N-Doped Porous Graphite-Like Carbon Armored with Dense Amorphous Shell Through a Trojan Horse Strategy for High Performance Potassium-Ion Battery Anode

Abstract

N-doped porous carbon materials are promising potassium-ion battery anodes for overcoming the depressing rate performance and poor cycling stability issues associated with the oversized radius of K-ion. However, the relatively low initial coulombic efficiency (ICE) as a result of porous structure and doped heteroatoms may limit the future application of potassium-ion batteries. Herein, a novel N-doped porous graphite-like carbon armored with dense amorphous shell is synthesized through a Trojan horse strategy by etching and doping the carbon matrix from inside out using oxidized coal tar pitch coated C₃N₄ as precursor. The N-doped porous interior, which endows anode outstanding rate performance (156.5 mAh g⁻¹ at 10 A g⁻¹) and superior reversible capacity (412.3 mAh g⁻¹ at 0.05 A g⁻¹), is isolated from the electrolyte by the external dense shell to gain a high ICE of 62.6%. In addition, the integrated structure mitigates the risk of phase separation between the shell and core, thereby high-current stability over 6000 cycles obtained. This work shed a new light on the fabrication of the well-balanced carbon anodes to meet the demand of the future PIBs industry.