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 . Significantly, when the current density is elevated to an ultrahigh rate of 5000 mA g , a high reversible capacity of 228 mAh g 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.