JP2013187027A - Positive electrode active material, positive electrode for electric device and electric device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a positive electrode active material capable of achieving excellent discharge operating voltage and initial rate characteristics while maintaining high discharge capacity; and a positive electrode for an electric device including the positive electrode active material; and an electric device.SOLUTION: A positive electrode active material contains: a solid solution lithium-containing transition metal oxide A which is represented by Li[NiCoMn[Li]]O(a+b+c+d=1.5, 0.25<d≤0.4, 1.1≤a+b+c<1.25 and 0.1≤a<0.5 are satisfied), has a lamellar structure site changing to a spinel structure through charge/discharge in a potential range of 4.3 V or more and 4.8 V or less, and has a change rate into the spinel structure of 0.25 or more and less than 1.0; and a lithium-containing transition metal oxide B which is represented by Li[NiCoMn[Li]]O(e+f+g+h=1.5, 0.15≤h≤0, 1.25≤e+f+g≤1.35 and 0.25≤e≤0.7 are satisfied), has a lamellar structure site changing to a spinel structure through charge or charge/discharge in a potential range of 4.3 V or more and 4.8 V or less, and has a change rate into the spinel structure of 0.25 or more and less than 1.0.

Description

The present invention relates to a positive electrode active material, a positive electrode for an electric device using the positive electrode active material, and an electric device.
More specifically, the electric device of the present invention is suitably used as an electric device for vehicles such as an electric vehicle, a fuel cell vehicle, and a hybrid electric vehicle. In addition, the positive electrode active material of the present invention is usually suitably used as a positive electrode active material for lithium ion secondary batteries or lithium ion capacitors as electrical devices.

  In recent years, in order to cope with air pollution and global warming, reduction of carbon dioxide emissions has been strongly desired. In the automobile industry, there is an expectation for the reduction of carbon dioxide emissions by introducing electric vehicles (EV) and hybrid electric vehicles (HEV). Electricity such as secondary batteries for motor drive is the key to the practical application of these. Device development is actively underway.

  As a secondary battery for driving a motor, a lithium ion secondary battery having a high theoretical energy is attracting attention, and is currently being developed rapidly. Lithium ion secondary batteries generally have a positive electrode formed by applying a positive electrode slurry containing a positive electrode active material to the surface of a current collector, and a negative electrode slurry containing a negative electrode active material applied to the surface of the negative electrode current collector. The negative electrode formed in this manner and the electrolyte positioned between them are housed in a battery case.

  In order to improve the capacity characteristics and output characteristics of the lithium ion secondary battery, selection of each active material is extremely important.

Conventionally, the formula (a) Li _y [M ¹ _(1-b) Mn _b ] O ₂ or (b) Li _x [M ¹ _(1-b) Mn _b ] O _{1.5 + c} (where 0 ≦ y < 1, 0 <b <1, and 0 <c <0.5, and M ¹ represents one or more metal elements, provided that in (a), M ¹ is a metal element other than chromium. A cathode composition for a lithium ion battery comprising 100 full charge / discharge cycles at 30 ° C. and a final capacity of 130 mAh / g using a discharge current of 30 mA / g when incorporated into a lithium ion battery. There has been proposed a cathode composition for a lithium ion battery that is in the form of a single phase having an O3 crystal structure that does not cause a phase transition to a spinel crystal structure when cycled (see Patent Document 1).

Japanese Patent Laid-Open No. 2004-538610

  However, in the study by the present inventors, even a lithium ion battery using the cathode composition for a lithium ion battery described in Patent Document 1 has sufficient discharge capacity, discharge operating voltage, and initial rate characteristics. There was a problem that it was not.

  The present invention has been made in view of such problems of the prior art, and an object of the present invention is to realize excellent discharge operating voltage and initial rate characteristics while maintaining a high discharge capacity. It is providing a positive electrode active material, a positive electrode for an electric device, and an electric device.

The present inventors have repeated intensive studies to achieve the above object. As a result, the layered structure part is represented by a specific composition formula and has a layered structure part that changes to a spinel structure by charging or charging / discharging in a predetermined potential range, and a layered structure part that does not change. When the spinel structure change ratio when all the Li ₂ MnO ₃ in the spinel structure is changed to LiMn ₂ O ₄ having a spinel structure is 1, the solid-solution lithium-containing transition metal oxidation has a spinel structure change ratio of 0.25 or more and less than 1.0. It has been found that the above object can be achieved by comprising the product A and a solid solution lithium-containing transition metal oxide B (A ≠ B) represented by the same composition formula and having the same spinel structure change ratio. The present invention has been completed.

That is, this invention is based on the said knowledge, Comprising: The positive electrode active material of this invention is a positive electrode active material containing the solid solution lithium containing transition metal oxide A and the solid solution lithium containing transition metal oxide B. FIG.
And the solid solution lithium containing transition metal oxide A in the positive electrode active material of this invention is the composition formula (1).
Li _1.5 [Ni _a Co _b Mn _c [Li] _d ] O ₃ (1)
(In the formula (1), Li is lithium, Ni is nickel, Co is cobalt, Mn is manganese, O is oxygen, and a, b, c, and d are 0.1 ≦ a <0.5, 0 ≦ b <1.15, 0 <c <1.15, 0.25 <d ≦ 0.4, a + b + c + d = 1.5, 1.1 ≦ a + b + c <1.25 are satisfied.) . Moreover, it has a layered structure part that changes into a spinel structure by charging or charging / discharging in a potential range of 4.3 V or more and 4.8 V or less, and a layered structure part that does not change, and Li _{2 of the} layered structure part that changes. When the spinel structure change ratio when MnO ₃ is all changed to LiMn ₂ O ₄ having a spinel structure is 1, the spinel structure change ratio is 0.25 or more and less than 1.0.
On the other hand, the solid solution lithium-containing transition metal oxide B in the positive electrode active material of the present invention has a composition formula (2)
_{Li 1.5 [Ni e Co f Mn} g [Li] h] O 3 ... (2)
(In the formula (2), Li is lithium, Ni is nickel, Co is cobalt, Mn is manganese, O is oxygen, and e, f, g, and h are 0.25 ≦ e ≦ 0.7, 0 <. f <1.1, 0 <g <1.1, 0.15 ≦ h ≦ 0.25, e + f + g + h = 1.5, and 1.25 ≦ e + f + g ≦ 1.35. . Then, by performing charging or charging / discharging in a potential range of 4.3 V or more and 4.8 V or less, there is a layered structure part that changes to a spinel structure and a layered structure part that does not change, and the Li of the layered structure part that changes ₂ When the spinel structure change ratio when all of the MnO ₃ is changed to LiMn ₂ O ₄ having a spinel structure is 1, the spinel structure change ratio is 0.25 or more and less than 1.0.

The positive electrode for an electric device of the present invention contains the positive electrode active material of the present invention.
Moreover, the electric device of the present invention has the positive electrode for an electric device of the present invention.

The positive electrode active material of the present invention is represented by a specific composition formula, and has a layered structure portion that changes to a spinel structure by charging or charging / discharging in a predetermined potential range, and a layered structure portion that does not change, A solid solution having a spinel structure change ratio of 0.25 or more and less than 1.0, assuming that the spinel structure change ratio when the Li ₂ MnO ₃ of the changing layered structure portion is all changed to the spinel structure LiMn ₂ O ₄ is 1. Lithium-containing transition metal oxide A and solid solution lithium-containing transition metal oxide B (where A ≠ B) are represented by the same composition formula and have the same spinel structure change rate. Therefore, according to the present invention, it is possible to provide a positive electrode active material, a positive electrode for an electric device, and an electric device that can realize an excellent discharge operating voltage and initial rate characteristics while maintaining a high discharge capacity.

It is a graph explaining the definition of a spinel structure change rate. It is a schematic sectional drawing which shows an example of the lithium ion secondary battery which concerns on one Embodiment of this invention.

  Hereinafter, the positive electrode active material, the positive electrode for an electric device, and the electric device of the present invention will be described in detail. Moreover, the positive electrode active material of this invention is used suitably as a positive electrode active material of the lithium ion secondary battery which is an electrical device, for example. Therefore, the positive electrode for an electric device and the electric device according to an embodiment of the present invention will be described by taking a positive electrode for a lithium ion secondary battery and a lithium ion secondary battery as examples.

First, a positive electrode active material according to an embodiment of the present invention will be described in detail.
The positive electrode active material of this embodiment is a positive electrode active material containing solid solution lithium-containing transition metal oxide A and solid solution lithium-containing transition metal oxide B.
And the solid solution lithium containing transition metal oxide A in the positive electrode active material of this embodiment is represented by a composition formula (1).
Li _1.5 [Ni _a Co _b Mn _c [Li] _d ] O ₃ (1)
(In the formula (1), Li is lithium, Ni is nickel, Co is cobalt, Mn is manganese, O is oxygen, and a, b, c, and d are 0.1 ≦ a <0.5, 0 ≦ (b <1.15, 0 <c <1.15, 0.25 <d ≦ 0.4, a + b + c + d = 1.5, 1.1 ≦ a + b + c <1.25 are satisfied)
Further, the solid solution lithium-containing transition metal oxide A in the positive electrode active material of the present embodiment has a layered structure portion that changes into a spinel structure by charging or charging / discharging in a potential range of 4.3 V to 4.8 V, A layered structure portion that does not change.
The solid solution lithium-containing transition metal oxide A in the positive electrode active material of this embodiment has a spinel structure change ratio of 1 when all the Li ₂ MnO _{3 in} the changing layered structure portion is changed to LiMn ₂ O ₄ in the spinel structure. The spinel structure change ratio is 0.25 or more and less than 1.0.

On the other hand, the lithium-containing transition metal oxide B in the positive electrode active material of the present embodiment is represented by the composition formula (2).
_{Li 1.5 [Ni e Co f Mn} g [Li] h] O 3 ... (2)
(In the formula (2), Li is lithium, Ni is nickel, Co is cobalt, Mn is manganese, O is oxygen, and e, f, g, and h are 0.25 ≦ e ≦ 0.7, 0 <. (F <1.1, 0 <g <1.1, 0.15 ≦ h ≦ 0.25, e + f + g + h = 1.5, 1.25 ≦ e + f + g ≦ 1.35)
Similarly, the solid solution lithium-containing transition metal oxide B includes a layered structure portion that changes into a spinel structure by charging or charging / discharging in a potential range of 4.3 V to 4.8 V, and a layered structure that does not change. When the spinel structure change ratio is 1 when all the Li ₂ MnO ₃ in the layered structure part having changed to the spinel structure LiMn ₂ O ₄ is 1, the spinel structure change ratio is 0.25 or more and 1 Less than 0.0.

When such a positive electrode active material is used in a lithium ion secondary battery, it can realize excellent discharge operating voltage and initial rate characteristics while maintaining a high discharge capacity. Therefore, it is suitably used for a positive electrode for lithium ion secondary batteries and a lithium ion secondary battery. In addition, such a positive electrode active material exhibits a high capacity retention rate, particularly in a potential range of 3.0 V to 4.5 V. As a result, it can be suitably used as a lithium-ion secondary battery for vehicle drive power or auxiliary power. In addition to this, the present invention can be sufficiently applied to lithium ion secondary batteries for home use and portable devices.
Note that “charging” refers to an operation of increasing a potential difference between electrodes continuously or stepwise. In addition, “charging / discharging” refers to an operation of decreasing a potential difference between electrodes continuously or stepwise, or an operation of repeating this appropriately, after an operation of increasing the potential difference between electrodes continuously or stepwise. Say.

In the composition formula (1) of the solid solution lithium-containing transition metal oxide A, a, b, c and d are 0.1 ≦ a <0.5, 0 <b <1.15, 0 <c <1.15. , 0.25 <d ≦ 0.4, a + b + c + d = 1.5, 1.1 ≦ a + b + c <1.25, the structure in the solid solution lithium-containing transition metal oxide A is not stabilized.
In addition, the solid solution lithium-containing transition metal oxide A does not have a layered structure part that changes to a spinel structure or a layered structure part that does not change by charging or charging / discharging in a potential range of 4.3 V to 4.8 V. In some cases, a high discharge capacity and capacity retention rate cannot be realized. Specifically, it is important to expose at least once to a potential plateau section near 4.5V.
Further, in the solid solution lithium-containing transition metal oxide A, the above-mentioned spinel structure change ratio does not become 1.0, and when it is less than 0.25, high discharge capacity, capacity maintenance rate, excellent initial rate The characteristics cannot be realized.

  On the other hand, in the composition formula (2) of the solid solution lithium-containing transition metal oxide B, e, f, g, and h are 0.25 ≦ e ≦ 0.7, 0 <f <1.1, 0 <g <1. .1, 0.15 ≦ h ≦ 0.25, e + f + g + h = 1.5, 1.25 ≦ e + f + g ≦ 1.35, the structure of the metal oxide B is not stabilized in the same manner. . In addition, by having a layered structure part that changes to a spinel structure by charging or charging / discharging in the potential range and a layered structure part that does not change, a high discharge capacity and capacity retention ratio can be realized, and the spinel structure change rate Is less than 0.25, similarly, a high discharge capacity, capacity retention rate, and excellent rate characteristics cannot be realized.

Here, "the spinel structure change ratio" in the present invention, by performing charge or discharge in a predetermined potential range, LiMn ₂ of Li ₂ MnO ₃ spinel structure of the layered structure in the solid solution lithium-containing transition metal oxide The ratio of change to O ₄ is defined, and the spinel structure change ratio when the layered structure Li ₂ MnO ₃ in the solid solution lithium-containing transition metal oxide A is all changed to the spinel structure LiMn ₂ O ₄ is 1 It is what. Specifically, it is defined by the following formula.

Regarding the definition of “spinel structure change ratio”, as shown in FIG. 1, for a battery assembled using a positive electrode having a solid solution lithium-containing transition metal oxide as a positive electrode active material, from the initial state A before the start of charging, as shown in FIG. An example will be described in which charging state B is charged to 5V, overcharge state C is charged to 4.8V through a plateau region, and discharging state D is further discharged to 2.0V. . The “actual capacity of the plateau region” in the above formula is the plateau region in FIG. 1 (specifically, the region from 4.5 V to 4.8 V (the actual capacity V _BC of the region BC from the charged state B to the overcharged state C) The actual capacity of the plateau region), which is the region resulting from the change in the crystal structure.

Further, in practice, in the solid solution lithium-containing transition metal oxide of the composition formulas (1) and (2), the practical amount V _{AB in} the region AB from the initial state A to the charged state B charged to 4.5 V is layered. Corresponding to the composition (y) and theoretical capacity (V _L ) of LiMO _{2 as} the structural part, the actual capacity of the region BC in the overcharged state C charged from 4.5 B to 4.8 V in the charged state B charged to 4.5 V Since V _BC corresponds to the composition ratio (x) and theoretical capacity (V _S ) of Li ₂ MnO ₃ which is a spinel structure site, the actual capacity (V _T ) measured from the initial state A to a predetermined plateau region is obtained. Assuming that (V _T = V _AB + V _BC ), V _AB = y (V _L ) and V _BC = x (V _S ) K, it can be calculated using the following formula (M is nickel ( Ni), cobalt (Co) and manganese (M ) Represents at least one selected from the group consisting of.).

Further, the “composition ratio of Li ₂ MnO _{3 in} the solid solution” can be calculated from the composition formula of the solid solution lithium-containing transition metal oxide. In addition, the presence or absence of the layered structure site and the spinel structure site in the solid solution lithium-containing transition metal oxide can be determined by the presence of a peculiar peak in the layered structure and the spinel structure by X-ray diffraction analysis (XRD), and the ratio is It can be determined from the measurement and calculation of the capacity as described above.

  Further, the solid solution lithium-containing transition metal oxide A in the positive electrode active material of the present embodiment is such that a, b, c, and d are 0.15 ≦ a ≦ 0.5, 0 <b <in the composition formula (1). 0.5, 0.15 <c <1.1, 0.25 ≦ d ≦ 0.35, a + b + c + d = 1.5, 1.25 ≦ a + b + c ≦ 1.25, 0 <b / a <1 It is preferable to satisfy.

  The positive electrode active material containing such a solid solution lithium-containing transition metal oxide A can realize excellent discharge operating voltage and initial rate characteristics while maintaining a higher discharge capacity.

Further, the solid solution lithium-containing transition metal oxide A in the positive electrode active material of the present embodiment has a BET specific surface area of 0.8 m ² / g to 10.0 m ² / g and a 50% passing particle size (D50) of 20 μm or less. The primary particle diameter is preferably 30 nm or more and 200 nm or less.

By setting it as such a range, the outstanding discharge operation voltage and the initial rate characteristic can be implement | achieved, maintaining a high discharge capacity, a capacity | capacitance maintenance factor, and initial stage charge / discharge efficiency. For example, when the BET specific surface area is less than 0.8 m ² / g, the diffusibility of lithium ions from the bulk in the crystal structure becomes low, so that high initial charge / discharge efficiency and excellent initial rate characteristics are realized. May not be possible. Further, for example, when the BET specific surface area is more than 10.0 m ² / g and the 50% passing particle size is more than 20 μm, the capacity retention ratio may be lowered. Moreover, when the primary particle diameter is out of the above range, a high discharge capacity may not be obtained.

  On the other hand, the solid solution lithium-containing transition metal oxide B in the positive electrode active material of the present embodiment has e, f, g, and h of 0.3 ≦ e ≦ 0.7, 0 <f <in the composition formula (2). It is desirable to satisfy the relationship of 1.05, 0 <g <1.05, 0.15 <h ≦ 0.2, 1.3 ≦ e + f + g <1.35.

  The positive electrode active material containing such a solid solution lithium-containing transition metal oxide B can realize excellent discharge operating voltage and initial rate characteristics while maintaining a higher discharge capacity.

Similarly, the solid solution lithium-containing transition metal oxide B in the positive electrode active material of the present embodiment has a BET specific surface area of 0.8 m ² / g or more and 10.0 m ² / g or less, and a 50% passing particle diameter (D50). Is 20 μm or less, and the primary particle size is preferably 30 nm or more and 200 nm or less.

  Next, a method for producing a solid solution lithium-containing transition metal oxide in a positive electrode active material according to an embodiment of the present invention will be described in detail with some examples.

As an example of a method for producing a precursor of a solid solution lithium-containing transition metal oxide, a production method to which a carbonate method (a composite carbonate method) is applied can be mentioned. First, nickel (Ni), cobalt (Co), manganese (Mn) sulfates, nitrates, and the like are used as starting materials, and a predetermined amount is weighed to prepare a mixed solution thereof. Next, aqueous ammonia is added dropwise to the mixed solution until pH 7 is reached, and an aqueous solution of sodium carbonate (Na ₂ CO ₃ ) is further added dropwise to precipitate Ni—Co—Mn complex carbonate (Na ₂ CO _3). While the aqueous solution is being dropped, pH 7 is maintained with aqueous ammonia). Further, it is suction filtered, washed with water, dried, and pre-baked. As drying conditions, it may be dried in the atmosphere at 100 to 150 ° C. for about 2 to 10 hours (for example, 120 ° C. for 5 hours), but is not limited to this range. The pre-baking conditions may be pre-baking in the atmosphere at 360 to 600 ° C. for 3 to 10 hours (for example, 500 ° C. for 5 hours), but are not limited to this range. Furthermore, a small excess of lithium hydroxide (LiOH.H ₂ O) is added to the temporarily fired product and mixed. After that, by carrying out the main firing, a precursor of the solid solution lithium-containing transition metal oxide A can be produced. Preferably, after the main calcination, rapid cooling is performed using liquid nitrogen. This is because quenching with liquid nitrogen or the like after the main firing is preferable for reactivity and cycle stability. The main baking may be performed, for example, in the atmosphere at a baking temperature of 700 to 1000 ° C. (for example, 800 to 900 ° C.) for about 3 to 20 hours (for example, 12 hours).

  The solid solution lithium-containing transition metal oxide can be obtained by oxidizing the precursor. For example, (1) charging or charging / discharging in a predetermined potential range, specifically, charging or charging / discharging from a low potential region that does not cause a significant change in the crystal structure of the solid solution lithium-containing transition metal oxide from the beginning; 2) Oxidation with an oxidizing agent (for example, halogen such as bromine and chlorine) corresponding to charging, and (3) oxidation treatment such as oxidation with a redox mediator.

  Here, as the oxidation treatment method of (1), which is a relatively simple method among the oxidation treatments of (1) to (3), a state in which a battery is configured or an electrode or a configuration corresponding to an electrode, It is effective to charge or charge / discharge so as not to exceed a predetermined maximum potential (= charge / discharge pretreatment with regulated potential). Thereby, a high discharge capacity and a capacity maintenance rate can be realized. Therefore, it is suitably used for a positive electrode for lithium ion secondary batteries and a lithium ion secondary battery.

  As the charge / discharge pretreatment method with regulated potential, the highest potential in the predetermined potential range with respect to the lithium metal counter electrode (lithium metal or the upper limit potential of charge / discharge converted to lithium metal) is 4.3 V or more and 4.8 V or less. It is desirable to perform 1 to 30 charge / discharge cycles under the conditions. More preferably, it is desirable to perform charging and discharging for 1 to 30 cycles under the condition of 4.4V to 4.6V. By performing the oxidation treatment by charging / discharging within the above range, a high discharge capacity and capacity retention rate can be realized. In particular, when performing charging or charging / discharging with the maximum potential of about 4.8 V in order to obtain a high capacity after the oxidation treatment (pre-charge / discharge pretreatment with regulated potential), it is particularly effective to maintain a remarkable capacity maintenance rate. Can be expressed. Furthermore, in this case, it is preferable from the viewpoint of improving the capacity maintenance rate that the upper limit potential is gradually (stepwise) increased after charging / discharging at the initial predetermined upper limit potential. Note that the potential converted to the lithium metal or the lithium metal corresponds to a potential based on the potential exhibited by the lithium metal in the electrolytic solution in which 1 mol / L of lithium ions are dissolved.

Further, it is desirable to further increase the maximum potential in the predetermined potential range for charging and discharging stepwise after 1 to 30 cycles of charging and discharging in the predetermined potential range with respect to the lithium metal counter electrode.
In particular, 4.7V, 4.8Vvs. When using up to the high potential capacity of Li (use of high capacity), the maximum potential of the charge / discharge potential in the oxidation process is increased step by step, so that the oxidation process can be performed in a short time (pre-charge / discharge pretreatment) However, the durability of the electrode can be improved.

  The number of cycles required for charging and discharging at each stage when raising the maximum potential (upper limit potential) in a predetermined potential range of charging and discharging is not particularly limited, but a range of 1 to 10 is effective. . In addition, the total number of charge / discharge cycles in the oxidation process when increasing the maximum potential (upper limit potential) in the predetermined potential range of charge / discharge (the total number of cycles required for charge / discharge in each stage) ) Is not particularly limited, but a range of 4 to 20 times is effective.

  There is no particular limitation on the range of increase (increase) in potential when increasing the maximum potential (upper limit potential) in a predetermined potential range of charge and discharge in stages, but 0.05V to 0.1V is effective. is there.

  It is effective that the final maximum potential (end maximum potential) when increasing the maximum potential (upper limit potential) in a predetermined potential range of charge / discharge stepwise is 4.6V to 4.9V. . However, the present invention is not limited to the above range, and oxidation treatment (charge / discharge pretreatment with regulated potential) may be performed up to a higher termination maximum potential as long as the above effects can be achieved.

  The minimum potential in the predetermined potential range is not particularly limited, and is 2 V or more and less than 3.5 V, more preferably 2 V or more and less than 3 V with respect to the lithium metal counter electrode. A high discharge capacity and capacity retention ratio can be realized by performing oxidation treatment (charge / discharge pretreatment with a regulated potential) by charging or charging / discharging within the above range. The charge / discharge potential (V) refers to a potential per unit cell (unit cell).

  Further, the temperature of the electrode (material) to be charged / discharged as an oxidation treatment (electrochemical pretreatment by charge / discharge with regulated potential) can be arbitrarily set as long as it does not impair the effects of the present invention. it can. From the economical point of view, it is desirable to carry out at room temperature that does not require special heating and cooling. On the other hand, it is desirable to carry out at a temperature higher than room temperature from the viewpoint that a larger capacity can be expressed and the capacity retention rate can be improved by a short charge / discharge treatment.

  Furthermore, the step (time) of applying the oxidation treatment (electrochemical pretreatment by charge / discharge with regulated potential) method is not particularly limited. For example, as described above, such oxidation treatment can be performed in a state in which a battery is configured, or in a configuration corresponding to an electrode or an electrode. That is, any of application in the state of positive electrode active material powder, application by constituting an electrode, and application after assembling a battery together with the negative electrode may be used. Application to a battery can be carried out by applying an oxidation treatment condition (electrochemical pretreatment condition by charge / discharge with regulated potential) in consideration of the potential profile of the capacitance of the negative electrode to be combined.

  Here, in the case where the battery is configured, it is superior in that the oxidation treatment of many electrodes can be performed at a time, rather than the individual electrodes or the configuration corresponding to the electrodes. On the other hand, when it is performed for each electrode or for each electrode-corresponding configuration, it is easier to control conditions such as the oxidation potential than the state in which the battery is configured, and there is a variation in the degree of oxidation to each electrode. It is excellent in a difficult point.

  The oxidant used in the oxidation method (2) is not particularly limited, and for example, halogen such as bromine and chlorine can be used. These oxidizing agents may be used alone or in combination. Oxidation with an oxidizing agent can be gradually oxidized by, for example, dispersing solid solution fine particles in a solvent in which the solid solution lithium-containing transition metal oxide does not dissolve, and blowing and dissolving the oxidizing agent into the dispersion.

Furthermore, in the positive electrode active material of the present embodiment, the solid solution lithium-containing transition metal oxide A and the solid solution lithium-containing transition metal oxide B may satisfy the relationship of the following formula (3) and further (4). preferable.
_{0.50 ≦ M B / (M A} + M B) <1.00 ... (3)
_{0.75 ≦ M B / (M A} + M B) <1.00 ... (4)
(Equation (3), (4), M _A is the mass of the solid solution lithium-containing transition metal oxide A, M _B represents the mass of the solid solution lithium-containing transition metal oxide B.)
By setting it as such a range, the outstanding discharge operating voltage and the initial rate characteristic can be implement | achieved, maintaining a higher discharge capacity. Also, the initial charge / discharge efficiency is excellent.

  Next, a positive electrode for a lithium ion secondary battery and a lithium ion secondary battery according to an embodiment of the present invention will be described in detail with reference to the drawings. In addition, the dimension ratio of drawing quoted by the following embodiment is exaggerated on account of description, and may differ from an actual ratio.

  FIG. 2 is a schematic cross-sectional view showing an example of a lithium ion secondary battery according to an embodiment of the present invention. Such a lithium ion secondary battery is called a laminated lithium ion secondary battery.

  As shown in FIG. 2, the lithium ion secondary battery 1 of the present embodiment has a configuration in which a battery element 10 to which a positive electrode lead 21 and a negative electrode lead 22 are attached is enclosed in an exterior body 30 formed of a laminate film. have. In the present embodiment, the positive electrode lead 21 and the negative electrode lead 22 are led out in the opposite direction from the inside of the exterior body 30 to the outside. Although not shown, the positive electrode lead and the negative electrode lead may be led out in the same direction from the inside of the exterior body toward the outside. Moreover, such a positive electrode lead and a negative electrode lead can be attached to a positive electrode current collector and a negative electrode current collector described later by, for example, ultrasonic welding or resistance welding.

  The positive electrode lead 21 and the negative electrode lead 22 are made of, for example, a metal material such as aluminum (Al), copper (Cu), titanium (Ti), nickel (Ni), alloys thereof, and stainless steel (SUS). However, the material is not limited thereto, and a conventionally known material used as a lead for a lithium ion secondary battery can be used.

  The positive electrode lead and the negative electrode lead may be made of the same material or different materials. Further, as in the present embodiment, a separately prepared lead may be connected to a positive electrode current collector and a negative electrode current collector described later, and each positive electrode current collector and each negative electrode current collector described later are extended. The lead may be formed by this. Although not shown, the positive lead and the negative lead taken out from the exterior body do not affect products (for example, automobile parts, especially electronic devices) by contacting with peripheral devices or wiring and causing electric leakage. Thus, it is preferable to coat with a heat-resistant insulating heat-shrinkable tube or the like.

  Further, although not shown, a current collector plate may be used for the purpose of taking out the current outside the battery. The current collector plate is electrically connected to a current collector or a lead, and is taken out of a laminate film that is an exterior material of the battery. The material which comprises a current collector plate is not specifically limited, The well-known highly electroconductive material conventionally used as a current collector plate for lithium ion secondary batteries can be used. As a constituent material of the current collector plate, for example, metal materials such as aluminum (Al), copper (Cu), titanium (Ti), nickel (Ni), alloys thereof, and stainless steel (SUS) are preferable, and light weight and corrosion resistance. From the viewpoint of high conductivity, aluminum (Al), copper (Cu), and the like are more preferable. Note that the same material may be used for the positive electrode current collector plate and the negative electrode current collector plate, or different materials may be used.

  For example, the exterior body 30 is preferably formed of a film-shaped exterior material from the viewpoints of miniaturization and weight reduction, but is not limited thereto, and the exterior body for a lithium ion secondary battery is not limited thereto. The conventionally well-known thing used for the body can be used. That is, a metal can case can also be applied.

  From the viewpoint that it is excellent in high output and cooling performance, and can be suitably used for batteries for large equipment of electric vehicles and hybrid electric vehicles, for example, a polymer-metal composite laminate film having excellent thermal conductivity is used. Can be mentioned. More specifically, an outer package formed of a three-layer laminated film outer package in which polypropylene as a thermocompression bonding layer, aluminum as a metal layer, and nylon as an outer protective layer are laminated in this order is suitably used. Can be used.

  Note that the exterior body may be constituted by another structure, for example, a laminate film not having a metal material, a polymer film such as polypropylene, or a metal film, instead of the above-described laminate film.

  Here, the general structure of an exterior body can be represented by the laminated structure of an external protective layer / metal layer / thermocompression bonding layer (however, the external protective layer and the thermocompression bonding layer may be composed of a plurality of layers. .) As the metal layer, it is sufficient to function as a moisture-permeable barrier film, and not only aluminum foil, but also stainless steel foil, nickel foil, plated iron foil, etc. can be used, but it is thin and lightweight. Thus, an aluminum foil excellent in workability can be suitably used.

  The structures that can be used as the exterior body are listed in the form of (external protective layer / metal layer / thermocompression layer). Terephthalate / unstretched polypropylene, polyethylene terephthalate / nylon / aluminum / unstretched polypropylene, polyethylene terephthalate / nylon / aluminum / nylon / unstretched polypropylene, polyethylene terephthalate / nylon / aluminum / nylon / polyethylene, nylon / polyethylene / aluminum / linear Low density polyethylene, polyethylene terephthalate / polyethylene / aluminum / polyethylene terephthalate / Density polyethylene, and a polyethylene terephthalate / nylon / aluminum / low density polyethylene / cast polypropylene.

  As shown in FIG. 2, the battery element 10 includes a positive electrode 11 having a positive electrode active material layer 11B formed on both main surfaces of the positive electrode current collector 11A, an electrolyte layer 13, and a negative electrode current collector 12A. A plurality of negative electrodes 12 each having a negative electrode active material layer 12 </ b> B formed on the main surface are stacked. At this time, one main surface of the positive electrode active material layer 11B formed on one main surface of the positive electrode current collector 11A of one positive electrode 11 and the negative electrode current collector 12A of the negative electrode 12 adjacent to the one positive electrode 11 The negative electrode active material layer 12 </ b> B formed above faces the electrolyte layer 13. In this way, a plurality of layers are laminated in the order of the positive electrode, the electrolyte layer, and the negative electrode.

  As a result, the adjacent positive electrode active material layer 11B, electrolyte layer 13 and negative electrode active material layer 12B constitute one unit cell layer. Therefore, the lithium ion secondary battery 1 of the present embodiment has a configuration in which a plurality of single battery layers 14 are stacked and electrically connected in parallel. In addition, the positive electrode and the negative electrode may have each active material layer formed on one main surface of each current collector. In the present embodiment, for example, the negative electrode current collector 12a located in the outermost layer of the battery element 10 has the negative electrode active material layer 12B formed on only one side.

  In addition, an insulating layer (not shown) may be provided on the outer periphery of the unit cell layer to insulate between the adjacent positive electrode current collector and negative electrode current collector. Such an insulating layer is preferably formed of a material that retains the electrolyte contained in the electrolyte layer and the like and prevents electrolyte leakage from the outer periphery of the single cell layer. Specifically, general-purpose plastics such as polypropylene (PP), polyethylene (PE), polyurethane (PUR), polyamide resin (PA), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polystyrene (PS), etc. Or thermoplastic olefin rubber can be used. Silicone rubber can also be used.

The positive electrode current collector 11A and the negative electrode current collector 12A are made of a conductive material. The size of the current collector can be determined according to the intended use of the battery. For example, if it is used for a large battery that requires a high energy density, a current collector having a large area is used. There is no particular limitation on the thickness of the current collector. The thickness of the current collector is usually about 1 to 100 μm. The shape of the current collector is not particularly limited. In the battery element 10 shown in FIG. 2, in addition to the current collector foil, a mesh shape (expanded grid or the like) can be used.
In addition, when forming the thin film alloy which is an example of a negative electrode active material directly on the negative electrode collector 12A by sputtering method etc., it is desirable to use a current collection foil.

There is no particular limitation on the material constituting the current collector. For example, a metal or a resin in which a conductive filler is added to a conductive polymer material or a non-conductive polymer material can be employed.
Specifically, examples of the metal include aluminum (Al), nickel (Ni), iron (Fe), stainless steel (SUS), titanium (Ti), copper (Cu), and the like. In addition to these, it is preferable to use a clad material of nickel (Ni) and aluminum (Al), a clad material of copper (Cu) and aluminum (Al), or a plating material combining these metals. Moreover, the foil by which the metal surface was coat | covered with aluminum (Al) may be sufficient. Among these, aluminum (Al), stainless steel (SUS), copper (Cu), and nickel (Ni) are preferable from the viewpoint of electronic conductivity, battery operating potential, and the like.

  Examples of the conductive polymer material include polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyphenylene vinylene, polyacrylonitrile, and polyoxadiazole. Since such a conductive polymer material has sufficient conductivity without adding a conductive filler, it is advantageous in terms of facilitating the manufacturing process or reducing the weight of the current collector.

  Non-conductive polymer materials include, for example, polyethylene (PE; high density polyethylene (HDPE), low density polyethylene (LDPE), etc.), polypropylene (PP), polyethylene terephthalate (PET), polyether nitrile (PEN), polyimide (PI), polyamideimide (PAI), polyamide (PA), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA) , Polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polystyrene (PS), and the like. Such a non-conductive polymer material has excellent potential resistance or solvent resistance.

  A conductive filler can be added to the conductive polymer material or the non-conductive polymer material as necessary. In particular, when the resin used as the base material of the current collector is made of only a non-conductive polymer, a conductive filler is inevitably necessary to impart conductivity to the resin. The conductive filler can be used without particular limitation as long as it is a substance having conductivity. For example, a metal, conductive carbon, etc. are mentioned as a material excellent in electroconductivity, electric potential resistance, or lithium ion interruption | blocking property.

As metals, nickel (Ni), titanium (Ti), aluminum (Al), copper (Cu), platinum (Pt), iron (Fe), chromium (Cr), tin (Sn), zinc (Zn), indium Preferred examples include those containing at least one metal selected from the group consisting of (In), antimony (Sb), and potassium (K), or an alloy or metal oxide containing these metals. In addition, preferred examples of the conductive carbon include those containing at least one selected from the group consisting of acetylene black, vulcan, black pearl, carbon nanofiber, ketjen black, carbon nanotube, carbon nanohorn, carbon nanoballoon, and fullerene. Can be mentioned. The amount of the conductive filler added is not particularly limited as long as it is an amount capable of imparting sufficient conductivity to the current collector, and is generally about 5 to 35% by mass.
However, the material is not limited to these, and a conventionally known material used as a current collector for a lithium ion secondary battery can be used.

  The positive electrode active material layer 11B includes the positive electrode active material according to the embodiment of the present invention described above as the positive electrode active material, and may include a binder and a conductive additive as necessary.

Although it does not specifically limit as a binder (binder), For example, the following materials are mentioned.
Polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyether nitrile (PEN), polyacrylonitrile (PAN), polyimide (PI), polyamide (PA), cellulose, carboxymethylcellulose (CMC), ethylene-acetic acid Vinyl copolymer, polyvinyl chloride (PVC), styrene / butadiene rubber (SBR), isoprene rubber, butadiene rubber, ethylene / propylene rubber, ethylene / propylene / diene copolymer, styrene / butadiene / styrene block copolymer, and Its hydrogenated product, thermoplastic polymer such as styrene / isoprene / styrene block copolymer and its hydrogenated product, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), tetrafluoro Tylene / hexafluoropropylene copolymer (FEP), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), ethylene / tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene / Fluoropolymers such as chlorotrifluoroethylene copolymer (ECTFE) and polyvinyl fluoride (PVF), vinylidene fluoride-hexafluoropropylene fluororubber (VDF-HFP fluoropolymer), vinylidene fluoride-hexafluoropropylene-tetra Fluoroethylene fluoro rubber (VDF-HFP-TFE fluoro rubber), vinylidene fluoride-pentafluoropropylene fluoro rubber (VDF-PFP fluoro rubber), vinylidene fluoride- Interfluoropropylene-tetrafluoroethylene fluorine rubber (VDF-PFP-TFE fluorine rubber), vinylidene fluoride-perfluoromethyl vinyl ether-tetrafluoroethylene fluorine rubber (VDF-PFMVE-TFE fluorine rubber), vinylidene fluoride -Vinylidene fluoride-based fluororubber such as chlorotrifluoroethylene-based fluororubber (VDF-CTFE-based fluororubber), epoxy resin and the like. Among these, polyvinylidene fluoride, polyimide, styrene / butadiene rubber, carboxymethyl cellulose, polypropylene, polytetrafluoroethylene, polyacrylonitrile, and polyamide are more preferable. These suitable binders are excellent in heat resistance, have a very wide potential window, are stable at both the positive electrode potential and the negative electrode potential, and can be used for the positive electrode (and negative electrode) active material layer.
However, the material is not limited to these, and a known material conventionally used as a binder for a lithium ion secondary battery can be used. These binders may be used alone or in combination of two or more.

  The amount of the binder contained in the positive electrode active material layer is not particularly limited as long as it can bind the positive electrode active material, but preferably 0.5 to 15 mass with respect to the positive electrode active material layer. %, More preferably 1 to 10% by mass.

A conductive support agent is mix | blended in order to improve the electroconductivity of a positive electrode active material layer. As a conductive support agent, carbon materials, such as carbon black, such as acetylene black, a graphite, and a vapor growth carbon fiber, can be mentioned, for example. When the positive electrode active material layer contains a conductive additive, an electronic network inside the positive electrode active material layer is effectively formed, which can contribute to improvement of the output characteristics of the battery.
However, the material is not limited to these, and a conventionally known material that is used as a conductive additive for a lithium ion secondary battery can be used. These conductive assistants may be used alone or in combination of two or more.

  In addition, the conductive binder having the functions of the conductive assistant and the binder may be used in place of the conductive assistant and the binder, or one or both of the conductive assistant and the binder. You may use together. As the conductive binder, for example, commercially available TAB-2 (manufactured by Hosen Co., Ltd.) can be used.

Furthermore, the density of the positive electrode active material layer is preferably 2.5 g / cm ³ or more and 3.0 g / cm ³ or less. When the density of the positive electrode active material layer is less than 2.5 g / cm ³ , it is difficult to improve the discharge capacity because the weight (filling amount) per unit volume cannot be improved. Further, when the density of the positive electrode active material layer exceeds 3.0 g / cm ³ , the amount of voids in the positive electrode active material layer is remarkably reduced, and the permeability of the non-aqueous electrolyte and the lithium ion diffusibility may be reduced. is there.

  The negative electrode active material layer 12B includes, as a negative electrode active material, lithium, a lithium alloy, or a negative electrode material capable of occluding and releasing lithium, and includes a binder and a conductive aid as necessary. May be. In addition, what was demonstrated above can be used for a binder and a conductive support agent.

Examples of the negative electrode material capable of inserting and extracting lithium include graphite (natural graphite, artificial graphite, etc.), which is highly crystalline carbon, low crystalline carbon (soft carbon, hard carbon), carbon black (Ketjen) Carbon materials such as black, acetylene black, channel black, lamp black, oil furnace black, thermal black), fullerenes, carbon nanotubes, carbon nanofibers, carbon nanohorns, carbon fibrils (containing 10% by mass or less of silicon nanoparticles) Silicon (Si), germanium (Ge), tin (Sn), lead (Pb), aluminum (Al), indium (In), zinc (Zn), hydrogen (H), calcium (Ca), strontium( r), barium (Ba), ruthenium (Ru), rhodium (Rh), iridium (Ir), palladium (Pd), platinum (Pt), silver (Ag), gold (Au), cadmium (Cd), mercury ( Hg), gallium (Ga), thallium (Tl), carbon (C), nitrogen (N), antimony (Sb), bismuth (Bi), oxygen (O), sulfur (S), selenium (Se), tellurium ( Te), elemental elements that form an alloy with lithium, such as chlorine (Cl), and oxides containing these elements (silicon monoxide (SiO), SiO _x (0 <x <2), tin dioxide (SnO ₂ )) , SnO _x (0 <x <2), SnSiO ₃ etc.) and carbides (silicon carbide (SiC) etc.), etc .; metal materials such as lithium metal; lithium-titanium composite oxide (lithium titanate: Li ₄ Ti ₅ O _12), etc. Lithium - can be exemplified transition metal composite oxide. However, it is not limited to these, The conventionally well-known material used as a negative electrode active material for lithium ion secondary batteries can be used. These negative electrode active materials may be used alone or in combination of two or more.

Further, in the present embodiment, the carbon material is made of a graphite material that is coated with an amorphous carbon layer and is not scale-like, and the BET specific surface area of the carbon material is 0.8 m ² / g or more and 1.5 m. ² / g or less and the tap density is preferably 0.9 g / cm ³ or more and 1.2 g / cm ³ or less. A carbon material made of a graphite material that is coated with an amorphous carbon layer and is not scale-like is preferable because of its high lithium ion diffusibility into the graphite layered structure. Moreover, it is preferable that the BET specific surface area of such a carbon material is 0.8 m ² / g or more and 1.5 m ² / g or less because the capacity retention rate can be further improved. Furthermore, when the tap density of such a carbon material is 0.9 g / cm ³ or more and 1.2 g / cm ³ or less, the weight (filling amount) per unit volume can be improved, and the discharge capacity is improved. be able to.

Furthermore, in the present embodiment, it is preferable that the negative electrode active material layer including at least the carbon material and the binder has a BET specific surface area of 2.0 m ² / g or more and 3.0 m ² / g or less. When the BET specific surface area of the negative electrode active material layer is 2.0 m ² / g or more and 3.0 m ² / g or less, the permeability of the non-aqueous electrolyte can be improved, and the capacity retention rate is further improved, Gas generation due to decomposition of the non-aqueous electrolyte can be suppressed.

In the present embodiment, the negative electrode active material layer containing at least a carbon material and a binder preferably has a BET specific surface area after pressure molding of 2.01 m ² / g or more and 3.5 m ² / g or less. It is. By setting the BET specific surface area of the negative electrode active material layer after pressure molding to 2.01 m ² / g or more and 3.5 m ² / g or less, the permeability of the non-aqueous electrolyte can be improved and the capacity can be maintained. The rate can be improved and gas generation due to decomposition of the non-aqueous electrolyte can be suppressed.

Furthermore, in the present embodiment, the increase in the BET specific surface area before and after pressure press molding of the negative electrode active material layer containing at least the carbon material and the binder is 0.01 m ² / g to 0.5 m ² / g. Preferably it is. Since the BET specific surface area after pressure forming of the negative electrode active material layer can be 2.01 m ² / g or more and 3.5 m ² / g or less, the permeability of the non-aqueous electrolyte can be improved. The capacity retention rate can be improved and gas generation due to decomposition of the non-aqueous electrolyte can be suppressed.

  Further, the thickness of each active material layer (active material layer on one side of the current collector) is not particularly limited, and conventionally known knowledge about the battery can be referred to as appropriate. For example, the thickness of each active material layer is usually about 1 to 500 μm, preferably 2 to 100 μm in consideration of the intended use of the battery (emphasis on output, energy, etc.) and ion conductivity.

Furthermore, when the optimum particle diameter is different for expressing the unique effect of each active material, the optimum particle diameters may be used in combination for expressing each unique effect. There is no need to make the particle size of the material uniform.
For example, when an oxide in the form of particles is used as the positive electrode active material, the average particle size of the oxide may be approximately the same as the average particle size of the positive electrode active material included in the existing positive electrode active material layer, and is not particularly limited. . From the viewpoint of increasing the output, it is preferably in the range of 1 to 20 μm. In the present specification, the “particle diameter” refers to the outline of active material particles (observation surface) observed using an observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). It means the maximum distance among any two points. As the value of “average particle diameter”, the average particle diameter of particles observed in several to several tens of fields using an observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The calculated value shall be adopted. The particle diameters and average particle diameters of other components can be defined in the same manner.
However, it is not limited to such a range at all, and it goes without saying that it may be outside this range as long as the effects of the present embodiment can be expressed effectively.

  As the electrolyte layer 13, for example, an electrolyte solution, a polymer gel electrolyte, a solid polymer electrolyte formed in a separator described later, and a layer structure formed using a solid polymer electrolyte, or a polymer gel electrolyte or a solid polymer electrolyte are used. Examples thereof include those having a laminated structure formed thereon.

For example, the electrolyte solution is preferably one that is usually used in a lithium ion secondary battery, and specifically has a form in which a supporting salt (lithium salt) is dissolved in an organic solvent. Examples of the lithium salt include lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium perchlorate (LiClO ₄ ), lithium hexafluoroarsenate (LiAsF ₆ ), six Inorganic acid anion salts such as lithium fluorotantalate (LiTaF ₆ ), lithium tetrachloroaluminate (LiAlCl ₄ ), lithium decachlorodecaborate (Li ₂ B ₁₀ Cl ₁₀ ), lithium trifluoromethanesulfonate (LiCF ₃₎ Organic acids such as SO ₃ ), lithium bis (trifluoromethanesulfonyl) imide (Li (CF ₃ SO ₂ ) ₂ N), lithium bis (pentafluoroethanesulfonyl) imide (Li (C ₂ F ₅ SO ₂ ) ₂ N) List at least one lithium salt selected from anionic salts Can. Among these, lithium hexafluorophosphate (LiPF ₆ ) is preferable.

Examples of the organic solvent include cyclic carbonates, fluorine-containing cyclic carbonates, chain carbonates, fluorine-containing chain carbonates, aliphatic carboxylic acid esters, fluorine-containing aliphatic carboxylic acid esters, and γ-lactone. , Fluorine-containing γ-lactones, cyclic ethers, fluorine-containing cyclic ethers, chain ethers, and at least one organic solvent selected from the group consisting of fluorine-containing chain ethers can be used.
Examples of cyclic carbonates include propylene carbonate (PC), ethylene carbonate (EC), and butylene carbonate (BC). Moreover, as a fluorine-containing cyclic carbonate, fluoroethylene carbonate (FEC) can be mentioned, for example. Further, examples of the chain carbonates include dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), and dipropyl carbonate (DPC). Can be mentioned. Examples of the aliphatic carboxylic acid esters include methyl formate, methyl acetate, and ethyl propionate. Furthermore, examples of γ-lactones include γ-butyrolactone. Examples of cyclic ethers include tetrahydrofuran, 2-methyltetrahydrofuran, and 1,4-dioxane. Furthermore, examples of the chain ethers include 1,2-ethoxyethane (DEE), ethoxymethoxyethane (EME), diethyl ether, 1,2-dimethoxyethane, and 1,2-dibutoxyethane. . Other examples include nitriles such as acetonitrile and amides such as dimethylformamide. These can be used alone or in combination of two or more.

  The electrolyte includes organic sulfone compounds such as sultone derivatives and cyclic sulfonic acid esters, organic disulfone compounds such as disulfone derivatives and cyclic disulfonic acid esters, vinylene carbonate derivatives, ethylene carbonate derivatives, ester derivatives, divalent phenol derivatives, ethylene Additives such as glycol derivatives, terphenyl derivatives, and phosphate derivatives may be added. These form a film on the surface of the negative electrode active material, reduce gas generation in the battery, and further improve the capacity retention rate.

  Examples of the organic sulfone compounds include 1,3-propanesulfone (saturated sultone) and 1,3-propene sultone (unsaturated sultone). Examples of organic disulfone compounds include methylene methanedisulfonate. Examples of the vinylene carbonate derivative include vinylene carbonate (VC). Moreover, as an ethylene carbonate derivative, fluoroethylene carbonate (FEC) can be mentioned, for example. Furthermore, examples of the ester derivative include 4-biphenylyl acetate, 4-biphenylyl benzoate, 4-biphenylyl benzyl carboxylate, and 2-biphenylyl propionate. Examples of the divalent phenol derivative include 1,4-diphenoxybenzene and 1,3-diphenoxybenzene. Furthermore, examples of the ethylene glycol derivative include 1,2-diphenoxyethane, 1- (4-biphenylyloxy) -2-phenoxyethane, and 1- (2-biphenylyloxy) -phenoxyethane. . Examples of the terphenyl derivative include o-terphenyl, m-terphenyl, p-terephenyl, 2-methyl-o-terphenyl, and 2,2-dimethyl-o-terphenyl. Further, examples of the phosphate derivative include triphenyl phosphate.

  Examples of the separator include a microporous film made of polyolefin such as polyethylene (PE) and polypropylene (PP), a porous flat plate, and a nonwoven fabric.

Examples of the polymer gel electrolyte include those containing a polymer constituting the polymer gel electrolyte and an electrolytic solution in a conventionally known ratio. For example, from the viewpoint of ionic conductivity and the like, it is desirable to set it to about several to 98% by mass.
The polymer gel electrolyte is a solid polymer electrolyte having ion conductivity containing the above-described electrolytic solution usually used in a lithium ion secondary battery. However, the present invention is not limited to this, and includes a structure in which a similar electrolyte solution is held in a polymer skeleton having no lithium ion conductivity.

  Examples of the polymer having no lithium ion conductivity used in the polymer gel electrolyte include polyvinylidene fluoride (PVDF), polyvinyl chloride (PVC), polyacrylonitrile (PAN), and polymethyl methacrylate (PMMA). Can be used. However, it is not necessarily limited to these. In addition, since polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), and the like are in a class that has almost no ionic conductivity, it can be a polymer having the ionic conductivity. Here, the polymer used for the polymer gel electrolyte is exemplified as a polymer having no lithium ion conductivity.

  Examples of the solid polymer electrolyte include a structure in which the lithium salt is dissolved in polyethylene oxide (PEO), polypropylene oxide (PPO), and the like, and does not contain an organic solvent. Therefore, when the electrolyte layer is composed of a solid polymer electrolyte, there is no fear of liquid leakage from the battery, and the battery reliability can be improved.

The thickness of the electrolyte layer is preferably thinner from the viewpoint of reducing internal resistance. The thickness of the electrolyte layer is usually 1 to 100 μm, preferably 5 to 50 μm.
A polymer gel electrolyte or a solid polymer electrolyte matrix polymer can exhibit excellent mechanical strength by forming a cross-linked structure. In order to form a crosslinked structure, a suitable polymerization initiator is used to polymerize a polymer for forming a polymer electrolyte (for example, polyethylene oxide (PEO) or polypropylene oxide (PPO)) by thermal polymerization, ultraviolet polymerization, A polymerization treatment such as radiation polymerization or electron beam polymerization may be performed.

Next, the manufacturing method of the lithium ion secondary battery of the present embodiment described above will be described with some examples.
An example of a method for manufacturing a lithium ion secondary battery will be described. First, a positive electrode is produced. For example, when a granular positive electrode active material is used, a positive electrode slurry is prepared by mixing the positive electrode active material described above and, if necessary, a conductive additive, a binder, and a viscosity adjusting solvent.
Next, this positive electrode slurry is applied to a positive electrode current collector, dried, and compression molded to form a positive electrode active material layer.

  Moreover, a negative electrode is produced. For example, when a granular negative electrode active material is used, a negative electrode active material and, if necessary, a conductive additive, a binder, and a viscosity adjusting solvent are mixed to prepare a negative electrode slurry. Thereafter, the negative electrode slurry is applied to a negative electrode current collector, dried, and compression molded to form a negative electrode active material layer.

  Next, the positive electrode lead is attached to the positive electrode and the negative electrode lead is attached to the negative electrode, and then the positive electrode, the separator, and the negative electrode are laminated. Further, the laminated product is sandwiched between polymer-metal composite laminate sheets, and the outer peripheral edge except one side is heat-sealed to form a bag-like exterior body.

  After that, a non-aqueous electrolyte containing a lithium salt such as lithium hexafluorophosphate and an organic solvent such as ethylene carbonate is prepared and injected into the interior through the opening of the exterior body, and the opening of the exterior body is thermally melted. Wear and enclose. Thereby, a laminate-type lithium ion secondary battery is completed.

Another example of a method for producing a lithium ion secondary battery will be described. First, a positive electrode is produced. For example, when using a granular positive electrode active material, the above-mentioned solid solution lithium-containing transition metal oxide precursor is mixed with a conductive additive, a binder and a viscosity adjusting solvent as necessary to prepare a positive electrode slurry.
Next, this positive electrode slurry is applied to a positive electrode current collector, dried, and compression molded to form a positive electrode active material layer.

  Moreover, a negative electrode is produced. For example, when a granular negative electrode active material is used, a negative electrode active material and, if necessary, a conductive additive, a binder, and a viscosity adjusting solvent are mixed to prepare a negative electrode slurry. Thereafter, the negative electrode slurry is applied to a negative electrode current collector, dried, and compression molded to form a negative electrode active material layer.

  Next, the positive electrode lead is attached to the positive electrode and the negative electrode lead is attached to the negative electrode, and then the positive electrode, the separator, and the negative electrode are laminated. Further, the laminated product is sandwiched between polymer-metal composite laminate sheets, and the outer peripheral edge except one side is heat-sealed to form a bag-like exterior body.

  After that, a non-aqueous electrolyte containing a lithium salt such as lithium hexafluorophosphate and an organic solvent such as ethylene carbonate is prepared and injected into the interior through the opening of the exterior body, and the opening of the exterior body is thermally melted. Wear and enclose. Furthermore, the predetermined charging or charging / discharging described above is performed, thereby completing a laminated lithium ion secondary battery.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.

Example 1
<Synthesis of Solid Solution Lithium-Containing Transition Metal Oxide A1>
The solid solution lithium-containing transition metal oxide A1 was synthesized using a composite carbonate method. Nickel (Ni), cobalt (Co), manganese (Mn) sulfate was used as a starting material, and a 2 mol / L sulfate aqueous solution was prepared. A 2 mol / L sodium carbonate aqueous solution was used as the precipitant, and a 0.2 mol / L ammonia aqueous solution was used as the pH adjuster.
A sodium carbonate aqueous solution was dropped into a composite sulfate aqueous solution stirred with a magnetic stirrer to precipitate the precursor. Thereafter, suction filtration was performed, and the precipitate deposited on the filter paper was dried to obtain a composite hydroxide precursor.
Thereafter, the obtained precursor and lithium carbonate are pulverized and mixed at a predetermined molar ratio, calcined at 500 ° C., and finally calcined at 800 ° C. to 1000 ° C. for 12 hours to 24 hours in the air to obtain a target sample. Obtained.

<Synthesis of lithium-containing transition metal oxide B1>
Lithium-containing transition metal oxide B1 was synthesized by the same composite carbonate method as the above-described solid solution lithium-containing transition metal oxide A1.

<Composition of solid solution lithium-containing transition metal oxide A1>
Composition formula: Li1.5 [Ni _0.525 Mn _0.825 [Li] _0.15 ] O ₃
(A + b + c + d = 1.5, d = 0.15, a + b + c = 1.35)

<Composition of solid solution lithium-containing transition metal oxide B1>
Composition formula: Li _1.5 [Ni _0.3 Mn _0.9 [Li] _0.3 ] O ₃
(A + b + c + d = 1.5, d = 0.3, a + b + c = 1.2)

<Composition of slurry for positive electrode>
Positive electrode active material: solid solution lithium-containing transition metal oxide A1: 75 parts by mass
: Lithium-containing transition metal oxide B1: 25 parts by mass conductive auxiliary agent: flake graphite: 2.0 parts by mass
: Acetylene black: 3.5 parts by mass Binder: Polyvinylidene fluoride (PVDF): 5.5 parts by mass Solvent: N-methylpyrrolidone (NMP): 74 parts by mass

<Production of positive electrode slurry>
A binder solution was prepared by dissolving 5.5 parts by mass of the binder in 49.5 parts by mass of NMP. Next, 55.0 parts by mass of the binder solution is added to the mixed powder of 5.5 parts by mass of the conductive additive and 100 parts by mass of the positive electrode active material, and a planetary mixer (manufactured by Primics, Hibismix 2P-03 type) is used. After kneading, 24.5 parts by mass of NMP was added to the kneaded product to obtain a slurry for positive electrode (solid content concentration 60% by mass).

<Application and drying of positive electrode slurry>
The obtained positive electrode slurry was applied to one side of a current collector made of 20 μm thick aluminum foil by a bar coater. Next, the current collector coated with the positive electrode slurry was dried on a hot plate at 120 to 130 ° C. for 10 minutes, so that the amount of NMP remaining in the positive electrode active material layer was 0.02 mass% or less.

<Positive electrode press>
The obtained sheet-like positive electrode is compression-molded using a roll press, cut, and the positive electrode active material layer on one side has a weight of about 3.5 mg / cm ² , a thickness of about 50 μm, and a density of 2.70 g / cm ³ . C1 was obtained.

<Drying the positive electrode>
Next, using this positive electrode C1, a drying process was performed in a vacuum drying furnace. After the positive electrode C1 was installed inside the drying furnace, the pressure in the room was reduced (100 mmHg (1.33 × 10 ⁴ Pa)) at room temperature (25 ° C.) to remove the air in the drying furnace. Next, while flowing nitrogen gas (100 cm ³ / min), the temperature was raised to 120 ° C. at 10 ° C./min, the pressure was reduced again at 120 ° C., and the nitrogen in the furnace was kept exhausted for 12 hours, and then to room temperature. The temperature was lowered to obtain a positive electrode C11.

<Production of lithium ion secondary battery>
After the positive electrode C11 produced in Example 1 was punched out to 15 mm in diameter, it was used again after drying for 2 hours at 100 ° C. in a vacuum dryer before producing the battery. In addition, a polypropylene porous film, a coin cell member, and the like were previously dried at room temperature for 24 hours or more in a glove box in an argon gas atmosphere.
In a glove box in an argon gas atmosphere, a positive electrode and a negative electrode made of metallic lithium were opposed to each other, and two separators (material: polypropylene, thickness: 20 μm) were disposed therebetween.
Next, this negative electrode, separator, and positive electrode laminate was placed on the bottom side of a coin cell (CR2032, material: stainless steel (SUS316)).
Furthermore, by attaching a gasket to maintain the insulation between the positive electrode and the negative electrode, injecting 150 μL of the following electrolyte using a syringe, laminating the spring and spacer, and overlapping and caulking the upper side of the coin cell Sealed to produce a lithium ion secondary battery.
As an electrolytic solution, lithium hexafluorophosphate as a supporting salt is mixed with an organic solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) are mixed at a ratio of EC: DEC = 1: 2 (volume ratio). (LiPF ₆₎ the concentration was used dissolved at a 1 mol / L. No special additives were added to the electrolyte.
Thereafter, the battery element was set on an evaluation cell attachment jig, and a positive electrode lead and a negative electrode lead were attached to each tab end portion of the battery element to perform a test.

<Electrochemical pretreatment>
Charging is performed at a constant current constant voltage charging (CCCV) method in which the battery is charged at a rate of 0.1 C until the maximum voltage of the battery reaches 4.2 V and then held for about 24 hours. It was performed by a constant current discharge (CC) method in which discharge was performed at a 1.0 C rate until
Next, as shown in Table 1, after charging at a 0.1 C rate until the maximum voltage is 4.5 V, a constant current charge / discharge cycle is performed at a 0.1 C rate until the minimum voltage is 2.0 V. After charging twice at a 0.1 C rate until the maximum voltage reaches 4.6 V, and then discharging at a constant current charge / discharge cycle of 0.1 C rate until the minimum voltage reaches 2.0 V, the maximum voltage is 4 After charging at a 0.1 C rate until 0.7 V is reached, a constant-current charge / discharge cycle is performed in which the battery is discharged at a 0.1 C rate until the minimum voltage is 2.0 V, until the maximum voltage reaches 4.8 V. After charging at a 1C rate, one constant current charge / discharge cycle that discharges at a 0.1C rate until the minimum voltage reaches 2.0V, and a constant current / constant voltage at a 0.1C rate until the maximum voltage reaches 4.8V After charging, 0 until the minimum voltage reaches 2.0V The cycle of constant current discharge at 1C rate were carried out once. All were performed at room temperature. Thus, the lithium ion secondary battery of this example was obtained.

(Example 2)
In the composition of the positive electrode slurry, the same operation as in Example 1 was repeated except that the solid solution lithium-containing transition metal oxide A1 was 50 parts by mass and the solid solution lithium-containing transition metal oxide B1 was 50 parts by mass. An example lithium ion secondary battery was obtained.

(Example 3)
In the composition of the positive electrode slurry, the same operation as in Example 1 was repeated except that the solid solution lithium-containing transition metal oxide A1 was 25 parts by mass and the solid solution lithium-containing transition metal oxide B1 was 75 parts by mass. An example lithium ion secondary battery was obtained.

Example 4
<Synthesis of transition metal oxide A2 containing solid solution lithium>
The solid solution lithium-containing transition metal oxide A2 was synthesized using the same composite carbonate method as the transition metal oxide A1 synthesized in Example 1 above.

<Composition of solid solution lithium-containing transition metal oxide A2>
Composition formula: Li _1.5 [Ni _0.4 Co _0.4 Mn _0.6 [Li] _0.1 ] O ₃
(A + b + c + d = 1.5, d = 0.1, a + b + c = 1.4)

  In the composition of the positive electrode slurry, the same operation as in Example 1 was repeated except that the solid solution lithium-containing transition metal oxide A2 was 75 parts by mass and the solid solution lithium-containing transition metal oxide B1 was 25 parts by mass. An example lithium ion secondary battery was obtained.

(Example 5)
In the composition of the positive electrode slurry, the same operation as in Example 1 was repeated except that 50 parts by mass of the solid solution lithium-containing transition metal oxide A2 and 50 parts by mass of the solid solution lithium-containing transition metal oxide B1 were repeated. An example lithium ion secondary battery was obtained.

(Example 6)
In the composition of the positive electrode slurry, the same operation as in Example 1 was repeated except that the solid solution lithium-containing transition metal oxide A2 was 25 parts by mass and the solid solution lithium-containing transition metal oxide B1 was 75 parts by mass. An example lithium ion secondary battery was obtained.

(Comparative Example 1)
In the composition of the positive electrode slurry, the same operation as in Example 1 was repeated except that the solid solution lithium-containing transition metal oxide A1 was changed to 100 parts by mass to obtain a lithium ion secondary battery of this example.

(Comparative Example 2)
In the composition of the positive electrode slurry, the same operation as in Example 1 was repeated except that the solid solution lithium-containing transition metal oxide A2 was changed to 100 parts by mass to obtain a lithium ion secondary battery of this example.

(Comparative Example 3)
In the composition of the positive electrode slurry, the same operation as in Example 1 was repeated except that the solid solution lithium-containing transition metal oxide B1 was set to 100 parts by mass to obtain a lithium ion secondary battery of this example. Table 2 shows a part of the specifications of the positive electrode active material in each of the above examples.

[Performance evaluation]
(Battery discharge capacity and average voltage)
For the lithium ion secondary batteries of the above examples, as shown in Table 3, after charging at a constant current and constant voltage at a rate of 0.1 C until the maximum voltage reaches 4.8 V, the minimum voltage becomes 2.0 V. A cycle of constant current discharge at a rate of 0.1 C was performed twice. At this time, the discharge capacity and average voltage of the battery were measured and calculated. In the present invention, the discharge operating voltage is evaluated based on the average voltage. The obtained results are also shown in Table 2.

(Charge / discharge efficiency)
Moreover, with respect to the lithium ion secondary battery of each of the above examples, the charge capacity and the discharge capacity were measured in the electrochemical pretreatment and the main charge / discharge cycle. At this time, from the ratio of the discharge capacity in the last discharge in the main charge / discharge cycle to the difference in the charge capacity in the charge / discharge cycle in the electrochemical pretreatment, the difference in the charge capacity in the main charge / discharge cycle, and the total charge capacity in the last charge The charge / discharge efficiency was calculated. The obtained results are also shown in Table 2.

  For the lithium ion secondary batteries of the above examples, as shown in Table 4, after charging at constant current and constant voltage at a rate of 0.1 C until the maximum voltage reaches 4.8 V, the minimum voltage becomes 2.0 V. 2 cycles of constant current discharge at 0.1C rate until 0.5V rate until the minimum voltage reaches 2.0V after charging at constant current and constant voltage at 0.1C rate until the maximum voltage reaches 4.8V The constant current discharge cycle is performed twice at a constant current constant voltage charge at a 0.1 C rate until the maximum voltage is 4.8 V, and then the constant current discharge is performed at a 1 C rate until the minimum voltage is 2.0 V. Two cycles of constant current and constant voltage charge at a 0.1C rate until the maximum voltage reaches 4.8V and then constant current discharge at a 2.5C rate until the minimum voltage reaches 2.0V 0.1C rate until 4.8V After constant-current constant-voltage charging, the lowest voltage is twice the cycle of constant current discharge at 0.1C rate until 2.0 V. All were performed at room temperature. At this time, the discharge capacity of the battery at each rate was measured, the capacity maintenance rate was calculated, and the initial rate characteristics were calculated from the ratio of the capacity maintenance rate at the 2.5 C rate to the capacity maintenance rate at the 0.1 C rate. The obtained results are also shown in Table 2.

  From Table 2, Examples 1 to 6 belonging to the scope of the present invention have excellent discharge operating voltage and initial value while maintaining a high discharge capacity as compared with Comparative Examples 1 to 3 outside the present invention. It can be seen that rate characteristics can be realized. In addition, in the result shown in Table 1, the result which attached | subjected "*" shows what has improved from the arithmetic average value according to the mixing ratio calculated | required from the result of the comparative example 1 or the comparative example 2 and the comparative example 3 . Among these, Example 2 and Example 5 are considered to be particularly excellent.

In addition, about the solid solution lithium containing transition metal oxide A taken out by disassembling the lithium ion secondary battery of each example, the layered structure site is present due to the presence of a peculiar peak in the layered structure and spinel structure by X-ray diffraction analysis (XRD). And having a spinel structure site.
Further, the solid solution lithium-containing transition metal oxide B taken out by disassembling the lithium ion secondary battery in each example has a spinel structure due to the presence of a peak specific to the spinel structure by X-ray diffraction analysis (XRD). confirmed. The structure may be confirmed by electron diffraction analysis, and the composition can be confirmed by, for example, inductively coupled plasma (ICP).

  As mentioned above, although this invention was demonstrated with some embodiment and an Example, this invention is not limited to these, A various deformation | transformation is possible within the range of the summary of this invention.

  That is, in the above-described embodiments and examples, as the lithium ion secondary battery, a laminate type battery or a coin type battery is exemplified, but the present invention is not limited to this, and a sheet type battery, a button type battery, a square shape or a cylindrical shape is not limited thereto. It can also be applied to a conventionally known form / structure such as a can-type battery.

  Further, for example, the present invention can be applied not only to the above-described stacked type (flat type) battery but also to conventionally known forms and structures such as a wound type (cylindrical type) battery.

  Furthermore, for example, the present invention is not only the above-described normal type (internal parallel connection type) battery but also a bipolar type (internal series connection) when viewed in terms of electrical connection form (electrode structure) in a lithium ion secondary battery. It can also be applied to conventionally known forms and structures such as type) batteries. A battery element in a bipolar battery generally has a bipolar electrode in which a negative electrode active material layer is formed on one surface of a current collector and a positive electrode active material layer is formed on the other surface, and an electrolyte layer. A plurality of layers.

  Furthermore, in the embodiments and examples described above, the lithium ion secondary battery has been described as an example of the electric device, but the present invention is not limited to this, and the present invention may be applied to a lithium ion capacitor or the like. it can.

DESCRIPTION OF SYMBOLS 1 Lithium ion secondary battery 10 Battery element 11 Positive electrode 11A Positive electrode collector 11B Positive electrode active material layer 12 Negative electrode 12A Negative electrode collector 12B Negative electrode active material layer 13 Electrolyte layer 14 Single battery layer 21 Positive electrode lead 22 Negative electrode lead 30 Exterior body

Claims (10)

A positive electrode active material containing a solid solution lithium-containing transition metal oxide A and a solid solution lithium-containing transition metal oxide B,
The solid solution lithium-containing transition metal oxide A has a composition formula (1)
Li _1.5 [Ni _a Co _b Mn _c [Li] _d ] O ₃ (1)
(In the formula (1), Li is lithium, Ni is nickel, Co is cobalt, Mn is manganese, O is oxygen, and a, b, c, and d are 0.1 ≦ a <0.5, 0 ≦ b <1.15, 0 <c <1.15, 0.25 <d ≦ 0.4, a + b + c + d = 1.5, 1.1 ≦ a + b + c <1.25 are satisfied.)
A layered structure part that changes to a spinel structure by charging or charging / discharging in a potential range of 4.3 V to 4.8 V, and a layered structure part that does not change;
When the change rate of spinel structure when all the Li ₂ MnO ₃ in the layered structure portion changed to the spinel structure LiMn ₂ O ₄ is 1, the spinel structure change rate is 0.25 or more and less than 1.0. ,
The solid solution lithium-containing transition metal oxide B has a composition formula (2)
_{Li 1.5 [Ni e Co f Mn} g [Li] h] O 3 ... (2)
(In the formula (2), Li is lithium, Ni is nickel, Co is cobalt, Mn is manganese, O is oxygen, and e, f, g, and h are 0.25 ≦ e ≦ 0.7, 0 <. f <1.1, 0 <g <1.1, 0.15 ≦ h ≦ 0.25, e + f + g + h = 1.5, and 1.25 ≦ e + f + g ≦ 1.35 are satisfied.)
A layered structure part that changes to a spinel structure by charging or charging / discharging in a potential range of 4.3 V to 4.8 V, and a layered structure part that does not change;
The spinel structure change ratio is 0.25 or more and less than 1.0, assuming that the spinel structure change ratio is 1 when Li ₂ MnO _{3 in the} above-mentioned changing layered structure portion is changed to the spinel structure LiMn ₂ O _4. A positive electrode active material characterized by the above. The positive electrode active material according to claim 1, wherein the solid solution lithium-containing transition metal oxide A and the solid solution lithium-containing transition metal oxide B satisfy the relationship of the following formula (3).
_{0.50 ≦ M B / (M A} + M B) <1.00 ... (3)
(Equation (3), M _A is the mass of the solid solution lithium-containing transition metal oxide A, M _B represents the mass of the solid solution lithium-containing transition metal oxide B.) The positive electrode active material according to claim 1 or 2, wherein the solid solution lithium-containing transition metal oxide A and the solid solution lithium-containing transition metal oxide B satisfy the relationship of the following formula (4).
_{0.75 ≦ M B / (M A} + M B) <1.0 ... (4)
(Formula (4) in, M _A is the mass of the solid solution lithium-containing transition metal oxide A, M _B represents the mass of the solid solution lithium-containing transition metal oxide B.) In the solid solution lithium-containing transition metal oxide A, in the above formula (1), a, b, c and d are 0.15 ≦ a ≦ 0.5, 0 <b <0.5, 0.15 <c. <1.1, 0.25 ≦ d ≦ 0.35, a + b + c + d = 1.5, 1.25 ≦ a + b + c ≦ 1.25, and 0 <b / a <1 are satisfied. The positive electrode active material according to any one of items 1 to 3. In the solid solution lithium-containing transition metal oxide B, in the above formula (2), e, f, g, and h are 0.3 ≦ e ≦ 0.7, 0 <f <1.05, 0 <g <1. The positive electrode active material according to claim 1, wherein the following relationships are satisfied: 0.05, 0.15 <h ≦ 0.2, 1.3 ≦ e + f + g <1.35. The solid solution lithium-containing transition metal oxide A has a BET specific surface area of 0.8 m ² / g or more and 10.0 m ² / g or less,
50% passage particle size of the solid solution lithium-containing transition metal oxide A is 20 μm or less,
The positive electrode active material according to any one of claims 1 to 5, wherein a primary particle size of the solid solution lithium-containing transition metal oxide A is 30 nm or more and 200 nm or less. The solid solution lithium-containing transition metal oxide B has a BET specific surface area of 0.8 m ² / g or more and 10.0 m ² / g or less,
50% passage particle size of the solid solution lithium-containing transition metal oxide B is 20 μm or less,
The positive electrode active material according to any one of claims 1 to 6, wherein a primary particle diameter of the solid solution lithium-containing transition metal oxide B is 30 nm or more and 200 nm or less.   A positive electrode for an electric device, comprising the positive electrode active material according to claim 1.   An electric device comprising the positive electrode for an electric device according to claim 8.   The electrical device according to claim 8, wherein the electrical device is a lithium ion secondary battery.

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