Novel lithium-containing composite solid-state negative electrode, preparation method thereof and semi-solid lithium-sulfur battery

Abstract

The application discloses a novel lithium-containing composite solid-state negative electrode, a preparation method thereof and a semi-solid lithium-sulfur battery. The novel lithium-containing composite solid-state negative electrode comprises, in sequence, a current collecting layer, a negative active material layer and a continuous solid electrolyte layer, and the negative active material layer comprises a porous carbon skeleton structure formed by a carbon material, lithium metal material distributed in the interior and surface of the porous carbon skeleton structure and lithium metal material coated with a solid electrolyte. The novel lithium-containing composite solid-state negative electrode with a surface modification layer has good stability, can realize uniform deposition of lithium ions and inhibit growth of lithium dendrites, meanwhile, interaction between liquid electrolyte and the negative electrode is isolated, and side reactions between the electrolyte and the electrode are effectively reduced; the semi-solid battery assembled by using the electrode sheet can effectively inhibit reduction and damage of dissolved polysulfides in the sulfur-carbon positive electrode on the negative electrode surface, and improve the cycle life and capacity performance of the battery.

Description

Technical Field

[0001] This invention relates to a novel solid-state negative electrode sheet, and more particularly to a novel lithium-containing composite solid-state negative electrode, its preparation method, and a semi-solid-state lithium-sulfur battery, belonging to the field of electrode structure and solid-state lithium battery technology. Background Technology

[0002] Traditional commercial lithium-ion batteries have limited energy density, making it increasingly difficult to meet the growing demand for energy storage systems. Lithium-sulfur batteries, as a new type of energy storage system with both extremely high energy density (theoretical specific energy 2860Wh / kg) and good safety performance, have become a potential direction for battery development. However, there are still many problems in the practical application of lithium-sulfur batteries, such as: (1) During cycling, sulfur cathodes produce a large number of polysulfides, which dissolve in the electrolyte and migrate to the anode, reacting on the anode surface, affecting the cycle performance of the battery and causing irreversible capacity loss; (2) Electrolyte components are reduced and decomposed on the anode surface, and further react with the anode to generate an unstable solid electrolyte intermediate phase. This intermediate phase will be stress-damaged with the volume change of the anode during electrochemical cycling, continuously consuming electrolyte and deteriorating the cycle performance of the battery; (3) The unstable solid electrolyte intermediate phase will also lead to uneven deposition of lithium ions, resulting in the rapid formation of lithium dendrites, which are very easy to puncture the separator and induce internal short circuits in the battery. Therefore, it is essential to take measures to construct a stable lithium-sulfur battery anode and suppress side reactions generated by the liquid electrolyte during cycling.

[0003] To suppress side reactions between the liquid electrolyte and the negative electrode, and improve battery capacity and cycle life, the most effective existing techniques for modifying the negative electrode involve pre-constructing a protective layer. For example, patent CN111540905A reports a negative electrode protective layer containing lithiophilic, reducing, and electronegative units. This is achieved by repeatedly mixing and reacting a precursor solution on the negative electrode surface, followed by solvent removal, to construct a protective layer and improve battery cycle life. Another example is patent CN105702914A, which reports a method of pre-treating lithium-ion negative electrodes with double-bonded organic compounds. By controlling the reaction time, a certain thickness of organic polymer compound is generated on the negative electrode surface to reduce the shuttle effect of polysulfide ions and passivation of the negative electrode surface. Finally, patent CN105552307A reports a modified negative electrode sheet obtained by mixing lithium powder, carbon materials, binders, and solvents, creating a slurry, and then coating it onto nickel foam to evaporate the solvent, thereby improving battery cycle life and cycle efficiency. In addition, there are other methods to improve the electrode, such as adding additives and using lithium compounds to encapsulate lithium powder. However, these processes are quite complex and not conducive to industrial production. Summary of the Invention

[0004] The main objective of this invention is to provide a novel lithium-containing composite solid anode and its preparation method, so as to overcome the shortcomings of the prior art.

[0005] Another objective of this invention is to provide a semi-solid lithium-sulfur battery and a method for preparing the same.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0007] This invention provides a novel lithium-containing composite solid-state anode, which sequentially comprises: a current collector layer, an anode active material layer, and a continuous solid electrolyte layer. The solid electrolyte layer is composed of a continuous polymer solid electrolyte and a lithium salt, and is uniformly coated on the surface of the anode active material layer. The anode active material layer includes a porous carbon framework structure formed of carbon material, lithium metal material distributed inside the porous carbon framework structure, and lithium metal material coated with solid electrolyte distributed on the surface of the porous carbon framework structure.

[0008] In some embodiments, the negative electrode active material layer includes a porous carbon framework structure formed of carbon material, lithium metal material and binder distributed inside the porous carbon framework structure, and lithium metal material coated with polymer solid electrolyte distributed on the surface of the porous carbon framework structure. The lithium metal material and binder are distributed and filled in the pores contained in the porous carbon framework structure, and the lithium metal material coated with solid electrolyte is continuously coated on the surface of the porous carbon framework structure and the current collector layer.

[0009] In some embodiments, the carbon material includes any one or a combination of two or more of the following: sheet-like carbon material, small-particle conductive carbon material, one-dimensional conductive carbon material, and microporous carbon material.

[0010] This invention also provides a method for preparing the aforementioned novel lithium-containing composite solid-state anode, comprising:

[0011] Provides a mixed slurry containing carbon materials, binders, and solid electrolytes, which may or may not be added;

[0012] The mixed slurry is applied to the current collector layer and dried to form a porous carbon electrode, which has a porous carbon framework structure formed of carbon material.

[0013] Lithium metal material is loaded onto the surface of the carbon material contained in the porous carbon framework structure of a carbon porous electrode; and...

[0014] A polymer precursor solution containing polymerizable polymer monomers and lithium salts is provided, and a carbon porous electrode loaded with lithium metal material is brought into full contact with the polymer precursor solution. Then, a polymerization reaction is carried out under the action of an initiator, and a continuous solid electrolyte layer is formed on the surface of the carbon porous electrode loaded with lithium metal material, thereby obtaining the novel lithium-containing composite solid anode.

[0015] Alternatively, an organic solution containing a polymer solid electrolyte and a lithium salt is provided, allowing the carbon porous electrode loaded with lithium metal material to come into full contact with the organic solution. After drying to remove the solvent, a continuous solid electrolyte layer is formed on the surface of the carbon porous electrode loaded with lithium metal material, thereby obtaining the novel lithium-containing composite solid anode.

[0016] In some embodiments, the preparation method includes: immersing the carbon porous electrode in an organic solution containing lithium metal material, or loading lithium metal material onto the surface of the carbon material contained in the porous carbon framework structure of the carbon porous electrode by at least one of vapor deposition, hot melt composite, or lithium electroplating.

[0017] This invention also provides a semi-solid lithium-sulfur battery, which includes a sulfur-carbon positive electrode, a negative electrode, an electrolyte, a separator disposed between the sulfur-carbon positive electrode and the negative electrode, and a shell, wherein the negative electrode adopts the aforementioned novel lithium-containing composite solid negative electrode.

[0018] The present invention also provides a method for preparing the aforementioned semi-solid lithium-sulfur battery, which includes: assembling a sulfur-carbon cathode, a separator, and a novel lithium-containing composite solid anode, and injecting an electrolyte to obtain the semi-solid lithium-sulfur battery.

[0019] Compared with the prior art, the beneficial effects of the present invention include:

[0020] 1) The novel lithium-containing composite solid anode with a surface modification layer provided by this invention has good stability, can achieve uniform deposition of lithium ions and suppress the growth of lithium dendrites, and at the same time isolates the interaction between the liquid electrolyte and the anode, effectively reducing the side reactions between the electrolyte and the electrode; at the same time, the solid electrolyte layer can isolate the contact between the electrolyte and the electrolyte, suppress the decomposition and side reactions of the electrolyte during the charging and discharging process, and can construct a stable artificial solid electrolyte intermediate phase;

[0021] 2) The semi-solid battery assembled using this electrode has excellent capacity utilization and long cycle performance. It can effectively suppress the reduction and destruction of polysulfides dissolved in the sulfur-carbon cathode on the surface of the anode, thereby improving the cycle life and capacity utilization performance of the battery. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of a novel lithium-containing composite solid negative electrode sheet in a typical embodiment of the present invention. Detailed Implementation

[0024] To address the shortcomings of existing technologies, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention, which mainly provides a novel method for preparing a negative electrode sheet and its corresponding application in a novel semi-solid lithium-sulfur battery. This novel negative electrode consists of a current collector, carbon material, lithium or a lithium alloy, a solid electrolyte, and a binder. The carbon material is loaded onto the current collector to form a porous carbon structure. Then, lithium metal or a lithium-containing alloy is attached to the surface of the porous carbon structure through methods such as vapor deposition, hot-melt bonding, or electroplating to form a lithium-carbon composite negative electrode. Finally, a layer of solid electrolyte is modified on the surface of the above negative electrode by means of polymerizing polymer monomers, dissolving the polymer coating, and evaporating the solvent, thus producing a composite solid negative electrode sheet. This electrode sheet, combined with a positive electrode, electrolyte, and separator, can be used to fabricate a semi-solid lithium-sulfur battery. The negative electrode material with a surface modification layer used in this invention has good stability, enabling uniform deposition of lithium ions and inhibiting the growth of lithium dendrites. Simultaneously, it isolates the interaction between the liquid electrolyte and the negative electrode, effectively reducing side reactions between the electrolyte and the electrode. Semi-solid-state batteries assembled using this electrode exhibit excellent capacity utilization and long cycle performance.

[0025] The following will provide a further explanation of the technical solution, its implementation process, and its principles.

[0026] Please see Figure 1 As shown, one aspect of the present invention provides a novel lithium-containing composite solid-state anode that sequentially comprises: a current collector layer, an anode active material layer, and a continuous solid electrolyte layer. The solid electrolyte layer is composed of a continuous polymer solid electrolyte and a lithium salt, and is uniformly coated on the surface of the anode active material layer. The anode active material layer includes a porous carbon framework structure formed of carbon material, lithium metal material distributed inside the porous carbon framework structure, and lithium metal material coated with solid electrolyte distributed on the surface of the porous carbon framework structure.

[0027] In some preferred embodiments, the negative electrode active material layer includes a porous carbon framework structure formed of carbon material, lithium metal material and binder distributed inside the porous carbon framework structure, and lithium metal material coated with polymer solid electrolyte distributed on the surface of the porous carbon framework structure. The lithium metal material and binder are distributed and filled in the pores contained in the porous carbon framework structure, and the lithium metal material coated with solid electrolyte is continuously coated on the surface of the porous carbon framework structure and the current collector layer.

[0028] Furthermore, the novel lithium-containing composite solid-state negative electrode sheet of the present invention comprises a current collector, a carbon material, lithium metal or lithium alloy or lithium-containing compound, a binder, and a continuous solid electrolyte layer. The continuous solid electrolyte layer uniformly coats the surface of the negative electrode active material and has the properties of electronic insulation but ion conduction.

[0029] In some preferred embodiments, the thickness of the negative electrode active material layer is 50–200 μm, preferably 80–130 μm.

[0030] In some preferred embodiments, the ratio of the thickness of the lithium metal material coated with the solid electrolyte to the thickness of the negative electrode active material layer is 50-100:100, preferably 90-100:100.

[0031] In some preferred embodiments, the carbon material includes any two or more combinations of sheet-like carbon materials, small-particle conductive carbon materials, one-dimensional conductive carbon materials, microporous carbon materials, etc., but is not limited thereto.

[0032] Furthermore, the carbon material comprises two or more of the following: sheet-like carbon such as sheet graphite or multilayer graphene; small-particle conductive carbon such as carbon black; one-dimensional conductive carbon materials such as carbon nanotubes; and microporous carbon materials. Other conductive materials may also be used to replace the carbon material.

[0033] In some preferred embodiments, the sheet-like carbon material has a sheet-like structure, particularly preferably including sheet-like graphite and / or multilayer graphene, but is not limited thereto.

[0034] Furthermore, the thickness of the sheet carbon material is 1 nm to 1 μm, preferably 5 nm to 50 nm, and the planar size is 100 nm to 50 μm, preferably 200 nm to 10 μm.

[0035] Furthermore, the one-dimensional conductive carbon material includes, but is not limited to, carbon nanotubes.

[0036] Furthermore, the diameter of the carbon nanotube is 5 nm to 5 μm, preferably 10 nm to 500 nm, and the length is 500 nm to 50 μm, preferably 2 to 10 μm.

[0037] Furthermore, the small particulate conductive carbon material includes, but is not limited to, carbon black particles.

[0038] Furthermore, the size of the small conductive carbon particles is below 1 μm, preferably below 100 nm. Specifically, the size of the carbon black particles is generally controlled below 100 nm, and other small conductive particles should normally be controlled below 1 μm.

[0039] Furthermore, the size of the microporous carbon material is generally controlled below 100 nm.

[0040] In some preferred embodiments, the lithium metal material includes any one or a combination of two or more of lithium metal, lithium alloys containing lithium, and lithium compounds containing lithium, but is not limited thereto.

[0041] Furthermore, the lithium-containing alloy material includes any one or a combination of two or more of lithium-silicon alloys, lithium-tin alloys, and lithium-magnesium alloys, but is not limited thereto.

[0042] Furthermore, the lithium-containing compound includes, but is not limited to, lithium sulfide and / or lithium selenide.

[0043] In some preferred embodiments, the lithium metal material comprises 50–95 wt% of the entire novel lithium-containing composite solid anode.

[0044] In some preferred embodiments, the lithium metal material (such as lithium metal or lithium alloy) in the novel lithium-containing composite solid anode can be continuously covered on the surface of the conductive carbon material and the current collector, but the thickness should be controlled below 1 mm, preferably 5 nm to 1 mm, and especially preferably below 100 μm, particularly preferably 5 nm to 100 μm.

[0045] Furthermore, the lithium metal material can also be distributed in particulate form, and the particle size of the lithium metal material particles is 10 nm to 10 μm, preferably controlled within 100 nm to 1 μm.

[0046] In some preferred embodiments, the solid electrolyte coating on the surface of the lithium metal material containing the solid electrolyte includes an inorganic solid electrolyte, preferably including an oxide solid electrolyte and / or a sulfide solid electrolyte, for example, Li... 10 GeP2S 12 Li 6.75 La3Zr 1.75 Ta 0.25 O 12 Li7La3Zr2O 12 Solid electrolyte powders, but not limited to these.

[0047] In some preferred embodiments, the porosity of the novel lithium-containing composite solid anode is generally below 60%, and preferably below 40%.

[0048] In some preferred embodiments, the carbon material accounts for 0.5 to 5% of the total mass of the novel lithium-containing composite solid anode excluding the current collector, and the binder accounts for 0.5 to 5% of the total mass of the novel lithium-containing composite solid anode excluding the current collector.

[0049] Furthermore, the adhesive may include any one or a combination of two or more of polyvinylidene fluoride, styrene-butadiene rubber latex, hydroxymethyl cellulose, polyacrylic acid, polyacrylonitrile, polyacrylate, etc., but is not limited thereto.

[0050] In some preferred embodiments, the current collector layer includes a porous current collector, preferably a porous metal foil (e.g., it may include copper, nickel, stainless steel, etc.), or it may be nickel foam, copper foam, polymer fiber cloth or non-woven cloth with metal plating on the surface, or any one or more combinations of carbon fiber cloth, but is not limited thereto.

[0051] Furthermore, the thickness of the current collector layer is 50–500 μm.

[0052] In some preferred embodiments, the thickness of the solid electrolyte layer covering the surface of the negative electrode active material layer is 10 nm to 10 μm, preferably 20 nm to 2 μm.

[0053] In some preferred embodiments, the polymeric solid electrolyte is obtained by polymerization of at least polymerizable polymeric monomers.

[0054] Furthermore, the polymer solid electrolyte in the solid electrolyte layer is formed by polymerizing a polymer precursor solution containing polymerizable polymer monomers and lithium salts on the surface of a carbon porous electrode using an initiator, or by evaporating the solvent from an organic solution containing already polymerized polymer solid electrolytes and lithium salts on the surface of a carbon porous electrode.

[0055] In some preferred embodiments, the polymerizable polymer monomer includes any one or a combination of two or more of polyvinylidene fluoride polymer monomers, polyethylene oxide polymer monomers, polycarbonate polymer monomers, polyether polymer monomers, polyacrylonitrile polymer monomers, and polyionic liquid monomers. For example, it may preferably be any one or a combination of two or more of polyvinylidene fluoride monomers, polyethylene glycol diacrylate, 1,3-dioxolane, tetraethylene glycol diacrylate monomers, caprolactone, vinylimidazolium bis(trifluoromethanesulfonyl)imide, 1,2,7,8-diepoxyoctane, butyl glycidyl ether, and lithium 1-[3-(methacryloyloxy)propylsulfonyl]-1-(trifluoromethylsulfonyl)imide, but is not limited thereto.

[0056] In some preferred embodiments, the polymer solid electrolyte includes any one or a combination of two or more of the following: polyvinylidene fluoride polymer, polyethylene oxide polymer, polycarbonate polymer, polyether polymer, polyacrylonitrile polymer, polyionic liquid polymer, etc. For example, it may preferably be any one or a combination of two or more of the following: polyvinylidene fluoride, poly(1-vinyl-3-butylimidazoline bis(trifluoromethanesulfonyl)imide-co-ethylene glycol diacrylate), polyethylene carbonate, etc., but is not limited thereto.

[0057] Furthermore, the lithium salt includes any one or more combinations of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide (e.g., 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide), lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium di(oxalate)borate, lithium di(fluorooxalate)borate, etc., but is not limited thereto.

[0058] Another aspect of the present invention provides a method for preparing the aforementioned novel lithium-containing composite solid-state anode, comprising:

[0059] Provides a mixed slurry containing carbon materials, binders, and solid electrolytes, which may or may not be added;

[0060] The mixed slurry is applied to the current collector layer and dried to form a porous carbon electrode, which has a porous carbon framework structure formed of carbon material.

[0061] Lithium metal material is loaded onto the surface of the carbon material contained in the porous carbon framework structure of a carbon porous electrode; and...

[0062] A polymer precursor solution containing polymerizable polymer monomers and lithium salts is provided, and a carbon porous electrode loaded with lithium metal material is brought into full contact with the polymer precursor solution. Then, a polymerization reaction is carried out under the action of an initiator, and a continuous solid electrolyte layer is formed on the surface of the carbon porous electrode loaded with lithium metal material, thereby obtaining the novel lithium-containing composite solid anode.

[0063] Alternatively, an organic solution containing a polymer solid electrolyte and a lithium salt is provided, allowing the carbon porous electrode loaded with lithium metal material to come into full contact with the organic solution. After drying to remove the solvent, a continuous solid electrolyte layer is formed on the surface of the carbon porous electrode loaded with lithium metal material, thereby obtaining the novel lithium-containing composite solid anode.

[0064] In summary, the preparation method of this invention includes: loading carbon material onto a current collector to form a porous carbon structure; then attaching lithium metal or a lithium-containing alloy to the surface of the porous carbon structure by methods such as vapor deposition, hot melt bonding, or electroplating to form a lithium-carbon composite negative electrode. Finally, a layer of solid electrolyte is modified on the surface of the above-mentioned negative electrode by means of polymerizing polymer monomers, dissolving the polymer coating, and evaporating the solvent to form a composite solid negative electrode sheet.

[0065] Furthermore, in the novel lithium-containing composite solid-state anode of the present invention, the solid electrolyte layer is formed by modifying the surface of a carbon porous electrode with a layer of polymer monomers or by coating a dissolved polymer and then evaporating the solvent, thus creating a composite solid-state anode sheet. This solid electrolyte layer can isolate the contact between the electrolyte and the electrolyte, suppress the decomposition and side reactions of the electrolyte during charging and discharging, and can construct a stable artificial solid electrolyte intermediate phase, promoting uniform deposition of lithium ions and inhibiting the growth of lithium dendrites.

[0066] Furthermore, the mass ratio of carbon materials, binders, lithium metal materials and solid electrolytes in the mixed slurry is 0.5-5:0.5-5:50-95:0.5-40.

[0067] Furthermore, the preparation method includes applying the mixed slurry onto the current collector layer by at least one of the following methods: scraping, extrusion, or slurry application.

[0068] Furthermore, the preparation method may more specifically include: first mixing two or more carbon materials and binders to form a slurry, and solid electrolyte powder may also be added, the process being similar to the slurry preparation process of porous electrodes; then attaching the prepared slurry to the current collector by means of scraping, extrusion, or slurry pulling, and drying to form a carbon porous electrode.

[0069] In some preferred embodiments, the preparation method may include: immersing the carbon porous electrode in an organic solution containing lithium metal for 6-12 hours, or loading lithium metal material onto the surface of the carbon material contained in the porous carbon framework structure of the carbon porous electrode by at least one of vapor deposition, hot melt composite, or lithium electroplating.

[0070] Furthermore, the preparation method may more specifically include: immersing the above-mentioned porous carbon electrode in an organic solution containing dissolved lithium metal, or attaching lithium or lithium alloy to the surface of the carbon material inside the porous carbon electrode by lithium electroplating.

[0071] In some preferred embodiments, the organic solution further includes a polycyclic aromatic compound and an organic solvent.

[0072] Furthermore, the polycyclic aromatic compounds may specifically include any one or a combination of two or more of naphthalene, biphenyl, terphenyl, tetraphenyl, anthracene, phenanthrene and their derivatives, but are not limited thereto.

[0073] Furthermore, the organic solvent may specifically include any one or a combination of two or more of dimethyl ether, diethyl ether, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dibutyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, and propylene glycol diethyl ether, but is not limited thereto.

[0074] Furthermore, the post-treatment methods after soaking in organic solutions include settling, washing, and vacuum drying.

[0075] Further, the lithium plating specifically includes: placing the carbon porous electrode as a conductive template substrate in an organic electrolyte system, using a lithium metal sheet as a cathode, and performing electrochemical deposition under constant current conditions to deposit lithium metal material on the carbon porous electrode; the lithium metal material can be continuously covered on the surface of the conductive carbon material and the current collector, but the thickness should be controlled below 1 mm, preferably 5 nm to 1 mm, and particularly preferably below 100 μm, especially preferably 5 nm to 100 μm.

[0076] Furthermore, the lithium plating method involves placing a porous carbon electrode as a conductive template substrate in an organic electrolyte system, connecting it to an external circuit to serve as the anode, and using a lithium metal sheet as the cathode. Electrochemical deposition is then performed under constant current conditions to deposit lithium metal material on the porous carbon electrode.

[0077] Furthermore, the organic electrolyte system includes an organic electrolyte and a lithium salt. The organic electrolyte includes any one or more combinations of carbonate electrolytes, carboxylic acid ester electrolytes, sulfone electrolytes, ether electrolytes, nitrile electrolytes, and ionic liquid electrolytes, but is not limited thereto.

[0078] Furthermore, the carbonate electrolyte includes linear carbonate electrolytes and / or cyclic carbonates, but is not limited to these.

[0079] Furthermore, the lithium salt includes any one or a combination of two or more of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium dioxalate borate, and lithium difluorooxalate borate, but is not limited thereto.

[0080] Furthermore, the constant current ranges from 0.1 to 20 mA / cm. 2The electrochemical deposition time is 30 min to 300 min.

[0081] In some preferred embodiments, the preparation method includes carrying out the polymerization reaction by at least one of the following methods: static settling, thermal polymerization, photopolymerization, etc.

[0082] Furthermore, the preparation method may more specifically include: contacting a polymer precursor solution containing polymerizable polymer monomers and lithium salts with a carbon porous electrode with lithium or lithium alloys attached by means of scraping, immersion, etc., and completing the polymerization reaction to generate a solid electrolyte by stirring and standing, thermal polymerization, photopolymerization, etc., with the participation of an initiator; or obtaining a solid electrolyte layer by evaporating the solvent of an organic solution containing a polymerized solid electrolyte and lithium salts dissolved on the surface of a carbon porous electrode, thereby preparing a novel lithium-containing composite solid anode.

[0083] Furthermore, the initiator used for the settling process is a Lewis acid type lithium salt initiator, such as lithium hexafluorophosphate, lithium tetrafluoroborate, etc., but not limited to these.

[0084] Furthermore, the initiator used in the thermal polymerization is a thermal initiator. For example, the thermal initiator may preferably include any one or a combination of two or more of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, dialkyl peroxide, potassium persulfate, cumene hydroperoxide, tert-butyl hydroperoxide, etc., but is not limited thereto.

[0085] Furthermore, the photopolymerization uses a photoinitiator, which may preferably include any one or a combination of two or more of 2-hydroxy-methylphenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, but is not limited thereto.

[0086] Furthermore, the thermal polymerization is carried out at a thermal initiation temperature of -10 to 150°C, preferably 60 to 140°C, and the thermal initiation time is 6 to 12 hours.

[0087] Furthermore, the photopolymerization uses ultraviolet light with a wavelength between 200 nm and 400 nm for photoinitiation, and the photoinitiation time is between 0.01 and 6 hours.

[0088] Furthermore, the wavelength of the photo-initiating ultraviolet light is 315–400 nm, and the photo-initiation time is 3–15 minutes.

[0089] Another aspect of the present invention provides a semi-solid lithium-sulfur battery comprising a sulfur-carbon positive electrode, a negative electrode, an electrolyte, a separator disposed between the sulfur-carbon positive electrode and the negative electrode, and a casing, wherein the negative electrode is any of the aforementioned novel lithium-containing composite solid negative electrodes.

[0090] In some preferred embodiments, the sulfur-carbon cathode is formed by combining elemental sulfur with carbon materials through a sintering method to form positive electrode active material particles, which are then applied to the surface of the current collector layer to form a porous electrode.

[0091] Furthermore, the sulfur-carbon cathode refers to a porous electrode formed by uniformly combining elemental sulfur with carbon materials through methods such as sintering, and then coating it onto the surface of a current collector or encapsulating it on a conductive current collector such as nickel foam.

[0092] In some preferred embodiments, the electrolyte includes an organic electrolyte and a lithium salt, wherein the organic electrolyte includes any one or a combination of two or more of carbonate electrolytes, carboxylic acid ester electrolytes, sulfone electrolytes, ether electrolytes, nitrile electrolytes, and ionic liquid electrolytes, but is not limited thereto.

[0093] Furthermore, the carbonate electrolyte includes linear carbonate electrolytes and / or cyclic carbonates, but is not limited thereto.

[0094] Furthermore, the lithium salt includes any one or a combination of two or more of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium dioxalate borate, and lithium difluorooxalate borate, but is not limited thereto.

[0095] Furthermore, the diaphragm includes, but is not limited to, any one of the following: multilayer diaphragm, organic / inorganic composite membrane, ceramic coated diaphragm, nonwoven fabric diaphragm, polyimide nanofiber diaphragm, etc.

[0096] The novel lithium-sulfur battery structure provided by this invention specifically comprises a sulfur-carbon cathode, a liquid electrolyte / separator, and a novel lithium-containing composite solid-state anode. This battery can effectively suppress the reduction and degradation of polysulfides dissolved from the sulfur-carbon cathode on the anode surface, thereby improving the battery's cycle life and capacity performance.

[0097] Another aspect of the present invention provides a method for preparing the aforementioned semi-solid lithium-sulfur battery, which includes assembling a sulfur-carbon cathode, a separator, and a novel lithium-containing composite solid anode, and injecting an electrolyte to obtain the semi-solid lithium-sulfur battery.

[0098] Furthermore, the preparation method includes: using the novel lithium-containing composite solid anode prepared above as the anode, combined with a sulfur-carbon cathode, electrolyte, separator and outer packaging, to produce a semi-solid lithium-sulfur battery.

[0099] Further, the preparation method includes:

[0100] Elemental sulfur and carbon materials are uniformly composited using a sintering method to form positive electrode active material particles; and...

[0101] The positive electrode active material particles are coated or encapsulated on the surface of the current collector layer to form a porous electrode, thereby obtaining the sulfur-carbon positive electrode.

[0102] Furthermore, the current collector layer is a conductive nickel foam-like current collector, but is not limited thereto.

[0103] In summary, the novel lithium-containing composite solid anode with a surface-modified layer provided by this invention exhibits excellent stability, enabling uniform deposition of lithium ions and suppressing lithium dendrite growth. Simultaneously, it isolates the interaction between the liquid electrolyte and the anode, effectively reducing side reactions between the electrolyte and the electrode. Furthermore, the solid electrolyte layer isolates the contact between the electrolyte and the electrolyte layer, suppressing electrolyte decomposition and side reactions during charging and discharging, and constructs a stable artificial solid electrolyte intermediate phase.

[0104] The semi-solid-state battery assembled using this electrode has excellent capacity utilization and long cycle performance. It can effectively suppress the reduction and destruction of polysulfides dissolved in the sulfur-carbon cathode on the surface of the anode, thereby improving the cycle life and capacity utilization performance of the battery.

[0105] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the manufacturer.

[0106] Example 1

[0107] Multilayer graphene with a thickness of 1 μm and a planar size of 500 nm, carbon nanotubes with a diameter of 5 nm and a length of 10 nm, polyvinylidene fluoride as a binder, and Li₂ with a diameter of 0.3 μm were used. 10 GeP2S 12 Solid electrolyte powder was mixed in tetrahydrofuran to prepare a slurry. The slurry was then extruded onto a nickel foam current collector, and subsequently dried under vacuum at 70°C for 12 hours to form a porous carbon electrode. The carbon material accounted for 0.5% of the total mass of the negative electrode excluding the current collector, and the binder accounted for 5% of the total mass of the negative electrode excluding the current collector.

[0108] The porous electrode was immersed in a mixed solvent containing dissolved lithium metal. The mixed solvent components included phenanthrene, anthracene, dimethyl ether, and diethyl ether. The immersion time was 15 minutes. After standing, cleaning, and vacuum drying, lithium metal was obtained on the surface of carbon material inside the electrode. The lithium metal particles attached in a particulate state had a particle size of 10 μm.

[0109] The lithium-containing porous carbon electrode was immersed in a solution containing polyvinylidene fluoride monomer and lithium bis(fluorosulfonyl)imide, and a tert-butyl hydroperoxide thermal initiator was added. The electrode was then heated at 140°C for 25 minutes to coat the surface with a layer of polymer electrolyte. The final electrode had a porosity of 60%.

[0110] The composite solid negative electrode sheet prepared above is stacked with a ceramic separator and a lithium-sulfur positive electrode, and then wound. A carbonate electrolyte with lithium hexafluorophosphate as the main lithium salt and dimethyl carbonate, diethyl carbonate, and ethylene methyl carbonate as the main electrolyte components is injected into the middle. The battery is then made by adding outer packaging.

[0111] Test results: The battery was charged and discharged at room temperature and 0.1C with a charge and discharge voltage of 1.7-2.8V. After 100 cycles, the discharge capacity was 192mAh / g, the capacity retention rate was 80%, and the coulombic efficiency was 98%.

[0112] Example 2

[0113] A sheet of graphite with a thickness of 1 nm and a planar size of 50 μm, carbon black with a size of 100 nm, hydroxymethyl cellulose as a binder, and a solid electrolyte Li with a diameter of 500 nm were used. 6.75 La3Zr 1.75 Ta 0.25 O 12 A mixed slurry was prepared by mixing with N-methylpyrrolidone. The slurry was then applied to a copper foil current collector by a scraping method, and subsequently dried under vacuum at 70°C for 12 hours to form a porous carbon electrode. The carbon material accounted for 5% of the total mass of the negative electrode excluding the current collector, and the binder accounted for 0.5% of the total mass of the negative electrode excluding the current collector.

[0114] The porous electrode was immersed in a mixed solvent containing dissolved lithium metal, the mixed solvent components including naphthalene, ethylene glycol diethyl ether, and propylene glycol dimethyl ether, for 5 minutes. After standing, cleaning and vacuum drying, lithium metal was obtained on the surface of carbon material inside the electrode, with the lithium metal particles attached in a granular state and a particle size of 1 μm.

[0115] The lithium-containing porous carbon electrode was further immersed in an acetonitrile solution containing polyethylene oxide and lithium bis(fluorosulfonyl)imide, and heated under vacuum at 50°C for 48 hours to evaporate the solvent, thereby coating the electrode surface with a layer of polymer electrolyte. The final electrode porosity was 55%.

[0116] The composite solid negative electrode sheet prepared above is stacked and wound with a multilayer separator and a lithium-sulfur positive electrode. Then, a carbonate solution with lithium bis(fluorosulfonyl)imide as the main lithium salt and ethyl acetate, propyl propionate, butyl butyrate and ethylene carbonate as the main electrolyte components is injected into the middle, and an outer packaging is added to form a battery.

[0117] Test results: The battery was charged and discharged at room temperature (0.05C) with a charge and discharge voltage of 1.7-2.8V. After 50 cycles, the discharge capacity was 206mAh / g, the capacity retention rate was 88%, and the coulombic efficiency was 97%.

[0118] Example 3

[0119] A slurry was prepared by mixing 70 nm carbon black, 60 nm microporous carbon, and a binder, polyacrylonitrile, in N-methylpyrrolidone. The slurry was then coated onto a copper foam current collector using a blade coating method and dried under vacuum at 65°C for 4 hours to form a porous carbon electrode. The carbon material accounted for 2.5% of the total mass of the negative electrode excluding the current collector, and the binder accounted for 3% of the total mass of the negative electrode excluding the current collector.

[0120] The aforementioned porous electrode was used as a conductive template substrate and placed in a mixed organic electrolyte containing lithium tetrafluoroborate, lithium dioxalatoborate, lithium N-methyl-N-butylpyrrole bisfluoromethanesulfonylimide, and ethylene carbonate. After being connected to an external circuit via wires, the carbon porous electrode served as the anode, and metallic lithium served as the cathode, at a current of 0.1 mA / cm². 2 Electroplating was performed at a constant current density for 300 minutes to obtain lithium metal attached to the surface of carbon material inside the electrode. The thickness of the continuously attached lithium metal was 10 μm, and the particle size of the lithium metal attached in a granular state was 100 nm.

[0121] The lithium-containing porous carbon electrode was further immersed in a solution containing 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt, tetraethylene glycol diacrylate monomer, and lithium bis(fluorosulfonyl)imide. Cumene hydrogen peroxide and tert-butyl hydrogen peroxide thermal initiators were added, and the polymerization was completed at -10°C for 30 minutes. Then, the electrode was heated at 75°C under vacuum for 12 hours to coat the electrode surface with a layer of polymer electrolyte. The final electrode had a porosity of 35%.

[0122] The composite solid negative electrode sheet prepared above is stacked with a commercial PP separator and a lithium-sulfur positive electrode, and then wound. Then, a sulfone electrolyte with lithium bis(trifluoromethanesulfonyl)imide as the main lithium salt and dimethyl sulfoxide, diphenyl sulfoxide, sulfolane cyclobutane and fluoroethylene carbonate as the main solvent is injected into the middle, and an outer packaging is added to make a battery.

[0123] Test results: The battery was charged and discharged at room temperature and 0.1C with a charge and discharge voltage of 1.7-2.8V. After 200 cycles, the discharge capacity was 492mAh / g, the capacity retention rate was 89%, and the coulombic efficiency was 99.0%.

[0124] Example 4

[0125] A slurry was prepared by mixing sheet graphite (50 nm thick, 200 nm planar size) and microporous carbon (100 nm size) with styrene-butadiene rubber emulsion as a binder in N-methylpyrrolidone. The slurry was then applied to a nickel foil current collector using a slurry-stretching method and dried at 65°C under vacuum for 6 hours to form a porous carbon electrode. The carbon material accounted for 3.5% of the total mass of the negative electrode excluding the current collector, and the binder accounted for 4.2% of the total mass of the negative electrode excluding the current collector.

[0126] The aforementioned porous electrode, serving as a conductive template substrate, was placed in a mixed organic electrolyte containing lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, ethylene glycol dimethyl ether, fluoroethylene carbonate, ethylene carbonate, and dimethyl carbonate. After connecting to an external circuit via wires, the carbon porous electrode served as the anode, and metallic lithium as the cathode, at a current of 20 mA / cm². 2 Electroplating was performed at a constant current density for 300 minutes to obtain lithium metal attached to the surface of carbon material inside the electrode, with a continuous lithium metal thickness of 1 mm.

[0127] The lithium-containing porous carbon electrode was further immersed in a solution containing polyvinyl carbonate, lithium bis(fluorosulfonyl)imide, and lithium bis(trifluoromethylsulfonyl)imide in tetrahydrofuran. The solvent was evaporated by heating under vacuum at 75°C for 24 hours, and a layer of polymer electrolyte was then coated onto the electrode surface. The final electrode porosity was 32%.

[0128] The composite solid negative electrode sheet prepared above is stacked and wound with a commercial PP separator and a lithium-sulfur positive electrode. Then, an ether electrolyte with lithium tetrafluoroborate and lithium perchlorate as the main lithium salts and ethylene glycol dimethyl ether, tetrahydrofuran, dioxolane and fluoroethylene carbonate as the main solvents is injected into the middle, and an outer packaging is added to make a battery.

[0129] Test results: The battery was charged and discharged at room temperature and 0.1C with a charge and discharge voltage of 1.7-2.8V. After 200 cycles, the discharge capacity was 892mAh / g, the capacity retention rate was 80%, and the coulombic efficiency was 90.0%.

[0130] Example 5

[0131] A mixed slurry was prepared by mixing multilayer graphene with a thickness of 25 nm and a planar dimension of 100 nm, carbon black with a dimension of 45 nm, carbon nanotubes with a diameter of 10 nm and a length of 500 nm, and polyacrylate binder in N-methylpyrrolidone. The slurry was then coated onto a copper-plated nonwoven fabric and dried under vacuum at 65°C for 6 hours to form a porous carbon electrode. The carbon material accounted for 2.7% of the total mass of the negative electrode excluding the current collector, and the binder accounted for 3.5% of the total mass of the negative electrode excluding the current collector.

[0132] The porous electrode was immersed in a mixed solvent containing dissolved lithium metal. The mixed solvent components included naphthalene, anthracene, ethylene glycol diethyl ether, propylene glycol diethyl ether, and dimethyl ether. The immersion time was 15 minutes. After standing, cleaning, and vacuum drying, lithium metal was obtained on the surface of carbon material inside the electrode. The lithium metal particles attached in a particulate state had a particle size of 10 nm.

[0133] The lithium-containing porous carbon electrode was further immersed in a solution of tetrahydrofuran containing caprolactone and lithium tetrafluoroborate. Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide was added as a photoinitiator, and polymerization was completed at 400 nm UV light for 3 minutes. The solvent was then evaporated by heating at 75°C under vacuum for 12 hours, resulting in a polymer electrolyte coating on the electrode surface. The final electrode had a porosity of 40%.

[0134] The composite solid negative electrode sheet prepared above is stacked and wound with a polyimide nanofiber separator and a lithium-sulfur positive electrode. Then, an electrolyte containing nitrile compounds, with lithium dioxaborate as the main lithium salt and succinic acid, hexanetrionitrile, ethylene carbonate, and propylene carbonate as the main solvents, is injected into the middle. Finally, an outer packaging is added to form a battery.

[0135] Test results: The battery was charged and discharged at room temperature (0.05C) with a charge and discharge voltage of 1.7-2.8V. After 100 cycles, the discharge capacity was 292mAh / g, the capacity retention rate was 84%, and the coulombic efficiency was 97.0%.

[0136] Example 6

[0137] A slurry was prepared by mixing 500 nm thick, 10 μm planar graphite, 30 nm carbon black, and 77 nm microporous carbon with a binder of polyacrylate in N-methylpyrrolidone. The slurry was then coated onto carbon fiber cloth and dried under vacuum at 65 °C for 6 hours to form a porous carbon electrode. The carbon material accounted for 4.7% of the total mass of the negative electrode excluding the current collector, and the binder accounted for 0.7% of the total mass of the negative electrode excluding the current collector.

[0138] The aforementioned porous electrode was used as a conductive template substrate and placed in a mixed organic electrolyte containing lithium tetrafluoroborate, lithium dioxalate borate, lithium N-methyl-N-butylpyrrole bisfluoromethanesulfonylimide, and ethylene carbonate. After being connected to an external circuit via wires, the carbon porous electrode served as the anode and metallic lithium as the cathode, at a current of 0.1 mA / cm². 2 Electroplating was performed at a constant current density for 30 minutes to obtain lithium metal deposited on the surface of carbon material inside the electrode. The thickness of the continuously deposited lithium metal was 5 nm.

[0139] The lithium-containing porous carbon electrode was further immersed in an acetonitrile solution containing 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1,3-dioxolane, and lithium bis(fluorosulfonyl)imide. Cumene hydrogen peroxide and tert-butyl hydrogen peroxide thermal initiators were added, and the mixture was heated at 60°C for 2 hours to coat the electrode surface with a layer of polymer electrolyte. The final electrode had a porosity of 17%.

[0140] The composite solid negative electrode sheet prepared above is stacked and wound with a non-woven fabric separator and a lithium-sulfur positive electrode. Then, an ionic liquid electrolyte with lithium hexafluorophosphate and lithium difluorooxalate borate as the main lithium salts and N-methyl-N-butylpyrrole bis(trifluoromethanesulfonyl)imide lithium, 1-propyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide lithium, 1-methyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide lithium and propylene carbonate as the main solvents is injected into the middle. The battery is then made by adding an outer packaging.

[0141] Test results: The battery was charged and discharged at room temperature and 0.1C with a charge and discharge voltage of 1.7-2.8V. After 50 cycles, the discharge capacity was 183mAh / g, the capacity retention rate was 94%, and the coulombic efficiency was 98.8%.

[0142] Example 7

[0143] A slurry was prepared by mixing 75 nm carbon black, 500 nm diameter carbon nanotubes, and 10 nm length carbon nanotubes with polyacrylic acid as a binder in N-methylpyrrolidone. The slurry was then coated onto a stainless steel current collector and dried under vacuum at 70 °C for 6 hours to form a porous carbon electrode. The carbon material accounted for 2.2% of the total mass of the negative electrode excluding the current collector, and the binder accounted for 1.7% of the total mass of the negative electrode excluding the current collector.

[0144] The aforementioned porous electrode was used as a conductive template substrate and placed in a mixed organic electrolyte containing lithium bis(trifluoromethanesulfonyl)imide, lithium dioxaborate, 1,3-dioxolane, and ethylene glycol dimethyl ether. After being connected to an external circuit via wires, the carbon porous electrode served as the anode, and metallic lithium served as the cathode, at a current of 10 mA / cm². 2 Electroplating was performed at a constant current density for 60 minutes to obtain lithium metal attached to the surface of carbon material inside the electrode, with a continuous lithium metal thickness of 100 μm.

[0145] The lithium-containing porous carbon electrode was further immersed in a solution containing 1,3-dioxolane monomer and lithium bis(fluorosulfonyl)imide, and potassium persulfate thermal initiator was added. The mixture was heated at 150°C for 12 hours to coat the electrode surface with a layer of polymer electrolyte. The final electrode porosity was 9%.

[0146] The composite solid negative electrode sheet prepared above is stacked and wound with a ceramic-coated separator and a lithium-sulfur positive electrode. Then, an electrolyte containing nitrile compounds, with lithium dioxaborate as the main lithium salt and succinic acid, hexanetrionitrile, ethylene carbonate, and propylene carbonate as the main solvents, is injected into the middle. Finally, an outer packaging is added to form a battery.

[0147] Test results: The battery was charged and discharged at room temperature and 0.1C with a charge and discharge voltage of 1.7-2.8V. After 200 cycles, the discharge capacity was 886mAh / g, the capacity retention rate was 92%, and the coulombic efficiency was 98.5%.

[0148] Example 8

[0149] A mixed slurry was prepared by mixing carbon nanotubes with a diameter of 5 μm and a length of 50 μm, microporous carbon with a size of 60 nm, and a binder of polyacrylate in N-methylpyrrolidone. The slurry was then coated onto a lithium-plated polymer fiber cloth and dried under vacuum at 60°C for 6 hours to form a porous carbon electrode. The carbon material accounted for 2.8% of the total mass of the negative electrode excluding the current collector, and the binder accounted for 3.4% of the total mass of the negative electrode excluding the current collector.

[0150] The aforementioned porous electrode, serving as a conductive template substrate, was placed in a mixed organic electrolyte containing lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, ethylene glycol dimethyl ether, fluoroethylene carbonate, ethylene carbonate, and dimethyl carbonate. After connecting to an external circuit via wires, the carbon porous electrode served as the anode, and metallic lithium as the cathode, at a current of 10 mA / cm². 2 Electroplating was performed at a constant current density for 180 minutes to obtain lithium metal attached to the surface of carbon material inside the electrode, with a continuous lithium metal thickness of 300 μm.

[0151] The lithium-containing porous carbon electrode was further immersed in a solution containing vinylimidazolium bis(trifluoromethanesulfonyl)imide salt and lithium bis(fluorosulfonyl)imide, and a 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone photoinitiator was added. Polymerization was carried out at a wavelength of 315 nm for 15 minutes. After the polymerization reaction was completed, a layer of polymer electrolyte was coated on the surface of the electrode. The final electrode had a porosity of 29%.

[0152] The composite solid negative electrode sheet prepared above is stacked with a ceramic separator and a lithium-sulfur positive electrode, and then wound. A carbonate electrolyte with lithium hexafluorophosphate as the main lithium salt and dimethyl carbonate, diethyl carbonate, and ethylene methyl carbonate as the main electrolyte components is injected into the middle. The battery is then made by adding outer packaging.

[0153] Test results: The battery was charged and discharged at room temperature and 0.1C with a charge and discharge voltage of 1.7-2.8V. After 200 cycles, the discharge capacity was 945mAh / g, the capacity retention rate was 90%, and the coulombic efficiency was 97.9%.

[0154] Example 9

[0155] Carbon black with a size of 35 nm, carbon nanotubes with a diameter of 2 μm and a length of 10 μm, microporous carbon with a size of 44 nm, polyvinylidene fluoride as a binder, and Li7La3Zr2O with an average particle size of 600 nm were combined. 12 A mixed slurry was prepared by mixing with N-methylpyrrolidone, and then the slurry was applied to a copper foil current collector by scraping. The slurry was then dried under vacuum at 80°C for 5 hours to form a porous carbon electrode. The carbon material accounted for 3.1% of the total mass of the negative electrode excluding the current collector, and the binder accounted for 2.4% of the total mass of the negative electrode excluding the current collector.

[0156] The porous electrode was immersed in a mixed solvent containing dissolved lithium metal. The mixed solvent components included naphthalene, ethylene glycol diethyl ether, and propylene glycol dimethyl ether. The immersion time was 5 seconds. After standing, cleaning, and vacuum drying, lithium metal was obtained on the surface of carbon material inside the electrode. The thickness of the continuously attached lithium metal was 5 nm.

[0157] The lithium-containing porous carbon electrode was immersed in a tetrahydrofuran solution containing 1,2,7,8-diepoxyoctane, butyl glycidyl ether, and lithium hexafluorophosphate. 2-hydroxy-methylphenylpropane-1-one was added as a photoinitiator, and photoinitiation was performed under 200 nm ultraviolet light for 0.01 hours to form a solid electrolyte layer. A polymer electrolyte layer was then coated onto the electrode surface to complete the polymerization reaction. The final electrode had a porosity of 20%.

[0158] The composite solid negative electrode sheet prepared above is stacked with an organic / inorganic composite separator and a lithium-sulfur positive electrode, and then wound. Then, an electrolyte containing nitrile compounds, with lithium dioxaborate as the main lithium salt and succinic acid, hexanetrionitrile, ethylene carbonate, and propylene carbonate as the main solvents, is injected into the middle. Finally, an outer packaging is added to form a battery.

[0159] Test results: The battery was charged and discharged at room temperature (0.05C) with a charge and discharge voltage of 1.7-2.8V. After 200 cycles, the discharge capacity was 168mAh / g, the capacity retention rate was 95%, and the coulombic efficiency was 98.8%.

[0160] Example 10

[0161] The mixture consists of carbon black with a size of 68 nm, carbon nanotubes with a diameter of 270 nm and a length of 2 μm, microporous carbon with a size of 55 nm, and sheet graphite with a thickness of 30 nm and a planar size of 3 μm, bound with polyvinylidene fluoride and Li7La3Zr2O with an average particle size of 1.2 μm. 12 A mixed slurry was prepared by mixing with N-methylpyrrolidone, and then the slurry was applied to a copper foil current collector by scraping. The slurry was then dried under vacuum at 80°C for 3 hours to form a porous carbon electrode. The carbon material accounted for 4.9% of the total mass of the negative electrode excluding the current collector, and the binder accounted for 3.3% of the total mass of the negative electrode excluding the current collector.

[0162] The porous electrode was immersed in a mixed solvent containing dissolved lithium metal. The mixed solvent components included naphthalene, anthracene, ethylene glycol diethyl ether, propylene glycol diethyl ether, and dimethyl ether. The immersion time was 15 minutes. After standing, cleaning, and vacuum drying, lithium metal was obtained on the surface of carbon material inside the electrode. The lithium metal particles attached in a particulate state had a particle size of 0.6 μm.

[0163] The lithium-containing porous carbon electrode was further immersed in a solution containing lithium 1-[3-(methacryloyloxy)propylsulfonyl]-1-(trifluoromethylsulfonyl)imide and lithium difluorosulfonylimide. A photoinitiator, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone, was added, and the electrode was irradiated under 400 nm ultraviolet light for 6 hours to complete the polymerization reaction, coating the electrode surface with a layer of polymer electrolyte. The final electrode porosity was 12%.

[0164] The composite solid negative electrode sheet prepared above is stacked with a multilayer separator and a lithium-sulfur positive electrode, and then wound. Then, an electrolyte containing nitrile salts, mainly lithium dioxaborate and mainly solvents such as succinic acid, hexanetrionitrile, ethylene carbonate, and propylene carbonate is injected into the middle, and an outer packaging is added to form a battery.

[0165] Test results: The battery was charged and discharged at room temperature (0.05C) with a charge and discharge voltage of 1.7-2.8V. After 100 cycles, the discharge capacity was 256mAh / g, the capacity retention rate was 93%, and the coulombic efficiency was 98.4%.

[0166] Comparative Example 1

[0167] A slurry was prepared by mixing 75 nm carbon black, 500 nm diameter carbon nanotubes, and 10 nm length carbon nanotubes with polyacrylic acid as a binder in N-methylpyrrolidone. The slurry was then coated onto a stainless steel current collector and dried under vacuum at 70 °C for 6 hours to form a porous carbon electrode. The carbon material accounted for 2.2% of the total mass of the negative electrode excluding the current collector, and the binder accounted for 1.7% of the total mass of the negative electrode excluding the current collector.

[0168] The aforementioned porous electrode was used as a conductive template substrate and placed in a mixed organic electrolyte containing lithium bis(trifluoromethanesulfonyl)imide, lithium dioxaborate, 1,3-dioxolane, and ethylene glycol dimethyl ether. After being connected to an external circuit via wires, the carbon porous electrode served as the anode, and metallic lithium served as the cathode, at a current of 10 mA / cm². 2 Electroplating was performed at a constant current density for 60 minutes to obtain lithium metal attached to the surface of carbon material inside the electrode, with a continuous lithium metal thickness of 100 μm.

[0169] The composite solid negative electrode sheet prepared above is stacked and wound with a ceramic-coated separator and a lithium-sulfur positive electrode. Then, an electrolyte containing nitrile compounds, with lithium dioxaborate as the main lithium salt and succinic acid, hexanetrionitrile, ethylene carbonate, and propylene carbonate as the main solvents, is injected into the middle. Finally, an outer packaging is added to form a battery.

[0170] Test results: The battery was charged and discharged at room temperature and 0.1C with a charge and discharge voltage of 1.7-2.8V. After 200 cycles, the discharge capacity was 108mAh / g, the capacity retention rate was 10.3%, and the efficiency was 41%.

[0171] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0172] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A lithium-containing composite solid-state anode for semi-solid-state lithium-sulfur batteries, characterized in that... The device comprises, in sequence: a current collector layer, a negative electrode active material layer, and a continuous solid electrolyte layer. The solid electrolyte layer is composed of a continuous polymer solid electrolyte and a lithium salt, and is uniformly coated on the surface of the negative electrode active material layer. The negative electrode active material layer includes a porous carbon framework structure formed of carbon material, lithium metal material and a binder distributed inside the porous carbon framework structure, and lithium metal material coated with polymer solid electrolyte distributed on the surface of the porous carbon framework structure. The lithium metal material and the binder are distributed and filled in the pores contained in the porous carbon framework structure. The lithium metal material coated with solid electrolyte is continuously coated on the surface of the porous carbon framework structure and the current collector layer. The thickness ratio of the lithium metal material coated with solid electrolyte to the thickness of the negative electrode active material layer is 50~100:

100. The carbon material is selected from any two or more combinations of sheet carbon material, small particle conductive carbon material, one-dimensional conductive carbon material, and microporous carbon material. The lithium metal material is selected from any one or more combinations of lithium metal, lithium-containing alloy material, and lithium-containing compound.

2. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 1, characterized in that: The thickness of the negative electrode active material layer is 50~200μm.

3. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 2, characterized in that: The thickness of the negative electrode active material layer is 80~130μm.

4. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 1, characterized in that: The ratio of the thickness of the lithium metal material coated with the solid electrolyte to the thickness of the negative electrode active material layer is 90~100:

100.

5. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 1, characterized in that: The sheet-like carbon material has a sheet-like structure and is selected from sheet graphite and / or multilayer graphene. The thickness of the sheet-like carbon material is 1 nm to 1 μm, and the planar size is 100 nm to 50 μm.

6. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 5, characterized in that: The thickness of the sheet carbon material is 5nm~50nm, and the planar size is 200nm~10μm.

7. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 1, characterized in that: The one-dimensional conductive carbon material is a carbon nanotube, with a diameter of 5 nm to 5 μm and a length of 500 nm to 50 μm.

8. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 7, characterized in that: The carbon nanotubes have a diameter of 10 nm to 500 nm and a length of 2 to 10 μm.

9. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 1, characterized in that: The small-particle conductive carbon material is carbon black particles, and the size of the small-particle conductive carbon material is less than 1 μm.

10. The lithium-containing composite solid-state anode for a semi-solid lithium-sulfur battery according to claim 9, characterized in that: The size of the small conductive carbon particles is less than 100 nm.

11. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 1, characterized in that: The size of the microporous carbon material is below 100 nm.

12. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 1, characterized in that: The lithium-containing alloy material is selected from any one or a combination of two or more of lithium-silicon alloys, lithium-tin alloys, and lithium-magnesium alloys.

13. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 1, characterized in that: The lithium-containing compound is selected from lithium sulfide and / or lithium selenide.

14. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 1, characterized in that: The thickness of the lithium metal material in the lithium-containing composite solid anode used in the semi-solid lithium-sulfur battery is less than 1 mm.

15. The lithium-containing composite solid-state anode for a semi-solid lithium-sulfur battery according to claim 14, characterized in that: The thickness of the lithium metal material in the lithium-containing composite solid anode used in the semi-solid lithium-sulfur battery is 5nm~1mm.

16. The lithium-containing composite solid-state anode for a semi-solid-state lithium-sulfur battery according to claim 14, characterized in that: The thickness of the lithium metal material in the lithium-containing composite solid anode used in the semi-solid lithium-sulfur battery is less than 100 μm.

17. The lithium-containing composite solid-state anode for a semi-solid-state lithium-sulfur battery according to claim 16, characterized in that: The thickness of the lithium metal material in the lithium-containing composite solid anode used in the semi-solid lithium-sulfur battery is 5nm~100μm.

18. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 1, characterized in that: The lithium metal material is distributed in particulate form, and the particle size of the lithium metal material is 10nm~10μm.

19. The lithium-containing composite solid-state anode for a semi-solid-state lithium-sulfur battery according to claim 18, characterized in that: The lithium metal material particles have a particle size of 100 nm to 1 μm.

20. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 1, characterized in that: The lithium metal material has a content of 50-95 wt% in the entire lithium-containing composite solid anode used in semi-solid lithium-sulfur batteries.

21. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 1, characterized in that: The porosity of the lithium-containing composite solid anode used in semi-solid lithium-sulfur batteries is below 60%.

22. The lithium-containing composite solid-state anode for a semi-solid-state lithium-sulfur battery according to claim 21, characterized in that: The porosity of the lithium-containing composite solid anode used in semi-solid lithium-sulfur batteries is below 40%.

23. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 1, characterized in that: The carbon material accounts for 0.5-5% of the total mass of the lithium-containing composite solid anode used in the semi-solid lithium-sulfur battery, excluding the current collector, and the binder accounts for 0.5-5% of the total mass of the lithium-containing composite solid anode used in the semi-solid lithium-sulfur battery, excluding the current collector.

24. The lithium-containing composite solid-state anode for semi-solid-state lithium-sulfur batteries according to claim 1, characterized in that: The adhesive is selected from any one or a combination of two or more of polyvinylidene fluoride, styrene-butadiene rubber latex, hydroxymethyl cellulose, polyacrylic acid, polyacrylonitrile, and polyacrylate.

25. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 1, characterized in that: The current collector layer is a porous current collector, selected from any one or a combination of two or more of porous metal foil, nickel foam, copper foam, polymer fiber cloth or non-woven cloth with metal plating on the surface, and carbon fiber cloth.

26. The lithium-containing composite solid-state anode for a semi-solid-state lithium-sulfur battery according to claim 25, characterized in that: The porous metal foil is selected from any one or a combination of two or more of copper, nickel, and stainless steel.

27. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 1, characterized in that: The thickness of the current collector layer is 50~500μm.

28. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 1, characterized in that: The thickness of the solid electrolyte layer covering the surface of the negative electrode active material layer is 10 nm to 10 μm.

29. The lithium-containing composite solid-state anode for a semi-solid lithium-sulfur battery according to claim 28, characterized in that: The thickness of the solid electrolyte layer covering the surface of the negative electrode active material layer is 20 nm to 2 μm.

30. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 1, characterized in that: The polymer solid electrolyte is obtained from at least polymerizable polymer monomers via a polymerization reaction; The polymerizable polymer monomer is selected from any one or a combination of two or more of the following polymer monomers: polyvinylidene fluoride polymer monomers, polyethylene oxide polymer monomers, polycarbonate polymer monomers, polyether polymer monomers, polyacrylonitrile polymer monomers, and polyionic liquid monomers.

31. The lithium-containing composite solid-state anode for a semi-solid lithium-sulfur battery according to claim 30, characterized in that: The polymerizable monomer is selected from any one or a combination of two or more of polyvinylidene fluoride monomer, polyethylene glycol diacrylate, and 1,3-dioxolane.

32. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 1, characterized in that: The polymer solid electrolyte is selected from any one or a combination of two or more of the following: polyvinylidene fluoride polymer, polyethylene oxide polymer, polycarbonate polymer, polyether polymer, polyacrylonitrile polymer, and polyionic liquid polymer.

33. The lithium-containing composite solid-state anode for a semi-solid lithium-sulfur battery according to claim 32, characterized in that: The polymer solid electrolyte is selected from any one or a combination of two or more of polyvinylidene fluoride, poly(1-vinyl-3-butylimidazoline bis(trifluoromethanesulfonyl)imide-co-ethylene glycol diacrylate), and polyethylene carbonate.

34. The lithium-containing composite solid-state anode for semi-solid lithium-sulfur batteries according to claim 1, characterized in that: The lithium salt is selected from any one or a combination of two or more of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethyl)sulfonyl)imide, lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium dioxalate borate, and lithium difluorooxalate borate.

35. The method for preparing a lithium-containing composite solid-state anode for a semi-solid-state lithium-sulfur battery as described in any one of claims 1-34, characterized in that... include: Provide mixed slurries containing carbon materials, binders, and solid electrolytes with or without additives; The mixed slurry is applied to the current collector layer and dried to form a porous carbon electrode, which has a porous carbon framework structure formed of carbon material. Lithium metal material is loaded onto the surface of the carbon material contained in the porous carbon framework structure of a carbon porous electrode; and... A polymer precursor solution containing polymerizable polymer monomers and lithium salts is provided, and a carbon porous electrode loaded with lithium metal material is brought into full contact with the polymer precursor solution. Then, a polymerization reaction is carried out under the action of an initiator, and a continuous solid electrolyte layer is formed on the surface of the carbon porous electrode loaded with lithium metal material, thereby obtaining the lithium-containing composite solid anode for semi-solid lithium-sulfur batteries. Alternatively, an organic solution containing a polymer solid electrolyte and a lithium salt is provided, allowing the carbon porous electrode loaded with lithium metal material to come into full contact with the organic solution. After drying to remove the solvent, a continuous solid electrolyte layer is formed on the surface of the carbon porous electrode loaded with lithium metal material, thereby obtaining the lithium-containing composite solid negative electrode for semi-solid lithium-sulfur batteries.

36. The preparation method according to claim 35, characterized in that: The mass ratio of carbon materials, binders, lithium metal materials and solid electrolytes in the mixed slurry is 0.5~5:0.5~5:50~95:0.5~40.

37. The preparation method according to claim 35, characterized in that, The preparation method includes applying the mixed slurry onto the current collector layer by at least one of the following methods: scraping, extrusion, or slurry drawing.

38. The preparation method according to claim 35, characterized in that, The preparation method includes: immersing the carbon porous electrode in an organic solution containing lithium metal for 6-12 hours, or loading lithium metal material onto the surface of the carbon material contained in the porous carbon framework structure of the carbon porous electrode by at least one of vapor deposition, hot melt composite, or lithium electroplating.

39. The preparation method according to claim 38, characterized in that: The organic solution further includes a polycyclic aromatic compound and an organic solvent; the polycyclic aromatic compound is selected from any one or a combination of two or more of naphthalene, biphenyl, terphenyl, tetraphenyl, anthracene, phenanthrene and their derivatives; the organic solvent is selected from any one or a combination of two or more of dimethyl ether, diethyl ether, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dibutyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, and propylene glycol diethyl ether.

40. The preparation method according to claim 38, characterized in that, The lithium plating specifically includes: placing the carbon porous electrode as a conductive template substrate in an organic electrolyte system, using a lithium metal sheet as a cathode, and performing electrochemical deposition under constant current conditions to deposit lithium metal material on the carbon porous electrode.

41. The preparation method according to claim 40, characterized in that: The organic electrolyte system includes an organic electrolyte and a lithium salt. The organic electrolyte is selected from any one or a combination of two or more of carbonate electrolytes, carboxylic acid ester electrolytes, sulfone electrolytes, ether electrolytes, nitrile electrolytes, and ionic liquid electrolytes. The carbonate electrolyte is selected from linear carbonate electrolytes and / or cyclic carbonates. The lithium salt is selected from any one or a combination of two or more of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium di(oxalato)borate, and lithium di(fluorooxalato)borate.

42. The preparation method according to claim 40, characterized in that: The magnitude of the constant current is 0.1~20mA / cm. 2 The electrochemical deposition time is 30 min to 300 min.

43. The preparation method according to claim 35, characterized in that, The preparation method includes: carrying out the polymerization reaction by at least one of static, thermal polymerization, and photopolymerization methods.

44. The preparation method according to claim 43, characterized in that: The initiator used for the static setting is a Lewis acid type lithium salt initiator, selected from lithium hexafluorophosphate and / or lithium tetrafluoroborate; The initiator used in the thermal polymerization is a thermal initiator selected from any one or a combination of two or more of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, dialkyl peroxide, potassium persulfate, cumene hydroperoxide, and tert-butyl hydroperoxide. The photopolymerization process uses a photoinitiator selected from any one or a combination of two or more of 2-hydroxy-methylphenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide. The thermal polymerization uses a thermal initiation temperature of -10 to 150°C and a thermal initiation time of 6 to 12 hours. The photopolymerization uses ultraviolet light with a wavelength of 200-400 nm for photoinitiation and a photoinitiation time of 0.01-6 hours.

45. The preparation method according to claim 44, characterized in that: The thermal polymerization uses a thermal initiation temperature of 60~140℃, the photoinitiation ultraviolet light wavelength is 315~400nm, and the photoinitiation time is 3~15 minutes.

46. ​​A semi-solid-state lithium-sulfur battery, comprising a sulfur-carbon positive electrode, a negative electrode, an electrolyte, a separator disposed between the sulfur-carbon positive electrode and the negative electrode, and a casing, characterized in that, The negative electrode is a lithium-containing composite solid negative electrode for semi-solid lithium-sulfur batteries as described in any one of claims 1-34.

47. The semi-solid-state lithium-sulfur battery according to claim 46, characterized in that: The sulfur-carbon cathode is formed by combining elemental sulfur with carbon materials through a sintering process to form positive electrode active material particles, which are then applied to the surface of the current collector layer to form a porous electrode.

48. The semi-solid-state lithium-sulfur battery according to claim 46, characterized in that: The electrolyte comprises an organic electrolyte and a lithium salt. The organic electrolyte is selected from any one or a combination of two or more of carbonate electrolytes, carboxylic acid ester electrolytes, sulfone electrolytes, ether electrolytes, nitrile electrolytes, and ionic liquid electrolytes. The carbonate electrolyte is selected from linear carbonate electrolytes and / or cyclic carbonates. The lithium salt is selected from any one or a combination of two or more of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium di(oxalato)borate, and lithium di(fluorooxalato)borate.

49. The semi-solid-state lithium-sulfur battery according to claim 46, characterized in that: The diaphragm is selected from any one of organic / inorganic composite membranes, ceramic-coated diaphragms, non-woven fabric diaphragms, and polyimide nanofiber diaphragms.

50. The method for preparing a semi-solid lithium-sulfur battery according to any one of claims 46-49, characterized in that... include: The semi-solid lithium-sulfur battery is obtained by assembling a sulfur-carbon cathode, a separator, and a lithium-containing composite solid anode for a semi-solid lithium-sulfur battery, and then injecting an electrolyte.

51. The preparation method according to claim 50, characterized in that, The preparation method includes: Elemental sulfur and carbon materials are uniformly composited using a sintering method to form positive electrode active material particles; and... The positive electrode active material particles are coated or encapsulated on the surface of the current collector layer to form a porous electrode, thereby obtaining the sulfur-carbon positive electrode.

52. The preparation method according to claim 51, characterized in that: The current collector layer is a conductive nickel foam-like current collector.

Images