Lithium dendrite holey strategy for enabling high-rate and wide-temperature all-solid-state Ti3C2Tx fiber supercapacitor

Abstract

Ti₃C₂T_x nanosheet has been considered as one of ideal precursor units for constructing fiber electrodes in fiber-shaped supercapacitors (FSCs) due to their high conductivity, abundant active sites, and excellent flexibility. Introducing porosity into Ti₃C₂T_x nanosheets for assembling fiber electrodes is a promising strategy to enhance axial ion transport along the vertical fiber. However, current porous Ti_3-αC₂T_x-β nanosheets prepared by conventional chemical etching methods often suffered from significant loss of Ti elements and surface functional groups, resulting in poor wettability of the material dispersion and difficulties in fiber spinning, as well as a substantial reduction in oxidation/reduction active sites. Herein, a lithium dendrite piercing technology was proposed for preparing a physical pore-engineered Ti₃C₂T_x nanosheets (P-Ti₃C₂T_x) with avoiding degradation of Ti/C ratio. Meanwhile, P-Ti₃C₂T_x was enable to be spun into fibers on basis of excellent ink properties and liquid crystal dispersibility. The obtained P-Ti₃C₂T_x fiber electrode exhibited an outstanding volumetric capacitance of 1413 F cm^-3, along with exceptional rate capability (86% capacity retention at 20 A cm^-3). Besides, a non-toxic and wide-temperature polyvinyl alcohol-glycerol hydrogel electrolyte had also been developed for P-Ti₃C₂T_x based FSCs. This FSCs achieved a remarkable volumetric energy density of 320.5 mWh cm^-3 at 26.5 mW cm^-3, maintains 80% capacitance after 20,000 cycles, and operated stably across a wide temperature range (-40 to 60 °C). This work provides a unique methodology for high-performance and wide-temperature FSCs in next-generation wearable energy storage systems.