A high-voltage and high-capacity Ti3C2Tx/BiCuS2.5 heterostructure to boost up the energy density and recyclability of zinc-ion-hybrid capacitors

In this paper, a brand-new amorphous Ti3C2Tx/BiCuS2.5 electrode material was first invented by a facile in-situ deposition strategy, whose workable voltage window was enlarged up to 2.0 V (-1.4 V similar to 0.6 V) with an improved capacity to 840 C g(-1) at 1 A g(-1) due to a baton relay mechanism. When the Ti3C2Tx/BiCuS2.5 electrode ma-terial was assembled for an aqueous symmetrical supercapacitor, the device exhibited a maximum energy density of 56.1 Wh kg(-1) at a power density of 15.3 kW kg(-1). After 10,000 cycles, the energy density was even elevated to 63.325 Wh kg-1. When the Ti3C2Tx/BiCuS2.5 material was used for a zinc-ion capacitor cathode, the device exhibited an energy density of 298.4 Wh kg(-1) at a power density of 7200 W kg(-1). The energy density retention of 95% after 7000 cycles and 82% after 10000 cycles clearly proved the good recyclability of Ti3C2Tx/BiCuS2.5 electrode. Based on the attentive DFT simulation and XPS analysis, the energy storage mechanism was ascribed to the co-existence of intercalation and redox battery-type capacity. This work opens a new direction with new electrode materials workable at a high voltage range for the construction of high specific energy supercapacitors.

Automated summary

This paper presents a novel amorphous Ti3C2Tx/BiCuS2.5 electrode material with an enlarged working voltage window for high specific energy supercapacitors. The material exhibited improved capacity and energy density in aqueous symmetrical supercapacitors and zinc-ion capacitors, attributing to a baton relay mechanism and a combination of intercalation and redox battery-type capacity. This work opens a new direction for the construction of high specific energy supercapacitors.