Material for battery positive electrode and use thereof in battery

Abstract

A material for a battery, having a structure of formula (I), wherein n is an integer selected from 1 to 10, 0≤x≤7n, 0≤y<3n, 0≤a<8n, 0≤b<8n, L is selected from one or more of Groups IA and IIA elements in a long period type periodic table of elements, M is selected from one or more of Groups IA-VIA, IB-VIIB and VIII metal elements in the long period type periodic table of elements, R is selected from one or more of Group VIIA elements in the long period type periodic table of elements, and Q is selected from one or more of Group VIA elements in the long period type periodic table of elements. The present invention further relates to a method for preparing the material of formula (I), a coating material, composite material, positive electrode active material, battery positive electrode, electrode sheet or separator containing the material of formula (I), and an electrochemical device. Na7n-xLxFe3n-yMyO8n-a-bRaQb (I)

Description

A material that can be used for battery positive electrode and its application in battery

[0001] This application claims priority to Chinese patent application No. 202311283540.0 filed on September 28, 2023, entitled “A material that can be used for a positive electrode of a battery and its application in a battery”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention belongs to the field of batteries, and in particular relates to a battery additive material, a preparation method and an application thereof. Background Art

[0003] Secondary batteries, also known as rechargeable batteries or storage batteries, refer to batteries that can be recharged to activate the active materials and continue to be used after the battery is discharged. Sodium-ion batteries and lithium-ion batteries are two commonly used secondary batteries on the market. Other metal-ion secondary batteries, such as magnesium-ion batteries and calcium-ion batteries, also show great potential and the possibility of surpassing sodium-ion batteries and lithium-ion batteries in some aspects. The working principles of metal-ion secondary batteries are similar, and similar problems also exist. For example, taking sodium-ion batteries as an example, when sodium-ion batteries are charged in the first week, a solid electrolyte interface phase (SEI) film will be formed on the surface of the negative electrode, causing irreversible capacity loss of the positive electrode material, thereby affecting the capacity and cycle life of the battery. Therefore, pre-sodiumization (sodium supplementation) is needed to solve this problem. Sodium-deficient oxide material Na tMO₂ (0 < t < 1) has a relatively high theoretical reversible capacity, good cycling performance and rate performance, and shows potential as a cathode material for sodium-ion batteries. However, the initial sodium content in sodium-deficient materials is insufficient, and additional sodium insertion is required for the remaining capacity. Therefore, in practical applications, an additional sodium source is needed to achieve and maintain a high specific capacity, and a large amount of sodium supplementation is required. The method of pre-sodiation (sodium supplementation) can effectively solve this problem. Currently, it can be roughly divided into two types according to the battery object to be treated: sodium supplementation at the negative electrode and sodium supplementation at the positive electrode. Sodium supplementation at the negative electrode is to achieve pre-insertion of sodium at the negative electrode by means of chemical / electrochemical reactions between sodium foil, sodium powder, etc. and the negative electrode sheet. Currently, due to factors such as safety, cost, and strict requirements for environmental control, its large-scale application is restricted. Sodium supplementation at the positive electrode is to add a sodium-rich material with a high capacity to the positive electrode sheet to compensate for the loss of active sodium at the negative electrode. Its advantage is that the sodium supplementation material can be directly added to the positive electrode slurry for use without changing the existing slurry-making and coating processes, which is convenient to operate and easy to industrialize. Currently, the reported sodium supplementation materials for the positive electrode include organic sodium salts and inorganic sodium supplementation agent materials. Among the inorganic sodium supplementation agent materials, those with relatively large commercial potential at present are mainly sodium-rich transition metal oxide types, but most of them have problems such as too high surface alkalinity and poor air stability (easy to absorb moisture and deteriorate). Among them, too high surface alkalinity will cause damage to the binder in the slurry, resulting in abnormal situations such as slurry jellyification and coating film peeling; while moisture absorption and deterioration will not only lead to a decrease in the sodium supplementation effect, but also affect the moisture control during the cell manufacturing process and the overall performance of the battery.

[0004] Therefore, there is a need to provide an improved battery additive that can overcome the disadvantages of the prior art and provide a relatively high commercial application value. Advantageously, a sodium supplementation agent is provided that can be controllably synthesized under simple conditions. Advantageously, a sodium supplementation agent is provided that has good air stability. Advantageously, a sodium supplementation agent is provided that has a relatively high theoretical specific capacity and / or a relatively low reversible specific capacity. Advantageously, a sodium supplementation agent is provided that has a relatively high irreversible specific capacity in the first cycle. Additionally, a battery additive is provided that can be applied to more types of metal ion secondary batteries by replacing a part or all of the sodium in the above sodium supplementation agent with one or more other alkali metal or alkaline earth metal elements such as lithium, magnesium, calcium, etc.

[0005] Summary of the Invention

[0006] In one aspect, the present invention provides a material having a structure of formula (I):

[0007] Na 7n-x L x Fe 3n-y M y O 8n-a-b R a Q b (I)

[0008] in:

[0009] n is an integer selected from 1 to 10,

[0010] 0≤x≤7n,

[0011] 0≤y<3n,

[0012] 0≤a<8n,

[0013] 0≤b<8n,

[0014] L is one or more elements selected from Groups IA and IIA of the long-period periodic table,

[0015] M is one or more metal elements selected from Groups IA-VIA, IB-VIIB and VIII of the long-period periodic table,

[0016] R is one or more elements selected from Group VIIA elements in the long-period periodic table, and

[0017] Q is one or more elements selected from Group VIA of the long-period periodic table. In another aspect, the present invention provides a method for preparing a material of formula (I) according to the present invention, the method comprising the following steps:

[0018] (a) mixing Fe2O3, Na2O and / or an oxide of L, and an optional dopant precursor to obtain a precursor mixture, wherein the stoichiometric ratio of Fe2O3 to the oxide of Na2O and / or L is 1:9-9:1, preferably 1:9-1:1, more preferably 1:6-1:2, wherein L is one or more elements selected from Groups IA and IIA of the long-period periodic table;

[0019] (b) heating the precursor mixture at a temperature of 100-1200° C., preferably 200-800° C., for 1-200 hours, preferably 20-100 hours under an inert atmosphere to perform high temperature sintering;

[0020] (c) Cooling to obtain the material.

[0021] In another aspect, the present invention provides a coated material comprising a core and a coating layer covering the surface of the core, wherein:

[0022] The core comprises a material of formula (I) according to the present invention;

[0023] The coating layer comprises one or more materials selected from the group consisting of metal fluorides, metal carbides, metal oxides, polymers, carbon, and combinations thereof;

[0024] Optionally, there may or may not be a cavity between the coating layer and the core, and optionally, the coating layer is a continuous layer or a discontinuous layer.

[0025] In another aspect, the present invention provides a composite material comprising a first material and a second material, wherein:

[0026] The first material comprises a material of formula (I) according to the present invention;

[0027] The second material is a positive electrode active material different from the first material.

[0028] In another aspect, the present invention provides a method for preparing a composite material according to the present invention, the method comprising the steps of compounding a first material and a second material in the form of mixing and / or coating, wherein the mixing preferably comprises the step of mixing the first material and the second material by stirring and / or grinding, and the coating preferably comprises the step of attaching the second material to the outside of the first material.

[0029] In another aspect, the present invention provides a positive electrode active material comprising one or more of the material of formula (I) according to the present invention, the coated material according to the present invention, the composite material according to the present invention, and combinations thereof.

[0030] In yet another aspect, the present invention provides a positive electrode for a battery, comprising the positive electrode active material according to the present invention, an optional conductive agent, and an optional binder.

[0031] In another aspect, the present invention provides an electrode sheet or a diaphragm, which comprises one or more of the material of formula (I) according to the present invention, the coated material according to the present invention, the composite material according to the present invention, and a combination thereof; the electrode sheet or the diaphragm preferably comprises a coating, and the coating comprises one or more of the material of formula (I) according to the present invention, the coated material according to the present invention, the composite material according to the present invention, and a combination thereof.

[0032] In yet another aspect, the present invention provides an electrochemical device comprising at least one of the positive electrode active material according to the present invention, the battery positive electrode according to the present invention, the electrode sheet or separator according to the present invention, and combinations thereof.

[0033] The present invention provides more possibilities for the development of high-performance batteries by providing a new type of battery additive material. The new type of battery additive material of the present invention can be used, for example, in sodium ion batteries and / or lithium ion batteries as a sodium / lithium supplement additive material. Specifically, the new type of battery additive material of the present invention can provide one or more of the following advantages: 1) it can be controllably synthesized under simple conditions; 2) it has good air stability; 3) it has a higher theoretical specific capacity and / or a lower reversible specific capacity; 4) it has a higher first-cycle irreversible specific capacity; 5) it can be widely applied to a variety of batteries, such as sodium ion batteries, lithium ion batteries, potassium ion batteries, rubidium ion batteries, cesium ion batteries, magnesium ion batteries, calcium ion batteries, strontium ion batteries, barium ion batteries and combinations thereof. Therefore, the present invention provides a new type of battery additive material with high commercial application value in the battery field, which can be widely applied to various types of batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention is explained in detail through the following specific embodiments and drawings, so that those skilled in the art can better understand the present invention. However, it should not be understood as limiting the scope of the present invention in any way.

[0035] FIG1 shows a scanning electron microscope (SEM) photograph of a sodium supplement according to one embodiment of the present invention (Example 1).

[0036] FIG2 shows an X-ray diffraction (XRD) pattern of a sodium supplement according to one embodiment of the present invention (Example 1).

[0037] FIG3 shows the XRD patterns of the sodium supplement according to one embodiment of the present invention (Example 1) before and after the air stability test (also known as the humidity test).

[0038] FIG4 shows the electrochemical performance of a sodium supplement half-cell according to one embodiment of the present invention (Example 1).

[0039] FIG5 shows XRD patterns of sodium supplements according to various embodiments (Examples 2-5) of the present invention.

[0040] FIG6 shows a scanning electron microscope-X-ray energy dispersive spectrometer (SEM-EDS) photograph of a sodium supplement according to one embodiment of the present invention (Example 2).

[0041] FIG7 shows the first cycle charge and discharge curves of a battery according to an embodiment of the present invention (Example 7) and a comparative embodiment (Comparative Example 2). DETAILED DESCRIPTION

[0042] In the context of describing the present invention (particularly in the context of the claims), unless otherwise stated herein or clearly contradictory to the context, the terms "one / a kind of" and "the / said" and similar uses should be interpreted as covering the singular and plural. Unless otherwise stated, the terms "comprise", "have", "include" and "contain" should be interpreted as open terms (that is, "including, but not limited to"), but also include "essentially consisting of..." and "consisting of..." Partially closed or closed terms. Unless otherwise stated, the term "and / or" means either or both. For example, "A and / or B" means only A, only B, or both A and B. Unless otherwise stated herein, the recording of numerical ranges herein is only intended to be used as a shorthand method for independently referring to each individual value falling within the range, and each individual value is incorporated into this specification as if it were independently recorded herein.

[0043] Unless otherwise indicated herein or the context clearly contradicts, all methods described herein can be performed in any suitable order. Unless otherwise stated, the use of any and all examples or exemplary language (e.g., "such as") provided herein is intended only to better illustrate the present invention and does not limit the scope of the present invention. Any language in this specification should not be construed as indicating that any unclaimed element is essential for the practice of the present invention.

[0044] Preferred embodiments of the present invention are described herein, including the best modes of implementing the present invention known to the inventors. After reading the description herein, variations of those preferred embodiments may become apparent to those of ordinary skill in the art. The inventors anticipate that skilled artisans will be able to appropriately adopt such variations, and anticipate that the present invention may be implemented in a manner different from that specifically described herein. Therefore, the present invention includes all variations and equivalents of the subject matter recited in the appended claims as permitted by applicable law. Furthermore, unless otherwise specified herein or clearly contradicted by the context, the present invention encompasses any combination of all possible variations of the above elements.

[0045] Listed below are definitions of various terms used to describe the materials disclosed herein. These definitions apply to the terms as used throughout this specification and claims, except where otherwise limited in specific instances, and where the terms are used either individually or as part of a larger group.

[0046] As used herein, the terms "optional", "optionally", and "optionally" include both selection and non-selection. For example, "optionally modified" includes both modification and non-modification.

[0047] Throughout this specification, reference to "an aspect," "an aspect," "one embodiment," "some embodiments," "an embodiment," "a specific embodiment," "a related embodiment," "an embodiment," "an additional embodiment," or "a further embodiment" or combinations thereof means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the aforementioned phrases in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0048] The first material, second material, coated material, composite material, positive electrode, separator, and electrochemical device of the present invention can be applied to battery systems / batteries, such as lithium-ion and sodium-ion battery systems. In one aspect, the electrochemical device and / or battery system of the present invention comprises a battery cell, which comprises a positive electrode and a negative electrode, and optionally further comprises a current collector, an electrolyte, and / or a separator. In this document, "battery system" can be used interchangeably with "battery."

[0049] The “first” or “second” in the “first material” or “second material” described herein is only for the convenience of expression and does not have any limitation or evaluation on the defined materials.

[0050] The term "cathode" as used herein refers to the electrode with higher electrical potential in a battery.

[0051] The term "anode" as used herein refers to the electrode with lower potential in a battery.

[0052] The term "sodium-supplementing" as used herein refers to the technology of replenishing a sodium source into a battery before operation.

[0053] The term "prelithiation" used herein refers to the technology of replenishing lithium sources into a battery before it operates.

[0054] The terms "sodium replenishing additive" or "sodium replenishing agent" used herein are used interchangeably to refer to a material that can replenish the irreversible sodium ion loss of a battery system, generally having a higher irreversible capacity.

[0055] As used herein, the terms "prelithiation additive" and "lithium replenisher" are used interchangeably to refer to materials that can replenish the irreversible lithium ion loss of a battery system, and generally have a higher irreversible capacity.

[0056] The term "long-form periodic table," also known as the "long-form periodic table," as used herein, refers to the most commonly used periodic table, which has seven horizontal rows and 18 vertical columns, each of which is called a period and each vertical column is called a group. The seven horizontal periods can be further divided into short periods (periods 1, 2, and 3), long periods (periods 4, 5, and 6), and an incomplete period (period 7). The vertical columns, from left to right, can be named using Arabic numerals as Groups 1 to 18, or using Roman numerals as Group IA, Group IIA, Group IIIB, Group IVB, Group VB, Group VIB, Group VIIB, Group VIII (including three columns), Group IB, Group IIB, Group IIIA, Group IVA, Group VA, Group VIA, Group VIIA, and Group 0.

[0057] The term "stoichiometric ratio" as used herein refers to the ratio of the amounts of substances participating in the reaction.

[0058] As used herein, variables represented by the same letters have the same meaning unless otherwise indicated.

[0059] In some embodiments, the “material that can be used for a battery positive electrode” described in the present invention may refer to a “battery positive electrode material”, also known as a “battery positive electrode active material” or “positive electrode active material” or “positive electrode material”.

[0060] Specifically, the present invention provides a new battery additive material, the chemical formula of which is A 14 Fe6O 16 (The simplest molecular formula is A7Fe3O8), wherein A is one or more elements selected from Groups IA and IIA of the long-period periodic table, such as one or more selected from lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, and barium. This material has never been disclosed in the prior art. 14 Fe6O 16 Alternatively, A7Fe3O8 can be independently doped with different elements at the A, Fe, and O sites to produce doped active materials (e.g., positive electrode active materials). Coating techniques can produce coated active materials (e.g., positive electrode active materials). Composite active materials (e.g., positive electrode active materials) can be produced by combining with other materials. This material and its derivatives can be used as positive electrode active materials for batteries and have high commercial application value. The present invention also provides methods for preparing this material and / or its derivatives, as well as their use in positive electrode active materials, battery positive electrodes, battery cells or separators, electrochemical devices, and the like.

[0061] In some embodiments, the present invention provides a material having the structure of Formula (I):

[0062] Na 7n-xL x Fe 3n-y M y O 8n-a-b R a Q b (I)

[0063] in:

[0064] n is an integer selected from 1 to 10,

[0065] 0≤x≤7n,

[0066] 0≤y<3n,

[0067] 0≤a<8n,

[0068] 0≤b<8n,

[0069] L is one or more elements selected from Groups IA and IIA of the long-period periodic table,

[0070] M is one or more metal elements selected from Groups IA-VIA, IB-VIIB and VIII of the long-period periodic table,

[0071] R is one or more elements selected from Group VIIA elements in the long-period periodic table, and

[0072] Q is one or more elements selected from Group VIA elements in the long-period periodic table.

[0073] In formula (I), the atomic molar ratio of (Na+L):(Fe+M):(O+R+Q) is 7:3:8.

[0074] In some embodiments, n is an integer selected from any one of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Preferably, n is selected from 1, 2, and 3.

[0075] In some embodiments, x is a value within the range formed by any two of the following numbers as endpoints: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, and 70. In some embodiments, x is 0. In some embodiments, x is 7n, where n is defined as above. In some embodiments, x is a non-integer. For example, x can be a decimal selected from, for example, 0.01, 0.05, 0.10, 10.十一, 20.20, 30.30, 40.40, 50.50, 60.60, 69.69, and the range formed by any two of these numbers as endpoints. When x is neither 0 nor 7n, the material can be used not only as a sodium supplement for sodium-ion batteries but also as a supplement for the metal-ion battery represented by L. For example, when x is within the range of 0 - 7n and not at the endpoint values (i.e., 0 and 7n) and L is lithium (Li), the material can be used as a sodium supplement for sodium-ion batteries and also as a lithium supplement for lithium-ion batteries.

[0076] In some embodiments, y is a value within the range formed by any two of the following numbers as endpoints: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, and 30. In some embodiments, y is 0. In some embodiments, 0 < y < 3n / 2, where n is defined as above. In some embodiments, y is a non-integer. For example, y can be a decimal selected from, for example, 0.01, 0.05, 0.10, 1.50, 5.11, 10.20, 15.30, 20.40, 25.50, 29.60, and the range formed by any two of these numbers as endpoints.

[0077] In some embodiments, a is a value within the range formed by any two of the following numbers as endpoints: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, and 40. In some embodiments, a is 0. In some embodiments, 0 < a < 4n, where n is defined as above. In some embodiments, a is a non-integer. For example, a can be a decimal selected from, for example, 0.01, 0.05, 0.10, 1.50, 5.11, 10.20, 15.30, 20.40, 25.50, 30.60, 35.50, 39.60, and the range formed by any two of these numbers as endpoints.

[0078] In some embodiments, b is a value within the range formed by any two of the following numbers as endpoints: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, and 40. In some embodiments, b is 0. In some embodiments, 0 < b < 4n, where n is defined as above. In some embodiments, b is a non-integer. For example, b can be a decimal selected from, for example, 0.01, 0.05, 0.10, 1.50, 5.11, 10.20, 15.30, 20.40, 25.50, 30.60, 35.50, 39.60, and the range formed by any two of these numbers as endpoints.

[0079] In some embodiments, L is one or more elements selected from Group IA and Group IIA of the long-period form of the periodic table of elements and excluding Na, and is an element that can be used for doping or substituting Na at the Na site. Preferably, L is one or more elements selected from lithium, potassium, rubidium, cesium, magnesium, calcium, strontium, and barium. In some embodiments, L is one or more elements selected from lithium, potassium, magnesium, calcium, and barium. In some embodiments, L is lithium.

[0080] In some embodiments, M is one or more elements selected from the metal elements in Group IA - VIA, Group IB - VIIB, and Group VIII of the long-period form of the periodic table of elements and excluding Fe, and is an element that can be used for doping at the Fe site. Specifically, M is one or more elements selected from the metal elements in Group IA, IIA, IIIA, IVA, VA, VIA, IB, IIB, IIIB, IVB, VB, VIB, VIIB, and VIII of the long-period form of the periodic table of elements. Preferably, M is one or more elements selected from lithium, magnesium, aluminum, nickel, boron, scandium, titanium, vanadium, chromium, manganese, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, iridium, and tin. In some embodiments, M is one or more elements selected from titanium, vanadium, chromium, manganese, cobalt, nickel, copper, and zinc. In some embodiments, M is titanium.

[0081] In some embodiments, R is one or more elements selected from Group VIIA of the long-period form of the periodic table of elements, and is an element that can be used for doping at the O site. Preferably, R is one or more elements selected from fluorine, chlorine, bromine, and iodine. In some embodiments, R is one or more elements selected from fluorine, chlorine, and bromine. In some embodiments, R is fluorine.

[0082] In some embodiments, Q is one or more elements selected from Group VIA of the long-period periodic table, excluding O, and is an element that can be used for doping at the O position. Preferably, Q is one or more selected from sulfur, selenium, and tellurium. In some embodiments, Q is one or more selected from sulfur and selenium. In some embodiments, Q is sulfur.

[0083] In some embodiments, the present invention provides a material having the structure of Formula (I):

[0084] Na 7n-x L x Fe 3n-y M y O 8n-a-b R a Q b (I)

[0085] Wherein formula (I) satisfies one or more of the following conditions:

[0086] 1) n is selected from 1, 2 and 3;

[0087] 2) x is 0 or 7n;

[0088] 3)0≤y<3n / 2;

[0089] 4)0≤a<4n;

[0090] 5) 0≤b<4n;

[0091] 6) M is one or more selected from lithium, magnesium, aluminum, nickel, boron, scandium, titanium, vanadium, chromium, manganese, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, iridium and tin;

[0092] 7) L is one or more selected from lithium, potassium, rubidium, cesium, magnesium, calcium, strontium, and barium;

[0093] 8) R is one or more selected from fluorine, chlorine, bromine, and iodine; and

[0094] 9) Q is one or more selected from sulfur, selenium, and tellurium.

[0095] In some embodiments, the material of formula (I) is selected from Na 7n Fe 3n O 8n 、Na 7n Fe 3n-y Ti y O 8n 、Na 7n Fe 3n-y Mn y O 8n 、Na 7n Fe3n- y Al y O 8n 、Na 7n Fe 3n-y Co y O 8n 、Na 7n Fe 3n-y Cu y O 8n 、Na 7n Fe 3n-y Zn y O 8n 、Na 7n Fe 3n-y Ru y O 8n 、Na 7n Fe 3n-y Y y O 8n 、Na 7n Fe 3n-y B y O 8n 、Na 7n Fe 3n-y Mg y O 8n 、Na 7n Fe 3n-y Zr y O 8n 、Na 7n Fe 3n-y Ni y O 8n 、Na 7n Fe 3n O 8n-a F a One or more of, wherein n is 1 or 2, 0 <y<3n,0<a<8n。

[0096] In some embodiments, the material of formula (I) is Na7Fe3O8 or Na 14 Fe6O 16 .

[0097] In some embodiments, the present invention provides a method for preparing a material of formula (I) according to the present invention, the method comprising the following steps:

[0098] (a) mixing Fe2O3, Na2O and / or an oxide of L, and an optional dopant precursor to obtain a precursor mixture, wherein the stoichiometric ratio of Fe2O3 to the oxide of Na2O and / or L is 1:9-9:1, preferably 1:9-1:1, more preferably 1:6-1:2, wherein L is one or more elements selected from Groups IA and IIA of the long-period periodic table;

[0099] (b) heating the precursor mixture at a temperature of 100-1200° C., preferably 200-800° C., for 1-200 hours, preferably 20-100 hours under an inert atmosphere to perform high temperature sintering;

[0100] (c) Cooling to obtain the material.

[0101] In some embodiments, the stoichiometric ratio of Fe2O3 to Na2O and / or L oxide is within a range consisting of any two of the following ratios as endpoints: 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, and 9:1.

[0102] In some embodiments, the inert atmosphere is at least one selected from nitrogen, argon, and helium.

[0103] In some embodiments, the precursor mixture is subjected to high temperature sintering at a temperature within a range consisting of any two of the following values ​​as endpoints: 100° C., 200° C., 300° C., 400° C., 500° C., 600° C., 700° C., 800° C., 900° C., 1000° C., 1100° C., and 1200° C. The high temperature sintering time may be within a range consisting of any two of the following values ​​as endpoints: 1 hour, 3 hours, 5 hours, 8 hours, 10 hours, 15 hours, 20 hours, 25 hours, 30 hours, 40 hours, 50 hours, 60 hours, 70 hours, 80 hours, 90 hours, 100 hours, 110 hours, 120 hours, 130 hours, 140 hours, 150 hours, 160 hours, 170 hours, 180 hours, 190 hours, and 200 hours.

[0104] In some embodiments, the dopant precursor is one or more selected from the group consisting of an oxide of M, sodium fluoride, sodium sulfide, iron fluoride, and iron sulfide, wherein M is one or more metal elements selected from Groups IA-VIA, IB-VIIB, and VIII of the long-period periodic table. Preferably, the dopant precursor is an oxide of M, wherein M is one or more metal elements selected from Groups IA, IIA, IIIA, IVA, VA, VIA, IB, IIB, IIIB, IVB, VB, VIB, VIIB, and VIII of the long-period periodic table. M is an element that dopes at the Fe position and is an element other than Fe. Preferably, M is one or more selected from the group consisting of lithium, magnesium, aluminum, nickel, boron, scandium, titanium, vanadium, chromium, manganese, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, iridium, and tin. In some embodiments, M is one or more selected from the group consisting of titanium, vanadium, chromium, manganese, cobalt, nickel, copper, and zinc. In some embodiments, M is titanium.

[0105] In some embodiments, the present invention provides a coated material comprising a core and a coating layer covering the surface of the core, wherein:

[0106] The core comprises a material of formula (I) according to the present invention;

[0107] The coating layer comprises one or more materials selected from the group consisting of metal fluorides, metal carbides, metal oxides, polymers, carbon, and combinations thereof.

[0108] In the present invention, there may or may not be a cavity between the coating layer and the core, and the coating layer may be a continuous layer or a discontinuous layer. The material of the coating layer includes but is not limited to: metal fluoride, metal carbide, metal oxide, polymer.

[0109] In some embodiments, the coating layer comprises one or more of a metal fluoride coating layer, a metal carbide coating layer, and a metal oxide coating layer, wherein the metal elements in the metal fluoride, the metal carbide, and the metal oxide are independently selected from one or more of nickel, cobalt, aluminum, manganese, lithium, potassium, barium, iron, calcium, copper, zinc, titanium, magnesium, zirconium, strontium, chromium, tin, antimony, tungsten, niobium, molybdenum, vanadium, palladium, bismuth, cesium, hafnium, tantalum, polonium, gallium, indium, thallium, yttrium, scandium, lanthanides, and combinations thereof.

[0110] In some embodiments, the coating comprises a metal fluoride coating, wherein the metal fluoride comprises nickel, cobalt, aluminum, manganese, lithium, potassium, barium, iron, calcium, copper, zinc, titanium, magnesium, zirconium, strontium, chromium, tin, antimony, tungsten, niobium, molybdenum, vanadium, palladium, bismuth, cesium, hafnium, tantalum, polonium, gallium, indium, thallium, yttrium, scandium, and metal fluorides of the lanthanide series.

[0111] In some embodiments, the coating comprises a metal carbide coating, wherein the metal carbide comprises metal carbides of nickel, cobalt, aluminum, manganese, lithium, potassium, barium, iron, calcium, copper, zinc, titanium, magnesium, zirconium, strontium, chromium, tin, antimony, tungsten, niobium, molybdenum, vanadium, palladium, bismuth, cesium, hafnium, tantalum, polonium, gallium, indium, thallium, yttrium, scandium, and lanthanides.

[0112] In some embodiments, the coating layer comprises a metal oxide coating layer, wherein the metal oxide is selected from nickel, cobalt, aluminum, manganese, lithium, potassium, barium, iron, calcium, copper, zinc, titanium, magnesium, zirconium, strontium, chromium, tin, antimony, tungsten, niobium, molybdenum, vanadium, palladium, bismuth, cesium, hafnium, tantalum, polonium, gallium, indium, thallium, yttrium, scandium and metal oxides of lanthanides. Preferably, the metal element in the metal oxide is selected from one or more of nickel, cobalt, aluminum, manganese, lithium, potassium, barium, iron, calcium, copper, zinc, titanium, magnesium, zirconium and combinations thereof. More preferably, in some embodiments, the metal oxide is aluminum oxide.

[0113] In some embodiments, the coating layer comprises a polymer coating layer, a carbon coating layer and a combination thereof, wherein the polymer includes one or more selected from the following: polypyrrole polymers and their modifications, polythiophene polymers and their modifications, polyamide polymers and their modifications, polyethylene oxide polymers and their modifications, polyvinylidene fluoride polymers and their modifications, polyacrylate polymers and their modifications, polyacrylonitrile polymers and their modifications, polyether polymers and their modifications, polysiloxane polymers and their modifications or polyanion single ion conductor type polymers and their combinations. One or more.

[0114] The preparation method of the coated material according to the present invention is not subject to any restriction, and suitable coating method can be selected by those skilled in the art according to the material used. For example, coating can be carried out by one or more methods in vacuum evaporation, ion plating, chemical vapor deposition (CVD) (such as thermal CVD, plasma CVD, organometallic CVD, metal CVD etc.), atomic layer deposition (ALD), radio frequency sputtering, magnetron sputtering, reactive sputtering, ball milling mixing, sol-gel method, hydrothermal or solvent thermal coating, spray drying.

[0115] In some embodiments, the coated material according to the present invention can be obtained by mixing Fe2O3, Na2O and / or L oxides, a coating layer precursor material and an optional dopant precursor and heating them at a certain temperature (e.g., a temperature of 100-800°C) for a certain time (e.g., 1-12 hours) to perform high-temperature sintering (preferably high-temperature sintering under an inert atmosphere), and then cooling.

[0116] In some embodiments, the coated material according to the present invention can be obtained by first forming a core material, then mixing the core material with a coating layer precursor material and heating at a certain temperature (e.g., a temperature of 100 - 800 °C) for a certain time (e.g., 1 - 12 hours) for high-temperature sintering (preferably high-temperature sintering is carried out in an inert atmosphere), and then cooling.

[0117] In some embodiments, the present invention provides a composite material comprising a first material and a second material, wherein the first material comprises a material of formula (I) according to the present invention; the second material is a battery active material different from the first material.

[0118] In some embodiments, the second material is at least one sodium-containing positive electrode active material selected from Prussian blue, polyanion compounds, transition metal layered oxides, and sodium-containing organic compounds. Preferably, the second material is selected from Na(Ni x’ Fe y’ Mn 1- x’-y’ )O2, Na 0.74 (Ni x’ Fe y’ Mn 1-x’-y’ )O2, Na 0.67 (Ni x’ Mn y’ Ti 1-x’-y’ )O2, Na 0.67 (Ni x’ Mn y’ Zn z’ Cu1-x’-y’-z’)O2, Na2M’[Fe(CN)6], NaVPO4F, Na2FePO4F, Na3V2(PO4)3, Na2Fe2(SO4)3, NaTiO2, NaMnO2, NaFeO2, NaCoO2, NaNiO2, Na2C6O6, and combinations thereof, where 0 < x’ < 1, 0 < y’ < 1, 0 < z’ < 1, and M’ is selected from Fe, Co, Mn, Ni, Cu, and combinations thereof.

[0119] In some embodiments, the second material is selected from Na(Ni x’ Fe y’ Mn 1-x’-y’ )O2, Na 0.74 (Ni x’ Fe y’ Mn 1-x’-y’ )O2, Na 0.67 (Ni x’ Mn y’ Ti 1-x’-y’ )O2, Na 0.67 (Nix’ Mn y’ Zn z’ Cu1-x'-y'-z')O2 and combinations thereof, wherein x', y' and z' in each chemical formula are independently selected from the range consisting of any two of the following numbers as endpoints (including or excluding the endpoints): 0, 1 / 50, 1 / 30, 1 / 20, 1 / 10, 1 / 9, 1 / 8, 1 / 7, 1 / 6, 1 / 5, 1 / 4, 1 / 3, 1 / 2 and 1.

[0120] In some embodiments, the second material is selected from NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2、Na 0.74 Ni 1 / 4 Fe 1 / 4 Mn 1 / 2 O2 and its combinations.

[0121] In some embodiments, the second material is selected from Na2M'[Fe(CN)6], wherein M' is selected from Co, Mn, Ni, Cu, and combinations thereof.

[0122] In some embodiments, the second material is one or more selected from ternary materials (e.g., nickel-cobalt-manganese, nickel-cobalt-aluminum, and / or nickel-cobalt-lithium ternary materials), sodium vanadium phosphate, sodium fluorovanadium phosphate, sodium cobaltate, sodium manganate, and combinations thereof. As used herein, the term "ternary material" refers to any known ternary material in the battery field.

[0123] In some embodiments, the weight ratio of the first material to the second material is 1:30 to 30: 1. The weight ratio of the first material to the second material can be within a range consisting of any two of the following ratios as endpoints: 1:30, 1:29, 1:28, 1:27, 1:26, 1:25, 1:24, 1:23, 1:22, 1:21, 1:20, 1:18, 1:15, 1:13, 1:10, 1:8, 1:5, 1:2, 1:1, 2:1, 5:1, 8:1, 10:1, 13:1, 15:1, 18:1, 20:1, 21:1, 22:1, 23:1, 24:1, 25:1, 26:1, 27:1, 28:1, 29:1, 30:1.

[0124] The composite method of the first material and the second material is not limited in any way and can be selected by those skilled in the art as needed. In some embodiments, the composite method of the first material and the second material can be a simple physical mixing or a form in which the second material is attached to the outside of the first material.

[0125] In some embodiments, the first material further comprises one or more additional materials selected from the group consisting of NaN3, Na2O, Na2O2, Na2C2O4, Na2CO3, Na3C6H5O7, Na2C2O2N2, Na2C2N4, Na2C4H5NO4, Na3C7H8NO6, and combinations thereof. The additional materials can be combined with the material of formula (I) by mixing or any other means to serve as the first material.

[0126] In some embodiments, the weight ratio of the material of formula (I) to the additional material is 1:30 to 30: 1. The weight ratio of the material of formula (I) to the additional material can be within a range consisting of any two of the following ratios as endpoints: 1:30, 1:29, 1:28, 1:27, 1:26, 1:25, 1:24, 1:23, 1:22, 1:21, 1:20, 1:18, 1:15, 1:13, 1:10, 1:8, 1:5, 1:2, 1:1, 2:1, 5:1, 8:1, 10:1, 13:1, 15:1, 18:1, 20:1, 21:1, 22:1, 23:1, 24:1, 25:1, 26:1, 27:1, 28:1, 29:1, 30:1.

[0127] When the material of formula (I) is combined with the second material and / or the aforementioned additional material for charge and discharge, the material of formula (I), as a transition metal compound, can also act as a catalyst when combined with the second material and / or the aforementioned additional material. The material of formula (I) and the second material and / or the aforementioned additional material serve as different types of sodium replenishers, which can simultaneously replenish sodium and help the other sodium replenishers reduce their decomposition voltage, thereby achieving a higher sodium replenishment capacity.

[0128] In some embodiments, the present invention provides a method for preparing a composite material according to the present invention, comprising the steps of combining a first material and a second material by mixing and / or coating. The mixing preferably comprises the steps of mixing the first material and the second material by stirring and / or grinding. The coating preferably comprises the steps of attaching the second material to the outside of the first material.

[0129] In some embodiments, the present invention provides a positive electrode active material comprising one or more of the material of formula (I) according to the present invention, the coated material according to the present invention, the composite material according to the present invention, and combinations thereof.

[0130] In some embodiments, the present invention provides a battery cathode comprising the cathode active material according to the present invention, an optional conductive agent, and an optional binder.

[0131] The choice of conductive agent is not subject to any restrictions and can be selected by those skilled in the art as needed. In some embodiments, the conductive agent is at least one selected from carbon black, acetylene black, Ketjen black, conductive graphite, carbon fiber, carbon nanotubes (CNTs), graphene, graphene oxide, reduced graphene oxide, and combinations thereof. Preferably, in some embodiments, the conductive agent is a carbon nanotube (CNTs) conductive agent.

[0132] Generally, the amount of the conductive agent used is 0.5-10% by weight based on the total weight of the battery positive electrode. Furthermore, the amount of the conductive agent used can be within a range consisting of any two of the following values ​​as endpoints: 0.5% by weight, 1% by weight, 1.5% by weight, 2% by weight, 2.5% by weight, 3% by weight, 3.5% by weight, 4% by weight, 4.5% by weight, 5% by weight, 5.5% by weight, 6% by weight, 6.5% by weight, 7% by weight, 7.5% by weight, 8% by weight, 8.5% by weight, 9% by weight, 9.5% by weight, and 10% by weight based on the total weight of the battery positive electrode.

[0133] The selection of binding agent is not subject to any restriction, can be selected as needed by those skilled in the art.In some embodiments, described binding agent is selected from at least one of polyvinylidene fluoride (PVDF), polyvinylidene chloride, polytetrafluoroethylene, polyethylene oxide, polyvinylidene chloride-hexafluoropropylene, polyacrylic acid, polyacrylonitrile, polyacrylamide, polyamide, polyamide-imide, polymethyl methacrylate, polycarbonate, carboxymethyl cellulose, sodium carboxymethyl cellulose, styrene-butadiene copolymer, sodium alginate, styrene-butadiene rubber and combination thereof.Preferably, in some embodiments, binding agent is PVDF.

[0134] Generally, the amount of the binder used is 0.5-10% by weight based on the total weight of the battery positive electrode. Furthermore, the amount of the binder used can be within a range consisting of any two of the following values ​​as endpoints: 0.5% by weight, 1% by weight, 1.5% by weight, 2% by weight, 2.5% by weight, 3% by weight, 3.5% by weight, 4% by weight, 4.5% by weight, 5% by weight, 5.5% by weight, 6% by weight, 6.5% by weight, 7% by weight, 7.5% by weight, 8% by weight, 8.5% by weight, 9% by weight, 9.5% by weight, and 10% by weight based on the total weight of the battery positive electrode.

[0135] In some embodiments, the weight ratio of the positive electrode active material, the binder, and the conductive agent is 1-10:1:1 or 2-9:1:1 or 3-8:1:1 or 4-7:1:1 or 5-6:1:1. For example, in some embodiments, the weight ratio of the positive electrode active material, the binder, and the conductive agent is 8:1:1.

[0136] In some embodiments, the present invention provides an electrode sheet comprising one or more of a material of formula (I) according to the present invention, a coated material according to the present invention, a composite material according to the present invention, and combinations thereof. Preferably, in some embodiments, the electrode sheet comprises a coating and the coating comprises one or more of a material of formula (I) according to the present invention, a coated material according to the present invention, a composite material according to the present invention, and combinations thereof.

[0137] In the field of electrochemistry, electrode sheets are important components of electrochemical cells and other electrochemical devices. In the present invention, electrode sheets refer to electrode sheets used in metal ion batteries, for example, positive electrode sheets (also known as "positive electrode sheets") and negative electrode sheets (also known as "negative electrode sheets"). In some embodiments, the electrode sheet according to the present invention further comprises a conductive substance. The conductive substance may be selected from conductive metals, conductive polymers, and combinations thereof. In some embodiments, the electrode sheet according to the present invention further comprises a current collector. The current collector may be made of a metal grid, conductive paper, or a combination thereof.

[0138] In some embodiments, the present invention provides a diaphragm comprising one or more of a material of formula (I) according to the present invention, a coated material according to the present invention, a composite material according to the present invention, and combinations thereof. Preferably, in some embodiments, the diaphragm comprises a coating and the coating comprises one or more of a material of formula (I) according to the present invention, a coated material according to the present invention, a composite material according to the present invention, and combinations thereof.

[0139] As used herein, the term "separator" refers to a membrane used in batteries, also known as a "battery separator." In some embodiments, a battery separator is a membrane material located between the positive and negative electrodes of a battery. Its primary function is to isolate the positive and negative electrodes, preventing electrons from freely passing through the battery while allowing ions in the electrolyte to pass freely between the positive and negative electrodes. In some embodiments, the separator according to the present invention further comprises a polymer material. The polymer material can be selected from polyethylene, polypropylene, and combinations thereof.

[0140] In some embodiments, the present invention provides an electrochemical device comprising at least one of a cathode active material according to the present invention, a battery cathode according to the present invention, an electrode sheet or separator according to the present invention, and combinations thereof. Preferably, in some embodiments, the electrochemical device is an energy storage system, such as a battery, more specifically a sodium ion battery, a lithium ion battery, a potassium ion battery, a rubidium ion battery, a cesium ion battery, a magnesium ion battery, a calcium ion battery, a strontium ion battery, a barium ion battery, or combinations thereof, especially a sodium ion battery, a lithium ion battery, or combinations thereof.

[0141] Therefore, the present invention can be applied to lithium-ion and sodium-ion battery systems, which are also the most mature energy storage systems currently used commercially. Its core components include a positive electrode, a negative electrode, an electrolyte, and a separator. During the charging process, under the action of an external circuit, lithium / sodium ions are deintercalated from the positive electrode active material and embedded into the negative electrode through the electrolyte separator. At the same time, the positive electrode loses electrons and flows out from the external circuit through the current collector. The discharge process is the opposite. Lithium / sodium ions are deintercalated from the negative electrode back to the positive electrode. At the same time, electrons move from the negative electrode to the positive electrode through the external circuit and perform work externally.

[0142] Example

[0143] The embodiments of the present invention will be described in detail below with reference to the examples, but those skilled in the art will appreciate that the following examples are intended only to illustrate the present invention and should not be construed as limiting the scope of the present invention. Where specific conditions are not specified in the examples, the experiments were performed according to conventional conditions or the conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments are not specified, they are all commercially available conventional products.

[0144] The experimental techniques and methods used in this example are conventional technical methods unless otherwise specified. The materials, reagents, etc. used in the examples can be synthesized by known methods or obtained through commercial channels unless otherwise specified. The synthetic techniques and conditions used are also easily understood by those skilled in the art.

[0145] Suitable modifications and adaptations of the various conditions, formulations, and other parameters normally encountered in the art and which would be apparent to those skilled in the art in light of this disclosure are within the spirit and scope of the present invention.

[0146] Example 1 Sodium ion battery using positive electrode sodium supplement

[0147] 1) Preparation of positive electrode sodium supplement:

[0148] Fe2O3 and Na2O were weighed in a stoichiometric ratio of 1:5. The powders were mixed and placed in a tube furnace. Dry argon was continuously introduced at a flow rate of 60 sccm and heated at 600°C for 200 hours. After sintering and cooling to room temperature, the resulting product was ground and sieved to obtain the positive electrode sodium supplement Na7Fe3O8.

[0149] The SEM image of the material is shown in Figure 1, showing that the overall morphology of the material is blocky and uniformly distributed. The XRD spectrum is shown in Figure 2. The synthesized material is consistent with the target material, with good crystallinity and no obvious impurity peaks.

[0150] The material was subjected to an air stability test (also known as a humidity test): a portion of the product powder was taken out and placed in a pharmaceutical tube and sealed with a sealing film, and then transferred to a constant temperature and humidity moisture-proof box with a humidity of 26% and a temperature of 25°C. After being stored for 24 hours, it was taken out and the appearance of the material was observed and an XRD test was performed.

[0151] The air stability test results showed no significant changes in the material's appearance, color, or morphology. XRD characterization of the material before and after the air stability test, as shown in Figure 3, also showed no significant changes in the material's phase.

[0152] 2) Preparation of battery positive electrode:

[0153] The Na7Fe3O8 prepared in step 1) was used as the positive electrode active material. The positive electrode active material, binder PVDF, and carbon nanotube (CNT) conductive agent were weighed in a weight ratio of 8:1:1. PVDF was first dissolved in NMP, then CNTs were added and dispersed evenly, and finally the above-mentioned positive electrode active material was added. After uniform dispersion, the resulting positive electrode slurry was filtered and coated on an aluminum foil current collector. After drying, rolling, and die-cutting, a circular positive electrode sheet with a diameter of 13 mm was obtained, with a loading of approximately 1.5 mg / cm. 2 .

[0154] 3) Assemble the battery:

[0155] The positive electrode sheet prepared in step 2) was matched with a sodium sheet (14 mm diameter and 0.45 mm thickness, same below) and a half-cell was assembled using 1M NaClO₄ + EC / PC (1:1, v / v) (i.e., sodium perchlorate as the electrolyte and a 1:1 volume ratio of propylene carbonate and ethylene carbonate as the solvent, same below) as the electrolyte. After the battery was allowed to rest for 24 hours, electrochemical testing was performed on a Land CT2001A constant current charge-discharge tester at a rate of 0.05C (the current value of the rated capacity discharged in 1 hour is defined as 1C, 1C = 411 mAh / g, same below) over a voltage range of 2.0V-4.5V. The first cycle charge-discharge curve is shown in Figure 4.

[0156] This material can release a specific capacity of 251.1mAh / g when charged to 4.2V in the first cycle, 280.0mAh / g at 4.3V, and 350.7mAh / g at 4.5V, but has almost no capacity when discharged to 2.0V in the first cycle.

[0157] Example 2 Sodium ion battery using a doped positive electrode sodium supplement

[0158] 1) Preparation of positive electrode sodium supplement:

[0159] Fe2O3, Na2O, TiO2, and Al2O3 were weighed and fully mixed in a stoichiometric ratio of 0.88:5:0.02:0.1, and the mixed powder was placed in a tube furnace, and dry argon was continuously introduced at a flow rate of 60 sccm, and heated at 600°C for 200 hours. After sintering and cooling to room temperature, the resulting product was ground and sieved to obtain a positive electrode sodium supplement doped with aluminum and titanium elements. The XRD test results of the product are shown in Figure 5. It can be seen that the material phase has no obvious difference compared with Na7Fe3O8, and no impurity peaks appear, indicating the successful incorporation of TiO2 and Al2O3. The SEM-EDS photo of the product powder is shown in Figure 6. It can be seen that there are obvious Fe and Al elements in the material, which further illustrates the successful incorporation of Fe and Al elements. The elemental analysis results obtained by EDS test are shown in Table 1. The molecular formula of the product can be deduced from the atomic percentage of transition metal elements to be Na7Fe 2.622 Al 0.304 Ti 0.055 □ 0.019 O8, where □ represents a vacancy.

[0160] Table 1 EDS element analysis results

[0161] 2) Preparation of battery positive electrode:

[0162] Take the material prepared in step 1) as the positive electrode active material, and weigh the positive electrode active material, binder PVDF and carbon nanotube (CNTs) conductive agent according to the weight ratio of 8:1:1. First, dissolve PVDF in N-methylpyrrolidone (NMP), then add CNTs and disperse them evenly, and finally add the above-mentioned positive electrode active material. After uniform dispersion, the obtained positive electrode slurry is filtered and coated on an aluminum foil current collector. After drying, rolling and die-cutting, a circular positive electrode sheet with a diameter of 13mm is obtained, with a loading of about 1.5mg / cm 2 .

[0163] 3) Assemble the battery:

[0164] The positive electrode sheet prepared in step 2) was matched with the sodium sheet, and a half-cell was assembled using 1M NaClO₄ + EC / PC (1:1, v / v) as the electrolyte. After the cell was allowed to rest for 24 hours, electrochemical testing was performed within the voltage range of 2.5-4.5 V using the same procedure as in Example 1.

[0165] The material can release a specific capacity of 379.4 mAh / g when charged to 4.5 V in the first cycle, but has almost no capacity when discharged to 2.0 V in the first cycle.

[0166] Example 3 Sodium ion battery using a doped positive electrode sodium supplement

[0167] 1) Preparation of positive electrode sodium supplement:

[0168] Fe2O3, Na2O, and NaF were weighed and mixed thoroughly in a stoichiometric ratio of 1:4.75:0.25. The mixed powder was placed in a tube furnace and continuously introduced with dry argon at a flow rate of 60 sccm. The mixture was heated at 600°C for 200 hours. After sintering and cooling to room temperature, the obtained product was ground and sieved to obtain the fluorine-doped positive electrode sodium supplement Na7Fe3O 7.6 F 0.4 The XRD test results of the powder are shown in Figure 5.

[0169] 2) Preparation of battery positive electrode:

[0170] The material prepared in step 1) was used as the positive electrode active material. The positive electrode active material, binder PVDF, and carbon nanotube (CNT) conductive agent were weighed in a weight ratio of 8:1:1. PVDF was first dissolved in NMP, then CNTs were added and dispersed evenly, and finally the above-mentioned positive electrode active material was added. After uniform dispersion, the obtained positive electrode slurry was filtered and coated on an aluminum foil current collector. After drying, rolling, and die-cutting, a circular positive electrode sheet with a diameter of 13 mm was obtained, with a loading of approximately 1.5 mg / cm 2 .

[0171] 3) Assemble the battery:

[0172] The cathode prepared in step 2) was paired with a sodium plate, and a half-cell was assembled using 1M NaClO₄ + EC / PC (1:1, v / v) as the electrolyte. After the cell was allowed to rest for 24 hours, electrochemical testing was performed within the voltage range of 2.5-4.5 V using the same procedure as in Example 1.

[0173] The material delivers a specific capacity of 394.1 mAh / g when charged to 4.5 V in the first cycle, but has almost no capacity when discharged to 2.0 V in the first cycle. The incorporation of transition metal elements improves the material's kinetics and reduces its decomposition voltage, allowing the doped product to release a higher specific capacity.

[0174] Example 4 Sodium ion battery using coated positive electrode sodium supplement

[0175] 1) Preparation of positive electrode sodium supplement:

[0176] Fe2O3 and Na2O were weighed in a stoichiometric ratio of 1:5. The powders were mixed and placed in a tube furnace. Dry argon was continuously introduced at a flow rate of 60 sccm, and the mixture was heated at 600°C for 200 hours. After sintering and cooling to room temperature, the resulting powder was ground and sieved to produce the positive electrode sodium supplement Na7Fe3O8. The resulting material was thoroughly mixed with 20% glucose by weight and placed in a tube furnace. Dry argon was continuously introduced at a flow rate of 60 sccm, and the mixture was heated at 350°C for 4 hours. After sintering and cooling to room temperature, the resulting product was ground and sieved to produce the carbon-coated positive electrode sodium supplement Na7Fe3O8. The XRD results of the powder are shown in Figure 5.

[0177] 2) Preparation of battery positive electrode:

[0178] The material prepared in step 1) was used as the positive electrode active material. The positive electrode active material, binder PVDF, and carbon nanotube (CNT) conductive agent were weighed in a weight ratio of 8:1:1. PVDF was first dissolved in NMP, then CNTs were added and dispersed evenly, and finally the above-mentioned positive electrode active material was added. After uniform dispersion, the obtained positive electrode slurry was filtered and coated on an aluminum foil current collector. After drying, rolling, and die-cutting, a circular positive electrode sheet with a diameter of 13 mm was obtained, with a loading of approximately 1.5 mg / cm 2 .

[0179] 3) Assemble the battery:

[0180] The positive electrode sheet prepared in step 2) was matched with the sodium sheet, and a half-cell was assembled using 1M NaClO₄ + EC / PC (1:1, v / v) as the electrolyte. After the cell was allowed to rest for 24 hours, electrochemical testing was performed within the voltage range of 2.0-4.5 V using the same procedure as in Example 1.

[0181] The material can release a specific capacity of 370.4 mAh / g when charged to 4.5 V in the first cycle, but has almost no capacity when discharged to 2.0 V in the first cycle. After coating, the material's air stability is improved, the deactivated part is reduced, and the corresponding specific capacity is improved.

[0182] Example 5 Sodium ion battery using coated positive electrode sodium supplement

[0183] 1) Preparation of positive electrode sodium supplement:

[0184] Fe2O3 and Na2O were weighed in a stoichiometric ratio of 1:5. The powders were mixed and placed in a tube furnace. Dry argon was continuously introduced at a flow rate of 60 sccm, and the mixture was heated at 600°C for 200 hours. After sintering and cooling to room temperature, the resulting powder was ground and sieved to produce Na7Fe3O8, a positive electrode sodium supplement. The resulting material was thoroughly mixed with 10% by weight aluminum isopropoxide. The mixed powder was placed in a tube furnace, dry argon was continuously introduced at a flow rate of 60 sccm, and the mixture was heated at 250°C for 2 hours. After sintering and cooling to room temperature, the resulting product was ground and sieved to produce the alumina-coated Na7Fe3O8, a positive electrode sodium supplement. The XRD results of the powder are shown in Figure 5.

[0185] 2) Preparation of battery positive electrode:

[0186] The material prepared in step 1) was used as the positive electrode active material. The positive electrode active material, binder PVDF, and conductive carbon nanotubes (CNTs) were weighed in a weight ratio of 8:1:1. PVDF was first dissolved in NMP, then the CNTs were added and dispersed evenly. Finally, the positive electrode active material was added. After uniform dispersion, the resulting positive electrode slurry was filtered and coated onto an aluminum foil current collector. After drying, roller pressing, and die-cutting, a circular positive electrode sheet with a diameter of 13 mm was obtained, with a loading of approximately 1.5 mg / cm. 2 .

[0187] 3) Assemble the battery:

[0188] The positive electrode sheet prepared in step 2) was matched with the sodium sheet, and a half-cell was assembled using 1M NaClO₄ + EC / PC (1:1, v / v) as the electrolyte. After the cell was allowed to rest for 24 hours, electrochemical testing was performed within the voltage range of 2.0-4.5 V using the same procedure as in Example 1.

[0189] The material can release a specific capacity of 375.6 mAh / g when charged to 4.5 V in the first cycle, but has almost no capacity when discharged to 2.0 V in the first cycle. After coating, the material's air stability is improved, the deactivated part is reduced, and the corresponding specific capacity is improved.

[0190] Example 6 Sodium Ion Battery Using Composite Positive Sodium Supplement

[0191] 1) Preparation of positive electrode sodium supplement:

[0192] Fe2O3 and Na2O were weighed in a stoichiometric ratio of 1:5. The powders were mixed and placed in a tube furnace. Dry argon was continuously introduced at a flow rate of 60 sccm and heated at 600°C for 200 hours. After sintering and cooling to room temperature, the resulting product was ground and sieved to obtain the positive electrode sodium supplement Na7Fe3O8.

[0193] 2) Preparation of battery positive electrode:

[0194] Take the material prepared in step 1) as a sodium supplement additive, weigh the sodium supplement additive NaNi and 1 / 3 Fe 1 / 3 Mn 1 / 3 O2, Na7Fe3O8, binder PVDF and carbon nanotubes (CNTs) conductive agent. First dissolve PVDF in NMP, then add CNTs and disperse them evenly, and finally add the above sodium supplement additives Na7Fe3O8 and NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 After uniform dispersion, the obtained positive electrode slurry was filtered and coated on an aluminum foil current collector, and then dried, rolled, and die-cut to obtain a composite positive electrode sodium supplementation electrode sheet, i.e. a circular positive electrode sheet with a diameter of 13 mm and a loading capacity of about 7.5 mg / cm 2 .

[0195] 3) Assemble the battery:

[0196] The positive electrode sheet prepared in step 2) was matched with the sodium sheet, and a half-cell was assembled using 1M NaClO₄ + EC / PC (1:1, v / v) as the electrolyte. After the cell was allowed to rest for 24 hours, electrochemical testing was performed within the voltage range of 2.0-4.2 V using the same procedure as in Example 1.

[0197] The material released a specific capacity of 192.6 mAh / g during the first charge cycle to 4.2 V, compared to the original cathode material's initial charge capacity of approximately 175 mAh / g, indicating that the sodium supplement contributed in part to this capacity. Upon discharge to 2.0 V, the specific capacity reached 165.0 mAh / g, demonstrating no negative impact on the capacity release of the cathode active material itself. The final battery achieved an initial coulombic efficiency of 85.80%, compared to approximately 93% for the original cathode material, demonstrating a significant effect of the sodium supplement.

[0198] Example 7 Sodium Ion Battery Using Composite Positive Sodium Supplement

[0199] 1) Preparation of positive electrode sodium supplement:

[0200] Fe2O3 and Na2O were weighed in a stoichiometric ratio of 1:5. The powders were mixed and placed in a tube furnace. Dry argon was continuously introduced at a flow rate of 60 sccm and heated at 600°C for 200 hours. After sintering and cooling to room temperature, the resulting product was ground and sieved to obtain the positive electrode sodium supplement Na7Fe3O8.

[0201] 2) Preparation of battery positive electrode:

[0202] Take the material prepared in step 1) as a sodium supplement additive, weigh the sodium supplement additive Na and 0.74 Ni 1 / 4 Fe 1 / 4 Mn 1 / 2 O2, Na7Fe3O8, binder PVDF and carbon nanotubes (CNTs) conductive agent. First dissolve PVDF in NMP, then add CNTs and disperse them evenly, and finally add the above sodium supplement additives Na7Fe3O8 and Na 0.74 Ni 1 / 4 Fe 1 / 4 Mn 1 / 2 After uniform dispersion, the obtained positive electrode slurry was filtered and coated on an aluminum foil current collector, and then dried, rolled, and die-cut to obtain a composite positive electrode sodium supplementation electrode sheet, i.e. a circular positive electrode sheet with a diameter of 13 mm and a loading capacity of about 7.5 mg / cm 2 .

[0203] 3) Assemble the battery:

[0204] The positive electrode sheet prepared in step 2) was matched with a sodium sheet, and a half-cell was assembled using 1M NaClO₄ + EC / PC (1:1, v / v) as the electrolyte. After the cell was allowed to rest for 24 hours, electrochemical testing was performed in the voltage range of 2.0-4.3 V according to the same procedure as in Example 1. The initial charge-discharge curve is shown in Figure 6.

[0205] The material released a specific capacity of 188.2 mAh / g during the first charge cycle to 4.3 V, compared to approximately 165 mAh / g for the original cathode material, indicating that the sodium supplement contributed to this capacity. Upon discharge to 2.0 V, the specific capacity reached 155.5 mAh / g, demonstrating no negative impact on the capacity release of the cathode active material itself. The final battery achieved a first-cycle coulombic efficiency of 82.33%, compared to approximately 92% for the original cathode material, demonstrating a significant effect of the sodium supplement.

[0206] Comparative Example 1: Sodium ion battery without sodium supplementation using the sodium supplement of the present invention

[0207] 1) Preparation of battery positive electrode:

[0208] NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3O2 was used as the positive electrode active material, and the positive electrode active material, binder PVDF, and carbon nanotube (CNT) conductive agent were weighed in a weight ratio of 8:1:1. PVDF was first dissolved in NMP, then CNTs were added and dispersed evenly, and finally the above positive electrode active materials were added. After uniform dispersion, the resulting positive electrode slurry was filtered and coated on an aluminum foil current collector. After drying, rolling, and die-cutting, a circular positive electrode sheet with a diameter of 13 mm was obtained, with a loading of approximately 7.5 mg / cm 2 .

[0209] 2) Assemble the battery:

[0210] The positive electrode sheet prepared in step 1) was matched with a sodium sheet and a half-cell was assembled using 1M NaClO₄ + EC / PC (1:1, v / v) as the electrolyte. After the cell was allowed to rest for 24 hours, electrochemical testing was performed within the voltage range of 2.0-4.2 V using the same procedure as in Example 1.

[0211] The material can release a specific capacity of 174.6 mAh / g when charged to 4.2 V in the first cycle, and a specific capacity of 162.2 mAh / g when discharged to 2.0 V, with a first-cycle coulombic efficiency of 92.89%.

[0212] Comparative Example 2: Sodium ion battery without sodium supplementation using the sodium supplement of the present invention

[0213] 1) Preparation of battery positive electrode:

[0214] Will Na 0.74 Ni 1 / 4 Fe 1 / 4 Mn 1 / 2 O2 was used as the positive electrode active material, and the positive electrode active material, binder PVDF, and carbon nanotube (CNT) conductive agent were weighed in a weight ratio of 8:1:1. PVDF was first dissolved in NMP, then CNTs were added and dispersed evenly, and finally the above positive electrode active materials were added. After uniform dispersion, the resulting positive electrode slurry was filtered and coated on an aluminum foil current collector. After drying, rolling, and die-cutting, a circular positive electrode sheet with a diameter of 13 mm was obtained, with a loading of approximately 7.5 mg / cm 2 .

[0215] 2) Assemble the battery:

[0216] The positive electrode sheet prepared in step 1) was matched with a sodium sheet, and a half-cell was assembled using 1M NaClO₄ + EC / PC (1:1, v / v) as the electrolyte. After the cell was allowed to rest for 24 hours, electrochemical testing was performed in the voltage range of 2.0-4.3 V according to the same procedure as in Example 1. The initial charge-discharge curve is shown in Figure 6.

[0217] The material can release a specific capacity of 166.2 mAh / g when charged to 4.3 V in the first cycle, and a specific capacity of 153.1 mAh / g when discharged to 2.0 V, with a first-cycle coulombic efficiency of 92.09%.

[0218] The electrochemical test results of Examples 1-7 and Comparative Examples 1-2 are summarized in Table 2 as shown below.

[0219] Table 2 First cycle charge and discharge test results of batteries in Examples 1-7 and Comparative Examples 1-2

[0220] Note:

[0221] * The first cycle coulombic efficiency refers to the coulombic efficiency of the first cycle of battery charge and discharge. The calculation method of coulombic efficiency is as follows:

[0222] The lower the first-cycle coulombic efficiency, the better the sodium replenishment effect. Examples 1-5 verify that the sodium replenisher according to the present invention has excellent sodium replenishment effect. Examples 6-7, compared with Comparative Examples 1-2, verify that the sodium replenisher according to the present invention can significantly improve the sodium replenishment effect of the prior art battery.

[0223] It can be seen that the novel material according to the present invention has excellent effects when applied in the field of sodium supplementation and therefore has high commercial potential.

[0224] Although only sodium supplements are illustrated in the examples, due to the similarity between lithium-ion batteries and sodium-ion batteries, similar technical effects can be achieved by replacing the sodium in the example materials with lithium or adjusting the relative amounts of sodium and lithium in the material of formula (I) of the present invention to apply it to the field of lithium supplementation or to lithium-ion batteries. In addition, by replacing part or all of the sodium in the example materials with one or more elements in Group IA and Group IIA of the long-period periodic table, the present invention can be applied to other batteries, such as potassium ion batteries, rubidium ion batteries, cesium ion batteries, magnesium ion batteries, calcium ion batteries, strontium ion batteries, barium ion batteries, or sodium ion batteries doped with one or more of lithium, potassium, rubidium, cesium, magnesium, calcium, strontium, and barium, to achieve similar technical effects.

[0225] Although many of the numerical values ​​and numerical ranges mentioned in this application are not described with the word "about", it should be understood that these numerical values ​​and numerical ranges, like the numerical values ​​and numerical ranges described with the word "about", can vary within the range of ±5% without departing from the spirit and scope of the present invention.

[0226] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. Although some methods and materials are specifically described herein, similar or equivalent methods and materials as described herein can also be used to implement the present invention although not specifically mentioned in this article. All publications, patent applications, patents and other references mentioned herein are incorporated herein by reference in their entirety. In the event of conflict, the definitions in this application shall prevail. In addition, these materials, methods and examples are merely illustrative and should not be construed as limiting the scope of protection claimed in this application.

[0227] Although this specification contains many details of specific embodiments, these details should not be construed as limitations on the scope of any invention or of what may be claimed, but rather as detailed descriptions of features that may be features of particular embodiments of particular inventions. Certain features described in this specification in the context of separate embodiments may also be implemented in combination in a single embodiment, and various features described in the context of a single embodiment may also be implemented in multiple embodiments, either separately or in any suitable subcombination.

Claims

1. A material having a structure of formula (I): Na 7n-x L x Fe 3n-y M y O 8n-a-b R a Q b (I) in: n is an integer selected from 1 to 10, 0≤x≤7n, 0≤y<3n, 0≤a<8n, 0≤b<8n, L is one or more elements selected from Group IA and IIA elements in the long-period periodic table, M is one or more metal elements selected from Groups IA-VIA, IB-VIIB and VIII in the long-period periodic table, R is one or more elements selected from Group VIIA elements in the long-period periodic table, Q is one or more selected from the elements of Group VIA in the long-period periodic table, and The atomic molar ratio of (Na+L):(Fe+M):(O+R+Q) is 7:3:

8.

2. The material according to claim 1, wherein formula (I) satisfies one or more of the following conditions: 1) n is selected from 1, 2 and 3; 2) x is 0 or 7n; 3)0≤y<3n / 2; 4)0≤a<4n; 5)0≤b<4n; 6) M is one or more selected from lithium, magnesium, aluminum, nickel, boron, scandium, titanium, vanadium, chromium, manganese, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, iridium and tin; 7) L is one or more selected from lithium, potassium, rubidium, cesium, magnesium, calcium, strontium, and barium; 8) R is one or more selected from fluorine, chlorine, bromine, and iodine; and 9) Q is one or more selected from sulfur, selenium and tellurium.

3. The material according to claim 1, which is selected from Na 7n Fe 3n O 8n 、Na 7n Fe 3n-y Ti y O 8n 、Na 7n Fe 3n-y Mn y O 8n 、Na 7n Fe 3n- y Al y O 8n 、Na 7n Fe 3n-y Co y O 8n 、Na 7n Fe 3n-y Cu y O 8n 、Na 7n Fe 3n-y Zn y O 8n 、Na 7n Fe 3n-y Ru y O 8n 、Na 7n Fe 3n-y Y y O 8n 、Na 7n Fe 3n-y B y O 8n 、Na 7n Fe 3n-y Mg y O 8n 、Na 7n Fe 3n-y Zr y O 8n 、Na 7n Fe 3n-y Ni y O 8n 、Na 7n Fe 3n O 8n-a F a or more than one of them, where n is 1 or 2, 0 < y < 3n, and 0 < a < 8n.

4. The material according to claim 1, which is Na7Fe3O8 or Na 14 Fe6O 16 .

5. A method for preparing a material according to any one of claims 1 to 4, the method comprising the following steps: (a) mixing Fe2O3, Na2O and / or an oxide of L, and an optional dopant precursor to obtain a precursor mixture, wherein the stoichiometric ratio between Fe2O3 and the oxide of Na2O and / or L is 1:9-9:1, preferably 1:9-1:1, more preferably 1:6-1:2, wherein L is one or more elements selected from Groups IA and IIA of the long period periodic table; (b) heating the precursor mixture at a temperature of 100-1200° C., preferably 200-800° C., for 1-200 hours, preferably 20-100 hours under an inert atmosphere for high temperature sintering; (c) After cooling, the material is obtained. The method according to claim 5 , wherein the inert atmosphere is at least one selected from nitrogen, argon and helium.

7. The method according to claim 5 or 6, wherein the dopant precursor is one or more selected from the group consisting of oxides of M, sodium fluoride, sodium sulfide, iron fluoride and iron sulfide, wherein M is one or more selected from the group consisting of metal elements in Groups IA-VIA, IB-VIIB and VIII of the long period periodic table; preferably, the dopant precursor is an oxide of M, wherein M is one or more selected from the group consisting of lithium, magnesium, aluminum, nickel, boron, scandium, titanium, vanadium, chromium, manganese, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, iridium and tin.

8. A coated material comprising a core and a coating layer covering the surface of the core, wherein: The core comprises the material of any one of claims 1 to 4; The coating layer comprises one or more materials selected from the group consisting of metal fluorides, metal carbides, metal oxides, polymers, carbon, and combinations thereof; Optionally, there may or may not be a cavity between the coating layer and the core, and optionally, the coating layer is a continuous layer or a discontinuous layer.

9. The coated material according to claim 8, wherein the coating layer comprises one or more of a metal fluoride coating layer, a metal carbide coating layer, and a metal oxide coating layer, wherein the metal elements in the metal fluoride, the metal carbide and the metal oxide are independently selected from nickel, cobalt, aluminum, manganese, lithium, potassium, barium, iron, calcium, copper, zinc, titanium, magnesium, zirconium, strontium, chromium, tin, antimony, tungsten, niobium, molybdenum, vanadium, palladium, bismuth, cesium, hafnium, tantalum, polonium, gallium, indium, thallium, yttrium, scandium, lanthanide elements and combinations thereof; preferably, the coating layer comprises a metal oxide coating layer, wherein the metal elements in the metal oxide are selected from nickel, cobalt, aluminum, manganese, lithium, potassium, barium, iron, calcium, copper, zinc, titanium, magnesium, zirconium and combinations thereof.

10. The coated material according to claim 8 or 9, wherein the coating layer comprises a polymer coating layer, a carbon coating layer and a combination thereof, wherein the polymer comprises one or more selected from the following: polypyrrole polymers and modified products thereof, polythiophene polymers and modified products thereof, polyamide polymers and modified products thereof, polyethylene oxide polymers and modified products thereof, polyvinylidene fluoride polymers and modified products thereof, polyacrylate polymers and modified products thereof, polyacrylonitrile polymers and modified products thereof, polyether polymers and modified products thereof, polysiloxane polymers and modified products thereof or polyanion single ion conductor type polymers and combinations thereof.

11. A composite material comprising a first material and a second material, wherein: The first material comprises the material according to any one of claims 1 to 4; The second material is a battery active material different from the first material.

12. The composite material according to claim 11, wherein the second material is at least one sodium-containing cathode active material selected from Prussian blue, polyanionic compounds, transition metal layered oxides, and sodium-containing organic compounds; preferably, the second material is selected from Na(Ni x’ Fe y’ Mn 1-x’-y’ )O2, Na 0.74 (Ni x’ Fe y’ Mn 1-x’-y’ )O2, Na 0.67 (Ni x’ Mn y’ Ti 1-x’-y’ )O2, Na 0.67 (Ni x’ Mn y’ Zn z’ Cu 1-x’-y’-z’ )O2, Na2M’[Fe(CN)6], NaVPO4F, Na2FePO4F, Na3V2(PO4)3, Na2Fe2(SO4)3, NaTiO2, NaMnO2, NaFeO2, NaCoO2, NaNiO2, Na2C6O6, and combinations thereof, where 0 < x’ < 1, 0 < y’ < 1, 0 < z’ < 1, and M’ is selected from Fe, Co, Mn, Ni, Cu, and combinations thereof; more preferably, the second material is selected from NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2, Na 0.74 Ni 1 / 4 Fe 1 / 4 Mn 1 / 2 O2, and combinations thereof. 13 . The composite material according to claim 11 , wherein the weight ratio of the first material to the second material is 1:30 to 30:

1.

14. The composite material according to claim 11 or 12, wherein the first material further comprises one or more additional materials selected from the following: NaN3, Na2O, Na2O2, Na2C2O4, Na2CO3, Na3C6H5O7, Na2C2O2N2, Na2C2N4, Na2C4H5NO4, Na3C7H8NO6 and combinations thereof.

15. A method for preparing a composite material according to any one of claims 11 to 14, the method comprising the step of compounding a first material and a second material in the form of mixing and / or coating, wherein the mixing preferably comprises the step of mixing the first material and the second material by stirring and / or grinding, and the coating preferably comprises the step of attaching the second material to the outside of the first material.

16. A positive electrode active material comprising one or more of the material according to any one of claims 1 to 4, the coated material according to any one of claims 8 to 10, the composite material according to any one of claims 11 to 14, and a combination thereof. 17 . A positive electrode for a battery, comprising the positive electrode active material according to claim 16 , an optional conductive agent, and an optional binder.

18. The positive electrode of a battery according to claim 17, wherein the binder is selected from at least one of polyvinylidene fluoride, polyvinylidene chloride, polytetrafluoroethylene, polyethylene oxide, polyvinylidene chloride-hexafluoropropylene, polyacrylic acid, polyacrylonitrile, polyacrylamide, polyamide, polyamideimide, polymethyl methacrylate, polycarbonate, carboxymethyl cellulose, sodium carboxymethyl cellulose, styrene-butadiene copolymer, sodium alginate, styrene-butadiene rubber and combinations thereof, and preferably the amount of the binder is 0.5-10 wt % based on the total weight of the positive electrode of the battery; and / or the conductive agent is selected from at least one of carbon black, acetylene black, Ketjen black, conductive graphite, carbon fiber, carbon nanotubes, graphene, graphene oxide, reduced graphene oxide and combinations thereof, and preferably the amount of the conductive agent is 0.5-10 wt % based on the total weight of the positive electrode of the battery.

19. An electrode sheet, comprising one or more of the material described in any one of claims 1 to 4, the coated material described in any one of claims 8 to 10, the composite material described in any one of claims 11 to 14, and a combination thereof, and a conductive substance; the electrode sheet preferably comprises a coating, and the coating comprises one or more of the material described in any one of claims 1 to 4, the coated material described in any one of claims 8 to 10, the composite material described in any one of claims 11 to 14, and a combination thereof.

20. A diaphragm comprising one or more of the material described in any one of claims 1 to 4, the coated material described in any one of claims 8 to 10, the composite material described in any one of claims 11 to 14, and combinations thereof, and a polymer material; the diaphragm preferably comprises a coating, and the coating comprises one or more of the material described in any one of claims 1 to 4, the coated material described in any one of claims 8 to 10, the composite material described in any one of claims 11 to 14, and combinations thereof.

21. An electrochemical device comprising at least one of the positive electrode active material according to claim 16, the battery positive electrode according to any one of claims 17-18, the electrode sheet or separator according to claim 19, and a combination thereof.

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