Regulating the Wettability of Hard Carbon through Open Mesochannels for Enhanced K+ Storage

Abstract Hard carbons are deemed as promising anode materials for high‐performance potassium‐ion battery, but their commercialization is still hindered by the insufficient K + transfer kinetics and poor potassiophilicity. Herein, these issues are addressed by improving the wettability of hard carbon, which can be achieved by the introduction of open mesochannels. A series of such hollow mesoporous carbon capsules with different dimensions are synthesized, which exhibit markedly enhanced wettability with electrolyte compared to the microporous counterparts. Various characterizations confirm its effects on promoting the kinetics and potassiophilicity of as‐synthesized carbons, which can be additionally improved by S‐doping. As a result, the 2D mesoporous carbon anode exhibits excellent rate capability (122.2 mAh g ‐1 at 4 A g ‐1 ), high reversible capacity (396.6 mAh g ‐1 at 0.1 A g ‐1 after 200 cycles), and outstanding cycling stability (197.0 mAh g ‐1 at 2 A g ‐1 after 1400 cycles). In addition, the hollow mesoporous architecture can effectively buffer the volume expansion and thus stabilize the carbon anodes, as visualized by in situ transmission electron microscopy. This work provides new insight for enhanced K + storage performance from the perspective of anode wettability with electrolyte, as well as a universal anode design that combines mesochannels architecture with heteroatom doping.