Bioderived carbon fiber conductive networks with inlaid electrocatalysts as an ultralight freestanding interlayer for working Li–SeS2 pouch cells

Abstract

Introducing a freestanding functional interlayer has been a conventional tactic to immobilize the soluble polysulfide intermediate in Li–S batteries. However, most of the designed interlayers possess extra heavy weight, casting additional technical challenges toward practical high-specific-energy batteries. Herein, an ultralight self-standing interlayer with an extremely low mass loading (∼0.14 mg cm−2), composed of porous curly carbon fibers derived from natural biomass with inlaid cobalt electrocatalysts (CF–Co), was engineered via a convenient way. After replacing the poor conductivity sulfur (∼10−28 S m−1) by higher conductivity selenium disulfide (SeS2, ∼10−6 S m−1) as active cathode materials, the hierarchically porous-structured, conductive CF-Co interlayer with outstanding adsorptive and electrocatalytic effects is introduced into the resulted Li–SeS2 batteries to capture dual-intermediate polysulfides/polyselenides, boost their conversion kinetics, and ensure favorable running of Li–SeS2 cells with high SeS2 loading and lean electrolyte. Consequently, the coin cells deliver outstanding high-rate capability (404 mAh g−1 at 8 A g−1) and superior cycling stability (∼81.5% areal capacity retention in 125 cycles) under high SeS2 loading (5.0 mg cm−2). Significantly, practical high-areal-capacity (>5.5 mAh cm−2) Li–SeS2 pouch cells can be realized by assembling this interlayer with double-side SeS2-loading cathodes (132 mg), working stably at relatively lower electrolyte condition (6.0 μL mg−1).