Achieving High‐Performance 3D K⁺‐Pre‐intercalated Ti₃C₂T_<i>x</i> MXene for Potassium‐Ion Hybrid Capacitors via Regulating Electrolyte Solvation Structure

Abstract

The development of high-performance anode materials for potassium-based energy storage devices with long-term cyclability requires combined innovations from rational material design to electrolyte optimization. A three-dimensional K⁺ -pre-intercalated Ti₃ C₂ T_x MXene with enlarged interlayer distance was constructed for efficient electrochemical potassium-ion storage. We found that the optimized solvation structure of the concentrated ether-based electrolyte leads to the formation of a thin and inorganic-rich solid electrolyte interphase (SEI) on the K⁺ -pre-intercalated Ti₃ C₂ T_x electrode, which is beneficial for interfacial stability and reaction kinetics. As a proof of concept, 3D K⁺ -Ti₃ C₂ T_x //activated carbon (AC) potassium-ion hybrid capacitors (PIHCs) were assembled, which exhibited promising electrochemical performances. These results highlight the significant roles of both rational structure design and electrolyte optimization for highly reactive MXene-based anode materials in energy storage devices.