Liquid sulfur positive electrode and semi-liquid lithium-sulfur battery

Abstract

The invention discloses a liquid sulfur positive electrode and a semi-liquid lithium-sulfur battery, the liquid sulfur positive electrode comprises a current collector and a sulfur-containing solution, and the sulfur-containing solution at least comprises polysulfide, a high donor number solvent, organic fluoroether and a catalyst. The liquid sulfur positive electrode is high in sulfur loading capacity, low in electrolyte consumption, moderate in viscosity and good in ionic conductivity, the problems of insulation and volume expansion of the sulfur positive electrode can be solved, meanwhile, sulfur conversion reaction kinetics is promoted, and shuttling of polysulfide can be inhibited. The semi-liquid lithium-sulfur battery manufactured by utilizing the liquid positive electrode has high reversible capacity, good cycling stability and rate capability, and the actual energy density has more advantages than that of the traditional solid lithium-sulfur battery.

Description

technical field [0001] The invention belongs to the technical field of new energy, and in particular relates to a liquid sulfur positive electrode and a semi-liquid lithium-sulfur battery. Background technique [0002] The theoretical energy density of lithium-sulfur batteries is close to 10 times that of traditional lithium-ion batteries, and the source of raw materials is abundant, and the cost is advantageous. However, there are always problems such as low utilization of active materials and poor cycle stability at this stage. The main reasons are poor conductivity of elemental sulfur, large volume change before and after sulfur lithiation, slow conversion kinetics, and easy dissolution and shuttling of intermediate products. Moreover, the battery usually needs to use more electrolyte (that is, the E / S ratio is high), which is not conducive to the actual specific energy improvement, thus greatly hindering its practical application. [0003] The existing technology usuall...

AI Technical Summary

Problems solved by technology

However, at this stage, there are always problems such as low utilization of active materials and poor cycle stability. The main reasons are poor conductivity of elemental sulfur, large volume change before and after sulfur lithiation, slow conversion kinetics, easy dissolution and shuttle of intermediate products, etc.

Moreover, the battery usually needs to use more electrolyte (that is, the E / S ratio is high), which is not conducive to the actual specific energy improvement, thus greatly hindering its practical application process.

[0003] The existing technology usually combines sulfur with conductive materials, which can improve the conductivity of the electrode and confine lithium polysulfides, but it is difficult to fundamentally limit the dissolution / shuttle of polysulfides, and the conductive phase as an inactive component will also cause electrode degradation. Decrease in specific capacity

Optimizing the electrolyte composition (such as using organic fluoroethers) can inhibit the dissolution of polysulfides and protect the lithium anode, but it cannot overcome the low conductivity and volume change defects of the sulfur cathode.

Therefore, these modification and optimization measures have certain limitations, and cannot comprehensively solve various problems existing in lithium-sulfur batteries, and the degree of improvement in battery performance is relatively limited.

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