Configuring single-layer MXene nanosheet onto natural wood fiber via C–Ti–C covalent bonds for high-stability Li-S batteries

Abstract

Lithium-sulfur batteries (LSBs) are considered promising candidates for next-generation battery technologies owing to their outstanding theoretical energy density and cost-effectiveness. However, the low conductivity and polysulfide shuttling effect of S cathodes severely hamper the practical performance of LSBs. Herein, in situ-generated single layer MXene nanosheet/hierarchical porous carbonized wood fiber (MX/PCWF) composites are prepared via a nonhazardous eutectic activation strategy coupled with pyrolysis-induced gas diffusion. The unique architecture, wherein single layer MXene nanosheets are constructed on carbonized wood fiber walls, ensures rapid polysulfide conversion and continuous electron transfer for redox reactions. The C–Ti–C bonds formed between MXene and PCWF can considerably expedite the conversion of polysulfides, effectively suppressing the shuttle effect. An impressive capacity of 1301.1 mA h g−1 at 0.5 C accompanied by remarkable stability is attained with the MX/PCWF host, as evidenced by the capacity maintenance of 722.6 mA h g−1 after 500 cycles. Notably, the MX/PCWF/S cathode can still deliver a high capacity of 886.8 mA h g−1 at a high S loading of 5.6 mg cm−2. The construction of two-dimensional MXenes on natural wood fiber walls offers a competitive edge over S-based cathode materials and demonstrates a novel strategy for developing high-performance batteries.