OCV at the time of discharge by the difference between the OCV at the time of charge and the OCV at the time of discharge in Comparative Example 1 was defined as the OCV ratio. That is, the OCV ratio is normalized by the difference between the OCV at the time of charge and the OCV at the time of discharge in Comparative Example 1. The result is shown in FIG. 4 as a list.
　図４に示すように、実施例１～１４では比較例１～５に比べて放電容量比が大きい。即ち、実施例１～１４は、比較例１～５に比べて高い容量が実現できている。また、ＯＣＶ比については、実施例１～１４では、比較例１より小さい。即ち、充電時ＯＣＶと放電時ＯＣＶとの差が小さい。なお、比較例２、３、および５については、ＯＣＶ比については、実施例と同レベルの値が実現できているものの、上記の通り放電容量比については、実施例に比べて小さい。即ち、組成式：Ｌｉ１．１５＋ｘＮｉ０．３＋ｙＭｎ０．５－ｙＯ２において、－０．１≦ｘ≦０．０５、－０．１＜ｙ≦０．１を満たす正極材料によれば、高容量であって、かつ、充電過程のＯＣＶと放電過程のＯＣＶとの差が小さいリチウムイオン二次電池が実現できることがわかる。 As shown in FIG. 4, in Examples 1 to 14, the discharge capacity ratio is larger than in Comparative Examples 1 to 5. That is, in Examples 1 to 14, higher capacities can be realized as compared with Comparative Examples 1 to 5. The OCV ratio is smaller than that of Comparative Example 1 in Examples 1-14. That is, the difference between the OCV during charging and the OCV during discharging is small. In addition, although the value of the same level as an Example is realized about OCV ratio about comparative examples 2, 3, and 5, about discharge capacity ratio as mentioned above, it is small compared with an example. That is, according to the positive electrode material satisfying the following condition: −0.1 ≦ x ≦ 0.05, −0.1 <y ≦ 0.1 in the composition formula: Li 1.15 + x Ni 0.3 + y Mn 0.5−y O 2 For example, it is understood that a lithium ion secondary battery having a high capacity and a small difference between the OCV in the charging process and the OCV in the discharging process can be realized.
　一方、比較例１及び４ではＯＣＶ比が大きい。これは、Ｎｉの含有割合が少ないために充放電反応における酸素の寄与が増加したためと考えられる。比較例２では放電容量比が小さい。これは、Ｌｉの含有率が高いために結晶格子が不安定になったためと考えられる。比較例３では放電容量比が小さい。これは、Ｌｉの含有率が少ないために反応に関与できるＬｉが少なくなったためと考えられる。比較例５では放電容量比が小さい。これは、Ｎｉの含有割合が多く、Ｍｎの含有割合が低いためにＮｉの価数が高くなり、Ｎｉが関与した充放電容量が低下したためと考えられる。 On the other hand, in Comparative Examples 1 and 4, the OCV ratio is large. It is considered that this is because the contribution of oxygen in the charge and discharge reaction is increased due to the small content of Ni. In Comparative Example 2, the discharge capacity ratio is small. This is considered to be because the crystal lattice became unstable due to the high content of Li. In Comparative Example 3, the discharge capacity ratio is small. It is considered that this is because the amount of Li that can be involved in the reaction is reduced due to the low content of Li. In Comparative Example 5, the discharge capacity ratio is small. It is considered that this is because the content rate of Ni is high and the content rate of Mn is low, so that the valence number of Ni is increased and the charge and discharge capacity associated with Ni is decreased.
　また、図４に示すように、放電容量比に着目すると、実施例１～１３は実施例１４に比べて値が大きい。即ち、組成式：Ｌｉ１．１５＋ｘＮｉ０．３＋ｙＭｎ０．５－ｙＯ２において、－０．１≦ｘ≦０．０５、－０．１＜ｙ≦０．０５を満たす正極材料によれば、さらに高容量なリチウムイオン二次電池が実現できることがわかる。 Further, as shown in FIG. 4, when focusing on the discharge capacity ratio, Examples 1 to 13 have larger values than Example 14. That is, according to the positive electrode material satisfying the following condition: −0.1 ≦ x ≦ 0.05, −0.1 <y ≦ 0.05 in the composition formula: Li 1.15 + x Ni 0.3 + y Mn 0.5−y O 2 For example, it can be understood that a lithium ion secondary battery with higher capacity can be realized.
　以上説明した通り、本発明のリチウムイオン二次電池用正極材料によれば、高容量であって、充電過程のＯＣＶと放電過程のＯＣＶとの差が小さく、電圧から電池の残存容量を検知する精度が高いリチウムイオン二次電池用正極材料及びそれを用いたリチウムイオン二次電池を提供することができる。 As described above, according to the positive electrode material for a lithium ion secondary battery of the present invention, the capacity is high, the difference between the OCV in the charging process and the OCV in the discharging process is small, and the remaining capacity of the battery is detected from the voltage. The positive electrode material for lithium ion secondary batteries with high accuracy and the lithium ion secondary battery using the same can be provided.
　上記の通り、種々の実施の形態および変形例について説明したが、本発明はこれらの内容に限定されるものではない。本発明の技術的思想の範囲内で考えられるその他の態様も本発明の範囲内に含まれる。 As described above, although various embodiments and modifications have been described, the present invention is not limited to these contents. Other embodiments considered within the scope of the technical idea of the present invention are also included within the scope of the present invention.
１　実施例１のＯＣＶ曲線
２　比較例１のＯＣＶ曲線
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 1 OCV Curve 2 of Example 1 OCV Curve 3 of Comparative Example 1 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

Claims (5)

  1. 　組成式：
    Ｌｉ１．１５＋ｘＮｉ０．３＋ｙＭｎ０．５－ｙＯ２
    ［式中、ｘ及びｙは、次の関係：
    －０．１≦ｘ≦０．０５、－０．１＜ｙ≦０．１
    を満たすパラメータである］で表されるリチウムイオン二次電池用正極材料。     Composition formula:
    Li 1.15 + x Ni 0.3 + y Mn 0.5-y O 2
    [Wherein, x and y have the following relationship:
    -0.1 ≦ x ≦ 0.05, -0.1 <y ≦ 0.1
    The positive electrode material for a lithium ion secondary battery represented by
  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、
    －０．１＜ｙ≦０．０５
    を満たす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, wherein
    -0.1 <y ≦ 0.05
    Cathode material for lithium ion secondary batteries satisfying
  3. 　請求項１または２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。 The positive electrode for lithium ion secondary batteries containing the positive electrode material for lithium ion secondary batteries of Claim 1 or 2.
  4. 　正極と、負極とを有するリチウムイオン二次電池であって、
    　前記正極および前記負極は共に、リチウムイオンの吸蔵放出が可能であって、
    　前記正極は、請求項１または２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。     A lithium ion secondary battery having a positive electrode and a negative electrode, wherein
    Both the positive electrode and the negative electrode are capable of absorbing and releasing lithium ions, and
    The said positive electrode is a lithium ion secondary battery containing the positive electrode material for lithium ion secondary batteries of Claim 1 or 2.
  5. 　請求項４に記載のリチウムイオン二次電池であって、
    　Ｌｉ金属に対して４．６Ｖまで充電した後２．５Ｖまで放電した際に、充電過程で定格容量の１／２となるときの開回路電圧と、放電過程で定格容量の１／２となるときの開回路電圧と、の差が０．３Ｖ以下であるリチウムイオン二次電池。
          The lithium ion secondary battery according to claim 4, wherein
    When the Li metal is charged to 4.6 V and then discharged to 2.5 V, the open circuit voltage at half the rated capacity in the charging process and half the rated capacity in the discharging process Lithium-ion secondary battery with a difference of 0.3 V or less when the open circuit voltage.
PCT/JP2013/059633 2013-03-29 2013-03-29 Positive electrode material for lithium ion secondary batteries, positive electrode for lithium ion secondary batteries, and lithium ion secondary battery WO2014155709A1 (en)

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JP2003297360A (en) * 2002-04-05 2003-10-17 Merck Ltd Positive electrode active material for non-aqueous electrolyte secondary battery and manufacturing method for positive electrode active material
JP2007516583A (en) * 2003-12-23 2007-06-21 トロノックス エルエルシー High voltage thin layer cathode material for lithium rechargeable battery and method for producing the same
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JP2012126633A (en) * 2009-12-28 2012-07-05 Sumitomo Chemical Co Ltd Method for producing lithium composite metal oxide

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003002664A (en) * 2001-06-13 2003-01-08 Mitsubishi Chemicals Corp Layered lithium nickel manganese composite oxide
JP2003297360A (en) * 2002-04-05 2003-10-17 Merck Ltd Positive electrode active material for non-aqueous electrolyte secondary battery and manufacturing method for positive electrode active material
JP2007516583A (en) * 2003-12-23 2007-06-21 トロノックス エルエルシー High voltage thin layer cathode material for lithium rechargeable battery and method for producing the same
JP2008226693A (en) * 2007-03-14 2008-09-25 Matsushita Electric Ind Co Ltd Lithium-ion secondary battery
JP2012126633A (en) * 2009-12-28 2012-07-05 Sumitomo Chemical Co Ltd Method for producing lithium composite metal oxide

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