Pore structure engineering in carbon microsphere for fast potassium/lithium storage

Abstract

Porous structure design is generally considered to be an effective strategy to enhance ions diffusion kinetics for carbon anode materials. In particular, mesoporous structures can enrich the active sites and enhance the structure stability during potassium storage. Herein, porous carbon nanosheet microspheres (PCNMs) is reported via the chemical deposition of pitch-derived carbon on the basic zinc carbonate (Zn5(CO3)2(OH)6) microspheres composited of nanosheets. The mesopores is further enriched by the in-situ pulverization of from Zn5(CO3)2(OH)6 nanosheets to ZnO nanoparticles. Compared to carbon monoliths (CMs), PCNMs possess both more abundant mesoporous and carbon defects. Benefiting from rich defect sites and fast ion diffusion kinetics, PCNMs-700 exhibits a superior reversible capacity (323 mAh g−1at 0.05 A g−1 after 50 cycles) with 92% capacity retention and a high rate (157 mAh g−1at 1 A g−1) in potassium-ion half cells. Similarly, when being applied to potassium ion hybrid capacitors, PCNMs-700 electrode performs a fast potassium storage capacity (81.2 mAh g−1 after 1500 cycles at 1 A g−1) with 92% capacity retention. This work provides a rational guide of pore engineering in carbon for fast ion storage.