CN113921773B - Surface-coated modified lithium ion battery positive electrode material and preparation method and application thereof - Google Patents
Surface-coated modified lithium ion battery positive electrode material and preparation method and application thereof Download PDFInfo
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Abstract
The invention discloses a surface coating modified lithium ion battery anode material and a lithium battery, wherein the surface coating modified lithium ion battery anode material specifically comprises the following components: the positive electrode material comprises a positive electrode material body, a high-entropy cation disordered oxide coating layer coated on the surface of the positive electrode material body and an ion doping layer existing on the surface close to the positive electrode material body; the positive electrode material body, the ion doping layer and the high-entropy cation disordered oxide coating layer jointly form a multi-stage core-shell coating structure; the near surface of the positive electrode material body is a distance from the material surface of the positive electrode material body to the inside within the range of 0-100 nm.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a surface-coated modified lithium ion battery anode material and a preparation method and application thereof.
Background
Rapid development in the fields of consumer electronics, electric vehicles, smart grids, and the like, put higher demands on the performance of rechargeable batteries. Among various rechargeable battery technologies, lithium ion batteries have become the most important development direction in the secondary battery market due to their excellent electrochemical performance. With the continuous expansion of the application field, how to further improve the energy density of the lithium ion battery becomes the key point of battery research and development.
Increasing the operating voltage of a lithium ion battery is the most direct and effective way to increase its energy density. However, at high voltages, the electrode materials in the battery present risks of safety and reliability. In order to ensure that the electrode material, especially the anode material, keeps stable in long-period circulation, modification of the surface of the anode material particles is necessary. The surface coating technology is the simplest and most effective surface modification method, and the surface coating layer can reduce side reactions generated on the interface of the electrolyte and the anode and stabilize the surface structure and components of the material, so that the electrochemical performance of the battery is improved.
Generally, the surface properties of the positive electrode material particles have great influence on the physical and electrochemical properties of the positive electrode material particles, for example, CN105489878A and CN105226256A adopt some inorganic oxides to perform surface coating modification on the positive electrode material, so that the direct contact between the positive electrode material and the electrolyte can be reduced or avoided, and the rapid capacity attenuation caused by interface side reactions can be relieved. However, these methods cause lithium ions in the bulk of the positive electrode material to diffuse into the coating layer material during the surface coating process, resulting in a change in the structure of the bulk of the positive electrode material, and thus, may also cause a decrease in battery performance. In addition, other various metal oxide coatings, e.g. MgO, snO 2 、SiO 2 ZnO, cuO, etc., are also used for LiCoO 2 The interface modification of the cathode material is carried out, but the electrochemical performance of the battery cannot be improved remarkably at a higher cut-off voltage. Further, metal fluoride (CeF) is performed on the surface of the positive electrode material 3 ,AlF 3 ,MgF 2 ,AlW x F y Etc.) the coating strategy is also applied, and although the cycle stability is improved, the coating structure and composition are not beneficial to the rapid transport of lithium ions at the interface of the anode material. In recent years, the appearance of solid electrolyte coating materials improves the ion transport performance of the interface of the positive electrode material to a certain extent, but due to the poor electronic conductivity and the essential properties of non-electrochemical activity, the problems of material capacity reduction, rate performance deterioration and the like are still caused.
Although the types of coating materials are various, the surface coating layers of the current commercial cathode materials are mainly oxides and fluorides. The traditional coating material can avoid direct contact of electrolyte and a positive electrode material to a certain extent, and improves the electrochemical stability of the material. However, since the coating material has no electrochemical activity and is limited in ionic and electronic conductivity, the optimal performance of the electrode material cannot be exerted to the maximum extent, and the improvement of the comprehensive performance of the material is limited.
Disclosure of Invention
The invention aims to provide a surface coating modified lithium ion battery anode material, and a preparation method and application thereof, aiming at the defects of the prior art. The adopted surface coating modified material has electrochemical activity and stable structure, can realize higher ionic and electronic conductivity, and can improve the electrochemical performance and safety of the lithium battery by applying the cathode material.
In view of this, the embodiment of the present invention provides a surface-coating modified lithium ion battery positive electrode material, which specifically includes: the positive electrode material comprises a positive electrode material body, a high-entropy cation disordered oxide coating layer coated on the surface of the positive electrode material body and an ion doping layer existing on the surface close to the positive electrode material body; the positive electrode material body, the ion doping layer and the high-entropy cation disordered oxide coating layer jointly form a multi-stage core-shell coating structure;
the near surface of the positive electrode material body is a distance from the material surface of the positive electrode material body to the inside within the range of 0-100 nm.
Preferably, the positive electrode material body includes: one or more of hexagonal layered oxide lithium cobaltate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate and lithium-rich cathode materials with layered and/or rock salt structure composite.
Preferably, the positive electrode material body is granular and comprises primary particles and secondary particles, and the particle size range of the primary particles is between 1nm and 10 um; the particle size range of the secondary particles is between 10nm and 100 um; the secondary particles are composed of a plurality of primary particles.
Preferably, the material of the high-entropy cation disordered oxide coating layer is a high-entropy cation disordered oxide with a molecular general formula of Li (M1) a M2 b M3 c ...Mi j )O 2 (ii) a Wherein, i = [5-10 =]Mi is selected from one of Li, mg, sc, ti, V, cr, mn, fe, co, ni, cu, zn, ga, sr, Y, zr, nb, mo, ru, sn, sb and W; j is the stoichiometric coefficient for each M element, and a + b + c + \ 8230, + j =1, meaning that the sum of the stoichiometric coefficients for all M elements is 1.
More preferably, the M element specifically includes 5 of Li, ti, V, cr, mn, fe, co, ni, zr, nb, and Mo.
Preferably, the positive electrode material near-surface ion doped layer comprises the following components: the positive electrode material comprises the constituent elements of the positive electrode material body and all or part of the constituent elements of the high-entropy cation disordered oxide coating material;
the structure type of the ion doping layer is specifically a derivative structure obtained by diffusion reaction of the constituent elements of the high-entropy cation disordered oxide coating layer to the near surface of the positive electrode material body.
Further preferably, the derivative structure is specifically: in the heat treatment process of synthesizing the surface coating modified lithium ion battery cathode material, metal ions in the high-entropy cation disordered oxide coating material diffuse to the cathode material body and occupy octahedral or tetrahedral sites in a transition metal layer or a lithium ion layer in the cathode material body structure, so that a derivative structure comprising one or more of a layered structure, a spinel structure, a rock salt structure or a disordered structure is formed.
Preferably, the mass ratio of the high-entropy cation disordered oxide coating layer to the positive electrode material body is 0.1-10%, and the average thickness of the high-entropy cation disordered oxide coating layer is 2nm-5 μm.
In a second aspect, an embodiment of the present invention provides a lithium battery, including the surface-coated modified lithium ion battery positive electrode material described in the first aspect.
Preferably, the lithium battery includes: any one of a liquid lithium ion battery, a liquid metal lithium battery, a mixed solid-liquid lithium ion battery, and a mixed solid-liquid metal lithium battery.
The invention provides a surface-coated modified lithium ion battery anode material, which is characterized in that multi-scale interface modification is carried out on the surface of an anode material particle, so that the outer surface, the grain boundary, primary particles or a bulk phase structure of the anode material particle contain component elements of the surface-coated modified material, and the actual application performance of the anode material is improved in a multi-scale cooperation mode. Compared with the existing anode material, the surface coating modified lithium ion battery anode material provided by the invention has the characteristics of simple material synthesis process, high structural stability and excellent ion conduction characteristic of the coating layer material, and can form a multi-level structure interface modification effect on the anode material body, so that the surface activity of the anode under high temperature and high voltage and the contact area of the anode and electrolyte can be effectively reduced, the occurrence of irreversible interface side reaction is inhibited, the ion transport capacity of the anode interface can be improved, and the surface coating modified lithium ion battery anode material has the advantage of multifunctional modification.
Drawings
The technical solutions of the embodiments of the present invention are further described in detail below with reference to the accompanying drawings and embodiments.
Fig. 1 is a schematic structural diagram of a surface-coated modified lithium ion battery positive electrode material provided in an embodiment of the present invention;
FIG. 2 shows a high-entropy cation-disordered oxide Li (Mn) as a surface coating material in example 1 of the present invention 0.2 Ni 0.2 Fe 0.2 Ti 0.2 Nb 0.2 )O 2 X-ray diffraction pattern (XRD);
fig. 3 is an X-ray diffraction (XRD) comparison graph of the lithium cobaltate positive electrode material before and after the surface modification coating provided in example 1 of the present invention;
fig. 4 is a Scanning Electron Microscope (SEM) image of lithium cobaltate as an original cathode material provided in example 1 of the present invention;
fig. 5 is an SEM image of lithium cobaltate as the surface-coating modified cathode material provided in example 1 of the present invention;
FIG. 6 is a comparison graph of electrochemical cycle performance at 25 ℃ of the original cathode material and the surface-coated modified cathode material provided in example 1 of the present invention;
fig. 7 is a comparison graph of electrochemical cycle performance at 45 ℃ of the original cathode material and the cathode material with the modified surface coating provided in example 1 of the present invention.
Detailed Description
The embodiment of the invention provides a surface coating modified lithium ion battery anode material, the structure of which is shown in figure 1, and the surface coating modified lithium ion battery anode material specifically comprises the following components: the positive electrode material comprises a positive electrode material body 1, a high-entropy cation disordered oxide coating layer 2 coated on the surface of the positive electrode material body 1 and an ion doping layer 3 existing on the surface, close to the surface, of the positive electrode material body 1; the positive electrode material body 1, the ion doping layer 3 and the high-entropy cation disordered oxide coating layer 2 jointly form a multi-stage core-shell coating structure.
Here, although the thickness of the clad layer 2 and the ion doped layer 3 of the cathode material body 1 shown in fig. 1 is small, uniform, and continuous in distribution, the distribution continuity, the thickness ratio, the uniformity, and the contact tightness among the cathode material body 1, the clad layer 2, and the ion doped layer 3 in the lithium ion battery cathode material obtained by actual production are not limited to the form and the thickness ratio shown in fig. 1.
The anode material body is granular and comprises primary granules and secondary granules, and the size range of the primary granules is between 1nm and 10 um; the particle size range of the secondary particles is between 10nm and 100 um; the secondary particles are composed of a plurality of primary particles.
The particles of the positive electrode material body comprise positive electrode material particles in pure phase (i.e. original single crystal phase) and/or positive electrode material particles containing doping elements, wherein the doping elements are elements which are subjected to bulk phase doping on the positive electrode material body in advance, such as Ti, al, la and the like; the material of the positive electrode material body comprises: one or more of hexagonal layered oxide lithium cobaltate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate and lithium-rich cathode materials with layered and/or rock salt structure composite.
The material is high-entropy cation disordered oxide, and the molecular general formula is Li (M1) a M2 b M3 c ...Mi j )O 2 (ii) a Wherein, i = [5-10 =]M1, M2 and M3.. Mi in the M elements are respectively selected from one of Li, mg, sc, ti, V, cr, mn, fe, co, ni, cu, zn, ga, sr, Y, zr, nb, mo, ru, sn, sb and W; j is the stoichiometric coefficient for each M element, and a + b + c + \ 8230, + j =1, indicating that the sum of the stoichiometric coefficients of the high-entropy cationic disordered oxide cladding for all M elements is 1. Preferably, i =5, and M1 to M5 are selected from 5 kinds of Li, ti, V, cr, mn, fe, co, ni, zr, nb, and Mo.
The mass ratio of the high-entropy cation disordered oxide coating layer to the anode material body is 0.1-10%, preferably 0.2-5%, and the average thickness of the high-entropy cation disordered oxide coating layer is 2nm-5 μm, preferably 2nm-1 μm.
The near surface of the positive electrode material body is a distance in a range of 0 to 100nm from the material surface of the positive electrode material body inwards. The thickness range of the near surface of the anode material body is determined by the thickness of the coating layer, the chemical composition of the coating layer material and the heat treatment condition of the anode material coating process.
The positive electrode material near-surface ion doped layer comprises the following components: the positive electrode material comprises the constituent elements of the positive electrode material body and all or part of the constituent elements of the high-entropy cation disordered oxide coating material. The structure type of the high-entropy cation disordered oxide coating layer is a derivative structure obtained by diffusion reaction of the constituent elements of the high-entropy cation disordered oxide coating layer towards the near surface of the anode material body. Specifically, in the heat treatment process of synthesizing the surface coating modified lithium ion battery cathode material, metal ions in the high-entropy cation disordered oxide coating material diffuse to the cathode material body and occupy octahedral or tetrahedral sites in a transition metal layer or a lithium ion layer in the cathode material body structure, so that a derivative structure comprising one or more of a layered structure, a spinel structure, a rock salt structure or a disordered structure is formed. The distribution of dopant ions (including dopant ions from the bulk of the positive electrode material and from the high entropy cationic disordered oxide coating) may be graded or uniform across the near surface of the bulk of the positive electrode material, depending on the nature of the different dopant elements.
According to the surface coating modified lithium ion battery anode material, multi-scale interface modification is performed on the surface of the anode material particle layer, so that the component elements of the surface coating modified material exist in the outer surface, the crystal boundary, the primary particle or the bulk phase structure of the anode material particle, and the practical application performance of the anode material is improved through multi-scale cooperation.
The surface-coated modified lithium ion battery cathode material provided by the embodiment can be obtained by fully and uniformly mixing the cathode material body and the surface-coated material high-entropy cation disordered oxide and then sintering.
Wherein, the mixing mode can specifically adopt one or more of solid phase mixing, liquid phase mixing, mechanical mixing and chemical mixing; the sintering mode can specifically adopt one-time sintering or multiple-time sintering; the sintering process can be carried out in a mixed atmosphere of one or more of air, argon, oxygen, nitrogen and hydrogen, and the sintering temperature is preferably 300-1000 ℃.
Multiple elements in the surface coating layer material can generate ionic thermal diffusion behavior on the near surface of the anode material body through high-temperature sintering, and an ion doping layer is formed on the near surface of the anode material body, so that a stable interface layer between the anode material body and the coating layer is formed, a multi-level interface modification structure is formed on the surface of the anode material body, and the obtained anode material has the advantages of high interface stability, good interface ion transport capacity, good thermal stability and the like. The preparation process is simple and easy to implement, and is beneficial to large-scale production in practical application.
The surface-coated modified lithium ion battery positive electrode material can be directly used for manufacturing lithium batteries after being prepared into a positive electrode plate, and can be specifically used for liquid lithium ion batteries, liquid metal lithium batteries, mixed solid-liquid lithium ion batteries, mixed solid-liquid metal lithium batteries and the like.
In order to better understand the technical solution of the present invention, the following will describe the preparation process of the surface-coating modified lithium ion battery positive electrode material proposed in the present invention and the characteristics of the lithium ion battery positive electrode material using the same in a plurality of specific examples. It should be understood that the following examples are only for enabling the person skilled in the art to practice the invention, and do not limit the scope of the invention.
Example 1
This embodiment 1 provides a surface-coated modified lithium ion battery positive electrode material, specifically a surface-coated modified lithium cobalt oxide positive electrode material, and is used to illustrate a synthesis method and an application thereof.
2kg of original lithium cobalt oxide powder was mixed with 20g of high entropy cation disordered oxide Li (Mn) 0.2 Ni 0.2 Fe 0.2 Ti 0.2 Nb 0.2 )O 2 The powder is put into a ball mill for mechanical ball milling and mixing, the ball milling rotating speed is 300rpm/min, and the mass of the material and the ball milling beadsThe ratio was 1 to 10 and the ball milling time was 2 hours. The obtained mixed powder was transferred to a tube furnace and sintered at 700 ℃ for 4 hours, thereby obtaining a surface-coated modified lithium cobaltate positive electrode material.
FIG. 2 shows Li (Mn) as a cladding material 0.2 Ni 0.2 Fe 0.2 Ti 0.2 Nb 0.2 )O 2 The powder X-ray diffraction (XRD) pattern of (2) was analyzed to find that the crystal had a cation disordered rock salt structure.
Fig. 3 shows a comparison result of XRD data before and after coating modification of the surface of the lithium cobaltate positive electrode material, and it can be seen from fig. 3 that the bulk layer structure of the positive electrode material is not changed by coating modification of the surface of the positive electrode material at a high temperature using a small amount of the high-entropy cation disordered oxide material.
Fig. 4 and fig. 5 respectively show scanning electron microscope images of the lithium cobaltate positive electrode material before and after surface coating modification, and a comparative analysis of the two images shows that after the surface coating modification treatment, a rough and uniform nanoparticle coating layer is loaded on the smooth surface of the original positive electrode material, which can show that the method provided by the present specification can achieve a better surface coating modification effect.
And preparing the surface-coated and modified lithium cobaltate positive electrode material into a positive electrode piece, and loading the positive electrode piece into a liquid lithium ion battery for electrochemical performance test. The specific battery assembling steps are as follows: mixing the surface-coated and modified lithium cobaltate positive electrode material, acetylene black and polyvinylidene fluoride (PVDF) according to the mass ratio of 90. Then, metal lithium is used as a negative electrode, an aluminum trioxide coated diaphragm is used as a separation film, and the positive electrode piece is used as a positive electrode, so that the CR2032 button cell is assembled together.
The obtained battery is subjected to electrochemical performance test in a constant-current constant-voltage charging mode and a constant-current discharging mode, and the cut-off voltage range of charging and discharging is 3-4.6V (vsLi/Li) + ). The test temperatures were respectively room temperature 25The charge and discharge current measured at 45 deg.C and elevated temperature was 0.1C.
To illustrate the positive effect of surface coating modification on positive performance of lithium ion batteries, we also performed comparative tests on the original lithium cobaltate positive electrode material without surface coating treatment by the above method, using the same assembly and test methods.
The results of comparing electrochemical cycle performance at 25 ℃ are shown in FIG. 6. The results of comparing electrochemical cycle performance at 45 ℃ are shown in FIG. 7. As can be seen from the electrochemical cycling test results in fig. 6 and 7, the electrochemical cycling stability of the surface-coated and modified cathode material is significantly improved.
Example 2
A surface-coating modified cathode material was prepared in the same manner as in example 1, except that this example was carried out using Li (Co) 0.2 Ni 0.2 Mn 0.2 Fe 0.2 Nb 0.2 )O 2 Used as a surface coating material of a cathode material.
Example 3
A surface-coating-modified positive electrode material was prepared in the same manner as in example 1, except that this example was made of Li (Ni) 7/15 Mn 3/15 Nb 1/15 Ti 2/15 Mo 2/15 )O 2 Used as a surface coating material of a cathode material.
Example 4
A surface-coating-modified positive electrode material was prepared in the same manner as in example 1, except that 2kg of the original lithium cobaltate powder and 10g of the high-entropy cation-disordered oxide Li (Mn) were used 0.2 Ni 0.2 Fe 0.2 Ti 0.2 Nb 0.2 )O 2 And (3) powder.
The electrochemical performance data of the original lithium cobaltate positive electrode material and the surface coating modified lithium cobaltate positive electrode material in examples 1-4 above are shown in table 1 below.
TABLE 1
Compared with the lithium battery using the original lithium cobaltate cathode material, the lithium battery using the surface-coated modified cathode material provided by the invention has more excellent comprehensive performance, and particularly the cycle capacity retention rate at normal temperature and high temperature is obviously improved. The surface of the anode material is uniformly coated with the high-entropy cation disordered rock salt oxide, so that the contact between the anode material and the electrolyte is effectively reduced, side reactions and the corrosion of the electrolyte to the anode material are reduced, and the electrochemical performance of the anode material is improved.
Example 5
Embodiment 5 of the invention provides a lithium ion battery cathode material, which is a surface-coated modified ternary cathode material, and the synthesis method and application thereof are described in the embodiment.
2kg of commercial ternary positive electrode LiNi 0.6 Mn 0.2 Ni 0.2 O 2 The powder was mixed with 20g of Li (Li) high-entropy disordered rock salt oxide 0.2 Ni 0.2 Mn 0.2 Ti 0.2 Nb 0.2 )O 2 And putting the powder into a ball mill for mechanical ball milling and mixing, wherein the ball milling rotating speed is 200rpm/min, the mass ratio of the materials to ball milling beads is 1: 10, and the ball milling time is 4 hours. The resulting mixed powder was transferred to a tube furnace and sintered at 550 ℃ for 6 hours. Thereby obtaining the surface-coated modified ternary cathode material.
And (3) preparing the ternary cathode material with the surface coated and modified into a cathode plate, and loading the cathode plate into a liquid lithium ion battery for electrochemical performance test. The specific battery assembling steps are as follows: mixing the surface-coated modified ternary cathode material, acetylene black and polyvinylidene fluoride (PVDF) according to the mass ratio of 90. Then, metal lithium was used as a negative electrode, an aluminum trioxide-coated separator was used as a separator, and the above-mentioned positive electrode piece was used as a positive electrode, and they were assembled together to form a CR2032 button cell.
The obtained battery is made to adopt a constant currentElectrochemical performance tests are carried out in a constant voltage charging mode and a constant current discharging mode, and the cut-off voltage range of charging and discharging is 3-4.4V (vsLi/Li) + ). The test temperature is room temperature, and the charge and discharge current is 0.1C.
To illustrate the positive effect of surface coating modification on positive performance of lithium ion batteries, we also conducted comparative tests on the original commercial ternary positive electrode material that was not surface coated by the above method, using the same assembly and test methods. The result shows that the electrochemical cycling stability of the ternary cathode material after surface coating modification is obviously improved.
Example 6
Embodiment 6 of the invention provides a lithium ion battery cathode material, which is a surface-coated modified lithium-rich manganese-based cathode material, and the embodiment illustrates a preparation method and application thereof.
2kg of sintered lithium-rich manganese-based material powder was mixed with 4g of nano-Li (Mn) 7/15 Ni 3/15 Nb 3/15 Ti 1/15 Mo 1/15 )O 2 And (3) putting the powder into a ball mill for mechanical ball milling and mixing, wherein the ball milling rotating speed is 200rpm/min, the mass ratio of the materials to ball milling beads is 1 to 10, and the ball milling time is 4 hours. The resulting mixed powder was transferred to a tube furnace and sintered at 550 ℃ for 6 hours. Thereby obtaining the surface coating modified lithium-rich manganese-based cathode material.
The surface-coated and modified lithium-rich manganese-based positive electrode material is prepared into a positive electrode plate of a liquid lithium ion battery and assembled into a CR2032 button cell, and the steps are the same as those in the embodiment 5. The research result of electrochemical test shows that compared with the original anode material, the lithium-rich manganese-based anode material with the modified surface coating has obviously improved electrochemical cycling stability.
The invention uses the high-entropy cation disordered rock salt oxide as the surface coating modified material of the anode material, has the characteristics of high structural stability and excellent lithium ion conduction characteristic, and forms an ion doping layer by utilizing the spontaneous ion diffusion effect between the anode material particles and the surface coating material and spontaneously diffusing chemical elements of the coating material on the near surface or crystal boundary of the anode material particle body at a specific synthesis temperature, so that the surface of the anode material obtains a multifunctional interface property with stable thermodynamics and good dynamics, the performance attenuation caused by a series of interface side reactions of the anode material in the circulation process can be effectively relieved, the stability of the anode material interface anions is improved, particularly the problem of oxygen precipitation under high voltage can be effectively inhibited, the structure of the anode material is more stable, and the battery can work more safely under high voltage and high temperature; in the material sintering process, a coating layer is formed on the outer surface of the positive electrode material particle body, and an ion doped layer is formed on the near surface of the positive electrode material, so that the structural stability and comprehensive performance of the material can be better improved from multiple scales and layers; in general, multiple interface modification is performed on the positive electrode material particles, so that the problems of direct contact between electrolyte and a positive electrode, volume expansion of the positive electrode particles, dissolution of transition metal and the like can be solved, and the structural stability, chemical stability and electrochemical stability of the positive electrode material at high working temperature and high working voltage are improved, so that the lithium ion battery has the advantages of good high-voltage performance, high safety, long cycle life and the like.
The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only examples of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (7)
1. The surface-coated and modified lithium ion battery positive electrode material is characterized by specifically comprising the following components in percentage by weight: the positive electrode material comprises a positive electrode material body, a high-entropy cation disordered oxide coating layer coated on the surface of the positive electrode material body and an ion doping layer existing on the surface close to the positive electrode material body; the positive electrode material body, the ion doping layer and the high-entropy cation disordered oxide coating layer jointly form a multi-stage core-shell coating structure;
the near surface of the positive electrode material body is a distance from the material surface of the positive electrode material body to the inside within the range of 0-100 nm;
the material of the high-entropy cation disordered oxide coating layer is a high-entropy cation disordered oxide with a molecular general formula of Li (M1) a M2 b M3 c ...Mi j )O 2 (ii) a Wherein, i = [5-10 =]M1, M2 and M3.. Mi in the M elements are respectively selected from one of Li, mg, sc, ti, V, cr, mn, fe, co, ni, cu, zn, ga, sr, Y, zr, nb, mo, ru, sn, sb and W; j is the stoichiometric coefficient for each M element, and a + b + c + \ 8230, + j =1, meaning that the sum of the stoichiometric coefficients for all M elements is 1;
the positive electrode material near-surface ion doped layer comprises the following components: the positive electrode material comprises the constituent elements of the positive electrode material body and all or part of the constituent elements of the high-entropy cation disordered oxide coating material;
the structure type of the ion doping layer is specifically a derivative structure obtained by diffusion reaction of the constituent elements of the high-entropy cation disordered oxide coating layer to the near surface of the positive electrode material body;
the derivative structure is specifically as follows: in the heat treatment process of synthesizing the surface coating modified lithium ion battery cathode material, metal ions in the high-entropy cation disordered oxide coating material diffuse to the cathode material body and occupy octahedral or tetrahedral sites in a transition metal layer or a lithium ion layer in the cathode material body structure, so that a derivative structure comprising one or more of a layered structure, a spinel structure, a rock salt structure or a disordered structure is formed.
2. The surface-coated modified lithium ion battery cathode material according to claim 1, wherein the cathode material body comprises: one or more of hexagonal layered oxide lithium cobaltate, nickel cobalt lithium manganate, nickel cobalt lithium aluminate, a lithium-rich cathode material with a layered structure, a lithium-rich cathode material with a rock salt structure or a lithium-rich cathode material compounded by the layered structure and the rock salt structure.
3. The surface-coated and modified lithium ion battery cathode material according to claim 1, wherein the cathode material body is granular and comprises primary particles and secondary particles, and the size of the primary particles is in the range of 1nm-10 um; the particle size range of the secondary particles is between 10nm and 100 um; the secondary particles are composed of a plurality of primary particles.
4. The surface-coating modified lithium ion battery cathode material according to claim 1, wherein the M element specifically comprises 5 of Li, ti, V, cr, mn, fe, co, ni, zr, nb and Mo.
5. The surface-coating-modified lithium ion battery cathode material as claimed in claim 1, wherein the mass ratio of the high-entropy cation disordered oxide coating layer to the cathode material body is 0.1-10%, and the average thickness of the high-entropy cation disordered oxide coating layer is 2nm-5 μm.
6. A lithium battery comprising the surface-coated modified lithium ion battery positive electrode material according to any one of claims 1 to 5.
7. The lithium battery of claim 6, comprising: any one of a liquid lithium ion battery, a liquid metal lithium battery, a mixed solid-liquid lithium ion battery, and a mixed solid-liquid metal lithium battery.
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