A functional current collector for inhibiting lithium dendrites, a preparation method thereof, a pole piece, and a battery

Abstract

The application discloses a functional current collector for inhibiting lithium dendrites, a preparation method thereof, a pole piece and a battery, and comprises a polydimethylsiloxane-based film layer located in the middle layer of the functional current collector; Li + -Nafion ion homogenization layer, which is coated on the polydimethylsiloxane-based film layer; a 3D Cu@Sn lithiumophilic metal layer, which is arranged on the surface of the Li + -Nafion ion homogenization layer; the 3D Cu@Sn lithiumophilic metal layer is a Cu layer with a Cu nanocone surface, and Sn nanoparticles are coated on the Cu nanocone. The composite current collector structure of the application has the advantages of the three-layer synergistic structure of the polydimethylsiloxane-based film layer, the Li + -Nafion ion homogenization layer and the 3D Cu@Sn lithiumophilic metal layer, and has significant advantages in inhibiting the growth of lithium dendrites and improving the safety and cycle stability of the battery.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a functional current collector for suppressing lithium dendrites, its preparation method, an electrode, and a battery. Background Technology

[0002] With the global energy structure transformation and the rapid iteration of the new energy vehicle industry, the performance and safety level of power batteries, as core energy supply components, directly determine the market competitiveness and application scope of new energy vehicles. Therefore, battery safety has always been a key focus of industry research and development, production, and application. During the long-term charging, discharging, and use of power batteries, lithium ions will deposit on the surface of the negative electrode. When the deposition process is uneven, needle-like or dendritic lithium dendrites will gradually form. These lithium dendrites have extremely strong piercing ability and can easily break through the internal separator structure of the battery. As a key isolation component between the positive and negative electrodes, the integrity of the separator is the core guarantee to avoid direct contact between the positive and negative electrodes and prevent internal short circuits. Once the separator is pierced by lithium dendrites, it will directly cause an internal short circuit in the battery, which will then induce serious safety accidents such as battery overheating, fire, or even explosion, seriously threatening the personal and property safety of users.

[0003] To address the safety hazards caused by lithium dendrites, the industry has conducted extensive technological research and development to achieve suppression. However, existing technologies still have many shortcomings and limitations, making it difficult to fundamentally solve the problem. Solid-state electrolytes (SSEs), due to their high mechanical strength, are considered one of the effective solutions for suppressing lithium dendrite penetration. However, they also have significant drawbacks: the presence of grain boundaries within SSEs disrupts the uniformity of ion transport. Even if they can block rapid penetration by lithium dendrites to some extent, differences in ion transport resistance at the grain boundaries can still lead to abnormal local growth of lithium dendrites, thus creating a short-circuit hazard. Simultaneously, the solid-solid interface formed between the SSE and the electrode has poor stability, and the uneven ion transport efficiency at the interface further exacerbates the uneven deposition of lithium ions on the negative electrode surface. This not only promotes the formation of lithium dendrites but also leads to faster battery capacity decay and shorter cycle life, doubly amplifying the battery's safety risks. Furthermore, the rigid current collectors used in existing power batteries, due to their rigid structure, cannot effectively release the volumetric and interfacial stresses generated during lithium-ion deposition. The accumulation of this stress accelerates the growth and penetration of lithium dendrites. More importantly, rigid current collectors cannot synchronously control the nucleation behavior of lithium ions on the negative electrode surface, and cannot guide the uniform nucleation and orderly deposition of lithium ions. This further exacerbates the safety hazards and performance degradation caused by lithium dendrites, and restricts the development of power batteries towards higher safety, higher capacity, and longer lifespan. Summary of the Invention

[0004] This invention aims to overcome the shortcomings of existing solid-state batteries, such as poor stress release of rigid current collectors, uneven lithium-ion deposition, and easy growth of lithium dendrites. It provides a method for preparing a multilayer composite current collector, which solves the problems of battery short circuits and capacity decay induced by lithium dendrites by combining flexible substrate, ion homogenization regulation and three-dimensional lithiophilic modification, thereby improving the safety and cycle stability of lithium metal batteries.

[0005] To achieve the above objectives, the technical solution provided by the present invention is as follows: The first aspect of this application provides a functional current collector for suppressing lithium dendrites, comprising: The polydimethylsiloxane film layer is located in the middle layer of the functional current collector; Li + -Nafion ion homogenization layer is coated on the polydimethylsiloxane film layer; A 3D Cu@Sn lithium-loving metal layer is disposed on the Li + - The surface of the Nafion ion homogenization layer; the 3DCu@Sn lithiophilic metal layer is a Cu layer with a Cu nanocone surface, and Sn nanoparticles are covered on ≥90% of the area of ​​the Cu nanocones.

[0006] To optimize the above technical solution, the specific measures / limitations also include: The Li + The thickness of the Nafion ion homogenization layer is 200~800 nm.

[0007] Furthermore, in the 3D Cu@Sn lithium-loving metal layer, the bottom of the Cu nanocone has a planar Cu layer of 5~50 nm, and the height of the Cu nanocone is 1~2 μm.

[0008] Furthermore, the particle size of the Sn nanoparticles is 50~100nm; the thickness of the Sn nanoparticle coating layer covering ≥90% of the area of ​​the Cu nanocone is 100~300nm.

[0009] The second aspect of this application provides a method for preparing a functional current collector that suppresses lithium dendrites, comprising the following steps: S1: Preparation of polydimethylsiloxane membrane; S2: Li is sprayed onto the surface of the polydimethylsiloxane film. + -Nafion solution, dried, to obtain Li + -Nafion ion homogenization layer; S3: In the presence of Li + - A planar Cu layer is formed on the surface of the polydimethylsiloxane film of the Nafion ion homogenization layer by magnetron sputtering; S4: Cu nanocones are prepared by deposition on a planar Cu layer; S5: Sn nanoparticles are deposited on Cu nanocones to form a coating.

[0010] Step S1 involves preparing a polydimethylsiloxane membrane by mixing a polydimethylsiloxane prepolymer and a curing agent at a mass ratio of 9-11:1, degassing the mixture, coating it evenly onto a substrate, and then peeling it off from the substrate after thermal curing to obtain the polydimethylsiloxane membrane.

[0011] In step S2, Li + The concentration of the Nafion solution is 5-8 wt%, and it is sprayed continuously 3-5 times. The temperature of the polydimethylsiloxane film during spraying is 60-85℃. After spraying, it is dried at 110-130℃ for 50-70 minutes.

[0012] Step S4: Cu nanocones are electrodeposited on a planar Cu layer. The electrolyte contains CuSO4·5H2O, H2SO4, polyethylene glycol, and NaCl, and the current density is -30 to -50 mA / cm². 2 The deposition time is 600~1200s; in step S5, Sn nanoparticles are electrodeposited on Cu nanocones in an electroplating solution containing SnSO4 and H2SO4, with a current density of 4~6mA / cm. 2 The deposition time is 300~500s.

[0013] A third aspect of this application provides an electrode comprising the aforementioned functional current collector for suppressing lithium dendrites.

[0014] A fourth aspect of this application provides a battery comprising the aforementioned electrode.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This invention focuses on the core issues of safety hazards and performance degradation caused by lithium dendrite growth in the field of solid-state batteries. Through a multi-layered synergistic composite current collector structure, it achieves efficient suppression of lithium dendrites and comprehensively improves the overall performance of the battery. The technical effect is highly targeted and has outstanding advantages.

[0016] This solution uses flexible PDMS (polydimethylsiloxane) as the base film layer. By utilizing its excellent flexibility and elasticity, it can effectively buffer and release the stress generated during the deposition of metallic lithium. From a physical perspective, it avoids lithium dendrites puncturing the battery separator due to stress concentration, thereby improving the safety performance of the battery from the root and solving the technical defects of existing rigid current collectors that cannot release deposition stress and accelerate dendrite growth.

[0017] Li coated on the surface of PDMS base film +- The Nafion ion homogenization layer, prepared by ultrasonic spraying, can efficiently regulate the transport and distribution of lithium ions, effectively suppress the local aggregation of ion flow, and avoid the rapid deposition of lithium ions in local areas due to uneven distribution. This lays the foundation for uniform nucleation of lithium ions and alleviates the problem of lithium dendrite growth caused by the existence of grain boundaries and the instability of solid-solid interfaces in existing solid electrolytes. It achieves the suppression of lithium dendrites from the ion transport level.

[0018] A 3D Cu@Sn lithiophilic metal layer constructed on the surface of the ion homogenization layer was prepared by combining magnetron sputtering and electrodeposition processes to form a unique three-dimensional composite structure. The copper nanocones provided ample conductive pathways and nucleation sites, while the Sn nanoparticles deposited on the surface exhibited excellent lithiophilic properties, which could significantly reduce the lithium nucleation overpotential and guide lithium ions to uniformly nucleate and deposit in an orderly manner across the entire current collector surface. This completely avoided the phenomenon of excessive aggregation of lithium ions in local areas to form lithium dendrites, and further optimized the deposition behavior of lithium ions.

[0019] Among them, flexible PDMS base film, Li + The three-layer composite structure, consisting of a Nafion ion homogenization layer and a 3D Cu@Sn lithium-affinity metal layer, features complementary and synergistic functions across each layer, constructing a multi-dimensional lithium dendrite suppression system. The flexible PDMS substrate, relying on its own elasticity, releases lithium deposition stress, eliminating dendrite puncture induction caused by stress concentration and providing flexible and stable support for the overall structure. Li + The Nafion ion homogenization layer uniformly regulates lithium-ion transport distribution, preventing localized ion enrichment and avoiding lithium-ion segregation and deposition at the source. It also connects the upper and lower layers, ensuring stable interfacial bonding. The three-dimensional Cu@Sn lithiophilic metal layer, with its three-dimensional conductive framework and high lithiophilic properties, lowers the lithium nucleation barrier, guiding uniform and orderly lithium-ion nucleation and deposition across the entire domain. This three-layer structure works in synergy, combining physical stress mitigation, uniform ion flow regulation, and lithiophilic nucleation induction mechanisms to synergistically overcome the shortcomings of existing rigid current collectors and single modification schemes. It effectively inhibits lithium dendrite growth, improves interfacial stability, reduces battery capacity decay, and significantly enhances the safety and cycle durability of solid-state batteries.

[0020] In summary, PDMS base film, Li +The synergistic effect of the Nafion ion homogenization layer and the 3D Cu@Sn lithium-loving metal layer forms a closed loop from three dimensions: stress release, ion regulation, and nucleation induction. This comprehensively solves the core problem of lithium dendrite growth in existing technologies, effectively improving battery safety performance and avoiding safety hazards such as short circuits and fires caused by lithium dendrites. It also reduces battery capacity decay, significantly extends battery cycle life, and optimizes the long-term stability of the battery. This provides reliable technical support for the large-scale and safe application of solid-state batteries, achieving significant breakthroughs and improvements in performance and safety compared to existing current collector solutions. Detailed Implementation

[0021] The present invention will be further described in detail below through specific embodiments, but it should not be construed as limiting the scope of the subject matter of the present invention to the following embodiments. All technologies implemented based on the above content of the present invention fall within the scope of the present invention.

[0022] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the reagents, methods and equipment used are conventional reagents, methods and equipment in this technical field.

[0023] This invention provides a functional current collector for suppressing lithium dendrites, comprising: The polydimethylsiloxane film layer is located in the middle layer of the functional current collector; Li + -Nafion ion homogenization layer, coated on polydimethylsiloxane film; 3D Cu@Sn lithium-loving metal layer, set on Li + - The surface of the Nafion ion homogenization layer; the 3D Cu@Sn lithiophilic metal layer is a Cu layer with a Cu nanocone surface, and Sn nanoparticles are covered on ≥90% of the area of ​​the Cu nanocones.

[0024] This invention utilizes the excellent flexibility and elasticity of a polydimethylsiloxane film to release the stress generated during lithium metal deposition, thereby physically suppressing the risk of lithium dendrite puncture of the separator due to stress concentration and improving battery safety performance; Li +- The Nafion ion homogenization layer can uniformly guide lithium ion migration, avoid local aggregation of ion flow, and reduce the probability of excessive local deposition of lithium ions to form lithium dendrites. In the 3D Cu@Sn lithiophilic metal layer, Cu nanocones provide sufficient nucleation sites, and Sn nanoparticles have excellent lithiophilicity, which can significantly reduce the lithium nucleation overpotential and induce lithium ions to uniformly nucleate and deposit on the current collector surface. Through synergistic effect, lithium dendrite growth is comprehensively suppressed from three dimensions: stress release, ion regulation, and nucleation induction. At the same time, the capacity retention rate and cycle stability of the battery are improved, solving the problems of unstable solid-solid interface and inability to release stress in rigid current collectors in existing solid-state batteries.

[0025] In some implementations, Li + The thickness of the Nafion ion homogenization layer is 200~800 nm.

[0026] This thickness range ensures that the ion homogenization layer has sufficient lithium-ion conduction and homogenization capabilities, effectively suppressing local ion flow aggregation and avoiding lithium dendrite growth caused by uneven ion concentration. It also avoids the problems of excessive thickness increasing ion conduction resistance and reducing battery energy density, or insufficient thickness leading to inadequate homogenization and failure to effectively suppress lithium dendrites. This ensures that the ion homogenization layer forms a good interface with the base film layer and the lithium-loving metal layer, achieving a balance between ion homogenization function and overall battery performance.

[0027] In some embodiments, the bottom of the Cu nanocone has a planar Cu layer of 5-50 nm, and the height of the Cu nanocone is 1-2 μm.

[0028] A planar Cu layer of 5–50 nm serves as a good conductive pathway and electrodeposition nucleation site, ensuring the conductivity of the current collector and providing a stable substrate for the subsequent deposition of Cu nanocones and Sn nanoparticles. Cu nanocones with a height of 1–2 μm construct a 3D structure, which significantly increases the specific surface area of ​​the current collector, providing more nucleation sites for lithium ions and preventing excessive accumulation of lithium ions in local areas. This structural design not only solves the problems of insufficient nucleation sites and uneven lithium ion deposition in traditional planar current collectors, but also synergistically improves the conductivity and lithiophilicity of the current collector through the conductive support of the planar Cu layer and the three-dimensional structure of the nanocones, further suppressing the growth of lithium dendrites.

[0029] In some embodiments, the Sn nanoparticles have a particle size of 50-100 nm; the thickness of the Sn nanoparticle covering ≥90% of the area of ​​the Cu nanocone is 100-300 nm.

[0030] Sn nanoparticles within this size range possess a large specific surface area and excellent lithiophilicity, enabling them to fully adhere to the surface of Cu nanocones, forming a uniform lithiophilic coating. This effectively reduces the lithium nucleation overpotential and induces uniform lithium ion nucleation. Simultaneously, the Sn nanoparticles of this size avoid the increased surface roughness and localized ion aggregation caused by excessively large particle sizes, and also prevent insufficient lithiophilic performance and easy coating detachment caused by excessively small particle sizes. This ensures that the Sn nanoparticles can stably exert their lithiophilic induction effect, synergistically working with Cu nanocones to further optimize lithium ion deposition behavior and inhibit lithium dendrite growth. The high coverage and controllable thickness of the Sn nanoparticle coating significantly increase the number of lithiophilic active sites, effectively reducing the lithium nucleation overpotential. Simultaneously, the uniform coating of the Cu nanocone surface optimizes interfacial conductivity and lithium ion adsorption capacity, further regulating lithium deposition behavior and fundamentally inhibiting localized lithium enrichment and dendrite growth.

[0031] This invention also provides a method for preparing a functional current collector that suppresses lithium dendrites, comprising the following steps: S1: Preparation of polydimethylsiloxane membrane; S2: Li is sprayed onto the surface of the polydimethylsiloxane film. + -Nafion solution (lithium-modified perfluorosulfonic acid resin dispersion), dried, to obtain Li + -Nafion ion homogenization layer; S3: In the presence of Li + - A planar Cu layer is formed on the surface of the polydimethylsiloxane film of the Nafion ion homogenization layer by magnetron sputtering; S4: Cu nanocones are prepared by deposition on a planar Cu layer; S5: Sn nanoparticles are deposited on Cu nanocones to form a coating.

[0032] Step S1 involves preparing a polydimethylsiloxane membrane by mixing a polydimethylsiloxane prepolymer and a curing agent at a mass ratio of 9-11:1, degassing the mixture, coating it evenly onto a substrate, and then peeling it off from the substrate after thermal curing to obtain the polydimethylsiloxane membrane.

[0033] The curing agent can be a composite curing agent containing hydrogen-containing silicone oil, platinum catalyst, alkynyl alcohol inhibitor (such as 1-ethynyl-1-cyclohexanol) and silica.

[0034] Controlling the mass ratio of polydimethylsiloxane prepolymer to curing agent to 9~11:1 ensures that the base film layer has excellent flexibility and elasticity, effectively releasing lithium deposition stress. The degassing, coating, and thermal curing process steps can avoid defects such as bubbles and cracks in the base film layer, ensuring the flatness and structural integrity of the base film layer, and providing a good substrate for the subsequent deposition of ion homogenization layer and metal layer.

[0035] In step S2, Li+ The concentration of the Nafion solution is 5-8 wt%, and it is sprayed continuously 3-5 times. The temperature of the polydimethylsiloxane film during spraying is 60-85℃. After spraying, it is dried at 110-130℃ for 50-70 minutes.

[0036] Step S4: Cu nanocones are electrodeposited on a planar Cu layer. The electrolyte contains CuSO4·5H2O, H2SO4, polyethylene glycol, and NaCl, and the current density is -30 to -50 mA / cm². 2 The deposition time is 600~1200s; in step S5, Sn nanoparticles are electrodeposited on Cu nanocones in an electroplating solution containing SnSO4 and H2SO4, with a current density of 4~6mA / cm. 2 The deposition time was 300-500 seconds. PEG and Cl were used. - The compounded copper sulfate electrolyte system can controllably grow copper needle-cone morphology with nanotwin characteristics.

[0037] The present invention also provides an electrode comprising the above-described current collector for suppressing lithium dendrites.

[0038] The present invention also provides a battery comprising the above-described electrode.

[0039] Applying the composite current collector with lithium dendrite suppression function of this invention to the electrode sheet enables the electrode sheet to possess excellent lithium affinity, ion homogenization ability, and stress release capability. It effectively solves the problems of lithium dendrite growth and capacity decay caused by uneven lithium ion deposition in traditional electrodes, ensuring that the electrode sheet maintains structural stability during cycling and avoiding potential hazards such as electrode sheet damage and short circuits caused by lithium dendrites. This lays the core foundation for high battery safety and high cycle stability, and is suitable for the electrode preparation needs of various lithium-ion batteries such as power batteries and energy storage batteries. It enables the battery to completely solve the safety hazards and performance decay problems caused by lithium dendrite growth at the core component level, effectively avoiding safety accidents such as internal short circuits and fires, while significantly improving the battery's cycle capacity retention rate and extending its service life.

[0040] The technical solution of the present invention will be further described in detail below with reference to specific embodiments: Example 1 Step S1: Preparation of polydimethylsiloxane membrane (PDMS-based membrane) The PDMS prepolymer and curing agent were mixed evenly at a mass ratio of 10:1 and placed in a vacuum drying oven for 30 minutes to degas the mixture. After removing the air bubbles, the mixture was evenly coated onto a clean and flat substrate. The coated PDMS base film was then placed in an 80°C oven for heat curing for 90 minutes. After complete curing, the film was peeled off from the substrate to obtain the PDMS base film. Step S2: Spraying Li +-Nafion Ion Homogenization Layer Li + - The Nafion solution was diluted to 6.5 wt% and filtered to remove particulate matter. Both sides of the PDMS base film were continuously sprayed four times each using a precision ultrasonic device, maintaining the PDMS base film temperature at 70-75℃ during spraying. After spraying, the sample was placed in a vacuum oven and dried at 120℃ for 60 min to obtain a Li film with a thickness of 500±30 nm. + -Nafion ion homogenization layer; Step S3: Prepare a planar Cu layer Using a magnetron sputtering coating machine, a high-purity copper target (99.99%+) was sputtered onto the above-mentioned Li-containing substrate. + Planar Cu layers with a single-sided thickness of 27-28 nm were prepared on both sides of the PDMS base film with a Nafion ion homogenization layer; sputtering parameters: vacuum <5×10 -4 The sputtering process was carried out at a pressure of 1.25 Pa, with a sputtering power of 125 W and a sputtering time of 155 s. During sputtering, the surface temperature of the substrate film was kept stable (room temperature ± 5 °C) to avoid high-temperature damage to Li. + -Nafion ion homogenization layer; Step S4: Electrodeposition of Cu nanocones Cu nanocones were electrodeposited on a planar Cu layer using an electrolyte consisting of CuSO4·5H2O (0.5 mol / L) + H2SO4 (1 mol / L) + 500 ppm polyethylene glycol (PEG) + 50 ppm NaCl, with the current density controlled at -40 mA / cm². 2 The deposition time was 900 s, the anode was a phosphor bronze plate (purity >99.9%), and a Cu nanocone array with a height of 1.5 μm was prepared. The electrolyte was continuously stirred during the electrodeposition process to ensure uniform ion concentration and avoid nanocone aggregation. Step S5: Electrodeposition of Sn nanoparticles Sn nanoparticles were electrodeposited onto Cu nanocones to form a coating. The electroplating solution was SnSO4 (0.3 mol / L) + H2SO4 (1.0 mol / L), and the current density was controlled at 5 mA / cm². 2 The deposition time was 400s, and the final Sn nanoparticle size was 75nm. ≥90% of the area on the Cu nanocone was covered by the Sn nanoparticle coating, with a coating thickness of 200nm. After electrodeposition, the sample surface was rinsed with deionized water to remove residual plating solution and avoid impurities affecting battery performance. Step S6: Battery assembly and testing.

[0041] Example 2 Same as in Example 1, except that in step S5: when electrodepositing Sn nanoparticles, the deposition time is adjusted to 300s, and ≥90% of the area on the Cu nanocone is covered with Sn nanoparticle coating, with a coating thickness of about 100nm.

[0042] Example 3 Same as in Example 1, except that in step S5: when electrodepositing Sn nanoparticles, the deposition time is adjusted to 500s, and ≥90% of the area on the Cu nanocone is covered with Sn nanoparticle coating, with a coating thickness of about 300nm.

[0043] Example 4 Same as Example 1, except for step S2: Li + -Nafion solution concentration 6.5wt%, sprayed Li + During the Nafion ion homogenization layer process, the number of spraying passes was adjusted to 3, the heating plate temperature to 60℃, and the drying time to 50 min, ultimately yielding a Li layer with a thickness of 200 nm. + -Nafion ion homogenization layer.

[0044] Example 5 Same as Example 1, except for step S2: Li + -Nafion solution concentration 6.5wt%, sprayed Li + During the Nafion ion homogenization layer process, the number of spraying passes was adjusted to 5, the heating plate temperature to 85℃, and the drying time to 70 min, ultimately yielding a Li layer with a thickness of 800 nm. + -Nafion ion homogenization layer.

[0045] Example 6 Same as in Example 1, except that in step S3: when preparing a planar Cu layer by magnetron sputtering, the sputtering time is adjusted to 10s and the sputtering power to 50W, and a planar Cu layer with a thickness of 5nm is prepared.

[0046] Example 7 Same as in Example 1, except that in step S3: when preparing a planar Cu layer by magnetron sputtering, the sputtering time is adjusted to 300s and the sputtering power to 200W to prepare a planar Cu layer with a thickness of 50nm.

[0047] Example 8 Same as Example 1, except that in step S4: during the electrodeposition of Cu nanocones, the current density is adjusted to -30 mA / cm. 2 A Cu nanocone array with a height of 1 μm was prepared by deposition time of 600 s.

[0048] Example 9 Same as Example 1, except that in step S4: during the electrodeposition of Cu nanocones, the current density is adjusted to -50 mA / cm. 2 A Cu nanocone array with a height of 2 μm was prepared by deposition time of 1200 s.

[0049] Example 10 Same as Example 1, except that in step S5: when electrodepositing Sn nanoparticles, the SnSO4 concentration in the electroplating solution is adjusted to 0.1 mol / L and the current density to 4 mA / cm². 2 Ultimately, ≥90% of the area of ​​the Cu nanocone is covered by Sn nanoparticles with a particle size of 50 nm.

[0050] Example 11 Same as Example 1, except that in step S5: when electrodepositing Sn nanoparticles, the SnSO4 concentration in the electroplating solution is adjusted to 0.5 mol / L and the current density to 6 mA / cm². 2 Ultimately, ≥90% of the area of ​​the Cu nanocone is covered by Sn nanoparticles with a particle size of 100 nm.

[0051] Example 12 Same as in Example 1, except for step S2: Li + - Dilute the Nafion solution to 5 wt%, while keeping other spraying and drying parameters unchanged.

[0052] Example 13 Same as in Example 1, except for step S2: Li + - Dilute the Nafion solution to 8 wt%, while keeping other spraying and drying parameters unchanged.

[0053] Comparative Example 1 Same as Example 1, except that: all steps S1~S5 are omitted, and a 6μm thick pure copper foil is directly used as the current collector, without PDMS substrate film or Li. + -Nafion ion homogenization layer, no 3D Cu@Sn lithium-affinity layer, battery assembly and testing procedures are the same.

[0054] Comparative Example 2 Similar to Example 1, the only difference is in step S5: when electrodepositing Sn nanoparticles, the deposition time is adjusted to 200s, and finally ≥90% of the area on the Cu nanocone is covered with Sn nanoparticle coating, with a coating thickness of about 80nm.

[0055] Comparative Example 3 Similar to Example 1, the only difference is that in step S5, when electrodepositing Sn nanoparticles, the deposition time is adjusted to 600s, and finally ≥90% of the area on the Cu nanocone is covered with Sn nanoparticle coating, with a coating thickness of about 350nm.

[0056] Comparative Example 4 Same as Example 1, except for step S2: Li + -Nafion solution concentration 6.5wt%, sprayed Li + During the Nafion ion homogenization layer process, the number of spraying passes was adjusted to 2, the heating plate temperature to 55℃, and the drying time to 40 min, ultimately resulting in a Li layer with a thickness of 150 nm. + -Nafion ion homogenization layer.

[0057] Comparative Example 5 Same as Example 1, except for step S2: Li + -Nafion solution concentration 6.5wt%, sprayed Li + During the Nafion ion homogenization layer process, the number of spraying passes was adjusted to 6, the heating plate temperature to 90℃, and the drying time to 80 min, ultimately yielding a Li layer with a thickness of 850 nm. + -Nafion ion homogenization layer.

[0058] Comparative Example 6 Same as in Example 1, except that in step S3: when preparing a planar Cu layer by magnetron sputtering, the sputtering time is adjusted to 5s and the sputtering power to 30W, and a planar Cu layer with a thickness of 3nm is prepared.

[0059] Comparative Example 7 Same as in Example 1, except that in step S3: when preparing a planar Cu layer by magnetron sputtering, the sputtering time is adjusted to 350s and the sputtering power to 250W, and a planar Cu layer with a thickness of 55nm is prepared.

[0060] Comparative Example 8 Same as in Example 1, except that in step S4: when electrodepositing Cu nanocones, the current density was adjusted to -25mA / cm² and the deposition time was 500s to prepare a Cu nanocone array with a height of 0.8μm.

[0061] Comparative Example 9 Same as Example 1, except that in step S4: when electrodepositing Cu nanocones, the current density was adjusted to -55mA / cm² and the deposition time was 1300s to prepare a Cu nanocone array with a height of 2.2μm.

[0062] Comparative Example 10 Same as Example 1, except that in step S5: when electrodepositing Sn nanoparticles, the SnSO4 concentration in the electroplating solution is adjusted to 0.05 mol / L and the current density to 3 mA / cm². 2 Ultimately, ≥90% of the area of ​​the Cu nanocone is covered by Sn nanoparticles, and the Sn nanoparticles have a particle size of 40 nm.

[0063] Comparative Example 11 Same as Example 1, except that in step S5: when electrodepositing Sn nanoparticles, the SnSO4 concentration in the electroplating solution is adjusted to 0.6 mol / L and the current density to 7 mA / cm². 2 Ultimately, ≥90% of the area of ​​the Cu nanocone is covered by Sn nanoparticles, and the Sn nanoparticles have a particle size of 110 nm.

[0064] Comparative Example 12 Same as in Example 1, except for step S2: Li + -Nafion solution diluted to 4 wt%, other spraying and drying parameters remained unchanged, resulting in Li + - The Nafion ion homogenization layer has uneven film formation, pinholes, and poor film adhesion, making it easy to peel off.

[0065] Comparative Example 13 Same as in Example 1, except for step S2: Li + -Nafion solution diluted to 9wt%, other spraying and drying parameters remained unchanged, resulting in Li + - The Nafion ion homogenization layer film is cracked, resulting in poor adhesion.

[0066] Comparative Example 14 Same as Example 1, except that step S2 (spraying Li) is omitted. + -Nafion ion homogenization layer), directly prepare a planar Cu layer, electrodeposited Cu nanocones, and electrodeposited Sn nanoparticles on the surface of the PDMS base film to obtain a PDMS base film + 3D Cu@Sn lithiophilic layer bilayer structure.

[0067] Comparative Example 15 Same as Example 1, except that steps S4-S5 (electrodeposition of Cu nanocones, electrodeposition of Sn nanoparticles) are omitted, and only steps S1-S3 (PDMS base film, Li) are retained. + -Nafion ion homogenization layer, planar Cu layer), to obtain PDMS base film + Li + - The structure consists of a Nafion ion homogenization layer and a planar Cu layer.

[0068] After all samples were prepared, the batteries were assembled and tested according to the following standards: The positive electrode (NCM811: sulfide electrolyte: conductive carbon = 70:28:2), the negative electrode is the functional current collector of this invention, the composite 50μm lithium metal layer, and the solid electrolyte layer (sulfide electrolyte Li6PS5Cl) are used to encapsulate a button cell. After 100 cycles at 0.5C and 25℃, the dendrite formation, nucleation overpotential, and cycle capacity retention are tested.

[0069] The test results are shown in Table 1.

[0070] Table 1

[0071] Analysis of experimental conclusions: From the perspective of the influence of Sn nanoparticle coating thickness in the 3D Cu@Sn lithiophilic metal layer, no obvious lithium dendrites were observed in Examples 1-3, and the battery performance was stable. When the Sn nanoparticle coating thickness is controlled within a suitable range, it can achieve uniform coverage of the Cu nanocone surface, fully utilize its lithiophilic properties, and guide the uniform nucleation and deposition of lithium ions. Comparative Example 2 had an excessively low Sn coating thickness, while Comparative Example 3 had an excessively high thickness. Both examples showed a small amount of lithium dendrites, reducing the lithiophilic active sites on the current collector surface and causing localized formation of a small amount of lithium dendrites. In Comparative Example 3, coating detachment also occurred.

[0072] Li + The performance of the Nafion ion homogenization layer is related to its thickness and solution concentration. In Examples 1, 4, 5, 12, and 13, no obvious lithium dendrites were observed, and the battery performance was good. Within a suitable thickness and concentration range, the ion homogenization layer can not only uniformly regulate the transport and distribution of lithium ions, avoiding local ion aggregation, but also ensure the film quality and adhesion of its own film layer, achieving good integration with the upper and lower layers. In Comparative Example 4, the ion homogenization layer thickness was below the suitable range, resulting in a small amount of lithium dendrites and uneven ion distribution; in Comparative Example 5, the thickness was above the suitable range, and although no obvious dendrites were observed, ion transport was hindered; in Comparative Example 12, the solution concentration was below the suitable range, resulting in numerous pinholes in the film layer and easy detachment; in Comparative Example 13, the concentration was above the suitable range, resulting in film layer cracking and poor adhesion. All four comparative examples showed a small amount of lithium dendrites. If the parameters of the ion homogenization layer are not properly controlled, it will not only affect the normal function of ion homogenization, leading to lithium dendrite growth, but also damage the structural integrity of the entire current collector.

[0073] In the 3D Cu@Sn lithiophilic metal layer, the selection of the planar Cu layer thickness and the Cu nanocone height also significantly affected the experimental results. No obvious lithium dendrites were observed in Examples 1, 6, 7, 8, and 9, and the battery performance was stable. This indicates that a suitable planar Cu layer thickness can provide good conductive support and deposition substrate for the entire structure, while a suitable Cu nanocone height can construct an effective 3D structure, increasing lithium ion nucleation sites. The synergistic effect of both significantly improves the lithiophilic and conductive properties of the current collector. In Comparative Example 6, the planar Cu layer thickness was below the suitable range, resulting in a small amount of lithium dendrites and Cu layer damage. In Comparative Example 7, the planar Cu layer thickness was above the suitable range; although no obvious dendrites were observed, the flexibility of the current collector deteriorated. In Comparative Example 8, the Cu nanocone height was below the suitable range, resulting in a small amount of lithium dendrites and insufficient lithiophilicity. In Comparative Example 9, the Cu nanocone height was above the suitable range, resulting in a small amount of lithium dendrites and nanocone aggregation. The thickness of the planar Cu layer and the height of the Cu nanocone affect the structural stability of the 3D Cu@Sn layer, thus affecting its function of guiding the uniform deposition of lithium ions.

[0074] Regarding the particle size of Sn nanoparticles, no obvious lithium dendrites were observed in Examples 1, 10, and 11, and their performance was consistent. This indicates that Sn nanoparticles of suitable size can fully utilize their lithiophilic properties, uniformly adhering to the surface of Cu nanocones and effectively preventing localized lithium ion aggregation. In contrast, the Sn nanoparticles in Comparative Example 10 had a particle size below the suitable range, exhibiting a small amount of lithium dendrites and uneven coating; the particle size in Comparative Example 11 was above the suitable range, also exhibiting a small amount of lithium dendrites and a less dense coating.

[0075] Besides controlling the parameters of each layer, the integrity of the three-layer composite structure is the core of achieving efficient suppression of lithium dendrites. Examples 1 to 13 all used PDMS base film and Li... + The three-layer structure of the Nafion ion homogenization layer and the 3D Cu@Sn lithium-loving metal layer showed no obvious lithium dendrites, resulting in excellent battery performance and fully demonstrating the complementary and synergistic effects of each layer. In contrast, Comparative Example 14, without Li... + - Nafion ion homogenization layer, retaining only the bilayer structure of PDMS base film and 3D Cu@Sn lithiophilic layer, compared to Comparative Example 15 without 3D Cu@Sn lithiophilic layer, retaining only PDMS base film and Li + The structures of the Nafion ion homogenization layer and the planar Cu layer in both comparative examples showed a large number of lithium dendrites, resulting in a significant decrease in battery performance. Single-layer or double-layer structures cannot achieve multi-dimensional lithium dendrite suppression, making it difficult to overcome the shortcomings of existing technologies. In addition, Comparative Example 1 directly used traditional pure metal copper foil as the current collector without any composite structure, which ultimately resulted in a large number of lithium dendrites that pierced the separator, resulting in the worst battery performance.

[0076] In summary, the composite current collector structure of this invention utilizes a polydimethylsiloxane film layer and Li + The three-layer synergistic structure of the Nafion ion homogenization layer and the 3D Cu@Sn lithium-loving metal layer has significant advantages in suppressing lithium dendrite growth, improving battery safety and cycle stability, and can fundamentally solve the technical defects of traditional rigid current collectors that cannot release deposition stress and accelerate dendrite growth.

[0077] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent substitutions, and improvements made by those skilled in the art to the above embodiments without departing from the scope of the technical solution of the present invention, based on the technical essence of the present invention, shall still fall within the protection scope of the technical solution of the present invention.

Claims

1. A functional current collector for suppressing lithium dendrites, characterized in that, include: The polydimethylsiloxane film layer is located in the middle layer of the functional current collector; Li + -Nafion ion homogenization layer is coated on the polydimethylsiloxane film layer; A 3D Cu@Sn lithium-loving metal layer is disposed on the Li + - The surface of the Nafion ion homogenization layer; the 3D Cu@Sn lithiophilic metal layer is a Cu layer with a Cu nanocone surface, and Sn nanoparticles are covered on ≥90% of the area of ​​the Cu nanocones.

2. The functional current collector for suppressing lithium dendrites according to claim 1, characterized in that: The Li + The thickness of the Nafion ion homogenization layer is 200~800 nm.

3. The functional current collector for suppressing lithium dendrites according to claim 1, characterized in that: In the 3D Cu@Sn lithium-loving metal layer, the bottom of the Cu nanocone has a planar Cu layer of 5~50nm, and the height of the Cu nanocone is 1~2μm.

4. The functional current collector for suppressing lithium dendrites according to claim 1, characterized in that: The particle size of Sn nanoparticles is 50~100nm; the thickness of the Sn nanoparticle capping layer is 100~300nm.

5. The method for preparing the functional current collector for suppressing lithium dendrites according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1: Preparation of polydimethylsiloxane membrane; S2: Li is sprayed onto the surface of the polydimethylsiloxane film. + -Nafion solution, dried, to obtain Li + -Nafion ion homogenization layer; S3: In the presence of Li + - A planar Cu layer is formed on the surface of the polydimethylsiloxane film of the Nafion ion homogenization layer by magnetron sputtering; S4: Cu nanocones are prepared by deposition on a planar Cu layer; S5: Sn nanoparticles are deposited on Cu nanocones to form a coating.

6. The method for preparing the functional current collector for suppressing lithium dendrites according to claim 5, characterized in that: Step S1 involves preparing a polydimethylsiloxane membrane by mixing a polydimethylsiloxane prepolymer and a curing agent at a mass ratio of 9-11:1, degassing the mixture, coating it evenly onto a substrate, and then peeling it off from the substrate after thermal curing to obtain the polydimethylsiloxane membrane.

7. The method for preparing the functional current collector for suppressing lithium dendrites according to claim 5, characterized in that: In step S2, Li + The concentration of the Nafion solution is 5-8 wt%, and it is sprayed continuously 3-5 times. The temperature of the polydimethylsiloxane film during spraying is 60-85℃. After spraying, it is dried at 110-130℃ for 50-70 minutes.

8. The method for preparing the functional current collector for suppressing lithium dendrites according to claim 5, characterized in that: Step S4: Cu nanocones are electrodeposited on a planar Cu layer. The electrolyte contains CuSO4·5H2O, H2SO4, polyethylene glycol, and NaCl, and the current density is -30 to -50 mA / cm². 2 The deposition time is 600~1200s; in step S5, Sn nanoparticles are electrodeposited on Cu nanocones in an electroplating solution containing SnSO4 and H2SO4, with a current density of 4~6mA / cm. 2 The deposition time is 300~500s.

9. An electrode sheet, characterized in that: The current collector includes the lithium dendrite-suppressing functional current collector as described in any one of claims 1 to 4.

10. A battery, characterized in that: It includes the electrode sheet as described in claim 9.

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