Positive electrode material, positive electrode plate, battery monomer, battery and electric device

Abstract

The embodiment of the invention provides a positive electrode material, a positive electrode plate, a battery monomer, a battery and an electric device, and belongs to the technical field of batteries. The positive electrode material comprises a layered lithium-containing metal oxide, the general formula of the layered lithium-containing metal oxide is LiaLxNibCocMndM (1-b-c-d) OeNf, L ions are cations with the radius larger than that of Li ions, M comprises at least one of Mg, Zr, Al, B, Ta, Mo, W, Nb, Sb and La, N comprises at least one of F, S and P, 0 < a < 2, 0 < = b < 1, 0 < = c < 1, 0 < = d < 1, 0 < b + c + d < = 1, 0 < e < = 2, 0 < = f < 2, and 0 < x < = 0.8, the technical scheme of the embodiment of the invention is beneficial to improving the performance of the positive electrode material and the performance of the battery monomer.

Description

Positive electrode materials, positive electrode sheets, battery cells, batteries and electrical devices Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a positive electrode material, a positive electrode sheet, a battery cell, a battery, and an electrical device. Background Art

[0002] With the increasing severity of environmental pollution, the new energy industry has attracted more and more attention. In the new energy industry, battery technology is an important factor in its development.

[0003] As a material for preparing the positive electrode sheets of battery cells, the performance of positive electrode materials is crucial to the performance of battery cells. Therefore, how to provide a positive electrode material to improve the performance of battery cells is a technical problem that needs to be solved urgently.

[0004] Summary of the Invention

[0005] The present application is made in view of the above-mentioned problems, and its purpose is to provide a positive electrode material to improve the performance of battery cells.

[0006] In order to achieve the above-mentioned objectives, the present application provides a positive electrode material, a positive electrode plate, a battery cell, a battery and an electrical device.

[0007] In a first aspect, a positive electrode material is provided, wherein the positive electrode material comprises a layered lithium-containing metal oxide, wherein the general formula of the layered lithium-containing metal oxide is Li a L x Ni b Co c Mn d M (1-b-c-d) O e N f , wherein L ion is a cation having a radius larger than that of Li ion, M includes at least one of Mg, Zr, Al, B, Ta, Mo, W, Nb, Sb, and La, and N includes at least one of F, S, and P, 0 <a<2,0≤b<1,0≤c<1,0≤d<1,0<b+c+d≤1,0<e≤2,0≤f<2,0<x≤0.8。

[0008] The present invention provides a positive electrode material, which includes a layered lithium-containing metal oxide. The general formula of the layered lithium-containing metal oxide is Li a L x Ni b Co c Mn d M (1-b-c-d) O e N f, where the L ion is a cation with a radius larger than that of the Li ion, M includes at least one of Mg, Zr, Al, B, Ta, Mo, W, Nb, Sb, La, N includes at least one of F, S, P, 0 < a < 2, 0 ≤ b < 1, 0 ≤ c < 1, 0 ≤ d < 1, 0 < b + c + d ≤ 1, 0 < e ≤ 2, 0 ≤ f < 2, 0 < x ≤ 0.8. After the lithium ions are removed from the cathode material, since the radius of the L ion is larger than that of the lithium ion, the range of the Coulomb interaction of the L ion with a large radius is larger than that of the lithium ion, which can weaken the electrostatic repulsion between the oxygen layers after the lithium ions are removed, and can also inhibit phenomena such as atomic misalignment and oxygen ion sliding caused by the vacancies generated during the removal of lithium ions. Therefore, the risk of structural collapse of the cathode material can be reduced, which is beneficial to improving the structural stability of the cathode material; in addition, the radius of the L ion is larger than that of the lithium ion, which can increase the layer spacing between the oxygen layers to a certain extent, thereby providing more space for the release of the stress generated during the charge and discharge process of the battery cell, and thus reducing the risk of cracking and oxidation of the cathode material caused by stress, which is beneficial to improving the stability of the cathode material. 0 < x ≤ 0.8. In this way, when the cathode material is used in a battery cell, the battery cell can have a high energy density while improving the stability of the cathode material. Therefore, the technical solution of the embodiment of the present application can improve the structural stability of the cathode material and the performance of the battery cell.

[0009] In one possible implementation, 0.001 ≤ x ≤ 0.5; optionally, 0.001 ≤ x ≤ 0.1. In this way, the battery cell can have a higher energy density while improving the stability of the cathode material.

[0010] In one possible implementation, 0 < c < 0.5. In this way, on the one hand, it is beneficial to improve the stability of the layered structure of the cathode material and the cycle performance of the battery cell; on the other hand, it is beneficial to reduce the preparation cost of the cathode material.

[0011] In one possible implementation, 0.3 ≤ b ≤ 0.96. In this way, by reasonably setting the content of Ni in the cathode material, it is beneficial to reasonably set the content of Co in the cathode material, which is beneficial to improving the stability of the layered structure of the cathode material.

[0012] In one possible implementation, 0 < d ≤ 0.3. In this way, by reasonably setting the content of Mn in the cathode material, it is beneficial to reasonably set the content of Co in the cathode material, which is beneficial to improving the stability of the layered structure of the cathode material.

[0013] In one possible implementation, the L ion occupies at least part of the lithium sites in the layered lithium-containing metal oxide, and the position of the Li ion in the layered lithium-containing metal oxide is the lithium site.

[0014] In the layered lithium-containing metal oxide structure, each element has its own arrangement position. In the layered lithium-containing metal oxide structure, the position where lithium ions are located is the lithium site, and L ions occupy at least part of the lithium sites in the layered lithium-containing metal oxide structure. The L ions have a large radius and are stable when occupying the lithium sites, which is beneficial to reducing the phenomenon of lithium-nickel mixing and thus beneficial to improving the stability of the layered structure.

[0015] In a possible implementation, the L ion element includes at least one of alkali metal elements, alkaline earth metal elements, transition metal elements, and other main group metal elements except lithium element. In this way, it is convenient to select appropriate elements for doping according to actual needs.

[0016] In a possible implementation, the alkali metal element includes at least one of Na, K, Rb, and Cs; the alkaline earth metal element includes at least one of Mg, Ca, and Sr; the transition metal element includes Y; and the other main group metal element includes Bi.

[0017] In the above technical solution, the above elements are convenient for doping and convenient for the preparation of the positive electrode material; in addition, by doping sodium ions, potassium ions, rubidium ions, cesium ions, etc. into the positive electrode material, it is beneficial to improve the stability of the positive electrode material.

[0018] In a possible implementation, the operating voltage V of the positive electrode material satisfies: V = kx, where 0 < k < 100. In this way, it is convenient to reasonably set the value of y according to the required positive electrode material to meet the requirement of the positive electrode material for the operating voltage.

[0019] In a possible implementation, the Poisson's ratio S of the positive electrode material is less than 0. In this way, it is beneficial to improve the stability of the positive electrode material, and at the same time, it is also beneficial to increase the operating voltage of the battery cell.

[0020] In a possible implementation, the Poisson's ratio S of the positive electrode material satisfies: -2 < S < 0; optionally, -0.2 ≤ S ≤ -0.05. In this way, the positive electrode material has high stability, and at the same time, it is also beneficial to increase the operating voltage of the battery cell, thereby increasing the energy density of the battery cell.

[0021] In a possible implementation, the operating voltage V of the positive electrode material satisfies: V = -TS, where 0 < T < 100. In this way, it is convenient to reasonably set the value of S according to the required positive electrode material to meet the requirement of the positive electrode material for the operating voltage.

[0022] In a second aspect, the present application provides a positive electrode tab, which includes the positive electrode material in the first aspect and any one of the possible implementations thereof.

[0023] In a third aspect, the present application provides a battery cell, including the positive electrode sheet described in the second aspect.

[0024] In a possible implementation, the operating voltage of the battery cell is 2V to 5V; optionally, it is 4.4V to 5V. In this way, it is beneficial to improve the energy density of the battery cell.

[0025] In a fourth aspect, the present application provides a battery, including the battery cell in the third aspect and any one of its possible implementations.

[0026] In a fifth aspect, the present application provides an electrical device, including the battery described in the fourth aspect.

[0027] The present application provides a positive electrode material, which includes a layered lithium-containing metal oxide. The general formula of the layered lithium-containing metal oxide is Li a L x Ni b Co c Mn d M (1-b-c-d) O e N f , where the L ion is a cation with a radius larger than that of the Li ion, M includes at least one of Mg, Zr, Al, B, Ta, Mo, W, Nb, Sb, La, N includes at least one of F, S, P, 0 < a < 2, 0 < b ≤ 0.96, 0 < c < 1, 0 < d < 1, 0 < b + c + d ≤ 1, 0 < e ≤ 2, 0 ≤ f < 2, 0 < x ≤ 0.8. After the lithium ions are removed from the positive electrode material, since the radius of the L ion is larger than that of the lithium ion, the range of the Coulomb interaction of the L ion with a large radius is larger than that of the lithium ion, which can weaken the electrostatic repulsion between the oxygen layers after the lithium ions are removed, and can also inhibit phenomena such as atomic misalignment and oxygen ion sliding caused by the vacancies generated by the removal of lithium ions. Therefore, the risk of structural collapse of the positive electrode material can be reduced, which is beneficial to improving the structural stability of the positive electrode material; in addition, the radius of the L ion is larger than that of the lithium ion, which can increase the layer spacing between the oxygen layers to a certain extent, thereby providing more space for the release of stress generated during the charge and discharge process of the battery cell, and thus reducing the risk of cracking and oxidation of the positive electrode material caused by stress, which is beneficial to improving the stability of the positive electrode material. 0 < x ≤ 0.8. In this way, when the positive electrode material is used in a battery cell, the battery cell can have a high energy density while improving the stability of the positive electrode material. Therefore, the technical solution of the present application can improve the performance of the positive electrode material and the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic diagram of a battery cell according to an embodiment of the present application;

[0029] FIG2 is a schematic diagram of a battery module according to an embodiment of the present application;

[0030] FIG3 is a schematic diagram of a battery according to an embodiment of the present application;

[0031] FIG4 is a schematic diagram of an electrical device according to an embodiment of the present application. DETAILED DESCRIPTION

[0032] Below, the embodiments of the positive electrode material, positive electrode sheet, battery cell, battery and electrical device of the present application are described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0033] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0034] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0035] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0036] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0037] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0038] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0039] Positive electrode materials, used to make the positive electrode sheets of battery cells, are crucial to their performance. Positive electrode materials can be broadly categorized into three structural types: layered oxides, such as LiMO2, where M comprises at least one of Co, Ni, and Mn; spinel oxides, such as LiMn2O4; and olivine oxides, such as LiFePO4. Layered positive electrode materials are widely used due to their high specific energy and capacity. In layered positive electrode materials, each metal oxide layer has two oxygen atom planes, with transition metal atoms occupying the interstitial cavities. Lithium ions are embedded in the gaps between the metal oxide layers, forming a one-atom-thick lithium layer. During the charge and discharge process of a battery cell, lithium ions can move two-dimensionally from their plane, undergoing lithium ion extraction and insertion.

[0040] Currently, the operating voltage of the cathode material with a layered structure is relatively low, resulting in limited improvement in the energy density of the battery cell. In some treatment methods, the energy density of the battery cell can be increased by raising the charge-discharge voltage (also known as the operating voltage) of the battery cell. However, when the charge-discharge voltage of the battery cell is relatively high, on the one hand, during the charging process of the battery cell, the number of lithium ions in the cathode material is relatively small, the cathode material is in a lithium-deficient state, and the structure of the cathode material is prone to collapse, thus affecting the performance of the battery cell; on the other hand, the stress generated during the charge-discharge process of the battery cell may cause cracking of the cathode material, leading to increased oxidation of the cathode material and affecting the performance of the battery cell.

[0041] The applicant has found through research that by doping cations with an ionic radius larger than that of lithium ions in the cathode material and reasonably setting the content of the doped cations, the stability of the cathode material can be improved, which is beneficial to enhancing the performance of the battery cell. In view of this, an embodiment of the present application provides a cathode material including a layered lithium-containing metal oxide, and the general formula of the layered lithium-containing metal oxide is Li a L x Ni b Co c Mn d M (1-b-c-d) O e N f , where the L ion is a cation with an ionic radius larger than that of the Li ion, M includes at least one of Mg, Zr, Al, B, Ta, Mo, W, Nb, Sb, La, N includes at least one of F, S, P, 0 < a < 2, 0 ≤ b < 1, 0 ≤ c < 1, d < 1, 0 < b + c + d ≤ 1, 0 < e ≤ 2, 0 ≤ f < 2, 0 < x ≤ 0.8. In this way, the stability of the cathode material can be improved, which is beneficial to enhancing the performance of the battery cell.

[0042] [Cathode Material]

[0043] An embodiment of the present application provides a cathode material, which includes a layered lithium-containing metal oxide, and the general formula of the layered lithium-containing metal oxide is Li a L x Ni b Co c Mn d M (1-b-c-d) O<* e N f , where the L ion is a cation with an ionic radius larger than that of the Li ion, M includes at least one of Mg, Zr, Al, B, Ta, Mo, W, Nb, Sb, La, N includes at least one of F, S, P, 0 < a < 2, 0 ≤ b < 1, 0 ≤ c < 1, 0 ≤ d < 1, 0 < b + c + d ≤ 1, 0 < e ≤ 2, 0 ≤ f < 2, 0 < x ≤ 0.8.

[0044] A layered lithium-containing metal oxide may refer to a lithium-containing salt that includes a metal element. For example, the layered lithium-containing metal oxide may be lithium nickel cobalt manganese oxide. "Layered" may refer to a lithium-containing metal oxide having a layered crystal structure.

[0045] L ions are cations with a radius larger than that of lithium ions. Thus, after lithium ions are released from the positive electrode material, since the radius of the L ions is larger than that of the lithium ions, the range of the Coulombic effect of the L ions with a large radius is larger than that of the lithium ions. This can weaken the electrostatic repulsion between the oxygen layers after the lithium ions are released, and can also inhibit phenomena such as atomic dislocation and oxygen ion sliding caused by vacancies generated by the release of lithium ions, thereby reducing the risk of structural collapse of the positive electrode material and improving the structural stability of the positive electrode material. In addition, the radius of the L ions is larger than that of the lithium ions, which can increase the spacing between the oxygen layers to a certain extent, thereby providing more space for releasing the stress generated by the battery cell during the charge and discharge process, reducing the risk of cracking and oxidation of the positive electrode material due to stress, and helping to improve the stability of the positive electrode material.

[0046] 0≤b<1, 0≤c<1, 0≤d<1, 0<b+c+d≤1, for example, b is 0, 0.1, 0.3, 0.5, 0.9 or any value within the above range, c is 0, 0.1, 0.3, 0.5, 0.9 or any value within the above range, d is 0, 0.1, 0.3, 0.5, 0.9 or any value within the above range, and the present embodiment does not impose any specific restrictions on this, as long as the above conditions are met. In the embodiment of the present application, b, c, and d are not all 0 at the same time, and one or two of the three can be 0. For example, the layered lithium-containing metal oxide is Li 0.5 Na 0.5 NiO2、Li 0.5 Na 0.5 CoO2、Li 0.5 Na 0.5 MnO2、Li 0.5 Na 0.5 Ni 0.9 Al 0.1 O2, etc.

[0047] M includes at least one of Mg, Zr, Al, B, Ta, Mo, W, Nb, Sb, and La, and 0<b+c+d≤1. When b+c+d<1, the layered lithium-containing metal oxide includes M element, and the layered lithium-containing metal oxide can have higher stability; when b+c+d=1, the layered lithium-containing metal oxide does not include M element, and the general formula of the layered lithium-containing metal oxide can be Li a L x Ni b Coc Mn d O e N f 。

[0048] It can be understood that the position of M ions in the layered lithium-containing metal oxide structure can be the position replacing part of the transition metals. For example, in the case where the layered lithium-containing metal oxide is a nickel-cobalt-manganese-based ternary material, M ions can replace part of the manganese position, nickel position or cobalt position.

[0049] N includes at least one of F, S, P, 0 ≤ f < 2. For example, f is 0, 0.5, 1, 1.5 or any other value within the above range. When f = 0, the layered lithium-containing metal oxide does not include the N element, and the general formula of the layered lithium-containing metal oxide can be Li a L x Ni b Co c Mn d M (1-b-c-d) O e 。

[0050] It can be understood that the position of N ions in the layered lithium-containing metal oxide structure can be the position replacing part of O. Optionally, e + f = 2.

[0051] 0 < a < 2, and the value of a can be flexibly set according to the required capacity of the battery cell. For example, a is 0.9, 1, 1.2, 1.5, 1.8 or any other value within the above range. When a is greater than 1, the layered lithium-containing metal oxide can be a lithium-rich metal oxide, which is beneficial to increasing the content of active lithium in the positive electrode material, thereby being beneficial to increasing the capacity of the battery cell.

[0052] 0 < x ≤ 0.8. For example, x is 0.001, 0.005, 0.1, 0.5, 0.6, 0.8 or any other value within the above range. On the one hand, x > 0, and the inclusion of L ions in the layered lithium-containing metal oxide is beneficial to improving the stability of the positive electrode material; on the other hand, x ≤ 0.8, and the content of L ions is within a suitable range, which can avoid the situation where the content of lithium ions is relatively low due to the excessive content of L ions, so that the battery cell can have relatively appropriate cycling performance while having a relatively high energy density.

[0053] It should be noted that the general formula of the layered lithium-containing metal oxide given in the embodiment of the present application can be a general formula in a rational state. The ideal state may include that when preparing the positive electrode material, the added lithium-containing layered oxide satisfies the above general formula. After the positive electrode material is prepared into a battery cell, due to various situations such as the deintercalation or consumption of lithium ions, the actual content of lithium ions may be reduced compared to the above general formula. Similarly, the actual content of oxygen ions may also be reduced. For example, when the lithium-containing layered metal oxide is Li 0.5 Na 0.5 In the case of NiO2, the actual measured formula may be Li 0.5+e Na 0.5+g NiO 2+f , e<0, g<0, f<0.

[0054] The positive electrode material in the embodiment of the present application can be used as a positive electrode active material. For example, it can be mixed with a binder, a conductive agent and a corresponding solvent to prepare a slurry, which can then be coated on a positive electrode current collector to prepare a positive electrode sheet.

[0055] The present invention provides a positive electrode material, which includes a layered lithium-containing metal oxide. The general formula of the layered lithium-containing metal oxide is Li a L x Ni b Co c Mn d M (1-b-c-d) O e N f, where the L ion is a cation with a radius larger than that of the Li ion, M includes at least one of Mg, Zr, Al, B, Ta, Mo, W, Nb, Sb, and La, N includes at least one of F, S, and P, 0 < a < 2, 0 ≤ b < 1, 0 ≤ c < 1, 0 ≤ d < 1, 0 < b + c + d ≤ 1, 0 < e ≤ 2, 0 ≤ f < 2, and 0 < x ≤ 0.8. After the lithium ions are removed from the cathode material, since the radius of the L ion is larger than that of the lithium ion, the range of the Coulomb interaction of the L ion with a large radius is larger than that of the lithium ion, which can weaken the electrostatic repulsion between the oxygen layers after the lithium ions are removed. It can also inhibit phenomena such as atomic misalignment and oxygen ion sliding caused by the vacancies generated during the removal of lithium ions, thereby reducing the risk of structural collapse of the cathode material and being conducive to improving the structural stability of the cathode material. In addition, since the radius of the L ion is larger than that of the lithium ion, it can increase the layer spacing between the oxygen layers to a certain extent, providing more space for the release of the stress generated during the charge and discharge process of the battery cell. Thus, it can reduce the risk of cracking and oxidation of the cathode material caused by stress and is beneficial to improving the stability of the cathode material. 0 < x ≤ 0.8. In this way, when the cathode material is used in a battery cell, the battery cell can have high cycle performance while improving the stability of the cathode material. Therefore, the technical solution of this application can improve the structural stability of the cathode material and the performance of the battery cell.

[0056] In some embodiments, 0.001 ≤ x ≤ 0.5. In this way, the cathode material has high stability, and the battery cell has a high operating voltage and good cycle performance.

[0057] Optionally, 0.001 ≤ x ≤ 0.1. In this way, the battery cell has a high operating voltage and good cycle performance.

[0058] In some embodiments, 0 < a < 1 and a + x = 1. In this way, the cathode material satisfying this proportional relationship is easy to prepare and obtain, which is beneficial to reducing production costs.

[0059] In some embodiments, 0 < c < 0.5. In this way, by reasonably setting the content of Co in the cathode material, on the one hand, it is beneficial to improving the stability of the layered structure of the cathode material and the cycle performance of the battery cell; on the other hand, it is beneficial to reducing the preparation cost of the cathode material.

[0060] In some embodiments, 0.3 ≤ b ≤ 0.96. In this way, by reasonably setting the content of Ni in the cathode material, it is beneficial to reasonably setting the content of Co in the cathode material and is beneficial to improving the stability of the layered structure of the cathode material.

[0061] In some embodiments, 0 < d ≤ 0.3. Thus, by reasonably setting the content of Mn in the cathode material, it is beneficial to reasonably set the content of Co in the cathode material, thereby facilitating the improvement of the stability of the layered structure of the cathode material.

[0062] In some embodiments, 0.3 ≤ b ≤ 0.96, 0 < c < 0.5, 0 < d ≤ 0.3. By reasonably setting the contents of Ni, Co, and Mn in the cathode material, it is beneficial to balance the operating voltage and cycling performance of the battery cell.

[0063] In some embodiments, L ions occupy at least part of the lithium sites in the layered lithium-containing metal oxide, and the position of Li ions in the layered lithium-containing metal oxide is the lithium site.

[0064] In the layered lithium-containing metal oxide structure, each element has its own arrangement position. In the layered lithium-containing metal oxide structure, the position where lithium ions are located is the lithium site, and L ions occupy at least part of the lithium sites in the layered lithium-containing metal oxide structure. The radius of L ions is large, and occupying the lithium site is stable, which is beneficial to reducing the phenomenon of lithium-nickel mixing and thus conducive to improving the stability of the layered structure.

[0065] In some embodiments, the L ion element includes at least one of alkali metal elements, alkaline earth metal elements, transition metal elements, and other main group metal elements other than lithium element. Thus, it is convenient to select a suitable element for doping according to actual needs.

[0066] In some embodiments, the alkali metal elements include at least one of Na, K, Rb, and Cs; the alkaline earth metal elements include at least one of Mg, Ca, and Sr; the transition metal element includes Y; and the other main group metal element includes Bi.

[0067] The above elements are convenient for doping and facilitating the preparation of the cathode material; in addition, by doping sodium ions, potassium ions, rubidium ions, cesium ions, etc. into the cathode material, it is beneficial to improve the stability of the cathode material.

[0068] In some embodiments, the operating voltage V of the cathode material satisfies: V = kx, where 0 < k < 100.

[0069] The unit of k is the same as the unit of voltage V, both being volts (V), and the value of k can be determined according to the operating voltage V and the content y of L ions.

[0070] The operating voltage of the cathode material can be understood as the voltage of the battery cell when the cathode material is fabricated into a cathode electrode sheet and used in the battery cell. This voltage can be understood as the charge-discharge voltage of the battery cell, and in some cases, it can also be understood as the upper or lower limit of the charge-discharge voltage of the battery cell.

[0071] The higher the voltage of the battery cell, the higher the number of lithium ions extracted from the positive electrode material, and thus the greater the possibility of the structure of the positive electrode material changing. The operating voltage V of the positive electrode material and the content y of L ions satisfy a certain relationship. By reasonably setting y, the requirement for the operating voltage V can be met while the positive electrode material maintains good structural stability.

[0072] In the above embodiments, it is convenient to reasonably set the value of y according to the required positive electrode material to meet the requirement of the positive electrode material for the operating voltage.

[0073] In some embodiments, the Poisson's ratio S of the positive electrode material is less than 0.

[0074] For the positive electrode material of the embodiments of the present application, the fact that the Poisson's ratio S of the positive electrode material is less than 0 is reflected in that when the positive electrode material is stretched in the direction of lithium ion deintercalation / insertion, the positive electrode material expands in the direction perpendicular to the lithium ion deintercalation / insertion; when the positive electrode material is compressed in the direction of lithium ion deintercalation / insertion, the positive electrode material contracts in the direction perpendicular to the lithium ion deintercalation / insertion. It can also be said that when the size of the positive electrode material becomes larger in one direction, the sizes of the positive electrode material in the other two directions perpendicular to the above direction become smaller. [[ID=IO]]

[0075] The Poisson's ratio S of the positive electrode material can refer to the Poisson's ratio of the lattice structure of the positive electrode material itself.

[0076] During the continuous charge and discharge of the battery cell, stress will be generated. When the battery cell is in a high-voltage state, the positive electrode material is in a lithium-deficient state, and the relatively large stress generated may cause the positive electrode material to crack. The cracked positive electrode material is easily oxidized, affecting the performance of the battery cell. The Poisson's ratio S of the positive electrode material of the present application is less than 0. When the structure of the positive electrode material is stretched in the direction of lithium ion extraction, due to the Poisson's ratio S of the positive electrode material being less than 0, the positive electrode material will not contract in the direction perpendicular to the lithium ion extraction direction, thereby reducing the possibility of the positive electrode material cracking and further reducing the possibility of the positive electrode material being oxidized.

[0077] In the above embodiments, the Poisson's ratio S of the positive electrode material is less than 0. In this way, it is beneficial to improve the stability of the positive electrode material, and at the same time, it is also beneficial to increase the operating voltage of the battery cell.

[0078] In some embodiments, the Poisson's ratio S of the positive electrode material satisfies: -2 < S < 0; optionally, -0.2 ≤ S ≤ -0.05. In this way, the positive electrode material has high stability, and at the same time, it is also beneficial to increase the operating voltage of the battery cell, thereby increasing the energy density of the battery cell.

[0079] In some embodiments, the operating voltage V of the positive electrode material satisfies: V = -TS, where 0 < T < 100.

[0080] The unit of T is the same as that of voltage V, both of which are volts v, where the value of T can be determined based on the used voltage V and the Poisson's ratio S of the positive electrode material.

[0081] The operating voltage V of the positive electrode material is related to the Poisson's ratio S of the positive electrode material. In the above embodiment, the value of S is reasonably set according to the required operating voltage of the positive electrode material to meet the working voltage requirement of the positive electrode material.

[0082] [Positive electrode]

[0083] An embodiment of the present application provides a positive electrode plate, comprising the positive electrode material in the above embodiment.

[0084] In some embodiments, the positive electrode plate includes a positive electrode current collector and a coating disposed on the positive electrode current collector, wherein the coating includes the positive electrode material in the above embodiments.

[0085] In some embodiments, the coating includes a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0086] In some embodiments, the coating layer includes a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0087] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0088] [Battery Cell]

[0089] An embodiment of the present application provides a battery cell, comprising the positive electrode sheet in the above embodiment.

[0090] The embodiment of the present application has no particular limitation on the shape of the battery cell, which may be cylindrical, square, or any other shape.

[0091] FIG1 is a schematic diagram of a battery cell according to an embodiment of the present application. As shown in FIG1 , the battery cell 3 includes a housing 31 , a cover plate 32 , and an electrode assembly 33 disposed in the housing 31 .

[0092] The electrode assembly 33 can be made of the positive electrode sheet, the negative electrode sheet and the separator according to the embodiment of the present application through a winding process or a lamination process.

[0093] Optionally, the battery cell 3 further includes an electrolyte. The electrolyte can be solid, semi-solid, or liquid, and this embodiment of the application does not impose any specific limitation on this.

[0094] In some embodiments, battery cells may be assembled into a battery module. The number of battery cells contained in a battery module may be one or more. The specific number may be selected by those skilled in the art based on the application and capacity of the battery module.

[0095] Figure 2 is a schematic diagram of a battery module according to one embodiment of the present application. Referring to Figure 2 , within a battery module 4, multiple battery cells 3 may be arranged sequentially along the length of the battery module 4. Of course, any other arrangement is also possible. Furthermore, the multiple battery cells 3 may be secured together using fasteners.

[0096] Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of battery cells 3 are accommodated in the accommodation space.

[0097] In some embodiments, the operating voltage of the battery cell is 2V to 5V; optionally, 4.4V to 5V. This is beneficial to improving the energy density of the battery cell.

[0098] When the battery cell operates at a higher voltage, such as greater than 4.4V, the positive electrode material maintains greater stability, allowing it to maintain its original structure. Furthermore, the operating voltage of a battery cell is related to its energy density: a higher operating voltage contributes to a higher energy density. This allows the battery cell to operate at a higher voltage, thereby increasing its energy density.

[0099] [Battery]

[0100] An embodiment of the present application provides a battery, comprising the battery cell described in the above embodiment.

[0101] Figure 3 is a schematic diagram of a battery according to an embodiment of the present application. As shown in Figure 3, the present application provides a battery 5, comprising the battery cell 3 according to any of the above embodiments.

[0102] The battery cells 3 can be directly assembled into the battery 5 , or they can be assembled into battery modules first, and then multiple battery modules can be assembled into the battery 5 .

[0103] [Electrical devices]

[0104] An embodiment of the present application provides an electrical device, comprising the battery described in the above embodiment.

[0105] Figure 4 is a schematic diagram of an electric device according to an embodiment of the present application. As shown in Figure 4 , the present application provides an electric device 6 including the battery 5 according to the above embodiment.

[0106] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0107] [Example]

[0108] Example 1

[0109] The general formula of the positive electrode material of Example 1 is Li 0.5 Na 0.5 Ni 0.5 Co 0.2 Mn 0.3 O2 is prepared as follows: In Example 1, a is 0.5 and x is 0.5.

[0110] (1) Add nickel acetate, cobalt acetate and manganese acetate to deionized water in a stoichiometric ratio and stir evenly to obtain a transition metal salt solution; (2) Quickly pour sodium carbonate solution into the above transition metal salt solution, continue to react for 9 hours, and then let it stand for 4 hours to obtain grown primary particles; (3) Wash the above primary particles with deionized water three times, dry them in a blower dryer, and then place them under vacuum at 100°C for 12 hours. Collect the dried solid, which is the precursor; (4) Mix the precursor with lithium carbonate and sodium carbonate in a molar ratio of 1:0.535:0.535 and grind them (wherein, the excess lithium carbonate is to compensate for the loss of lithium during high-temperature calcination); (5) Transfer the fully ground solid powder to a crucible and place it in a muffle furnace with programmed temperature for calcination. The calcination procedure is as follows: (6) Pre-calcine from room temperature to 500°C for 5 hours, and then heat to a high temperature of 800°C for 12 hours, with a heating rate of 3°C min -1 , and then cooled to room temperature and collected to obtain the above-mentioned positive electrode material.

[0111] Example 2

[0112] The general formula of the positive electrode material of Example 2 is Li 0.4 Na 0.6 Ni 0.5 Co0.2 Mn 0.3 O2. In Example 2, a is 0.4 and x is 0.6.

[0113] The preparation method of Example 2 is substantially the same as that of Example 1, except that the molar ratio in step (4) is different. In Example 2, the precursor, lithium carbonate, and sodium carbonate are in a molar ratio of 1:0.428:0.642.

[0114] Example 3

[0115] The general formula of the positive electrode material of Example 3 is Li 0.3 Na 0.7 Ni 0.5 Co 0.2 Mn 0.3 O2. In Example 3, a is 0.3 and x is 0.7.

[0116] The preparation method of Example 3 is substantially the same as that of Example 1, except that the molar ratio in step (4) is different. In Example 3, the precursor, lithium carbonate, and sodium carbonate are in a molar ratio of 1:0.321:0.749.

[0117] Example 4

[0118] The general formula of the positive electrode material of Example 4 is Li 0.2 Na 0.8 Ni 0.5 Co 0.2 Mn 0.3 O2. In Example 4, a is 0.2 and x is 0.8.

[0119] The preparation method of Example 4 is substantially the same as that of Example 1, except that the molar ratio in step (4) is different. In Example 3, the precursor, lithium carbonate, and sodium carbonate are in a molar ratio of 1:0.214:0.856.

[0120] Example 5

[0121] The general formula of the positive electrode material of Example 5 is Li 0.9 Na 0.1 Ni 0.5 Co 0.2 Mn 0.3 O2. In Example 5, a is 0.9 and x is 0.1.

[0122] The preparation method of Example 5 is substantially the same as that of Example 1, except that the molar ratio in step (4) is different. In Example 5, the precursor, lithium carbonate, and sodium carbonate are in a molar ratio of 1:0.963:0.107.

[0123] Example 6

[0124] The general formula of the positive electrode material of Example 6 is Li 0.99 Na 0.01 Ni 0.5 Co 0.2 Mn 0.3 O2. In Example 6, a is 0.99 and x is 0.01.

[0125] The preparation method of Example 6 is substantially the same as that of Example 1, except that the molar ratio in step (4) is different. In Example 6, the precursor, lithium carbonate, and sodium carbonate are in a molar ratio of 1:1.056:0.011.

[0126] Example 7

[0127] The general formula of the positive electrode material of Example 7 is Li 0.999 Na 0.001 Ni 0.5 Co 0.2 Mn 0.3 O2. In Example 6, a is 0.999 and x is 0.001.

[0128] The preparation method of Example 7 is substantially the same as that of Example 1, except that the molar ratio in step (4) is different. In Example 7, the precursor, lithium carbonate, and sodium carbonate are in a molar ratio of 1:1.068:0.002.

[0129] Examples 8-13

[0130] The general formula of the positive electrode material of Example 8 is Li 0.5 Na 0.5 Ni 0.3 Co 0.4 Mn 0.3 O2, the general formula of the positive electrode material of Example 9 is Li 0.5 Na 0.5 Ni 0.4 Co 0.3 Mn 0.3 O2, the general formula of the positive electrode material of Example 10 is Li 0.5 Na 0.5 Ni 0.7 Co 0.1 Mn 0.2 O2, the general formula of the positive electrode material of Example 11 is Li 0.5 Na 0.5 NiO2, the general formula of the positive electrode material of Example 12 is Li 0.5 Na 0.5 CoO2, the general formula of the positive electrode material of Example 13 is Li 0.5 Na 0.5 MnO2.

[0131] The difference between Examples 8-13 and Example 1 lies in the contents of Co, Mn, and Ni.

[0132] Example 14

[0133] The general formula of the positive electrode material of Example 14 is Li 0.5 Na 0.1 K 0.2 Cs 0.05 Rb 0.15 Ni 0.5 Co 0.2 Mn 0.3 O2. In Example 14, a is 0.5 and x is 0.5.

[0134] The preparation method of Example 14 is substantially the same as that of Example 1, except that the molar ratio in step (4) is different. In Example 14, the precursor and lithium carbonate, sodium carbonate, potassium carbonate, cesium carbonate, and rubidium carbonate are in a molar ratio of 1:0.535:0.107:0.216:0.0535:0.1605.

[0135] Examples 15-20

[0136] The general formula of the positive electrode material of Example 15 is Li 0.5 K 0.5 Ni 0.5 Co 0.2 Mn 0.3 O2, the general formula of the positive electrode material of Example 16 is Li 0.5 Rb 0.5 Ni 0.5 Co 0.2 Mn 0.3 O2, the general formula of the positive electrode material of Example 17 is Li 0.5 Cs 0.5 Ni 0.5 Co 0.2 Mn 0.3 O2, the general formula of the positive electrode material of Example 18 is Li 0.5 Mg 0.5 Ni 0.5 Co 0.2 Mn 0.3 O2, the general formula of the positive electrode material of Example 19 is Li 0.5 Y 0.5 Ni 0.5 Co 0.2 Mn 0.3 O2, the general formula of the positive electrode material of Example 20 is Li 0.5 Bi 0.5 Ni 0.5 Co 0.2 Mn0.3 O2.

[0137] The difference between Examples 15-20 and Example 1 lies in the different doped L elements.

[0138] Examples 21-23

[0139] The general formula of the positive electrode material of Example 21 is Li 1.5 Na 0.5 Ni 0.5 Co 0.2 Mn 0.3 O2, the general formula of the positive electrode material of Example 22 is Li 1.2 Na 0.8 Ni 0.5 Co 0.2 Mn 0.3 O2, the general formula of the positive electrode material of Example 23 is Li 0.8 Na 0.8 Ni 0.5 Co 0.2 Mn 0.3 O2.

[0140] The difference between Examples 21-23 and Example 1 is that the value of x+a is different.

[0141] In Examples 21-23, the molar ratios of the precursor to lithium carbonate and sodium carbonate are 1:1.605:0.535; 1:1.284:0.856; and 1:0.856:0.856, respectively.

[0142] Examples 24-25

[0143] In Examples 24-25, M element is doped.

[0144] The general formula of the positive electrode material of Example 24 is Li 0.5 Na 0.5 Ni 0.5 Co 0.2 Mn 0.2 Al 0.1 O2, in Example 24, M is Al.

[0145] The general formula of the positive electrode material of Example 25 is Li 0.5 Na 0.5 Ni 0.5 Co 0.2 Mn 0.2 Mg 0.1 O2, in Example 25, M is Mg.

[0146] Comparative Example 1

[0147] The general formula of the positive electrode material of Comparative Example 1 is LiNi0.5 Co 0.2 Mn 0.2 Al 0.1 In Comparative Example 1, the positive electrode material is not doped with cations having an ion radius larger than that of lithium ions.

[0148] Comparative Example 2

[0149] The general formula of the positive electrode material of Comparative Example 2 is LiNi 0.5 Co 0.2 Mn 0.3 In Comparative Example 2, the positive electrode material is not doped with cations having an ion radius larger than that of lithium ions.

[0150] [Preparation of positive electrode sheet]

[0151] The above-mentioned positive electrode material, polyvinylidene fluoride binder, and carbon black conductive agent are mixed in a mass ratio of 90:5:5. N-methyl-pyrrolidone is used as the solvent. The amount of solvent added is adjusted to control the slurry viscosity to 100-20,000 mPa.s. The slurry is applied to the positive electrode current collector using a coater or sprayer. After drying at 85°C, it is cold pressed. Then, the edges are trimmed, cut into pieces, and slit. Then, it is dried under vacuum at 85°C for 4 hours. The tabs are welded to produce the positive electrode sheets of the battery cells that meet the requirements.

[0152] [Preparation of battery cells]

[0153] The positive electrode sheet, separator, and negative electrode sheet are stacked and wound in order to obtain an electrode assembly; the electrode assembly is placed in an outer package, and an electrolyte is added. After packaging, standing, formation, aging and other processes, a battery cell is obtained.

[0154] [Method for determining the general formula]

[0155] The general formula of the positive electrode material can be determined by chemical analysis.

[0156] The composition of the positive electrode material can be determined by inductively coupled plasma (ICP) spectrometry analysis, and reference can be made to standards YS / T 1006.2-2014, GB / T 23367.2-2009, or YS / T 1028.5-2015. As an example, in the embodiments of the present application, an inductively coupled plasma emission spectrometer can be used for measurement. Alternatively, the content of metal elements in the sample can also be determined by gravimetric analysis and ethylenediaminetetraacetic acid (EDTA) complexometric titration.

[0157] [Test method of Poisson's ratio]

[0158] The Poisson's ratio of the positive electrode material can be determined as follows.

[0159] The laser beam is directly shot onto the surface of the positive electrode (or positive electrode material powder) to stimulate surface acoustic waves. The incident sound wave in acoustic microscopy is the medium shooting onto the surface of the material to stimulate surface acoustic waves. According to the classical elastic wave propagation theory, the surface Rayleigh wave velocity v can be obtained. R Approximate relationship with elastic modulus: v R =(C 11 / ρ) 1 / 2 [(2.87C 11 -4C 44 ) / 3(C 11 -4C 44 )], where: C 11 =G(E-4G) / (E-3G), C 44 =G,C 11 、C 44 are two independent elastic coefficient components; ρ is the material layer density. 11 and C 44 The best C 11 and C 44 value, based on the best C 11 and C 44 The E and G values ​​can be deduced from the values, and the Poisson's ratio of the material can be calculated by the following general formula: G = E / [2(1+S)], where: tensile modulus E (or Young's modulus), shear modulus G and Poisson's ratio S are used to describe the elastic behavior of the material.

[0160] [Testing the upper limit of the operating voltage of battery cells]

[0161] Determined by cyclic voltammetry: During the test, the measured voltage range is continuously increased, the current is constant at 0.1C, and a different voltage range-current relationship diagram is obtained. The upper limit voltage of the sudden voltage range is the upper limit voltage of the battery cell.

[0162] [Battery cell cycle life test]

[0163] The battery was charged and discharged using a constant current charge and discharge instrument at 25°C and 1C / 1C conditions, and the number of cycles required to reach 80% SOH was tested.

[0164] [Volume energy density test]

[0165] At 25°C, the battery cell was charged at a constant current of 0.33C to 4.35V, then charged at a constant voltage of 4.35V until the current was less than 0.05C, and then discharged at 0.33C to 2.8V to obtain the discharge energy E. The size of the battery cell was measured using the three-coordinate method (which can be measured using a three-coordinate measuring machine) to calculate the volume V.

[0166] Volume energy density K = E / V.

[0167] Table 1 shows the experimental results of various embodiments and comparative examples. Specific data can be found in Table 1.

[0168] The upper limit of the operating voltage of a battery cell is related to the stability of the positive electrode material. The higher the stability of the positive electrode material, the higher the upper limit of the voltage of the battery cell can be achieved, and thus the higher energy density of the battery cell can be achieved.

[0169] Combining Examples 1-23 with Comparative Example 2, and combining Example 24 with Comparative Example 1, it can be seen that by doping ions whose ion radius is larger than that of lithium ions, such as by doping sodium ions, potassium ions, cesium ions, and rubidium ions, it is beneficial to increase the upper limit of the operating voltage of the battery cell, and it is also beneficial to increase the cycle life of the battery cell.

[0170] As shown in Examples 1-7, a reasonable setting of the value of x is conducive to achieving the negative Poisson's ratio characteristics of the positive electrode material, thereby increasing the upper voltage limit of the applicable battery cell; at the same time, when the value of y is small, a larger upper voltage limit can be achieved.

[0171] As shown in Examples 8-13, by reasonably setting the ratio of the three elements Ni, Co, and Mn, it is beneficial to take into account the energy density, upper limit of operating voltage, and cycle life of the battery cell.

[0172] As shown in Example 1 and Examples 24-25, adding Al element to the positive electrode material is beneficial to improving the stability of the positive electrode material, thereby helping to increase the upper limit of the operating voltage and cycle life of the battery cell.

[0173] As shown in Examples 14-20, the positive electrode material can be doped with a variety of different ions, for example, sodium ions, potassium ions, cesium ions, rubidium ions, or a combination thereof, to increase the upper limit of the operating voltage of the battery cell.

[0174] As shown in Examples 21-23, as the total content of lithium ions and doped sodium ions increases, the content of lithium ions also increases, which is beneficial to further improve the energy density and cycle performance of the battery cell.

[0175] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A positive electrode material, characterized in that: The positive electrode material comprises a layered lithium-containing metal oxide, wherein the general formula of the layered lithium-containing metal oxide is Li a L x Ni b Co c Mn d M (1-b-c-d) O e N f , wherein L ion is a cation having a radius greater than that of Li ion, M includes at least one of Mg, Zr, Al, B, Ta, Mo, W, Nb, Sb, and La, N includes at least one of F, S, and P, and 0 <a<2,0≤b<1,0≤c<1,0≤d<1,0<b+c+d≤1,0<e≤2,0≤f<2,0<x≤0.8。 2. The positive electrode material according to claim 1, characterized in that 0.001 ≤ x ≤ 0.5; optionally, 0.001 ≤ x ≤ 0.

1.

3. The positive electrode material according to claim 1 or 2, characterized in that 0＜c＜0.5。 4. The positive electrode material according to any one of claims 1 to 3, characterized in that 0.3≤b≤0.96。 5. The positive electrode material according to any one of claims 1 to 4, characterized in that 0<d≤0.3。 6. The positive electrode material according to any one of claims 1 to 5, characterized in that The L ions occupy at least part of the lithium sites in the layered lithium-containing metal oxide, and the positions of the Li ions in the layered lithium-containing metal oxide are the lithium sites.

7. The positive electrode material according to any one of claims 1 to 6, characterized in that The L ion element includes at least one of an alkali metal element, an alkaline earth metal element, a transition metal element, and other main group metal elements other than the lithium element.

8. The positive electrode material according to claim 7, characterized in that The alkali metal element includes at least one of Na, K, Rb, and Cs; The alkaline earth metal element includes at least one of Mg, Ca, and Sr; The transition metal element includes Y; The other main group metal element includes Bi.

9. The positive electrode material according to any one of claims 1 to 8, characterized in that The operating voltage V of the positive electrode material satisfies: V = kx, where 0 < k < 100.

10. The positive electrode material according to any one of claims 1 to 9, characterized in that The Poisson's ratio S of the positive electrode material is less than 0.

11. The positive electrode material according to any one of claims 1 to 10, characterized in that The Poisson's ratio S of the positive electrode material satisfies: -2 < S < 0; optionally, -0.2 ≤ S ≤ -0.

05.

12. The positive electrode material according to claim 11, characterized in that The operating voltage V of the positive electrode material satisfies: V = -TS, where 0 < T < 100.

13. A positive electrode sheet, characterized in that: It includes the positive electrode material according to any one of claims 1-12.

14. A battery cell, characterized in that: It includes the positive electrode tab according to claim 13.

15. The battery cell according to claim 14, characterized in that: The operating voltage of the battery cell is 2V to 5V; optionally, it is 4.4V to 5V.

16. A battery, characterized in that: It includes the battery cell according to claim 14 or 15.

17. An electrical device, characterized in that: It includes the battery according to claim 16.

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