Lithium-sulfur battery gel-state positive electrode and preparation method thereof

Abstract

The invention discloses a lithium-sulfur battery gel-state positive electrode and a preparation method thereof. The lithium-sulfur battery gel-state positive electrode comprises a gel layer, the gel layer is formed by fully swelling a polymer skeleton through an electrolyte, and the polymer skeleton is at least formed by blending a conductive polymer and an easy-to-gel polymer and then coating a supporting body with the mixture; and the electrolyte is at least formed by dissolving lithium polysulfide in a high dielectric constant solvent. The gel-state positive electrode has multiple advantages of high sulfur loading capacity, low electrolyte consumption, flexible and stable structure, effective sulfur species confinement, electron conduction and the like, various problems of sulfur insulation, expansion, dissolution, shuttling and the like are effectively solved, and the lithium-sulfur battery prepared from the gel-state positive electrode has high reversible specific capacity and actual specific energy, excellent cycling stability and good safety performance.

Description

technical field [0001] The invention belongs to the technical field of new energy, and in particular relates to a gel-state positive electrode of a lithium-sulfur battery and a preparation method thereof. Background technique [0002] Lithium-sulfur batteries have outstanding advantages such as high theoretical energy density, abundant raw material sources, and environmental friendliness. However, there are currently common defects such as low utilization of active materials, poor cycle stability, and serious self-discharge. This is mainly due to: 1) elemental sulfur and its The poor conductivity of solid-state discharge products leads to low electrochemical activity and serious polarization problems; 2) large volume changes of sulfur before and after lithiation lead to pulverization or even collapse of the electrode structure; 3) the formation of sulfur during charging and discharging The intermediate product lithium polysulfide is easily dissolved in the electrolyte and di...

AI Technical Summary

Problems solved by technology

The combination of sulfur and conductive materials can improve the conductivity of the electrode and confine lithium polysulfides to a certain extent, but it cannot fundamentally solve the problem of volume change in the process of lithium polysulfide dissolution / shuttle and intercalation and delithiation, and the conductive phase as an inactive component will also lead to a decrease in the actual specific capacity of the electrode

The use of flexible polymer materials in the electrode can better adapt to the volume change before and after sulfur lithiation, but the conductivity of most polymers deviates

The use of organic solvents with low dielectric constant and weak solvent capability can inhibit the dissolution of lithium polysulfide, but the ionic conductance of the electrolyte is affected, and the amount of electrolyte is difficult to reduce

Setting a barrier layer between the positive and negative electrodes can physically prevent the diffusion of lithium polysulfide, but as an inactive component, these barrier layers are not conducive to the increase of the volume or mass specific energy of the battery

[0004] To sum up, the existing modification and optimization measures for lithium-sulfur batteries have certain limitations, and cannot solve the various problems of lithium-sulfur batteries from an overall perspective, so the improvement of battery performance is limited.

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