Preparation method of high-energy-density super-long-life fast-charging negative electrode material and lithium battery

Abstract

The invention relates to the technical field of lithium battery negative electrodes, and discloses a preparation method of a high-energy-density super-long-life fast-charging negative electrode material and a lithium battery, the preparation method of the negative electrode material comprises the following steps: preheating graphite under the protection of inert gas, then introducing carbon source gas and oxygen-containing gas, carrying out deposition reaction at 350-450 DEG C under normal pressure for 0.5-4 hours, and carrying out vacuum drying to obtain the high-energy-density super-long-life fast-charging negative electrode material. The functional carbon coating layer is formed on the surface of the negative electrode material. By adopting a low-temperature vapor deposition carbon coating technology, an amorphous disordered layer structure carbon layer is constructed on an artificial graphite substrate, an oxygen-containing functional group is introduced at the same time, the functionalized carbon coating layer provides a three-dimensional ion transmission channel, the interface impedance is remarkably reduced, the wettability of an electrolyte is improved, and the service life of the electrolyte is prolonged. And the problems of quick charging, low-temperature performance and cycle life can be synchronously solved.

Description

Preparation method of high energy density ultra-long life fast-charging anode material and lithium battery Technical Field

[0001] This invention relates to the technical field of lithium battery anodes, and in particular to a method for preparing high-energy-density, ultra-long-life, fast-charging anode materials and lithium batteries. Background Technology

[0002] Lithium-ion batteries have been widely used in consumer electronics, electric vehicles, and large-scale energy storage due to their high energy density and long cycle life. However, the performance of traditional lithium-ion batteries deteriorates sharply when faced with fast charging and low-temperature applications, which has become a key bottleneck restricting their further development.

[0003] Currently, commercial lithium-ion batteries mostly use artificial graphite as the anode material. To improve its initial efficiency and cycle performance, high-temperature vapor deposition (typically ≥800℃) is commonly used to carbon-coat it. For example, invention patent CN117276513A discloses a composite anode material for lithium-ion batteries, its preparation method, and a lithium-ion battery. The third precursor Si-xSiO2@EG is subjected to chemical vapor deposition in an ethylene atmosphere at a temperature of 600~1000℃ for 1~12 hours to achieve carbon coating, thus obtaining the composite anode material for lithium-ion batteries.

[0004] Although this technology can form a dense graphitized carbon layer on the graphite surface, it has the following inherent defects: (1) Poor ion transport performance: The carbon layer formed at high temperature is highly graphitized, with a regular crystal structure, a single lithium ion transport path, and a large interface impedance, which seriously limits the fast charging capability of the battery; (2) Surface chemical inertness: The surface energy of the graphitized carbon layer at high temperature is low, and there are few oxygen-containing functional groups, resulting in poor wettability of the electrolyte. In particular, the viscosity of the electrolyte increases at low temperatures, which leads to a further decrease in ionic conductivity; (3) High energy consumption and strong destructiveness of the process: The high-temperature process consumes a lot of energy, which increases the production cost. At the same time, the excessively high temperature may damage the crystal structure of the artificial graphite itself, which will have a negative impact on its performance. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for preparing high-energy-density, ultra-long-life, fast-charging anode materials and a lithium battery. By employing low-temperature (350-450℃) vapor deposition carbon coating technology, an amorphous disordered carbon layer is constructed on an artificial graphite substrate, while simultaneously introducing oxygen-containing functional groups (-COOH / -OH). This functionalized carbon coating layer provides three-dimensional ion transport channels, significantly reduces interfacial impedance, and improves electrolyte wettability, thereby enabling the production of a battery that combines fast charging, high energy density, and ultra-long cycle life.

[0006] The objective of this invention is achieved through the following technical solution: In a first aspect, this invention provides a method for preparing a high-energy-density, ultra-long-life, fast-charging anode material, comprising the following steps: preheating graphite under inert gas protection, then introducing a carbon source gas and an oxygen-containing gas, and carrying out a deposition reaction at 350-450℃ and normal pressure for 0.5-4h to obtain an anode material with a functionalized carbon coating layer on its surface, wherein the structure of the functionalized carbon coating layer is an amorphous disordered layer structure and contains oxygen-containing functional groups.

[0007] Conventional high-temperature vapor deposition (typically ≥800℃) for carbon coating results in complete carbon source decomposition, producing a highly graphitized, layered, dense structure with a regular, defect-free lattice and no obvious micropores or defects. This prevents the formation of three-dimensional ion transport channels, thus limiting the diversity of ion transport pathways. In contrast, this invention employs low-temperature vapor deposition (350-450℃) and the introduction of oxygen-containing gas. Under these low-temperature conditions, the carbon source gas undergoes only incomplete decomposition, generating carbon reactive species (such as carbon free radicals) with low energy. Graphitization is a process of carbon atoms transforming from a disordered to an ordered lattice, requiring the overcoming of a high energy barrier. 350-450℃ is far below the critical temperature required for graphitization; carbon atoms lack sufficient energy to form a regular six-membered ring layered structure and can only accumulate in disordered or amorphous forms. Moreover, the oxygen-containing substances introduced into the reaction system react with carbon active species to generate oxygen-containing functional groups (-COOH and -OH functional groups). These groups will embed into the carbon layer, disrupt the orderly stacking of carbon atoms, further inhibit graphitization, and at the same time, micropores and defects are easily formed during the carbon layer growth process, eventually forming an amorphous disordered layer structure.

[0008] The amorphous / randomized layered structure determines the multidimensionality of the ion transport pathway. The amorphous carbon layer contains numerous disordered carbon chains, micropores, and grain boundary defects. These structures form interconnected channels, allowing lithium ions to migrate in multiple directions (lateral and longitudinal), thus achieving three-dimensional transport. Simultaneously, oxygen-containing functional groups enhance the wettability of the electrolyte with the carbon layer, making it easier for the electrolyte to fill the micropores and defects, further widening the ion transport pathway and reducing transport resistance.

[0009] However, if the vapor deposition temperature exceeds 450℃, the increased temperature leads to increased carbon atom energy, causing them to align in an ordered manner. This disrupts the amorphous / random layer structure, resulting in a denser carbon layer. Existing micropores and defects are filled, forming localized graphitized regions. This reduces the number of three-dimensional transport channels, simplifies the lithium-ion transport path, and decreases fast-charging capability. Simultaneously, the high temperature causes the decomposition and release of -COOH and -OH groups, worsening electrolyte wettability and deteriorating low-temperature performance. If the vapor deposition temperature is below 350℃, the low temperature prevents effective carbon source decomposition, resulting in insufficient carbon active species formation, inadequate carbon layer deposition, and failure to form effective coating. This leads to increased interfacial impedance and poor fast-charging and low-temperature performance. Furthermore, an incomplete carbon layer cannot prevent direct contact between the electrolyte and graphite, easily triggering side reactions (such as SEI film instability) and reducing cycle life.

[0010] Preferably, the preheating temperature is 350-450℃.

[0011] Preferably, the median D50 particle size of the graphite is 8-12 μm.

[0012] Preferably, the deposition reaction temperature is 400-450°C.

[0013] Preferably, the carbon source gas includes C2H2 and / or CH4.

[0014] Preferably, the oxygen-containing gas includes CO2 and / or water vapor.

[0015] CO2 can act as a weak oxidant, undergoing redox reactions with carbon source gases. The energy released can lower the activation energy of ethylene cracking and promote the breaking of CC and CH bonds. Water vapor can also react with carbon source gases, assisting in the cracking of carbon sources.

[0016] Preferably, the flow rate ratio of the carbon source gas to the oxygen-containing gas is 5-15:1; more preferably, the flow rate ratio of the carbon source gas to the oxygen-containing gas is 10-15:1.

[0017] When the ratio of carbon source to oxygen-containing gas is appropriate, the carbon source undergoes sufficient pyrolysis without excessive oxidation, resulting in a uniform amorphous disordered carbon layer structure with abundant micropores and defects, and complete three-dimensional ion transport channels. Simultaneously, the moderate content of oxygen-containing functional groups leads to low interfacial impedance and rapid lithium-ion migration. Appropriate oxygen-containing functional groups enhance electrolyte wettability (at low temperatures, electrolyte viscosity is high; polar functional groups bind to carbonate molecules in the electrolyte via hydrogen bonds, promoting electrolyte diffusion) and improve ionic conductivity. Furthermore, the complete carbon layer with moderate defects effectively inhibits direct reaction between graphite and the electrolyte (reducing excessive SEI film growth), ensuring stable functional groups that are less prone to detachment, resulting in a more uniform SEI film, slower impedance growth during cycling, and a longer cycle life.

[0018] When the flow rate ratio is too high (excessive carbon source), incomplete pyrolysis occurs, leaving unreacted hydrocarbon oligomers in the carbon layer, resulting in a loose and uneven structure, and even agglomeration. Simultaneously, insufficient oxygen-containing gas leads to a low functional group content and poor electrolyte wettability. This results in deterioration of fast-charging, low-temperature performance, and cycle life. Conversely, when the flow rate ratio is too low (excessive oxygen-containing gas), the carbon source is over-oxidized, generating more CO and CO2 gases that escape. This reduces the generation of carbon active species, preventing the formation of a complete coating layer and potentially exposing the graphite substrate. The exposed area directly contacts the electrolyte, directly increasing interfacial impedance and affecting low-temperature performance and cycle life.

[0019] Preferably, the functionalized carbon coating layer contains oxygen-containing functional groups (-COOH and -OH functional groups), and the relative total content of oxygen-containing functional groups is not less than 30%.

[0020] Preferably, the thickness of the functionalized carbon coating layer is 5-15 nm.

[0021] Secondly, the present invention provides a negative electrode sheet comprising the negative electrode material prepared by the above-described preparation method.

[0022] Preferably, the preparation of the negative electrode sheet includes: mixing the negative electrode material with a binder, a conductive agent and a thickener in a certain proportion to form a slurry, coating it on a copper foil, and then drying, rolling and cutting it to form a negative electrode sheet.

[0023] Thirdly, the present invention provides a lithium battery, comprising a negative electrode, a positive electrode, a separator, and an electrolyte.

[0024] Preferably, the positive electrode sheet comprises a high-capacity ternary material (such as NCM523, NCM622, or NCM811).

[0025] Preferably, the separator is a ceramic-coated separator with a thickness of 12-20 μm to improve the thermal safety of the battery.

[0026] Preferably, the electrolyte is a conventional lithium salt (such as LiPF6) dissolved in a carbonate organic solvent.

[0027] Preferably, the lithium battery is manufactured using a Z-shaped stacking process, which offers superior rate performance and heat dissipation compared to the winding process.

[0028] Compared with existing technologies, the present invention has the following advantages: The present invention employs low-temperature (350-450℃) vapor deposition carbon coating technology, in which carbon source gas is decomposed to form a carbon layer, constructing an amorphous disordered layer carbon layer on an artificial graphite substrate; simultaneously, oxygen-containing gas is introduced during the vapor deposition process, which partially oxidizes the newly formed carbon, introducing oxygen-containing functional groups such as carboxyl groups (-COOH) and hydroxyl groups (-OH) in situ on the surface of the carbon layer; the formed functionalized carbon coating layer provides a three-dimensional ion transport channel, significantly reduces interfacial impedance, and improves electrolyte wettability, ultimately obtaining a graphite anode with fast charging, good low-temperature performance, and high cycle life. The lithium-ion battery made using this graphite anode has excellent electrochemical performance. Attached Figure Description

[0029] Figure 1 shows the cycle curves of lithium-ion batteries in Examples 1-5 and Comparative Examples 1-3, which are charged at 25°C and discharged at 3C.

[0030] Figure 2 shows the cycle curves of lithium-ion batteries in Examples 1-5 and Comparative Examples 1-3, which are charged and discharged at 3C at a high temperature of 45°C. Detailed Implementation

[0031] The technical solution of the present invention will be illustrated below with specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0032] 1. Anode Material The specific steps for preparing the anode material are as follows: (1) Pretreatment: Artificial graphite powder with a median particle size of 8-12 μm in D50 is placed in a tube furnace and heated to 350-450℃ at a rate of 5-10℃ / min under an argon (Ar) atmosphere, and kept at the temperature for 0.5h to remove the physically adsorbed water on the surface and activate the surface; (2) Vapor phase co-deposition: Keeping the temperature constant at 350-450℃, carbon source gas (C2H2 and / or CH4) and oxygen-containing gas (CO2 and / or water vapor) are introduced into the reaction system, and the deposition reaction is carried out at atmospheric pressure for 0.5-4h. During this process, the carbon source gas is decomposed to form a carbon layer, while the oxygen-containing gas partially oxidizes the newly formed carbon and introduces oxygen-containing functional groups such as carboxyl groups (-COOH) and hydroxyl groups (-OH) in situ on its surface.

[0033] (3) Post-processing: After the reaction is completed, the reaction gas is stopped and the material is naturally cooled to room temperature under the protection of argon (Ar) atmosphere to obtain the negative electrode material with a functionalized carbon coating on the surface.

[0034] 2. Lithium-ion battery negative electrode sheet: The negative electrode material prepared above is mixed with binder (such as SBR), conductive agent (such as SP), and thickener (such as CMC) in a certain proportion to form a slurry, which is then coated on copper foil, dried, rolled, and slit to form a negative electrode sheet.

[0035] Positive electrode sheet: A slurry is prepared by mixing conventional high-capacity ternary materials (such as NCM523, NCM622, or NCM811), conductive agents (such as SP), and binders (such as PVDF) in a certain proportion, which is then coated onto copper foil and dried, rolled, and slit to form the positive electrode sheet.

[0036] Separator: 12-20μm thick ceramic-coated diaphragm.

[0037] Electrolyte: A conventional lithium salt (such as LiPF6) dissolved in a carbonate organic solvent.

[0038] A lithium-ion battery is obtained by assembling the negative electrode, positive electrode, separator, and electrolyte using a Z-shaped stacking process.

[0039] Example 11. Negative electrode material The specific steps for preparing the negative electrode material are as follows: (1) Pretreatment: Artificial graphite powder with a median particle size of 10 μm in D50 is placed in a tube furnace and heated to 400℃ at a rate of 5℃ / min under an argon atmosphere (Ar: 200 sccm) and kept at that temperature for 0.5h; (2) Vapor phase co-deposition: Keeping the temperature constant at 400℃, carbon source gas (C2H2: 50 sccm) and oxygen-containing gas (CO2: 5 sccm) are introduced into the reaction system and the deposition reaction is carried out at atmospheric pressure for 2h.

[0040] (3) Post-processing: After the reaction is completed, the reaction gas is stopped and the material is naturally cooled to room temperature under the protection of argon (Ar) atmosphere to obtain the negative electrode material with a functionalized carbon coating on the surface.

[0041] 2. Lithium-ion battery negative electrode sheet: The negative electrode material prepared above is mixed with binder (SBR), conductive agent (SP) and thickener (CMC) in a mass ratio of 96:1.5:1:1.5 to form a slurry, which is then coated on copper foil and dried, rolled, and slit to form a negative electrode sheet.

[0042] Positive electrode sheet: A slurry is prepared by mixing conventional high-capacity ternary material (NCM811), conductive agent (SP), and binder (PVDF) in a mass ratio of 97:1.5:1.5. The slurry is coated on copper foil and then dried, rolled, and slit to form the positive electrode sheet.

[0043] Separator: 16μm thick ceramic-coated separator (Al2O3 coating).

[0044] Electrolyte: 1M LiPF6 dissolved in carbonate organic solvent (EC:EMC:DEC = 1:1:1 (Vol%), containing 2wt% VC additive.

[0045] The negative electrode, positive electrode, separator, and electrolyte are assembled using a Z-shaped stacking process to obtain a soft-pack battery with a rated capacity of 57Ah, an in-cell voltage of 3.74V, a weight of 906g, and a weight energy density of 235Wh / Kg.

[0046] The difference between Example 2 and Example 1 is that CH4 is used as the carbon source gas.

[0047] 1. Anode Material The specific steps for preparing the anode material are as follows: (1) Pretreatment: Place artificial graphite powder with a median particle size of 10 μm in a tube furnace, heat it to 400℃ at a rate of 5℃ / min under an argon atmosphere (Ar: 200 sccm), and keep it at that temperature for 0.5h; (2) Gas phase co-deposition: Keep the temperature constant at 400℃, introduce carbon source gas (CH4: 50 sccm) and oxygen-containing gas (CO2: 5 sccm) into the reaction system, and carry out the deposition reaction for 2h under normal pressure.

[0048] (3) Post-processing: After the reaction is completed, the reaction gas is stopped and the material is naturally cooled to room temperature under the protection of argon (Ar) atmosphere to obtain the negative electrode material with a functionalized carbon coating on the surface.

[0049] 2. Lithium-ion battery negative electrode sheet: The negative electrode material prepared above is mixed with binder (SBR), conductive agent (SP) and thickener (CMC) in a mass ratio of 96:1.5:1:1.5 to form a slurry, which is then coated on copper foil and dried, rolled, and slit to form a negative electrode sheet.

[0050] Positive electrode sheet: A slurry is prepared by mixing conventional high-capacity ternary material (NCM811), conductive agent (SP), and binder (PVDF) in a mass ratio of 97:1.5:1.5. The slurry is coated on copper foil and then dried, rolled, and slit to form the positive electrode sheet.

[0051] Separator: 16μm thick ceramic-coated separator (Al2O3 coating).

[0052] Electrolyte: 1M LiPF6 dissolved in carbonate organic solvent (EC:EMC:DEC = 1:1:1 (Vol%), containing 2wt% VC additive.

[0053] The negative electrode, positive electrode, separator, and electrolyte are assembled using a Z-shaped stacking process to obtain a soft-pack battery with a rated capacity of 57Ah, an in-cell voltage of 3.74V, a weight of 906g, and a weight energy density of 235Wh / Kg.

[0054] The difference between Example 3 and Example 1 is that water vapor is used as the oxygen-containing gas.

[0055] 1. Anode Material The specific steps for preparing the anode material are as follows: (1) Pretreatment: Place artificial graphite powder with a median particle size of 10 μm in a tube furnace, heat it to 400℃ at a rate of 5℃ / min under an argon atmosphere (Ar: 200 sccm), and keep it at that temperature for 0.5h; (2) Gas phase co-deposition: Keep the temperature constant at 400℃, introduce carbon source gas (C2H2: 50 sccm) and oxygen-containing gas (water vapor: 5 sccm) into the reaction system, and carry out the deposition reaction for 2h under normal pressure.

[0056] (3) Post-processing: After the reaction is completed, the reaction gas is stopped and the material is naturally cooled to room temperature under the protection of argon (Ar) atmosphere to obtain the negative electrode material with a functionalized carbon coating on the surface.

[0057] 2. Lithium-ion battery negative electrode sheet: The negative electrode material prepared above is mixed with binder (SBR), conductive agent (SP) and thickener (CMC) in a mass ratio of 96:1.5:1:1.5 to form a slurry, which is then coated on copper foil and dried, rolled, and slit to form a negative electrode sheet.

[0058] Positive electrode sheet: A slurry is prepared by mixing conventional high-capacity ternary material (NCM811), conductive agent (SP), and binder (PVDF) in a mass ratio of 97:1.5:1.5. The slurry is coated on copper foil and then dried, rolled, and slit to form the positive electrode sheet.

[0059] Separator: 16μm thick ceramic-coated separator (Al2O3 coating).

[0060] Electrolyte: 1M LiPF6 dissolved in carbonate organic solvent (EC:EMC:DEC = 1:1:1 (Vol%), containing 2wt% VC additive.

[0061] The negative electrode, positive electrode, separator, and electrolyte are assembled using a Z-shaped stacking process to obtain a soft-pack battery with a rated capacity of 57Ah, an in-cell voltage of 3.74V, a weight of 906g, and a weight energy density of 235Wh / Kg.

[0062] The difference between Example 4 and Example 1 is that the flow ratio of carbon source gas to oxygen-containing gas is 5:1.

[0063] 1. Anode Material The specific steps for preparing the anode material are as follows: (1) Pretreatment: Place artificial graphite powder with a median particle size of 10 μm in a tube furnace, heat it to 400℃ at a rate of 5℃ / min under an argon atmosphere (Ar: 200 sccm), and keep it at that temperature for 0.5h; (2) Gas phase co-deposition: Keep the temperature constant at 400℃, introduce carbon source gas (C2H2: 50 sccm) and oxygen-containing gas (CO2: 10 sccm) into the reaction system, and carry out the deposition reaction for 2h under normal pressure.

[0064] (3) Post-processing: After the reaction is completed, the reaction gas is stopped and the material is naturally cooled to room temperature under the protection of argon (Ar) atmosphere to obtain the negative electrode material with a functionalized carbon coating on the surface.

[0065] 2. Lithium-ion battery negative electrode sheet: The negative electrode material prepared above is mixed with binder (SBR), conductive agent (SP) and thickener (CMC) in a mass ratio of 96:1.5:1:1.5 to form a slurry, which is then coated on copper foil and dried, rolled, and slit to form a negative electrode sheet.

[0066] Positive electrode sheet: A slurry is prepared by mixing conventional high-capacity ternary material (NCM811), conductive agent (SP), and binder (PVDF) in a mass ratio of 97:1.5:1.5. The slurry is coated on copper foil and then dried, rolled, and slit to form the positive electrode sheet.

[0067] Separator: 16μm thick ceramic-coated separator (Al2O3 coating).

[0068] Electrolyte: 1M LiPF6 dissolved in carbonate organic solvent (EC:EMC:DEC = 1:1:1 (Vol%), containing 2wt% VC additive.

[0069] The negative electrode, positive electrode, separator, and electrolyte are assembled using a Z-shaped stacking process to obtain a soft-pack battery with a rated capacity of 57Ah, an in-cell voltage of 3.74V, a weight of 906g, and a weight energy density of 235Wh / Kg.

[0070] The difference between Example 5 and Example 1 is that the vapor deposition temperature used is 350°C.

[0071] 1. Anode Material The specific steps for preparing the anode material are as follows: (1) Pretreatment: Place artificial graphite powder with a median particle size of 10 μm in a tube furnace, heat it to 350°C at a rate of 5°C / min under an argon atmosphere (Ar: 200 sccm), and keep it at that temperature for 0.5 h; (2) Gas phase co-deposition: Keep the temperature constant at 350°C, introduce carbon source gas (C2H2: 50 sccm) and oxygen-containing gas (CO2: 5 sccm) into the reaction system, and carry out the deposition reaction for 3 h under normal pressure.

[0072] (3) Post-processing: After the reaction is completed, the reaction gas is stopped and the material is naturally cooled to room temperature under the protection of argon (Ar) atmosphere to obtain the negative electrode material with a functionalized carbon coating on the surface.

[0073] 2. Lithium-ion battery negative electrode sheet: The negative electrode material prepared above is mixed with binder (SBR), conductive agent (SP) and thickener (CMC) in a mass ratio of 96:1.5:1:1.5 to form a slurry, which is then coated on copper foil and dried, rolled, and slit to form a negative electrode sheet.

[0074] Positive electrode sheet: A slurry is prepared by mixing conventional high-capacity ternary material (NCM811), conductive agent (SP), and binder (PVDF) in a mass ratio of 97:1.5:1.5. The slurry is coated on copper foil and then dried, rolled, and slit to form the positive electrode sheet.

[0075] Separator: 16μm thick ceramic-coated separator (Al2O3 coating).

[0076] Electrolyte: 1M LiPF6 dissolved in carbonate organic solvent (EC:EMC:DEC = 1:1:1 (Vol%), containing 2wt% VC additive.

[0077] The negative electrode, positive electrode, separator, and electrolyte are assembled using a Z-shaped stacking process to obtain a soft-pack battery with a rated capacity of 57Ah, an in-cell voltage of 3.74V, a weight of 906g, and a weight energy density of 235Wh / Kg.

[0078] The difference between Comparative Example 1 and Example 1 is that the graphite was carbon-coated using high-temperature vapor deposition technology (temperature 800°C).

[0079] 1. Anode Material The specific steps for preparing the anode material are as follows: (1) Pretreatment: Place artificial graphite powder with a median particle size of 10 μm in a tube furnace, heat it to 800℃ at a rate of 5℃ / min under an argon atmosphere (Ar: 200 sccm), and keep it at that temperature for 0.5h; (2) Vapor phase co-deposition: Keep the temperature constant at 800℃, introduce carbon source gas (C2H2: 50 sccm) into the reaction system, and carry out the deposition reaction for 2h under normal pressure.

[0080] (3) Post-processing: After the reaction is completed, the reaction gas is stopped and the material is naturally cooled to room temperature under the protection of argon (Ar) atmosphere to obtain the negative electrode material with carbon coating on the surface.

[0081] 2. Lithium-ion battery negative electrode sheet: The negative electrode material prepared above is mixed with binder (SBR), conductive agent (SP) and thickener (CMC) in a mass ratio of 96:1.5:1:1.5 to form a slurry, which is then coated on copper foil and dried, rolled, and slit to form a negative electrode sheet.

[0082] Positive electrode sheet: A slurry is prepared by mixing conventional high-capacity ternary material (NCM811), conductive agent (SP), and binder (PVDF) in a mass ratio of 97:1.5:1.5. The slurry is coated on copper foil and then dried, rolled, and slit to form the positive electrode sheet.

[0083] Separator: 16μm thick ceramic-coated separator (Al2O3 coating).

[0084] Electrolyte: 1M LiPF6 dissolved in carbonate organic solvent (EC:EMC:DEC = 1:1:1 (Vol%), containing 2wt% VC additive.

[0085] The negative electrode, positive electrode, separator, and electrolyte are assembled using a Z-shaped stacking process to obtain a soft-pack battery with a rated capacity of 57Ah, an in-cell voltage of 3.74V, a weight of 906g, and a weight energy density of 235Wh / Kg.

[0086] The difference between Comparative Example 2 and Example 1 is that the flow ratio of carbon source gas to oxygen-containing gas is 20:1.

[0087] 1. Anode Material The specific steps for preparing the anode material are as follows: (1) Pretreatment: Place artificial graphite powder with a median particle size of 10 μm in a tube furnace, heat it to 400℃ at a rate of 5℃ / min under an argon atmosphere (Ar: 200 sccm), and keep it at that temperature for 0.5h; (2) Gas phase co-deposition: Keep the temperature constant at 400℃, introduce carbon source gas (C2H2: 100 sccm) and oxygen-containing gas (CO2: 5 sccm) into the reaction system, and carry out the deposition reaction for 2h under normal pressure.

[0088] (3) Post-processing: After the reaction is completed, the reaction gas is stopped and the material is naturally cooled to room temperature under the protection of argon (Ar) atmosphere to obtain the negative electrode material with a functionalized carbon coating on the surface.

[0089] 2. Lithium-ion battery negative electrode sheet: The negative electrode material prepared above is mixed with binder (SBR), conductive agent (SP) and thickener (CMC) in a mass ratio of 96:1.5:1:1.5 to form a slurry, which is then coated on copper foil and dried, rolled, and slit to form a negative electrode sheet.

[0090] Positive electrode sheet: A slurry is prepared by mixing conventional high-capacity ternary material (NCM811), conductive agent (SP), and binder (PVDF) in a mass ratio of 97:1.5:1.5. The slurry is coated on copper foil and then dried, rolled, and slit to form the positive electrode sheet.

[0091] Separator: 16μm thick ceramic-coated separator (Al2O3 coating).

[0092] Electrolyte: 1M LiPF6 dissolved in carbonate organic solvent (EC:EMC:DEC = 1:1:1 (Vol%), containing 2wt% VC additive.

[0093] The negative electrode, positive electrode, separator, and electrolyte are assembled using a Z-shaped stacking process to obtain a soft-pack battery with a rated capacity of 57Ah, an in-cell voltage of 3.74V, a weight of 906g, and a weight energy density of 235Wh / Kg.

[0094] The difference between Comparative Example 3 and Example 1 is that the flow ratio of carbon source gas to oxygen-containing gas is 2:1.

[0095] 1. Anode Material The specific steps for preparing the anode material are as follows: (1) Pretreatment: Place artificial graphite powder with a median particle size of 10 μm in a tube furnace, heat it to 400℃ at a rate of 5℃ / min under an argon atmosphere (Ar: 200 sccm), and keep it at that temperature for 0.5h; (2) Gas phase co-deposition: Keep the temperature constant at 400℃, introduce carbon source gas (C2H2: 50 sccm) and oxygen-containing gas (CO2: 25 sccm) into the reaction system, and carry out the deposition reaction for 2h under normal pressure.

[0096] (3) Post-processing: After the reaction is completed, the reaction gas is stopped and the material is naturally cooled to room temperature under the protection of argon (Ar) atmosphere to obtain the negative electrode material with a functionalized carbon coating on the surface.

[0097] 2. Lithium-ion battery negative electrode sheet: The negative electrode material prepared above is mixed with binder (SBR), conductive agent (SP) and thickener (CMC) in a mass ratio of 96:1.5:1:1.5 to form a slurry, which is then coated on copper foil and dried, rolled, and slit to form a negative electrode sheet.

[0098] Positive electrode sheet: A slurry is prepared by mixing conventional high-capacity ternary material (NCM811), conductive agent (SP), and binder (PVDF) in a mass ratio of 97:1.5:1.5. The slurry is coated on copper foil and then dried, rolled, and slit to form the positive electrode sheet.

[0099] Separator: 16μm thick ceramic-coated separator (Al2O3 coating).

[0100] Electrolyte: 1M LiPF6 dissolved in carbonate organic solvent (EC:EMC:DEC = 1:1:1 (Vol%), containing 2wt% VC additive.

[0101] The negative electrode, positive electrode, separator, and electrolyte are assembled using a Z-shaped stacking process to obtain a soft-pack battery with a rated capacity of 57Ah, an in-cell voltage of 3.74V, a weight of 906g, and a weight energy density of 235Wh / Kg.

[0102] Performance Testing: 1. Fast Charging Test (25℃): First, charge to 4.2V at a constant current of 0.5C and record the capacity C0. Then charge to 4.2V at a constant current of 4C and record the capacity C4. Calculate the 4C charging retention rate = (C4 / C0) × 100%.

[0103] 2. Low-temperature discharge test (-20℃): Fully charge the battery at 0.5C at 25℃. Then place the battery in a -20℃ environment for 4 hours. Afterward, discharge at a constant current of 0.5C at -20℃ until the cutoff voltage. Calculate the low-temperature discharge efficiency = (low-temperature discharge capacity / room temperature charging capacity) × 100%.

[0104] 3. Cycle life test: The test measures the number of cycles of 3C charging and 3C discharging at 25℃ (room temperature) and 45℃ (high temperature) with 100% DOD.

[0105] Table 1 As shown in Table 1, the lithium-ion battery made using the negative electrode material of this invention has a capacity retention rate of ≥91% under a 4C charging regime and a discharge efficiency of ≥82% at an ambient temperature of -20℃. As shown in Figures 1 and 2, when the capacity retention rate is 80%, the maximum number of cycles under 3C charging and 3C discharging at room temperature (25℃) can reach more than 15,000, and the maximum number of cycles under 3C / 3D charging at high temperature (45℃) can reach 8,500. It has an ultra-long fast charging cycle capability, and the energy density of the battery reaches 235Wh / kg or more. It is a battery that truly combines fast charging, high energy density and ultra-long cycle life. Its fast charging and cycle life performance reaches the performance of lithium titanate batteries, but its energy density is nearly 3 times that of lithium titanate batteries.

[0106] Furthermore, since the vapor deposition temperature used in Example 5 is lower than that used in Example 1, the amount of carbon active species generated and the amount of carbon layer deposited are less, resulting in lower capacity retention, low-temperature discharge efficiency, and cycle life. This indicates that if the vapor deposition temperature is too low, the carbon source cannot be effectively decomposed, the carbon layer cannot form an effective coating, and fast charging, low-temperature performance, and cycle life will all decrease significantly. Examples 1, 4, and Comparative Examples 2-3 show that both excessively high and low flow ratios of carbon source gas and oxygen-containing gas will affect battery performance. Specifically, when the flow ratio is too high (excessive carbon source), incomplete decomposition will occur, while insufficient oxygen-containing gas will result in low functional group content and poor electrolyte wettability. When the flow ratio is too low (excessive oxygen-containing gas), the amount of carbon active species generated will decrease, a complete coating layer cannot be formed, and even the graphite substrate may be exposed.

[0107] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made using the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing a high-energy-density, ultra-long-life, fast-charging anode material, characterized in that, The process includes the following steps: preheating graphite under inert gas protection, then introducing carbon source gas and oxygen-containing gas, and carrying out a deposition reaction at 350-450℃ and normal pressure for 0.5-4 hours to obtain a negative electrode material with a functionalized carbon coating layer on the surface. The structure of the functionalized carbon coating layer is an amorphous disordered layer structure containing oxygen-containing functional groups.

2. The preparation method of the high energy density, ultra-long lifespan, fast-charging anode material according to claim 1, characterized in that, The preheating temperature is 350-450℃.

3. The method for preparing the high energy density, ultra-long lifespan, fast-charging anode material according to claim 1 or 2, characterized in that, The median D50 particle size of the graphite is 8-12 μm.

4. The preparation method of the high energy density, ultra-long lifespan, fast-charging anode material according to claim 1, characterized in that, The carbon source gas includes C2H2 and / or CH4.

5. The preparation method of the high energy density, ultra-long lifespan, fast-charging anode material according to claim 1, characterized in that, The oxygen-containing gas includes CO2 and / or water vapor.

6. The method for preparing the high energy density, ultra-long lifespan, fast-charging anode material according to claim 1, 4, or 5, characterized in that, The flow rate ratio of the carbon source gas to the oxygen-containing gas is 5-15:

1.

7. The method for preparing the high energy density, ultra-long lifespan, fast-charging anode material according to claim 1, 4, or 5, characterized in that, The functionalized carbon coating layer contains -COOH and -OH functional groups; the thickness of the functionalized carbon coating layer is 5-15 nm.

8. A negative electrode sheet, characterized in that, Includes the negative electrode material prepared by the preparation method according to any one of claims 1-7.

9. A lithium battery, characterized in that, It includes the negative electrode, positive electrode, separator, and electrolyte as described in claim 8.

10. The lithium battery according to claim 9, characterized in that, The lithium battery is manufactured using a Z-shaped stacking process.

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