Surface-reconstructed layered oxide positive electrode material, preparation method, application and battery

Abstract

The invention discloses a surface-reconstructed layered oxide positive electrode material, a preparation method, application and a battery. The preparation method comprises the following steps: (1) forming carbonate on the surface of a layered oxide positive electrode material in situ to obtain a surface-activated layered oxide positive electrode material; and (2) carrying out ion exchange reaction on the surface-activated layered oxide positive electrode material and metal salt, and then carrying out annealing treatment to obtain the surface-reconstructed layered oxide positive electrode material. The surface-reconstructed layered oxide positive electrode material prepared by the invention can realize higher energy density and rate capability, and the preparation method is simple to operate and can be used for large-scale preparation.

Description

TECHNICAL FIELD

[0001] The present application relates to a surface-reconstructed layered oxide cathode material, a preparation method, applications and a battery. BACKGROUND

[0002] In the field of electric vehicles and portable electronic devices, lithium ion batteries have become the mainstream energy storage solution. To meet the urgent market demand for higher energy density and longer cycle life, the key performance indicators of battery electrode materials need to be broken through. Layered oxide LiTMO2 cathode materials, such as lithium cobaltate and ternary materials, have a relatively high theoretical specific capacity (about 275 mAh / g), but their actual available capacity is usually low. To further improve the energy density and power density, it is usually necessary to increase the charge cut-off voltage. Studies have shown that by increasing the charge cut-off voltage of lithium cobaltate cathode from 4.2 V to 4.6 V, the reversible specific capacity can be increased from 140 mAh / g to 220 mAh / g, and the volume energy density can be significantly increased from 2293.2 Wh / L to 3721.0 Wh / L.

[0003] However, when the layered oxide cathode material is charged to a high delithiation state (Li 1-x TMO2, x > 0.8), a series of problems such as H1-3 / O1 harmful phase transition, lattice oxygen loss and severe interface side reactions are easily caused, which leads to the gradual transformation of the layered structure into spinel or rock salt phase, thereby causing rapid decay of the electrochemical performance. Therefore, how to effectively modify the structure and interface instability of layered materials at high voltage, and simultaneously improve the energy density and power density, has become the focus of attention of the academic and industrial circles.

[0004] Currently, the modification of layered oxide cathode materials is mainly surface coating, and common methods include solid phase mixing / ball milling combined with annealing process. Although this method is simple to operate, the coating layer formed is often thick, uneven or island-like, not only hindering the transmission of lithium ions at the interface, but also easily falling off during long-term cycling, resulting in limited improvement effect on the performance of the material. SUMMARY

[0005] The technical problem solved by the present application is to overcome the defects of large impedance and uneven thickness of the coating layer in the prior art, which leads to limited improvement effect on the performance of the material, and to provide a surface-reconstructed layered oxide cathode material, a preparation method, applications and a battery. The surface-reconstructed layered oxide cathode material prepared by the present application can achieve higher energy density and rate performance, and the preparation method is simple to operate and can be prepared on a large scale.

[0006] In the preparation of the surface-restructured layered oxide positive electrode material, first, a carbonate is formed in situ on the surface of the layered oxide positive electrode material to obtain a surface-activated layered oxide positive electrode material, the carbonate coating layer is not a simple physical coating layer, but is formed in situ on the internal surface of the layered oxide positive electrode material. It plays a multiple role of bridging the past and the future: it is a "cleaning agent" for removing surface defects of the positive electrode material, and a "reaction base stone" for constructing an advanced functional interface. Subsequently, the surface-activated layered oxide positive electrode material is subjected to an ion exchange reaction with a metal salt (such as Ca 2+ , La 3+ , etc.), and by means of a topological ion exchange reaction, on the one hand, the initial carbonate (such as Li2CO3) layer reacts with the introduced metal (TM) ions. The TM ions partially replace the lithium sites of the carbonate, and due to the difference in valence and radius of different ions, in order to maintain charge balance, lithium vacancies are generated in the lattice, and a Li x TM y CO3 restructured layer (such as Li 2-2x Ca x CO3) is formed; on the other hand, the TM penetrates into the Li site of the layered oxide, and due to the size mismatch and charge driving, the oxygen skeleton is restructured, and the original ABC close-packed arrangement is changed into a network with larger Goldschmidt tolerance factor of the octahedral interstice and the octahedral common vertex angle connection, and a perovskite structure (such as ) is constructed in situ on the surface, and finally a restructured layered oxide positive electrode material with a carbonate and perovskite composite coating structure is formed in situ on the surface. Among them, the Li x TM y CO3 layer has the characteristics of low modulus and good elasticity, and the perovskite layer is rich in oxygen vacancies and is an excellent oxygen ion conductor, which can be used as an oxygen release buffer layer at high voltage. The finally prepared surface-restructured layered oxide positive electrode material exhibits superior performance in terms of energy density and power density.

[0007] The present application solves the above technical problems by the following technical scheme:

[0008] The present application provides a preparation method of a surface-restructured layered oxide positive electrode material, which comprises the following steps:

[0009] (1) forming a carbonate in situ on the surface of the layered oxide positive electrode material to obtain a surface-activated layered oxide positive electrode material;

[0010] (2) after the ion exchange reaction of the surface-activated layered oxide positive electrode material with a metal salt, annealing treatment is performed to obtain the surface-restructured layered oxide positive electrode material.

[0011] In step (1), the thickness of the carbonate can be 1-30 nm, such as 3 nm, 5 nm or 10 nm.

[0012] In step (1), the layered oxide cathode material can be a conventional layered oxide material in the art, preferably one or more of lithium cobalt oxide (LiCoO2), ternary material (LiNi x Co y Mn 1-x-y O2), lithium-rich material (x Li2MnO3·(1-x) LiTMO2, 0 < x < 1) and sodium battery layered cathode material. When the cation in the layered oxide cathode material is lithium ion, the component of the carbonate is generally lithium carbonate; when the cation in the layered oxide cathode material is sodium ion, the component of the carbonate is generally sodium carbonate.

[0013] In some embodiments, the layered oxide cathode material is 003-type lithium cobalt oxide or 004-type lithium cobalt oxide.

[0014] In step (1), the method for forming the carbonate in situ preferably comprises the step of: cooling the layered oxide cathode material directly in a dry ice-acetone saturated solution.

[0015] For example, when the cation in the layered oxide cathode material is lithium ion, lithium carbonate is formed due to the residual lithium on the surface of the layered oxide cathode material contacting the dry ice during the cooling process.

[0016] In the dry ice-acetone saturated solution, the amount of dry ice needs to be excessive, i.e. solid dry ice is always present in the saturated solution, because the dry ice will sublimate. The mass ratio of dry ice to acetone in the dry ice-acetone saturated solution is preferably (0.5-10):1, such as 0.5:1, 1:1, 2:1 or 5:1.

[0017] The mass of the layered oxide cathode material to the volume of the dry ice-acetone saturated solution can be 1:(2-50) g / mL, such as 1:10, 1:20, 1:25 or 1:30.

[0018] The cooling treatment is generally performed in a room temperature environment. The cooling treatment is generally performed in a mixed state. The mixing can be performed by stirring. The mixing time can be 20-120 min, preferably 40-90 min, for example 50 min, 60 min or 70 min. The stirring speed can be 300-1000 r / min, preferably 500-1000 r / min, for example 600 r / min, 700 r / min, 800 r / min or 900 r / min. After the cooling treatment, a drying treatment is generally performed to remove residual acetone. The drying treatment is generally performed in an oven. The drying temperature can be 70-100℃, for example 70℃ or 80℃. The drying time can be 4-24 h, for example 6 h, 12 h or 18 h.

[0019] In step (1), the method for forming a carbonate in situ can comprise the following steps: after short-time pulse heating, dry ice quenching treatment is performed.

[0020] The short-time pulse heating and dry ice quenching treatment not only help to promote lattice expansion and introduce oxygen vacancy defects, but also effectively activate the material surface, making it rough and high-energy, thus more conducive to subsequent surface structure reconstruction.

[0021] The short-time pulse heating refers to heating the layered oxide positive electrode material to a target temperature in a short time. For example, the layered oxide positive electrode material is directly placed into a sintering furnace (for example, a muffle furnace or a tube furnace) preheated to a target temperature for calcination, or is heated to a target temperature in a short time by methods such as joule heat and discharge plasma sintering, which can also achieve the purpose. When the short-time pulse heating is calcination, the calcination is generally performed in an air atmosphere. The temperature of the short-time pulse heating (i.e., the target temperature) can be 300-800℃, for example 350℃, 400℃, 450℃, 500℃, 600℃ or 650℃. The time of the short-time pulse heating can be 0.5-10 min, for example 1 min, 3 min, 5 min or 8 min.

[0022] The dry ice quenching treatment refers to rapidly transferring the positive electrode material after the short-time pulse heating to a dry ice-acetone saturated solution for quenching treatment. The parameters and conditions for quenching treatment in the dry ice-acetone saturated solution, such as quenching treatment time and stirring speed, can be the same as those described above for the cooling treatment.

[0023] In step (2), the metal salt can be one or more of alkaline earth metal salts, rare earth metal salts and transition metal salts.

[0024] The metal salt can be a hydrochloride, a nitrate of the corresponding metal.

[0025] The alkaline earth metal salt can be one or more of a magnesium salt, a calcium salt, a strontium salt, and a barium salt.

[0026] The calcium salt can be calcium chloride (CaCl2).

[0027] The transition metal salt can be one or more of a copper salt, an aluminum salt, a zirconium salt, and a titanium salt.

[0028] The copper salt can be, for example, copper chloride (CuCl2); the aluminum salt can be, for example, aluminum nitrate (Al(NO3)3); the zirconium salt can be, for example, zirconyl nitrate (ZrO(NO3)2); and the titanium salt can be, for example, tetrabutyl titanate (C 16 H 36 O4Ti).

[0029] The rare earth metal salt can be one or more of a lanthanum salt, a cerium salt, a gadolinium salt, and an europium salt.

[0030] The lanthanum salt can be, for example, lanthanum nitrate (LaNO3·6H2O); the cerium salt can be, for example, cerium nitrate (Ce(NO3)3·6H2O); the gadolinium salt can be, for example, gadolinium nitrate (Gd(NO3)3·6H2O); and the europium salt can be, for example, europium nitrate (Eu(NO3)3·6H2O).

[0031] In step (2), the metal salt can be added in an amount of 0.1-5 wt%, preferably 0.3-3 wt%, such as 0.5 wt%, 0.8 wt%, 1.0 wt%, 1.5 wt%, or 2.0 wt%, wt% referring to the mass percentage of the metal salt relative to the surface-activated layered oxide cathode material.

[0032] In step (2), in addition to the metal salt, an anion salt can be additionally added for ion exchange reaction. The anion salt can be an ammonium salt, such as ammonium fluoride (NH4F), ammonium phosphate ((NH4)3PO4), ammonium sulfate ((NH4)2SO4). The anion salt can be added in an amount of 0.1-5 wt%, preferably 0.3-3 wt%, such as 0.5 wt%, 0.8 wt%, 1.0 wt%, 1.5 wt%, or 2.0 wt%, wt% referring to the mass percentage of the anion salt relative to the surface-activated layered oxide cathode material.

[0033] In some embodiments, the salt used in the ion exchange reaction can be 0.5 wt% CaCl2, 0.5 wt% CaCl2 and 1.0 wt% LaNO3·6H2O, or 0.5 wt% NH4F and 1.0 wt% LaNO3·6H2O.

[0034] In step (2), the ion exchange reaction can be performed by a liquid stirring method, a molten salt calcination method, or a solvent method.

[0035] In some embodiments, the solvent used in the liquid stirring method can be deionized water. The mass of the layered oxide cathode material and the volume of the solvent can be 1: (20-60) g / mL, such as 1:20 g / mL, 1:25 g / mL, or 1:30 g / mL. The liquid stirring method can be performed at atmospheric pressure. The reaction temperature of the liquid stirring method can be 20-80°C, such as 25°C, 30°C, 40°C, 50°C, or 60°C. The reaction time of the liquid stirring method can be 1-8 h, such as 2 h, 3 h, or 4 h. The stirring speed of the liquid stirring method can be 500-1000 r / min, such as 600 r / min, 700 r / min, 800 r / min, or 900 r / min.

[0036] In some embodiments, the molten salt calcination method refers to placing the reactants in a sintering furnace for calcination. When the molten salt calcination method is used, the calcination temperature can be 100-700°C, such as 200°C, 350°C, 450°C, 550°C, or 650°C; and the calcination time can be 0.5-10 h, such as 1 h, 2 h, 4 h.

[0037] In some embodiments, the solvent used in the solvent method can be one or more of ethanol, ethylene glycol, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and deionized water, such as a volume ratio of 1:1 of ethylene glycol / deionized water, a volume ratio of 2:1 of DMF / ethanol. The reaction temperature can be 100-200°C, such as 120°C, 150°C, 180°C. The reaction time can be 1-24 h, such as 4 h, 8 h, 12 h, 18 h. The reaction is generally performed in a sealed autoclave. The filling degree of the autoclave can be 60-80%.

[0038] In step (2), according to conventional methods, after the ion exchange reaction is completed, the filtration and drying treatment are generally required before the annealing treatment. The filtration method can be conventional, such as suction filtration. The drying treatment temperature can be 60-100°C, such as 80°C. The drying treatment time can be 4-24 h.

[0039] In step (2), the annealing treatment is generally performed in a muffle furnace, a sintering furnace or a tube furnace. The annealing treatment is generally performed in an air atmosphere. The heating rate of the annealing treatment can be 1-10°C / min, for example 5°C / min; the temperature of the annealing treatment can be 300-800°C, for example 350°C, 400°C, 450°C, 500°C or 600°C; the time of the annealing treatment can be 1-6h, for example 1.5h, 2h or 4h. The annealing treatment is generally followed by natural cooling to room temperature.

[0040] In step (2), the annealing treatment is preferably followed by a grinding treatment to obtain a powder product. The grinding can be a dry grinding as conventional in the art.

[0041] In certain preferred embodiments, when the layered oxide cathode material is a 003-type lithium cobaltate:

[0042] The temperature of the short-time pulse heating in step (1) is 600°C and the temperature of the annealing treatment in step (2) is 400°C;

[0043] Alternatively, the temperature of the short-time pulse heating in step (1) is 400°C and the temperature of the annealing treatment in step (2) is 600°C;

[0044] Alternatively, the temperature of the short-time pulse heating in step (1) is 600°C and the temperature of the annealing treatment in step (2) is 600°C.

[0045] In certain preferred embodiments, when the layered oxide cathode material is a 004-type lithium cobaltate:

[0046] The temperature of the short-time pulse heating in step (1) is 400°C and the temperature of the annealing treatment in step (2) is 400°C;

[0047] Alternatively, the temperature of the short-time pulse heating in step (1) is 600°C and the temperature of the annealing treatment in step (2) is 400°C;

[0048] Alternatively, the temperature of the short-time pulse heating in step (1) is 400°C and the temperature of the annealing treatment in step (2) is 600°C.

[0049] In certain specific embodiments, step (1) comprises the following step: cooling the layered oxide cathode material directly in a dry ice-acetone saturated solution for 20-120min;

[0050] Alternatively, the layered oxide cathode material is pulse heated at 300-800°C for 0.5-10min, and then rapidly transferred to a dry ice-acetone saturated solution for quenching treatment for 20-120min.

[0051] The application further provides the surface-restructured layered oxide positive electrode material prepared by the preparation method.

[0052] In the application, the surface-restructured layered oxide positive electrode material preferably comprises a layered oxide positive electrode material and a composite coating layer of a carbonate and a perovskite formed in situ on the surface of the surface-restructured layered oxide positive electrode material.

[0053] The application further provides application of the surface-restructured layered oxide positive electrode material in a battery positive electrode material.

[0054] The application further provides a battery comprising the surface-restructured layered oxide positive electrode material.

[0055] On the basis of common knowledge in the art, the above-mentioned preferred conditions can be combined in any manner to obtain preferred examples of the application.

[0056] The reagents and raw materials used in the application are commercially available.

[0057] The positive progress of the application is that:

[0058] The surface-restructured layered oxide positive electrode material prepared by the application effectively alleviates the structural and interface instability under high voltage through the uniform carbonate and perovskite restructuring coating layer, realizes higher energy density and rate performance, and the preparation method is simple and can be prepared on a large scale. BRIEF DESCRIPTION OF DRAWINGS

[0059] Figure 1 SEM image of the surface-restructured layered lithium cobalt oxide positive electrode material prepared in Example 1;

[0060] Figure 2 TEM image of the surface-restructured layered lithium cobalt oxide positive electrode material prepared in Example 1;

[0061] Figure 3 TEM image of the surface-restructured layered lithium cobalt oxide positive electrode material prepared in Example 1. DETAILED DESCRIPTION

[0062] The application will be further described below by way of examples, but the application is not limited in the scope of the examples. The experimental methods in the following examples are not specified, and are selected according to conventional methods and conditions or according to the instructions of the goods.

[0063] The 003 type lithium cobalt oxide used in Examples 1-6 and the 004 type lithium cobalt oxide used in Examples 7-11 were purchased from Xiamen Xiangtong New Energy; the manufacturer of the muffle furnace was Shanghai Nianshuo.

[0064] Example 1

[0065] Step (1): Prepare acetone (National Pharmaceutical Group, ≥99.7%) saturated solution of dry ice (Sain Biological). Put 2 g of lithium cobaltate (model 003) into a preheated muffle furnace at 400℃ for 5 minutes, then quickly transfer to 50 mL of dry ice-acetone saturated solution (mass ratio of dry ice to acetone is 2:1) at -78℃ for quenching treatment. Stir at 800 r / min for 60 minutes at room temperature of 25℃, then dry the sample in an 80℃ oven to remove residual acetone to obtain surface-activated lithium cobaltate.

[0066] Step (2): Then, add 0.5 wt% CaCl2 (Araldite, analytical pure), 1.0 wt% LaNO3·6H2O (Araldite, analytical pure) and 50 mL of deionized water to the surface-activated lithium cobaltate, respectively, stir at 800 r / min for 3 hours at room temperature to carry out the surface ion exchange reaction. The stirred solution is suction filtered, and the solid is dried in an 80℃ oven overnight. Finally, the sample is heated to 400℃ in a muffle furnace at a heating rate of 5℃ / min, and the temperature is kept for 2 hours. After natural cooling to room temperature, the powder product is taken out after annealing, dry ground in a mortar, and then loaded into a sample tube and stored in a vacuum environment for subsequent testing and synthesis, i.e. to obtain a reconstructed layered oxide positive electrode material with a surface carbonate and perovskite composite coating structure; wherein wt% refers to the mass percentage of metal salt relative to the mass of lithium cobaltate raw material.

[0067] Example 2

[0068] Step (1): Same as Example 1;

[0069] Step (2): Compared with Example 1, except that only 0.5 wt% CaCl2 is added and LaNO3·6H2O is not added, the rest of the operations and conditions are the same as Example 1.

[0070] Example 3

[0071] Step (1): Put 2 g of lithium cobaltate powder of model 003 directly into 50 mL of dry ice-acetone saturated solution, stir at 800 r / min for 60 min at room temperature, and then dry the sample in an 80℃ oven to remove residual acetone.

[0072] Step (2): Except that only 0.5 wt% CaCl2 is added and LaNO3·6H2O is not added, the rest of the operations and conditions are the same as Example 1.

[0073] Examples 4-10

[0074] The same operations and conditions as in Example 1 were used except that the lithium cobaltate type in Step (1), the calcination temperature in the muffle furnace in Step (1), and the calcination temperature in the muffle furnace in Step (2) were adjusted to the values in Table 1.

[0075] Table 1

[0076] Lithium cobalt oxide raw material Calcination temperature (°C) of Step (1) Calcination temperature (°C) of Step (2) Example 4 003 600 400 Example 5 003 400 600 Example 6 003 600 600 Example 7 004 400 400 Example 8 004 600 400 Example 9 004 400 600 Example 10 004 600 600

[0077] Example 11

[0078] Step (1): The same as in Example 1.

[0079] Step (2): The same operations and conditions as in Example 1 were used except that 0.5 wt% CaCl2and 1.0 wt% LaNO3·6H2O were replaced by 0.5 wt% NH4F and 1.0 wt% LaNO3·6H2O.

[0080] Comparative Example 1

[0081] Raw material 003 type lithium cobaltate.

[0082] Comparative Example 2

[0083] Raw material 004 type lithium cobaltate.

[0084] Effect Example

[0085] (1) Morphology characterization

[0086] According to Figure 1 It can be seen that the prepared surface-restructured layered oxide positive electrode material is a single-crystal particle with a particle size of 5-8 μm.

[0087] According to Figure 2 and Figure 3 It can be seen that the prepared surface-restructured layered oxide positive electrode material forms a coating layer with a thickness of about 5 nm on the surface.

[0088] (2) Electrochemical performance test

[0089] 1. Preparation of lithium battery positive electrode sheet

[0090] The modified layered oxide positive electrode material prepared in the present application, the conductive agent conductive carbon black (Super P), and the binder polyvinylidene fluoride (PVDF) were weighed and mixed uniformly in a mass ratio of 80:10:10. Subsequently, 2.5 times the total mass of N-methyl pyrrolidone (NMP) solvent was added to the mixed powder, and the obtained mixture was placed in a vortex mixer and continuously stirred at room temperature for 2 hours to form a uniform slurry.

[0091] The slurry was uniformly coated on a carbon-coated aluminum foil current collector, dried in a blast oven at 110°C for 30 min, and then the electrode sheet was rolled and cut into a 12 mm diameter circular positive electrode sheet using a punching machine. The electrode sheet was placed in a vacuum oven and dried at 110°C for 12 hours to completely remove the residual solvent. The surface density of the active material on the obtained electrode sheet was about 2.0 mg / cm2. The prepared electrode sheet was immediately transferred to an argon-filled glove box after drying for battery assembly.

[0092] 2. Assembly of a button-type lithium ion battery

[0093] A CR2032 type button battery was assembled in an argon atmosphere glove box with a water and oxygen concentration of less than 0.1 ppm. All battery components (including the battery shell, separator and electrode sheet) were treated with ethanol ultrasonic cleaning and drying before assembly and transferred to the glove box.

[0094] The battery used the positive electrode sheet as the positive electrode, a lithium metal sheet as the negative electrode, a ceramic type separator (2ccs+12pe+2ccs) as the separator, and a 1 M lithium hexafluorophosphate (LiPF6) dimethyl carbonate (DMC) / ethylene carbonate (EC) / methyl ethyl carbonate (EMC)+5 wt% fluoroethylene carbonate (FEC) mixed solution (the volume ratio of solvents DMC:EC:EMC is 1:1:1) as the electrolyte.

[0095] The assembly sequence was as follows: negative electrode shell, lithium sheet negative electrode, appropriate amount of electrolyte, separator, appropriate amount of electrolyte, positive electrode sheet, positive electrode shell. Ensure that the separator is fully soaked with electrolyte and completely covers the electrode sheet to achieve effective isolation. After aligning the positive and negative electrode sheets, a motorized button battery sealing machine was used to package under a constant pressure of 700 kg.

[0096] The assembled battery needed to be left to mature for 6 hours before testing. The results of the electrochemical performance test are shown in Table 2. 1C is 200 mA g -1 .

[0097] Table 2

[0098]

[0099] According to the above experimental results, the surface-reconstructed double-coated layered oxide positive electrode material prepared by the present application has higher specific capacity and stability, while also having good cycle stability.

[0100] Although the specific embodiments of the present application have been described above, it is understood by those skilled in the art that the present application is only illustrated by way of example, and the scope of protection of the present application is defined by the appended claims. Those skilled in the art can make various changes or modifications to the embodiments without departing from the principles and essence of the present application, and such changes and modifications fall within the scope of protection of the present application.

Claims

1. A method for preparing a surface-reconstructed layered oxide cathode material, characterized in that, Includes the following steps: (1) Carbonates are formed in situ on the surface of the layered oxide cathode material to obtain a surface-activated layered oxide cathode material; (2) After the surface-activated layered oxide cathode material is subjected to ion exchange reaction with metal salt, it is then subjected to annealing treatment to obtain the surface-reconstructed layered oxide cathode material.

2. The method for preparing the surface-reconstructed layered oxide cathode material as described in claim 1, characterized in that, In step (1), the thickness of the carbonate is 1-30 nm, for example 3 nm, 5 nm or 10 nm; And / or, in step (1), the layered oxide cathode material is one or more of lithium cobalt oxide, ternary materials, lithium-rich materials and sodium-ion battery layered cathode materials; Preferably, the lithium cobalt oxide is type 003 lithium cobalt oxide or type 004 lithium cobalt oxide; And / or, in step (1), the method for forming carbonate in situ includes the following steps: cooling the layered oxide cathode material directly in a dry ice-acetone saturated solution.

3. The method for preparing the surface-reconstructed layered oxide cathode material as described in claim 2, characterized in that, In the dry ice-acetone saturated solution, the mass ratio of dry ice to acetone is (0.5-10):1, for example, 0.5:1, 1:1, 2:1 or 5:1; And / or, the mass ratio of the layered oxide cathode material to the volume ratio of the dry ice-acetone saturated solution is 1:(2-50) g / mL, for example 1:10, 1:20, 1:25 or 1:30; And / or, the cooling process is performed in a mixed state.

4. The method for preparing the surface-reconstructed layered oxide cathode material as described in claim 1, characterized in that, In step (1), the method for forming carbonate in situ includes the following steps: after the layered oxide cathode material is subjected to short-time pulse heating, it is then subjected to dry ice rapid quenching treatment.

5. The method for preparing the surface-reconstructed layered oxide cathode material as described in claim 4, characterized in that, The short-time pulse heating method involves directly placing the layered oxide cathode material into a sintering furnace preheated to the target temperature for calcination, or sintering it through Joule heating or discharge plasma. When the short-time pulse heating method is calcination, the temperature of the short-time pulse heating is preferably 300-800℃, such as 350℃, 400℃, 450℃, 500℃, 600℃ or 650℃; the time of the short-time pulse heating is preferably 0.5-10min, such as 1min, 3min, 5min or 8min.

6. The method for preparing the surface-reconstructed layered oxide cathode material as described in claim 1, characterized in that, Step (2) satisfies one or more of the following conditions: (1) The metal salt is one or more of alkaline earth metal salts, rare earth metal salts and transition metal salts; The alkaline earth metal salt is preferably one or more of magnesium, calcium, strontium, and barium salts; the transition metal salt is preferably one or more of copper, aluminum, zirconium, and titanium salts; and the rare earth metal salt is preferably one or more of lanthanum, cerium, gadolinium, and europium salts. (2) The amount of the metal salt added is 0.1-5 wt%, preferably 0.3-3 wt%, for example 0.5 wt%, 0.8 wt%, 1.0 wt%, 1.5 wt%, or 2.0 wt%; (3) In addition to the metal salt, an anionic salt is added to carry out an ion exchange reaction; The anionic salt is preferably an ammonium salt, such as ammonium fluoride, ammonium phosphate, or ammonium sulfate; the amount of the anionic salt added is preferably 0.1-5 wt%, more preferably 0.3-3 wt%, for example 0.5 wt%, 0.8 wt%, 1.0 wt%, 1.5 wt%, or 2.0 wt%. (4) The ion exchange reaction is carried out by liquid phase stirring, molten salt calcination or solvothermal method; The reaction temperature of the liquid phase stirring method is preferably 20-80℃, for example 25℃, 30℃, 40℃, 50℃ or 60℃; the reaction time of the liquid phase stirring method is preferably 1-8h, for example 2h, 3h or 4h.

7. The method for preparing the surface-reconstructed layered oxide cathode material as described in claim 4, characterized in that, When the layered oxide cathode material is type 003 lithium cobalt oxide: The temperature of the short-time pulse heating in step (1) is 600°C, and the temperature of the annealing treatment in step (2) is 400°C; Alternatively, the temperature of the short-time pulse heating in step (1) is 400°C, and the temperature of the annealing treatment in step (2) is 600°C; Alternatively, the temperature of the short-time pulse heating in step (1) is 600°C, and the temperature of the annealing treatment in step (2) is 600°C; When the layered oxide cathode material is type 004 lithium cobalt oxide: The temperature of the short-time pulse heating in step (1) is 400℃, and the temperature of the annealing treatment in step (2) is 400℃; Alternatively, the temperature of the short-time pulse heating in step (1) is 600°C, and the temperature of the annealing treatment in step (2) is 400°C; Alternatively, the temperature of the short-time pulse heating in step (1) is 400°C, and the temperature of the annealing treatment in step (2) is 600°C.

8. A surface-reconstructed layered oxide cathode material prepared by the method described in any one of claims 1-7; Preferably, the surface-reconstructed layered oxide cathode material includes a layered oxide cathode material and a carbonate and perovskite composite coating layer formed in situ on the surface of the surface-reconstructed layered oxide cathode material.

9. The application of the surface-reconstructed layered oxide cathode material as described in claim 8 in battery cathode materials.

10. A battery comprising the surface-reconstructed layered oxide cathode material as described in claim 8.

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