N, P, O-codoped biochar from phytoremediation residues: a promising cathode material for Li-S batteries

Environment and energy are two key issues in today's society. In terms of environmental protection, the treatment of phytoremediation residues has become a key problem to be solved urgently, while for energy storage, it tends to utilize low-cost and high specific energy storage materials (i.e. porous carbon). In this study, the phytoremediation residues is applied to the storage materials with low-cost and high specific capacity. Firstly, the phosphorous acid assisted pyrolysis of oilseed rape stems from phytoremediation is effective in the removal of Zn, Cu, Cd and Cr from the derived biochar. Moreover, the derived biochar from phytoremediation residues shows abundant porous structure and polar groups (-O/-P/-N), and it can deliver 650 mAh g^-1with 3.0 mg cm^-2_sulfur, and keeps 80% capacity after 200 cycles when employing it as a sulfur host for lithium-sulfur (Li-S) batteries. Hence, phosphorous acid assisted pyrolysis and application in Li-S battery is a promising approach for the disposal of phytoremediation residues, which is contributed to the environmental protection as well as energy storage.