Hard Carbon Anode Synthesized by an In Situ Porous Strategy for Advanced Potassium-Ion Batteries

As the next-generation renewable energy-storage technology at the grid scale, potassium-ion batteries demonstrate huge advantages when carbonaceous materials are adopted as K-storage anodes due to their low cost, environmental friendliness, and broad theoretical and practical basis in lithium-ion batteries. However, such kinds of anode materials still suffer from low capacity and severe volume change during the K-storage process. Herein, an approach based on a molecular-scale in situ porous design is proposed to develop carbonaceous electrodes with uniform pores and defective structures. K+ could move rapidly in the bulk electrode along with mitigated volume expansion owing to the abundant channel structure. Moreover, the discharge capacity of the porous hard carbon electrode increases significantly because of the defect structure in the carbon layer. As a consequence, the developed porous hard carbon electrode can maintain a high capacity of 151.9 mAh/g after 2500 cycles at 1 A/g with an average capacity decay rate per cycle of just 0.008%. These excellent K-storage properties can be attributed to the molecular-scale-derived porous structure and defects with increased carbon layer spacing.