Prelithiated positive electrode material, and preparation method therefor and use thereof

Abstract

Provided in the present application are a prelithiated positive electrode material, and a preparation method therefor and the use thereof. The prelithiated positive electrode material comprises an active material core and a coating layer that coats the surface of the active material core, wherein the coating layer comprises prelithiation particles and carbon; the active material core comprises one or more of Lix1Fey1PO4, LiFex2Mn1-x2PO4, LiNix3Coy3Mn1-x3-y3O2 and LiNix4Coy4Al1-x4-y4O2, where 0.9≤x1≤1.1, 0.9≤y1≤1.1, 0<x2<1, 0<x3<1, 0<y3<1, 0<x4<1, and 0<y4<1; and the prelithiation particles comprise LiaCbOc, where 0<a≤6, 0<b≤6, and 0<c≤6.

Description

Lithium supplementing cathode material, preparation method and application thereof

[0001] The present application claims priority to the Chinese patent application No. 202411340742.9, filed on September 24, 2024, and entitled "Lithium supplementing cathode material, preparation method and application thereof", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] Embodiments of the present application relate to the technical field of lithium ion batteries, in particular to a lithium supplementing cathode material, a preparation method and application thereof. BACKGROUND

[0003] Lithium supplementing technology is an effective means to improve the energy density of lithium ion batteries while improving the cycle life and energy storage performance of the batteries. The existing common lithium supplementing technologies include negative electrode lithium supplementing, positive electrode lithium supplementing, electrolyte lithium supplementing, separator lithium supplementing, current collector lithium supplementing and electrochemical lithium supplementing. Among them, positive electrode lithium supplementing is one of the most commonly used means. Currently, the method for positive electrode lithium supplementing is usually to directly add a lithium supplementing agent into the positive electrode slurry during the homogenizing process, which will result in poor contact between the lithium supplementing agent and the positive electrode active material particles, leading to a high decomposition voltage, and thus causing problems such as gas production of the battery after lithium supplementing. In addition, the residual lithium supplementing agent residues in a high oxidation state remaining in the interior of the positive electrode sheet will increase the risk of side reactions when in contact with the electrolyte, thereby increasing the risk of gas production of the battery during use, especially in a high temperature environment. SUMMARY

[0004] In view of this, the present application provides a lithium supplementing cathode material, a preparation method and application thereof. The lithium supplementing cathode material is prepared by in-situ compounding carbon-oxygen-lithium compound lithium supplementing particles in the core of the positive electrode active material, so that the size of the lithium supplementing particles in the lithium supplementing cathode material is much smaller than that of the lithium supplementing agent commonly added in the positive electrode active slurry, thereby effectively reducing the risk of gelation of the positive electrode active slurry caused by residual alkali on the surface of the lithium supplementing agent, and effectively improving the electronic and ionic conduction capabilities of the lithium supplementing cathode material. In addition, the carbon-containing coating layer can effectively slow down the rate of water absorption failure of the lithium supplementing particles. Furthermore, the structure of the lithium supplementing cathode material can also effectively reduce the decomposition voltage, thereby solving the problem of gas production of the battery during the later use process.

[0005] The first aspect of the present application provides a lithium supplementing cathode material, which comprises an active material core and a coating layer coated on the surface of the active material core, wherein the coating layer comprises lithium supplementing particles and carbon; and the active material core comprises Li x1 Fe y1 PO4, LiFe x2 Mn 1-x2 PO4, LiNi x3 Co y3 Mn1-x3-y3 O2and LiNi x4 Co y4 Al 1-x4-y4 O2, wherein 0.9≤x1≤1.1, 0.9≤y1≤1.1, 0 a C b O c , wherein 0

[0006] In the embodiments of the present application, the carbon is coated on the surface of the active material inner core and / or the lithium supplementing particles.

[0007] In the embodiments of the present application, at least part of the lithium supplementing particles are grown in situ on the surface of the active material inner core.

[0008] In the embodiments of the present application, the lithium supplementing particles comprise one or more of Li2C4O4, Li2CO3, Li2C2O4 and Li6C6O6.

[0009] In the embodiments of the present application, the mass ratio of the lithium supplementing particles to the active material inner core is (0.1-10):100.

[0010] In the embodiments of the present application, the mass percentage of the carbon in the lithium supplementing positive electrode material is 0.1%-5%.

[0011] In the embodiments of the present application, the particle size of the active material inner core is 0.02 μm-50 μm, and the particle size of the lithium supplementing particles is 0.01 μm-10 μm.

[0012] In the embodiments of the present application, when the active material inner core is Li x1 Fe y1 PO4and / or LiFe x2 Mn 1-x2 PO4, the particle size of the active material inner core is 0.02 μm-15 μm, and the particle size of the lithium supplementing particles is 0.01 μm-8 μm; when the active material inner core is LiNi x3 Co y3 Mn 1-x3-y3 O2and / or LiNi x4 Co y4 Al 1-x4-y4 O2, the particle size of the active material inner core is 0.4 μm-50 μm, and the particle size of the lithium supplementing particles is 0.01 μm-10 μm.

[0013] In the embodiments of the present application, the specific surface area of the lithium supplementing positive electrode material is 0.2 m2 / g-20m 2 / g.

[0014] The second aspect of the present application provides a preparation method of the lithium supplementing cathode material provided in the first aspect of the present application, comprising the following steps:

[0015] mixing a lithium source, a phosphorus source, an iron source and a carbon source to obtain a lithium supplementing cathode material precursor; or mixing a lithium source, a phosphorus source, an iron source, a manganese source and a carbon source to obtain a lithium supplementing cathode material precursor;

[0016] sintering treatment is performed on the lithium supplementing cathode material precursor to obtain a lithium supplementing cathode material;

[0017] or, comprising:

[0018] mixing a lithium source, a nickel source, a cobalt source, and a manganese source or an aluminum source to obtain a lithium supplementing cathode material precursor;

[0019] sintering treatment is performed on the lithium supplementing cathode material precursor, and then secondary sintering treatment is performed after mixing with a carbon source to obtain a lithium supplementing cathode material.

[0020] In the embodiments of the present application, the temperature of the sintering treatment is 600-900℃, and the sintering time is 6-24h; the temperature of the secondary sintering treatment is 700-1000℃, and the sintering time is 2-8h.

[0021] The third aspect of the present application provides a positive electrode sheet, which comprises a current collector and a positive electrode active layer loaded on the current collector, and the positive electrode active layer comprises a lithium supplementing cathode material provided in the first aspect of the present application or a lithium supplementing cathode material prepared by the preparation method provided in the second aspect of the present application.

[0022] The fourth aspect of the present application provides a lithium ion battery, which comprises a positive electrode sheet provided in the third aspect of the present application.

[0023] The fifth aspect of the present application provides an electric device, which comprises a lithium ion battery provided in the fourth aspect of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0024] FIG. 1 is a schematic diagram of the cross-sectional structure of a lithium supplementing cathode material provided in an embodiment of the present application;

[0025] FIG. 2 is a schematic diagram of the cross-sectional structure of a lithium supplementing cathode material provided in another embodiment of the present application.

[0026] Explanation of reference numerals 100-lithium supplementing cathode material; 101-active material core; 102-lithium supplementing particle; 103-carbon. DETAILED DESCRIPTION

[0027] The application will be further described in connection with the preferred embodiments. However, the scope of the application is not limited to the following specific embodiments.

[0028] In the present application, all the professional terms have the same meanings as generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing the specific embodiments and are not intended to limit the scope of the application.

[0029] Lithium supplement technology is an effective means to improve the energy density of lithium ion batteries while improving the cycle life and energy storage performance of the batteries. The commonly used lithium supplement technologies include negative electrode lithium supplement, positive electrode lithium supplement, electrolyte lithium supplement, separator lithium supplement, current collector lithium supplement, and electrochemical lithium supplement. Among them, positive electrode lithium supplement is one of the most commonly used means. Currently, the method for positive electrode lithium supplement is usually to directly add the lithium supplement agent into the positive electrode slurry during the homogenizing process, which will make the contact between the lithium supplement agent and the positive electrode active material particles poor, resulting in a high decomposition voltage, and thus causing the battery to produce gas after lithium supplement. In addition, the residual lithium supplement agent residue in the positive electrode sheet in a high oxidation state will increase the risk of side reactions when in contact with the electrolyte, thereby increasing the risk of gas production during the use of the battery, especially in a high temperature environment. In addition, the commonly used lithium supplement agent usually has a large particle size, which is about one order of magnitude larger than the positive electrode active material, so that the lithium supplement agent particles shrink after decomposition, resulting in the formation of a collapse cavity around the lithium supplement agent particles, and thus causing the deterioration of the electrical contact between the positive electrode active materials in the positive electrode sheet.

[0030] Referring to FIG. 1, the present application provides a lithium supplement positive electrode material 100, which includes an active material inner core 101 and a coating layer coated on the surface of the active material inner core 101, wherein the coating layer includes lithium supplement particles 102 and carbon 103. In the present application, the active material inner core 101 includes Li x1 Fe y1 PO4, LiFe x2 Mn 1-x2 PO4, LiNi x3 Co y3 Mn 1-x3-y3 O2, and LiNi x4 Co y4 Al 1-x4-y4one or more of O2, wherein 0.9 < xi < 1.1, 0.9 < yi < 1.1, 0 < x2< 1, 0 < x3< 1, 0 < y3< 1, 0 < x4< 1, 0 < y4< 1. In some embodiments, xi can be, for example, 0.9, 0.95, 1, 1.05, 1.1; yi can be, for example, 0.9, 0.95, 1, 1.05, 1.1; x2may be, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9; x3may be, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95; y3may be, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95; x4may be, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95. y4may be, for example, 0.9, 0.95.

[0031] In embodiments of the application, the lithium supplement particles 102 comprise Li a C b O cwherein 0 < a < 6, 0 < b < 6, 0 < c < 6. In some embodiments, a can be, for example, 1, 2, 3, 4, 5, 6; b can be, for example, 1, 2, 3, 4, 5, 6; c can be, for example, 1, 2, 3, 4, 5, 6. The lithium supplementing cathode material of the present application supplements lithium by in-situ compounding carbon-oxygen-lithium compound lithium supplementing particles in the core of the cathode active material, without affecting the energy density of the active material core 101, the lithium supplementing particles 102 provide the function of supplementing lithium. Compared with the common method of supplementing lithium by directly adding a lithium supplementing agent to the active slurry, the lithium supplementing particles 102 are compounded with the active material core 101 in an in-situ growth manner, which can effectively improve the contact between the lithium supplementing particles 102 and the active material core 101, on the one hand, it can effectively reduce the decomposition starting voltage required for decomposition polarization, improve the decomposition rate, effectively avoid the gas production problem of the battery during the cyclic use, and thus improve the service life and safety performance of the battery; on the other hand, it can effectively shorten the electron transport path and lithium ion transport path, and improve the electronic conductivity and ionic conductivity of the lithium supplementing cathode material 100. The carbon-oxygen-lithium compound lithium supplementing particles used in the present application do not have residual metal oxides compared with other conventional lithium-rich metal oxide lithium supplementing agents, do not release oxygen and do not have metal element dissolution, have higher safety performance, and have lower cost than lithium-rich metal oxides, which can further reduce the preparation cost of the lithium supplementing cathode material. In addition, the carbon-oxygen-lithium compound has very high theoretical lithium supplementing capacity and stable chemical properties, does not absorb water and fail, is easier to produce and store, and thus widens the application scenarios of the lithium supplementing cathode material and reduces the production cost. However, the carbon-oxygen-lithium compound itself has high decomposition voltage and poor electrical conductivity, and it is difficult to use it alone as a lithium supplementing agent. The present application uses a coating layer containing carbon 103 to at least partially wrap the lithium supplementing particles 102 and the active material core 101, on the one hand, the lithium supplementing particles 102 and the active material core 101 are tightly combined, the decomposition voltage is effectively reduced, and on the other hand, the electrical conductivity of the lithium supplementing cathode material as a whole is also significantly improved. In the present application, the decomposition voltage and the decomposition rate can be measured by cyclic voltammetry.

[0032] In the embodiments of the present application, at least part of the lithium supplementing particles 102 are in-situ grown on the surface of the active material core 101.

[0033] In some embodiments of the present application, the structure of the lithium supplementing cathode material 100 is shown in FIG. 1, which includes an active material core 101, lithium supplementing particles 102 combined on the surface of the active material core 101, and a carbon 103 coating layer coated on the surface of the active material core 101 and / or the lithium supplementing particles 102, wherein the lithium supplementing particles 102 are in-situ grown on the surface of the active material core 101. In some embodiments of the present application, the lithium supplementing particles 102 are in direct contact with the surface of the active material core 101. The lithium supplementing particles in the lithium supplementing cathode material of this structure are larger in size, which further makes the specific surface area of the lithium supplementing cathode material smaller, and the stability of the lithium supplementing cathode material better.

[0034] In some other embodiments of the present application, the structure of the lithium supplementing cathode material 100 is shown in FIG. 2, which includes an active material core 101, and a coating layer coated on the surface of the active material core 101, wherein the coating layer includes lithium supplementing particles 102 and carbon 103, and the lithium supplementing particles 102 are distributed inside the coating layer formed by the carbon 103. In some embodiments of the present application, the lithium supplementing particles 102 are not in direct contact with the surface of the active material core 101, but are connected to the surface of the active material core 101 through the carbon 103.

[0035] In some embodiments of the present application, the carbon 103 is coated on the surface of the active material core 101 and / or the lithium supplementing particles 102. In some embodiments of the present application, the coating of the carbon 103 on the active material core 101 and the lithium supplementing particles 102 can be complete coating or incomplete coating. Through the coating of the carbon 103, the lithium supplementing cathode material 100 of the present application effectively reduces the contact area of the lithium supplementing particles 102 with air, which further reduces the rate of water absorption failure of the lithium supplementing particles 102 and effectively avoids the mixing of residual alkali on the surface of the lithium supplementing particles with the positive active paste to cause agglomeration, gelation and other phenomena, which further improves the utilization rate and service life of the lithium supplementing particles and reduces the cost of preparation, and can further improve the electrochemical performance of the battery product. The coating of the carbon 103 can also optimize the conductive network structure of the lithium supplementing cathode material, ensure the electronic path of the lithium supplementing particles 102 and the active material core 101, ensure the conductivity of the lithium supplementing cathode material 100 while adding the lithium supplementing particles 102, and further improve the lithium ion deintercalation path of the lithium supplementing particles 102 and the active material core 101, improve the ionic conductivity of the lithium supplementing cathode material 100, which further effectively reduces the decomposition voltage and accelerates the decomposition speed, effectively improves the decomposition efficiency, and alleviates the gas production problem during the use of the battery. And through the coating of the carbon 103, the active material core 101 and the lithium supplementing particles 102 are more closely combined, which can also reduce the decomposition voltage.

[0036] In some embodiments of the present application, the lithium supplementing particles 102 can be Li2C4O4 or Li2CO3. The lithium supplementing particles can further improve the lithium supplementing efficiency by selecting appropriate lithium oxycarbon compounds. Compared with lithium-rich metal oxides, the lithium oxycarbon compound particles do not remain after the first full charge and decomposition, effectively avoiding the risk of metal dissolution during subsequent battery use.

[0037] In some embodiments of the present application, the mass ratio of the lithium supplementing particles 102 to the active material core 101 is (0.1-10):100. In some specific embodiments, the mass ratio of the lithium supplementing particles 102 to the active material core 101 can be 0.1:100, 0.2:100, 0.3:100, 0.5:100, 0.8:100, 1:100, 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, or 10:100. By controlling the mass ratio of the lithium supplementing particles to the active material core within an appropriate range, the lithium supplementing positive electrode material can have a higher specific capacity, improve the utilization rate of the lithium supplementing particles, effectively avoid waste of the lithium supplementing particles, avoid side reactions caused by excessive lithium supplementing particles, and have better overall performance to meet different application requirements.

[0038] In some embodiments of the present application, the mass percentage of carbon 103 in the lithium supplementing positive electrode material 100 is 0.1%-5%. In some specific embodiments, the mass percentage of carbon 103 in the lithium supplementing positive electrode material 100 can be 0.1%, 0.2%, 0.3%, 0.5%, 0.6%, 0.8%, 1%, 2%, 3%, 4%, or 5%. By reasonably controlling the carbon content in the lithium supplementing positive electrode material, the thickness of the coating layer can be controlled, and the coating method and degree of carbon 103 on the active material core 101 and the lithium supplementing particles 102 can be comprehensively adjusted to control the power performance, cycle performance, and storage performance of the battery and meet different battery requirements.

[0039] In some embodiments of the present application, the particle size of the active material core 101 is 0.02 μm-50 μm, and the particle size of the lithium supplement particle 102 is 0.01 μm-10 μm. In some specific embodiments, the particle size of the active material core 101 can be, for example, 0.02 μm, 0.05 μm, 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, and the particle size of the lithium supplement particle 102 can be, for example, 0.01 μm, 0.02 μm, 0.05 μm, 0.1 μm, 0.5 μm, 1 μm, 2 μm, 5 μm, 8 μm, 10 μm.

[0040] In some embodiments of the present application, the active material core 101 is LiFePO4. x1 Fe y1 PO4and / or LiFe x2 Mn 1-x2 PO4, the particle size of the active material core 101 is 0.02 μm-15 μm, and the particle size of the lithium supplement particle 102 is 0.01 μm-8 μm. In some specific embodiments, the particle size of the active material core 101 can be, for example, 0.02 μm, 0.04 μm, 0.05 μm, 0.06 μm, 0.08 μm, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.8 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, and the particle size of the lithium supplement particle 102 can be, for example, 0.01 μm, 0.02 μm, 0.04 μm, 0.05 μm, 0.08 μm, 0.1 μm, 0.2 μm, 0.4 μm, 0.5 μm, 0.8 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 5 μm, 6 μm, 8 μm. In some embodiments, the particle size of the active material core 101 can be 0.2 μm-5 μm, and the particle size of the lithium supplement particle 102 can be 0.02 μm-3 μm. When the active material is a lithium iron phosphate type or a lithium manganese iron phosphate type positive electrode material, controlling the particle sizes of the active material core and the lithium supplement particle within the above ranges not only facilitates the processing of the lithium supplement positive electrode material particles, but also facilitates the processing stability of the slurry in the process of preparing the slurry, thereby further improving the specific capacity and rate performance of the lithium supplement positive electrode material and further reducing the decomposition voltage. In the present application, the particle size specifically refers to the median particle size D50, i.e., DV50, which refers to the particle size corresponding to the cumulative particle size distribution percentage of 50% of the measured sample, and the physical meaning is that the particles with a particle size greater than it account for 50%, and the particles with a particle size less than it also account for 50%.

[0041] In some embodiments of the present application, the specific surface area of the lithium supplement positive electrode material 100 is 3 m 2 / g-20 m 2 / g. In some embodiments, the specific surface area of the lithium supplementing cathode material 100 can be, for example, 3 m 2 / g, 5 m 2 / g, 6 m 2 / g, 8 m 2 / g, 10 m 2 / g, 12 m 2 / g, 14 m 2 / g, 15 m 2 / g, 16 m 2 / g, 18 m 2 / g, 20 m 2 / g. In some embodiments, the specific surface area of the lithium supplementing cathode material 100 can be 5 m 2 / g-18 m 2 / g. By controlling the particle size of the active material inner core and the lithium supplementing particles within a suitable range, and further controlling the specific surface area of the lithium supplementing cathode material within a suitable range, the stability of the lithium supplementing cathode material can be further improved, and the cycle performance and service life of the battery can be improved.

[0042] In some embodiments of the present application, the active material inner core 101 is LiNi x3 Co y3 Mn 1-x3-y3 O2and / or LiNi x4 Co y4 Al 1-x4-y4 O2, the particle size of the active material inner core 101 is 0.4 μm-50 μm, and the particle size of the lithium supplementing particles 102 is 0.01 μm-10 μm. In some embodiments, the particle size of the active material inner core 101 can be, for example, 0.4 μm, 0.5 μm, 1 μm, 2 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, or 50 μm; and the particle size of the lithium supplementing particles 102 can be, for example, 0.01 μm, 0.02 μm, 0.04 μm, 0.05 μm, 0.08 μm, 0.1 μm, 0.2 μm, 0.4 μm, 0.5 μm, 0.8 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 5 μm, 6 μm, 8 μm, or 10 μm. In some embodiments, the particle size of the active material inner core 101 can be 0.5 μm-20 μm, and the particle size of the lithium supplementing particles 102 can be 0.02 μm-4 μm. When the active material is a ternary layered oxide type cathode material, controlling the particle size of the active material inner core and the lithium supplementing particles within the above range not only facilitates the processing of the lithium supplementing cathode material particles, but also facilitates the processing stability of the slurry during the preparation of the slurry, thereby further improving the specific capacity and rate performance of the lithium supplementing cathode material and further reducing the decomposition voltage.

[0043] In some embodiments of the present application, the specific surface area of the lithium supplementing cathode material 100 is 0.2m 2 / g-2m 2 / g. In some specific embodiments, the specific surface area of the lithium supplementing cathode material 100 can be, for example, 0.2m 2 / g, 0.3m 2 / g, 0.5m 2 / g, 0.6m 2 / g, 0.8m 2 / g, 1m 2 / g, 1.2m 2 / g, 1.3m 2 / g, 1.5m 2 / g, 1.6m 2 / g, 1.8m 2 / g, 2m 2 / g. In some embodiments, the specific surface area of the lithium supplementing cathode material 100 can be 0.5m 2 / g-1.5m 2 / g. By controlling the particle size of the active material inner core and the lithium supplementing particles within a suitable range and further controlling the specific surface area of the lithium supplementing cathode material within a suitable range, the stability of the lithium supplementing cathode material can be further improved, and the cycle performance and service life of the battery can be improved.

[0044] The lithium supplementing cathode material provided in the present application can effectively avoid the gelation of the cathode active slurry and improve the electronic conductivity and ionic conductivity of the lithium supplementing cathode material by special design of the structure of the lithium supplementing cathode material, in-situ compounding of the lithium supplementing particles and the active material inner core, and coating with carbon.

[0045] The present application also provides a preparation method of the lithium supplementing cathode material provided above, comprising:

[0046] S101, mixing a lithium source, a phosphorus source, an iron source, and a carbon source to obtain a lithium supplementing cathode material precursor; or, mixing a lithium source, a phosphorus source, an iron source, a manganese source, and a carbon source to obtain a lithium supplementing cathode material precursor;

[0047] S102, performing sintering treatment on the lithium supplementing cathode material precursor to obtain a lithium supplementing cathode material;

[0048] or, comprising:

[0049] S201, mixing a lithium source, a nickel source, a cobalt source, and a manganese source or an aluminum source to obtain a lithium supplementing cathode material precursor;

[0050] S202, performing a sintering treatment on the lithium supplementing cathode material precursor, and then performing a secondary sintering treatment after mixing with a carbon source to obtain the lithium supplementing cathode material.

[0051] In step S101, the lithium source includes one or more of lithium carbonate, lithium hydroxide, lithium hydroxide monohydrate, lithium nitrate, lithium oxide, lithium peroxide, and lithium acetate; the phosphorus source includes one or more of lithium dihydrogen phosphate, iron phosphate, ammonium phosphate, sodium dihydrogen phosphate, lithium monohydrogen phosphate, lithium phytate, and sodium tripolyphosphate; the iron source includes one or more of ferrous oxide, diiron trioxide, iron nitrate, iron phosphate, ferrous oxalate, and ferrous sulfate; the carbon source includes one or more of a sugar, a high-molecular organic substance, and an electrically conductive carbon, and specifically includes one or more of glucose, sucrose, fructose, chitosan, lignin, carboxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, phenol formaldehyde resin, needle coke, petroleum coke, pitch coke, pitch, polystyrene, polyphenylacetylene, carbon black, acetylene black, super-P, carbon nanotube, graphene, ketjen black, and VGCF; and one or more of trimanganese tetroxide, manganese sulfate, manganese oxalate, manganese carbonate, manganese dioxide, and manganese acetate.

[0052] In some embodiments of the present application, the preparation raw materials of the lithium supplementing cathode material precursor include a lithium source, a phosphorus source, an iron source, and a carbon source, and the active material core of the prepared lithium supplementing cathode material is Li x1 Fe y1 PO4, 0.9≤x1≤1.1, 0.9≤y1≤1.1. In the embodiments of the present application, the feeding ratio of the lithium source, the phosphorus source, the iron source, and the carbon source is (1-1.2):(0.9-1.1):(0.9-1.1):(0.02-0.1).

[0053] In some other embodiments of the present application, the preparation raw materials of the lithium supplementing cathode material precursor include a lithium source, a phosphorus source, an iron source, a carbon source, and a manganese source, and the active material core of the prepared lithium supplementing cathode material is Li x2 Mn 1-x2 PO4, 0<x2<1. In the embodiments of the present application, the feeding ratio of the lithium source, the phosphorus source, the iron source, the carbon source, and the manganese source is (1-1.2):(0.9-1.1):(0.4-0.6):(0.05-0.1):(0.4-0.6).

[0054] In the embodiments of the present application, the mixing manner includes but is not limited to mixing by ball milling.

[0055] In step S102, the sintering treatment is performed in a protective atmosphere, which includes but is not limited to a nitrogen atmosphere or an argon atmosphere. In the embodiments of the present application, the sintering temperature of the sintering treatment is 600-900°C, and the sintering time is 6-24h. The sintering temperature of the sintering treatment may, for example, be 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, or 900°C; and the sintering time may, for example, be 6h, 8h, 10h, 12h, 15h, 16h, 20h, or 24h. The present application can produce the active material core particles of the lithium iron phosphate type or the lithium iron manganese phosphate type by controlling the temperature and time of the sintering treatment within a suitable range, and on this basis, in-situ composite lithium supplement particles, and at this temperature, the carbon source plays a reducing role on one hand, and can also obtain a carbon coating layer on the surface of the lithium supplement cathode material on the other hand.

[0056] In step S201, the lithium source includes one or more of lithium carbonate, lithium hydroxide, lithium hydroxide monohydrate, lithium nitrate, lithium oxide, lithium peroxide, and lithium acetate; the nickel source includes one or more of nickel oxides, nickel hydroxides, nickel sulfates, and nickel acetates; the cobalt source includes one or more of cobalt oxides, cobalt hydroxides, cobalt sulfates, and cobalt acetates; the manganese source includes one or more of manganese oxides, manganese hydroxides, manganese sulfates, and manganese acetates; and the aluminum source includes one or more of Al2O3, Al(OH)3, Al2(SO4)3, and Al(NO3)3.

[0057] In some embodiments of the present application, the preparation raw materials of the lithium supplement cathode material precursor include a lithium source, a nickel source, a cobalt source, and a manganese source, and the active material core of the lithium supplement cathode material produced is LiNi x3 Co y3 Mn 1-x3-y3 O2, 0 < x3 < 1, 0 < y3 < 1. In the embodiments of the present application, the feeding ratio of the lithium source, the nickel source, the cobalt source, and the manganese source is (1-1.2):(0.1-0.5):(0.1-0.5):(0.1-0.5).

[0058] In some embodiments of the present application, the preparation raw materials of the lithium supplement cathode material precursor include a lithium source, a nickel source, a cobalt source, and a manganese source, and the active material core of the lithium supplement cathode material produced is LiNi x4 Co y4 Al 1-x4-y4 O2, 0 < x4 < 1, 0 < y4 < 1. In the embodiments of the present application, the feeding ratio of the lithium source, the nickel source, the cobalt source, and the aluminum source is (1-1.2):(0.1-0.5):(0.1-0.5):(0.1-0.5).

[0059] In the embodiments of the present application, the mixing method includes, but is not limited to, ball milling. The ball milling time is 1 h-12 h. In some embodiments, the ball milling time can be, for example, 1 h, 2 h, 3 h, 5 h, 10 h, or 12 h.

[0060] In step S202, the sintering treatment is performed in an oxygen or air atmosphere. In the embodiments of the present application, the sintering temperature of the sintering treatment is 600-900°C, and the sintering time is 6-24 h. In some embodiments, the sintering temperature of the sintering treatment can be, for example, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, or 900°C; and the sintering time can be, for example, 6 h, 8 h, 10 h, 12 h, 15 h, 16 h, 20 h, or 24 h. By controlling the sintering temperature and time of the sintering treatment within a suitable range, the present application can prepare the formation and growth of the ternary layered oxide positive electrode material crystal.

[0061] In the embodiments of the present application, the secondary sintering treatment is performed in a protective atmosphere, which includes, but is not limited to, a nitrogen atmosphere or an argon atmosphere. In the embodiments of the present application, the sintering temperature of the secondary sintering treatment is 700-1000°C, and the sintering time is 2-8 h. In some embodiments, the sintering temperature of the secondary sintering treatment can be, for example, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, or 1000°C; and the sintering time can be, for example, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, or 8 h. By adding a carbon source during the secondary sintering treatment and controlling the temperature and time within a suitable range, the present application can cause the carbon source to be carbonized and obtain a carbon coating layer on the surface of the lithium supplement positive electrode.

[0062] The preparation method of the lithium supplement positive electrode material provided by the present application can control the feeding ratio of each raw material within a suitable range to obtain a lithium supplement positive electrode material in which the active material core is in-situ compounded with lithium supplement particles and coated with carbon. The size of the lithium supplement particles of the lithium supplement positive electrode material is much smaller than that of the conventional lithium supplement agent. The prepared lithium supplement positive electrode material has no metal oxide residue after lithium supplement, has lower requirements for the feeding of the positive electrode preparation and the coating process, is less likely to cause gelation during the preparation of the slurry, shortens the preparation process, reduces the production cost, and improves the yield of the finished product.

[0063] The application also provides a positive electrode sheet, which comprises a current collector and a positive electrode active layer loaded on the current collector, wherein the positive electrode active layer comprises the lithium supplementing positive electrode material provided in the foregoing or is prepared by the preparation method provided in the foregoing. In the embodiments of the application, the positive electrode active layer further comprises a binder and a conductive agent. In the embodiments of the application, the conductive agent can be any conductive agent known in the art, including but not limited to one or more of super P-Li, super P, acetylene black, graphene and carbon nanotubes. In the embodiments of the application, the binder can be any binder known in the art, including but not limited to polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyethylene oxide (PEO) and polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) and the like.

[0064] The application also provides a lithium ion battery, which comprises a positive electrode sheet, a negative electrode sheet, and a separator and an electrolyte between the positive electrode sheet and the negative electrode sheet, wherein the positive electrode sheet comprises the positive electrode sheet provided in the foregoing. In the embodiments of the application, the separator comprises but is not limited to a high molecular polymer film. In the embodiments of the application, the negative electrode sheet comprises a negative electrode current collector and a negative electrode active layer arranged on the negative electrode current collector, and the negative electrode active material in the negative electrode material layer can be any negative electrode active material for a lithium ion battery known in the art. In the embodiments of the application, the negative electrode active material in the negative electrode material layer can be any negative electrode active material for a lithium ion battery known in the art. Exemplarily, the negative electrode active material can be selected from one or more of a carbon-based negative electrode active material, a silicon-based negative electrode active material, a tin-based negative electrode active material and a lithium metal negative electrode active material. Among them, the carbon-based negative electrode includes but is not limited to natural graphite, artificial graphite, hard carbon, soft carbon, graphene; the silicon-based negative electrode includes but is not limited to silicon, silicon-carbon, silicon-oxygen and the like; the tin-based negative electrode includes but is not limited to tin, tin-carbon, tin-oxygen and tin metal compounds.

[0065] The application also provides an electric device, which comprises the lithium ion battery described in the foregoing. The electric device can be, for example, an electric vehicle, a mobile phone, a tablet computer, a notebook computer, a wearable device (watch, bracelet), a digital camera and the like.

[0066] The application is further described in the following embodiments:

[0067] Embodiment 1

[0068] Lithium carbonate and iron phosphate with a molar ratio of 1.01:2 were weighed and sintered at 650°C for 12h to obtain a lithium iron phosphate intermediate;

[0069] The lithium supplement anode material is prepared by taking lithium carbonate, lithium phosphate and glucose with a molar ratio of 1:0.03:0.03, ball-milling for 3 hours and then sintering at 850 DEG C for 4 hours, wherein the active material core is LiFePO4, the coating layer comprises lithium supplement particles and carbon, and the lithium supplement particles are Li2CO3.

[0070] The prepared lithium supplement anode material is dissolved in N-methyl pyrrolidone solvent to prepare anode slurry, the obtained anode slurry is uniformly coated on an aluminum foil and vacuum dried to obtain a lithium supplement anode sheet.

[0071] Example 2

[0072] The lithium supplement anode material is prepared by taking lithium carbonate, lithium phosphate and glucose with a molar ratio of 1:0.03:0.03, ball-milling for 3 hours and then sintering at 850 DEG C for 4 hours, wherein the active material core is LiFePO4, the coating layer comprises lithium supplement particles and carbon, and the lithium supplement particles are Li2CO3.

[0073] The lithium supplement anode material is prepared by taking lithium carbonate, lithium phosphate and glucose with a molar ratio of 1:0.03:0.03, ball-milling for 3 hours and then sintering at 850 DEG C for 4 hours, wherein the active material core is LiFePO4, the coating layer comprises lithium supplement particles and carbon, and the lithium supplement particles are Li2CO3. 0.4 Mn 0.6 PO4, the coating layer comprises lithium supplement particles and carbon, and the lithium supplement particles are Li2CO3; the prepared lithium supplement anode material is dissolved in N-methyl pyrrolidone solvent to prepare anode slurry, the obtained anode slurry is uniformly coated on an aluminum foil and vacuum dried to obtain a lithium supplement anode sheet.

[0074] Example 3

[0075] The ternary material intermediate NiCoMn(OH)2 is prepared by taking NiSO4·H2O, CoSO4·H2O and MnSO4·H2O with a molar ratio of 5:2:3, dissolving them into a mixed solution of sodium hydroxide and ammonia water, and then sintering at 850 DEG C for 9 hours. 0.5 Co 0.2 Mn 0.3 (OH)2.

[0076] The lithium supplement anode material is prepared by taking lithium carbonate, lithium phosphate and glucose with a molar ratio of 1:0.03:0.03, ball-milling for 3 hours and then sintering at 850 DEG C for 4 hours, wherein the active material core is LiFePO4, the coating layer comprises lithium supplement particles and carbon, and the lithium supplement particles are Li2CO3. 0.5 Co 0.2 Mn 0.3 (OH)2 and lithium carbonate, and sintering at 850 DEG C for 9 hours to obtain the active material core intermediate LiNi 0.5 Co 0.2 Mn 0.3 O2.

[0077] The lithium supplement anode material is prepared by taking lithium carbonate, lithium phosphate and glucose with a molar ratio of 1:0.03:0.03, ball-milling for 3 hours and then sintering at 850 DEG C for 4 hours, wherein the active material core is LiFePO4, the coating layer comprises lithium supplement particles and carbon, and the lithium supplement particles are Li2CO3. 0.5 Co 0.2 Mn 0.3O2, Li2CO3, and glucose, ball-milling mixed for 3h and then sintered at 950℃ for 4h to obtain the lithium-supplemented cathode material, wherein the active material core is LiNi 0.5 Co 0.2 Mn 0.3 O2, the coating layer comprising lithium-supplemented particles and carbon, the lithium-supplemented particles being Li2CO3;

[0078] The prepared lithium-supplemented cathode material is dissolved in N-methyl pyrrolidone solvent to prepare a cathode slurry, the obtained cathode slurry is uniformly coated on an aluminum foil and vacuum dried to obtain a lithium-supplemented cathode sheet.

[0079] Example 4

[0080] Lithium iron phosphate intermediates are obtained by sintering lithium carbonate and iron phosphate at a molar ratio of 1.01:2 at 650℃ for 12h;

[0081] Lithium-supplemented cathode material is obtained by sintering lithium iron phosphate intermediates, Li2C4O4, and glucose at a molar ratio of 1:0.03:0.03 at 850℃ for 4h after ball-milling mixed for 3h, wherein the active material core is LiFePO4, and the coating layer comprises lithium-supplemented particles and carbon, the lithium-supplemented particles being Li2C4O4; the prepared lithium-supplemented cathode material is dissolved in N-methyl pyrrolidone solvent to prepare a cathode slurry, the obtained cathode slurry is uniformly coated on an aluminum foil and vacuum dried to obtain a lithium-supplemented cathode sheet.

[0082] Example 5

[0083] Lithium iron phosphate intermediates are obtained by sintering lithium carbonate and iron phosphate at a molar ratio of 1.01:2 at 650℃ for 12h;

[0084] Lithium-supplemented cathode material is obtained by sintering lithium iron phosphate intermediates, lithium carbonate, and glucose at a molar ratio of 1:0.06:0.03 at 850℃ for 4h after ball-milling mixed for 3h, wherein the active material core is LiFePO4, and the coating layer comprises lithium-supplemented particles and carbon, the lithium-supplemented particles being Li2CO3; the prepared lithium-supplemented cathode material is dissolved in N-methyl pyrrolidone solvent to prepare a cathode slurry, the obtained cathode slurry is uniformly coated on an aluminum foil and vacuum dried to obtain a lithium-supplemented cathode sheet.

[0085] Example 6

[0086] Lithium iron phosphate intermediates are obtained by sintering lithium carbonate and iron phosphate at a molar ratio of 1.01:2 at 650℃ for 12h;

[0087] The lithium supplement anode material is prepared by taking 100 parts by weight of the active material lithium iron phosphate, 1.4 parts by weight of lithium carbonate as the lithium supplement agent, and 0.2 parts by weight of glucose as the carbon source, mixing them in a ball mill for 3 hours, and then sintering them at 850 DEG C for 4 hours.

[0088] Example 7

[0089] The lithium iron phosphate intermediate is prepared by taking lithium carbonate and iron phosphate in a molar ratio of 1.01:2, sintering them at 650 DEG C for 12 hours;

[0090] The lithium supplement anode material is prepared by taking 100 parts by weight of the active material lithium iron phosphate, 1.4 parts by weight of lithium carbonate as the lithium supplement agent, and 0.2 parts by weight of glucose as the carbon source, mixing them in a ball mill for 3 hours, and then sintering them at 850 DEG C for 4 hours.

[0091] Comparative Example 1

[0092] The lithium supplement anode material is prepared by taking 100 parts by weight of the active material lithium iron phosphate, 1.4 parts by weight of lithium carbonate as the lithium supplement agent, and 0.2 parts by weight of glucose as the carbon source, mixing them in a ball mill for 3 hours, and then sintering them at 850 DEG C for 4 hours.

[0093] Performance detection

[0094] Specific surface area: The lithium supplement anode materials of Examples 1-7 are tested according to the national standard "Gas adsorption BET method for determining the specific surface area of solid substances" (GB / T 19587-2017), and the specific surface area is measured. The results are shown in Table 1.

[0095] Particle size D50: The particle size of the active material core and the lithium supplement particles of Examples 1-7 and the lithium supplement particles of Comparative Example 1 is tested by a laser particle size distribution instrument. The measured particle size D50 is shown in Table 1.

[0096] Mass percentage of carbon in lithium supplement material: The carbon content of the active material of Examples 1-7 is quantified by thermal gravimetric analysis (TGA). The mass percentage of each example is shown in Table 1.

[0097] The lithium supplement positive electrode plate prepared from Example 1 to Example 7 and Comparative Example 1 is combined with a negative electrode, a separator and an electrolyte to form a soft package battery.

[0098] Gas production performance: the soft package batteries prepared from Example 1 to Example 7 and Comparative Example 1 are adjusted to 100%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10% and 0% in turn, and after 28 days of storage at 60°C, the weight of the batteries is tested by the drainage method, the gas production performance of the batteries is calculated and counted by the weight difference, and the results are shown in Table 1.

[0099] Cycle performance: the soft package batteries prepared from Example 1 to Example 7 and Comparative Example 1 are cycled at 45°C under the conditions of 0.5C CC-CV to 3.7V cutoff current of 0.05C charging and 0.5C discharging to 2.3V, and after 1000 cycles, the capacity retention rate of the batteries relative to the capacity of the batteries before cycling is observed, and the results are shown in Table 1.

[0100] Rate performance: the soft package batteries prepared from Example 1 to Example 7 and Comparative Example 1 are cycled at 25°C under the conditions of 0.5C CC-CV to 3.7V cutoff current of 0.05C charging and 0.1C discharging to 2.3V, and the capacity is recorded as C1; the batteries are cycled at 25°C under the conditions of 0.5C CC-CV to 3.7V cutoff current of 0.05C charging and 2C discharging to 2.3V, and the capacity is recorded as C2; the 2C / 0.1C capacity retention rate is calculated according to the formula: C2 / C1*100%, and the results are shown in Table 1.

[0101] Table 1

[0102] As can be seen from Table 1, compared with Comparative Example 1 in which lithium supplement particles are directly added to the active slurry, in the present application, the lithium supplement particles are in-situ compounded in the core of the positive electrode active material and coated with carbon material, which significantly reduces the particle size of the lithium supplement particles, effectively reduces the risk of gelation of the positive electrode active slurry caused by residual alkali on the surface of the lithium supplement particles, and improves the electronic and ionic conductivity of the lithium supplement positive electrode material, reduces the initial decomposition voltage, improves the decomposition rate, reduces the gas production of the battery, and further improves the cycle performance and rate performance of the battery.

[0103] The preferred embodiments are described in detail above, but the present application is not limited to the specific embodiments described above, and those skilled in the art can make various specific modifications under the inspiration of the present application without departing from the scope of the present application, and these all belong to the protection scope of the present application.

Claims

1. A lithium supplemented cathode material, wherein, The lithium supplement positive electrode material comprises an active material core and a coating layer coated on the surface of the active material core, the coating layer comprises lithium supplement particles and carbon; the active material core comprises Li x1 Fe y1 PO4, LiFe x2 Mn 1-x2 PO4, LiNi x3 Co y3 Mn 1-x3-y3 O2, and LiNi x4 Co y4 Al 1-x4-y4 O2, wherein 0.9≤x1≤1.1, 0.9≤y1≤1.1, 0 a C b O c , wherein 0 2. The lithium supplemented cathode material of claim 1, wherein, The carbon is coated on the surface of the active material inner core and / or the surface of the lithium supplementing particles.

3. The lithium supplementing cathode material of claim 1 or 2, wherein, At least part of the lithium supplementing particles are grown in-situ on the surface of the active material inner core.

4. The lithium supplementing cathode material of any one of claims 1-3, wherein, The lithium supplementing particles include one or more of Li2C4O4, Li2CO3, Li2C2O4 and Li6C6O6.

5. The lithium supplementing cathode material of any one of claims 1-4, wherein, The mass ratio of the lithium supplementing particles to the active material inner core is (0.1-10):

100.

6. The lithium supplementing cathode material of any one of claims 1-5, wherein, The mass percentage of the carbon in the lithium supplementing positive electrode material is 0.1%-5%.

7. The lithium supplementing cathode material of any one of claims 1-6, wherein, The particle size of the active material inner core is 0.02-50 μm, and the particle size of the lithium supplementing particles is 0.01-10 μm.

8. The lithium-replenishing cathode material of claim 7, wherein, when the active material core is LiFe x1 Fe y1 PO4and / or LiFe x2 Mn 1-x2 PO4, the particle size of the active material core is 0.02-15 μm, and the particle size of the lithium supplement particles is 0.01-8 μm; when the active material core is LiNi x3 Co y3 Mn 1-x3-y3 O2and / or LiNi x4 Co y4 Al 1-x4-y4 O2, the particle size of the active material core is 0.4-50 μm, and the particle size of the lithium supplement particles is 0.01-10 μm.

9. The lithium-replenishing cathode material of any one of claims 1-8, wherein, The specific surface area of the lithium supplementing positive electrode material is 0.2 m 2 / g-20 m 2 / g.

10. A method of preparing a lithium supplemented cathode material as claimed in any one of claims 1 to 9, wherein, The method comprises: Mixing a lithium source, a phosphorus source, an iron source and a carbon source to obtain a lithium supplementing positive electrode material precursor; Or, mixing a lithium source, a phosphorus source, an iron source, a manganese source and a carbon source to obtain a lithium supplementing positive electrode material precursor; Sintering the lithium supplementing positive electrode material precursor to obtain a lithium supplementing positive electrode material; Or, the method comprises: Mixing a lithium source, a nickel source, a cobalt source and a manganese source or an aluminum source to obtain a lithium supplementing positive electrode material precursor; Sintering the lithium supplementing positive electrode material precursor, mixing a carbon source and then performing secondary sintering to obtain a lithium supplementing positive electrode material.

11. The method of preparing a lithium supplemented cathode material of claim 10, wherein, The sintering temperature is 600-900 ℃, and the sintering time is 6-24 h; the secondary sintering temperature is 700-1000 ℃, and the sintering time is 2-8 h.

12. A positive electrode sheet, wherein The positive electrode sheet comprises a current collector and a positive electrode active layer loaded on the current collector, and the positive electrode active layer comprises the lithium supplementing positive electrode material according to any one of claims 1-9 or the lithium supplementing positive electrode material prepared by the preparation method according to any one of claims 10-11.

13. A lithium-ion battery, wherein, The lithium ion battery comprises the positive electrode sheet according to claim 12.

14. An electrical device, comprising: The electric device comprises the lithium ion battery according to claim 13.

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