Microstructure-controlled amorphous carbon anode via pre-oxidation engineering for superior potassium-ion storage

Abstract

Amorphous carbon is considered as a potential anode material for potassium ion batteries due to its advantages of low cost, diverse precursors and structural plasticity. However, constructing a rational carbon structure through a simple fabrication process to achieve superior potassium storage remains challenging yet. Herein, carbonized pre-oxidation coal tar pitch (CPO-CTP) with controlled microstructure is proposed to boost potassium storage capacity and rate capability. Introducing oxygen-containing functional groups into coal tar pitch (CTP) can induce the establishment of cross-linked structures, which can limit the rearrangement of carbon layers during the carbonization process and is the key to disorder in the microstructure. Benefiting from a rational pre-oxidation approach, CPO-CTP200 exhibits both rich active sites and fast K+ diffusion kinetics, resulting in high charge capacity (460.8 mAh g−1 at 0.05 A g−1 after 50 cycles) and high rate (189.8 mAh g−1 at 2 A g−1), as well as favourable initial Coulombic efficiency (67.12%). This study provides a promising approach for large-scale production of high-performance carbon anode materials for batteries based on CTP through a green pre-oxidation strategy.