Hard carbons (HCs) have gained much attention for next-generation high energy density lithium-ion battery (LIB) anode candidates. However, voltage hysteresis, low rate capability, and large initial irreversible capacity severely affect their booming application. Herein, a general strategy is reported to fabricate heterogeneous atom (N/S/P/Se)-doped HC anodes with superb rate capability and cyclic stability based on a three-dimensional (3D) framework and a hierarchical porous structure. The obtained N-doped hard carbon (NHC) exhibits an excellent rate capability of 315 mA h g-1 at 10.0 A g-1 and a long-term cyclic stability of 90.3% capacity retention after 1000 cycles at 3 A g-1. Moreover, the as-constructed pouch cell delivers a high energy density of 483.8 W h kg-1 and fast charging capability. The underlying mechanisms of lithium storage are illustrated by electrochemical kinetic analysis and theoretical calculations. It is demonstrated that heteroatom doping imposes significant effects on adsorption and diffusion for Li+. The versatile strategy in this work opens an avenue for rational design of advanced carbonaceous materials with high performance for LIB applications.
Keywords: anode; hard carbon; heteroatom doping; lithium storage mechanism; lithium-ion batteries.