Lithium supplement material and preparation method thereof, lithium supplement pole piece, positive pole piece and battery

Abstract

The invention belongs to the technical field of battery materials, and particularly relates to a lithium supplement material and a preparation method thereof, a lithium supplement pole piece, a positive pole piece and a battery. The lithium supplementing material comprises a core body and a coating layer coating the core body, the core body comprises a lithium-rich material; the coating layer includes a metal compound and carbon. The lithium supplementing material provided by the invention has relatively high environmental stability, and is beneficial to improving the electrochemical performance of the battery.

Description

Technical Field

[0001] This invention belongs to the field of battery material technology, specifically relating to a lithium replenishment material and its preparation method, a positive electrode sheet, a battery, and an electrical device. Background Technology

[0002] Lithium-ion batteries have been widely commercialized due to their advantages such as good safety performance, long cycle life, high specific energy, and lightweight and high efficiency. However, during the first charge and discharge process, the irreversible loss of active lithium due to the formation of the SEI film leads to a decrease in coulombic efficiency and a reduction in battery cycle life. Adding lithium-rich materials to the positive electrode is a safe and simple method for lithium replenishment, which can improve the battery's energy density and cycle performance.

[0003] Lithium-rich materials, due to their lithium ion content, have poor environmental stability and are sensitive to water and CO2. When exposed to water and CO2, they react to form impurities such as LiOH and Li2CO3, leading to deactivation during use. The high alkalinity of deactivated lithium-rich materials not only causes excessively high viscosity in the cathode slurry, increasing the risk of gelation and hindering coating and sheet fabrication, but also makes them prone to side reactions when used for battery lithium replenishment, resulting in suboptimal battery performance. Summary of the Invention

[0004] The present invention aims to at least partially solve the aforementioned technical problems. Therefore, one object of the present invention is to provide a lithium-supplementing material and a method for preparing the same, a positive electrode, a battery, and an electrical device.

[0005] A first aspect of this application provides a lithium replenishment material. According to an embodiment of this application, the lithium replenishment material includes a core and a coating layer covering the core; the core includes a lithium-rich material; the coating layer includes a metal compound and carbon.

[0006] The lithium replenishment material provided in this application exhibits high environmental stability, which is beneficial for improving the electrochemical performance of the battery. In this lithium replenishment material, a coating layer is applied to the outer surface of the lithium-rich material, and the coating layer includes a metal compound and carbon. During the preparation process, the metal compound is less likely to undergo side reactions with the lithium-rich material, thus ensuring that the lithium-rich material maintains high purity and improving the lithium replenishment effect. Carbon has high chemical stability, which can further isolate water and CO2 from contact with the lithium-rich material, increasing the effectiveness of the lithium replenishment material. Furthermore, the lithium replenishment material provided in this application has no risk of gelation during electrode preparation, facilitating smooth coating.

[0007] According to embodiments of this application, the above-mentioned lithium replenishment material may further include at least one of the following additional technical features:

[0008] In some embodiments, the moisture absorption rate M of the lithium replenishment material satisfies 0 < M ≤ 17; the unit is ppm / s.

[0009] In some embodiments, the relationship between the particle size D of the lithium replenishment material, the mass content X of the metal element in the coating layer, and the carbon content C in the coating layer satisfies equation (1):

[0010] 0 < -0.127*D 10 +0.65*D 50 -0.404*D 99 -1.185*C+0.000636*X≤17(1); where, D 10 The particle size D of the lithium supplement material is indicated. 10 The unit is μm; D 50 The particle size D of the lithium supplement material is indicated. 50 The unit is μm; D 99 The particle size D of the lithium supplement material is indicated. 99 The unit is μm; C represents the carbon content in the coating layer calculated based on the total mass of the lithium replenishing material, in wt%; X represents the mass content of metal elements in the coating layer calculated based on the total mass of the lithium replenishing material, in ppm.

[0011] In some embodiments, the lithium replenishment material satisfies at least one of the following (1) to (5):

[0012] (1) Particle size D of lithium supplementation material 10 Satisfy: 0 < D 10 ≤5μm;

[0013] (2) Particle size D of lithium supplementation material 50 Satisfying: 5μm≤D 50 ≤12μm;

[0014] (3) Particle size D of lithium supplementation material 99 Satisfying: 15μm≤D 99 ≤25μm;

[0015] (4) Based on the total mass of the lithium replenishment material, the mass content X of the metal element in the coating layer satisfies: 0

[0016] <X≤27000ppm;

[0017] (5) Based on the overall mass of the lithium replenishment material, the carbon content C in the coating layer satisfies: 0 < C ≤ 5 wt%.

[0018] In some embodiments, the coating layer includes a first coating layer and a second coating layer; the second coating layer is disposed on the outer surface of the first coating layer, the first coating layer includes a metal compound layer; the second coating layer includes a carbon layer.

[0019] In some embodiments, the lithium-rich material in the core includes at least one of Li5FeO4, Li2NiO2, and LiCoO2; and / or, the metal element in the metal compound layer includes at least one of Al, Ti, Mg, Zr, and Zn.

[0020] In some implementations, the lithium-rich material includes Li5FeO4.

[0021] The second aspect of this application provides a method for preparing the lithium supplementation material of the first aspect, comprising:

[0022] Lithium-supplementing materials are prepared using raw materials for the core and the coating layer. The lithium-supplementing material includes a core and a coating layer covering the core. The core includes lithium-rich materials. The coating layer includes metal compounds and carbon.

[0023] The lithium supplementation material prepared in this application has high environmental stability, which is beneficial to improving the electrochemical performance of the battery.

[0024] In some embodiments, the method for preparing lithium-supplementing materials uses raw materials for the core and the coating layer to prepare the lithium-supplementing materials, including:

[0025] A lithium supplement material precursor is prepared using raw materials from the core and the first coating layer. The lithium supplement material precursor includes a core and a first coating layer covering the core.

[0026] A second coating layer is prepared outside the first coating layer to obtain a lithium-replenishing material. The lithium-replenishing material includes a core and a first coating layer and a second coating layer sequentially coating the core. The core includes a lithium-rich material. The first coating layer includes a metal compound layer. The second coating layer includes a carbon layer.

[0027] In some embodiments, the method for preparing the lithium-supplementing material includes:

[0028] Methods for preparing lithium supplementation material precursors include solid-phase or wet methods; and / or, methods for preparing the second coating layer include vapor deposition.

[0029] In some embodiments, the step of preparing a lithium supplement material precursor using raw materials from the core and the first coating layer includes: mixing, grinding, granulating, sintering once, and pulverizing the raw materials from the core and the first coating layer to obtain the lithium supplement material precursor.

[0030] In some embodiments, the primary pulverization method includes primary airflow pulverization, with a power of 50 kW to 150 kW.

[0031] In some embodiments, the raw materials of the core include a lithium source and a metal source; the metal source includes at least one of an iron source, a manganese source, a nickel source, a cobalt source, and a vanadium source; the raw materials of the first coating layer include at least one of an aluminum source, a titanium source, a magnesium source, a zirconium source, and a zinc source.

[0032] In some embodiments, the molar ratio of lithium source, metal source and metal source in the first coating layer is 5:1:(0.01 to 0.05).

[0033] In some embodiments, the step of preparing a second coating layer outside the first coating layer includes: depositing a carbon layer in vitro in front of the lithium replenishing material, followed by secondary sintering and secondary pulverization to obtain the lithium replenishing material.

[0034] In some embodiments, the control parameters in the step of preparing the second coating layer outside the first coating layer include at least one of the following:

[0035] (a) The secondary grinding method includes secondary airflow grinding, and the power of the secondary airflow grinding is 50kw to 150kw;

[0036] (b) In the method of vapor deposition of carbon layer: the carbon source includes organic carbon source; the content of carbon source is ≤10ppm; the ventilation time is 7h to 12h.

[0037] A third aspect of this application provides a positive electrode sheet, comprising the above-described lithium replenishment material, or the lithium replenishment material obtained by the above-described preparation method.

[0038] The positive electrode provided in this application embodiment uses the above-mentioned lithium-supplementing material as a lithium-supplementing agent, exhibiting good stability and electrochemical performance.

[0039] In some embodiments, the positive electrode sheet also includes a positive electrode material, and the mass ratio of the lithium supplement material to the positive electrode material is 1:99 to 8:92.

[0040] In some implementations, the cathode material includes lithium iron phosphate.

[0041] A fourth aspect of this application provides a battery including the above-described positive electrode.

[0042] The battery provided in this application exhibits good electrochemical performance, with high capacity and long cycle life.

[0043] A fifth aspect of this application provides an electrical device including the battery described above.

[0044] The electrical equipment provided in this application has excellent performance.

[0045] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0046] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0047] Figure 1 The SEM image of the lithium-replenishing electrode before it is placed in the environment is provided in Example 2 of this application.

[0048] Figure 2 The SEM image of the lithium-filled electrode after it has been placed in place, provided in Example 2 of this application.

[0049] Figure 3 The SEM image of the lithium-filled electrode before it was placed in Comparative Example 1 of this application is provided.

[0050] Figure 4 The SEM image of the lithium-filled electrode after it has been left to stand, provided in Comparative Example 1 of this application. Detailed Implementation

[0051] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0052] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0053] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0054] In this document, the terms “comprising” or “including” are open-ended expressions, meaning that they include the contents specified in this invention, but do not exclude other aspects.

[0055] In this document, the terms “optionally,” “optionally,” or “optionally” generally refer to a subsequent event or condition that may but may not occur, and the description includes both cases in which the event or condition occurs and cases in which the event or condition does not occur.

[0056] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0057] The first aspect of this application provides a lithium replenishment material, including a core and a coating layer covering the core;

[0058] The core consists of lithium-rich materials; the coating consists of metal compounds and carbon.

[0059] The lithium replenishment material provided in this application exhibits high environmental stability, which is beneficial for improving the electrochemical performance of the battery. In this lithium replenishment material, a coating layer is applied to the outer surface of the lithium-rich material, and the coating layer includes a metal compound and carbon. During the preparation process, the metal compound is less likely to undergo side reactions with the lithium-rich material, thus ensuring that the lithium-rich material maintains high purity and improving the lithium replenishment effect. Carbon has high chemical stability, which can further isolate water and CO2 from contact with the lithium-rich material, increasing the effectiveness of the lithium replenishment material. Furthermore, the lithium replenishment material provided in this application has no risk of gelation during electrode preparation, facilitating smooth coating.

[0060] In some embodiments, the moisture absorption rate M of the lithium replenishment material satisfies 0 < M ≤ 17; the unit is ppm / s. M represents the amount of water absorbed by the lithium replenishment material per unit time when placed in the environment, to assess the environmental stability of the lithium replenishment material. When the lithium replenishment material is exposed to air for a certain period of time, materials with large mass changes have poor environmental stability, while materials with small mass changes have high environmental stability. M meeting the above range can effectively reduce side reactions of the lithium replenishment material, which is beneficial to improving battery capacity and cycle life, thereby enabling the battery to obtain good electrochemical performance.

[0061] Test method for the moisture absorption rate M of lithium replenishment material: Weigh M0g of lithium replenishment material using an analytical balance in a constant temperature and humidity chamber at 25℃ and 45% humidity, and record the weight M of the lithium replenishment material after 40 minutes. 40 g. The moisture absorption rate of the lithium replenishment material M = 10000 * (M 40 -M0) / M0 / (40*60), unit is ppm / s; where M 40 M0 represents the mass of the lithium replenishment material after 40 minutes of exposure, in g; M0 represents the initial mass of the lithium replenishment material, in g.

[0062] In some embodiments, the relationship between the particle size D of the lithium replenishment material, the mass content X of the metal element in the coating layer, and the carbon content C in the coating layer satisfies equation (1):

[0063] 0 < -0.127*D 10 +0.65*D 50 -0.404*D 99 -1.185*C+0.000636*X≤17(1); In formula (1), D10 represents the particle size D of the lithium replenishment material. 10 The unit is μm; D 50 The particle size D of the lithium supplement material is indicated. 50 The unit is μm; D 99 The particle size D of the lithium supplement material is indicated. 99 The unit is μm; C represents the carbon content in the coating layer calculated based on the total mass of the lithium replenishing material, in wt%; X represents the mass content of metal elements in the coating layer calculated based on the total mass of the lithium replenishing material, in ppm.

[0064] The inventors of this application, through extensive experiments, discovered a certain relationship between the physical properties of lithium-supplementing materials and their stability. Specifically, the particle size D, the mass content X of the metal element in the coating layer, and the carbon content C in the coating layer of the lithium-supplementing material satisfy: -0.127 * D 10 +0.65*D 50 -0.404*D 99 The relation is -1.185*C + 0.000636*X, and 0 < -0.127*D. 10 +0.65*D 50 -0.404*D 99 When -1.185*C+0.000636*X≤17, the lithium-rich material coating effect is better. It can not only effectively isolate the internal lithium-rich material from the external water and CO2, but also effectively alleviate the direct contact between the electrolyte and the lithium-rich material, reducing the occurrence of side reactions. At the same time, it also has high electronic conductivity and structural strength. When combined with positive electrode active material, it can improve the discharge capacity and improve the battery cycle performance.

[0065] In some embodiments, the lithium replenishment material provided in this application satisfies at least one of the following (1) to (5):

[0066] (1) Particle size D of lithium supplementation material 10 Satisfy: 0 < D 10 ≤5μm;

[0067] (2) Particle size D of lithium supplementation material 50 Satisfying: 5μm≤D 50 ≤12μm;

[0068] (3) Particle size D of lithium supplementation material 99 Satisfying: 15μm≤D 99 ≤25μm;

[0069] (4) Based on the overall mass of the lithium replenishment material, the mass content X of the metal element in the coating layer satisfies: 0 < X ​​≤ 27000 ppm;

[0070] (5) Based on the overall mass of the lithium replenishment material, the carbon content C in the coating layer satisfies: 0 < C ≤ 5 wt%.

[0071] Lithium supplement material particle size D 10 D 50 and D 99 The processing of the electrode sheet will affect the use of the lithium replenishment material. In the embodiments of this application, the particle size D of the lithium replenishment material is... 10 D 50 and D 99 Meeting the above conditions helps to avoid abnormal phenomena such as slurry problems and uneven coating during use.

[0072] In this embodiment, the mass content X of the metal element in the coating layer meets the above conditions, which is beneficial to obtaining a higher cell capacity and at the same time avoids the safety hazards caused by the subsequent gas generation risk of the cell.

[0073] In this embodiment, the carbon content C in the coating layer meets the above conditions, which is beneficial to obtaining high conductivity and ensuring the lithium ion transport process during charging and discharging.

[0074] In a specific example, the particle size D of the lithium replenishment material 10 The sizes are 0.1μm, 0.5μm, 1μm, 2μm, 3μm, 4μm, or 5μm, etc.

[0075] In a specific example, the particle size D of the lithium replenishment material 50 The sizes are 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, or 12μm, etc.

[0076] In a specific example, the particle size D of the lithium replenishment material 99 The sizes are 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, or 25μm, etc.

[0077] In specific examples, the mass content X of the metal element in the coating layer is 1ppm, 100ppm, 1000ppm, 5000ppm, 10000ppm, 15000ppm, 18000ppm, 21000ppm, 25000ppm, or 27000ppm, etc., calculated based on the overall mass of the lithium replenishment material.

[0078] In specific examples, the carbon content C in the coating layer is 0.1wt%, 1wt%, 2wt%, 3wt%, 4wt%, or 5wt%, etc., calculated based on the overall mass of the lithium replenishment material.

[0079] By further designing various physicochemical parameters, it is beneficial for lithium replenishment materials to maintain high environmental stability and electrochemical performance.

[0080] Particle size testing method for lithium replenishment materials: The particle size of the lithium replenishment materials was determined using a Malvern dry particle size analyzer, where D... 10 D 50 D 99 These are the particle sizes corresponding to the cumulative volume percentage of material particles reaching 10%, 50%, and 99%, respectively, in μm.

[0081] Test method for carbon content in the coating layer of lithium supplementation material: The carbon content in the sample is obtained by detecting the CO2 concentration during the combustion of the lithium supplementation material using a carbon-sulfur analyzer, expressed as a percentage.

[0082] Method for detecting metal elements in the coating layer of lithium replenishment material: After digesting the lithium replenishment material with hydrochloric acid at 250℃ for 20 minutes, the metal element content was detected by ICP-AES instrument, and the unit was ppm.

[0083] In some embodiments, the lithium-replenishing material includes a core and a first coating layer and a second coating layer sequentially covering the core; the core includes a lithium-rich material; the first coating layer includes a metal compound layer; and the second coating layer includes a carbon layer.

[0084] The lithium replenishment material provided in this application embodiment exhibits high environmental stability, which is beneficial for improving the electrochemical performance of the battery. The lithium replenishment material provided in this application embodiment is a three-phase, double-coated lithium replenishment material. The core is a highly active lithium-rich material, the inner layer is a metal compound coating layer, and the outer layer is a carbon coating layer. The metal compound layer (first coating layer), as the inner coating layer, directly contacts the lithium-rich material. During the preparation process, it is less likely to undergo side reactions with the lithium-rich material, thus ensuring that the lithium-rich material maintains high purity. The carbon layer has high environmental stability and, as the second coating layer, coats the outer surface of the metal compound layer, further isolating the lithium-rich material from water and CO2 in the environment, thus improving the performance of the lithium replenishment material. Furthermore, the lithium replenishment material provided in this application embodiment has good environmental stability and eliminates the risk of gelation during electrode preparation.

[0085] In some embodiments, the lithium-rich material in the core includes at least one of Li5FeO4, Li2NiO2, and LiCoO2; and / or, the metal element in the coating layer includes at least one of Al, Ti, Mg, Zr, and Zn.

[0086] The coating layer includes at least one of magnesium oxide (MgO), aluminum oxide (Al2O3), titanium oxide (TiO2), zirconium oxide (ZrO2), and zinc oxide (ZnO).

[0087] These lithium-rich materials are beneficial for improving the lithium replenishment effect of batteries. The metal elements in the coating layer, including the aforementioned elements, can enhance the electrochemical performance of the battery.

[0088] In some implementations, the lithium-rich material includes Li5FeO4.

[0089] The second aspect of this application provides a method for preparing a lithium supplement material, comprising:

[0090] Lithium-supplementing materials are prepared using raw materials for the core and the coating layer. The lithium-supplementing material includes a core and a coating layer covering the core. The core includes lithium-rich materials. The coating layer includes metal compounds and carbon.

[0091] The lithium supplementation material prepared in this application has high environmental stability, which is beneficial to improving the electrochemical performance of the battery.

[0092] In some embodiments, the method for preparing lithium-supplementing materials uses raw materials for the core and the coating layer to prepare the lithium-supplementing materials, including:

[0093] A lithium supplement material precursor is prepared using raw materials from the core and the first coating layer. The lithium supplement material precursor includes a core and a first coating layer covering the core.

[0094] A second coating layer is prepared outside the first coating layer to obtain a lithium-replenishing material. The lithium-replenishing material includes a core and a first coating layer and a second coating layer sequentially coating the core. The core includes a lithium-rich material. The first coating layer includes a metal compound layer. The second coating layer includes a carbon layer.

[0095] The method for preparing lithium-supplementing materials provided in this application is simple in synthesis, has a short processing time, reduces product costs, and produces a uniform coating layer, which is beneficial for improving the environmental stability of the lithium-supplementing materials.

[0096] In some embodiments, the methods for preparing lithium supplementation material precursors using raw materials from the core and the first coating layer include wet and solid-phase methods.

[0097] The preparation method provided in this embodiment is simple to synthesize, has low cost, and produces a uniform and dense first coating layer.

[0098] In some embodiments, the method for preparing the second coating layer includes vapor deposition.

[0099] The preparation method provided in this embodiment is simple to synthesize, has low cost, and produces a uniform and dense second coating layer.

[0100] In some embodiments, the step of preparing the lithium supplementation material precursor includes:

[0101] The raw materials of the core and the first coating layer are mixed, ground, granulated, sintered once, and crushed once to obtain the lithium supplement material precursor.

[0102] In some embodiments, the primary pulverization method includes primary airflow milling, with a power of 50 kW to 150 kW. The material obtained by primary airflow milling has an irregular morphology, which is beneficial for obtaining lithium-supplementing materials with suitable particle size. As examples, the power of primary airflow milling is 50 kW, 55 kW, 60 kW, 65 kW, 70 kW, 75 kW, 80 kW, 85 kW, 90 kW, 95 kW, 100 kW, 105 kW, 110 kW, 115 kW, 120 kW, 125 kW, 130 kW, 135 kW, 140 kW, 145 kW, 150 kW, etc.

[0103] Furthermore, the sintering process is carried out in an oxygen-rich atmosphere.

[0104] Furthermore, the sintering temperature is 700℃~900℃, and the sintering time is 6h~10h.

[0105] Controlling the above preparation process is beneficial to obtaining lithium supplementation materials with suitable particle size.

[0106] In some embodiments, the raw materials of the core include a lithium source and a metal source; the metal source includes at least one of an iron source, a manganese source, a nickel source, a cobalt source, and a vanadium source; the raw materials of the first coating layer include at least one of an aluminum source, a titanium source, a magnesium source, a zirconium source, and a zinc source.

[0107] In some embodiments, the molar ratio of the lithium source, the metal source, and the metal source in the first coating layer is 5:1:(0.01 to 0.05). As examples, the molar ratios of the lithium source, the metal source, and the metal source in the first coating layer are 5:1:0.01, 5:1:0.02, 5:1:0.03, 5:1:0.04, 5:1:0.05, etc.

[0108] In some embodiments, the lithium source includes at least one of LiOH, Li2CO3, and Li2O.

[0109] In some implementations, the iron source includes Fe2O3.

[0110] In some embodiments, the raw material for the first coating layer is at least one selected from aluminum isopropoxide, tetrabutyl titanate, magnesium oxide (MgO), aluminum oxide (Al2O3), titanium oxide (TiO2), zirconium oxide (ZrO2), and zinc oxide (ZnO).

[0111] In some embodiments, the above-described lithium replenishing material is prepared by the above-described method for preparing the lithium replenishing material.

[0112] Controlling the above preparation process is beneficial to obtaining lithium-supplementing materials with uniform metal compounds and carbon coating and appropriate particle size.

[0113] In some embodiments, the step of preparing a second coating layer outside the first coating layer includes:

[0114] A carbon layer is deposited in vitro before the lithium replenishment material is prepared, followed by secondary sintering and secondary pulverization to obtain the lithium replenishment material.

[0115] The control parameters in the step of preparing the second coating layer outside the first coating layer include at least one of the following:

[0116] (a) The secondary grinding method includes secondary airflow grinding, and the power of the secondary airflow grinding is 50kw to 150kw;

[0117] (a) In the method of vapor deposition of carbon layer: the carbon source includes organic carbon source; the content of carbon source is ≤10ppm; the ventilation time is 7h to 12h.

[0118] In this embodiment, after the secondary sintering process, a secondary pulverization process is performed to obtain lithium-supplementing material with the target particle size. Furthermore, the secondary pulverization method includes secondary airflow pulverization. The power of the secondary airflow pulverization is 50 kW to 150 kW. As examples, the power of the secondary airflow pulverization is 50 kW, 55 kW, 60 kW, 65 kW, 70 kW, 75 kW, 80 kW, 85 kW, 90 kW, 95 kW, 100 kW, 105 kW, 110 kW, 115 kW, 120 kW, 125 kW, 130 kW, 135 kW, 140 kW, 145 kW, 150 kW, etc.

[0119] In the embodiments, the method for vapor-phase deposition of carbon layers includes: the carbon source comprising an organic carbon source; and vapor-phase deposition performed under an inert atmosphere. The carbon source content is ≤10 ppm; the aeration time is 7 h to 12 h. Controlling the above preparation process is beneficial for obtaining lithium supplementation materials with suitable carbon content. As examples, the carbon source content is 10 ppm, 9 ppm, 8 ppm, 7 ppm, 6 ppm, 5 ppm, 4 ppm, 3 ppm, 2 ppm, 1 ppm, etc. As examples, the aeration time is 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, etc.

[0120] Furthermore, the vapor deposition temperature (i.e., the secondary sintering temperature) is 500℃~1000℃, and the time is 7h~12h.

[0121] Furthermore, the organic carbon source includes at least one of methane, ethane, ethylene, and acetylene.

[0122] A third aspect of the embodiments of this application provides a lithium-replenishing electrode, comprising the lithium-replenishing material described above, or the lithium-replenishing material obtained by the preparation method described above.

[0123] The lithium-filled electrode provided in this application embodiment has high stability and exhibits high stability when exposed to air with a certain humidity.

[0124] The lithium-replenishing electrode provided in this application showed no change in SEM morphology after being placed in a constant temperature and humidity chamber at 25°C and 45% for 48 hours, indicating good stability.

[0125] In some embodiments, the lithium-supplementing electrode contains lithium-supplementing material at a mass percentage of 1% to 98%. The raw materials for the lithium-supplementing electrode include not only the lithium-supplementing material but also components such as binders, conductive agents, and solvents. Specific examples show that the mass percentage of the lithium-supplementing material is 1%, 5%, 10%, 21%, 32%, 43%, 54%, 65%, 76%, 87%, 98%, etc.

[0126] The fourth aspect of this application provides a positive electrode sheet comprising the above-described lithium replenishment material, or comprising the lithium replenishment material obtained by the above-described preparation method.

[0127] The positive electrode provided in this application embodiment uses the above-mentioned lithium-supplementing material as a lithium-supplementing agent, exhibiting good stability and electrochemical performance.

[0128] The positive electrode provided in this application showed no change in the SEM morphology of the lithium-added material after being placed in a constant temperature and humidity chamber at 25°C and 45% for 48 hours, indicating good stability.

[0129] In some embodiments, the positive electrode sheet further comprises a positive electrode material, and the mass ratio of the lithium replenishment material to the positive electrode material is 1:99 to 8:92; further, the mass ratio of the lithium replenishment material to the positive electrode material is 1:99 to 8:92, and the sum of the first and second terms of the ratio is 100. In specific examples, the mass ratio of the lithium replenishment material to the positive electrode material is 1:99, 2:98, 3:97, 4:96, 5:95, 6:94, 7:93, 8:92, etc.

[0130] When the proportion of lithium-added material is too high, problems such as low battery energy density, increased cost, increased battery weight, and severe gas production will occur; while when the proportion of lithium-added material is too low, problems such as insignificant improvement in battery capacity and cycle life will occur. In the embodiments of this application, the mass ratio of lithium-added material to cathode material meets the above conditions, which is beneficial to improving the electrochemical performance and safety performance of the battery.

[0131] In some implementations, the cathode material includes lithium iron phosphate.

[0132] The embodiments of this application can be used for cathode materials in lithium iron phosphate (LFP) systems. For example, LFP batteries suffer from excessive lithium loss during the first charge-discharge cycle. This occurs because lithium in the cathode undergoes irreversible side reactions on the anode surface, forming a solid electrolyte interphase (SEI) layer. This SEI layer cannot return to the cathode during subsequent discharge, leading to irreversible reduction in battery capacity, shortened cycle life, and decreased first-cycle efficiency. When using high-specific-capacity silicon-based composite anode materials, lithium consumption in the cathode material is further exacerbated. Therefore, it is necessary to replenish the battery with a lithium source to compensate for the irreversible consumption of active lithium in the cathode.

[0133] In this application embodiment, the cathode material includes lithium iron phosphate, and the lithium supplementation material includes lithium iron phosphate. Together, they improve the electrochemical and safety performance of the battery. This is due to: ① Complementary chemical properties: Lithium iron phosphate has a high theoretical specific capacity and a fast ion diffusion rate, but it lacks good rate performance and high energy density. Lithium iron phosphate has a lower specific capacity but possesses very high thermal stability and good cycle life, and is highly safe. Combining the two can compensate for each other's weaknesses, improving the battery's energy density while maintaining good safety and cycle stability. ② Cost-effectiveness: Compared to the preparation and use costs of single materials, composite materials can achieve improved cost-effectiveness through optimized formulation. Lithium iron phosphate has a relatively low cost, which can help reduce the overall battery cost. ③ Market and application demands: Electric vehicles and other energy storage applications have high requirements for battery safety and cycle life. Lithium iron phosphate is the preferred choice due to its excellent safety. Simultaneously, with the increasing demands for electric vehicle range, adding lithium iron phosphate to improve the energy density of lithium iron phosphate has achieved certain results.

[0134] In some embodiments, the positive electrode material also includes materials such as binders and conductive agents.

[0135] In some embodiments, a positive electrode slurry is prepared using a binder (such as PVDF), a conductive agent (such as CNT), a solvent (such as NMP), a positive electrode material (such as LFP), and the aforementioned lithium supplementation material, and then coated to prepare a positive electrode sheet. A full cell prepared using this positive electrode sheet...

[0136] The fifth aspect of this application provides a battery including the above-described positive electrode sheet.

[0137] Batteries prepared using the lithium-replenishing materials provided in the embodiments of this application have high capacity and long cycle life, exhibiting excellent electrochemical performance.

[0138] A sixth aspect of this application provides an electrical device including the battery described above.

[0139] The electrical equipment provided in this application has excellent performance.

[0140] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the invention in any way. The reagents used in the embodiments are all from Aladdin Biochemical Technology Co., Ltd.

[0141] Example 1

[0142] This embodiment provides a lithium supplementation material C@Al2O3@Li5FeO4, and the specific preparation method is shown below:

[0143] Step 1: Weigh out lithium source Li2O, iron source Fe2O3, and aluminum isopropoxide (5:1:0.03) according to the molar stoichiometric ratio, mix them evenly, and then grind them. The grinding power is 3.5 kWh / kg.

[0144] Step 2: The ground powder is placed in an atmosphere furnace for primary sintering. The atmosphere is oxygen, and the primary sintering temperature is set to 800℃ for 9 hours. The material after primary sintering is then subjected to primary airflow pulverization to obtain Al2O3@Li5FeO4; the primary airflow pulverization power is 60 kW.

[0145] Step 3: The Al2O3@Li5FeO4 material after primary pulverization is placed in a protective atmosphere furnace for secondary sintering. The protective atmosphere is nitrogen, and acetylene gas is introduced during the process. The acetylene content in the sintering furnace is ≤10ppm, the gas introduction time is 9 hours, the sintering temperature is 700℃, and the sintering time is 8 hours. The material after secondary sintering is pulverized by a secondary airflow to obtain the lithium-supplementing material C@Al2O3@Li5FeO4. The secondary airflow pulverization power is 100kW.

[0146] Example 2

[0147] This embodiment provides a lithium supplementation material C@TiO2@Li5FeO4, and the specific preparation method is shown below:

[0148] Step 1: Weigh out lithium source Li2O, iron source Fe2O3, and tetrabutyl titanate (5:1:0.05) according to the molar stoichiometric ratio, mix them evenly, and then grind them. The grinding power is 3.5 kWh / kg.

[0149] Step 2: The ground powder is placed in an atmosphere furnace for primary sintering. The atmosphere is oxygen, and the sintering temperature of the primary sintering section is set to 800℃ for 7 hours. The material after primary sintering is then subjected to primary airflow pulverization to obtain TiO2@Li5FeO4. The primary airflow pulverization power is 70 kW.

[0150] Step 3: The TiO2@Li5FeO4 material after primary pulverization is placed in a protective atmosphere furnace for secondary sintering. The protective atmosphere is nitrogen, and ethylene gas is introduced during the process. The ethylene content in the sintering furnace is less than or equal to 10 ppm, the gas introduction time is 10 hours, the sintering temperature is set to 700℃, and the sintering time is 9 hours. After secondary sintering, the material is pulverized by a secondary gas flow to obtain the lithium-supplementing material C@TiO2@Li5FeO4. The secondary gas flow pulverization power is 110 kW.

[0151] Example 3

[0152] This embodiment provides a lithium supplementation material C@Al2O3@Li5FeO4, and the specific preparation method is shown below:

[0153] Step 1: Weigh out lithium source Li2O, iron source Fe2O3, and aluminum isopropoxide (5:1:0.025) according to the molar stoichiometric ratio, mix them evenly, and then grind them. The grinding power is 3.5 kWh / kg.

[0154] Step 2: The ground powder is placed in an atmosphere furnace for primary sintering. The atmosphere is oxygen, and the primary sintering temperature is set to 800℃ for 9 hours. The material after primary sintering is then subjected to primary airflow pulverization to obtain Al2O3@Li5FeO4. The primary airflow pulverization power is 65 kW.

[0155] Step 3: The Al2O3@Li5FeO4 material after primary pulverization is placed in a protective atmosphere furnace for secondary sintering. The protective atmosphere is nitrogen, and acetylene gas is introduced during the process. The acetylene content in the sintering furnace is ≤10ppm, the gas introduction time is 11h, the sintering temperature is 700℃, and the sintering time is 10h. The material after secondary sintering is pulverized by a secondary airflow to obtain the lithium-supplementing material C@Al2O3@Li5FeO4. The secondary airflow pulverization power is 120kW.

[0156] Example 4

[0157] This embodiment provides a lithium supplementation material C@Al2O3@Li5FeO4, and the specific preparation method is shown below:

[0158] Step 1: Weigh out lithium source Li2O, iron source Fe2O3, and aluminum isopropoxide (5:1:0.02) according to the molar stoichiometric ratio, mix them evenly, and then grind them. The grinding power is 3.5 kWh / kg.

[0159] Step 2: The ground powder is placed in an atmosphere furnace for primary sintering. The atmosphere is oxygen, and the primary sintering temperature is set to 800℃ for 9 hours. The material after primary sintering is then subjected to primary airflow pulverization to obtain Al2O3@Li5FeO4. The primary airflow pulverization power is 80 kW.

[0160] Step 3: The Al2O3@Li5FeO4 material after primary pulverization is placed in a protective atmosphere furnace for secondary sintering. The protective atmosphere is nitrogen, and acetylene gas is introduced during the process. The acetylene content in the sintering furnace is ≤10ppm, the gas introduction time is 9 hours, the sintering temperature is 700℃, and the sintering time is 8 hours. The material after secondary sintering is pulverized by a secondary airflow to obtain the lithium-supplementing material C@Al2O3@Li5FeO4. The secondary airflow pulverization power is 125kW.

[0161] Example 5

[0162] This embodiment provides a lithium supplementation material C@Al2O3@Li5FeO4, and the specific preparation method is shown below:

[0163] Step 1: Weigh out lithium source Li2O, iron source Fe2O3, and aluminum isopropoxide (5:1:0.04) according to the molar stoichiometric ratio, mix them evenly, and then grind them. The grinding power is 3.5 kWh / kg.

[0164] Step 2: The ground powder is placed in an atmosphere furnace for primary sintering. The atmosphere is oxygen, and the primary sintering temperature is set to 800℃ for 9 hours. The material after primary sintering is then subjected to primary airflow pulverization to obtain Al2O3@Li5FeO4. The primary airflow pulverization power is 70 kW.

[0165] Step 3: The Al2O3@Li5FeO4 material after primary pulverization is placed in a protective atmosphere furnace for secondary sintering. The protective atmosphere is nitrogen, and acetylene gas is introduced during the process. The acetylene content in the sintering furnace is ≤10ppm, the gas introduction time is 10h, the sintering temperature is 700℃, and the sintering time is 9h. The material after secondary sintering is pulverized by a secondary airflow to obtain the lithium-supplementing material C@Al2O3@Li5FeO4. The secondary airflow pulverization power is 70kW.

[0166] Example 6

[0167] This embodiment provides a lithium supplementation material C@TiO2@Li5FeO4, and the specific preparation method is shown below:

[0168] Step 1: Weigh out lithium source Li2O, iron source Fe2O3, and tetrabutyl titanate (5:1:0.04) according to the molar stoichiometric ratio, mix them evenly, and then grind them. The grinding power is 3.5 kWh / kg.

[0169] Step 2: The ground powder is placed in an atmosphere furnace for primary sintering. The atmosphere is oxygen, and the sintering temperature of the primary sintering section is set to 800℃, with a sintering time of 8 hours. The material after primary sintering is then subjected to primary airflow pulverization to obtain TiO2@Li5FeO4 material. The primary airflow pulverization power is 105 kW.

[0170] Step 3: The TiO2@Li5FeO4 material after primary pulverization is placed in a protective atmosphere furnace for secondary sintering. The protective atmosphere is nitrogen, and ethylene gas is introduced during the process. The ethylene content in the sintering furnace is less than or equal to 10 ppm, the gas introduction time is 8 hours, the sintering temperature is set to 700℃, and the sintering time is 7 hours. After secondary sintering, the material is pulverized by a secondary gas flow to obtain the lithium-supplementing material C@TiO2@Li5FeO4. The secondary gas flow pulverization power is 140 kW.

[0171] Example 7

[0172] This embodiment provides a lithium supplementation material C@TiO2@Li5FeO4, and the specific preparation method is shown below:

[0173] Step 1: Weigh out lithium source Li2O, iron source Fe2O3, and tetrabutyl titanate (5:1:0.02) according to the molar stoichiometric ratio, mix them evenly, and then grind them. The grinding power is 3.5 kWh / kg.

[0174] Step 2: The ground powder is placed in an atmosphere furnace for primary sintering. The atmosphere is oxygen, and the sintering temperature of the primary sintering section is set to 800℃ for 7 hours. The material after primary sintering is then subjected to primary airflow pulverization to obtain TiO2@Li5FeO4. The primary airflow pulverization power is 110 kW.

[0175] Step 3: The TiO2@Li5FeO4 material after primary pulverization is placed in a protective atmosphere furnace for secondary sintering. The protective atmosphere is nitrogen, and ethylene gas is introduced during the process. The ethylene content in the sintering furnace is less than or equal to 10 ppm, the gas introduction time is 8 hours, the sintering temperature is set to 700℃, and the sintering time is 7 hours. After secondary sintering, the material is pulverized by a secondary gas flow to obtain the lithium-supplementing material C@TiO2@Li5FeO4. The secondary gas flow pulverization power is 140 kW.

[0176] Example 8

[0177] This embodiment provides a lithium supplementation material C@Al2O3@Li5FeO4, and the specific preparation method is shown below:

[0178] Step 1: Weigh out lithium source Li2O, iron source Fe2O3, and aluminum isopropoxide (5:1:0.04) according to the molar stoichiometric ratio, mix them evenly, and then grind them. The grinding power is 3.5 kWh / kg.

[0179] Step 2: The ground powder is placed in an atmosphere furnace for primary sintering. The atmosphere is oxygen, and the primary sintering temperature is set to 800℃ for 9 hours. The material after primary sintering is then subjected to primary airflow milling to obtain Al2O3@Li5FeO4. The primary airflow milling power is 60 kW.

[0180] Step 3: The Al2O3@Li5FeO4 material after primary pulverization is placed in a protective atmosphere furnace for secondary sintering. The protective atmosphere is nitrogen, and acetylene gas is introduced during the process. The acetylene content in the sintering furnace is ≤10ppm, the gas introduction time is 11h, the sintering temperature is 700℃, and the sintering time is 10h. The material after secondary sintering is pulverized by a secondary airflow to obtain the lithium-supplementing material C@Al2O3@Li5FeO4. The secondary airflow pulverization power is 110kW.

[0181] Example 9

[0182] This embodiment provides a lithium supplementation material C@Al2O3@Li5FeO4, and the specific preparation method is shown below:

[0183] Step 1: Weigh out lithium source Li2O, iron source Fe2O3, and aluminum isopropoxide (5:1:0.04) according to the molar stoichiometric ratio, mix them evenly, and then grind them. The grinding power is 3.5 kWh / kg.

[0184] Step 2: The ground powder is placed in an atmosphere furnace for primary sintering. The atmosphere is oxygen, and the primary sintering temperature is set to 800℃ for 9 hours. The material after primary sintering is then subjected to primary airflow pulverization to obtain Al2O3@Li5FeO4. The primary airflow pulverization power is 65 kW.

[0185] Step 3: The Al2O3@Li5FeO4 material after primary pulverization is placed in a protective atmosphere furnace for secondary sintering. The protective atmosphere is nitrogen, and acetylene gas is introduced during the process. The acetylene content in the sintering furnace is ≤10ppm, the gas introduction time is 9 hours, the sintering temperature is 700℃, and the sintering time is 8 hours. The material after secondary sintering is pulverized by a secondary airflow to obtain the lithium-supplementing material C@Al2O3@Li5FeO4. The secondary airflow pulverization power is 110kW.

[0186] Example 10

[0187] This embodiment provides a lithium supplementation material C@Al2O3@Li5FeO4, and the specific preparation method is shown below:

[0188] Step 1: Weigh out lithium source Li2O, iron source Fe2O3, and aluminum isopropoxide (5:1:0.04) according to the molar stoichiometric ratio, mix them evenly, and then grind them. The grinding power is 3.5 kWh / kg.

[0189] Step 2: The ground powder is placed in an atmosphere furnace for primary sintering. The atmosphere is oxygen, and the primary sintering temperature is set to 800℃ for 8 hours. The material after primary sintering is then subjected to primary airflow pulverization to obtain Al2O3@Li5FeO4. The primary airflow pulverization power is 110 kW.

[0190] Step 3: The Al2O3@Li5FeO4 material after primary pulverization is placed in a protective atmosphere furnace for secondary sintering. The protective atmosphere is nitrogen, and acetylene gas is introduced during the process. The acetylene content in the sintering furnace is ≤10ppm, the gas introduction time is 9 hours, the sintering temperature is 700℃, and the sintering time is 10 hours. The material after secondary sintering is pulverized by a secondary airflow to obtain the lithium-supplementing material C@Al2O3@Li5FeO4. The secondary airflow pulverization power is 145kW.

[0191] Example 11

[0192] This embodiment provides a lithium supplementation material C@Al2O3@Li5FeO4, and the specific preparation method is shown below:

[0193] Step 1: Weigh out lithium source Li2O, iron source Fe2O3, and aluminum isopropoxide (5:1:0.04) according to the molar stoichiometric ratio, mix them evenly, and then grind them. The grinding power is 3.5 kWh / kg.

[0194] Step 2: The ground powder is placed in an atmosphere furnace for primary sintering. The atmosphere is oxygen, and the primary sintering temperature is set to 800℃ for 8 hours. The material after primary sintering is then subjected to primary airflow pulverization to obtain Al2O3@Li5FeO4. The primary airflow pulverization power is 80 kW.

[0195] Step 3: The Al2O3@Li5FeO4 material after primary pulverization is placed in a protective atmosphere furnace for secondary sintering. The protective atmosphere is nitrogen, and acetylene gas is introduced during the process. The acetylene content in the sintering furnace is ≤10ppm, the gas introduction time is 11h, the sintering temperature is 700℃, and the sintering time is 10h. The material after secondary sintering is pulverized by a secondary airflow to obtain the lithium-supplementing material C@Al2O3@Li5FeO4. The primary airflow pulverization power is 130kW.

[0196] Example 12

[0197] This embodiment provides a lithium supplementation material C@Al2O3@Li5FeO4, and the specific preparation method is shown below:

[0198] Step 1: Weigh out lithium source Li2O, iron source Fe2O3, and aluminum isopropoxide (5:1:0.025) according to the molar stoichiometric ratio, mix them evenly, and then grind them. The grinding power is 3.5 kWh / kg.

[0199] Step 2: The ground powder is placed in an atmosphere furnace for primary sintering. The atmosphere is oxygen, and the primary sintering temperature is set to 800℃ for 8 hours. The material after primary sintering is then subjected to primary airflow pulverization to obtain Al2O3@Li5FeO4. The primary airflow pulverization power is 120 kW.

[0200] Step 3: The Al2O3@Li5FeO4 material after primary pulverization is placed in a protective atmosphere furnace for secondary sintering. The protective atmosphere is nitrogen, and acetylene gas is introduced during the process. The acetylene content in the sintering furnace is ≤10ppm, the gas introduction time is 11h, the sintering temperature is 700℃, and the sintering time is 9h. The material after secondary sintering is pulverized by a secondary airflow to obtain the lithium-supplementing material C@Al2O3@Li5FeO4. The secondary airflow pulverization power is 130kW.

[0201] Comparative Example 1

[0202] Uncoated modified lithium supplement material Li5FeO4.

[0203] Step 1: Weigh out lithium source Li2O and iron source Fe2O3 (5:1) according to the molar stoichiometric ratio, mix them evenly, and then grind them. The grinding power is 3.5 kWh / kg.

[0204] Step 2: The ground powder is placed in an atmosphere furnace for sintering. The atmosphere is oxygen, and the sintering temperature is set to 800℃ for 9 hours. The sintered material is then pulverized by airflow to obtain uncoated modified lithium supplementary material Li5FeO4.

[0205] Comparative Example 2

[0206] Preparation of Al2O3@Li5FeO4.

[0207] The difference between Comparative Example 2 and Example 1 is that step 3 is omitted, while the other steps are the same.

[0208] Comparative Example 3

[0209] Preparation of C@Li5FeO4.

[0210] The difference between Comparative Example 3 and Example 1 is that aluminum isopropoxide was not added in step 1, while the other steps are the same.

[0211] Detection method:

[0212] Particle size testing method for lithium replenishment materials: The particle size of the lithium replenishment materials was determined using a Malvern dry particle size analyzer, where D... 10 D 50 D 99 These are the particle sizes corresponding to the cumulative volume percentage of material particles reaching 10%, 50%, and 99%, respectively, in μm.

[0213] Test method for carbon content in lithium supplementation materials: The carbon content in the sample is obtained by detecting the CO2 concentration during the combustion process of the lithium supplementation material using a carbon-sulfur analyzer, expressed as a percentage.

[0214] Method for detecting metal elements in the metal compound layer of lithium replenishment material: After digesting the lithium replenishment material with hydrochloric acid at 250℃ for 20 minutes, the metal element content is detected by ICP-AES instrument, and the unit is ppm.

[0215] Test method for the moisture absorption rate M of lithium replenishment material: Weigh M0g of lithium replenishment material using an analytical balance in a constant temperature and humidity chamber at 25℃ and 45% humidity, and record the weight M of the lithium replenishment material after 40 minutes. 40 g. The moisture absorption rate of the lithium replenishment material M = 10000 * (M 40 -M0) / M0 / (40*60), unit is ppm / s; where M 40 M0 represents the mass of the lithium replenishment material after 40 minutes of exposure, in g; M0 represents the initial mass of the lithium replenishment material, in g.

[0216] Characterization of the interfacial stability of the lithium replenishment material: After being placed in a constant temperature and humidity chamber at 25℃ and 45% for 48 hours, the morphological changes of the lithium replenishment material were tested by SEM.

[0217] The lithium replenishing materials from Example 2 and Comparative Example 1 were placed in a constant temperature and humidity chamber at 25°C and 45% for 48 hours, and the morphological changes of the lithium replenishing materials before and after the placement were tested by SEM. The SEM image of the lithium replenishing material in Example 2 before placement is shown in the figure. Figure 1 The SEM image of the lithium replenishment material in Example 2 after being left to stand for 48 hours is shown below. Figure 2 The changes in both were not significant, indicating that the lithium replenishment material exhibited high stability. The SEM images of the lithium replenishment material in Comparative Example 1 before it was left to stand are shown below. Figure 3 The SEM images of the lithium replenishment material in Comparative Example 1 after 48 hours of rest are shown in the attached figures. Figure 4 , attached Figure 4 The surface roughness of medium-proportion materials leads to side reactions in the surface lithium-added materials, resulting in poor stability.

[0218] The particle size D of the lithium-supplementing materials was obtained by testing Examples 1-12 and Comparative Examples 1-3. 10 D 50 D 99 The metal element content X, carbon content C, and moisture absorption rate M of the lithium replenishment material in the metal compound layer are shown in Table 1.

[0219] Table 1

[0220]

[0221] Preparation of lithium-replenishing electrode: The binder PVDF (polyvinylidene fluoride), the conductive agent CNT (carbon nanotubes), and NMP (N-methyl-2-pyrrolidone) were combined with the lithium-replenishing materials prepared in Examples 1-12 and Comparative Examples 1-4 to form a lithium-replenishing slurry. The lithium-replenishing material accounted for 96.8%, the binder accounted for 2.42%, and the conductive agent accounted for 0.78%. The lithium-replenishing slurry had good fluidity. After being coated on aluminum foil and dried, the lithium-replenishing electrode was obtained and its performance was tested.

[0222] Preparation of the positive electrode sheet: The binder PVDF (polyvinylidene fluoride), conductive agent CNT (carbon nanotubes), NMP (N-methyl-2-pyrrolidone), and LFP (lithium iron phosphate) were combined with the lithium-supplementing materials prepared in Examples 1-12 and Comparative Examples 1-4 to form a positive electrode slurry for coating, thereby preparing the positive electrode sheet. The lithium-supplementing material accounted for 2%, the lithium iron phosphate material for 94.8%, the binder for 2.42%, and the conductive agent for 0.78%.

[0223] Button cell test: Take the above-mentioned positive electrode sheet or lithium-added electrode sheet, punch it into small round pieces, and assemble the button cell in a glove box. The glove box environment is: water <0.1ppm, oxygen <1ppm. The counter electrode is a lithium sheet, and the electrolyte is 1mol / L lithium hexafluorophosphate. The assembled button cell is tested using the Blue Battery system to test the specific capacity of the materials.

[0224] Full cell fabrication: The above-mentioned positive electrode sheets are stacked in a Z-shape, alternating between negative electrode-separator-positive electrode-separator-negative electrode. Each cell contains 3 positive electrodes and 4 negative electrodes. Each cell is injected with 2.8g of electrolyte. Then, the cells undergo chemical decomposition, aging, and capacity testing. The negative electrode is made of graphite material, and the mass ratio of graphite, conductive carbon black, and SBR (styrene-butadiene rubber) is 96:2:2.

[0225] Electrochemical performance testing:

[0226] Lithium replenishment capacity test: The lithium replenishment electrode was assembled into a coin cell and tested using a Xinwei battery cabinet. The initial charge capacity was measured when the charging voltage was 2.5-4.3V and the charging current was 0.5C.

[0227] Capacity test of positive electrode after lithium replenishment: The positive electrode was assembled into a coin cell and tested using a Xinwei battery cabinet. The initial charge capacity was measured when the charging voltage was 2.5-4.3V and the charging current was 0.5C.

[0228] Cyclic performance test: The positive electrode plates are assembled into a full battery for cyclic testing. The temperature chamber is set at 60℃, the charging voltage is 2.5~4.3V, and the charge and discharge test is carried out with a current of 1C. The capacity retention rate of the battery after 1000 cycles is recorded.

[0229] The test results are shown in Table 2.

[0230] Table 2

[0231]

[0232] In summary, the lithium replenishment material provided in this application is a three-phase composite double-layer coated lithium-rich material with high environmental stability. This lithium replenishment material and the lithium replenishment electrode can be placed in the air for a long time without deactivation. When used in combination with the cathode material system, it can improve the system's capacity and long-cycle performance.

[0233] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A lithium supplementation material, characterized in that, include: The nucleus and the coating layer covering the nucleus; The core body comprises a lithium-rich material; The coating layer comprises a metal compound and carbon.

2. The lithium replenishment material according to claim 1, characterized in that, The moisture absorption rate M of the lithium replenishment material satisfies: 0 < M ≤ 17; the unit is ppm / s.

3. The lithium replenishment material according to claim 2, characterized in that, The particle size D of the lithium replenishment material, the mass content X of the metal element in the coating layer, and the carbon content C in the coating layer satisfy the relationship (1): 0 < -0.127*D 10 +0.65*D 50 -0.404*D 99 -1.185*C+0.000636*X≤17(1); where, D 10 The particle size D of the lithium supplement material is indicated. 10 The unit is μm; D 50 The particle size D of the lithium supplement material is indicated. 50 The unit is μm; D 99 The particle size D of the lithium supplement material is indicated. 99 The unit is μm; C represents the carbon content in the coating layer calculated based on the total mass of the lithium replenishing material, in wt%; X represents the mass content of the metal element in the coating layer calculated based on the total mass of the lithium replenishing material, in ppm.

4. The lithium replenishment material according to any one of claims 1 to 3, characterized in that, The lithium replenishment material satisfies at least one of the following conditions (1) to (5): (1) The particle size D of the lithium replenishment material 10 Satisfy: 0 < D 10 ≤5μm; (2) The particle size D of the lithium replenishment material 50 Satisfying: 5μm≤D 50 ≤12μm; (3) The particle size D of the lithium replenishment material 99 Satisfying: 15μm≤D 99 ≤25μm; (4) Based on the total mass of the lithium replenishment material, the mass content X of the metal element in the coating layer satisfies: 0 <X≤27000ppm; (5) Based on the total mass of the lithium replenishment material, the carbon content C in the coating layer satisfies: 0 < C ≤ 5 wt%.

5. The lithium replenishment material according to any one of claims 1 to 4, characterized in that, The coating layer includes a first coating layer and a second coating layer; the second coating layer is disposed on the outer surface of the first coating layer, the first coating layer includes a metal compound layer; the second coating layer includes a carbon layer.

6. The lithium replenishment material according to any one of claims 1 to 5, characterized in that, In the core, the lithium-rich material includes at least one of Li5FeO4, Li2NiO2, and LiCoO2; and / or, the metal element in the coating layer includes at least one of Al, Ti, Mg, Zr, and Zn.

7. The lithium replenishment material according to claim 6, characterized in that, The lithium-rich material includes Li5FeO4.

8. A method for preparing the lithium supplementation material according to any one of claims 1-7, characterized in that, include: The lithium-supplementing material is prepared using raw materials for the core and the coating layer; the lithium-supplementing material includes a core and a coating layer covering the core, the core comprising a lithium-rich material; the coating layer comprising a metal compound and carbon.

9. The method according to claim 8, characterized in that, The preparation of the lithium-supplementing material using raw materials for the core and the coating layer includes: A lithium supplement material precursor is prepared using raw materials for a core and a first coating layer. The lithium supplement material precursor includes a core and a first coating layer covering the core. A second coating layer is prepared outside the first coating layer to obtain a lithium-replenishing material. The lithium-replenishing material includes a core and a first coating layer and a second coating layer sequentially coating the core. The core includes a lithium-rich material. The first coating layer includes a metal compound layer. The second coating layer includes a carbon layer.

10. The method according to claim 9, characterized in that, The method for preparing the lithium supplementation material precursor includes a solid-state method or a wet method; and / or, the method for preparing the second coating layer includes a vapor deposition method.

11. The method according to claim 9 or 10, characterized in that, The step of preparing the lithium supplementation material precursor using the raw materials of the core and the first coating layer includes: The raw materials of the core and the first coating layer are mixed, ground, granulated, sintered once, and crushed once to obtain the lithium supplement material precursor.

12. The method according to claim 11, characterized in that, The primary pulverization method includes primary airflow pulverization, wherein the power of primary airflow pulverization is 50kW to 150kW.

13. The method according to any one of claims 9 to 12, characterized in that, The raw materials for the core include a lithium source and a metal source; the metal source includes at least one of an iron source, a manganese source, a nickel source, a cobalt source, and a vanadium source. The raw materials for the first coating layer include at least one of aluminum source, titanium source, magnesium source, zirconium source and zinc source.

14. The method according to claim 13, characterized in that, The molar ratio of the lithium source, the metal source and the metal source in the first coating layer is 5:1:(0.01~0.05).

15. The method according to any one of claims 9 to 15, characterized in that, The step of preparing the second coating layer outside the first coating layer includes: A carbon layer is deposited in vitro before the lithium replenishment material is prepared, followed by secondary sintering and secondary pulverization to obtain the lithium replenishment material.

16. The method according to claim 15, characterized in that, The control parameters in the step of preparing the second coating layer outside the first coating layer include at least one of the following: (a) The secondary pulverization method includes secondary airflow pulverization, wherein the power of the secondary airflow pulverization is 50 kW to 150 kW; (b) In the method of vapor deposition of carbon layer: the carbon source includes organic carbon source; the content of the carbon source is ≤10ppm; the ventilation time is 7h to 12h.

17. A positive electrode plate, characterized in that, It includes the lithium replenishing material according to any one of claims 1 to 7, or the lithium replenishing material obtained by the preparation method according to any one of claims 8 to 16.

18. The positive electrode sheet according to claim 17 further includes a positive electrode material, wherein the mass ratio of the lithium replenishing material to the positive electrode material is 1:99 to 8:

92.

19. The positive electrode sheet according to claim 18, characterized in that, The cathode material includes lithium iron phosphate.

20. A battery, characterized in that, Includes the positive electrode sheet as described in any one of claims 17 to 19.

21. An electrical appliance, characterized in that, Includes the battery as described in claim 20.

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