Interlayer Engineering of K<sub><i>x</i></sub>MnO<sub>2</sub> Enables Superior Alkali Metal Ion Storage for Advanced Hybrid Capacitors
Lina Chen, Yamin Zhang, Chongyang Hao, Xiaowen Zheng, Qidi Sun, Youri Wei, Bohao Li, Lijie Ci, Jun Wei
Abstract
Abstract The lack of ideal cathode materials is a great challenge in the development of hybrid capacitors based on various alkali metal ions. In this work, potassium‐ion pre‐intercalated K x MnO 2 nanowires with enlarged interplanar spacing and optimized ion diffusion channels are successfully obtained through a hydrothermal process, and exhibit superior electrochemical property in lithium‐, sodium‐, and potassium‐ion‐based hybrid supercapacitors (HSCs). The potassium‐ion hybrid supercapacitor (KIC) assembled with a K x MnO 2 cathode and activated carbon anode delivers a high energy density of 49.2 Wh kg −1 , a high power density of 4.7 kW kg −1 , and outstanding cycling performance up to 7000 cycles with almost no capacitance decay, which outperforms most of the KICs reported previously. This ion intercalation engineering provides a strategy to design high‐performance cathodes for hybrid capacitors and other battery systems.