Preparation of a macroscopic, robust carbon-fiber monolith from filamentous fungi and its application in Li–S batteries

Abstract

A new sustainable microorganism-based route is reported for the synthesis of carbon-fiber monolith through using filamentous fungi as feedstock. The fungi are cultured in solution within three days with biomass as nutrient, and fungi concentration reaches as high as 11 mg mL⁻¹ on an average. Based on the rational control of fungi filtration and drying, fungi membrane or aerogel was obtained. Through pyrolysis in an inert atmosphere, intact carbon-fiber monolith (membrane or aerogel) was formed and its conductivity was more than 1 S cm⁻¹. The carbon-fiber aerogel and membrane synthesized at 800 °C was doped by N (∼2.4 at%) and O (∼1.3 at%) and displayed a BET surface area of ∼305 and ∼20 m² g⁻¹, respectively. Mesopores and macropores were detected in the carbon materials. The carbon-fiber monolith showed promising capability to improve the cyclability and capacity of lithium–sulphur (Li–S) batteries, and are expected to be used as versatile electrode in energy storage.