Screening Heteroatom Configurations for Reversible Sloping Capacity Promises High-Power Na-Ion Batteries

Heteroatom doping has been proved to effectively enhance the sloping capacity, nevertheless, the high sloping capacity almost encounters a conflict with the disappointing initial Coulombic efficiency (ICE). Herein, we propose a heteroatom configuration screening strategy by introducing a secondary carbonization process for the phosphate-treated carbons to remove the irreversible heteroatom configurations but with the reversible ones and free radicals remaining, achieving a simultaneity between the high sloping capacity and ICE (≈250 mAh g^-1 and 80 %). The Na storage mechanism was also studied based on this "slope-dominated" carbon to reveal the reason for the absence of the plateau. This work could inspire to distinguish and filter the irreversible heteroatom configurations and facilitate the future design of practical "slope-dominated" carbon anodes towards high-power Na-ion batteries.