Sulfurized polythiol-rich lithium-sulfur battery cathode composite material and preparation method thereof

Abstract

The invention discloses a vulcanized polythiol-rich lithium sulfur battery positive electrode composite material. In the lithium sulfur battery positive electrode composite material, a reduction-oxidization graphene / polythiol / sulfur composite material takes reduction-oxidization graphene as a conductive modification phase, phlythiol is used for providing a copolymerization site with sulfur, so that the capacity and the charge-discharge stability of the composite material are improved. Sublimed sulfur, graphene oxide, L-cysteine hydrochloride, ammonium hydroxide and deionized water are selected, 90 DEG C is used as a polymerization and reduction temperature, and the polythiol-rich reduction-oxidization graphene is obtained after vacuum filtering, freezing and drying, and the vulcanized polythiol-rich reduction-oxidization graphene is obtained by mixing the polythiol-rich reduction-oxidization graphene and the sublimed sulfur and by thermal processing. The method is simple in productionprocess and relatively low in cost, and the obtained vulcanized polythiol-rich reduction-oxidization graphene composite material has favorable electrochemical performance.

Description

technical field [0001] The invention relates to a composite material, in particular to a vulcanized reduced graphene oxide rich in polythiol, which belongs to the technical field of advanced composite material preparation technology. Background technique [0002] Energy issues are closely related to human life. At present, the main source of energy is fossil energy, however, fossil energy is non-renewable energy, which is gradually exhausted, and its use will bring serious environmental pollution and greenhouse effect. Therefore, we need some clean and renewable energy to replace it, such as wind energy, water energy, solar energy, geothermal energy, etc. However, these cleaning energies require good energy storage devices. [0003] The current commercial lithium-ion battery (take lithium cobalt oxide / carbon battery as an example) has a theoretical energy density of 387 watt-hours per kilogram, but practical applications can only reach about 200 watt-hours per kilogram. Wi...

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Problems solved by technology

Despite these advantages, the practical application of lithium-sulfur batteries still faces the following problems: (1) sulfur, lithium polysulfide and the final product lithium sulfide have extremely low ion and electron conductivity; The dissolution of lithium sulfide can lead to the "shuttle effect" and the resulting insoluble lithium sulfide will be deposited on the surface of the lithium electrode, eventually leading to the complete loss of the capacity of the sulfur electrode; (3) the active electrode will be lost during the lithiation / delithiation process Severe volume changes occur, leading to comminution of the electrode material

As in the prior art ""Sulfur-rich polymeric materials with semi-interpenetrating network structure as a novel lithium-sulfur cathode", Sun Z, Xiao M, Wang S, etal.Journal of Materials Chemistry A, 2014,2(24): 9280-9286" mentions that "the cycle stability of the copolymerization of o-phenylenediacetylene and elemental sulfur is significantly improved, and the capacity remains 70% after 500 cycles at a current density of 1675 milliamperes per gram." However, its discharge specific capacity still needs to be further improved

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