Liquid Template Assisted Activation for "Egg Puff"-Like Hard Carbon toward High Sodium Storage Performance.

The slow solid diffusion dynamics of sodium ions and the side-reaction of sodium metal plating at low potential in the hard carbon anode of sodium ion batteries (SIBs) pose significant challenges to the safety manipulation of high-rate batteries. Herein, a simple yet powerful fabricating method is reported on for "egg puff"-like hard carbon with few N doping using rosin as a precursor via liquid salt template-assisted and potassium hydroxide dual activation. The as-synthesized hard carbon delivers promising electrochemical properties in the ether-based electrolyte especially at high rates, based on the absorption mechanism of fast charge transfer. The optimized hard carbon exhibits a high specific capacity of 367 mAh g at 0.05 A g and 92.9% initial coulombic efficiency (ICE), 183 mAh g at 10 A g , and ultra-long cycle stability of reversible discharge capacity of 151 mAh g after 12,000 cycles at 5 A g with the average coulombic efficiency of ≈99% and the decay of 0.0026% per cycle. These studies will undoubtedly provide an effective and practical strategy for advanced hard carbon anode of SIBs based on adsorption mechanism.