Lithium-containing cathode materials and their preparation methods, cathodes, batteries and electrical equipment

Abstract

This application provides a cathode lithium supplement material and its preparation method. The cathode lithium supplement material includes a Li5FeO4 core and a coating layer covering the outer surface of the Li5FeO4 core. The coating layer includes at least one nitride layer and at least one oxide layer alternately stacked. The thickness of each nitride layer is 0.1 nm-0.5 nm, and the thickness of each oxide layer is 0.1 nm-1 nm. The nitride layer can improve the stability and conductivity of the cathode lithium supplement material, and the oxide layer can effectively isolate the Li5FeO4 core from contact and reaction with water and oxygen in the external environment, thereby improving the stability of the cathode lithium supplement material. Furthermore, the cathode lithium supplement material of this application controls the thickness of the nitride layer and the oxide layer at the atomic level, which can further improve the stability of the cathode lithium supplement material. The preparation method can also control the coating layer thickness by controlling the number of nitride layers and oxide layers.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery technology, and in particular to a positive electrode lithium replenishment material and its preparation method, a positive electrode, a battery, and an electrical device. Background Technology

[0002] Li5FeO4 is a lithium-rich transition metal oxide with an anti-fluorite structure and high theoretical specific capacity. It can be used as a cathode material in lithium-ion batteries to compensate for irreversible capacity loss during the first cycle and improve the battery's cycle life. However, Li5FeO4 readily reacts with H2O and CO2 in the air, which not only reduces its electrochemical activity but also generates residual alkali that can produce gas in the battery, posing a safety hazard.

[0003] Although there are technologies to improve the stability of Li5FeO4 by coating and modifying it, there are still problems such as uneven thickness of the coating layer, inability to accurately control the thickness of the coating layer, and the use of a single material for the coating layer. In addition, excessively thick coating layers formed by methods such as high-temperature solid-state sintering will reduce the proportion of active materials. Summary of the Invention

[0004] In view of this, this application provides a cathode lithium supplement material, which includes a Li5FeO4 core and a coating layer covering the outer surface of the Li5FeO4 core. The coating layer includes at least one nitride layer and at least one oxide layer alternately stacked. The nitride layer can improve the stability and conductivity of the cathode lithium supplement material, and the oxide layer can effectively isolate the Li5FeO4 core from contact and reaction with water and oxygen in the external environment, thereby improving the stability of the cathode lithium supplement material. Furthermore, the cathode lithium supplement material of this application has a relatively thin nitride layer and oxide layer thickness, and the coating layer thickness can be controlled by controlling the number of nitride layers and oxide layers.

[0005] The first aspect of this application provides a positive electrode lithium replenishment material, the positive electrode lithium replenishment material comprising a Li5FeO4 core and a coating layer covering the outer surface of the Li5FeO4 core, the coating layer comprising at least one nitride layer and at least one oxide layer alternately stacked; the thickness of each nitride layer is 0.1nm-0.5nm, and the thickness of each oxide layer is 0.1nm-1nm.

[0006] In this embodiment of the application, the coating layer includes a nitride layer and an oxide layer; or, the coating layer includes at least one nitride layer and at least two oxide layers stacked alternately; or, the coating layer includes at least two nitride layers and at least one oxide layer stacked alternately.

[0007] In this embodiment of the application, the nitride layer includes one or more of AlN, TiN, GaN, NbN, and InN.

[0008] In this embodiment of the application, the oxide layer includes one or more of Al2O3, SiO2, TiO2, NiO, ZnO, Ga2O3, Y2O3, ZrO2, Nb2O5, In2O3, SnO2, HfO2, and Ta2O5.

[0009] In this embodiment of the application, the particle size D99 of the Li5FeO4 core is 1μm-25μm, the thickness of the coating layer is 0.2nm-6nm, and the ratio of the total thickness of the nitride layer to the total thickness of the oxide layer in the coating layer is (0.05-10):1.

[0010] In this embodiment of the application, the particle size D99 of the Li5FeO4 core is 1μm-18μm; the thickness of the coating layer is 0.2nm-1.9nm; and the ratio of the total thickness of the nitride layer to the total thickness of the oxide layer in the coating layer is (0.125-1.5):1.

[0011] The second aspect of this application provides a method for preparing the positive electrode lithium replenishment material provided in the first aspect of this application, comprising the following steps:

[0012] S101. Place the Li5FeO4 powder into the atomic layer deposition equipment;

[0013] S102. Nitride sources and oxide sources are alternately introduced into an atomic layer deposition apparatus to deposit at least one nitride layer and at least one oxide layer alternately stacked on the surface of the Li5FeO4 powder, wherein the order in which the nitride sources and oxide sources are introduced is not limited.

[0014] In this embodiment of the application, the nitride source includes a first metal source and a nitrogen source; the first metal source includes one or more of Al(NEt2)3, Al(NMe2)3, AlCl3, AlEt3, AlMe3, Ti(NEt2)4, Ti(NEtMe)4, Ti(NMe2)4, TiCl4, TiI4, GaCl3, GaEt3, GaMe3, NbCl5, InEtMe2, and InMe3, and the nitrogen source includes one or more of NH3, N2H4, and N2.

[0015] In this embodiment of the application, the oxide source includes a second metal source and an oxygen source; the second metal source includes Al(NEt2)3, Al(NMe2)3, Al(OEt)3, AlCl3, AlEt3, AlMe2Cl, AlMe3, Si(OEt)4, Si(OMe)4, Si2Cl6, SiCl2H2, SiCl3H, SiCl4, SiH(NMe2)3, SiH2(NEt2)2, SiH2(N Me2)2, Ti(NEt2)4, Ti(NEtMe)4, Ti(NMe2)4, Ti(OEt)4, Ti(OMe)4, TiCl4, TiF4, TiI4, Ni(acac)2, N i(CpEt)2, Ni(CpMe)2, NiCp2, Zn, Zn(OAc)2, ZnCl2, ZnEt2, ZnMe2, Ga(acac)3, Ga2(NMe2)6, GaEt3, G aMe3, Y(CpBu)3, Y(CpEt)3, Y(CpMe)3, YCp3, Zr(NEt2)4, Zr(NEtMe)4, Zr(NMe2)4, ZrCl4, ZrCp2Cl2 , ZrCp2Me2, ZrI4, Nb(OEt)5, In(acac)3, InCl3, InEt3, InMe3, Sn(acac)2, Sn(NEtMe)4, Sn(NMe2)4, The oxygen source comprises one or more of SnCl4, SnEt4, SnI4, SnMe4, Hf(NEt2)4, Hf(NEtMe)4, Hf(NMe2)4, HfCl4, HfCp2Cl2, HfCp2Me2, HfI4, Ta(NEt2)5, Ta(NMe2)5, Ta(OEt)5, TaCl5, TaF5, and TaI5, wherein the oxygen source comprises one or more of H2O, O3, O2, and H2O2.

[0016] In this embodiment of the application, the reaction temperature in the atomic layer deposition equipment is 25℃-400℃.

[0017] A third aspect of this application provides a battery positive electrode, including a current collector and a positive electrode active material loaded on the current collector, wherein the positive electrode active material includes a positive electrode lithium replenishment material as described in the first aspect or a positive electrode lithium replenishment material obtained by the preparation method described in the second aspect of this application.

[0018] A fourth aspect of this application provides a battery comprising a positive electrode as described in the third aspect.

[0019] The fifth aspect of this application provides an electrical device comprising a battery as described in the fourth aspect. Attached Figure Description

[0020] Figure 1 This is a schematic cross-sectional view of a positive electrode lithium replenishment material provided in an embodiment of this application;

[0021] Figure 2 This is a schematic diagram of the cross-sectional structure of a positive electrode lithium replenishment material provided in another embodiment of this application;

[0022] Figure 3 This is a schematic diagram of the cross-sectional structure of a positive electrode lithium replenishment material provided in another embodiment of this application.

[0023] Explanation of icon numbers

[0024] 10-Cathode lithium replenishment material; 11-Li5FeO4 core; 12-Coating layer; 121-Nitrogen layer; 122-Oxide layer. Detailed Implementation

[0025] The present application will be further described in detail below with reference to preferred embodiments, but the scope of protection of the present application is not limited to the following specific embodiments.

[0026] In this application, all technical terms have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this application.

[0027] Li5FeO4 is a lithium-rich transition metal oxide with an anti-fluorite structure and high theoretical specific capacity. It can be used as a cathode material in lithium-ion batteries to compensate for irreversible capacity loss during the first cycle and improve the battery's cycle life. However, Li5FeO4 readily reacts with H2O and CO2 in the air, which not only reduces its electrochemical activity but also increases gas production in the battery due to the generated residual alkali, posing a safety hazard.

[0028] Although there are technologies to improve the stability of Li5FeO4 by coating and modifying it, there are still problems such as uneven thickness of the coating layer, inability to accurately control the thickness of the coating layer, and the use of a single material for the coating layer. In addition, excessively thick coating layers formed by methods such as high-temperature solid-state sintering will reduce the proportion of active materials.

[0029] To address the aforementioned issues, this application provides a cathode lithium replenishment material comprising a Li5FeO4 core and a coating layer covering the outer surface of the Li5FeO4 core. The coating layer comprises at least one nitride layer and at least one oxide layer alternately stacked. The nitride layer can improve the stability and conductivity of the cathode lithium replenishment material, while the oxide layer can effectively isolate the Li5FeO4 core from contact and reaction with external water and oxygen, thus improving the stability of the cathode lithium replenishment material. Furthermore, the cathode lithium replenishment material of this application has a relatively thin nitride layer and oxide layer; controlling the thickness of the nitride layer and oxide layer to the atomic level can further improve the stability of the cathode lithium replenishment material.

[0030] See Figure 1 The first aspect of this application provides a positive electrode lithium replenishment material 10, which includes a Li5FeO4 core 11 and a coating layer 12 covering the outer surface of the Li5FeO4 core 11. The coating layer 12 includes at least one nitride layer 121 and at least one oxide layer 122 that are alternately stacked. This application selects Li5FeO4 as the core of the positive electrode lithium replenishment material 10. Li5FeO4 has a high theoretical specific capacity, which can effectively compensate for the irreversible capacity loss of the battery during the first cycle and improve the cycle life of the battery. The coating layer 12 can effectively isolate the Li5FeO4 core 11 from contact with water and carbon dioxide in the outside air, thereby avoiding its decomposition reaction and affecting its electrochemical activity, and effectively preventing the residual alkali generated by it from causing gas production in the battery. After the Li5FeO4 core 11 is coated by the coating layer 12, the stability of the positive electrode lithium replenishment material 10 is greatly improved, further improving the battery's first charge and discharge specific capacity and safety performance, and broadening the application scenarios of this positive electrode lithium replenishment material.

[0031] In this embodiment, the coating layer 12 includes at least one nitride layer 121 and at least one oxide layer 122 alternately stacked. In this embodiment, the number of nitride layers 121 in the coating layer 12 is greater than or equal to 1. In some specific embodiments, the number of nitride layers 121 in the coating layer 12 can be, for example, 1, 2, 3, or 4. In this embodiment, the number of oxide layers 122 in the coating layer 12 is greater than or equal to 1. In some specific embodiments, the number of oxide layers 122 in the coating layer 12 can be, for example, 1, 2, 3, or 4. In this embodiment, the number of nitride layers 121 and the number of oxide layers 122 in the coating layer 12 can be the same or different. When the number of nitride layers 121 is greater than 1, the materials of the different nitride layers 121 can be the same or different; when the number of oxide layers 122 is greater than 1, the materials of the different oxide layers 122 can be the same or different.

[0032] In some embodiments of this application, the innermost layer of the coating layer 12 near the Li5FeO4 core 11 can be either a nitride layer 121 or an oxide layer 122. In some embodiments of this application, such as... Figure 1 As shown, the nitride layer 121 can be the innermost layer of the coating layer 12 closest to the Li5FeO4 core, directly contacting the outer surface of the Li5FeO4 core 11; in other embodiments of this application, such as Figure 2 As shown, the oxide layer 122 can be the innermost layer of the coating layer 12, close to the Li5FeO4 core, and is in direct contact with the outer surface of the Li5FeO4 core 11.

[0033] In this embodiment of the application, the outermost layer of the coating layer 12 on the side furthest from the Li5FeO4 core can be either a nitride layer 121 or an oxide layer 122. In some embodiments of this application, such as... Figure 1 As shown, oxide layer 122 can be the outermost layer of the coating layer 12 on the side away from the Li5FeO4 core, that is, the outermost layer of the positive electrode lithium replenishment material 10 is oxide layer 122; in other embodiments of this application, such as Figure 2 As shown, the nitride layer 121 can be the outermost layer of the coating layer 12 on the side away from the Li5FeO4 core, that is, the outermost layer of the positive electrode lithium replenishment material 10 is the nitride layer 121.

[0034] In this embodiment, the thickness of each nitride layer 121 is 0.1 nm-0.5 nm, and the thickness of each oxide layer 122 is 0.1 nm-1 nm. In some specific embodiments of this application, the thickness of each nitride layer 121 can be, for example, 0.1 nm, 0.2 nm, 0.3 nm, 0.4 nm, or 0.5 nm, and the thickness of each oxide layer 122 can be, for example, 0.1 nm, 0.2 nm, 0.3 nm, 0.4 nm, 0.5 nm, 0.6 nm, 0.7 nm, 0.8 nm, 0.9 nm, or 1 nm. By controlling the thickness of each nitride layer 121 and each oxide layer 122, this application can achieve the design of the stacked structure of the coating layer 12 and the control of the total thickness of the coating layer 12 according to actual needs, thereby adjusting its physical and chemical properties to meet the usage requirements of different application scenarios. In addition, controlling the thickness of each nitride layer and oxide layer within a suitable atomic level range is beneficial to improving the uniformity of the coating layer, thereby further improving the stability of the cathode lithium replenishment material. At the same time, it is beneficial to obtain a better protection effect on the Li5FeO4 core with the smallest possible coating layer thickness, as well as to obtain better conductivity.

[0035] In some embodiments of this application, such as Figure 1 and Figure 2As shown, the coating layer 12 includes a nitride layer 121 and an oxide layer 122 stacked together, wherein the nitride layer 121 or the oxide layer 122 is close to the Li5FeO4 core 11. In other embodiments of this application, such as Figure 3 As shown, the coating layer 12 includes at least two alternately stacked nitride layers 121 and at least one oxide layer 122, wherein the nitride layer 121 is close to the Li5FeO4 core 11, the oxide layer 122 is located between the two nitride layers 121, and the outermost layer of the coating layer 12 is the nitride layer 121. In some embodiments of this application, the coating layer 12 includes at least one alternately stacked nitride layer 121 and at least two oxide layers 122, wherein the oxide layer 122 is close to the Li5FeO4 core 11, the nitride layer 121 is located between the two oxide layers 122, and the outermost layer of the coating layer 12 is the oxide layer 122. The coating layer 12 of the positive electrode lithium replenishment material 10 provided in this application embodiment includes at least two coating sublayers, including at least one nitride layer 121 and at least one oxide layer 122. The oxide layer 122 can effectively isolate the core material Li5FeO4 from contact with water and carbon dioxide in the outside air, avoid the occurrence of side reactions, and thus improve its stability. At the same time, the nitride layer 121 can effectively improve the conductivity of the positive electrode lithium replenishment material 10, thereby further improving the electrochemical performance of the positive electrode lithium replenishment material. In addition, the coating of the nitride layer 121 can also play a certain role in improving the stability of the positive electrode lithium replenishment material 10.

[0036] In this embodiment, the nitride layer 121 includes one or more of AlN, TiN, GaN, NbN, and InN. In this embodiment, the oxide layer 122 includes one or more of Al2O3, SiO2, TiO2, NiO, ZnO, Ga2O3, Y2O3, ZrO2, Nb2O5, In2O3, SnO2, HfO2, and Ta2O5.

[0037] In this application, the particle size D99 of the Li5FeO4 core 11 is 1μm-25μm. The particle size D99 mentioned in this application refers to the particle size corresponding to when the percentage of Li5FeO4 core 11 in the quantity distribution reaches 99%. In this application, the particle size testing method for the Li5FeO4 core 11 can refer to GB / T 19077-2016. In some specific embodiments of this application, the particle size D99 of the Li5FeO4 core 11 can be, for example, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, or 25μm. In some embodiments of this application, the particle size D99 of the Li5FeO4 core 11 can be 1μm-18μm. In some embodiments of this application, the thickness of the coating layer 12 is 0.2nm-6nm. In some embodiments of this application, the thickness of the coating layer 12 can be obtained by FIB-TEM (Focused Ion Beam-Transmission Electron Microscope). In some specific embodiments, the thickness of the coating layer 12 can be, for example, 0.2nm, 0.3nm, 0.4nm, 0.5nm, 0.6nm, 0.7nm, 0.8nm, 0.9nm, 1.0nm, 1.1nm, 1.2nm, 1.3nm, 1.4nm, 1.5nm, 1.6nm, 1.7nm, 1.8nm, 1.9nm, 2.0nm, 2.1nm, 2.2nm, 2.3nm, 2.4nm, 2.5nm, 2.6nm, 2.7nm, 2.8nm, 2.9nm. The thicknesses are 3.0 nm, 3.1 nm, 3.2 nm, 3.3 nm, 3.4 nm, 3.5 nm, 3.6 nm, 3.7 nm, 3.8 nm, 3.9 nm, 4.0 nm, 4.1 nm, 4.2 nm, 4.3 nm, 4.4 nm, 4.5 nm, 4.6 nm, 4.7 nm, 4.8 nm, 4.9 nm, 5.0 nm, 5.1 nm, 5.2 nm, 5.3 nm, 5.4 nm, 5.5 nm, 5.6 nm, 5.7 nm, 5.8 nm, 5.9 nm, and 6.0 nm. In some embodiments of this application, the thickness of the coating layer 12 can be 0.2 nm to 1.9 nm. This application controls the size of the Li5FeO4 core 11 and the coating layer 12 within a suitable range. On the one hand, it can control the size of the positive electrode lithium replenishment material 10 to a suitable size. On the other hand, it can effectively balance the activity and stability of the positive electrode lithium replenishment material 10, thereby obtaining a positive electrode lithium replenishment material 10 with suitable size and excellent activity, stability and conductivity.In addition, by controlling the thickness of the coating layer 12 within a suitable range, it can be made thick enough to protect the Li5FeO4 core of the positive electrode lithium replenishment material from water and oxygen erosion, ensuring its stability and conductivity, while maximizing the activity of the positive electrode lithium replenishment material and reducing costs, and avoiding the decrease in the activity of the positive electrode lithium replenishment material or the increase in costs caused by the coating layer 12 being too thick.

[0038] In this embodiment of the application, the ratio of the total thickness of the nitride layer 121 to the total thickness of the oxide layer 122 in the coating layer 12 is (0.05-10):1. In some specific embodiments of this application, the ratio of the total thickness of the nitride layer 121 to the total thickness of the oxide layer 122 in the coating layer 12 can be, for example, 0.05:1, 0.1:1, 0.125:1, 0.15:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1:1.5, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, or 10:1. In some embodiments of this application, the ratio of the total thickness of the nitride layer 121 to the total thickness of the oxide layer 122 in the coating layer 12 can be (0.125-1.5):1. This application ensures that Li5FeO4 has a high proportion of active materials and excellent electrochemical performance by controlling the ratio of the total thickness of the nitride layer to the oxide layer within a suitable range.

[0039] The cathode lithium replenishment material provided in this application uses nitrides and oxides to coat the Li5FeO4 core, and reasonably controls the coating thickness to obtain a dense coating layer with controllable thickness. This effectively isolates the Li5FeO4 core from contact with water and carbon dioxide in the air, avoids the occurrence of side reactions, and effectively improves the stability of the cathode lithium replenishment material. In addition, nitrides can also effectively improve the conductivity of the cathode lithium replenishment material, so that the cathode lithium replenishment material has excellent activity, stability and conductivity.

[0040] This application also provides a method for preparing the cathode lithium replenishment material provided above, including the following steps:

[0041] S101. Place the Li5FeO4 powder into the atomic layer deposition equipment;

[0042] S102. Nitride sources and oxide sources are alternately introduced into an atomic layer deposition apparatus to deposit at least one nitride layer and at least one oxide layer alternately stacked on the surface of the Li5FeO4 powder, wherein the order in which the nitride sources and oxide sources are introduced is not limited.

[0043] This application employs atomic layer deposition (ALD) technology to modify the Li5FeO4 core with nitrides and oxides. ALD is a self-limiting chemical vapor deposition technique that breaks down the target reaction into several half-reactions to achieve atomic-level thickness control of the coating layer on the material surface, down to as little as 0.1 nm. Compared to conventional high-temperature solid-state sintering coating methods, the surface coating layer of the cathode lithium replenishment material prepared by ALD in this application exhibits better film quality, uniformity, shape preservation, density without pinholes, and controllable thickness. Furthermore, the growth of the coating film can be carried out at relatively low temperatures ranging from room temperature to 400°C, with a shorter reaction time.

[0044] In step S101, the Li5FeO4 powder can be commercially available or synthesized through reaction. The synthesis methods and raw materials include, but are not limited to, conventional Li5FeO4 synthesis methods and raw materials in the field. In some embodiments of this application, the Li5FeO4 powder is unmodified Li5FeO4 powder.

[0045] In this embodiment, the atomic layer deposition equipment is pre-filled with air before adding Li5FeO4 powder, and after adding Li5FeO4 powder, a vacuum is rapidly drawn and the temperature is raised to the reaction temperature. In this embodiment, the reaction temperature in the atomic layer deposition equipment is 25℃-400℃, and the heating rate is 1℃ / min-20℃ / min. In some specific embodiments of this application, the reaction temperature in the atomic layer deposition apparatus can be, for example, 25°C, 30°C, 40°C, 50°C, 60°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 150°C, 160°C, 170°C, 180°C, 200°C, 220°C, 250°C, 280°C, 300°C, 320°C, 350°C, 380°C, or 400°C; and the heating rate can be, for example, 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, 11°C / min, 12°C / min, 13°C / min, 14°C / min, 15°C / min, 16°C / min, 17°C / min, 18°C / min, 19°C / min, or 20°C / min. This application employs atomic layer deposition (ALD) technology to coat the Li5FeO4 core with nitrides and oxides. The film growth can be carried out at a relatively low temperature of room temperature to 400°C, which effectively reduces the reaction temperature of the coating modification, thereby reducing the reaction conditions and production costs.

[0046] In step S102, nitride sources and oxide sources are alternately introduced into the atomic layer deposition equipment to coat and modify the surface of Li5FeO4 particles. In this embodiment, the introduction of nitride sources into the atomic layer deposition equipment to deposit a nitride layer specifically includes: first, introducing a first metal source, reacting it within a first specified time, then introducing an inert gas into the equipment for cleaning within a second specified time to remove excess first metal source from the equipment; then, introducing a nitrogen source, reacting it within a third specified time, and finally introducing an inert gas into the equipment for cleaning within a fourth specified time. In this embodiment, the first metal source includes one or more of Al(NEt2)3, Al(NMe2)3, AlCl3, AlEt3, AlMe3, Ti(NEt2)4, Ti(NEtMe)4, Ti(NMe2)4, TiCl4, TiI4, GaCl3, GaEt3, GaMe3, NbCl5, InEtMe2, and InMe3, and the nitrogen source includes one or more of NH3, N2H4, and N2. In this embodiment, an inert gas is introduced for cleaning, the inert gas including nitrogen or argon, wherein only argon is used for cleaning during nitride coating. This application provides metal atoms by introducing a suitable first metal source to adsorb onto the surface of Li5FeO4 particles, and by introducing a suitable nitrogen source to adsorb onto the first metal source and react with it to generate the corresponding metal nitride, which is then deposited as a nitride layer.

[0047] In this embodiment of the application, an oxide source is introduced into the atomic layer deposition equipment to deposit an oxide layer. Specifically, introducing the oxide source includes: first, introducing a second metal source, reacting within a fifth specified time period, and then introducing an inert gas into the equipment for cleaning within a sixth specified time period to remove excess second metal source from the equipment; then, introducing an oxygen source, reacting within a seventh specified time period, and finally introducing an inert gas into the equipment for cleaning within an eighth specified time period. In this embodiment of the application, the second metal source includes Al(NEt2)3, Al(NMe2)3, Al(OEt)3, AlCl3, AlEt3, AlMe2Cl, AlMe3, Si(OEt)4, Si(OMe)4, Si2Cl6, SiCl2H2, SiCl3H, SiCl4, SiH(NMe2)3, SiH2(NEt2)2, SiH2(NMe2)2, and Ti(NEt2)3. )4, Ti(NEtMe)4, Ti(NMe2)4, Ti(OEt)4, Ti(OMe)4, TiCl4, TiF4, TiI4, Ni(acac)2, Ni(CpEt)2, Ni (CpMe)2, NiCp2, Zn, Zn(OAc)2, ZnCl2, ZnEt2, ZnMe2, Ga(acac)3, Ga2(NMe2)6, GaEt3, GaMe3, Y(C pBu)3, Y(CpEt)3, Y(CpMe)3, YCp3, Zr(NEt2)4, Zr(NEtMe)4, Zr(NMe2)4, ZrCl4, ZrCp2Cl2, ZrCp2 Me2, ZrI4, Nb(OEt)5, In(acac)3, InCl3, InEt3, InMe3, Sn(acac)2, Sn(NEtMe)4, Sn(NMe2)4, SnC The oxygen source includes one or more of the following: L4, SnEt4, SnI4, SnMe4, Hf(NEt2)4, Hf(NEtMe)4, Hf(NMe2)4, HfCl4, HfCp2Cl2, HfCp2Me2, HfI4, Ta(NEt2)5, Ta(NMe2)5, Ta(OEt)5, TaCl5, TaF5, and TaI5. In this application embodiment, an inert gas is introduced for cleaning, including nitrogen or argon. Nitrogen or argon can be used for cleaning during oxide coating. This application introduces a suitable second metal source, which adsorbs onto the surface of Li5FeO4 particles to provide metal atoms. A suitable oxygen source is then introduced, adsorbed onto the first metal source, and reacts with it to generate the corresponding metal oxide, which is then deposited as an oxide layer.

[0048] In this application's embodiments, the first specified time to the eighth specified time are each independently 5s-30s. In some specific embodiments of this application, the first specified time to the eighth specified time can be, for example, 5s, 6s, 7s, 8s, 9s, 10s, 11s, 12s, 13s, 15s, 18s, 20s, 25s, or 30s. In this application's embodiments, the first specified time to the eighth specified time can be the same or different, and can be adjusted according to the selection of specific oxide and nitride sources and the thickness of the deposited coating layer in the actual production process.

[0049] In this embodiment, the order of introducing the oxide source and the nitride source is not required and can be adjusted according to the needs of the coating layer structure of the cathode lithium supplement material. In this embodiment, the number of times the nitride source is introduced into the atomic layer deposition (ALD) apparatus to deposit the nitride layer and the number of times the oxide source is introduced into the ALD apparatus to deposit the oxide layer are adjusted according to the required coating layer thickness of the cathode lithium supplement material. In this application, the coating layer thickness increases by approximately 0.1 nm with each ALD deposition. In this embodiment, the number of times the nitride source is introduced into the ALD apparatus to deposit the nitride layer is 1-5 times, i.e., the thickness of each deposited nitride layer is 0.1 nm-0.5 nm. In some specific embodiments of this application, the number of times the nitride source is introduced into the ALD apparatus to deposit the nitride layer can be, for example, 1, 2, 3, 4, or 5 times, and the thickness of each deposited nitride layer can be, for example, 0.1 nm, 0.2 nm, 0.3 nm, 0.4 nm, or 0.5 nm. In this application, the number of times the oxide source is introduced into the atomic layer deposition equipment to deposit the oxide layer is 1-10 times, that is, the thickness of each deposited oxide layer is 0.1nm-1nm. In some specific embodiments of this application, the number of times the oxide source is introduced into the atomic layer deposition equipment to deposit the oxide layer can be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 times, and the thickness of each deposited oxide layer can be, for example, 0.1nm, 0.2nm, 0.3nm, 0.4nm, 0.5nm, 0.6nm, 0.7nm, 0.8nm, 0.9nm, or 1nm. This application uses atomic layer deposition technology to coat and modify Li5FeO4, and by adjusting the number and order of deposition, the structure and thickness of the coating layer of the cathode lithium replenishment material can be designed and controlled.

[0050] The method for preparing the positive electrode lithium replenishment material provided in this application has a simple process, a low reaction temperature, and a short reaction time. By using atomic layer deposition technology to coat and modify the surface of Li5FeO4 at the atomic layer thickness, the structure and thickness of the coating layer of the positive electrode lithium replenishment material can be designed and controlled by adjusting the number and sequence of deposition. The resulting positive electrode lithium replenishment material has good film quality, uniform and dense coating layer, and controllable thickness, which can effectively isolate it from contact and reaction with water and oxygen in the air.

[0051] This application also provides a battery positive electrode, which includes a current collector and a positive electrode active material loaded on the current collector. The positive electrode active material includes the positive electrode lithium replenishment material provided above or the positive electrode lithium replenishment material prepared by the preparation method described above.

[0052] This application also provides a battery, which includes a positive electrode, a negative electrode, a separator and an electrolyte located between the positive and negative electrodes, wherein the positive electrode includes the battery positive electrode described above. In embodiments of this application, the battery may be, for example, a lithium-ion battery, including but not limited to wound lithium-ion batteries and stacked lithium-ion batteries. In some embodiments of this application, the battery is a lithium-ion battery, and the negative electrode active material in the negative electrode can be any negative electrode active material known in the art for lithium-ion batteries. Exemplarily, the negative electrode active material may be selected from one or more of carbon-based negative electrode active materials, silicon-based negative electrode active materials, tin-based negative electrode active materials, and lithium metal negative electrode active materials. Carbon-based negative electrodes may include natural graphite, artificial graphite, hard carbon, soft carbon, graphene, etc.; silicon-based negative electrodes may include silicon, silicon-carbon, silicon-oxygen, etc.; tin-based negative electrodes may include tin, tin-carbon, tin-oxygen, tin metal compounds, but are not limited thereto. In embodiments of this application, the separator may include, but is not limited to, a composite membrane of one or more of polyethylene, polypropylene, and polyvinylidene fluoride.

[0053] This application also provides an electrical device that includes the battery described above. This electrical device may be, for example, an electric vehicle, a mobile phone, a tablet computer, a laptop computer, a wearable device (watch, bracelet), a digital camera, etc.

[0054] The present application will be further described below with reference to several embodiments:

[0055] Example 1

[0056] (1) Place the Li5FeO4 material powder with a particle size D99 of 12μm into the reaction chamber of the atomic layer deposition equipment that is pre-filled with dry air, quickly evacuate the vacuum and raise the temperature of the reaction chamber, and keep the temperature of the reaction chamber at 300℃.

[0057] (2) Introduce TiCl4, the first metal source of the nitride layer, into the reaction chamber and maintain it for 5s. Then, argon gas is introduced into the reaction chamber for 30s to clean it and remove excess TiCl4.

[0058] (3) Introduce the nitrogen source NH3 of the nitride layer into the reaction chamber and maintain it for 7s. Then, introduce argon gas into the reaction chamber for 25s to clean it and remove excess NH3.

[0059] After repeating steps (2)-(3) once, we can obtain Li5FeO4@TiN as a lithium replenishment material for Li5FeO4 cathode modified with TiN as a nitride layer.

[0060] (4) Place the TiN-modified positive electrode lithium replenishment material Li5FeO4@TiN powder into the reaction chamber of an atomic layer deposition equipment pre-filled with dry air, quickly evacuate and raise the temperature of the reaction chamber, and keep the temperature of the reaction chamber at 100℃.

[0061] (5) Introduce the second metal source AlMe3 of the oxide layer into the reaction chamber and maintain for 15s. Then, introduce nitrogen gas into the reaction chamber for 30s to clean it and remove excess AlMe3.

[0062] (6) Introduce the oxygen source H2O from the oxide layer into the reaction chamber and maintain it for 12s. Then, introduce nitrogen gas into the reaction chamber for 20s to clean it and remove excess H2O.

[0063] After repeating steps (5)-(6) once, a Li5FeO4 cathode lithium replenishment material Li5FeO4@TiN@Al2O3 modified with TiN as the nitride layer and Al2O3 as the oxide layer can be obtained, wherein the thickness of the TiN nitride layer is 0.1 nm and the thickness of the Al2O3 oxide layer is 0.1 nm.

[0064] Example 2

[0065] (1) Place the Li5FeO4 material powder with a particle size D99 of 12μm into the reaction chamber of the atomic layer deposition equipment that is pre-filled with dry air, quickly evacuate the vacuum and raise the temperature of the reaction chamber, and keep the temperature of the reaction chamber at 250℃.

[0066] (2) Introduce the first metal source AlCl3 of the nitride layer into the reaction chamber and maintain it for 8s. Then, introduce argon gas into the reaction chamber for 15s to clean it and remove excess AlCl3.

[0067] (3) Introduce the nitrogen source NH3 of the nitride layer into the reaction chamber and maintain it for 10s. Then, introduce argon gas into the reaction chamber for 15s to clean it and remove excess NH3.

[0068] After repeating steps (2)-(3) 3 times, we can obtain Li5FeO4@AlN as a lithium replenishment material for Li5FeO4 cathode modified with AlN as a nitride layer.

[0069] (4) The AlN-modified positive electrode lithium replenishment material Li5FeO4@AlN powder is placed into the reaction chamber of an atomic layer deposition equipment pre-filled with dry air, and the vacuum is quickly drawn and the temperature of the reaction chamber is raised to maintain the temperature of the reaction chamber at 110℃.

[0070] (5) Introduce the second metal source Zr(NEtMe)4 of the oxide layer into the reaction chamber and maintain it for 10s. Then, argon gas is introduced into the reaction chamber for 20s to clean it and remove excess Zr(NEtMe)4.

[0071] (6) Introduce oxygen source O3 from the oxide layer into the reaction chamber and maintain for 15s. Then, introduce argon gas into the reaction chamber for 25s to clean it and remove excess O3.

[0072] After repeating steps (5)-(6) 10 times, a Li5FeO4 cathode lithium replenishment material Li5FeO4@AlN@ZrO2 modified with AlN as the nitride layer and ZrO2 as the oxide layer can be obtained, wherein the thickness of the AlN nitride layer is 0.3nm and the thickness of the ZrO2 oxide layer is 1nm.

[0073] Example 3

[0074] (1) Place the Li5FeO4 material powder with a particle size D99 of 12μm into the reaction chamber of the atomic layer deposition equipment that is pre-filled with dry air, quickly evacuate the vacuum and raise the temperature of the reaction chamber, and keep the temperature of the reaction chamber at 180℃.

[0075] (2) Introduce the first metal source GaCl3 of the nitride layer into the reaction chamber and maintain it for 6s. Then, introduce argon gas into the reaction chamber for 10s to clean it and remove excess GaCl3.

[0076] (3) Introduce the nitrogen source NH3 of the nitride layer into the reaction chamber and maintain it for 6s. Then, introduce argon gas into the reaction chamber for 20s to clean it and remove excess NH3.

[0077] After repeating steps (2)-(3) 5 times, we can obtain Li5FeO4@GaN as a lithium replenishment material for Li5FeO4 cathode modified with GaN as nitride layer.

[0078] (4) Place the GaN-modified positive electrode lithium replenishment material Li5FeO4@GaN powder into the reaction chamber of an atomic layer deposition equipment pre-filled with dry air, quickly evacuate and raise the temperature of the reaction chamber, and keep the temperature of the reaction chamber at 150℃.

[0079] (5) Introduce the second metal source Hf(NEt2)4 of the oxide layer into the reaction chamber and maintain it for 8s. Then, introduce nitrogen gas into the reaction chamber for 20s to clean it and remove excess Hf(NEt2)4.

[0080] (6) Introduce the oxygen source H2O from the oxide layer into the reaction chamber and maintain it for 12s. Then, introduce nitrogen gas into the reaction chamber for 30s to clean it and remove excess H2O.

[0081] After repeating steps (5)-(6) 5 times, a Li5FeO4 cathode lithium replenishment material Li5FeO4@GaN@HfO2 modified with GaN as the nitride layer and HfO2 as the oxide layer can be obtained, wherein the thickness of the GaN nitride layer is 0.5nm and the thickness of the HfO2 oxide layer is 0.5nm.

[0082] Example 4

[0083] (1) Place the Li5FeO4 material powder with a particle size D99 of 12μm into the reaction chamber of the atomic layer deposition equipment that is pre-filled with dry air, quickly evacuate the vacuum and raise the temperature of the reaction chamber, and keep the temperature of the reaction chamber at 120℃.

[0084] (2) Introduce the first metal source NbCl5 of the nitride layer into the reaction chamber and maintain it for 10s. Then, introduce argon gas into the reaction chamber for 15s to clean it and remove excess NbCl5.

[0085] (3) Introduce the nitrogen source NH3 of the nitride layer into the reaction chamber and maintain it for 8s. Then, introduce argon gas into the reaction chamber for 20s to clean it and remove excess NH3.

[0086] After repeating steps (2)-(3) once, Li5FeO4@NbN, a lithium replenishment material for Li5FeO4 cathode modified with NbN as a nitride layer, can be obtained.

[0087] (4) Place the NbN-modified positive electrode lithium replenishment material Li5FeO4@NbN powder into the reaction chamber of an atomic layer deposition equipment pre-filled with dry air, quickly evacuate and raise the temperature of the reaction chamber, and keep the temperature of the reaction chamber at 200℃.

[0088] (5) Introduce the second metal source Ta(OEt)5 of the oxide layer into the reaction chamber and maintain it for 6s. Then, introduce nitrogen gas into the reaction chamber for 15s to clean it and remove excess Ta(OEt)5.

[0089] (6) Introduce oxygen source O3 from the oxide layer into the reaction chamber and maintain for 10s. Then, introduce nitrogen gas into the reaction chamber for 20s to clean it and remove excess O3.

[0090] After repeating steps (5)-(6) 8 times, a Li5FeO4 cathode lithium replenishment material Li5FeO4@NbN@Ta2O5 modified with NbN as the nitride layer and Ta2O5 as the oxide layer can be obtained, wherein the thickness of the NbN nitride layer is 0.1 nm and the thickness of the Ta2O5 oxide layer is 0.8 nm.

[0091] Example 5

[0092] (1) Place the Li5FeO4 material powder with a particle size D99 of 12μm into the reaction chamber of the atomic layer deposition equipment that is pre-filled with dry air, quickly evacuate the vacuum and raise the temperature of the reaction chamber, and keep the temperature of the reaction chamber at 220℃.

[0093] (2) InMe3, the first metal source of the nitride layer, is introduced into the reaction chamber and maintained for 9s. Then, argon gas is introduced into the reaction chamber for 25s to clean it and remove excess InMe3.

[0094] (3) Introduce nitrogen source N2 from the nitride layer into the reaction chamber and maintain for 11s. Then, introduce argon gas into the reaction chamber for 10s to clean it and remove excess N2.

[0095] After repeating steps (2)-(3) twice, we can obtain Li5FeO4@InN as a lithium replenishment material for Li5FeO4 cathode modified with InN as a nitride layer.

[0096] (4) Place the InN-modified positive electrode lithium replenishment material Li5FeO4@InN powder into the reaction chamber of an atomic layer deposition equipment pre-filled with dry air, quickly evacuate and raise the temperature of the reaction chamber, and keep the temperature of the reaction chamber at 170℃.

[0097] (5) Introduce the second metal source SiCl4 of the oxide layer into the reaction chamber and maintain it for 13s. Then, introduce argon gas into the reaction chamber for 15s to clean it and remove excess SiCl4.

[0098] (6) Introduce the oxygen source H2O from the oxide layer into the reaction chamber and maintain it for 13s. Then, introduce argon gas into the reaction chamber for 10s to clean it and remove excess H2O.

[0099] After repeating steps (5)-(6) 7 times, a Li5FeO4 cathode lithium replenishment material Li5FeO4@InN@SiO2 modified with InN as the nitride layer and SiO2 as the oxide layer can be obtained, wherein the thickness of the InN nitride layer is 0.2nm and the thickness of the SiO2 oxide layer is 0.7nm.

[0100] Example 6

[0101] (1) Place the Li5FeO4 material powder with a particle size D99 of 12μm into the reaction chamber of the atomic layer deposition equipment that is pre-filled with dry air, quickly evacuate the vacuum and raise the temperature of the reaction chamber, and keep the temperature of the reaction chamber at 330℃.

[0102] (2) Introduce the second metal source Ni(acac)2 of the oxide layer into the reaction chamber and maintain it for 14s. Then, introduce nitrogen gas into the reaction chamber for 25s to clean it and remove excess Ni(acac)2.

[0103] (3) Introduce oxygen source O2 from the oxide layer into the reaction chamber and maintain for 12s. Then, introduce nitrogen gas into the reaction chamber for 10s to clean it and remove excess O2.

[0104] After repeating steps (2)-(3) 6 times, we can obtain Li5FeO4@NiO, a Li5FeO4 cathode lithium supplement material modified with NiO as oxide layer.

[0105] (4) Place the NiO-modified positive electrode lithium replenishment material Li5FeO4@NiO powder into the reaction chamber of an atomic layer deposition equipment pre-filled with dry air, quickly evacuate and raise the temperature of the reaction chamber, and keep the temperature of the reaction chamber at 140℃.

[0106] (5) Introduce the first metal source Al(NMe2)3 of the nitride layer into the reaction chamber and maintain it for 12s. Then, argon gas is introduced into the reaction chamber for 15s to clean it and remove excess Al(NMe2)3.

[0107] (6) Introduce NH3, the nitrogen source of the nitride layer, into the reaction chamber and maintain for 8s. Then, introduce argon gas into the reaction chamber for 30s to clean it and remove excess NH3.

[0108] After repeating steps (5)-(6) 4 times, a Li5FeO4 cathode lithium replenishment material Li5FeO4@NiO@AlN modified with NiO as the oxide layer and AlN as the nitride layer can be obtained, wherein the thickness of the NiO oxide layer is 0.6nm and the thickness of the AlN nitride layer is 0.4nm.

[0109] Example 7

[0110] (1) Place the Li5FeO4 material powder with a particle size D99 of 12μm into the reaction chamber of the atomic layer deposition equipment that is pre-filled with dry air, quickly evacuate the vacuum and raise the temperature of the reaction chamber, and keep the temperature of the reaction chamber at 130℃.

[0111] (2) Introduce the first metal source GaEt3 of the nitride layer into the reaction chamber and maintain it for 7s. Then, introduce argon gas into the reaction chamber for 15s to clean it and remove excess GaEt3.

[0112] (3) Introduce the nitrogen source NH3 of the nitride layer into the reaction chamber and maintain it for 5s. Then, introduce argon gas into the reaction chamber for 10s to clean it and remove excess NH3.

[0113] After repeating steps (2)-(3) 5 times, we can obtain Li5FeO4@GaN as a lithium replenishment material for Li5FeO4 cathode modified with GaN as nitride layer.

[0114] (4) Place the GaN-modified positive electrode lithium replenishment material Li5FeO4@GaN powder into the reaction chamber of an atomic layer deposition equipment pre-filled with dry air, quickly evacuate and raise the temperature of the reaction chamber, and keep the temperature of the reaction chamber at 240℃.

[0115] (5) Introduce the second metal source SnCl4 of the oxide layer into the reaction chamber and maintain it for 5s. Then, introduce argon gas into the reaction chamber for 10s to clean it and remove excess SnCl4.

[0116] (6) Introduce the oxygen source H2O2 from the oxide layer into the reaction chamber and maintain it for 9s. Then, introduce argon gas into the reaction chamber for 30s to clean it and remove excess H2O2.

[0117] After repeating steps (5)-(6) 10 times, a Li5FeO4 cathode lithium replenishment material Li5FeO4@GaN@SnO2 with GaN as the nitride layer and SnO2 as the oxide layer can be obtained.

[0118] (7) Place the GaN and SnO2 modified positive electrode lithium replenishment material Li5FeO4@GaN@SnO2 powder into the reaction chamber of an atomic layer deposition equipment pre-filled with dry air, quickly evacuate and raise the temperature of the reaction chamber, and keep the temperature of the reaction chamber at 100℃.

[0119] (8) Introduce Ti(NMe2)4, the first metal source of the nitride layer, into the reaction chamber and maintain it for 15s. Then, argon gas is introduced into the reaction chamber for 25s to clean it and remove excess Ti(NMe2)4.

[0120] (9) Introduce the nitrogen source N2H4 of the nitride layer into the reaction chamber and maintain it for 14s. Then, introduce argon gas into the reaction chamber for 20s to clean it and remove excess N2H4.

[0121] After repeating steps (8)-(9) 4 times, a Li5FeO4 cathode lithium replenishment material Li5FeO4@GaN@SnO2@TiN modified with GaN as the first nitride layer, SnO2 as the oxide layer, and TiN as the second nitride layer can be obtained. The thickness of the GaN nitride layer is 0.5 nm, the thickness of the SnO2 oxide layer is 1 nm, and the thickness of the TiN nitride layer is 0.4 nm.

[0122] Example 8

[0123] (1) Place the Li5FeO4 material powder with a particle size D99 of 12μm into the reaction chamber of the atomic layer deposition equipment that is pre-filled with dry air, quickly evacuate the vacuum and raise the temperature of the reaction chamber, and keep the temperature of the reaction chamber at 260℃.

[0124] (2) Introduce the second metal source Zn(OAc)2 of the oxide layer into the reaction chamber and maintain it for 11s. Then, introduce nitrogen gas into the reaction chamber for 10s to clean it and remove excess Zn(OAc)2.

[0125] (3) Introduce the oxygen source H2O from the oxide layer into the reaction chamber and maintain it for 12s. Then, introduce nitrogen gas into the reaction chamber for 15s to clean it and remove excess H2O.

[0126] After repeating steps (2)-(3) 6 times, we can obtain Li5FeO4@ZnO, a lithium supplement material for Li5FeO4 cathode modified with ZnO as oxide layer.

[0127] (4) Place the ZnO-modified positive electrode lithium replenishment material Li5FeO4@ZnO powder into the reaction chamber of an atomic layer deposition equipment pre-filled with dry air, quickly evacuate and raise the temperature of the reaction chamber, and keep the temperature of the reaction chamber at 80℃.

[0128] (5) Introduce the first metal source InEtMe2 of the nitride layer into the reaction chamber and maintain it for 8s. Then, argon gas is introduced into the reaction chamber for 20s to clean it and remove excess InEtMe2.

[0129] (6) Introduce NH3, the nitrogen source of the nitride layer, into the reaction chamber and maintain for 6s. Then, introduce argon gas into the reaction chamber for 15s to clean it and remove excess NH3.

[0130] After repeating steps (5)-(6) twice, a Li5FeO4@ZnO@InN cathode lithium replenishment material modified with ZnO as the oxide layer and InN as the nitride layer can be obtained.

[0131] (7) The positive electrode lithium replenishment material Li5FeO4@ZnO@InN powder modified by ZnO and InN is placed into the reaction chamber of an atomic layer deposition equipment pre-filled with dry air, and the vacuum is quickly drawn and the temperature of the reaction chamber is raised to maintain the temperature of the reaction chamber at 320℃.

[0132] (8) Introduce the second metal source Y(CpMe)3 of the oxide layer into the reaction chamber and maintain it for 9s. Then, introduce nitrogen gas into the reaction chamber for 30s to clean it and remove excess Y(CpMe)3.

[0133] (9) Introduce oxygen source O3 from the oxide layer into the reaction chamber and maintain for 9s. Then, introduce nitrogen gas into the reaction chamber for 25s to clean it and remove excess O3.

[0134] After repeating steps (8)-(9) 7 times, a Li5FeO4 cathode lithium replenishment material modified with ZnO as the first oxide layer, InN as the nitride layer, and Y2O3 as the second oxide layer can be obtained, namely Li5FeO4@ZnO@InN@Y2O3. The thickness of the ZnO oxide layer is 0.6 nm, the thickness of the InN nitride layer is 0.2 nm, and the thickness of the Y2O3 oxide layer is 0.7 nm.

[0135] Comparative Example 1

[0136] The positive electrode lithium replenishment material is the untreated Li5FeO4 material powder from Example 1.

[0137] Comparative Example 2

[0138] (1) Take Li5FeO4 (particle size D99 is 12μm) and titanium powder with a mass ratio of 50:1, mix them evenly, and sinter them at 1000℃ for 2h in a tube furnace under nitrogen atmosphere to obtain Li5FeO4@TiN as a lithium supplement material for Li5FeO4 cathode modified with TiN as nitride layer.

[0139] (2) The TiN-modified positive electrode lithium replenishment material Li5FeO4@TiN powder was added to an aluminum sulfate solution with a concentration of 1 mol / L and a mixture was prepared according to the molar ratio of aluminum ions to Li5FeO4 coated with TiN on the surface of 1:20.

[0140] (3) Slowly pour a 0.5 mol / L ammonium hydroxide solution into the mixture and stir until the solution becomes a paste, thereby forming an aluminum hydroxide precipitate layer on the surface of Li5FeO4@TiN;

[0141] (4) The above materials are placed in a tube furnace and sintered at 700°C for 6 hours under an argon atmosphere to obtain Li5FeO4 cathode lithium replenishment material Li5FeO4@TiN@Al2O3 modified with TiN as nitride layer and Al2O3 as oxide layer. The thickness of TiN nitride layer is 4nm and the thickness of Al2O3 oxide layer is 5nm.

[0142] The positive electrode lithium replenishment materials prepared in Examples 1-8 and Comparative Examples 1-2 were divided into two groups. One group underwent exposure treatment, being exposed to air at 25°C and 40% humidity for 24 hours. The other group was not subjected to any other treatment. The two groups of positive electrode lithium replenishment materials were used as positive electrode materials to fabricate coin cells. The positive electrode material, conductive carbon black, and polyvinylidene fluoride were dispersed in N-methylpyrrolidone at a mass ratio of 8:1:1. The positive electrode sheet was obtained by slurry preparation, coating, drying, and rolling. A lithium metal sheet was used as the negative electrode sheet, a Celgard 2400 polypropylene membrane was used as the separator, and a mixed solution of ethylene carbonate and dimethyl carbonate containing 1 mol / L lithium hexafluorophosphate (volume ratio 1:1) was used as the electrolyte. The battery was assembled with the above positive electrode sheet in an argon-filled glove box. The coin cells prepared from the positive electrode lithium replenishment materials of Examples 1-8 are designated as S1, S2, S3, S4, S5, S6, S7, and S8; the coin cells prepared from the positive electrode lithium replenishment materials of Comparative Examples 1-2 are designated as D1 and D2; the coin cells prepared from the positive electrode lithium replenishment materials of Examples 1-8 after exposure treatment are designated as S10, S20, S30, S40, S50, S60, S70, and S80; and the coin cells prepared from the positive electrode lithium replenishment materials of Comparative Examples 1-2 after exposure treatment are designated as D10 and D20.

[0143] Charge / discharge specific capacity test

[0144] The LAND battery testing system was used, with a charging cutoff voltage of 4.5V, a discharging cutoff voltage of 2.0V, and a charge / discharge rate of 0.1C. The specific capacity of the battery during the first charge and discharge was recorded, and the test results are shown in Table 1.

[0145] Table 1

[0146]

[0147] As shown in Table 1, the data from this application demonstrates that by modifying Li5FeO4 material with atomically thin nitride and oxide layers, the battery charge-discharge specific capacities obtained before and after exposure treatment are similar, indicating that the cathode lithium replenishment material of this application has significantly improved its tolerance and stability in air. In contrast, the unmodified Li5FeO4 material in Comparative Example 1 exhibits poor structural stability, with an initial charge-discharge specific capacity far lower than that after modification, and even complete loss of electrochemical activity after 24 hours of exposure to air. The cathode lithium replenishment material in Comparative Example 2, obtained through high-temperature solid-state sintering, has a thicker coating layer than Example 1, and its corresponding initial charge-discharge specific capacity and stability in air exposure are lower than those of the cathode lithium replenishment material obtained in Example 1. This application, by controlling the thickness of the nitride and oxide layers to the atomic level, not only improves the tolerance and stability of Li5FeO4 material in air and enhances battery safety, but also increases the initial charge-discharge specific capacity of the battery.

[0148] The preferred embodiments have been described in detail above, but the present invention is not limited to the specific implementation methods described above. Those skilled in the art can make various specific modifications under the guidance of this application without departing from the scope of protection of this application, and these modifications all fall within the scope of protection of the present invention.

Claims

1. A positive electrode lithium replenishment material, characterized in that, The positive electrode lithium replenishment material includes a Li5FeO4 core and a coating layer covering the outer surface of the Li5FeO4 core; the coating layer includes at least one nitride layer and at least two oxide layers alternately stacked; or, the coating layer includes at least two nitride layers and at least one oxide layer alternately stacked; the thickness of each nitride layer is 0.1 nm-0.5 nm, and the thickness of each oxide layer is 0.1 nm-1 nm.

2. The positive electrode lithium replenishment material as described in claim 1, characterized in that, The nitride layer includes one or more of AlN, TiN, GaN, NbN, and InN.

3. The positive electrode lithium replenishment material as described in claim 1 or 2, characterized in that, The oxide layer includes one or more of Al2O3, SiO2, TiO2, NiO, ZnO, Ga2O3, Y2O3, ZrO2, Nb2O5, In2O3, SnO2, HfO2, and Ta2O5.

4. The positive electrode lithium replenishment material according to any one of claims 1-3, characterized in that, The particle size D99 of the Li5FeO4 core is 1 μm-25 μm; the thickness of the coating layer is 0.3 nm-6 nm; the ratio of the total thickness of the nitride layer to the total thickness of the oxide layer in the coating layer is (0.05-10):

1.

5. The positive electrode lithium replenishment material as described in claim 4, characterized in that, The particle size D99 of the Li5FeO4 core is 1 μm-18 μm; the thickness of the coating layer is 0.3 nm-1.9 nm; the ratio of the total thickness of the nitride layer to the total thickness of the oxide layer in the coating layer is (0.125-1.5):

1.

6. A method for preparing a positive electrode lithium replenishment material as described in any one of claims 1-5, characterized in that, Includes the following steps: S101. Place the Li5FeO4 powder into the atomic layer deposition equipment; S102. Alternatingly introducing nitride and oxide sources into an atomic layer deposition apparatus to deposit at least one nitride layer and at least two oxide layers of alternating layers on the surface of the Li5FeO4 powder, or depositing at least two nitride layers and at least one oxide layer of alternating layers on the surface of the Li5FeO4 powder, wherein the order in which the nitride and oxide sources are introduced is not limited.

7. The method for preparing the positive electrode lithium replenishment material as described in claim 6, characterized in that, The nitride source includes a first metal source and a nitrogen source; the first metal source includes one or more of Al(NEt2)3, Al(NMe2)3, AlCl3, AlEt3, AlMe3, Ti(NEt2)4, Ti(NEtMe)4, Ti(NMe2)4, TiCl4, TiI4, GaCl3, GaEt3, GaMe3, NbCl5, InEtMe2, and InMe3, and the nitrogen source includes one or more of NH3, N2H4, and N2.

8. The method for preparing the positive electrode lithium replenishment material as described in claim 6 or 7, characterized in that, The oxide source includes a second metal source and an oxygen source; the second metal source includes Al(NEt2)3, Al(NMe2)3, Al(OEt)3, AlCl3, AlEt3, AlMe2Cl, AlMe3, Si(OEt)4, Si(OMe)4, Si2Cl6, SiCl2H2, SiCl3H, SiCl4, SiH(NMe2)3, SiH2(NEt2)2, and SiH2(NMe2)2. Ti(NEt2)4, Ti(NEtMe)4, Ti(NMe2)4, Ti(OEt)4, Ti(OMe)4, TiCl4, TiF4, TiI4, Ni(acac)2, Ni(CpE t)2, Ni(CpMe)2, NiCp2, Zn, Zn(OAc)2, ZnCl2, ZnEt2, ZnMe2, Ga(acac)3, Ga2(NMe2)6, GaEt3, GaMe3 , Y(CpBu)3, Y(CpEt)3, Y(CpMe)3, YCp3, Zr(NEt2)4, Zr(NEtMe)4, Zr(NMe2)4, ZrCl4, ZrCp2Cl2, Zr Cp2Me2, ZrI4, Nb(OEt)5, In(acac)3, InCl3, InEt3, InMe3, Sn(acac)2, Sn(NEtMe)4, Sn(NMe2)4, Sn The oxygen source includes one or more of Cl4, SnEt4, SnI4, SnMe4, Hf(NEt2)4, Hf(NEtMe)4, Hf(NMe2)4, HfCl4, HfCp2Cl2, HfCp2Me2, HfI4, Ta(NEt2)5, Ta(NMe2)5, Ta(OEt)5, TaCl5, TaF5, and TaI5, wherein the oxygen source includes one or more of H2O, O3, O2, and H2O2.

9. The method for preparing the positive electrode lithium replenishment material according to any one of claims 6-7, characterized in that, The reaction temperature in the atomic layer deposition equipment is 25℃-400℃.

10. A battery positive electrode, characterized in that, It includes a current collector and a positive electrode active material loaded on the current collector, wherein the positive electrode active material includes the positive electrode lithium replenishment material as described in any one of claims 1-5 or the positive electrode lithium replenishment material prepared by the preparation method as described in any one of claims 6-9.

11. A battery, characterized in that, The battery includes the positive electrode as described in claim 10.

12. An electrical appliance, characterized in that, The electrical device includes the battery as described in claim 11.

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