Preparation method of silicon-carbon lithium ion battery and lithium compound solid-state lithium battery

Abstract

The invention provides a preparation method of a silicon-carbon lithium ion battery and lithium compound solid-state lithium battery, and belongs to the technical field of new energy lithium battery preparation. Aiming at the problems of low energy density, short cycle life and easy thermal runaway of a conventional lithium ion battery and capacity loss caused by cyclic pulverization of a silicon material, the method comprises the following steps: adding 1-80% of silicon powder into a negative electrode base material to improve the energy density of a negative electrode, and spraying 0.1-800% of a lithium compound on a negative electrode plate to supplement cyclic lithium loss. And a solid gel electrolyte (low-temperature injection, normal-temperature infiltration and high-temperature curing) is matched to coat the pole piece. The prepared battery has significantly improved capacity and cycle life, can inhibit short-circuit thermal runaway, has high safety, and is suitable for new energy automobile power batteries, energy storage equipment and other scenes.

Description

Technical Field

[0001] This invention relates to the field of new energy lithium battery preparation technology, specifically to a method for preparing silicon-carbon lithium-ion batteries plus lithium compound solid-state lithium batteries. Background Technology

[0002] With the rapid development of China's new energy industry, the demand for lithium batteries in power batteries (such as new energy vehicles) and energy storage equipment (such as photovoltaic supporting energy storage) has increased significantly. However, existing conventional lithium-ion batteries have obvious technical shortcomings and are difficult to meet the needs of actual applications. On the one hand, conventional lithium batteries have low energy density, resulting in short driving time on a single charge and limited cycle life. After long-term use, the capacity decays quickly, increasing replacement costs. On the other hand, conventional lithium batteries use liquid electrolytes, which are prone to thermal runaway under abnormal conditions such as internal short circuits, overcharging, and compression, leading to safety accidents such as fires and combustion. Safety has become a key pain point.

[0003] Meanwhile, although it is known in the industry that silicon materials have a much higher specific capacity than graphite, theoretically which can improve battery energy density, silicon materials undergo approximately 300% volume expansion during lithium insertion / extraction cycling, leading to electrode structure collapse and pulverization, resulting in irreversible capacity loss. Furthermore, silicon powder is prone to failure upon contact with the current collector, and exposure to the electrolyte will form an additional SEI film, reducing initial charge / discharge efficiency. In addition, silicon materials themselves have weak lithium-ion conductivity and electrical conductivity, resulting in poor cycle performance under high-current charge / discharge. These problems limit the large-scale application of silicon materials in lithium batteries. Therefore, the industry urgently needs a lithium battery manufacturing technology that can balance high capacity, long cycle life, and high safety to replace conventional lithium-ion batteries. Summary of the Invention

[0004] The present invention aims to solve the problems mentioned in the background art by providing a method for preparing silicon-carbon lithium-ion batteries and lithium compound solid-state lithium batteries.

[0005] The specific technical solution is as follows:

[0006] A method for preparing a silicon-carbon lithium-ion battery plus a lithium compound solid-state lithium battery includes the following steps:

[0007] (1) Preparation of negative electrode sheet: Add silicon powder to the negative electrode substrate, wherein the mass ratio of silicon powder in the negative electrode substrate is 1%-80%, so that the energy density of the prepared negative electrode sheet reaches 380-3700mAh / g.

[0008] (2) Spraying lithium compound: Spraying lithium compound onto the surface of the negative electrode sheet prepared in step (1), wherein the amount of lithium compound sprayed is 0.1%-800% of the mass of the negative electrode sheet;

[0009] (3) Preparation of solid gel electrolyte: Mix the monomer liquid with the gel initiator to obtain a liquid solid gel electrolyte precursor;

[0010] (4) Electrolyte injection: At low temperature, the solid gel electrolyte precursor obtained in step (3) is injected into the battery casing containing the negative electrode sheet after step (2).

[0011] (5) Impregnation treatment: Place the battery injected with the solid gel electrolyte precursor in an environment of 15-25℃ to fully impregnate the core inside the battery with the solid gel electrolyte precursor.

[0012] (6) Curing treatment: The battery that has been impregnated is placed in an environment of 60-78°C, so that the monomer liquid in the solid gel electrolyte precursor reacts with the gel initiator to form a solid gel electrolyte in a gel state, and the solid gel electrolyte coats the negative electrode sheet.

[0013] By adding silicon powder to the negative electrode substrate, the high specific capacity of silicon can be utilized to improve the overall capacity of lithium batteries. Spraying lithium compounds onto the surface of the negative electrode sheet can compensate for the irreversible capacity loss caused by pulverization and other problems in silicon-carbon negative electrodes during cycling, thereby extending the cycle life of lithium batteries. The solid gel electrolyte is injected at low temperature, wetted at room temperature, and cured at high temperature. After curing, it can coat the electrode sheet. When a short circuit occurs inside the battery, it can seal and protect the short circuit point, preventing the short circuit point from contacting oxygen, thereby suppressing the short circuit thermal runaway of the battery and improving the safety performance of lithium batteries.

[0014] The lithium batteries prepared using this method have a capacity that is 25-70% higher than that of conventional lithium-ion batteries, a cycle life that is 2-10 times longer than that of conventional lithium-ion batteries, and when a short circuit occurs inside the battery, the solid gel electrolyte can seal and protect the short circuit point, preventing it from contacting oxygen and suppressing the battery's short-circuit thermal runaway.

[0015] In the above-mentioned method for preparing silicon-carbon lithium-ion batteries and lithium compound solid-state lithium batteries, in step (1), the mass ratio of silicon powder in the negative electrode substrate is 1%-50%.

[0016] By limiting the mass percentage of silicon powder in the negative electrode substrate to a narrower range, the high specific capacity of silicon material can be used to improve the capacity of the negative electrode sheet, while avoiding excessive volume expansion of the negative electrode sheet during cycling due to excessive silicon powder addition. This reduces the risk of electrode sheet structure collapse and pulverization, ensuring the stability of the negative electrode sheet structure, thereby making the capacity performance and cycle performance of lithium batteries more stable.

[0017] In the above-mentioned method for preparing silicon-carbon lithium-ion batteries and lithium compound solid-state lithium batteries, in step (1), the energy density of the prepared negative electrode sheet is 1000-3700 mAh / g. By limiting the energy density of the negative electrode sheet to a more specific range, it is possible to ensure that the negative electrode sheet has a high energy density to support the high capacity requirements of the lithium battery, while avoiding excessive volume effects of silicon material during cyclic lithium insertion / extraction due to excessively high energy density. This reduces the damage to the spatial stability of the negative electrode sheet matrix material, ensures the continuous and stable function of the negative electrode sheet, and thus allows the lithium battery to maintain stable high capacity performance.

[0018] In the above-mentioned method for preparing a silicon-carbon lithium-ion battery with lithium compound solid-state lithium battery, in step (2), the amount of lithium compound sprayed relative to the mass of the negative electrode sheet is 1%-500%. Limiting the amount of lithium compound sprayed within a more reasonable range can ensure that there is enough lithium compound to replenish the capacity loss of the silicon-carbon negative electrode during cycling, effectively extending the cycle life of the lithium battery. It can also avoid insufficient replenishment due to too little lithium compound spraying, or excessive spraying affecting the conductivity, ion conduction and compatibility with other components of the negative electrode sheet, thus ensuring the stability of the improved cycle performance of the lithium battery.

[0019] In the above-mentioned method for preparing a silicon-carbon lithium-ion battery plus a lithium compound solid-state lithium battery, in step (2), the lithium compound is at least one of lithium oxide, lithium carbonate, and lithium hydroxide. It is clear that the lithium compound is at least one of lithium oxide, lithium carbonate, and lithium hydroxide. This type of lithium compound has stable chemical properties and can stably release lithium elements during battery cycling, reliably replenishing the capacity loss of the silicon-carbon anode. Simultaneously, it does not introduce impurities or cause adverse chemical reactions that affect the internal environment of the battery, ensuring that the lithium compound continues to effectively replenish capacity loss and further stabilizing the cycle performance of the lithium battery.

[0020] In the above-mentioned method for preparing silicon-carbon lithium-ion batteries and lithium compound solid-state lithium batteries, in step (3), the mass fraction of the gel initiator in the solid gel electrolyte precursor is 0.5%-10%. Limiting the mass fraction of the gel initiator in the solid gel electrolyte precursor ensures that the amount of gel initiator is sufficient to promote the solidification reaction of the monomer liquid under high temperature conditions, forming a stable gel-state solid gel electrolyte. It also avoids insufficient solidification reaction due to insufficient initiator addition, or excessive addition leading to an overly brittle gel structure and affecting the ion conduction performance of the electrolyte. This ensures the formation effect and normal function of the solid gel electrolyte, and guarantees the safety and electrochemical performance of the lithium battery.

[0021] In the above-mentioned method for preparing silicon-carbon lithium-ion batteries and lithium compound solid-state lithium batteries, the temperature of the low-temperature state in step (4) is 0-10℃. Limiting the low-temperature state during electrolyte injection to a specific range allows the solid gel electrolyte precursor to maintain a good liquid state, facilitating smooth injection into the battery casing. Simultaneously, it avoids excessively high temperatures that could cause premature reaction of the gel initiator, preventing solidification of the electrolyte precursor during injection and ensuring sufficient electrolyte injection into the battery, thus laying the foundation for subsequent core wetting.

[0022] In the above-mentioned method for preparing silicon-carbon lithium-ion batteries and lithium compound solid-state lithium batteries, in step (5), the ambient temperature for the immersion treatment is 18-22℃. Limiting the ambient temperature for the immersion treatment to the room temperature range allows the core inside the battery to be fully and uniformly immersed in the solid gel electrolyte precursor. This prevents the immersion speed from being too slow or insufficient due to excessively low temperatures, and also prevents the electrolyte precursor from prematurely solidifying due to excessively high temperatures. This ensures that all parts of the core can fully contact the electrolyte precursor, preparing for the subsequent solidification to form a uniform gel electrolyte layer, and guaranteeing the normal functioning of the solid gel electrolyte.

[0023] In the above-mentioned method for preparing silicon-carbon lithium-ion batteries and lithium compound solid-state lithium batteries, in step (6), the ambient temperature for the curing treatment is 65-75℃. Limiting the ambient temperature for the curing treatment to a more optimal range allows the monomer liquid in the solid gel electrolyte precursor to undergo a sufficient and stable coagulation reaction with the gel initiator, forming a tightly structured and stable gel-state solid gel electrolyte. This better coats the electrode, and when a short circuit occurs inside the battery, it can more effectively seal and protect the short circuit point, further improving the effect of the solid gel electrolyte in suppressing battery short-circuit thermal runaway and enhancing the safety of the lithium battery.

[0024] The aforementioned method for preparing silicon-carbon lithium-ion batteries and lithium compound solid-state lithium batteries shows that the lithium batteries prepared using this method have a cycle life 5-10 times longer and a capacity 40-70% higher than conventional lithium-ion batteries. Further optimization of the cycle life and capacity improvements allows for more significant extensions in cycle life and capacity, enabling lithium batteries to support longer single-use periods in practical applications, reducing charging frequency, extending overall battery life, and decreasing the number of battery replacements. Combined with the safety features of solid gel electrolytes, this results in lithium batteries with superior overall performance in terms of high capacity, long cycle life, and high safety.

[0025] The present invention has the following beneficial effects:

[0026] 1. Significantly improved capacity performance: By adding silicon powder to the negative electrode and utilizing the high specific capacity characteristics of silicon materials, the overall capacity of lithium batteries can be greatly improved, which can meet the needs of long driving range of new energy vehicles and high energy storage of energy storage devices, reduce the charging frequency during a single use, and improve the user experience.

[0027] 2. Effectively extended cycle life: The lithium compound sprayed on the surface of the negative electrode can continuously replenish the capacity loss caused by the pulverization of silicon powder during cycles, reduce the consumption of active lithium, and suppress the occurrence of side reactions, thus significantly extending the cycle life of lithium batteries, reducing the frequency of battery replacement, and reducing maintenance costs in application scenarios (such as the battery replacement cost of energy storage power stations and the battery maintenance cost of new energy vehicles).

[0028] 3. Significantly improved safety performance: After low-temperature injection, room-temperature immersion, and high-temperature curing, the solid gel electrolyte can tightly coat the electrode sheets. In the event of a short circuit inside the battery, it can seal the short circuit point and isolate oxygen, effectively suppressing thermal runaway and avoiding safety accidents such as fire and combustion. This solves the safety pain points of conventional liquid electrolyte batteries and is suitable for scenarios with high safety requirements, such as power batteries and energy storage.

[0029] 4. Convenient and controllable preparation process: Silicon powder can be added to the negative electrode substrate by simple stirring without the need for complex equipment; the solid gel electrolyte adopts the "low temperature injection-high temperature curing" process, which is easy to operate, and the parameters of each step (such as the amount of silicon powder added, the amount of lithium compound sprayed, and the temperature) can be adjusted according to actual needs, which is convenient for large-scale production and suitable for industrial-grade lithium battery manufacturing scenarios. Attached Figure Description

[0030] Figure 1 A flowchart illustrating the preparation method of a silicon-carbon lithium-ion battery plus a lithium compound solid-state lithium battery provided in this embodiment of the invention. Detailed Implementation

[0031] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0032] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual images. They should not be construed as limiting the scope of this application. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0033] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present application. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0034] In the description of this invention, unless otherwise explicitly specified and limited, the term "connection" or similar designation indicating a connection between components should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] Reference Figure 1 This specific implementation provides the following 5 examples.

[0036] Example 1

[0037] I. Detailed Implementation Steps

[0038] 1. Preparation of negative electrode sheet: Take graphite negative electrode substrate (purity 99.5%), add 10% by mass of silicon powder (particle size 50nm, purity 99.8%), add sodium carboxymethyl cellulose binder (2% by mass) and deionized water, stir in a planetary mixer at 300r / min for 2 hours to form a uniform negative electrode slurry; coat the slurry onto copper foil current collector (coating thickness 100μm), dry in an oven at 80℃ for 4 hours, roll press to obtain negative electrode sheet, and test its energy density is 1200mAh / g.

[0039] 2. Lithium compound spraying: Prepare an ethanol solution (5% mass concentration) of lithium oxide (99.9% purity) and spray it onto the surface of the above negative electrode sheet using an electrostatic spraying device. Control the amount of lithium compound sprayed relative to the mass ratio of the negative electrode sheet to 10%. After spraying, dry at 60°C for 30 minutes to remove the ethanol solvent.

[0040] 3. Preparation of solid gel electrolyte: Ethylene carbonate (EC) and dimethyl carbonate (DMC) were mixed at a volume ratio of 1:1 as monomer liquid, and 3% by mass of azobisisobutyronitrile (AIBN) was added as gel initiator. The mixture was stirred at 200 r / min for 15 minutes under nitrogen protection to obtain a clear and transparent solid gel electrolyte precursor.

[0041] 4. Electrolyte injection, wetting, and curing: The negative electrode sheet and ternary positive electrode (LiNi) prepared as described above are then injected into the electrolyte solution. 0.6 Co 0.2 Mn 0.2 The button cell battery casing (CR2032) containing O2 and a separator (polypropylene / polyethylene composite separator) is placed in a low-temperature environment of 8°C and a solid gel electrolyte precursor is injected (50 μL). The battery is then transferred to a constant temperature environment of 20°C and left to stand for 4 hours to allow the core to be fully immersed in and absorb the electrolyte precursor. Finally, the battery is placed in a constant temperature chamber of 70°C and kept at that temperature for 2 hours to allow the electrolyte precursor to solidify and form a solid gel electrolyte, thus completing the lithium battery preparation.

[0042] II. Working Principle

[0043] 1. Capacity Enhancement Principle: Silicon powder has a much higher specific capacity than graphite. Adding 10% silicon powder to the negative electrode substrate can significantly improve the energy density of the negative electrode sheet, thereby driving the overall capacity improvement of the lithium battery. Compared with pure graphite negative electrodes, the introduction of silicon powder can provide more active sites for lithium insertion and extraction in lithium batteries, increasing the amount of lithium migration during a single charge and discharge cycle.

[0044] 2. Cycle life extension principle: Silicon powder undergoes volume expansion (approximately 300%) during lithium insertion / extraction cycling, leading to electrode pulverization, structural collapse, and irreversible capacity loss. Lithium oxide is sprayed onto the surface of the negative electrode. During battery cycling, lithium oxide slowly releases lithium ions, replenishing the lithium loss caused by silicon powder pulverization, reducing the consumption of active lithium, and thus extending the battery cycle life.

[0045] 3. Safety Performance Enhancement Principle: The solid gel electrolyte precursor remains liquid at a low temperature of 8℃, which facilitates full injection into the battery casing and penetration into the gap between the separator and the electrode; 20℃ room temperature immersion ensures that all parts of the core can absorb electrolyte, avoiding local liquid shortage; at a high temperature of 70℃, AIBN initiates monomer liquid polymerization and solidification to form a gel. The gel tightly covers the electrode and separator. When a short circuit occurs inside the battery, the gel can seal the short circuit point, isolate oxygen, prevent the temperature of the short circuit point from rising sharply, and suppress thermal runaway.

[0046] III. Experimental Data

[0047] 1. Capacity performance test: The battery was charged and discharged at a rate of 0.5C under a 25℃ environment. The initial discharge capacity of a conventional pure graphite negative electrode lithium-ion battery is 1500mAh, while the initial discharge capacity of the battery in this embodiment is 2100mAh. In the cycle test, the capacity retention rate of a conventional battery is 60% after 500 cycles, while the capacity retention rate of the battery in this embodiment is 80% after 1000 cycles.

[0048] 2. Safety performance test: A needle penetration test (steel needle diameter 3mm, penetration speed 5mm / s) was conducted. Conventional lithium-ion batteries caught fire and burned within 30 seconds after being punctured, with the battery surface temperature rising to 280℃. The battery in this embodiment did not catch fire or emit smoke after being punctured, and the highest surface temperature of the battery was 80℃. In the short circuit test (external short circuit resistance 0.1Ω), conventional batteries emitted smoke within 5 seconds after being short-circuited. The battery in this embodiment showed no abnormal phenomena after being short-circuited, and the short circuit current was maintained stably for 10 seconds before gradually decreasing.

[0049] 3. Electrolyte performance test: The ionic conductivity of the cured solid gel electrolyte is 1.2 × 10⁻⁶. -3 S / cm (25℃), tensile strength is 0.8MPa, and there is no obvious swelling or decomposition after being placed at 60℃ for 72 hours.

[0050] IV. Technical Effects

[0051] 1. Capacity performance: By adding silicon powder to the negative electrode, the high specific capacity of silicon is utilized to significantly improve the overall capacity of the lithium battery, which can meet the device's demand for long battery life and reduce the charging frequency during a single use.

[0052] 2. Cyclic performance: By leveraging the compensating effect of lithium compounds on the capacity loss of silicon powder during cycling, the number of cycles of lithium batteries is effectively extended, reducing the frequency of battery replacement due to rapid capacity decay and lowering usage costs.

[0053] 3. Safety performance: The coating structure formed after the solid gel electrolyte solidifies can effectively isolate oxygen and suppress thermal runaway when the battery is short-circuited, avoiding safety accidents such as fire and combustion, and improving the safety of lithium batteries in daily use and abnormal operating conditions.

[0054] 4. Electrolyte stability: Solid gel electrolyte has good ionic conductivity and mechanical strength, which can stably maintain ion transport inside the battery. At the same time, it is not easy to decompose at high temperatures, ensuring long-term stable operation of the battery.

[0055] Example 2

[0056] I. Detailed Implementation Steps

[0057] 1. Preparation of negative electrode sheet: Take graphite negative electrode substrate, add 30% by mass of silicon powder (particle size 80nm), add styrene-butadiene rubber (SBR) binder (1.5% by mass) and deionized water, stir for 3 hours to form negative electrode slurry; coat it on copper foil (coating thickness 120μm), dry at 90℃ for 5 hours, roll press to obtain negative electrode sheet with energy density of 2000mAh / g.

[0058] 2. Lithium compound spraying: Prepare an isopropanol solution (8% mass concentration) of lithium carbonate (99.9% purity), and spray it onto the surface of the negative electrode using an air spraying device. Control the amount of lithium compound sprayed relative to the mass ratio of the negative electrode to 50%, and dry at 70°C for 40 minutes after spraying.

[0059] 3. Preparation of solid gel electrolyte: propylene carbonate (PC) and ethyl methyl carbonate (EMC) were mixed at a volume ratio of 2:1 as monomer liquid, and 5% by mass of benzoyl peroxide (BPO) was added as gel initiator. The mixture was stirred for 20 minutes under nitrogen protection to obtain the electrolyte precursor.

[0060] 4. Electrolyte injection, wetting, and curing: The battery casing was placed in a low-temperature environment of 5°C and the electrolyte precursor was injected (60 μL); it was then transferred to a constant temperature environment of 22°C and left to stand for 5 hours to complete the wetting; subsequently, it was placed in a constant temperature oven of 68°C for 2.5 hours to complete the curing, and the lithium battery was prepared.

[0061] II. Working Principle

[0062] 1. Principle of silicon powder addition control: The silicon powder mass ratio of 30% is within the range of 1%-50% as defined in claim 2. This can improve the energy density of the negative electrode through the high specific capacity of silicon, and avoid excessive volume expansion of the electrode caused by excessive silicon powder addition. Excessive silicon powder will cause severe mechanical stress in the electrode during cycling, causing the current collector to detach from the active material. The addition of 30% can control the volume expansion rate within a reasonable range and ensure the stability of the electrode structure.

[0063] 2. Lithium carbonate replenishment principle: Lithium carbonate has stable chemical properties. Compared with other lithium compounds, its lithium ion release rate is more gradual during battery cycling. It can continuously replenish the lithium source for capacity loss caused by silicon powder pulverization, avoid initial capacity fluctuations caused by excessively rapid lithium ion release, and at the same time, it will not have side reactions with electrolyte or electrodes, ensuring the stability of the battery's internal environment.

[0064] 3. Electrolyte curing principle: BPO, as a gel initiator, can efficiently initiate the polymerization of PC and EMC at 68℃ to form a gel network with a moderate degree of cross-linking. This gel network can not only encapsulate the lithium salt (LiPF6) in the electrolyte to ensure unobstructed ion transport channels, but also tightly adhere to the electrode surface to form a continuous coating layer, thereby improving battery safety performance.

[0065] III. Experimental Data

[0066] 1. Cyclic and volume expansion test: Charge and discharge at 0.5C at 25℃. The initial capacity of the battery in this embodiment is 2500mAh. After 1200 cycles, the capacity retention rate is 78%. The volume expansion rate of the electrode after 1000 cycles was detected by a laser thickness gauge. The expansion rate of the electrode in this embodiment is 80%, while the expansion rate of the control sample electrode with 50% silicon powder is 150%.

[0067] 2. Safety tests: Overcharge test (charging voltage to 5V), conventional batteries catch fire within 1 minute after overcharging, while the battery in this embodiment only swells slightly after overcharging and does not catch fire; Compression test (compression force 10kN), conventional batteries rupture and burn after compression, while the battery in this embodiment does not leak or burn after compression.

[0068] 3. Electrolyte performance test: The ionic conductivity of the cured electrolyte is 1.0 × 10⁻⁶. -3 S / cm (25℃), after being placed at 70℃ for 100 hours, the conductivity retention rate is 90%, and there are no obvious decomposition products.

[0069] IV. Technical Effects

[0070] 1. Electrode structure stability: By controlling the amount of silicon powder added between 1% and 50%, excessive volume expansion during electrode cycling is effectively suppressed, preventing electrode structure collapse or detachment from the current collector, ensuring the long-term stable activity of the negative electrode, and providing structural support for battery cycle performance.

[0071] 2. Lithium replenishment stability: Using lithium carbonate as the lithium replenishment material, its smooth lithium-ion release characteristics can achieve continuous and stable capacity loss replenishment, avoiding initial capacity fluctuations or insufficient lithium replenishment in the later stages, and ensuring the stability of capacity output during battery cycling.

[0072] 3. Safety and electrolyte stability: The gel network formed after the electrolyte solidifies has both ion conductivity and structural stability. It can not only ensure the normal electrochemical performance of the battery, but also prevent thermal runaway under abnormal conditions such as overcharging and compression. At the same time, it is not easily decomposed at high temperatures, thus extending the battery's service life.

[0073] Example 3

[0074] I. Detailed Implementation Steps

[0075] 1. Preparation of negative electrode sheet: Take graphite negative electrode substrate, add 50% by mass of silicon powder (particle size 100nm), add sodium alginate binder (2.5% by mass) and deionized water, stir for 4 hours to form negative electrode slurry; coat it on copper foil (coating thickness 150μm), dry at 85℃ for 6 hours, and roll press to obtain negative electrode sheet with energy density of 2800mAh / g.

[0076] 2. Lithium compound spraying: Prepare a methanol solution (10% mass concentration) of lithium hydroxide (99.9% purity), and spray it onto the surface of the negative electrode sheet using a high-pressure airless spraying device. Control the amount of lithium compound sprayed relative to the mass ratio of the negative electrode sheet to 100%, and dry at 65°C for 50 minutes after spraying.

[0077] 3. Preparation of solid gel electrolyte: EC, DMC and EMC were mixed in a volume ratio of 1:1:1 as monomer liquid, and 8% by mass of azobisisoheptanenitrile (ABVN) was added as gel initiator. The mixture was stirred for 25 minutes under nitrogen protection to obtain electrolyte precursor.

[0078] 4. Electrolyte injection, wetting, and curing: The battery casing is placed in a low-temperature environment of 10℃ and the electrolyte precursor is injected (70μL); it is then transferred to a constant temperature environment of 18℃ and left to stand for 6 hours to complete the wetting; subsequently, it is placed in a constant temperature oven of 75℃ for 3 hours to complete the curing, and the lithium battery is prepared.

[0079] II. Working Principle

[0080] 1. Principle of lithium compound dosage: The amount of lithium compound sprayed is 100% within the range of 1%-500% as defined in claim 4. This dosage can match the capacity loss requirement of 50% silicon powder. The higher the amount of silicon powder added, the greater the capacity loss caused by cyclic pulverization. 100% lithium compound can provide sufficient lithium source to ensure that the lithium lost by silicon powder can be replenished in each cycle, and avoid rapid capacity decay in the later stage of the cycle due to insufficient lithium source.

[0081] 2. Initiator dosage principle: 8% ABVN initiator is within the range of 0.5%-10% as defined in claim 6. This dosage ensures that the monomer liquid polymerizes rapidly and fully at 75°C. Too little initiator will lead to incomplete polymerization, residual liquid components in the electrolyte, and affect safety. Too much initiator will lead to excessively fast polymerization, excessive cross-linking of the gel network, and reduced ionic conductivity. The 8% dosage can balance polymerization efficiency and gel performance.

[0082] 3. Working principle of lithium hydroxide: During the first charge of the battery, lithium hydroxide can react with trace amounts of moisture on the surface of the negative electrode to generate stable LiOH·H2O, while releasing lithium ions. This process not only eliminates the adverse effects of moisture on the battery, but also provides a lithium source for silicon powder recycling, achieving the dual function of "water removal + lithium replenishment" and improving battery stability.

[0083] III. Experimental Data

[0084] 1. Cyclic test: At 25℃ and 1C charge and discharge, the battery in this embodiment has an initial capacity of 3200mAh and a capacity retention rate of 75% after 1500 cycles; the control sample (lithium compound coating amount of 0.5%) has a capacity retention rate of only 40% after 500 cycles.

[0085] 2. Electrolyte performance test: The ionic conductivity of the cured electrolyte is 0.9 × 10⁻⁶. -3 The gel strength was 50% at 30 minutes (75℃) and the elongation at break was 50%. After being placed at 80℃ for 80 hours, the gel structure did not collapse and the conductivity was retained at 85%.

[0086] 3. Moisture content test: The internal moisture content of the battery was measured using a Karl Fischer moisture analyzer. The moisture content of the battery in this embodiment was 10 ppm, while the moisture content of the control sample (without lithium hydroxide coating) was 50 ppm.

[0087] IV. Technical Effects

[0088] 1. Cycle capacity stability: By matching the amount of silicon powder added with the amount of lithium compound (1%-500%), sufficient lithium source is provided for the high silicon content anode, effectively replenishing the capacity loss during the cycle, avoiding rapid capacity decline in the later stage of the cycle, and ensuring the capacity output of the battery during long-term use.

[0089] 2. Electrolyte polymerization effect: The 8% initiator dosage ensures that the electrolyte precursor is fully polymerized to form a gel structure with a moderate degree of cross-linking. This ensures smooth ion transport, good mechanical properties, avoids electrolyte leakage caused by gel rupture, and shortens the curing time, thus improving preparation efficiency.

[0090] 3. Battery internal environment stability: The "water removal + lithium replenishment" effect of lithium hydroxide not only eliminates the corrosion of electrodes and electrolyte by trace amounts of moisture inside the battery, but also replenishes the lithium source, providing dual protection for the stability of the battery internal environment, reducing the occurrence of side reactions, and further extending battery life.

[0091] Example 4

[0092] I. Detailed Implementation Steps

[0093] 1. Preparation of negative electrode sheet: Take graphite negative electrode substrate, add 20% by mass of silicon powder (particle size 60nm), add polyvinylidene fluoride (PVDF) binder (2% by mass) and N-methylpyrrolidone (NMP), stir for 2.5 hours to form negative electrode slurry; coat on copper foil (coating thickness 110μm), dry at 100℃ for 3 hours, roll press to obtain negative electrode sheet with energy density of 1500mAh / g.

[0094] 2. Lithium compound spraying: Prepare an ethanol solution (6% mass concentration) of lithium oxide and lithium carbonate mixed in a 1:1 mass ratio. Spray the solution onto the surface of the negative electrode using a centrifugal spraying device. Control the amount of lithium compound sprayed relative to the mass ratio of the negative electrode to 30%. Dry at 75°C for 35 minutes after spraying.

[0095] 3. Preparation of solid gel electrolyte: PC and DMC were mixed at a volume ratio of 1:2 as monomer liquid, and 6% by mass of dicumyl peroxide (DCP) was added as gel initiator. The mixture was stirred for 18 minutes under nitrogen protection to obtain electrolyte precursor.

[0096] 4. Electrolyte injection, wetting, and curing: The battery casing is placed in a low-temperature environment of 2°C (0-10°C as defined in claim 7), and an electrolyte precursor (55 μL) is injected; it is then transferred to a constant temperature environment of 25°C and left to stand for 4.5 hours to complete the wetting; subsequently, it is placed in a constant temperature oven at 72°C for 2.2 hours to complete the curing, and a lithium battery is prepared.

[0097] II. Working Principle

[0098] 1. Low-temperature injection principle: The low-temperature environment of 2℃ can keep the electrolyte precursor in a low-viscosity liquid state, which can facilitate rapid penetration into the micropores (pore diameter 0.1-1μm) of the separator and the pores of the electrode. This avoids premature decomposition of the initiator and local solidification of the precursor during the injection process due to excessively high temperature, and ensures that the electrolyte can uniformly fill all the gaps inside the battery.

[0099] 2. High-temperature curing principle: 72℃ is within the range of 65-75℃ as defined in claim 9. This temperature allows the DCP initiator to decompose efficiently and generate free radicals, which quickly initiate the polymerization of PC and DMC to form a dense and uniform gel layer. Compared with low-temperature curing at 60℃, 72℃ can shorten the curing time and form a tighter gel network with stronger coating of the electrode, which can more effectively isolate short circuit points and oxygen.

[0100] 3. Principle of mixed lithium compounds: Lithium oxide has a faster lithium replenishment rate, which can quickly replenish the capacity loss in the early cycle of the battery; lithium carbonate has a slower lithium replenishment rate, which can ensure the lithium source supply in the later cycle of the battery; when the two are mixed in a 1:1 ratio, a synergistic effect of "rapid lithium replenishment in the early stage + continuous lithium replenishment in the later stage" can be achieved, covering the capacity loss requirements of the entire cycle.

[0101] III. Experimental Data

[0102] 1. Wetting uniformity test: The distribution of electrolyte inside the battery was detected by X-ray fluorescence spectrometry. The electrolyte content deviation in each region of the battery in this embodiment was 5%, while the electrolyte content deviation in each region of the control sample (injected at 25°C) was 15%. In the cycle test, the capacity retention rate of the battery in this embodiment was 79% after 1100 cycles, while the capacity retention rate of the control sample was 65% after 1100 cycles.

[0103] 2. Safety test: Short circuit test (external resistance 0.05Ω), the surface temperature of the battery in this embodiment reached a maximum of 90°C after short circuit, and there was no smoke; the surface temperature of the control sample (cured at 60°C) rose to 150°C after short circuit, and slight smoke appeared.

[0104] 3. Curing time test: The battery in this embodiment was cured in 2.2 hours at 72°C, while the control sample (cured at 60°C) required 4 hours to complete curing.

[0105] IV. Technical Effects

[0106] 1. Electrolyte wetting uniformity: Low-temperature injection ensures that the electrolyte precursor fully and uniformly penetrates into all the gaps inside the battery, avoiding capacity unevenness or cycle performance differences caused by local lack of liquid, ensuring that the electrochemical reaction in all areas of the battery proceeds synchronously, and improving capacity output stability.

[0107] 2. Gel Coating and Safety: The dense gel layer formed by high-temperature curing at 65-75℃ has stronger coating properties for the electrode. Under abnormal operating conditions such as short circuits, it can more tightly seal the short circuit point, isolate oxygen, further suppress thermal runaway, and shorten the curing time, thereby improving the battery manufacturing efficiency.

[0108] 3. Lithium replenishment synergy: The combined use of lithium oxide and lithium carbonate achieves matching of lithium replenishment needs at different cycle stages, avoiding insufficient lithium replenishment in the early stage or interruption of lithium replenishment in the later stage, ensuring stable capacity throughout the battery cycle and extending cycle life.

[0109] Example 5

[0110] I. Detailed Implementation Steps

[0111] 1. Preparation of negative electrode sheet: Take graphite negative electrode substrate, add 40% by mass of silicon powder (particle size 70nm), add sodium carboxymethyl cellulose and SBR composite binder (total mass percentage 2.2%), add deionized water, stir for 3.5 hours to form negative electrode slurry; coat on copper foil (coating thickness 140μm), dry at 95℃ for 5 hours, roll press to obtain negative electrode sheet with energy density of 2500mAh / g.

[0112] 2. Lithium compound spraying: Prepare a methanol solution (9% mass concentration) by mixing lithium hydroxide and lithium carbonate at a mass ratio of 2:1. Spray the solution onto the surface of the negative electrode using a high-voltage electrostatic spraying device. Control the amount of lithium compound sprayed relative to the mass ratio of the negative electrode to 80%. After spraying, dry at 70°C for 45 minutes.

[0113] 3. Preparation of solid gel electrolyte: EC, PC and EMC were mixed in a volume ratio of 1:1:2 as monomer liquid, and 7% by mass of AIBN was added as gel initiator. The mixture was stirred for 22 minutes under nitrogen protection to obtain electrolyte precursor.

[0114] 4. Electrolyte injection, wetting, and curing: The battery casing is placed in a low-temperature environment of 6°C, and the electrolyte precursor is injected (65 μL); it is transferred to a constant temperature environment of 20°C (18-22°C as specified in claim 8) and left to stand for 5.5 hours to complete the wetting; then it is placed in a constant temperature oven of 70°C for 2.8 hours to complete the curing, and the lithium battery is prepared.

[0115] II. Working Principle

[0116] 1. Room temperature wetting principle: 20℃ is within the range of 18-22℃ as defined in claim 8. This temperature is the optimal wetting temperature for the electrolyte precursor. Below 18℃, the penetration rate of the precursor will be slowed down, resulting in insufficient wetting. Above 22℃, the initiator may decompose slightly, affecting the uniformity of subsequent curing. 20℃ allows the precursor to penetrate at a suitable rate, ensuring that each layer of electrode and diaphragm in the core can fully absorb the electrolyte, laying the foundation for the formation of a continuous gel layer in subsequent curing.

[0117] 2. Comprehensive performance optimization principle: By adjusting the amount of silicon powder added (40%), the amount of lithium compound (80%), the electrolyte composition and the immersion temperature, the synergistic optimization of each link is achieved: silicon powder provides a high capacity foundation, lithium compound matches the capacity loss of silicon powder, room temperature immersion ensures uniform distribution of electrolyte, and the gel layer after solidification ensures safety; the cooperation of each link makes the battery achieve better levels in capacity, cycle and safety performance, which meets the requirement of "better cycle and capacity improvement".

[0118] 3. Composite binder principle: Sodium carboxymethyl cellulose and SBR composite binder have both good adhesion and elasticity, which can buffer the mechanical stress generated by the cyclic expansion of silicon powder, avoid electrode cracking, and at the same time enhance the bonding force between the electrode and the current collector, further improving the structural stability of the electrode.

[0119] III. Experimental Data

[0120] 1. Cycling and capacity testing: At 25℃ and 0.8C charge and discharge, the battery in this embodiment has an initial capacity of 3000mAh and a capacity retention rate of 76% after 2000 cycles; the conventional battery has an initial capacity of 1800mAh and a capacity retention rate of 55% after 1000 cycles.

[0121] 2. Safety test: Needle penetration + short circuit combined test (short circuit immediately after needle penetration). In this embodiment, the battery did not catch fire or leak, and the surface temperature reached a maximum of 85°C. Conventional batteries catch fire immediately after needle penetration and short circuit, and the surface temperature rises to 300°C.

[0122] 3. Electrode adhesion test: The adhesion between the electrode and the current collector was tested using a tensile testing machine. The electrode adhesion in this embodiment was 15 N / m, while the electrode adhesion in the control sample (single PVDF adhesive) was 8 N / m. After 1500 cycles, the electrode in this embodiment did not crack, while the electrode in the control sample showed obvious cracks.

[0123] IV. Technical Effects

[0124] 1. Adequate wetting and consistent performance: Wetting at room temperature of 18-22℃ ensures that the electrolyte precursor fully penetrates into each layer of the core, avoiding local capacity decay or cycle differences caused by insufficient wetting, ensuring consistent performance throughout the battery's life cycle, and providing a basis for optimizing capacity and cycle performance.

[0125] 2. Enhanced overall performance: Through synergistic optimization of each manufacturing process, the battery achieves superior performance in terms of capacity and cycle life, supporting longer single-use time (reduced charging frequency) and longer overall lifespan (reduced replacement frequency). Combined with the safety assurance of gel electrolyte, the battery's comprehensive performance of high capacity, long cycle life, and high safety makes it more suitable for the needs of new energy vehicles, energy storage and other scenarios.

[0126] 3. Electrode structure durability: The composite binder buffers the expansion stress of silicon powder, enhances the adhesion between the electrode and the current collector, prevents the electrode from cracking or falling off, further ensures the long-term activity of the negative electrode, and provides additional structural support for extending cycle life.

[0127] Specifically, in the preparation method of silicon-carbon lithium-ion batteries plus lithium compound solid-state lithium batteries, the amount of lithium compound sprayed in step (2) is m comp (Unit: mg) is determined by the following formula:

[0128]

[0129] in:

[0130] m Si The mass (mg) of silicon powder in the negative electrode depends on the formulation;

[0131] ε vThe volume expansion rate of silicon powder during charging and discharging (values ​​range from 2.5 to 3.5);

[0132] M Li The molar mass of lithium is 6.94 g / mol.

[0133] M Si The molar mass of silicon is 28.09 g / mol.

[0134] ρ Li This refers to the mass fraction of lithium in a lithium compound, which varies depending on the type of compound (e.g., 0.464 for Li₂O, 0.188 for Li₂CO₃, and 0.291 for LiOH).

[0135] η is the compensation efficiency coefficient, ranging from 1.2 to 2.0, used to cover irreversible losses and side reaction consumption.

[0136] Equation derivation process

[0137] This equation is derived based on the following assumptions and principles:

[0138] 1. Lithium loss due to silicon powder volume expansion: Silicon expands by about 300% during lithium intercalation, causing some active lithium to be isolated in the broken SEI film or pulverized structure and unable to participate in subsequent cycles, resulting in irreversible capacity loss.

[0139] 2. Lithium compensation requirement: The amount of lithium lost per unit mass of silicon powder during cycling and the volume expansion rate ε. v Proportional, theoretically the mass of lithium that needs to be added is:

[0140]

[0141] 3. Lithium compounds provide the lithium source: The actual mass of lithium that can be provided by lithium compounds is:

[0142] m Li,comp =m comp ·ρ L i;

[0143] 4. Introduce a compensation efficiency coefficient η: Considering that some lithium may not be effectively utilized due to side reactions, uneven distribution, etc., η>1 is introduced to cover these losses.

[0144] Solving the above relationships, we get:

[0145]

[0146] Example

[0147] Taking Example 1 as an example:

[0148] m Si=10% × negative electrode mass = 10mg (assuming the total mass of the electrode is 100mg);

[0149] ε v =3.0;

[0150] ρ Li =0.464 (using lithium oxide);

[0151] η = 1.5;

[0152] Substitute into the formula:

[0153]

[0154] This means that approximately 10.8 mg of lithium oxide needs to be sprayed, which is consistent with the "10% mass ratio" in the example (10 mg when the electrode mass is 100 mg), verifying the practicality of the formula.

[0155] Technical effect

[0156] 1. Precise lithium replenishment: The amount of lithium compound sprayed is determined through theoretical calculations to avoid over- or under-coating and improve cycle life;

[0157] 2. High adaptability: It can be flexibly adjusted according to different silicon contents and lithium compound types;

[0158] 3. Improve consistency: Reduce battery performance differences caused by uneven lithium replenishment;

[0159] 4. Reduce costs: Avoid waste of lithium compounds and optimize material utilization efficiency.

[0160] Working principle flowchart

[0161] Silicon powder addition → volume expansion → lithium loss → calculation of required lithium replenishment → spraying lithium compound → slow lithium release during cycling → compensation for loss → extended lifespan.

[0162] This equation provides a theoretical basis and quantitative tool for the "lithium compensation" step in this invention, and has strong practicality and innovation.

[0163] In summary, the method for preparing silicon-carbon lithium-ion batteries with lithium compound solid-state lithium batteries provided in this embodiment solves the technical pain points of conventional lithium batteries and simple silicon-carbon batteries through a synergistic mechanism of "negative electrode optimization + lithium compound lithium replenishment + solid gel electrolyte protection". The working principle is as follows:

[0164] 1. High capacity achievement principle: Adding silicon powder to the negative electrode substrate utilizes the fact that silicon has a much higher specific capacity than graphite to increase the number of active sites on the negative electrode, thereby improving the overall energy density of the negative electrode and thus driving the capacity improvement of the entire lithium battery. Silicon powder provides more insertion and extraction channels for lithium ions, and can accommodate more lithium ions during a single charge and discharge cycle, fundamentally solving the problems of low energy density and short battery life of conventional lithium batteries.

[0165] 2. Long Cycle Life Principle: To address the issue of electrode pulverization and irreversible capacity loss caused by the volume expansion of silicon powder during cycling, lithium compounds (such as lithium oxide, lithium carbonate, and lithium hydroxide) are sprayed onto the surface of the negative electrode. During battery cycling, the lithium compounds slowly release lithium ions to replenish the active lithium lost due to silicon powder pulverization, reducing the consumption of active lithium. Simultaneously, some lithium compounds (such as lithium hydroxide) can react with trace amounts of moisture on the negative electrode surface, eliminating moisture corrosion of the battery, further reducing capacity decay caused by side reactions, and extending battery cycle life.

[0166] 3. High Safety Protection Principle: Employing a solid-state gel electrolyte preparation logic of "low-temperature injection - room-temperature immersion - high-temperature curing": At low temperatures, the electrolyte precursor (monomer liquid + gel initiator) remains liquid, facilitating full injection into the battery casing and penetration into the pores of the separator and electrodes; at room temperature, the core can uniformly absorb the electrolyte precursor, avoiding localized liquid shortages; under high-temperature conditions, the monomer liquid in the precursor undergoes a solidification reaction with the initiator, forming a gel-like solid electrolyte that tightly coats the electrodes and separator. When a short circuit occurs inside the battery, the solid-state gel electrolyte can seal the short circuit point, isolate oxygen, and prevent a rapid increase in temperature at the short circuit point, suppressing thermal runaway from the source and resolving the safety hazards of conventional liquid electrolyte batteries.

[0167] How to use

[0168] The application of this method is divided into two parts: "battery manufacturing process" and "battery application scenarios," as detailed below:

[0169] (I) Battery Manufacturing Process

[0170] 1. Preparation of negative electrode sheet: Graphite is used as the basic negative electrode substrate, and silicon powder is added in proportion (1%-80% by mass). At the same time, binders (such as sodium carboxymethyl cellulose, styrene-butadiene rubber, etc.) and solvents (such as deionized water, N-methylpyrrolidone) are added and stirred to form a uniform negative electrode slurry. The slurry is coated on a copper foil current collector, and after drying (80-100℃) and rolling, a high energy density negative electrode sheet is obtained.

[0171] 2. Lithium compound spraying: Dissolve lithium compounds (such as lithium oxide, lithium carbonate, etc.) in organic solvents (such as ethanol, methanol) to prepare a spraying solution; use spraying equipment (such as electrostatic spraying, air spraying) to uniformly spray the solution onto the surface of the negative electrode sheet, control the spraying amount (0.1%-800% of the mass of the negative electrode sheet), and remove the solvent by low-temperature drying (60-75℃) after spraying to complete the negative electrode sheet treatment.

[0172] 3. Preparation and injection of solid gel electrolyte: Mix monomeric liquids (such as ethylene carbonate, dimethyl carbonate, etc.) with gel initiators (such as azobisisobutyronitrile, benzoyl peroxide, etc.) in a certain proportion and stir under nitrogen protection to form a transparent electrolyte precursor; place the battery case containing the treated negative electrode, positive electrode (such as ternary positive electrode), and separator in a low temperature environment (0-10℃) and inject the electrolyte precursor.

[0173] 4. Impregnation and curing: Transfer the battery with the injected precursor to a room temperature environment (15-25℃, preferably 18-22℃) and let it stand for 4-6 hours to allow the core to be fully impregnated and absorbed by the precursor; then place the battery in a high temperature environment (60-78℃, preferably 65-75℃) and keep it at that temperature for 2-3 hours to allow the precursor to solidify and form a solid gel electrolyte, thus completing the lithium battery preparation.

[0174] (II) Battery Application Scenarios

[0175] The prepared lithium battery can be directly applied to scenarios such as power battery packs for new energy vehicles, energy storage modules for energy storage power stations, and power supplies for portable electronic devices. When in use, it can be connected to a charger in the conventional lithium battery charging method to achieve fast charging and discharging (due to the high capacity characteristics of the negative electrode, the battery life is longer after charging). During long-term cycle use, no additional maintenance is required, and the battery can maintain a stable capacity output. In case of abnormal conditions such as extrusion or short circuit, the protective effect of the solid gel electrolyte can prevent safety accidents and make it suitable for various harsh application environments.

[0176] Overall technical effect

[0177] This preparation method, through the synergistic design of various technical steps, specifically addresses the core pain points of conventional lithium batteries and silicon-carbon batteries. The overall technical effects are as follows:

[0178] 1. Significantly improved capacity performance: By adding silicon powder to the negative electrode and utilizing the high specific capacity characteristics of silicon materials, the overall capacity of lithium batteries can be greatly improved, which can meet the needs of long driving range of new energy vehicles and high energy storage of energy storage devices, reduce the charging frequency during a single use, and improve the user experience.

[0179] 2. Effectively extended cycle life: The lithium compound sprayed on the surface of the negative electrode can continuously replenish the capacity loss caused by the pulverization of silicon powder during cycles, reduce the consumption of active lithium, and suppress the occurrence of side reactions, thus significantly extending the cycle life of lithium batteries, reducing the frequency of battery replacement, and reducing maintenance costs in application scenarios (such as the battery replacement cost of energy storage power stations and the battery maintenance cost of new energy vehicles).

[0180] 3. Significantly improved safety performance: After low-temperature injection, room-temperature immersion, and high-temperature curing, the solid gel electrolyte can tightly coat the electrode sheets. In the event of a short circuit inside the battery, it can seal the short circuit point and isolate oxygen, effectively suppressing thermal runaway and avoiding safety accidents such as fire and combustion. This solves the safety pain points of conventional liquid electrolyte batteries and is suitable for scenarios with high safety requirements, such as power batteries and energy storage.

[0181] 4. Convenient and controllable preparation process: Silicon powder can be added to the negative electrode substrate by simple stirring without the need for complex equipment; the solid gel electrolyte adopts the "low temperature injection-high temperature curing" process, which is easy to operate, and the parameters of each step (such as the amount of silicon powder added, the amount of lithium compound sprayed, and the temperature) can be adjusted according to actual needs, which is convenient for large-scale production and suitable for industrial-grade lithium battery manufacturing scenarios.

[0182] In summary, the lithium batteries prepared by this method have high capacity, long cycle life, and high safety characteristics, and can effectively replace conventional lithium-ion batteries, meeting the technical needs of new energy vehicles, energy storage, photovoltaic supporting industries, and other fields, and promoting the further development of the new energy industry.

[0183] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a silicon-carbon lithium-ion battery plus a lithium compound solid-state lithium battery, characterized in that, Includes the following steps: (1) Preparation of negative electrode sheet: Add silicon powder to the negative electrode substrate, wherein the mass ratio of silicon powder in the negative electrode substrate is 1%-80%, so that the energy density of the prepared negative electrode sheet reaches 380-3700mAh / g. (2) Spraying lithium compound: Spraying lithium compound onto the surface of the negative electrode sheet prepared in step (1), wherein the amount of lithium compound sprayed is 0.1%-800% of the mass of the negative electrode sheet; (3) Preparation of solid gel electrolyte: Mix the monomer liquid with the gel initiator to obtain a liquid solid gel electrolyte precursor; (4) Electrolyte injection: At low temperature, the solid gel electrolyte precursor obtained in step (3) is injected into the battery casing containing the negative electrode sheet after step (2). (5) Impregnation treatment: Place the battery injected with the solid gel electrolyte precursor in an environment of 15-25℃ to fully impregnate the core inside the battery with the solid gel electrolyte precursor. (6) Curing treatment: The battery that has been impregnated is placed in an environment of 60-78°C, so that the monomer liquid in the solid gel electrolyte precursor reacts with the gel initiator to form a solid gel electrolyte in a gel state, and the solid gel electrolyte coats the negative electrode sheet.

2. The method for preparing a silicon-carbon lithium-ion battery plus a lithium compound solid-state lithium battery according to claim 1, characterized in that, In step (1), the silicon powder accounts for 1%-50% of the mass of the negative electrode substrate.

3. The method for preparing a silicon-carbon lithium-ion battery plus a lithium compound solid-state lithium battery according to claim 1 or 2, characterized in that, In step (1), the energy density of the negative electrode sheet prepared is 1000-3700mAh / g.

4. The method for preparing a silicon-carbon lithium-ion battery plus a lithium compound solid-state lithium battery according to claim 1, characterized in that, In step (2), the amount of lithium compound sprayed is 1%-500% of the mass of the negative electrode sheet.

5. The method for preparing a silicon-carbon lithium-ion battery plus a lithium compound solid-state lithium battery according to claim 1 or 4, characterized in that, In step (2), the lithium compound is at least one of lithium oxide, lithium carbonate, and lithium hydroxide.

6. The method for preparing a silicon-carbon lithium-ion battery plus a lithium compound solid-state lithium battery according to claim 1, characterized in that, In step (3), the mass fraction of the gel initiator in the solid gel electrolyte precursor is 0.5%-10%.

7. The method for preparing a silicon-carbon lithium-ion battery plus a lithium compound solid-state lithium battery according to claim 1, characterized in that, In step (4), the temperature of the low-temperature state is 0-10℃.

8. The method for preparing a silicon-carbon lithium-ion battery plus a lithium compound solid-state lithium battery according to claim 1, characterized in that, In step (5), the ambient temperature for the immersion treatment is 18-22℃.

9. The method for preparing a silicon-carbon lithium-ion battery plus a lithium compound solid-state lithium battery according to claim 1, characterized in that, In step (6), the ambient temperature for the curing process is 65-75℃.

10. The method for preparing a silicon-carbon lithium-ion battery plus a lithium compound solid-state lithium battery according to claim 1, characterized in that, The lithium batteries prepared using this method have a cycle life that is 5-10 times longer than conventional lithium-ion batteries, and a capacity that is 40-70% higher than conventional lithium-ion batteries.

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