Electrospun-cellulose derived free-standing carbon nanofibers as lightweight, ultrathin, and stackable interlayers for lithium-sulfur batteries

The insertion of an interlayer between the separator and cathode is considered a promising strategy to improve the conductivity as well as suppress the polysulfide shuttling effect in lithium-sulfur batteries (LSBs). However, the fundamental disadvantages of loss in weight/volume capacity and high cost upon the addition of an interlayer brings significant challenges. Herein, we report free-standing carbon nanofibers based on electrospun-cellulose (ACCF) as a lightweight (0.38 mg cm⁻²) and ultrathin (10 μm) interlayer for LSBs. The unique semi-carbonization of cellulose precursors provides a large surface area (2665.2 m² g⁻¹) and high conductivity (6.5 S cm⁻¹) to overcome the conductivity–surface area trade-off in conventional interlayers. Interestingly, the high wettability of ACCF is induced by the functional groups in cellulose, which decreases the electrolyte demand and enables the material to be stacked into multiple layers. This allows a conceptual study providing the scientific clue for the critical material factor in the LSB interlayer. Benefitting from its multi-functional characteristics, ACCF-modified cell provides a high specific capacity of 1403 mA h g⁻¹ and a remarkable areal capacity 4.83 mA h cm⁻² (S loading 4.6 mg cm⁻²) at 0.1C. Therefore, this innovative, cheap, and scalable ACCF can be used as a practical interlayer toward the commercialization of high-energy LSBs.