Fabrication of carbon nanofibril/carbon nanotube composites with high sulfur loading from nanocellulose for high-performance lithium‑sulfur batteries

Recently, lithium‑sulfur batteries have attracted much more attention due to their high specific capacity, energy density and wide range of sources. Here, a simple method to prepare sulfur host material was explored. In this method, carbonized cellulose nanofibrils doped with carbon nanotubes were used as the matrix and applied in the cathode. It was found that the sample 40-CNFC with the mass ratio of carbon nanotubes to cellulose dry weight of 4:6 showed the best three-dimensional porous network structure, and its specific surface area was up to 254.4 m2 g−1. After loading sulfur, the initial specific capacity of 40-CNFC@S was 1168 mAh g−1 at 0.1C, and the initial specific capacity of 858 mAh g−1 was still up to 739 mAh g−1 after 120 cycles at 0.5C, providing an available access for designing a promising electrode material for lithium‑sulfur batteries. [Display omitted] •Carbon aerogels fabricated from TEMPO-oxidized cellulose nanofibrils had plenty of nanopores.•Carbon nanotubes were effective to improve the electrical conductivity, thus enhancing the specific capacity.•The initial specific capacity could be up to 1168 mAh g-1 at 0.1C and the capacity remained 86% after 120 cycles at 0.5 C.•Abundant nanopores on the carbon nanofibrils could effectively inhibit the dissolution and diffusion of polysulfide.