Integrated composite negative electrode for all-solid-state battery, preparation method of integrated composite negative electrode and all-solid-state battery
By adopting an integrated composite negative electrode structure in the all-solid-state battery, the problem of unstable interfacial contact between the negative electrode and the electrolyte is solved, thereby improving the battery's energy density, cycle stability, and safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-12
- Publication Date
- 2026-04-07
AI Technical Summary
In all-solid-state batteries, the interfacial contact between the negative electrode and the electrolyte is unstable, leading to reduced electrochemical performance and lithium dendrite growth, which affects the battery's safety and cycle stability.
The integrated composite negative electrode structure includes a current collector, a first electrode layer, and a second electrode layer. The first electrode layer is composed of a first solid electrolyte, a binder, and additives, while the second electrode layer is composed of a second solid electrolyte, a binder, a negative electrode active material, and a conductive agent. The electrode-electrolyte system is formed through a one-step coating process.
It effectively improves the interfacial contact between the negative electrode and the electrolyte, reduces lithium dendrite growth, and improves the energy density, cycle stability and safety of the battery.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of solid-state batteries, in particular to an integrated composite negative electrode for a solid-state battery, a preparation method thereof and a solid-state battery. BACKGROUND
[0002] With the increasing demand for sustainable energy worldwide, electric vehicles (EVs) have gradually become the mainstream trend in the automotive industry, which has greatly promoted the innovation and development of lithium-ion battery technology. Lithium-ion batteries have dominated the rechargeable battery market due to their high energy density, long life, and low self-discharge rate. However, in order to meet the demand for higher range and faster charging and discharging, metal lithium negative electrodes are considered as a key to breaking through the existing energy density bottleneck due to their high theoretical energy density and low charging voltage. However, the lithium dendrite problem in lithium metal negative electrodes can easily cause internal short circuits in the battery, and even may cause thermal runaway, leading to fires or explosions, posing a significant safety risk. Moreover, the liquid electrolyte in traditional lithium-ion batteries also has the problems of flammability and volatility, which also pose a significant safety risk. The safety problem has become a major obstacle to the development of the battery industry.
[0003] To solve these problems, the concept of solid-state lithium batteries (SSLBs) has been proposed and received widespread attention. SSLBs use solid-state electrolytes instead of liquid electrolytes, which can effectively inhibit the growth of lithium dendrites and significantly improve the safety performance of the battery. At the same time, due to the better chemical stability of solid-state electrolytes, they can work at higher voltages, thereby improving the overall energy density.
[0004] However, the preparation process of all-solid-state batteries has encountered new difficulties. In all-solid-state batteries, the contact mode between the negative electrode and the electrolyte changes from liquid-solid contact in traditional liquid batteries to solid-solid contact. While this change brings many advantages in theory, it is quite challenging in actual production, especially in the face of the unevenness of the negative electrode surface. During the battery cycling process, the contact between the negative electrode and the solid-state electrolyte film becomes unstable, and even with high-pressure rolling technology for compounding, the gap between the two cannot be completely eliminated. The existence of these gaps, on the one hand, reduces the electrochemical performance of the battery, and on the other hand, provides an opportunity for the formation of lithium dendrites, thereby causing short circuits and failures of the battery, severely restricting the practical application prospects of all-solid-state batteries.
[0005] In summary, developing an innovative method to improve the interface contact between the negative electrode and the electrolyte in all-solid-state batteries is of great significance for improving the overall performance and stability of the battery, especially the cycling stability and reliability. Therefore, the present application is proposed. SUMMARY
[0006] The main purpose of the present application is to provide an integrated composite negative electrode for a full solid-state battery and a preparation method thereof, and a full solid-state battery, so as to solve the interface contact problem between the negative electrode and the electrolyte in the prior art full solid-state battery, and further improve the battery capacity, cycle stability and reliability of the battery.
[0007] The present application provides an integrated composite negative electrode for a full solid-state battery, which comprises a current collector and a first electrode layer and a second electrode layer located on one side surface of the current collector, the second electrode layer is arranged close to the current collector, and the first electrode layer is formed by coating the material of the first electrode layer on the surface of the side of the second electrode layer away from the current collector; wherein the material of the first electrode layer comprises: a first solid-state electrolyte, a first binder and an additive; and the material of the second electrode layer comprises: a second solid-state electrolyte, a second binder, a negative electrode active material and a conductive agent.
[0008] Further, the weight ratio of the first solid-state electrolyte, the first binder and the additive is 100:(2-5):(0.5-2); and the weight ratio of the second solid-state electrolyte, the second binder, the conductive agent and the negative electrode active material is (10-30):(2-5):(0.5-2):100; preferably, the weight ratio of the first solid-state electrolyte, the first binder and the additive is 100:(2-3):(0.5-1); and the weight ratio of the second solid-state electrolyte, the second binder, the conductive agent and the negative electrode active material is (10-20):(2-3):(0.5-1):100.
[0009] Further, the thickness of the first electrode layer is 10-60 µm, and the thickness of the second electrode layer is 10-100 µm; preferably, the thickness of the first electrode layer is 20-30 µm, and the thickness of the second electrode layer is 10-30 µm.
[0010] Further, in the material of the first electrode layer, the weight percentage content of the first binder is 2-3%; and / or; in the material of the second electrode layer, the weight percentage content of the second binder is 2-3%.
[0011] Further, the first solid-state electrolyte is a sulfide solid-state electrolyte; preferably, the sulfide solid-state electrolyte is selected from Li3PS4, Li 10 GeP2S 12 , Li7P3S 11one or more of Li6PS5Cl, Li6PS5Br and Li6PS5I solid state electrolyte; and / or; the first binder is selected from one or more of styrene-butadiene-styrene rubber, hydrogenated styrene-butadiene-styrene rubber, nitrile rubber, hydrogenated nitrile rubber, styrene-butadiene rubber and acrylate rubber; and / or; the additive is selected from inorganic additive and / or organic additive; preferably, the inorganic additive is selected from one or more of aluminum oxide, titanium dioxide, zirconium oxide, magnesium oxide, tin dioxide, silicon dioxide, boron nitride or titanium phosphate; and / or, the organic additive is selected from one or more of cellulose nanocrystalline material, polyimide nanocrystalline material and aramid nanocrystalline material; preferably, the particle size of the additive is ≤ 5 µm; preferably, the current collector is at least one of copper foil, nickel-plated copper foil or tin-plated copper foil.
[0012] Further, the second solid state electrolyte comprises sulfide electrolyte and / or oxide electrolyte; preferably, the second solid state electrolyte comprises sulfide electrolyte and oxide electrolyte; preferably, the sulfide solid state electrolyte is selected from Li3PS4, Li 10 GeP2S 12 , Li7P3S 11 , Li6PS5Cl, Li6PS5Br and Li6PS5I solid state electrolyte; preferably, the oxide electrolyte is selected from one or more of LATP, LLZO, LLZTO and LLTO; and / or; the second binder is selected from one or more of polyvinylidene fluoride, styrene-butadiene-styrene rubber, fluorinated styrene-butadiene rubber and fluorinated nitrile rubber; and / or; the negative active material is selected from one or more of silicon material, silicon-carbon material, silicon monoxide material and graphite; and / or; the conductive agent is selected from one or more of carbon black, carbon nanotube and carbon fiber material.
[0013] According to the second aspect of the present application, there is also provided a preparation method of the above integrated composite negative electrode for all-solid-state battery, comprising the following steps: dispersing the first solid state electrolyte, the first binder and the additive in a first organic solvent to obtain a first slurry; dispersing the second solid state electrolyte, the second binder, the negative active material and the conductive agent in a second organic solvent to obtain a second slurry; coating the second slurry on the surface of one side of the current collector, and performing first drying to form a second electrode layer, thereby obtaining a composite negative electrode precursor; coating the first slurry on the surface of the second electrode layer, and performing second drying to form a first electrode layer, thereby obtaining an integrated composite negative electrode.
[0014] Further, the coating method is transfer coating or extrusion coating; preferably, the current collector is selected from at least one of copper foil, nickel-plated copper foil or tin-plated copper foil; preferably, the first organic solvent is selected from amyl valerate and / or dimethylbenzene; preferably, the second organic solvent is selected from N-methyl pyrrolidone and / or ethyl benzoate; preferably, the solid content of the first slurry is 50-75%; preferably, the solid content of the second slurry is 45-65%.
[0015] Further, the first drying temperature is 120-150°C, and the first drying time is 10-30 min; the second drying temperature is 60-150°C, and the second drying time is 8-12 h; preferably, the first drying temperature is 120-130°C, and the first drying time is 10-15 min; the second drying temperature is 80-120°C, and the second drying time is 8-10 h.
[0016] According to a third aspect of the present application, a full solid-state battery is also provided, which includes a positive electrode sheet and a negative electrode sheet, and the negative electrode sheet is the above-mentioned integrated composite negative electrode for a full solid-state battery.
[0017] The present application provides an integrated composite negative electrode for a full solid-state battery, which includes a current collector and a first electrode layer and a second electrode layer on one side surface of the current collector, the second electrode layer is arranged close to the current collector, and the first electrode layer is formed by coating the material of the first electrode layer on the surface of the side of the second electrode layer away from the current collector; wherein the material of the first electrode layer includes: a first solid-state electrolyte, a first binder and an additive; and the material of the second electrode layer includes: a second solid-state electrolyte, a second binder, a negative electrode active material and a conductive agent. The integrated composite negative electrode with the above structure and composition is used in a full solid-state battery, which can effectively improve the interface contact problem between the negative electrode and the electrolyte in the full solid-state battery and the lithium dendrite growth problem caused thereby, thereby effectively improving the battery capacity and cycle stability of the battery and improving the safety of the battery. DETAILED DESCRIPTION
[0018] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments.
[0019] As described in the background section, in all-solid-state batteries, the contact mode of the negative electrode with the electrolyte is changed from liquid-solid contact in traditional liquid batteries to solid-solid contact. This change, although theoretically brings many advantages, is quite tricky in actual production, especially in the face of the unevenness of the negative electrode surface. During the battery cycle, the contact between the negative electrode and the solid electrolyte film becomes unstable, and even with high-pressure rolling technology for compounding, the gap between the two cannot be completely eliminated. The existence of these gaps, on the one hand, reduces the electrochemical performance of the battery, and on the other hand, provides an opportunity for the formation of lithium dendrites, thereby triggering short circuits and failure of the battery, severely restricting the practical application prospects of solid-state batteries.
[0020] To solve the above problems, the present application provides an integrated composite negative electrode for a solid-state battery, which comprises a current collector and a first electrode layer and a second electrode layer on one side surface of the current collector, the second electrode layer is arranged close to the current collector, and the first electrode layer is formed by coating the material of the first electrode layer on the surface of the second electrode layer away from the current collector; wherein the material of the first electrode layer comprises: a first solid-state electrolyte, a first binder and an additive; the material of the second electrode layer comprises: a second solid-state electrolyte, a second binder, a negative electrode active material and a conductive agent. The integrated composite negative electrode with the above structure and composition used in a solid-state battery can effectively improve the interface contact problem between the negative electrode and the electrolyte in the solid-state battery and the lithium dendrite growth problem caused thereby, thereby effectively improving the battery capacity and cycle stability of the battery and improving the safety of the battery. The reasons for the above beneficial effects are analyzed, which may include the following aspects:
[0021] Firstly, the integrated composite negative electrode provided by the present application coats the material of the first electrode layer on one side surface of the second electrode layer to obtain an integrated composite negative electrode comprising a first electrode layer and a second electrode layer. The above structure can make the first electrode layer and the second electrode layer achieve a tightly fitted state, forming a seamless and efficient electrode-electrolyte system, thereby effectively solving the problems of traditional all-solid-state batteries in interface contact, lithium dendrite growth and battery reliability, and achieving the purpose of further improving the energy density, cycle stability and safety of all-solid-state batteries.
[0022] Further, the material in the first electrode layer includes: a first solid-state electrolyte, a first binder, and an additive. The first solid-state electrolyte can provide better charge and discharge rates for the composite anode; the first binder is used to enhance the adhesion between the solid-state electrolyte particles and the adhesion strength on the interface between the second electrode layer, ensuring that the first electrode layer can maintain structural integrity during battery charge and discharge cycles without cracking or delamination; the presence of the additive helps to further buffer the stress generated by the volume change of the battery during the charging and discharging process, thereby better maintaining the integrity of the electrolyte layer, maintaining the contact between the solid-state electrolyte and the negative active material, while also enhancing the mechanical strength and thermal stability of the first electrode layer, reducing the probability of lithium dendrite formation.
[0023] The material in the second electrode layer includes: a second solid-state electrolyte, a second binder, a negative active material, and a conductive agent. The second solid-state electrolyte can improve the battery capacity and increase the migration efficiency of charge carriers, adapt to the contact with the negative active material and the lithium ion insertion / extraction process. The presence of the conductive agent can improve the electronic conduction network of the second electrode layer, ensuring that electrons can be quickly and uniformly transmitted between active material particles, reducing charge accumulation and internal resistance, thereby improving the rate performance and overall efficiency of the battery. The negative active material can reversibly insert and extract lithium ions, directly affecting the energy density, charge and discharge efficiency, and cycle life of the all-solid-state battery. The second binder can firmly bind the electrode active material, conductive agent, and electrolyte particles together, ensuring that the second electrode layer can maintain structural stability and integrity under battery operating conditions. Under the synergistic effect of the various components in the first electrode layer and the second electrode layer, the energy density and conductivity of the all-solid-state battery can be further improved.
[0024] In summary, the integrated composite anode provided by the present application tightly combines the first electrode layer and the second electrode layer through a one-step coating process, forming a seamless and efficient electrode-electrolyte system that can effectively address the challenges of interface contact between the negative electrode and the electrolyte layer, lithium dendrite growth, and cell reliability in traditional all-solid-state batteries, thereby achieving a major breakthrough in improving the energy density, cycle stability, and safety of the battery.
[0025] In a preferred embodiment, the weight ratio of the first solid electrolyte, the first binder, and the additive is 100:(2~5):(0.5~2); the weight ratio of the second solid electrolyte, the second binder, the conductive agent, and the negative electrode active material is (10~30):(2~5):(0.5~2):100. As mentioned above, the materials in the first electrode layer and the second electrode layer have a significant impact on the energy density and conductivity of the composite negative electrode. By controlling the addition ratio of the materials in the first electrode layer and the second electrode layer within the above-mentioned ranges, the first electrode layer and the second electrode layer can achieve a better tight fit, which helps to better alleviate the interface contact problem of traditional all-solid-state batteries and the resulting problems such as lithium dendrite growth, thereby further improving the overall electrochemical performance of the all-solid-state battery. Preferably, the weight ratio of the first solid electrolyte, the first binder, and the additive is 100:(2~3):(0.5~1); the weight ratio of the second solid electrolyte, the second binder, the conductive agent, and the negative electrode active material is (10~20):(2~3):(0.5~1):100. Controlling the addition ratio of materials in the first electrode layer and the second electrode layer within the above-mentioned preferred range yields even better results.
[0026] In a preferred embodiment, the thickness of the first electrode layer is 10-60 µm, and the thickness of the second electrode layer is 10-100 µm. The aforementioned thickness of the first electrode layer can further improve the ion conductivity and rate performance of the electrode, helping to avoid the problems of reduced ion conductivity due to excessive thinness, or increased internal resistance and reduced rate performance due to excessive thickness. Furthermore, the aforementioned thickness range of the second electrode layer also contributes to the comprehensive improvement of the composite anode's electrochemical activity, charge transport, and mechanical strength. Preferably, the thickness of the first electrode layer is 20-30 µm, and the thickness of the second electrode layer is 10-30 µm. Controlling the thickness of the first and second electrode layers within the aforementioned preferred ranges yields better results in improving the electrochemical performance of the composite anode.
[0027] In a preferred embodiment, the weight percentage of the first binder in the material of the first electrode layer is 2-3%; and / or, the weight percentage of the second binder in the material of the second electrode layer is 2-3%. Controlling the binder content in the materials of the first and second electrode layers within the above range can better form a stable and dense electrode structure while ensuring the lithium-ion insertion and extraction efficiency and the energy density and rate performance of the composite electrode, thereby contributing to further improving the overall electrochemical performance of the formed all-solid-state battery.
[0028] In a preferred embodiment, the first solid electrolyte is a sulfide solid electrolyte; preferably, the sulfide solid electrolyte is selected from Li3PS4, Li10 GeP2S 12 Li7P3S 11 One or more of Li6PS5Cl, Li6PS5Br, and Li6PS5I solid electrolytes are used. Sulfide solid electrolytes possess high ionic conductivity and good chemical stability, effectively suppressing lithium dendrite growth and improving battery safety and electrochemical performance. Using the aforementioned sulfide solid electrolytes can better improve the electrochemical performance of the composite negative electrode. Preferably, the first binder is selected from one or more of styrene-butadiene-styrene rubber, hydrogenated styrene-butadiene-styrene rubber, nitrile rubber, hydrogenated nitrile rubber, styrene-butadiene rubber, and acrylate rubber; and / or, the additives are selected from inorganic additives and / or organic additives; preferably, the inorganic additives are selected from one or more of alumina, titanium dioxide, zirconium oxide, magnesium oxide, tin dioxide, silicon dioxide, boron nitride, or titanium phosphate; and / or, the organic additives are selected from one or more of cellulose nanocrystalline materials, polyimide nanocrystalline materials, and aramid nanocrystalline materials; preferably, the particle size of the additives is ≤5µm. Using the aforementioned type of first binder and additives can better enhance the mechanical strength of the electrode layer, improve the electrode-electrolyte interface contact, and reduce internal gaps, thereby improving the cycle performance and stability of the battery. Preferably, the current collector is at least one of copper foil, nickel-plated copper foil, or tin-plated copper foil. The aforementioned current collector is beneficial for further improving the overall performance of the integrated composite negative electrode.
[0029] In a preferred embodiment, the second solid electrolyte comprises a sulfide electrolyte and / or an oxide electrolyte; preferably, the second solid electrolyte comprises a sulfide electrolyte and an oxide electrolyte; preferably, the sulfide solid electrolyte is selected from Li3PS4, Li 10 GeP2S 12 Li7P3S 11The composite negative electrode uses one or more of the following solid electrolytes: Li6PS5Cl, Li6PS5Br, and Li6PS5I. Preferably, the oxide electrolyte is selected from one or more of LATP, LLZO, LLZTO, and LLTO. Preferably, the second binder is selected from one or more of polyvinylidene fluoride, styrene-butadiene-styrene rubber, fluorinated styrene-butadiene rubber, and fluorinated nitrile rubber. Preferably, the negative electrode active material is selected from one or more of silicon, silicon-carbon, silicon suboxide, and graphite. Preferably, the conductive agent is selected from one or more of carbon black, carbon nanotubes, and carbon fiber materials. The preferred combination of sulfide and oxide electrolytes can better balance the ionic conductivity and electrochemical stability of the composite negative electrode. The addition of the conductive agent enhances the electron transport between the charge carrier lithium ions and the active material in the composite negative electrode, playing an important role in improving the rate performance and cycle stability of the battery. The combined use of sulfide and oxide solid electrolytes in the second electrode layer, along with the selection of binders, negative electrode active materials (such as silicon, graphite, etc.), and conductive agents (such as carbon nanotubes), aims to construct a more efficient charge storage and transport system.
[0030] According to another aspect of the present invention, a method for preparing the above-mentioned integrated composite negative electrode for all-solid-state batteries is also provided. This method includes the following steps: dispersing a first solid electrolyte, a first binder, and additives in a first organic solvent to obtain a first slurry; dispersing a second solid electrolyte, a second binder, a negative electrode active material, and a conductive agent in a second organic solvent to obtain a second slurry; coating the second slurry onto the surface of a current collector side, and subjecting it to a first drying to form a second electrode layer, thereby obtaining a composite negative electrode precursor; coating the first slurry onto the surface of the second electrode layer, and subjecting it to a second drying to form a first electrode layer, thereby obtaining an integrated composite negative electrode. In the above preparation method, by coating the material of the first electrode layer onto the surface of one side of the second electrode layer, an integrated composite negative electrode comprising a first electrode layer and a second electrode layer is obtained, enabling the first electrode layer and the second electrode layer to achieve a close fit, forming a seamless and efficient electrode-electrolyte system. The composite anode prepared by the above method can effectively solve the problems of interface contact, lithium dendrite growth and cell reliability between the anode and electrolyte layer in traditional all-solid-state batteries, thereby helping to improve the overall performance of all-solid-state batteries in terms of energy density, cycle stability and safety.
[0031] In a preferred embodiment, the coating method is at least one of transfer coating or extrusion coating; preferably, the current collector is selected from at least one of copper foil, nickel-plated copper foil, or tin-plated copper foil; preferably, the solid content of the first slurry is 50-75%; preferably, the solid content of the second slurry is 45-65%. Controlling the thickness of the first and second electrode layers, the coating method, and the solid content of the slurry within the above ranges enables a better and tighter bond between the first and second electrode layers, thereby more effectively mitigating the lithium dendrite problem in all-solid-state batteries. Preferably, the first organic solvent includes amyl valerate and / or xylene; preferably, the second organic solvent is selected from N-methylpyrrolidone and / or ethyl benzoate. Preferably, the solubility of the first binder in the second organic solvent is ≤0.1g / 100g; controlling these conditions is to prevent the second organic solvent in the second slurry from dissolving the first binder in the first slurry during coating, leading to detachment of the second electrode layer and the current collector. Simultaneously, it also avoids unevenness on the coating surface caused by dissolving the binder in the second electrode layer.
[0032] In a preferred embodiment, the first drying temperature is 120-150°C for 10-30 minutes; the second drying temperature is 60-150°C for 8-12 hours. If the first drying time is too short, the second electrode layer may not be preliminarily dried, affecting the subsequent coating process; if the drying time is too long, it is detrimental to the formation of an interface layer between the first and second electrode layers. If the second drying temperature is too low or the time is too long, the electrolyte layer may flow, leading to a shift in coating thickness; if the second drying temperature is too high, the binder may float, causing uneven material gradients in the formed second electrode layer. All of these problems will adversely affect the performance of the composite negative electrode. Controlling the temperature and time of the first and second drying within the above-mentioned ranges allows for a better interface layer to be formed between the first and second electrode layers. Preferably, the first drying temperature is 120-130°C for 10-15 minutes; the second drying temperature is 80-120°C for 8-10 hours. Controlling the temperature and time of the first and second drying within the above-mentioned preferred ranges yields even better results.
[0033] According to a third aspect of the present invention, an all-solid-state battery is also provided, the all-solid-state battery comprising a positive electrode and a negative electrode, wherein the negative electrode is the aforementioned integrated composite negative electrode for the all-solid-state battery.
[0034] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.
[0035] Example 1
[0036] Li6PS5Cl, nitrile rubber, alumina, and pentyl valerate were mixed in a weight ratio of 100:3:1:80 to obtain a first slurry; LATP, PVDF, carbon black, N-methylpyrrolidone, and micron-sized silicon were mixed in a weight ratio of 20:3:1:80:100 to obtain a second slurry; the second slurry was coated onto the surface of nickel-plated copper foil and dried at 120°C for 20 min to form a second electrode layer with a thickness of 20 µm; the first slurry was coated onto the surface of the second electrode layer and dried at 120°C for 10 h to form a first electrode layer with a thickness of 20 µm, thus obtaining an integrated composite negative electrode sheet.
[0037] Example 2
[0038] Li3PS4, styrene-butadiene-styrene rubber, silica, and xylene were mixed in a weight ratio of 100:2.5:2:85 to obtain the first slurry; Li7P3S 11 Fluorinated nitrile rubber, carbon nanotubes, ethyl benzoate, and porous silicon carbon are mixed in a weight ratio of 15:3:1.5:90:100 to obtain a second slurry. The second slurry is coated onto the surface of a nickel-plated copper foil and dried at 140°C for 10 min to form a second electrode layer with a thickness of 20 µm. The first slurry is coated onto the surface of the second electrode layer and dried at 110°C for 8 h to form a first electrode layer with a thickness of 25 µm, thus obtaining an integrated composite negative electrode sheet.
[0039] Example 3
[0040] Li6PS5Cl, nitrile rubber, alumina, and pentyl valerate were mixed in a weight ratio of 100:3:1:80 to obtain a first slurry; LATP, PVDF, carbon black, N-methylpyrrolidone, and micron-sized silicon were mixed in a weight ratio of 20:3:1:80:100 to obtain a second slurry; the second slurry was coated onto the surface of nickel-plated copper foil and dried at 120°C for 30 min to form a second electrode layer with a thickness of 20 µm; the first slurry was coated onto the surface of the second electrode layer and dried at 60°C for 12 h to form a first electrode layer with a thickness of 20 µm, thus obtaining an integrated composite negative electrode sheet.
[0041] Example 4
[0042] Li6PS5Cl, nitrile rubber, alumina, and pentyl valerate were mixed in a weight ratio of 100:3:1:80 to obtain a first slurry; LATP, PVDF, carbon black, N-methylpyrrolidone, and micron-sized silicon were mixed in a weight ratio of 20:3:1:80:100 to obtain a second slurry; the second slurry was coated onto the surface of nickel-plated copper foil and dried at 130℃ for 15 min to form a second electrode layer with a thickness of 20µm; the first slurry was coated onto the surface of the second electrode layer and dried at 120℃ for 8 h to form a first electrode layer with a thickness of 20µm, thus obtaining an integrated composite negative electrode sheet.
[0043] Example 5
[0044] Li6PS5Cl, nitrile rubber, alumina, and pentyl valerate were mixed in a weight ratio of 100:3:1:80 to obtain a first slurry; LATP, PVDF, carbon black, N-methylpyrrolidone, and micron-sized silicon were mixed in a weight ratio of 20:3:1:80:100 to obtain a second slurry; the second slurry was coated onto the surface of nickel-plated copper foil and dried at 150°C for 10 min to form a second electrode layer with a thickness of 20 µm; the first slurry was coated onto the surface of the second electrode layer and dried at 150°C for 8 h to form a first electrode layer with a thickness of 20 µm, thus obtaining an integrated composite negative electrode sheet.
[0045] Example 6
[0046] Li6PS5Cl, nitrile rubber, alumina, and pentyl valerate were mixed in a weight ratio of 100:3:1:80 to obtain a first slurry; LATP, PVDF, carbon black, N-methylpyrrolidone, and micron-sized silicon were mixed in a weight ratio of 20:3:1:80:100 to obtain a second slurry; the second slurry was coated onto the surface of nickel-plated copper foil and dried at 170℃ for 30 min to form a second electrode layer with a thickness of 20 µm; the first slurry was coated onto the surface of the second electrode layer and dried at 150℃ for 10 h to form a first electrode layer with a thickness of 20 µm, thus obtaining an integrated composite negative electrode sheet.
[0047] Example 7
[0048] The difference between Example 7 and Example 1 is that in the first slurry, the weight ratio of Li6PS5Cl, nitrile rubber, and alumina is 100:5:2; and in the second slurry, the weight ratio of LATP, PVDF, carbon black, and micronized silicon is 10:2:0.5:100.
[0049] Example 8
[0050] The difference between Example 8 and Example 1 is as follows: In the first slurry, the weight ratio of Li6PS5Cl, nitrile rubber, and alumina is 100:2:0.5; in the second slurry, the weight ratio of the total weight of LATP and Li3PS4 (weight ratio 1:1), PVDF, carbon black, and micronized silicon is 30:5:2:100.
[0051] Example 9
[0052] The difference between Example 9 and Example 1 is that the thickness of the first electrode layer is 10µm and the thickness of the second electrode layer is 10µm.
[0053] Example 10
[0054] The difference between Example 10 and Example 1 is that the thickness of the first electrode layer is 60µm and the thickness of the second electrode layer is 100µm.
[0055] Example 11
[0056] The difference between Example 11 and Example 1 is that the thickness of the first electrode layer is 20µm and the thickness of the second electrode layer is 10µm.
[0057] Example 12
[0058] The difference between Example 12 and Example 1 is that the thickness of the first electrode layer is 30µm and the thickness of the second electrode layer is 30µm.
[0059] Comparative Example 1
[0060] LATP, PVDF, carbon black, N-methylpyrrolidone, and micron-sized silicon were mixed in a mass ratio of 20:3:1:80:100 and coated onto one side of a nickel-plated copper foil. After pre-drying at 120°C for 20 min, a negative electrode sheet was obtained, with the negative electrode active material layer on the nickel-plated copper foil surface having a thickness of 20 µm. Li6PS5Cl, nitrile rubber, alumina, and pentyl valerate were mixed in a mass ratio of 100:3:1:80 and coated onto a release substrate. After drying at 120°C for 10 h, an electrolyte membrane layer with a thickness of 20 µm was obtained. This electrolyte membrane layer was then transferred to the surface of the negative electrode active material layer using a roller press to obtain a composite negative electrode sheet.
[0061] Comparative Example 2
[0062] Li7P3S 11 Fluorinated nitrile butadiene rubber, carbon nanotubes, ethyl benzoate, and porous silicon carbon were mixed in a mass ratio of 15:3:1.5:90:100 and coated onto the surface of a nickel-plated copper foil. After pre-drying at 140℃ for 10 min, a negative electrode sheet was obtained, wherein the thickness of the negative electrode active material layer formed on the surface of the nickel-plated copper foil was 25 µm. Li3PS4, styrene-butadiene-styrene rubber, silica, and xylene were mixed in a mass ratio of 100:2.5:2:85 and coated onto the surface of a release substrate. After drying at 110℃ for 8 h, an electrolyte membrane layer with a thickness of 25 µm was obtained. The electrolyte membrane layer was then transferred to the surface of the negative electrode active material layer using a roller press to obtain a composite negative electrode sheet.
[0063] The integrated composite anode prepared in the above embodiments was used to prepare an all-solid-state battery. The relevant performance of the prepared all-solid-state battery was tested, and the results are shown in Table 1. The preparation method of the all-solid-state battery includes the following steps:
[0064] The positive electrode active material NCM811, carbon nanotubes, Li6PS5Cl, styrene-butadiene-styrene rubber, and isoamyl isovalerate were mixed in a mass ratio of 85:1:12:2:80 and transferred to a spheroidizing ink can. The mixture was spheroidized at 300 rpm for 1 hour to obtain a positive electrode slurry. The slurry was then coated onto aluminum foil using a doctor blade, with the coating thickness controlled to adjust the NP ratio to approximately 1.1. The positive electrode material was then placed in an oven and dried at 120°C for 10 hours to obtain the positive electrode sheet used for battery assembly. The integrated composite negative electrode sheet or composite negative electrode sheet from the above examples or comparative examples, along with the positive electrode sheet prepared above, were cut and assembled into solid-state batteries. Cycle performance and rate performance were then tested.
[0065] The testing method includes: charging and discharging tests using a Xinwei charge-discharge tester under applied external pressure. After 0.1C activation, charging and discharging are performed at a 1C rate and a cutoff voltage of 2~4.2V. Each complete charge-discharge cycle is counted as one cycle. After 200 cycles, the capacity retention rate after 200 cycles is obtained by dividing the battery's discharge specific capacity by the discharge specific capacity of the first cycle.
[0066] Table 1
[0067]
[0068] Regarding the " / " in Table 1, it should be further explained that this symbol indicates that the corresponding all-solid-state battery is difficult to complete the test under these test conditions.
[0069] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:
[0070] Examples 1 to 12 describe the fabrication of all-solid-state batteries using the integrated composite anode proposed in this application. According to the data in Table 1, using the integrated composite anode proposed in this application in all-solid-state batteries can effectively improve the energy density, rate performance, and electrochemical stability of the all-solid-state batteries. In particular, controlling the various parameters in the integrated composite anode within their preferred ranges results in even better performance of the corresponding all-solid-state batteries.
[0071] Comparative Examples 1 and 2, which have similar negative electrode active material layer thickness and solid electrolyte layer thickness to the integrated composite negative electrode in Example 1, show significant differences in energy density, rate performance, and cycle stability compared to the embodiments of this application.
[0072] In summary, using an integrated composite anode with the above structure and composition in all-solid-state batteries can effectively improve the interfacial contact barrier between the anode and the electrolyte in all-solid-state batteries, as well as the resulting lithium dendrite growth problem. This can effectively improve the battery capacity and cycle stability, and enhance battery safety.
[0073] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. An integrated composite negative electrode for all-solid-state batteries, characterized in that, The integrated composite negative electrode includes a current collector and a first electrode layer and a second electrode layer located on one side of the current collector. The second electrode layer is disposed close to the current collector, and the first electrode layer is formed by coating the surface of the second electrode layer away from the current collector with the material of the first electrode layer. The material of the first electrode layer includes: a first solid electrolyte, a first binder, and additives; The materials of the second electrode layer include: a second solid electrolyte, a second binder, a negative electrode active material, and a conductive agent.
2. The integrated composite negative electrode for all-solid-state batteries according to claim 1, characterized in that, The weight ratio of the first solid electrolyte, the first binder, and the additive is 100:(2~5):(0.5~2); the weight ratio of the second solid electrolyte, the second binder, the conductive agent, and the negative electrode active material is (10~30):(2~5):(0.5~2):
100. Preferably, the weight ratio of the first solid electrolyte, the first binder and the additive is 100:(2~3):(0.5~1); the weight ratio of the second solid electrolyte, the second binder, the conductive agent and the negative electrode active material is (10~20):(2~3):(0.5~1):
100.
3. The integrated composite negative electrode for all-solid-state batteries according to claim 1, characterized in that, The thickness of the first electrode layer is 10~60µm, and the thickness of the second electrode layer is 10~100µm; Preferably, the thickness of the first electrode layer is 20~30µm, and the thickness of the second electrode layer is 10~30µm.
4. The integrated composite negative electrode for all-solid-state batteries according to any one of claims 1 to 3, characterized in that, In the material of the first electrode layer, the weight percentage of the first binder is 2-3%; and / or; In the material of the second electrode layer, the weight percentage of the second binder is 2-3%.
5. The integrated composite negative electrode for all-solid-state batteries according to any one of claims 1 to 3, characterized in that, The first solid electrolyte is a sulfide solid electrolyte; preferably, the sulfide solid electrolyte is selected from Li3PS4, Li 10 GeP2S 12 Li7P3S 11 One or more of the following solid electrolytes: Li6PS5Cl, Li6PS5Br, and Li6PS5I; and / or; The first adhesive is selected from one or more of styrene-butadiene-styrene rubber, hydrogenated styrene-butadiene-styrene rubber, nitrile rubber, hydrogenated nitrile rubber, styrene-butadiene rubber, and acrylate rubber; and / or the additive is selected from inorganic additives and / or organic additives; Preferably, the inorganic additive is selected from one or more of alumina, titanium dioxide, zirconium oxide, magnesium oxide, tin dioxide, silicon dioxide, boron nitride, or titanium phosphate; and / or, the organic additive is selected from one or more of cellulose nanocrystalline materials, polyimide nanocrystalline materials, and aramid nanocrystalline materials. Preferably, the particle size of the additive is ≤5µm; Preferably, the current collector is at least one of copper foil, nickel-plated copper foil, or tin-plated copper foil.
6. The integrated composite negative electrode for all-solid-state batteries according to any one of claims 1 to 3, characterized in that, The second solid electrolyte includes sulfide electrolytes and / or oxide electrolytes; Preferably, the second solid electrolyte comprises the sulfide electrolyte and the oxide electrolyte; Preferably, the sulfide solid electrolyte is selected from Li3PS4, Li 10 GeP2S 12 Li7P3S 11 One or more of the following solid electrolytes: Li6PS5Cl, Li6PS5Br, and Li6PS5I; Preferably, the oxide electrolyte is selected from one or more of LATP, LLZO, LLZTO, and LLTO; And / or; the second adhesive is selected from one or more of polyvinylidene fluoride, styrene-butadiene-styrene rubber, fluorinated styrene-butadiene rubber, and fluorinated nitrile rubber; And / or; the negative electrode active material is selected from one or more of silicon materials, silicon carbide materials, silicon suboxide materials, and graphite; And / or; the conductive agent is selected from one or more of carbon black, carbon nanotubes and carbon fiber materials.
7. The method for preparing an integrated composite negative electrode for an all-solid-state battery according to any one of claims 1 to 6, characterized in that, The preparation method includes the following steps: A first solid electrolyte, a first binder, and an additive are dispersed in a first organic solvent to obtain a first slurry; a second solid electrolyte, a second binder, a negative electrode active material, and a conductive agent are dispersed in a second organic solvent to obtain a second slurry; The second slurry is coated onto the surface of the current collector side and dried first to form the second electrode layer, thus obtaining the composite negative electrode precursor. The first slurry is coated onto the surface of the second electrode layer and dried in a second process to form the first electrode layer, thereby obtaining the integrated composite negative electrode.
8. The method for preparing an integrated composite negative electrode for all-solid-state batteries according to claim 7, characterized in that, The coating method is transfer coating or extrusion coating; Preferably, the current collector is selected from at least one of copper foil, nickel-plated copper foil, or tin-plated copper foil; Preferably, the first organic solvent is selected from amyl valerate and / or xylene; Preferably, the second organic solvent is selected from N-methylpyrrolidone and / or ethyl benzoate; Preferably, the solid content of the first slurry is 50-75%; Preferably, the solid content of the second slurry is 45-65%.
9. The method for preparing an integrated composite negative electrode for an all-solid-state battery according to claim 7 or 8, characterized in that, The first drying temperature is 120~150℃ and the time is 10~30min; the second drying temperature is 60~150℃ and the time is 8~12h. Preferably, the temperature of the first drying is 120~130℃ and the time is 10~15min; the temperature of the second drying is 80~120℃ and the time is 8~10h.
10. An all-solid-state battery, characterized in that, The all-solid-state battery includes a positive electrode and a negative electrode, wherein the negative electrode is an integrated composite negative electrode for an all-solid-state battery as described in any one of claims 1 to 6.