Perovskite metal oxide negative electrode material and preparation method thereof, negative electrode sheet and lithium battery

Abstract

This application relates to the field of lithium-ion batteries, and discloses a perovskite-type metal oxide anode material, its preparation method, an anode sheet, and a lithium battery. The anode material described in this application includes a core layer material and a coating layer material, wherein the core layer material has the chemical formula La. 1‑x Ca x MnO3, 0.1≤x≤0.4; the coating material is amorphous carbon. This application uses metals La, Ca, and Mn as metal sources, and employs a sol-gel process to prepare perovskite-type metal oxides by controlling the molar ratio between La and Ca ions. Simultaneously, amorphous carbon is applied to these oxides to prepare La... 1‑x Ca x MnO3 / C composite anode material has many advantages such as high reversible capacity, high safety, good rate performance and good long-term cycle stability, which meet the requirements of the development of lithium-ion battery anode materials.

Description

Technical Field

[0001] This application relates to the field of lithium-ion batteries, and in particular to a perovskite-type metal oxide anode material, its preparation method, anode sheet, and lithium battery. Background Technology

[0002] Currently, lithium-ion batteries are developing rapidly, and various industries have increasingly higher requirements for their performance. Although graphite is widely used as a negative electrode material, it is easy for lithium dendrites to form when charged and discharged at high rates, which can cause serious safety hazards.

[0003] For high-performance lithium-ion battery anode materials, in addition to safe operating potential and high reversible capacity, high rate performance and long-term cycle stability are also two important properties. Exploring new lithium-ion battery anode composite materials with high capacity, long cycle life, and high safety to replace the current low-capacity graphite anode materials is of great significance.

[0004] CN113991088A discloses a chemical formula X Li x A y BO 3 a @C perovskite-type metal oxide anode material is produced by processing Li with a uniformly distributed transition metal X in the bulk phase. x A y B 1 z X z O 3 a The perovskite nanoparticles undergo a one-step reduction and carbonization process, causing the transition metal X in the perovskite lattice to undergo a desolvation reaction. As a result, the negative electrode material consists of several discrete transition metal X nanoparticles embedded on the surface of perovskite nanoparticles coated with a carbon layer. The transition metal nanoparticles are embedded on the substrate and form a good electronic conductivity network with the surface carbon layer.

[0005] Existing patent CN104157856A discloses a core-shell type LaFeO3@C lithium battery anode material, which is carbon-coated on perovskite metal oxide LaFeO3. Electrochemical experiments show that the core-shell type LaFeO3@C nanoparticles have excellent cycle lithium storage performance (mainly reflected in high specific capacity, stable cycle performance, and good adaptability to high current), and its lithium storage performance is far superior to that of LaFeO3 nanoparticles without carbon coating.

[0006] Perovskite metal oxides have advantages such as high theoretical capacity, high ionic conductivity, abundant resources, and high safety, which meet the requirements for the future development of lithium-ion battery anode materials. Summary of the Invention

[0007] In view of this, the purpose of this application is to provide a perovskite-type metal oxide anode material and a method for preparing the same, so that the anode material can improve the cycle performance of the battery;

[0008] Another objective of this application is to provide a perovskite-type metal oxide anode material and a method for preparing the same, so that the anode material can improve the rate performance of the battery.

[0009] Another objective of this application is to provide a negative electrode sheet and a lithium battery based on the aforementioned negative electrode material.

[0010] To solve the aforementioned technical problems / achieve the aforementioned objectives, or at least partially solve the aforementioned technical problems / achieve the aforementioned objectives, as a first aspect of this application, a perovskite-type metal oxide anode material is provided, comprising a core layer material and a coating layer material, wherein the core layer material has the chemical formula La. 1-x Ca x MnO3, 0.1≤x≤0.4; the coating material is amorphous carbon.

[0011] Optionally, the amorphous carbon includes hard carbon and soft carbon; further optionally, the carbon source of the hard carbon includes one or more of sugars, starch, cellulose, lignin, sawdust, bamboo shavings, coconut shells, and nut shells.

[0012] As a second aspect of this application, a method for preparing the aforementioned negative electrode material is provided, comprising:

[0013] The perovskite-type metal oxide La was synthesized using a sol-gel process with lanthanum, calcium, and manganese source materials. 1- x Ca x MnO3, 0.1≤x≤0.4;

[0014] The perovskite-type metal oxide is brought into full contact with a carbon source containing amorphous carbon, and then carbonized to obtain a carbon-coated perovskite-type metal oxide anode material.

[0015] Optionally, the sol-gel process is a citric acid sol-gel process, comprising:

[0016] Lanthanum, calcium, and manganese source materials were weighed and dissolved in water at a molar ratio of (0.6-0.9):(0.4-0.1):1 and mixed evenly. Citric acid and ethylene glycol were added and the mixture was aged. The pH was adjusted to 8-10, and the mixture was freeze-dried to form a gel. The gel was then calcined to obtain the perovskite-type metal oxide La. 1-x Ca x MnO3, 0.1≤x≤0.4.

[0017] Optionally, the calcination is carried out at 1000-1200°C.

[0018] Optionally, the lanthanum source, calcium source, and manganese source raw materials include nitrates of each metal and their corresponding hydrates.

[0019] Optionally, the carbon source of the amorphous carbon is added at 5-10% of the mass of the perovskite-type metal oxide.

[0020] As a third aspect of this application, a negative electrode sheet is provided, using the negative electrode material described in this application or the negative electrode material prepared by the preparation method described in this application as the active material.

[0021] As a fourth aspect of this application, a lithium battery is provided, comprising a positive electrode, a separator, an electrolyte, and a negative electrode as described in the third aspect.

[0022] This application uses metals La, Ca, and Mn as metal sources and employs a sol-gel process to prepare perovskite-type metal oxides by controlling the molar ratio between La and Ca ions. Simultaneously, amorphous carbon coating is applied to these oxides to prepare La... 1- x Ca x MnO3 / C composite anode material has many advantages such as high reversible capacity, high safety, good rate performance and good long-term cycle stability, which meet the requirements of the development of lithium-ion battery anode materials. Attached Figure Description

[0023] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.

[0024] Figure 1 The image shown is a SEM image of the negative electrode material described in this application. Detailed Implementation

[0025] This application discloses a graphite composite anode material and its preparation method. Those skilled in the art can refer to this document and appropriately modify the process parameters to achieve the desired result. It is particularly important to note that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this application. The products, processes, and applications described in this application have been described through preferred embodiments. Those skilled in the art can obviously modify or appropriately change and combine the methods described herein without departing from the content, spirit, and scope of this application to realize and apply the technology of this application. Obviously, the described embodiments are only some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without creative effort are within the scope of protection of this application.

[0026] It should be noted that, in this document, relational terms such as "first" and "second," "step 1" and "step 2," and "(1)" and "(2)" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Moreover, the embodiments and features described in this application can be combined with each other without conflict.

[0027] In the first aspect of this application, a perovskite-type metal oxide anode material is provided, comprising a core material and a coating material, wherein the core material has the chemical formula La. 1-x Ca x MnO3, 0.1≤x≤0.4; the coating material is amorphous carbon, and its SEM image is shown below. Figure 1 The SEM image shows that the negative electrode material particles described in this application are uniformly distributed, and most particles show obvious boundaries.

[0028] The core material is selected with a metal ion ratio of 0.1 ≤ x ≤ 0.4, which is beneficial for the regulation of perovskite photoelectric properties, crystal growth, structural stability, and light conversion. Exceeding this ratio range will have adverse effects. In some embodiments of this application, x = 0.1, 0.2, 0.3, or 0.4.

[0029] In some embodiments of this application, the amorphous carbon includes hard carbon and soft carbon; wherein, the carbon source of the hard carbon includes one or more of sugars, starch, cellulose, lignin, sawdust, bamboo shavings, coconut shells and nut shells; in some embodiments of this application, the sugars include glucose and sucrose.

[0030] In a second aspect of this application, a method for preparing the aforementioned negative electrode material is provided, comprising:

[0031] The perovskite-type metal oxide La was synthesized using a sol-gel process with lanthanum, calcium, and manganese source materials. 1- x Ca x MnO3, 0.1≤x≤0.4;

[0032] The perovskite-type metal oxide is brought into full contact with a carbon source containing amorphous carbon, and then carbonized to obtain a carbon-coated perovskite-type metal oxide anode material.

[0033] In some embodiments of this application, the sol-gel process employs a citric acid sol-gel process, comprising:

[0034] Lanthanum, calcium, and manganese source materials were weighed and dissolved in water at a molar ratio of (0.6-0.9):(0.4-0.1):1 and mixed evenly. Citric acid and ethylene glycol were added and the mixture was aged. The pH was adjusted to 8-10, and the mixture was freeze-dried to form a gel. The gel was then calcined to obtain the perovskite-type metal oxide La. 1-x Ca x MnO3, 0.1≤x≤0.4.

[0035] The addition of surfactants ethylene glycol and citric acid can reduce capillary forces during the gel drying process and prevent gel cracking. In some embodiments of this application, the molar ratio of metal ions:citric acid:ethylene glycol is 1:2:2.

[0036] In some embodiments of this application, ammonia is used to adjust the pH value.

[0037] Calcination below 1000 degrees Celsius results in a relatively poor crystal structure and affects electrochemical performance. Calcination above 1200 degrees Celsius not only damages the crystal structure and easily leads to sintering, but also poses significant risks and high energy consumption. Therefore, in some embodiments of this application, the calcination is carried out at 1000-1200 degrees Celsius, such as 1000 degrees Celsius, 1100 degrees Celsius, or 1200 degrees Celsius. In other embodiments of this application, pre-calcination can be performed before calcination at a temperature of 200-300 degrees Celsius, such as 200 degrees Celsius, 250 degrees Celsius, or 300 degrees Celsius. Regarding the duration of pre-calcination and calcination, long-term calcination at temperatures above 1000 degrees Celsius is typically used to obtain perovskite oxides with relatively pure crystal phases. However, prolonged high-temperature calcination easily leads to severe agglomeration and sintering of the material, resulting in large grains and a very low specific surface area. Therefore, in other embodiments of this application, the duration of pre-calcination and calcination is independently selected from 3-5 hours, such as 3 hours, 4 hours, or 5 hours.

[0038] In some embodiments of this application, the lanthanum source, calcium source, and manganese source raw materials include nitrates of each metal and their corresponding hydrates; in other embodiments of this application, the lanthanum source nitrates and their corresponding hydrates include La(NO3)3 and La(NO3)3·6H2O, the calcium source nitrates and their corresponding hydrates include Ca(NO3)2 and Ca(NO3)2·4H2O, and the manganese source nitrates and their corresponding hydrates include Mn(NO3)3 and Mn(NO3)3·4H2O.

[0039] In some embodiments of this application, the carbon source of the amorphous carbon is added at 5-10% of the mass of the perovskite metal oxide, for example, at 5%, 6%, 7%, 8%, 9% or 10% of the mass of the perovskite metal oxide.

[0040] In some embodiments of this application, the perovskite-type metal oxide and the amorphous carbon source are brought into full contact through either hydrothermal reaction or ball milling, depending on the water solubility of the carbon source. For example, hydrothermal reaction can be used for water-soluble carbon sources in hard carbon, while ball milling can be used directly for non-water-soluble carbon sources in hard carbon. In other embodiments of this application, water-soluble sugar carbon sources in hard carbon, such as glucose and sucrose, are used for hydrothermal reaction, which is carried out at 160-200°C for 6-10 hours. The reaction temperature can be selected from 160°C, 170°C, 180°C, 190°C, or 200°C, and the reaction time can be selected from 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours.

[0041] In some embodiments of this application, the carbonization temperature is 400-600℃, for example 400℃, 500℃ or 600℃; the carbonization time is 5-8h, for example 5h, 6h, 7h or 8h; in other embodiments of this application, the carbonization is carried out at a heating rate of 1-10℃ / min to the required carbonization temperature.

[0042] In some embodiments of this application, ultrasonic means may be used to assist in the uniform mixing or dispersion of the solution.

[0043] In some embodiments of this application, the method for preparing the negative electrode material includes:

[0044] S1: Dissolve the metal nitrates La(NO3)3·6H2O, Ca(NO3)2·4H2O, and Mn(NO3)3·4H2O in deionized water at a molar ratio of 0.6-0.9:0.4-0.1:1, and sonicate until a homogeneous solution is obtained. Add ethylene glycol and citric acid (metal ions:citric acid:ethylene glycol molar ratio of 1:2:2), adjust the pH of the solution to 8-10 using ammonia, and freeze-dry to obtain a gel. Pre-calcine the gel in a muffle furnace at 200-300℃ for 3-5 hours, then continue calcining at 1000-1200℃ for another 3-5 hours, and finally grind it into powder.

[0045] S2: Glucose or sucrose is added at a mass ratio of 5-10% to the perovskite. Both are added to deionized water, ultrasonically dispersed, and then placed in a hydrothermal reactor. The mixture is reacted at 160-200℃ for 6-10 hours in a homogeneous reactor. The product is then filtered, washed, and dried. The dried product is then carbonized in a protective gas atmosphere at a heating rate of 1-10℃ / min and held at 400-600℃ for 5-8 hours to obtain a carbon-coated perovskite-type metal oxide anode material.

[0046] In a third aspect of this application, a negative electrode sheet is provided, using the composite negative electrode material described in this application as the active material or the negative electrode material prepared by the preparation method described in this application as the active material.

[0047] In some embodiments of this application, the negative electrode sheet includes a current collector and an active material coated on the current collector; wherein, the current collector may be selected from a metal foil with good conductivity, such as copper foil; the active material includes the negative electrode material described in this application, as well as a binder, a conductive agent, and a solvent. The binder, conductive agent, and solvent, and their amounts, are selected in accordance with conventional methods, and this application does not impose specific limitations. For example, the binder may be polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), and sodium carboxymethyl cellulose (CMC), etc.; the conductive agent may be conductive carbon black (SP), acetylene black, etc.; and the solvent may be N-methylpyrrolidone (NMP), deionized water, etc. The ratio of negative electrode material: conductive agent: binder is 6:3:1.

[0048] In a fourth aspect of this application, a lithium battery is provided, including a positive electrode, a separator, an electrolyte, and the negative electrode described in this application; in some embodiments of this application, the lithium-ion battery is a full cell, a pouch cell, a Swagelok cell, or a button cell.

[0049] In some embodiments of this application, the positive electrode is a lithium metal sheet or lithium iron phosphate, high-nickel ternary, lithium-rich manganese-based material, etc.; the separator is a PP separator or a Celegard series separator; the electrolyte is a 1.0-1.5 mol / L LiPF6 solution, for example, a LiPF6 electrolyte with a volume ratio of ethylene carbonate (EC) and diethyl carbonate (DEC) as solvents of 1:1.

[0050] In the comparative experiments provided in this application, unless otherwise specified, all experimental conditions and materials remain consistent to ensure comparability. Furthermore, all materials used in this application are commercially available.

[0051] The following provides a further description of the perovskite-type metal oxide anode material, its preparation method, anode sheet, and lithium battery provided in this application.

[0052] Example 1:

[0053] S1: Weigh La(NO3)3·6H2O, Ca(NO3)2·4H2O, and Mn(NO3)3·4H2O in a molar ratio of 0.8:0.2:1, dissolve them in distilled water, and sonicate for 4 hours. Then add citric acid and ethylene glycol in a molar ratio of 1:2:2 (metal ion: citric acid: ethylene glycol), and continue sonicating until the citric acid is completely dissolved. Adjust the pH of the solution to 9 using ammonia water, and freeze-dry to obtain a gel. Pre-calcine the gel in a muffle furnace at 200℃ for 3 hours, then continue calcining at 1000℃ for 3 hours. After grinding, obtain La. 0.8 Ca 0.2 MnO3 powder.

[0054] S2: Weigh the above La 0.8 Ca 0.2 MnO3 powder and 8% glucose (by mass) were added to deionized water and ultrasonically dispersed for 8 hours. The mixture was then placed in a polytetrafluoroethylene hydrothermal reactor and reacted at 180°C for 8 hours in a homogeneous reactor. The product was then filtered and washed with anhydrous ethanol and deionized water, and dried under vacuum at 60°C for 12 hours. The dried product was then carbonized in a tube furnace under a nitrogen atmosphere at a heating rate of 5°C / min and held at 400°C for 7 hours. The carbonized product was then passed through a 200-mesh sieve to obtain carbon-coated perovskite La. 0.8 Ca 0.2 MnO3 / C materials.

[0055] Example 2:

[0056] S1: Weigh La(NO3)3·6H2O, Ca(NO3)2·4H2O, and Mn(NO3)3·4H2O in a molar ratio of 0.9:0.1:1, dissolve them in distilled water, and sonicate for 3 hours. Then, add citric acid and ethylene glycol in a molar ratio of 1:2:2 (metal ions: citric acid: ethylene glycol), and continue sonicating until the citric acid is completely dissolved. Adjust the pH of the solution to 10 using ammonia water, and freeze-dry to obtain a gel. Pre-calcine the gel in a muffle furnace at 300℃ for 4 hours, then continue calcining at 1100℃ for 4 hours. After grinding, obtain La. 0.9 Ca 0.1 MnO3 powder.

[0057] S2: Weigh the above La 0.9 Ca 0.1MnO3 powder and 5% sucrose by mass were added to deionized water and ultrasonically dispersed for 6 hours. The mixture was then placed in a polytetrafluoroethylene hydrothermal reactor and reacted at 160°C for 10 hours in a homogeneous reactor. The product was then filtered and washed with anhydrous ethanol and deionized water, and vacuum dried at 60°C for 18 hours. The dried product was then carbonized in a tube furnace under a nitrogen atmosphere at a heating rate of 5°C / min and held at 500°C for 6 hours. The carbonized product was then passed through a 300-mesh sieve to obtain carbon-coated perovskite La. 0.9 Ca 0.1 MnO3 / C materials.

[0058] Example 3:

[0059] S1: Weigh La(NO3)3·6H2O, Ca(NO3)2·4H2O, and Mn(NO3)3·4H2O in a molar ratio of 0.7:0.3:1, dissolve them in distilled water, and sonicate for 4 hours. Then add citric acid and ethylene glycol in a molar ratio of 1:2:2 (metal ion: citric acid: ethylene glycol), and continue sonicating until the citric acid is completely dissolved. Adjust the pH of the solution to 10 using ammonia water, and freeze-dry to obtain a gel. Pre-calcine the gel in a muffle furnace at 250°C for 5 hours, then continue calcining at 1200°C for 4 hours. After grinding, obtain La. 0.7 Ca 0.3 MnO3 powder.

[0060] S2: Weigh the above La 0.7 Ca 0.3 MnO3 powder and 10% glucose (by mass) were added to deionized water and ultrasonically dispersed for 7 hours. The mixture was then placed in a polytetrafluoroethylene hydrothermal reactor and reacted at 200°C for 6 hours in a homogeneous reactor. The product was then filtered and washed with anhydrous ethanol and deionized water, and dried under vacuum at 60°C for 24 hours. The dried product was then carbonized in a tube furnace under a nitrogen atmosphere at a heating rate of 5°C / min and held at 600°C for 5 hours. The carbonized product was then passed through a 200-mesh sieve to obtain carbon-coated perovskite La. 0.7 Ca 0.3 MnO3 / C materials.

[0061] Example 4:

[0062] S1: Weigh La(NO3)3·6H2O, Ca(NO3)2·4H2O, and Mn(NO3)3·4H2O in a molar ratio of 0.6:0.4:1, dissolve them in distilled water, and sonicate for 6 hours. Then add citric acid and ethylene glycol in a molar ratio of 1:2:2 (metal ion: citric acid: ethylene glycol), and continue sonicating until the citric acid is completely dissolved. Adjust the pH of the solution to 8 using ammonia water, and freeze-dry to obtain a gel. Calcine the gel in a muffle furnace at 300℃ for 2 hours, then continue calcining at 1200℃ for 5 hours. After grinding, obtain La. 0.6 Ca 0.4 MnO3 powder.

[0063] S2: Weigh the above La 0.6 Ca 0.4 MnO3 powder and 6% glucose (by mass) were added to deionized water and ultrasonically dispersed for 6 hours. The mixture was then placed in a polytetrafluoroethylene hydrothermal reactor and reacted at 160°C for 6 hours in a homogeneous reactor. The product was then filtered and washed with anhydrous ethanol and deionized water, and vacuum dried at 60°C for 12 hours. The dried product was then carbonized in a tube furnace under a nitrogen atmosphere at a heating rate of 5°C / min and held at 400°C for 5 hours. The carbonized product was then passed through a 200-mesh sieve to obtain carbon-coated perovskite La. 0.6 Ca 0.4 MnO3 / C materials.

[0064] Comparative Example 1:

[0065] Based on Example 1, the phrase "after calcining at 1000°C for 3 hours" in step S1 is adjusted to "after calcining at 800°C for 3 hours".

[0066] Comparative Example 2:

[0067] Based on Example 2, the molar ratio of La(NO3)3·6H2O, Ca(NO3)2·4H2O, and Mn(NO3)3·4H2O was changed from 0.9:0.1:1 to 0.5:0.5:1.

[0068] Comparative Example 3:

[0069] Based on Example 3, carbon coating is not performed, i.e., step S2 is not performed.

[0070] Comparative Example 4:

[0071] Based on Example 4, the molar ratio of La(NO3)3·6H2O, Ca(NO3)2·4H2O, and Mn(NO3)3·4H2O was changed from 0.6:0.4:1 to 0.3:0.7:1.

[0072] Experimental Example 1:

[0073] 1. SEM morphology characterization

[0074] The La obtained in Example 4 0.6 Ca 0.4 SEM tests were performed on the MnO3 / C anode material, and the test results are as follows: Figure 1 As shown. By La 0.6 Ca 0.4 The SEM images of the MnO3 / C anode material show that the particles are uniformly distributed, and most particles exhibit clear boundaries. The SEM results of other embodiments are basically consistent with those of Example 4, and the SEM images will not be repeated here.

[0075] 2. Electrochemical performance testing

[0076] The negative electrode materials from Examples 1-4 and Comparative Examples 1-4 were assembled into simulated batteries A1, A2, A3, A4, B1, B2, B3, and B4.

[0077] Specific steps: Weigh the negative electrode material, acetylene black, and PVDF in a mass ratio of 6:3:1 and place them in an agate mortar. Mix and grind thoroughly for 30 minutes, then add an appropriate amount of NMP to form a paste. Spread the paste evenly onto copper foil. After drying at a constant temperature of 80℃ for 12 hours, cut the paste into 15mm diameter round pieces using a cutting machine and store for later use.

[0078] The simulated battery (Swagelok battery) was assembled in a Lab2000 glove box. Under an argon atmosphere, the electrode plates, separator, and lithium metal sheet were gradually loaded into the simulated battery. After adding 15-20 drops of 1.0-1.5 mol / L LiPF6 electrolyte, the simulated battery was encapsulated and further sealed with a sealing film. The assembled simulated battery was then allowed to stand in a 25°C constant temperature chamber for 12 hours before relevant tests were performed.

[0079] Rate performance test conditions: with a current density of 100-400 mA·g -1 The rate is increased, with a step size of 100 mA·g. -1 Finally, it returns to 100mA. g -1 Each current density was tested for 50 cycles, and the data are shown in Table 1.

[0080] Cyclic performance test conditions: voltage range 0-3V, number of cycles 800, data are shown in Table 2.

[0081] Table 1

[0082]

[0083] Table 2

[0084] Constant current charge and discharge <![CDATA[200mA·g -1 800-cycle capacity (mA·g) -1 )]]> Example 1 / A1 305.8 Example 2 / A2 284.5 Example 3 / A3 280.1 Example 4 / A4 291.7 Comparative Example 1 / B1 215.3 Comparative Example 2 / B2 240.2 Comparative Example 3 / B3 175.8 Comparative Example 4 / B4 234.6

[0085] As can be seen from Tables 1 and 2, the simulated batteries assembled with the negative electrode materials of Examples 1-4 of this application exhibit significantly better rate performance and cycle performance than the simulated batteries assembled with the negative electrode materials of the comparative examples. The reason for this is that the appropriate ratio of La and Ca ions improves their size distribution, effectively reducing the charge transfer resistance and enhancing the material's stability, thus strengthening lithium-ion diffusion. Simultaneously, carbon coating further improves conductivity and also enhances the material's cycle stability.

[0086] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A perovskite-type metal oxide lithium battery negative electrode material, characterized by, The core layer material has a chemical formula of La 1-x Ca x MnO3, 0.1≤x≤0.4, wherein the core layer material is obtained by dissolving raw materials of a lanthanum source, a calcium source and a manganese source in water, mixing them uniformly, adding citric acid and ethylene glycol for aging, adjusting the pH value to 8-10, and freeze-drying to form a gel, and then calcining the gel at 1000-1200°C; and the coating layer material is amorphous carbon.

2. The negative electrode material of claim 1, wherein, The amorphous carbon includes hard carbon and soft carbon.

3. The negative electrode material of claim 2, wherein, The carbon source of the hard carbon includes one or more than two of sugar, lignin, sawdust, bamboo shavings, coconut shell and nut shell.

4. The method of producing the negative electrode material according to claim 1, characterized by, The method comprises the following steps: A perovskite-type metal oxide LaCaMn1-xMxO3 (0.1≤x≤0.4) is synthesized by a sol-gel process using a lanthanum source, a calcium source, and a manganese source as raw materials and calcining at 1000-1200°C. 1-x Ca x MnO3, 0.1≤x≤0.4 The perovskite metal oxide is fully contacted with the carbon source of the amorphous carbon, and then carbonized to obtain a carbon-coated perovskite metal oxide lithium battery negative electrode material.

5. The preparation method according to claim 4, characterized in that, The sol-gel process is a citric acid sol-gel process, which comprises the following steps: La source, Ca source and Mn source raw materials are weighed according to a molar ratio of (0.6-0.9):(0.4-0.1):1, dissolved in water and mixed uniformly, citric acid and ethylene glycol are added for aging, the pH value is adjusted to 8-10, and after freeze-drying, a gel is formed, the gel is calcined to obtain a perovskite type metal oxide La 1-x Ca x MnO3, 0.1≤x≤0.

4.

6. The preparation method according to claim 4 or 5, characterized in that, The lanthanum source, calcium source and manganese source raw materials include nitrate salts of each metal and corresponding hydrates.

7. The preparation method according to claim 4, characterized in that, The carbon source of the amorphous carbon is added at 5-10% of the mass of the perovskite metal oxide.

8. A negative electrode sheet characterized by comprising: The negative electrode material of any one of claims 1-3 or prepared by the preparation method of any one of claims 4-7 is used as an active material.

9. A lithium battery, characterized by The method comprises the following steps: preparing a positive electrode sheet, a separator, an electrolyte and the negative electrode sheet of claim 8.

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