Department of Chemistry, Imperial College London , 82 Wood Lane, W12 0BZ London, United Kingdom; Department of Physics and Astronomy, University of Bologna , 40127 Bologna, Italy
Heather Au
Department of Chemical Engineering, Imperial College London , South Kensington Campus SW7 2AZ London, United Kingdom
Department of Chemical Engineering, Imperial College London , South Kensington Campus SW7 2AZ London, United Kingdom; School of Materials Science and Engineering, Queen Mary University of London , E1 4NS London, United Kingdom
We present a combination of experiments and theory to study the effect of sulfur doping in hard carbons anodes for sodium-ion batteries. Hard carbons are synthesised through a two step process: hydrothermal carbonisation followed by pyrolysis of a biomass-derived carbon precursor. Subsequent sulfur doping is introduced via chemical-vapour deposition. The resulting sulfur-doped hard carbon shows enhanced sodium storage capacity with respect to the pristine material, with significantly improved cycling reversibility. Atomistic first principles simulations give insight into this behaviour, revealing that sulfur chemisorbed onto the hard carbon increases the sodium adsorption energies and facilitates sodium desorption. This mechanism would increase reversible Na storage, confirming our experimental observations and opening a pathway towards more efficient Na-ion batteries.
