Microporous tungsten oxide spheres coupled with Ti3C2T x nanosheets for high-volumetric capacitance supercapacitors.

In the contemporary landscape of technological advancements, the burgeoning demand for portable electronics and flexible wearable devices has necessitated the development of energy storage systems with superior volumetric performance. Tungsten oxide (WO₃), known for its high density and theoretical capacitance, is a promising electrode material for supercapacitors. However, low conductivity and poor cycling stability are still the key bottlenecks for its application. Herein, a novel composite comprising hollow porous WO₃ spheres (HPWS) derived by template method was electrostatic self-assembled on the surface of the Ti₃C₂T _x nanosheets. The resulting electrodes exhibited ultra-high volumetric capacitance of 1930 F cm⁻³ at 1 A g⁻¹ and rate capability of 46% at 50 A g⁻¹, attributed to enhanced ion accessibility from microporous structure and electron transport from conductive network of Ti₃C₂T _x even at a high packing density of 3.86 g cm⁻³. Utilizing HPWS/Ti₃C₂T _x as the negative electrode and porous carbon as the positive electrode, the assembled asymmetric supercapacitor achieved an energy density of 31 Wh kg⁻¹ at a power density of 650 W kg⁻¹ with over 107% capacitance retention after 5000 cycles. This work provides a promising approach for developing next-generation supercapacitors with ultra-high volumetric capacitance. [ABSTRACT FROM AUTHOR]