Positive electrode material composition, secondary battery, and power consumption device

Abstract

This application provides a cathode material composition, a secondary battery, and a power consumption device. This cathode material composition comprises a phosphate-based cathode material and a ternary cathode material, where W1 is the weight of the phosphate-based cathode material and W2 is the weight of the ternary cathode material, and α = W1 / (W1+W2), 50% ≤ α ≤ 97%, selectively 70% ≤ α ≤ 90%, the phosphate-based cathode material is a polycrystalline secondary spherical material and / or the ternary cathode material is a polycrystalline secondary spherical material. After mixing both the phosphate-based cathode material and the ternary cathode material, their advantages are complementary, and by adjusting the ratio of the two, a synergistic effect can be achieved, giving the cathode material composition advantages in terms of higher energy density and higher cycle performance. Phosphate-based cathode materials and / or ternary cathode materials are polycrystalline secondary spheres, and by fully utilizing the advantage of low bulk diffusion resistance in polycrystalline secondary spheres, the charging capacity and low-temperature discharge capacity of the composition are improved.

Description

[Technical Field]

[0001] This application relates to the battery technology field, and more particularly to positive electrode material compositions, secondary batteries, and power consumption devices. [Background technology]

[0002] Lithium-ion batteries are rechargeable batteries that operate primarily through the movement of lithium ions between the positive and negative electrodes. During the charging and discharging process, Li ions intercept and deintercept between the two electrodes: during charging, Li ions are deintercepted from the positive electrode and intercepted at the negative electrode via the electrolyte, resulting in a lithium-rich state at the negative electrode, and the reverse occurs during discharging.

[0003] Currently, there are many methods to improve the cycle performance of lithium-ion batteries. These include doping or coating modification of the cathode material to mitigate the degradation of the crystal structure during the cycle process, or combining cathode materials with different advantages to take the strengths and compensate for the weaknesses, thereby improving the battery's cycle performance and energy density. For example, lithium iron phosphate cathode materials and ternary cathode materials are combined. However, while combining the two can improve the battery's cycle capability or energy density to some extent, it cannot improve the battery's charging capability. [Overview of the project] [Means for solving the problem]

[0004] This application provides a positive electrode material composition, a secondary battery, and a power consumption device that improve the rapid charging performance of a battery.

[0005] According to a first aspect of this application, a cathode material composition is provided comprising a phosphate-based cathode material and a ternary cathode material, wherein the weight of the phosphate-based cathode material is denoted as W1, the weight of the ternary cathode material is denoted as W2, α = W1 / (W1+W2), 50% ≤ α ≤ 97%, selectively 70% ≤ α ≤ 90%, and the phosphate-based cathode material is a polycrystalline secondary spherical material and / or the ternary cathode material is a polycrystalline secondary spherical material.

[0006] Phosphate-based cathode materials, due to their phosphate polyanion material, exhibit high stability, good cycle stability, and superior lifetime. While ternary cathode materials have relatively high energy density, the layered transition metal oxide structure is unstable during the cycling process, resulting in a shorter lifetime for ternary cathode materials compared to phosphate-based materials. By mixing the two, the high energy density of the ternary cathode material compensates for the low energy density of the phosphate-based cathode material, and the high stability of the phosphate-based cathode material compensates for the low structural stability of the ternary cathode material. Simultaneously, by adjusting the ratio of the two, a synergistic effect can be achieved, resulting in the cathode material composition of this application having the advantages of higher energy density and higher cycle performance. Furthermore, the phosphate-based cathode material and / or ternary cathode material of this application are polycrystalline secondary spheres, and by fully utilizing the advantage of low bulk diffusion resistance in polycrystalline secondary spheres, the charging capacity and low-temperature discharge capacity of the composition are improved.

[0007] In any embodiment of the first aspect, D of the positive electrode material composition V The particle size is 50 ≥ 8 μm, and selectively, the particle size distribution of the above cathode material composition satisfies the relationship 14 > Aα + B(1-α) > 7, where A is the phosphate-based cathode material D V 50, and B is the ternary cathode material D V The ratio is 50, where α is the proportion of manganese iron lithium cathode material. By further improving the particle size blending effect between phosphate-based cathode material and ternary cathode material, rapid charging capability and low-temperature discharge efficiency are significantly improved.

[0008] In any embodiment of the first aspect, the particle size of the primary particles of the phosphate-based cathode material is 10 to 600 nm, selectively 35 to 110 nm, and by selecting a phosphate-based cathode material in which the particle size of the primary particles is nanoscale, the rate performance of the phosphate-based cathode material can be further improved.

[0009] In any embodiment of the first aspect, optionally, the laser particle size D of the phosphate-based cathode material V 50 is 7 to 30 μm, and D V 50 is optionally 8 to 14 μm, and D V 90 < 30 μm. Selecting the laser particle size D V 50 within the above range makes the aggregation of primary particles more stable, further improving the structural stability of this phosphate-based cathode material.

[0010] In any embodiment of the first aspect, optionally, the BET specific surface area of the phosphate-based cathode material is 8 - 20 m 2 / g.

[0011] In any embodiment of the first aspect, optionally, the tap density of the phosphate-based cathode material is 1.5 - 2.6 g / cm 3 and the tap density is optionally 2.15 - 2.5 g / cm 3 This further improves the rate performance of the composition.

[0012] In any embodiment of the first aspect, optionally, the specific capacity of the phosphate-based cathode material at a 0.1C rate is 140 - 165 mAh / g, and optionally 155 - 160 mAh / g.

[0013] In any embodiment of the first aspect, the chemical formula of the above phosphate-based cathode material is Li 1+x Mn 1-y A y P 1-z R zThe compound is O4, and in the chemical formula, x is any value in the range of -0.100 to 0.100, y is any value in the range of 0.001 to 0.500, and z is any value in the range of 0.001 to 0.100, where the values ​​of x, y, and z satisfy the condition of keeping the chemical formula electrically neutral, A is one or more elements selected from Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb, and Ge, and selectively one or more elements from Fe, Ti, V, Ni, Co, and Mg, and R is one or more elements selected from B, Si, N, S, F, Cl, and Br, and selectively R is one element selected from B, Si, N, and S. Doping phosphate systems with elements A and R contributes to improving the structural stability of phosphate-based cathode materials and the rate performance of secondary batteries having them.

[0014] In any embodiment of the first aspect, the chemical formula of the phosphate-based cathode material is Li a A x Mn 1-y B y P 1-z C z O 4-n D n Herein, A comprises one or more elements from the group consisting of Zn, Al, Na, K, Mg, Nb, Mo, and W; B comprises one or more elements from the group consisting of Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge; C comprises one or more elements from the group consisting of B (boron), S, Si, and N; D comprises one or more elements from the group consisting of S, F, Cl, and Br; a is selected from the range of 0.9-1.1; x is selected from the range of 0.001-0.1; y is selected from the range of 0.001-0.5; z is selected from the range of 0.001-0.1; n is selected from the range of 0.001-0.1; and the phosphate-based cathode material is electrically neutral. By simultaneously doping the four locations mentioned above with specific amounts of the aforementioned elements, the rate performance, cycle performance, and / or high-temperature stability of the phosphate-based cathode material can be significantly improved.

[0015] In any embodiment of the first aspect, the cathode material selectively includes a polycrystalline core and a coating layer covering the polycrystalline core, wherein the phosphate-based cathode material has the chemical formula Li 1+x Mn 1-y A y P 1-z R z O4 or chemical formula Li a A x Mn 1-y B y P 1-z C z O 4-n D n The coating layer is selectively composed of one or more layers of pyrophosphate, phosphate, and carbon. The coating layer can effectively suppress the elution of transition metals and reduce surface side reactions of phosphate-based cathode materials.

[0016] In any embodiment of the first aspect, the ternary cathode material D V 50 is 5-11 μm, D V The particle size is 99 ≤ 30 μm, and selectively, the average particle size of the primary particles of the ternary cathode material is 50-800 nm. By using the ternary material as secondary particles, the lithium ion diffusion pathway and bulk diffusion resistance can be further shortened.

[0017] In any embodiment of the first aspect, the BET specific surface area of ​​the ternary cathode material is 0.2 to 1.2 m². 2 A ternary material with a BET specific surface area within the above range can be improved by controlling the density of secondary particles, thereby increasing its compaction and further improving its energy density.

[0018] In any embodiment of the first aspect, the ternary cathode material is an NCM ternary cathode material or an NCA ternary cathode material. Optionally, the molar content of Ni in the ternary cathode material is 50% to 75%, and the molar content of Co is 0.5% to 49.5%. Further optionally, the molar content of Ni is 50% to 70%, and the molar content of Co is 5% to 35%. The molar content of Ni affects the performance of the capacity of the ternary cathode material and has a great impact on improving the energy density of the composite material. The molar content of Co can improve the electronic conductivity and ionic conductivity of the system and can effectively improve the charging ability of the ternary cathode material.

[0019] In any embodiment of the first aspect, the ternary cathode material has the chemical formula Li a’ Ni b’ Co c’ M1 d’ M2 e’ O f’ R´ g’ where 0.75 ≤ a’ ≤ 1.2, 0 < b’ < 1, 0 < c’ < 1, 0 < d’ < 1, 0 ≤ e’ ≤ 0.2, 1 ≤ f’ ≤ 2.5, 0 ≤ g’ ≤ 1, and f’ + g’ ≤ 3. M1 is the Mn element and / or the Al element. M2 is one or more elements selected from Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, Nb. R´ is one or more elements selected from N, F, S, Cl. Element doping is used to improve the cycle performance and rate performance of the ternary cathode material.

[0020] According to the second aspect of the present application, a secondary battery is provided. The secondary battery includes a positive electrode plate, and the positive electrode plate includes a positive electrode active material, which is any one of the positive electrode material compositions of the first aspect. The secondary battery having the positive electrode material composition of the present application has a high energy density and cycle performance, and also effectively improves the charging ability and low-temperature discharge ability.

[0021] According to the third aspect of the present application, a power consumption device including a secondary battery selected from the secondary batteries of the second aspect is provided. The power consumption device has better operating stability at low temperatures. To more clearly illustrate the technical concept of the embodiments of this application, the following briefly introduces the drawings that may be used in the embodiments of this application. It is obvious that the drawings in the following description are only a few of the embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without expending any creative effort. [Brief explanation of the drawing]

[0022] [Figure 1] This is a schematic diagram of a secondary battery according to one embodiment of the present application. [Figure 2] Figure 1 is an exploded view of a secondary battery according to one embodiment of this application. [Figure 3] This is a schematic diagram of a battery module according to one embodiment of the present application. [Figure 4] This is a schematic diagram of a battery pack according to one embodiment of the present application. [Figure 5] Figure 4 is an exploded view of a battery pack according to one embodiment of this application. [Figure 6] This is a schematic diagram of a power consumption device powered by a secondary battery according to one embodiment of the present application.

[0023] In drawings, the drawings are not drawn to the actual scale. [Modes for carrying out the invention]

[0024] The embodiments of this application will be described in more detail below, linking them with the drawings and examples. The detailed descriptions of the embodiments and drawings below are for illustrative purposes to illustrate the principles of this application, but are not intended to limit the scope of this application; in other words, this application is not limited to the embodiments described.

[0025] The following describes in detail embodiments specifically disclosing the positive electrode material composition, secondary battery, and power consumption device of this application, with appropriate reference to the drawings. However, unnecessary detailed explanations may be omitted. For example, detailed explanations of well-known matters and repeated explanations of structures that are actually the same may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to make it easily understandable to those skilled in the art. The drawings and the following explanation are provided to enable those skilled in the art to fully understand this application and are not intended to limit the topics described in the claims.

[0026] The “range” disclosed in this application is limited in the form of a lower limit and an upper limit, and a given range is limited by selecting one lower limit and one upper limit, which define the boundary of a particular range. The range thus limited may or may not include the limit value, and any combination is possible, that is, any lower limit may be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 60-110 and 80-120 can also be assumed. Furthermore, if 1 and 2 are listed as the minimum range values ​​and 3, 4, and 5 are listed as the maximum range values, then ranges such as 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 can all be assumed. In this application, unless otherwise specified, the numerical range “a-b” represents an abbreviated expression for any combination of real numbers a-b, where a and b are both real numbers. For example, the numerical range "0 to 5" indicates that all real numbers between "0 to 5" have already been listed in this specification, and "0 to 5" is simply a shortened representation of combinations of these numbers. Also, expressing a parameter as an integer ≥ 2 is equivalent to disclosing that this parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0027] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical inventions.

[0028] Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical concepts.

[0029] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, the fact that the method includes steps (a) and (b) means that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, the fact that the method referred to above may further include step (c) means that step (c) may be added to the method in any order, for example the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), and so on.

[0030] Unless otherwise specified, the terms “includes” and “inclusion” as used in this application may represent an open or closed configuration. For example, the terms “includes” and “inclusion” may mean that other components not listed may be included or inclusion, or that only the listed components may be included or inclusion.

[0031] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any of the following conditions satisfy "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) but B is true (or exists); and both A and B are true (or exist).

[0032] [Secondary battery] A secondary battery, also known as a rechargeable battery or storage battery, is a type of battery that can be used continuously by reactivating its active material through a charging method after it has been discharged.

[0033] Generally, a secondary battery includes a positive electrode plate, a negative electrode plate, a separator, and an electrolyte. During the charging and discharging process of the battery, active ions (e.g., lithium ions) intermittently move back and forth between the positive and negative electrode plates, being absorbed and released. The separator is placed between the positive and negative electrode plates and primarily serves to prevent short circuits between them, while also allowing active ions to pass through. The electrolyte primarily serves to conduct active ions between the positive and negative electrode plates.

[0034] [Positive electrode material] A typical embodiment of this application provides a cathode material composition comprising a phosphate-based cathode material and a ternary cathode material, wherein the weight of the phosphate-based cathode material is denoted as W1, the weight of the ternary cathode material is denoted as W2, α = W1 / (W1+W2), 50% ≤ α ≤ 97%, selectively 70% ≤ α ≤ 90%, and the phosphate-based cathode material is a polycrystalline secondary spherical material and / or the ternary cathode material is a polycrystalline secondary spherical material.

[0035] Phosphate-based cathode materials, due to their phosphate polyanion material, exhibit high stability, good cycle stability, and superior lifetime. While ternary cathode materials have relatively high energy density, the layered transition metal oxide structure is unstable during the cycling process, resulting in a shorter lifetime for ternary cathode materials compared to phosphate-based materials. By mixing the two, the high energy density of the ternary cathode material compensates for the low energy density of the phosphate-based cathode material, and the high stability of the phosphate-based cathode material compensates for the low structural stability of the ternary cathode material. Simultaneously, by adjusting the ratio of the two, a synergistic effect can be achieved, resulting in the cathode material composition of this application having the advantages of higher energy density and higher cycle performance. Furthermore, the phosphate-based cathode material and / or ternary cathode material of this application are polycrystalline secondary spheres, and by fully utilizing the advantage of low bulk diffusion resistance in polycrystalline secondary spheres, the charging capacity and low-temperature discharge capacity of the composition are improved.

[0036] The positive electrode plates are cut using argon ion polishing, and elemental analysis is performed on the cut surfaces. Then, the ratio of the main elements of the manganese iron lithium phosphate material and the ternary material is compared, and the weight is determined based on the ratio.

[0037] In some embodiments, the D of the positive electrode material composition V The particle size is 50 ≥ 8 μm, and selectively, the particle size distribution of the above cathode material composition satisfies the relationship 30 > 1 / {Aα + B(1-α)} > 7, where A is the phosphate-based cathode material D V 50, and B is the ternary cathode material D V The value is 50. By further improving the particle size blending effect between the phosphate-based cathode material and the ternary cathode material, rapid charging capability and low-temperature discharge efficiency are significantly improved.

[0038] In some embodiments, the particle size of the primary particles of the phosphate-based cathode material is 10 to 600 nm, selectively 35 to 110 nm, and by selecting a phosphate-based cathode material in which the particle size of the primary particles is nanoscale, the rapid charging capability and low-temperature discharge efficiency of the phosphate-based cathode material can be further improved.

[0039] In some embodiments, the laser particle size D of the phosphate-based cathode material is selectively controlled. V 50 is 7-30 μm, D V 50 selectively targets 8-14 μm, D V 90 < 30 μm. Laser particle size D V By selecting 50 within the above range, the aggregation of primary particles becomes more stable, further improving the structural stability of this phosphate-based cathode material and thereby further improving the cycle performance of the cathode material composition. The above laser particle size is the laser particle size of the secondary spheres of the phosphate-based cathode material.

[0040] In some embodiments, the BET specific surface area of ​​the phosphate-based cathode material is selectively set to 8-20 m². 2 It is / g. Furthermore, its cycle performance is controlled within a desirable range.

[0041] In some embodiments, the compaction density of the phosphate-based cathode material is selectively set to 1.5–2.6 g / cm³. 3 The compaction density is selectively 2.15–2.5 g / cm³. 3 This further improves the rate performance of the composition.

[0042] In some embodiments, the specific capacity of the phosphate-based cathode material at a 0.1C rate is selectively 140–165 mAh / g, and selectively 155–160 mAh / g.

[0043] In this embodiment, the chemical formula of the phosphate-based cathode material is Li 1+x Mn 1-y A y P 1-z R z The compound is O4, and in the chemical formula, x is any number in the range of -0.100 to 0.100, y is any number in the range of 0.001 to 0.500, z is any number in the range of 0.001 to 0.100, the values ​​of x, y and z satisfy the condition that the chemical formula is electrically neutral, A is one or more elements selected from Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb and Ge, selectively one or more elements from Fe, Ti, V, Ni, Co and Mg, R is one or more elements selected from B, Si, N, S, F, Cl and Br, selectively R is one element selected from B, Si, N and S. Element A, doped into the manganese sites of lithium manganese phosphate, reduces the lattice change rate of lithium manganese phosphate during lithium desorption and absorption processes, improving the structural stability of the lithium manganese phosphate cathode material and significantly reducing manganese elution, thereby lowering oxygen activity on the particle surface. Element R, doped into the phosphorus sites, contributes to altering the difficulty of changing the Mn-O bond length, thereby lowering the lithium ion transition barrier, facilitating lithium ion transitions, and improving the rate performance of secondary batteries.

[0044] In some embodiments, the chemical formula of the phosphate-based cathode material is Lia A x Mn 1-y B y P 1-z C z O 4-n D n Here, A comprises one or more elements from the group consisting of Zn, Al, Na, K, Mg, Nb, Mo, and W; B comprises one or more elements from the group consisting of Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge; C comprises one or more elements from the group consisting of B (boron), S, Si, and N; D comprises one or more elements from the group consisting of S, F, Cl, and Br; a is selected from the range of 0.9-1.1, for example, 0.97, 0.977, 0.984, 0.988, 0.99, 0.991, 0.992, 0.993, 0.994, 0.995, 0.996, 0.997, 0.998, 1.01; and x is 0.001 The range is selected from -0.1, for example 0.001, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, and y is selected from the range 0.001-0.5, for example 0.001, 0.005, 0.02, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0. The values ​​are 34, 0.345, 0.349, 0.35, 0.4, and 0.5, where z is selected from the range of 0.001-0.1, for example 0.001, 0.005, 0.08, and 0.1, and n is selected from the range of 0.001-0.1, for example 0.001, 0.005, 0.08, and 0.1, and the phosphate-based cathode material is electrically neutral. A, B, C, and D are the elements doped into the Li site, Mn site, P site, and O site of the compound LiMnPO4, respectively. Although we do not wish to be bound by theory, it is thought that the improvement in the performance of phosphate-based cathode materials is related to the reduction in the lattice change rate and decrease in surface activity of the phosphate-based cathode material during the lithium desorption and absorption process. The reduction in the lattice change rate reduces the lattice constant difference where the grain boundary is between two phases, reducing interfacial stress, and Li +This can enhance the transmission capability at the interface, thereby improving the rate performance of the cathode active material. On the other hand, high surface activity can easily lead to serious interfacial side reactions, intensifying gas generation, electrolyte consumption, and interface breakdown, thereby affecting battery cycle performance. The above phosphate-based cathode materials have reduced lattice change rates through Li and Mn site doping. Doping to the Mn site further effectively reduces surface activity, thereby suppressing Mn elution and interfacial side reactions between the cathode active material and the electrolyte. Doping to the P site accelerates the rate of change of Mn-O bond length, reducing the small polariton transition barrier of the material, which is advantageous for electronic conductivity. Doping to the O site has a good effect in reducing interfacial side reactions. Doping to the P and O sites further affects Mn elution of antisite defects and kinetic performance. Therefore, doping can reduce the concentration of antisite defects in the material, improve the kinetic performance and gram capacity of the material, and can also change the particle topography, thereby increasing the compaction density. The applicant has unexpectedly discovered that by simultaneously doping specific elements in specific amounts to the Li, Mn, P, and O sites of the compound LiMnPO4, significantly improved rate performance can be obtained, the elution of Mn and the doped elements to the Mn site is greatly reduced, resulting in greatly improved cycle performance and / or high-temperature stability, as well as improved gram capacity and compaction density of the material.

[0045] In some embodiments, the phosphate-based cathode material is selectively selected, with the chemical formula Li 1+x Mn 1-y A y P 1-z R zThe electrode comprises a polycrystalline core containing O4 and a coating layer covering the polycrystalline core, the coating layer being one or more layers of selectively pyrophosphate, phosphate, or carbon. Because the transition barrier of the transition metal pyrophosphate is relatively high (>1 eV), the elution of the transition metal can be effectively suppressed. On the other hand, phosphate has excellent lithium ion conductivity and can reduce the heterolithium content on the surface. The carbon layer can effectively improve the conductivity and desolvation capacity of LiMnPO4, act as a "barrier," further inhibit the movement of manganese ions into the electrolyte, and reduce corrosion of the electrolyte to the active material. At the same time, the carbon layer can optimize the conductive network around the ternary cathode material in the mixture, improving the uniformity of the mixture between the phosphate-based cathode material and the ternary cathode material.

[0046] In some embodiments, the ternary cathode material D V 50 is 5-11 μm, DV99 ≤ 30 μm, and selectively, the average particle size of the primary particles of the ternary cathode material is 50-800 nm. By using the ternary material as secondary particles, the lithium ion diffusion pathway and bulk diffusion resistance can be further shortened.

[0047] Generally, secondary particles have a larger specific surface area than primary particles of equal size, leading to serious interfacial side reactions that cause the consumption of active lithium and worsen battery life. To avoid the above problems caused by secondary particles, in some embodiments, the BET specific surface area of ​​the ternary cathode material is set to 0.2 to 1.2 m². 2 By selecting a ternary material with a BET specific surface area within the above range and controlling the density of secondary particles, compaction is improved, and the energy density of the material is further enhanced.

[0048] In some embodiments, the ternary cathode material is an NCM ternary cathode material or an NCA ternary cathode material. Optionally, the molar content of Ni in the ternary cathode material is 50% to 75%, and the molar content of Co is 0.5% to 49.5%. Further optionally, the molar content of Ni is 50% to 70%, and the molar content of Co is 5% to 35%. The molar content of Ni affects the performance of the ternary cathode material's capacity and has a great impact on improving the energy density of the composite material. The molar content of Co can improve the electronic conductivity and ionic conductivity of the system and effectively improve the kinetic performance of the ternary cathode material.

[0049] In some embodiments, the ternary cathode material has the chemical formula Li a’ Ni b’ Co c’ M1 d’ M2 e’ O f’ R´ g’ where 0.75 ≦ a’ ≦ 1.2, 0 < b’ < 1, 0 < c’ < 1, 0 < d’ < 1, 0 ≦ e’ ≦ 0.2, 1 ≦ f’ ≦ 2.5, 0 ≦ g’ ≦ 1, and f’ + g’ ≦ 3. M1 is the Mn element and / or the Al element. M2 is one or more elements selected from Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, Nb. R´ is one or more elements selected from N, F, S, Cl. Element doping is used to improve the cycle performance and rate performance of the ternary cathode material.

[0050] According to some embodiments of the present invention, the method for manufacturing the phosphate cathode material Li 1+x Mn 1-y A y P 1-z R z O4 includes the following: Mixing a manganese source, a source of element A, and an acid in a container and stirring to obtain manganese salt particles doped with element A. Here, the stirring is carried out at a temperature of 20 - 120°C, optionally 25 - 80°C, and / or the stirring is carried out at 500 - 700 rpm for 60 - 420 minutes, optionally 120 - 360 minutes. Element A-doped manganese salt particles are mixed with a source of lithium, a source of phosphorus, and a source of element R in a solvent to obtain a slurry, and after sintering under the protection of an inert gas atmosphere, lithium manganese phosphate doped with element A and element R is obtained. The sintering step is to sinter at 1100 - 1250 °C for 12 - 20 h.

[0051] According to some embodiments of the present invention, the method for manufacturing the phosphate-based cathode material Li m A x Mn 1-y B y P 1-z C z O 4-n D n includes the following: A manganese source, a source of element B, and an acid are dissolved in a solvent and stirred to form a suspension of manganese salt doped with element B. The suspension is filtered and the filter cake is dried to obtain manganese salt doped with element B. Here, the stirring is carried out at a temperature within the range of 60 - 120 °C, and / or the stirring is carried out at a stirring speed of 200 - 800 rpm. A lithium source, a phosphorus source, a source of element A, a source of element C, and a source of element D, a solvent, and the manganese salt doped with element B obtained in the previous step are added to a reaction vessel, pulverized, and mixed to obtain a slurry. The slurry obtained in the previous step is transferred to a spray dryer for spray drying granulation to obtain particles. The particles obtained in the previous step are sintered to obtain Li m A x Mn 1-y B y P 1-z C z O 4-n D n The sintering is carried out at a temperature within the range of 1150 - 1250 °C for 10 - 20 hours.

[0052] If there is a coating layer, a coating layer is further formed by a sintering process. Specifically, the prior art can be referred to and will not be described further in this application.

[0053] The manganese source, A source, lithium source, M source, and X source may be selected from corresponding water-soluble salts, such as chloride salts, sulfates, nitrates, and organic acid salts. The phosphorus source may be selected from phosphoric acid, phosphorous acid, pyrophosphate, or corresponding salts. The ammonia source may be selected from ammonium salts.

[0054] The above-mentioned ternary cathode material can be manufactured by referring to manufacturing methods generally used in this field, or by adopting commercially available ternary materials from the prior art. For example, a series of polycrystalline ternary cathode materials produced by Ningbo Rongbai New Energy Technology Co., Ltd. (abbreviated as Rongbai Technology in the examples) can be adopted.

[0055] [Positive electrode plate] The positive electrode plate is generally placed on a positive electrode current collector and a positive electrode film layer installed on at least one surface of the positive electrode current collector, and the positive electrode film layer contains a positive electrode active material.

[0056] For example, a positive electrode current collector has two opposing surfaces in the thickness direction of itself, and the positive electrode film layer is installed on one or both of the two opposing surfaces of the positive electrode current collector.

[0057] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, aluminum foil may be used as the metal foil sheet. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer material substrate (for example, a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0058] In some embodiments, the positive electrode film layer further selectively includes an adhesive. For example, the adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0059] In some embodiments, the cathode film layer further selectively comprises a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0060] In some embodiments, the positive electrode plate may be manufactured by the following method: Components for manufacturing the positive electrode plate, such as a positive electrode active material, a conductive agent, an adhesive, and any other component, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry. The positive electrode slurry is then applied onto a positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode plate is obtained.

[0061] [Negative electrode plate] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer placed on at least one surface of the negative electrode current collector, the negative electrode film layer containing a negative electrode active material.

[0062] For example, the negative electrode current collector has two opposing surfaces in the direction of its own thickness, and the negative electrode film layer is installed on one or both of the two opposing surfaces of the negative electrode current collector.

[0063] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, copper foil may be used as the metal foil sheet. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (such as copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys) on a polymer material substrate (for example, a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0064] In some embodiments, the negative electrode active material may be a negative electrode active material for batteries known in the art. For example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be selected from at least one of elemental silicon, silicate compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, stancate compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may be used. These negative electrode active materials may be used individually or in combination of two or more.

[0065] In some embodiments, the negative electrode film layer further selectively comprises an adhesive. For example, the adhesive may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0066] In some embodiments, the negative electrode film layer further selectively comprises a conductive agent. For example, the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0067] In some embodiments, the negative electrode film layer further selectively includes other auxiliary agents, such as thickeners (e.g., sodium carboxymethylcellulose (CMC-Na)).

[0068] In some embodiments, the negative electrode plate may be manufactured in the following manner: The above components for manufacturing the negative electrode plate, such as a negative electrode active material, a conductive agent, an adhesive, and any other component, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry, the negative electrode slurry is applied onto a negative electrode current collector, and the negative electrode plate is obtained after going through processes such as drying and cold pressing.

[0069] [Electrolytes] The electrolyte plays a role in conducting ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, which may be selected according to the requirements. For example, the electrolyte may be a liquid, a gel, or all-solid.

[0070] In some embodiments, the electrolyte is a liquid and comprises an electrolyte salt and a solvent.

[0071] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethylsulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0072] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethyl methyl sulfone, and diethyl sulfone.

[0073] In some embodiments, the electrolyte further selectively includes additives. For example, the additives may include negative electrode film-forming additives and positive electrode film-forming additives, and may also include additives that can improve some of the battery's performance characteristics, such as additives that improve the battery's overcharge performance, or additives that improve the battery's high-temperature or low-temperature performance.

[0074] [Separator] In some embodiments, the secondary battery further includes a separator. This application is not particularly limited to the type of separator, and any known porous separator having good chemical and mechanical stability may be selected.

[0075] In some embodiments, the material of the separator may be at least one selected from glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of each layer may be the same or different, and are not particularly limited.

[0076] In some embodiments, the positive electrode plate, negative electrode plate, and separator can be manufactured into an electrode assembly by a winding process or a lamination process.

[0077] In some embodiments, the secondary battery may include an outer casing. This casing may be used to package the electrode assembly and electrolyte.

[0078] In some embodiments, the casing of the secondary battery may be a rigid case, such as a rigid plastic case, an aluminum case, or a steel case. The casing of the secondary battery may also be a pouch, such as a bag-shaped pouch. The material of the pouch may be plastic, and examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0079] This application does not particularly limit the shape of the secondary battery, and it may be cylindrical, rectangular, or any other shape. For example, Figure 1 shows a rectangular secondary battery 5 as an example.

[0080] In some embodiments, referring to Figure 2, the casing may include a case 51 and a top cover structure 53. Here, the case 51 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates enclosing and forming a housing cavity. The case 51 has an opening that communicates with the housing cavity, and the top cover structure 53 can cover the opening to seal the housing cavity. The positive electrode plate, negative electrode plate and separator may form an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is packaged within the housing cavity. The electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and a person skilled in the art can select according to the specific practical needs.

[0081] In some embodiments, the secondary batteries may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, and the specific number may be selected by those skilled in the art depending on the application and capacity of the battery module.

[0082] Figure 3 shows an example of a battery module 4. Referring to Figure 3, multiple secondary batteries 5 may be installed in the battery module 4 in a sequential arrangement along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, these multiple secondary batteries 5 may be fixed in place by fasteners.

[0083] Selectively, the battery module 4 may further include a housing having a housing space, in which a plurality of secondary batteries 5 are housed.

[0084] In some embodiments, the battery modules may be assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, the specific number of which can be selected by those skilled in the art depending on the application and capacity of the battery pack.

[0085] Figures 4 and 5 show an example of a battery pack 1. Referring to Figures 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, the upper housing 2 being lidable onto the lower housing 3 and forming a sealed space for housing the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0086] Furthermore, this application provides a power consumption device comprising at least one of a secondary battery, battery module, or battery pack according to this application. The secondary battery, battery module, or battery pack may be used as a power source for the power consumption device or as an energy storage unit for the power consumption device. The power consumption device may include, but is not limited to, mobile devices (e.g., mobile phones, laptop computers, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0087] As the power consumption device, a secondary battery, battery module, or battery pack can be selected according to the usage demand.

[0088] Figure 6 shows an example of a power consumption device. This power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the demand for high output and high energy density of the secondary battery in this power consumption device, a battery pack or battery module can be used. [Examples]

[0089] [Examples] Examples of the present application are described below. The examples described below are illustrative and are used solely for the purpose of interpreting this application and should not be understood as limitations thereon. Unless specific techniques or conditions are specified in the examples, they shall be carried out in accordance with the techniques or conditions described in the literature in the art or in accordance with the product description. Unless the manufacturer is specified, the reagents or equipment used are all commonly available commercial products.

[0090] The source of the cathode material here is LiMn, a phosphate-based cathode material. 0.6 Fe 0.4 PO4 was purchased from Shenzhen Defang Namie Co., Ltd., the ternary cathode material was purchased from Rongbai Technology, and the remaining cathode material was manufactured by the following method.

[0091] (1) Production of co-doped manganese iron lithium core Preparation of Fe, Co, and V co-doped manganese oxalate: 689.5 g of manganese carbonate (MnCO3 equivalent, hereafter the same), 455.2 g of ferrous carbonate (FeCO3 equivalent, hereafter the same), 4.6 g of cobalt sulfate (CoSO4 equivalent, hereafter the same), and 4.9 g of vanadium dichloride (VCl2 equivalent, hereafter the same) were thoroughly mixed in a mixer for 6 hours. The mixture was transferred to a reaction vessel, and 5 liters of deionized water and 1260.6 g of oxalic acid dihydrate (C2H2O4.2H2O equivalent, hereafter the same) were added. The reaction vessel was heated to 80°C and stirred at a rotation speed of 600 rpm for 6 hours until the reaction terminated (no bubbles were produced) to obtain a Fe, Co, V, and S co-doped manganese oxalate suspension. Next, the suspension was filtered, the filtered cake was dried at 120°C, and then pulverized, classified, and sieved through a 325-mesh sieve to obtain Fe, Co, and V co-doped manganese oxalate dihydrate particles.

[0092] Preparation of Fe, Co, V, and S co-doped lithium manganese iron phosphate: 1793.4 g of manganese oxalate dihydrate particles obtained in the previous step, 369.0 g of lithium carbonate (equivalent to Li2CO3, the same applies hereafter), 1.6 g of 60% dilute sulfuric acid (equivalent to 60% H2SO4, the same applies hereafter), and 1148.9 g of ammonium dihydrogen phosphate (equivalent to NH4H2PO4, the same applies hereafter) were added to 20 L of deionized water, and the mixture was stirred for 10 hours to obtain a slurry. The slurry was transferred to a spray drying apparatus and spray-dried and granulated, with the drying temperature set to 250°C and dried for 4 hours to obtain a powder material. The powder material was sintered at 1200°C for 16 hours in a nitrogen gas (90 vol%) + hydrogen gas (10 vol%) protective atmosphere to obtain 1572.1 g of Fe, Co, V, and S co-doped lithium manganese iron phosphate.

[0093] Production example 2: Li 0.994 Mo 0.001 Mn 0.65 Fe 0.35 P 0.999 Si 0.001 O 3.999 F 0.001 Manufacturing 1) Manufacturing of positive electrode active material Preparation of doped manganese oxalate: 1.3 mol of MnSO4·H2O and 0.7 mol of FeSO4·H2O were thoroughly mixed in a mixer for 6 hours. The mixture was transferred to a reaction vessel, and 10 L of deionized water and 2 mol of oxalic acid dihydrate (oxalic acid equivalent) were added. The reaction vessel was heated to 80°C and stirred at a rotation speed of 600 rpm for 6 hours until the reaction was terminated (no bubbles were formed) to obtain a suspension of Fe-doped manganese oxalate. The suspension was then filtered, the filtered cake was dried at 120°C, then pulverized, classified, sieved through a 325 mesh, and pulverized to the target particle size as needed to obtain Fe-doped manganese oxalate particles.

[0094] Preparation of doped manganese iron lithium phosphate: 1 mol of the above manganese oxalate particles, 0.497 mol of lithium carbonate, 0.001 mol of Mo(SO4)3, an 85% aqueous phosphoric acid solution containing 0.999 mol of phosphoric acid, 0.001 mol of H4SiO4, 0.0005 mol of NH4HF2, and 0.005 mol of sucrose were taken and added to 20 L of deionized water. The mixture was transferred to a sand mill and thoroughly ground and stirred for 10 hours to obtain a slurry. The slurry was transferred to a spray dryer and spray dried and granulated, with the drying temperature set to 250°C and dried for 4 hours to obtain particles. The above powder material was sintered at 1150°C for 15 hours in a protective atmosphere of nitrogen gas (90 vol%) + hydrogen gas (10 vol%) to obtain carbon-coated Li 0.994 Mo 0.001 Mn 0.65 Fe 0.35 P 0.999 Si 0.001 O 3.999 F 0.001 I obtained it.

[0095] By adjusting the heating temperature of the reaction vessel, the number of meshes used in the sieving, and the sintering temperature of the materials obtained in the above-mentioned Manufacturing Example 1 and Manufacturing Example 2, the particle size, volume particle size distribution, and specific surface area of ​​the primary particles are adjusted, and this application does not describe each manufacturing process of each material individually.

[0096] Here, SEM is used to determine that the phosphate-based cathode material and ternary cathode material in each example are polycrystalline secondary spheres.

[0097] The particle size of the phosphate-based cathode materials and ternary cathode materials in each example was measured by powder laser particle size testing: referring to national standard GB / T19077-2016, the solvent used was deionized water, and ultrasound was used for 5 minutes before the test.

[0098] Powder Specific Surface Area (BET) Test: The test was conducted according to GB / T 19587-2004. Before the test, the powder was placed in a vacuum oven and dried at 200°C for ≥2 hours, and the required amount of powder was weighed out >20g.

[0099] Powder primary particle size test: The primary particle size was confirmed by measuring the powder using SEM.

[0100] Compaction test: Weigh 1.00 ± 0.05 g of material powder, record the weight data M (in g), and place all the powder material into the groove of the mold (groove area S = 1.327 cm²). 2 The mixture was injected into the container, another steel gasket was taken and pressed flat against the powder, and the flat side of the steel column was pressed against the gasket. The height of the steel column at this time was H0. After pressurizing to 30000N, it was held for 30s, the pressure was released, and after waiting for 10s, the height of the steel column H1 was read. Consolidation density = M / [(H1-H0)*S] (The consolidation density of the phosphate-based cathode material is 2.3 g / cm³). 3 (To that extent).

[0101] Gram Capacity Test: Each of the manufactured button batteries was left standing for 5 minutes in a constant temperature environment of 25°C, discharged to 2.5V at 0.1C, left standing for 5 minutes, then charged at 0.1C to 4.3V or 4.25V (Ni content > 70%, upper voltage limit 4.25V) using constant current and constant voltage, and then charged at 4.3V or 4.25V with a current ≤ 0.05mA, left standing for 5 minutes. The charge capacity at this time was denoted as C0, and then discharged to 2.5V at 0.1C. The discharge capacity at this time was the initial discharge capacity and was denoted as D0.

[0102] The tested discharge capacity value (i.e., initial discharge capacity D0) is divided by the mass of the positive electrode active material in the button cell to obtain the gram capacity of the positive electrode active material.

[0103] ICP testing of positive electrode plates Approximately 0.4 g of dried cathode plate was taken, 10 ml of aqua regia was added, then the mixture was placed on a hot plate and heated to 180°C. After standing for 30 minutes to digest the cathode plate, it was cooled to room temperature, and then transferred to a 100 ml volumetric flask and brought to a final volume. A 1 ml sample was taken and diluted to 100 ml, and the content of elements Ni, Co, and Mn was measured using a thermometer.

[0104] Gram capacity of the phosphate-based cathode material and ternary cathode material used in the examples, D V 50, D V 90. Record the BET specific surface area in Table 1.

[0105] [Table 1-1] [Table 1-2] [Table 1-3]

[0106] Here, NCM-21 is a single-crystal particle, while the rest are all polycrystalline particles.

[0107] Table 2 shows the composition of the cathode material composition for each example and comparative example (where the proportion of LMFP is the mass ratio of LMFP to NCM).

[0108] [Table 2-1] [Table 2-2]

[0109] The electrical performance was tested as follows:

[0110] (1) Manufacturing of mixed electrode laminate batteries: Manufacturing of mixed cathodes: The A and B system materials from each of the above examples and comparative examples were added to the cathode active material (mixing ratio based on the mass ratio of both, mA + mB = 100%), polyvinylidene fluoride (PVDF), and a fixed amount of N-methylpyrrolidone (NMP) as conductive carbon, with a mass ratio of active material:PVDF:conductive carbon of 90:5:5. A uniform slurry was produced by stirring in a drying chamber, controlling the viscosity to 3000-10000 mPa·s, and the slurry was applied to aluminum foil. A cathode plate was manufactured by drying and cold pressing. Manufacturing of graphite negative electrodes: Artificial graphite is used as the negative electrode active material, with a mass ratio of carboxymethylcellulose sodium (CMC-Na), conductive carbon, and styrene-butadiene rubber (SBR) of 94:1.5:2:2.5. A certain amount of deionized water is added, and the mixture is stirred in a drying chamber to produce a uniform slurry. The viscosity is controlled to 2000-12000 mPa·s. The slurry is applied to copper foil, and the coating mass of the negative electrode is determined by the matching relationship with the positive electrode (94% * negative electrode coating mass * graphite gram capacity = 1.15 * 90% * positive electrode coating mass * mixed positive electrode gram capacity, where the gram capacity refers to the gram capacity information of the material after the third powder cycle for lithium half-cells). The negative electrode plate is then manufactured by drying and cold pressing. The electrolyte used is 1 mol / L LiPF6 / (ethylene carbonate (EC) + diethyl carbonate (DEC) + dimethyl carbonate (DMC)) (volume ratio 1:1:1) + 5 wt.% fluoroethylene carbonate (FEC). A porous polymerized polyethylene (PE) film was used as a separator.

[0111] The laminated battery cores were assembled in a drying chamber through processes such as plate punching, tab cleaning, lamination, welding, top sealing, fluid injection, pre-conversion, extraction, conversion, and molding, in preparation for testing.

[0112] (2) Initial gram capacity test of laminated batteries: Each of the manufactured laminated batteries was left standing for 5 minutes in a constant temperature environment of 25°C, discharged to 2.5V at 1 / 3C, left standing for 5 minutes, then charged at 1 / 3C to 4.3V or 4.25V (Ni content > 70%, upper voltage limit 4.25V) with constant current and constant voltage, then charged at 4.3V or 4.25V with constant voltage until the current ≤ 0.05mA, left standing for 5 minutes, and the charge capacity at this time was denoted as C0. Then, it was discharged to 2.5V at 1 / 3C0, and the discharge capacity at this time was the initial discharge capacity and denoted as D0.

[0113] Dividing the tested discharge capacity value (i.e., initial discharge capacity D0) by the mass of the positive electrode active material in the secondary battery gives the total initial electrical gram capacity of the positive electrode active material.

[0114] (3) Cycle performance test of secondary batteries at 25°C Each of the manufactured secondary batteries was charged to 4.3V or 4.25V at 2.5~4.3V or 4.25V with 0.5C0 in a constant temperature environment of 25°C, then charged at a constant voltage of 4.3V or 4.25V to a current of ≤0.05mA, left to stand for 5 minutes, and then discharged to 2.5V with 0.5C. The capacity was recorded as Dn (n=1, 2, 3...), and the above operation was repeated for >5000 cycles. The capacity fading value was measured, and the degree of battery core fading (State of Health) was defined according to the ratio of Dn / D3. The number of cycles for each battery core when the fading reached 80% SOH was compared and used as an evaluation index for cycle capability.

[0115] (4) Charging capacity experiment: First, a capacity test is performed on the pouch-laminated battery, and the flow is as follows: After constant current charging at 0.33C until the full charge voltage V1, it is converted to constant voltage charging. When the charging current decreases to 0.05C, constant voltage charging ends, and then it is discharged at 0.33C until the full discharge voltage V2. This flow is repeated three times, and the capacity result from the third time is used as the baseline, and the gram capacity of the positive electrode can be calculated using the result from the third time.

[0116] Perform charge tests on the pouch laminate battery at different rates (C1 < C2 < C3 < C4 < …… < Cn). In the test, it is necessary to increase the charge rate from a lower rate to a higher rate. During the charging process, it is necessary to simultaneously monitor the total electrical voltage of the pouch laminate battery and the negative electrode voltage of the pouch laminate battery. As a detailed process, the pouch laminate battery is charged at C1 until the full charge voltage V1 or the negative electrode voltage reaches 0V, and the battery SOC value at the end of charging is extracted. Subsequently, it is discharged at 0.33C until the full discharge voltage V2. By repeating the above process, the SOC values at the end of charging at different rates can be obtained. Here, Cn when charging at 100% SOC is the charging capacity of the battery core of this solution.

[0117] (5) Low-temperature discharge capacity experiment In a constant temperature environment of 25°C, let the battery stand for 30 minutes, then discharge it at a constant current of 0.33C until the lower cut-off voltage of 2.5V, let it stand for 5 minutes, charge it at a constant current of 0.33C until the upper cut-off voltage (4.4V), then charge it at a constant voltage until the current < 0.05C, let it stand for 5 minutes, and then discharge it at a constant current of 0.33C until the lower cut-off voltage of 2.5V. Record the discharge capacity at this time, which becomes the initial discharge capacity C0.

[0118] Operate the battery at 5°C according to the above process and record the discharge capacity Cn. Calculate the discharge capacity retention rate of the battery at a low temperature of -5°C using the following formula.

[0119] Low-temperature discharge capacity = 100% × Cn / C0 Record the test results in Table 3.

[0120]

Table 3-1

Table 3-2

[0121] As can be seen from the comparison of Examples 1 to 5 in the table above, the cycle life increases first and then decreases as the phosphate-based cathode material decreases. This is because the cycle performance of the phosphate-based cathode material itself is superior to that of the ternary cathode material, but when mixed with the ternary cathode material in an appropriate ratio, the lithium and iron in the mixture play an auxiliary role in the stability of the cycle performance of the ternary cathode material. Therefore, when the content of the phosphate-based cathode material in the mixture of the two is greater than 80%, the cycle life of the battery is further improved, and the charge and discharge capacity of the battery gradually improves as the content of the phosphate-based cathode material increases.

[0122] As can be seen from the comparison between Examples 6-16, Examples 21-24 and Example 1, the D of the phosphate-based cathode material V When controlling 50 within the range of 7 to 30 μm, or when controlling the particle size of the primary particles of the phosphate-based cathode material to 35 to 110 nm, or when controlling the D of the ternary cathode material V When the 50 is controlled to 5-11 μm, good charging and discharging capabilities of the battery can be achieved.

[0123] As can be seen from the comparison between Examples 17-20, 34-26 and Example 1, changes in the BET specific surface area of ​​both the phosphate-based cathode material and the ternary cathode material affect the battery's charge / discharge capacity and cycle performance. If the BET specific surface area of ​​the phosphate-based cathode material and the ternary cathode material is too large, the cycle performance and charging capacity will be significantly reduced.

[0124] As can be seen from the comparison between Examples 25-33 and Example 1, the molar content of Ni has a significant effect on improving the energy density of the mixed material, and the molar content of Co improves the electronic and ionic conductivity of the system, effectively improving the charge and discharge capacity of the cathode material.

[0125] While this application has been written with reference to preferred embodiments, various improvements can be made thereto, and components thereof can be replaced with equivalents, without departing from the scope of this application. In particular, unless there is a structural conflict, each technical feature referred to in each embodiment may be combined in any manner. This application is not limited to the specific embodiments disclosed in the specification, but includes all technical ideas that fall within the scope of the claims. [Explanation of Symbols]

[0126] 1: Battery pack, 2: Upper casing, 3: Lower casing, 4: Battery module, 5: Rechargeable battery, 51: Case, 52: Electrode assembly, 53: Top cover structure.

Claims

1. A cathode material composition comprising a phosphate-based cathode material and a ternary cathode material, wherein the weight of the phosphate-based cathode material is denoted as W1, the weight of the ternary cathode material is denoted as W2, α = W1 / (W1+W2), 50% ≤ α ≤ 97%, selectively 70% ≤ α ≤ 90%, and the phosphate-based cathode material is a polycrystalline secondary sphere material and / or the ternary cathode material is a polycrystalline secondary sphere material.

2. The particle size distribution of the cathode material composition satisfies the relationship 14 > Aα + B(1-α) > 7, where A is D of the phosphate-based cathode material. Ｖ 50, and B is the D of the ternary cathode material. Ｖ The positive electrode material composition according to claim 1, wherein the coefficient is 50.

3. The particle size of the primary particles of the phosphate-based cathode material is 10 to 600 nm, selectively 35 to 110 nm, and selectively the laser particle size D of the phosphate-based cathode material. Ｖ 50 is 7-30 μm, D Ｖ 50 selectively targets 8-14 μm, D Ｖ The positive electrode material composition according to claim 1 or 2, wherein the thickness is 90 < 30 μm.

4. The BET specific surface area of ​​the phosphate-based cathode material is 8-20 m². ２ A positive electrode material composition according to any one of claims 1 to 3, wherein the value is / g.

5. The chemical formula of the phosphate-based cathode material is Li １＋ｘ Mn １－ｙ A ｙ P １－ｚ R ｚ O ４ wherein in the chemical formula, x is any numerical value within the range of -0.100 to 0.100, y is any numerical value within the range of 0.001 to 0.500, z is any numerical value within the range of 0.001 to 0.100, the values of x, y and z satisfy the condition of keeping the chemical formula electrically neutral, A is one or more elements selected from Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb and Ge, optionally one or more elements of Fe, Ti, V, Ni, Co and Mg, R is one or more elements selected from B, Si, N, S, F, Cl and Br, and optionally, R is one element selected from B, Si, N and S, Alternatively, the chemical formula of the phosphate-based cathode material is Li ａ A ｘ Mn １－ｙ B ｙ P １－ｚ C ｚ O ４－ｎ D ｎ The cathode material composition according to any one of claims 1 to 4, wherein A comprises one or more elements from the group consisting of Zn, Al, Na, K, Mg, Nb, Mo, and W; B comprises one or more elements from the group consisting of Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge; C comprises one or more elements from the group consisting of B (boron), S, Si, and N; D comprises one or more elements from the group consisting of S, F, Cl, and Br; a is selected from the range of 0.9-1.1; x is selected from the range of 0.001-0.1; y is selected from the range of 0.001-0.5; z is selected from the range of 0.001-0.1; n is selected from the range of 0.001-0.1; and the phosphate-based cathode material is electrically neutral.

6. The phosphate-based cathode material includes a polycrystalline core and a coating layer covering the polycrystalline core, wherein the polycrystalline core has the chemical formula Li １＋ｘ Mn １－ｙ A ｙ P １－ｚ R ｚ O ４ A material having the chemical formula Li ａ A ｘ Mn １－ｙ B ｙ P １－ｚ C ｚ O ４－ｎ D ｎ The positive electrode material composition according to claim 5, comprising a material having, wherein the coating layer is selectively one or more layers of pyrophosphate, phosphate, and carbon.

7. The ternary cathode material D Ｖ 50 is 5-11 μm, D Ｖ The cathode material composition according to any one of claims 1 to 6, wherein the average particle size of the primary particles of the ternary cathode material is 50 to 800 nm, and the particle size is 99 ≤ 30 μm.

8. The BET specific surface area of ​​the aforementioned ternary cathode material is 0.2 to 1.2 m². ２ A positive electrode material composition according to any one of claims 1 to 7, wherein the value is / g.

9. The ternary cathode material is an NCM ternary cathode material or an NCA ternary cathode material, and selectively, the molar content of Ni in the ternary cathode material is 50% to 75% and the molar content of Co is 0.5% to 49.5%, and more selectively, the molar content of Ni is 50% to 70% and the molar content of Co is 5% to 35%, the cathode material composition according to any one of claims 1 to 8.

10. The aforementioned ternary cathode material has the chemical formula Li ａ’ Ni ｂ’ Co ｃ’ M1 ｄ’ M2 ｅ’ O ｆ’ R' ｇ’ The positive electrode material composition according to claim 9, having the following properties: 0.75 ≤ a' ≤ 1.2, 0, 0 < b' < 1, 0 < c' < 1, 0 < d' < 1, 0 ≤ e' ≤ 0.2, 1 ≤ f' ≤ 2.5, 0 ≤ g' ≤ 1, f' + g' ≤ 3, M1 is an element Mn and / or an element Al, M2 is one or more elements selected from Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, Nb, and R' is one or more elements selected from N, F, S, Cl.

11. A secondary battery, wherein the secondary battery includes a positive electrode plate, the positive electrode plate includes a positive electrode active material, and the positive electrode active material is a positive electrode material composition according to any one of claims 1 to 10.

12. A power consumption device including a secondary battery, wherein the secondary battery is selected from the secondary batteries described in claim 11.

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