Negative electrode material and method for manufacturing the same, and battery

Abstract

The present invention provides a negative electrode material, a method for manufacturing the same, and a battery. [Solution] The negative electrode material contains secondary particles, which are aggregates of primary particles containing active material doped with iron and nickel. If the mass content of iron in the negative electrode material is A ppm and the mass content of nickel in the negative electrode material is B ppm, then A and B satisfy the following equation. 9.2 ≤ A / B ≤ 20 The negative electrode material according to this application enhances the hardness of nanosilicon, improves the stability of nanosilicon particles, reduces volume changes of the negative electrode material, and ultimately improves the cycle stability of the battery.

Description

[Technical Field]

[0001] (Cross-reference of related applications) This application claims priority based on a Chinese patent application filed with the China Patent Administration on September 28, 2023, with application number 202311294624.4, titled "Negative electrode material, method for manufacturing the same, and battery," the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to the technical field of negative electrode materials, and more specifically to negative electrode materials, methods for manufacturing the same, and batteries. [Background technology]

[0003] In recent years, with the development of the market, the demand for high-energy-density anode materials has increased. Lithium batteries are used not only in mobile devices such as smartphones and portable computers, but also in electric vehicles. As research shows, long driving range is a point of great interest to consumers, and the length of a powered vehicle's range directly affects the user experience. Therefore, there is a need to develop power batteries with higher energy density. Positive and negative electrode materials are the core of a battery and determine its operating efficiency. Currently, the commercially available anode material is graphite, and its capacity is already close to its theoretical limit, leaving little room for further improvement. Therefore, the development of next-generation high-energy-density anode materials is eagerly awaited.

[0004] Silicon anodes, generally considered the next-generation battery anode material, possess advantages such as high capacity, abundant sources, and relative safety. However, silicon anode materials exhibit a rapid volume expansion effect during the cycle process, which can cause pulverization and fragmentation of the material, potentially accelerating battery degradation over time.

[0005] Therefore, reducing the pulverization and crushing of silicon materials and improving the cycle stability of silicon anode materials remain urgent priorities. [Overview of the project] [Problems that the invention aims to solve]

[0006] This application provides a negative electrode material that can strengthen the hardness of negative electrode material particles and improve the cycle stability of negative electrode material particles, a method for manufacturing the same, and a battery. [Means for solving the problem]

[0007] In the first embodiment, the present application is, A negative electrode material containing secondary particles, The aforementioned secondary particles include multiple aggregated primary particles, The primary particles include an active material doped with iron and nickel elements. If the mass content of the iron element in the negative electrode material is A ppm and the mass content of the nickel element in the negative electrode material is B ppm, then A and B provide a negative electrode material that satisfies the following equation. 9.2 ≤ A / B ≤ 20

[0008] In the second embodiment, the present application is, A method for manufacturing a negative electrode material, A mixture containing a silicon source precursor, an iron dopant, and a nickel dopant is heat-treated to obtain primary particles doped with iron and nickel, and The process includes coating primary particles to obtain the negative electrode material, The present invention provides a method for manufacturing a negative electrode material, wherein the mass content of iron in the negative electrode material is A ppm, and the mass content of nickel in the negative electrode material is B ppm, such that A and B satisfy the following equation. 9.2 ≤ A / B ≤ 20

[0009] In a third embodiment, the present application provides a battery comprising the negative electrode material described above or a negative electrode material manufactured by the manufacturing method described above. [Effects of the Invention]

[0010] The proposed technology has at least the following beneficial effects.

[0011] According to the negative electrode material provided in this application, the negative electrode material contains secondary particles, the secondary particles contain a plurality of aggregated primary particles, and the primary particles contain an active material doped with iron and nickel. If the mass content of iron in the negative electrode material is A ppm and the mass content of nickel in the negative electrode material is B ppm, then A and B satisfy the following equation. 9.2 ≤ A / B ≤ 20 By adding iron and nickel elements to the negative electrode material, iron-nickel co-doping occurs. Since nickel has a higher atomic number than iron and a larger volume difference between nickel and silicon atoms, the solid solution strengthening effect becomes more pronounced, and the hardness of the negative electrode material can be enhanced by iron-nickel co-doping. Furthermore, controlling the content of iron doped into the negative electrode material to be higher than that of nickel is because iron atoms have less effect on volume due to heat, while nickel atoms have a greater volume expansion effect after being heated compared to iron atoms. Therefore, by controlling the A / B ratio within the above range, the volume expansion effect of the doped metal elements can be reduced while strengthening the hardness of the negative electrode material. In turn, the volume expansion stress of the negative electrode material can be effectively relieved, the structural stability of the negative electrode material can be increased, the cycle life of batteries manufactured with the negative electrode material can be improved, and the resulting negative electrode material can have good electronic conductivity and electrochemical properties.

[0012] In the method for manufacturing the negative electrode material provided in the present application, by heat-treating a mixture containing a silicon source precursor, an iron dopant, and a nickel dopant, primary particles doped with iron and nickel are obtained. The primary particles contain an active material doped with iron and nickel. Further, by coating the primary particles, a negative electrode material doped with iron and nickel is obtained. By adding iron elements and nickel elements to the primary particles, the hardness of the primary particles is enhanced, the volume expansion of the active material is effectively alleviated, the structural stability of the negative electrode material is improved, and the cycle life of the battery manufactured with the negative electrode material can be improved. Moreover, the entire manufacturing process is simple, and industrialized manufacturing is easy. The manufactured negative electrode material has a stable structure, an improved initial Coulomb efficiency, an improved structural stability of the negative electrode material, and an improved cycle stability of the negative electrode material.

Brief Description of the Drawings

[0013] [Figure 1] It is a process flow diagram of the method for manufacturing the negative electrode material according to the present application. [Figure 2] It is a scanning electron microscope (SEM) photograph of the negative electrode material manufactured in Example 1 of the present application. [Figure 3] It is an XRD chart of the negative electrode material manufactured in Example 1 of the present application. [Figure 4] It is a diagram showing the first charge-discharge curve of the negative electrode material manufactured in Example 1 of the present application. [Figure 5] It is a diagram showing the cycle characteristic curve of the negative electrode material manufactured in Example 1 of the present application.

Modes for Carrying Out the Invention

[0014] In order to better explain the present invention and make the technical solution of the present invention easier to understand, the present invention will be described in more detail below. It should be noted that the following examples are merely simple examples of the present invention and do not indicate or limit the protection scope of the present application. The scope of the present invention is indicated by the scope of the claims.

[0015] In a first aspect, the present application provides a negative electrode material containing secondary particles, The aforementioned secondary particles contain multiple aggregated primary particles containing an active material doped with iron and nickel elements. If the mass content of iron in the negative electrode material is A ppm and the mass content of nickel in the negative electrode material is B ppm, then A and B provide a negative electrode material that satisfies the following equation. 9.2 ≤ A / B ≤ 20 In this invention, the term "primary particle" refers to the primary structure of a single particle. The term "secondary particle" refers to an aggregate formed when primary particles aggregate through physical or chemical bonding between them, i.e., a secondary structure. However, the aggregation or combination process of the primary particles constituting the secondary particle does not necessarily have to be intentional.

[0016] According to the negative electrode material provided in this application, the negative electrode material contains secondary particles, the secondary particles contain multiple aggregated primary particles, and the primary particles contain an active material doped with iron and nickel. If the mass content of iron in the negative electrode material is A ppm and the mass content of nickel in the negative electrode material is B ppm, then A and B satisfy the equation 9.2 ≤ A / B ≤ 20. By adding iron and nickel to the negative electrode material, iron-nickel co-doping occurs. Since nickel has a larger atomic number than iron, and the volume difference between nickel atoms and silicon atoms is greater, the solid solution strengthening effect becomes more pronounced, and the hardness of the negative electrode material can be strengthened by the co-doping of iron-nickel. Furthermore, controlling the content of iron doped into the negative electrode material to be higher than that of nickel is because iron atoms are less affected by heat in terms of volume, while nickel atoms have a greater volume expansion effect after being heated compared to iron atoms. Therefore, by controlling the A / B ratio within the above range, the volume expansion effect of the doping metal element can be reduced while strengthening the hardness of the negative electrode material. This effectively mitigates the volume expansion of the active material, increases the structural stability of the negative electrode material, improves the cycle life of batteries made with the negative electrode material, and allows the resulting negative electrode material to have good electronic conductivity and electrochemical properties.

[0017] Specifically, the ratio of the mass content of iron element A ppm to the mass content of nickel element B ppm in the negative electrode material, i.e., A / B, may be 9.2, 10, 12, 14, 16, 18, 20, etc., and is not limited thereto. By controlling the ratio of the mass content of iron element to the mass content of nickel element, and by doping the negative electrode material with nickel and iron elements, the hardness of the negative electrode material can be improved, which can resist stress due to the expansion of the active material during the roll pressing or charge-discharge process of the electrode sheet, suppress particle pulverization and crushing, and improve the cycle stability of batteries made with the negative electrode material.

[0018] In some embodiments, the active material is a substance that reacts with lithium and is capable of releasing and storing lithium.

[0019] The active material comprises at least one of elemental metals, metal oxides, and metal alloys. Furthermore, the metal comprises at least one of Li, Na, K, Sn, Ge, Si, Fe, Mg, Ti, Zn, Al, P, and Cu. Elemental metals refer to the elemental form of the above-mentioned metals, metal oxides refer to oxides of the above-mentioned metals, and metal alloys refer to alloys containing at least one of the above-mentioned metals.

[0020] In some embodiments, the active material includes a silicon-based material, which includes at least one of crystalline silicon, amorphous silicon, silicon oxide, silicon alloy, and composites of crystalline silicon and amorphous silicon. Specifically, the silicon alloy may be a lithium silicon alloy, a magnesium silicon alloy, etc. Of course, the lithium silicon alloy may also include both elemental particles and alloys.

[0021] In some embodiments, the total mass content of iron and nickel in the negative electrode material is less than 1%, specifically 0.99%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, or 0.1%, but is not limited to these values; values ​​not listed can also be applied as long as they are within this range. As a result of repeated tests, it was found that controlling the amount of iron and nickel added within the above ranges clearly improves material performance, but when the total mass content of iron and nickel in the negative electrode material exceeds the above range, the magnetism of iron and nickel has a significant effect on the negative electrode material, which is detrimental to the cycle stability of batteries manufactured with this negative electrode material. As is clear, by controlling the mass content of iron and nickel elements in the negative electrode material, the magnetic material in the negative electrode material can be controlled so as not to exceed standards, thereby reducing the effect of magnetic field action on the fatigue and degradation of the negative electrode material, improving the hardness of the negative electrode material without affecting its electrochemical properties, resisting stress due to expansion, suppressing particle pulverization and fragmentation, and improving the cycle stability of batteries manufactured with the negative electrode material.

[0022] In some embodiments, if the mass content of iron in the negative electrode material is A ppm, then A satisfies the equation 0.1 ≤ A ≤ 1000. More specifically, A may be 0.1 ppm, 20 ppm, 100 ppm, 300 ppm, 500 ppm, 700 ppm, 900 ppm, or 1000 ppm, but is not limited to these values. Any other value within this range that is not listed can be applied.

[0023] In some embodiments, if the mass content of nickel in the negative electrode material is B ppm, then B satisfies the equation 0.1 ≤ B ≤ 500. More specifically, B may be 0.1 ppm, 20 ppm, 100 ppm, 200 ppm, 300 ppm, 400 ppm, or 500 ppm, but is not limited to these values. Any other value within this range that is not listed can be applied.

[0024] In some embodiments, the average particle diameter D of the primary particles 50 is from 1 nm to 500 nm, specifically, it may be 1 nm, 50 nm, 100 nm, 200 nm, 300 nm, 400 nm or 500 nm, etc., but is not limited thereto, and values not listed within these numerical ranges are equally applicable. As a result of repeated tests, it was found that nanoscale primary particles have high surface energy, strong particle structure, and can suppress the volume expansion of silicon. However, for nanoscale primary particles,the smaller the particle diameter, the greater the surface energy, so aggregation is likely to occur during the charge-discharge process, and if the particle diameter is too small, the cost of the manufacturing process is high. The average particle diameter D of the primary particles 50 is preferably from1 nm to 200 nm, more preferably from 5 nm to 100 nm.

[0025] In some embodiments, the particle diameter of the primary particles satisfies (D 100 -D 10 ) / D 50 ≧1.5, specifically, it may be 1.5 nm, 2 nm, 5 nm, 10 nm, 50 nm, 100 nm, 200 nm, etc., but is not limited thereto, and values not listed within these numerical ranges are equally applicable. Note that the particle diameter of the primary particles is small, and particle size analysis statistics are performed on the SEM using Nano Measure software to obtain the average particle diameter D 50 , D 10 and the maximum particle diameter D 100 0. The specific measurement method is as follows. The SEM photo is at a magnification of 50K, and the sizes of 200 particles in the SEM photo are measured using Nano Measure software. The average particle diameter of the 200 particles is calculated as D1, and the maximum value among the 200 particles is taken as the maximum value D2 of the primary particles. After that, this is repeated to measure the results in at least 10 SEM photos, and the average value of the average values is calculated. The maximum value of the primary particles is the maximum value D 100 of the particles in at least 10 SEM statistics measured. The average particle diameter of the primary particles was (D1 + D2 + ··· + D10) / 10 of the average particle diameter of the 10th statistics. D10 This indicates the corresponding particle size when the cumulative particle size distribution percentage of the powder reaches 10%.

[0026] In some embodiments, the anode material further comprises a carbon material located on at least a portion of the surface of the secondary particles and / or the primary particles. The carbon material forms a carbon layer. Specifically, the carbon layer comprises amorphous carbon, which has good compatibility with the electrolyte, thereby ensuring the stability of the electrical properties of the anode material during the charge-discharge process. Exemplarily, the amorphous carbon in the carbon layer may be derived from at least one of petroleum pitch, coal pitch, reformed pitch, and mesophase pitch, and formed by carbonization.

[0027] In some embodiments, the active material includes a silicon-based material, which is further doped with oxygen. The mass content of oxygen in the negative electrode material is 0.1% to 18%, specifically 0.1%, 1%, 3%, 6%, 9%, 12%, 15%, 18%, etc., but is not limited to these values; values ​​not listed can also be applied as long as they are within this range. By adding oxygen within the above range, the volume expansion of the silicon-based material can be reduced, and the cycle performance of batteries manufactured with negative electrode materials containing silicon-based materials can be improved. If the oxygen content in the silicon-based material is too high, the capacity and initial Coulomb efficiency of the negative electrode material containing silicon-based materials will decrease.

[0028] In some embodiments, the specific surface area of ​​the negative electrode material is 0.1 m². 2 / g~5m 2 It is / g, specifically 0.1m 2 / g, 0.3m 2 / g, 0.5m 2 / g, 1.0m 2 / g, 1.8m 2 / g, 2.6m 2 / g, 3.5m 2 / g, 5.0m 2It may be / g, and of course, it may be any other value within the above range, and is not limited thereto. Controlling the specific surface area of ​​the negative electrode material within the above range is advantageous for improving the cycle performance of lithium batteries manufactured from said negative electrode material.

[0029] In some embodiments, the median diameter of the anode material is 0.5 μm to 30 μm, specifically 0.5 μm, 1 μm, 5 μm, 8 μm, 10 μm, 13 μm, 15 μm, 18 μm, 20 μm, 25 μm, or 30 μm, and of course, may be other values ​​within the above range, but is not limited thereto. Controlling the median diameter of the anode material within the above range helps to improve the cycle performance of the anode material.

[0030] In a second embodiment, the present application provides a method for manufacturing a negative electrode material, as shown in Figure 1, comprising the following steps. S10: A mixture containing an active material precursor, an iron dopant, and a nickel dopant is heat-treated to obtain primary particles doped with iron and nickel; S20: Primary particles are coated to obtain the negative electrode material. Here, if the mass content of iron in the negative electrode material is A ppm and the mass content of nickel in the negative electrode material is B ppm, then A and B satisfy the equation 9.2 ≤ A / B ≤ 20.

[0031] In the method for manufacturing a negative electrode material provided in this application, primary particles doped with iron and nickel are obtained by heat-treating a mixture containing an active material precursor, an iron dopant, and a nickel dopant. Furthermore, the primary particles doped with iron and nickel are subjected to a coating treatment to obtain a negative electrode material doped with iron and nickel. By adding iron and nickel elements to the primary particles, the hardness of the primary particles is strengthened, the volume expansion during the lithium release and absorption process of the negative electrode material is effectively mitigated, the structural stability of the negative electrode material is improved, and the cycle life of batteries manufactured with the negative electrode material can be improved. Moreover, the entire manufacturing process is simple and easy to industrialize. The manufactured negative electrode material has a stable structure, improved initial Coulomb efficiency, improved structural stability of the negative electrode material, and improved cycle stability of batteries manufactured with the negative electrode material.

[0032] The manufacturing method provided by the present invention will be described in detail below.

[0033] S10: A mixture containing an active material precursor, an iron dopant, and a nickel dopant is heat-treated to obtain primary particles doped with iron and nickel.

[0034] In some embodiments, the iron dopant is iron powder, iron nitrate, nickel nitrate, ferrous lactate (C6H 10 It contains at least one of the following: FeO6·3H2O), iron citrate (FeC6H5O7), yellow blood salt (K4[Fe(CN)6]·3H2O), iron glycinate (Fe[C2H4O2N]2), and ferrocene (Fe(C5H5)2).

[0035] In some embodiments, the nickel dopant comprises at least one of nickel oleate, nickel propionate, nickel butyrate, nickel octylate, nickel lactate, nickel benzoate, bis(acetylacetonate)nickel, nickel salicylate, and alkylphenylsalicylate.

[0036] In some embodiments, the step of heat-treating a mixture containing an active material precursor, an iron dopant, and a nickel dopant includes forming primary particles from a gas-phase active material, such as a silicon source precursor, by gas-phase deposition, and doping the primary particles with metal vapors generated from the iron dopant and nickel dopant. Both the iron dopant and nickel dopant are compounds that decompose easily at low temperatures, and when heated, these compounds decompose to generate vapors containing metal elements.

[0037] In some embodiments, the temperature of gas-phase deposition is 300°C to 1000°C, and more specifically, it may be 300°C, 350°C, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C, or 1000°C, but is not limited to these values, and any other values ​​not listed within this range can be applied.

[0038] In some embodiments, the gas-phase silicon source precursor includes at least one of silane, disilane, trisilane, tetrasilane, and monosilane.

[0039] In some embodiments, the flow rate of the gas phase silicon source precursor is 5 scc to 1000 scc, and more specifically, it may be 5 scc, 30 scc, 60 scc, 200 scc, 300 scc, 600 scc, 800 scc, or 1000 scc, but is not limited to these values, and any other values ​​not listed within this range can be applied.

[0040] In some embodiments, the mass ratio of iron dopant to nickel dopant is 0.1 to 30, specifically 0.1, 0.5, 1, 2, 5, 8, 10, 15, 20, 25, or 30, but is not limited to these values; any other value within this range can be applied.

[0041] In some embodiments, the step of heat-treating a mixture containing a silicon source precursor, an iron dopant, and a nickel dopant may employ liquid-phase mixing, specifically including adding a metal reducing agent to a mixture containing a liquid-phase silicon source precursor, an iron dopant, and a nickel dopant, separating the solid-liquid mixture, and then heat-treating the resulting mixture to obtain nickel and iron-doped primary particles.

[0042] In some embodiments, the liquid-phase silicon source precursor comprises at least one of trichlorosilane, silicon tetrachloride, methylchlorosilane, polysilane, and triethylchlorosilane.

[0043] In some embodiments, the mass ratio of the liquid-phase silicon source precursor, iron dopant, nickel dopant, and metal reducing agent is (40-100):(0.01-1):(0.05-1):(0.01-5). Specifically, this may be 40:0.01:0.05:0.01, 40:0.05:0.1:0.1, 40:0.05:0.1:0.5, 100:1:0.5:0.1, or 100:1:1:5, but is not limited to these values, and any other values ​​not listed can be applied within these ranges.

[0044] In some embodiments, the metal reducing agent includes at least one of magnesium powder, zinc powder, aluminum powder, lithium powder, sodium powder, and potassium powder.

[0045] In some embodiments, the mass ratio of the metal reducing agent to the liquid-phase silicon source precursor is (0.01-5):100.

[0046] In some embodiments, the heat treatment temperature is 400 to 1200°C, and the heat treatment time is 1 to 15 hours. Specifically, the heat treatment temperature may be 400°C, 500°C, 600°C, 700°C, 800°C, 950°C, 1500°C, 1200°C, etc., and the heat treatment time may be 1 hour, 2 hours, 4 hours, 6 hours, 9 hours, 11 hours, 12 hours, 14 hours, 15 hours, etc., but is not limited thereto.

[0047] In some embodiments, a coating agent is further added to the mixture, the mixture is heat-treated under the protection of an inert gas, and then acid-treated to obtain nickel and iron-doped primary particles.

[0048] In some embodiments, the coating agent comprises at least one of a liquid-phase carbon source or a solid-phase carbon source. Exemplarily, the solid-phase carbon source comprises at least one of sugars, esters, hydrocarbons, organic acids, and polymeric polymers.

[0049] In some embodiments, the inert gas includes at least one of helium gas, neon gas, argon gas, krypton gas, and xenon gas.

[0050] In some embodiments, the heat treatment temperature is 500°C to 1000°C, more specifically 500°C, 600°C, 700°C, 800°C, 900°C, or 1000°C, but is not limited to these values; any value not listed within this range can be applied. The heat treatment time is 11 to 115 hours, more specifically 11 hours, 20 hours, 30 hours, 50 hours, 70 hours, 80 hours, 90 hours, 100 hours, 115 hours, etc., but is not limited thereto.

[0051] In some embodiments, the acid used for acid treatment includes at least one of hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, and acetic acid.

[0052] S20: Primary particles are coated to obtain the negative electrode material. Here, if the mass content of iron in the negative electrode material is A ppm and the mass content of nickel in the negative electrode material is B ppm, then A and B satisfy the equation 9.2 ≤ A / B ≤ 20.

[0053] In some embodiments, the coating process includes at least one of a solid-phase carbon coating process, a liquid-phase carbon coating process, and a gas-phase carbon coating process.

[0054] In some embodiments, the coating treatment is a solid-phase carbon coating treatment, which specifically involves carbonizing a mixture of primary particles and a solid-phase carbon source to obtain a negative electrode material.

[0055] In some embodiments, the carbonization temperature is 500°C to 1000°C. Specifically, it may be 500°C, 600°C, 650°C, 800°C, 950°C, 1000°C, etc., but is not limited to these values, and any value not listed within this range can be applied. The holding time for the carbonization is 30 minutes to 24 hours, specifically, it may be 30 minutes, 2 hours, 5 hours, 8 hours, 11 hours, 13 hours, 16 hours, 17 hours, 18 hours, 20 hours, 24 hours, etc., but is not limited to these values, and any value not listed within this range can be applied.

[0056] By controlling the carbonization temperature within an appropriate range, it is possible to reduce the occurrence of thermal decomposition of primary particles due to excessively high temperatures and insufficient carbonization of primary particles due to excessively low temperatures. This allows for sufficient carbonization of the primary particle coating layer, leading to better mixing of primary particles with the solid-phase carbon source and reducing product resistance.

[0057] In some embodiments, the solid-phase carbon source comprises at least one of sugars, esters, hydrocarbons, organic acids, and polymeric polymers.

[0058] In some embodiments, the solid-phase carbon source includes at least one of polyvinyl chloride, polyvinyl butyral, polyacrylonitrile, polyacrylic acid, polyethylene glycol, polypyrrole, polyaniline, sucrose, glucose, maltose, citric acid, pitch, furfural resin, epoxy resin, and phenolic resin.

[0059] In some embodiments, the mass ratio of the solid-phase carbon source to the primary particles is 5:(5~95), specifically 5:5, 5:15, 5:35, 5:50, 5:60, 5:75, 5:95, etc., but is not limited to these values; any other values ​​within this range that are not listed can also be applied.

[0060] In a third embodiment, the present application provides a battery comprising the negative electrode material described in the first embodiment or a negative electrode material manufactured by the manufacturing method described in the second embodiment.

[0061] In some other embodiments, the negative electrode material may be applied to a lithium-ion battery or to other electrochemical devices such as a sodium-ion battery.

[0062] As will be apparent to those skilled in the art, the methods for manufacturing lithium-ion batteries described above are merely embodiments. Other methods commonly used in the art can be employed without departing from the scope of this application.

[0063] The embodiments of the present application will be further described below with reference to several examples. However, the embodiments of the present application are not limited to the following specific examples. They can be implemented with appropriate modifications within the scope of protection. [Examples]

[0064] Example 1 The method for manufacturing the negative electrode material in this embodiment includes the following steps. (1) 35 g of iron nitrate powder Fe(NO3) and 20.8 g of nickel nitrate powder Ni(NO3) were placed on the substrate of a gas-phase chemical deposition apparatus. Then silane was introduced, the flow rate of the silane was controlled to 50 scc, the temperature was raised to 600°C, and the gas-phase deposition reaction was carried out for 1 hour to obtain primary particles. (2) The primary particles and phenolic resin were mixed in a mass ratio of 40:43. The mixture was then placed in a high-temperature box-type furnace, nitrogen gas was introduced, and the mixture was carbonized at 950°C for 2 hours. The carbonized product was then crushed, sieved, and classified to obtain the anode material.

[0065] The negative electrode material manufactured in this embodiment contains secondary particles, the secondary particles contain a plurality of aggregated primary particles, the primary particles contain silicon particles doped with iron and nickel, and if the mass content of iron in the negative electrode material is A ppm and the mass content of nickel in the negative electrode material is B ppm, then the ratio of A / B is 9.2.

[0066] Figure 2 is a scanning electron microscope image of the negative electrode material manufactured in Example 1.

[0067] Figure 3 is an XRD chart of the negative electrode material manufactured in Example 1. As can be seen from the chart, the negative electrode material exhibits characteristic peaks of silicon-based materials.

[0068] Figure 4 shows the initial charge-discharge curve of the negative electrode material manufactured in Example 1. As can be seen from Figure 4, the initial charge-discharge capacity of the negative electrode material is high, reaching 1855 mAh / g, and the initial Coulomb efficiency is also high.

[0069] Figure 5 shows the cycle characteristic curve of the anode material manufactured in Example 1. As can be seen from Figure 5, the capacity retention rate of the anode material after 100 cycles is 94.2%, indicating that the anode material has excellent cycle characteristics.

[0070] Example 2 The method for manufacturing the negative electrode material in this embodiment includes the following steps. (1) Silicon tetrachloride, iron chloride solution, and nickel chloride solution were added to a reaction vessel and mixed. Then, metallic magnesium powder was added, with a mass ratio of silicon tetrachloride:magnesium:iron chloride:nickel chloride of 100:28.5:0.5:0.03. The mixture was heated to 300°C in a sealed state and the reduction reaction was carried out for 15 hours to obtain primary particles with an A / B ratio of 14.4. (2) The primary particles and sucrose were mixed in a mass ratio of 55:69. The mixture was then placed in a high-temperature box-type furnace, nitrogen gas was introduced, and the mixture was carbonized at 920°C for 4 hours. The carbonized product was then pulverized, sieved, and subsequently classified to obtain the anode material.

[0071] The negative electrode material manufactured in this embodiment contains secondary particles, the secondary particles contain a plurality of aggregated primary particles, the primary particles contain silicon particles doped with iron and nickel, and if the mass content of iron in the negative electrode material is A ppm and the mass content of nickel in the negative electrode material is B ppm, then the ratio of A / B is 14.4.

[0072] Example 3 (1) Silicon dioxide nanoparticles, metallic aluminum powder, and mixed pitch with a mass ratio of silicon dioxide nanoparticles:metallic aluminum:mixed pitch of 180:25:110 were added to a reaction vessel. Then, 0.6 g of iron chloride and 0.1 g of nickel chloride were added, and the mixture was heated to 950°C in an argon gas atmosphere and reacted for 12 hours. After cooling, the product was washed by immersion in an acid solution and dried to obtain primary particles with an A / B ratio of 9.6. (2) The primary particles and phenolic resin were mixed in a mass ratio of 50:65. The mixture was then placed in a high-temperature box-type furnace, nitrogen gas was introduced, and the mixture was carbonized at 980°C for 5 hours. The carbonized product was then crushed, sieved, and classified to obtain the anode material.

[0073] The negative electrode material manufactured in this embodiment contains secondary particles, the secondary particles contain a plurality of aggregated primary particles, the primary particles contain silicon particles doped with iron and nickel, and if the mass content of iron in the negative electrode material is A ppm and the mass content of nickel in the negative electrode material is B ppm, then the ratio of A / B is 9.6.

[0074] Example 4 (1) 39 g of iron nitrate powder Fe(NO3) and 21.8 g of nickel nitrate powder Ni(NO3) were placed on the substrate of a gas-phase chemical deposition apparatus. Then, silane and acetylene gases were introduced, the volume ratio of silane to acetylene was controlled to 25:1, the flow rate of silane and acetylene was controlled to 60 scc, the temperature was raised to 700°C, and the gas-phase deposition reaction was carried out for 3 hours to obtain primary particles. (2) The primary particles and phenolic resin were mixed in a mass ratio of 30:45. The mixture was then placed in a high-temperature box-type furnace, nitrogen gas was introduced, and the mixture was carbonized at 820°C for 4 hours. The carbonized product was then crushed, sieved, and classified to obtain the anode material.

[0075] The negative electrode material manufactured in this embodiment includes secondary particles, the secondary particles include a plurality of aggregated primary particles, the negative electrode material further includes carbon material located on at least a portion of the surface of the secondary particles and primary particles, the primary particles include silicon particles doped with iron and nickel, and if the mass content of iron in the negative electrode material is A ppm and the mass content of nickel in the negative electrode material is B ppm, then the ratio of A / B is 10.6.

[0076] Example 5 (1) Trichlorosilane solution was added to the reaction vessel, and then equal volume proportions of fructose solution and metallic zinc powder were added, where the mass ratio of trichlorosilane:metallic zinc powder:fructose was 100:29.5:11.4. Then, 1.6 g of iron chloride and 0.3 g of nickel chloride were added, and the temperature was raised to 350°C in a sealed state and the reaction was carried out for 15 hours, followed by centrifugal drying to obtain primary particles. (2) The primary particles and sucrose were mixed in a mass ratio of 20:45. The mixture was then placed in a high-temperature box-type furnace, nitrogen gas was introduced, and the mixture was carbonized at 950°C for 2 hours. The carbonized product was then crushed, sieved, and classified to obtain the anode material.

[0077] The negative electrode material manufactured in this embodiment includes secondary particles, the secondary particles include a plurality of aggregated primary particles, the negative electrode material further includes carbon material located on at least a portion of the surface of the secondary particles and primary particles, the primary particles include silicon particles doped with iron and nickel, and if the mass content of iron in the negative electrode material is A ppm and the mass content of nickel in the negative electrode material is B ppm, then the ratio of A / B is 19.

[0078] Example 6 (1) Using 400g of commercially available SiO particles as raw material, 31g of iron nitrate Fe(NO3) and 20.1g of nickel nitrate powder Ni(NO3) were added, and polishing was carried out in a nitrogen gas atmosphere at a rotation speed of 400 rpm for a polishing time of 6 hours to obtain primary particles. (2) The primary particles and phenolic resin were mixed in a mass ratio of 40:33. The mixture was then placed in a high-temperature box-type furnace, nitrogen gas was introduced, and the mixture was carbonized at 950°C for 2 hours. The carbonized product was then crushed, sieved, and classified to obtain the anode material.

[0079] The negative electrode material manufactured in this embodiment contains secondary particles, the secondary particles contain a plurality of aggregated primary particles, the primary particles contain silicon particles doped with iron and nickel, and if the mass content of iron in the negative electrode material is A ppm and the mass content of nickel in the negative electrode material is B ppm, then the ratio of A / B is 9.9.

[0080] Example 7 (1) Using 600g of commercially available LiSi particles as raw material, 31g of iron nitrate Fe(NO3) and 20.09g of nickel nitrate powder Ni(NO3) were added, and polishing was carried out in an argon gas atmosphere at a rotation speed of 450 rpm for a polishing time of 5 hours to obtain primary particles. (2) The primary particles and polyvinyl alcohol were mixed in a mass ratio of 50:56. The mixture was then placed in a high-temperature box furnace, nitrogen gas was introduced, and the mixture was carbonized at 850°C for 6 hours. The carbonized product was then crushed, sieved, and classified to obtain the anode material.

[0081] The negative electrode material manufactured in this embodiment contains secondary particles, the secondary particles contain a plurality of aggregated primary particles, the primary particles contain silicon particles doped with iron and nickel, and if the mass content of iron in the negative electrode material is A ppm and the mass content of nickel in the negative electrode material is B ppm, then the ratio of A / B is 9.3.

[0082] Comparative Example 1 The difference from Example 1 is that the negative electrode material is obtained without performing the coating treatment in step (2).

[0083] The negative electrode material produced in this comparative example includes primary particles containing an active material doped with iron and nickel elements.

[0084] Comparative Example 2 The difference from Example 1 is that (1) 0.5 g of iron nitrate powder and 0.32 g of nickel nitrate powder are placed on the substrate of the gas-phase chemical deposition apparatus, then silane is introduced, the flow rate of the silane is controlled to 50 scc, the temperature is raised to 600°C, and the reaction is carried out for 1 hour to obtain primary particles.

[0085] The negative electrode material manufactured in this embodiment contains primary particles including silicon particles doped with iron and nickel. If the mass content of iron in the negative electrode material is A ppm and the mass content of nickel in the negative electrode material is B ppm, then the A / B ratio is 9.0.

[0086] Comparative Example 3 The difference from Example 1 is that (1) 12 g of iron nitrate powder and 1 g of nickel nitrate powder are placed on the substrate of the CVD apparatus, then silane is introduced, the flow rate of the silane is controlled to 50 scc, the temperature is raised to 600°C, and the reaction is carried out for 1 hour to obtain primary particles.

[0087] The negative electrode material manufactured in this embodiment contains primary particles including silicon particles doped with iron and nickel. If the mass content of iron in the negative electrode material is A ppm and the mass content of nickel in the negative electrode material is B ppm, then the A / B ratio is 21.2.

[0088] Comparative Example 4 The difference from Example 1 is that the negative electrode material is obtained without performing Fe and Ni doping in step (1).

[0089] The negative electrode material manufactured in this embodiment includes secondary particles containing a plurality of aggregated primary particles, the primary particles containing silicon particles.

[0090] Comparative Example 5 The difference from Example 1 is that 17.2 g of iron nitrate powder Fe(NO3)3 is placed on the substrate of the gas-phase chemical deposition apparatus, then silane is introduced, the silane flow rate is controlled to 50 scc, the temperature is raised to 600°C, and the gas-phase deposition reaction is carried out for 1 hour to obtain primary particles.

[0091] The negative electrode material manufactured in this embodiment contains secondary particles, the secondary particles contain a plurality of aggregated primary particles, the primary particles contain silicon particles, and if the mass content of iron in the negative electrode material is A ppm and the mass content of nickel in the negative electrode material is B ppm, then the ratio of A / B is 82.

[0092] Comparative Example 6 The difference from Example 1 is that 20.8 g of nickel nitrate powder Ni(NO3) is placed on the substrate of the gas-phase chemical deposition apparatus, then silane is introduced, the silane flow rate is controlled to 50 scc, the temperature is raised to 600°C, and the gas-phase deposition reaction is carried out for 1 hour to obtain primary particles.

[0093] The negative electrode material produced in this embodiment contains secondary particles, the secondary particles contain a plurality of aggregated primary particles, the primary particles contain silicon particles, and if the mass content of iron in the negative electrode material is A ppm and the mass content of nickel in the negative electrode material is B ppm, then the ratio of A / B is 0.06.

[0094] Measurement method: (1) Measurement of the mass content of iron and nickel in the negative electrode material The Fe and Ni content in the particles is measured using the ICP method, based on GB / T38823-2020. (2) Particle size of primary particles The SEM image is set to 50K magnification, and the size of 200 particles in the SEM image is measured using Nano Measure software. The average particle diameter of the 200 particles is calculated as D1, and the maximum value among the 200 particles is taken as the maximum primary particle value D2. This process is then repeated to measure the results for at least 10 SEM images, and the average of the average values ​​is calculated. The maximum primary particle value is the maximum particle value in the 10 SEM statistics. The average particle diameter of the primary particle is (D1 + D2 + ... + D10) / 10 of the average particle diameter of the 10th-order statistics. (3) Specific surface area of ​​the negative electrode material The measurement was performed using the JW-DX dynamic specific surface area high-speed measuring instrument from Beijing Jingwei Gaobo Science and Technology Co., Ltd., and the unit is m. 2 It is / g. (4) Median diameter of the negative electrode material The particle size distribution range of the negative electrode material is measured using a Malvern laser particle size analyzer. (5) Measurement of the mass content of oxygen element in the negative electrode material The oxygen content of the negative electrode material is measured using an oxygen content meter, with ISO 17053:2005 as the measurement standard. (6) Measurement of indentation hardness in negative electrode material Indentation hardness is measured using a nanoindenter with a load of 0.6 N and an indentation depth of 0.5 μm. (7) Measurement of electrochemical properties Using the negative electrode materials produced in the examples and comparative examples, respectively, the negative electrode material, carboxymethylcellulose, and styrene-butadiene rubber are dissolved in N-methylpyrrolidone in a mass ratio of 94:1:5, the solid content is controlled to 50%, and the mixture is applied to a copper foil current collector and vacuum-dried to produce a negative electrode sheet. A metallic lithium sheet is used as the counter electrode, and a 1 mol / L LiPF6 / (ethylene carbonate + dimethyl carbonate + ethyl methyl carbonate) (v / v=1:1:1) electrolyte, a Celgard 2400 separator, and an 18650 cylindrical single cell as the housing are mounted using a normal manufacturing process to assemble a cylindrical battery. The charge-discharge test of the cylindrical battery is performed using LAND battery test equipment manufactured by Wuhan LAND electronics Co., Ltd., under room temperature conditions, with constant current charging and discharging at 0.2C, and the charge-discharge voltage is controlled between 2.75 and 4.2V. Using a micrometer, the initial thickness H0 of the lithium-ion battery plates was measured, and the initial reversible ratio capacity, initial cycle charge capacity, and initial cycle discharge capacity were obtained by repeatedly charging and discharging the battery. Initial Coulomb efficiency = Initial cycle discharge capacity / Initial cycle charge capacity

[0095] The results of the above performance measurements are shown in the table below.

[0096] [Table 1]

[0097] As can be seen from Table 1 and the test data from Examples 1 to 7, by adding appropriate amounts of iron and nickel to nanosilicon, the hardness of the nanosilicon is strengthened, the volume expansion of the nanosilicon-containing anode material is effectively mitigated, the structural stability of the anode material is improved, the cycle life of batteries manufactured with the anode material is improved, and the resulting anode material can have good electronic conductivity and electrochemical properties.

[0098] In Example 6, the active material is silicon oxide (SiO), and because its theoretical capacity is relatively low, the initial reversible capacity and initial Coulombic efficiency of the manufactured anode material are relatively reduced. However, by adding appropriate amounts of iron and nickel, the hardness of the anode material can be strengthened, the volume expansion during the lithium release and absorption process of the anode material can be effectively mitigated, the structural stability of the anode material can be improved, and the cycle life of the battery manufactured with the anode material can be improved.

[0099] In Comparative Example 1, compared to Example 1, the primary particles were not coated during the manufacturing process of the graphite anode material, making it difficult to improve the product's performance, and both the initial Coulombic efficiency and cycle performance of the battery were reduced. As can be seen from this, the coated carbon material reduces the decrease in initial Coulombic efficiency caused by side reactions occurring when the electrolyte enters the interior, while the primary particles, which are synergistically doped with iron and nickel elements, mitigate the volume expansion of silicon, reducing the overall volume expansion of the composite anode material and the volume expansion of the electrode sheet, thereby improving the cycle stability of batteries manufactured with this anode material.

[0100] In Comparative Examples 2 and 3, the ratio of doped iron and nickel elements, i.e., A / B, was not within the scope of the present invention compared to Example 1, and the cycle performance of batteries manufactured with the negative electrode material was reduced in both cases. Furthermore, if the amount of doped iron and nickel elements is too small, the effect on the volume expansion of the primary particles is weak, and the volume expansion of the negative electrode material due to the process of silicon releasing and absorbing lithium cannot be effectively mitigated. On the other hand, if the amount of doped iron and nickel elements is too large, they themselves are magnetic, which adversely affects the negative electrode material, making it even more difficult to mitigate the volume expansion of the negative electrode material.

[0101] In Comparative Example 4, compared to Example 1, the iron and nickel elements were not doped into the negative electrode material. As a result, the indentation hardness of the primary particles of the negative electrode material was significantly reduced, and during the charge-discharge cycle process, the particles were more prone to fragmentation due to the volume expansion stress during the process of lithium release and absorption. Consequently, the cycle stability of the battery made with the negative electrode material was reduced.

[0102] In Comparative Example 5, compared to Example 1, only iron nitrate was added, resulting in an excessively large A / B ratio in the final anode material. This means that too much iron was added, causing the magnetism of the iron to significantly affect the anode material, which is detrimental to the cycle stability of the anode material.

[0103] Comparative Example 6, compared to Example 1, only nickel nitrate is added, and the volume expansion effect of the nickel element under heating is clear. As a result, the volume expansion of the active material becomes more severe, and the expansion suppression effect of a single nickel element is worse compared to the case where nickel and iron elements work together, which is unfavorable for the cycle stability of the anode material.

[0104] While the present application has described the detailed process apparatus and process flow using the above-described embodiments, the applicant has stated that it is not limited to the above-described detailed process apparatus and process flow; that is, the present application is not limited to the above-described detailed process apparatus and process flow. As will be apparent to those skilled in the art, any improvements to the present application, equivalent substitutions of each raw material of the present product, addition of auxiliary components, selection of specific methods, etc., are all within the scope of the claims and disclosures of the present application.

Claims

1. A negative electrode material containing secondary particles, The aforementioned secondary particles include multiple aggregated primary particles, The primary particles include an active material doped with iron and nickel elements. A negative electrode material characterized in that, if the mass content of the iron element in the negative electrode material is A ppm and the mass content of the nickel element in the negative electrode material is B ppm, then A and B satisfy the following formula. 9.2 ≤ A / B ≤ 20

2. The negative electrode material according to claim 1, characterized in that the total mass content of the iron element and the nickel element in the negative electrode material is less than 1%.

3. The negative electrode material according to claim 2, characterized by having at least one of the following features. (1) If the mass content of the iron element in the negative electrode material is A ppm, then 0.1 ≤ A ≤ 1000 is satisfied; (2) If the mass content of the nickel element in the negative electrode material is B ppm, then the condition 0.1 ≤ B ≤ 500 is satisfied.

4. The negative electrode material according to claim 1, characterized in that it has an indentation hardness of 100 MPa or more.

5. The negative electrode material according to claim 1, characterized by having at least one of the following features. (1) The active material includes a silicon-based material; (2) The active material includes a silicon-based material, the silicon-based material includes at least one of crystalline silicon, amorphous silicon, silicon oxide, silicon alloy, and a composite of crystalline silicon and amorphous silicon.

6. The negative electrode material according to claim 1, characterized by having at least one of the following features. (1) The average particle diameter D of the primary particles 50 The range is 1 nm to 500 nm; (2) The particle size of the primary particle is (D 100 -D 10 ) / D 50 It satisfies ≥ 1.

5.

7. The active material includes a silicon-based material, The aforementioned silicon-based material is further doped with oxygen. The negative electrode material according to any one of claims 1 to 6, characterized in that the mass content of the oxygen element in the negative electrode material is 0.1% to 18%.

8. The negative electrode material according to any one of claims 1 to 6, further comprising a carbon material located on at least a portion of the surface of the secondary particles and / or the primary particles.

9. Specific surface area is 0.1 m² 2 / g to 5m 2 The negative electrode material according to any one of claims 1 to 6, characterized in that it is / g.

10. The negative electrode material according to any one of claims 1 to 6, characterized in that the median diameter is 0.5 μm to 30 μm.

11. A mixture containing a silicon source precursor, an iron dopant, and a nickel dopant is heat-treated to obtain primary particles doped with iron and nickel, and A method for producing a negative electrode material, comprising coating primary particles to obtain the negative electrode material, A method for manufacturing a negative electrode material, characterized in that, if the mass content of iron in the negative electrode material is A ppm and the mass content of nickel in the negative electrode material is B ppm, then A and B satisfy the following formula. 9.2 ≤ A / B ≤ 20

12. The iron dopant comprises at least one of iron powder, iron nitrate, nickel nitrate, ferrous lactate, iron citrate, yellow hemolybdenum, iron glycinate, and ferrocene, and / or The manufacturing method according to claim 11, characterized in that the nickel dopant comprises at least one of nickel oleate, nickel propionate, nickel butyrate, nickel octylate, nickel lactate, nickel benzoate, bis(acetylacetonate)nickel, nickel salicylate, and alkylphenylsalicylate.

13. The heat treatment of the mixture containing the silicon source precursor, iron dopant, and nickel dopant includes forming primary particles from the gas phase silicon source precursor by gas phase deposition, and doping the primary particles with metal vapor generated from the iron dopant and nickel dopant. The manufacturing method according to claim 11, characterized in that the mass ratio of the iron dopant to the nickel dopant is 0.1 to 30.

14. The heat treatment of the mixture containing the silicon source precursor, iron dopant, and nickel dopant includes adding a metal reducing agent to a mixture containing the liquid-phase silicon source precursor, iron dopant, and nickel dopant, separating the solid and liquid components, and then heat-treating the resulting mixture to obtain primary particles doped with nickel and iron. The manufacturing method according to claim 11, characterized in that the mass ratio of the liquid-phase silicon source precursor, iron dopant, nickel dopant, and metal reducing agent is (40-100):(0.01-1):(0.05-1):(0.01-5).

15. A battery characterized by comprising a negative electrode material according to any one of claims 1 to 11, or a negative electrode material manufactured by a method for manufacturing a negative electrode material according to any one of claims 12 to 14.

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