Boosting Zinc-Ion Storage Capability in Longitudinally Aligned MXene Arrays with Microchannel Architecture

Abstract

Flexible Zn²⁺ ion hybrid capacitors (ZHCs) will play a crucial role in developing next-generation wearable products, which demand portability, durability, and environmental adaptability. To further meet these requirements, Ti₃C₂T_x MXene with exceptional conductivity and robust mechanical properties can be utilized as cathodes, except for challenges such as the dense stacking of Ti₃C₂T_x nanosheets. In this study, a novel MXene cathode architecture has been developed with the facilitation of an ice template, which creates longitudinally aligned Ti₃C₂T_x arrays with microchannels. The introduction of hydrochloric acid to the Ti₃C₂T_x slurry induces a crumpled morphology, increasing active sites and enhancing ion transport with expanded interlayer spacing. Interestingly, experimental results and COMSOL simulations verify that the cathode structure also has effective impacts on the Zn anode with a weakened ion concentration gradient and suppressed dendrite formation. Consequently, the ZHCs exhibit enhanced electrochemical performance with excellent rate performance and long-term cycling stability (enduring over 50 000 cycles at 5 A g⁻¹) and further deliver a reliable low-temperature operation by applying an anti-freezing electrolyte. Moreover, flexible ZHCs assembled with gel electrolytes demonstrate excellent flexibility, improved rate performance, and mechanical stability, making them well-suited for flexible electronics that power flexible LED panels.