Strain-Induced Distortion of MXene Nanosheets Enabling Freestanding Electrodes with Linearly Upscaling Areal Capacitance at Ultrahigh Mass Loadings

Abstract

The development of high-mass-loading electrodes offers a promising solution for enhancing energy density and reducing costs by minimizing inactive components. However, thick electrodes often face challenges, such as structural instability and poor electron and ion transport. Here, we present a strain-induced strategy for preparing distorted MXene nanosheets, enabling the fabrication of pressure-resistant crumpled freestanding electrodes with low tortuosity and a curvature-induced cation enrichment effect. This low tortuosity and curvature-induced cation enrichment of the conductive MXene freestanding electrode synergistically addresses the challenges associated with high mass loadings. This approach is broadly applicable to various MXenes, including V₂CT_x, Ti₃C₂T_x, and V₄C₃T_x. In zinc-ion hybrid capacitors, the freestanding electrodes exhibit an areal energy storage performance that scales linearly with mass loading up to 171.3 mg cm^-2, delivering a high areal capacitance of 57.6 F cm^-2 and a maximum areal energy density of 7.5 mWh cm^-2. For practical applications, a soft-packaged pouch cell was fabricated, with 87.2% capacitance retention after 750 cycles. This work introduces a feasible strategy for the morphological editing of MXenes, showcasing their potential for next-generation areal-efficient energy storage technologies.