“…27 In particular, heteroatom-doped carbon is beneficial for improving the electronic conductivity and maintaining cycling stability. 28 For example, Zhang et al 29 and Liu et al 30 fabricated nano-sized metal sulfide composites into heteroatom-doped carbon materials for improving electronic conductivity and ion transport paths. Despite these tremendous efforts being made, comprehensive Na + storage performances, including cycling stability, specific capacity and rate performance, are still limited by structural instability and inaccessible active sites.…”