Positive electrode material, positive electrode sheet, electrochemical energy storage battery and preparation method

Abstract

A positive electrode material, a positive electrode sheet, an electrochemical energy storage battery and a preparation method for the positive electrode material. The positive electrode material comprises a positive electrode active material aggregate and active ion supplementary materials, and the positive electrode active material aggregate is formed by stacking positive electrode active materials; the active ion supplementary materials are at least located in a plurality of gaps of the positive electrode active material aggregate, and the active ion supplementary materials are bonded to the positive electrode active materials.

Description

Positive electrode material, positive electrode sheet, electrochemical energy storage battery and preparation method

[0001] This application claims priority to Chinese patent application No. 202310802486.X filed on June 30, 2023, entitled “Positive Electrode Material, Positive Electrode Sheet, Electrochemical Energy Storage Battery and Preparation Method,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present disclosure relates to the field of electrochemical batteries, and in particular to positive electrode materials, positive electrode sheets, electrochemical energy storage batteries, and preparation methods. Background Art

[0003] Electrochemical energy storage batteries achieve charging and discharging through the mutual conversion of chemical energy and electrical energy. Lithium-ion batteries and sodium-ion batteries are both common types of electrochemical energy storage batteries. Lithium-ion batteries achieve energy storage based on the cyclic flow of lithium ions between the positive and negative electrodes, while sodium-ion batteries achieve energy storage based on the cyclic flow of sodium ions between the positive and negative electrodes. During the charging and discharging operations of lithium-ion and sodium-ion batteries, a solid electrolyte interphase (SEI) will form at the negative electrode. Due to the formation of the SEI and the irreversible capacity loss caused by the initial charge, lithium and sodium ions are excessively consumed. Therefore, in order to improve the irreversible capacity loss of lithium-ion and sodium-ion batteries and improve the initial charge and discharge efficiency, lithium and sodium supplementation is usually performed in the battery.

[0004] For lithium-ion batteries, the relevant technology mixes lithium-supplementing materials with lithium-based positive electrode active materials and uses them to prepare positive electrode slurry, and uses the lithium-supplementing materials to compensate for the above-mentioned irreversible capacity loss. For sodium-ion batteries, the relevant technology mixes sodium-supplementing materials with sodium-based positive electrode active materials and uses them to prepare positive electrode slurry, and uses the sodium-supplementing materials to compensate for the above-mentioned irreversible capacity loss.

[0005] However, the currently known lithium-supplementing materials and sodium-supplementing materials have poor stability in the air, making them extremely easy to deteriorate. In addition, the residues formed by the lithium-supplementing materials and sodium-supplementing materials after releasing active ions dissolve in the electrolyte and easily produce side reactions, which is not conducive to improving battery performance.

[0006] Public content

[0007] In view of this, the present disclosure provides a positive electrode material, a positive electrode sheet, an electrochemical energy storage battery and a preparation method, which can solve the technical problems in the related art.

[0008] Specifically, the following technical solutions are included:

[0009] In one aspect, the present disclosure provides a positive electrode material, comprising a positive electrode active material agglomerate and an active ion supplement material, wherein the positive electrode active material agglomerate is formed by stacking the positive electrode active material;

[0010] The active ion supplement material is located at least in a plurality of gaps in the positive electrode active material aggregates, and the active ion supplement material is bound to the positive electrode active material.

[0011] The positive electrode material provided by the embodiment of the present disclosure makes the active ion supplement material located in the multiple gaps of the positive electrode active material agglomerate, and the active ion supplement material is combined with the positive electrode active material, so that the active ion supplement material is stably embedded in the interior of the positive electrode active material agglomerate without the occurrence of undesirable shedding phenomenon. The positive electrode material provided by the embodiment of the present disclosure has at least the following advantages: First, the active ion supplement material is located in the multiple gaps of the positive electrode active material agglomerate, which can reduce the contact of the active ion supplement material with air (such as water, carbon dioxide, oxygen, etc.), improve the moisture resistance of the positive electrode material, and prevent it from deteriorating. Second, this can reduce the contact between the residue formed by the active ion supplement material after releasing the active ions and the electrolyte, thereby reducing side reactions. Third, this can reduce the direct contact between the active ion supplement material and the battery slurry, reduce the residual alkali on its surface and the adverse effects on the binder, etc., and increase the stability of the slurry. Fourth, the active ion supplement material is embedded in the multiple voids of the positive electrode active material aggregates in granular form. This increases its contact area with the positive electrode active material, reduces the decomposition potential, and facilitates the complete release of the required capacity in one go. Fifth, the structural units of the positive electrode active material aggregates are stacked and in contact with each other, resulting in a dispersed void space. After the active ion supplement material decomposes and releases active ions, the vacancies left in the positive electrode active material aggregates are also dispersed. This not only does not affect the structural stability of the positive electrode active material aggregates, but also helps to slowly release structural stress and improve the cycling stability of the positive electrode material. Sixth, this positive electrode material can be directly used to prepare positive electrode sheets, which helps to simplify the battery manufacturing process.

[0012] In some possible implementations, the average particle size of the positive electrode material is 2 μm-20 μm, and the average particle size of the active ion supplement material is 10 nm-2000 nm.

[0013] The positive electrode material's average particle size within the aforementioned range can provide high rate capability and compaction density, while effectively avoiding electrolyte side reactions. The active ion supplement material's average particle size within the aforementioned range can effectively increase the total contact area between the active ion supplement material and the positive electrode material, which helps reduce the decomposition potential and facilitates the complete release of the required capacity in one go.

[0014] In some possible implementation manners, based on 100 parts by weight of the positive electrode material, the weight of the active ion supplement material is 1 part - 10 parts.

[0015] In some possible implementation manners, the density of the positive electrode material is greater than 90%.

[0016] The higher the density of the positive electrode material, the more the amount of the active ion supplement material it can carry, and the better the compensation effect on the irreversible capacity loss of the positive electrode material.

[0017] In some possible implementation manners, between different particles of the positive electrode active material, and between the positive electrode active material and the active ion supplement material, there are carbon单质 and / or carbon compounds, which are used to provide chemical binding force, which can ensure the structural stability of the positive electrode active material agglomerates, and ensure that the active ion supplement material is stably embedded inside the positive electrode active material agglomerates.

[0018] In some possible implementation manners, the mass ratio of the active ion supplement material located in multiple voids of the positive electrode active material agglomerates to the total mass of the active ion supplement material is greater than or equal to 90%.

[0019] In some possible implementation manners, the positive electrode active material agglomerates are formed by stacking lithium-based positive electrode active material phases, and the active ion supplement material is a lithium supplement material.

[0020] In some possible implementation manners, the lithium-based positive electrode active material is selected from at least one of lithium iron phosphate, lithium iron manganese phosphate, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, and lithium-rich layered oxide;

[0021] The lithium supplement material is selected from Li3N, LiF, Li2O 2、 Li2O, Li x M [[ID=2,6]] y O z and at least one of them, where 0 < x ≤ 6, 0 < y ≤ 4, 0 ≤ z ≤ 5, and M is selected from at least one of C, S, Si, Fe, Al, Co, Mn, Zn, Ni, Sb, Te, Ti. [[ID=3|1]]

[0022] In some possible implementation manners, the positive electrode active material agglomerates are formed by stacking sodium-based positive electrode active material phases, and the active ion supplement material is a sodium supplement material.

[0023] In some possible implementation manners, the sodium-based positive electrode active material is selected from at least one of sodium vanadium phosphate, sodium fluorovanadate phosphate, sodium manganese phosphate, sodium iron phosphate, sodium cobalt oxide, sodium manganese oxide, sodium nickel oxide, sodium vanadate, and sodium nickel iron manganese phosphate;

[0024] The sodium supplement material is selected from at least one of Na3N, NaF, Na2O2, Na2O, Na x M y O z where 0 < x ≤ 6, 0 < y ≤ 4, 0 ≤ z ≤ 5, and M is selected from at least one of C, S, Si, Fe, Al, Co, Mn, Zn, Ni, Sb, Te, Ti.

[0025] In some possible implementation manners, the positive electrode material further includes a coating layer, the coating layer is coated on the outside of the positive electrode active material agglomerates, and the coating layer is used to enhance the structural stability of the positive electrode material and reduce the surface area so as to reduce side reactions.

[0026] On the other hand, a positive electrode plate is provided, and the positive electrode plate includes the positive electrode material described in any one of the above.

[0027] The positive electrode plate provided by the embodiments of the present disclosure has all the advantages of the positive electrode material involved above. Exemplarily, the positive electrode plate includes: a positive electrode material layer and a current collector, the positive electrode material layer is located on at least one surface of the current collector, for example, on two opposite surfaces of the current collector, and the positive electrode material layer is prepared by using the above positive electrode material.

[0028] On yet another hand, an electrochemical energy storage battery is provided, and the electrochemical energy storage battery includes a positive electrode plate as described above.

[0029] The electrochemical energy storage battery provided by the embodiments of the present disclosure has all the advantages of the positive electrode material involved above. Based on the use of the above positive electrode material, it can supplement the lost active ions for the electrochemical energy storage battery, effectively improve its initial discharge efficiency and cycle life, and significantly improve its electrochemical performance.

[0030] In some possible implementation manners, the electrochemical energy storage battery includes a lithium ion battery and a sodium ion battery.

[0031] On yet another aspect, a preparation method of a positive electrode material is provided, and the positive electrode material is as described in any one of the above;

[0032] The preparation method of the positive electrode material includes:

[0033] uniformly mixing a positive electrode active material, an active ion supplement material, an organic binder and a solvent to form a raw material liquid;

[0034] spray drying the raw material liquid under an inert atmosphere to obtain granular intermediates;

[0035] calcining the granular intermediates under an inert atmosphere to obtain the positive electrode material.

[0036] The method for preparing the positive electrode material provided by the embodiments of the present disclosure has at least the following advantages: first, the operation steps are simpler, the controllability is strong, and it is convenient for industrial batch production; second, the active ion supplement material will not produce side reactions during the preparation process, thereby ensuring the performance and quality of the positive electrode material and avoiding post-processing; third, multiple types of active ion supplement materials can be used at the same time, making the active ion supplement material more versatile; fourth, the requirements for the particle size of the active ion supplement material and the active material of the positive electrode material are wider, making the preparation method more fault-tolerant.

[0037] In some possible implementations, the solid content of the raw material liquid is 10%-50%, and the viscosity is 1000 cP-5000 cP.

[0038] In some possible implementations, the spray drying operating parameters meet at least one of the following parameters: inlet air temperature is 150°C-200°C, outlet air temperature is 90°C-120°C, peristaltic pump speed is 100ml / h-1000ml / h, and nozzle diameter is 0.5mm-2mm.

[0039] By limiting the parameters of the raw material liquid and spray drying as described above, the spray granulation effect can be improved so that the particle size of the granular intermediate is within the desired range.

[0040] In some possible implementations, the operating parameters of the calcination process meet at least one of the following parameters: a calcination temperature of 400° C. to 700° C., and a calcination time of 6 hours to 12 hours.

[0041] The purpose of the calcination treatment is to sinter and carbonize the organic binder to form a carbon layer without damaging the structures of the active ion supplement material and the positive electrode active material, so that both maintain their original structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] FIG1 is a schematic structural diagram of an exemplary positive electrode material provided in an embodiment of the present disclosure;

[0043] FIG2 is a schematic structural diagram of an exemplary electrochemical energy storage battery provided by an embodiment of the present disclosure;

[0044] FIG3 is a surface SEM image of the positive electrode material provided in Example 2;

[0045] FIG4 is a cross-sectional SEM image of the positive electrode material provided in Example 2;

[0046] FIG5 is an EDS spectrum of a cross section of the positive electrode material provided in Example 2;

[0047] FIG6 is an EDS distribution diagram of cobalt element in the positive electrode material provided in Example 2;

[0048] FIG7 is an EDS distribution diagram of the iron element in the positive electrode material provided in Example 2.

[0049] The reference numerals represent:

[0050] 001. Agglomerate of positive electrode active material; 002. Active ion supplement material; 003. Positive electrode active material; 100. Positive electrode sheet; 200. Negative electrode sheet; 300. Negative electrode sheet; 400. Negative electrode sheet; 500. Encapsulation layer. DETAILED DESCRIPTION

[0051] The following will clearly and completely describe the technical solutions in the embodiments of the present disclosure in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present disclosure without making any creative efforts shall fall within the scope of protection of the present disclosure.

[0052] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the appended claims.

[0053] In the description of this disclosure, it should be understood that the terms "inside" and "outside" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in FIG1 , and are intended solely to facilitate the description of this disclosure and simplify the description. They are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting this disclosure. For example, these orientation terms are generally based on the relative orientations shown in FIG1 , and are used solely to more clearly describe the relationships between structures, and are not intended to describe absolute orientations.

[0054] Lithium-ion batteries and sodium-ion batteries are both electrochemical energy storage batteries, and they both consist of a positive electrode, a negative electrode, an electrolyte, a diaphragm, and corresponding circuits. Among them, lithium-ion batteries achieve energy storage and release by the intercalation and deintercalation of lithium ions between the positive and negative electrodes, and sodium-ion batteries achieve energy storage and release by the intercalation and deintercalation of sodium ions between the positive and negative electrodes. The electrolyte is a carrier for the transmission of lithium ions or sodium ions between the positive and negative electrodes. The diaphragm is ion conductive but electronically insulating. It can ensure the migration of lithium ions or sodium ions while separating the positive and negative electrodes to prevent short circuits. The positive electrode and negative electrode rely on the positive electrode material and negative electrode material respectively to perform energy storage functions.

[0055] During charge and discharge, a solid electrolyte interface film (SEL) forms at the negative electrode of lithium-ion and sodium-ion batteries. This SEL formation and the irreversible capacity loss caused by the initial charge result in excessive consumption of lithium and sodium ions. Currently, lithium and sodium replenishment materials are commonly used to compensate for the loss of active lithium and sodium in the battery.

[0056] For lithium-ion batteries, the relevant technology mixes lithium-supplementing materials with lithium-based positive electrode active materials to form positive electrode materials, and uses the positive electrode materials to prepare positive electrode slurry, and uses the lithium-supplementing materials to compensate for the above-mentioned irreversible capacity loss. For sodium-ion batteries, the relevant technology mixes sodium-supplementing materials with sodium-based positive electrode active materials to form positive electrode materials, and uses the positive electrode materials to prepare positive electrode slurry, and uses the sodium-supplementing materials to compensate for the irreversible capacity loss in the initial cycle.

[0057] However, the currently known lithium-supplementing materials and sodium-supplementing materials have poor stability in the air, making them extremely easy to deteriorate. In addition, the residues formed by the lithium-supplementing materials and sodium-supplementing materials after releasing active ions dissolve in the electrolyte and easily produce side reactions, which is not conducive to improving battery performance.

[0058] In response to the technical problems existing in the related technologies, on the one hand, an embodiment of the present disclosure provides a positive electrode material. FIG1 illustrates the structure of a positive electrode material. As shown in FIG1 , the positive electrode material includes a positive electrode active material agglomerate 001 and an active ion supplement material 002. The positive electrode active material agglomerate 001 is formed by the accumulation of positive electrode active materials 003; the active ion supplement material 002 is at least located in the gaps of the positive electrode active material agglomerate 001, and the active ion supplement material 002 is bonded to the positive electrode active material 003.

[0059] The positive electrode active material exists in the form of particles, and the positive electrode active material agglomerates are formed by stacking a plurality of positive electrode active material particles, thereby forming a plurality of dispersed voids.

[0060] The positive electrode material provided by the embodiment of the present disclosure makes the active ion supplement material located in the multiple gaps of the positive electrode active material agglomerate, and the active ion supplement material is combined with the positive electrode active material, so that the active ion supplement material is stably embedded in the interior of the positive electrode active material agglomerate without the occurrence of undesirable shedding phenomenon. The positive electrode material provided by the embodiment of the present disclosure has at least the following advantages: First, the active ion supplement material is located in the multiple gaps of the positive electrode active material agglomerate, which can reduce the contact of the active ion supplement material with air (such as water, carbon dioxide, oxygen, etc.), improve the moisture resistance of the positive electrode material, and prevent it from deteriorating. Second, this can reduce the contact between the residue formed by the active ion supplement material after releasing the active ions and the electrolyte, thereby reducing side reactions. Third, this can reduce the direct contact between the active ion supplement material and the battery slurry, reduce the residual alkali on its surface and the adverse effects on the binder, etc., and increase the stability of the slurry. Fourth, the active ion supplement material is embedded in the multiple voids of the positive electrode active material aggregates in granular form. This increases its contact area with the positive electrode active material, reduces the decomposition potential, and facilitates the complete release of the required capacity in one go. Fifth, the structural units of the positive electrode active material aggregates are stacked and in contact with each other, resulting in a dispersed void space. After the active ion supplement material decomposes and releases active ions, the vacancies left in the positive electrode active material aggregates are also dispersed. This not only does not affect the structural stability of the positive electrode active material aggregates, but also helps to slowly release structural stress and improve the cycling stability of the positive electrode material. Sixth, this positive electrode material can be directly used to prepare positive electrode sheets, which helps to simplify the battery manufacturing process.

[0061] The positive electrode material provided in the embodiment of the present disclosure is a composite positive electrode material pre-installed with an active ion supplement material. The positive electrode material is also in a granular form, including spherical particles and quasi-spherical particles.

[0062] Exemplarily, the average particle size of the positive electrode material (which can also be understood as the median particle size D50) is 2um-20um, for example, this includes but is not limited to: 3um, 4um, 5um, 6um, 7um, 8um, 9um, 10um, 11um, 12000nm, 13um, 14um, 15um, 16um, 17m, 18um, 19um, 20um, etc.

[0063] The average particle size of the positive electrode material is within the above range, which can provide higher rate performance and compaction density and effectively avoid electrolyte side reactions.

[0064] Furthermore, the active ion supplement material is also in a granular form, which can be embedded in the positive electrode active material agglomerate in the form of primary particles, or in the form of secondary particles. Exemplarily, the average particle size of the active ion supplement material (which can also be understood as the median particle size D50) is 10nm-2000nm, which includes but is not limited to: 10nm, 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm, 750nm, 800nm, 850nm , 900nm, 950nm, 1000nm, 1050nm, 1100nm, 1150nm, 1200nm, 1250nm, 1300nm, 1350nm, 1400nm, 1450nm, 1500nm, 1550nm, 1600nm, 1650nm, 1700nm, 1750nm, 1800nm, 1850nm, 1900nm, 1950nm, 2000nm, etc.

[0065] In some examples, the average particle size of the positive electrode material can be at least 10 times the average particle size of the active ion supplement material. For example, the average particle size of the positive electrode material is 100-2000 times the average particle size of the active ion supplement material, further can be 200-1000 times, further can be 300-1000 times.

[0066] By making the average particle size of the active ion supplement material within the above range, its particle size is small enough, so that the active ion supplement material contained in the positive electrode material can fully contact the positive electrode material, thereby effectively increasing the total contact area between the active ion supplement material and the positive electrode material, which is conducive to reducing the decomposition potential and facilitating the one-time release of the required capacity.

[0067] For the positive electrode material provided in the embodiment of the present disclosure, the particle size range of the active ion supplement material contained therein can be designed to be relatively wide, and the particle size range of the positive electrode active material can also be designed to be relatively wide, which is conducive to improving the versatility of the positive electrode material.

[0068] For the positive electrode material provided in the embodiment of the present disclosure, the type of active ion supplement material contained therein can be a single one or multiple types, such as two, three, four or more, so that it has multiple active ion supplement materials at the same time, which is also conducive to improving the versatility of the positive electrode material.

[0069] For the mass ratio of active ion supplement material to positive electrode active material, please refer to the following: based on 100 parts by weight of positive electrode material, the weight of active ion supplement material is 1 part to 10 parts, that is, the mass percentage of active ion supplement material in positive electrode material is 1% to 10%, which includes but is not limited to 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, etc.

[0070] The mass percentage of the active ion supplement material is within the above range, ensuring that sufficient active ions are accommodated in the multiple gaps of the positive electrode active material agglomerates, thereby improving the energy density and cycle life of the positive electrode material.

[0071] The positive electrode material involved in the embodiment of the present disclosure has a binding force between the active ion supplement material and the positive electrode active material, so that the two are stably combined. The binding force includes a chemical binding force provided by a chemical bond, and further, it can also include a physical binding force provided by a physical bond, and the physical bond can be a van der Waals bond.

[0072] Regarding the chemical bonding force provided by chemical bonds, for example, carbon elements and / or carbon compounds are present between different particles of the positive electrode active material, and between the positive electrode active material and the active ion supplement material, and the carbon elements and / or carbon compounds are used to provide chemical bonding force.

[0073] The chemical bond can be a covalent bond formed between the carbon element and other elements in the active ion supplement material and the positive electrode active material. That is, a carbon element and / or a carbon compound exists at the contact interface between the active ion supplement material and the positive electrode active material, and their structural form can be at least one of a layer, a block, and a discrete point. The carbon element and / or the carbon compound existing between the active ion supplement material and the positive electrode active material can be a continuous structure or a discontinuous structure. The carbon element and / or the carbon compound not only enables stable bonding and contact between the active ion supplement material and the positive electrode active material, but also helps to enhance the activity of the positive electrode active material, thereby significantly improving the electrochemical performance of the positive electrode material.

[0074] In the embodiment of the present disclosure, the mass percentage of carbon element and / or carbon compound in the positive electrode material is 1%-10%. The mass percentage of carbon element and / or carbon compound within the above range can not only achieve full combination of all active ion supplement materials and positive electrode active materials, but also has the effect of improving the electrochemical performance of the positive electrode material.

[0075] The term "and / or" in the embodiments of the present disclosure is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent three situations: A exists alone, A and B exist at the same time, and B exists alone.

[0076] The positive electrode active material aggregates are formed by stacking the positive electrode active material phase, resulting in multiple gaps, or vacancies, within the positive electrode active material aggregates. These vacancies are occupied by the active ion supplementary material, thereby forming a composite material positive electrode material. It is desirable that the positive electrode material of the disclosed embodiments have a density greater than 90%, that is, a porosity less than 10%.

[0077] Illustratively, the density of the positive electrode material is greater than or equal to 95%, further, the density of the positive electrode material is greater than or equal to 96%, further greater than or equal to 97%, further greater than or equal to 98%, further greater than or equal to 99%, further equal to 100%.

[0078] The higher the density of the positive electrode material, the more it can carry active ion supplementary materials, and the better the effect of compensating for the irreversible capacity loss of the positive electrode material.

[0079] The disclosed embodiments desirably locate the active ion supplementing material within the multiple voids of the positive electrode active material aggregates, i.e., within the interior of the positive electrode active material aggregates. This is particularly advantageous for reducing contact between the active ion supplementing material and air, electrolyte, slurry, etc. However, considering that during the preparation process, it is not ruled out that some active ion supplementing material may be bound to the outer surface of the positive electrode active material aggregates.

[0080] Exemplarily, the mass ratio of the mass of the active ion supplement material located in the multiple voids of the positive electrode active material agglomerates to the total mass of the active ion supplement material is greater than or equal to 90%, for example, this includes but is not limited to greater than or equal to 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%. Furthermore, the mass ratio of the mass of the active ion supplement material located in the multiple voids of the positive electrode active material agglomerates to the total mass of the active ion supplement material can be 100%.

[0081] In some examples (1), the positive electrode material is a lithium-based positive electrode material, which can be used in lithium-ion batteries. Accordingly, the positive electrode active material agglomerates involved in the positive electrode material are formed by stacking lithium-based positive electrode active materials, and the active ion supplement material is a lithium supplement material.

[0082] Some applicable lithium-based cathode active materials are selected from at least one of lithium iron phosphate, lithium iron manganese phosphate, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, and lithium-rich layered oxides. Among them, the chemical formula of lithium nickel cobalt manganese oxide is LiMO2, where M is a nickel cobalt manganese ternary compound, and the atomic percentages of nickel, cobalt, and manganese elements can be in any ratio. For example, the atomic percentage of nickel is 80%, the atomic percentage of cobalt is 10%, and the atomic percentage of manganese is 10%.

[0083] Some applicable lithium supplement materials are selected from at least one of Li3N, LiF, Li2O 2、 Li2O, Li x M y O z where 0 < x ≤ 6, 0 < y ≤ 4, 0 ≤ z ≤ 5 (x, y, and z respectively represent the number of corresponding atoms), and M is selected from at least one of C, S, Si, Fe, Al, Co, Mn, Zn, Ni, Sb, Te, Ti.

[0084] For Li x M y O z where the value of x includes but is not limited to 1, 2, 3, 4, 5, 6, the value of y includes but is not limited to 1, 2, 3, 4, and z includes but is not limited to 0, 1, 2, 3, 4, 5, etc. For example, Li x M y O z can be Li6CoO4, Li5FeO4, Li2C2O4, etc.

[0085] It can be seen that for the lithium-based cathode material provided by the embodiments of the present disclosure, the types of applicable lithium-based cathode active materials and lithium supplement materials are more extensive and have stronger versatility.

[0086] In some examples (2), the cathode material is a sodium-based cathode material, which can be used in sodium-ion batteries. Correspondingly, the cathode active material agglomerates involved in the cathode material are formed by stacking sodium-based cathode active material phases, and the active ion supplement material is a sodium supplement material.

[0087] Some applicable sodium-based cathode active materials are selected from at least one of sodium vanadium phosphate, sodium fluoro vanadate phosphate, sodium manganese phosphate, sodium iron phosphate, sodium cobalt oxide, sodium manganese oxide, sodium nickel oxide, sodium vanadate, and sodium nickel iron manganese.

[0088] Some applicable sodium supplement materials are selected from at least one of Na3N, NaF, Na2O2, Na2O, Na x M y O zat least one of them, where 0 < x ≤ 6, 0 < y ≤ 4, 0 ≤ z ≤ 5 (x, y, and z respectively represent the number of corresponding atoms), and M is selected from at least one of C, S, Si, Fe, Al, Co, Mn, Zn, Ni, Sb, Te, Ti.

[0089] For Na x M y O z , where the value range of x includes but is not limited to 1, 2, 3, 4, 5, 6, the value range of y includes but is not limited to 1, 2, 3, 4, and z includes but is not limited to 0, 1, 2, 3, 4, 5, etc. For example, Na x M y O z can be Li6CoO4, Na5FeO4, Na2C2O4, etc.

[0090] It can be seen that for the sodium-based cathode material provided by the embodiments of the present disclosure, the types of lithium-based cathode active materials and lithium supplement materials applicable to it are more extensive and have stronger versatility.

[0091] In some implementation manners, the cathode material provided by the embodiments of the present disclosure further includes a coating layer, the coating layer is coated on the outside of the cathode active material agglomerates, and the coating layer is used to enhance the structural stability of the cathode material and reduce the surface area so as to reduce side reactions.

[0092] A coating layer with good mechanical properties can be used to endow it with better toughness and fatigue resistance, so as to alleviate the volume expansion problem of the cathode active material agglomerates and further improve its structural stability.

[0093] Exemplarily, the material of the coating layer includes but is not limited to metal fluorides, metal carbides, metal oxides, polymers, etc.

[0094] Exemplarily, the metal elements involved in the above metal fluorides, metal carbides, and metal oxides include but are not limited to: at least one 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 lanthanide elements.

[0095] The above-mentioned polymers include but are not limited to: at least one of polypyrrole and its modified products, polythiophene and its modified products, polyamide and its modified products, polyethylene oxide and its modified products, polyvinylidene fluoride and its modified products, polyacrylate polymers and their modified products, polyacrylonitrile polymers and their modified products, polyether polymers and their modified products, polysiloxane and its modified products, or polyanionic single-ion conductor type polymers.

[0096] Illustratively, the thickness of the coating layer ranges from 2 nm to 100 nm, including but not limited to 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, etc.

[0097] On the other hand, an embodiment of the present disclosure further provides a positive electrode plate, which includes any one of the positive electrode materials described above.

[0098] The positive electrode sheet provided by the embodiments of the present disclosure has all the advantages of the positive electrode materials mentioned above.

[0099] Illustratively, the positive electrode plate includes: a positive electrode material layer and a current collector. The positive electrode material layer is located on at least one surface of the current collector, for example, on two opposite surfaces of the current collector. The positive electrode material layer is prepared using the above-mentioned positive electrode material.

[0100] Based on the positive electrode material provided in the embodiment of the present disclosure, the embodiment of the present disclosure further provides a positive electrode material system, which includes: any one of the positive electrode materials described above, a binder, and a conductive agent.

[0101] In some examples, the weight percentage of the positive electrode material in the positive electrode material system is 80wt% to 98wt%; the weight percentage of the binder in the positive electrode material system is 1wt% to 15wt%; and the weight percentage of the conductive agent in the positive electrode material system is 1wt% to 15wt%.

[0102] For example, the weight percentage of the positive electrode material in the positive electrode material system includes but is not limited to: 80wt%, 81wt%, 82wt%, 83wt%, 84wt%, 85wt%, 86wt%, 87wt%, 88wt%, 89wt%, 90wt%, 91wt%, 92wt%, 93wt%, 94wt%, 95wt%, 96wt%, 97wt%, 98wt%, etc. The weight percentage of the binder in the positive electrode material system includes but is not limited to: 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, etc. The weight percentage of the conductive agent in the positive electrode material system includes but is not limited to: 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, etc.

[0103] The binder is used to bond the active material, the conductive agent and the current collector. In some examples, the binder is at least one of polyvinylidene fluoride, carboxymethyl cellulose binder, styrene-butadiene rubber binder, polyimide binder, polyacrylic acid binder, polyacrylonitrile binder and polyvinyl alcohol binder.

[0104] Conductive agents are used to improve the electron conductivity of the electrode without providing additional capacity or causing additional chemical reactions. Suitable conductive agents include, but are not limited to, at least one of conductive graphite, conductive carbon black, acetylene black, carbon nanotubes, and graphene. Using these conductive agents can reduce the impedance of the positive electrode and improve rate performance.

[0105] Exemplarily, the preparation method of the positive electrode sheet is as follows:

[0106] The binder is dissolved in a polar solvent to obtain a glue solution; the glue solution is mixed with the positive electrode material and the conductive agent, and stirred evenly to obtain a positive electrode slurry; the positive electrode slurry is coated on at least one surface of the current collector, and sequentially dried and rolled to obtain a positive electrode sheet.

[0107] In order to improve the quality of the positive electrode sheet, the positive electrode slurry can be degassed and screened, and then coated on the surface of the current collector.

[0108] In some examples, the current collector includes, but is not limited to, at least one of copper foil, copper mesh, carbon-coated copper foil, stainless steel foil, and nickel foil.

[0109] In some examples, the polar solvent includes, but is not limited to, at least one of N-methylpyrrolidone, dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, and cyclohexanone.

[0110] On the other hand, an embodiment of the present disclosure further provides an electrochemical energy storage battery, which includes a positive electrode plate, and the positive electrode plate is as described above.

[0111] The electrochemical energy storage battery provided by the embodiments of the present disclosure has all the advantages of the above-mentioned positive electrode materials. Based on the use of the above-mentioned positive electrode materials, the lost active ions of the electrochemical energy storage battery are replenished, which can effectively improve its initial discharge efficiency and cycle life, and significantly improve its electrochemical performance.

[0112] As shown in FIG2 , the electrochemical energy storage battery includes, in addition to the aforementioned positive electrode sheet 100, a negative electrode sheet 200, an electrolyte 300, a separator 400, and an encapsulation layer 500. The electrolyte 300 is filled in the space between the positive electrode sheet 100 and the negative electrode sheet 200, and the separator 400 is located in the electrolyte 300 to separate the positive electrode sheet 100 from the negative electrode sheet 200. The encapsulation layer 500 is used to encapsulate the positive electrode sheet 100, the negative electrode sheet 200, the electrolyte 300, and the separator 400 as a whole.

[0113] Electrochemical energy storage batteries achieve energy storage and release through the intercalation and deintercalation of active ions between the positive electrode sheet 100 and the negative electrode sheet 200. The electrolyte 300 is the carrier for the transmission of active ions between the positive electrode sheet 100 and the negative electrode sheet 200. The diaphragm 400 is ion conductive but electronically insulating. The diaphragm 400 is used to ensure the migration of active ions while separating the positive electrode sheet 100 and the negative electrode sheet 200 to prevent short circuits.

[0114] In some examples, the electrochemical energy storage battery includes a lithium-ion battery or a sodium-ion battery. As one example, the electrochemical energy storage battery is a lithium-ion battery. As another example, the electrochemical energy storage battery is a sodium-ion battery.

[0115] On the other hand, an embodiment of the present disclosure further provides a method for preparing a positive electrode material, wherein the positive electrode material is as described above.

[0116] The preparation method of the positive electrode material comprises:

[0117] Step S1: uniformly mix the positive electrode active material, the active ion supplement material, the organic binder and the solvent to form a raw material solution.

[0118] Step S2: spray-drying the raw material liquid under an inert atmosphere to obtain a granular intermediate.

[0119] Step S3: calcining the granular intermediate under an inert atmosphere to obtain a positive electrode material.

[0120] Step S1 forms a uniformly mixed raw material solution, whereby the active ion supplement material is uniformly dispersed between the positive electrode active materials. The organic binder is used to bind the positive electrode active materials and the active ion supplement material to form particles, and after calcination, forms a carbon layer that binds the active ion supplement material to the positive electrode active materials.

[0121] In step S2, the raw material liquid is spray-dried to achieve granulation to form a granular intermediate. After the spray drying, at least 90% of the solvent will be volatilized.

[0122] The spray drying granulation method offers at least the following advantages: First, it integrates mixing, granulation, and drying functions, enabling the raw material liquid to be granulated in a single step, shortening drying time and improving granulation and drying efficiency. Second, it enables the active ion supplement material to be evenly dispersed throughout the closely packed positive electrode active material aggregates. Third, the average particle size of the resulting positive electrode active material aggregates and active ion supplement material can be more precisely and conveniently controlled.

[0123] In step S3, the granular intermediate is calcined to carbonize the organic binder into a carbon layer, thereby achieving a stable bond between the positive electrode active material and the active ion supplement material. Simultaneously, the solvent and some impurities are further thoroughly removed, thereby preparing the positive electrode material.

[0124] It can be seen that the preparation method of the positive electrode material provided by the embodiment of the present disclosure has at least the following advantages: first, the operation steps are simpler, the controllability is strong, and it is convenient for industrial batch production; second, the active ion supplement material will not produce side reactions during the preparation process, thereby ensuring the performance and quality of the positive electrode material and avoiding post-processing; third, multiple types of active ion supplement materials can be used at the same time, making the general range of active ion supplement materials wider; fourth, the requirements for the particle size of the active ion supplement material and the active material of the positive electrode material are wider, making the preparation method more fault-tolerant.

[0125] The following further explains the above steps and their functions:

[0126] For step S1, the amount of the active ion supplement material and the positive electrode active material can be determined according to their mass ratio. The active ion supplement material and the positive electrode active material with a specific ratio are dispersed in a solvent pre-dispersed with an organic binder, and stirred evenly to obtain a raw material liquid with a uniform texture.

[0127] The solid content of the raw material liquid is 10%-50%, including but not limited to 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, etc. The viscosity of the raw material liquid is 1000 cP-5000 cP, including but not limited to 1000 cP-2000 cP, 1000 cP-3000 cP, 2000 cP-4000 cP, 3000 cP-4000 cP, 3000 cP-5000 cP, etc.

[0128] The solid content mentioned here refers to the ratio of the total mass of the active ion supplement material and the positive electrode active material to the mass of the raw material solution.

[0129] By imposing the above-mentioned limitations on the solid content and viscosity of the raw material liquid, the thickening of the raw material liquid is ensured to facilitate rapid granulation in the subsequent spray drying process. This is also particularly beneficial for controlling the particle size of the formed particles within the desired range, because the embodiment of the present disclosure expects that the average particle size of the final positive electrode material formed is 2um-20um, and the average particle size of the active ion supplement material is 10nm-2000nm.

[0130] The solvent plays a dispersing role here, and it is expected that the solvent is easily volatilized at a certain temperature to avoid residue in the positive electrode material. Some suitable solvents include but are not limited to at least one of N-methylpyrrolidone, ether, dichloromethane, benzene, tetrachloromethane, and chloroform.

[0131] Some suitable organic binders include, but are not limited to, at least one of glucose, polyacrylonitrile, polyvinylidene chloride, polyvinylidene chloride-hexafluoropropylene, polytetrafluoroethylene, polyethylene oxide, polyamide, polyamideimide, polymethyl methacrylate, polycarbonate, carboxymethyl cellulose, styrene-butadiene copolymer, polyacrylonitrile, sodium carboxymethyl cellulose, or styrene-butadiene rubber.

[0132] The content of the organic binder may be such that the solid content and viscosity of the raw material liquid are within the above-specified ranges. For example, the mass percentage of the organic binder in the raw material liquid may be 1%-5%.

[0133] The operating parameters of spray drying can affect the particle size of the granular intermediate, as well as the uniform dispersion effect of the active ion supplement material therein. In the embodiment of the present disclosure, it is expected that the operating parameters of spray drying meet at least one of the following parameters to obtain excellent spray granulation effect: inlet air temperature is 150℃-200℃, outlet air temperature is 90℃-120℃, peristaltic pump speed is 100ml / h-1000ml / h, and nozzle diameter is 0.5mm-2mm.

[0134] For example, air inlet temperatures include, but are not limited to, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, and 200°C. Air outlet temperatures include, but are not limited to, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, and 120°C. Peristaltic pump speeds include, but are not limited to, 100 ml / h, 200 ml / h, 300 ml / h, 400 ml / h, 500 ml / h, 600 ml / h, 700 ml / h, 800 ml / h, 900 ml / h, and 1000 ml / h. The nozzle diameter includes but is not limited to: 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, etc.

[0135] By limiting the spray drying operating parameters as above, the active ion supplement material in the granular intermediate is uniformly dispersed in multiple gaps of the positive electrode active material agglomerates, and the average particle size of the granular intermediate is 2um-20um, and the average particle size of the active ion supplement material is 10nm-2000nm.

[0136] In the disclosed embodiments, the purpose of the calcination process is to sinter and carbonize the organic binder to form a carbon layer without damaging the structures of the active ion supplement material and the positive electrode active material, maintaining their original structures. To this end, the calcination process parameters meet at least one of the following parameters: a calcination temperature of 400°C to 700°C and a calcination time of 6 to 12 hours.

[0137] For example, the calcination temperature includes but is not limited to 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, etc.; the calcination time includes but is not limited to 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, etc.

[0138] The spray drying and calcination treatments are both performed under an inert atmosphere. For example, the inert atmosphere may be a nitrogen atmosphere, an argon atmosphere, or the like.

[0139] Furthermore, the method for preparing the positive electrode material provided in the embodiment of the present disclosure may further include screening the particles of the prepared positive electrode material to collect the positive electrode material with a particle size within a desired range.

[0140] The present disclosure will be further described below through more specific examples. Although some specific embodiments are described below, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the examples set forth herein. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in the art or in accordance with the product instructions are used. Where the manufacturer of the reagents or instruments is not specified, they may be conventional products that can be obtained commercially.

[0141] Example 1

[0142] This embodiment 1 provides a lithium-based positive electrode material, a 1# positive electrode plate prepared based on the lithium-based positive electrode material, and a 1# lithium-ion battery obtained based on the 1# positive electrode plate.

[0143] This lithium-based positive electrode material includes a positive electrode active material aggregate and an active ion supplement material. The positive electrode active material aggregate is formed by the accumulation of lithium iron phosphate (LiFePO4), the positive electrode active material. The active ion supplement material is Li6CoO4, which is located at least within the multiple voids of the positive electrode active material aggregate. The active ion supplement material and the positive electrode active material are chemically bonded by a carbon layer. The average particle size of the positive electrode material is 2-20 μm, and the average particle size of the active ion supplement material is 500-1000 nm. The mass ratio of the active ion supplement material located within the multiple voids of the positive electrode active material aggregate to the total mass of the active ion supplement material is greater than 95%.

[0144] The preparation method of the positive electrode material is as follows: 10g of polyacrylonitrile is dispersed in 200mL of N-methylpyrrolidone in advance, and then 95g of lithium iron phosphate (LiFePO4, D50 is 0.9um) and 5g of Li6CoO4 (D50 is 1um) are added thereto, and stirred and mixed at room temperature for 20min to form a raw material solution with a solid content of 10%. Under an argon atmosphere, the raw material solution is spray-dried to obtain a granular intermediate, wherein the spray drying temperature is 160°C. Under an argon atmosphere, the granular intermediate is calcined to obtain a positive electrode material. The calcination temperature is 650°C and the calcination time is 8 hours. After the calcination treatment, the temperature is naturally lowered to obtain the lithium-based positive electrode material of Example 1, which is a LiFePO4@Li6CoO4 composite material.

[0145] The preparation method of the 1# positive electrode plate is as follows: 48g of the above-mentioned lithium-based positive electrode material is mechanically mixed with 0.5g of carbon nanotubes and 1.5g of polyvinylidene fluoride, and then N-methylpyrrolidone is added as a solvent to prepare a slurry with a solid content of 65wt% and stirred evenly to obtain a uniform positive electrode slurry. The positive electrode slurry is coated on a 10μm thick aluminum foil current collector, dried at 90°C, and rolled to obtain a single-sided coated 1# positive electrode plate. The 1# positive electrode plate has a compaction density of 2.3g / cc and an active material loading of 22mg / cm 2 .

[0146] The 1# lithium-ion battery is a half-cell. The preparation method of the 1# lithium-ion battery is as follows: a 1# positive electrode sheet, a separator (Celgard 2400), and a lithium sheet are placed in a button battery in order, an electrolyte (a mixed solution of ethylene carbonate (EC) and diethyl carbonate (EMC) (v / v=1:1) containing 1 mol / L LiPF6, and fluoroethylene carbonate (FEC), with the added amount of FEC being 10wt%) is injected, the button battery is encapsulated, and the battery is left to stand for 12 hours to obtain the 1# lithium-ion battery.

[0147] Example 2-Example 8

[0148] Examples 2 to 6 provide corresponding lithium-based positive electrode materials, positive electrode sheets prepared based on the corresponding lithium-based positive electrode materials, and lithium-ion batteries obtained based on the corresponding positive electrode sheets, wherein all of these lithium-ion batteries are in the form of half-cells. Examples 7 and 8 provide corresponding sodium-based positive electrode materials, positive electrode sheets prepared based on the corresponding sodium-based positive electrode materials, and sodium-ion batteries obtained based on the corresponding positive electrode sheets, wherein all of these sodium-ion batteries are in the form of half-cells.

[0149] Examples 2-6 are essentially the same as Example 1 in terms of the preparation methods for the lithium-based positive electrode material, positive electrode sheet, and lithium-ion battery, except that the types of positive electrode active material and active ion supplement material are different, and the ratios of the two are different. Furthermore, Examples 7-8 are essentially the same as Example 1 in terms of the preparation methods for the lithium-based positive electrode material, positive electrode sheet, and lithium-ion battery, except that: (1) the types of positive electrode active material and active ion supplement material are different, and the ratios of the two are different. (2) Sodium sheet is used.

[0150] For the differences mentioned above, see Table 1.

[0151] Table 1

[0152] Among them, NMC811 mentioned in Table 1 is LiNi 0.8 Mn 0.1 Co0.1 O2, which is a nickel-rich layered oxide.

[0153] Comparative Example 1

[0154] Comparative Example 1 provides corresponding lithium-based positive electrode materials, positive electrode sheets prepared based on the corresponding lithium-based positive electrode materials, and lithium-ion batteries obtained based on the corresponding positive electrode sheets.

[0155] Compared with Example 1, Comparative Example 1 differs in that no lithium supplement material is added to the positive electrode plate, and the rest is the same as Example 1.

[0156] Comparative Example 2-Comparative Example 6

[0157] Compared with Example 1, Comparative Example 2 differs in that the positive electrode active material and the active ion supplement material in the positive electrode plate are mixed in a conventional manner, and the rest are the same as Example 1.

[0158] The preparation method of the positive electrode sheet in the comparative example is as follows:

[0159] 45.6g of LiFePO4, 2.4g of Li6CoO4, 0.5g of carbon nanotubes, and 1.5g of polyvinylidene fluoride were mechanically mixed, and then N-methylpyrrolidone was added as a solvent to prepare a slurry with a solid content of 65wt%. The mixture was stirred evenly to obtain a uniform positive electrode slurry. The positive electrode slurry was coated on a 10μm thick aluminum foil current collector, dried at 90°C, and rolled to obtain a single-sided coated positive electrode sheet. The density of the positive electrode sheet was 2.3g / cc, and the active material loading was 22mg / cm 2 .

[0160] Compared with Example 3, Comparative Example 3 differs in that the positive electrode active material and the lithium supplement material in the positive electrode plate are mixed in a conventional manner, and the rest are the same as Example 1. On this basis, the preparation method of the positive electrode plate can refer to Comparative Example 2.

[0161] The difference between Comparative Example 4 and Example 5 is that the positive electrode active material and the lithium supplement material in the positive electrode plate are mixed in a conventional manner, and the rest are the same as Example 1. On this basis, the preparation method of the positive electrode plate can refer to Comparative Example 2.

[0162] The difference between Comparative Example 5 and Example 7 is that the positive electrode active material and the lithium supplement material in the positive electrode plate are mixed in a conventional manner, and the rest are the same as Example 1. On this basis, the preparation method of the positive electrode plate can refer to Comparative Example 2.

[0163] The difference between Comparative Example 6 and Example 8 is that the positive electrode active material and the lithium supplement material in the positive electrode plate are mixed in a conventional manner, and the rest are the same as Example 1. On this basis, the preparation method of the positive electrode plate can refer to Comparative Example 2.

[0164] For the above-mentioned differences, please refer to Table 2.

[0165] Table 2

[0166] Test Example 1

[0167] This Test Example 1 tests the element distribution, structural morphology, and distribution of the positive electrode active material and active ion supplement material in the positive electrode material provided in Example 2. For element distribution, see Table 3, which is shown below.

[0168] Table 3

[0169] The surface morphology of the positive electrode material of Example 2 is shown in Figure 3 , the cross-sectional morphology of the positive electrode material of Example 2 is shown in Figure 4 , and the EDS (Energy Dispersive Spectroscopy) spectrum of the positive electrode material of Example 2 is shown in Figure 5 . The distribution of the cobalt (Co) element in the positive electrode material of Example 2 is shown in Figure 6 . The distribution of the cobalt (Co) element represents the distribution of the active ion supplement material, wherein the cobalt (Co) element is the off-white particles in Figure 6 ; the distribution of the iron (Fe) element in the positive electrode material of Example 2 is shown in Figure 7 . The distribution of the iron (Fe) element represents the distribution of the positive electrode active material, wherein the iron (Fe) element is indicated by the off-white particles or regions in Figure 7 .

[0170] It can be seen from Figures 3 to 7 that for the positive electrode material provided in Example 2, the active ion supplement material particles are in close contact with the positive electrode active material particles, and the active ion supplement material particles are uniformly dispersed in the voids of the positive electrode active material accumulation body, which indicates that the active ion supplement particles are successfully embedded in the interior of the positive electrode active material agglomerates, and moreover, both the active ion supplement material and the positive electrode active material are in a highly uniform dispersion state.

[0171] Test Example 2

[0172] This test example 2 tests the performance of the positive electrode materials, positive electrode sheets, and lithium-ion / sodium-ion batteries provided in Examples 1 to 8 and Comparative Examples 1 to 6. Specific test items are as follows:

[0173] (1) Slurry stability: After the positive electrode slurry is prepared, take a portion of the positive electrode slurry and let it stand for 2 hours. Observe its state and record it.

[0174] (2) First coulombic efficiency: The first discharge capacity and first charge capacity of each of the above lithium-ion / sodium-ion batteries were measured using a blue battery tester CT3001A, and the first coulombic efficiency was calculated, where first coulombic efficiency = first discharge capacity / first charge capacity × 100%.

[0175] (3) Based on the theoretical capacity of the positive electrode active material and its proportion, the capacity of the active ion supplement material can be reversely calculated, that is, the capacity of the active ion supplement material.

[0176] (4) Cycle retention rate: The capacity retention rate of the above-mentioned lithium-ion / sodium-ion battery after 100 cycles at a charge and discharge rate of 0.2C / 0.2C.

[0177] The test results above are shown in Table 4.

[0178] Table 4

[0179] As can be seen from Table 4, for high-capacity lithium-supplementing materials / sodium-supplementing materials (Examples 1-4, 6, and 8, and Comparative Examples 2-3 and 6), if a conventional mixing method is used to mix with the positive electrode active material (Comparative Examples 2-3 and 6), the positive electrode slurry will show different degrees of sedimentation after standing, and the stability is poor. It is speculated that this is due to the high residual alkali on the surface of the lithium-supplementing / sodium-supplementing material, which causes the polyvinylidene fluoride to fail and the positive electrode slurry to be jelly-like. However, for the "embedded" lithium-supplementing / sodium-supplementing composite positive electrode slurry involved in the embodiments of the present disclosure (Examples 1-4, 6, and 8), the positive electrode slurry remains stable after standing, without sedimentation, indicating that the structure of the positive electrode material enables the protection of the high-capacity lithium-supplementing / sodium-supplementing material and improves process compatibility.

[0180] For batteries obtained by conventionally mixing positive electrode active materials with active ion supplementary materials, the discharge capacity is estimated. The capacity of the lithium / sodium supplementary materials is relatively low (only 10%-40% of the theoretical capacity). This indicates that during the preparation process, the lithium / sodium supplementary materials are affected by air, humidity, etc., causing local failure and failing to achieve the theoretical capacity. The corresponding battery has a low capacity retention rate after 100 cycles (60%-75%), indicating that the failed lithium / sodium supplementary materials have adverse effects on the overall positive electrode, presumably due to increased polarization, gas production, and catalytic side reactions in the battery cell.

[0181] The positive electrode material provided in the embodiment of the present disclosure has an active ion supplement material capacity of 400mAh / g-750mAh / g, which is close to its theoretical capacity, and has good battery cycle stability (>90%@100cls), proving that the structure of the positive electrode material increases the stability of the lithium / sodium supplement material while not causing additional side reactions to the battery system.

[0182] For the organic lithium / sodium-supplementing materials (Comparative Examples 4 and 5, and Examples 5 and 7), the lithium / sodium-supplementing capacity of Comparative Examples 4 and 5 was not fully realized. This is presumably because the organic lithium / sodium-supplementing materials have high decomposition potentials, resulting in poor contact with conventional mixing methods and inability to decompose within the designed voltage window. However, the lithium / sodium-supplementing capacity of Examples 5 and 7 approached the theoretical value, indicating that the "embedded" composite structure of the positive electrode material provides better contact with the lithium / sodium-supplementing material, significantly reducing its decomposition overpotential and enabling decomposition within the designed voltage window. The resulting batteries also exhibited excellent cycling stability (>93% @ 100 cls).

[0183] The above description is only for the purpose of facilitating those skilled in the art to understand the technical solutions of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the scope of protection of the present disclosure.

Claims

1. A positive electrode material, wherein: The positive electrode material comprises positive electrode active material aggregates and active ion supplementary materials, wherein the positive electrode active material aggregates are formed by stacking the positive electrode active materials; The active ion supplement material is located at least in a plurality of gaps of the positive electrode active material agglomerates, and the active ion supplement material is bonded to the positive electrode active material.

2. The positive electrode material according to claim 1, wherein The average particle size of the positive electrode material is 2um-20um, and the average particle size of the active ion supplement material is 10nm-2000nm.

3. The positive electrode material according to claim 1, wherein Based on 100 parts by weight of the positive electrode material, the weight of the active ion supplement material is 1 part to 10 parts.

4. The positive electrode material according to claim 1, wherein The density of the positive electrode material is greater than 90%.

5. The positive electrode material according to any one of claims 1 to 4, wherein Carbon simple substance and / or carbon compound exist between different particles of the positive electrode active material and between the positive electrode active material and the active ion supplement material, and the carbon simple substance and / or carbon compound are used to provide chemical bonding force.

6. The positive electrode material according to claim 1, wherein The mass ratio of the active ion supplement material located in the plurality of gaps of the positive electrode active material agglomerates to the total mass of the active ion supplement material is greater than or equal to 90%.

7. The positive electrode material according to any one of claims 1 to 6, wherein The positive electrode active material agglomerates are formed by stacking lithium-based positive electrode active materials, and the active ion supplement material is a lithium supplement material.

8. The positive electrode material according to any one of claims 1 to 6, wherein The positive electrode active material agglomerates are formed by stacking sodium-based positive electrode active materials, and the active ion supplement material is a sodium supplement material.

9. The positive electrode material according to claim 7, wherein The lithium-based positive electrode active material is selected from at least one of lithium iron phosphate, lithium iron manganese phosphate, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, and lithium-rich layered oxide; The lithium supplement material is selected from at least one of Li3N, LiF, and Li2O 2、 Li2O, Li x M y O z where 0 < x ≤ 6, 0 < y ≤ 4, 0 ≤ z ≤ 5, and M is selected from at least one of C, S, Si, Fe, Al, Co, Mn, Zn, Ni, Sb, Te, and Ti.

10. The positive electrode material according to claim 8, wherein The sodium-based positive electrode active material is selected from at least one of sodium vanadium phosphate, sodium vanadium fluorophosphate, sodium manganese phosphate, sodium iron phosphate, sodium cobaltate, sodium manganate, sodium nickelate, sodium vanadate, and sodium nickel iron manganate; The sodium supplement material is selected from at least one of Na3N, NaF, Na2O2, Na2O, Na x M y O z , where 0 < x ≤ 6, 0 < y ≤ 4, 0 ≤ z ≤ 5, and M is selected from at least one of C, S, Si, Fe, Al, Co, Mn, Zn, Ni, Sb, Te, Ti.

11. The positive electrode material according to any one of claims 1 to 10, wherein: The positive electrode material further comprises a coating layer, which is coated on the outside of the positive electrode active material agglomerate and is used to enhance the structural stability of the positive electrode material.

12. A positive electrode sheet, wherein: The positive electrode sheet comprises the positive electrode material according to any one of claims 1 to 11.

13. An electrochemical energy storage battery, wherein: The electrochemical energy storage battery includes a positive electrode plate, and the positive electrode plate is as described in claim 12.

14. The electrochemical energy storage cell according to claim 13, wherein: The electrochemical energy storage battery includes a lithium ion battery and a sodium ion battery.

15. A method for preparing a positive electrode material, wherein: The positive electrode material is as described in any one of claims 1 to 11; The preparation method of the positive electrode material comprises: The positive electrode active material, the active ion supplement material, the organic binder and the solvent are uniformly mixed to form a raw material solution; Under an inert atmosphere, spray drying the raw material liquid to obtain a granular intermediate; The granular intermediate is calcined under an inert atmosphere to obtain the positive electrode material.

16. The method for preparing a positive electrode material according to claim 15, wherein: The solid content of the raw material liquid is 10%-50%, and the viscosity is 1000cP-5000cP.

17. The method for preparing a positive electrode material according to claim 15, wherein: The spray drying operation parameters meet at least one of the following parameters: air inlet temperature is 150°C-200°C, air outlet temperature is 90°C-120°C, peristaltic pump speed is 100ml / h-1000ml / h, and nozzle diameter is 0.5mm-2mm.

18. The method for preparing a positive electrode material according to claim 15, wherein: The operating parameters of the calcination process meet at least one of the following parameters: the calcination temperature is 400° C.-700° C., and the calcination time is 6 hours-12 hours.

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