Positive electrode active material composition, positive electrode plate, battery and electric device

Abstract

The invention provides a positive electrode active material composition, a positive electrode plate, a battery and a power utilization device, the positive electrode active material composition comprises a first positive electrode active material and a second positive electrode active material with a crystal form different from that of the first positive electrode active material, and the second positive electrode active material comprises a phosphate material, the positive electrode active material composition satisfies the following conditions: Dv10 (1) / Dv50 (2) > 1, Dv50 (1) / Dv50 (2) > = 1.4, and-2.0 < = 1-[(rho2 * W2) / (rho1 * W1)] < = 0.98. The parameters are defined in the description.

Description

Positive electrode active material composition, positive electrode sheet, battery and electrical device Technical Field

[0001] The present application relates to a positive electrode active material composition, a positive electrode plate, a battery and an electrical device. Background Art

[0002] In recent years, batteries have been widely used in energy storage systems such as hydropower, thermal, wind, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and other fields. As battery applications continue to expand, the demand for battery energy density and service life is increasing.

[0003] Summary of the Invention

[0004] The present application provides a positive electrode active material composition, a positive electrode plate, a battery and an electrical device, which can enable the battery to have high energy density, low cost and good service life.

[0005] The first aspect of the present application provides a positive electrode active material composition, wherein the positive electrode active material composition comprises a first positive electrode active material and a second positive electrode active material having a crystal form different from that of the first positive electrode active material, wherein the second positive electrode active material comprises a phosphate material, and the volume distribution particle size Dv10 of the first positive electrode active material is (1) The volume distribution particle size Dv50 of the second positive electrode active material (2) Meet Dv10 (1) / Dv50 (2) >1, the volume distribution particle size Dv50 of the first positive electrode active material (1) The volume distribution particle size Dv50 of the second positive electrode active material (2) Meet Dv50 (1) / Dv50 (2) ≥1.4, the true density of the first positive electrode active material is recorded as ρ1, and the true density of the second positive electrode active material is recorded as ρ2, both in g / cm 3 Based on the total mass of the positive electrode active material composition, the mass proportion of the first positive electrode active material is recorded as W1, and the mass proportion of the second positive electrode active material is recorded as W2, then the positive electrode active material composition satisfies -2.0≤1-[(ρ2×W2) / (ρ1×W1)]≤0.98.

[0006] By adjusting the volume distribution particle size, true density and mass ratio of the first positive electrode active material and the second positive electrode active material in the positive electrode active material composition, the battery using the positive electrode active material composition of the present application can have high energy density, low cost and good service life.

[0007] In any embodiment, 1 < Dv10 (1) / Dv50 (2) ≤16.5, optionally, 1.07≤Dv10 (1) / Dv50 (2) ≤11.3. This allows the first positive electrode active material and the second positive electrode active material to be stacked more densely, further improving the actual stacking density of the positive electrode active material composition, improving the compaction density and compaction density efficiency of the positive electrode sheet, and thus enabling the battery using the positive electrode active material composition of the present application to have a higher energy density and / or a longer service life.

[0008] In any embodiment, 1.4 < Dv50 (1) / Dv50 (2) ≤30.0, optionally, 2.0≤Dv50 (1) / Dv50 (2) ≤23.8. This allows the first positive electrode active material and the second positive electrode active material to be stacked more densely, further improving the actual stacking density of the positive electrode active material composition, improving the compaction density and compaction density efficiency of the positive electrode sheet, and thus enabling the battery using the positive electrode active material composition of the present application to have a higher energy density and / or a longer service life.

[0009] In any embodiment, -0.78≤1-[(ρ2×W2) / (ρ1×W1)]≤0.96, optionally, -0.14≤1-[(ρ2×W2) / (ρ1×W1)]≤0.92, and more optionally, 0.67≤1-[(ρ2×W2) / (ρ1×W1)]≤0.92. This allows the first positive electrode active material and the second positive electrode active material to be stacked more densely, further improving the actual stacking density of the positive electrode active material composition, improving the compaction density and compaction density efficiency of the positive electrode sheet, and thus enabling the battery using the positive electrode active material composition of the present application to have a higher energy density and a longer service life.

[0010] In any embodiment, W2 = ρ2 / [(β × ρ1) + ρ2], 0.3 ≤ β ≤ 30, optionally, 0.5 ≤ β ≤ 6.9, and more optionally, 1.8 ≤ β ≤ 6.9. By setting β within the above range, the positive electrode active material composition can have a higher actual packing density, thereby further improving the compaction density and compaction density efficiency of the positive electrode sheet, thereby enabling the battery using the positive electrode active material composition of the present application to have a higher energy density and / or a longer service life.

[0011] In any embodiment, the particle size distribution curve of the positive electrode active material composition has at least two volume distribution peaks, the peak with the smallest volume distribution particle size is recorded as peak I, and the other peaks other than peak I are recorded as peak II. The volume distribution particle size corresponding to the maximum peak intensity of peak I is between 0.3 μm and 2.1 μm, and the volume distribution particle size corresponding to the maximum peak intensity of peak II is between 3 μm and 15 μm. The ratio of the integral area of ​​peak I to the total integral area of ​​peak II is (0.010-2.5):1, which can be optionally (0.011-1.3):1. By making the ratio of the integral area of ​​peak I to the total integral area of ​​peak II in the particle size distribution curve of the positive electrode active material composition within the above range, the contribution of the first positive electrode active material to the compaction density of the positive electrode sheet can be improved, and the second positive electrode active material can be better filled in the gaps between the particles of the first positive electrode active material, thereby making the first positive electrode active material and the second positive electrode active material more densely stacked, thereby improving the actual stacking density of the positive electrode active material composition, improving the compaction density and compaction density efficiency of the positive electrode sheet, and further making the battery using the positive electrode active material composition of the present application have a higher energy density and / or a longer service life.

[0012] In any embodiment, the particle size distribution curve of the second positive electrode active material has at least two volume distribution peaks, the peak with the smallest volume distribution particle size is designated as peak III, and the peaks other than peak III are designated as peak IV. The volume distribution particle size corresponding to the maximum peak intensity of peak III is between 0.3 μm and 2.1 μm, and the volume distribution particle size corresponding to the maximum peak intensity of peak IV is between 2.1 μm and 10 μm. The ratio of the integrated area of ​​peak III to the total integrated area of ​​peak IV is (0.5-20):1. By ensuring that the ratio of the integrated area of ​​peak III to the total integrated area of ​​peak IV in the particle size distribution curve of the second positive electrode active material is within the above range, the second positive electrode active material can be more effectively filled in the gaps between the particles of the first positive electrode active material, thereby enabling the first and second positive electrode active materials to be more densely packed, thereby increasing the actual packing density of the positive electrode active material composition, improving the compaction density and compaction density efficiency of the positive electrode sheet, and further enabling batteries using the positive electrode active material composition of the present application to have higher energy density and / or longer service life.

[0013] In any embodiment, the ratio of the major axis length to the minor axis length of the first positive electrode active material is 1-2, and can be optionally 1-1.4.

[0014] In any embodiment, the ratio of the major axis length to the minor axis length of the second positive electrode active material is 1-2, and can be optionally 1-1.4.

[0015] In any embodiment, the volume distribution particle size Dv10 of the first positive electrode active material is (1)0.3-8μm, optional 1.6-6.6μm.

[0016] In any embodiment, the volume distribution particle size Dv50 of the first positive electrode active material is (1) 1.5-15μm, optional 3-12μm.

[0017] In any embodiment, the volume distribution particle size Dv50 of the second positive electrode active material is (2) 0.25-3μm, optional 0.4-2μm.

[0018] When the volume distribution particle size of the first positive electrode active material and / or the second positive electrode active material is within the above range, the battery can have a higher energy density, and can also reduce side reactions, thereby extending the battery life.

[0019] In any embodiment, the true density ρ1 of the first positive electrode active material is 4.40-5.15 g / cm 3 , optional 4.60-5.10g / cm 3 .

[0020] In any embodiment, the true density ρ2 of the second positive electrode active material is 3.20-3.65 g / cm 3 , optional 3.30-3.60g / cm 3 .

[0021] In any embodiment, based on the total mass of the positive electrode active material composition, the mass proportion W1 of the first positive electrode active material is 30%-98%, and optionally 70%-90%, thereby enabling the battery to better balance high energy density and long service life.

[0022] In any embodiment, based on the total mass of the positive electrode active material composition, the mass proportion W2 of the second positive electrode active material is 2%-70%, and optionally 10%-30%. This enables the battery to better achieve both high energy density and long service life.

[0023] In any embodiment, the second positive electrode active material includes a compound represented by formula (I), Li a A x Mn 1-y B y P 1-z C z O 4-n D n (I)

[0024] A includes one or more elements selected from Group IA, Group IIA, Group IIIA, Group IIB, Group VB and Group VIB; B includes one or more elements selected from Group IA, Group IIA, Group IIIA, Group IVA, Group VA, Group IIB, Group IVB, Group VB, Group VIB and Group VIII; C includes one or more elements selected from Group IIIA, Group IVA, Group VA and Group VIA; D includes one or more elements selected from Group VIA and Group VIIA; a is selected from the range of 0.85 to 1.15; x is selected from the range of 0 to 0.1; y is selected from the range of 0.001 to 1; z is selected from the range of 0 to 0.5; n is selected from the range of 0 to 0.5.

[0025] In any embodiment, y is selected from the range of 0.001 to 0.999. By doping the compound LiMnPO4 with a specific element in a specific amount at the Mn position and optionally at the Li position, P position, and / or O position, improved rate performance can be achieved while reducing the dissolution of Mn and the doping element at the Mn position, thereby achieving improved cycling performance and / or high-temperature stability, and increasing the specific capacity and compacted density of the material.

[0026] In any embodiment, A comprises one or more elements selected from Rb, Cs, Be, Ca, Sr, Ba, Ga, In, Cd, V, Ta, Cr, Zn, Al, Na, K, Mg, Nb, Mo, and W, and may optionally comprise one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo, and W; and / or B comprises one or more elements selected from Rb, Cs, Be, Ca, Sr, Ba, In, Pb, Bi, Cd, Hf, Ta, Cr, Ru, Rh, Pd, Os, Ir, Pt, Zn, ... The present invention may further comprise one or more elements selected from the group consisting of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb and Ge, and may optionally comprise one or more elements selected from the group consisting of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb and Ge; and / or, C comprises one or more elements selected from the group consisting of B (boron), S, Si and N; and / or, D comprises one or more elements selected from the group consisting of S, F, Cl and Br.

[0027] In any embodiment, A includes any one element selected from Zn, Al, Na, K, Mg, Nb, Mo and W, and optionally includes any one element selected from Mg and Nb; and / or, B includes one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge, and optionally includes at least two elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge, and more optionally includes at least two elements selected from Fe, Ti, V, Ni, Co and Mg, and further optionally includes at least two elements selected from Fe, Ti, V, Co and Mg, and further optionally includes Fe and one or more elements selected from Ti, V, Co and Mg; and / or, C includes any one element selected from B (boron), S, Si and N, and optionally is S; and / or, D includes any one element selected from S, F, Cl and Br, and optionally is F.

[0028] By selecting the Li-position doping element within the above range, the lattice change rate during the delithiation process can be further reduced, thereby further improving the rate performance of the battery. By selecting the Mn-position doping element within the above range, the electronic conductivity can be further improved and the lattice change rate can be further reduced, thereby improving the rate performance and gram capacity of the battery. By selecting the P-position doping element within the above range, the rate performance of the battery can be further improved. By selecting the O-position doping element within the above range, the side reactions at the interface can be further reduced, thereby improving the high-temperature performance of the battery.

[0029] In any embodiment, a is selected from the range of 0.9 to 1.1, optionally from the range of 0.97 to 1.01; and / or, x is selected from the range of 0.001 to 0.005; and / or, y is selected from the range of 0.001 to 0.5, optionally from the range of 0.01 to 0.5, optionally from the range of 0.25 to 0.5; and / or, z is selected from the range of 0.001 to 0.5, optionally from the range of 0.001 to 0.1, more optionally from the range of 0.001 to 0.005; and / or, n is selected from the range of 0 to 0.1, optionally from the range of 0.001 to 0.005.

[0030] By selecting the value of y within the above range, the gram capacity and rate performance of the second positive electrode active material can be further improved. By selecting the value of x within the above range, the kinetic performance of the second positive electrode active material can be further improved. By selecting the value of z within the above range, the rate performance of the battery can be further improved. By selecting the value of n within the above range, the high-temperature performance of the battery can be further improved.

[0031] In any embodiment, x is 0, z is selected from the range of 0.001 to 0.5, and n is selected from the range of 0.001 to 0.1; or, x is selected from the range of 0.001 to 0.1, z is 0, and n is selected from the range of 0.001 to 0.1; or, x is selected from the range of 0.001 to 0.1, z is selected from the range of 0.001 to 0.5, and n is 0; or, x is 0, z is 0, and n is selected from the range of 0.001 to 0.1; or, x is 0, z is 0, and n is selected from the range of 0.001 to 0.5, and n is 0; or, x is selected from the range of 0.001 to 0.1, z is selected from the range of 0.001 to 0.5, and n is 0.

[0032] Thus, by doping a specific element in a specific amount at the Mn position of the compound LiMnPO4 and optionally at the Li position, P position and / or O position, especially doping a specific element in a specific amount at the Mn position and P position of LiMnPO4 or at the Li position, Mn position, P position and O position of LiMnPO4, the rate performance can be improved, the dissolution of Mn and the doping element at the Mn position can be reduced, the cycle performance and / or high temperature stability can be improved, and the gram capacity and compaction density of the second positive electrode active material can be increased.

[0033] In any embodiment, y:z is selected from the range of 0.002 to 999, and can be selected from the range of 0.025 to 999 or the range of 0.002 to 500, and can be further selected from the range of 0.2 to 600. In this way, defects of the second positive electrode active material can be reduced, and the integrity of the framework structure of the second positive electrode active material can be improved, thereby effectively improving the structural stability of the second positive electrode active material and further improving the cycle stability of the battery.

[0034] In any embodiment, z:n is selected from the range of 0.002 to 500, optionally from the range of 0.2 to 100, and more optionally from the range of 0.2 to 50. In this way, defects of the second positive electrode active material can be further reduced, the integrity of the framework structure of the second positive electrode active material can be further improved, the structural stability of the second positive electrode active material can be effectively improved, and the cycle stability of the battery can be improved.

[0035] In any embodiment, A includes one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo and W; B includes one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge; C includes one or more elements selected from B (boron), S, Si and N; D includes one or more elements selected from S, F, Cl and Br; a is selected from the range of 0.9 to 1.1, x is selected from the range of 0.001 to 0.1, y is selected from the range of 0.001 to 0.5, z is selected from the range of 0.001 to 0.1, and n is selected from the range of 0.001 to 0.1.

[0036] By doping specific elements in specific amounts at the Li, Mn, P, and O positions of the compound LiMnPO4 simultaneously, improved rate performance can be obtained, while reducing the dissolution of Mn and the doping elements at the Mn position, thereby obtaining improved cycle performance and / or high-temperature stability, and the gram capacity and compaction density of the second positive electrode active material can also be improved.

[0037] In any embodiment, B includes one or more elements selected from Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb and Ge, and can be optionally selected from one or more elements selected from Zn, Fe, Ti, V, Ni, Co and Mg; C includes one or more elements selected from B (boron), Si, N and S; a is selected from the range of 0.9 to 1.1, x is 0, y is selected from the range of 0.001 to 0.5, z is selected from the range of 0.001 to 0.1, and n is 0.

[0038] By doping specific elements at specific amounts at both the Mn and P sites of the LiMnPO4 compound, rate performance can be improved, the dissolution of Mn and the doping elements at the Mn site can be reduced, the cycle performance and / or high-temperature stability can be improved, and the gram capacity and compaction density of the second positive electrode active material can be increased.

[0039] In any embodiment, (1-y):y is in the range of 0.1-999, optionally in the range of 0.1-10 or in the range of 0.67-999, more optionally in the range of 1 to 10, further optionally in the range of 1 to 4, and further optionally in the range of 1.5 to 3; and / or, a:x is in the range of 1 to 1200, optionally in the range of 9 to 1100, and more optionally in the range of 190 to 998. As a result, the energy density and cycle performance of the second positive electrode active material can be further improved.

[0040] In any embodiment, z:(1-z) is 1:9 to 1:999, and can be 1:499 to 1:249. Thus, the energy density and cycle performance of the second positive electrode active material can be further improved.

[0041] In any embodiment, the second positive electrode active material includes a core and a shell covering the core, the core includes the compound represented by formula (I); the shell includes one or more coating layers; each coating layer has ionic conductivity and / or electronic conductivity.

[0042] By arranging a coating layer with ionic conductivity and / or electronic conductivity on the surface of the inner core, a second positive electrode active material with a core-shell structure is provided. Applying the second positive electrode active material to the battery can improve the high-temperature cycle performance, cycle stability and high-temperature storage performance of the battery.

[0043] In any embodiment, the one or more coating layers each independently include one or more selected from the group consisting of pyrophosphate, phosphate, carbon, doped carbon, oxide, boride, and polymer.

[0044] The above materials can be used to obtain a coating layer with ionic conductivity and / or electronic conductivity, thereby improving the high-temperature cycle performance, cycle stability and high-temperature storage performance of the battery.

[0045] In any embodiment, the shell comprises a coating layer; optionally, the coating layer comprises one or more selected from pyrophosphate, phosphate, carbon, doped carbon, oxide, boride and polymer.

[0046] In any embodiment, the shell includes a first coating layer coating the core and a second coating layer coating the first coating layer; optionally, the first coating layer and the second coating layer each independently include one or more selected from pyrophosphate, phosphate, carbon, doped carbon, oxide, boride and polymer; more optionally, the first coating layer includes one or more selected from pyrophosphate, phosphate, oxide and boride, and the second coating layer includes one or more selected from carbon and doped carbon.

[0047] The use of a first coating layer of a specific material and a second coating layer of a specific material can further improve rate performance and further reduce the dissolution of Mn and Mn-doping elements, thereby improving the cycle performance and / or high-temperature stability of the battery.

[0048] In any embodiment, the shell includes a first coating layer coating the core, a second coating layer coating the first coating layer, and a third coating layer coating the second coating layer; optionally, the first coating layer, the second coating layer and the third coating layer each independently include one or more selected from pyrophosphate, phosphate, carbon, doped carbon, oxide, boride and polymer; more optionally, the first coating layer includes pyrophosphate, the second coating layer includes one or more selected from phosphate, oxide and boride, and the third coating layer includes one or more selected from carbon and doped carbon.

[0049] The use of a first coating layer of a specific material, a second coating layer of a specific material, and a third coating layer of a specific material further improves the rate performance, further reduces the dissolution of Mn and Mn-doping elements, thereby improving the cycle performance and / or high-temperature stability of the battery, and further increases the gram capacity and compaction density of the second positive electrode active material.

[0050] In any embodiment, the pyrophosphate is M b (P2O7) c ; and / or, the phosphate is X m (PO4) q and / or, the doping element in the doped carbon includes one or more elements selected from Group IIIA, Group VA, Group VIA and Group VIIA; and / or, the oxide is M' d O e ; and / or, the boride is Z v B w ; and / or, the polymer includes one or more elements selected from polysaccharides and their derivatives, polysiloxanes; M, X and Z each independently include one or more elements selected from Group IA, Group IIA, Group IIIA, Group IB, Group IIB, Group IVB, Group VB, Group VIIB and Group VIII; b is selected from the range of 1 to 4; c is selected from the range of 1 to 6; m is selected from the range of 1 to 2; q is selected from the range of 1 to 4; M′ includes one or more elements selected from alkali metals, alkaline earth metals, transition metals, Group IIIA elements, Group IVA elements, lanthanides and Sb; d is greater than 0 and less than or equal to 2; e is greater than 0 and less than or equal to 5; v is selected from the range of 1 to 7; w is selected from the range of 1 to 2.

[0051] By using the above materials as the coating layer, the dissolution of Mn and Mn-doping elements can be further reduced, the gram capacity and compaction density of the second positive electrode active material can be further increased, and the battery's rate performance, high-temperature cycle performance and high-temperature storage performance can be further improved.

[0052] In any embodiment, M, X and Z each independently include one or more elements selected from Li, Fe, Ni, Mg, Co, Cu, Zn, Ti, Ag, Zr, Nb, Mn and Al; and / or, the doping element in the doped carbon includes one or more elements selected from nitrogen, phosphorus, sulfur, boron and fluorine; and / or, M' includes one or more elements selected from Li, Be, B, Na, Mg, Al, Si, P, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, One or more elements selected from Ga, Ge, As, Se, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, W, La and Ce, optionally including one or more elements selected from Mg, Al, Si, Zn, Zr and Sn; and / or, the polysiloxane is selected from one or more of linear polysiloxanes and cyclic polysiloxanes; and / or, the polysaccharide is selected from one or more of plant polysaccharides and marine polysaccharides.

[0053] By using the above-mentioned specific material as the coating layer, the dissolution of Mn and Mn-doping elements can be further reduced, and the high-temperature cycle performance and high-temperature storage performance of the battery can be further improved.

[0054] In any embodiment, the second positive electrode active material includes a core and a shell covering the core, wherein the core includes Li a Mn 1-y B y P 1-z C z O4, a is selected from the range of 0.9 to 1.1, y is selected from the range of 0.001 to 0.5, z is selected from the range of 0.001 to 0.1, B includes one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge, and C includes one or more elements selected from B (boron), S, Si and N; the shell includes a first coating layer coating the core and a second coating layer coating the first coating layer, the first coating layer includes pyrophosphate MP2O7 and phosphate XPO4, M and X each independently include one or more elements selected from Li, Fe, Ni, Mg, Co, Cu, Zn, Ti, Ag, Zr, Nb and Al; the second coating layer contains carbon.

[0055] By doping lithium manganese phosphate with specific elements and coating its surface, the dissolution of Mn during the lithium insertion and extraction process can be effectively reduced, while promoting the migration of lithium ions, thereby improving the battery's rate performance, cycle performance and high-temperature performance.

[0056] In any embodiment, the second positive electrode active material includes a core and a shell covering the core, wherein the core includes Lia Mn 1-y B y P 1-z C z O4, a is selected from the range of 0.9 to 1.1, y is selected from the range of 0.001 to 0.5, z is selected from the range of 0.001 to 0.1, B includes one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge, C includes one or more elements selected from B (boron), S, Si and N; the shell includes a first coating layer covering the core, a second coating layer covering the first coating layer and a third coating layer covering the second coating layer, the first coating layer includes pyrophosphate Li f QP2O7 and / or Q g (P2O7) h , 0≤f≤2, 1≤g≤4, 1≤h≤6, the pyrophosphate Li f QP2O7 and / or Q g (P2O7) h wherein Q independently comprises one or more elements selected from Fe, Ni, Mg, Co, Cu, Zn, Ti, Ag, Zr, Nb and Al; the second coating layer comprises crystalline phosphate XPO4, and X comprises one or more elements selected from Li, Fe, Ni, Mg, Co, Cu, Zn, Ti, Ag, Zr, Nb and Al; and the third coating layer comprises carbon.

[0057] Therefore, the second positive electrode active material can improve the specific capacity and cycle performance of the battery.

[0058] In any embodiment, the one or more coating layers in the shell that are furthest from the core each independently comprise one or more selected from polysiloxanes, polysaccharides, and polysaccharide derivatives. This improves coating uniformity and effectively blocks interfacial side reactions caused by high voltage, thereby enhancing the high-temperature cycling and storage performance of the second positive electrode active material. Furthermore, the coating layer has good ionic conductivity, which helps increase the specific capacity of the second positive electrode active material while reducing battery heat generation.

[0059] In any embodiment, the polysiloxane comprises a structural unit represented by formula (i),

[0060] R1 and R2 are independently selected from H, -COOH, -OH, -SH, -CN, -SCN, amino, phosphate, carboxylate, amide, aldehyde, sulfonyl, polyether segment, C1-C20 aliphatic, C1-C20 halogenated aliphatic, C1-C20 heteroaliphatic, C1-C20 halogenated heteroaliphatic, C6-C20 aromatic, C6-C20 halogenated aromatic, C2-C20 heteroaromatic and C2-C20 halogenated heteroaromatic; optionally, R1 and R2 are independently selected from H, amino, phosphate, polyether segment, C1-C8 alkyl, C1-C8 halogenated alkyl, C1-C8 heteroalkyl, C1-C8 halogenated heteroalkyl, C2-C8 alkenyl and C2-C8 halogenated alkenyl.

[0061] In any embodiment, the polysiloxane further comprises an end-capping group, wherein the end-capping group comprises one or more of the following functional groups: polyether, C1-C8 alkyl, C1-C8 haloalkyl, C1-C8 heteroalkyl, C1-C8 haloheteroalkyl, C2-C8 alkenyl, C2-C8 haloalkenyl, C6-C20 aromatic hydrocarbon, C1-C8 alkoxy, C2-C8 epoxy, hydroxyl, C1-C8 hydroxyalkyl, amino, C1-C8 aminoalkyl, carboxyl, C1-C8 carboxylalkyl.

[0062] In any embodiment, the polysiloxane comprises a polysiloxane selected from polydimethylsiloxane, polydiethylsiloxane, polymethylethylsiloxane, polymethylvinylsiloxane, polyphenylmethylsiloxane, polymethylhydrogensiloxane, carboxyl functionalized polysiloxane, epoxy-terminated polysiloxane, methoxy-terminated polydimethylsiloxane, hydroxypropyl-terminated polydimethylsiloxane, polymethylchloropropylsiloxane, hydroxy-terminated polydimethylsiloxane, polymethyltrifluoropropylsiloxane, perfluorooctylmethylpolysiloxane, aminoethylaminopropyl polydimethylsiloxane, terminal polyether polydimethylsiloxane, side chain aminopropyl polysiloxane. , aminopropyl-terminated polydimethylsiloxane, side chain phosphate grafted polydimethylsiloxane, side chain polyether grafted polydimethylsiloxane, 1,3,5,7-octamethylcyclotetrasiloxane, 1,3,5,7-tetrahydro-1,3,5,7-tetramethylcyclotetrasiloxane, cyclopentapolydimethylsiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, cyclic polymethylvinylsiloxane, hexadecylcyclooctasiloxane, tetradecamethylcycloheptasiloxane, and one or more of cyclic polydimethylsiloxane.

[0063] In any embodiment, the number average molecular weight of the polysiloxane, the polysaccharide and the polysaccharide derivative is independently below 300,000, optionally 10,000 to 200,000, more optionally 20,000 to 120,000, further optionally 400 to 80,000.

[0064] In any embodiment, the mass percentage of the polar functional groups in the polysiloxane is α, 0≤α<50%, optionally, 5%≤α≤30%.

[0065] In any embodiment, the substituents attached to the sugar units in the polysaccharide and the polysaccharide derivatives each independently include one or more of the group consisting of the following functional groups: -OH, -COOH and its salts, -R-OH, -SO3H and its salts, -R-OH, -R-SO3H and its salts, sulfate, alkoxy, R represents an alkylene group, optionally representing a C1 to C5 alkylene group; optionally, the substituents attached to the sugar units in the polysaccharide and the polysaccharide derivatives each independently include one or more of the group consisting of the following functional groups: -OH, -COOH, -COOLi, -COONa, -COOK, -SO3H, -SO3Li, -SO3Na, -SO3K, -CH2-SO3H, -CH2-SO3Li, -CH2-SO3Na, -CH2-SO3K, methoxy, ethoxy.

[0066] In any embodiment, the polysaccharide comprises one or more selected from pectin, carboxymethyl starch, hydroxypropyl starch, dextrin, cellulose ether, carboxymethyl chitosan, hydroxyethyl cellulose, carboxymethyl cellulose, carboxypropyl methyl cellulose, guar gum, sesbania gum, gum arabic, lithium alginate, sodium alginate, potassium alginate, fucoidan, agar, carrageenan, carrageenan, xanthan gum and fenugreek gum.

[0067] In any embodiment, the weight percentage of the substituents attached to the sugar units in the polysaccharide and the polysaccharide derivative is independently 20% to 85%, optionally 30% to 78%.

[0068] In any embodiment, the lattice mismatch between the core material and the shell material is less than 10%, thereby ensuring good contact between the core and the shell (or coating layer) to prevent the shell (or coating layer) from falling off.

[0069] In any embodiment, based on the total weight of the second positive active material, the manganese content is in the range of 10 weight %-35 weight %, optionally in the range of 13.3 weight %-33.2 weight %, more optionally in the range of 15 weight %-30 weight %, and further optionally in the range of 17 weight %-20 weight %; and / or, the phosphorus content is in the range of 12 weight %-25 weight %, optionally in the range of 15 weight %-20 weight %, and more optionally in the range of 16.8 weight %-19.5 weight %; and / or, the weight ratio of manganese to phosphorus is in the range of 0.71-1.85, optionally in the range of 0.90-1.25, and more optionally in the range of 0.95-1.20.

[0070] Limiting the manganese content within the above range can further improve the stability and density of the second positive electrode active material, thereby improving the battery's cycling, storage, and compaction performance; and can maintain a higher voltage platform, thereby improving the battery's energy density.

[0071] Limiting the phosphorus content within the above range can effectively reduce the influence of small polaron conductivity on the conductivity of the second positive electrode active material, further improve the stability of the lattice structure, and thus enhance the overall stability of the second positive electrode active material.

[0072] Limiting the weight ratio of manganese to phosphorus within the above range can further reduce manganese dissolution, improve the stability and gram capacity of the second positive electrode active material, and improve the cycle performance and storage performance of the battery; it can also reduce impurities, enable the second positive electrode active material to maintain a higher discharge voltage platform, and enable the battery to have a high energy density.

[0073] In any embodiment, the surface of the second positive electrode active material is coated with one or more of carbon and doped carbon; optionally, the surface of the second positive electrode active material is coated with carbon, thereby improving the conductivity of the second positive electrode active material.

[0074] In any embodiment, the doping element in the doped carbon includes one or more elements selected from nitrogen, phosphorus, sulfur, boron and fluorine, so as to facilitate control of the properties of the doped carbon layer.

[0075] In any embodiment, the coating amount of the shell is 0.1 wt% to 6 wt% based on the weight of the core. The coating amount of the coating layer is preferably within the above range, which can fully coat the core and further improve the kinetic performance of the battery without sacrificing the gram capacity of the second positive electrode active material.

[0076] In any embodiment, the coating amount of the first coating layer is greater than 0 and less than or equal to 7 weight%, optionally greater than 0 and less than or equal to 6 weight%, more optionally greater than 0 and less than or equal to 5.5 weight% or 4-5.6 weight%, further optionally greater than 0 and less than or equal to 2 weight%, based on the weight of the core; and / or, the coating amount of the second coating layer is greater than 0 and less than or equal to 6 weight%, optionally greater than 0 and less than or equal to 5.5 weight%, more optionally 2-4 weight% or 3-5 weight%, based on the weight of the core; and / or, the coating amount of the third coating layer is greater than 0 and less than or equal to 6 weight%, optionally greater than 0 and less than or equal to 5.5 weight%, more optionally greater than 0 and less than or equal to 2 weight%, based on the weight of the core.

[0077] In any embodiment, the shell further includes a fourth coating layer coating the third coating layer and a fifth coating layer coating the fourth coating layer; the coating amounts of the fourth coating layer and the fifth coating layer are each independently 0.01 wt % to 10 wt %, optionally 0.05 wt % to 10 wt %, more optionally 0.1 wt % to 5 wt %, and further 0.1 wt % to 2 wt %, based on the weight of the core.

[0078] The coating amount of each coating layer is preferably within the above range, so that the core can be fully coated and the kinetic performance of the battery can be further improved without sacrificing the gram capacity of the second positive electrode active material.

[0079] In any embodiment, the shell is located on 40% to 90% of the surface of the core, optionally 60% to 80% of the surface.

[0080] This allows the core to be fully coated, thereby improving the battery's dynamic performance.

[0081] In any embodiment, the shell has a thickness of 1-15 nm.

[0082] In any embodiment, the thickness of the first cladding layer is 1-10nm, optionally 2-10nm; and / or the thickness of the second cladding layer is 2-25nm, optionally 2-15nm, more optionally 3-15nm; and / or the thickness of the third cladding layer is 2-25nm, optionally 5-25nm.

[0083] In any embodiment, the one or more coating layers independently include one or more selected from pyrophosphate, phosphate and oxide, and one or more selected from the pyrophosphate, phosphate and oxide is crystalline; optionally, the crystallinity of the pyrophosphate, the phosphate and the oxide is independently 10% to 100%, and more optionally 50% to 100%.

[0084] Pyrophosphate and phosphate with a certain degree of crystallinity are not only conducive to giving full play to the pyrophosphate coating layer's ability to reduce manganese dissolution and the phosphate coating layer's excellent lithium ion conductivity and the function of reducing interface side reactions, but also enable the pyrophosphate coating layer and the phosphate coating layer to better lattice match, thereby achieving a close bond between the coating layers.

[0085] In any embodiment, in the shell, the weight ratio of pyrophosphate to phosphate and the weight ratio of pyrophosphate to oxide are each independently 1:3 to 3:1, optionally 1:3 to 1:1.

[0086] Therefore, by keeping pyrophosphate and phosphate in a suitable weight ratio range or pyrophosphate and oxide in a suitable weight ratio range, manganese dissolution can be effectively reduced, the surface impurity lithium content can be effectively reduced, and the interface side reaction can be reduced, thereby improving the high-temperature storage performance and high-temperature cycle performance of the battery.

[0087] In any embodiment, the one or more coating layers independently comprise carbon, and the carbon is a mixture of SP2 carbon and SP3 carbon. Optionally, the molar ratio of the SP2 carbon to the SP3 carbon is any value in the range of 0.07-13, more preferably any value in the range of 0.1-10, and further preferably any value in the range of 2.0-3.0. By selecting the carbon morphology in the carbon coating layer, the overall electrical performance of the battery is improved.

[0088] In any embodiment, the one or more coating layers independently include doped carbon, and the weight content of the doping element in the doped carbon is less than 30%; alternatively, the weight content of the doping element in the doped carbon is less than 20%. The doping element within the above content range can not only fully improve the conductivity of the pure carbon layer, but also effectively avoid excessive surface activity caused by excessive doping of the doping element, thereby effectively controlling interfacial side reactions caused by excessive doping of the coating layer.

[0089] In any embodiment, the one or more coating layers independently include doped carbon, in which the doping element is nitrogen and / or sulfur, and the mass content of the doping element in the doped carbon is 1% to 15%; or, the doping element is phosphorus, boron and / or fluorine, and the mass content of the doping element in the doped carbon is 0.5% to 5%; optionally, the doping element is nitrogen, phosphorus, sulfur, boron or fluorine.

[0090] Since nitrogen atoms and sulfur atoms are closer in atomic radius to carbon atoms and are less likely to destroy the carbon skeleton, when the doping amount of nitrogen atoms and sulfur atoms is within the above relatively wide range, the conductivity of the doped carbon layer can be fully exerted, and the lithium ion transport and lithium ion desolvation capabilities can be promoted.

[0091] Since the atomic radius of phosphorus atoms, boron atoms and / or fluorine atoms is different from that of carbon atoms, excessive doping can easily destroy the carbon skeleton. Therefore, when the doping amount of phosphorus atoms, boron atoms and / or fluorine atoms is within the above-mentioned relatively small range, it can not only fully exert the conductivity of the doped carbon layer, but also promote lithium ion transmission and lithium ion desolvation capabilities.

[0092] In any embodiment, the one or more coating layers independently include pyrophosphate, the interplanar spacing of the pyrophosphate is in the range of 0.293-0.470 nm, optionally 0.297-0.462 nm or 0.293-0.326 nm, more optionally 0.300-0.310 nm, and the angle of the crystal direction (111) is in the range of 18.00°-32.57°, optionally 18.00°-32.00° or 26.41°- 32.57°, more optionally 19.211°-30.846°, further optionally 29.00°-30.00°; and / or, the one or more coating layers each independently include phosphate, the phosphate has a lattice spacing range of 0.244-0.425nm, optionally 0.345-0.358nm, and a crystal orientation (111) angle range of 20.00°-37.00°, optionally 24.25°-26.45°.

[0093] The first and second coating layers of the second positive electrode active material are both crystalline, with their interplanar spacing and angles falling within the aforementioned ranges. This effectively reduces impurity phases in the coating layers, thereby improving the material's specific capacity, cycle performance, and rate capability.

[0094] In any embodiment, the first coating layer or the second coating layer comprises phosphate.

[0095] In any embodiment, the lattice change rate of the second positive electrode active material before and after complete lithium deintercalation is 50% or less, optionally 9.8% or less, more optionally 8.1% or less, further optionally 7.5% or less, further optionally 6% or less, further optionally 4% or less, further optionally 3.8% or less, and further optionally 2.0-3.8%. By reducing the lattice change rate, lithium ion transport can be facilitated, that is, the mobility of lithium ions in the second positive electrode active material is stronger, which is beneficial to improving the rate performance of the battery.

[0096] In any embodiment, the Li / Mn antisite defect concentration of the second positive electrode active material is 5.3% or less, optionally 5.1% or less, more optionally 4% or less, further optionally 2.2% or less, further optionally 2% or less, further optionally 1.5%-2.2% or 0.5% or less. By reducing the Li / Mn antisite defect concentration, the specific capacity and rate performance of the second positive electrode active material are improved.

[0097] In any embodiment, the surface oxygen valence state of the second positive electrode active material is -1.55 or less, optionally -1.82 or less, more optionally -1.88 or less, further optionally -1.90 or less, or -1.98 to -1.88, further optionally -1.98 to -1.89, and further optionally -1.98 to -1.90. By reducing the surface oxygen valence state, it is possible to reduce the interfacial side reactions between the second positive electrode active material and the electrolyte, thereby improving the cycle performance and high temperature stability of the battery.

[0098] In any embodiment, the powder compaction density P1 of the first positive electrode active material at 30000N is 3.0 g / cm 3 Above, 3.2g / cm2 can be selected 3 Above, 3.3g / cm2 is optional 3 Above, further optional 3.4g / cm 3 Above, further optional 3.5g / cm 3 above.

[0099] In any embodiment, the powder compaction density P2 of the second positive electrode active material at 30000N is 1.89 g / cm 3 Above, 1.95g / cm2 is optional 3 Above, 1.98g / cm2 is optional 3 Above, further optional 2.0g / cm 3 Above, further optional 2.2g / cm 3 Above, further optionally 2.2g / cm 3 Above and 2.8g / cm 3 Below or 2.2g / cm 3 Above and 2.65g / cm 3 the following.

[0100] The higher the powder compaction density, the greater the weight of the material per unit volume, which is beneficial to increasing the compaction density of the positive electrode sheet and the volume energy density of the battery.

[0101] In any embodiment, the first positive electrode active material includes one or more of a layered oxide material, a lithium-rich oxide material, a spinel-type lithium manganate material, and modified compounds thereof, wherein the modification method includes doping and / or surface coating modification. By properly combining the second positive electrode active material with the first positive electrode active material, the actual packing density of the positive electrode active material composition can be increased, the compaction density and compaction density efficiency of the positive electrode sheet can be improved, and the battery can also achieve high energy density, low cost, and a long service life.

[0102] In any embodiment, the first positive electrode active material includes a compound represented by formula (II), Li a1 A 1 b1 Ni c1 Co d1 B 1 e1 C 1 f1 O 2-g1 D 1 g1 (II)

[0103] A 1 including one or more elements selected from Group IA, Group IIA, Group VIII, Group VIB, and Group IIB; B 1 including Mn and / or Al; C 1 comprising one or more elements selected from Group IA, Group IIA, Group IIIA, Group IVA, Group VA, Group VIA, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, and Group VIII; D 1 Includes one or more elements selected from Group VIA and Group VIIA; a1 is selected from the range of 0.8 to 1.2; b1 is selected from the range of 0 to 0.2; c1 is selected from the range of 0 to 1; d1 is selected from the range of 0 to 1; e1 is selected from the range of 0 to 1; f1 is selected from the range of 0 to 0.1; g1 is selected from the range of 0 to 0.1; and c1+d1+e1+f1=1.

[0104] In any embodiment, A 1 including one or more elements selected from Na, K, Mg, Rb, Zn, and Zr; and / or C 1 including one or more elements selected from the group consisting of Al, Mg, Ca, Na, Ti, W, Zr, Sr, Cr, Fe, Zn, Ba, Mo, V, Ce, Nb, Sb, Ta, Ge, Nb, Sc, Ba, B, S, and Y, and optionally including one or more elements selected from the group consisting of Al, Ti, Zr, Nb, Sr, Sc, Sb, Y, Ba, and B; and / or, D 1Includes one or more elements selected from N, S, F, Cl and Br, and may optionally include S and / or F; and / or, a1 is selected from the range of 0.9 to 1.1; and / or, b1 is selected from the range of 0 to 0.1; and / or, c1 is selected from the range of 0.314 to 0.990, and may optionally be selected from the range of 0.500 to 0.990; and / or, d1 is selected from the range of 0 to 0.320, and may optionally be selected from the range of 0 to 0.150; and / or, e1 is selected from the range of 0.001 to 0.450, and may optionally be selected from the range of 0.005 to 0.4; and / or, f1 is selected from the range of 0.001 to 0.1, and may optionally be selected from the range of 0.001 to 0.05; and / or, g1 is selected from the range of 0 to 0.01, and may optionally be selected from the range of 0.01 to 0.05.

[0105] In any embodiment, the first positive electrode active material includes a core and a shell covering the core, the core includes the compound represented by formula (II); the shell includes one or more coating layers; each coating layer has ionic conductivity and / or electronic conductivity.

[0106] In any embodiment, one or more coating layers in the shell coating the compound represented by formula (II) independently include one or more selected from phosphate, pyrophosphate, carbon, doped carbon, oxide, and fast ion conductor, and may optionally include one or more selected from phosphate, pyrophosphate, and oxide.

[0107] In any embodiment, the shell encapsulating the compound represented by formula (II) includes a coating layer; optionally, the coating layer includes one or more selected from phosphates, pyrophosphates, and oxides.

[0108] In any embodiment, the shell coating the compound represented by formula (II) includes a first coating layer coating the core and a second coating layer coating the first coating layer; optionally, the first coating layer and the second coating layer each independently include one or more selected from phosphates, pyrophosphates, and oxides; more optionally, the first coating layer includes one or more selected from phosphates and oxides, and the second coating layer includes one or more selected from pyrophosphates and oxides.

[0109] In any embodiment, the coating amount of the shell coating the compound represented by formula (II) is 0.005 wt% to 1 wt%, optionally 0.01 wt% to 0.5 wt%, based on the weight of the core; and / or the thickness of the shell coating the compound represented by formula (II) is 2 nm to 200 nm, optionally 5 nm to 50 nm.

[0110] In any embodiment, the first positive electrode active material includes a compound represented by formula (III), Li1+p1 A 2 q1 B 2 r1 O s1 (III)

[0111] 0.05 ≤ p1 < 0.2, 0.10 < q1 ≤ 0.95, 0 ≤ r1 ≤ 0.2, and 2 ≤ s1 < 3, A 2 comprises one or more elements selected from Co, Ni, Mn, and Al; B 2 comprises one or more elements selected from Mg, Ti, Cr, Zr, Nb, Fe, Mo, Cu, Sb, V, P, and F.

[0112] In any embodiment, the first positive electrode active material includes a core and a shell coating the core, the core includes the compound represented by the formula (III); the shell includes one or more coating layers; each coating layer has ionic conductivity and / or electronic conductivity.

[0113] In any embodiment, one or more of the coating layers in the shell coating the compound represented by the formula (III) independently includes one or more selected from phosphates, pyrophosphates, solid electrolytes, conductive polymers, and materials capable of reversibly inserting and extracting lithium ions.

[0114] In any embodiment, the coating amount of the shell coating the compound represented by the formula (III) is 0.1 wt% to 5 wt%, optionally 0.5 wt% to 2 wt%, based on the weight of the core; and / or, the thickness of the shell coating the compound represented by the formula (III) is 2 nm to 200 nm, optionally 5 nm to 50 nm.

[0115] In any embodiment, the first positive electrode active material includes a compound represented by the formula (IV), LiMn t1 A 3 2-t1 O4 (IV)

[0116] t1 is selected from the range of 0 to 2, A 3 comprises one or more elements selected from Ni, Cr, Al, Zr, V, Ti, Mo, Ru, Mg, Nb, Ba, Si, P, W, Co, Cu, and Zn.

[0117] In any embodiment, the third positive electrode active material includes a core and a shell coating the core, the core includes the compound represented by the formula (IV); the shell includes one or more coating layers; each coating layer has ionic conductivity and / or electronic conductivity.

[0118] In any embodiment, the one or more coating layers in the shell coating the compound represented by formula (IV) independently include one or more materials selected from phosphates, pyrophosphates, solid electrolytes, conductive polymers, and materials capable of reversibly inserting and deinserting lithium ions.

[0119] In any embodiment, the coating amount of the shell coating the compound represented by formula (IV) is 0.1 wt % to 3 wt %, optionally 0.2 wt % to 1.5 wt %, based on the weight of the core; and / or the thickness of the shell coating the compound represented by formula (IV) is 2 nm to 200 nm, optionally 5 nm to 50 nm.

[0120] A second aspect of the present application provides a positive electrode plate, comprising a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises the positive electrode active material composition of the first aspect of the present application.

[0121] In any embodiment, the content of the positive electrode active material composition in the positive electrode film layer is 90-99.5% by weight, and more preferably 95-99.5% by weight, based on the total weight of the positive electrode film layer.

[0122] In any embodiment, the positive electrode sheet satisfies 0.23≤(h1×N1) / (CW / PD / 10000)<1, optionally, 0.63≤(h1×N1) / (CW / PD / 10000)≤0.87, where h1 represents the average size of the first positive electrode active material particles along the thickness direction of the positive electrode film layer, in μm; N1 represents the number of first positive electrode active material particles accommodated in the positive electrode film layer along the thickness direction of the positive electrode film layer; CW represents the surface density of the positive electrode film layer, in g / cm 2 PD represents the compaction density of the positive electrode film layer, in g / cm 3 This allows the battery to have a long cycle life.

[0123] In any embodiment, along the thickness direction of the positive electrode film layer, the average size h1 of the first positive electrode active material particles is 0.5-20 μm, and optionally 2.8-9.2 μm.

[0124] In any embodiment, along the thickness direction of the positive electrode film layer, the number N1 of the first positive electrode active material particles contained in the positive electrode film layer is 5-25, and can be optionally 6-20.

[0125] In any embodiment, the surface density CW of the positive electrode film layer is 0.01-0.05 g / cm 2 , optional 0.015-0.035g / cm 2 .

[0126] In any embodiment, the compaction density PD of the positive electrode film layer is 1.8-3.6 g / cm 3 , optional 2.0-3.4g / cm 3 .

[0127] In any embodiment, the positive electrode sheet also satisfies 0.5≤α1+(PD / ρ1)≤1.5, where α1 represents the porosity of the positive electrode film layer. This can enable the battery to have a long cycle life and / or high energy density.

[0128] In any embodiment, the porosity α1 of the positive electrode film layer is 0.28-0.50, and can be optionally 0.30-0.39.

[0129] In any embodiment, based on the total mass of the positive electrode active material composition, the mass proportion of the first positive electrode active material is recorded as W1, the mass proportion of the second positive electrode active material is recorded as W2, the powder compaction density of the first positive electrode active material at 30000N is recorded as P1, and the powder compaction density of the second positive electrode active material at 30000N is recorded as P2, both in g / cm 3 , then PD / [(P1×W1)+(P2×W2)] is above 89%, and can be optionally above 92%.

[0130] A third aspect of the present application provides a battery, comprising the positive electrode active material composition of the first aspect of the present application, or the positive electrode plate of the second aspect of the present application.

[0131] A fourth aspect of the present application provides an electrical device comprising the battery of the third aspect of the present application.

[0132] The electric device of the present application includes the battery provided by the present application, and thus has at least the same advantages as the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0133] To more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on the drawings without inventive effort.

[0134] FIG1 is a schematic diagram of a battery cell according to an embodiment of the present application.

[0135] FIG2 is an exploded schematic diagram of an embodiment of a battery cell of the present application.

[0136] FIG3 is a schematic diagram of an embodiment of a battery module of the present application.

[0137] FIG4 is a schematic diagram of an embodiment of a battery pack of the present application.

[0138] FIG. 5 is an exploded schematic diagram of the embodiment of the battery pack shown in FIG. 4 .

[0139] FIG6 is a schematic diagram of an embodiment of an electric device including the battery of the present application as a power source.

[0140] In the accompanying drawings, which are not necessarily drawn to scale, reference numerals are as follows: 1 battery pack, 2 upper housing, 3 lower housing, 4 battery module, 5 battery cell, 51 housing, 52 electrode assembly, 53 cover plate. DETAILED DESCRIPTION

[0141] Below, with appropriate reference to the accompanying drawings, the embodiments of the positive electrode active material composition, positive electrode sheet, battery, and electrical device of the present application are described in detail. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0142] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0143] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0144] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of this application.

[0145] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0146] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0147] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0148] Unless otherwise specified, in this application, the terms "first", "second", "third", "fourth", "fifth", etc. are used to distinguish different objects rather than to describe a specific order or a primary-secondary relationship.

[0149] In this application, the terms "plurality" and "multiple" refer to two or more.

[0150] Throughout this specification, substituents of compounds are disclosed in groups or ranges. It is expressly intended that such descriptions include each individual subcombination of the members of these groups and ranges. For example, it is expressly intended that the term "C1-C6 alkyl" individually discloses C1, C2, C3, C4, C5, C6, C1-C6, C1-C5, C1-C4, C1-C3, C1-C2, C2-C6, C2-C5, C2-C4, C2-C3, C3-C6, C3-C5, C3-C4, C4-C6, C4-C5, and C5-C6 alkyl.

[0151] Unless otherwise specified, the terms used in this application have the common meanings that are commonly understood by those skilled in the art.

[0152] Unless otherwise stated, the values ​​of the various parameters mentioned in this application can be measured using various test methods commonly used in the art, for example, they can be measured according to the test methods given in the examples of this application. Unless otherwise stated, the test temperature of each parameter is 25°C.

[0153] Unless otherwise specified, all ratio parameters mentioned in this application are compared in the same units. For example, the ratio of the volume distribution particle sizes of A and B is 1:1, and the units of the volume distribution particle sizes of A and B are the same.

[0154] In this application, the term "compaction density efficiency" refers to the ratio of the compaction density of the membrane layer to the theoretical compaction density of the active material powder.

[0155] In the present application, the first positive electrode active material, the second positive electrode active material, and the third positive electrode active material can be tested for element content using inductively coupled plasma emission spectroscopy (ICP).

[0156] The battery mentioned in the embodiments of this application refers to a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in this application may include a battery cell, a battery module or a battery pack.

[0157] A battery cell is the smallest unit of a battery, independently capable of charging and discharging. A battery cell can be cylindrical, flat, rectangular, or in other shapes, though this is not a limitation in the present invention. Figure 1 shows a battery cell 5 with a rectangular structure as an example.

[0158] When there are multiple battery cells, the multiple battery cells are connected in series, in parallel, or in mixed series via a busbar. In some embodiments, the battery may be a battery module; when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module. In some embodiments, the battery may be a battery pack, which includes a housing and battery cells, with the battery cells or battery modules housed in the housing. In some embodiments, the housing may serve as part of the vehicle's chassis structure. For example, a portion of the housing may form at least a portion of the vehicle's floor, or a portion of the housing may form at least a portion of the vehicle's crossbeam or longitudinal beam.

[0159] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0160] The battery cells mentioned in the embodiments of the present application include lithium-ion primary battery cells, lithium-ion secondary battery cells, lithium metal battery cells, negative electrode-free lithium metal battery cells, etc., which are not limited in the embodiments of the present application.

[0161] A battery cell generally includes an electrode assembly. The electrode assembly generally includes a positive electrode sheet, a negative electrode sheet, and a separator located between the positive and negative electrode sheets. The electrode assembly can be a wound structure or a laminated structure, which is not limited in the present embodiment.

[0162] The battery cell may also include an outer packaging that can be used to encapsulate the electrode assembly and electrolyte. The outer packaging can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging can also be a soft package, such as a bag-type soft package. The soft package can be made of plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0163] In some embodiments, as shown in Figure 2, the outer packaging may include a housing 51 and a cover plate 53. The housing 51 may include a base plate and side plates connected to the base plate, which together form a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 is used to cover the opening, thereby sealing the receiving cavity. The electrode assembly 52 is enclosed in the receiving cavity. The number of electrode assemblies 52 contained in a battery cell 5 can be one or more, and can be adjusted according to needs.

[0164] In some embodiments, battery cells can be assembled into a battery module. The number of battery cells contained in a battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module. Figure 3 is a schematic diagram of a battery module 4 as an example. As shown in Figure 3, in the battery module 4, multiple battery cells 5 can be arranged in sequence along the length of the battery module 4. Of course, they can also be arranged in any other manner. The multiple battery cells 5 can further be fixed by fasteners.

[0165] Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of battery cells 5 are accommodated in the accommodation space.

[0166] In some embodiments, the battery modules described above may also be assembled into a battery pack, and the number of battery modules contained in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0167] Figures 4 and 5 are schematic diagrams of an exemplary battery pack 1. As shown in Figures 4 and 5, the battery pack 1 may include a housing and multiple battery modules 4 disposed within the housing. The housing comprises an upper housing 2 and a lower housing 3. The upper housing 2 covers the lower housing 3 and forms an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 may be arranged in any manner within the housing.

[0168] The positive electrode sheet contains the positive electrode active material. As an important component of the battery, the performance of the positive electrode active material is a major factor that affects the battery's energy density and service life. Currently, no positive electrode active material has been developed that can simultaneously meet the requirements of low cost, high capacity, and low side reactions.

[0169] In view of this, the inventors have proposed a positive electrode active material composition, which can enable a battery to have high energy density, low cost and good service life.

[0170] [Positive Electrode Active Material Composition]

[0171] The positive electrode active material composition provided in the embodiment of the present application includes a first positive electrode active material and a second positive electrode active material having a different crystal form from the first positive electrode active material, wherein the second positive electrode active material includes a phosphate material.

[0172] Volume distribution particle size Dv10 of the first positive electrode active material (1) The volume distribution particle size Dv50 of the second positive electrode active material (2) Meet Dv10 (1) / Dv50 (2) >1, the volume distribution particle size Dv50 of the first positive electrode active material (1) The volume distribution particle size Dv50 of the second positive electrode active material (2) Meet Dv50 (1) / Dv50 (2) ≥1.4.

[0173] The true density of the first positive electrode active material is denoted as ρ1, and the true density of the second positive electrode active material is denoted as ρ2, both in g / cm 3 Based on the total mass of the positive electrode active material composition, the mass proportion of the first positive electrode active material is recorded as W1, and the mass proportion of the second positive electrode active material is recorded as W2. Then the positive electrode active material composition satisfies -2.0≤1-[(ρ2×W2) / (ρ1×W1)]≤0.98.

[0174] The second positive electrode active material includes phosphate, which is usually an olivine structure and has a generally low production cost. However, the compaction density of the second positive electrode active material is relatively low, making it difficult to meet the requirements of high energy density batteries. Combining it with another positive electrode active material with a high compaction density can increase the compaction density of the positive electrode sheet. However, simply mixing the two positive electrode active materials generally does not improve the compaction density and compaction density efficiency of the positive electrode sheet, making it difficult to fully utilize the battery capacity and also affecting the battery life.

[0175] The inventors have found that by adjusting the volume distribution particle size, true density and mass ratio of the first positive electrode active material and the second positive electrode active material in the positive electrode active material composition, the battery using the positive electrode active material composition of the present application can have high energy density, low cost and good service life.

[0176] By adjusting the volume distribution particle size Dv10 of the first positive electrode active material (1) The volume distribution particle size Dv50 of the second positive electrode active material (2) Meet Dv10 (1) / Dv50 (2) >1, the second positive electrode active material can fill the gaps between the first positive electrode active material particles, thereby facilitating a closer stacking of the first positive electrode active material and the second positive electrode active material.

[0177] By adjusting the volume distribution particle size Dv50 of the first positive electrode active material (1) The volume distribution particle size Dv50 of the second positive electrode active material (2) Meet Dv50 (1) / Dv50 (2) ≥1.4, which is conducive to closer stacking of the first positive electrode active material and the second positive electrode active material.

[0178] The inventors also discovered that simply adjusting the volume distribution particle size of the first and second positive electrode active materials does not result in a high compacted density for the positive electrode sheet. However, by further adjusting the true density ρ1 and mass fraction W1 of the first positive electrode active material and the true density ρ2 and mass fraction W2 of the second positive electrode active material to satisfy -2.0≤1-[(ρ2×W2) / (ρ1×W1)]≤0.98 on the basis of satisfying the above conditions, the first and second positive electrode active materials can be more densely packed, thereby increasing the actual packing density of the positive electrode active material composition, the compacted density of the positive electrode sheet, and the compacted density efficiency, thereby enabling batteries using the positive electrode active material composition of the present application to have high energy density and long service life.

[0179] The true density ρ1 of the first positive electrode active material is related to parameters such as the type, elemental composition, crystal form, particle morphology, structure (such as porosity, optional coating layer type, optional coating layer thickness, etc.) of the first positive electrode active material. By adjusting one or more of the above parameters, the first positive electrode active material can have a suitable true density ρ1.

[0180] The true density ρ2 of the second positive electrode active material is related to parameters such as the type, elemental composition, crystal form, particle morphology, structure (such as porosity, optional coating layer type, optional coating layer thickness, etc.) of the second positive electrode active material. By adjusting one or more of the above parameters, the second positive electrode active material can have a suitable true density ρ2.

[0181] The true density ρ1 of the first positive electrode active material and the true density ρ2 of the second positive electrode active material have meanings well known in the art and can be determined using methods known in the art. For example, they can be determined with reference to GB / T1033.1, GB / T6155, GB / T23561, YB / T5300, JB / T7984.3, GB / T 1713, GB / T8929, GB / T1713, GB / T208, GB / T5071, QB / T1010, GB / T9966, GB / T18856, GB / T24203, GB / T8330, or SL-237.

[0182] The volume distribution particle sizes Dv10 and Dv50 of materials (e.g., the first positive electrode active material and the second positive electrode active material) have well-known meanings in the art, representing the particle sizes corresponding to 10% and 50% of the cumulative volume distribution percentage of the material, respectively. These can be measured using instruments and methods known in the art. For example, the measurement can be performed using a laser particle size analyzer, as described in GB / T 19077-2016. The testing instrument can be a Mastersizer 3000 laser particle size analyzer from Malvern Instruments Ltd., UK. Deionized water can be used as the solvent for the test, and the material can be ultrasonically treated for 5 minutes prior to testing.

[0183] The different crystal forms of the first positive electrode active material and the second positive electrode active material mean that the first positive electrode active material and the second positive electrode active material have different crystal systems.

[0184] In some embodiments, 1 < Dv10 (1) / Dv50 (2) ≤16.5, optionally, 1.07≤Dv10 (1) / Dv50 (2) ≤11.3, 1.07≤Dv10 (1) / Dv50 (2) ≤9.0, 1.07≤Dv10 (1) / Dv50 (2) ≤8.0, 1.07≤Dv10 (1) / Dv50 (2)≤7.0. This allows the first positive electrode active material and the second positive electrode active material to be stacked more densely, further improving the actual stacking density of the positive electrode active material composition, improving the compaction density and compaction density efficiency of the positive electrode sheet, and thus enabling the battery using the positive electrode active material composition of the present application to have a higher energy density and / or a longer service life.

[0185] As an example, Dv10 (1) / Dv50 (2) can be 1.02, 1.05, 1.07, 1.1, 1.2, 1.4, 1.8, 2.0, 2.5, 2.7, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.3, 14.0, 16.5, or any range thereof.

[0186] In some embodiments, 1.4 < Dv50 (1) / Dv50 (2) ≤30.0, optionally, 2.0≤Dv50 (1) / Dv50 (2) ≤23.8, 2.0≤Dv50 (1) / Dv50 (2) ≤9.8. This allows the first positive electrode active material and the second positive electrode active material to be stacked more densely, further improving the actual stacking density of the positive electrode active material composition, improving the compaction density and compaction density efficiency of the positive electrode sheet, and thus enabling the battery using the positive electrode active material composition of the present application to have a higher energy density and / or a longer service life.

[0187] As an example, Dv50 (1) / Dv50 (2) can be 1.5, 1.8, 2.0, 2.3, 2.5, 3.0, 4.0, 5.7, 7.0, 8.5, 9.0, 9.8, 11.0, 12.0, 14.0, 16.0, 18.0, 20.0, 22.0, 23.8, 26.0, 28.0, 30.0, or any range thereof.

[0188] In some embodiments, -0.78≤1-[(ρ2×W2) / (ρ1×W1)]≤0.96, optionally, -0.14≤1-[(ρ2×W2) / (ρ1×W1)]≤0.92, 0.24≤1-[(ρ2×W2) / (ρ1×W1)]≤0.92, 0.49≤1-[(ρ2×W2) / (ρ1×W1)]≤0.92, and 0.67≤1-[(ρ2×W2) / (ρ1×W1)]≤0.92. This allows the first positive electrode active material and the second positive electrode active material to be stacked more densely, further improving the actual stacking density of the positive electrode active material composition, improving the compaction density and compaction density efficiency of the positive electrode sheet, and thus enabling the battery using the positive electrode active material composition of the present application to have a higher energy density and a longer service life.

[0189] As an example, 1-[(ρ2×W2) / (ρ1×W1)] can be -1.5, -1.0, -0.78, -0.50, -0.25, -0.14, 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.67, 0.80, 0.87, 0.9, 0.92, 0.94, 0.96, 0.98, or any range of any of the above values.

[0190] In some embodiments, the ratio of the major axis length to the minor axis length of the first positive electrode active material is 1-2, and may be 1-1.4.

[0191] In some embodiments, the ratio of the major axis length to the minor axis length of the second positive electrode active material is 1-2, and may be 1-1.4.

[0192] The first positive electrode active material and the second positive electrode active material may have regular morphologies, such as spherical or quasi-spherical shapes, or may have irregular morphologies.

[0193] In some embodiments, the volume distribution particle size Dv10 of the first positive electrode active material is (1) 0.3-8μm, optional 1.6-6.6μm.

[0194] In some embodiments, the volume distribution particle size Dv50 of the first positive electrode active material is (1) 1.5-15μm, optional 3-12μm.

[0195] In some embodiments, the volume distribution particle size Dv50 of the second positive electrode active material is (2) 0.25-3μm, optional 0.4-2μm.

[0196] When the volume distribution particle size of the first positive electrode active material and / or the second positive electrode active material is within the above range, the battery can have a higher energy density, and can also reduce side reactions, thereby extending the battery life.

[0197] In some embodiments, the true density ρ1 of the first positive active material is 4.40-5.15 g / cm 3 , optional 4.60-5.10g / cm 3 .

[0198] In some embodiments, the true density ρ2 of the second positive electrode active material is 3.20-3.65 g / cm 3 , optional 3.30-3.60g / cm 3 .

[0199] In some embodiments, based on the total mass of the positive electrode active material composition, the mass proportion W1 of the first positive electrode active material is 30%-98%, optionally 50%-90%, or 70%-90%, thereby enabling the battery to better balance high energy density and long service life.

[0200] In some embodiments, based on the total mass of the positive electrode active material composition, the mass proportion W2 of the second positive electrode active material is 2%-70%, optionally 10%-50%, or 10%-30%. This enables the battery to better balance high energy density and long service life.

[0201] In some embodiments, the powder compaction density P1 of the first positive electrode active material at 30000N is 3.0 g / cm 3 Above, 3.2g / cm2 can be selected 3 Above, 3.3g / cm2 is optional 3 Above, further optional 3.4g / cm 3 Above, further optional 3.5g / cm 3 above.

[0202] In some embodiments, the powder compaction density P2 of the second positive electrode active material at 30000N is 1.89 g / cm 3 Above, 1.95g / cm2 is optional 3 Above, 1.98g / cm2 is optional 3 Above, further optional 2.0g / cm 3 Above, further optional 2.2g / cm 3 Above, further optionally 2.2g / cm 3 Above and 2.8g / cm 3 Below or 2.2g / cm 3 Above and 2.65g / cm3 the following.

[0203] The higher the powder compaction density, the greater the weight of the material per unit volume, which is beneficial for increasing the compaction density of the positive electrode sheet and the volumetric energy density of the battery. Powder compaction density can be measured according to GB / T 24533-2009.

[0204] In some embodiments, W2=ρ2 / [(β×ρ1)+ρ2], 0.3≤β≤30, optionally, 0.5≤β≤6.9, 0.8≤β≤6.9, 1.1≤β≤6.9, 1.8≤β≤6.9. By setting β within the above range, the positive electrode active material composition can have a higher actual packing density, thereby further improving the compaction density and compaction density efficiency of the positive electrode sheet, thereby enabling the battery using the positive electrode active material composition of the present application to have a higher energy density and / or a longer service life.

[0205] In some embodiments, the particle size distribution curve of the positive electrode active material composition has at least two volume distribution peaks, the peak with the smallest volume distribution particle size is recorded as peak I, and the peaks other than peak I are recorded as peak II. Peak II can have one or more peaks.

[0206] The volume distribution particle size corresponding to the maximum peak intensity of Peak I is between 0.3 μm and 2.1 μm, and the volume distribution particle size corresponding to the maximum peak intensity of Peak II is between 3 μm and 15 μm. The ratio of the integrated area of ​​Peak I to the total integrated area of ​​Peak II is (0.010-2.5):1, and can optionally be (0.011-1.3):1. The total integrated area of ​​Peak II refers to the sum of the integrated areas of multiple peaks in Peak II.

[0207] By making the ratio of the integral area of ​​peak I to the total integral area of ​​peak II in the particle size distribution curve of the positive electrode active material composition within the above range, the contribution of the first positive electrode active material to the compaction density of the positive electrode sheet can be improved, and the second positive electrode active material can be better filled in the gaps between the particles of the first positive electrode active material, thereby making the first positive electrode active material and the second positive electrode active material more densely stacked, thereby improving the actual stacking density of the positive electrode active material composition, improving the compaction density and compaction density efficiency of the positive electrode sheet, and further making the battery using the positive electrode active material composition of the present application have a higher energy density and / or a longer service life.

[0208] The particle size distribution curve of the positive electrode active material composition can be measured with reference to GB / T 19077-2016 using a laser particle size analyzer. The testing instrument can be a Mastersizer 3000 laser particle size analyzer from Malvern Instruments Ltd., UK. Deionized water can be used as the solvent for testing, and the material can be ultrasonically treated for 5 minutes before testing.

[0209] In some embodiments, the particle size distribution curve of the second positive electrode active material has at least two volume distribution peaks, the peak with the smallest volume distribution particle size is recorded as peak III, and the peaks other than peak III are recorded as peak IV.

[0210] The volume distribution particle size corresponding to the maximum peak intensity of peak III is between 0.3 μm and 2.1 μm, the volume distribution particle size corresponding to the maximum peak intensity of peak IV is between 2.1 μm and 10 μm, and the ratio of the integral area of ​​peak III to the total integral area of ​​peak IV is (0.5-20):1.

[0211] By ensuring that the ratio of the integral area of ​​peak III to the total integral area of ​​peak IV in the particle size distribution curve of the second positive electrode active material is within the above range, the second positive electrode active material can be promoted to better fill the gaps between the particles of the first positive electrode active material, thereby enabling the first positive electrode active material and the second positive electrode active material to be more densely stacked, thereby improving the actual stacking density of the positive electrode active material composition, improving the compaction density and compaction density efficiency of the positive electrode sheet, and further enabling the battery using the positive electrode active material composition of the present application to have a higher energy density and / or a longer service life.

[0212] The particle size distribution curve of the second positive electrode active material can be measured with reference to GB / T 19077-2016 using a laser particle size analyzer. The testing instrument can be a Mastersizer 3000 laser particle size analyzer from Malvern Instruments Ltd., UK. Deionized water can be used as the solvent for testing, and the material can be ultrasonically treated for 5 minutes before testing.

[0213] In some embodiments, the second positive electrode active material includes a compound represented by formula (I), Li a A x Mn 1-y B y P 1-z C z O 4-n D n (I)

[0214] A includes one or more elements selected from Group IA, Group IIA, Group IIIA, Group IIB, Group VB and Group VIB; B includes one or more elements selected from Group IA, Group IIA, Group IIIA, Group IVA, Group VA, Group IIB, Group IVB, Group VB, Group VIB and Group VIII; C includes one or more elements selected from Group IIIA, Group IVA, Group VA and Group VIA; D includes one or more elements selected from Group VIA and Group VIIA; a is selected from the range of 0.85 to 1.15; x is selected from the range of 0 to 0.1; y is selected from the range of 0.001 to 1; z is selected from the range of 0 to 0.5; n is selected from the range of 0 to 0.5.

[0215] Unless otherwise specified, in the above chemical formula, when A is two or more elements, the above-mentioned numerical range for x is not only a limit on the stoichiometric number of each element serving as A, but also a limit on the sum of the stoichiometric numbers of each element serving as A. For example, when A is two or more elements A1, A2, ..., An, the stoichiometric numbers x1, x2, ..., xn of A1, A2, ..., An must each fall within the numerical range for x specified in this application, and the sum of x1, x2, ..., xn must also fall within this numerical range.

[0216] Similarly, for B, C, D, M, M', X, Z, P, Q, A mentioned in the embodiments of this application 1 、B 1 、C 1 、D 1 、A 2 、B 2 、A 3 When there are two or more elements, the numerical range of the stoichiometric number in this application also has the above meaning.

[0217] In some embodiments, y is selected from the range of 0.001 to 0.999.

[0218] The second positive electrode active material is obtained by doping elements in the compound LiMnPO4, wherein A, B, C and D are elements doped in the Li, Mn, P and O positions of the compound LiMnPO4, respectively. Without wishing to be bound by theory, it is now believed that the performance improvement of lithium manganese phosphate is related to reducing the lattice change rate of lithium manganese phosphate during the lithium insertion and extraction process and reducing the surface activity. Reducing the lattice change rate can reduce the lattice constant difference between the two phases at the grain boundary, reduce the interfacial stress, and enhance the Li +The transport capacity at the interface improves the rate performance of the second positive electrode active material. However, high surface activity can easily lead to serious side reactions at the interface, exacerbating gas production, electrolyte consumption and interface damage, thereby affecting the cycle performance of the battery. The lattice change rate can be reduced by doping with Li and / or Mn. Mn doping can also effectively reduce surface activity, thereby reducing Mn dissolution and side reactions at the interface between the second positive electrode active material and the electrolyte. P-site doping makes the change rate of the Mn-O bond length faster, reduces the migration barrier of small polarons in the material, and is beneficial to improving electronic conductivity. O-site doping has a good effect on reducing side reactions at the interface. P-site and / or O-site doping also affects the Mn dissolution and kinetic properties of antisite defects. Therefore, doping reduces the concentration of antisite defects in the material, improves the kinetic properties and specific capacity of the material, and can also change the morphology of the particles, thereby improving the compaction density. The inventors unexpectedly discovered that by doping a specific element in a specific amount at the Mn position of the compound LiMnPO4 and optionally at the Li position, P position and / or O position, improved rate performance can be obtained, while reducing the dissolution of Mn and the doping element at the Mn position, obtaining improved cycle performance and / or high-temperature stability, and the gram capacity and compaction density of the material are also improved.

[0219] In some embodiments, A includes one or more elements selected from Rb, Cs, Be, Ca, Sr, Ba, Ga, In, Cd, V, Ta, Cr, Zn, Al, Na, K, Mg, Nb, Mo, and W, and may optionally include one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo, and W; and / or

[0220] B comprises one or more elements selected from the group consisting of Rb, Cs, Be, Ca, Sr, Ba, In, Pb, Bi, Cd, Hf, Ta, Cr, Ru, Rh, Pd, Os, Ir, Pt, Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb, and Ge, and may optionally comprise one or more elements selected from the group consisting of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb, and Ge; and / or

[0221] C includes one or more elements selected from B (boron), S, Si and N; and / or,

[0222] D includes one or more elements selected from S, F, Cl and Br.

[0223] In some embodiments, A comprises any one element selected from Zn, Al, Na, K, Mg, Nb, Mo, and W, and optionally any one element selected from Mg and Nb; and / or

[0224] B comprises one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge, and may optionally comprise at least two elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge, and may further optionally comprise at least two elements selected from Fe, Ti, V, Ni, Co and Mg, and may further optionally comprise at least two elements selected from Fe, Ti, V, Co and Mg, and may further optionally comprise Fe and one or more elements selected from Ti, V, Co and Mg; and / or

[0225] C includes any one element selected from B (boron), S, Si and N, and may be S; and / or,

[0226] D includes any one element selected from S, F, Cl and Br, and may be F.

[0227] By selecting the Li-position doping element within the above range, the lattice change rate during the delithiation process can be further reduced, thereby further improving the rate performance of the battery. By selecting the Mn-position doping element within the above range, the electronic conductivity can be further improved and the lattice change rate can be further reduced, thereby improving the rate performance and gram capacity of the battery. By selecting the P-position doping element within the above range, the rate performance of the battery can be further improved. By selecting the O-position doping element within the above range, the side reactions at the interface can be further reduced, thereby improving the high-temperature performance of the battery.

[0228] In some embodiments, a is selected from the range of 0.9 to 1.1, optionally selected from the range of 0.97 to 1.01; and / or,

[0229] x is selected from the range of 0.001 to 0.005; and / or,

[0230] y is selected from the range of 0.001 to 0.5, optionally selected from the range of 0.01 to 0.5, optionally selected from the range of 0.25 to 0.5; and / or,

[0231] z is selected from the range of 0.001 to 0.5, alternatively selected from the range of 0.001 to 0.1, more alternatively selected from the range of 0.001 to 0.005; and / or,

[0232] n is selected from the range of 0 to 0.1, optionally from the range of 0.001 to 0.005.

[0233] By selecting the value of y within the above range, the gram capacity and rate performance of the second positive electrode active material can be further improved. By selecting the value of x within the above range, the kinetic performance of the second positive electrode active material can be further improved. By selecting the value of z within the above range, the rate performance of the battery can be further improved. By selecting the value of n within the above range, the high-temperature performance of the battery can be further improved.

[0234] In some embodiments, y is selected from the range of 0.001 to 0.999, and x is 0, z is selected from the range of 0.001 to 0.5, and n is selected from the range of 0.001 to 0.1; or, x is selected from the range of 0.001 to 0.1, z is 0, and n is selected from the range of 0.001 to 0.1; or, x is selected from the range of 0.001 to 0.1, z is 0, and n is 0; or, x is 0, z is 0, and n is selected from the range of 0.001 to 0.1; or, x is 0, z is 0, and n is selected from the range of 0.001 to 0.5, and n is 0; or, x is selected from the range of 0.001 to 0.1, z is selected from the range of 0.001 to 0.5, and n is 0.

[0235] Thus, by doping a specific element in a specific amount at the Mn position of the compound LiMnPO4 and optionally at the Li position, P position and / or O position, especially doping a specific element in a specific amount at the Mn position and P position of LiMnPO4 or at the Li position, Mn position, P position and O position of LiMnPO4, the rate performance can be improved, the dissolution of Mn and the doping element at the Mn position can be reduced, the cycle performance and / or high temperature stability can be improved, and the gram capacity and compaction density of the second positive electrode active material can be increased.

[0236] In some embodiments, y:z is selected from the range of 0.002 to 999, optionally from the range of 0.025 to 999 or from the range of 0.002 to 500, and more optionally from the range of 0.2 to 600, such as 0.2, 0.25, 1, 2, 3, 4, 5, 6, 8, 10, 12, 13, 15, 17, 20, 70, 80, 84, 67, 91, 100, 134, 150, 182, 200, 250, 300, 320, 350, 400, 420, 450, 500, 600, 999, or a range consisting of any two of the above values. Thus, the defects of the second positive electrode active material can be reduced, the integrity of the framework structure of the second positive electrode active material can be improved, thereby effectively improving the structural stability of the second positive electrode active material, and further improving the cycle stability of the battery.

[0237] In some embodiments, z:n is selected from the range of 0.002 to 500, optionally from the range of 0.2 to 100, and more preferably from the range of 0.2 to 50, such as 0.2, 0.8, 1, 1.25, 4, 5, 50, or a range consisting of any two of the foregoing values. This can further reduce defects in the second positive electrode active material, further improve the integrity of the framework structure of the second positive electrode active material, effectively enhance the structural stability of the second positive electrode active material, and improve the cycling stability of the battery.

[0238] In some embodiments, (1-y):y is in the range of 0.1-999, optionally in the range of 0.1-10 or in the range of 0.67-999, more optionally in the range of 1 to 10, further optionally in the range of 1 to 4, and further optionally in the range of 1.5 to 3; and / or,

[0239] a:x is in the range of 1 to 1200, and can be optionally in the range of 9 to 1100, and more optionally in the range of 190-998.

[0240] Here, y represents the sum of the stoichiometric numbers of the doping elements at the Mn site. When the above conditions are met, the energy density and cycle performance of the second positive electrode active material can be further improved.

[0241] In some embodiments, z:(1-z) is 1:9 to 1:999, and can be 1:499 to 1:249. When the above conditions are met, the energy density and cycle performance of the second positive electrode active material can be further improved.

[0242] In some embodiments, A includes one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo and W; B includes one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge; C includes one or more elements selected from B (boron), S, Si and N; D includes one or more elements selected from S, F, Cl and Br; a is selected from the range of 0.9 to 1.1, x is selected from the range of 0.001 to 0.1, y is selected from the range of 0.001 to 0.5, z is selected from the range of 0.001 to 0.1, and n is selected from the range of 0.001 to 0.1.

[0243] By doping specific elements in specific amounts at the Li, Mn, P, and O positions of the compound LiMnPO4 simultaneously, improved rate performance can be obtained, while reducing the dissolution of Mn and the doping elements at the Mn position, thereby obtaining improved cycle performance and / or high-temperature stability, and the gram capacity and compaction density of the second positive electrode active material can also be improved.

[0244] In some embodiments, B includes one or more elements selected from Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb and Ge, and may optionally include one or more elements selected from Zn, Fe, Ti, V, Ni, Co and Mg; C includes one or more elements selected from B (boron), Si, N and S; a is selected from the range of 0.9 to 1.1, x is 0, y is selected from the range of 0.001 to 0.5, z is selected from the range of 0.001 to 0.1, and n is 0.

[0245] By doping specific elements at specific amounts at both the Mn and P sites of the LiMnPO4 compound, rate performance can be improved, the dissolution of Mn and the doping elements at the Mn site can be reduced, the cycle performance and / or high-temperature stability can be improved, and the gram capacity and compaction density of the second positive electrode active material can be increased.

[0246] In some embodiments, the second positive electrode active material includes a core and a shell coating the core, wherein the core includes a compound represented by formula (I) above. The shell includes one or more coating layers. The coating layers have ionic conductivity and / or electronic conductivity. In practice, each coating layer may be completely or partially coated.

[0247] By arranging a coating layer with ionic conductivity and / or electronic conductivity on the surface of the inner core, a second positive electrode active material with a core-shell structure is provided. Applying the second positive electrode active material to the battery can improve the high-temperature cycle performance, cycle stability and high-temperature storage performance of the battery.

[0248] In some embodiments, the shell comprises a coating; optionally, the coating comprises one or more selected from pyrophosphate, phosphate, carbon, doped carbon, oxide, boride, and polymer.

[0249] The above materials can be used to obtain a coating layer with ionic conductivity and / or electronic conductivity, thereby improving the high-temperature cycle performance, cycle stability and high-temperature storage performance of the battery.

[0250] In some embodiments, the shell comprises a first coating layer coating the inner core and a second coating layer coating the first coating layer; optionally, the first coating layer and the second coating layer each independently comprise one or more selected from pyrophosphate, phosphate, carbon, doped carbon, oxide, boride and polymer.

[0251] Using the above materials as the materials for the coating layer and providing two coating layers can further improve the high-temperature cycle performance, cycle stability and high-temperature storage performance of the battery.

[0252] In some embodiments, the first coating layer includes one or more selected from pyrophosphate, phosphate, oxide, and boride, and the second coating layer includes one or more selected from carbon and doped carbon.

[0253] The use of a first coating layer of a specific material and a second coating layer of a specific material can further improve rate performance and further reduce the dissolution of Mn and Mn-doping elements, thereby improving the cycle performance and / or high-temperature stability of the battery.

[0254] In some embodiments, the shell includes a first coating layer coating the inner core, a second coating layer coating the first coating layer, and a third coating layer coating the second coating layer; optionally, the first coating layer, the second coating layer and the third coating layer each independently include one or more selected from pyrophosphate, phosphate, carbon, doped carbon, oxide, boride and polymer.

[0255] Using the above materials as the coating layer material and providing three coating layers can further reduce the dissolution of Mn and Mn-doping elements, and further improve the high-temperature cycle performance, cycle stability and high-temperature storage performance of the battery.

[0256] In some embodiments, the first coating layer includes pyrophosphate, the second coating layer includes one or more selected from phosphates, oxides, and borides, and the third coating layer includes one or more selected from carbon and doped carbon.

[0257] The use of a first coating layer of a specific material, a second coating layer of a specific material, and a third coating layer of a specific material further improves the rate performance, further reduces the dissolution of Mn and Mn-doping elements, thereby improving the cycle performance and / or high-temperature stability of the battery, and further increases the gram capacity and compaction density of the second positive electrode active material.

[0258] In some embodiments, the one or more coating layers each independently comprise one or more selected from the group consisting of pyrophosphate, phosphate, carbon, doped carbon, oxide, boride, and polymer.

[0259] In some embodiments, the pyrophosphate is b (P2O7) c and / or,

[0260] Phosphate is X m (PO4) q and / or,

[0261] The doping element in the doped carbon includes one or more elements selected from Group IIIA, Group VA, Group VIA and Group VIIA; and / or,

[0262] Oxide is M' d O eand / or,

[0263] Boride is Z v B w and / or,

[0264] The polymer includes one or more selected from polysaccharides and their derivatives, and polysiloxanes;

[0265] M, X, and Z each independently comprise one or more elements selected from Group IA, Group IIA, Group IIIA, Group IB, Group IIB, Group IVB, Group VB, Group VIIB, and Group VIII;

[0266] b is selected from the range of 1 to 4, c is selected from the range of 1 to 6; m is selected from the range of 1 to 2, q is selected from the range of 1 to 4;

[0267] M′ comprises one or more elements selected from alkali metals, alkaline earth metals, transition metals, Group IIIA elements, Group IVA elements, lanthanides, and Sb;

[0268] d is greater than 0 and less than or equal to 2, e is greater than 0 and less than or equal to 5;

[0269] v is selected from the range of 1 to 7, and w is selected from the range of 1 to 2.

[0270] By using the above materials as the coating layer, the dissolution of Mn and Mn-doping elements can be further reduced, the gram capacity and compaction density of the second positive electrode active material can be further increased, and the battery's rate performance, high-temperature cycle performance and high-temperature storage performance can be further improved.

[0271] In some embodiments, M, X, and Z each independently comprise one or more elements selected from Li, Fe, Ni, Mg, Co, Cu, Zn, Ti, Ag, Zr, Nb, Mn, and Al; and / or,

[0272] The doping element in the doped carbon includes one or more elements selected from nitrogen, phosphorus, sulfur, boron and fluorine; and / or,

[0273] M′ comprises one or more elements selected from the group consisting of Li, Be, B, Na, Mg, Al, Si, P, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, W, La, and Ce, and may optionally comprise one or more elements selected from the group consisting of Mg, Al, Si, Zn, Zr, and Sn; and / or

[0274] The polysiloxane is selected from one or more of linear polysiloxanes and cyclic polysiloxanes; and / or,

[0275] The polysaccharide is selected from one or more of plant polysaccharides and marine polysaccharides.

[0276] By using the above-mentioned specific material as the coating layer, the dissolution of Mn and Mn-doping elements can be further reduced, and the high-temperature cycle performance and high-temperature storage performance of the battery can be further improved.

[0277] In some embodiments, the second positive active material includes a core and a shell covering the core.

[0278] The core includes Li a Mn 1-y B y P 1-z C z O4, a is selected from the range of 0.9 to 1.1, y is selected from the range of 0.001 to 0.5, z is selected from the range of 0.001 to 0.1, B includes one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge, and C includes one or more elements selected from B (boron), S, Si and N.

[0279] The shell includes a first coating layer coating the core and a second coating layer coating the first coating layer, the first coating layer includes pyrophosphate MP2O7 and phosphate XPO4, M and X each independently include one or more elements selected from Li, Fe, Ni, Mg, Co, Cu, Zn, Ti, Ag, Zr, Nb and Al; the second coating layer contains carbon.

[0280] The second positive electrode active material can have a core-shell structure with two coating layers. The element B doped at the manganese position of the lithium manganese phosphate helps reduce the rate of lattice change during lithium insertion and extraction, improving the structural stability of the second positive electrode active material, significantly reducing manganese dissolution, and lowering oxygen activity on the particle surface. The element C doped at the phosphorus position helps modify the ease of change in the Mn-O bond length, thereby lowering the lithium ion migration barrier, promoting lithium ion migration, and improving the battery's rate performance. The first coating layer of the second positive electrode active material comprises pyrophosphate and phosphate. Since the migration barrier of transition metals in pyrophosphate is relatively high (>1 eV), it can effectively reduce transition metal dissolution. Phosphate has excellent lithium ion conductivity and can reduce the surface impurity lithium content. Furthermore, since the second coating layer is a carbon-containing layer, it can effectively improve the conductivity and desolvation ability of the LiMnPO4. Furthermore, the "barrier" effect of the second coating layer further reduces the migration of manganese ions into the electrolyte and reduces electrolyte corrosion of the second active material. Therefore, by doping lithium manganese phosphate with specific elements and surface coating, the dissolution of Mn during the lithium insertion process can be effectively reduced, while promoting the migration of lithium ions, thereby improving the battery's rate performance, cycle performance and high-temperature performance.

[0281] In some embodiments, the second positive active material includes a core and a shell covering the core.

[0282] The core includes Li a Mn 1-y B y P 1-z C z O4, a is selected from the range of 0.9 to 1.1, y is selected from the range of 0.001 to 0.5, z is selected from the range of 0.001 to 0.1, B includes one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge, and C includes one or more elements selected from B (boron), S, Si and N.

[0283] The shell includes a first covering layer covering the inner core, a second covering layer covering the first covering layer, and a third covering layer covering the second covering layer.

[0284] The first coating layer includes Li pyrophosphate f QP2O7 and / or Q g (P2O7) h , 0≤f≤2, 1≤g≤4, 1≤h≤6, pyrophosphate Li f QP2O7 and / or Q g (P2O7) h Each Q in the above-mentioned ions independently comprises one or more elements selected from the group consisting of Fe, Ni, Mg, Co, Cu, Zn, Ti, Ag, Zr, Nb and Al.

[0285] The second coating layer includes crystalline phosphate XP04, where X includes one or more elements selected from Li, Fe, Ni, Mg, Co, Cu, Zn, Ti, Ag, Zr, Nb and Al.

[0286] The third coating layer includes carbon.

[0287] Therefore, the second positive electrode active material can improve the specific capacity and cycle performance of the battery.

[0288] The second positive electrode active material is a core-shell structure, in which the manganese site and phosphorus site of the inner core are doped with elements B and C respectively, which can not only effectively reduce the dissolution of manganese, thereby reducing the manganese ions migrating to the negative electrode, reducing the electrolyte consumed due to the decomposition of the SEI film, and improving the cycle performance of the battery, but also promote the adjustment of the Mn-O bond, reduce the lithium ion migration barrier, promote lithium ion migration, and improve the battery's rate performance; by coating the inner core with a first coating layer including pyrophosphate, the migration resistance of manganese can be further increased, its dissolution can be reduced, and the surface impurity lithium content and the contact between the inner core and the electrolyte can be reduced, thereby reducing interfacial side reactions, reducing gas production, and improving the high-temperature storage performance and cycle performance of the battery; by further coating with a phosphate coating layer with excellent lithium ion conductivity, the interfacial side reactions on the surface of the second positive electrode active material can be effectively reduced, thereby improving the high-temperature cycle and storage performance of the battery; by further coating with a carbon layer as a third coating layer, the battery's kinetic performance can be further improved. In addition, in the core, the element B doped at the manganese position also helps to reduce the lattice change rate of lithium manganese phosphate during the lithium insertion and extraction process, improves the structural stability of the second positive electrode active material, greatly reduces the dissolution of manganese and reduces the oxygen activity on the particle surface; the element C doped at the phosphorus position also helps to change the difficulty of the Mn-O bond length change, thereby improving electronic conductivity and reducing the lithium ion migration barrier, promoting lithium ion migration, and improving the battery's rate performance.

[0289] Furthermore, maintaining electrical neutrality throughout the core system minimizes defects and impurities in the second cathode active material. If the second cathode active material contains an excess transition metal (e.g., manganese), due to the inherently stable structure of the material system, the excess transition metal is likely to precipitate as a single element or form impurities within the crystal lattice. Maintaining electrical neutrality minimizes these impurities. Furthermore, maintaining electrical neutrality can, in some cases, create lithium vacancies within the material, thereby enhancing the kinetic performance of the second cathode active material.

[0290] In some embodiments, the one or more coating layers in the shell that are farthest from the core each independently comprise one or more selected from polysiloxanes, polysaccharides, and polysaccharide derivatives.

[0291] As a result, the uniformity of the coating can be improved, and the interfacial side reactions caused by high voltage can be effectively blocked, thereby improving the high-temperature cycle performance and high-temperature storage performance of the second positive electrode active material; and the coating layer has good ionic conductivity, which helps to improve the gram capacity of the second positive electrode active material while reducing the heat generation of the battery.

[0292] In some embodiments, the polysiloxane comprises a structural unit represented by formula (i),

[0293] R1 and R2 are independently selected from H, -COOH, -OH, -SH, -CN, -SCN, amino, phosphate, carboxylate, amide, aldehyde, sulfonyl, polyether segment, C1-C20 aliphatic, C1-C20 halogenated aliphatic, C1-C20 heteroaliphatic, C1-C20 halogenated heteroaliphatic, C6-C20 aromatic, C6-C20 halogenated aromatic, C2-C20 heteroaromatic, and C2-C20 halogenated heteroaromatic;

[0294] Optionally, R1 and R2 are independently selected from H, amino, phosphate, polyether segment, C1-C8 alkyl, C1-C8 haloalkyl, C1-C8 heteroalkyl, C1-C8 haloheteroalkyl, C2-C8 alkenyl and C2-C8 haloalkenyl.

[0295] In some embodiments, the polysiloxane further comprises an end-capping group, which includes one or more of the following functional groups: polyether, C1-C8 alkyl, C1-C8 haloalkyl, C1-C8 heteroalkyl, C1-C8 haloheteroalkyl, C2-C8 alkenyl, C2-C8 haloalkenyl, C6-C20 aromatic hydrocarbon, C1-C8 alkoxy, C2-C8 epoxy, hydroxyl, C1-C8 hydroxyalkyl, amino, C1-C8 aminoalkyl, carboxyl, C1-C8 carboxylalkyl.

[0296] In some embodiments, the polysiloxane comprises a polysiloxane selected from polydimethylsiloxane, polydiethylsiloxane, polymethylethylsiloxane, polymethylvinylsiloxane, polyphenylmethylsiloxane, polymethylhydrogensiloxane, carboxyl functionalized polysiloxane, epoxy-terminated polysiloxane, methoxy-terminated polydimethylsiloxane, hydroxypropyl-terminated polydimethylsiloxane, polymethylchloropropylsiloxane, hydroxy-terminated polydimethylsiloxane, polymethyltrifluoropropylsiloxane, perfluorooctylmethylpolysiloxane, aminoethylaminopropyl polydimethylsiloxane, terminal polyether polydimethylsiloxane, side chain aminopropyl polysiloxane, One or more of aminopropyl-terminated polydimethylsiloxane, side chain phosphate-grafted polydimethylsiloxane, side chain polyether-grafted polydimethylsiloxane, 1,3,5,7-octamethylcyclotetrasiloxane, 1,3,5,7-tetrahydro-1,3,5,7-tetramethylcyclotetrasiloxane, cyclopentasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, cyclic polymethylvinylsiloxane, hexadecylcyclooctasiloxane, tetradecamethylcycloheptasiloxane, and cyclic polydimethylsiloxane.

[0297] In some embodiments, the number average molecular weight of polysiloxane, polysaccharide, and polysaccharide derivative is independently less than 300,000, optionally 10,000 to 200,000, more optionally 20,000 to 120,000, and further optionally 400 to 80,000.

[0298] The number average molecular weight of polysiloxane, polysaccharide and polysaccharide derivatives can be measured by methods known in the art, such as gel permeation chromatography (GPC), using a PL-GPC 220 high temperature gel permeation chromatograph.

[0299] In some embodiments, the mass percentage of polar functional groups in the polysiloxane is α, 0≤α<50%, optionally, 5%≤α≤30%.

[0300] The "mass percentage of polar functional groups in the polysiloxane" refers to the mass proportion of polar functional groups in R1, R2, and end-capping groups in the polysiloxane. Polar functional groups include one or more of -COOH, -OH, -SH, -CN, -SCN, amino groups (including -NH2 and -NH-), phosphate groups, carboxylate groups (-COO-), amide groups (-CONH-), aldehyde groups (-CHO), sulfonyl groups (-S(=O)2-), polyether segments, halogen groups, alkoxy groups, and epoxy groups. When the polar functional groups are directly attached to silicon atoms, α represents the mass fraction of these polar functional groups in the polysiloxane. When the polar functional groups are not directly attached to silicon atoms, α represents the sum of the mass fractions of the polar functional groups and the divalent to tetravalent methyl groups (e.g., -CH2, -CH-, -C-, etc.) directly attached to them in the polysiloxane. Here, "divalent to tetravalent methyl groups" refers to the carbon atoms directly attached to the polar functional groups and located between the polar functional groups and the silicon atoms, as well as other non-polar functional groups attached to carbon atoms. For example, in polymethyltrifluoropropylsiloxane, α refers to the mass percentage of -CF3, excluding the ethylene group; in polymethylchloropropylsiloxane, α refers to the mass percentage of -CH2Cl, excluding the ethylene group; and in hydroxypropyl-terminated polydimethylsiloxane, α refers to the mass percentage of -CH2OH. The mass percentage of the polar functional groups in the polysiloxane can be determined by methods known in the art, such as titration (eg, acid-base titration, redox titration, precipitation titration), infrared spectroscopy, and nuclear magnetic resonance spectroscopy.

[0301] In some embodiments, the substituents attached to the sugar units in the polysaccharides and polysaccharide derivatives independently include one or more of the group consisting of the following functional groups: -OH, -COOH and its salts, -R-OH, -SO3H and its salts, -R-OH, -R-SO3H and its salts, sulfate, alkoxy, R represents an alkylene group, optionally representing a C1 to C5 alkylene group.

[0302] Optionally, the substituents attached to the sugar units in the polysaccharide and polysaccharide derivatives each independently include one or more of the group consisting of the following functional groups: -OH, -COOH, -COOLi, -COONa, -COOK, -SO3H, -SO3Li, -SO3Na, -SO3K, -CH2-SO3H, -CH2-SO3Li, -CH2-SO3Na, -CH2-SO3K, methoxy, ethoxy.

[0303] The term "substituents attached to the sugar unit" includes all groups attached to the sugar unit backbone.

[0304] In some embodiments, the polysaccharide comprises one or more selected from pectin, carboxymethyl starch, hydroxypropyl starch, dextrin, cellulose ether, carboxymethyl chitosan, hydroxyethyl cellulose, carboxymethyl cellulose, carboxypropyl methyl cellulose, guar gum, sesbania gum, gum arabic, lithium alginate, sodium alginate, potassium alginate, fucoidan, agar, carrageenan, carrageenan, xanthan gum, and fenugreek gum.

[0305] In some embodiments, the weight percentage of substituents attached to the sugar units in the polysaccharide and polysaccharide derivatives is independently 20% to 85%, and optionally 30% to 78%. The weight percentage of substituents attached to the sugar units in the polysaccharide and polysaccharide derivatives can be determined by methods known in the art, such as titration (e.g., acid-base titration, redox titration, precipitation titration), infrared spectroscopy, and nuclear magnetic resonance spectroscopy.

[0306] In some embodiments, the lattice mismatch between the core material and the shell material is less than 10%, thereby enabling good contact between the core and the shell (or coating) to prevent the shell (or coating) from falling off.

[0307] In some embodiments, based on the weight of the positive electrode active material,

[0308] The manganese content is in the range of 10 wt% to 35 wt%, optionally in the range of 13.3 wt% to 33.2 wt%, more optionally in the range of 15 wt% to 30 wt%, further optionally in the range of 17 wt% to 20 wt%; and / or,

[0309] The phosphorus content is in the range of 12 wt% to 25 wt%, optionally in the range of 15 wt% to 20 wt%, and more optionally in the range of 16.8 wt% to 19.5 wt%; and / or,

[0310] The weight ratio of manganese element to phosphorus element ranges from 0.71 to 1.85, optionally from 0.90 to 1.25, and more preferably from 0.95 to 1.20.

[0311] In the case where manganese is contained only in the core of the second positive electrode active material, the content of manganese may correspond to that of the core.

[0312] Limiting the manganese content within the above range can further improve the stability and density of the second positive electrode active material, thereby improving the battery's cycling, storage, and compaction performance; and can maintain a higher voltage platform, thereby improving the battery's energy density.

[0313] Limiting the phosphorus content within the above range can effectively reduce the influence of small polaron conductivity on the conductivity of the second positive electrode active material, further improve the stability of the lattice structure, and thus enhance the overall stability of the second positive electrode active material.

[0314] Limiting the weight ratio of manganese to phosphorus within the above range can further reduce manganese dissolution, improve the stability and gram capacity of the second positive electrode active material, and improve the cycle performance and storage performance of the battery; it can also reduce impurities, enable the second positive electrode active material to maintain a higher discharge voltage platform, and enable the battery to have a high energy density.

[0315] Manganese and phosphorus can be measured using conventional techniques in the art. Specifically, the following method is used to determine the manganese and phosphorus contents: the material is dissolved in dilute hydrochloric acid (concentration 10-30%), the content of each element in the solution is measured using ICP, and then the manganese content is measured and converted to obtain its weight percentage.

[0316] In some embodiments, the surface of the second positive electrode active material is coated with one or more of carbon and doped carbon; alternatively, the surface of the second positive electrode active material is coated with carbon, thereby improving the conductivity of the second positive electrode active material.

[0317] In some embodiments, the doping element in the doped carbon layer includes one or more elements selected from nitrogen, phosphorus, sulfur, boron, and fluorine, so as to facilitate control of the properties of the doped carbon layer.

[0318] In some embodiments, the coating amount of the shell (which is only one coating layer) is 0.1 wt % to 6 wt % based on the weight of the core. The coating amount of the coating layer is preferably within the above range to fully coat the core and further improve the kinetic performance of the battery without sacrificing the gram capacity of the second positive electrode active material.

[0319] In some embodiments, the coating amount of the first coating layer is greater than 0 and less than or equal to 7 weight %, optionally greater than 0 and less than or equal to 6 weight %, more optionally greater than 0 and less than or equal to 5.5 weight % or 4-5.6 weight %, further optionally greater than 0 and less than or equal to 2 weight %, based on the weight of the kernel; and / or,

[0320] The coating amount of the second coating layer is greater than 0 and less than or equal to 6 weight%, optionally greater than 0 and less than or equal to 5.5 weight%, more optionally 2-4 weight% or 3-5 weight%, based on the weight of the kernel; and / or,

[0321] The coating amount of the third coating layer is greater than 0 and less than or equal to 6 wt %, optionally greater than 0 and less than or equal to 5.5 wt %, and more optionally greater than 0 and less than or equal to 2 wt %, based on the weight of the core.

[0322] In some embodiments, the shell further includes a fourth cladding layer covering the third cladding layer and a fifth cladding layer covering the fourth cladding layer.

[0323] The coating amounts of the fourth coating layer and the fifth coating layer are each independently 0.01 to 10 wt %, optionally 0.05 to 10 wt %, more optionally 0.1 to 5 wt %, further 0.1 to 2 wt %, based on the weight of the core.

[0324] In the second positive electrode active material with a core-shell structure of the present application, the coating amount of each coating layer is preferably within the above range, thereby being able to fully coat the core and further improve the battery's kinetic performance without sacrificing the gram capacity of the second positive electrode active material.

[0325] In some embodiments, the shell is located on 40% to 90% of the surface of the core, and optionally 60% to 80% of the surface, thereby fully covering the core and improving the dynamic performance of the battery.

[0326] In some embodiments, the shell (which is just one coating layer) has a thickness of 1-15 nm.

[0327] In some embodiments, the thickness of the first coating layer is 1-10 nm, optionally 2-10 nm; and / or,

[0328] The thickness of the second coating layer is 2-25 nm, optionally 2-15 nm, more optionally 3-15 nm; and / or,

[0329] The thickness of the third cladding layer is 2-25 nm, and can be optionally 5-25 nm.

[0330] In some embodiments, the thickness of the first cladding layer can be about 2 nm, about 3 nm, about 4 nm, about 5 nm, about 6 nm, about 7 nm, about 8 nm, about 9 nm, or about 10 nm, or any range thereof.

[0331] In some embodiments, the thickness of the second coating layer may be about 2 nm, about 3 nm, about 4 nm, about 5 nm, about 6 nm, about 7 nm, about 8 nm, about 9 nm, about 10 nm, about 11 nm, about 12 nm, about 13 nm, about 14 nm, about 15 nm, or within any range of any of the above values.

[0332] In some embodiments, the thickness of the third coating layer may be about 2 nm, about 3 nm, about 4 nm, about 5 nm, about 6 nm, about 7 nm, about 8 nm, about 9 nm, about 10 nm, about 11 nm, about 12 nm, about 13 nm, about 14 nm, about 15 nm, about 16 nm, about 17 nm, about 18 nm, about 19 nm, about 20 nm, about 21 nm, about 22 nm, about 23 nm, about 24 nm or about 25 nm, or within any range of any of the above values.

[0333] The first coating layer has a thickness within the above range, which can further reduce the adverse effects on the kinetic properties of the second positive electrode active material.

[0334] The second coating layer has the above-mentioned thickness range, so that the surface structure of the second coating layer is stable and the side reaction with the electrolyte is small, thereby effectively reducing the interface side reaction and improving the high temperature performance of the battery.

[0335] The third coating layer has the above-mentioned thickness range, which can enhance the electrical conductivity of the second positive electrode active material and improve the compaction density of the positive electrode sheet prepared using the second positive electrode active material.

[0336] The thickness test of the coating layer is mainly carried out by FIB. The specific method may include the following steps: randomly selecting a single particle from the second positive electrode active material powder to be tested, cutting a thin slice with a thickness of about 100nm from the middle position or near the middle position of the selected particle, and then performing TEM testing on the thin slice to measure the thickness of the coating layer, measuring 3-5 positions and taking the average value.

[0337] In some embodiments, the one or more coating layers each independently include one or more selected from pyrophosphate, phosphate, and oxide, and the one or more selected from pyrophosphate, phosphate, and oxide are crystalline.

[0338] Optionally, the crystallinity of the pyrophosphate, phosphate, and oxide are each independently from 10% to 100%, more preferably from 50% to 100%.

[0339] Herein, crystalline means a crystallinity of 50% or more, i.e., 50%-100%. That is, when the crystalline pyrophosphate and crystalline phosphate of the present application appear, it means a crystallinity of 50% to 100%.

[0340] Pyrophosphate and phosphate with a certain degree of crystallinity are not only conducive to giving full play to the pyrophosphate coating layer's ability to reduce manganese dissolution and the phosphate coating layer's excellent lithium ion conductivity and the function of reducing interface side reactions, but also enable the pyrophosphate coating layer and the phosphate coating layer to better lattice match, thereby achieving a close bond between the coating layers.

[0341] It should be noted that the crystallinity can be adjusted, for example, by adjusting the process conditions of the sintering process, such as sintering temperature, sintering time, etc. The crystallinity can be measured by methods known in the art, such as X-ray diffraction, density method, infrared spectroscopy, differential scanning calorimetry, and nuclear magnetic resonance absorption method. A specific method for testing the crystallinity of the second positive electrode active material by X-ray diffraction method may include the following steps:

[0342] Take a certain amount of the second positive electrode active material powder and measure the total scattering intensity by X-ray. It is the sum of the scattering intensities of the entire space matter and is only related to the intensity of the primary rays, the chemical structure of the second positive electrode active material powder, and the total number of electrons participating in the diffraction, that is, the mass, but has nothing to do with the order state of the sample; then separate the crystalline scattering and the non-crystalline scattering from the diffraction pattern, and the crystallinity is the ratio of the scattering of the crystalline part to the total scattering intensity.

[0343] In some embodiments, in the shell, the weight ratio of the pyrophosphate to the phosphate, and the weight ratio of the pyrophosphate to the oxide, are each independently 1:3 to 3:1, and may be 1:3 to 1:1. Thus, by having the pyrophosphate to the phosphate or the pyrophosphate to the oxide in a suitable weight ratio range, manganese dissolution can be effectively reduced, the surface lithium content can be effectively reduced, and interfacial side reactions can be reduced, thereby improving the high-temperature storage performance and high-temperature cycling performance of the battery.

[0344] In some embodiments, one or more coating layers independently include carbon, and the carbon is a mixture of SP2 carbon and SP3 carbon. Optionally, the molar ratio of SP2 carbon to SP3 carbon in the carbon is any value in the range of 0.07-13, more preferably any value in the range of 0.1-10, and further preferably any value in the range of 2.0-3.0.

[0345] In some embodiments, the molar ratio of sp2 carbon to sp3 carbon can be about 0.1, about 0.2, about 0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, or about 10, or any range thereof.

[0346] In this application, "about" a numerical value represents a range, which means a range of ±10% of the numerical value.

[0347] By selecting the carbon morphology in the carbon coating, the overall electrical performance of the battery is improved. Specifically, by using a mixture of SP2 carbon and SP3 carbon and limiting the ratio of SP2 carbon to SP3 carbon to a certain range, the following situations can be avoided: if the carbon in the coating is all amorphous SP3, the conductivity is poor; if it is all graphitized SP2, although the conductivity is good, there are few lithium ion pathways, which is not conducive to lithium intercalation and deintercalation. In addition, limiting the molar ratio of SP2 carbon to SP3 carbon to the above range can achieve good conductivity and promote the transport of lithium ions, which is beneficial to the realization of battery functions and its cycle performance.

[0348] The mixing ratio of the SP2 and SP3 carbon forms can be controlled by sintering conditions, such as temperature and time. The molar ratio of SP2 to SP3 carbon can be determined by Raman spectroscopy. The Raman spectrum is separated to obtain the peak intensity of the SP3 carbon form (Id / Ig), where Id represents the peak intensity of the SP3 carbon form and Ig represents the peak intensity of the SP2 carbon form. This allows the molar ratio of the two to be determined.

[0349] In some embodiments, one or more coating layers independently include doped carbon, and the weight content of the doping element in the doped carbon is less than 30%; alternatively, the weight content of the doping element in the doped carbon is less than 20%. The doping element within the above content range can not only fully improve the conductivity of the pure carbon layer, but also effectively avoid excessive surface activity caused by excessive doping of the doping element, thereby effectively controlling interfacial side reactions caused by excessive doping of the coating layer.

[0350] In some embodiments, one or more coating layers each independently include doped carbon, wherein the doped carbon

[0351] The doping element is nitrogen and / or sulfur, and the mass content of the doping element in the doped carbon is 1% to 15%; or,

[0352] The doping element is phosphorus, boron and / or fluorine, and the mass content of the doping element in the doped carbon is 0.5% to 5%;

[0353] Optionally, the doping element is nitrogen, phosphorus, sulfur, boron or fluorine.

[0354] Since nitrogen atoms and sulfur atoms are closer in atomic radius to carbon atoms and are less likely to destroy the carbon skeleton, when the doping amount of nitrogen atoms and sulfur atoms is within the above relatively wide range, the conductivity of the doped carbon layer can be fully exerted, and the lithium ion transport and lithium ion desolvation capabilities can be promoted.

[0355] Since the atomic radius of phosphorus atoms, boron atoms and / or fluorine atoms is different from that of carbon atoms, excessive doping can easily destroy the carbon skeleton. Therefore, when the doping amount of phosphorus atoms, boron atoms and / or fluorine atoms is within the above-mentioned relatively small range, it can not only fully exert the conductivity of the doped carbon layer, but also promote lithium ion transmission and lithium ion desolvation capabilities.

[0356] In some embodiments, the one or more coating layers independently comprise pyrophosphate, the interplanar spacing of the pyrophosphate is in the range of 0.293-0.470 nm, optionally 0.297-0.462 nm or 0.293-0.326 nm, more optionally 0.300-0.310 nm, and the angle of the crystal direction (111) is in the range of 18.00°-32.57°, optionally 18.00°-32.00° or 26.41°-32.57°, more optionally 19.211°-30.846°, further optionally 29.00°-30.00°; and / or,

[0357] The one or more coating layers independently include phosphate, the interplanar spacing of the phosphate is in the range of 0.244-0.425 nm, optionally 0.345-0.358 nm, and the angle of the crystal orientation (111) is in the range of 20.00°-37.00°, optionally 24.25°-26.45°;

[0358] Optionally, the first coating layer or the second coating layer comprises phosphate.

[0359] The first and second coating layers of the second positive electrode active material are both crystalline, with their interplanar spacing and angles falling within the aforementioned ranges. This effectively reduces impurity phases in the coating layers, thereby improving the material's specific capacity, cycle performance, and rate capability.

[0360] In some embodiments, the lattice change rate of the second positive electrode active material before and after complete deintercalation of lithium is less than 50%, optionally less than 9.8%, more optionally less than 8.1%, further optionally less than 7.5%, further optionally less than 6%, further optionally less than 4%, further optionally less than 3.8%, and further optionally less than 2.0-3.8%.

[0361] By reducing the lattice change rate, Li ion transport can be facilitated, that is, the mobility of Li ions in the second positive electrode active material is stronger, which is beneficial to improving the rate performance of the battery. The lattice change rate can be measured by methods known in the art, such as X-ray diffraction (XRD).

[0362] In some embodiments, the Li / Mn antisite defect concentration of the second positive electrode active material is less than 5.3%, optionally less than 5.1%, more optionally less than 4%, further optionally less than 2.2%, further optionally less than 2%, further optionally less than 1.5%-2.2% or less than 0.5%.

[0363] The so-called Li / Mn antisite defect refers to the Li + With Mn 2+ The positions of Li / Mn are interchanged. The Li / Mn antisite defect concentration refers to the concentration of Li / Mn in the second positive electrode active material. 2+ Li exchange occurs + Occupy + The percentage of total antisite defect Mn 2+ Will hinder Li + The transport of Li / Mn antisite defects can improve the specific capacity and rate performance of the second positive electrode active material by reducing the concentration of Li / Mn antisite defects. The concentration of Li / Mn antisite defects can be measured by methods known in the art, such as XRD.

[0364] In some embodiments, the surface oxygen valence state of the second positive electrode active material is below -1.55, optionally below -1.82, more optionally below -1.88, further optionally below -1.90 or -1.98 to -1.88, further optionally -1.98 to -1.89, further optionally -1.98 to -1.90.

[0365] By reducing the surface oxygen valence state, the interfacial side reactions between the second cathode active material and the electrolyte can be reduced, thereby improving the cycle performance and high temperature stability of the battery. The surface oxygen valence state can be measured by methods known in the art, such as electron energy loss spectroscopy (EELS).

[0366] In some embodiments, the first positive electrode active material may include one or more of a layered oxide material, a lithium-rich oxide material, a spinel-type lithium manganate material, and modified compounds thereof, and the modification method includes doping and / or surface coating modification.

[0367] The first positive electrode active material has a high compaction density, but this is costly, results in numerous side reactions during battery use, and has a less stable crystal structure than the first positive electrode material. By properly combining the second positive electrode active material with the first positive electrode active material, the actual bulk density of the positive electrode active material composition can be increased, as can the compaction density and compaction density efficiency of the positive electrode sheet. This allows the battery to achieve both high energy density, low cost, and a long service life.

[0368] In some embodiments, the first positive electrode active material includes a compound represented by formula (II), Lia1 A 1 b1 Ni c1 Co d1 B 1 e1 C 1 f1 O 2-g1 D 1 g1 (II)

[0369] A 1 including one or more elements selected from Group IA, Group IIA, Group VIII, Group VIB, and Group IIB; B 1 including Mn and / or Al; C 1 comprising one or more elements selected from Group IA, Group IIA, Group IIIA, Group IVA, Group VA, Group VIA, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, and Group VIII; D 1 Includes one or more elements selected from Group VIA and Group VIIA; a1 is selected from the range of 0.8 to 1.2; b1 is selected from the range of 0 to 0.2; c1 is selected from the range of 0 to 1; d1 is selected from the range of 0 to 1; e1 is selected from the range of 0 to 1; f1 is selected from the range of 0 to 0.1; g1 is selected from the range of 0 to 0.1; and c1+d1+e1+f1=1.

[0370] In some embodiments, A 1 including one or more elements selected from Na, K, Mg, Rb, Zn, and Zr; and / or,

[0371] C 1 including one or more elements selected from the group consisting of Al, Mg, Ca, Na, Ti, W, Zr, Sr, Cr, Fe, Zn, Ba, Mo, V, Ce, Nb, Sb, Ta, Ge, Nb, Sc, Ba, B, S, and Y, and optionally including one or more elements selected from the group consisting of Al, Ti, Zr, Nb, Sr, Sc, Sb, Y, Ba, and B; and / or,

[0372] D 1 comprising one or more elements selected from N, S, F, Cl and Br, optionally including S and / or F; and / or,

[0373] a1 is selected from the range of 0.9 to 1.1; and / or,

[0374] b1 is selected from the range of 0 to 0.1; and / or,

[0375] c1 is selected from the range of 0.314 to 0.990, and may be selected from the range of 0.500 to 0.990; and / or,

[0376] d1 is selected from the range of 0 to 0.320, and optionally from the range of 0 to 0.150; and / or,

[0377] e1 is selected from the range of 0.001 to 0.450, and can be optionally selected from the range of 0.005 to 0.4; and / or,

[0378] f1 is selected from the range of 0.001 to 0.1, and may be selected from the range of 0.001 to 0.05; and / or,

[0379] g1 is selected from the range of 0 to 0.01, and can be optionally selected from the range of 0.01 to 0.05.

[0380] In some embodiments, the first positive electrode active material includes a core and a shell covering the core, wherein the core includes the compound represented by formula (II) above; and the shell includes one or more coating layers. Each coating layer has ionic conductivity and / or electronic conductivity.

[0381] In some embodiments, one or more coating layers in the shell of the compound represented by formula (II) independently include one or more selected from phosphate, pyrophosphate, carbon, doped carbon, oxide, and fast ion conductor, and may optionally include one or more selected from phosphate, pyrophosphate, and oxide.

[0382] In some embodiments, the shell encapsulating the compound represented by formula (II) comprises a coating layer; optionally, the coating layer comprises one or more selected from phosphates, pyrophosphates, and oxides.

[0383] In some embodiments, the shell of the compound represented by formula (II) includes a first coating layer coating the inner core and a second coating layer coating the first coating layer; optionally, the first coating layer and the second coating layer each independently include one or more selected from phosphates, pyrophosphates, and oxides; more optionally, the first coating layer includes one or more selected from phosphates and oxides, and the second coating layer includes one or more selected from pyrophosphates and oxides.

[0384] In some embodiments, the coating amount of the shell coating the compound represented by formula (II) is 0.005 wt % to 1 wt %, optionally 0.01 wt % to 0.5 wt %, based on the weight of the core.

[0385] In some embodiments, the thickness of the shell encapsulating the compound represented by formula (II) is 2 nm to 200 nm, optionally 5 nm to 50 nm.

[0386] In some embodiments, the first positive electrode active material includes a compound represented by formula (III), Li 1+p1 A 2q1 B 2 r1 O s1 (III)

[0387] 0.05 ≤ p1 < 0.2, 0.10 < q1 ≤ 0.95, 0 ≤ r1 ≤ 0.2, and 2 ≤ s1 < 3, A 2 comprises one or more elements selected from Co, Ni, Mn, and Al; B 2 comprises one or more elements selected from Mg, Ti, Cr, Zr, Nb, Fe, Mo, Cu, Sb, V, P, and F.

[0388] In some embodiments, the first positive electrode active material comprises a core and a shell coating the core, the core comprises a compound represented by formula (III); the shell comprises one or more coating layers; each coating layer has ionic conductivity and / or electronic conductivity.

[0389] In some embodiments, one or more coating layers of the shell coating the compound represented by formula (III) independently comprise one or more selected from phosphates, pyrophosphates, solid electrolytes, conductive polymers, materials capable of reversibly intercalating and deintercalating lithium ions.

[0390] In some embodiments, the coating amount of the shell coating the compound represented by formula (III) is 0.1 wt% to 5 wt%, optionally 0.5 wt% to 2 wt%, based on the weight of the core.

[0391] In some embodiments, the thickness of the shell coating the compound represented by formula (III) is 2 nm to 200 nm, optionally 5 nm to 50 nm.

[0392] In some embodiments, the first positive electrode active material comprises a compound represented by formula (IV), LiMn t1 A 3 2-t1 O4 (IV)

[0393] t1 is selected from the range of 0 to 2, A 3 comprises one or more elements selected from Ni, Cr, Al, Zr, V, Ti, Mo, Ru, Mg, Nb, Ba, Si, P, W, Co, Cu, and Zn.

[0394] In some embodiments, the third positive electrode active material comprises a core and a shell coating the core, the core comprises a compound represented by formula (IV); the shell comprises one or more coating layers; each coating layer has ionic conductivity and / or electronic conductivity.

[0395] In some embodiments, the one or more coating layers of the shell of the compound shown in the coating formula (IV) each independently include one or more materials selected from phosphates, pyrophosphates, solid electrolytes, conductive polymers, and materials capable of reversibly intercalating and deintercalating lithium ions. Alternatively, the one or more coating layers of the shell of the compound shown in the coating formula (IV) each independently include one or more materials selected from lithium boron oxide glass, carbonates, carbon metal composites, metal oxides (such as MgO, Al2O3, LiAlO2), silicon oxide, KMnF3 and LiCoO2, acetylacetone, and conductive polymers.

[0396] In some embodiments, the coating amount of the shell coating the compound represented by formula (IV) is 0.1 wt % to 3 wt %, optionally 0.2 wt % to 1.5 wt %, based on the weight of the core.

[0397] In some embodiments, the thickness of the shell encapsulating the compound represented by formula (IV) is 2 nm to 200 nm, optionally 5 nm to 50 nm.

[0398] The first positive electrode active material and the second positive electrode active material can be prepared by a sintering method. The shells of the first positive electrode active material and the second positive electrode active material can be prepared by a liquid phase coating method.

[0399] [Positive electrode]

[0400] The positive electrode sheet provided in the embodiments of the present application includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, wherein the positive electrode film layer includes the aforementioned positive electrode active material composition. The positive electrode current collector has two surfaces that oppose each other in the thickness direction thereof, and the positive electrode film layer is disposed on either or both of the two opposing surfaces of the positive electrode current collector.

[0401] In some embodiments, the content of the positive electrode active material composition in the positive electrode film layer is 50-99.5 wt %, optionally 90-99.5 wt %, or 95-99.5 wt %, based on the total weight of the positive electrode film layer.

[0402] In some embodiments, the positive electrode sheet satisfies 0.23≤(h1×N1) / (CW / PD / 10000)<1, optionally, 0.63≤(h1×N1) / (CW / PD / 10000)≤0.87, where h1 represents the average size of the first positive electrode active material particles along the thickness direction of the positive electrode film layer, in μm; N1 represents the number of first positive electrode active material particles accommodated in the positive electrode film layer along the thickness direction of the positive electrode film layer; CW represents the surface density of the positive electrode film layer, in g / cm 2 PD represents the compaction density of the positive electrode film, in g / cm 3 This allows the battery to have a long cycle life.

[0403] The above parameters (such as h1, N1, CW, PD) all refer to the parameters of the positive electrode film layer on a single side of the positive electrode current collector.

[0404] In some embodiments, along the thickness direction of the positive electrode film layer, the average size h1 of the first positive electrode active material particles is 0.5-20 μm, and optionally 2.8-9.2 μm.

[0405] In some embodiments, along the thickness direction of the positive electrode film layer, the number N1 of the first positive electrode active material particles contained in the positive electrode film layer is 5-25, optionally 6-20, or optionally 6-18.

[0406] The number N1 of the first positive electrode active material particles and the average size h1 of the first positive electrode active material particles along the thickness direction of the positive electrode film layer can be measured using an ion polishing cross-section method. For example, the measurement can be performed as follows: using the ion polishing cross-section method, a cross section of the positive electrode sheet is taken. Under a scanning electron microscope, at least five reference lines perpendicular to the current collector are taken. The number of first positive electrode active material particles along each reference line is counted, and the average value is taken to be the number N1 of the first positive electrode active material particles along the thickness direction of the positive electrode film layer. The particle size of the first positive electrode active material particles along each reference line is counted, and the average value is taken to be the average size h1 of the first positive electrode active material particles along the thickness direction of the positive electrode film layer.

[0407] In some embodiments, the surface density CW of the positive electrode film layer is 0.01-0.05 g / cm 2 , optional 0.015-0.035g / cm 2 .

[0408] In some embodiments, the compaction density PD of the positive electrode film layer is 1.8-3.6 g / cm 3 , optional 2.0-3.4g / cm 3 .

[0409] The surface density and compaction density of the positive electrode film layer are well known in the art and can be tested by methods known in the art. The compaction density of the positive electrode film layer = the surface density of the positive electrode film layer / the thickness of the positive electrode film layer. The thickness of the positive electrode film layer is well known in the art and can be tested by methods known in the art, such as using a micrometer (such as Mitutoyo 293-100, with an accuracy of 0.1 μm). The surface density of the positive electrode film layer is well known in the art and can be tested by methods known in the art. For example, a single-sided coated and cold-pressed positive electrode sheet can be taken (if it is a double-sided coated positive electrode sheet, the positive electrode film layer on one side can be wiped off first), punched into small discs with an area of ​​S1, weighed, and recorded as M1. Then wipe off the positive electrode film layer of the weighed positive electrode sheet, weigh the weight of the positive electrode current collector, and record it as M0. The surface density of the positive electrode sheet = (M1-M0) / S1.

[0410] In some embodiments, the positive electrode sheet further satisfies 0.5≤α1+(PD / ρ1)≤1.5, where α1 represents the porosity of the positive electrode film layer. This can enable the battery to have a long cycle life and / or high energy density.

[0411] In some embodiments, the porosity α1 of the positive electrode film layer is 0.28-0.50, and can be optionally 0.30-0.39.

[0412] The porosity of the positive electrode film layer is a well-known meaning in the art and can be measured using methods known in the art. An exemplary test method is as follows: take a single-sided coated and cold-pressed positive electrode sheet (if it is a double-sided coated positive electrode sheet, the positive electrode film layer on one side can be wiped off first), punch it into small disc samples of a certain area, and calculate the apparent volume V1 of the positive electrode sheet, V1 = S × H × A, S represents the sample area, H represents the sample thickness, and A represents the number of samples; refer to GB / T24586-2009, use an inert gas (such as helium) as the medium, adopt a gas replacement method, and use a true density tester to measure the true volume V2 of the positive electrode sheet. The porosity of the positive electrode film layer = (V1-V2) / V1×100%. The testing instrument can be a Micromeritics AccuPyc II 1340 true density tester.

[0413] In some embodiments, based on the total mass of the positive electrode active material composition, the mass proportion of the first positive electrode active material is recorded as W1, the mass proportion of the second positive electrode active material is recorded as W2, the powder compaction density of the first positive electrode active material at 30000N is recorded as P1, and the powder compaction density of the second positive electrode active material at 30000N is recorded as P2, both in g / cm 3, then PD / [(P1×W1)+(P2×W2)] is greater than 89%, and can optionally be greater than 92%. (P1×W1)+(P2×W2) can represent the theoretical powder compaction density of the positive electrode active material composition, and PD / [(P1×W1)+(P2×W2)] can represent the compaction density efficiency of the positive electrode sheet.

[0414] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0415] In some embodiments, the positive electrode film layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0416] In some embodiments, the positive electrode film layer may further include a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0417] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0418] [Negative electrode]

[0419] In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0420] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0421] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base material. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0422] In some embodiments, the negative electrode active material may be a material known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may include at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may include at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0423] In some embodiments, the negative electrode film layer may further optionally include a binder. As an example, the binder may include at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0424] In some embodiments, the negative electrode film layer may further include a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0425] In some embodiments, the negative electrode film layer may optionally further include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC)).

[0426] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0427] In some embodiments, the negative electrode plate may not include a negative electrode active material capable of intercalating and deintercalating lithium ions. For example, the negative electrode plate may include a lithium plate or a lithium alloy plate; or, the negative electrode plate may include a three-dimensional skeleton layer in a network or foam form; or, the negative electrode plate may include a negative electrode current collector and a lithium-containing layer disposed on at least one surface of the negative electrode current collector.

[0428] [Electrolytes]

[0429] The electrolyte conducts ions between the positive and negative electrodes. This application does not specify the type of electrolyte, and the electrolyte can be selected based on the needs. For example, the electrolyte can be liquid, gel, or solid.

[0430] In some embodiments, the electrolyte is liquid (also known as an electrolyte solution) and includes an electrolyte salt and a solvent.

[0431] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0432] In some embodiments, the solvent may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0433] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0434] [Isolation film]

[0435] In some embodiments, the battery cell further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0436] In some embodiments, the separator includes a porous substrate. The porous substrate may be made of at least one of fiberglass, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, polyester, and polyimide. The porous substrate may be a single-layer film or a multi-layer composite film, without particular limitation. When the porous substrate is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0437] In some embodiments, the isolation membrane may further include a coating layer located on at least one surface of the porous substrate. Optionally, the coating layer includes one or more of inorganic heat-resistant particles and organic heat-resistant particles.

[0438] The present application also provides an electrical device, which includes at least one of the battery cells, battery modules, or battery packs provided in the present application. The battery cells, battery modules, or battery packs can be used as power sources for the electrical device, or as energy storage units for the electrical device. The electrical device may include, but is not limited to, mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc.

[0439] As an electrical device, a battery cell, battery module or battery pack can be selected according to its usage requirements.

[0440] Figure 6 shows an example of an electric device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of this device, a battery pack or battery module can be used.

[0441] As another example, an electric device may be a mobile phone, a tablet computer, a laptop computer, etc. Such an electric device is usually required to be lightweight and thin, and may use a battery cell as a power source.

[0442] Example

[0443] The following examples describe the present disclosure in more detail. These examples are intended to be illustrative only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing. The instruments used in the examples are commercially available.

[0444] The batteries of Examples 1-14 and Comparative Examples 1-6 were prepared according to the following method.

[0445] Preparation of positive electrode

[0446] The first and second positive electrode active materials shown in Table 1, the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) were thoroughly stirred and mixed in an appropriate amount of solvent NMP at a mass ratio of 96:2:2 to form a uniform positive electrode slurry; the positive electrode slurry was evenly coated on both surfaces of the positive electrode current collector aluminum foil, and after drying and cold pressing, a positive electrode sheet was obtained. The surface density CW of the positive electrode film layer on one side of the positive electrode current collector was 0.0196 g / cm 2 .

[0447] Preparation of negative electrode sheet

[0448] The negative electrode active material graphite, binder styrene-butadiene rubber (SBR), thickener sodium carboxymethyl cellulose (CMC-Na), and conductive agent carbon black (Super P) are fully stirred and mixed in an appropriate amount of solvent deionized water at a mass ratio of 96.2:1.8:1.2:0.8 to form a uniform negative electrode slurry; the negative electrode slurry is evenly coated on the surface of the negative electrode current collector copper foil, and after drying and cold pressing, a negative electrode sheet is obtained.

[0449] Preparation of electrolyte

[0450] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an organic solvent, and then fully dried LiPF6 is dissolved in the above organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0451] Preparation of isolation membrane

[0452] A porous polyethylene film was used as the separator.

[0453] Battery preparation

[0454] The positive electrode sheet, separator, and negative electrode sheet are stacked and wound in sequence to obtain an electrode assembly; the electrode assembly is placed in an outer package, dried, and then injected with electrolyte. After vacuum packaging, standing, formation, shaping and other processes, a battery is obtained.

[0455] Test section

[0456] At 25°C, charge the battery at a constant current of 0.5C to 4.2V. Continue charging at a constant voltage until the current reaches 0.05C. At this point, the battery is fully charged. Record the charge capacity at this point, which is the first cycle charge capacity. After the battery rests for 5 minutes, discharge it at a constant current of 0.5C to 2.8V. This constitutes one cycle of charge and discharge. Record the discharge capacity at this point, which is the first cycle discharge capacity. Repeat the battery charge and discharge test as described above, recording the discharge capacity after each cycle until the battery's discharge capacity decays to 80% of the first cycle discharge capacity. The number of cycles at this point is used to characterize the battery's cycling performance. The higher the number of cycles, the longer the battery's service life.

[0457] In Table 1 and Table 2, NCM811 refers to LiNi 0.8 Co 0.1 Mn 0.1 O2, LCO refers to LiCoO2, LMFP refers to carbon-coated LiMn 0.60 Fe 0.40 PO4.

[0458] The NCM811, LCO and LMFP of each embodiment and comparative example can be commercially purchased, and then a variety of commercially available materials are screened by selecting a suitable sieve and then mixed in a predetermined proportion to obtain the obtained materials; or, the commercially available materials are first ball-milled to a suitable size, and then screened by selecting a suitable sieve, and then mixed in a predetermined proportion to obtain the obtained materials; or, a sintering method is adopted and the sintering process parameters (such as sintering temperature, sintering time, sintering atmosphere, etc.) and grinding parameters (such as grinding speed, grinding time, etc.) are adjusted, and a suitable sieve is selected for screening to obtain the obtained materials; or, a variety of materials of different sizes prepared by the sintering method are mixed in a predetermined proportion to obtain the obtained materials.

[0459] The ratios of the major axis length to the minor axis length of the first positive electrode active material and the second positive electrode active material in Table 1 are both between 1 and 1.4, which can be obtained by adjusting grinding parameters (such as grinding speed, grinding time, etc.).

[0460] Dv10 (1) 、Dv50 (1) is the volume distribution particle size of the first positive electrode active material, ρ1 is the true density of the first positive electrode active material, and P1 is the powder compaction density of the first positive electrode active material under 30000N.

[0461] Dv50 (2) is the volume distribution particle size of the second positive electrode active material, ρ2 is the true density of the second positive electrode active material, and P2 is the powder compaction density of the second positive electrode active material under 30000N.

[0462] W1 is the mass ratio of the first positive electrode active material based on the total mass of the positive electrode active material composition.

[0463] W2 is the mass ratio of the second positive electrode active material based on the total mass of the positive electrode active material composition, and W2=ρ2 / [(β×ρ1)+ρ2].

[0464] In the particle size distribution curve of the positive electrode active material composition, the integrated area of ​​peak I represents the integrated area of ​​the peak with the smallest volume distribution particle size, and the integrated area of ​​peak II represents the total integrated area of ​​peaks other than peak I.

[0465] h1 represents the average size of the first positive electrode active material particles along the thickness direction of the positive electrode film layer.

[0466] N1 represents the number of first positive electrode active material particles contained in the positive electrode film layer along the thickness direction of the positive electrode film layer.

[0467] PD represents the compacted density of the positive electrode film.

[0468] α1 represents the porosity of the positive electrode film layer.

[0469] The compaction density efficiency of the positive electrode sheet = PD / [(P1×W1)+(P2×W2)].

[0470] The above parameters can be measured according to the test methods given above.

[0471] From Table 1 and Table 2, it can be seen that when the first positive electrode active material and the second positive electrode active material simultaneously meet Dv10 (1) / Dv50 (2) >1, Dv50 (1) / Dv50 (2) When ≥1.4 and -2.0≤1-[(ρ2×W2) / (ρ1×W1)]≤0.98, the positive electrode sheet using the positive electrode active material composition can have both high compaction density and high compaction density efficiency, and the battery using the positive electrode active material composition can have high energy density and long service life.

[0472] The preparation methods of the batteries of Examples 15-19 are similar to that of Example 5, except that the types of the second positive electrode active materials are different, as detailed in Table 3. The test results are shown in Table 4.

[0473] The second positive electrode active materials of Examples 15-19 can be obtained by sintering by adjusting sintering process parameters (e.g., sintering temperature, sintering time, sintering atmosphere, etc.), grinding parameters (e.g., grinding speed, grinding time, etc.), and selecting a suitable sieve for screening. Alternatively, they can be obtained by mixing multiple materials of different particle sizes prepared by sintering in a predetermined ratio. The ratio of the major axis length to the minor axis length of the second positive electrode active materials used in Examples 15-19 is between 1 and 1.4.

[0474] From Tables 3 and 4, it can be seen that by doping specific elements at the Mn position of LiMnPO4 and further at the Li position, P position and / or O position, it is possible to dope specific elements at the Mn position and P position of LiMnPO4, or more preferably at the Li position, Mn position, P position and O position of LiMnPO4, the cycle performance of the battery can be further improved.

[0475] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and within the scope of the technical solution of the present application, embodiments having substantially the same structure as the technical concept and exerting the same effects are all included in the technical scope of the present application. In addition, within the scope of the subject matter of the present application, various modifications that can be conceived by those skilled in the art to the embodiments, and other methods constructed by combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A positive electrode active material composition, wherein: The positive electrode active material composition includes a first positive electrode active material and a second positive electrode active material having a different crystal form from the first positive electrode active material, wherein the second positive electrode active material includes a phosphate material. The volume distribution particle size Dv10 of the first positive electrode active material (1) The volume distribution particle size Dv50 of the second positive electrode active material (2) Meet Dv10 (1) / Dv50 (2) >1, The volume distribution particle size Dv50 of the first positive electrode active material (1) The volume distribution particle size Dv50 of the second positive electrode active material (2) Meet Dv50 (1) / Dv50 (2) ≥1.4, The true density of the first positive electrode active material is denoted as ρ1, and the true density of the second positive electrode active material is denoted as ρ2, both in units of g / cm 3 Based on the total mass of the positive electrode active material composition, the mass proportion of the first positive electrode active material is recorded as W1, and the mass proportion of the second positive electrode active material is recorded as W2, then the positive electrode active material composition satisfies -2.0≤1-[(ρ2×W2) / (ρ1×W1)]≤0.

98.

2. The positive electrode active material composition according to claim 1, wherein 1<Dv10 (1) / Dv50 (2) ≤16.5, optionally, 1.07≤Dv10 (1) / Dv50 (2) ≤11.3; and / or, 1.4<Dv50 (1) / Dv50 (2) ≤30.0, optionally, 2.0≤Dv50 (1) / Dv50 (2) ≤23.8; and / or, -0.78≤1-[(ρ2×W2) / (ρ1×W1)]≤0.96, optionally, -0.14≤1-[(ρ2×W2) / (ρ1×W1)]≤0.92, more optionally, 0.67≤1-[(ρ2×W2) / (ρ1×W1)]≤0.

92.

3. The positive electrode active material composition according to claim 1 or 2, wherein: W2=ρ2 / [(β×ρ1)+ρ2], 0.3≤β≤30, optionally, 0.5≤β≤6.9, more optionally, 1.8≤β≤6.

9.

4. The positive electrode active material composition according to any one of claims 1 to 3, wherein: The particle size distribution curve of the positive electrode active material composition has at least two volume distribution peaks, the peak with the smallest volume distribution particle size is recorded as peak I, and the other peaks other than peak I are recorded as peak II. The volume distribution particle size corresponding to the maximum peak intensity of peak I is between 0.3μm and 2.1μm, and the volume distribution particle size corresponding to the maximum peak intensity of peak II is between 3μm and 15μm. The ratio of the integral area of ​​peak I to the total integral area of ​​peak II is (0.010-2.5):1, and can be optionally (0.011-1.3):

1.

5. The positive electrode active material composition according to any one of claims 1 to 4, wherein: The particle size distribution curve of the second positive electrode active material has at least two volume distribution peaks, the peak with the smallest volume distribution particle size is recorded as peak III, and the other peaks other than peak III are recorded as peak IV. The volume distribution particle size corresponding to the maximum peak intensity of peak III is between 0.3μm and 2.1μm, the volume distribution particle size corresponding to the maximum peak intensity of peak IV is between 2.1μm and 10μm, and the ratio of the integral area of ​​peak III to the total integral area of ​​peak IV is (0.5-20):

1.

6. The positive electrode active material composition according to any one of claims 1 to 5, wherein: The ratio of the major axis length to the minor axis length of the first positive electrode active material is 1-2, and can be 1-1.4; and / or, The ratio of the major axis length to the minor axis length of the second positive electrode active material is 1-2, and can be 1-1.4; and / or, The volume distribution particle size Dv10 of the first positive electrode active material (1) 0.3-8 μm, optionally 1.6-6.6 μm; and / or, The volume distribution particle size Dv50 of the first positive electrode active material (1) 1.5-15 μm, optionally 3-12 μm; and / or, The volume distribution particle size Dv50 of the second positive electrode active material (2) 0.25-3 μm, optionally 0.4-2 μm; and / or, The true density ρ1 of the first positive electrode active material is 4.40-5.15 g / cm 3 , optional: 4.60-5.10g / cm 3 and / or, The true density ρ2 of the second positive electrode active material is 3.20-3.65 g / cm 3 , optional: 3.30-3.60g / cm 3 and / or, Based on the total mass of the positive electrode active material composition, the mass proportion W1 of the first positive electrode active material is 30%-98%, and can be 70%-90%; and / or, Based on the total mass of the positive electrode active material composition, the mass proportion W2 of the second positive electrode active material is 2%-70%, and can be optionally 10%-30%.

7. The positive electrode active material composition according to any one of claims 1 to 6, wherein: The second positive electrode active material includes a compound represented by formula (I), Li a A x Mn 1-y B y P 1-z C z O 4-n D n (I) A includes one or more elements selected from Group IA, Group IIA, Group IIIA, Group IIB, Group VB and Group VIB; B includes one or more elements selected from Group IA, Group IIA, Group IIIA, Group IVA, Group VA, Group IIB, Group IVB, Group VB, Group VIB and Group VIII; C includes one or more elements selected from Group IIIA, Group IVA, Group VA and Group VIA; D includes one or more elements selected from Group VIA and Group VIIA; a is selected from the range of 0.85 to 1.15; x is selected from the range of 0 to 0.1; y is selected from the range of 0.001 to 1; z is selected from the range of 0 to 0.5; n is selected from the range of 0 to 0.

5.

8. The positive electrode active material composition according to claim 7, wherein: y is selected from the range of 0.001 to 0.

999.

9. The positive electrode active material composition according to claim 8, wherein A includes one or more elements selected from Rb, Cs, Be, Ca, Sr, Ba, Ga, In, Cd, V, Ta, Cr, Zn, Al, Na, K, Mg, Nb, Mo and W, and may optionally include one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo and W; and / or, B includes one or more elements selected from Rb, Cs, Be, Ca, Sr, Ba, In, Pb, Bi, Cd, Hf, Ta, Cr, Ru, Rh, Pd, Os, Ir, Pt, Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb and Ge, and may optionally include one or more elements selected from Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb and Ge; and / or, C includes one or more elements selected from B (boron), S, Si and N; and / or, D includes one or more elements selected from S, F, Cl and Br.

10. The positive electrode active material composition according to claim 8 or 9, wherein: A comprises any one element selected from Zn, Al, Na, K, Mg, Nb, Mo and W, and optionally any one element selected from Mg and Nb; and / or, B includes one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge, and may include at least two elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge, and may include at least two elements selected from Fe, Ti, V, Ni, Co and Mg, and may include at least two elements selected from Fe, Ti, V, Co and Mg, and may include Fe and one or more elements selected from Ti, V, Co and Mg; and / or C includes any one element selected from B (boron), S, Si and N, and may be S; and / or, D includes any one element selected from S, F, Cl and Br, and may be F.

11. The positive electrode active material composition according to any one of claims 8 to 10, wherein: a is selected from the range of 0.9 to 1.1, optionally selected from the range of 0.97 to 1.01; and / or, x is selected from the range of 0.001 to 0.005; and / or, y is selected from the range of 0.001 to 0.5, optionally selected from the range of 0.01 to 0.5, optionally selected from the range of 0.25 to 0.5; and / or, z is selected from the range of 0.001 to 0.5, optionally selected from the range of 0.001 to 0.1, more optionally selected from the range of 0.001 to 0.005; and / or, n is selected from the range of 0 to 0.1, optionally from the range of 0.001 to 0.

005.

12. The positive electrode active material composition according to any one of claims 8 to 11, wherein: x is 0, z is selected from the range of 0.001 to 0.5, and n is selected from the range of 0.001 to 0.1; or, x is selected from the range of 0.001 to 0.1, z is 0, and n is selected from the range of 0.001 to 0.1; or, x is selected from the range of 0.001 to 0.1, z is selected from the range of 0.001 to 0.5, and n is 0; or, x is 0, z is 0, and n is selected from the range of 0.001 to 0.1; or, x is 0, z is selected from the range of 0.001 to 0.5, and n is 0; or, x is selected from the range of 0.001 to 0.1, z is selected from the range of 0.001 to 0.5, and n is selected from the range of 0.001 to 0.

1.

13. The positive electrode active material composition according to any one of claims 8 to 12, wherein: y:z is selected from the range of 0.002 to 999, and may be selected from the range of 0.025 to 999 or the range of 0.002 to 500, and may be further selected from the range of 0.2 to 600.

14. The positive electrode active material composition according to any one of claims 8 to 13, wherein: z:n is selected from the range of 0.002 to 500, can be selected from the range of 0.2 to 100, and can be further selected from the range of 0.2 to 50.

15. The positive electrode active material composition according to any one of claims 8 to 14, wherein: A includes one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo and W; B includes one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge; C includes one or more elements selected from B (boron), S, Si and N; D includes one or more elements selected from S, F, Cl and Br; a is selected from the range of 0.9 to 1.1, x is selected from the range of 0.001 to 0.1, y is selected from the range of 0.001 to 0.5, z is selected from the range of 0.001 to 0.1, and n is selected from the range of 0.001 to 0.

1.

16. The positive electrode active material composition according to any one of claims 8 to 14, wherein: B includes one or more elements selected from Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb and Ge, and can be optionally one or more elements selected from Zn, Fe, Ti, V, Ni, Co and Mg; C includes one or more elements selected from B (boron), Si, N and S; a is selected from the range of 0.9 to 1.1, x is 0, y is selected from the range of 0.001 to 0.5, z is selected from the range of 0.001 to 0.1, and n is 0.

17. The positive electrode active material composition according to any one of claims 8 to 16, wherein: (1-y): y is in the range of 0.1-999, optionally in the range of 0.1-10 or in the range of 0.67-999, more optionally in the range of 1 to 10, further optionally in the range of 1 to 4, and further optionally in the range of 1.5 to 3; and / or, a:x is in the range of 1 to 1200, and can be optionally in the range of 9 to 1100, and can be more optionally in the range of 190-998.

18. The positive electrode active material composition according to any one of claims 8 to 17, wherein: z:(1-z) is 1:9 to 1:999, and can be optionally 1:499 to 1:

249.

19. The positive electrode active material composition according to any one of claims 8 to 18, wherein: The second positive electrode active material includes a core and a shell covering the core, The inner core comprises the compound represented by formula (I); The shell includes one or more coating layers; each coating layer has ionic conductivity and / or electronic conductivity.

20. The positive electrode active material composition according to claim 19, wherein: The one or more coating layers each independently include one or more selected from pyrophosphate, phosphate, carbon, doped carbon, oxide, boride and polymer.

21. The positive electrode active material composition according to claim 19 or 20, wherein: The shell comprises a coating layer; optionally, the coating layer comprises one or more selected from pyrophosphate, phosphate, carbon, doped carbon, oxide, boride and polymer.

22. The positive electrode active material composition according to claim 19 or 20, wherein: The shell includes a first coating layer covering the core and a second coating layer covering the first coating layer; Optionally, the first coating layer and the second coating layer each independently include one or more selected from pyrophosphate, phosphate, carbon, doped carbon, oxide, boride and polymer; More optionally, the first coating layer includes one or more selected from pyrophosphate, phosphate, oxide and boride, and the second coating layer includes one or more selected from carbon and doped carbon.

23. The positive electrode active material composition according to claim 19 or 20, wherein: The shell includes a first coating layer covering the core, a second coating layer covering the first coating layer, and a third coating layer covering the second coating layer; Optionally, the first coating layer, the second coating layer and the third coating layer each independently include one or more selected from pyrophosphate, phosphate, carbon, doped carbon, oxide, boride and polymer; More optionally, the first coating layer includes pyrophosphate, the second coating layer includes one or more selected from phosphates, oxides and borides, and the third coating layer includes one or more selected from carbon and doped carbon.

24. The positive electrode active material composition according to any one of claims 20 to 23, wherein: The pyrophosphate is M b (P2O7) c and / or, The phosphate is X m (PO4) q and / or, The doping element in the doped carbon includes one or more elements selected from Group IIIA, Group VA, Group VIA and Group VIIA; and / or, The oxide is M' d O e and / or, The boride is Z v B w and / or, The polymer includes one or more selected from polysaccharides and their derivatives, and polysiloxanes; M, X and Z each independently include one or more elements selected from Group IA, Group IIA, Group IIIA, Group IB, Group IIB, Group IVB, Group VB, Group VIIB and Group VIII; b is selected from the range of 1 to 4; c is selected from the range of 1 to 6; m is selected from the range of 1 to 2; q is selected from the range of 1 to 4; M′ comprises one or more elements selected from alkali metals, alkaline earth metals, transition metals, Group IIIA elements, Group IVA elements, lanthanides and Sb; d is greater than 0 and less than or equal to 2; e is greater than 0 and less than or equal to 5; v is selected from the range of 1 to 7; w is selected from the range of 1 to 2.

25. The positive electrode active material composition according to claim 24, wherein: M, X and Z each independently include one or more elements selected from Li, Fe, Ni, Mg, Co, Cu, Zn, Ti, Ag, Zr, Nb, Mn and Al; and / or, The doping element in the doped carbon includes one or more selected from nitrogen, phosphorus, sulfur, boron and fluorine; and / or, M′ comprises one or more elements selected from Li, Be, B, Na, Mg, Al, Si, P, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, W, La and Ce, and may optionally comprise one or more elements selected from Mg, Al, Si, Zn, Zr and Sn; and / or The polysiloxane is selected from one or more of linear polysiloxane and cyclic polysiloxane; and / or, The polysaccharide is selected from one or more of plant polysaccharides and marine polysaccharides.

26. The positive electrode active material composition according to any one of claims 19 to 20, 22, 24 to 25, wherein: The second positive electrode active material includes a core and a shell covering the core, The core includes Li a Mn 1-y B y P 1-z C z O4, a is selected from the range of 0.9 to 1.1, y is selected from the range of 0.001 to 0.5, z is selected from the range of 0.001 to 0.1, B includes one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge, and C includes one or more elements selected from B (boron), S, Si and N; The shell includes a first coating layer coating the inner core and a second coating layer coating the first coating layer, wherein the first coating layer includes pyrophosphate MP2O7 and phosphate XPO4, and M and X each independently include one or more elements selected from Li, Fe, Ni, Mg, Co, Cu, Zn, Ti, Ag, Zr, Nb and Al; and the second coating layer contains carbon.

27. The positive electrode active material composition according to any one of claims 19 to 20, 23 to 25, wherein: The second positive electrode active material includes a core and a shell covering the core, The core includes Li a Mn 1-y B y P 1-z C z O4, a is selected from the range of 0.9 to 1.1, y is selected from the range of 0.001 to 0.5, z is selected from the range of 0.001 to 0.1, B includes one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge, and C includes one or more elements selected from B (boron), S, Si and N; The shell includes a first coating layer covering the core, a second coating layer covering the first coating layer, and a third coating layer covering the second coating layer. The first coating layer includes pyrophosphate Li f QP2O7 and / or Q g (P2O7) h , 0≤f≤2, 1≤g≤4, 1≤h≤6, the pyrophosphate Li f QP2O7 and / or Q g (P2O7) h wherein Q independently comprises one or more elements selected from Fe, Ni, Mg, Co, Cu, Zn, Ti, Ag, Zr, Nb and Al; The second coating layer comprises crystalline phosphate XPO4, wherein X comprises one or more elements selected from the group consisting of Li, Fe, Ni, Mg, Co, Cu, Zn, Ti, Ag, Zr, Nb and Al; The third coating layer includes carbon.

28. The positive electrode active material composition according to any one of claims 19 to 25, wherein: The one or more coating layers in the shell that are farthest from the core each independently include one or more selected from polysiloxane, polysaccharide and polysaccharide derivatives.

29. The positive electrode active material composition according to any one of claims 19 to 25 and 28, wherein: The polysiloxane comprises a structural unit represented by formula (i), R1 and R2 are independently selected from H, -COOH, -OH, -SH, -CN, -SCN, amino, phosphate, carboxylate, amide, aldehyde, sulfonyl, polyether segment, C1-C20 aliphatic, C1-C20 halogenated aliphatic, C1-C20 heteroaliphatic, C1-C20 halogenated heteroaliphatic, C6-C20 aromatic, C6-C20 halogenated aromatic, C2-C20 heteroaromatic and C2-C20 halogenated heteroaromatic; Optionally, R1 and R2 are independently selected from H, amino, phosphate, polyether segment, C1-C8 alkyl, C1-C8 haloalkyl, C1-C8 heteroalkyl, C1-C8 haloheteroalkyl, C2-C8 alkenyl and C2-C8 haloalkenyl.

30. The positive electrode active material composition according to any one of claims 19 to 25, 28 to 29, wherein: The polysiloxane further comprises an end-capping group, which comprises one or more of the following functional groups: polyether, C1-C8 alkyl, C1-C8 haloalkyl, C1-C8 heteroalkyl, C1-C8 haloheteroalkyl, C2-C8 alkenyl, C2-C8 haloalkenyl, C6-C20 aromatic hydrocarbon group, C1-C8 alkoxy, C2-C8 epoxy, hydroxyl, C1-C8 hydroxyalkyl, amino, C1-C8 aminoalkyl, carboxyl, C1-C8 carboxylalkyl.

31. The positive electrode active material composition according to any one of claims 19 to 25, 28 to 30, wherein: The polysiloxane comprises polydimethylsiloxane, polydiethylsiloxane, polymethylethylsiloxane, polymethylvinylsiloxane, polyphenylmethylsiloxane, polymethylhydrogensiloxane, carboxyl functionalized polysiloxane, epoxy-terminated polysiloxane, methoxy-terminated polydimethylsiloxane, hydroxypropyl-terminated polydimethylsiloxane, polymethylchloropropylsiloxane, hydroxy-terminated polydimethylsiloxane, polymethyltrifluoropropylsiloxane, perfluorooctylmethylpolysiloxane, aminoethylaminopropyl polydimethylsiloxane, terminal polyether polydimethylsiloxane, side-chain aminopropyl polysiloxane, aminopropyl One or more of end-capped polydimethylsiloxane, side chain phosphate grafted polydimethylsiloxane, side chain polyether grafted polydimethylsiloxane, 1,3,5,7-octamethylcyclotetrasiloxane, 1,3,5,7-tetrahydro-1,3,5,7-tetramethylcyclotetrasiloxane, cyclopentapolydimethylsiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, cyclic polymethylvinylsiloxane, hexadecylcyclooctasiloxane, tetradecamethylcycloheptasiloxane, and cyclic polydimethylsiloxane.

32. The positive electrode active material composition according to any one of claims 19 to 25 and 28 to 31, wherein: The number average molecular weight of the polysiloxane, the polysaccharide and the polysaccharide derivative is independently below 300,000, and may be 10,000 to 200,000, more preferably 20,000 to 120,000, and further preferably 400 to 80,000.

33. The positive electrode active material composition according to any one of claims 19 to 25 and 28 to 32, wherein: The mass percentage of the polar functional groups in the polysiloxane is α, 0≤α<50%, optionally, 5%≤α≤30%.

34. The positive electrode active material composition according to any one of claims 19 to 25 and 28 to 33, wherein: The substituents attached to the sugar units in the polysaccharide and the polysaccharide derivatives each independently include one or more of the group consisting of the following functional groups: -OH, -COOH and salts thereof, -R-OH, -SO3H and salts thereof, -R-OH, -R-SO3H and salts thereof, sulfate, alkoxy, R represents an alkylene group, optionally a C1 to C5 alkylene group; Optionally, the substituents attached to the sugar units in the polysaccharide and the polysaccharide derivatives each independently include one or more of the group consisting of the following functional groups: -OH, -COOH, -COOLi, -COONa, -COOK, -SO3H, -SO3Li, -SO3Na, -SO3K, -CH2-SO3H, -CH2-SO3Li, -CH2-SO3Na, -CH2-SO3K, methoxy, ethoxy.

35. According to any one of claims 19 to 25, 28 to 34, the positive electrode active material composition, the polysaccharide comprises one or more selected from pectin, carboxymethyl starch, hydroxypropyl starch, dextrin, cellulose ether, carboxymethyl chitosan, hydroxyethyl cellulose, carboxymethyl cellulose, carboxypropyl methyl cellulose, guar gum, sesbania gum, gum arabic, lithium alginate, sodium alginate, potassium alginate, fucoidan, agar, carrageenan, carrageenan, xanthan gum and fenugreek gum.

36. The positive electrode active material composition according to any one of claims 19 to 25 and 28 to 35, wherein: The mass percentage of the substituents attached to the sugar units in the polysaccharide and the polysaccharide derivatives is independently 20% to 85%, and optionally 30% to 78%.

37. The positive electrode active material composition according to any one of claims 19 to 36, wherein: The lattice mismatch between the material of the core and the material of the shell is less than 10%.

38. The positive electrode active material composition according to any one of claims 8 to 39, wherein: Based on the total weight of the second positive electrode active material, The manganese content is in the range of 10 wt% to 35 wt%, optionally in the range of 13.3 wt% to 33.2 wt%, more optionally in the range of 15 wt% to 30 wt%, further optionally in the range of 17 wt% to 20 wt%; and / or, The phosphorus content is in the range of 12 wt% to 25 wt%, optionally in the range of 15 wt% to 20 wt%, and more optionally in the range of 16.8 wt% to 19.5 wt%; and / or, The weight ratio of manganese element to phosphorus element ranges from 0.71 to 1.85, and can be selected from 0.90 to 1.25, and more preferably from 0.95 to 1.

20.

39. The positive electrode active material composition according to any one of claims 1 to 18, wherein: The surface of the second positive electrode active material is coated with one or more of carbon and doped carbon; optionally, the surface of the second positive electrode active material is coated with carbon.

40. The positive electrode active material composition according to claim 39, wherein The doping elements in the doped carbon include one or more selected from nitrogen, phosphorus, sulfur, boron and fluorine.

41. The positive electrode active material composition according to any one of claims 19 to 21, 24 to 25, 28 to 40, wherein: The coating amount of the shell is 0.1 wt % to 6 wt % based on the weight of the core.

42. The positive electrode active material composition according to any one of claims 19 to 20, 22 to 38, wherein: The coating amount of the first coating layer is greater than 0 and less than or equal to 7% by weight, and can be greater than 0 and less than or equal to 6% by weight, and can be greater than 0 and less than or equal to 5.5% by weight or 4-5.6% by weight, and can be further greater than 0 and less than or equal to 2% by weight, based on the weight of the core; and / or, The coating amount of the second coating layer is greater than 0 and less than or equal to 6% by weight, optionally greater than 0 and less than or equal to 5.5% by weight, and more optionally 2-4% by weight or 3-5% by weight, based on the weight of the core; and / or, The coating amount of the third coating layer is greater than 0 and less than or equal to 6% by weight, optionally greater than 0 and less than or equal to 5.5% by weight, and more optionally greater than 0 and less than or equal to 2% by weight, based on the weight of the core.

43. The positive electrode active material composition according to any one of claims 19 to 20, 23 to 25, 27 to 38, and 42, wherein: The shell further includes a fourth coating layer covering the third coating layer and a fifth coating layer covering the fourth coating layer; The coating amounts of the fourth coating layer and the fifth coating layer are each independently 0.01 wt % to 10 wt %, optionally 0.05 wt % to 10 wt %, more optionally 0.1 wt % to 5 wt %, further 0.1 wt % to 2 wt %, based on the weight of the core.

44. The positive electrode active material composition according to any one of claims 19 to 43, wherein: The shell is located on 40% to 90% of the surface of the inner core, optionally 60% to 80% of the surface.

45. The positive electrode active material composition according to any one of claims 19 to 21, 24 to 25, 28 to 41, 44, wherein: The shell has a thickness of 1-15 nm.

46. ​​The positive electrode active material composition according to any one of claims 19 to 20, 22 to 38, 42 to 45, wherein: The thickness of the first coating layer is 1-10 nm, and can be 2-10 nm; and / or, The thickness of the second coating layer is 2-25 nm, optionally 2-15 nm, more optionally 3-15 nm; and / or, The thickness of the third coating layer is 2-25 nm, and can be optionally 5-25 nm.

47. The positive electrode active material composition according to any one of claims 19 to 46, wherein: The one or more coating layers each independently include one or more selected from pyrophosphate, phosphate and oxide, and the one or more selected from the pyrophosphate, phosphate and oxide are crystalline; Optionally, the crystallinity of the pyrophosphate, the phosphate and the oxide is each independently 10% to 100%, more preferably 50% to 100%.

48. The positive electrode active material composition according to any one of claims 19 to 47, wherein: In the shell, the weight ratio of pyrophosphate to phosphate and the weight ratio of pyrophosphate to oxide are each independently 1:3 to 3:1, and optionally 1:3 to 1:

1.

49. The positive electrode active material composition according to any one of claims 19 to 48, wherein The one or more coating layers each independently include carbon, and the carbon is a mixture of SP2 carbon and SP3 carbon; Optionally, in the carbon, the molar ratio of the SP2 carbon to the SP3 carbon is any value in the range of 0.07-13, more preferably any value in the range of 0.1-10, and further preferably any value in the range of 2.0-3.

0.

50. The positive electrode active material composition according to any one of claims 19 to 49, wherein: The one or more coating layers each independently include doped carbon, and the mass content of the doping element in the doped carbon is less than 30%; optionally, the mass content of the doping element in the doped carbon is less than 20%.

51. The positive electrode active material composition according to any one of claims 19 to 50, wherein: The one or more coating layers each independently include doped carbon, in which: The doping element is nitrogen and / or sulfur, and the mass content of the doping element in the doped carbon is 1% to 15%; or, The doping element is phosphorus, boron and / or fluorine, and the mass content of the doping element in the doped carbon is 0.5% to 5%; Optionally, the doping element is nitrogen, phosphorus, sulfur, boron or fluorine.

52. The positive electrode active material composition according to any one of claims 19 to 51, wherein: The one or more coating layers independently include pyrophosphate, the interplanar spacing of the pyrophosphate is in the range of 0.293-0.470nm, optionally 0.297-0.462nm or 0.293-0.326nm, more optionally 0.300-0.310nm, and the angle of the crystal direction (111) is in the range of 18.00°-32.57°, optionally 18.00°-32.00° or 26.41°-32.57°, more optionally 19.211°-30.846°, and further optionally 29.00°-30.00°; and / or, The one or more coating layers independently include phosphate, the interplanar spacing of the phosphate is in the range of 0.244-0.425 nm, optionally 0.345-0.358 nm, and the angle of the crystal direction (111) is in the range of 20.00°-37.00°, optionally 24.25°-26.45°; Optionally, the first coating layer or the second coating layer comprises phosphate.

53. The positive electrode active material composition according to any one of claims 1 to 52, wherein: The lattice change rate of the second positive electrode active material before and after complete lithium deintercalation is 50% or less, optionally 9.8% or less, more optionally 8.1% or less, further optionally 7.5% or less, further optionally 6% or less, further optionally 4% or less, further optionally 3.8% or less, further optionally 2.0-3.8%; and / or, The Li / Mn antisite defect concentration of the second positive electrode active material is 5.3% or less, optionally 5.1% or less, more optionally 4% or less, further optionally 2.2% or less, further optionally 2% or less, further optionally 1.5%-2.2% or 0.5% or less; and / or, The surface oxygen valence state of the second positive electrode active material is -1.55 or less, optionally -1.82 or less, more optionally -1.88 or less, further optionally -1.90 or less or -1.98 to -1.88, further optionally -1.98 to -1.89, further optionally -1.98 to -1.

90.

54. The positive electrode active material composition according to any one of claims 1 to 53, wherein: The powder compaction density P1 of the first positive electrode active material at 30000N is 3.0 g / cm 3 Above, 3.2g / cm2 is optional 3 Above, 3.3g / cm2 is optional 3 Above, further optional 3.4g / cm 3 Above, further optional 3.5g / cm 3 above; and / or, The powder compaction density P2 of the second positive electrode active material at 30000N is 1.89 g / cm 3 Above, optional 1.95g / cm 3 Above, 1.98g / cm2 is optional 3 Above, further optional 2.0g / cm 3 Above, further optional 2.2g / cm 3 Above, further optionally 2.2 g / cm 3 Above and 2.8g / cm 3 Below or 2.2g / cm 3 Above and 2.65g / cm 3 the following.

55. The positive electrode active material composition according to any one of claims 1 to 54, wherein: The first positive electrode active material includes one or more of a layered oxide material, a lithium-rich oxide material, a spinel lithium manganate material, and their respective modified compounds, and the modification method includes doping and / or surface coating modification.

56. The positive electrode active material composition according to claim 55, wherein The first positive electrode active material includes a compound represented by formula (II), Li a1 A 1 b1 Ni c1 Co d1 B 1 e1 C 1 f1 O 2-g1 D 1 g1 (II) A 1 Includes one or more elements selected from Group IA, Group IIA, Group VIII, Group VIB, and Group IIB; B 1 including Mn and / or Al; C 1 comprising one or more elements selected from Group IA, Group IIA, Group IIIA, Group IVA, Group VA, Group VIA, Group IIB, Group IIIB, Group IVB, Group VB, Group VIB, and Group VIII; D 1 It includes one or more elements selected from Group VIA and Group VIIA; a1 is selected from the range of 0.8 to 1.2; b1 is selected from the range of 0 to 0.2; c1 is selected from the range of 0 to 1; d1 is selected from the range of 0 to 1; e1 is selected from the range of 0 to 1; f1 is selected from the range of 0 to 0.1; g1 is selected from the range of 0 to 0.1; and c1+d1+e1+f1=1.

57. The positive electrode active material composition according to claim 56, wherein A 1 including one or more elements selected from the group consisting of Na, K, Mg, Rb, Zn, and Zr; and / or, C 1 including one or more elements selected from the group consisting of Al, Mg, Ca, Na, Ti, W, Zr, Sr, Cr, Fe, Zn, Ba, Mo, V, Ce, Nb, Sb, Ta, Ge, Nb, Sc, Ba, B, S and Y, and optionally including one or more elements selected from the group consisting of Al, Ti, Zr, Nb, Sr, Sc, Sb, Y, Ba, B; and / or, D 1 comprising one or more elements selected from N, S, F, Cl and Br, and optionally comprising S and / or F; and / or, a1 is selected from the range of 0.9 to 1.1; and / or, b1 is selected from the range of 0 to 0.1; and / or, c1 is selected from the range of 0.314 to 0.990, and may be selected from the range of 0.500 to 0.990; and / or, d1 is selected from the range of 0 to 0.320, and may be selected from the range of 0 to 0.150; and / or, e1 is selected from the range of 0.001 to 0.450, and may be selected from the range of 0.005 to 0.4; and / or, f1 is selected from the range of 0.001 to 0.1, and may be selected from the range of 0.001 to 0.05; and / or, g1 is selected from the range of 0 to 0.01, and can be optionally selected from the range of 0.01 to 0.

05.

58. The positive electrode active material composition according to claim 56 or 57, wherein The first positive electrode active material includes a core and a shell covering the core, The core comprises the compound represented by formula (II); The shell includes one or more coating layers; each coating layer has ionic conductivity and / or electronic conductivity.

59. The positive electrode active material composition according to claim 58, wherein The one or more coating layers each independently include one or more selected from phosphate, pyrophosphate, carbon, doped carbon, oxide, and fast ion conductor, and may optionally include one or more selected from phosphate, pyrophosphate, and oxide.

60. The positive electrode active material composition according to claim 58 or 59, wherein The shell includes a coating; Optionally, the coating layer includes one or more selected from phosphates, pyrophosphates, and oxides.

61. The positive electrode active material composition according to claim 58 or 59, wherein: The shell includes a first coating layer covering the core and a second coating layer covering the first coating layer; Optionally, the first coating layer and the second coating layer each independently include one or more selected from phosphates, pyrophosphates, and oxides; More optionally, the first coating layer includes one or more selected from phosphates and oxides, and the second coating layer includes one or more selected from pyrophosphates and oxides.

62. The positive electrode active material composition according to any one of claims 58 to 61, wherein The coating amount of the shell is 0.005 wt % to 1 wt %, and optionally 0.01 wt % to 0.5 wt %, based on the weight of the core; and / or, The shell has a thickness of 2 nm to 200 nm, and optionally 5 nm to 50 nm.

63. The positive electrode active material composition according to claim 55, wherein The first positive electrode active material includes a compound represented by formula (III), Li 1+p1 A 2 q1 B 2 r1 O s1 (III) 0.05 ≤ p1 < 0.2, 0.10 < q1 ≤ 0.95, 0 ≤ r1 ≤ 0.2, and 2 ≤ s1 < 3, A 2 comprises one or more elements selected from Co, Ni, Mn, and Al; B 2 comprises one or more elements selected from Mg, Ti, Cr, Zr, Nb, Fe, Mo, Cu, Sb, V, P, and F.

64. The positive electrode active material composition according to claim 63, wherein: The first positive electrode active material includes a core and a shell covering the core, The inner core comprises the compound represented by formula (III); The shell includes one or more coating layers; each coating layer has ionic conductivity and / or electronic conductivity.

65. The positive electrode active material composition according to claim 64, wherein The one or more coating layers independently include one or more materials selected from phosphates, pyrophosphates, solid electrolytes, conductive polymers, and materials capable of reversibly inserting and deinserting lithium ions.

66. The positive electrode active material composition according to claim 64 or 65, wherein The coating amount of the shell is 0.1 wt % to 5 wt %, optionally 0.5 wt % to 2 wt %, based on the weight of the core; and / or, The shell has a thickness of 2 nm to 200 nm, and optionally 5 nm to 50 nm.

67. The positive electrode active material composition according to claim 55, wherein: The first positive electrode active material includes a compound represented by formula (IV), LiMn t1 A 3 2-t1 O4 (IV) t1 is selected from the range of 0 to 2, A 3 Includes one or more elements selected from Ni, Cr, Al, Zr, V, Ti, Mo, Ru, Mg, Nb, Ba, Si, P, W, Co, Cu and Zn.

68. The positive electrode active material composition according to claim 67, wherein The third positive electrode active material includes a core and a shell covering the core, The inner core comprises the compound represented by formula (IV); The shell includes one or more coating layers; each coating layer has ionic conductivity and / or electronic conductivity.

69. The positive electrode active material composition according to claim 68, wherein The one or more coating layers independently include one or more materials selected from phosphates, pyrophosphates, solid electrolytes, conductive polymers, and materials capable of reversibly inserting and deinserting lithium ions.

70. The positive electrode active material composition according to claim 68 or 69, wherein The coating amount of the shell is 0.1 wt % to 3 wt %, optionally 0.2 wt % to 1.5 wt %, based on the weight of the core; and / or, The shell has a thickness of 2 nm to 200 nm, and optionally 5 nm to 50 nm.

71. A positive electrode sheet, comprising a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises the positive electrode active material composition according to any one of claims 1 to 70, Optionally, the content of the positive electrode active material composition in the positive electrode film layer is 90-99.5% by weight, more preferably 95-99.5% by weight, based on the total weight of the positive electrode film layer.

72. The positive electrode sheet according to claim 71, wherein: The positive electrode sheet satisfies 0.23≤(h1×N1) / (CW / PD / 10000)<1, optionally, 0.63≤(h1×N1) / (CW / PD / 10000)≤0.87, h1 represents the average size of the first positive electrode active material particles along the thickness direction of the positive electrode film layer, in μm; N1 represents the number of the first positive electrode active material particles accommodated in the positive electrode film layer along the thickness direction of the positive electrode film layer; CW represents the surface density of the positive electrode film layer, in g / cm 2 PD represents the compaction density of the positive electrode film layer, in g / cm 3 .

73. The positive electrode sheet according to claim 72, wherein: Along the thickness direction of the positive electrode film layer, the average size h1 of the first positive electrode active material particles is 0.5-20 μm, and can be 2.8-9.2 μm; and / or, Along the thickness direction of the positive electrode film layer, the number N1 of the first positive electrode active material particles contained in the positive electrode film layer is 5-25, and can be 6-20; and / or, The surface density CW of the positive electrode film layer is 0.01-0.05 g / cm 2 , optional: 0.015-0.035g / cm 2 and / or, The compaction density PD of the positive electrode film layer is 1.8-3.6 g / cm 3 , optional: 2.0-3.4g / cm 3 .

74. The positive electrode sheet according to claim 72 or 73, wherein: The positive electrode sheet also satisfies 0.5≤α1+(PD / ρ1)≤1.5, where α1 represents the porosity of the positive electrode film layer. Optionally, the porosity α1 of the positive electrode film layer is 0.28-0.50, and optionally 0.30-0.

39.

75. The positive electrode sheet according to any one of claims 72 to 74, wherein: Based on the total mass of the positive electrode active material composition, the mass proportion of the first positive electrode active material is recorded as W1, the mass proportion of the second positive electrode active material is recorded as W2, the powder compaction density of the first positive electrode active material at 30000N is recorded as P1, and the powder compaction density of the second positive electrode active material at 30000N is recorded as P2, both in g / cm 3 , then PD / [(P1×W1)+(P2×W2)] is above 89%, and can be optionally above 92%.

76. A battery comprising the positive electrode active material composition according to any one of claims 1 to 70, or the positive electrode sheet according to any one of claims 71 to 75.

77. An electrical device comprising the battery according to claim 76.

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