Battery cathode materials and their applications

Abstract

A battery positive electrode material is provided, the battery positive electrode material comprising: lithium manganese iron phosphate particles; and active particles dispersed in the gaps between the lithium manganese iron phosphate particles, the active particles being selected from the group consisting of lithium nickel cobalt manganese oxide particles, lithium nickel cobalt aluminate particles, lithium-rich manganese-based material particles, lithium cobalt oxide particles, spinel lithium manganese oxide LiMn 2 O 4 Particles and layered lithium manganese oxide LiMnO 2 The present invention also provides an application of the above-mentioned battery positive electrode material, wherein the ratio of the median size of the lithium manganese iron phosphate to the active particles is 3 to 8, and the mass percentage of the lithium manganese iron phosphate in the battery positive electrode material is 70% to 90%, and the mass percentage of the active particles is 10% to 30%.

Description

[Technical Field]

[0001] This application claims priority to Chinese Patent Application No. 202111126603.2, filed on September 24, 2021, entitled "Battery Positive Electrode Material and Its Application," the entire contents of which are incorporated herein by reference.

[0002] This application relates to the field of secondary batteries, and more particularly to battery cathode materials and their applications. [Background technology]

[0003] The phosphate-based material LiMPO4 (M = Fe, Mn, Ni, Co) has many advantages when used as a cathode material for secondary batteries, such as a stable structure, low reactivity with electrolytes, high safety, and good battery cycle characteristics. However, the low packing density and energy density of conventional phosphate-based batteries make them unsuitable for battery applications. Therefore, there is a need to develop a battery cathode material that allows the electrode plate to have a high packing density and allows the battery to have high energy density, high cycle stability, and high safety. Summary of the Invention

[0004] A battery positive electrode material according to a first aspect of the present application includes lithium manganese iron phosphate particles and active particles filled in gaps between the lithium manganese iron phosphate particles, the active particles including one or more of lithium nickel cobalt manganese oxide particles, lithium nickel cobalt aluminate particles, lithium-rich manganese-based material particles, lithium cobalt oxide particles, spinel lithium manganese oxide LiMn2O4 particles, and layered lithium manganese oxide LiMnO2 particles, and the lithium manganese iron phosphate particle and the active particles have a median diameter ratio of 3 to 8. particle The mass percentage of the active particles is 10% to 30%.

[0005] In one embodiment of the present application, the median diameter of the lithium iron manganese phosphate particles is 2 μm to 15 μm.

[0006] In one embodiment of the present application, the median diameter of the active particles is between 0.5 μm and 5 μm.

[0007] In one embodiment of the present application, the active particles include primary active particles and secondary active particles, the median diameter of the primary active particles is 0.5 μm to 5 μm, and the median diameter of the secondary active particles is 0.1 μm to 2 μm.

[0008] In one embodiment of the present application, the mass ratio of the lithium iron manganese phosphate particles to the active particles is 1:(0.2-0.35).

[0009] In one embodiment of the present application, the lithium manganese iron phosphate particles are LiMn x Fe 1-x PO4, and 0.5≦x≦0.9.

[0010] In one embodiment of the present application, the lithium manganese iron phosphate particles contain carbon, and the mass percentage of the carbon in the lithium manganese iron phosphate particles is 1% to 3%.

[0011] In one embodiment of the present application, the lithium manganese iron phosphate particles further comprise a doping element, wherein the doping element comprises one or more of Ti, V, Co, Ni, Cu, Zn, Mg, Ca, Al, Nb, and Mo.

[0012] In one embodiment of the present application, the lithium nickel cobalt manganese oxide particles are LiNi a Co b Mn 1-a-b Contains O2, 0 <a<1、0<b<1、0<1-a-b<1である。

[0013] In one embodiment of the present application, the lithium nickel cobalt manganese oxide particles further comprise a doping element, wherein the doping element comprises one or more of Ti, V, Fe, Cu, Zn, Mg, Ca, Al, Nb, and Mo.

[0014] In one embodiment of the present application, the lithium nickel cobalt aluminate particles contain LiNi m Co n Al 1-m-n O2, where 0 < m < 1, 0 < n < 1, and 0 < 1 - m - n < 1.

[0015] In one embodiment of the present application, the lithium nickel cobalt aluminate particles further contain a doping element, and the doping element includes one or more of Ti, V, Mn, Fe, Cu, Zn, Mg, Ca, Nb, and Mo.

[0016] In one embodiment of the present application, the lithium-rich manganese-based material particles contain yLi2MnO3·(1 - y)LiMO2, where 0 < y < 1, and M includes at least one of Mn, Ni, or Co.

[0017] In one embodiment of the present application, the lithium-rich manganese-based material particles further contain a doping element, and the doping element includes one or more of Ti, V, Fe, Co, Cu, Zn, Mg, Ca, Nb, and Mo.

[0018] In one embodiment of the present application, the battery cathode material has a tap density of 2.4 g / cm 3 ~3.2 g / cm 3 .

[0019] In one embodiment of the present application, there is no agglomeration between the lithium iron manganese phosphate particles and the active particles, and the active particles are not coated and adhered to the particle surface of the lithium iron manganese phosphate particles.

[0020] In one embodiment of the present application, the active particles have a higher tap density than the lithium iron manganese phosphate particles.

[0021] The positive electrode plate according to the second aspect of the present application includes a current collector and a positive electrode material layer provided on the current collector, and the positive electrode material layer includes the battery cathode material described in the first aspect. <00002 A secondary battery according to a third aspect of the present application includes a positive electrode, a negative electrode, a separator, and an electrolyte solution, and the positive electrode includes the positive electrode plate according to the second aspect. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic structural diagram of a battery positive electrode material according to an embodiment of the present application. [Figure 2] 1 is a schematic structural diagram of a positive electrode material according to the present application. [Figure 3] 1 is a schematic structural diagram of a battery positive electrode material according to an embodiment of the present application. [Figure 4] 1 is a scanning electron microscope photograph of a battery positive electrode material according to Example 1 of the present application.

[0024] The schematic structural diagram of the battery positive electrode material shows the particle distribution in two dimensions, but in reality it should be a three-dimensional perspective view. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, the technical means in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, but not all of them, and all other embodiments that can be obtained by those skilled in the art based on the embodiments of the present application without any creative work are all within the scope of protection of the present application.

[0026] Phosphate positive electrode materials, such as lithium iron phosphate, have advantages such as long cycle life, high safety, environmental friendliness, and low cost, making them an important part of the lithium-ion battery positive electrode material system. Compared to lithium iron phosphate, lithium manganese iron phosphate has a higher theoretical energy density, but its electron and ion transport rate is slow, limiting its capacity. To improve the conductivity of lithium manganese iron phosphate positive electrode materials, carbon coating is required, but the introduction of carbon reduces the compaction density of the material. To improve the compaction density of the positive electrode material, the present application provides a battery positive electrode material with high gravimetric energy density and high volumetric energy density by blending different components in consideration of particle size distribution. Batteries using this battery positive electrode material have high energy density, high safety performance, and excellent low-temperature performance. 1 is a schematic structural diagram of a battery cathode material according to one embodiment of the present invention. As shown in FIG. 1, the battery cathode material 10 of the present invention includes lithium manganese iron phosphate particles 11 and active particles 12 dispersed in the gaps between the lithium manganese iron phosphate particles. In the present invention, the active particles and the lithium manganese iron phosphate particles form a physically mixed system, with the smaller active particles filling the gaps between the lithium manganese iron phosphate particles. Furthermore, in the battery cathode material of the present invention, there is no agglomeration between the particles, and the smaller particles are not coated on or attached to the surfaces of the larger particles, but rather accumulate with the larger particles in a single dispersed state to form a physically mixed system.

[0027] In the cathode material of the present application, the lithium iron manganese phosphate particles have a large particle size, and the active particles with a small particle size can be filled in the gaps between the lithium iron manganese phosphate particles. Since the active particles have a higher tap density than the lithium iron manganese phosphate particles, without changing the volume of the whole material, by significantly improving the tap density of the whole material, the cathode material of the battery has a high volume energy density. Also, since the active particles have a higher mass specific capacity and voltage than the lithium iron manganese phosphate particles, the cathode material of the battery also has a high weight energy density. In addition, the active particles have excellent low-temperature performance and are helpful for improving the low-temperature performance of the cathode material of the battery.

[0028] In the present application, lithium iron manganese phosphate is LiMn x Fe 1-x PO4, where 0.5 ≤ x ≤ 0.9. In some embodiments of the present application, elements can be doped into the lithium iron manganese phosphate to improve its conductivity. The doping elements may be, for example, one or more of Ti, V, Co, Ni, Cu, Zn, Mg, Ca, Al, Nb, Mo. The mass percentage of the doping elements in all transition metal elements in the lithium iron manganese phosphate is 0.2% - 2%. In some embodiments of the present application, the lithium iron manganese phosphate further contains carbon with a mass percentage of 1% - 3%. A certain content of carbon is helpful for improving the conductivity of the cathode material of the battery.

[0029] In the present application, the active particles include one or more of lithium nickel cobalt manganese oxide particles, lithium nickel cobalt aluminum oxide particles, high-lithium-concentration manganese-based material particles, lithium cobalt oxide particles, and lithium manganese oxide particles. In the embodiments of the present application, the lithium nickel cobalt manganese oxide particles contain LiNi a Co b Mn 1-a-b O2, where 0 < a < 1, 0 < b < 1, and 0 < 1 - a - b < 1. The lithium nickel cobalt aluminum oxide particles contain LiNi m Co n Al 1-m-nContaining O₂, where 0 < m < 1, 0 < n < 1, and 0 < 1 - m - n < 1, the high-lithium-concentration manganese-based material particles contain yLi₂MnO₃·(1 - y)LiMO₂, where 0 < y < 1, M contains at least one of Mn, Ni, or Co, the chemical formula of lithium cobaltate particles is LiCoO₂, and the lithium manganese oxide particles contain one or more of spinel lithium manganese oxide LiMn₂O₄ or layered lithium manganese oxide LiMnO₂. Using the above active particles can not only improve the energy density of the battery cathode material, but also effectively improve the low-temperature performance of the battery, which is helpful for extending the service life of the battery. In some embodiments of the present application, a doping element is added to the active particles, and the doping element may be, for example, one or more of Ti, V, Co, Ni, Cu, Zn, Mg, Al, Ca, Nb, Mo. By adding a doping element to the active particles, the conductivity and cycle performance of the battery cathode material can be further improved.

[0030] In the present application, the active particles have a higher tap density than lithium iron manganese phosphate particles. For example, the tap density of lithium cobaltate is 4 g / cm 3 and the tap density of lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminate is 3.7 - 3.9 g / cm 3 and the tap density of lithium manganese oxide is 2.9 - 3.2 g / cm 3 Therefore, the active particles can also improve the volume energy density of the battery cathode material.

[0031] In the embodiments of the present application, the mass percentage of lithium iron manganese phosphate particles in the battery cathode material is 70% - 90%. Specifically, the mass percentage of lithium iron manganese phosphate particles in the battery cathode material is 70%、A high content of lithium manganese iron phosphate particles can ensure the battery positive electrode material has excellent safety and cycle performance, such as, but not limited to, 75%, 80%, 85%, or 90%. In the present embodiment, the mass percentage of the active particles in the battery positive electrode material is 10% to 30%, and the mass percentage of the active particles in the battery positive electrode material can be, but is not limited to, 10%, 15%, 20%, 25%, or 30%. When the content of the active particles is within this range, the gaps between the lithium manganese iron phosphate particles can be sufficiently filled, effectively improving the compaction density of the battery positive electrode material. When the content of the active particles is within this range, the safety of the battery positive electrode material is improved, and when the amount of active particles is within this range, the gaps between the lithium manganese iron phosphate particles do not further expand, thereby preventing a decrease in the compaction density.

[0032] In the present embodiment, the ratio of the median size of the lithium manganese iron phosphate particles to the active particles is 3 to 8. The ratio of the median size of the lithium manganese iron phosphate particles to the active particles may be, but is not limited to, 3, 4, 5, 6, 7, or 8. Controlling the ratio of the median size of the lithium manganese iron phosphate particles to the active particles ensures that particles of different sizes can achieve a good particle size distribution, thereby effectively reducing porosity. When the ratio of the median size of the lithium manganese iron phosphate particles to the active particles is within the above range, effective mixing of large and small particles can be achieved, reducing gaps between particles.

[0033] In the embodiment of the present application, the median diameter D of the lithium iron manganese phosphate particles 50 The median diameter D of the lithium manganese iron phosphate particles is 2 μm to 15 μm. 50 Specifically, the median diameter D of the lithium manganese iron phosphate particles may be, but is not limited to, 2 μm, 5 μm, 7 μm, 10 μm, or 15 μm. When the median diameter D of the lithium manganese iron phosphate particles is within the above range, the diffusion path of lithium ions can be prevented from becoming long, thereby improving the rate performance of the battery. In the embodiment of the present application, the median diameter D of the active particles is 50The median diameter D of the active particles is 0.5 μm to 5 μm. 50 Specifically, the median diameter of the active particles may be, but is not limited to, 0.5 μm, 1 μm, 3 μm, or 5 μm. When the median diameter of the active particles is within the above range, the porosity can be effectively reduced, and when the median diameter of the active particles is within the above range, an excellent packing effect can be achieved, thereby reducing the specific surface area of ​​the positive electrode material and improving processing performance.

[0034] In some embodiments of the present application, the mass ratio of the lithium manganese iron phosphate particles to the active particles is 1:(0.2-0.35). Specifically, the mass ratio of the lithium manganese iron phosphate particles to the active particles may be, but is not limited to, 1:0.2, 1:0.25, 1:0.3, or 1:0.35. By further controlling the mass ratio of the lithium manganese iron phosphate particles to the active particles while optimizing the particle size distribution between the large and small particles, the particle distribution can be optimized. The active particles with smaller particle sizes can be filled into the gaps between the lithium manganese iron phosphate particles with larger particle sizes. That is, the active particles can be directly filled into the gaps between the lithium manganese iron phosphate particles without destroying the original gap distribution of the lithium manganese iron phosphate particles. Furthermore, the number of active particles can be maintained within a reasonable range, preventing the active particles from piling up and reducing the gaps between the battery positive electrode materials. FIG. 2 is a schematic structural diagram of a cathode material according to the present application. As shown in FIG. 2, the particle size of the active particles in the cathode material is smaller than that of the lithium manganese iron phosphate particles, and the number of active particles is greater than that of the lithium manganese iron phosphate particles. Compared to the cathode material shown in FIG. 2, the cathode material shown in FIG. 1 has smaller active particle size and a reasonable number of active particles. This prevents the active particles from piling up and the formation of numerous voids between the active particles, thereby effectively improving the compaction density of the cathode material. In some embodiments of the present application, the percentage of lithium manganese iron phosphate particles per unit volume of the battery cathode material is 25% to 75%, where the percentage refers to the percentage of the number of lithium manganese iron phosphate particles relative to the total number of particles in the battery cathode material. Controlling the percentage of the lithium manganese iron phosphate particles can improve space efficiency and increase the volumetric energy density of the battery cathode material.

[0035] In some embodiments of the present application, the active particles include primary active particles and secondary active particles. That is, active particles of different particle sizes are used to fill the gaps between the lithium manganese iron phosphate particles. FIG. 3 is a schematic structural diagram of a battery cathode material according to one embodiment of the present application. As shown in FIG. 3, active particles 12 are filled in the gaps between the lithium manganese iron phosphate particles 11. The active particles 12 include primary active particles 121 and secondary active particles 122. The secondary active particles 122 are filled between the primary active particles 121 and the lithium manganese iron phosphate particles 11. In some embodiments of the present application, the median diameter of the primary active particles is 0.5 μm to 5 μm, and the median diameter of the secondary active particles is 0.1 μm to 2 μm. In some embodiments of the present application, the ratio of the median diameters of the primary active particles to the secondary active particles is 3 to 8. By controlling the ratio of the median diameters of the primary active particles and the secondary active particles, it is possible to ensure that the secondary active particles are further packed into the gaps between the primary active particles and the lithium manganese iron phosphate particles, and to sufficiently improve the compaction density of the battery positive electrode material.

[0036] In the present embodiment, the battery positive electrode material has a compacted density of 2.4 g / cm 3 ~3.2g / cm 3 The compaction density of the battery positive electrode material is specifically 2.4 g / cm 3 , 2.6g / cm 3 , 2.8g / cm 3 , 3.0g / cm 3 or 3.2 g / cm 3 The battery positive electrode material of the present application has a high compaction density, and when a positive electrode plate made of this material is applied to a battery, it can not only improve the safety and low-temperature performance of the battery, but also provide the battery with high volumetric energy density and weight energy density.

[0037] The method for producing the battery positive electrode material according to the present application includes: The method includes mixing lithium iron manganese phosphate particles with active particles, and the mixing method may be one or more of ball mill mixing, powder mixing, or liquid phase mixing.

[0038] The positive electrode plate according to the present application includes a current collector and a positive electrode material layer disposed on the current collector, the positive electrode material layer including the battery positive electrode material according to the present application. In the present application, the positive electrode material layer may be manufactured by mixing a battery positive electrode material, a conductive agent, a binder, and a solvent to form a positive electrode paste, and then applying and drying the positive electrode paste to obtain the positive electrode material layer. To manufacture the positive electrode paste, the binder and the solvent may be mixed, thoroughly stirred, and then the conductive agent is added. After stirring, the battery positive electrode material is added, and the mixture is stirred and sieved to obtain the positive electrode paste. The conductive agent, binder, and solvent are commonly selected in the battery field. For example, the binder may be one or more selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), styrene butadiene rubber (SBR), polyacrylonitrile (PAN), polyimide (PI), polyacrylic acid (PAA), polyacrylate, polyolefin, sodium carboxymethyl cellulose (CMC), and sodium alginate. The conductive agent may be one or more selected from carbon nanotubes, carbon black, and graphene.

[0039] The secondary battery according to the present application includes a positive electrode, a negative electrode, an electrolyte, and a separator located between the positive electrode and the negative electrode, and the positive electrode includes the positive electrode plate according to the present application.

[0040] In the present application, the negative electrode of the secondary battery may be any negative electrode known in the art. In the present embodiment, the negative electrode may include one or more of a carbon-based negative electrode, a silicon-based negative electrode, a tin-based negative electrode, and a lithium negative electrode. The carbon-based negative electrode may include graphite, hard carbon, soft carbon, graphene, etc. The silicon-based negative electrode may include a silicon-containing material such as silicon, silicon carbon, silicon oxygen, or a silicon metal compound, or a mixture of the silicon-containing material with a non-silicon-containing material such as graphite. The tin-based negative electrode may include a tin-containing material such as tin, tin carbon, tin oxygen, or a tin metal compound, or a mixture of the tin-containing material with a non-tin-containing material such as graphite. The lithium negative electrode may include metallic lithium or a lithium alloy. Specifically, the lithium alloy may be at least one of a lithium-silicon alloy, a lithium-sodium alloy, a lithium-potassium alloy, a lithium-aluminum alloy, a lithium-tin alloy, and a lithium-indium alloy. In some embodiments of the present application, the negative electrode current collector is copper foil, the negative electrode active material includes one or more of natural graphite, artificial graphite, hard carbon, soft carbon, lithium titanate, iron oxide, lithium titanium phosphate, titanium dioxide, silicon, silicon monoxide, tin and its oxides, and antimony and its oxides, and the binder is polyacrylic acid (PAA), polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), or the like. sodium and styrene butadiene rubber (SBR), and the conductive agent includes one or more of acetylene black, Ketjen black, Super-P, carbon nanotubes, carbon nanofibers, activated carbon, and graphene. In the present application, any method known in the art may be used as a method for manufacturing the negative electrode.

[0041] In the present application, the separator of the secondary battery may be any separator known to those skilled in the art, for example, the separator may be one or more of a polyolefin microporous membrane, polyethylene terephthalate, polyethylene felt, glass mat, or ultrafine glass fiber paper.

[0042] In the present application, the electrolyte of the secondary battery includes a solution formed by dissolving an electrolyte lithium salt in a non-aqueous solvent. In embodiments of the present application, the electrolyte lithium salt includes one or more of lithium hexafluorophosphate (LiPF), lithium perchlorate (LiClO), lithium tetrafluoroborate (LiBF), lithium hexafluoroarsenate (LiAsF), lithium hexafluorosilicate (LiSiF), lithium tetraphenylborate (LiB(CH)), lithium chloride (LiCl), lithium bromide (LiBr), lithium chloroaluminate (LiAlCl), lithium fluorohydrocarbon sulfonate (LiC(SOCF)), LiCHSO, LiN(SOCF), and LiN(SOCF) . In some embodiments of the present application, the non-aqueous solvent includes one or more of a chain acid ester and a cyclic acid ester. In some embodiments of the present application, the chain acid ester includes one or more of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC), and dipropyl carbonate (DPC). In some embodiments of the present application, the chain acid ester includes chain organic esters containing fluorine, sulfur, or an unsaturated bond. In some embodiments of the present application, the cyclic acid ester includes one or more of ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), γ-butyrolactone (γ-BL), and sultone. In some embodiments of the present application, the cyclic acid ester includes a cyclic organic ester containing fluorine, sulfur, or an unsaturated bond. In some embodiments of the present application, the non-aqueous solvent includes one or more of a chain ether solution and a cyclic ether solution. In some embodiments of the present application, the cyclic ether comprises one or more of tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHF), 1,3-dioxolane (DOL), and 4-methyl-1,3-dioxolane (4-MeDOL). In some embodiments of the present application, the cyclic ether comprises a cyclic organic ether containing fluorine, sulfur, or an unsaturated bond.In some embodiments of the present application, the chain ether includes one or more of dimethoxymethane (DMM), 1,2-dimethoxyethane (DME), 1,2-dimethoxypropane (DMP), and diglyme (DG). In some embodiments of the present application, the chain ether includes a chain organic ether containing fluorine, sulfur, or an unsaturated bond. In some embodiments of the present application, the concentration of the electrolyte lithium salt in the electrolyte solution is 0.1 mol / L to 15 mol / L. In some embodiments of the present application, the concentration of the electrolyte lithium salt is 1 mol / L to 10 mol / L.

[0043] In the embodiments of the present application, the secondary battery can be manufactured using either a lamination process or a winding process. In some examples of the present application, the battery is manufactured using a lamination process.

[0044] The technical means of the present application will be further described below by dividing it into several embodiments. [Example]

[0045] The method for producing the battery positive electrode material is as follows.

[0046] 800g of lithium manganese iron phosphate and 200g of lithium nickel cobalt manganese oxide were mixed in a mixer to obtain lithium manganese iron phosphate with the chemical formula LiMn 0.6 Fe 0.4 PO4, the carbon content of the lithium manganese iron phosphate is 1.5%, and the median diameter D 50 is 15 μm, and the chemical formula of lithium nickel cobalt manganese oxide is LiNi 0.8 Co 0.1 Mn 0.1 O2, and the median diameter of lithium nickel cobalt manganese oxide is D 50 The particle size is 3.2 μm, and the mixture is mechanically mixed at a speed of 30 rpm for 5 hours to obtain a battery positive electrode material.

[0047] The prepared battery cathode material, conductive agent, and binder were dispersed in N-methylpyrrolidone in a mass ratio of 90:5:5, where the conductive agent was carbon nanotubes and the binder was PVDF5130. The paste had a solid content of 50%. The paste was applied to the surface of aluminum foil at a coating density of 200 g / m. 2 After drying, the electrode plate is cut into 15 mm positive electrode plates and assembled with a separator and a lithium sheet to form a 2032 button-type half cell. [Example]

[0048] The method for producing the battery positive electrode material is as follows.

[0049] 800g of lithium manganese iron phosphate and 200g of lithium nickel cobalt manganese oxide were mixed in a ball mill to obtain lithium manganese iron phosphate with the chemical formula LiMn 0.6 Fe 0.4 PO4, the carbon content of the lithium manganese iron phosphate is 1.5%, and the median diameter D 50 is 15 μm, and the chemical formula of lithium nickel cobalt aluminate is LiNi 0.8 Co 0.15 Al 0.05 O2, and the median diameter of lithium nickel cobalt aluminate is D 50 The particle size is 3.2 μm, and after adding zirconium balls, the mixture is ball milled for 5 hours to obtain a battery positive electrode material. A battery is manufactured in the same manner as in Example 1. [Example]

[0050] The method for producing the battery positive electrode material is as follows.

[0051] Mix 800g of lithium manganese iron phosphate, 100g of lithium nickel cobalt manganese oxide, and 100g of lithium cobalt oxide (LiCoO2) in a ball mill to obtain lithium manganese iron phosphate with the chemical formula LiMn 0.6 Fe 0.4PO4, the carbon content of the lithium manganese iron phosphate is 1.5%, and the median diameter D 50 is 15 μm, and the chemical formula of lithium nickel cobalt manganese oxide is LiNi 0.8 Co 0.1 Mn 0.1 O2, and the median diameter of lithium nickel cobalt manganese oxide is D 50 The median diameter of the lithium cobalt oxide is 3.2 μm, and the zirconium balls are added, followed by ball milling for 5 hours to obtain a battery positive electrode material. A battery is manufactured in the same manner as in Example 1. [Example]

[0052] The method for producing the battery positive electrode material is as follows.

[0053] 800g of lithium manganese iron phosphate, 100g of lithium nickel cobalt manganese oxide, and 100g of lithium-rich manganese material were mixed in a ball mill to obtain lithium manganese iron phosphate with the chemical formula LiMn 0.6 Fe 0.4 PO4, the carbon content of the lithium manganese iron phosphate is 1.5%, and the median diameter D 50 is 15 μm, and the chemical formula of lithium nickel cobalt manganese oxide is LiNi 0.8 Co 0.1 Mn 0.1 O2, and the median diameter of lithium nickel cobalt manganese oxide is D 50 The lithium-rich manganese-based material has a chemical formula of 0.5Li2MnO3·0.5LiMnO2 and a median diameter of 3.2 μm. Zirconium balls are added and the material is ball milled for 5 hours to obtain a battery positive electrode material. A battery is manufactured in the same manner as in Example 1. [Example]

[0054] The method for producing the battery positive electrode material is as follows.

[0055] 800g of lithium manganese iron phosphate and 200g of lithium nickel cobalt manganese oxide were mixed in a mixer to obtain lithium manganese iron phosphate with the chemical formula LiMn 0.6 Fe 0.4 PO4, the carbon content of the lithium manganese iron phosphate is 1.5%, and the median diameter D 50 is 15 μm, and nickel cobalt manganese The chemical formula for lithium phosphate is LiNi 0.8 Co 0.1 Mn 0.1 O2, and the median diameter of lithium nickel cobalt manganese oxide is D 50 The particle size is 3.5 μm, and the mixture is mechanically mixed at a speed of 30 rpm for 5 hours to obtain a battery positive electrode material. A battery is manufactured in the same manner as in Example 1. (Comparative Example 7) [Example]

[0056] The method for producing the battery positive electrode material is as follows.

[0057] 900g of lithium manganese iron phosphate and 100g of lithium nickel cobalt manganese oxide were mixed in a ball mill to obtain lithium manganese iron phosphate with the chemical formula LiMn 0.6 Fe 0.4 PO4, the carbon content of the lithium manganese iron phosphate is 1.5%, and the median diameter D 50 is 15 μm, and the chemical formula of lithium nickel cobalt aluminate is LiNi 0.8 Co 0.15 Al 0.05 O2, and the median diameter of lithium nickel cobalt aluminate is D 50 After adding zirconium balls, the mixture was ball milled for 5 hours to obtain a battery positive electrode material. A battery was manufactured in the same manner as in Example 1. [Example]

[0058] The method for producing the battery positive electrode material is as follows.

[0059] 700g of lithium manganese iron phosphate and 300g of lithium nickel cobalt manganese oxide were mixed in a ball mill to obtain lithium manganese iron phosphate with the chemical formula LiMn 0.6 Fe 0.4 PO4, the carbon content of the lithium manganese iron phosphate is 1.5%, and the median diameter D 50 is 15 μm, and the chemical formula of lithium nickel cobalt manganese oxide is LiNi 0.8 Co 0.1 Mn 0.1 O2, and the median diameter of lithium nickel cobalt manganese oxide is D 50 After adding zirconium balls, the mixture was ball milled for 5 hours to obtain a battery positive electrode material. A battery was manufactured in the same manner as in Example 1. [Example]

[0060] The method for producing the battery positive electrode material is as follows.

[0061] 800g of lithium manganese iron phosphate and 200g of lithium nickel cobalt manganese oxide were mixed in a mixer to obtain lithium manganese iron phosphate with the chemical formula LiMn 0.6 Fe 0.4 PO4, the carbon content of the lithium manganese iron phosphate is 1.5%, and the median diameter D 50 is 12 μm, and the chemical formula of lithium nickel cobalt manganese oxide is LiNi 0.8 Co 0.1 Mn 0.1 O2, and the median diameter of lithium nickel cobalt manganese oxide is D 50 The particle size is 4 μm, and the mixture is mechanically mixed at a speed of 30 rpm for 5 hours to obtain a battery positive electrode material. A battery is manufactured in the same manner as in Example 1. [Example]

[0062] The method for producing the battery positive electrode material is as follows.

[0063] 800g of lithium manganese iron phosphate and 200g of lithium nickel cobalt manganese oxide were mixed in a ball mill to obtain lithium manganese iron phosphate with the chemical formula LiMn 0.6 Fe 0.4 PO4, the carbon content of the lithium manganese iron phosphate is 1.5%, and the median diameter D 50 is 12 μm, and the chemical formula of lithium nickel cobalt aluminate is LiNi 0.8 Co 0.15 Al 0.05 O2, and the median diameter of lithium nickel cobalt aluminate is D 50 The particle size is 2.4 μm, and after adding zirconium balls, the mixture is ball milled for 5 hours to obtain a battery positive electrode material. A battery is manufactured in the same manner as in Example 1. [Example]

[0064] The method for producing the battery positive electrode material is as follows.

[0065] 800g of lithium manganese iron phosphate and 200g of lithium nickel cobalt manganese oxide were mixed in a ball mill to obtain lithium manganese iron phosphate with the chemical formula LiMn 0.6 Fe 0.4 PO4, the carbon content of the lithium manganese iron phosphate is 1.5%, and the median diameter D 50 is 12 μm, and the chemical formula of lithium nickel cobalt manganese oxide is LiNi 0.8 Co 0.1 Mn 0.1 O2, and the median diameter of lithium nickel cobalt manganese oxide is D 50 The particle size is 1.5 μm, and after adding zirconium balls, the mixture is ball milled for 5 hours to obtain a battery positive electrode material. A battery is manufactured in the same manner as in Example 1. [Example]

[0066] The method for producing the battery positive electrode material is as follows.

[0067] 800g of lithium iron manganese phosphate, 180g of primary lithium nickel cobalt manganese oxide, and 20g of secondary lithium nickel cobalt manganese oxide were mixed in a ball mill to produce lithium iron manganese phosphate with the chemical formula LiMn 0.6 Fe 0.4 PO4, the carbon content of the lithium manganese iron phosphate is 1.5%, and the median diameter D 50 is 15 μm, and the chemical formula of primary lithium nickel cobalt manganese oxide is LiNi 0.8 Co 0.1 Mn 0.1 O2, and the median diameter of lithium nickel cobalt manganese oxide is D 50 is 3.2 μm, and the chemical formula of secondary lithium nickel cobalt manganese oxide is LiNi 0.8 Co 0.1 Mn 0.1 O2, and the median diameter of lithium nickel cobalt manganese oxide is D 50 After adding zirconium balls, the mixture was ball milled for 5 hours to obtain a battery positive electrode material. A battery was manufactured in the same manner as in Example 1. Comparative Example 1

[0068] Median diameter D 50 Lithium iron manganese phosphate LiMn 0.6 Fe 0.4 The positive electrode material was PO4, and the positive electrode material, conductive agent, and binder were dispersed in N-methylpyrrolidone in a mass ratio of 90:5:5. The conductive agent was carbon nanotubes, the binder was PVDF5130, and the solid content of the paste was 50%. The paste was applied to the surface of aluminum foil at a coating density of 200 g / m. 2 After drying, the electrode plate is cut into 15 mm electrode plates and assembled with a separator and a lithium sheet to form a 2032 button-type half cell.

[0069] 950g of lithium manganese iron phosphate and 50g of lithium nickel cobalt manganese oxide were mixed in a ball mill to obtain lithium manganese iron phosphate with the chemical formula LiMn 0.6 Fe 0.4PO4, and the median diameter of lithium iron manganese phosphate D 50 is 15 μm, and the chemical formula of lithium nickel cobalt manganese oxide is LiNi 0.8 Co 0.1 Mn 0.1 O2, and the median diameter of lithium nickel cobalt manganese oxide is D 50 After adding zirconium balls, the mixture was ball milled for 5 hours to obtain a battery positive electrode material. A battery was manufactured in the same manner as in Comparative Example 1. Comparative Example 3

[0070] 600g of lithium manganese iron phosphate and 400g of lithium nickel cobalt manganese oxide were mixed in a ball mill to obtain lithium manganese iron phosphate with the chemical formula LiMn 0.6 Fe 0.4 PO4, and the median diameter of lithium iron manganese phosphate D 50 is 15 μm, and the chemical formula of lithium nickel cobalt manganese oxide is LiNi 0.8 Co 0.1 Mn 0.1 O2, and the median diameter of lithium nickel cobalt manganese oxide is D 50 After adding zirconium balls, the mixture was ball milled for 5 hours to obtain a battery positive electrode material. A battery was manufactured in the same manner as in Comparative Example 1. Comparative Example 4

[0071] 800g of lithium manganese iron phosphate and 200g of lithium nickel cobalt manganese oxide were mixed in a ball mill to obtain lithium manganese iron phosphate with the chemical formula LiMn 0.6 Fe 0.4 PO4, and the median diameter of lithium iron manganese phosphate D 50 is 12 μm, and the chemical formula of lithium nickel cobalt manganese oxide is LiNi 0.8 Co 0.1 Mn 0.1 O2, and the median diameter of lithium nickel cobalt manganese oxide is D 50 After adding zirconium balls, the mixture was ball milled for 5 hours to obtain a battery positive electrode material. A battery was manufactured in the same manner as in Comparative Example 1. Comparative Example 5

[0072] 800g of lithium manganese iron phosphate and 200g of lithium nickel cobalt manganese oxide were mixed in a ball mill to obtain lithium manganese iron phosphate with the chemical formula LiMn 0.6 Fe 0.4 PO4, and the median diameter of lithium iron manganese phosphate D 50 is 12 μm, and the chemical formula of lithium nickel cobalt manganese oxide is LiNi 0.8 Co 0.1 Mn 0.1 O2, and the median diameter of lithium nickel cobalt manganese oxide is D 50 After adding zirconium balls, the mixture was ball milled for 5 hours to obtain a battery positive electrode material. A battery was manufactured in the same manner as in Comparative Example 1. Comparative Example 6

[0073] 800g of lithium manganese iron phosphate, 100g of lithium nickel cobalt manganese oxide, and 100g of lithium manganese oxide were mixed in a ball mill to obtain lithium manganese iron phosphate with the chemical formula LiMn 0.6 Fe 0.4 PO4, and the median diameter of lithium iron manganese phosphate D 50 is 1.5 μm, and the chemical formula of lithium nickel cobalt manganese oxide is LiNi 0.8 Co 0.1 Mn 0.1 O2, and the median diameter of lithium nickel cobalt manganese oxide is D 50 is 15 μm, the chemical formula of lithium manganese oxide is LiMn2O4, and the median diameter D 50 After adding zirconium balls, the mixture is ball milled for 5 hours to obtain a battery positive electrode material. A battery is manufactured in the same manner as in Comparative Example 1.

[0074] To verify the performance of the battery manufactured in this application, this application further provides an effect example.

[0075] 1) FIG. 4 is a scanning electron microscope photograph of the battery positive electrode material according to Example 1 of the present application. As shown in FIG. 4, the bright particles in FIG. 4 are lithium nickel cobalt manganese oxide particles, and the dark particles are lithium manganese iron phosphate particles. As can be seen from FIG. 4, in the battery positive electrode material of Example 1, small particles of lithium nickel cobalt manganese oxide are tightly packed in the gaps between the lithium manganese iron phosphate particles. 1~5、7~11 and comparative examples 1~7 The particle size distribution of the battery positive electrode material was obtained, and the particle size distribution was used as a basis for the examples. 1~5、7~11 and comparative examples 1~7 The median diameter D of the battery positive electrode material 50 The measurement results are shown in Table 1.

[0076] 2) Example 1~5、7~11 and comparative examples 1~7 The positive electrode plate is subjected to compaction density measurement, and the measurement method includes the following: 1~5、7~11 and comparative examples 1~7 The positive electrode plate is compacted, a round sheet of a certain radius R is cut out from the surface of the positive electrode plate, its mass M1 and thickness H1 are measured, a round sheet of aluminum foil of the same radius is cut out, its mass M2 and thickness H2 are measured, and the difference in mass is divided by the volume of the positive electrode coating material to obtain the compacted density. The formula for calculating the compacted density is as follows:

number

[0077] 3) Example 1~5、7~11 and comparative examples 1~7 The electrochemical performance of the battery was measured. 1~5、7~11 and comparative examples 1~7The battery was charged at a constant voltage of 0.1C at 25°C within the voltage measurement range of 2.8 to 4.3V, and then discharged at a constant current of 0.1C with a cut-off current of 0.02C. The initial charge capacity and discharge capacity were recorded. The discharge specific capacity = initial discharge capacity of the battery (milliampere-hours) / weight of the positive electrode material (grams), the initial coulombic efficiency = initial discharge capacity / initial charge capacity, the gravimetric energy density = discharge specific capacity (mAh / g) * average discharge voltage (V), and the volumetric energy density = gravimetric energy density (Wh / kg) * compaction density (g / cm 3 The battery parameters were calculated based on the formula, and the measurement results are shown in Table 1. Table 1. Examples 1~5、7~11 and comparative examples 1~7 Table of battery cathode materials and battery parameters [Table 1]

[0078] As can be seen from the experimental results in Table 1, compared to Comparative Example 1, the battery positive electrode materials of Examples 1 to 4 contain active particles with smaller particle sizes, so the manufactured batteries have higher gravimetric energy densities, and the volumetric energy densities of the batteries of Examples 1 to 4 are improved by 20% compared to the battery of Comparative Example 1. This is because the active particles have higher energy densities, and after optimizing particle deposition, the compaction density of the battery positive electrode material is further improved, resulting in improved volumetric energy densities.

[0079] Compared with Comparative Example 2 and Comparative Example 3, Example 5 、 The battery cathode material of Example 7 has a higher compaction density, which is 、The battery positive electrode material of Example 7 has an appropriate mass ratio between the lithium manganese iron phosphate and the active particles, allowing the small active particles to fill the gaps between the lithium manganese iron phosphate effectively, resulting in a significantly improved packing density compared to Comparative Example 2. However, due to the limited size of the gaps between the lithium manganese iron phosphate, there is a certain limit to the amount of particles that can be filled into the gaps, and once the amount of active particles reaches a certain value, the packing density decreases. Therefore, the packing density of the battery positive electrode material of Example 7 is lower than that of Example 5. Experiments have shown that when the mass ratio of the lithium manganese iron phosphate to the active particles is 1:(0.2-0.35), the battery positive electrode material can have a high packing density. In addition, Example 5 、 In Example 7, active particles with a higher specific capacity were added, so Example 5 、 The weight energy density of the 7's battery has also been improved.

[0080] Compared with Comparative Examples 4 and 6, the particle size ratios of the lithium manganese iron phosphate to the active particles in the battery positive electrode materials of Examples 8 to 10 were 3 to 8, allowing the particles to be densely packed together. In Comparative Example 4, the particle size difference between the lithium manganese iron phosphate and the active particles was large, leaving many gaps between the larger particle sizes of the lithium manganese iron phosphate. That is, the gaps between the larger particles needed to be filled with more small particles to achieve dense packing. In Comparative Example 5, the particle size difference between the lithium manganese iron phosphate and the active particles was small, preventing the active particles from filling the gaps between the lithium manganese iron phosphate, resulting in a low packing density. In Comparative Example 6, the particle size of the lithium manganese iron phosphate was much smaller than that of the active particles, and the mass of the lithium manganese iron phosphate was much larger than that of the active particles. This resulted in a significant particle imbalance. The battery positive electrode material had a packing method in which the active particles were dispersed among the lithium manganese iron phosphate particles, failing to achieve a good packing effect and resulting in a low packing density.

[0081] In Example 11, secondary filling is carried out based on the primary filling, and secondary lithium nickel cobalt manganese oxide can be further filled into the remaining gap after the primary filling. The experimental results show that the positive electrode plates of Example 11 and Example 1 have higher packing densities, which indicates that the secondary filling can effectively improve the packing density of the positive electrode plate, thereby improving the gravimetric energy density and volumetric energy density of the battery.

[0082] As can be seen from the above experimental results, by controlling the mass ratio of the lithium manganese iron phosphate to the active particles and the particle size distribution, the active particles can be effectively filled into the gaps between the lithium manganese iron phosphate particles, thereby improving the compaction density of the battery positive electrode material. When the battery positive electrode material is manufactured into a positive electrode plate and applied to a battery, the battery can have high gravimetric energy density and volumetric energy density.

[0083] The above description is an exemplary embodiment of the present application, but should not be understood as limiting the scope of the present application. It should be noted that those skilled in the art can make some improvements and modifications without departing from the principles of the present application, and these improvements and modifications are also deemed to be within the protection scope of the present application.

Claims

1. A battery positive electrode material includes lithium manganese iron phosphate particles (11) and active particles (12) dispersed in the gaps between the lithium manganese iron phosphate particles (11), and the active particles (12) are selected from the group consisting of lithium nickel cobalt manganese oxide particles, lithium nickel cobalt aluminate particles, lithium-rich manganese-based material particles, lithium cobalt oxide particles, and spinel lithium manganese oxide LiMn ２ O ４ Particles, and layered lithium manganese oxide LiMnO ２ a mass percentage of the lithium manganese iron phosphate particles is 70% to 80% and a mass percentage of the active particles (12) is 20% to 30%; and a compacted density of the battery positive electrode material is 2.4 g / cm 3 to 3.2 g / cm 3 .

2. 2. The battery positive electrode material according to claim 1, wherein the median diameter of the lithium iron manganese phosphate particles (11) is 2 μm to 15 μm.

3. 2. The battery cathode material according to claim 1, wherein the median diameter of the active particles is 0.5 μm to 5 μm.

4. 2. The battery cathode material of claim 1, wherein the active particles (12) include primary active particles (121) and secondary active particles (122), the median diameter of the primary active particles (121) being 0.5 μm to 5 μm, and the median diameter of the secondary active particles (122) being 0.1 μm to 2 μm.

5. 2. The battery positive electrode material according to claim 1, wherein the mass ratio of the lithium iron manganese phosphate particles (11) to the active particles (12) is 1:(0.2-0.35).

6. The lithium manganese iron phosphate particles (11) are LiMn ｘ Fe １－ｘ P.O. ４ 2. The battery cathode material of claim 1, wherein 0.5≦x≦0.

9.

7. The lithium manganese iron phosphate particles (11) contain carbon, and the lithium manganese iron phosphate 2. The battery positive electrode material according to claim 1, wherein the mass percentage of the carbon in the lithium particles (11) is 1% to 3%.

8. 2. The battery cathode material of claim 1, wherein the lithium manganese iron phosphate particles (11) further comprise a doping element, and the doping element comprises one or more of Ti, V, Co, Ni, Cu, Zn, Mg, Ca, Al, Nb, and Mo.

9. The lithium nickel cobalt manganese oxide particles are LiNi ａ Co ｂ Mn １－ａ－ｂ O ２ 2. The battery positive electrode material according to claim 1, wherein 0<a<1, 0<b<1, and 0<1-a-b<1.

10. 2. The battery cathode material of claim 1, wherein the lithium nickel cobalt manganese oxide particles further comprise a doping element, the doping element comprising one or more of Ti, V, Fe, Cu, Zn, Mg, Ca, Al, Nb, and Mo.

11. The lithium nickel cobalt aluminate particles are LiNi ｍ Co ｎ Al １－ｍ－ｎ O ２ 2. The battery positive electrode material according to claim 1, wherein m is a number of carbon atoms, n is a number of carbon atoms, and m is a number of carbon atoms.

12. 2. The battery cathode material of claim 1, wherein the lithium nickel cobalt aluminate particles further comprise a doping element, the doping element comprising one or more of Ti, V, Mn, Fe, Cu, Zn, Mg, Ca, Nb, and Mo.

13. The lithium-rich manganese-based material particles are ２ MnO ３ ・(1-y)LiMO ２ 2. The battery cathode material of claim 1, wherein 0<y<1, and M comprises at least one of Mn, Ni, or Co.

14. 2. The battery cathode material of claim 1, wherein the lithium-rich manganese-based material particles further comprise a doping element, the doping element comprising one or more of Ti, V, Fe, Co, Cu, Zn, Mg, Ca, Nb, and Mo.

15. 2. The battery positive electrode material according to claim 1, wherein there is no agglomeration between the lithium manganese iron phosphate particles (11) and the active particles (12), and the active particles (12) do not coat or adhere to the particle surfaces of the lithium manganese iron phosphate particles (11).

16. A positive electrode plate comprising: a current collector; and a positive electrode material layer disposed on the current collector, wherein the positive electrode material layer comprises the battery positive electrode material according to any one of claims 1 to 15.

17. A secondary battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the positive electrode comprises the positive electrode plate according to claim 16.

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