Enhanced Interfacial Kinetics of Carbon Monolith Boosting Ultrafast Na‐Storage

Slow ion kinetics of negative electrode materials is the main factor of limiting fast charge and discharge of batteries. Sluggish Na + kinetics property leads to large electrode polarization, resulting in poor rate and cyclic performances. Herein, an electrode of ultrasmall tin nanoparticles decorated in N, S codoped carbon monolith (TCM) with exceptional high‐rate capability and ultrastable cycling behavior for Na‐storage is reported. The resulted TCM electrode exhibits an extremely high retention of 96% initial charge capacity after 500 cycles at a current density of 500 mA g −1 . Significantly, when the current density is elevated to an ultrahigh rate of 5000 mA g −1 , a high reversible capacity of 228 mAh g −1 after the 2000th cycle is still maintained. More importantly, the stable and fast Na‐storage of TCM is investigated and understood by experimental characterizations and kinetics calculations, including interfacial ion/electron transport behavior, ion diffusion, and quantitative pseudocapacitive analysis. These investigations elucidate that the TCM shows improved ion/electron conductivity and enhanced interfacial kinetics. An entirely new perspective to deep insights into the fast ion/electron transport mechanisms revealed by interfacial kinetics of sodiation/desodiation, which contributes to the profound understanding for developing fast charging/discharging and long‐term stable electrodes in sodium‐ion batteries, is provided.