Traditional Chinese medicine residue-derived micropore-rich porous carbon frameworks as efficient sulfur hosts for high-performance lithium–sulfur batteries

Biomass-derived carbon-based energy materials are receiving extensive attention nowadays. With the widespread use of traditional Chinese medicines in the treatment of diseases and health care, a great deal of herb residues are thrown away after the unique decoction process. Here, through hydrothermal carbonization combined with KOH activation, a micropore-rich and nitrogen-doped porous carbon framework (MRNCF) is prepared from the waste roots of a kind of well-known and widely used traditional Chinese medicine, Acanthopanax senticosus. Compared with ordinary carbon-based sulfur host materials, the MRNCFs can effectively hinder the shuttling effect and dissolution of polysulfides through the synergistic action of physical confinement in micropores and chemical anchoring for nitrogen doping, and the lithium-sulfur batteries using MRNCF as the host present superior electrochemical performance. In a high sulfur content of over 75%, the as-prepared electrodes exhibit a highly reversible specific capacity of 540.4 mA h g-1 at a current density of 0.5C after 150 cycles and an excellent rate capability at different current densities.