Lithium metal composite oxide, positive electrode active material for lithium secondary battery, positive electrode for lithium secondary battery, and lithium secondary battery

Abstract

Provided is a lithium metal composite oxide or the like with which it is possible to improve the discharge capacity at a high rate. In the lithium metal composite oxide having pores, the maximum value dV1 of the ratio dVp / ddp of the pore volume Vp of the pores, which increases with respect to the increase in the pore diameter dp of the pores, in a range in which the ratio dap / ddp of the pore surface area ap of the pores with respect to the increase in the pore diameter dp of the pores satisfies the relationship dap / ddp < = 0.10, satisfies the relationship represented by dV1 < = 1.00 * 10 <-4 >, and satisfies the relationship dap / ddpgt; and the maximum value dV1 of the ratio dVp / ddp of the pore volume Vp of the pores with respect to the increase in the pore diameter dp of the pores satisfies the relationship dV1 < = 1.00 * 10 <-4 >. And the maximum value dV2 of dVp / ddp in the range of the relationship of 0.10 ''satisfies the relationship represented by dV2 > = 1.00 * 10 <-4 >.

Description

TECHNICAL FIELD

[0001] The present application relates to a lithium metal complex oxide, a positive electrode active material for a lithium secondary battery, a positive electrode for a lithium secondary battery, and a lithium secondary battery. BACKGROUND

[0002] In a lithium secondary battery, a positive electrode is fabricated using, for example, a positive electrode active material containing a lithium metal complex oxide.

[0003] Hitherto, various lithium metal complex oxides have been proposed in order to improve the performance of a lithium secondary battery.

[0004] PRIOR ART DOCUMENTS PATENT DOCUMENTS Patent Document 1: WO2019 / 069402A1 SUMMARY

[0005] PROBLEMS TO BE SOLVED BY THE INVENTION For a lithium secondary battery, it is required to improve the discharge capacity.

[0006] An object of the present application is to provide a lithium metal complex oxide, a positive electrode active material for a lithium secondary battery, a positive electrode for a lithium secondary battery, and a lithium secondary battery, which can improve the discharge capacity at a high rate.

[0007] MEANS FOR SOLVING THE PROBLEMS The present application has the following solutions.

[0008] [1] A lithium metal complex oxide, The aforementioned lithium metal complex oxide contains Li, Ni, and an element M, The aforementioned element M is at least one element selected from the group consisting of Co, Mn, Fe, Cu, Ti, Mg, Ca, Al, Zn, Sn, Zr, B, Si, Nb, W, Ta, Ba, S, and P, The aforementioned lithium metal complex oxide has fine pores, In a fine pore size distribution calculated from a nitrogen adsorption isotherm by the Barrett-Joyner-Halenda method with respect to the aforementioned fine pores, The maximum value dV1 of the proportion dVp / ddp with which the fine pore volume Vp of the aforementioned fine pores increases as the fine pore size dp of the aforementioned fine pores increases, in the range in which the proportion dap / ddp with which the fine pore surface area ap of the aforementioned fine pores increases as the fine pore size dp of the aforementioned fine pores increases satisfies the relationship "dap / ddp≤0.10", satisfies the relationship shown in the following (Formula A1), The maximum value dV2 of the aforementioned dVp / ddp in the range where the aforementioned dap / ddp satisfies the relationship "dap / ddp > 0.10" satisfies the relationship shown by the following (Formula A2), dV1≤1.00×10 -4 …… (Formula A1) dV2≥1.00×10 -4 …… (Formula A2).

[0009] [2] The lithium metal complex oxide according to [1], wherein, In the aforementioned pore size distribution, the pore volume V satisfies the relationship shown by the following (Formula B), 0.001 cm 3 / g≤V≤0.01 cm 3 / g …… (Formula B).

[0010] [3] The lithium metal complex oxide according to [1] or [2], wherein, In the aforementioned pore size distribution, the pore surface area Ap satisfies the relationship shown by the following (Formula C), 0.5 m 2 / g≤Ap≤2.0 m 2 / g …… (Formula C).

[0011] [4] The lithium metal complex oxide according to any one of [1] to [3], wherein, In the aforementioned pore size distribution, the average pore diameter Adp satisfies the relationship shown by the following (Formula D), 10 nm≤Adp≤40 nm …… (Formula D).

[0012] [5] The lithium metal complex oxide according to any one of [1] to [4], wherein, which is a lithium metal complex oxide represented by (Composition Formula I), In (Composition Formula I), M1 is at least one element selected from the group consisting of Mn, Al, and Co, M2 is at least one element selected from the group consisting of Fe, Cu, Ti, Mg, Ca, Zn, Sn, Zr, B, Si, Nb, W, Ta, Ba, S, and P, satisfies the relationships shown by the following (Formula la) to (Formula Id).

[0013] Li[Li α (Ni （1-x-y） M1 x M2 y ) 1-αO2... (Composition Formula I), -0.1 ≤ α ≤ 0.2... (Formula Ia), 0 ≤ x ≤ 0.5... (Formula Ib), 0 ≤ y ≤ 0.7... (Formula Ic), 0 < x + y < 1... (Formula Id).

[0014] [6] The lithium metal complex oxide according to any one of [1] to [5], wherein, The amount of substance of Co is 10 mol% or less relative to the total amount of substance of Ni and the aforementioned element M.

[0015] [7] The lithium metal complex oxide according to [5], wherein, In (Composition Formula I), the following (Formula Id_1) indicated by the following relation is satisfied, 0 < x + y ≤ 0.15... (Formula Id_1).

[0016] [8] The lithium metal complex oxide according to any one of [1] to [7], wherein, The metal site occupancy SR obtained by Rietveld analysis satisfies the following relation indicated by the following (Formula E), 1.0% ≤ SR ≤ 4.0%... (Formula E).

[0017] [9] The lithium metal complex oxide according to any one of [1] to [8], wherein, The average crystal grain size AK obtained by Rietveld analysis satisfies the following relation indicated by the following (Formula F), 80 nm ≤ AK ≤ 200 nm... (Formula F).

[0018]

[10] A positive electrode active material for a lithium secondary battery, which has the lithium metal complex oxide according to any one of [1] to [9].

[0019]

[11] A positive electrode for a lithium secondary battery, which has the positive electrode active material for a lithium secondary battery according to

[10] .

[0020]

[12] A lithium secondary battery, which has the positive electrode for a lithium secondary battery according to

[11] .

[0021] Effects of the Invention According to the present application, it is possible to provide a lithium metal complex oxide, a positive electrode active material for a lithium secondary battery, a positive electrode for a lithium secondary battery, and a lithium secondary battery, which can improve the discharge capacity at a high rate. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1Ais a graph showing an example of a proportion dap / ddp in which the pore surface area ap of the pores increases in accordance with an increase in the pore diameter dp of the pores in the embodiment.

[0023] Figure 1B is a graph showing an example of a proportion dVp / ddp in which the pore volume Vp of the pores increases in accordance with an increase in the pore diameter dp of the pores in the embodiment.

[0024] Figure 1C is a graph showing an example of the relationship between dap / ddp and dVp / ddp in the embodiment.

[0025] Figure 2 is a schematic view showing an example of a lithium secondary battery.

[0026] Figure 3 is a schematic view showing an example of an all-solid-state lithium secondary battery. DETAILED DESCRIPTION

[0027] Hereinafter, an example of an embodiment of the present application will be described.

[0028] In the present specification, a metal composite compound is represented by the abbreviation "MCC" (Metal Composite Compound). A lithium metal composite oxide is represented by the abbreviation "LiMO" (Lithium Metal composite Oxide). A cathode active material for lithium secondary batteries is represented by the abbreviation "CAM" (Cathode Active Material for lithium secondary batteries). Furthermore, "Ni", "Li" do not represent nickel metal, lithium metal, but represent nickel element, lithium element. The same applies to the expression of other elements such as Co, Mn. As for numerical ranges, for example, in the case where it is described as "5-15 μm", it means a range from 5 μm to 15 μm, and means a numerical range including 5 μm as a lower limit value and 15 μm as an upper limit value. Furthermore, the numerical ranges of each property, composition, and manufacturing conditions, etc. can be arbitrarily combined. A lithium secondary battery refers to a battery in which an electrolyte (non-aqueous electrolyte, solid electrolyte, etc.) is disposed between a positive electrode and a negative electrode, and charging and discharging are performed by moving lithium ions between the positive electrode and the negative electrode by means of the electrolyte.

[0029] [A] LiMO [A-1] Crystal structure In the present embodiment, LiMO is a substance used as a CAM. LiMO is preferably has a layered structure from the viewpoint of improving the discharge capacity at a high rate.

[0030] The crystal structure of LiMO is preferably hexagonal or monoclinic. The crystal structure of the hexagonal is attributed to one of the space groups selected from the group consisting of P3, P31, P32, R3, P-3, R-3, P312, P321, P3112, P3121, P3212, P3221, R32, P3m1, P31m, P3c1, P31c, R3m, R3c, P-31m, P-31c, P-3m1, P-3c1, R-3m, R-3c, P6, P61, P65, P62, P64, P63, P-6, P6 / m, P63 / m, P622, P6122, P6522, P6222, P6422, P6322, P6mm, P6cc, P63cm, P63mc, P-6m2, P-6c2, P-62m, P-62c, P6 / mmm, P6 / mcc, P63 / mcm, and P63 / mmc. Further, the crystal structure of the monoclinic is attributed to one of the space groups selected from the group consisting of P2, P21, C2, Pm, Pc, Cm, Cc, P2 / m, P21 / m, C2 / m, P2 / c, P21 / c, and C2 / c. Among the above, in order to obtain a lithium secondary battery having a high discharge capacity, the crystal structure of LiMO is further preferably hexagonal attributed to the space group R-3m or monoclinic attributed to C2 / m.

[0031] The crystal structure of LiMO can be confirmed by observation using a powder X-ray diffraction measuring device. The powder X-ray diffraction measurement can use an X-ray diffractometer such as Ultima IV manufactured by Rigaku Corporation.

[0032] [A-2] Composition The composition of LiMO contains at least Li, Ni, and an element M.

[0033] The element M is at least one element selected from the group consisting of Co, Mn, Fe, Cu, Ti, Mg, Ca, Al, Zn, Sn, Zr, B, Si, Nb, W, Ta, Ba, S, and P.

[0034] LiMO preferably contains an element M1 selected from at least one of Li, Ni, and Co, Mn, and Al.

[0035] The above LiMO is preferably represented by (Composition Formula I).

[0036] Li[Li α (Ni （1-x-y） M1 x M2 y ) 1-α ]O2 …… (Composition Formula I) In (Composition Formula I), M1 is at least one element selected from the group consisting of Mn, Al, and Co. M2 is at least one element selected from the group consisting of Fe, Cu, Ti, Mg, Ca, Zn, Sn, Zr, B, Si, Nb, W, Ta, Ba, S, and P.

[0037] In (Composition Formula I), a, x, y preferably satisfy the relationships shown in (Formula Ia) to (Formula Id) below.

[0038] -0.1 ≤ a ≤ 0.2 …… (Formula Ia) 0 ≤ x ≤ 0.5 …… (Formula Ib) 0 ≤ y ≤ 0.7 …… (Formula Ic) 0 < x + y < 1 …… (Formula Id) In (Composition Formula I), by the value of a satisfying the relationship shown in (Formula Ia), the internal resistance of the lithium secondary battery can be reduced, and the discharge capacity at a high rate can be increased. Further, in (Composition Formula I), a is more preferably -0.03 or greater, and further preferably -0.02 or greater. Furthermore, a is more preferably 0.1 or less, and further preferably 0.07 or less. As the range of a, more preferably -0.03 ≤ a ≤ 0.1, and further preferably -0.02 ≤ a ≤ 0.07.

[0039] In (Composition Formula I), by the value of x satisfying the relationship shown in (Formula Ib), the internal resistance of the lithium secondary battery can be reduced, the discharge capacity at a high rate can be increased, the life can be extended, and the rate characteristics can be improved. Further, in (Composition Formula I), x is more preferably 0.01 or greater, and further preferably 0.02 or greater. Furthermore, x is more preferably 0.4 or less, and further preferably 0.3 or less. As the range of x, more preferably 0.01 ≤ x ≤ 0.4, and further preferably 0.02 ≤ x ≤ 0.3.

[0040] In (Composition Formula I), by the value of y satisfying the relationship shown in (Formula Ic), the cycle retention rate of the lithium secondary battery can be improved. Further, in the case where LiMO contains M2, in (Composition Formula I), y is more preferably 0.0002 or greater, and further preferably 0.0005 or greater. Furthermore, y is more preferably 0.6 or less, and further preferably 0.5 or less. As the range of y, more preferably 0 ≤ y ≤ 0.6, further preferably 0.0002 ≤ y ≤ 0.6, and particularly preferably 0.0005 ≤ y ≤ 0.5.

[0041] In (Composition Formula I), by the total value of the value of x and the value of y (x+y) satisfying the relationship shown in (Formula Id), the initial capacity of the lithium secondary battery and the discharge capacity at a high rate can be improved. Further, in (Composition Formula I), (x+y) is more preferably less than 0.6, further preferably 0.3 or less, particularly preferably 0.15 or less. (x+y) is more preferably 0.01 or more. As the range of (x+y), for example, 0.01≤x+y<0.6, 0.01≤x+y≤0.3, 0.01≤x+y≤0.15 can be cited, and particularly by satisfying the relationship shown in (Formula Id_1) below, the discharge capacity at a high rate can be improved.

[0042] 0 < x+y ≤ 0.15 …… (Formula Id_1) M2 is preferably at least one element selected from the group consisting of Ti, Mg, Zr, B, Nb, and W.

[0043] In the above LiMO, the amount of substance of Co is preferably 10 mol% or less, more preferably 5 mol% or less, further preferably 3 mol% or less, particularly preferably 1 mol% or less, and can be 0, with respect to the total amount of substance of Ni and the element M. In the case of (Composition Formula I), the amount of substance of the aforementioned Co can be calculated using the amount of substance of Ni [Ni], the amount of substance of M1 [M1], the amount of substance of M2 [M2], and the amount of substance of Co [Co] by (Formula II) below. In the case where the amount of substance of the aforementioned Co is in the above range, since the operating voltage of the lithium secondary battery is less likely to rise, the electrolyte is less likely to be decomposed on the surface of LiMO, and thus the resistance can be reduced, and the discharge capacity of the lithium secondary battery at a high rate can be further improved.

[0044] 100·[Co] / ([Ni]+[M1]+[M2]) …… (Formula II) <Method for measuring composition> The composition of LiMO is measured, for example, using an ICP emission spectrometry device (Optima 7300 (manufactured by Perkin Elmer Corporation) or the like). Before measuring the composition, the sample is dissolved in an acid or a base according to the element to be measured.

[0045] [A-3] Fine pores of LiMO LiMO has fine pores. Further, LiMO is a powder. LiMO can be composed of secondary particles formed by aggregation of primary particles alone, or can be a mixture of primary particles and secondary particles. For example, LiMO can include a plurality of primary particles and secondary particles formed by aggregation of the plurality of primary particles.

[0046] The above "primary particle" is a particle in which no grain boundary exists in appearance when LiMO is observed at a field of view of 1000 to 30000 times using a microscope (scanning electron microscope, etc.). Then, the above "secondary particle" is an aggregate of the primary particle.

[0047] In the secondary particle constituting LiMO, fine pores are interposed between a plurality of primary particles.

[0048] As for the fine pores of LiMO, a fine pore diameter (fine pore diameter) dp, a fine pore surface area ap, and a fine pore volume Vp can be obtained using a fine pore diameter distribution calculated from a nitrogen adsorption isotherm by a Barrett-Joyner-Halenda method (BJH method). The ap affects a reaction field of a lithium secondary battery, and the Vp affects impregnation property (accessibility) of an electrolyte solution in the lithium secondary battery.

[0049] <Method for measuring fine pore volume ratio> The nitrogen adsorption isotherm is obtained by measuring a sample of 10 g of LiMO using a measurement device for an adsorption isotherm (for example, BELSORP-mini (manufactured by MicrotracBEL Corp.)) under liquid nitrogen (temperature: 77 K) after vacuum degassing treatment is performed on the sample using a vacuum heat treatment device (for example, BELSORP-vac II (manufactured by MicrotracBEL Corp.)). In the nitrogen adsorption isotherm, the nitrogen adsorption amount of nitrogen adsorbed by unit weight of LiMO is expressed by the volume of nitrogen at a standard state (STP; Standard Temperature and Pressure). By analyzing the nitrogen adsorption isotherm by the BJH method, a fine pore diameter distribution can be obtained. From the fine pore diameter distribution, the average fine pore diameter Adp, the fine pore volume V, and the fine pore surface area Ap described later are obtained. The BJH method is a method of analyzing based on a relationship formula (Kelvin formula) of the fine pore diameter at which capillary condensation occurs and the relative pressure of nitrogen gas, assuming that the shape of the fine pore is cylindrical, and is used for evaluation of fine pores (mesopores, etc.) in which the fine pore diameter dp is about 2 to 200 nm.

[0050] (Ratio dVp / ddp of increase in fine pore volume Vp) In the fine pore diameter distribution of LiMO obtained as described above, a ratio dap / ddp of increase in ap of the fine pore with respect to dp and a ratio dVp / ddp of increase in Vp of the fine pore with respect to dp satisfy a specific relationship, as described later.

[0051] Figure 1A is a graph showing an example of dap / ddp of the fine pore. In Figure 1A , the horizontal axis represents dp of the fine pore, and the vertical axis represents dap / ddp (change rate of ap with respect to dp) of the fine pore.

[0052] Figure 1B is a graph showing an example of dVp / ddp of the fine pores. In Figure 1B , the horizontal axis indicates dp of the fine pores, and the vertical axis indicates dVp / ddp (rate of change in Vp with respect to dp) of the fine pores.

[0053] Figure 1C is a graph showing an example of the relationship between dap / ddp and dVp / ddp. In Figure 1C , the horizontal axis indicates dap / ddp, and the vertical axis indicates dVp / ddp.

[0054] As shown in Figure 1C , the maximum value dV1 of dVp / ddp of the LiMO of the present embodiment in the range where the relationship of "dap / ddp≤0.10" is satisfied satisfies the relationship shown in the following (Formula Al). Also, the maximum value dV2 of dVp / ddp of the above-described LiMO in the range where the relationship of "dap / ddp>0.10" is satisfied satisfies the relationship shown in the following (Formula A2).

[0055] dV1≤1.00×10 -4 (Formula Al) dV2≥1.00×10 -4 (Formula A2) The range where the relationship of "dap / ddp≤0.10" is satisfied is a region where the increase ratio of the fine pore surface area with respect to the increase in the fine pore diameter is small, and is a region including fine pores having a small reaction field in the electrode reaction. The LiMO satisfying the above-described (Formula Al) indicates that fine pores having a small increase ratio of the fine pore volume with respect to the increase in the fine pore diameter, which are difficult to impregnate with the electrolyte, are formed in this region. That is, it can be considered that the LiMO satisfying the above-described (Formula Al) has a small number of fine pores as non-efficient structures in the electrode reaction.

[0056] The range where the relationship of "dap / ddp>0.10" is satisfied is a region where the increase ratio of the fine pore surface area with respect to the increase in the fine pore diameter is large, and is a region including fine pores having a large reaction field in the electrode reaction. The LiMO satisfying the above-described (Formula A2) indicates that fine pores having a large increase ratio of the fine pore volume with respect to the increase in the fine pore diameter, which are easy to impregnate with the electrolyte, are formed in this region. That is, it can be considered that the LiMO satisfying the above-described (Formula A2) has a sufficient number of fine pores as efficient structures in the electrode reaction.

[0057] Therefore, the LiMO satisfying the relationship shown in (Formula Al) and (Formula A2) can improve the discharge capacity at a high rate of the lithium secondary battery.

[0058] From the viewpoint of improving the discharge capacity at a high rate, dV1 is more preferably 0.90×10 -4 It is further preferable that dV1 be 0.80×10-4 Further, dV1 is more preferably 0.20 x 10 -4 Further, dV1 is more preferably 0.20 x 10 -4 Further, dV1 is more preferably 0.20 x 10 -4 Further, dV1 is more preferably 0.20 x 10 -4 ≤ dV1 ≤ 0.90 x 10 -4 Further, dV1 is more preferably 0.20 x 10 -4 ≤ dV1 ≤ 0.80 x 10 -4 Further, dV1 is more preferably 0.20 x 10 -4 ≤ dV1 ≤ 0.80 x 10 -4 .

[0059] From the viewpoint of improving the discharge capacity at a high rate, dV2 is more preferably 1.01 x 10 -4 Further, dV2 is more preferably 1.01 x 10 -4 Further, dV2 is more preferably 1.01 x 10 -4 Further, dV2 is more preferably 1.01 x 10 -4 Further, dV2 is more preferably 1.01 x 10 -4 Further, dV2 is more preferably 1.01 x 10 -4 ≤ dV2 ≤ 2.50 x 10 -4 Further, dV2 is more preferably 1.01 x 10 -4 ≤ dV2 ≤ 2.30 x 10 -4 ≤ dV2 ≤ 2.00 x 10 -4 ≤ dV2 ≤ 2.00 x 10 -4 .

[0060] (Pore Volume V) The pore volume V of LiMO preferably satisfies the relationship shown in the following (Formula B). V is the pore volume of pores having a pore diameter of 2 to 200 nm in the aforementioned pore size distribution.

[0061] 0.001 cm 3 / g ≤ V ≤ 0.01 cm 3 / g … (Formula B) LiMO satisfying Formula (B) has a sufficient pore volume, and there are pores in which the impregnation of electrolyte solution and the formation of a reaction field are balanced. Therefore, the above-described LiMO can further improve the discharge capacity of a lithium secondary battery at a high rate.

[0062] V is more preferably 0.009 cm 3 / g or less, and further preferably 0.008 cm 3 / g or less. Further, V is more preferably 0.002 cm 30.004 cm or more, further preferably 0.004 cm or more 3 0.002 cm or more, more preferably 0.002 cm or more 3 0.004 cm or more, further preferably 0.004 cm or more 3 0.004 cm or more, further preferably 0.004 cm or more 3 0.004 cm or more, further preferably 0.004 cm or more 3 0.004 cm or more, further preferably 0.004 cm or more 3 0.004 cm or more, further preferably 0.004 cm or more 3 0.004 cm or more, further preferably 0.004 cm or more

[0063] (Pore surface area Ap) The pore surface area Ap of LiMO preferably satisfies the relationship shown in the following (Formula C). Ap is the pore surface area of pores having a pore diameter of 2 to 200 nm in the aforementioned pore size distribution.

[0064] 0.5 m 2 0.7 m or more, further preferably 0.9 m or more 2 0.7 m or more, further preferably 0.9 m or more LiMO satisfying Formula (C) has a sufficient pore surface area, and a reaction field is easily formed. Therefore, the discharge capacity of the lithium secondary battery at a high rate can be further improved.

[0065] 0.7 m or more, further preferably 0.9 m or more 2 0.7 m or more, further preferably 0.9 m or more 2 0.7 m or more, further preferably 0.9 m or more 2 0.7 m or more, further preferably 0.9 m or more 2 0.7 m or more, further preferably 0.9 m or more 2 0.7 m or more, further preferably 0.9 m or more 2 0.7 m or more, further preferably 0.9 m or more 2 0.7 m or more, further preferably 0.9 m or more 2 0.7 m or more, further preferably 0.9 m or more

[0066] (Average pore diameter Adp) The average pore diameter Adp of LiMO preferably satisfies the relationship shown in the following (Formula D).

[0067] 10 nm or more, more preferably 10 nm or more LiMO satisfying Formula (D) has pores effective for electrode reactions present at an appropriate pore diameter. Therefore, the discharge capacity of the lithium secondary battery at a high rate can be further improved.

[0068] Adp is more preferably 35 nm or less, and further preferably 30 nm or less. In addition, Adp is more preferably 15 nm or more, and further preferably 20 nm or more. As a range of Adp, more preferably 15 nm ≤ Adp ≤ 35 nm, and further preferably 20 nm ≤ Adp ≤ 30 nm.

[0069] [A-4] Regarding Other Characteristics (SR of Metal Sites) The SR of the LiMO is preferably in a relationship indicated by the following (Formula E).

[0070] 1.0% ≤ SR ≤ 4.0% …… (Formula E) SR is a ratio at which Ni and the element M exist in the Li layer (Li site) of the LiMO constituting the layered structure. In a case where SR is below the above upper limit value, the diffusion resistance in the lithium secondary battery is less likely to increase, and the decrease in the discharge capacity at a high rate can be further suppressed. In a case where SR is above the above lower limit value, the volume change rate of the lithium secondary battery is less likely to increase, and breakage or the like is less likely to occur.

[0071] SR is more preferably 3.5% or less, and further preferably 3.0% or less. In addition, SR is more preferably 1.1% or more, and further preferably 1.2% or more. As a range of SR, more preferably 1.1% ≤ SR ≤ 3.5%, and further preferably 1.2% ≤ SR ≤ 3.0%.

[0072] (Average Crystal Grain Size AK) The AK of the LiMO is preferably in a relationship indicated by the following (Formula F).

[0073] 80 nm ≤ AK ≤ 200 nm …… (Formula F) In a case where AK is within the above range, the crystal of the LiMO moderately and sufficiently grows, and the increase in the resistance of the lithium secondary battery can be suppressed, and the discharge capacity at a high rate can be further improved.

[0074] AK is more preferably 170 nm or less, and further preferably 150 nm or less, and particularly preferably 130 nm or less. In addition, AK is more preferably 90 nm or more, and further preferably 100 nm or more, and particularly preferably 105 nm or more. As a range of AK, more preferably 90 nm ≤ AK ≤ 170 nm, and further preferably 100 nm ≤ AK ≤ 150 nm, and particularly preferably 105 nm ≤ AK ≤ 130 nm.

[0075] <Measurement Method of SR of Metal Sites and AK> SR and AK calculated the results using Riedbold analysis on powder X-ray diffraction patterns obtained from powder X-ray diffraction measurements. Riedbold analysis is a method for optimizing crystal structure parameters in a crystal structure model by comparing the measured powder X-ray diffraction pattern with a simulated pattern obtained from a crystal structure model, in order to minimize the difference between the two.

[0076] Powder X-ray diffraction measurements were performed using an X-ray diffraction apparatus. For example, the D8 Advance (manufactured by Bruker) can be used as the X-ray diffraction apparatus. Specifically, LiMO powder was filled onto a dedicated substrate, and measurements were performed using a CuKα-ray source at diffraction angles of 2θ = 10°–90° and a sampling width of 0.02° to obtain the powder X-ray diffraction pattern. The obtained powder X-ray diffraction pattern was then subjected to Ridbold analysis. The Ridbold analysis software used was TOPAS ver. 4.2 (manufactured by Bruker). At this point, a layered rock-salt type crystal structure (Li...) was used as the initial crystal structure model. 1-n Me n (Me) 1- n Li n O2 is used to optimize the metal site occupancy rate n at Li sites. Using the above method, SR and AK can be calculated.

[0077] [B]LiMO Manufacturing Method The method for manufacturing the aforementioned LiMO will be described.

[0078] In the manufacture of LiMO, a mixing process and a firing process are performed sequentially.

[0079] [B-1] Mixing process The mixing process prepares a mixture of MCC and lithium compounds as a precursor for LiMO.

[0080] [B-1-1]MCC MCC is a substance containing Ni and element M that constitute LiMO, such as a metal complex hydroxide, a metal complex oxide, or a mixture thereof.

[0081] Metal complex hydroxides used as MCCs are manufactured, for example, by known intermittent or continuous coprecipitation methods.

[0082] The following section provides a detailed explanation of the manufacturing method of a metal composite hydroxide containing Ni and element M.

[0083] Specifically, a nickel salt solution and a metal salt solution of element M are reacted by the continuous coprecipitation method described in JP-A-2002-201028. Thus, a metal composite hydroxide containing Ni and element M (Ni （1-a） M a (OH)2(0 < a < 1) is produced.

[0084] The nickel salt as the solute of the nickel salt solution is, for example, at least one of nickel sulfate, nickel nitrate, nickel chloride, and nickel acetate.

[0085] The metal salt of element M as the solute of the metal salt solution of element M is, for example, at least one of cobalt sulfate, cobalt nitrate, cobalt chloride, cobalt acetate, manganese sulfate, manganese nitrate, manganese chloride, manganese acetate, aluminum sulfate, aluminum nitrate, aluminum chloride, and aluminum acetate.

[0086] The nickel salt solution and the metal salt solution of element M are mixed in a proportion corresponding to the nickel salt and the metal salt of element M to (Ni （1-a） M a (OH)2). Also, water is used as the solvent of these solutions.

[0087] The manufacturing process of the metal composite hydroxide can use a complexing agent. In this case, the amount of the complexing agent is greater than 0 and 2 or less in terms of the molar ratio to the total of the moles of, for example, the nickel salt and the metal salt of element M.

[0088] The complexing agent is a material that can form a complex with nickel ions and ions of element M in an aqueous solution. The complexing agent can be exemplified by, for example, at least one of an ammonium ion donor (ammonium hydroxide, ammonium sulfate, ammonium chloride, ammonium carbonate, or ammonium fluoride, etc.), hydrazine, ethylenediaminetetraacetic acid, nitrilotriacetic acid, uracil diacetic acid, and glycine.

[0089] Before the pH of the mixed solution containing the nickel salt solution, the metal salt solution of element M, and the optional complexing agent changes from alkaline to neutral, an aqueous solution of an alkali metal hydroxide is added to the mixed solution. The alkali metal hydroxide is, for example, sodium hydroxide or potassium hydroxide.

[0090] Note that the pH of the mixed solution is measured when the temperature of the mixed solution is 40°C. In the case where the temperature of the mixed solution sampled from the reaction tank is not 40°C, the pH is measured after the mixed solution is warmed or cooled to 40°C.

[0091] The temperature of the reaction tank is controlled, for example, in the range of 20-80°C, preferably in the range of 30-70°C.

[0092] Also, the pH of the reaction tank is controlled, for example, in the range of pH 9-13 during the reaction.

[0093] Then, neutralization is performed while stirring the reaction precipitate formed in the reaction tank. The time for which the reaction precipitate is neutralized is, for example, in the range of 1 to 20 hours.

[0094] As the reaction tank used in the continuous coprecipitation method, a reaction tank of the type in which overflow occurs can be used in order to separate the reaction precipitate formed.

[0095] In the case where a metal composite hydroxide is manufactured by the batch coprecipitation method, a reaction tank not provided with an overflow pipe, a device provided with a mechanism for concentrating the reaction precipitate that has overflowed in a concentration tank connected to the overflow pipe and recycling it to the reaction tank, or the like can be used.

[0096] Here, various gases (for example, an inert gas such as nitrogen, argon, or carbon dioxide, an oxidizing gas such as air or oxygen, or a mixed gas thereof) are supplied to the reaction tank.

[0097] After the reaction, the reaction precipitate obtained is separated. Separation is performed, for example, using a method in which a slurry containing the reaction precipitate is dewatered by centrifugal separation, suction filtration, or the like. In addition, the reaction precipitate can be washed before separation.

[0098] Then, for the separated reaction precipitate, drying and sieving are performed as necessary, whereby a metal composite hydroxide can be obtained.

[0099] Washing of the reaction precipitate is preferably performed using water or an alkaline washing liquid. Washing of the reaction precipitate is preferably performed using an alkaline washing liquid, and particularly preferably using an aqueous sodium hydroxide solution. In addition, washing can be performed using a washing liquid containing sulfur. The washing liquid containing sulfur is, for example, an aqueous potassium or sodium sulfate solution or the like.

[0100] Note that, in the above example, a metal composite hydroxide was manufactured as MCC, but a metal composite oxide can also be prepared.

[0101] A metal composite oxide is manufactured, for example, by oxidizing a metal composite hydroxide (oxidation step). The oxidation step can be performed multiple times as necessary. In the case where multiple oxidation steps are performed, the oxidation temperature refers to the temperature of the step in which oxidation is performed at the highest temperature among the multiple oxidation steps.

[0102] The oxidation temperature is preferably in the range of 400 to 700°C, and more preferably in the range of 450 to 680°C. Note that the oxidation temperature refers to the set temperature of the device used for oxidation.

[0103] The time for which the oxidation temperature is maintained in the oxidation step is preferably in the range of 0.1 to 20 hours, more preferably in the range of 0.5 to 10 hours. The temperature increase rate to the above oxidation temperature is, for example, in the range of 50 to 400°C / hour. Further, the oxidation step is performed, for example, under an atmosphere containing air, oxygen, nitrogen, argon, or a mixed gas thereof.

[0104] The inside of the apparatus for oxidation can be an oxygen-containing atmosphere moderately containing oxygen. The oxygen-containing atmosphere can be a mixed gas atmosphere of an inert gas and oxygen, or a state in which an oxidizing agent is present in an inert gas atmosphere.

[0105] The oxygen-containing gas atmosphere can be an atmosphere in which oxygen atoms exist as long as the oxygen atoms are sufficient to oxidize the transition metal.

[0106] In the case where the oxygen-containing gas atmosphere is a mixed gas atmosphere containing an active gas and oxygen, the control of the atmosphere in the apparatus can be performed by a method of introducing oxygen into the apparatus, or a method of bubbling oxygen into the mixed solution.

[0107] The oxidizing agent is a peroxide such as hydrogen peroxide, a peroxide salt such as permanganate, perchlorate, hypochlorite, nitric acid, halogen, or ozone.

[0108] [B-1-2] Lithium compound The lithium compound used in the production of LiMO is, for example, a powder of at least one of lithium carbonate, lithium nitrate, lithium acetate, lithium hydroxide, lithium hydroxide monohydrate, lithium oxide, lithium chloride, and lithium fluoride. Among these, at least one of lithium hydroxide, lithium hydroxide monohydrate, and lithium carbonate is preferably used as the lithium compound.

[0109] The lithium compound is mixed with the MCC in consideration of the composition ratio of the final target product, to obtain a mixture of the lithium compound and the MCC. The amount of Li contained in the lithium compound is preferably 0.90 to 1.10, more preferably 0.95 to 1.10, and further preferably 0.98 to 1.07, relative to the total amount (molar ratio) of the elements other than oxygen atoms (Ni and the element M) contained in the MCC.

[0110] [B-2] Firing step The firing step produces a fired product by firing the mixture prepared in the mixing step.

[0111] The firing step preferably sequentially performs primary firing and secondary firing.

[0112] The primary firing is performed, for example, under the firing conditions shown below.

[0113] • Primary firing temperature (holding temperature): 500 to 900°C • Primary firing time (holding time): 1 to 50 hours The primary firing temperature is more preferably 550 to 850°C, and further preferably 600 to 700°C. If the primary firing temperature is higher than the lower limit of the aforementioned range, LiMO having a strong crystal structure can be obtained. In addition, if the primary firing temperature is lower than the upper limit of the aforementioned range, the evaporation of lithium ions from the particle surface of LiMO can be reduced. Note that the primary firing temperature or the secondary firing temperature described later refers to the set temperature of the firing device. In the case where multiple primary firings or secondary firings are performed, the primary firing temperature or the secondary firing temperature refers to the temperature of the stage at the highest temperature in the multiple primary firing stages or secondary firing stages.

[0114] The primary firing is performed under an atmosphere containing air, oxygen, nitrogen, argon, or a mixed gas thereof, or the like, depending on the composition. The primary firing is preferably performed under an oxygen atmosphere.

[0115] The secondary firing is performed, for example, under the firing conditions shown below.

[0116] • Secondary firing temperature (heating rate): 80°C / hour or more • Secondary firing temperature (holding temperature): 600 to 900°C • Secondary firing time (holding time): 1 to 50 hours The secondary firing is performed under a state where oxygen is supplied. Specifically, the secondary firing is performed in a manner that the BET specific surface area FS1 of the powder of the primary fired product obtained in the primary firing, the oxygen flow rate FS2 at the time of the secondary firing (at the time of heating and at the time of holding), and the sheath filling amount FS3 at the time of the secondary firing satisfy the relationship shown in the following formula (X). The secondary firing is performed by placing the powder of the primary fired product in the internal space of a sheath that is a container in the shape of a rectangular parallelepiped. The sheath filling amount FS3 corresponds to the ratio of the area FS31 of the bottom surface of the internal space of the sheath to the layer height FS32 of the powder of the primary fired product placed in the internal space of the sheath (i.e., FS3 = FS32 / FS31).

[0117] 1.50 ≤ (FS2 / FS1) FS3 ≤ 5.20 …… (Formula X) (FS2 / FS1) FS3 is more preferably 1.7 or more, further preferably 1.9 or more, and particularly preferably 2.3 or more. In addition, (FS2 / FS1) FS3 is more preferably 5.15 or less, further preferably 5.10 or less, and particularly preferably 5.05 or less. If (FS2 / FS1) FS3 is within the aforementioned range, then LiMO having a pore structure satisfying the relationships shown by (Formula A1) and (Formula A2) can be efficiently produced with a high degree of sintering affected by the amount of oxygen with respect to the BET specific surface area of the primary sinter and uniformity of sintering affected by the ratio of the layer height to the bottom surface of the interior space of the sheath being appropriately controlled. Furthermore, Adp, V, Ap, SR, and AK of LiMO can be adjusted to the aforementioned ranges.

[0118] (BET specific surface area measurement method) The BET specific surface area of the primary sinter is measured using nitrogen as the adsorption gas. The BET specific surface area (unit: m 2 / g) is measured using a BET specific surface area meter (for example, Macsorb (manufactured by Mountech Co., Ltd.)) after 1 g of the primary sinter is dried for 30 minutes under a nitrogen atmosphere at a temperature of 105°C, for example.

[0119] FS2 is preferably 0.1 to 10 L / minute. Furthermore, FS3 is preferably 200 to 2000 cm 3 .

[0120] Note that the primary sintering and the secondary sintering are performed using a sintering device such as a continuous stationary sintering furnace, a flow-type sintering furnace, and the like. The continuous stationary sintering furnace is a tunnel furnace or a roller hearth kiln, for example. The flow-type sintering furnace is a rotary kiln, for example.

[0121] The primary sintering or the secondary sintering can be performed in the presence of an inactive flux. The inactive flux can be added to the extent that the initial capacity of a battery using LiMO is not impaired and can remain in the sinter. As the inactive flux, a substance described in WO2019 / 177032A1, for example, can be used.

[0122] The secondary sintering temperature is set to a temperature higher than the primary sintering temperature. The secondary sintering temperature is more preferably 650 to 850°C, and further preferably 700 to 820°C. If the secondary sintering temperature is the lower limit value of the aforementioned range or more, then LiMO having a strong crystal structure can be obtained. Furthermore, excessive sintering can be suppressed.

[0123] The secondary sintering temperature is set to a temperature higher than the primary sintering temperature. The secondary sintering temperature is more preferably 650 to 850°C, and further preferably 700 to 820°C. If the secondary sintering temperature is the lower limit value of the aforementioned range or more, then LiMO having a strong crystal structure can be obtained. Furthermore, excessive sintering can be suppressed.

[0124] The secondary sintering time is more preferably 2 to 20 hours. If the secondary sintering time is the upper limit value of the aforementioned range or less, then lithium ion evaporation can be suppressed, and battery performance can be suppressed from decreasing. If the secondary sintering time is the lower limit value of the aforementioned range or more, then the development of crystals can be promoted, and battery performance can be suppressed from decreasing.

[0125] The crushing can be appropriately performed after the firing step.

[0126] The fired product obtained in the firing step can be appropriately subjected to a post-treatment step and a drying step, and can be further subjected to crushing and sieving.

[0127] [B-3] Post-treatment step The post-treatment step subjects the fired product obtained in the firing step to post-treatment. As the post-treatment, for example, a treatment of washing using a washing liquid such as water, ion-exchanged water, an alkaline aqueous solution, a sulfate aqueous solution, or the like to remove impurities from the fired product can be cited. At this time, the slurry concentration is preferably 40 mass% or more. As the washing time, for example, 5 to 20 minutes can be cited. Note that the slurry concentration (mass%) is the ratio of the mass of the fired product (WS) to the total mass of the fired product (WS) and the washing liquid (WL) (i.e., 100 (WS + WL).

[0128] In the washing step, as the method of bringing the washing liquid into contact with the fired product, a method of putting the fired product into each washing liquid and stirring, a method of spraying each washing liquid as spray water to the fired product, or a method of putting the fired product into a washing liquid and stirring, then separating the fired product from each washing liquid, and then spraying each washing liquid as spray water to the separated fired product can be cited.

[0129] The temperature of the washing liquid used in the washing is preferably 15°C or lower, more preferably 10°C or lower, and further preferably 8°C or lower. By controlling the temperature of the washing liquid in the above range, the excessive elution of lithium ions from the crystal structure of the fired product into the washing liquid at the time of washing can be suppressed.

[0130] [B-4] Drying step The drying step dries the fired product subjected to the post-treatment in the post-treatment step.

[0131] The drying step dries the fired product at a temperature of, for example, 100 to 400°C. Note that the drying is performed, for example, by reduced pressure drying, vacuum drying, air blowing, heating, or a combination thereof.

[0132] By the above steps, LiMO can be produced.

[0133] [C] Battery evaluation In the battery evaluation of LiMO, after the positive electrode is produced from LiMO, a lithium secondary battery is produced using the produced positive electrode. Then, as the battery evaluation, the "3C discharge capacity" is measured with respect to the produced lithium secondary battery.

[0134] [C-1] Production of positive electrode for lithium secondary battery First, a paste-like positive electrode mixture is prepared. The positive electrode mixture is prepared by kneading a mixture of LiMO and a conductive material and a binder. Here, acetylene black is used as the conductive material, and PVdF is used as the binder. Then, the materials are mixed in the following proportions. In preparing the positive electrode mixture, N-methyl-2-pyrrolidone is used as the organic solvent.

[0135] • LiMO: 92 parts by mass • Conductive material: 5 parts by mass • Binder: 3 parts by mass Then, the paste-like positive electrode mixture prepared as described above is applied to a current collector (aluminum foil having a thickness of 40 μm). Then, the current collector to which the positive electrode mixture is applied is subjected to vacuum drying in an atmosphere at a temperature of 150°C for 8 hours, thereby completing the positive electrode for lithium secondary battery. Here, the electrode area of the positive electrode for lithium secondary battery is made 1.65 cm 2 .

[0136] [C-2] Preparation of lithium secondary battery In preparing the lithium secondary battery, first, the positive electrode prepared as described above is placed on the upper surface of the lower case of a coin-type battery CR2032 part (manufactured by Hojun Corporation). In the setting of the lower case, the aluminum foil of the positive electrode for lithium secondary battery is made to face downward. Then, a separator is set on the upper surface of the lower case on which the positive electrode is set. As the separator, a polyethylene-made porous film having a thickness of 25 μm is used.

[0137] Next, 300 μl of electrolyte is injected into the inside of the above part. Here, as the electrolyte, a solution obtained by adding 1% by volume of vinylene carbonate to a mixed solution obtained by mixing each substance in the following proportions and further dissolving LiPF6 is used. The electrolyte is prepared so that the concentration of LiPF6 reaches 1 mol / 1.

[0138] • Vinylene carbonate: 30 parts by volume • Dimethyl carbonate: 35 parts by volume • Ethyl methyl carbonate: 35 parts by volume Next, a negative electrode is set on the upper side of the separator. Here, metallic lithium is used as the negative electrode. Then, the setting of the upper case is performed with a gasket interposed, and the upper case is riveted using a riveter. Thus, the lithium secondary battery is prepared.

[0139] [C-3] Measurement of "3C discharge capacity" After the lithium secondary battery prepared in the above is left to stand at room temperature for 12 hours so that the electrolyte is sufficiently impregnated into the separator and the positive electrode active material layer, the "3C discharge capacity" is measured under the following conditions.

[0140] • Processing temperature: 25°C • Charge maximum voltage 4.3 V, charge current 1 CA, constant current constant voltage charge • Discharge minimum voltage 2.5 V, discharge current 3 CA, constant current discharge [D] Lithium secondary battery An example of a lithium secondary battery using LiMO as a CAM, and a lithium secondary battery having the same will be described. Hereinafter, the lithium secondary battery will be sometimes referred to as a positive electrode.

[0141] An example of a lithium secondary battery preferred when using LiMO as a CAM has a positive electrode and a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte disposed between the positive electrode and the negative electrode.

[0142] Figure 2 is a schematic view showing an example of a lithium secondary battery. For example, a cylindrical lithium secondary battery 10 is manufactured as follows.

[0143] First, as shown in a partial enlarged view of Figure 2 a pair of separators 1 in a band shape, a positive electrode 2 having a positive electrode lead 21 at one end in a band shape, and a negative electrode 3 having a negative electrode lead 31 provided at one end in a band shape are prepared. Then, a laminate in which the separators 1, the positive electrode 2, the separators 1, and the negative electrode 3 are stacked in this order is wound, whereby an electrode group 4 is produced.

[0144] As an example, the positive electrode 2 has a positive electrode active material layer 2a containing LiMO and a positive electrode current collector 2b on which the positive electrode active material layer 2a is formed on one surface. Such a positive electrode 2 can be manufactured by first preparing a positive electrode mixture containing LiMO, a conductive material, and a binder, and forming the positive electrode active material layer 2a on one surface of the positive electrode current collector 2b by loading the positive electrode mixture thereon.

[0145] As an example, the negative electrode 3 can be exemplified by an electrode in which a negative electrode mixture containing a negative electrode active material is loaded on a negative electrode current collector, and an electrode formed of a negative electrode active material alone, and can be manufactured in the same manner as the positive electrode 2.

[0146] Next, after the electrode group 4 and an insulator (not shown) are housed in a battery can 5, the bottom of the battery can 5 is sealed. Then, an electrolyte 6 is caused to be impregnated in the electrode group 4 in the battery can 5, whereby the electrolyte is interposed between the positive electrode 2 and the negative electrode 3 (not shown). Then, the upper portion of the battery can 5 is sealed with a top insulator 7 and a sealing body 8. Thus, the lithium secondary battery 10 is completed.

[0147] As the shape of the electrode group 4, for example, a columnar shape in which the cross-sectional shape when the electrode group 4 is cut in the vertical direction with respect to the axis of winding is a circle, an ellipse, a rectangle, or a rectangular shape with rounded corners can be cited.

[0148] Further, as the shape of the lithium secondary battery having such an electrode group 4, a shape prescribed in the standards of the International Electrotechnical Commission (IEC), that is, IEC60086 or JIS C 8500 can be adopted. For example, a cylindrical shape or a square shape or the like can be cited.

[0149] Further, the lithium secondary battery is not limited to the above-described wound type configuration, and can be a laminated type configuration in which a stacked structure of a positive electrode, a separator, a negative electrode, and a separator is repeatedly overlapped. As the lithium secondary battery of the laminated type, a so-called coin-type battery, a button-type battery, or a paper-type (or sheet-type) battery can be cited.

[0150] As the positive electrode, the separator, the negative electrode, and the electrolyte that constitute the lithium secondary battery, the configuration, the material, and the manufacturing method described in paragraphs

[0113] to

[0140] of WO2022 / 113904A1 can be used, for example.

[0151] [E] All-solid-state lithium secondary battery The LiMO of the present embodiment can be used as a CAM of an all-solid-state lithium secondary battery.

[0152] Figure 3 is a schematic view showing an example of an all-solid-state lithium secondary battery.

[0153] As shown in Figure 3 , the all-solid-state lithium secondary battery 1000 includes a laminate 100 having a positive electrode 110, a negative electrode 120, and a solid electrolyte layer 130, and a housing 200 that accommodates the laminate 100. The all-solid-state lithium secondary battery 1000 can be a bipolar structure in which the LiMO and the negative electrode active material are disposed on both sides of a current collector. As a specific example of the bipolar structure, for example, the structure described in JP-A-2004-95400 can be cited.

[0154] The positive electrode 110 has a positive electrode active material layer 111 and a positive electrode current collector 112. The positive electrode active material layer 111 contains the LiCAM and the solid electrolyte described above. Further, the positive electrode active material layer 111 can contain a conductive material and a binder.

[0155] The negative electrode 120 has a negative electrode active material layer 121 and a negative electrode current collector 122. The negative electrode active material layer 121 contains a negative electrode active material. Further, the negative electrode active material layer 121 can contain a solid electrolyte and a conductive material.

[0156] The laminate 100 can have an external terminal 113 connected to the positive electrode current collector 112, and an external terminal 123 connected to the negative electrode current collector 122. In addition to this, the all-solid-state lithium secondary battery 1000 can also have a separator between the positive electrode 110 and the negative electrode 120.

[0157] The all-solid-state lithium secondary battery 1000 also has an unillustrated insulator (not illustrated) that insulates the laminate 100 and the outer case 200, and an unillustrated encapsulant that encapsulates the opening portion 200a of the outer case 200.

[0158] The outer case 200 is a container obtained by molding a metal material having high corrosion resistance such as aluminum, stainless steel, or nickel-plated steel. In addition, the outer case 200 can also be a container obtained by processing a laminated film on which corrosion-resistant processing has been performed on at least one face into a bag shape.

[0159] As the shape of the all-solid-state lithium secondary battery 1000, for example, a coin type, a button type, a paper type (or a sheet type), a cylindrical type, a square type, or a laminated type (a bag type) can be cited.

[0160] The all-solid-state lithium secondary battery 1000 is, for example, in a form having one laminate 100, but is not limited thereto. The all-solid-state lithium secondary battery 1000 can also be configured so that the laminate 100 is a unit cell and a plurality of unit cells (laminate 100) are enclosed inside the outer case 200.

[0161] As for the all-solid-state lithium secondary battery, for example, the configuration, materials, and manufacturing method described in paragraphs

[0151] to

[0181] of WO2022 / 113904A1 can be used.

[0162] Example Hereinafter, the examples and comparative examples will be described using Table 1. In Table 1, (Example 1) to (Example 3) correspond to examples, and (Example C1) and (Example C2) correspond to comparative examples.

[0163] [1] Sample Production The steps for producing the sample of LiMO of each example will be described in order. Note that the BET specific surface area of the primary sinter of each example was measured according to the method described in the above (Method for measuring BET specific surface area).

[0164] (Example 1) First, after adding water to a reaction tank equipped with a stirrer and an overflow pipe, an aqueous sodium hydroxide solution was added, and the liquid temperature was maintained at 70°C (the temperature of the reaction tank).

[0165] A mixed raw material solution 1 was prepared by mixing a nickel sulfate aqueous solution, a manganese sulfate aqueous solution, and an aluminum sulfate aqueous solution in such a manner that [Ni]:[Mn]:[Al] reached the values shown in Table 1 (93:3.5:3.5 in Example 1).

[0166] While the mixed raw material solution 1 was being stirred, an ammonium sulfate aqueous solution as a complexing agent was continuously added to the reaction tank while nitrogen gas was being supplied. Then, an aqueous sodium hydroxide solution was added dropwise as appropriate until the pH of the mixed solution in the reaction tank reached 11.4 (measurement temperature: 40°C), thereby obtaining a reaction precipitate 1.

[0167] The reaction precipitate 1 was washed with a 5 mass% aqueous sodium hydroxide solution. In the washing of the reaction precipitate 1, 20 times the amount of the aqueous sodium hydroxide solution was used relative to the mass of the reaction precipitate 1. After the washed reaction precipitate 1 was dewatered using a centrifugal separator, it was washed with water, and then further dewatered, thereby separating the reaction precipitate 1. The separated reaction precipitate 1 was dried at 105°C for 20 hours, thereby obtaining a metal composite hydroxide 1 containing Ni, Mn, and Al.

[0168] The metal composite hydroxide 1 was oxidized at 650°C for 5 hours in an air atmosphere, thereby obtaining MCC1 as a metal composite oxide.

[0169] Next, a powder of lithium hydroxide monohydrate as a lithium compound was mixed with a powder of MCC1, thereby obtaining a mixture 1. Here, the mixture 1 was obtained by mixing the lithium hydroxide monohydrate so that the amount of Li contained in the lithium hydroxide monohydrate relative to the total amount of Ni, Mn, and Al contained in the MCC1 (molar ratio) reached 1.05.

[0170] The mixture 1 was subjected to a first firing at 650°C for 5 hours in an oxygen atmosphere, thereby obtaining a first fired product 1.

[0171] Next, the powder of the first fired product 1 was charged into the inner space of the sheath. At this time, the sheath filling amount FS3 was the value shown in Table 1.

[0172] Then, the first fired product 1 was subjected to a second firing at 750°C for 5 hours in an oxygen atmosphere at a temperature increase rate of 300°C / hour. The second firing was performed in a state in which oxygen was being supplied. At this time, the oxygen flow rate FS2 during the second firing (during temperature increase and during holding) was 3.0 L / minute.

[0173] At this time, the value obtained by dividing the above oxygen flow rate FS2 by the BET specific surface area FS1 of the first fired product 1 was multiplied by the value obtained by dividing the sheath filling amount FS3 by the BET specific surface area FS1 of the first fired product 1 ((FS2 / FS1) FS3) was the value shown in Table 1.

[0174] The resultant calcined product 1 was mixed with pure water (liquid temperature 5°C), whereby a slurry was prepared. The slurry was prepared so as to contain 50 mass% of the calcined product. The slurry was stirred for 20 minutes. Then, the calcined product 1 was dried under a nitrogen atmosphere at 210°C for 10 hours.

[0175] Thus, samples of LiM01 having the compositions (a, x, y) shown in Table 1 were obtained.

[0176] (Example 2) A nickel sulfate aqueous solution, a manganese sulfate aqueous solution, and an aluminum sulfate aqueous solution were added and mixed so that [Ni]:[Mn]:[Al] would attain the values shown in Table 1, and a sodium hydroxide aqueous solution was added dropwise in a timely manner so that the pH of the mixed solution in the reaction tank would attain 11.0 (measuring temperature: 40°C), ( (FS2 / FS1) A secondary calcination was performed under the conditions shown in Table 1, and samples were prepared in the same manner as in (Example 1) except for this. Thus, samples of LiM02 having the compositions (a, x, y) shown in Table 1 were obtained.

[0177] (Example 3) A nickel sulfate aqueous solution, a manganese sulfate aqueous solution, and an aluminum sulfate aqueous solution were added and mixed so that [Ni]:[Mn]:[Al] would attain the values shown in Table 1, and a sodium hydroxide aqueous solution was added dropwise in a timely manner so that the pH of the mixed solution in the reaction tank would attain 11.2 (measuring temperature: 40°C), ( (FS2 / FS1) A secondary calcination was performed under the conditions shown in Table 1, and samples were prepared in the same manner as in (Example 1) except for this. Thus, samples of LiM03 having the compositions (a, x, y) shown in Table 1 were obtained.

[0178] (Example C1) A sodium hydroxide aqueous solution was added dropwise in a timely manner so that the pH of the mixed solution in the reaction tank would attain 12.2 (measuring temperature: 40°C), ( (FS2 / FS1) A secondary calcination was performed under the conditions shown in Table 1, and samples were prepared in the same manner as in (Example 1) except for this. Thus, samples of LiM04 having the compositions (a, x, y) shown in Table 1 were obtained.

[0179] (Example C2) ( (FS2 / FS1) A secondary calcination was performed under the conditions shown in Table 1, and samples were prepared in the same manner as in (Example 2) except for this. Thus, samples of LiM05 having the compositions (a, x, y) shown in Table 1 were obtained.

[0180] [2] Characteristics of Samples Each property of the LiMO sample produced for each example was obtained as described above. The results thereof are shown in Table 1.

[0181] [2-1] Composition of LiMO The composition of LiMO was measured according to the method described in the above <Measurement method of composition>. In addition, the amount of substance of Co with respect to the total amount of substance of Ni and the element M was calculated using the above (Formula II).

[0182] [2-2] Pore property of LiMO As the pore property of LiMO, dV1, dV2, V, Ap, and Adp were obtained according to the method described in the above <Measurement method of pore volume ratio> as shown in Table 1.

[0183] [2-2] Other properties of LiMO As the other properties of LiMO of each example, SR and AK were obtained according to the method described in the above <Measurement method of metal site occupancy and average crystal grain size> as shown in Table 1.

[0184] [3] Battery evaluation As described above, the battery evaluation was performed for the LiMO sample produced in each example as shown in Table 1. The battery evaluation was performed according to the method described in the above "[C] Battery evaluation".

[0185] [4] Summary The results of each example are described.

[0186] [4-1] Regarding (Example 1) to (Example 3) In (Example 1) to (Example 3), the composition of LiMO satisfies the relationships shown in (Formula Ia), (Formula Ib), (Formula Ic), (Formula Id), and (Formula Id_1) as shown in Table 1.

[0187] In addition, LiMO in (Example 1) to (Example 3) satisfies the relationships shown in (Formula A1) and (Formula A2). Furthermore, LiMO in (Example 1) to (Example 3) satisfies the relationships shown in (Formula B), (Formula C), (Formula D), (Formula E), and (Formula F).

[0188] Thus, the lithium secondary batteries of (Example 1) to (Example 3) had a 3C discharge capacity of 150 mAh / g or more as shown in Table 1, and a preferable result was obtained.

[0189] [4-2] Regarding the results of (Example C1) and (Example C2) The composition of LiMO of (Example C1) and (Example C2) satisfies the relationships shown in (Formula Ia), (Formula Ib), (Formula Ic), (Formula Id), and (Formula Id_1) described above as shown in the table. In addition, the LiMO of (Example C1) and (Example C2) satisfies the relationships shown in (Formula B), (Formula C), (Formula D), and (Formula F).

[0190] However, the LiMO of (Example C1) does not satisfy the relationship shown in (Formula Al). The LiMO of (Example C2) does not satisfy the relationship shown in (Formula A2).

[0191] Therefore, the lithium secondary batteries of (Example C1) and (Example C2) have a 3C discharge capacity of less than 150 mAh / g as shown in Table 1.

[0192] Industrial applicability According to the present application, it is possible to provide LiMO, a CAM, a positive electrode for a lithium secondary battery, and a lithium secondary battery, which can improve the discharge capacity at a high rate.

[0193] Explanation of symbols 1…separator, 2…positive electrode, 2a…positive electrode active material layer, 2b…positive electrode current collector, 3…negative electrode, 4…electrode group, 5…battery can, 6…electrolyte solution, 7…top insulator, 8…sealing body, 10…lithium secondary battery, 21…positive electrode lead, 31…negative electrode lead, 100…laminated body, 110…positive electrode, 111…positive electrode active material layer, 112…positive electrode current collector, 113…external terminal, 120…negative electrode, 121…negative electrode active material layer, 122…negative electrode current collector, 123…external terminal, 130…solid electrolyte layer, 200…housing body, 200a…opening, 1000…all-solid-state lithium secondary battery

Claims

1. A lithium metal complex oxide, the lithium metal complex oxide contains Li, Ni, and an element M, the element M is at least one element selected from the group consisting of Co, Mn, Fe, Cu, Ti, Mg, Ca, Al, Zn, Sn, Zr, B, Si, Nb, W, Ta, Ba, S, and P, the lithium metal complex oxide has fine pores, in a pore size distribution calculated for the fine pores from a nitrogen adsorption isotherm by the Barrett-Joyner-Halenda method, a maximum value dV1 of a proportion dVp / ddp at which a pore volume Vp of the fine pores increases with an increase in a pore size dp of the fine pores in a range in which the proportion dap / ddp at which a pore surface area ap of the fine pores increases with an increase in the pore size dp of the fine pores satisfies a relationship of "dap / ddp≤0.10" satisfies a relationship represented by the following (Formula A1), a maximum value dV2 of the dVp / ddp in a range in which the dap / ddp satisfies a relationship of "dap / ddp>0.10" satisfies a relationship represented by the following (Formula A2): dV1≤ 1.00 x 10 -4 …… (Equation A1), dV2≥ 1.00 x 10 -4 …… (Equation A2).

2. The lithium metal complex oxide according to claim 1, wherein In the pore size distribution, the pore volume V satisfies the following relation shown in (Formula B) : 0.001 cm 3 / g ≤ V ≤ 0.01 cm 3 / g …… (Formula B).

3. The lithium metal complex oxide according to claim 1 or 2, wherein In the pore size distribution, the pore surface area Ap satisfies the following relation shown in (Formula C): 0.5 m 2 / g ≤ Ap ≤ 2.0 m 2 / g …… (Formula C).

4. The lithium metal complex oxide according to claim 1 or 2, wherein in the pore size distribution, an average pore size Adp satisfies a relationship represented by the following (Formula D): 10 nm≤Adp≤40 nm …… (Formula D).

5. The lithium metal complex oxide according to claim 1 or 2, which is a lithium metal complex oxide represented by (Composition Formula I), in (Composition Formula I), M1 is at least one element selected from the group consisting of Mn, Al, and Co, M2 is at least one element selected from the group consisting of Fe, Cu, Ti, Mg, Ca, Zn, Sn, Zr, B, Si, Nb, W, Ta, Ba, S, and P, satisfies a relationship represented by the following (Formula la) to (Formula Id): Li[Li α (Ni （1-x-y） M1 x M2 y ) 1-α ]O2 …… (Composition Formula I), -0.1≤α≤0.2 …… (Formula la), 0≤x≤0.5 …… (Formula lb), 0≤y≤0.7 …… (Formula lc), 0 6. The lithium metal complex oxide according to claim 1 or 2, wherein the amount of substance of Co is 10 mol% or less relative to the total amount of substance of Ni and the element M.

7. The lithium metal complex oxide according to claim 5, wherein in (Composition Formula I), a relationship represented by the following (Formula Id_1) is satisfied: 0 8. The lithium metal complex oxide according to claim 1 or 2, wherein a metal site occupancy SR obtained from Rieder analysis satisfies a relationship represented by the following (Formula E): 1.0%≤SR≤4.0% …… (Formula E).

9. The lithium metal complex oxide according to claim 1 or 2, wherein The average crystal grain size AK obtained by the Rietveld analysis satisfies the following relationship shown in (Formula F): 80 nm ≤ AK ≤ 200 nm … (Formula F).

10. A positive electrode active material for a lithium secondary battery, which has the lithium metal complex oxide according to claim 1 or 2.

11. A positive electrode for a lithium secondary battery, which has the positive electrode active material for a lithium secondary battery according to claim 10.

12. A lithium secondary battery, which has the positive electrode for a lithium secondary battery according to claim 11.

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