Negative electrode material, preparation method therefor, and use thereof

Abstract

A negative electrode material, a preparation method therefor, and a use thereof. The structure of the negative electrode material comprises a core and a shell; the core comprises the following components: porous carbon, a first solid electrolyte, and nano silicon particles; the first solid electrolyte is loaded on the surface of the porous carbon and the pore structure of the porous carbon; the nano silicon particles are deposited in the pore structure of the porous carbon; the outer surface of the core is coated with the shell; and the shell comprises the following component(s): a carbon material and / or a second solid electrolyte. In the negative electrode material, the first solid electrolyte in the core is loaded on the surface of the porous carbon, such that generation of electrochemically inactive silicon carbide due to direct contact between the nano silicon particles and the porous carbon is avoided, and the actual capacity of a lithium-ion battery can be increased; coating of the shell can improve the initial coulombic efficiency of the lithium-ion battery, and can also improve the rate capability and the fast charging performance; and the addition of the first solid electrolyte and the second solid electrolyte can improve the performance of the lithium-ion battery in an extreme environment.

Description

A negative electrode material and its preparation method and application

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on January 22, 2024, with application number 202410092993.3 and invention name “A negative electrode material, its preparation method and application”. Technical Field

[0002] The present invention relates to the field of lithium-ion battery materials, and in particular to a negative electrode material and a preparation method and application thereof. Background Art

[0003] Lithium-ion battery anode materials are an important component of lithium-ion batteries and are primarily responsible for storing and releasing lithium ions. Currently, lithium-ion battery anode materials primarily include carbon materials and lithium titanate materials. With the rapid development and continuous iteration of the entire industry, some new anode materials have gradually begun to occupy the market, such as silicon-based anode materials (silicon-oxygen anode and silicon-carbon anode, etc.) with high gram capacity and abundant reserves.

[0004] At present, silicon-carbon negative electrode materials mainly prepared by chemical vapor deposition have shown excellent performance, because vapor deposition reduces the size of nano-silicon particles, effectively slowing down a series of problems caused by the expansion of nano-silicon particles; in addition, vapor deposition ensures the uniform deposition of nano-silicon particles, inhibits the agglomeration of nano-silicon particles, and improves the cycle performance of lithium-ion batteries.

[0005] However, when preparing silicon-carbon negative electrode materials by chemical vapor deposition, nano-silicon particles are directly deposited in the pores of porous carbon. Due to the high activity of nano-silicon particles, it is easy to react with the carbon in the porous carbon to generate electrochemically inactive silicon carbide, thereby reducing the capacity of the silicon-carbon negative electrode material. In addition, the fast charging demand of batteries requires the development of silicon-carbon negative electrode materials with high rate performance, so the rapid transmission of electrons and ions in silicon-carbon negative electrode materials poses a more severe challenge. In addition, for the use of batteries in extreme environments, such as high / low temperature and high / low pressure, in order to ensure the normal charging and discharging of batteries, requirements are also put forward for the application of silicon-carbon negative electrode materials in extreme environments.

[0006] Therefore, how to solve the problem of generating inactive silicon carbide during the preparation process of silicon-carbon negative electrode materials and how to improve the fast charging of batteries and their performance in extreme environments have become one of the current research hotspots.

[0007] Summary of the Invention

[0008] The purpose of the present invention is to address the defects of the prior art and provide a negative electrode material, a preparation method and an application thereof, wherein the negative electrode material has a core-shell structure, the first solid electrolyte in the core can inhibit the formation of inactive electrochemically active silicon carbide, and the carbon material or the first solid electrolyte in the outer shell can improve the electronic conductivity and ionic conductivity of the negative electrode material.

[0009] To achieve the above objectives, in a first aspect, the present invention provides a negative electrode material, wherein the structure of the negative electrode material comprises a core and an outer shell;

[0010] The components of the core include porous carbon, a first solid electrolyte and nano-silicon particles; the first solid electrolyte is loaded on the surface of the porous carbon and in the pore structure of the porous carbon; the nano-silicon particles are deposited in the pore structure of the porous carbon;

[0011] The shell is coated on the outer surface of the core, and the shell comprises carbon material and / or a second solid electrolyte.

[0012] Preferably, the first solid electrolyte is an oxide solid electrolyte and / or a sulfide solid electrolyte.

[0013] Preferably, the second solid electrolyte is an oxide solid electrolyte and / or a sulfide solid electrolyte.

[0014] In a second aspect, the present invention provides a method for preparing the negative electrode material according to any one of the first aspects above, the preparation method comprising:

[0015] adding a first solid electrolyte raw material and a porous carbon raw material into a solvent and stirring to obtain a slurry;

[0016] heat-treating the slurry to obtain a porous carbon material loaded with a first solid electrolyte;

[0017] Under an inert atmosphere, vapor-depositing the porous carbon material and a silicon source gas to obtain a porous carbon composite material comprising porous carbon, a first solid electrolyte, and nano-silicon particles;

[0018] Under an inert atmosphere, the porous carbon composite material is coated to obtain a shell containing a carbon material and / or a second solid electrolyte, thereby obtaining a negative electrode material.

[0019] Preferably, the heat treatment is spray drying and high temperature calcination;

[0020] The spray drying conditions are: air inlet temperature is 150°C-400°C, and air outlet temperature is 80°C-200°C;

[0021] The high temperature calcination conditions are: temperature of 400° C.-800° C., and time of 1 hour-5 hours.

[0022] Preferably, the temperature of the vapor deposition is 400° C.-1000° C., and the time is 2 hours-15 hours.

[0023] Preferably, the coating treatment includes carbon coating and / or second solid electrolyte coating;

[0024] The carbon coating conditions are: temperature of 300°C-1000°C, time of 2 hours-20 hours;

[0025] The second solid electrolyte coating includes a spray drying stage and a high-temperature calcination stage;

[0026] The conditions of the spray drying stage are: the air inlet temperature is 150°C-400°C, and the air outlet temperature is 80°C-200°C;

[0027] The conditions of the high-temperature calcination stage are: temperature of 400° C.-800° C., and time of 1 hour-5 hours.

[0028] More preferably, the carbon source of the carbon coating is one or more of alkanes, alkenes, and alkynes.

[0029] In a third aspect, the present invention provides a negative electrode plate, comprising the negative electrode material described in any one of the first aspects or the negative electrode material prepared by the preparation method described in any one of the second aspects.

[0030] In a fourth aspect, the present invention provides a lithium-ion battery, comprising the negative electrode sheet described in the third aspect; the electrolyte of the lithium-ion battery is an aqueous electrolyte or an oil-based electrolyte.

[0031] An embodiment of the present invention provides a negative electrode material having a core-shell structure consisting of a core and an outer shell. The first solid electrolyte in the core is loaded on the surface of porous carbon, preventing direct contact between nano-silicon particles and the porous carbon to form electrochemically inactive silicon carbide, thereby increasing the actual capacity of the lithium-ion battery. The outer shell coating can reduce the specific surface area of ​​the negative electrode material, increase the initial coulombic efficiency of the lithium-ion battery, and also increase the ionic conductivity and ionic conductivity, thereby improving the rate performance of the lithium-ion battery and improving its fast charging performance. The addition of the first solid electrolyte and the second solid electrolyte is beneficial to improving the performance of the negative electrode material in extreme environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG1 is a flow chart of a method for preparing a negative electrode material provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions, and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings. It is apparent that the embodiments described are only some, not all, of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0034] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments.

[0035] An embodiment of the present invention provides a negative electrode material, wherein the structure of the negative electrode material includes a core and an outer shell.

[0036] The components of the core may specifically include porous carbon, a first solid electrolyte and nano-silicon particles. The first solid electrolyte is loaded on the surface of the porous carbon and in the pore structure of the porous carbon. The first solid electrolyte may specifically be an oxide solid electrolyte and / or a sulfide solid electrolyte. The oxide solid electrolyte may specifically include lithium aluminum titanium phosphate (LiA 1.4 Al 0.4 Ti 1.6 (PO4)3, referred to as LATP), lithium lanthanum titanium oxide (Li 0.33 La 0.56 TiO3, referred to as LLTO), lithium lanthanum zirconium oxide (Li7La3Zr20 12 , referred to as LLZO) and so on. Sulfide solid electrolytes can specifically include Li3PS4, Li 10 GeP2S 12 wait.

[0037] When this negative electrode material is used in a lithium-ion battery, the first solid electrolyte in the core can increase the interfacial transport rate of lithium ions during the electrochemical reaction and improve the performance of the negative electrode material in extreme environments. Furthermore, the first solid electrolyte is loaded on the surface of the porous carbon and within the pore structure of the porous carbon, preventing direct contact between the nano-silicon particles and the pore structure of the porous carbon. This can inhibit the formation of electrochemically inactive silicon carbide, thereby increasing the actual capacity of the lithium-ion battery.

[0038] The components of the shell may specifically include carbon material and / or a second solid electrolyte. The second solid electrolyte may specifically include an oxide solid electrolyte and / or a sulfide solid electrolyte. Among them, the oxide solid electrolyte may specifically include lithium aluminum titanium phosphate (Li 1.4 Al 0.4 Ti 1.6 (PO4)3, referred to as LATP), lithium lanthanum titanium oxide (Li 0.33 La 0.56TiO3, referred to as LLTO), lithium lanthanum zirconium oxide (Li7La3Zr20 12 , referred to as LLZO) and so on. Sulfide solid electrolytes can specifically include Li3PS4, Li 10 GeP2S 12 The outer shell can have a thickness of 2 nm to 50 nm. The outer shell coats the outer surface of the inner core, forming a core-shell structure for the negative electrode material. The carbon material in the outer shell improves the electronic conductivity of the negative electrode material, while the second solid electrolyte improves the ionic conductivity of the negative electrode material. Furthermore, the outer shell coating reduces the specific surface area of ​​the negative electrode material, thereby improving the initial coulombic efficiency of the lithium-ion battery.

[0039] In summary, an embodiment of the present invention provides a negative electrode material having a core-shell structure consisting of a core and an outer shell. The first solid electrolyte in the core is loaded on the surface of the porous carbon, avoiding direct contact between the nano-silicon particles and the porous carbon to generate electrochemically inactive silicon carbide, thereby increasing the actual capacity of the lithium-ion battery. The outer shell coating can reduce the specific surface area of ​​the negative electrode material, increase the initial coulombic efficiency of the lithium-ion battery, and also increase the ionic conductivity and ionic conductivity, thereby improving the rate performance of the lithium-ion battery and improving its fast charging performance. The addition of the first solid electrolyte and the second solid electrolyte is beneficial to improving the performance of the negative electrode material in extreme environments.

[0040] The present invention also provides a method for preparing the negative electrode material described above, the process of which is shown in FIG1 and includes the following steps:

[0041] Step 110, adding a first solid electrolyte raw material and a porous carbon raw material into a solvent and stirring to obtain a slurry;

[0042] Specifically, the first solid electrolyte raw material can be added to the solvent and stirred for a certain period of time so that the first solid electrolyte raw material is completely dissolved in the solvent, and then the porous carbon raw material is added and stirred for a period of time so that the first solid electrolyte raw material and the porous carbon raw material are evenly mixed. The first solid electrolyte raw material can specifically include oxide solid electrolyte raw materials and sulfide solid electrolyte raw materials. For example, a single substance or compound containing elements such as lithium, lanthanum, aluminum, titanium, zirconium, phosphorus, oxygen, sulfur, and germanium. The porous carbon raw material can specifically include activated carbon, carbon molecular sieve, activated carbon fiber, etc. The solvent can be deionized water or ethanol. The mass fraction of ethanol can be 50%-75%.

[0043] Step 120, heat-treating the slurry to obtain a porous carbon material loaded with a first solid electrolyte;

[0044] Specifically, the heat treatment includes two stages: spray drying and high-temperature calcination. Spray drying can make the porous carbon material have uniform particle size and small particle size. High-temperature calcination can further remove residual solvent and other substances from the spray-dried particles, improving purity and dryness, making the particles more uniform and refined, and further improving the material's heat resistance.

[0045] The spray drying conditions are as follows: air inlet temperature 150°C-400°C, preferably 200°C-300°C, air outlet temperature 80°C-200°C, preferably 100°C-160°C.

[0046] High-temperature calcination can be performed in a high-temperature furnace. The inert atmosphere for high-temperature calcination can be one or more of nitrogen, argon, and helium. The gas flow rate is 3 L / min-10 L / min, preferably 5 L / min-8 L / min. The heating rate of the high-temperature furnace is 2°C / min-8°C / min, preferably 4°C / min-6°C / min. The high-temperature calcination conditions are as follows: temperature 400°C-800°C, preferably 500°C-700°C, and time 1 hour-5 hours, preferably 2.5 hours-3.5 hours.

[0047] The process mainly involves loading the first solid electrolyte onto the surface of the porous carbon raw material and into the pore structure of the porous carbon raw material.

[0048] Step 130 , vapor-depositing the porous carbon material and the silicon source gas under an inert atmosphere to obtain a porous carbon composite material including porous carbon, a first solid electrolyte, and nano-silicon particles;

[0049] Specifically, the inert atmosphere can be one or more of nitrogen, argon, and helium. Vapor deposition can be performed in a deposition furnace. First, an inert gas is introduced into the deposition furnace at a predetermined flow rate to form an inert atmosphere. The inert atmosphere can be one or more of nitrogen, argon, and helium, and the flow rate can be 15 L / min. Then, the deposition furnace is heated to 400°C-1000°C, preferably 600°C-800°C, at a heating rate of 2°C / min-8°C / min, preferably 4°C / min-6°C / min. The temperature is maintained at this temperature for 30-40 minutes to stabilize the deposition furnace temperature. Finally, a silicon source gas and an inert gas are introduced into the deposition furnace at a predetermined ratio and maintained at this temperature for 2-15 hours, preferably 5-10 hours, to perform vapor deposition. The predetermined ratio can be 1:5-4:5, preferably 1:2. The silicon source gas can include, but is not limited to, monosilane, disilane, and other silane-containing hydrocarbons. In this way, a porous carbon composite material is obtained as the core of the negative electrode material. Since the first solid electrolyte is loaded on the surface and pore structure of the porous carbon, it cuts off the direct contact between the nano-silicon particles and the porous carbon, greatly reducing the probability of silicon carbide formation. When applied to lithium-ion batteries, the actual capacity of the lithium-ion battery can be increased.

[0050] Step 140, coating the porous carbon composite material under an inert atmosphere to obtain a shell containing a carbon material and / or a second solid electrolyte, thereby obtaining a negative electrode material;

[0051] Specifically, the coating treatment is mainly to form the outer shell of the negative electrode material, which specifically includes carbon coating and / or second solid electrolyte coating. The carbon source of the carbon coating is one or more of alkanes, alkenes, and alkynes. The carbon coating treatment can be carried out in a coating furnace, and the ratio of inert gas to carbon source can be 1:3-4:5, preferably 3:5. The coating temperature can be 300°C-1000°C, preferably 500°C-800°C, and the time is 2 hours-20 hours, preferably 8 hours-16 hours. The coating thickness can be 2nm-50nm.

[0052] The second solid electrolyte coating is divided into two stages: spray drying stage and high temperature calcination stage;

[0053] The conditions of the spray drying stage are: the air inlet temperature is 150℃-400℃, the air outlet temperature is 80℃-200℃. The conditions of the high temperature calcination stage are: the temperature is 400℃-800℃, the time is 1 hour-5 hours.

[0054] It should be noted that there is no specific order for applying both carbon coating and a second solid electrolyte coating simultaneously. Coating creates a shell for the negative electrode material, improving its electronic and ionic conductivity, which is beneficial for enhancing the rate capability and fast-charging performance of lithium-ion batteries. Coating also reduces the material's specific surface area to a certain extent, which helps improve the initial coulombic efficiency of lithium-ion batteries.

[0055] An embodiment of the present invention provides a method for preparing a negative electrode material. First, a first solid electrolyte is loaded on the surface of a porous carbon raw material by heat treatment. When silicon particles are deposited in the pore structure of the porous carbon raw material, the first solid electrolyte can avoid direct contact between nano-silicon particles and the porous carbon raw material, inhibiting the formation of electrochemically inactive silicon carbide and increasing the actual capacity of the lithium-ion battery. Through coating treatment, the electronic conductivity and ionic conductivity of the negative electrode material are further improved, thereby improving its rate performance and fast charging performance, while reducing the specific surface area of ​​the material and increasing the first coulombic efficiency of the lithium-ion battery. The addition of the first solid electrolyte and the second solid electrolyte is beneficial to improving the performance of lithium-ion batteries in extreme environments.

[0056] The negative electrode material provided by the present invention can be applied to the electrode material of lithium ion batteries.

[0057] To better understand the technical solution provided by the present invention, the following uses multiple specific examples to illustrate the specific process of preparing the negative electrode material using the method provided by the above embodiment of the present invention, as well as the electrochemical properties of the prepared negative electrode material.

[0058] Example 1

[0059] In the first step, 18.13 g of lithium acetate, 20.09 g of aluminum nitrate nonahydrate, 69.02 g of ammonium dihydrogen phosphate and 120.44 g of tetrabutyl titanate were weighed as the first solid electrolyte raw material, added to 45 kg of deionized water and stirred for 1.5 hours, and then 7.5 kg of porous carbon raw material was added and stirred for 3 hours to obtain a slurry.

[0060] In the second step, the slurry was spray-dried at an air inlet temperature of 200°C and an air outlet temperature of 120°C to obtain spray particles. The spray particles were then placed in a high-temperature furnace at a nitrogen flow rate of 3 L / min. The temperature was then increased to 550°C at a heating rate of 3°C / min and maintained at this temperature for 2.5 hours to obtain a porous carbon material loaded with LATP. The mass ratio of LATP to the porous carbon raw material was 1%.

[0061] In the third step, 2.5 kg of porous carbon material was placed in a deposition furnace, nitrogen was introduced into the deposition furnace at a gas flow rate of 15 L / min for protection, and the deposition furnace was heated to 600 ° C at a heating rate of 2 ° C / min, and kept warm for 35 minutes. Then, a mixed gas of monosilane and nitrogen was introduced at a ratio of 10 L / min:50 L / min, and the heat was continued for 5.5 hours to allow the porous carbon material and monosilane to be vapor-deposited to obtain a porous carbon composite material including porous carbon, LATP and nano-silicon particles.

[0062] The fourth step is to place the porous carbon composite material in a coating furnace under a nitrogen atmosphere, and then introduce a mixed gas of nitrogen and methane into the coating furnace at a ratio of 15L / min:25L / min, and heat the coating furnace to 650°C. Keep it at this temperature for 7.5 hours to form a carbon layer shell, thereby obtaining a negative electrode material with a carbon layer shell and an inner core.

[0063] Afterwards, the prepared negative electrode material was used to prepare a pole piece of a lithium-ion battery, and the pole piece was used to assemble a button-type half-cell for testing, as follows:

[0064] First, the negative electrode material, conductive agent Super P, and binder sodium carboxymethyl cellulose were ground in a mortar at a mass ratio of 8:1:1. The mixture was then added to deionized water and blended in a blender to form a slurry, which was then coated onto a copper foil current collector. The mixture was then dried in a vacuum oven at 80°C for 12 hours. The dried electrode was then cut into 14mm diameter discs to serve as the electrode sheets for button-type half-cells.

[0065] Next, the electrodes were assembled into a button-type half-cell in an argon-filled glove box. The aqueous electrolyte in the button-type half-cell was 1 mol / L lithium hexafluorophosphate (LiPF6). The solvents were ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC), with a volume ratio of 1:1:1 between EC, DMC, and DEC. The counter electrode was a lithium sheet.

[0066] Finally, the electrochemical performance was evaluated on a BlueDian battery testing system under a voltage window of 0.01V-2V.

[0067] Example 2

[0068] In the first step, 36.27 g of lithium acetate, 39.43 g of aluminum nitrate nonahydrate, 135.47 g of ammonium dihydrogen phosphate and 236.40 g of tetrabutyl titanate were weighed as the first solid electrolyte raw material, added to 45 kg of deionized water and stirred for 1.5 hours, and then 7.5 kg of porous carbon raw material was added and stirred for 3 hours to obtain a slurry.

[0069] In the second step, the slurry was spray-dried at an air inlet temperature of 200°C and an air outlet temperature of 120°C to obtain spray particles. The spray particles were then placed in a high-temperature furnace at a nitrogen flow rate of 3 L / min. The temperature was then increased to 550°C at a heating rate of 3°C / min and maintained at this temperature for 2.5 hours to obtain a porous carbon material loaded with LATP. The mass ratio of LATP to the porous carbon raw material was 2%.

[0070] In the third step, 2.5 kg of porous carbon material was placed in a deposition furnace, nitrogen was introduced into the deposition furnace at a gas flow rate of 15 L / min for protection, and the deposition furnace was heated to 600 ° C at a heating rate of 2 ° C / min, and kept warm for 35 minutes. Then, a mixed gas of monosilane and nitrogen was introduced at a ratio of 10 L / min:50 L / min, and the heat was continued for 5.5 hours to allow the porous carbon material and monosilane to be vapor-deposited to obtain a porous carbon composite material including porous carbon, LATP and nano-silicon particles.

[0071] The fourth step is to place the porous carbon composite material in a coating furnace under a nitrogen atmosphere, and then introduce a mixed gas of nitrogen and methane into the coating furnace at a ratio of 15L / min:25L / min, and heat the coating furnace to 650°C. Keep it at this temperature for 7.5 hours to form a carbon layer shell, thereby obtaining a negative electrode material with a carbon layer shell and an inner core.

[0072] Afterwards, the assembly and testing of the button half-cell were the same as in Example 1.

[0073] Example 3

[0074] In the first step, 90.67 g of lithium acetate, 98.58 g of aluminum nitrate nonahydrate, 338.69 g of ammonium dihydrogen phosphate and 591 g of tetrabutyl titanate were weighed as the first solid electrolyte raw material, added to 45 kg of deionized water and stirred for 1.5 hours, and then 7.5 kg of porous carbon raw material was added and stirred for 3 hours to obtain a slurry.

[0075] In the second step, the slurry was spray-dried at an air inlet temperature of 200°C and an air outlet temperature of 120°C to obtain spray particles. The spray particles were then placed in a high-temperature furnace at a nitrogen flow rate of 3 L / min. The furnace was then heated to 550°C at a heating rate of 3°C / min and held at this temperature for 2.5 hours to obtain a porous carbon material loaded with LATP. The mass ratio of LATP to the porous carbon raw material was 5%.

[0076] In the third step, 2.5 kg of porous carbon material was placed in a deposition furnace, nitrogen was introduced into the deposition furnace at a gas flow rate of 15 L / min for protection, and the deposition furnace was heated to 600 ° C at a heating rate of 2 ° C / min, and kept warm for 35 minutes. Then, a mixed gas of monosilane and nitrogen was introduced at a ratio of 10 L / min:50 L / min, and the heat was continued for 5.5 hours to allow the porous carbon material and monosilane to be vapor-deposited to obtain a porous carbon composite material including porous carbon, LATP and nano-silicon particles.

[0077] The fourth step is to place the porous carbon composite material in a coating furnace under a nitrogen atmosphere, and then introduce a mixed gas of nitrogen and methane into the coating furnace at a ratio of 15L / min:25L / min, and heat the coating furnace to 650°C. Keep it at this temperature for 7.5 hours to form a carbon layer shell, thereby obtaining a negative electrode material with a carbon layer shell and an inner core.

[0078] Afterwards, the assembly and testing of the button half-cell were the same as in Example 1.

[0079] Comparative Example 1

[0080] In the first step, 2.5 kg of porous carbon raw material is placed in a deposition furnace, nitrogen is introduced into the deposition furnace at a gas flow rate of 15 L / min for protection, and the deposition furnace is heated to 600°C at a heating rate of 2°C / min, and kept warm for 35 minutes. Then, a mixed gas of monosilane and nitrogen is introduced at a ratio of 10 L / min:50 L / min, and the heat is continued for 5.5 hours to allow the porous carbon raw material and monosilane to be vapor-deposited to obtain a porous carbon composite material including porous carbon and nano-silicon particles.

[0081] The fourth step is to place the porous carbon composite material in a coating furnace under a nitrogen atmosphere, and then introduce a mixed gas of nitrogen and methane into the coating furnace at a ratio of 15L / min:25L / min, and heat the coating furnace to 650°C. Keep it at this temperature for 7.5 hours to form a carbon layer shell, thereby obtaining a negative electrode material with a carbon layer shell and an inner core.

[0082] Afterwards, the assembly and testing of the button half-cell were the same as in Example 1.

[0083] Comparative Example 2

[0084] In the first step, 2.5 kg of porous carbon raw material is placed in a deposition furnace, nitrogen is introduced into the deposition furnace at a gas flow rate of 15 L / min for protection, and the deposition furnace is heated to 600°C at a heating rate of 2°C / min, and kept warm for 35 minutes. Then, a mixed gas of disilane and nitrogen is introduced at a ratio of 10 L / min:50 L / min, and the heat is continued for 5.5 hours, so that the porous carbon raw material and monosilane are vapor-deposited to obtain a porous carbon composite material including porous carbon and nano-silicon particles.

[0085] The fourth step is to place the porous carbon composite material in a coating furnace under a nitrogen atmosphere, and then introduce a mixed gas of nitrogen and methane into the coating furnace at a ratio of 15L / min:25L / min, and heat the coating furnace to 650°C. Keep it at this temperature for 7.5 hours to form a carbon layer shell, thereby obtaining a negative electrode material with a carbon layer shell and an inner core.

[0086] Afterwards, the assembly and testing of the button half-cell were the same as in Example 1.

[0087] Table 1 shows the rate performance test data of the button-type half-cells prepared in Examples 1-3 and Comparative Examples 1-2.

[0088] Table 1

[0089] As can be seen from Table 1, compared with Comparative Examples 1 and 2, the button-type half-cell of the embodiment of the present invention exhibits excellent rate performance. This is because the core of the negative electrode material of the present application is loaded with LATP, which can effectively inhibit the formation of silicon carbide, improve the interface transmission rate of the battery during the electrochemical reaction process, and avoid the loss of gram capacity of the battery during the charge and discharge process.

[0090] Table 2 shows the comparative data of the capacity retention of button-type half-cells prepared in Examples 1-3 and Comparative Examples 1-2 after 100 cycles at a current density of 0.1C and a temperature of 80°C.

[0091] Table 2

[0092] As can be seen from Table 2, compared with Comparative Examples 1 and 2, the cycle retention rate of the button half-cell of the embodiment of the present invention under the test conditions is maintained at more than 80%. This is because the core of the negative electrode material of the present application is loaded with LATP, which can improve the cycle stability of the lithium-ion battery under high temperature conditions.

[0093] Example 4

[0094] In the first step, 68.96 g of lithium nitrate, 232.68 g of lanthanum nitrate and 481.28 g of tetrabutyl titanate were weighed as the first solid electrolyte raw material, added to 50 kg of ethanol and stirred for 2 hours, and then 7.5 kg of porous carbon raw material was added and stirred for 4 hours to obtain a slurry.

[0095] In the second step, the slurry was spray-dried at an air inlet temperature of 150°C and an air outlet temperature of 100°C to obtain spray particles. The spray particles were then placed in a high-temperature furnace at an argon flow rate of 10 L / min. The temperature was then increased to 400°C at a heating rate of 2°C / min and maintained at this temperature for 5 hours to obtain a porous carbon material loaded with LLTO. The mass ratio of LLTO to the porous carbon raw material was 3%.

[0096] In the third step, 2.5 kg of porous carbon material was placed in a deposition furnace, helium was introduced into the deposition furnace at a gas flow rate of 15 L / min for protection, and the deposition furnace was heated to 400°C at a heating rate of 8°C / min and kept warm for 40 minutes. Then, a mixed gas of disilane and helium was introduced at a ratio of 40 L / min:50 L / min, and the temperature was kept warm for 2 hours to allow the porous carbon material and disilane to be vapor-deposited to obtain a porous carbon composite material including porous carbon, LLTO and nano-silicon particles.

[0097] In the fourth step, the porous carbon composite material and LLTO slurry are mixed and spray-dried with an air inlet temperature of 150°C and an air outlet temperature of 100°C to obtain spray particles. Then, the spray particles are placed in a high-temperature furnace at an argon flow rate of 10 L / min, and the high-temperature furnace is heated to 400°C at a heating rate of 2°C / min and kept warm for 5 hours to form an LLTO layer shell, thereby obtaining a negative electrode material having an LLTO layer shell and a core.

[0098] Afterwards, the prepared negative electrode material was used to prepare a pole piece of a lithium-ion battery, and the pole piece was used to assemble a button-type half-cell for testing, as follows:

[0099] First, the negative electrode material, conductive agent Super P, and binder sodium carboxymethyl cellulose were ground in a mortar at a mass ratio of 8:1:1. The mixture was then added to deionized water and blended in a blender to form a slurry, which was then coated onto a copper foil current collector. The mixture was then dried in a vacuum oven at 80°C for 12 hours. The dried electrode was then cut into 14mm diameter discs to serve as the electrode sheets for button-type half-cells.

[0100] Next, the electrodes were assembled into a button-type half-cell in an argon-filled glove box. The oil-based electrolyte in the button-type half-cell contained N-methylpyrrolidone (NMP) as the solvent. The counter electrode was a lithium sheet.

[0101] Finally, the electrochemical performance was evaluated on a BlueDian battery testing system under a voltage window of 0.01V-2V.

[0102] Example 5

[0103] In the first step, 59.89 g of lithium hydroxide, 349.19 g of lanthanum oxide and 88.04 g of zirconium oxide were weighed as the first solid electrolyte raw material, added to 45 kg of deionized water and stirred for 2 hours, and then 7.5 kg of porous carbon raw material was added and stirred for 5 hours to obtain a slurry.

[0104] In the second step, the slurry was spray-dried at an air inlet temperature of 400°C and an air outlet temperature of 160°C to obtain spray particles. The spray particles were then placed in a high-temperature furnace at an argon flow rate of 5 L / min. The temperature was then increased to 800°C at a heating rate of 8°C / min and maintained for 1 hour to obtain a porous carbon material loaded with LLZO. The mass ratio of LLZO to the porous carbon raw material was 4%.

[0105] In the third step, 2.5 kg of porous carbon material was placed in a deposition furnace, argon was introduced into the deposition furnace at a gas flow rate of 15 L / min for protection, and the deposition furnace was heated to 1000°C at a heating rate of 4°C / min, and kept warm for 30 minutes. Then, a mixed gas of monosilane and argon was introduced at a ratio of 10 L / min:20 L / min, and the temperature was kept warm for 5 hours, so that the porous carbon material and monosilane were vapor-deposited to obtain a porous carbon composite material including porous carbon, LLZO and nano-silicon particles.

[0106] The fourth step is to place the porous carbon composite material in a coating furnace under a nitrogen atmosphere, and then introduce a mixed gas of nitrogen and ethylene into the coating furnace at a ratio of 40L / min:50L / min, and heat the coating furnace to 1000°C. Keep it at this temperature for 2 hours to form a carbon layer shell, thereby obtaining a negative electrode material with a carbon layer shell and an inner core.

[0107] Example 6

[0108] In the first step, 318.30 g of lithium chloride, 77.52 g of phosphorus and 321.07 g of sulfur were weighed as the first solid electrolyte raw material, added to 50 kg of ethanol and stirred for 1.5 hours, and then 7.5 kg of porous carbon raw material was added and stirred for 3.5 hours to obtain a slurry.

[0109] In the second step, the slurry was spray-dried at an air inlet temperature of 300°C and an air outlet temperature of 80°C to obtain spray particles. The spray particles were then placed in a high-temperature furnace at a helium flow rate of 8 L / min. The temperature of the high-temperature furnace was then increased to 500°C at a heating rate of 4°C / min and maintained at this temperature for 3.5 hours to obtain a porous carbon material loaded with Li3PS4. The mass ratio of Li3PS4 to the porous carbon raw material was 6%.

[0110] In the third step, 2.5 kg of porous carbon material was placed in a deposition furnace, argon was introduced into the deposition furnace at a gas flow rate of 15 L / min for protection, and the deposition furnace was heated to 800 ° C at a heating rate of 6 ° C / min, and kept warm for 32 minutes. Then, a mixed gas of disilane and argon was introduced at a ratio of 20 L / min:30 L / min, and the heat was continued for 15 hours to allow the porous carbon material and disilane to be vapor-deposited to obtain a porous carbon composite material including porous carbon, Li3PS4 and nano-silicon particles.

[0111] The fourth step is to place the porous carbon composite material in a coating furnace under an argon atmosphere, and then introduce a mixed gas of argon and propyne into the coating furnace at a ratio of 10L / min:30L / min, and heat the coating furnace to 500°C. Keep it at this temperature for 16 hours to form a carbon layer shell, thereby obtaining a negative electrode material with a carbon layer shell and an inner core.

[0112] Example 7

[0113] In the first step, 234.45 g of lithium sulfide, 226.81 g of phosphorus pentasulfide and 139.57 g of germanium disulfide were weighed as the first solid electrolyte raw material, added to 45 kg of ethanol and stirred for 2 hours, and then 7.5 kg of porous carbon raw material was added and stirred for 4 hours to obtain a slurry.

[0114] In the second step, the slurry was spray-dried at an air inlet temperature of 260°C and an air outlet temperature of 200°C to obtain spray particles. Then, the spray particles were placed in a high-temperature furnace at a helium flow rate of 7 L / min, and then the high-temperature furnace was heated to 700°C at a heating rate of 6°C / min and kept warm for 3 hours to obtain Li-loaded 10 GeP2S 12 Porous carbon materials. 10 GeP2S 12 The mass ratio of the porous carbon raw material is 8%.

[0115] In the third step, 2.5 kg of porous carbon material was placed in a deposition furnace, argon was introduced into the deposition furnace at a gas flow rate of 15 L / min for protection, and the deposition furnace was heated to 700 ° C at a heating rate of 5 ° C / min, and kept warm for 38 minutes. Then, a mixed gas of disilane and argon was introduced at a ratio of 10 L / min: 25 L / min, and the temperature was kept warm for 10 hours, so that the porous carbon material and disilane were vapor-deposited to obtain porous carbon, Li 10 GeP2S 12 and porous carbon composites of nano-silicon particles.

[0116] The fourth step is to place the porous carbon composite material in a coating furnace under a nitrogen atmosphere, and then introduce a mixed gas of nitrogen and butene into the coating furnace at a ratio of 10L / min:20L / min, and heat the coating furnace to 800°C and keep it at this temperature for 8 hours to form a carbon layer shell; then, the porous carbon composite material with a carbon layer shell and Li 10 GeP2S 12 The slurry mixture was spray-dried with an air inlet temperature of 400°C and an air outlet temperature of 200°C to obtain spray particles. Then, the spray particles were placed in a high-temperature furnace at a helium flow rate of 7 L / min, and then the high-temperature furnace was heated to 400°C at a heating rate of 6°C / min and kept at this temperature for 5 hours to form Li 10 GeP2S 12 layer shell, thereby obtaining a carbon layer, Li 10 GeP2S 12 The negative electrode material of the outer shell and the inner core.

[0117] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A negative electrode material, characterized in that, The structure of the negative electrode material includes a core and a shell; The composition of the core includes porous carbon, a first solid electrolyte, and nano-silicon particles; the first solid electrolyte is loaded on the surface of the porous carbon and in the pore structure of the porous carbon; the nano-silicon particles are deposited in the pore structure of the porous carbon; The shell covers the outer surface of the core, and the composition of the shell includes a carbon material and / or a second solid electrolyte.

2. The negative electrode material according to claim 1, wherein The first solid electrolyte is an oxide solid electrolyte and / or a sulfide solid electrolyte.

3. The negative electrode material according to claim 1, wherein The second solid electrolyte is an oxide solid electrolyte and / or a sulfide solid electrolyte.

4. A method for preparing the negative electrode material according to any one of claims 1-3 above, characterized in that, The preparation method includes: Adding a first solid electrolyte raw material and a porous carbon raw material into a solvent and stirring to obtain a slurry; Performing heat treatment on the slurry to obtain a porous carbon material loaded with the first solid electrolyte; Under an inert atmosphere, performing chemical vapor deposition on the porous carbon material and a silicon source gas to obtain a porous carbon composite material including porous carbon, a first solid electrolyte, and nano-silicon particles; Under an inert atmosphere, performing a coating treatment on the porous carbon composite material to obtain a shell containing a carbon material and / or a second solid electrolyte, thereby obtaining the negative electrode material.

5. The preparation method according to claim 4, wherein, The heat treatment is spray drying and high-temperature calcination; The conditions of the spray drying: the inlet air temperature is 150°C - 400°C, and the outlet air temperature is 80°C - 200°C; The conditions of the high-temperature calcination: the temperature is 400°C - 800°C, and the time is 1 hour - 5 hours.

6. The preparation method according to claim 4, characterized in that The temperature of the chemical vapor deposition is 400°C - 1000°C, and the time is 2 hours - 15 hours.

7. The preparation method according to claim 4, wherein The coating treatment includes carbon coating and / or second solid electrolyte coating; The conditions of the carbon coating are: the temperature is 300°C - 1000°C, and the time is 2 hours - 20 hours; The second solid electrolyte coating includes a spray drying stage and a high-temperature calcination stage; The conditions of the spray drying stage: the inlet air temperature is 150°C - 400°C, and the outlet air temperature is 80°C - 200°C; The conditions of the high-temperature calcination stage: the temperature is 400°C - 800°C, and the time is 1 hour - 5 hours.

8. The preparation method according to claim 7, characterized in that, The carbon source for the carbon coating is one or more of alkanes, alkenes, and alkynes.

9. A negative electrode plate, characterized in that, The negative electrode sheet includes the negative electrode material according to any one of claims 1 - 3 or the negative electrode material prepared by the preparation method according to any one of claims 4 - 8.

10. A lithium-ion battery, characterized in that, The lithium-ion battery includes the negative electrode sheet according to claim 9; the electrolyte of the lithium-ion battery is an aqueous electrolyte or an oil-based electrolyte.

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