Positive electrode active material, secondary battery, battery module, battery pack, and power consumption device

Abstract

Provided are a positive electrode active material, a secondary battery, a battery module, a battery pack, and an electric power consuming device. The positive electrode active material includes a spinel-type lithium manganese-containing composite oxide having a molecular formula of Li 1+x A a M b X c Mn 2-a-b-c-x O 4-t In the molecular formula, A is a manganese-site doping element of the spinel-type lithium manganese-containing composite oxide, and A includes one or more of V, Nb, Ta, Mo, W, Ru, Rh, Sn, Sb, Te, Tl, Pd, Bi, and Po. M is used to form a second phase containing O and a polyoxyanion, and M includes one or more of B, C, N, Si, P, S, and Cl. X includes one or more of Mg, Al, Si, Ca, Sc, Ti, Cr, Fe, Co, Ni, Cu, Zn, and Zr, and -0.1 ≦ x ≦ 0.3, 0 < a ≦ 0.2, 0 < b ≦ 0.2, 0 ≦ c ≦ 0.7, 0 ≦ t ≦ 0.2. By simultaneously doping A and M into the positive electrode active material, the cycle storage performance and cycle service life of the secondary battery at high temperatures can be improved simultaneously. Figure 1

Description

[Technical Field]

[0001] This application relates to the technical field of battery manufacturing, and more particularly to positive electrode active materials, secondary batteries, battery modules, battery packs, and power consumption devices. [Background technology]

[0002] Rechargeable batteries have advantages such as small volume, high energy density, high safety, low self-discharge, and long lifespan, and are widely applied in many fields such as energy storage, communications, electric vehicles, and aerospace. Batteries include multiple secondary batteries connected in series, parallel, or series-parallel. The positive electrode active material is an important component of secondary batteries, as it provides lithium ions that move back and forth between the positive and negative electrodes for the charging and discharging process of the secondary battery, and is therefore crucial for the performance of the battery.

[0003] While spinel-type lithium manganese-containing composite oxides have high theoretical capacity, their poor high-temperature cycling performance limits their application. Therefore, improving the high-temperature cycling performance of secondary batteries is an urgent technological challenge that needs to be addressed. [Overview of the Initiative]

[0004] This application was made in view of the above-mentioned problems, and aims to provide a positive electrode active material capable of improving the cycle performance of a secondary battery, and a secondary battery, battery module, battery pack, and power consumption device manufactured with said positive electrode active material.

[0005] To achieve the above objective, a first aspect of the present application provides a positive electrode active material having the molecular formula Li 1+x A a M b X c Mn 2-a-b-c-x O 4-tThe material contains a spinel-type lithium manganese-containing composite oxide, in which A is the manganese moiety doping element of the spinel-type lithium manganese-containing composite oxide, and A comprises one or more of V, Nb, Ta, Mo, W, Ru, Rh, Sn, Sb, Te, Tl, Pd, Bi, and Po; M is used to form a second phase containing O and a polyoxyanion, and M comprises one or more of B, C, N, Si, P, S, and Cl; X comprises one or more of Mg, Al, Si, Ca, Sc, Ti, Cr, Fe, Co, Ni, Cu, Zn, and Zr, and -0.1≦x≦0.3, 0 <a≦0.2、0<b≦0.2、0≦c≦0.7、0≦t≦0.2である。

[0006] As a result, in the embodiments of the present invention, doping the positive electrode active material with A and M simultaneously stabilizes the spinel structure and also provides the ability to capture HF in the electrolyte. After capturing HF, the positive electrode active material can form a more stable fluorinated oxide containing elements A and M. In other words, elements A and M exert a synergistic effect, not only protecting the structural stability of the positive electrode active material but also protecting the entire battery system, improving cycle storage performance and cycle life at high temperatures.

[0007] In some embodiments, A includes one or more of Nb, Ta, Mo, W, Ru, Te, and Tl.

[0008] In some embodiments, M comprises one or more of Si, S, and Cl.

[0009] In some embodiments, X comprises one or more of Al, Sc, Cr, Ni, Cu, Zn, and Ti, and / or 0.1 ≤ c ≤ 0.6.

[0010] As a result, the element X in the embodiment of the present application enhances the average valence state of manganese and manganese moieties in the spinel structure, increases the average valence of manganese and manganese moieties during the charge-discharge process to more than +3.5, reduces the risk of Jahn-Teller strain occurring in the spinel structure, and improves the structural stability and capacity characteristics of the positive electrode active material.

[0011] In some embodiments, the spinel-type lithium manganese-containing composite oxide comprises a first region and a second region sequentially distributed along the direction from its center to its outer surface, wherein the volume fraction content of the second region is p ≤ 50% based on the volume of the spinel-type lithium manganese-containing composite oxide, the percentage of element A located in the second region is m based on the total mass of element A in the spinel-type lithium manganese-containing composite oxide, and the percentage of element M located in the second region is n based on the total mass of element M in the spinel-type lithium manganese-containing composite oxide, where m + n ≥ 70%, selectively 10% ≤ p ≤ 30%, and / or 80% ≤ m + n ≤ 95%.

[0012] As a result, elements A and M in the embodiment of the present application are concentrated in the second region, and the synergistic effect of elements A and M provides sufficient protection to the surface layer of the spinel-type lithium manganese composite oxide, enhances the structural stability of the surface layer, improves the overall structural stability of the positive electrode active material, contributes to the capacity expression of the positive electrode active material, and further improves the cycle performance and cycle life of the secondary battery employing the positive electrode active material.

[0013] In some examples, the molecular formula is such that -0.1 ≤ x ≤ 0.3 and / or 0 ≤ t ≤ 0.2. This makes the structure of the spinel-type lithium manganese-containing composite oxide in the examples of this application more stable and contributes more to capacity expression.

[0014] In some embodiments, the molecular formula is such that 0.001 ≤ a ≤ 0.1 and / or 0.001 ≤ b ≤ 0.1, and selectively, 0.005 ≤ a + b ≤ 0.1.

[0015] Therefore, when the A element and the M element of the embodiment of the present application simultaneously satisfy the above range, the synergistic effect between the A element and the M element can be fully exerted, enhancing the structural stability of the positive electrode active material and contributing to the capacity performance of the positive electrode active material, thereby improving the cycle storage performance and cycle service life of the positive electrode active material at high temperatures.

[0016] In some embodiments, the specific surface area of the spinel-type lithium manganese-containing composite oxide is 0.01 m 2 / g to 1.5 m 2 / g, and optionally 0.1 m 2 / g to 1 m 2 / g.

[0017] Thereby, the specific surface area of the spinel-type lithium manganese-containing composite oxide of the embodiment of the present application is relatively small, reducing the risk of side reactions occurring on the surface, and contributing to the long-term cycle stability of the secondary battery manufactured using the spinel-type nickel manganese lithium-containing composite oxide as the positive electrode active material. The surface of the spinel structure is more comprehensively covered and easily modified, enhancing the structural stability of the entire spinel structure. Also, there is a positive correlation between the quality of the modification layer for modifying the spinel structure and the specific surface area of the spinel structure, and the thickness of the modification layer of the embodiment of the present application is not too large, ensuring the kinetic performance of the spinel structure.

[0018] In some embodiments, the average particle size D V50 of the spinel-type lithium manganese-containing composite oxide is 1 μm to 20 μm, and optionally 2 μm to 15 μm.

[0019] Thereby, when the average particle size D V50 of the spinel-type lithium manganese-containing composite oxide of the embodiment of the present application is within the above range, the crystal structure is relatively perfect, the surface of the crystal particles is stable and the specific surface area is small, and during the manufacturing process, it is easy to perform doping on the second region of the spinel-type lithium manganese-containing composite oxide, The consumption of elements such as Li and O has decreased. and at the same time, it has excellent processing performance when used later. Therefore, the overall performance of the materials and batteries can be improved. .

[0020] In several examples, a and b in the molecular formula and the average particle size D of the spinel-type lithium manganese-containing composite oxide V50 During this period, 0.01 ≤ (a+b) × D V50 It satisfies ≤ 1.

[0021] Therefore, in the embodiments of this application, the doping amounts of element A and element B and the average particle size D of the spinel-type lithium manganese-containing composite oxide are determined. V50 By simultaneously controlling these factors, it is possible to achieve both structural stability and dynamic performance in spinel-type lithium manganese-containing composite oxides.

[0022] In some embodiments, the spinel-type lithium manganese-containing composite oxide has the form of single crystal particles or pseudo-single crystal particles.

[0023] As a result, single-crystal or pseudo-single-crystal particles have fewer grain boundaries within the particles, reducing the likelihood of particle fracture during subsequent processing and use of the secondary battery, resulting in a more stable structure and contributing to improved long-term stability of the secondary battery. Furthermore, single-crystal or pseudo-single-crystal particles have high dispersibility, making it easier to achieve uniform and comprehensive surface modification. Polycrystalline particles have a large number of grain boundaries within them, making them prone to fracture at the grain boundaries during subsequent processing and use. After fracture, a new surface is exposed that has not been modified and lacks the electrolyte interface CEI film, further degrading battery performance.

[0024] In some embodiments, the spinel-type lithium manganese-containing composite oxide has at least one of the following shapes: octahedral particle shape, truncated octahedral particle shape, and regular polyhedral particle shape with beveled octahedra.

[0025] As a result, the crystal planes on the surface of the crystal grains of the spinel-type lithium manganese-containing composite oxide described above are more stable, and the surface is smaller, which helps to mitigate surface side reactions, thereby improving the structural stability of the positive electrode active material.

[0026] A second aspect of the present application provides a battery module including a secondary battery according to any one embodiment of the first aspect of the present application.

[0027] A third aspect of the present application provides a battery pack including the battery module of the second aspect of the present application.

[0028] A fourth aspect of the present application provides a power consumption device comprising at least one selected from a secondary battery according to any one embodiment of the first aspect of the present application, a battery module according to the second aspect of the present application, or a battery pack according to the third aspect of the present application. [Brief explanation of the drawing]

[0029] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings necessary for use in the embodiments of this application will be briefly described below. However, obviously, the drawings described below represent only a few embodiments of this application, and those skilled in the art can obtain further drawings based on these drawings without any creative effort. [Figure 1] This is a schematic diagram of a secondary battery according to one embodiment of the present invention. [Figure 2] Figure 1 is an exploded view of a secondary battery according to one embodiment of the present invention. [Figure 3] This is a schematic diagram of a battery module according to one embodiment of the present invention. [Figure 4] This is a schematic diagram of a battery pack according to one embodiment of the present invention. [Figure 5] Figure 4 is an exploded view of a battery pack according to one embodiment of the present invention. [Figure 6] A schematic diagram of a power consumption device according to one embodiment of the present invention. [Figure 7] This is a schematic diagram illustrating the regional division of the positive electrode active material particles in the present invention. [Figure 8] This is a morphological diagram of the positive electrode active material manufactured in Example 51. [Modes for carrying out the invention]

[0030] Hereinafter, embodiments specifically disclosing the positive electrode active material, secondary battery, battery module, battery pack, and power consumption device of the present application will be described in detail with appropriate reference to the drawings. Unnecessary details may be omitted. For example, detailed explanations of well-known matters and redundant explanations of substantially the same structures may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to ensure that it is easily understood by those skilled in the art. Furthermore, the drawings and the following explanation are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the essence of the claims.

[0031] The “range” disclosed herein 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, and the boundaries of the given range are limited by the selected lower limit and upper limit. The range thus limited may include the values ​​at both ends, or it may not include the values ​​at both ends, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if the ranges 60~120 and 80~110 are listed for a given parameter, it is understood that the ranges 60~110 and 80~120 are also expected. Also, if 1 and 2 are listed as the minimum range values, and 3, 4 and 5 are listed as the maximum range values, then the ranges 1~3, 1~4, 1~5, 2~3, 2~4 and 2~5 are all expected. In this application, unless otherwise stated, the numerical range “a~b” represents an abbreviated expression for any combination of real numbers between a and b, and both a and b are real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 to 5" are listed in this specification, and "0 to 5" is simply an abbreviated representation of combinations of these numbers. Furthermore, when it is stated that a parameter is an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0032] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined to form new technical solutions.

[0033] Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions.

[0034] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably in order. For example, if it is stated that the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, if it is stated that the method may further include step (c), it means that step (c) can 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).

[0035] Unless otherwise specified, the terms “include” and “incorporate” as used herein may be in open-ended form or closed-ended form. For example, “include” and “incorporate” may further include or incorporate other components not listed, or may include or incorporate only the listed components.

[0036] 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 one of the following conditions satisfies the condition “A or B”: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0037] [Cathode active material] Lithium manganese-containing composite oxides (LMOs) have a spinel structure in which the oxygen atoms are face-centered cubic packed and occupy the 32e position in the crystal lattice structure, the lithium atoms are tetrahedral, and the transition metal element manganese belongs to the octahedral coordination. The spinel structure provides a good channel for the insertion and removal of lithium ions, contributing to the charging and discharging of secondary batteries. In this specification, since the lithium atom is located at the 8a position of the tetrahedron, the 8a position of the tetrahedron is referred to as the "lithium moiety," and since the manganese atom is located at the 16d position of the octahedron, the 16d position of the octahedron is referred to as the "manganese moiety."

[0038] Manganese compounds have many valence states. In lithium spinelmanganate, the average valence state of manganese is +3.5, with some manganese existing in a +3 state. The divalent manganese is unstable and easily undergoes disproportionation reactions to produce divalent and tetravalent manganese.

[0039] The inventor's research showed that if a spinel-type lithium manganese-containing composite oxide (LMO) is used as the positive electrode active material for a secondary battery, a side reaction occurs on the surface of the positive electrode active material during the charging process of the secondary battery, especially after charging to a high voltage (oxygen deficiency, hydrogen ion H2). + Mn 2+ Elution of transition metal ions such as Mn is likely to occur, and in particular Mn 2+ We found that when manganese dissolves in the electrolyte, the structure of the positive electrode active material is destroyed, the material's structure becomes unstable during the cycling process, and the cycling performance deteriorates. At the same time, a small amount of water may be present in the electrolyte, and this water reacts with the electrolyte salt to produce hydrofluoric acid (HF). The presence of HF further promotes the dissolution of manganese, creating a vicious cycle.

[0040] Also, H + It diffuses into the negative electrode sheet and is reduced to produce H2, Mn 2+The ions diffuse and deposit on the negative electrode sheet, reducing the ionic conductivity of the solid electrolyte interface (SEI) film. This creates a risk of the secondary battery swelling during high-temperature storage and cycling, resulting in rapid capacity decay, poor long-term stability at high temperatures and voltages, and ultimately shortening the battery's lifespan.

[0041] In view of this, the inventors in this application modify the positive electrode active material by adding doping elements such as element A, element M, and element X, and there is a desire to improve the high-temperature storage performance and cycle performance of secondary batteries using this positive electrode active material.

[0042] The positive electrode active material provided by this application has the molecular formula Li 1+x A a M b X c Mn 2-a-b-c-x O 4-t The material contains a spinel-type lithium manganese-containing composite oxide, in which A is the manganese moiety doping element of the spinel-type lithium manganese-containing composite oxide, and A comprises one or more of V, Nb, Ta, Mo, W, Ru, Rh, Sn, Sb, Te, Tl, Pd, Bi, and Po; M is used to form a second phase containing O and a polyoxyanion, and M comprises one or more of B, C, N, Si, P, S, and Cl; X comprises one or more of Mg, Al, Si, Ca, Sc, Ti, Cr, Fe, Co, Ni, Cu, Zn, and Zr, and -0.1≦x≦0.3, 0 <a≦0.2、0<b≦0.2、0≦c≦0.7、0≦t≦0.2である。

[0043] A may include subgroup elements and / or main group elements, and exemplary A includes one or more of V, Nb, Ta, Mo, W, Ru, Rh, Sn, Sb, Te, Tl, Pd, Bi, and Po, and selectively A includes one or more of Nb, Ta, Mo, W, Ru, Te, and Tl.

[0044] Element A can be doped into the spinel structure, mainly replacing some manganese ions and entering the manganese site. Element A forms a strong interaction with a plurality of surrounding oxygen atoms, significantly stabilizing the oxygen atoms, weakening the side reactions (such as oxygen deficiency, etc.) occurring on the surface of the cathode active material at high voltages, and can improve the structural stability of the cathode active material.

[0045] M is used to form a second phase containing oxygen atoms and polyoxyanions, can absorb hydrofluoric acid HF generated in the electrolyte at high voltages, and the stability of the generated fluorinated anions in the electrolyte is high. Exemplarily, M contains one or more of B, C, N, Si, P, S, and Cl. Optionally, M contains one or more of Si, S, and Cl.

[0046] In the embodiments of the present application, by simultaneously doping A and M into the cathode active material, while stabilizing the spinel structure, it also has the ability to capture HF in the electrolyte. After capturing HF, the cathode active material can form a more stable fluorinated oxide containing elements A and M. That is, elements A and M exert a synergistic effect, which can not only protect the structural stability of the cathode active material, but also protect the entire battery system, and improve the cycle storage performance and cycle service life at high temperatures.

[0047] In some embodiments, the cathode active material may not be doped with element X. In this case, c = 0, and the molecular formula of the spinel-type lithium manganese-containing composite oxide is Li 1+x A a M b Mn 2-a-b-x O 4-t and the synergistic effect of A and M improves the performance of the cathode active material.

[0048] In some embodiments, the cathode active material is further doped with element X. In this case, 0 < c ≤ 0.7, optionally, 0.1 ≤ c ≤ 0.6. Exemplarily, c may be 0.1, 0.2, 0.3, 0.4, 0.5, or 0.6.

[0049] X comprises one or more of Mg, Al, Si, Ca, Sc, Ti, Cr, Fe, Co, Ni, Cu, Zn, and Zr. Selectively, X comprises one or more of Al, Sc, Cr, Ni, Cu, Zn, and Ti.

[0050] Element X can increase the average valence state of manganese and manganese moieties in the spinel structure, raise the average valence of manganese and manganese moieties to above +3.5 during the charge-discharge process, reduce the risk of Jahn-Teller strain occurring in the spinel structure, and improve the structural stability and capacity characteristics of the positive electrode active material. In particular, if X contains one or more of Al, Sc, Cr, Ni, Cu, Zn, and Ti, and c ≤ 0.1 ≤ 0.6, element X can significantly improve the structural stability of the positive electrode active material and can exert a synergistic effect with elements such as phosphorus (P) to jointly improve the performance of the positive electrode active material.

[0051] In some embodiments, the spinel-type lithium manganese-containing composite oxide comprises a first region and a second region sequentially distributed along the direction from its center to its outer surface, wherein the volume fraction content of the second region is p ≤ 50% based on the volume of the spinel-type lithium manganese-containing composite oxide, the percentage of element A located in the second region is m based on the total mass of element A in the spinel-type lithium manganese-containing composite oxide, and the percentage of element M located in the second region is n based on the total mass of element M in the spinel-type lithium manganese-containing composite oxide, where m + n ≥ 70%, selectively 10% ≤ p ≤ 30%, and / or 80% ≤ m + n ≤ 95%.

[0052] The positive electrode active material particles are divided into a first region and a second region by volume, with the first region located in the central part of the particle and the second region located in the part away from the center of the particle. However, the first and second regions are continuous parts with no clear interface between them, and dividing the positive electrode active material particles into different regions is merely for the purpose of ease of calculation, and does not mean that the spinel structure of this application is restricted.

[0053] The volume fraction content of the second region is p ≤ 50%, selectively 10% ≤ p ≤ 30%, and exemplary p may be 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, or 30%. The relatively small volume fraction of the second region indicates that the second region is mainly located in the outer layer of the spinel structure.

[0054] Based on the total mass of A in the spinel-type lithium manganese-containing composite oxide, the percentage of element A located in the second region is m. Based on the total mass of M in the spinel-type lithium manganese-containing composite oxide, the percentage of element M located in the second region is n, where m+n≧70%, selectively 80%≦m+n≦95%, and exemplary, m+n may be 70%, 75%, 80%, 85%, 88%, 90%, 92%, or 95%. In this specification, the percentage of element A located in the second region refers to the ratio of the mass of element A located in the second region to the total mass of element A in the spinel-type lithium manganese-containing composite oxide. The percentage of element M located in the second region refers to the ratio of the mass of element M located in the second region to the total mass of element M in the spinel-type lithium manganese-containing composite oxide.

[0055] Element A and Element M are concentrated in the second region, and the synergistic effect of Element A and Element M provides sufficient protection to the surface layer of the spinel-type lithium manganese composite oxide, enhancing the structural stability of the surface layer, improving the overall structural stability of the positive electrode active material, contributing to the capacity reallocation of the positive electrode active material, and further improving the cycle performance and cycle life of secondary batteries employing this positive electrode active material.

[0056] In some embodiments, the molecular formula is -0.1 ≤ x ≤ 0.3, and exemplarily, x may be -0.1, 0, 0.1, 0.15, 0.2, or 0.3. When x is within this range, it is possible to ensure sufficient Li to guarantee capacity, improve the kinetic performance and structural stability of the material, and maintain a good spinel structure.

[0057] In some embodiments, the molecular formula is 0 ≤ t ≤ 0.2, and exemplary, t may be 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.15, 0.18, or 0.2. When t satisfies the above range, oxygen vacancies in the structure of the positive electrode active material can be reduced, and the risk of side reactions on the surface of the positive electrode active material can be reduced.

[0058] In some examples, the molecular formulas are -0.1 ≤ x ≤ 0.3 and 0 ≤ t ≤ 0.2. The performance of the spinel-type lithium manganese-containing composite oxide is adjusted by simultaneously controlling the proportions of lithium and oxygen elements.

[0059] In some examples, the molecular formula is such that 0.001 ≤ a ≤ 0.1, and exemplary, a may be 0.001, 0.002, 0.005, 0.008, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, or 0.1. When the content of element A satisfies the above range, the improvement effect of substituting the manganese moiety with element A is good.

[0060] In some examples, the molecular formula is such that 0.001 ≤ b ≤ 0.1, and exemplary, b may be 0.001, 0.002, 0.005, 0.008, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, or 0.1. When the content of element M satisfies the above range, the polyoxyanion formed by M and oxygen can sufficiently absorb the hydrofluoric acid HF produced in the electrolyte and generate a fluorinated anion that is highly stable in the electrolyte.

[0061] In some examples, the molecular formulas are 0.001 ≤ a ≤ 0.1 and 0.001 ≤ b ≤ 0.1. When elements A and M simultaneously satisfy the above ranges, the synergistic effect of elements A and M can be fully exerted, improving the structural stability of the positive electrode active material, contributing to the capacity expression of the positive electrode active material, and improving the high-temperature cycle storage performance and cycle service life of the positive electrode active material.

[0062] In some embodiments, the molecular formula is 0.005 ≤ a + b ≤ 0.1, and exemplary, a + b may be 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, or 0.1. When element A and element M satisfy the above range simultaneously, the synergistic effect of element A and element M can be fully exerted, improving the structural stability of the positive electrode active material, contributing to the capacity expression of the positive electrode active material, and improving the high-temperature cycle storage performance and cycle service life of the positive electrode active material.

[0063] In several examples, the specific surface area of ​​the spinel-type lithium manganese-containing composite oxide was 0.01 m². 2 / g~1.5m 2 It is / g, and selectively 0.1m 2 / g~1m 2 The specific surface area is 0.01 m² / g, and as an example, the specific surface area of ​​a spinel-type lithium manganese-containing composite oxide is 0.01 m². 2 / g, 0.05m 2 / g, 0.1m 2 / g, 0.12m 2 / g, 0.15m 2 / g, 0.2m 2 / g, 0.3m 2 / g, 0.4m 2 / g, 0.5m 2 / g, 0.6m 2 / g, 0.7m 2 / g, 0.8m 2 / g, 0.9m 2 / g, 1.0m 2 / g, 1.2m 2 / g, 1.4m 2 / g or 1.5m 2 / g is also acceptable.

[0064] The spinel-type lithium manganese-containing composite oxide has a relatively small specific surface area, which reduces the risk of side reactions occurring on the surface and can contribute to the long-term cycle stability of secondary batteries manufactured using this spinel-type nickel-manganese-lithium-containing composite oxide as the positive electrode active material. Furthermore, the relatively small specific surface area further contributes to uniform and comprehensive surface modification of the spinel material particles, thereby enhancing the overall structural stability of the spinel structure.

[0065] In several examples, the average particle size D of the spinel-type lithium manganese-containing composite oxide V50 The size ranges from 1 μm to 20 μm, selectively from 2 μm to 15 μm, and exemplarily, D V50 The particle size may be 1 μm, 1.5 μm, 2 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, or 20 μm.

[0066] The average particle size D of the spinel-type lithium manganese-containing composite oxide in the embodiment of the present application V50 When the above range is present, the crystal structure is relatively perfect, the surface of the crystal grains is stable and has a small specific surface area, and it is easy to dope the second region of the spinel-type lithium manganese-containing composite oxide during the manufacturing process, and at the same time, it has excellent processing performance when used afterward. During the doping process, elements such as Li and O in the spinel-type lithium manganese-containing composite oxide Reduce consumption Difficult, This can improve the overall performance of materials and batteries. .

[0067] In several examples, a and b in the molecular formula and the average particle size D of the spinel-type lithium manganese-containing composite oxide V50 During this period, 0.01 ≤ (a+b) × D V50 The expression satisfies ≤ 1, and as an example, (a+b)×D V50This may be 0.01, 0.02, 0.03, 0.05, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.

[0068] Content of elements A and M and average particle size D V50 As the performance of the spinel LMO active material changes, the changes exhibit similar behavioral rules, and the three elements work synergistically to further improve the performance of the positive electrode active material. For example, when the content of elements A and M is low, the improvement effect on the positive electrode active material is not strong, and at the same time D V50 If the amount is small, the improvement effect will be even weaker. If the content of elements A and M is high, it may degrade the performance of some of the positive electrode active materials, and at the same time D V50 If the amount is also large, the performance of that part of the positive electrode active material may further deteriorate. Therefore, in the embodiments of this application, the doping amounts of element A and element M and the average particle size D of the spinel-type lithium manganese-containing composite oxide are considered. V50 By simultaneously controlling these factors, it is possible to achieve both structural stability and dynamic performance in spinel-type lithium manganese-containing composite oxides.

[0069] In some embodiments, the spinel-type lithium manganese-containing composite oxide has the form of single crystal particles or pseudo-single crystal particles.

[0070] The positive electrode active material having the above configuration has few grain boundaries within the particles, resulting in a low probability of particle fracture during subsequent processing and use of the secondary battery, thus maintaining a stable structure and contributing to improved long-term stability of the secondary battery. Furthermore, the single crystal or pseudo-single crystal particles have high dispersibility, making it easy to achieve uniform and comprehensive surface modification. Polycrystalline particles have a large number of grain boundaries within them, making them prone to fracture at the grain boundaries during subsequent processing and use. After fracture, a new surface is exposed that has not been modified and lacks the electrolyte interface CEI film, further degrading battery performance.

[0071] In some embodiments, the spinel-type lithium manganese-containing composite oxide has at least one of the following particle shapes: octahedral particle shape, truncated octahedral particle shape, and polyhedral particle shape with beveled octahedra.

[0072] The crystal planes on the surface of crystal particles having the above-described morphology are more stable, and the surface area is smaller, which contributes to mitigating surface side reactions, thereby improving the structural stability of the positive electrode active material.

[0073] [Method for manufacturing positive electrode active material] The method for producing a positive electrode active material provided herein may include the following steps:

[0074] The lithium source, manganese source, A source, M source, and X source are weighed in stoichiometric ratios corresponding to the target component, and then uniformly mixed to obtain a raw material mixture powder. The lithium source, manganese source, A source, M source, and X source may each be different, or they may be a mixture of multiple sources. Examples include lithium hydroxide, lithium carbonate, lithium nitrate, lithium oxalate, manganese oxide, nickel oxide, nickel manganese hydroxide, and oxides, hydroxides, and carbonates of at least one of A, M, and X.

[0075] The above mixed powder was heated to 800-1100°C in an oxygen-containing atmosphere and kept warm for 2-50 hours to produce the cathode active material.

[0076] In some embodiments, in order to lower the t-value, if the sintering temperature is >900°C or higher, the material may be kept warm at 550°C to 850°C for 5 to 30 hours. Specifically, after high-temperature sintering, the material may be cooled to the temperature range and kept warm, or after high-temperature sintering, the material may be cooled to room temperature, other processes such as ball milling may be performed, and then the temperature may be raised to the temperature range and kept warm.

[0077] [Secondary battery] This application further provides a secondary battery comprising a positive electrode active material according to any one of the above embodiments, wherein the secondary battery has good long-term stability at high temperature and high voltage, and in particular high-temperature full-charge storage performance. The secondary battery may be a lithium-ion secondary battery, a sodium-ion secondary battery, a lithium-sodium secondary battery, or the like.

[0078] A secondary battery may include a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. During the charging process of a secondary battery, active ions repeatedly insert and remove between the positive and negative electrode sheets. The electrolyte plays a role in conducting ions between the positive and negative electrode sheets. The separator is placed between the positive and negative electrode sheets and primarily serves to prevent short circuits between the positive and negative electrodes while simultaneously allowing ions to pass through.

[0079] [Positive electrode sheet] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector and containing a positive electrode active material. For example, the positive electrode current collector has two opposing surfaces in its thickness direction, and the positive electrode film layer is provided on one or both of the two opposing surfaces of the positive electrode current collector.

[0080] The positive electrode current collector can be made of a material that has good conductivity and mechanical strength. In some embodiments, aluminum foil can be used as the positive electrode current collector.

[0081] In the secondary battery provided by this application, the positive electrode active material in the positive electrode sheet is provided by this application, and the molecular formula is Li 1+x A a M b X c Mn 2-a-b-c-x O 4-tThis material contains a spinel-type nickel-manganese-lithium composite oxide. This spinel-structured nickel-manganese-lithium composite oxide material has good structural stability, especially surface structural stability. When used as the active material for the positive electrode sheet of a secondary battery, it can significantly enhance the battery system performance at high temperatures and high voltages, such as reducing swelling. It also exhibits slow capacity decay, achieves long-term stability at high temperatures and high voltages, especially high-temperature full-charge storage performance, and clearly extends the service life and safety performance of the secondary battery.

[0082] In some embodiments, the positive electrode active material is a Li-based material whose molecular formula is provided in this application. 1+x A a M b X c Mn 2-a-b-c-x O 4-t In addition to spinel-type nickel-manganese-lithium-containing composite oxides, other cathode active materials for batteries known in the art may be included. For example, other cathode active materials may include at least one of materials such as olivine-structured lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials used as cathode active materials for batteries may be used. Examples of lithium transition metal oxides include lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel-cobalt oxide, lithium manganese-cobalt oxide, lithium nickel-manganese oxide, and lithium nickel-cobalt-manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM 333 (It may also be abbreviated as LiNi) 0.5 Co 0.2 Mn 0.3 O2(NCM 523 (It may also be abbreviated as LiNi) 0.5 Co 0.25 Mn 0.25 O2(NCM 211 (It may also be abbreviated as LiNi) 0.6 Co0.2 Mn 0.2 O2 (which may be abbreviated as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (which may be abbreviated as NCM 811 ), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.80 Co 0.15 Al 0.05 O2) and at least one of its modified compounds, etc., can be included, but not limited thereto. Examples of olivine-structured lithium-containing phosphates include lithium iron phosphate (e.g., LiFePO4 (which may be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and at least one of a composite material of lithium manganese iron phosphate and carbon, but not limited thereto.

[0083] In some embodiments, the positive electrode film layer further selectively contains a binder. The type of the binder is not specifically limited, and those skilled in the art can select it according to actual needs. As an example, the binder used in the positive electrode film layer can include one or more of polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE).

[0084] In some embodiments, the positive electrode film layer further selectively contains a conductive agent. The type of the conductive agent is not specifically limited, and those skilled in the art can select it according to actual needs. As an example, the conductive agent used in the positive electrode film layer can include one or more of graphite, superconducting carbon, acetylene black, carbon black, ketjen black, carbon dot, carbon nanotube, graphene, and carbon nanofiber.

[0085] In some embodiments, the step of manufacturing a positive electrode sheet using a positive electrode active material may include: dispersing the positive electrode active material, a binder, and a selective conductive agent in a solvent which may be N-methylpyrrolidone, and uniformly stirring them with a vacuum stirrer to obtain a positive electrode slurry; and uniformly coating the positive electrode slurry onto the aluminum foil of a positive electrode current collector, drying it at room temperature, then transferring it to an oven for drying, followed by cold pressing and slitting to obtain a positive electrode sheet.

[0086] [Negative electrode sheet] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector. For example, the negative electrode current collector has two opposing surfaces in its thickness direction, and the negative electrode film layer is provided on one or both of the two opposing surfaces of the negative electrode current collector.

[0087] The negative electrode current collector can be made of a material with good conductivity and mechanical strength, and it performs the roles of conductivity and current collection. In some embodiments, copper foil can be used as the negative electrode current collector.

[0088] The negative electrode film layer contains a negative electrode active material, and the steps of manufacturing a negative electrode sheet using the negative electrode active material may include dispersing the negative electrode active material, a binder, and a selective thickener and conductive agent in a solvent that may be deionized water to form a uniform negative electrode slurry, and applying the negative electrode slurry to a negative electrode current collector, and obtaining a negative electrode sheet after processes such as baking and cold pressing.

[0089] In some embodiments, the present application does not specifically limit the type of negative electrode active material, and the negative electrode sheet includes negative electrode active materials used selectively as the negative electrode of a secondary battery. The negative electrode active material may be one or more of the following: graphite materials (e.g., artificial graphite, natural graphite), mesocarbon microbeads (abbreviated as MCMB), hard carbon, soft carbon, silicon-based materials, and tin-based materials.

[0090] In some examples, the binder can be selected from one or more of the following: polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), styrene-butadiene rubber (SBR), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0091] In some examples, the thickener may be sodium carboxymethylcellulose (CMC-Na).

[0092] In some embodiments, the conductive agent used in the negative electrode sheet can be selected from one or more of the following: graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0093] [Electrolytes] The electrolyte plays a role in conducting ions between the positive and negative electrodes. In this application, the type of electrolyte is not specifically limited and can be selected according to the needs. For example, the electrolyte may be a liquid, a gel, or an all-solid.

[0094] In some embodiments, an electrolyte solution is used as the electrolyte. The electrolyte solution contains an electrolyte salt and a solvent.

[0095] In some examples, the electrolyte salt can be selected from one or more of the following: LiPF6 (lithium hexafluoride phosphate), LiBF4 (lithium tetraborate tetrafluoride), LiClO4 (lithium perchlorate), LiAsF6 (lithium hexafluoride arsenate), LiFSI (lithium bis(fluorosulfonyl)imide), LiTFSI (lithium bis(trifluoromethanesulfonyl)imide), LiTFS (lithium trifluoromethanesulfonate), LiDFOB (lithium difluorooxalatoborate), LiBOB (lithium bisoxalatoborate), LiPO2F2 (lithium difluorophosphate), LiDFOP (lithium difluorodioxalatophosphate), and LiTFOP (lithium tetrafluorooxalatophosphate).

[0096] In some examples, the solvent can be selected from one or more of the following: ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0097] In some embodiments, the electrolyte further selectively contains additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives capable of improving certain battery performance, such as additives that improve the overcharge performance of the battery, additives that improve the high-temperature performance of the battery, and additives that improve the low-temperature performance of the battery.

[0098] [Separator] In some embodiments, the secondary battery further includes a separator. The present application does not particularly limit the type of separator, and any known porous separator having good chemical and mechanical stability can be selected.

[0099] In some embodiments, the material of the separator can be selected from at least one of 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. If the separator is a multilayer composite film, the materials of each layer may be the same or different, and are not particularly limited.

[0100] In some embodiments, the positive electrode sheet, negative electrode sheet, and separator can be manufactured as an electrode assembly by a winding process or a lamination process.

[0101] [Exterior] In some embodiments, the secondary battery may include an outer casing. This casing can be used to enclose the electrode assembly and electrolyte.

[0102] In some embodiments, the casing of the secondary battery may be a rigid case, such as a hard plastic case, an aluminum case, or a steel case. The casing of the secondary battery may also be a soft pack, such as a bag-type soft pack. The material of the soft pack may be plastic, and examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0103] In this application, the shape of the secondary battery is not particularly limited and may be cylindrical, rectangular, or any other shape. For example, Figures 1 and 2 show a secondary battery 1 having a rectangular structure as an example.

[0104] In some embodiments, the secondary battery 1 includes an outer casing 11. The outer casing 11 includes a top cover assembly 111 and a housing 112. An electrode assembly 12, composed of a positive electrode sheet, a negative electrode sheet, and a separator, is housed within the housing 112, and an electrolyte is further housed within the housing 112. The positive electrode sheet or the negative electrode sheet includes a tab. During the charging and discharging process of the secondary battery 1, active ions repeatedly insert and withdraw between the positive electrode sheet and the negative electrode sheet. The electrolyte plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is provided between the positive electrode sheet and the negative electrode sheet and mainly serves to prevent short circuits between the positive and negative electrodes, while simultaneously allowing active ions to pass through. Specifically, the secondary battery 1 may be a roll-type or stack-type battery such as a lithium-ion battery or a sodium-ion battery, but is not limited thereto.

[0105] Selectively, the housing 112 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates enclosing each other to form a housing chamber. The housing 112 has an opening communicating with the housing chamber, and the top cover assembly 111 may cover the opening to seal the housing chamber. The positive electrode sheet, negative electrode sheet and separator can form an electrode assembly 12 by a winding or lamination process. The electrode assembly 12 is sealed within the housing chamber. The electrolyte permeates the electrode assembly 12. The number of electrode assemblies 12 contained in the lithium-ion battery 1 may be one or more, and a person skilled in the art can select them according to specific practical requirements.

[0106] In some embodiments, the secondary battery 1 can be assembled into a battery. The battery may be a battery module or a battery pack. For example, the number of secondary batteries 1 included in a battery module may be one or more, and the specific number can be selected by those skilled in the art depending on the application and capacity of the battery module.

[0107] Figure 3 shows an example of a battery module 10. Referring to Figure 3, in the battery module 10, a plurality of secondary batteries 1 may be arranged sequentially along the longitudinal direction of the battery module 10. Of course, they may be arranged in any other arbitrary form. Furthermore, the plurality of secondary batteries 1 may be fixed by fastening members. Optionally, the battery module 10 may further include a housing having a housing space, and the plurality of secondary batteries 1 are housed in this housing space.

[0108] In some embodiments, the battery module 10 can be further assembled into a battery pack, and the number of battery modules 10 included in the battery pack may be one or more, and the specific number can be selected by those skilled in the art depending on the application and capacity of the battery pack. Of course, the battery pack may also be directly composed of multiple secondary batteries 1.

[0109] Figures 4 and 5 show an example of a battery pack 20. Referring to Figures 4 and 5, the battery pack 20 may include a battery box and a plurality of battery modules 10 provided in the battery box. The battery box includes an upper box 21 and a lower box 22, the upper box 21 covering the lower box 22 and forming a sealed space for housing the battery modules 10. The plurality of battery modules 10 can be arranged in the battery box in any manner.

[0110] Furthermore, the present application further provides a power consumption device comprising at least one of the secondary battery, battery module, or battery pack provided herein. 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, notebook computers, etc.), electric vehicles (e.g., secondary battery electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric vehicles, ships and satellites, and energy storage systems. As a power consumption device, a secondary battery, battery module, or battery pack can be selected according to the needs of its use.

[0111] Figure 6 shows an example of a power consumption device 30. This power consumption device 30 is a secondary battery electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power output and high energy density requirements for the secondary battery of this power consumption device 30, a battery pack or battery module can be used.

[0112] Other examples of such devices may include mobile phones, tablet computers, and notebook computers. These devices typically require lightweight and thin designs and can utilize rechargeable batteries as their power source.

[0113] Examples Examples of the present application are described below. The examples described below are illustrative and are for interpretation purposes only, and should not be understood as limiting the present application. Unless otherwise specified in the examples, specific techniques or conditions are described in the art literature or in accordance with product specifications. Unless otherwise specified, the reagents or equipment used are all commercially available, common products.

[0114] Example 1 1. Manufacturing of positive electrode sheets 1.1 Manufacturing of positive electrode active material The doping elements in the positive electrode active material are as shown in Tables 1 to 4.

[0115] According to the components in Tables 1 to 4, lithium carbonate, manganese tetroxide, source A, source M, and source X were weighed in the corresponding stoichiometric ratios, then uniformly mixed to obtain a raw material mixture powder. This mixture powder was then heated to 900°C in an air atmosphere and maintained at that temperature for 20 hours to produce the positive electrode active material.

[0116] 1.2 Manufacturing of positive electrode sheets An 8μm thick aluminum foil was used as the positive electrode current collector.

[0117] The manufactured positive electrode active material, conductive carbon black, and polyvinylidene fluoride (PVDF) binder were thoroughly mixed in an appropriate amount of N-methylpyrrolidone (NMP) solvent in a weight ratio of 95:2:3 to form a uniform positive electrode slurry. This slurry was then applied to the surface of the positive electrode current collector, and after processes such as baking, a positive electrode sheet was obtained.

[0118] 2. Manufacturing of negative electrode sheets The negative electrode active material, graphite, conductive carbon black, the thickener, sodium carboxymethylcellulose (CMC), and the binder, styrene-butadiene rubber emulsion (SBR), were thoroughly mixed in an appropriate amount of deionized water in a weight ratio of 96:1:1:2 to form a uniform negative electrode slurry. This slurry was then applied to a negative electrode current collector, and after processes such as baking, a negative electrode sheet was obtained.

[0119] 3. Manufacturing of electrolyte Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a 1:1:1 volume ratio to obtain an organic solvent. Subsequently, a thoroughly dried lithium salt LiPF6 was dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0120] 4. Manufacturing of lithium-ion batteries A positive electrode sheet, a separator (PP / PE / PP composite thin film), and a negative electrode sheet were sequentially laminated and assembled, then wound into a cell and packed into a packaging case. The electrolyte was injected into the cell, and then a lithium-ion battery was obtained through processes such as sealing, standing, hot pressing / cold pressing, and chemical formation.

[0121] Examples 2 to 5 The type of doping element A is the same as in Example 1, but the mass content of A is different.

[0122] Examples 6 to 11 The difference from Example 1 is that the type of doping element A is different.

[0123] Examples 12 to 15 The type of doping element M is the same as in Example 1, but the mass content of M is different.

[0124] Example 16 The types of doping elements A and M are the same as in Example 1, but the mass content of A and M is different.

[0125] Examples 17-21 The difference from Example 12 lies in the type of M source used for doping.

[0126] Examples 22 to 31 The difference from Example 12 is that Example 30 is doped with element X, and the type of doping element M is different from that of Example 30.

[0127] Examples 32 to 41 The difference from Example 12 lies in the degree of concentration of the doped A and M elements in the second region.

[0128] Examples 42 to 58 The difference from Example 12 is that at least one of the doped elements A and M is adjusted to be different, and / or the sintering process is adjusted to be different to be different to at least one of the particle size, specific surface area and particle shape.

[0129] Comparative Example 1 The difference from Example 12 is that element A was doped, but element M was not.

[0130] Comparative Example 2 The difference from Example 12 is that element A was not doped, while element M was doped.

[0131] Comparative Example 3 The difference from Example 12 is that while element A was not doped and element M was not doped, element X was doped.

[0132] Comparative Example 4 The difference from Example 12 is that element A is not doped, element M is not doped, and element X is not doped.

[0133] Examples 1-3 1 Elemental content of the positive electrode active material produced in Comparative Examples 1-4 [Table 1] [Table 2]

[0134] In Tables 1 and 2, element A originates from an oxide containing element A (source A). For example, if element A is Nb, source A may be Nb2O5. Element M originates from an oxide containing element M (source M). For example, if element M is B, source M may be B2O3. Element X originates from an oxide containing element X (source X). For example, if element X is Mg, source X may be MgO.

[0135] Examples 12, 3 2 ~4 1 Elemental distribution of positive electrode active material manufactured by [Table 3]

[0136] In Table 3, element A originates from an oxide containing element A (source A). For example, if element A is Nb, source A may be Nb2O5. Element M originates from an oxide containing element M (source M). For example, if element M is B, source M may be B2O3.

[0137] Examples 12, 4 2 ~5 8 Physicochemical indicators of positive electrode active material manufactured by [Table 4]

[0138] In Table 4, element A originates from an oxide containing element A (source A). For example, if element A is Nb, source A may be Nb2O5. Element M originates from an oxide containing element M (source M). For example, if element M is B, source M may be B2O3.

[0139] Performance testing: 1. Initial discharge Gram capacity test of spinel LMO in secondary batteries The rechargeable batteries that were manufactured were used as the test subjects.

[0140] At 25°C, the upper cutoff voltage V is 0.3C for the secondary battery. max (V of regular spinel LMO and spinel LMO with small amounts of doping) max After constant current charging up to 4.3V, V max The battery was then charged at a constant voltage until the current reached 0.05C, left to stand for 5 minutes, and then the secondary battery was charged to 0.33C with a lower cutoff voltage V min (V of regular spinel LMO and spinel LMO with small amounts of doping)min By discharging at a constant current down to 2.5V and dividing the discharge capacity by the mass of the positive electrode active material, spinel LMO, the initial discharge gram capacity C0 (mAh / g) of spinel LMO in the secondary battery is obtained.

[0141] The initial discharge gram capacity is the most fundamental performance parameter of a positive electrode active material. If the gram capacity C0 of spinel LMO is less than the standard value of 100 mAh / g, its practical value is limited.

[0142] 2. Testing the high-temperature full-charge storage performance of secondary batteries. The rechargeable batteries that were manufactured were used as the test subjects.

[0143] At 25°C, the secondary battery was charged with a constant current of 0.3C until the voltage reached Vmax, and then charged with a constant voltage until the current reached 0.05C at Vmax. After that, the secondary battery was left at 45°C, fully discharged every month, and then fully charged and fully discharged once at 25°C to determine the discharge capacity value. C n After extraction, it was fully charged again and stored in a 45°C environment. Discharge capacity C n is the initial value C Until it decays to 80% of 0 、 Storage has ended. The total time the device was stored at 45°C after full charge is the high-temperature full-charge storage time ts (months, m).

[0144] 3. Testing of the high-temperature cycle performance of secondary batteries The rechargeable batteries that were manufactured were used as the test subjects.

[0145] At 45°C, the secondary battery was charged with a constant current of 0.3C until the voltage reached Vmax, then charged with a constant voltage until the current reached 0.05C at Vmax, allowed to stand for 5 minutes, and then discharged with a constant current of 0.33C until the voltage reached Vmin. This constitutes one charging cycle, and the discharge capacity recorded here is the discharge capacity of the first cycle. After performing the cycle charging test on all batteries according to the above method, the remaining reversible discharge capacity was recorded, and the total number of cycles tc (×10 cycles, 10cls) was recorded until the reversible discharge capacity decayed to 80% of the initial value.

[0146] This application defines the overall coefficient E for evaluating the electrical performance of a secondary battery as satisfying the formula E = (C0 / 100) × (ts / 36 + tc / 100), after comprehensively considering the capacity, storage, and cycle performance of the secondary battery.

[0147] Let's take the example of a vehicle as the power-consuming device. The on-board performance of a secondary battery is expressed in terms of vehicle durability and total mileage. Durability can be evaluated by the initial capacity, total mileage is the product of durability per unit life and total life, and total life can be evaluated by the sum of cycle life and storage life. In the above formulas, the numbers represent the overall performance and usable criteria of the spinel LMO, respectively. In (C0 / 100), 100 represents an initial capacity of 100 mAh / g, 36 represents a high-temperature full-charge storage life of 3 years, and in tc / 100, 100 represents a high-temperature cycle of 1000 cls. Clearly, the applicable standard performance index is E=2.

[0148] 4. Testing of elemental content in positive electrode active material The content of each element in the cathode active material was measured by referring to EPA 6010D-2014 inductively coupled plasma atomic emission spectroscopy.

[0149] 5. Average particle size Dv of the positive electrode active material 50 (Volume median particle size Dv 50 ) test Referencing GB / T 19077-2016 Particle Size Analysis Laser Diffraction Method, the volume median particle size D of the positive electrode active material was determined using a Mastersizer 3000 laser particle size analyzer. v50 Measure the volume median particle size D v 50 This represents the particle size corresponding to the point when the cumulative volume distribution percentage of the material reaches 50%.

[0150] 6. Specific surface area test of positive electrode active material The specific surface area of ​​the positive electrode active material powder was measured by referring to the GB / T 19587-2004 method for measuring the specific surface area of ​​solid materials using the gas adsorption BET method.

[0151] 7. Scanning electron microscopy examination of positive electrode active material Referring to JY / T010-1996, the morphology of the positive electrode active material powder was observed using a field emission scanning electron microscope (Zeiss Sigma300). Based on the observations in the scanning electron microscope images, a single crystal particle is defined as a single-crystal particle if it contains only one crystal particle, or if one crystal particle occupies more than half of the volume of the powder particle. A pseudo-single-crystal particle is defined as a powder particle containing 10 or fewer crystal particles of similar size. A polycrystalline particle is defined as a powder particle containing more than 10 crystal particles.

[0152] Performance test results Examples 1-3 1 Performance of batteries manufactured in Comparative Examples 1-4 [Table 5]

[0153] Compared to Comparative Example 4, doping was performed on the positive electrode active material in Comparative Examples 1 to 3, which improved the structural stability of the positive electrode active material to some extent, and improved the high-temperature storage performance and cycle performance of the secondary battery to some extent. However, E < 2 was clearly present, and there is still a considerable gap from the performance required for application.

[0154] Compared to Comparative Examples 1 to 3, in Examples 1 to 31, by elemental doping of the manganese portion of the positive electrode active material and doping with an element capable of forming a polyoxyanion with oxygen, the structural stability and thermal stability of the positive electrode active material itself can be significantly improved, and furthermore, the storage performance and cycle performance of the secondary battery can be significantly improved.

[0155] Compared to Example 2, Examples 6 to 11 employ different A elements such as Ru and Ta for doping, and in all cases, the storage performance and cycle performance of the secondary battery at high temperatures can be improved.

[0156] Compared to Example 12, Examples 16 to 20 employ different M elements such as C, P, Si, and S for doping, and in all cases, they form polyoxyanions with oxygen elements, improving the structural stability of the secondary battery and further enhancing its performance.

[0157] Compared to Example 12, Examples 21 to 31 further doping with element X reduces the risk of Jahn-Teller strain occurring in the spinel structure and improves the structural stability and capacitance characteristics of the positive electrode active material.

[0158] As can be seen from Examples 1 to 5, the performance of the secondary battery is affected to some extent by the change in the doping content of element A, and the performance of the secondary battery is relatively good when 0.001 ≤ a ≤ 0.1. In particular, the storage performance at high temperatures and the cycle performance of the secondary battery are even better when 0.005 ≤ a + b ≤ 0.1.

[0159] As can be seen from Examples 12 to 16, the performance of the secondary battery is affected to some extent by the change in the doping content of element M, and the performance of the secondary battery is relatively good when 0.001 ≤ b ≤ 0.1.

[0160] Examples 12, 3 2 ~4 1 Performance of batteries manufactured in [Table 6]

[0161] As can be seen from Examples 12 and 32 to 41 in Table 6, while keeping m+n constant, p is within a predetermined range, and as the volume fraction content p in the second region decreases, more A and M elements can be concentrated on the surface of the positive electrode active material, further improving the surface performance of the positive electrode active material and enhancing the structural stability of the surface of the positive electrode active material. Figure 7 shows schematic diagrams of the distribution of the first region 121 and the second region 122 of the positive electrode active material.

[0162] As can be seen from Examples 36 to 41, a higher m+n content means that elements A and M are more concentrated on the surface of the positive electrode active material, which can further improve the structural stability of the surface of the positive electrode active material.

[0163] Performance of batteries manufactured in Example 12, 42-58 [Table 7]

[0164] As can be seen from Table 7, the performance of a secondary battery can be effectively adjusted by controlling the particle size, specific surface area BET, and crystal grain structure of the positive electrode active material. In particular, 0.01 ≤ (a + b) × D V50 When the value is ≤1, it is possible to effectively balance the changes in electrical performance due to doping and changes in each physicochemical parameter, avoid problems that cannot be reconciled, and maximize the overall performance of the positive electrode active material. In particular, in Examples 56 to 58, excellent high capacity and long life were achieved by doping with multiple elements and controlling the physicochemical parameters. Figure 8 shows Example 5 1 A diagram of the morphology of the positive electrode active material is shown.

[0165] While the present application has been described with reference to preferred embodiments, various improvements can be made thereto without departing from the scope of the application, and components therein can be replaced with equivalents. In particular, all technical features mentioned in each embodiment can be combined in any way, provided that there are no structural conflicts. The present application is not limited to the specific embodiments disclosed in the specification, but includes all technical solutions within the scope of the claims. [Explanation of Symbols]

[0166] 1 Secondary battery 11 Exterior 111 Top lid assembly 112 Housing 12 Electrode assembly 121 First Domain 122 Second Domain 10 Battery Modules 20 battery packs 21 Top box 22 Lower box 30 Power consumption equipment

Claims

1. The molecular formula is Li １＋ｘ A ａ M ｂ X ｃ Mn ２－ａ－ｂ－ｃ－ｘ O ４－ｔ It contains a spinel-type lithium manganese-containing composite oxide, and in the above molecular formula, A is a manganese moiety doping element of a spinel-type lithium manganese-containing composite oxide, and A comprises one or more of V, Nb, Ta, Mo, W, Ru, Rh, Sn, Sb, Te, Tl, Pd, Bi, and Po. M is used to form a polyoxyanion with O, and M comprises one or more of B, C, N, Si, P, S, and Cl. X includes one or more of Mg, Al, Ca, Sc, Ti, Cr, Fe, Co, Ni, Cu, Zn, and Zr. -0.1 ≤ x ≤ 0.3, 0 < a ≤ 0.2, 0 < b ≤ 0.2, 0 ≤ c ≤ 0.7, 0 ≤ t ≤ 0.2, a and b in the above molecular formula, and the average particle size D of the spinel-type lithium manganese-containing composite oxide. Ｖ５０ The interval between these two is 0.01 ≤ (a + b) × D Ｖ５０ The condition satisfies ≤ 1, and the unit of D V50 is μm. The spinel-type lithium manganese-containing composite oxide includes a first region and a second region that are sequentially distributed along the direction from the center to the outer surface. Based on the volume of the spinel-type lithium manganese-containing composite oxide, the volume fraction content of the second region is p ≤ 30%. Based on the total mass of element A in the spinel-type lithium manganese-containing composite oxide, the percentage of element A located in the second region is m. A positive electrode active material in which, based on the total mass of M in the spinel-type lithium manganese-containing composite oxide, the percentage of element M located in the second region is n, and m + n ≥ 70%.

2. The positive electrode active material according to claim 1, wherein A comprises one or more of Nb, Ta, Mo, W, and Ru.

3. The positive electrode active material according to claim 1 or 2, wherein M comprises one or more of Si, S, and Cl.

4. The positive electrode active material according to claim 1 or 2, wherein X comprises one or more of Al, Sc, Cr, Ni, Cu, Zn, and Ti.

5. In the above molecular formula, 0.001 ≤ a ≤ 0.1 and / or 0.001 ≤ b ≤ 0.1, The positive electrode active material according to claim 1 or 2.

6. The specific surface area of the spinel-type lithium manganese-containing composite oxide is 0.01 m ２ / g to 1.5 m ２ / g. The positive electrode active material according to claim 1 or 2.

7. The average particle size D of the spinel-type lithium manganese-containing composite oxide Ｖ５０ The positive electrode active material according to claim 1 or 2, wherein the particle size is 1 μm to 20 μm.

8. The positive electrode active material according to claim 1 or 2, wherein the spinel-type lithium manganese-containing composite oxide has the form of single crystal particles or pseudo-single crystal particles.

9. The positive electrode active material according to claim 1 or 2, wherein the spinel-type lithium manganese-containing composite oxide has at least one of the following shapes: octahedral particle shape, truncated octahedral particle shape, and polyhedral particle shape in which the octahedrons are beveled.

10. A secondary battery (1) comprising the positive electrode active material according to claim 1.

11. A battery module (10) comprising the secondary battery (1) described in claim 10.

12. A battery pack (20) including the battery module (10) according to claim 11.

13. A power consumption device (30) comprising a secondary battery (1) according to claim 10, a battery module (10) according to claim 11, or a battery pack (20) according to claim 12.

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