Method for constructing ultra-thin amorphous nanocoating layer in situ
By constructing an ultrathin amorphous nanocoating layer on the surface of Li2MnO3 cathode material, the voltage decay problem of lithium-ion battery cathode materials was solved, achieving high capacity and stable cycle performance, thus promoting the commercial application of the material.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING UNIV OF TECH
- Filing Date
- 2023-03-28
- Publication Date
- 2026-05-01
AI Technical Summary
In the existing technology, the positive electrode material Li2MnO3 for lithium-ion batteries suffers from oxygen release, poor cycle stability, and poor battery capacity retention. In particular, the structural transformation caused by the migration of transition metal ions and oxygen release leads to severe voltage decay, which hinders its commercial application.
By constructing an ultrathin amorphous nano-coating material LixMnOy in situ on the surface of Li2MnO3 cathode material, and using co-precipitation, sol-gel method or electrodeposition combined with hydrothermal method, an amorphous amorphous coating layer with a thickness of 0.1-10 nm is formed, thereby improving the interfacial stability of the material.
It significantly suppressed voltage decay, with zero voltage decay during 50 charge-discharge cycles, while maintaining high discharge specific capacity and improving the cycling stability of the material.
Smart Images
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Abstract
Description
Methods for in-situ construction of ultrathin amorphous nano-coating materials Technical Field
[0001] This invention relates to the field of cathode materials for lithium-ion batteries, specifically to a method for in-situ construction of ultrathin amorphous nano-coating materials. Background Technology
[0002] Rechargeable lithium-ion batteries play a crucial role in powering various applications, particularly electric vehicles, portable electronic devices, and large-scale stationary energy storage. However, due to limitations in cathode materials, the energy density of lithium-ion batteries is insufficient to meet our energy needs. Compared to traditional layered LiCoO2 and olivine LiFePO4 cathode materials, lithium-rich layered oxides have attracted widespread attention due to their low cost, high capacity, and high energy density. Among typical lithium-rich layered oxide cathode materials, Li2MnO3 exhibits a high capacity (theoretical capacity up to 458 mAh g⁻¹). -1 This material is considered a potential candidate material for the commercialization of electric vehicles. In addition, when combined with other cathode materials as part of composite materials, it can effectively increase the capacity of traditional cathodes, such as Li₂MnO₃ and LiNi. x CoMn 1-x-y The discharge specific capacity of the O2-based complex can reach 200 mAh g. -1 While Li₂MnO₃ and its composites offer advantages such as high capacity and high energy density, they also suffer from numerous problems, including oxygen release, poor rate performance, poor cycle stability, and severe voltage decay. In particular, continuous structural decay not only reduces cycle life but also leads to drastic voltage decay, severely hindering the commercial application of lithium-rich layered oxides.
[0003] The voltage decay of lithium-rich layered oxides is mainly due to the structural transformation from the layered phase to the spinel phase induced by the migration of transition metal ions and the release of oxygen, which promotes the Mn phase transition. 3+ / Mn 4+ The contribution of redox reactions to capacity at low voltages. To suppress voltage decay and improve capacity retention in lithium-rich environments, researchers have developed various schemes. For example, Professor Wei Haijun's research group at Beijing University of Technology introduced amorphous LiTaO3 and spinel structures onto the surface of lithium-rich grains, reducing voltage decay to 0.9 mV / cycle. Furthermore, they found that co-doping Al / Ti in lithium-rich environments can further reduce voltage decay to 0.34 mV / cycle. Manthiram, after amorphizing Li2MnO3, found that the relaxation of the amorphous structure was Li... + The embedding and extraction create a smooth path. This improves Li +The diffusion rate is increased, reducing the battery resistance during cycling and thus increasing the discharge specific capacity. Furthermore, unlike the spinel LiMn2O4 structure, the amorphous structure reduces the lattice distortion caused by the Jahn-Teller effect, allowing Li2MnO3 materials to smoothly adapt to deformation without macroscopic distortion. However, due to its chemical synthesis, it inevitably contains impurities such as Na and I, resulting in a very low discharge voltage of only 2.6V. Therefore, to address the voltage decay of lithium-rich manganese-based amorphous oxide cathode materials, this invention developed a series of methods to successfully construct an ultrathin amorphous nano-coating material, Li2MnO3, in situ on the surface of the Li2MnO3 cathode material. x MnO y While ensuring the high discharge specific capacity of the material, it also significantly suppressed the voltage decay of Li2MnO3. During 50 charge-discharge cycles, its voltage decay was zero. Summary of the Invention
[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for in-situ construction of ultrathin amorphous nano-coating materials.
[0005] The objective of this invention can be achieved through the following technical solutions:
[0006] A method for in-situ construction of ultrathin amorphous nanostructured coating materials. Methods for constructing amorphous nanostructured coatings of Li₂MnO₃ include one of the following: co-precipitation, sol-gel method, or electrodeposition combined with hydrothermal method. The synthesized material is a crystalline Li₂MnO₃ material coated with a layer of amorphous Li₂MnO₃. x MnO y Its chemical formula is Li x MnO y @Li2MnO3, where Li x MnO y The thickness of the amorphous coating layer is 0.1-10 nm. Li x MnO y In Li, x and y are not specified. x MnO y Overall, it represents amorphous, non-crystalline Li-Mn-O materials.
[0007] One of the methods for constructing ultrathin amorphous nanocoatings according to the present invention is a coprecipitation method, which includes the following steps:
[0008] (1) Prepare solution A by mixing manganese source, lithium source and deionized water in a certain stoichiometric ratio;
[0009] (2) After adding the precipitant to solution A, react it at a certain temperature for a period of time; during the reaction, add a certain amount of CH3COOH to make Li + With H+ Proton exchange is performed to pre-construct attachment sites for amorphous materials, followed by further reaction to evaporate the liquid to dryness. The sample is then washed, dried, and finally calcined at a certain temperature for a period of time. After cooling, Li is obtained through screening. x MnO y @Li2MnO3 sample.
[0010] The manganese source in step (1) is at least one of MnSO4, Mn(NO3)2, Mn(CH3COO)2, and MnCl2; the lithium source is LiOH. . At least one of H2O, Li2CO3, LiNO3, CH3COOLi, and LiF; Mn:Li = 1:2~3 (molar ratio);
[0011] The precipitant in step (2) can be ammonia or ammonium salt; the ratio of precipitant to Mn is 1 to 2:1 (molar ratio); the reaction temperature is 50-120℃, the reaction time is 6-20h; the concentration of CH3COOH is 0.1-1mol / L; the calcination temperature is 400-900℃, the heating rate is 2.5-10℃ / min, the cooling rate is 5-15℃ / min, and the holding time is 5-30h.
[0012] One of the methods for constructing ultrathin amorphous nano-coating layers according to the present invention is the sol-gel method, which includes the following steps:
[0013] (1) Dissolve manganese source and lithium source in deionized water at a certain stoichiometric ratio to form transparent solution A;
[0014] (2) The chelating agent was added to solution A at a certain stoichiometric ratio, and after mixing evenly, solution B was obtained. Subsequently, a certain amount of CH3COOH was added to solution B to make Li + With H + Proton exchange is performed by pre-constructing amorphous interface attachment sites to obtain solution C, and then a certain amount of NH3 is added. . H₂O was added to solution C and mixed thoroughly to obtain solution D. Solution D was then heated at a certain temperature for a period of time to obtain a gel-like sample E. Finally, gel-like sample E was dried in an oven for a period of time, then calcined at a certain temperature for a period of time, and cooled to obtain Li. x MnO y @Li2MnO3 sample.
[0015] The manganese source in step (1) can be at least one of MnSO4, Mn(NO3)2, Mn(CH3COO)2, and MnCl2; the lithium source can be LiOH. .At least one of H2O, Li2CO3, LiNO3, CH3COOLi, and LiF; Mn:Li = 1:1~2 (molar ratio);
[0016] The chelating agent in step (2) can be at least one of ethylenediaminetetraacetic acid, ethylene glycol, citric acid, tartaric acid, and phthalic acid; the concentration of CH3COOH is 0.1-1 mol / L; the chelating agent:Mn = 1-2:1; NH3 . The addition of H2O allows the pH of the solution to be adjusted within the range of 9–12. Solution C is heated at 50–80℃ for 5–12 h to obtain gel-like sample D. Gel-like sample D is dried at 60–120℃ for 8–12 h, and then calcined at 300–900℃ for 4–10 h to finally obtain Li. x MnO y @Li2MnO3 sample.
[0017] One method for constructing an ultrathin amorphous nanocoating layer according to the present invention is an electrodeposition combined with a hydrothermal method, comprising the following steps:
[0018] (1) Preparation of δ-MnO2 precursor: Manganese source and deionized water were mixed in a certain stoichiometric ratio to prepare electrodeposition solutions A of different concentrations. After ultrasonication for 30 min, the solutions were prepared for use. Electrodeposition was performed using a two-electrode system consisting of a working electrode and a counter electrode, or a three-electrode system consisting of a working electrode, a counter electrode, and a reference electrode. After inserting the electrode into electrodeposition solution A in the electrodeposition tank, different deposition voltages or deposition currents were applied for deposition. After deposition at a certain temperature for a period of time, a tightly attached δ-MnO2 precursor was obtained on the working electrode. A certain amount of CH3COOH solution was added to the δ-MnO2 precursor to make Li + With H + Proton exchange is performed to pre-construct amorphous interface attachment sites; finally, the surface is rinsed with deionized water 3-5 times to remove residual electrodeposition solution and then placed in an 80℃ oven to dry for later use.
[0019] (2) Preparation of Li x MnO y @Li2MnO3 cathode material: Lithium source and deionized water were prepared into solutions B of different concentrations according to a certain stoichiometric ratio. After ultrasonic mixing for 30 min, the mixture was transferred to a 90 ml stainless steel autoclave lined with polytetrafluoroethylene. Then, the δ-MnO2 that had been dried in step (1) and attached to the working electrode was placed into the autoclave liner. The autoclave was then heated in a water bath at a certain temperature for a period of time. Finally, the synthesized Li2MnO3 cathode material was taken out. x MnO y @Li2MnO3 sample, rinsed and dried.
[0020] The manganese source in step (1) is at least one of MnSO4, Mn(NO3)2, Mn(CH3COO)2, and MnCl2; the concentration of electrodeposition solution A is 0.1-5 mol / L; both the working electrode and the counter electrode are conductive materials, selected from any one or more of metals and carbon materials; the reference electrode can be one of a saturated calomel electrode and an Ag / AgCl electrode; the electrodeposition temperature is 10-70℃; the electrodeposition method can be constant voltage electrodeposition, pulsed voltage electrodeposition, constant current electrodeposition, and pulsed current electrodeposition, wherein the deposition current density is 0.1-10 mA / cm². 2 The concentration of CH3COOH is 0.1-1 mol / L.
[0021] The lithium source in step (2) is at least one of LiOH.H2O, Li2CO3, LiNO3, CH3COOLi and LiF; the concentration of solution B is 0.1-10 mol / L; the water bath heating temperature is 100-220℃ and the hydrothermal time is 10-40h.
[0022] Advantages of this invention:
[0023] 1. This invention utilizes co-precipitation, sol-gel methods, and electrodeposition combined with hydrothermal methods to in-situ coat an ultrathin amorphous Li₂MnO₃ surface with a layer of Li₂. x MnO y This improves the interfacial stability of the material.
[0024] 2. Li x MnO y The structural design of the @Li2MnO3 cathode material significantly suppresses voltage decay, with zero voltage decay during 50 charge-discharge cycles. Attached Figure Description
[0025] Figure 1 shows the XRD pattern of pure Li2MnO3 synthesized by solid-state reaction in Comparative Example 1.
[0026] Figure 2 shows the synthesis of Li by electrodeposition combined with hydrothermal method in Example 3. x MnO y XRD pattern of @Li2MnO3.
[0027] Figure 3 shows the Li synthesized in Examples 1, 2, and 3 respectively using the co-precipitation method, sol-gel method, and electrodeposition combined with hydrothermal method. x MnO y TEM image of @Li2MnO3.
[0028] Figure 4 shows the synthesis of Li by electrodeposition combined with hydrothermal method in Example 3. x MnO y EDS plot of @Li2MnO3.
[0029] Figure 5 compares the pure Li₂MnO₃ obtained by solid-state synthesis in Example 1 and the Li₂MnO₃ synthesized by electrodeposition combined with hydrothermal method in Example 3. x MnO y Comparison of discharge voltage changes for @Li2MnO3. Detailed Implementation
[0030] The present invention will be illustrated below with specific embodiments. The purpose of providing the embodiments is to facilitate a better understanding of the present invention, rather than to limit the scope of the present invention.
[0031] Comparative Example 1
[0032] Pure Li2MnO3 cathode material was prepared by solid-state synthesis.
[0033] (1) Weigh MnO2 and Li2CO3 in a molar ratio of 1:1.05 and grind them in a mortar for 15 minutes. Then mix them evenly by mechanical grinding (wet ball milling, the liquid added during the ball milling process is alcohol).
[0034] (2) The mixed material was dried in a vacuum oven at 80°C for 12 hours. After the sample was completely dried, it was calcined in a tube furnace with Ar at 450°C for 48 hours. The heating rate was 5°C / min and the cooling rate was 10°C / min. After cooling, pure Li2MnO3 cathode material was obtained.
[0035] Figure 1 shows the XRD pattern of pure Li2MnO3 synthesized by solid-state reaction method. As shown in the figure, it can be found that all the peaks correspond to the standard PDF card of Li2MnO3.
[0036] Example 1
[0037] The preparation technique for in-situ construction of ultrathin amorphous nano-coating layers on the surface of Li₂MnO₃ using a co-precipitation method is as follows:
[0038] (1) Dissolve Mn(CH3COO)2 and CH3COOLi in deionized water to obtain solution A, wherein Mn:Li = 1:2 (molar ratio).
[0039] (2) NH4 . After HCO3 was added to solution A, the reaction was carried out at 80℃ for 8 hours (NH4HCO3:Mn = 2:1); after 1 hour of reaction, 0.5 mol / L CH3COOH was added to Li + With H +Proton exchange was performed to pre-construct amorphous interface attachment sites, followed by continued reaction until the liquid was evaporated to dryness. The resulting sample was then washed and dried. Finally, it was calcined at 600℃ for 20 hours (heating rate 5℃ / min), and after cooling to room temperature (cooling rate 10℃ / min), Li was obtained through screening. x MnO y @Li2MnO3 sample.
[0040] Figure 3(a) shows the synthesis of Li by the coprecipitation method. x MnO y TEM images of Li2MnO3 clearly show an ultrathin amorphous coating layer on the surface of Li2MnO3, with a thickness of approximately 0.5-1 nm.
[0041] Example 2
[0042] The preparation technique of in-situ constructing an ultrathin amorphous nano-coating layer on the surface of Li₂MnO₃ using the sol-gel method is as follows:
[0043] (1) Dissolve Mn(NO3)2 and Li2CO3 in deionized water to form a transparent solution A, wherein Mn:Li = 1:2 (molar ratio).
[0044] (2) Tetraethyl oxalate was added to solution A as a chelating agent and mixed thoroughly to obtain solution B, wherein the ratio of tetraethyl oxalate to Mn was 1:1; subsequently, 0.5 mol / L CH3COOH was added to solution B to make Li + With H + Proton exchange is performed, and amorphous interface attachment sites are pre-constructed to obtain solution C; then a certain amount of NH3 is added. . H₂O was added to solution C to adjust the pH to 10, and the mixture was thoroughly mixed to obtain solution D. Solution D was then heated at 80℃ for 10 hours to obtain a gel-like sample E. Gelatinous sample E was dried in a 100℃ oven for 10 hours, followed by calcination at 700℃ for 5 hours. After cooling, Li was obtained. x MnO y @Li2MnO3 sample.
[0045] Figure 3(b) shows Li synthesized via the sol-gel method. x MnO y The TEM image of @Li2MnO3 clearly shows that an ultrathin amorphous coating layer with a thickness of about 3-5 nm is formed on the surface of Li2MnO3.
[0046] Example 3
[0047] The preparation technique for in-situ construction of ultrathin amorphous nano-coating layers on the surface of Li₂MnO₃ using a combination of electrodeposition and hydrothermal method is as follows:
[0048] (1) Prepare electrodeposition solution A of 1 mol / L by mixing Mn(NO3)2 and deionized water in a certain stoichiometric ratio, and ultrasonically mix for 30 min for later use; use a three-electrode system consisting of carbon paper as the working electrode, metal Pt as the counter electrode, and a saturated calomel electrode as the reference electrode for electrodeposition; after inserting the electrodes into electrodeposition solution A in the electrodeposition tank, introduce 3 mA / cm 2 Deposition was performed using a constant current at 25°C for 1 hour, and a tightly adhered δ-MnO2 precursor was observed on the working electrode. The δ-MnO2 precursor was then added to a certain amount of CH3COOH to... + With H + Proton exchange is performed to pre-construct amorphous interface attachment sites; finally, the surface is rinsed with deionized water 3-5 times until the residual electrodeposition solution is completely removed, and then placed in an 80℃ oven to dry for later use.
[0049] (2) LiOH . H2O and deionized water were mixed at a certain stoichiometric ratio to form a 1 mol / L solution B. After ultrasonication for 30 min, the mixture was transferred to a 90 ml stainless steel autoclave lined with polytetrafluoroethylene. Subsequently, the δ-MnO2 precursor attached to the working electrode in step (1) was placed into the autoclave liner and reacted in a 200 °C oven for 12 h. After the reaction was completed, yellow Li was obtained. x MnO y @Li2MnO3 samples were then rinsed with deionized water 3-5 times until all residual electrodeposition solution was removed, and then dried in an 80℃ oven for later use.
[0050] Figure 2 shows Li synthesized by electrodeposition combined with hydrothermal method. x MnO y The XRD pattern of Li₂MnO₃ is shown in the figure. It can be observed that all diffraction peaks correspond to the standard PDF card of Li₂MnO₃, but no Li₂ is observed. x MnO y The diffraction peaks are due to its ultrathin and amorphous nature.
[0051] Figure 3(c) shows Li synthesized via electrodeposition combined with a hydrothermal method. x MnO y The TEM image of @Li2MnO3 clearly shows that an ultrathin amorphous coating layer with a thickness of about 2-3 nm is formed on the surface of Li2MnO3.
[0052] Figure 4 shows the synthesis of Li via electrodeposition combined with hydrothermal method. x MnO y @Li2MnO3 material surface amorphous coating layer Lix MnO y The EDS plot of Li. As shown in the figure, Li can be observed. x MnO y Uniform distribution of Mn and O elements on the surface.
[0053] Figure 5 shows the synthesis of Li2MnO3 from pure Li2MnO3 prepared by solid-state synthesis and Li2MnO3 by electrodeposition combined with hydrothermal method. x MnO y A comparison of the average discharge voltage of the cathode materials during charge-discharge cycles at a current density of 20 mA / g. As shown in the figure, pure Li₂MnO₃ exhibits significant voltage decay during cycling, with the average discharge voltage decreasing from 3.2V to 2.7V after 50 cycles, a decrease of 10mV per cycle. Meanwhile, Li… x MnO y @Li2MnO3 exhibits superior voltage drop suppression behavior, with zero voltage decay during 50 discharge cycles.
[0054] The purpose of this embodiment description is to facilitate understanding and application of the present invention by those skilled in the art. Those skilled in the art can easily modify or substitute the conditions in the embodiments, and thus apply the general principles described herein to other embodiments without creative effort. Therefore, improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, are all within the protection scope of the present invention.
Claims
1. A method for in-situ construction of an ultrathin amorphous nano-coating material, characterized in that, The in-situ constructed ultrathin amorphous nanocoating material has a structure of crystalline Li₂MnO₃ coated with a layer of amorphous Li₂. x MnO y Its chemical formula is Li x MnO y @Li2MnO3, where Li x MnO y The thickness of the amorphous coating layer is 0.1-10 nm; Li x MnO y The overall representation is an amorphous, non-crystalline Li-Mn-O material; the method is co-precipitation, including the following steps: (1) Manganese source, lithium source and deionized water are prepared into solution A according to a certain stoichiometric ratio; the molar ratio of Mn:Li is 1:2~3; (2) After adding the precipitant to solution A, it is reacted at a certain temperature for a period of time; a certain amount of CH3COOH is added during the reaction to make Li + With H + Proton exchange is performed to pre-construct amorphous material attachment sites, followed by continued reaction until the liquid is evaporated to dryness. The sample is then washed and dried. Finally, it is calcined at a certain temperature for a period of time, and after cooling, Li is obtained through screening. x MnO y @Li2MnO3 sample.
2. The method according to claim 1, characterized in that, The manganese source in step (1) is at least one of MnSO4, Mn(NO3)2, Mn(CH3COO)2 and MnCl2; the lithium source is at least one of LiOH·H2O, Li2CO3, LiNO3, CH3COOLi and LiF; the precipitant in step (2) is ammonia or ammonium salt; the molar ratio of precipitant to Mn is 1~2:1; the reaction temperature is 50-120 ℃, the reaction time is 6-20 h; the concentration of CH3COOH is 0.1-1 mol / L; the calcination temperature is 400-900 ℃, the heating rate is 2.5-10 ℃ / min, the cooling rate is 5-15 ℃ / min, and the holding time is 5-30 h.
3. A method for in-situ construction of an ultrathin amorphous nano-coating material, characterized in that, The in-situ constructed ultrathin amorphous nanocoating material has a structure of crystalline Li₂MnO₃ coated with a layer of amorphous Li₂. x MnO y Its chemical formula is Li x MnO y @Li2MnO3, where Li x MnO y The thickness of the amorphous coating layer is 0.1-10 nm; Li x MnO y The overall representation is an amorphous, non-crystalline Li-Mn-O material; the method is the sol-gel method, including the following steps: (1) dissolving manganese source and lithium source in deionized water at a certain stoichiometric ratio to form a transparent solution A; the molar ratio of Mn:Li is 1:1~2; (2) adding chelating agent to solution A at a certain stoichiometric ratio, mixing evenly to obtain solution B, and then adding a certain amount of CH3COOH to solution B to make Li + With H + Proton exchange was performed to pre-construct amorphous material attachment sites, resulting in solution C. A certain amount of NH3·H2O was then added to solution C and mixed thoroughly to obtain solution D. Solution D was then heated at a certain temperature for a period of time to obtain a gel-like sample E. Finally, gel-like sample E was dried in an oven for a period of time, calcined at a certain temperature for a period of time, and cooled to obtain Li. x MnO y @Li2MnO3 sample.
4. The method according to claim 3, characterized in that, The manganese source in step (1) is at least one of MnSO4, Mn(NO3)2, Mn(CH3COO)2, and MnCl2; the lithium source is at least one of LiOH·H2O, Li2CO3, LiNO3, CH3COOLi, and LiF; the chelating agent in step (2) is at least one of ethylenediaminetetraacetic acid, ethylene glycol, citric acid, tartaric acid, and phthalic acid; the ratio of chelating agent to Mn is 1~2:1; the concentration of CH3COOH is 0.1-1 mol / L; the addition of NH3·H2O adjusts the pH of the solution to within the range of 9~12; the heating temperature of solution D is 50-80 ℃, and the heating time is 5-12 h; the drying temperature of gel sample E is 60-120 ℃, the drying time is 8-12 h, the calcination temperature is 300-900 ℃, and the calcination time is 4-10 h, finally obtaining Li x MnO y @Li2MnO3 sample.
5. A method for in-situ construction of ultrathin amorphous nano-coating materials, characterized in that, The in-situ constructed ultrathin amorphous nanocoating material has a structure of crystalline Li₂MnO₃ coated with a layer of amorphous Li₂. x MnO y Its chemical formula is Li x MnO y @Li2MnO3, where Li x MnO y The thickness of the amorphous coating layer is 0.1-10 nm; Li x MnO y The whole represents amorphous and amorphous Li-Mn-O material; the method is electrodeposition combined with hydrothermal method, including the following steps: (1) Preparation of δ-MnO2 precursor: Manganese source and deionized water are prepared into electrodeposition solution A of different concentrations according to a certain stoichiometric ratio, and ultrasonically mixed for 30 min for use; electrodeposition is carried out using a two-electrode system consisting of a working electrode and a counter electrode or a three-electrode system consisting of a working electrode, a counter electrode and a reference electrode; after inserting the electrode into the electrodeposition solution A in the electrodeposition tank, different deposition voltages or deposition currents are introduced for deposition, and after deposition at a certain temperature for a period of time, a tightly attached δ-MnO2 precursor is obtained on the working electrode; (2) Preparation of Li x MnO y @Li2MnO3 cathode material: Lithium source and deionized water were prepared into solutions B of different concentrations according to a certain stoichiometric ratio. After being ultrasonically mixed for 30 min, the mixture was transferred to a 90 ml stainless steel autoclave lined with polytetrafluoroethylene. Then, the δ-MnO2 attached to the working electrode in step (1) was placed into the autoclave liner. The autoclave was then heated in a water bath at a certain temperature for a period of time. Finally, the synthesized Li2MnO3 cathode material was taken out. x MnO y @Li2MnO3 sample, rinsed and dried.
6. The method according to claim 5, characterized in that, The manganese source in step (1) is at least one of MnSO4, Mn(NO3)2, Mn(CH3COO)2, and MnCl2; the concentration of electrodeposition solution A is 0.1-5 mol / L; both the working electrode and the counter electrode are conductive materials, selected from any one or more of metals and carbon materials; the reference electrode is one of a saturated calomel electrode and an Ag / AgCl electrode; the temperature during the electrodeposition process is 10-70 ℃; the electrodeposition method is constant voltage electrodeposition, pulsed voltage electrodeposition, constant current electrodeposition, and pulsed current electrodeposition, wherein the deposition current density is 0.1-10 mA / cm². 2 The lithium source in step (2) is at least one of LiOH·H2O, Li2CO3, LiNO3, CH3COOLi and LiF; the concentration of solution B is 0.1-10 mol / L; the water bath heating temperature is 100-220 ℃ and the hydrothermal time is 10-40 h.
7. The application of the in-situ constructed ultrathin amorphous nano-coating material prepared by the method according to any one of claims 1-6, Li x MnO y @Li2MnO3 as a cathode material for lithium batteries.
8. The application according to claim 7, Li x MnO y The structure of the @Li2MnO3 cathode material significantly suppresses voltage decay, with zero voltage decay during 50 charge-discharge cycles.