A negative electrode material, a preparation method, application and a button lithium battery comprising the same

Abstract

The application discloses a kind of negative electrode material, preparation method, application and contain its button lithium battery, belong to electrochemical energy storage device technical field, negative electrode material includes following raw materials: silicon monoxide, active component, binder and conductive agent;Wherein, the active component is selected from at least one in microcrystalline graphite and hard carbon.It is prepared process: silicon monoxide and active component are dissolved in solvent, conductive agent is added to it and is mixed after ball milling dispersion, and continue to ball mill and be obtained even slurry after adding binder;Slurry is coated on copper foil, after drying, roll pressing and obtain the negative electrode material described above.That is, the application is by optimizing negative electrode material system, with silicon monoxide as base and composite graphite or hard carbon and other conductive buffer component structure design, effectively reduce the lithium ion loss caused in first charge process;While combining fine manufacturing process, ensure the uniformity and integrity of electrode internal structure, to significantly improve the initial efficiency of battery.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage device technology, and particularly relates to a negative electrode material, preparation method, application, and a button lithium battery containing the same. Background Technology

[0002] With the development of technology, lithium batteries have been widely used in portable electronic devices and vehicles due to their high energy density, lightweight characteristics, and long cycle life. Especially in consumer electronics and new energy transportation, lithium batteries have become an ideal energy storage solution due to their high energy density, long cycle life, low self-discharge rate, wide operating temperature range, lack of memory effect, environmental friendliness, and safety. Furthermore, in the field of energy storage batteries, the application of lithium batteries is rapidly expanding with technological advancements.

[0003] However, despite the significant advantages of lithium-ion batteries and their wide range of applications, existing button-type lithium-ion batteries and their manufacturing processes still face several pressing issues. First, the external tabs of button-type lithium-ion batteries are typically fixed to the electrodes by welding. This connection method is not only unstable but also prone to detachment due to vibration or temperature changes, leading to abnormal charging and discharging and severely impacting the battery's operational stability. Second, traditional manufacturing processes require coating and fixing the electrodes onto conductive sheets before winding and mounting them into the battery casing. This not only increases manufacturing complexity but also reduces the product yield, further affecting production efficiency and cost control.

[0004] Furthermore, the lack of sufficient pretreatment steps for raw materials in existing processing techniques results in low conductivity of the manufactured electrodes and poor bonding performance of the prepared positive and negative electrode slurries. These factors directly affect the grouting effect and limit the full potential of the battery performance. Specifically, using unoptimized raw materials directly in subsequent processes often leads to problems such as uneven internal structure of the electrode materials and poor interfacial contact, thereby weakening the overall performance of the battery.

[0005] In summary, although lithium-ion batteries have broad application prospects, the current manufacturing process of button-type lithium-ion batteries still faces many challenges, including but not limited to key issues such as poor connection stability, complex manufacturing processes, and low raw material utilization. These problems not only restrict product quality improvement but also hinder the industry's progress to a higher level. Therefore, it is essential to develop a new generation of button-type lithium-ion batteries and their manufacturing methods that can effectively overcome the aforementioned shortcomings. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a negative electrode material, a preparation method, an application, and a button lithium battery containing the same.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A negative electrode material, comprising the following raw materials:

[0009] Silicon suboxide (SiO), active components, binders, and conductive agents;

[0010] The active component is selected from at least one of microcrystalline graphite and hard carbon.

[0011] Optionally, the active component is 5-20% of the total mass of the silicon suboxide and the active component.

[0012] Furthermore, the active component is 5%, 10%, 15%, or 20% of the total mass of the silicon suboxide and the active component.

[0013] Optionally, the mass ratio of the silicon suboxide, active component, binder and conductive agent is (4.8-5.7):(0.3-1.2):2:2.

[0014] Optionally, the adhesive is an aqueous solution of polyacrylic acid with a mass concentration of 6%.

[0015] Optionally, the conductive agent is carbon black (SP).

[0016] A method for preparing a negative electrode material includes the following steps:

[0017] Silicon suboxide and active components are dissolved in a solvent, a conductive agent is added and mixed, and then the mixture is ball-milled and dispersed. A binder is then added and ball-milling is continued to obtain a uniform slurry. The slurry is coated onto copper foil, and after drying and rolling, the negative electrode material is obtained.

[0018] Optionally, the dissolution process is as follows: the silicon suboxide and the active component are mixed evenly to obtain a mixture, and then deionized water and anhydrous ethanol are added sequentially, and the mixture is shaken to dissolve it completely.

[0019] Furthermore, the ratio of the mixture, deionized water, and anhydrous ethanol is 800 mg: 9 mL: 1 mL.

[0020] Optionally, the ball milling dispersion conditions are: ball milling for 6-12 hours at a frequency of 14-16 Hz;

[0021] The conditions for continuing ball milling are: ball milling for 2 hours at a frequency of 14-16 Hz.

[0022] Optionally, the drying conditions are: drying at 80°C until the solvent is completely removed.

[0023] The application of the above-mentioned negative electrode materials in the preparation of button lithium-ion batteries.

[0024] A button lithium-ion battery includes a casing, a pre-drilled slot, a negative electrode casing, an electrode sheet, a positive electrode casing, a gasket, an electrolyte, a spring sheet, and a separator;

[0025] The electrode includes a positive electrode and a negative electrode, wherein the negative electrode is the aforementioned negative electrode material, and the positive electrode is a single-element lithium electrode.

[0026] Beneficial Effects: The button lithium-ion battery prepared using the negative electrode material disclosed in this invention not only has lower cost and higher initial charge-discharge efficiency, but also exhibits significantly better discharge performance than traditional button lithium-ion batteries, effectively improving its lifespan and discharge specific capacity. This is mainly due to the excellent properties of silicon suboxide (SiO) in the negative electrode material: SiO has an ultra-high theoretical capacity (2600mAh / g), a self-built buffer layer for lithium insertion / extraction, less volume expansion, less SEI (solid electrolyte interphase), more stable cycling, adjustable particle size, and controllable Si grain size. Furthermore, the silicon-carbon composite material prepared by combining silicon suboxide and carbon materials in this invention has advantages such as excellent air permeability, corrosion resistance, and high specific capacity. The high specific capacity and high specific energy allow for the storage of more charge and the provision of more energy output. During cyclic charging and discharging, it maintains a relatively stable structure and performance, and is less prone to severe capacity decay. It also possesses high electronic conductivity, providing a fast electron transport channel and improving the battery's charging and discharging efficiency. Furthermore, the nano-silicon-carbon material (anode material) prepared in this invention exhibits good mechanical stability during charging and discharging, and is less prone to structural breakage or detachment. This further enhances the long-term reliability of the battery under complex operating conditions.

[0027] In summary, this invention achieves controllable fabrication of high-performance, long-life, and low-cost button lithium-ion batteries through material design and process optimization.

[0028] Compared with the prior art, the present invention has the following advantages and technical effects:

[0029] 1. Significantly improves first charge and discharge efficiency: This invention optimizes the negative electrode material system by adopting a structural design based on silicon suboxide (SiO) and composite with conductive buffer components such as graphite or hard carbon, which effectively reduces lithium-ion loss during the first charge. At the same time, combined with refined manufacturing processes (such as step-by-step ball milling, solution binder addition, uniform coating and rolling), the uniformity and integrity of the internal structure of the electrode are ensured, thereby significantly improving the battery's first-charge efficiency.

[0030] 2. Effective control of production costs: While improving performance, this invention reduces overall manufacturing costs by using reasonable material ratios, reducing raw material waste, simplifying process flow, and improving equipment automation, thus achieving a good balance between high performance and economy.

[0031] 3. Ensure product quality and stability: From raw material selection, slurry preparation, electrode processing to battery assembly and finished product testing, strict quality control is implemented throughout the entire process to ensure that the products have high consistency, reliability and long-term cycle stability, and to ensure that the final products meet high quality standards.

[0032] 4. Promoting the market application of high-performance button lithium batteries: The button lithium battery prepared by this invention has the advantages of high initial efficiency, high energy density, excellent cycle performance and cost, providing the market with a new type of micro power solution that is high-performance, reliable and competitive. Attached Figure Description

[0033] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0034] Figure 1 The specific capacity-voltage curve of the button lithium battery prepared by Example 1 (100% SiO) as the negative electrode material after 69 cycles.

[0035] Figure 2 The formation curves of button lithium batteries using SiO composites with different proportions of microcrystalline graphite as negative electrode materials in Examples 2-5 of this invention are shown.

[0036] Figure 3 The cycle performance curves of button lithium batteries using SiO composites with different proportions of microcrystalline graphite as negative electrode materials in Examples 2-5 of this invention are shown.

[0037] Figure 4 The formation curves of button lithium batteries using SiO composites with different proportions of hard carbon as the negative electrode material in Examples 6-9 of this invention are shown. Detailed Implementation

[0038] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0039] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0040] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0041] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0042] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0043] This invention discloses a method for preparing a button lithium battery, comprising the following steps:

[0044] I. Material and Equipment Preparation

[0045] Planetary ball mill;

[0046] SiO+ active ingredient ∶PAA ∶SP = 6 ∶ 2 ∶ 2;

[0047] SiO+ active ingredient: SiO+ microcrystalline graphite, or SiO+ hard carbon, 600mg;

[0048] Adhesive: PAA, 200mg;

[0049] Conductive agent: SP, 200mg;

[0050] Positive electrode shell, negative electrode shell, separator, gasket, lithium sheet, spring and electrolyte treatment materials: ensure all components are clean.

[0051] II. Specific steps for electrode fabrication (the following steps are performed in a planetary ball mill)

[0052] Prepare a 50mL beaker;

[0053] First, weigh 600 mg of SiO; add 200 mg of SP; add 9 ml of deionized water to the beaker, shake the beaker well to allow the deionized water to penetrate into the material; then add 1 ml of anhydrous ethanol to the beaker, shake the beaker well to allow the anhydrous ethanol to penetrate into the material.

[0054] Seal the beaker with plastic wrap and place it into the planetary ball mill;

[0055] Adjust the rotation speed of the planetary ball mill according to the actual situation; that is: (1) If it needs to rotate for 12 hours, adjust the frequency to 14HZ and the rotation speed will be automatically displayed as 180; (2) If it needs to rotate for 6 hours, adjust the frequency to 16HZ and the rotation speed will be automatically displayed as 206.

[0056] After ball milling for 6 hours, remove the beaker and add 3.33g of PAA (since the mass fraction of PAA is 6%, the actual amount of PAA is 200mg. It should be noted that solid raw materials cannot be added directly to PAA, because particle residue will appear after granular coating. A mixture should be added and prepared in advance). Put it back into the planetary ball mill and mill for 2 hours at the same frequency and speed.

[0057] Coating is performed, with two areas coated each time. Specifically, this invention uses a graphite coating and pressing method to prepare the negative electrode material, and the specific operation is as follows:

[0058] 1. Coating machine operation steps

[0059] (1) Open the machine cover, wipe the surface of the coating machine several times with alcohol, and place copper foil on it;

[0060] (2) Add negative electrode material slurry near the roller. That is, the slurry needs to be coated onto the conductive copper foil. Pay attention to uniform coating and reasonable thickness control to ensure the consistency of battery performance.

[0061] (3) Start the machine and make the roller roll evenly over the slurry (Note: Press down by hand to prevent the roller from bouncing up).

[0062] (4) Turn off the machine, remove the copper foil, and wipe the roller clean with alcohol;

[0063] 2. Drying Oven Operation Procedures

[0064] (1) Adjust the temperature and turn on the drying oven;

[0065] (2) Place the copper foil in the drying oven and fix it in the drying oven with a magnet;

[0066] (3) Adjust the temperature according to the selected material, dry the negative electrode at 80°C, roll it and then press the negative electrode sheet.

[0067] (4) After tableting, weigh and record the data, and put it in a drying oven for 24 hours.

[0068] 3. Assemble the button lithium batteries inside the glove box:

[0069] (1) Place the negative electrode shell facing upwards on the paper and lay it flat;

[0070] (2) Clamp the lithium sheet and place it into the negative electrode shell;

[0071] (3) Clamp the diaphragm and cover the lithium sheet;

[0072] (4) Add 50 μL of electrolyte using a pipette;

[0073] (5) Pick up the electrode sheet (copper foil coated with the negative electrode material prepared in this invention) and place it in the center;

[0074] (6) Place a pad on the electrode sheet and align it precisely;

[0075] (7) Pick up the spring clip and place it on the pad, making sure it is properly aligned;

[0076] (8) Use tweezers to pick up the positive electrode shell and cover it;

[0077] (9) Use insulated tweezers to clamp the battery and place it into the packaging machine with the negative terminal facing down;

[0078] (10) Assembly complete, organize items; battery removed from the compartment.

[0079] The following points should be noted during the assembly process:

[0080] Ensure that the water and oxygen concentration in the glove box is normal. When materials are sent into the transition chamber for vacuum cleaning in the glove box, three cycles of vacuum cleaning should be performed.

[0081] Lithium sheets are relatively soft and easily deformed. The deformed lithium sheets can be flattened using the positive electrode shell. However, metallic lithium is extremely prone to oxidation and deterioration in air and is easily exploded when exposed to water. Therefore, direct contact between the positive and negative electrodes must be avoided during assembly in a glove box to prevent short circuits. Insulated tweezers should also be used for assembly.

[0082] In addition, various materials need to be processed before the preparation of lithium-ion batteries. For example, the negative electrode material needs to be ball-milled, specifically: (1) If ball milling is required for 12 hours, the frequency is adjusted to 14 Hz and the rotation number is automatically displayed as 180; (2) If ball milling is required for 6 hours, the frequency is adjusted to 16 Hz and the rotation number is automatically displayed as 206, in order to increase its conductivity and specific capacity.

[0083] IV. Battery Testing

[0084] Battery testers are used to check the battery's capacity, internal resistance, and other performance characteristics to ensure the battery quality meets standards. Quality control is a crucial aspect of lithium battery production, encompassing all aspects of raw materials, manufacturing processes, and finished products. The following are quality control measures for lithium batteries:

[0085] (1) Raw material quality control: Strict quality inspection of purchased raw materials to ensure that they meet relevant standards and requirements.

[0086] (2) Finished product inspection: A comprehensive inspection of the finished product is carried out, including capacity testing, cycle life testing, and first-efficiency testing. These tests can verify the performance of the product and ensure that the first-efficiency of the product can be significantly improved compared with existing technologies.

[0087] (3) Continuous improvement: By collecting and analyzing quality data, we continuously improve production processes and quality control measures to enhance product performance.

[0088] The test steps and conditions for the formation curves involved in this invention are shown in Table 1.

[0089] Table 1 Test procedures and conditions for curve transformation

[0090]

[0091] Unless otherwise specified, the term "parts" in this invention refers to parts by weight.

[0092] All raw materials used in this invention were purchased commercially. The microcrystalline graphite (MG) used in the following examples was purchased from Ganzhou Kangda New Energy Materials Co., Ltd., model KDG; the hard carbon was purchased from Ganzhou Litan New Energy Technology Co., Ltd., model LHC-5.

[0093] The technical solution of the present invention will be further illustrated by the following embodiments.

[0094] Example 1 (100% SiO)

[0095] A method for preparing a negative electrode material includes the following steps:

[0096] (1) Weigh the materials according to the mass ratio of SiO:PAA (polyacrylic acid):SP (carbon black) = 6:2:2. Specifically, take 600mg of silicon suboxide (SiO) and 200mg of carbon black (SP), and prepare 3.33g of 6% polyacrylic acid (PAA) aqueous solution (containing 200mg of solid PAA; solid PAA should not be used directly to avoid residual particles after coating).

[0097] (2) Weigh the SiO and SP and add them to a 50mL beaker. Then add 9mL of deionized water and gently shake to allow the water to fully penetrate the powder. Add 1mL of anhydrous ethanol and shake again to improve wettability. Seal the beaker with plastic wrap to prevent solvent evaporation and place it in a planetary ball mill. Ball mill for 6 hours at a frequency of 16Hz (corresponding to a speed of about 206rpm) to allow the active material and conductive agent to be initially and uniformly mixed. After ball milling, remove the beaker and add 3.33g of pre-prepared PAA aqueous solution. Seal again and place it back in the planetary ball mill. Continue ball milling for 2 hours under the same parameters to fully disperse the binder and form a homogeneous and stable negative electrode slurry.

[0098] (3) Then carry out the coating operation: First, thoroughly clean the roller and worktable of the coating machine with alcohol, put copper foil on it and fix it, place the slurry near the roller, start the machine to make the roller roll the slurry evenly to form a coating. During the operation, you need to press the roller lightly by hand to prevent it from bouncing up and causing uneven thickness. Coat 2 negative electrode sheets each time. After the coating is completed, take out the copper foil with the coating and clean the equipment.

[0099] (4) Place the coated copper foil into an oven, fix it to the inner wall with a magnet, and dry it at 80°C to remove the solvent. The dried electrode sheet needs to be rolled to improve the electrode density and interfacial contact performance. Then cut it into the required size and weigh and record the quality data of each piece. After that, transfer it to a glove box with strictly controlled water and oxygen content for subsequent button cell assembly.

[0100] The entire preparation process, through the design of a SiO-based composite system, stepwise ball milling for optimized dispersion, addition of solution-based binders, and strict control of drying and rolling, aims to reduce irreversible lithium loss during the first charge and discharge process, thereby effectively improving the battery's initial efficiency.

[0101] Example 2

[0102] A method for preparing a negative electrode material differs from Example 1 in that 600 mg of SiO is replaced with an equal mass of a mixture of SiO and MG, wherein the mass percentage of MG is 5%, i.e., SiO + 5% MG.

[0103] Example 3

[0104] A method for preparing a negative electrode material differs from Example 1 in that 600 mg of SiO is replaced with an equal mass of SiO and MG, wherein the mass percentage of MG is 10%, i.e., SiO + 10% MG.

[0105] Example 4

[0106] A method for preparing a negative electrode material differs from Example 1 in that 600 mg of SiO is replaced with an equal mass of a mixture of SiO and MG, wherein the mass percentage of MG is 15%, i.e., SiO + 15% MG.

[0107] Example 5

[0108] A method for preparing a negative electrode material differs from Example 1 in that 600 mg of SiO is replaced with an equal mass of a mixture of SiO and MG, wherein the mass percentage of MG is 20%, i.e., SiO + 20% MG.

[0109] Example 6

[0110] A method for preparing a negative electrode material differs from Example 1 in that 600 mg of SiO is replaced with an equal mass of a mixture of SiO and hard carbon, wherein the mass percentage of hard carbon is 5%, i.e., SiO + 5% hard carbon.

[0111] Example 7

[0112] A method for preparing a negative electrode material differs from Example 1 in that 600 mg of SiO is replaced with an equal mass of a mixture of SiO and hard carbon, wherein the mass percentage of hard carbon is 10%, i.e., SiO + 10% hard carbon.

[0113] Example 8

[0114] A method for preparing a negative electrode material differs from Example 1 in that 600 mg of SiO is replaced with an equal mass of a mixture of SiO and hard carbon, wherein the mass percentage of hard carbon is 15%, i.e., SiO + 15% hard carbon.

[0115] Example 9

[0116] A method for preparing a negative electrode material differs from Example 1 in that 600 mg of SiO is replaced with an equal mass of a mixture of SiO and hard carbon, wherein the mass percentage of hard carbon is 15%, i.e., SiO + 20% hard carbon.

[0117] Application Example 1

[0118] This invention modifies the proportions of microcrystalline graphite and SiO composite, and hard carbon and SiO composite to prepare different button lithium batteries for experiments. The performance and charge / discharge specific capacity of these batteries are compared to produce more efficient and energy-saving button lithium batteries. The specific process of assembling button batteries using the negative electrode materials synthesized in the above embodiments is as follows:

[0119] First, before assembly, ensure that the water and oxygen content in the glove box are within acceptable ranges. All battery components (including positive electrode shell, negative electrode shell, separator, spring, gasket, etc.) have been cleaned and dried, and sent into the glove box through the transition chamber. Three vacuum-inert gas filling cleaning cycles are completed in the transition chamber to thoroughly remove the moisture and oxygen adsorbed on the surface.

[0120] The battery assembly then begins: First, the negative electrode shell is laid flat on the paper with the opening facing upwards; then, a lithium sheet is placed into the negative electrode shell using tweezers, and a separator is placed on top of the lithium sheet; next, 50 μL of electrolyte (composed of lithium salt and organic solvents such as DMC and EMC, purchased from Shenzhen Xinzhoubang Technology Co., Ltd.) is added using a pipette; then, a copper foil electrode coated with the negative electrode material prepared in this invention is placed in the center of the separator; then, a spacer is placed on the electrode and aligned precisely; then, a spring is placed on the spacer, again ensuring alignment; then, the positive electrode shell is placed on the spring using tweezers; finally, the entire battery assembly is clamped with insulated tweezers and placed with the negative electrode facing downwards into the packaging machine for pressing and sealing; after assembly, the experimental materials are tidied up, and the battery is removed from the chamber.

[0121] Finally, the positive electrode shell is snapped onto the negative electrode shell, and appropriate pressure is applied using a sealing machine or manual pressing tool to make the upper and lower shells fit tightly together, forming a sealed button lithium battery.

[0122] Throughout the assembly process, insulated tweezers are used to handle each component, and direct contact between the positive and negative electrode materials is strictly prohibited to avoid short circuits. Simultaneously, the entire process is conducted under an inert atmosphere to prevent lithium metal oxidation or reaction with moisture, which could lead to safety hazards. This assembly process closely integrates with the high-efficiency SiO-based negative electrode material prepared in this invention, ensuring the integrity of the battery structure and consistency of electrochemical performance, providing reliable samples for subsequent testing.

[0123] Figure 1 The specific capacity-voltage curve of a button lithium battery prepared using Example 1 (100% SiO) as the negative electrode material after 69 cycles.

[0124] Figure 2The graphs show the formation curves of button lithium batteries using SiO composites with different proportions of microcrystalline graphite as the negative electrode material in Examples 2-5 of this invention. As can be seen from the figures, pure SiO (100% SiO) exhibits significant irreversible capacity loss in the initial charging phase. This corresponds to the irreversible reaction caused by the formation of the SEI film and structural reconstruction during lithium-ion intercalation, manifested as a rapid increase in current accompanied by significant capacity decay in the initial stage. However, when 5%, 10%, 15%, and 20% microcrystalline graphite are added, the initial charging curves gradually flatten out, especially in the low-capacity region where the current response is more stable. This indicates that the composite material forms a more stable and dense SEI film during the first cycle, effectively suppressing excessive electrolyte decomposition and thus reducing irreversible lithium loss. Furthermore, with the increase of microcrystalline graphite content, the initial discharge capacity gradually increases, and the plateau region lengthens, indicating that the composite system enhances electronic conductivity and lithium-ion transport kinetics, improving the rate performance and cycle stability of the electrode. The curves for SiO+20% MG and SiO+10% MG showed excellent overall performance: while maintaining a high reversible capacity, the initial coulombic efficiency was significantly higher than that of the pure SiO system, indicating that the introduction of microcrystalline graphite not only improved the initial efficiency but also optimized the electrochemical reaction pathway. The positive regulatory effect of the microcrystalline graphite-SiO composite on the initial efficiency of the anode material is as follows: the appropriate addition of microcrystalline graphite can effectively alleviate the volume expansion of SiO, enhance the conductive network, and promote the formation of a uniform SEI film, thereby achieving higher initial charge-discharge efficiency and more stable cycle performance, verifying the effectiveness of the technical route of this invention to optimize battery performance by controlling the composite ratio.

[0125] Figure 3The figure shows the cycle performance curves of button lithium batteries using SiO composites with different proportions of microcrystalline graphite as the negative electrode material in Examples 2-5 of this invention. As can be seen from the figure, the capacity of pure SiO (100% SiO) rapidly decreases in the first few cycles, reaching approximately 20 mAh / g by cycle 50. This indicates that during cycling, the drastic volume expansion and contraction leads to particle pulverization, repeated breakage and reconstruction of the SEI film, resulting in active material shedding and electrode structure damage, thus causing severe capacity decay. However, the introduction of microcrystalline graphite significantly improves cycle stability: SiO + 5% MG exhibits better capacity retention than pure SiO, and the decay rate slows down in the first 10 cycles; SiO + 10% MG, SiO + 15% MG, and SiO + 20% MG demonstrate even better cycle performance. SiO + 10% MG still maintains a specific capacity of approximately 150 mAh / g by cycle 50, while SiO + 20% MG shows good stability during long-term cycling, with capacity decay becoming more gradual. This indicates that the addition of microcrystalline graphite effectively buffers the volume change of SiO during charging and discharging, enhances the mechanical integrity of the electrode, and improves electron transport efficiency by providing a stable conductive network, thereby delaying the electrode failure process.

[0126] Figure 4 The graphs show the formation curves of button lithium batteries using SiO composites with different proportions of hard carbon as the negative electrode material in Examples 6-9 of this invention. As can be seen from the figures, pure SiO exhibits typical high irreversible capacity loss characteristics in the initial stage of the first charge. Its voltage curve rises rapidly in the low-capacity range, accompanied by significant current fluctuations, indicating severe electrolyte decomposition, uneven SEI film formation, and a large thickness, leading to the irreversible consumption of a large number of lithium ions. However, when 5%, 10%, and 15% hard carbon are introduced, the first charge curves gradually flatten out, especially in the 0–200 mAh / g range where the voltage plateau is more stable. This indicates that the addition of hard carbon effectively suppresses excessive electrolyte decomposition and promotes the formation of a denser and more stable SEI film, thereby reducing irreversible lithium loss. Furthermore, with the increase of hard carbon content, the initial discharge capacity gradually increases, and the discharge plateau lengthens, indicating that hard carbon not only improves the overall conductivity of the material but also improves the diffusion kinetics of lithium ions in the electrode. The curves for SiO + 10% hard carbon and SiO + 5% hard carbon showed the best first-cycle efficiency: while maintaining a high reversible capacity, the first-cycle coulombic efficiency was significantly higher than that of the pure SiO system. This indicates that hard carbon, as a buffer phase and conductive network enhancer, can effectively alleviate the volume expansion of SiO, reduce stress concentration, and promote the coordinated transport of electrons and ions. In summary, the appropriate addition of hard carbon not only improves the first-cycle charge-discharge efficiency but also optimizes the electrochemical reaction pathway, verifying the effectiveness of the technical route of this invention to achieve high-performance anode materials by controlling the ratio of SiO to hard carbon.

[0127] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A negative electrode material, characterized in that, Including the following raw materials: Silicon suboxide, active components, binders, and conductive agents; The active component is hard carbon; The active component comprises 5-10% of the total mass of the silicon suboxide and the active component. The method for preparing the negative electrode material includes the following steps: Silica and active components are dissolved in a solvent, a conductive agent is added and mixed, and then the mixture is ball-milled and dispersed. A binder is then added and ball-milling is continued to obtain a uniform slurry. The slurry is coated onto copper foil, dried, and rolled to obtain the negative electrode material. The binder is an aqueous solution of polyacrylic acid, and the conductive agent is carbon black.

2. The negative electrode material according to claim 1, characterized in that, The active component is 5% or 10% of the total mass of the silicon suboxide and the active component.

3. The negative electrode material according to claim 1, characterized in that, The mass ratio of silicon suboxide, active component, binder and conductive agent is (5.4-5.7):(0.3-0.6):2:

2.

4. The negative electrode material according to claim 1, characterized in that, The mass concentration of the polyacrylic acid aqueous solution is 6%.

5. A method for preparing a negative electrode material as described in any one of claims 1-4, characterized in that, Includes the following steps: Silicon suboxide and active components are dissolved in a solvent, a conductive agent is added and mixed, and then the mixture is ball-milled and dispersed. A binder is then added and ball-milling is continued to obtain a uniform slurry. The slurry is coated onto copper foil, and after drying and rolling, the negative electrode material is obtained.

6. The method for preparing the negative electrode material according to claim 5, characterized in that, The dissolution process is as follows: the silicon suboxide and the active component are mixed evenly to obtain a mixture, and then deionized water and anhydrous ethanol are added in sequence, and the mixture is shaken to dissolve it completely.

7. The method for preparing the negative electrode material according to claim 5, characterized in that, The ball milling dispersion conditions are: ball milling for 6-12 hours at a frequency of 14-16 Hz; and / or, The conditions for continued ball milling are: ball milling for 2 hours at a frequency of 14-16 Hz; and / or, The drying conditions are as follows: drying at 80°C until the solvent is completely removed.

8. The use of the negative electrode material as described in any one of claims 1-4 in the preparation of a button lithium-ion battery.

9. A button lithium-ion battery, characterized in that, Includes the negative electrode material as described in any one of claims 1-4.

Images