Lithium metal negative electrode material of solid-state battery, production process of lithium metal negative electrode material and solid-state battery

Abstract

The invention discloses a solid-state battery lithium metal negative electrode material, a production process thereof and a solid-state battery, and belongs to the technical field of solid-state battery electrode materials. The solid-state battery lithium metal negative electrode material comprises lithium metal; the porous carbon material has a communicated pore structure, and the lithium metal is accommodated in the pore structure on the surface of the porous carbon material to form a uniform composite material; the surface of the lithium metal is coated with the conductive polymer; the composite solid electrolyte comprises a sulfide-based solid electrolyte and a flexible electrolyte, and the surface of the sulfide-based solid electrolyte is covered with a polydopamine coating. According to the invention, the transmission path and the transmission rate of lithium ions can be optimized, and the transmission path and the transmission rate of the lithium ions are not influenced by relatively large volume change of lithium metal in the charging and discharging process.

Description

Technical Field

[0001] The present invention relates to the technical field of solid-state battery electrode materials, and particularly to a lithium metal negative electrode material for a solid-state battery, its production process, and a solid-state battery. Background Art

[0002] The definition of concentration polarization is that concentration polarization refers to the phenomenon that during an electrode reaction, due to the change in the concentration of reactants (such as lithium ions), the electrode potential deviates from the equilibrium potential. This phenomenon is particularly significant in lithium metal negative electrodes, especially under high-rate charge and discharge conditions. The reasons for concentration polarization of solid-state battery electrode materials are as follows: The ionic conductivity of solid electrolytes is lower than that of liquid electrolytes, which limits the transport rate of lithium ions. During high-rate charge and discharge, lithium ions may not reach the electrode surface in time, resulting in a change in the lithium ion concentration near the electrode surface, thus causing concentration polarization; The interfacial resistance between the lithium metal negative electrode and the solid electrolyte is relatively large, further limiting the transport of lithium ions and exacerbating concentration polarization; Lithium metal undergoes a large volume change during charge and discharge, which affects the transport path and rate of lithium ions, resulting in concentration polarization; During high-rate charge and discharge, the distribution of lithium ions in the electrode is uneven, forming a gradient distribution, which affects the performance and lifespan of the battery. Due to the above factors, concentration polarization will cause the electrode potential to deviate from the equilibrium potential, increase the internal resistance of the solid-state battery, reduce the discharge efficiency of the solid-state battery, and due to the limitation of the lithium ion transport rate, some electrode materials cannot be utilized, resulting in capacity attenuation of the solid-state battery, especially for thick electrodes under high discharge and high charge rates. Summary of the Invention

[0003] In order to overcome the deficiencies of the prior art, one of the objectives of the present invention is to provide a lithium metal negative electrode material for a solid-state battery, which can optimize the transport path and rate of lithium ions, and the transport path and rate of lithium ions are not affected by the large volume change that lithium metal undergoes during charge and discharge.

[0004] Another objective of the present invention is to provide a production process for the lithium metal negative electrode material of a solid-state battery, which can enable the porous carbon material to have a connected pore structure.

[0005] One of the objectives of the present invention is achieved by adopting the following technical solution: A lithium metal negative electrode material for a solid-state battery, comprising: Lithium metal; A porous carbon material, the porous carbon material having a connected pore structure, and the lithium metal is accommodated in the pore structure on the surface of the porous carbon material to form a uniform composite material; A conductive polymer, the surface of the lithium metal being coated with the conductive polymer; A composite solid electrolyte, the composite solid electrolyte including a sulfide-based solid electrolyte and a flexible electrolyte, a polydopamine coating covering the surface of the sulfide-based solid electrolyte.

[0006] Further, the sulfide-based solid electrolyte is Li 6 PS 5 Cl.

[0007] The second object of the present invention is achieved by the following technical solution: A production process of a lithium metal negative electrode material for a solid-state battery, including the following steps: S1. Dissolve polyethylene oxide and LiTFSI in a solvent to form a uniform mixed solution of a polyethylene oxide solution and LiTFSI, then prepare a sulfide-based solid electrolyte with a polydopamine coating on its surface, add it to the mixed solution of the polyethylene oxide solution and LiTFSI, and ultrasonically disperse it evenly for standby; S2. After obtaining a porous carbon material with a connected pore structure, immerse the porous carbon material with the connected pore structure in the mixed solution of the polyethylene oxide solution and LiTFSI, use the vacuum impregnation method, and by the way of evacuating and then restoring the atmospheric pressure, ensure that the solution infiltrates into the porous carbon material with the connected pore structure, so that the porous carbon material with the connected pore structure is completely filled with the mixed solution of the polyethylene oxide solution and LiTFSI, and dry the immersed porous carbon material with the connected pore structure for 2 h to ensure that the solvent completely volatilizes, obtaining a filled porous carbon material; Flexible substrate material: Flexible polymer (such as polyethylene oxide, PEO), used to improve flexibility and reduce the influence of hot pressing on the porosity; S3. Place the filled porous carbon material in a heating device, gradually raise the temperature to 120 °C, and control the heating rate at 5 °C / min to 10 °C / min to avoid thermal stress generated by the material due to heating; Holding time: Hold at 120 °C for 2 h to ensure cross-linking of polyethylene oxide molecular chains; After the holding ends, cool to room temperature of 25 °C to avoid cracks or structural damage generated by the material due to cooling, so that PEO and LiTFSI form the composite solid electrolyte, obtaining a solidified porous carbon material; S4. Place the solidified porous carbon material into a mold, then place the mold into a hot press, and hot press at a temperature of 150 °C and a pressure of 20 MPa for 1 h to ensure that the solidified porous carbon material is compacted, obtaining the lithium metal negative electrode material for the solid-state battery.

[0008] Further, in step S1, the method for preparing the sulfide-based solid electrolyte with a polydopamine coating on its surface includes the following steps: S11. Dissolve dopamine monomer (DA) in Tris-HCl buffer solution with a concentration of 50 mmol / L, and adjust the pH value of the Tris-HCl buffer solution to 8.5 to obtain a dopamine solution; S12. Dip-coat the sulfide-based solid electrolyte: Immerse the sulfide-based solid electrolyte in the dopamine solution to ensure surface contact, and add an oxidant (such as ammonium persulfate) to promote the oxidative polymerization of the dopamine monomer; S13. Reaction and curing: Let the dip-coated sulfide-based solid electrolyte stand at room temperature of 25 °C for 3 h to allow the self-polymerization reaction of the dopamine monomer on the surface of the sulfide-based solid electrolyte. After the reaction is completed, wash with deionized water or ethanol to remove the unreacted dopamine monomer, and dry for 2 h to remove excess moisture, thereby obtaining a sulfide-based solid electrolyte coated with a polydopamine coating.

[0009] Further, in step S2, the method for obtaining the porous carbon material with a connected pore structure includes the following steps: S21. Mix the porous carbon material with the lithium metal powder, and place the mixed material in a heating device, a muffle furnace. Under the protection of an inert gas, nitrogen, heat it to above the melting point of lithium, and the lithium metal will melt and penetrate into the pores of the porous carbon material; S22. Cooling: When the lithium metal is evenly distributed in the porous carbon material, cool it to re-solidify the lithium metal, and the lithium metal is accommodated in the pore structure on the surface of the porous carbon material.

[0010] The third object of the present invention is achieved by the following technical solution: A solid-state battery includes a negative electrode made of the lithium metal negative electrode material of the solid-state battery.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: The lithium metal anode material for solid-state batteries provided by the present invention. Porous carbon materials (such as activated carbon, carbon nanotubes, graphene) can provide micropores and nanopores, increasing the specific surface area. Pore structure. The pores of the porous carbon material are connected. Especially under the rigid structure of the porous carbon material, the pores of the porous carbon material can be completely filled, which can shorten the transmission path of lithium ions, reduce the diffusion distance of lithium ions in the electrode material, reduce the energy loss of lithium ions during transmission, improve the transmission rate, thereby reducing concentration polarization, and solving the problem that although the porous structure increases the specific surface area, it may also lead to uneven contact between the solid electrolyte and the electrode material, poor local contact, increase the interfacial resistance, reduce the transmission efficiency of lithium ions, and even may lead to an increase in the local current density, accelerating the formation of lithium dendrites. In the porous carbon material with a connected pore structure, the PEO-LiTFSI solution forms a uniform electrolyte network, and lithium ions can move in the pores through the movement of polymer segments, thereby achieving efficient lithium ion transmission; the pores of the porous carbon material are connected, which means that lithium ions can move from one pore to another, thereby achieving efficient lithium ion transmission throughout the electrode, and the connected porous structure can improve the wettability of the electrolyte, enabling the PEO-LiTFSI solution to fill the pores, further optimizing the lithium ion transmission path, and at the same time the uniformly distributed solid electrolyte can reduce the concentration gradient during lithium ion transmission, improving the battery performance. Sulfide-based solid electrolytes are solid electrolyte materials with high ionic conductivity, which can improve the transmission efficiency of lithium ions and reduce the transmission resistance. Combining the sulfide-based solid electrolyte with a flexible electrolyte to form a composite solid electrolyte further improves the lithium ion transmission rate, and utilizes the softness of the flexible electrolyte composite to alleviate the impact of volume expansion of the solid-state battery, so as to reduce the damage to the pore structure during the hot pressing process. Detailed implementation manners

[0012] The following combines specific embodiments to further describe the present invention. It should be noted that on the premise of no conflict, the following described embodiments or technical features can be combined arbitrarily to form new embodiments.

[0013] Example 1

[0014] The lithium metal anode material for solid-state batteries provided by this example includes: Lithium metal; Activated carbon as the porous carbon material. The activated carbon of the porous carbon material has a connected pore structure, and the lithium metal is accommodated in the pore structure on the surface of the activated carbon of the porous carbon material to form a uniform composite material; Conductive polymer, with the lithium metal surface coated with the conductive polymer; Composite solid electrolyte. The composite solid electrolyte includes a sulfide-based solid electrolyte Li 6 PS5 Cl and flexible electrolyte poly(ethylene oxide), sulfide-based solid electrolyte Li 6 PS 5 The surface of Cl is covered with a polydopamine coating.

[0015] This embodiment also provides a production process for the lithium metal negative electrode material of a solid-state battery, including the following steps: S1. Dissolve flexible electrolyte poly(ethylene oxide) and LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) in a solvent to form a uniform mixed solution of flexible electrolyte poly(ethylene oxide) and LiTFSI, and then prepare sulfide-based solid electrolyte Li 6 PS 5 Cl with a polydopamine coating on its surface, add it to the mixed solution of flexible electrolyte poly(ethylene oxide) and LiTFSI, and ultrasonically disperse it evenly for standby; S2. After obtaining activated carbon, a porous carbon material with a connected pore structure, immerse the porous carbon material with a connected pore structure in the mixed solution of flexible electrolyte poly(ethylene oxide) and LiTFSI. Using the vacuum impregnation method, by the way of evacuating and then restoring atmospheric pressure, ensure that the solution infiltrates into the porous carbon material with a connected pore structure, so that the connected pore structure of the porous carbon material activated carbon is completely filled with the mixed solution of flexible electrolyte poly(ethylene oxide) and LiTFSI. Dry the immersed porous carbon material activated carbon with a connected pore structure for 2 h to ensure that the solvent completely volatilizes, and obtain the filled porous carbon material activated carbon; Flexible electrolytes (such as poly(ethylene oxide), PEO) are used to improve flexibility and reduce the influence of hot pressing on porosity; S3. Place the filled porous carbon material activated carbon in a heating device, gradually raise the temperature to 120 °C, and control the heating rate at 5 °C / min to 10 °C / min to avoid thermal stress generated by the material due to heating; Holding time: Keep it at 120 °C for 2 h to ensure cross-linking of the flexible electrolyte poly(ethylene oxide) molecular chains; After the holding is over, cool it to room temperature of 25 °C to avoid cracks or structural damage caused by cooling of the material, and form a composite solid electrolyte of PEO and LiTFSI to obtain the cured porous carbon material activated carbon; S4. Put the cured porous carbon material activated carbon into a mold, then put the mold into a hot press, and then put the mold into a hot press. Hot press at a temperature of 150 °C and a pressure of 20 MPa for 1 h to ensure that the cured porous carbon material activated carbon is compacted, and obtain the lithium metal negative electrode material of the solid-state battery.

[0016] The essence of prelithiation: The core of prelithiation is to pre-introduce lithium ions into the negative electrode material by chemical or electrochemical methods, while LiTFSI itself is a lithium salt and cannot directly provide lithium ions.

[0017] Mechanism of LiTFSI: In the electrolyte, LiTFSI mainly protects the lithium metal anode by forming a stable SEI film, reducing the irreversible loss of lithium ions. It cannot directly compensate for the lithium ions lost due to the formation of the SEI film.

[0018] In step S1 of this embodiment, the method for preparing the sulfide-based solid electrolyte Li 6 PS 5 Cl with a polydopamine coating on its surface includes the following steps: S11. Dissolve dopamine monomer (DA) in Tris-HCl buffer solution with a concentration of 50 mmol / L, and adjust the pH value of the Tris-HCl buffer solution to 8.5 to obtain a dopamine solution. S12. Dip-coat the sulfide-based solid electrolyte Li 6 PS 5 Cl: Immerse the sulfide-based solid electrolyte Li 6 PS 5 Cl into the dopamine solution to ensure surface contact, and add an oxidant (such as ammonium persulfate) to promote the oxidative polymerization of dopamine monomer. S13. Reaction and curing: Leave the dip-coated sulfide-based solid electrolyte Li 6 PS 5 Cl standing at room temperature of 25°C for 3 h to allow the self-polymerization reaction of dopamine monomer to occur on the surface of the sulfide-based solid electrolyte Li 6 PS 5 Cl. After the reaction is completed, wash with deionized water or ethanol to remove the unreacted dopamine monomer, and dry for 2 h to remove the excess moisture, obtaining the sulfide-based solid electrolyte Li 6 PS 5 Cl coated with a polydopamine coating.

[0019] Ion transport path: The polydopamine coating can provide an additional transport path for lithium ions and reduce the resistance of ion transport. For example, the polydopamine coating can adsorb lithium ions and promote their migration at the interface, thereby improving the ionic conductivity.

[0020] Inhibiting anion migration: There is a strong adsorption effect between the polydopamine coating and TFSI⁻ anions, which can inhibit the migration of anions, thus creating a more stable environment for the transport of lithium ions.

[0021] Polydopamine (PDA) coating: Coating a thin layer of polydopamine on the surface of the sulfide electrolyte can significantly improve its compatibility with the PEO matrix and provide a stable ion transport channel.

[0022] In step S2 of this embodiment, the method for obtaining the porous carbon material with a connected pore structure includes the following steps: S21. Mix the porous carbon material activated carbon with lithium metal powder. Put the mixed material into a heating device, a muffle furnace, and heat it above the melting point of lithium under the protection of an inert gas, nitrogen. The lithium metal will melt and penetrate into the pores of the porous carbon material activated carbon. S22. Cooling: After the lithium metal is evenly distributed in the porous carbon material activated carbon, cool it to re-solidify the lithium metal, and the lithium metal is accommodated in the pore structure on the surface of the porous carbon material activated carbon.

[0023] In step S21, when mixing the porous carbon material with the lithium metal powder, the conductive polymer is polypyrrole (PPy). The method steps for coating polypyrrole on the surface of the lithium metal include: S211. Prepare a pyrrole monomer solution: Dissolve pyrrole monomer (Py) in a solvent (such as water or ethanol), and add ammonium persulfate (APS) as an oxidant to initiate the polymerization reaction. S212. Immerse the lithium metal: Immerse the lithium metal in the pyrrole monomer solution to ensure that the pyrrole monomer solution wets the lithium metal, and obtain the immersed lithium metal. S213. Initiate the polymerization reaction: Let the immersed lithium metal stand for 1.5 h to cause the pyrrole monomer to polymerize on the surface of the lithium metal, and the reaction generates a polypyrrole coating that uniformly coats the surface of the lithium metal. S214. Post-treatment: After the reaction is completed, wash the polypyrrole coating on the surface of the lithium metal with deionized water or ethanol multiple times to remove unreacted monomers and impurities, and perform a drying treatment to remove surface moisture.

[0024] Coat polypyrrole (PPy) on the surface of the porous lithium metal by an in-situ polymerization method to form a protective layer, which can reduce the direct contact between the lithium metal and the solid electrolyte, lower the interfacial resistance, and the protective layer can physically limit the growth of lithium dendrites, improving the safety of the battery; the protective layer can buffer the volume change of the lithium metal and improve the stability of the electrode.

[0025] Furthermore, the porous carbon material activated carbon has a connected pore structure. The specific implementation method steps include: S23. Mixing and dispersing: After the lithium metal is accommodated in the pore structure on the surface of the porous carbon material activated carbon, then add the template material nano-silica, and uniformly mix it by mechanical stirring to obtain a template material nano-silica mixture. S24. Perform carbonization treatment on the mixture. The carbonization treatment includes gradually heating to 600 °C in an inert gas atmosphere and holding for 2 h to form a stable network structure of the lithium metal and the porous carbon material, and obtain the carbonized mixture. S25. Immerse the carbonized mixture in a hydrofluoric acid (HF) or hydrochloric acid (HCl) solution, and remove the template material nano-silica by chemical etching to form a porous carbon material activated carbon with a connected pore structure.

[0026] A solid-state battery, the composition of which includes a negative electrode made of the solid-state battery lithium metal negative electrode material disclosed in Example 1.

[0027] Example 2

[0028] The solid-state battery lithium metal negative electrode material provided in this example includes: Lithium metal; Porous carbon material carbon nanotubes, the porous carbon material carbon nanotubes have a connected pore structure, and the lithium metal is accommodated in the pore structure on the surface of the porous carbon material carbon nanotubes to form a uniform composite material; Conductive polymer, the surface of the lithium metal is coated with the conductive polymer; Composite solid electrolyte, the composite solid electrolyte includes sulfide-based solid electrolyte Li 6 PS 5 Cl and flexible electrolyte polyethylene oxide, the surface of the sulfide-based solid electrolyte Li 6 PS 5 Cl is covered with a polydopamine coating.

[0029] Different from step S2 of Example 1, in step S2 of this example, the method for obtaining the porous carbon material with a connected pore structure includes the following steps: S21. Mix the porous carbon material carbon nanotubes with lithium metal powder, put the mixed material into a heating device, a muffle furnace, and heat it above the melting point of lithium under the protection of an inert gas, nitrogen, and the lithium metal will melt and penetrate into the pores of the porous carbon material carbon nanotubes; S22. Cooling: When the lithium metal is uniformly distributed in the porous carbon material carbon nanotubes, cool it to make the lithium metal re-solidify, and the lithium metal is accommodated in the pore structure on the surface of the porous carbon material carbon nanotubes.

[0030] In this example, the porous carbon material carbon nanotubes have a connected pore structure, and the specific implementation method steps include: S23. Mixing and dispersion: After the lithium metal is accommodated in the pore structure on the surface of the porous carbon material carbon nanotubes, then add the template material, nano-silica, and uniformly mix it by mechanical stirring to obtain a template material nano-silica mixture; S24. Carbonization treatment of the mixture, the carbonization treatment includes gradually heating to 800 °C in an inert gas atmosphere and holding for 3 h to make the lithium metal and the porous carbon material form a stable network structure to obtain a carbonized mixture; S25. Immerse the carbonized mixture in hydrofluoric acid (HF) or hydrochloric acid (HCl) solution, and remove the template material nano-silica by chemical etching to form porous carbon material carbon nanotubes with a connected pore structure.

[0031] This embodiment also provides a production process for the lithium metal negative electrode material of a solid-state battery, including the following steps: S1. Dissolve flexible electrolyte poly(ethylene oxide) and LiTFSI in a solvent to form a uniform mixed solution of flexible electrolyte poly(ethylene oxide) and LiTFSI. Then prepare a sulfide-based solid electrolyte Li 6 PS 5 Cl with a polydopamine coating on its surface, and add it to the mixed solution of flexible electrolyte poly(ethylene oxide) solution and LiTFSI. Ultrasonically disperse it evenly for standby; S2. After obtaining a porous carbon material carbon nanotube with a connected pore structure, immerse the porous carbon material with a connected pore structure in the mixed solution of flexible electrolyte poly(ethylene oxide) and LiTFSI. Use the vacuum impregnation method to ensure that the solution infiltrates into the porous carbon material with a connected pore structure by evacuating and then restoring atmospheric pressure, so that the connected pore structure of the porous carbon material carbon nanotube is completely filled with the mixed solution of flexible electrolyte poly(ethylene oxide) and LiTFSI. Dry the immersed porous carbon material carbon nanotube with a connected pore structure for 2 h to ensure complete volatilization of the solvent, and obtain a filled porous carbon material carbon nanotube; Flexible electrolyte (such as flexible electrolyte poly(ethylene oxide), PEO) is used to improve flexibility and reduce the impact of hot pressing on the porosity; S3. Place the filled porous carbon material carbon nanotube in a heating device, gradually raise the temperature to 120 °C, and control the heating rate at 5 °C / min to 10 °C / min to avoid thermal stress generated by the material due to heating; Holding time: Keep it at 120 °C for 2 h to ensure cross-linking of the flexible electrolyte poly(ethylene oxide) molecular chains; After the holding is completed, cool it to room temperature of 25 °C to avoid cracks or structural damage caused by the material due to cooling, and form a composite solid electrolyte of PEO and LiTFSI to obtain a solidified porous carbon material carbon nanotube; S4. Put the solidified porous carbon material carbon nanotube into a mold, and then put the mold into a hot press. Hot press it at a temperature of 150 °C and a pressure of 20 MPa for 1 h to ensure compaction of the solidified porous carbon material carbon nanotube, and obtain the lithium metal negative electrode material of the solid-state battery. Further processing, such as grinding, cutting, etc., can be carried out according to needs to form the required electrode shape.

[0032] A solid-state battery, the composition of which includes a negative electrode made of the lithium metal negative electrode material of the solid-state battery disclosed in Example 2.

[0033] Example 3

[0034] The lithium metal negative electrode material provided in this embodiment includes: Lithium metal; Porous carbon material graphene. The porous carbon material graphene has a connected pore structure, and lithium metal is accommodated in the pore structure on the surface of the porous carbon material graphene to form a uniform composite material; Conductive polymer, with lithium metal surface coated with conductive polymer; Composite solid electrolyte. The composite solid electrolyte includes sulfide-based solid electrolyte Li 6 PS 5 PS 6 Cl and flexible electrolyte polyethylene oxide. The surface of the sulfide-based solid electrolyte Li 5 Cl is covered with a polydopamine coating.

[0035] Different from step S2 of Example 1, in step S2 of this example, the method for obtaining a porous carbon material with a connected pore structure includes the following steps: S21. Mix the porous carbon material graphene with lithium metal powder, put the mixed material into a heating device, a muffle furnace, and heat it above the melting point of lithium under the protection of inert gas nitrogen. The lithium metal will melt and penetrate into the pores of the porous carbon material graphene; S22. Cooling: When the lithium metal is evenly distributed in the porous carbon material graphene, cool it to re-solidify the lithium metal, and the lithium metal is accommodated in the pore structure on the surface of the porous carbon material graphene.

[0036] In this example, the porous carbon material graphene has a connected pore structure. The specific implementation method steps include: S23. Mixing and dispersion: After the lithium metal is accommodated in the pore structure on the surface of the porous carbon material graphene, then add template material nano-silica, and uniformly mix by mechanical stirring to obtain a template material nano-silica mixture; S24. Perform carbonization treatment on the mixture. The carbonization treatment includes gradually heating to 1000 °C in an inert gas atmosphere and holding for 5 h to make the lithium metal and the porous carbon material form a stable network structure, obtaining a carbonized mixture; among them, high-temperature carbonization can fix the structures of the porous carbon material graphene and the template material nano-silica to form a stable network structure, and this network structure helps to improve the mechanical properties and electrochemical stability of the porous carbon material.

[0037] After the template material nano-silica SiO 2 nano-particles are mixed and then carbonized, the template material nano-silica will fill into the pores of the composite, further stabilizing the composite structure, and removing the template material nano-silica, making the lithium metal and the porous carbon material graphene form a stable network structure.

[0038] S25. Immerse the carbonized mixture in a hydrofluoric acid (HF) or hydrochloric acid (HCl) solution, and remove the template material nano-silica by chemical etching to form a porous carbon material graphene with a connected pore structure.

[0039] This embodiment also provides a production process for the lithium metal negative electrode material of a solid-state battery, including the following steps: S1. Dissolve the flexible electrolyte poly(ethylene oxide) and LiTFSI in a solvent to form a uniform mixed solution of the flexible electrolyte poly(ethylene oxide) solution of LiTFSI, and then prepare a sulfide-based solid electrolyte Li 6 PS 5 Cl coated on the surface, and add it to the mixed solution of the flexible electrolyte poly(ethylene oxide) solution of LiTFSI, and disperse it evenly by ultrasonic treatment for standby; S2. After obtaining the porous carbon material graphene with a connected pore structure, immerse the porous carbon material with the connected pore structure in the mixed solution of the flexible electrolyte poly(ethylene oxide) and LiTFSI. Using the vacuum impregnation method, by the way of evacuating and then restoring the atmospheric pressure, ensure that the solution infiltrates into the porous carbon material with the connected pore structure, so that the connected pore structure of the porous carbon material graphene is completely filled with the mixed solution of the flexible electrolyte poly(ethylene oxide) and LiTFSI. Dry the immersed porous carbon material graphene with the connected pore structure for 2 h to ensure that the solvent completely volatilizes to obtain the filled porous carbon material graphene; Flexible substrate material: Flexible polymer (such as flexible electrolyte poly(ethylene oxide), PEO), which is used to improve flexibility and reduce the influence of hot pressing on the porosity; S3. Place the filled porous carbon material graphene in a heating device, gradually raise the temperature to 120 °C, and control the heating rate at 5 °C / min to 10 °C / min to avoid thermal stress generated by the material due to heating; Holding time: Keep it at 120 °C for 2 h to ensure the cross-linking of the flexible electrolyte poly(ethylene oxide) molecular chains; After the holding is completed, cool it to room temperature of 25 °C to avoid cracks or structural damage generated by the material due to cooling, so that PEO and LiTFSI form a composite solid electrolyte to obtain the cured porous carbon material graphene; S4. Put the cured porous carbon material graphene into a mold, and then put the mold into a hot press, and hot press it at a temperature of 150 °C and a pressure of 20 MPa for 1 h to ensure the compaction of the cured porous carbon material graphene, and obtain the lithium metal negative electrode material of the solid-state battery.

[0040] A solid-state battery, the composition of which includes a negative electrode made of the lithium metal negative electrode material of the solid-state battery disclosed in Example 3.

[0041] The above embodiments are only the preferred embodiments of the present invention, and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention fall within the scope of protection required by the present invention.

Claims

1. A solid-state battery lithium metal negative electrode material, characterized in that: include Lithium metal; A porous carbon material having a connected pore structure, wherein the lithium metal is contained in the pore structure on the surface of the porous carbon material to form a uniform composite material; Conductive polymer, the surface of the lithium metal is coated with the conductive polymer; A composite solid electrolyte, comprising a sulfide-based solid electrolyte and a flexible electrolyte, wherein the surface of the sulfide-based solid electrolyte is covered with a polydopamine coating; micropores and nanopores can be provided to increase the specific surface area.

2. The solid-state battery lithium metal negative electrode material according to claim 1, characterized in that The sulfide-based solid electrolyte is Li6PS5Cl.

3. The solid-state battery lithium metal negative electrode material according to claim 1, characterized in that The porous carbon material is one of activated carbon, carbon nanotubes and graphene.

4. The solid-state battery lithium metal negative electrode material according to claim 1, characterized in that The flexible electrolyte is selected from polyethylene oxide.

5. The production process of the solid-state battery lithium metal negative electrode material according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, dissolving polyethylene oxide and LiTFSI in a solvent to form a uniform mixed solution of polyethylene oxide solution and LiTFSI, then preparing a sulfide-based solid electrolyte with a polydopamine coating on the surface, adding the sulfide-based solid electrolyte to the mixed solution of polyethylene oxide solution and LiTFSI, and uniformly dispersing the sulfide-based solid electrolyte by ultrasonication for standby use; S2. After obtaining the porous carbon material with interconnected pore structure, immerse the porous carbon material with interconnected pore structure in a mixed solution of the polyethylene oxide solution and LiTFSI, and use a vacuum impregnation method to restore the atmospheric pressure by evacuating the vacuum to ensure that the solution infiltrates the porous carbon material with interconnected pore structure, so that the porous carbon material with interconnected pore structure is completely filled with the mixed solution of the polyethylene oxide solution and LiTFSI, and dry the porous carbon material with interconnected pore structure after immersion for 2 hours to ensure that the solvent is completely volatilized to obtain a filled porous carbon material; S3, placing the filled porous carbon material in a heating device, gradually heating it to 120° C., and controlling the heating rate at 5° C. / min to 10° C. / min to avoid thermal stress in the material due to heating; Insulation time: 2 hours at 120°C to ensure cross-linking of polyethylene oxide molecular chains; After the heat preservation is completed, the material is cooled to room temperature of 25° C. to avoid cracks or structural damage caused by cooling, so that the polyethylene oxide and LiTFSI form the composite solid electrolyte to obtain a solidified porous carbon material; S4. Place the solidified porous carbon material into a mold, then place the mold into a hot press, and hot press at a temperature of 150° C. and a pressure of 20 MPa for 1 hour to ensure that the solidified porous carbon material is compacted to obtain the solid-state battery lithium metal negative electrode material.

6. The production process of the solid-state battery lithium metal negative electrode material according to claim 5, characterized in that: In step S1, the method for preparing a sulfide-based solid electrolyte having a surface covered with a polydopamine coating comprises the following steps: S11, dissolving the dopamine monomer in a Tris-HCl buffer having a concentration of 50 mmol / L, and adjusting the pH value of the Tris-HCl buffer to 8.5 to obtain a dopamine solution; S12, dip-coating a sulfide-based solid electrolyte: immersing the sulfide-based solid electrolyte into the dopamine solution to ensure surface contact, and adding an oxidant, ammonium persulfate, to promote oxidative polymerization of the dopamine monomer; S13, reaction and curing: the dip-coated sulfide-based solid electrolyte is allowed to stand at room temperature of 25°C for 3 hours to allow the dopamine monomer to undergo self-polymerization reaction on the surface of the sulfide-based solid electrolyte. After the reaction is completed, it is washed with deionized water or ethanol to remove the unreacted dopamine monomer, and dried for 2 hours to remove excess water to obtain a sulfide-based solid electrolyte coated with a polydopamine coating.

7. The production process of the solid-state battery lithium metal negative electrode material according to claim 5, characterized in that: In step S2, the method for obtaining a porous carbon material with a connected pore structure comprises the following steps: S21, mixing the porous carbon material with the lithium metal powder, placing the mixed material into a muffle furnace of a heating device, and heating to a temperature above the melting point of lithium under the protection of an inert gas, nitrogen, so that the lithium metal will melt and penetrate into the pores of the porous carbon material; S22, cooling: after the lithium metal is evenly distributed in the porous carbon material, cooling is performed to re-solidify the lithium metal. The lithium metal is accommodated in the pore structure on the surface of the porous carbon material.

8. The production process of the solid-state battery lithium metal negative electrode material according to claim 7, characterized in that: The porous carbon material has a connected pore structure, and the specific implementation method steps include: S23, mixing and dispersing: after the lithium metal is contained in the pore structure on the surface of the porous carbon material, a template material is then added, and the mixture is uniformly mixed by mechanical stirring to obtain a template material mixture; S24, carbonizing the mixture, wherein the carbonization treatment comprises gradually raising the temperature to 600° C. to 1000° C. in an inert gas atmosphere, and keeping the temperature for 2 h to 5 h, so that the lithium metal and the porous carbon material form a stable network structure, thereby obtaining a carbonized mixture; S25, immersing the carbonized mixture in a hydrofluoric acid or hydrochloric acid solution, removing the template material by chemical etching, and forming the porous carbon material with interconnected pore structure.

9. The production process of the solid-state battery lithium metal negative electrode material according to claim 7, characterized in that: Step S21, mixing the porous carbon material with the lithium metal powder, wherein the conductive polymer is polypyrrole, and the method steps of coating the polypyrrole on the surface of the lithium metal include: S211, preparing a pyrrole monomer solution: dissolving the pyrrole monomer in a solvent, ethanol, and adding an oxidizing agent, ammonium persulfate, to initiate a polymerization reaction; S212, impregnating lithium metal: immersing the lithium metal in the pyrrole monomer solution, ensuring that the pyrrole monomer solution infiltrates the lithium metal to obtain the impregnated lithium metal; S213, initiating a polymerization reaction: leaving the impregnated lithium metal to stand for 1.5 hours to allow the pyrrole monomer to undergo a polymerization reaction on the surface of the lithium metal to generate a polypyrrole coating that is uniformly coated on the surface of the lithium metal; S214, post-treatment: After the reaction is completed, the polypyrrole coating coated on the surface of the lithium metal is washed with deionized water or ethanol for multiple times to remove unreacted monomers and impurities, and dried to remove surface moisture.

10. A solid-state battery, characterized in that: A negative electrode comprising the solid-state battery lithium metal negative electrode material according to any one of claims 1 to 4.