Composite cathode material, cathode electrode sheet and battery

Abstract

The present invention relates to a composite cathode material, a cathode electrode sheet and a battery. The composite cathode material includes a lithium manganate material and a lithium-rich and sodium-rich manganese-based material, and the median particle size of the lithium manganate material is greater than that of the lithium-rich and sodium-rich manganese-based material; the tap density PD of the composite cathode material satisfies: 1.05×(X1×PD1 + X2×PD2) < PD < 1.2×(X1×PD1 + X2×PD2), and PD > 1.02×max{PD1, PD2}, where X1 represents the mass fraction of the lithium manganate material in the composite cathode material, 50% ≤ X1 ≤ 90%, PD1 represents the tap density of the lithium manganate material, X2 represents the mass fraction of the lithium-rich and sodium-rich manganese-based material in the composite cathode material, 10% ≤ X2 ≤ 50%, PD2 represents the tap density of the lithium-rich and sodium-rich manganese-based material, and max represents taking the maximum value of PD1 and PD2. The composite cathode material of the present invention not only has a lower cost, but also has excellent cycling performance, and can significantly improve the electrical performance when applied to a battery.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to a composite cathode material, a cathode pole piece, and a battery. Background Art

[0002] Spinel lithium manganate has a three-dimensional lithium-ion diffusion channel, excellent rate performance and low-temperature performance, and low cost, and has received extensive attention in recent years. However, its relatively low energy density, severe manganese dissolution during cycling, and Jahn-Teller effect greatly limit its application in the power field.

[0003] Although the performance defects of lithium manganate can be compensated by blending spinel lithium manganate with lithium-rich manganese-based materials, the cost of lithium-rich manganese-based materials is relatively high, and there are phenomena of oxygen release and transformation from a layered structure to a spinel structure and then to a rock salt structure during cycling, resulting in poor structural stability and cycling performance of the blended cathode material. Therefore, there is an urgent need to develop a cathode material with both low cost and high cycling performance. Summary of the Invention

[0004] Based on this, in view of the above problems, it is necessary to provide a composite cathode material, a cathode pole piece, and a battery; the composite cathode material not only has a lower cost, but also has excellent cycling performance, and can significantly improve the electrical performance when applied to a battery.

[0005] A composite cathode material includes a lithium manganate material and a lithium-rich and sodium-rich manganese-based material, and the median particle size of the lithium manganate material is greater than that of the lithium-rich and sodium-rich manganese-based material;

[0006] The tap density PD of the composite cathode material satisfies: 1.05×(X 1 ×PD 1 +X 2 ×PD 2 )<PD<1.2×(X 1 ×PD 1 +X 2 ×PD 2 ) and PD>1.02×max{PD 1 , PD 2}, where X 1 represents the mass fraction of the lithium manganate material in the composite cathode material, 50%≤X 1 ≤90%, PD 1 represents the tap density of the lithium manganate material, X 2 represents the mass fraction of the lithium-rich and sodium-rich manganese-based material in the composite cathode material, 10%≤X 2 ≤50%, PD 2 represents the tap density of the lithium-rich and sodium-rich manganese-based material, and max represents taking PD 1 , PD2 The maximum value in

[0007] In one embodiment, the particle size distribution width SPAN of the composite cathode material ≥ 1.3×(SPAN 1 +SPAN 2 ) / 2, where SPAN 1 represents the particle size distribution width of the lithium manganese oxide material, and SPAN 2 represents the particle size distribution width of the lithium-rich and sodium-rich manganese-based material.

[0008] In one embodiment, the difference between the median particle size of the lithium manganese oxide material and the median particle size of the lithium-rich and sodium-rich manganese-based material is 5 μm - 15 μm.

[0009] In one embodiment, the lithium manganese oxide material satisfies at least one of the following conditions:

[0010] (1) 8 μm ≤ D 50 ≤ 20 μm;

[0011] (2) 3 μm ≤ D 10 ≤ 7 μm;

[0012] (3) The particle size distribution width SPAN of the lithium manganese oxide material 1 is 1 - 2;

[0013] (4) The tap density PD of the lithium manganese oxide material 1 is 2.6 g / cm 3 - 2.9 g / cm 3 ;

[0014] (5) The specific surface area of the lithium manganese oxide material is 0.2 m 2 / g - 0.8 m 2 / g;

[0015] (6) The lithium manganese oxide material has a spinel crystal structure;

[0016] (7) The chemical formula of the lithium manganese oxide material is Li 1+x Mn 2-a A a O 4 D b , where 0 ≤ x ≤ 0.2, 0 < a ≤ 0.2, 0 ≤ b ≤ 0.05, A represents a cation doping element, A is selected from at least one of W, Mo, V, Ta, Nb, P, Zr, Ti, Cr, Al, Fe, La, Ce, Nd, Sm, Gd, Tm, Bi, Co, Mg, Ni, Zn, and D represents an anion doping element, D is selected from at least one of F, Cl, I, S.

[0017] In one of the embodiments, the lithium-rich and sodium-rich manganese-based material satisfies at least one of the following conditions:

[0018] (1) 3 μm ≤ D 50 ≤ 6 μm;

[0019] (2) 1 μm ≤ D 10 ≤ 4 μm;

[0020] (3) The particle size distribution width SPAN of the lithium-rich and sodium-rich manganese-based material 2 is 0.5 - 1.5;

[0021] (4) The tap density PD of the lithium-rich and sodium-rich manganese-based material 2 is 2.7 g / cm 3 - 2.9 g / cm 3 ;

[0022] (5) The specific surface area of the lithium-rich and sodium-rich manganese-based material is 1 m 2 / g - 4 m 2 / g;

[0023] (6) The lithium-rich and sodium-rich manganese-based material is in a layered structure;

[0024] (7) In the X-ray diffraction pattern of the lithium-rich and sodium-rich manganese-based material, the diffraction peak intensities of (002), (003), (104), and (101) are respectively denoted as I (002) , I (003) , I (104) , I (101) , and 0.01 ≤ I (002) / [I (003) + I (104) + I (101) ≤ 0.5;

[0025] (8) The chemical formula of the lithium-rich and sodium-rich manganese-based material is Li 1+m Na n Ni 1-c-d-e Co c Mn d M e O f E g, where \(0\leq m\leq0.3\), \(0.05\leq n\leq0.3\), and \(0.1\leq m + n\leq0.5\), \(0.2\leq1 - c - d - e\leq0.4\), \(0\leq c\leq0.1\), \(0.5\leq d\leq0.8\), \(0\lt e\leq0.05\), \(0\leq g\leq0.1\), and \(f + g = 2 + m + n\), \(M\) represents a cation-doped element, and \(M\) is selected from at least one of \(W\), \(Mo\), \(Nb\), \(Ta\), \(V\), \(Te\), \(Sb\), \(Ce\), \(Ti\), \(Zr\), \(Sn\), \(B\), \(Cr\), \(Fe\), \(Al\), \(La\), \(Sc\), \(Sm\), \(Y\), \(Ba\), \(Mg\), \(Sr\), \(Zn\), \(Cu\), \(K\); \(E\) represents an anion-doped element, and \(E\) is selected from at least one of \(F\), \(Cl\), \(I\), \(S\).

[0026] In one embodiment, the composite cathode material further includes lithium iron manganese phosphate material, and the median particle size of the lithium-rich and sodium-rich manganese-based material is greater than that of the lithium iron manganese phosphate material;

[0027] The tap density \(PD\) of the composite cathode material satisfies: \(1.05\times(X\) 1 \times PD\) 1 +X\) 2 \times PD\) 2 +X\) 3 \times PD\) 3 ) \lt PD \lt 1.2\times(X\) 1 \times PD\) 1 +X\) 2 \times PD\) 2 +X\) 3 \times PD\) 3 ), and \(PD\gt1.02\times max\{PD\) 1 , \(PD\) 2 , \(PD\) 3 \}, where \(X\) 1 represents the mass fraction of lithium manganese oxide material in the composite cathode material, \(50\%\leq X\) 1 \leq70\%\), \(PD\) 1 represents the tap density of the lithium manganese oxide material, \(X\) 2 represents the mass fraction of the lithium-rich and sodium-rich manganese-based material in the composite cathode material, \(20\%\leq X\) 2 \leq40\%\), \(PD\) 2 represents the tap density of the lithium-rich and sodium-rich manganese-based material, \(X\) 3 represents the mass fraction of lithium iron manganese phosphate material in the composite cathode material, \(5\%\leq X\) 3 \leq20\%\), \(PD\) 3 represents the tap density of the lithium iron manganese phosphate material, and \(max\) represents taking the maximum value of \(PD\) 1 , \(PD\) 2 , \(PD\) 3 .

[0028] In one embodiment, the particle size distribution width SPAN of the composite cathode material satisfies SPAN≥1.3×(SPAN 1 +SPAN 2 +SPAN 3 ) / 3, where SPAN 1 represents the particle size distribution width of the lithium manganate material, SPAN 2 represents the particle size distribution width of the lithium-rich and sodium-rich manganese-based material, and SPAN 3 represents the particle size distribution width of the lithium iron manganese phosphate material.

[0029] In one embodiment, the difference between the median particle size of the lithium-rich and sodium-rich manganese-based material and the median particle size of the lithium iron manganese phosphate material is 2 μm - 5 μm.

[0030] In one embodiment, the lithium iron manganese phosphate material satisfies at least one of the following conditions:

[0031] (1) 0.5 μm ≤ D 50 ≤ 2 μm;

[0032] (2) 0.1 μm ≤ D 10 ≤ 1 μm;

[0033] (3) The particle size distribution width SPAN of the lithium iron manganese phosphate material is 1.0 - 3.0; 3 ;

[0034] (4) The tap density PD of the lithium iron manganese phosphate material is 2.0 g / cm 3 - 2.5 g / cm 3 ; 3 ;

[0035] (5) The specific surface area of the lithium iron manganese phosphate material is 15 m 2 / g - 25 m 2 / g;

[0036] (6) The lithium iron manganese phosphate material has an olivine crystal structure;

[0037] (7) The chemical formula of the lithium iron manganese phosphate material is Li 1+y Mn p Fe q Q 1-p-q PO 4 @C, where 0 ≤ y ≤ 0.1, 0.4 ≤ p < 1, 0 < q ≤ 0.6, 0 ≤ 1 - p - q ≤ 0.05, and Q is selected from at least one of V, Nb, Ti, Zr, Al, Mg, Ni, Co, Zn.

[0038] In one embodiment, the composite cathode material satisfies at least one of the following conditions:

[0039] (1) 3μm ≤ D 50 ≤ 15μm;

[0040] (2) 1μm ≤ D 10 ≤ 4μm;

[0041] (3) The particle size distribution width SPAN of the composite cathode material ≥ 2.0;

[0042] (4) The tap density PD of the composite cathode material ≥ 2.9 g / cm 3 ;

[0043] (5) The specific surface area of the composite cathode material is 0.5 m 2 / g - 6 m 2 / g.

[0044] A positive electrode sheet, comprising a positive electrode current collector and a positive electrode active material layer, wherein the positive electrode active material layer contains the composite cathode material as described above.

[0045] A battery, comprising the positive electrode sheet as described above.

[0046] The composite cathode material of the present invention uses a low-cost lithium-rich and sodium-rich manganese-based material. By blending lithium manganate materials with larger particle sizes and lithium-rich and sodium-rich manganese-based materials with smaller particle sizes, and synergistically controlling the mass fraction and particle size difference of the lithium manganate material and the lithium-rich and sodium-rich manganese-based material, not only is the compaction greatly improved, but also the problem of capacity attenuation of the lithium manganate material in the initial stage of cycling is overcome, the first Coulomb efficiency and discharge capacity of the composite cathode material are improved. Moreover, compared with the lithium-rich manganese-based material under the same blending ratio, the composite cathode material with the blended lithium-rich and sodium-rich manganese-based material provided by the present invention has better structural stability, which is beneficial to improving the cycling performance. Therefore, applying it to a battery can significantly improve the electrical performance, especially the cycling performance and rate performance, thereby improving the fast charging performance of the battery. Description of the Drawings

[0047] Figure 1 It is a scanning electron microscope (SEM) image of the lithium manganate material prepared in Example 1;

[0048] Figure 2 It is a scanning electron microscope (SEM) image of the lithium-rich and sodium-rich manganese-based material prepared in Example 1;

[0049] Figure 3 It is an X-ray diffraction (XRD) pattern of the lithium-rich and sodium-rich manganese-based material prepared in Example 1, where △ represents the characteristic peak of the P2 phase;

[0050] Figure 4 It is a scanning electron microscope (SEM) image of the composite cathode material prepared in Example 1;

[0051] Figure 5 The particle size distribution diagram of the composite cathode material prepared in Example 1;

[0052] Figure 6 The scanning electron microscope (SEM) image of the mixture of lithium manganate material and lithium iron manganese phosphate material prepared in Example 9;

[0053] Figure 7 The scanning electron microscope (SEM) image of the composite cathode material prepared in Example 9;

[0054] Figure 8 The particle size distribution diagram of the composite cathode material prepared in Example 9. Detailed implementation manners

[0055] For the convenience of understanding the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the implementation manners or embodiments described herein. On the contrary, the purpose of providing these implementation manners or embodiments is to make the understanding of the disclosure content of the present invention more thorough and comprehensive.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific implementation manners or embodiments, and are not intended to limit the present invention.

[0057] The present invention provides a composite cathode material, including a lithium manganate material and a lithium-rich and sodium-rich manganese-based material, and the median particle size of the lithium manganate material is greater than that of the lithium-rich and sodium-rich manganese-based material.

[0058] The tap density PD of the composite cathode material satisfies: 1.05×(X 1 ×PD 1 +X 2 ×PD 2 )<PD<1.2×(X 1 ×PD 1 +X 2 ×PD 2 ), and PD>1.02×max{PD 1 , PD 2}. Preferably, PD>1.03×max{PD 1 , PD 2}; More preferably, PD>1.04×max{PD 1 , PD 2}. Wherein, X 1 represents the mass fraction of the lithium manganate material in the composite cathode material, 50%≤X 1 ≤90%, PD1 represents the tap density of the lithium manganate material, X 2 represents the mass fraction of the lithium-rich and sodium-rich manganese-based material in the composite cathode material, 10% ≤ X 2 ≤ 50%, PD 2 represents the tap density of the lithium-rich and sodium-rich manganese-based material, max represents taking the maximum value of PD 1 and PD 2 among them.

[0059] In the present invention, by blending the lithium manganate material with a larger particle size and the lithium-rich and sodium-rich manganese-based material with a smaller particle size, and controlling the mass fractions of the lithium manganate material and the lithium-rich and sodium-rich manganese-based material, the tap density of the composite cathode material is greatly improved. In addition, the lithium-rich and sodium-rich manganese-based material adopted in the present invention has a P2-O3 type composite structure, and the two phases are evenly distributed, and the P2 phase is occupied by sodium ions and vacancies. During the charging process, some sodium ions will be removed and participate in the formation of the negative electrode SEI film, which is beneficial to reducing the loss of active lithium. This not only overcomes the problem of capacity decay of the lithium manganate material in the initial stage of cycling, improves the first Coulomb efficiency and discharge capacity of the composite cathode material, but also compared with the lithium-rich manganese-based material under the same blending ratio, the composite cathode material provided by the present invention with the blended lithium-rich and sodium-rich manganese-based material has better structural stability, is beneficial to improving the cycling performance, and has lower cost.

[0060] Specifically, the mass fraction X of the lithium manganate material in the composite cathode material 1 includes but is not limited to any point value or the range value between any two of 50%, 60%, 70%, 80%, 90%; the mass fraction X of the lithium-rich and sodium-rich manganese-based material in the composite cathode material 2 includes but is not limited to any point value or the range value between any two of 10%, 20%, 30%, 40%, 50%.

[0061] In one embodiment, the particle size distribution width SPAN of the composite cathode material ≥ 1.3 × (SPAN 1 +SPAN 2 ) / 2, where SPAN 1 represents the particle size distribution width of the lithium manganate material, and SPAN 2 represents the particle size distribution width of the lithium-rich and sodium-rich manganese-based material.

[0062] It can be understood that the particle size distribution width SPAN = (D 90 -D 10 ) / D 50 , where D 50 is the particle size corresponding to the cumulative volume of the particles reaching 50%, that is, the median particle size; D 90 is the particle size corresponding to the cumulative volume of the particles reaching 90%; D 10is the particle size corresponding to the accumulation of 10% of the granules.

[0063] In one embodiment, the difference between the median particle size of the lithium manganate material and the median particle size of the lithium-rich and sodium-rich manganese-based material is 5 μm - 15 μm, including but not limited to any point value among 5 μm, 8 μm, 10 μm, 12 μm, 15 μm or the range value between any two of them. Further preferably, it is 6 μm - 15 μm, including but not limited to any point value among 6 μm, 8 μm, 10 μm, 12 μm, 15 μm or the range value between any two of them. Even more preferably, it is 6 μm - 12 μm, including but not limited to any point value among 6 μm, 8 μm, 10 μm, 12 μm or the range value between any two of them.

[0064] In one embodiment, the median particle size of the lithium manganate material is preferably 8 μm - 20 μm, including but not limited to any point value among 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm or the range value between any two of them. Further preferably, it is 9 μm - 18 μm, including but not limited to any point value among 9 μm, 10 μm, 12 μm, 15 μm, 18 μm or the range value between any two of them. Even more preferably, it is 10 μm - 18 μm, including but not limited to any point value among 10 μm, 12 μm, 15 μm, 18 μm or the range value between any two of them.

[0065] In one embodiment, the D of the lithium manganate material 10 is preferably 3 μm - 7 μm, including but not limited to any point value among 3 μm, 4 μm, 5 μm, 6 μm, 7 μm or the range value between any two of them. Further preferably, it is 3 μm - 6 μm, including but not limited to any point value among 3 μm, 4 μm, 5 μm, 6 μm or the range value between any two of them.

[0066] In one embodiment, the particle size distribution width SPAN of the lithium manganate material 1 is preferably 1 - 2, including but not limited to any point value among 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 or the range value between any two of them. Further preferably, it is 1.2 - 2, including but not limited to any point value among 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 or the range value between any two of them.

[0067] In one embodiment, the tap density PD of the lithium manganate material 1 is preferably 2.6 g / cm 3 - 2.9 g / cm 3 , including but not limited to 2.6 g / cm 3 , 2.7 g / cm 3, 2.8 g / cm 3 , 2.9 g / cm 3 Any point value within these or any range value between any two of them.

[0068] In one embodiment, the specific surface area of the lithium manganate material is preferably 0.2 m 2 / g - 0.8 m 2 / g, including but not limited to 0.2 m 2 / g, 0.3 m 2 / g, 0.4 m 2 / g, 0.5 m 2 / g, 0.6 m 2 / g, 0.8 m 2 / g. Further preferably, it is 0.3 m 2 / g - 0.8 m 2 / g, including but not limited to 0.3 m 2 / g, 0.4 m 2 / g, 0.5 m 2 / g, 0.6 m 2 / g, 0.8 m 2 / g. Any point value within these or any range value between any two of them.

[0069] In one embodiment, the lithium manganate material has a spinel crystal structure.

[0070] In one embodiment, the chemical formula of the lithium manganate material is Li 1+x Mn 2-a A a O 4 D b , where 0 ≤ x ≤ 0.2, 0 < a ≤ 0.2, 0 ≤ b ≤ 0.05. Preferably, 0.01 ≤ x ≤ 0.15, 0.001 ≤ a ≤ 0.18, 0.001 ≤ b ≤ 0.045. Further preferably, 0.02 ≤ x ≤ 0.12, 0.002 ≤ a ≤ 0.15, 0.002 ≤ b ≤ 0.04; A represents a cation doping element, and A is selected from at least one of W, Mo, V, Ta, Nb, P, Zr, Ti, Cr, Al, Fe, La, Ce, Nd, Sm, Gd, Tm, Bi, Co, Mg, Ni, Zn. Preferably, A is selected from at least one of Nb, P, Cr, Al, La, Sm, Gd, Co, Mg, Ni; D represents an anion doping element, and D is selected from at least one of F, Cl, I, S. Preferably, D is selected from at least one of F, Cl, I. Further preferably, D is selected from at least one of F, Cl. Still further preferably, D is selected from F.

[0071] In one embodiment, the median particle size of the lithium-rich and sodium-rich manganese-based material is preferably 3 μm - 6 μm, including but not limited to any point value among 3 μm, 4 μm, 5 μm, 6 μm or the range value between any two of them. More preferably, it is 3 μm - 5 μm, including but not limited to any point value among 3 μm, 4 μm, 5 μm or the range value between any two of them.

[0072] In one embodiment, the D 10 of the lithium-rich and sodium-rich manganese-based material is preferably 1 μm - 4 μm, including but not limited to any point value among 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm or the range value between any two of them. More preferably, it is 1.5 μm - 3.5 μm, including but not limited to any point value among 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm or the range value between any two of them. Even more preferably, it is 2 μm - 3.5 μm, including but not limited to any point value among 2 μm, 2.5 μm, 3 μm, 3.5 μm or the range value between any two of them.

[0073] In one embodiment, the particle size distribution width SPAN 2 of the lithium-rich and sodium-rich manganese-based material is preferably 0.5 - 1.5, including but not limited to any point value among 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5 or the range value between any two of them. More preferably, it is 0.6 - 1.2, including but not limited to any point value among 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2 or the range value between any two of them.

[0074] In one embodiment, the tap density PD 2 of the lithium-rich and sodium-rich manganese-based material is preferably 2.7 g / cm 3 - 2.9 g / cm 3 , including but not limited to any point value among 2.7 g / cm 3 , 2.75 g / cm 3 , 2.8 g / cm 3 , 2.85 g / cm 3 , 2.9 g / cm 3 or the range value between any two of them.

[0075] In one embodiment, the specific surface area of the lithium-rich and sodium-rich manganese-based material is preferably 1 m 2 / g - 4 m 2 / g, including but not limited to any point value among 1 m 2 / g, 2 m 2 / g, 3 m 2 / g, 4 m 2Any point value in / g or a range value between any two of them.

[0076] In one embodiment, the lithium-rich and sodium-rich manganese-based material has a layered structure.

[0077] In one embodiment, in the X-ray diffraction pattern of the lithium-rich and sodium-rich manganese-based material, the diffraction peak intensities of (002), (003), (104), and (101) are denoted as I (002) , I (003) , I (104) , I (101) , 0.01 ≤ I (002) / [I (003) + I (104) + I (101) ≤ 0.5. Preferably, 0.02 ≤ I (002) / [I (003) + I (104) + I (101) ≤ 0.4. More preferably, 0.05 ≤ I (002) / [I (003) + I (104) + I (101) ≤ 0.2. It should be noted that (002) represents the diffraction peak of the P2 phase, and (003), (104), and (101) represent the three strongest diffraction peaks of the O3 phase. By regulating the proportion of the P2 phase in the lithium-rich and sodium-rich manganese-based material, it is beneficial to reduce the residual alkali of the material, further improve the structural stability and kinetic performance, and thus enhance the cycling performance.

[0078] In one embodiment, the chemical formula of the lithium-rich and sodium-rich manganese-based material is Li 1+m Na n Ni 1-c-d-e Co c Mn d M e O f E g, where \(0\leq m\leq0.3\), \(0.05\leq n\leq0.3\), and \(0.1\leq m + n\leq0.5\), \(0.2\leq1 - c - d - e\leq0.4\), \(0\leq c\leq0.1\), \(0.5\leq d\leq0.8\), \(0\lt e\leq0.05\), \(0\leq g\leq0.1\), and \(f + g=2 + m + n\). Preferably, \(0.1\leq m\leq0.3\), \(0.05\leq n\leq0.25\), \(0.15\leq m + n\leq0.5\), \(0.25\leq1 - c - d - e\leq0.4\), \(0.005\leq c\leq0.09\), \(0.6\leq d\leq0.8\), \(0.001\leq e\leq0.05\), \(0.005\leq g\leq0.08\). More preferably, \(0.15\leq m\leq0.3\), \(0.05\leq n\leq0.2\), \(0.2\leq m + n\leq0.5\), \(0.25\leq1 - c - d - e\leq0.35\), \(0.005\leq c\leq0.08\), \(0.6\leq d\leq0.7\), \(0.002\leq e\leq0.04\), \(0.005\leq g\leq0.05\); \(M\) represents a cation-doped element, and \(M\) is selected from at least one of \(W\), \(Mo\), \(Nb\), \(Ta\), \(V\), \(Te\), \(Sb\), \(Ce\), \(Ti\), \(Zr\), \(Sn\), \(B\), \(Cr\), \(Fe\), \(Al\), \(La\), \(Sc\), \(Sm\), \(Y\), \(Ba\), \(Mg\), \(Sr\), \(Zn\), \(Cu\), \(K\). Preferably, \(M\) is selected from at least one of \(W\), \(Mo\), \(Nb\), \(Te\), \(Sb\), \(Ti\), \(Cr\), \(Al\). More preferably, \(M\) is selected from at least one of \(W\), \(Nb\), \(Ti\); \(E\) represents an anion-doped element, and \(E\) is selected from at least one of \(F\), \(Cl\), \(I\), \(S\). Preferably, \(E\) is selected from at least one of \(F\), \(Cl\), \(I\). More preferably, \(E\) is selected from at least one of \(F\), \(Cl\).

[0079] In one embodiment, the composite cathode material further includes lithium iron manganese phosphate material, and the median particle size of the lithium-rich and sodium-rich manganese-based material is greater than the median particle size of the lithium iron manganese phosphate material.

[0080] When the composite cathode material includes lithium manganate material, lithium-rich and sodium-rich manganese-based material, and lithium iron manganese phosphate material, the tap density \(PD\) of the composite cathode material satisfies: \(1.05\times(X 1 \times PD 1 +X 2 \times PD 2 +X 3 \times PD 3 )\lt PD\lt1.2\times(X 1 \times PD 1 +X 2 \times PD 2 +X 3 \times PD 3 ), and \(PD\gt1.02\times max\{PD 1 , PD 2 , PD 3 \}. Preferably, \(PD\gt1.03\times max\{PD 1 , PD 2, PD 3}; Further preferably, PD > 1.04×max{PD 1 , PD 2 , PD 3}. Wherein, X 1 represents the mass fraction of lithium manganate material in the composite cathode material, 50% ≤ X 1 ≤ 70%, PD 1 represents the tap density of the lithium manganate material, X 2 represents the mass fraction of lithium-rich and sodium-rich manganese-based material in the composite cathode material, 20% ≤ X 2 ≤ 40%, PD 2 represents the tap density of the lithium-rich and sodium-rich manganese-based material, X 3 represents the mass fraction of lithium iron phosphate manganese material in the composite cathode material, 5% ≤ X 3 ≤ 20%, PD 3 represents the tap density of the lithium iron phosphate manganese material, max represents taking the maximum value of PD 1 , PD 2 , PD 3 .

[0081] In the present invention, by blending lithium manganate material, lithium-rich and sodium-rich manganese-based material, and lithium iron phosphate manganese material, the lithium iron phosphate manganese material with the smallest particle size can coat the surface of the lithium manganate material and / or the lithium-rich and sodium-rich manganese-based material, greatly improving the electrochemical performance, especially the cycling performance, of the composite cathode material. In addition, by controlling the mass fractions and particle size differences of the lithium manganate material, the lithium-rich and sodium-rich manganese-based material, and the lithium iron phosphate manganese material, the tap density of the composite cathode material can also be greatly increased, significantly improving the battery energy density.

[0082] Specifically, the mass fraction X 1 of the lithium manganate material in the composite cathode material includes but is not limited to any one value or the range value between any two of 50%, 55%, 60%, 65%, 70%; the mass fraction X 2 of the lithium-rich and sodium-rich manganese-based material in the composite cathode material includes but is not limited to any one value or the range value between any two of 20%, 25%, 30%, 35%, 40%; the mass fraction X 3 of the lithium iron phosphate manganese material in the composite cathode material includes but is not limited to any one value or the range value between any two of 5%, 10%, 15%, 20%.

[0083] In one embodiment, the particle size distribution width SPAN of the composite cathode material ≥ 1.3×(SPAN 1 + SPAN 2 + SPAN 3 ) / 3, wherein, SPAN 1Represents the particle size distribution width of lithium manganate material, SPAN 2 Represents the particle size distribution width of lithium-rich and sodium-rich manganese-based materials, SPAN 3 Represents the particle size distribution width of lithium iron manganese phosphate material.

[0084] In one embodiment, the difference between the median particle size of the lithium-rich and sodium-rich manganese-based material and the median particle size of the lithium iron manganese phosphate material is 2 μm - 5 μm, including but not limited to any point value among 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 5 μm or the range value between any two of them.

[0085] In one embodiment, the median particle size of the lithium iron manganese phosphate material is preferably 0.5 μm - 2 μm, including but not limited to any point value among 0.5 μm, 1 μm, 1.5 μm, 2 μm or the range value between any two of them. Further preferably, it is 0.5 μm - 1.5 μm, including but not limited to any point value among 0.5 μm, 1 μm, 1.5 μm or the range value between any two of them.

[0086] In one embodiment, the D of the lithium iron manganese phosphate material 10 is preferably 0.1 μm - 1 μm, including but not limited to any point value among 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm or the range value between any two of them. Further preferably, it is 0.1 μm - 0.8 μm, including but not limited to any point value among 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm or the range value between any two of them. Even more preferably, it is 0.1 μm - 0.6 μm, including but not limited to any point value among 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm or the range value between any two of them.

[0087] In one embodiment, the particle size distribution width SPAN of the lithium iron manganese phosphate material 3 is preferably 1.0 - 3.0, including but not limited to any point value among 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0 or the range value between any two of them. Further preferably, it is 1.2 - 2.8, including but not limited to any point value among 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8 or the range value between any two of them.

[0088] In one embodiment, the tap density PD of the lithium iron manganese phosphate material 3 is preferably 2.0 g / cm 3 - 2.5 g / cm 3 , including but not limited to any point value between 2.0 g / cm 3 and 2.5 g / cm 3 , such as 2.0 g / cm 3 , 2.1 g / cm 3 , 2.2 g / cm 3 , 2.3 g / cm 3 , 2.4 g / cm 3 - 2.5 g / cm 3 , including but not limited to any point value between 2.1 g / cm 3 and 2.5 g / cm 3 , such as 2.1 g / cm 3 , 2.2 g / cm 3 , 2.3 g / cm 3 , 2.4 g / cm

[0089] In one embodiment, the specific surface area of the lithium iron manganese phosphate material is preferably 15 m 2 / g - 25 m 2 / g, including but not limited to any point value between 15 m 2 / g and 25 m 2 / g, such as 15 m 2 / g, 16 m 2 / g, 17 m 2 / g, 18 m 2 / g, 19 m 2 / g, 20 m 2 / g, 21 m 2 / g, 22 m 2 / g, 23 m 2 / g, 24 m 2 / g - 24 m 2 / g, including but not limited to any point value between 16 m 2 / g and 24 m 2 / g, such as 16 m 2 / g, 17 m 2 / g, 18 m 2 / g, 19 m 2 / g, 20 m 2 / g, 21 m 2 / g, 22 m 2 / g, 23 m 2 / g - 22 m2 / g, including but not limited to 16 m 2 / g, 17 m 2 / g, 18 m 2 / g, 19 m 2 / g, 20 m 2 / g, 21 m 2 / g, 22 m 2 Any point value within or range value between any two of / g, including but not limited to 16 m / g, 17 m / g, 18 m / g, 19 m / g, 20 m / g, 21 m / g, 22 m / g.

[0090] In one embodiment, the lithium iron manganese phosphate material has an olivine crystal structure.

[0091] In one embodiment, the chemical formula of the lithium iron manganese phosphate material is Li 1+y Mn p Fe q Q 1-p-q PO 4 @C, where 0 ≤ y ≤ 0.1, 0.4 ≤ p < 1, 0 < q ≤ 0.6, 0 ≤ 1 - p - q ≤ 0.05. Preferably, 0 ≤ y ≤ 0.08, 0.6 ≤ p ≤ 0.8, 0.2 ≤ q ≤ 0.4, 0 ≤ 1 - p - q ≤ 0.04. More preferably, 0.01 ≤ y ≤ 0.06, 0.6 ≤ p ≤ 0.7, 0.2 ≤ q ≤ 0.3, 0.001 ≤ 1 - p - q ≤ 0.03; Q is selected from at least one of V, Nb, Ti, Zr, Al, Mg, Ni, Co, Zn. Preferably, Q is selected from at least one of Ti, Mg, Ni, Co, Zn. It should be noted that @C represents carbon-coated lithium iron manganese phosphate, and the mass fraction of carbon in the lithium iron manganese phosphate is 1% - 3%. Preferably, the mass fraction of carbon in the lithium iron manganese phosphate is 1% - 2%.

[0092] In one embodiment, the median particle size of the composite cathode material is preferably 3 μm - 15 μm, including but not limited to any point value within or range value between any two of 3 μm, 4 μm, 5 μm, 6 μm, 8 μm, 10 μm, 12 μm, 13 μm, 14 μm, 15 μm.

[0093] In one embodiment, the D 10 of the composite cathode material is preferably 1 μm - 4 μm, including but not limited to any point value within or range value between any two of 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm. More preferably, it is 1 μm - 3 μm, including but not limited to any point value within or range value between any two of 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm.

[0094] In one embodiment, the particle size distribution width of the composite cathode material preferably has SPAN ≥ 2.0, more preferably SPAN ≥ 2.2, and still more preferably SPAN ≥ 2.5.

[0095] In one embodiment, the tap density PD of the composite cathode material is preferably ≥ 2.9 g / cm 3 , more preferably ≥ 3.0 g / cm 3 .

[0096] In one embodiment, the specific surface area of the composite cathode material is preferably 0.5 m 2 / g - 6 m 2 / g, more preferably 0.6 m 2 / g - 5 m 2 / g, and still more preferably 0.6 m 2 / g - 4 m 2 / g.

[0097] In one embodiment, the composite cathode material has a spherical structure, and the spherical structure is formed by the aggregation of secondary particles. The secondary particles are composed of primary particles and / or primary lamellae. Specifically, when the composite cathode material includes lithium manganate material, lithium-rich and sodium-rich manganese-based material, and lithium iron phosphate manganese material, at least part of the lithium iron phosphate manganese material is coated on the surface of the lithium manganate material and / or the lithium-rich and sodium-rich manganese-based material, and there is also part of the lithium iron phosphate manganese material filled in the voids between adjacent large particles.

[0098] In one embodiment, in the 3.00 V - 4.35 V electrochemical window, the room temperature half-cell 0.1C discharge capacity of the composite cathode material is ≥ 123 mAh / g, the initial efficiency is ≥ 94%, the 2C discharge capacity is ≥ 113 mAh / g, the 3C discharge capacity is ≥ 108 mAh / g, and (3C discharge capacity / 0.1C discharge capacity × 100)% ≥ 85%. Preferably, in the 3.00 V - 4.35 V electrochemical window, the room temperature half-cell 0.1C discharge capacity of the composite cathode material is ≥ 124 mAh / g, the initial efficiency is ≥ 94%, the 2C discharge capacity is ≥ 114 mAh / g, the 3C discharge capacity is ≥ 109 mAh / g, and (3C discharge capacity / 0.1C discharge capacity × 100)% ≥ 85%. More preferably, in the 3.00 V - 4.35 V electrochemical window, the room temperature half-cell 0.1C discharge capacity of the composite cathode material is ≥ 125 mAh / g, the initial efficiency is ≥ 95%, the 2C discharge capacity is ≥ 115 mAh / g, the 3C discharge capacity is ≥ 110 mAh / g, and (3C discharge capacity / 0.1C discharge capacity × 100)% ≥ 85%.

[0099] In one embodiment, in the electrochemical window of 2.95V - 4.30V, the capacity retention rate of the composite cathode material soft-pack full cell at high temperature (45°C) with 1C charge-discharge for 100 cycles is ≥92%. Preferably, in the electrochemical window of 2.95V - 4.30V, the capacity retention rate of the composite cathode material soft-pack full cell at high temperature (45°C) with 1C charge-discharge for 100 cycles is ≥93%. Further preferably, in the electrochemical window of 2.95V - 4.30V, the capacity retention rate of the composite cathode material soft-pack full cell at high temperature (45°C) with 1C charge-discharge for 100 cycles is ≥94%.

[0100] It should be noted that the present invention does not limit the specific preparation method of the composite cathode material. The composite cathode material can be prepared by mixing lithium manganate material with lithium-rich and sodium-rich manganese-based material, or by mixing lithium manganate material with lithium iron phosphate manganese material and then mixing with lithium-rich and sodium-rich manganese-based material. It can be understood that the present invention does not limit the specific preparation methods of lithium manganate material, lithium iron phosphate manganese material and lithium-rich and sodium-rich manganese-based material, and existing preparation processes can be adopted.

[0101] In one embodiment, it is preferred to mix lithium manganate material with lithium-rich and sodium-rich manganese-based material to obtain the composite cathode material. For example: mixing a lithium source, a manganese source and a cationic additive, and obtaining the lithium manganate material through sintering, cooling, crushing and sieving; mixing a lithium source, a sodium source, a manganese-based precursor and a cationic additive, and obtaining the lithium-rich and sodium-rich manganese-based material through sintering, cooling, crushing and sieving, and then washing and drying; mixing the obtained lithium manganate material with the lithium-rich and sodium-rich manganese-based material to obtain the composite cathode material.

[0102] In another embodiment, it is preferred to mix a lithium source, a manganese source and a cationic additive, and obtain the lithium manganate material through sintering, cooling, crushing and sieving; mixing a lithium source, a manganese source, an iron source, phosphate, an additive, a carbon source and deionized water, grinding, and then obtaining the lithium iron phosphate manganese material through spray drying, sintering, cooling, crushing and sieving; mixing the obtained lithium manganate material with the lithium iron phosphate manganese material to obtain a mixture; mixing a lithium source, a sodium source, a manganese-based precursor and a cationic additive, and obtaining the lithium-rich and sodium-rich manganese-based material through sintering, cooling, crushing and sieving, and then washing and drying; mixing the obtained mixture with the lithium-rich and sodium-rich manganese-based material to obtain the composite cathode material.

[0103] By first mixing large-particle-size lithium manganate material with small-particle-size lithium iron phosphate manganese material, it is beneficial to improve the coating effect of lithium iron phosphate manganese material on lithium manganate material, and then mixing with medium-particle-size lithium-rich and sodium-rich manganese-based material, so that part of the lithium iron phosphate manganese material fills the voids between the particles, which can not only significantly improve the electrochemical performance of the composite cathode material, but also be beneficial to further improving the tap density of the composite cathode material.

[0104] It is understandable that the lithium iron manganese phosphate material can also be mixed with the lithium manganese oxide material and the lithium-rich and sodium-rich manganese-based material respectively to form two mixtures, and then the two mixtures are mixed to prepare a composite cathode material, so that the surfaces of the lithium manganese oxide material and the lithium-rich and sodium-rich manganese-based material are coated with the lithium iron manganese phosphate material. This invention will not elaborate on this any further.

[0105] Specifically, in the step of preparing the lithium manganese oxide material, the lithium source is selected from at least one of Li 2 CO 3 , LiOH, LiOH·H 2 O, LiNO 3 , Li 2 SO 4 . The manganese source is preferably (quasi) spherical Mn 3 O 4 . The cationic additive is selected from at least one of the oxide containing G element, the hydroxide containing G element, the phosphate containing G element, the carbonate containing G element, the chloride containing G element, the fluoride containing G element, the iodide containing G element, and the sulfide containing G element. The G element is selected from at least one of W, Mo, V, Ta, Nb, P, Zr, Ti, Cr, Al, Fe, La, Ce, Nd, Sm, Gd, Tm, Bi, Co, Mg, Ni, Zn. In addition to at least one of the above-mentioned chloride, fluoride, iodide, and sulfide containing G element, the anionic additive can also be selected from at least one of the lithium salts containing F, Cl, I, S.

[0106] The sintering process is preferably as follows: heating to a pre-sintering temperature of 450°C - 650°C at a rate of 1°C / min - 15°C / min, holding for 2h - 10h, then heating to a sintering temperature of 650°C - 900°C, holding for 6h - 20h, and then cooling to an annealing temperature of 500°C - 700°C at a rate of 0.2°C / min - 5°C / min, holding for within 8h, and finally cooling naturally.

[0107] Specifically, in the step of preparing the lithium-rich and sodium-rich manganese-based material, the lithium source is selected from at least one of Li 2 CO 3 , LiOH, LiOH·H 2 O, LiNO 3 , Li 2 SO 4 . The sodium source is selected from at least one of Na 2 CO 3 , NaOH, Na 2 SO 4 , Na 2 C 2 O 4 . The manganese-based precursor is selected from Ni a Cob Mn c (OH) 2 、Ni a Co b Mn c CO 3 、Ni a Co b Mn c At least one of O, where 0.25 < a ≤ 0.35, 0.005 ≤ b ≤ 0.08, 0.6 ≤ c < 0.7, and a + b + c = 1. The cationic additive is selected from at least one of oxides containing element J, hydroxides containing element J, phosphates containing element J, carbonates containing element J, chlorides containing element J, fluorides containing element J, iodides containing element J, and sulfides containing element J. Element J is selected from at least one of W, Mo, Nb, Ta, V, Te, Sb, Ce, Ti, Zr, Sn, B, Cr, Fe, Al, La, Sc, Sm, Y, Ba, Mg, Sr, Zn, Cu, K. In addition to at least one of the above chlorides, fluorides, iodides, and sulfides containing element J, the anionic additive can also be selected from at least one of lithium salts containing F, Cl, I, S.

[0108] The sintering process is preferably as follows: heating to a pre-sintering temperature of 300°C - 800°C at a rate of 1°C / min - 15°C / min, holding for within 6 h, and then heating to a sintering temperature of 800°C - 1000°C, holding for 6 h - 20 h and then naturally cooling.

[0109] The water washing process is preferably as follows: quickly adding the product after sintering and crushing under the condition of stirring deionized ultrapure water, stirring for a certain time, then dehydrating and drying. Among them, the water temperature is within 25°C, the water-to-material ratio is 0.5:1 - 5:1, the water washing time is 1 min - 10 min, the stirring speed is 100 rpm - 500 rpm, the dehydration method is selected from one of suction filtration, centrifugation, and pressure filtration, the drying method is selected from air drying or vacuum drying, the drying temperature is 100°C - 200°C, and the drying time is 10 h - 24 h.

[0110] Specifically, in the step of preparing the lithium iron manganese phosphate material, the lithium source is selected from at least one of lithium carbonate, lithium hydroxide, lithium hydroxide monohydrate, lithium nitrate, lithium sulfate, lithium dihydrogen phosphate, lithium hydrogen phosphate, and lithium phosphate; the manganese source is selected from at least one of manganese dioxide, manganese carbonate, manganese tetroxide, manganese sesquioxide, manganese nitrate, and manganese dihydrogen phosphate; the iron source is selected from at least one of iron hydroxide, ferrous hydroxide, ferrous oxide, iron nitrate, iron phosphate, and iron sesquioxide; the phosphorus source is selected from at least one of lithium dihydrogen phosphate, ammonium dihydrogen phosphate, manganese dihydrogen phosphate, iron phosphate, phosphoric acid, lithium hydrogen phosphate, and lithium phosphate; the additive is selected from at least one of an oxide containing element X, a hydroxide containing element X, a phosphate containing element X, and a carbonate containing element X, where element X is selected from at least one of Ti, Zr, Al, Mg, Ni, Co, and Zn; and the carbon source is selected from at least one of sucrose, glucose, polyethylene glycol, and citric acid.

[0111] The sintering process is preferably as follows: heating to a pre-sintering temperature of 300°C - 550°C at a rate of 1°C / min - 15°C / min, holding for 2 h - 8 h, then heating to a sintering temperature of 600°C - 800°C, and naturally cooling after holding for 6 h - 20 h.

[0112] Specifically, in the steps of preparing the lithium manganese oxide material, the lithium-rich and sodium-rich manganese-based material, and the lithium iron manganese phosphate material, the crushing device is selected from at least one of a juicer, a mechanical mill, and a jaw crusher with opposing rollers.

[0113] Specifically, the mixing method of the lithium manganese oxide material and the lithium iron manganese phosphate material is selected from at least one of juicer mixing, high-speed mixing, plow blade mixing, and ball milling mixing, preferably ball milling mixing.

[0114] Specifically, the mixing device for the lithium manganese oxide material and the lithium-rich and sodium-rich manganese-based material, and the mixing device for the mixture and the lithium-rich and sodium-rich manganese-based material are selected from at least one of a juicer, a high-speed mixer, and a plow blade mixer.

[0115] The present invention also provides a positive electrode plate. The positive electrode plate includes a positive electrode current collector and a positive electrode active material layer, and the positive electrode active material layer contains the composite positive electrode material as described above. It can be understood that the positive electrode active material layer may also include materials such as a conductive agent and a binder, which are not limited in the present invention.

[0116] It should be noted that the present invention does not limit the preparation method of the positive electrode plate, and it can be prepared by a conventional process.

[0117] The present invention also provides a battery. The battery includes the positive electrode sheet as described above. It is understandable that the battery also includes a negative electrode sheet, a separator and an electrolyte, wherein the negative electrode sheet, the separator and the electrolyte can adopt any conventional commercially available negative electrode sheet (or negative electrode material), the separator and the electrolyte, and the present invention is not limited to this.

[0118] The present invention further provides an electrical device, comprising the battery as described above.

[0119] It is understandable that the above-mentioned power usage settings include any equipment that uses the above-mentioned batteries, such as electric vehicles, power tools, electronic products, energy storage systems, and office equipment, but are not limited thereto.

[0120] The composite positive electrode material, positive electrode sheet and battery will be further described below by the following specific examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If no specific conditions are specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are followed. The reagents or instruments used without indicating the manufacturer are all conventional products that can be purchased commercially.

[0121] Example 1

[0122] According to Li 1.06 Mn 1.85 La 0.05 Al 0.1 O 3.99 F 0.01 Weigh lithium carbonate and manganese tetraoxide (D 50 The mixture is mixed with lanthanum hydroxide, aluminum hydroxide and lithium fluoride, and mixed in a high-speed mixer. The mixture is loaded into a boat and put into a sintering furnace. The temperature is increased to 500°C at a rate of 3°C / min, and kept for 4 hours. The temperature is then increased to 850°C at a rate of 3°C / min, and kept for 12 hours. The temperature is then decreased to 700°C at a rate of 1°C / min, and kept for 2 hours. The mixture is cooled naturally, the sagger is taken out, the powder is crushed by a mechanical grinder, and the powder is sieved through a 325-mesh sieve to obtain the spinel lithium manganate material. Figure 1 This is a scanning electron microscope (SEM) image of the spinel lithium manganate material obtained in this embodiment. Figure 1 It can be seen that the morphology of the lithium manganese oxide material is a secondary sphere formed by the aggregation of primary particles.

[0123] According to Li 1.22 Na 0.1 (Ni 0.33 Co 0.03 Mn 0.64 ) 0.99 Nb 0.01 O 2.312 F 0.008 Weigh lithium carbonate, sodium carbonate, Ni0.33 Co 0.03 Mn 0.64 (OH) 2 Precursor (D 50 (about 3 μm), niobium pentoxide and lithium fluoride were added, mixed well in a high-speed mixer, loaded into boats and sliced, then put into a sintering furnace, heated to 600 °C at a rate of 5 °C / min, held for 6 h, then heated to 900 °C at a rate of 5 °C / min, held for 10 h, cooled naturally, the crucible was taken out, mechanically ground and pulverized, sieved through a 325-mesh sieve, then washed with deionized water, the water temperature was controlled at 0 °C, the water-to-material ratio was 2:1, stirred at 400 rpm, the washing time was 2 min, filtered by suction, and dried in a vacuum oven at 120 °C for 16 h to obtain a lithium-rich and sodium-rich manganese-based material. Figure 2 is the SEM image of the lithium-rich and sodium-rich manganese-based material prepared in this example. From Figure 2 it can be seen that the morphology of the lithium-rich and sodium-rich manganese-based material is secondary spheres formed by the aggregation of primary lamellae. Figure 3 is the XRD pattern of the lithium-rich and sodium-rich manganese-based material prepared in this example. From Figure 3 it can be seen that there are characteristic peaks of the P2 phase at diffraction angles of 15.5° - 16.5°.

[0124] The prepared spinel lithium manganate material and the lithium-rich and sodium-rich manganese-based material were mixed according to a mass ratio of 7:3 to obtain a composite cathode material. Figure 4 is the SEM image of the composite cathode material prepared in this example. Figure 5 is the particle size distribution diagram of the composite cathode material prepared in this example. It can be seen that the curve shows an obvious bimodal shape.

[0125] Example 2

[0126] The difference between Example 2 and Example 1 is that the mixing mass ratio of the spinel lithium manganate material and the lithium-rich and sodium-rich manganese-based material is 9:1.

[0127] Example 3

[0128] The difference between Example 3 and Example 1 is that the mixing mass ratio of the spinel lithium manganate material and the lithium-rich and sodium-rich manganese-based material is 8:2.

[0129] Example 4

[0130] The difference between Example 4 and Example 1 is that the mixing mass ratio of the spinel lithium manganate material and the lithium-rich and sodium-rich manganese-based material is 6:4.

[0131] Example 5

[0132] The difference between Example 5 and Example 1 is that the mixing mass ratio of the spinel lithium manganate material and the lithium-rich and sodium-rich manganese-based material is 5:5.

[0133] Example 6

[0134] According to Li 1.12 Mn 1.945 La 0.05 Nb 0.005 O 3.963 F 0.037 Weigh lithium carbonate and manganese tetraoxide (D 50 The mixture is mixed with lanthanum hydroxide, niobium pentoxide and lithium fluoride, and mixed in a high-speed mixer. The mixture is loaded into a boat and put into a sintering furnace. The temperature is increased to 550°C at a rate of 5°C / min, and kept for 6 hours. The temperature is then increased to 890°C at a rate of 5°C / min, and kept for 15 hours. The temperature is then decreased to 650°C at a rate of 0.5°C / min, and kept for 4 hours. The mixture is cooled naturally, the sagger is taken out, the powder is crushed by a mechanical grinder, and the powder is sieved through a 325-mesh sieve to obtain the spinel lithium manganate material.

[0135] According to Li 1.28 Na 0.06 (Ni 0.33 Co 0.01 Mn 0.66 ) 0.98 W 0.02 O 2.295 Cl 0.045 Weigh lithium carbonate, sodium carbonate, Ni 0.33 Co 0.01 Mn 0.66 (OH) 2 Precursor (D 50 The mixture is prepared by mixing tungsten trioxide and lithium chloride in a high-speed mixer, and then placed in a boat and put into a sintering furnace. The mixture is heated to 550°C at a rate of 4°C / min, kept warm for 4 hours, and then heated to 950°C at a rate of 4°C / min, kept warm for 14 hours, cooled naturally, taken out of the sagger, crushed by mechanical grinding, sieved through a 325-mesh sieve, and then washed with deionized water. The water temperature was controlled at 10°C, the water-to-material ratio was 3:1, stirred at 350rpm, washed for 3 minutes, filtered, and dried in a vacuum oven at 150°C for 15 hours to obtain a lithium-rich and sodium-rich manganese-based material.

[0136] The prepared spinel lithium manganate material and the lithium-rich sodium-rich manganese-based material are mixed in a mass ratio of 7:3 to obtain a composite positive electrode material.

[0137] Example 7

[0138] According to Li 1.01 Mn 1.90 La 0.05 Ni 0.05 O 3.98 Cl 0.02 Weigh lithium carbonate and manganese tetraoxide (D 50Approximately 3 μm), lanthanum hydroxide, nickel oxide, and lithium chloride were added, mixed evenly in a high-speed mixer, loaded into boats and cut into blocks, then placed in a sintering furnace. The temperature was raised to 490 °C at a rate of 5 °C / min, held for 5 h, then raised to 750 °C at a rate of 5 °C / min, held for 10 h, and then cooled to 680 °C at a rate of 0.8 °C / min, held for 3 h, and naturally cooled. The crucible was taken out, mechanically ground and pulverized, and sieved through a 325-mesh sieve to obtain the spinel lithium manganate material.

[0139] According to Li 1.26 Na 0.16 (Ni 0.33 Co 0.01 Mn 0.66 ) 0.973 Sr 0.027 O 2.394 Cl 0.026 Weigh lithium carbonate, sodium carbonate, Ni 0.33 Co 0.01 Mn 0.64 (OH) 2 precursor, strontium oxide, and lithium chloride, add them to a high-speed mixer and mix evenly, load into boats and cut into blocks, then place in a sintering furnace. The temperature is raised to 520 °C at a rate of 4 °C / min, held for 4 h, then raised to 830 °C at a rate of 4 °C / min, held for 10 h, and naturally cooled. The crucible is taken out, mechanically ground and pulverized, sieved through a 325-mesh sieve, and then washed with deionized water. The water temperature is controlled at 5 °C, the water-to-material ratio is 5:1, stirred at 200 rpm, the washing time is 8 min, centrifuged for dehydration, and dried in a vacuum oven at 180 °C for 12 h to obtain the lithium-rich and sodium-rich manganese-based material.

[0140] Mix the prepared spinel lithium manganate material and the lithium-rich and sodium-rich manganese-based material according to a mass ratio of 7:3 to obtain the composite cathode material.

[0141] Example 8

[0142] Mix the spinel lithium manganate material prepared in Example 6 and the lithium-rich and sodium-rich manganese-based material prepared in Example 7 according to a mass ratio of 7:3 to obtain the composite cathode material.

[0143] Example 9

[0144] Refer to the same method as in Example 1 to prepare the lithium manganate material and the lithium-rich and sodium-rich manganese-based material.

[0145] According to Li 1.03 Mn 0.59 Fe 0.39 Mg 0.02 PO 4 @1.0% C ratio, weigh lithium carbonate, manganese tetraoxide (D 50Approximately 3 μm), lithium iron phosphate, magnesium oxide and sucrose, dispersed in deionized water, milled for 3 h at 1500 rmp, spray-dried, with the inlet air temperature set at 200 °C and the outlet air temperature at 90 °C, and then the dried powder was sintered, heated to 450 °C at a rate of 5 °C / min, held for 4 h, then heated to 670 °C at a rate of 5 °C / min, held for 9 h, and naturally cooled to obtain lithium manganese iron phosphate material.

[0146] Weigh 60 parts of lithium manganese oxide material and 10 parts of lithium manganese iron phosphate material, put them into a ball mill for ball milling to obtain a mixture. Figure 6 This is the SEM image of the mixture of lithium manganese oxide material and lithium manganese iron phosphate material in this example. It can be seen that small-sized lithium manganese iron phosphate particles are evenly coated on the surface of lithium manganese oxide.

[0147] Then take 30 parts of lithium-rich and sodium-rich manganese-based material and mix it with the mixture to obtain a composite cathode material. Figure 7 This is the SEM image of the composite cathode material prepared in this example. It can be seen that the lithium manganese oxide material and the lithium-rich and sodium-rich manganese-based material are interspersed, and some extremely fine lithium manganese iron phosphate particles are coated on the surface of lithium manganese oxide, and some particles are filled and dispersed in the gaps between lithium manganese oxide and the lithium-rich and sodium-rich manganese-based material. Figure 8 This is the particle size distribution diagram of the composite cathode material prepared in this example. It can be seen that the curve shows an obvious three-peak pattern.

[0148] Example 10

[0149] Refer to the same method as in Example 1 to prepare lithium manganese oxide material and lithium-rich and sodium-rich manganese-based material.

[0150] According to Li 1.07 Mn 0.696 Fe 0.296 Ti 0.008 PO 4 @1.6%C Weigh lithium carbonate, manganese tetraoxide, iron phosphate, titanium dioxide and glucose, disperse them in deionized water, mill them for 4 h at 1400 rmp, spray-dry them, with the inlet air temperature set at 200 °C and the outlet air temperature at 90 °C, and then sinter the dried powder, heat it to 350 °C at a rate of 3 °C / min, hold for 6 h, then heat it to 650 °C at a rate of 3 °C / min, hold for 12 h, and naturally cool it to obtain lithium manganese iron phosphate material.

[0151] Weigh 60 parts of lithium manganese oxide material and 10 parts of the above-mentioned lithium manganese iron phosphate material, put them into a ball mill for ball milling to obtain a mixture. Then take 30 parts of lithium-rich and sodium-rich manganese-based material and mix it with the mixture to obtain a composite cathode material.

[0152] Example 11

[0153] The lithium manganate material and the lithium-rich and sodium-rich manganese-based material were prepared by referring to the same method as in Example 1.

[0154] According to Li 1.01 Mn 0.782 Fe 0.182 Al 0.036 PO 4 @2.4%C, lithium carbonate, manganese tetraoxide, iron phosphate, titanium dioxide and glucose were weighed, dispersed in deionized water, milled with sand at 1400 rmp for 4 h, spray-dried, with the inlet air temperature set at 200 °C and the outlet air temperature at 90 °C, and then the dried powder was sintered, heated to 350 °C at a rate of 3 °C / min, held for 6 h, then heated to 650 °C at a rate of 3 °C / min, held for 12 h, and cooled naturally to obtain the lithium iron manganese phosphate material.

[0155] 60 parts of the lithium manganate material and 10 parts of the above-mentioned lithium iron manganese phosphate material were weighed and put into a ball mill for ball milling to obtain a mixture. Then 30 parts of the lithium-rich and sodium-rich manganese-based material were mixed with the mixture by high-speed mixing to obtain the composite cathode material.

[0156] Example 12

[0157] The difference between Example 12 and Example 9 is that 50 parts of the lithium manganate material and 10 parts of the lithium iron manganese phosphate material were mixed and ball milled as a mixture, and then 40 parts of the lithium-rich and sodium-rich manganese-based material were mixed with the mixture by high-speed mixing to obtain the composite cathode material.

[0158] Example 13

[0159] The difference between Example 13 and Example 9 is that 70 parts of the lithium manganate material and 10 parts of the lithium iron manganese phosphate material were mixed and ball milled as a mixture, and then 20 parts of the lithium-rich and sodium-rich manganese-based material were mixed with the mixture by high-speed mixing to obtain the composite cathode material.

[0160] Example 14

[0161] The difference between Example 14 and Example 9 is that 55 parts of the lithium manganate material and 5 parts of the lithium iron manganese phosphate material were mixed and ball milled as a mixture, and then 40 parts of the lithium-rich and sodium-rich manganese-based material were mixed with the mixture by high-speed mixing to obtain the composite cathode material.

[0162] Example 15

[0163] The difference between Example 15 and Example 9 is that 60 parts of the lithium manganate material and 20 parts of the lithium iron manganese phosphate material were mixed and ball milled as a mixture, and then 20 parts of the lithium-rich and sodium-rich manganese-based material were mixed with the mixture by high-speed mixing to obtain the composite cathode material.

[0164] Example 16

[0165] Example 16 is different from Example 9 in that 55 parts of lithium manganese oxide material and 25 parts of lithium iron manganese phosphate material are weighed, put into a ball mill for ball milling to obtain a mixture, and then high-mixed with 20 parts of lithium-rich and sodium-rich manganese-based material to obtain a composite cathode material.

[0166] Example 17

[0167] Example 17 is different from Example 9 in that 58 parts of lithium manganese oxide material and 2 parts of lithium iron manganese phosphate material are weighed, put into a ball mill for ball milling to obtain a mixture, and then high-mixed with 40 parts of lithium-rich and sodium-rich manganese-based material to obtain a composite cathode material.

[0168] Example 18

[0169] Example 18 is different from Example 9 in that 75 parts of lithium manganese oxide material and 5 parts of lithium iron manganese phosphate material are weighed, put into a ball mill for ball milling to obtain a mixture, and then high-mixed with 20 parts of lithium-rich and sodium-rich manganese-based material to obtain a composite cathode material.

[0170] Example 19

[0171] Example 19 is different from Example 9 in that 50 parts of lithium manganese oxide material and 5 parts of lithium iron manganese phosphate material are weighed, put into a ball mill for ball milling to obtain a mixture, and then high-mixed with 45 parts of lithium-rich and sodium-rich manganese-based material to obtain a composite cathode material.

[0172] Example 20

[0173] Example 20 is different from Example 9 in that 70 parts of lithium manganese oxide material and 15 parts of lithium iron manganese phosphate material are weighed, put into a ball mill for ball milling to obtain a mixture, and then high-mixed with 15 parts of lithium-rich and sodium-rich manganese-based material to obtain a composite cathode material.

[0174] Comparative Example 1

[0175] The lithium manganese oxide material was prepared by referring to the same method as in Example 1, and the lithium manganese oxide material was directly used as the cathode material.

[0176] Comparative Example 2

[0177] The lithium-rich and sodium-rich manganese-based material was prepared by referring to the same method as in Example 1, and the lithium-rich and sodium-rich manganese-based material was directly used as the cathode material.

[0178] Comparative Example 3

[0179] Comparative Example 3 is different from Example 1 in that according to Li 1.32 (Ni 0.33 Co 0.03 Mn 0.64 ) 0.99 Nb 0.01 O 2.312 F0.008 Weigh lithium carbonate, Ni 0.33 Co 0.03 Mn 0.64 (OH) 2 precursor, niobium pentoxide and lithium fluoride, add them to a high-speed mixer to mix evenly, load them into boats and cut them into blocks, put them into a sintering furnace, heat them up to 600 °C at a rate of 5 °C / min, keep them at this temperature for 6 h, then heat them up to 900 °C at a rate of 5 °C / min, keep them at this temperature for 10 h, cool them naturally, take out the crucible, crush them with a mechanical grinder, and sieve them through a 325-mesh sieve to obtain a lithium-rich manganese-based material. Mix the spinel lithium manganate material and the lithium-rich manganese-based material prepared in Example 1 according to a mass ratio of 7:3 to obtain a composite cathode material.

[0180] Comparative Example 4

[0181] The difference between Comparative Example 4 and Example 1 is that the spinel lithium manganate material and the lithium-rich and sodium-rich manganese-based material are mixed according to a mass ratio of 4.5:5.5 to obtain a composite cathode material.

[0182] Comparative Example 5

[0183] The difference between Comparative Example 5 and Example 1 is that the spinel lithium manganate material and the lithium-rich and sodium-rich manganese-based material are mixed according to a mass ratio of 9.5:0.5 to obtain a composite cathode material.

[0184] Comparative Example 6

[0185] The difference between Comparative Example 6 and Example 9 is that 35 parts of lithium manganate material and 25 parts of lithium iron phosphate manganese material are weighed, put into a ball mill for ball milling to obtain a mixture, and then high-speed mixed with 40 parts of lithium-rich and sodium-rich manganese-based material to obtain a composite cathode material.

[0186] Comparative Example 7

[0187] The difference between Comparative Example 7 and Example 9 is that 48 parts of lithium manganate material and 2 parts of lithium iron phosphate manganese material are weighed, put into a ball mill for ball milling to obtain a mixture, and then high-speed mixed with 50 parts of lithium-rich and sodium-rich manganese-based material to obtain a composite cathode material.

[0188] Comparative Example 8

[0189] The difference between Comparative Example 8 and Example 9 is that 75 parts of lithium manganate material and 20 parts of lithium iron phosphate manganese material are weighed, put into a ball mill for ball milling to obtain a mixture, and then high-speed mixed with 5 parts of lithium-rich and sodium-rich manganese-based material to obtain a composite cathode material.

[0190] Physicochemical characterization was performed on the materials prepared in the above examples and comparative examples.

[0191] (1) Particle size: The particle size of the sample was measured using a laser particle size analyzer (Malvern, Master Sizer 2000). Specifically, a certain mass of the sample was added to a 50 mL beaker (the feeding amount was based on meeting the obscuration requirement), followed by the addition of sodium hexametaphosphate, and then approximately 20 mL of ultrapure water was added. The power was set to 120 W, the frequency was 53 Hz, and ultrasonic treatment was carried out for 5 minutes. After the ultrasonic treatment was completed, the particle size was measured using a MasterSizer 2000 particle size tester. The obscuration requirement was within the range of 8% - 12%, and the particle size test results were recorded.

[0192] (2) Specific surface area (BET): 5 g of the sample was taken and placed in a long tube with a bulb. First, vacuum treatment was carried out at 200 °C for 2 h, and then N 2 was introduced for gas adsorption. The adsorption amount of the positive electrode material sample for the adsorbate molecules (N 2 ) was determined based on the pressure or weight change before and after adsorption, and thus the specific surface area was obtained.

[0193] (3) Apparent density (PD): The apparent density of the sample was measured using a particle density analyzer (CARVER4350). Specifically, the sample was loaded into a mold with a cylinder height of 28 mm and a cylinder diameter of 9 mm, and held under a pressure of 3.5 T for a certain period of time, the pressure was reduced and then held for another period of time, and finally the apparent density was obtained based on the powder thickness.

[0194] The test results of the lithium manganate material, lithium-rich and sodium-rich manganese-based material, lithium iron phosphate manganese material prepared in the examples and the materials prepared in the comparative examples are shown in Table 1 and Table 2, and the calculation results are shown in Table 3.

[0195] Table 1

[0196]

[0197] Table 2

[0198]

[0199] Table 3

[0200]

[0201] The test results of the positive electrode materials prepared in the above examples and comparative examples are shown in Table 4.

[0202] Table 4

[0203]

[0204] The positive electrode materials obtained from the above examples and comparative examples were characterized for their half-cell rate performance at room temperature (25 °C): Using N-methylpyrrolidone (NMP) as the solvent, the positive electrode material was mixed with a conductive agent (SP) and a binder (PVDF) in a ratio of 94.5 wt%: 3 wt%: 2.5 wt%, and the mixture was stirred at 2000 r / min for 9 min to obtain a positive electrode active paste; The paste was evenly coated on aluminum foil using an automatic coater, vacuum dried at 110 °C for 30 min, punched into a pole piece with a diameter of 15 mm, and vacuum dried at 120 °C for 12 h. Then, a 1 mol / L LiPF 6 solution (solvent volume ratio EC: DMC: DEC = 1:1:1) was used as the electrolyte, a metallic lithium sheet was used as the negative electrode, and a CR2430 type button cell was assembled. The test voltage was 3.00 V - 4.35 V, the cut-off current was 0.05 C, charged and discharged at 0.1 C for 2 cycles (activation), charged and discharged at 0.33 C for 1 cycle, charged and discharged at 1 C for 1 cycle, charged at 1 C and discharged at 2 C for 1 cycle, charged at 1 C and discharged at 3 C for 1 cycle. The test results are shown in Table 5.

[0205] Table 5

[0206]

[0207] The positive electrode materials obtained from the above examples and comparative examples were characterized for their soft-pack full-cell performance at high temperature (45 °C): Using N-methylpyrrolidone (NMP) as the solvent, the positive electrode material was mixed with a conductive agent (SP) and a binder (PVDF) in a ratio of 94.5 wt%: 3 wt%: 2.5 wt%, and the mixture was stirred at 1500 r / min for 15 min to obtain a positive electrode active paste; The paste was evenly coated on aluminum foil using an automatic coater, and the areal density was 19 mg / cm 2 Then, a 1 mol / L LiPF 6 solution (solvent volume ratio EC: DMC: DEC = 1:1:1) was used as the electrolyte, graphite was used as the negative electrode, and the NP ratio was 1.12. A soft-pack full cell with a nominal capacity of 500 mAh was assembled, and the high-temperature cycle retention rate (charged and discharged at 1 C for 100 cycles at 45 °C) was tested. The test voltage was 2.95 V - 4.30 V, and the cut-off current was 0.05 C. The test results are shown in Table 6.

[0208] Table 6

[0209]

[0210] As can be seen from Table 4, Table 5 and Table 6, the compaction of the blended lithium manganate and lithium-rich and sodium-rich manganese-based cathode materials is significantly improved compared to that of a single cathode material, and it can better balance cycling and rate performance. When lithium iron manganese phosphate is added for blending, the compaction and capacity are further improved compared to the binary blending system, and the cycling performance can be made better without affecting the rate performance, showing great application prospects.

[0211] However, in the present invention, when the ratio deviates from the defined range, the compaction and electrical properties cannot be improved simultaneously or cannot be significantly improved. For example, for Comparative Example 3, although the compaction is as high as 3.03 g / cm 3 , the capacity is not improved, and the rate and cycling performance are poor; for Comparative Example 4, the capacity and cycling performance are relatively ideal, but the rate performance is poor and the compaction is low (the same situation applies to Comparative Example 6); for Comparative Example 5, the rate performance is good, but the compaction is extremely low, and the capacity and cycling performance are also poor. Examples are not given one by one here. In summary, in order to obtain a composite cathode material with excellent comprehensive performance, it is necessary to blend according to the ratio provided by the present invention.

[0212] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0213] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A composite positive electrode material, characterized in that: The composite cathode material includes lithium manganate material and lithium-rich and sodium-rich manganese-based material, and the median particle size of the lithium manganate material is greater than that of the lithium-rich and sodium-rich manganese-based material; The tap density PD of the composite cathode material satisfies: 1.05×(X1×PD1 + X2×PD2) < PD < 1.2×(X1×PD1 + X2×PD2), and PD > 1.02×max{PD1, PD2}, where X1 represents the mass fraction of the lithium manganate material in the composite cathode material, 50% ≤ X1 ≤ 90%, PD1 represents the tap density of the lithium manganate material, X2 represents the mass fraction of the lithium-rich and sodium-rich manganese-based material in the composite cathode material, 10% ≤ X2 ≤ 50%, PD2 represents the tap density of the lithium-rich and sodium-rich manganese-based material, and max represents taking the maximum value of PD1 and PD2; In the X-ray diffraction pattern of lithium-rich and sodium-rich manganese-based materials, the diffraction peak intensities of (002), (003), (104), and (101) are denoted as I (002) ,I (003) ,I (104) ,I (101) , 0.01≤I (002) / [I (003) +I (104) +I (101) ]≤0.5; The chemical formula of the lithium-rich and sodium-rich manganese-based material is Li 1+m Na n Ni 1-c-d-e Co c Mn d M e O f E g , where 0 ≤ m ≤ 0.3, 0.05 ≤ n ≤ 0.3, and 0.1 ≤ m + n ≤ 0.5, 0.2 ≤ 1 - c - d - e ≤ 0.4, 0 ≤ c ≤ 0.1, 0.5 ≤ d ≤ 0.8, 0 < e ≤ 0.05, 0 ≤ g ≤ 0.1, and f + g = 2 + m + n. M represents a cation doping element, and M is selected from at least one of W, Mo, Nb, Ta, V, Te, Sb, Ce, Ti, Zr, Sn, B, Cr, Fe, Al, La, Sc, Sm, Y, Ba, Mg, Sr, Zn, Cu, K. E represents an anion doping element, and E is selected from at least one of F, Cl, I, S.

2. The composite positive electrode material according to claim 1, characterized in that The particle size distribution width SPAN of the composite cathode material satisfies: SPAN ≥ 1.3×(SPAN1 + SPAN2) / 2, where SPAN1 represents the particle size distribution width of the lithium manganate material, and SPAN2 represents the particle size distribution width of the lithium-rich and sodium-rich manganese-based material.

3. The composite positive electrode material according to claim 1, characterized in that: The difference between the median particle size of the lithium manganate material and that of the lithium-rich and sodium-rich manganese-based material is 5 μm - 15 μm.

4. The composite positive electrode material according to claim 1, characterized in that The lithium manganate material satisfies at least one of the following conditions: (1)8μm≤D 50 ≤20μm; (2)3μm≤D 10 ≤7μm; (3) The particle size distribution width SPAN1 of the lithium manganate material is 1 - 2; (4) The compaction density PD1 of lithium manganese oxide material is 2.6g / cm 3 -2.9g / cm 3 ; (5) The specific surface area of ​​lithium manganese oxide material is 0.2m 2 / g-0.8m 2 / g; (6) The lithium manganate material has a spinel crystal structure; (7) The chemical formula of the lithium manganate material is Li 1+x Mn 2-a A a O4D b , where 0 ≤ x ≤ 0.2, 0 < a ≤ 0.2, 0 ≤ b ≤ 0.05, A represents a cation doping element, and A is selected from at least one of W, Mo, V, Ta, Nb, P, Zr, Ti, Cr, Al, Fe, La, Ce, Nd, Sm, Gd, Tm, Bi, Co, Mg, Ni, Zn; D represents an anion doping element, and D is selected from at least one of F, Cl, I, S.

5. The composite positive electrode material according to claim 1, characterized in that: The lithium-rich and sodium-rich manganese-based material satisfies at least one of the following conditions: (1)3μm≤D 50 ≤6μm; (2)1μm≤D 10 ≤4μm; (3) The particle size distribution width SPAN2 of the lithium-rich and sodium-rich manganese-based material is 0.5 - 1.5; (4) The compaction density PD2 of lithium-rich and sodium-rich manganese-based materials is 2.7 g / cm 3 -2.9g / cm 3 ; (5) The specific surface area of ​​lithium-rich and sodium-rich manganese-based materials is 1m 2 / g-4m 2 / g; (6) The lithium-rich and sodium-rich manganese-based material has a layered structure.

6. The composite positive electrode material according to claim 1, characterized in that: The composite cathode material further includes lithium iron manganese phosphate material, and the median particle size of the lithium-rich and sodium-rich manganese-based material is greater than that of the lithium iron manganese phosphate material; The tap density PD of the composite cathode material satisfies: 1.05×(X1×PD1 + X2×PD2 + X3×PD3) < PD < 1.2×(X1×PD1 + X2×PD2 + X3×PD3), and PD > 1.02×max{PD1, PD2, PD3}, where X1 represents the mass fraction of the lithium manganate material in the composite cathode material, 50% ≤ X1 ≤ 70%, PD1 represents the tap density of the lithium manganate material, X2 represents the mass fraction of the lithium-rich and sodium-rich manganese-based material in the composite cathode material, 20% ≤ X2 ≤ 40%, PD2 represents the tap density of the lithium-rich and sodium-rich manganese-based material, X3 represents the mass fraction of the lithium iron manganese phosphate material in the composite cathode material, 5% ≤ X3 ≤ 20%, PD3 represents the tap density of the lithium iron manganese phosphate material, and max represents taking the maximum value of PD1, PD2, and PD3.

7. The composite positive electrode material according to claim 6, characterized in that: The particle size distribution width SPAN of the composite cathode material satisfies: SPAN ≥ 1.3×(SPAN1 + SPAN2 + SPAN3) / 3, where SPAN1 represents the particle size distribution width of the lithium manganate material, SPAN2 represents the particle size distribution width of the lithium-rich and sodium-rich manganese-based material, and SPAN3 represents the particle size distribution width of the lithium iron manganese phosphate material.

8. The composite positive electrode material according to claim 6, characterized in that: The difference between the median particle size of the lithium-rich and sodium-rich manganese-based material and the median particle size of the lithium iron manganese phosphate material is 2 μm-5 μm.

9. The composite positive electrode material according to claim 6, characterized in that: The lithium manganese iron phosphate material meets at least one of the following conditions: (1)0.5μm≤D 50 ≤2μm; (2)0.1μm≤D 10 ≤1μm; (3) The particle size distribution width SPAN3 of lithium manganese iron phosphate material is 1.0-3.0; (4) The compaction density PD3 of lithium manganese iron phosphate material is 2.0g / cm 3 -2.5g / cm 3 ; (5) The specific surface area of ​​lithium manganese iron phosphate material is 15m 2 / g-25m 2 / g; (6) Lithium manganese iron phosphate material has an olivine crystal structure; (7) The chemical formula of the lithium iron manganese phosphate material is Li 1+y Mn p Fe q Q 1-p-q PO4@C, where 0 ≤ y ≤ 0.1, 0.4 ≤ p < 1, 0 < q ≤ 0.6, 0 ≤ 1 - p - q ≤ 0.05, and Q is selected from at least one of V, Nb, Ti, Zr, Al, Mg, Ni, Co, and Zn.

10. The composite positive electrode material according to any one of claims 1 to 9, characterized in that: The composite positive electrode material satisfies at least one of the following conditions: (1)3μm≤D 50 ≤15μm; (2)1μm≤D 10 ≤4μm; (3) The particle size distribution width SPAN of the composite positive electrode material is ≥ 2.0; (4) The compaction density of the composite positive electrode material is PD ≥ 2.9 g / cm 3 ; (5) The specific surface area of ​​the composite positive electrode material is 0.5m 2 / g-6m 2 / g.

11. A positive electrode sheet, characterized in that: The positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer, and the positive electrode active material layer comprises the composite positive electrode material according to any one of claims 1 to 10.

12. A battery, characterized in that: Comprising the positive electrode sheet as claimed in claim 11.

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