1381 results about "Lithium sulfur" patented technology

The invention relates to a method for preparing lithium sulfide, which comprises the following steps: respectively dissolving a sulfur source compound and a lithium source compound in alcohol under the protection of inert atmosphere, and then mixing the two alcohol solutions for double decomposition reaction to generate a lithium sulfide suspension; and then carrying out evaporative crystallization, supercritical fluid washing, centrifugal separation and freeze drying treatment to obtain a lithium sulfide product. The purity of the lithium sulfide prepared through the method can reach 99.9% or above, the lithium sulfide can be used as a positive electrode material of a lithium-sulfur battery or a raw material of a sulfide solid electrolyte in an all-solid-state battery, and the method is low in energy consumption, conforms to the concept of green chemistry and is suitable for large-scale industrial production.

The invention relates to the technical field of lithium-sulfur batteries, and discloses a sulfonyl ZIF-8 metal organic framework material, a lithium-sulfur battery diaphragm and a preparation method of the lithium-sulfur battery diaphragm. The preparation method of the sulfonyl ZIF-8 metal organic framework material comprises the following steps: dissolving a metal precursor and a mixed ligand in an organic solvent, and carrying out a coordination reaction under the action of organic alkali; solid is collected, washed and dried, and the sulfonic group ZIF-8 metal organic framework material is obtained. The metal precursor is soluble zinc salt; the mixed ligand comprises 2-methylimidazole and an imidazole derivative containing a sulfonic acid group. The sulfo group ZIF-8 metal organic framework material is prepared through a ligand doping strategy and is used for functional modification of the lithium-sulfur battery diaphragm; the shuttle behavior of lithium polysulfide (LiPS) can be effectively inhibited through the electrostatic repulsion effect of sulfonic acid groups and the synergistic effect of high-polarity adsorption sites; and the migration of Li < + > and the conversion efficiency of LiPS are remarkably promoted by an efficient ion transmission network, so that the cycle performance of the lithium-sulfur battery is improved.

The invention discloses a preparation method and application of a composite sulfur positive electrode packaged by a sulfide-halide composite electrolyte spherical shell. The composite sulfur positive electrode packaged by the sulfide-halide composite electrolyte spherical shell provided by the invention has a core-shell structure, the inner core is a sulfur-carbon composite material, and the outer layer is a sulfide-halide composite electrolyte shell; the sulfur volume change effect in the charging and discharging process can be effectively relieved, uniform stress distribution and effective contact in the composite positive electrode are ensured, and the utilization rate of positive electrode active substances and the overall energy density of the battery are improved. Meanwhile, the composite sulfur positive electrode provided by the invention has high ionic conductivity at room temperature, can significantly improve the reaction kinetics of the positive electrode and improve the capacity and rate capability of the battery, can be used for assembling and preparing a solid-state lithium-sulfur battery, has good safety performance and high energy density, and has a wide application prospect.

The present invention relates to a carbon structure, which can stably support a high content of sulfur in pores and has excellent electrical conductivity properties, wherein the carbon structure is a polyhedron, of which the center on at least one side is concave, and is a highly graphitized nitrogen-doped porous carbon structure. Therefore, the stability of lithium-sulfur batteries can be improved by effectively suppressing a s shuttle phenomenon occurring during an electrochemical reaction of lithium-sulfur batteries containing, as a cathode active material, the carbon structure supporting sulfur as well as minimizing the volume change resulting from sulfur and reduced lithium sulfide.

The invention discloses a high-interface-stability composite solid electrolyte membrane as well as a preparation method and application thereof. The composite solid electrolyte membrane comprises a gradient aperture three-dimensional porous skeleton formed by sintering inorganic solid electrolyte particles, a polymer electrolyte filled in a pore channel, and a plastic interface stable layer positioned between the electrolyte membrane and an electrode. The preparation method comprises the following steps: preparing a gradient aperture porous framework through a pore-forming agent template method and a tape casting technology, dipping and filling a polymer electrolyte precursor solution in a solution, accelerating in-situ polymerization by adopting electric induction, and performing hot-pressing treatment. The composite solid-state electrolyte membrane has high ionic conductivity, excellent interface compatibility and high mechanical strength, can effectively inhibit the growth of lithium dendrites, can be applied to solid-state batteries such as lithium metal batteries, lithium sulfur batteries and lithium air batteries, and can remarkably prolong the cycle life and improve the safety performance of the batteries, and the preparation process is suitable for large-scale production.

The invention provides a lithium-sulfur battery abnormal heating diagnosis method and system based on deep learning, and belongs to the technical field of lithium-sulfur battery safety monitoring. According to the method, an enhanced temperature difference sequence is constructed based on temperature and voltage detection data, a temperature state sequence is modeled, and continuous dynamic representation of thermal behaviors is realized; a double-path gating mechanism is designed, a global temperature rise suppression gate is utilized to capture the overall temperature rise trend, and an abnormal temperature rise sensitive gate is combined to focus local violent fluctuation, so that normal charging and discharging temperature rise interference is effectively suppressed, and temperature abnormal probability distribution is output; meanwhile, according to the interval where the current SOC is located, a corresponding voltage compensation function is selected, original voltage data are corrected point by point, a double-group long and short time memory network is designed to extract voltage platform drift characteristics, the perception capability of abnormal drift caused by the polysulfide effect is enhanced, and finally a comprehensive risk index is generated. And when the lithium-sulfur battery is under the polysulfide shuttle effect, the battery heating abnormity identification accuracy and robustness are obviously improved.

The invention relates to the technical field of lithium-sulfur battery materials, and discloses a lithium-sulfur battery diaphragm preparation method, which comprises: 1, material preparation: using polyimide as a base material, boron nitride as a two-dimensional material, and deionized water as a solvent; step 2, substrate material pretreatment: placing a substrate film on a sample table of plasma treatment equipment, closing the equipment, vacuumizing to a set pressure, starting plasma treatment, setting power and time, taking out the film after the treatment is completed, and naturally airing; step 3, preparing dispersion liquid, namely weighing 0.5 g of boron nitride powder; according to the preparation method of the lithium-sulfur battery diaphragm, polyimide is selected as a base material and has excellent mechanical strength, thermal stability, chemical stability and electrical insulation performance, and the base material is chemically modified and physically treated in the preparation process; therefore, the effect of improving the mechanical strength and the thermal stability of the lithium-sulfur battery diaphragm can be achieved.

The invention provides a sulfur positive electrode, a lithium-sulfur battery and a preparation method of the lithium-sulfur battery. The sulfur positive electrode comprises a sulfur positive electrode membrane and an active lithium membrane covering the sulfur positive electrode membrane, the sulfur positive electrode membrane comprises active sulfur, a carbonaceous carrier framework and a solid electrolyte, and the mass ratio of the active sulfur to the carbonaceous carrier framework to the solid electrolyte is (5-35): (10-20): (55-75); the mass of the active lithium is 10-45% of the mass of the active sulfur, the active sulfur is adsorbed on the surface of the carbonaceous carrier framework, and the solid electrolyte is filled between the carbonaceous carrier frameworks adsorbed with the active sulfur. The lithium-sulfur battery comprises the sulfur positive electrode and a lithium-free negative electrode, active lithium and active sulfur react to form Li2Sx, and x is smaller than or equal to 4. According to the all-solid-state lithium-sulfur battery disclosed by the invention, potential safety hazards caused by using a metal lithium negative electrode are avoided; in addition, the active sulfur is cured in the all-solid-state electrolyte, so that the problem of sulfur shuttling is avoided; according to the all-solid-state lithium-sulfur battery, the solid electrolyte is used, a conventional liquid electrolyte is not used, and the battery is safe, reliable and high in energy density.

The invention relates to the technical field of new energy materials and devices, and discloses a lithium-sulfur battery difunctional diaphragm and a preparation method thereof, the lithium-sulfur battery difunctional diaphragm comprises a diaphragm substrate and a load slurry, the load slurry is coated on the surface of the diaphragm substrate; the loaded slurry comprises an electrocatalyst material, and the electrocatalyst material is a monatomic catalyst carbon-based material / diatomic catalyst carbon-based material. The monatomic catalyst carbon-based material is a nickel monatomic catalyst carbon-based material or a cobalt monatomic catalyst carbon-based material; the diatomic catalyst carbon-based material is a nickel-cobalt diatomic catalyst carbon-based material. The nickel-cobalt diatomic catalyst coupled carbon-based material is applied to the field of lithium-sulfur batteries and serves as a lithium-sulfur battery diaphragm modification material, sulfur redox kinetics can be promoted, the shuttle effect can be inhibited, lithium ion flux can be induced, so that lithium dendrite growth is inhibited, and finally the cycle performance of the lithium-sulfur batteries is improved.

The invention provides a gel electrolyte membrane for a lithium-sulfur battery, the gel electrolyte membrane comprises a base membrane and a polymer electrolyte cured based on the base membrane, and the polymer electrolyte comprises the following raw materials: a halogenated amide additive, a monomer containing unsaturated carbon-carbon double bonds and disulfide bonds, an ether solvent, a lithium salt and an initiator. The gel electrolyte membrane provided by the invention can prevent the consumption of positive and negative active substances while inhibiting the shuttle effect of LiPSs, so that the cycle capacity and electrochemical performance of the lithium-sulfur battery are improved.

The invention discloses a molybdenum carbide / nitrogen-doped carbon composite material and a preparation method and application thereof, and belongs to the technical field of new energy materials and devices. The preparation method comprises the following steps: uniformly mixing ammonium molybdate, glucose and g-C3N4, and carrying out hydrothermal and high-temperature calcination treatment to obtain a composite material (Mo2C / NC) in which a nano Mo2C electrocatalyst is dispersed and distributed on a nitrogen-doped carbon matrix. The nitrogen-doped carbon in the composite material has a hierarchical porous structure, so that the electrolyte permeation and ion transmission capabilities are enhanced; the nitrogen-doped active sites not only enhance the adsorption performance of the porous carbon on polysulfide, but also improve the catalytic activity by optimizing the coordination structure of Mo2C; mo2C can chemically adsorb and efficiently catalyze reversible conversion of polysulfide, and the utilization rate of active substances is increased. When the composite material is used as a positive electrode additive of a lithium-sulfur battery, dissolution and shuttling of polysulfide can be effectively inhibited, so that the battery has high specific capacity, rate capability and excellent cycle reversibility.

A method for fabricating carbon cryogel exhibiting high surface area, an increased mesopore ratio, and cost-efficiency, utilizing biomass-derived, low-cost tannin and formaldehyde. Furthermore, this method incorporates calcium salt as a catalyst, a deviation from the widely used sodium carbonate. The resulting carbon cryogel possesses high surface area, an enhanced mesopore ratio, and improved sulfur loading capacity, rendering them ideal sulfur hosts for Li—S batteries. The present method disclosed herein constitutes a significant improvement over the existing state-of-the-art carbon cryogel for Li—S batteries, with potential implications for the progression of high-performance, cost-effective Li—S batteries.

According to the application of the ZIF-8 coated hemoglobin composite material in preparation of the lithium-sulfur battery, an enzyme solution, an organic ligand and metal ions are co-precipitated through in-situ biomineralization to prepare an MOF-enzyme compound, the method is not influenced by the size of enzyme molecules, the synthesis condition of ZIF-8 is mild, the structure of enzyme cannot be damaged in the reaction process, and the preparation method is simple and easy to implement. And the synthesis process has the advantages of short reaction time, no need of other organic solvents, capability of expanding multiple synthesis, simple synthesis method and high yield. The results of XRD, FIIR and XPS experiments show that the MOF (at) enzyme compound prepared by the method preserves the inherent structure of the enzyme, and when the MOF (at) enzyme compound is assembled into a battery, the electrochemical performance and the dynamic performance of the battery containing ZIF-8 (at) Hb are better.

A method for synergistically preparing lithium sulfide by vacuum molten salt based on hydrogen sulfide-lithium salt reaction belongs to the technical field of battery materials, and comprises the following steps: placing a lithium salt solid in a reactor, introducing a molten salt medium on the surface of the lithium salt or in a reaction system, introducing purified hydrogen sulfide gas under a vacuum auxiliary condition, controlling the reaction temperature to be 200-500 DEG C, and reacting for 1-2 hours; and adjusting the flow rate of hydrogen sulfide to be 50-1000mL / min and the retention time to be 5-180min, continuously exhausting gas to discharge water vapor in the reaction process, stopping introducing hydrogen sulfide gas after the reaction is finished, cooling the system to room temperature under the protection of inert gas, taking out the product, washing to remove residual fused salt, and carrying out vacuum drying to obtain the high-purity lithium sulfide. The prepared lithium sulfide has high purity (greater than or equal to 99.90%), low defect density and an excellent crystal structure, and can be widely applied to lithium-sulfur batteries, all-solid-state batteries and novel energy storage technologies, so that the energy density is improved, the cycle life is prolonged, and the energy consumption is reduced.

Disclosed is an electrolyte for a lithium-sulfur battery and a lithium-sulfur battery including the same, more specifically an electrolyte for a lithium-sulfur battery including a lithium salt, a non-aqueous organic solvent, and an additive, wherein the additive includes a sulfide compound. The electrolyte for the lithium-sulfur battery improves the efficiency and stability of the negative electrode, thereby improving the capacity and lifetime characteristics of the lithium-sulfur battery.

The invention discloses a three-dimensional multi-interface heterostructure lithium-sulfur battery interlayer, a preparation method thereof and a lithium-sulfur battery, and the preparation method comprises the following steps: placing acidified carbon cloth in a mixed solution of cobalt nitrate, nickel nitrate and hexamethylenetetramine for primary hydrothermal reaction to prepare NiCo2O4 (at) CC; the NiCo2O4 (at) CC is placed in a mixed solution of nickel chloride and sodium molybdate, a secondary hydrothermal reaction is carried out, and NiMoO4 (at) NiCo2O4 (at) CC is obtained; according to the preparation method, NiMoO4-coated NiCo2O4-coated CC is subjected to thermal reduction annealing in a mixed atmosphere of hydrogen and argon, the three-dimensional multi-interface heterostructure lithium-sulfur battery interlayer is prepared, active sites of the three-dimensional heterostructure are increased, the oxidation-reduction reaction efficiency under high sulfur loading capacity is improved, the nano-particle anchored amorphous nanosheets form the multi-interface heterostructure, and the performance of the lithium-sulfur battery is improved. Good chemical adsorptivity and catalytic conversion on polysulfide in the battery are realized, and the cycle life of the battery is prolonged.

The invention provides a Mn-based metal organic framework derived Mn2O3 / Mn3O4 heterojunction material as well as a preparation method and application thereof, and belongs to the field of nano material preparation methods and electro-catalysis cross application. The preparation method comprises the following steps: S10, reacting manganese salt, a surfactant and a benzoic acid compound in a solvent to obtain a Mn-based metal organic framework material; s20, calcining the Mn-based metal organic framework material in an inert atmosphere to obtain a carbonized product; and S30, flattening the carbonized product, and calcining the flattened carbonized product in an air atmosphere to obtain the Mn-based metal organic framework derived Mn2O3 / Mn3O4 heterojunction material. The method can be applied to renewable energy sources, is simple in process, universal in preparation condition, high in yield, green and environment-friendly, stable in product morphology and excellent in catalytic activity, shows excellent activity and electrochemical performance in catalysis of lithium polysulfide conversion of a cathode of a lithium-sulfur battery, and is also suitable for medium-scale industrial production.

The invention relates to a dual-rare earth metal catalytic nano material, a diaphragm and a preparation method and application thereof. The preparation method comprises the following steps: carrying out hydrothermal reaction on an aqueous solution containing a carbon source, a hard template, a graphene oxide dispersion liquid, a nitrogen source, a phosphorus source, cerium salt and neodymium salt; then carrying out centrifugal separation to obtain a precipitate, and generating a precursor containing Ce and Nd rare earth bimetallic modified nitrogen and phosphorus doped graphene coated microspheres; and carrying out chemical etching on the precipitate after heat treatment to obtain the dual-rare earth metal catalytic nano material (HCS-coated NPrGO / CeNd). The HCS-coated NPrGO / CeNd can be used as a modification material of a lithium-sulfur battery diaphragm, not only can catalyze the conversion of polysulfide, but also can inhibit the shuttle effect of the polysulfide, so that the lithium-sulfur battery has relatively high capacity under high-rate charge and discharge, and has relatively low capacity fading rate in a high-rate long-cycle test.

The invention discloses a composite positive electrode material applied to an all-solid-state lithium-sulfur battery. The composite positive electrode material comprises elemental sulfur as an active substance, and a high-temperature and high-ionic-conductivity sulfide solid electrolyte as an ionic conductive agent for conducting lithium ions; and the conductive carbon material is used as an electronic conductive agent for conducting electrons. The mass ratio of the elemental sulfur to the conductive carbon material to the sulfide solid electrolyte can be 1: 1: 2. The volume expansion of the active substance sulfur in the obtained composite positive electrode is small, the ion / electron path in the composite positive electrode is excellent, and the assembled all-solid-state battery is high in safety, good in cycle stability and high in energy density and power density.

The invention provides waterborne polyurethane resin and a porphyrin-based lithium-sulfur battery electrode binder prepared from the waterborne polyurethane resin, and particularly relates to high-molecular waterborne polyurethane resin with carboxyl in a molecular chain and a preparation method of the high-molecular waterborne polyurethane resin. The preparation method comprises the following steps: carrying out condensation polymerization reaction on 2, 2-dimethylolpropionic acid, N-methyldiethanolamine and diisocyanate which are used as raw materials to prepare an isocyanate-terminated prepolymer solution, and then sequentially carrying out salifying carboxyl neutralization, emulsification and chain extension to prepare the polyurethane prepolymer. The invention discloses a water-based binder for a lithium-sulfur battery electrode, which is prepared by in-situ crosslinking of the water-based polyurethane resin and porphyrin / metalloporphyrin and has electrocatalytic performance, and a preparation method of a sulfur electrode based on the water-based binder for the lithium-sulfur battery electrode. Compared with a commercial electrode binder, the aqueous binder for the lithium-sulfur battery electrode has higher initial discharge capacity, higher capacity retention ratio and lower charge-discharge voltage polarization, and a brand new thought and scheme are provided for developing a high-performance lithium-sulfur battery.

The invention relates to the technical field of solid-state lithium-sulfur batteries, in particular to application of an iodine-containing conductive ion additive in a sulfur positive electrode of a solid-state lithium-sulfur battery, a positive electrode material as well as a preparation method and application of the positive electrode material. The iodine-containing guide ion additive is used as a redox mediating agent to promote Li2S oxidation, I <-> in the iodine-containing guide ion additive is electrochemically oxidized into iodine in an oxidation state on a conductive material interface of the iodine-containing guide ion additive during charging, and then the iodine in the oxidation state chemically oxidizes Li2S in contact with the iodine in the oxidation state. On the basis of a redox mediation process on the surface of the iodine-containing guide ion additive, the reaction on a Li2S two-phase interface of the iodine-containing guide ion additive is carried out, so that the solid reaction kinetics of sulfur is improved; the iodine-containing guide ion additive comprises a compound containing iodine, lithium and sulfur elements, and the molar weight of the iodine element in each mole of the iodine-containing guide ion additive is 0 lt; nI < = 2. The iodine-containing conductive ion additive enables the sulfur positive electrode of the solid-state lithium-sulfur battery and the battery prepared from the sulfur positive electrode to have fast charge performance and high cycle stability.

The invention discloses a preparation method and application of an in-situ curing polymer electrolyte for a lithium-sulfur battery, and belongs to the technical field of solid-state batteries, the preparation method comprises the following steps: stirring and mixing an initiator, a polymeric monomer, a lithium salt and an additive to obtain a uniform precursor solution; and 2, dropwise adding the precursor solution obtained in the step 1 to the surface of a diaphragm, and carrying out thermal initiation polymerization to obtain the polymer electrolyte. According to the preparation method and application of the in-situ curing polymer electrolyte for the lithium-sulfur battery, through an in-situ curing process, shuttling of polysulfide is inhibited, the interface resistance between an electrode and the electrolyte is reduced, and the ion transmission capacity is improved; the nitrate ester additive is added into the electrolyte, so that a nitrogen-rich stable interface layer with high ionic conductivity is formed on the surface of the lithium negative electrode under the condition that the polymerization state of the electrolyte is not damaged, the growth of lithium dendrites is effectively inhibited, and the assembled solid polymer lithium-sulfur battery keeps excellent performance.

The invention discloses a preparation method of an all-solid-state lithium-sulfur battery composite positive electrode, which comprises the following steps: weighing raw materials of sodium thiosulfate, hydrochloric acid and a conductive agent (such as one or more of graphene, carbon nanotubes, conductive carbon black and acetylene black) according to a certain proportion, stirring, precipitating, washing and drying to obtain a sulfur-carbon precursor; and performing mechanical ball milling on the precursor and an electrolyte according to a certain proportion, and grinding with a binder to obtain a composite positive electrode, and taking the composite positive electrode as the positive electrode of the all-solid-state lithium-sulfur battery. According to the invention, the problem of non-uniform lithium ion transmission caused by large particle size of active substance sulfur is solved, so that the utilization rate of the active substance is improved; meanwhile, the problem of non-uniform dispersion of the active substance sulfur and the conductive agent carbon is solved, so that the cycle stability of the battery is improved; in addition, the addition of the binder enhances the contact of each component in the composite positive electrode, thereby obtaining more excellent electrochemical performance.

Discussed is an electrolyte solution for a lithium-sulfur battery including a lithium salt, an organic solvent and an additive, and a lithium-sulfur battery including the same, wherein the additive includes a heterocyclic compound containing at least one double bond, and a heterocycle of the heterocyclic compound comprises an oxygen atom or a sulfur atom.

The present disclosure relates to an electrolyte for a lithium-sulfur battery and a lithium-sulfur battery comprising the same, and the electrolyte for the lithium-sulfur battery comprises a lithium salt and a nonaqueous solvent, wherein the nonaqueous solvent comprises glycol ether, cyclic ether and acyclic ether represented by the following chemical formula 1, the acyclic ether is included in an amount of 15 vol % or less based on the total volume of the nonaqueous solvent, and a ratio of a total volume of the glycol ether to a total volume of the acyclic ether is 5 or more:R1—O—R2  [Chemical formula 1]where R1 is an unsubstituted or substituted C1 to C3 alkyl group, and R2 is an unsubstituted or substituted C3 to C20 alkyl group.

The invention discloses a preparation method and application of a two-dimensional composite material. The preparation method comprises the following steps: adding MXene into formamide, carrying out ultrasonic dispersion to obtain an MXene formamide dispersion liquid, then adding MgAl LDH into the MXene formamide dispersion liquid, carrying out magnetic stirring, washing with absolute ethyl alcohol, and carrying out vacuum drying to obtain a two-dimensional composite material which is marked as MgAl LDH / MXene. The two-dimensional composite material is used for a lithium-sulfur battery diaphragm barrier layer so as to inhibit the shuttle effect of polysulfide. The preparation method is simple and environment-friendly, and the prepared MgAl LDH / MXene two-dimensional composite material is high in specific surface area, has strong affinity to polysulfide, can promote rapid transmission of lithium ions, can provide an instant electron conduction way for adsorbed polysulfide, is applied to a diaphragm barrier layer of a lithium-sulfur battery, and has a good application prospect. The wettability of the electrolyte on the diaphragm and the conversion of polysulfide are enhanced, the problem of volume expansion in the cycle process of the lithium-sulfur battery is relieved, and the redox reaction kinetics is accelerated.

According to the cobalt-doped molybdenum disulfide lithium-sulfur battery composite positive electrode material, the preparation method and the application, a cobalt-doped stable molybdenum disulfide defect structure composite nitrogen-doped graphene material is prepared by combining a solvothermal method and an annealing technology, and the process is mature; the method is simple, and the composite positive electrode material with high sulfur content is easy to obtain. According to the lithium-sulfur battery composite sulfur positive electrode material disclosed by the invention, the strong chemical adsorption effect and catalytic conversion effect of the cobalt-doped stable molybdenum disulfide defect structure composite nitrogen-doped graphene carrier on polar lithium polysulfide are utilized, so that the diffusion of the lithium polysulfide in an ether electrolyte is inhibited, and the electrochemical reaction kinetics is improved; therefore, the shuttling effect is slowed down, and the lithium-sulfur battery has the characteristics of high capacity and long service life.

The invention discloses a composite lithium sulfide positive electrode material as well as a preparation method and application thereof, and belongs to the field of lithium-sulfur batteries. A carbon source and metal salt are subjected to a one-step calcination method, urea reacts with nickel salt and iron salt to generate a nickel nitride and iron nitride compound, glucose and urea generate nitrogen-doped multi-stage porous carbon under the action of a sodium chloride template, and a nickel nitride / iron nitride compound and a nitrogen-doped multi-stage porous carbon composite material are obtained and serve as precursor materials. The preparation method comprises the following steps: mixing lithium sulfide with N-methyl pyrrolidone to prepare lithium sulfide slurry; and immersing the prepared precursor material into the lithium sulfide slurry, and drying to obtain the composite lithium sulfide positive electrode material. Nickel nitride and iron nitride in the material are used as double catalysts and have a synergistic effect to accelerate the redox reaction of lithium sulfide / lithium polysulfide. In addition, the nitrogen-doped multi-stage porous carbon structure can effectively bear lithium sulfide and lithium polysulfide and relieve volume expansion.

The present invention provides a composite positive electrode for an all-solid-state lithium-sulfur battery and a method for preparing the same, belonging to the technical field of positive electrode materials for lithium-sulfur batteries. The composite positive electrode comprises a sulfur / carbon composite material with a gradient surface modification of phosphorus polysulfide and a solid electrolyte. The composite material comprises porous carbon, sulfur, and phosphorus polysulfide, with the sulfur loaded on the outer surface and / or in the pores of the porous carbon, and a phosphorus polysulfide layer with a gradient distribution of a specific structure on the surface of the sulfur / carbon composite. The present invention utilizes the sulfur / carbon composite material with a gradient surface modification of phosphorus polysulfide as a positive electrode material for an all-solid-state lithium-sulfur battery, effectively increasing the active sulfur content and specific capacity of the composite positive electrode layer. The composite positive electrode of the present invention can have an active sulfur content exceeding 50 wt%, a specific capacity calculated based on elemental sulfur exceeding 1300 mAh / g, and a specific capacity based on the total mass of the composite positive electrode exceeding 650 mAh / g. Furthermore, the composite positive electrode exhibits excellent cycle and rate performance.

The invention relates to a method for preparing lithium sulfide at low temperature by microwave molten salt assisted carbon disulfide-lithium salt reaction, and belongs to the technical field of key materials of lithium-sulfur batteries and solid-state batteries. The technical problems of high energy consumption, difficulty in inhibiting by-products, insufficient purity and crystal phase stability, difficulty in continuous amplification and the like in the existing lithium sulfide preparation process are solved. Comprising the following steps: step 1, performing crushing, screening and grading treatment on lithium source powder; step 2, placing the treated lithium source powder and molten salt in a closed reactor, and introducing CS2 in a gas or liquid form; 3, applying microwave radiation, and reacting at a gas-solid-liquid multiphase interface to generate lithium sulfide; and 4, cooling the material after the reaction to room temperature, separating and recovering the fused salt to obtain the lithium sulfide powder. The method is low in reaction temperature, low in energy consumption, high in reaction rate, high in product purity and suitable for continuous and industrial production.