Influence of catholyte composition on the performances of VACNT/Polysulfides/Li cells

摘要

Elemental sulfur has become a particularly attractive material for lithium metal batteries owing to its low cost, availability, non-toxicity and high specific capacity of sulfur active material. Problematics of the Li/S cell arise from its particular mechanism, based on dissolution/precipitation phenomena of active materials along cycling. The phase transitions endured by active material are responsible for dramatic changes in the morphology of the positive electrode upon cycling, and results in severe capacity fading. In this work, vertically-aligned carbon nanotubes (VACNT) were investigated as a positive electrode 3D current collector for Li/S cells, combined with a semi-liquid VACNT/Polysulfides (catholyte)/Li battery configuration. The influence of the catholyte composition and the sulfur concentration, and the impact of electrolyte solvents and additives in the catholyte were investigated, yielding significant improvements in terms of practical surface capacity of the cells. (C) 2015 Elsevier Ltd. All rights reserved.