Liquid Template Assisted Activation for “Egg Puff”‐Like Hard Carbon toward High Sodium Storage Performance

Abstract 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⁻¹ at 0.05 A g⁻¹ and 92.9% initial coulombic efficiency (ICE), 183 mAh g⁻¹ at 10 A g⁻¹, and ultra‐long cycle stability of reversible discharge capacity of 151 mAh g⁻¹ after 12,000 cycles at 5 A g⁻¹ 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.