Advanced Pseudocapacitive Performances of a Ti₃C₂T_x–ZnOHF/ZnO Nanocomposite for Energy Storage Applications

The growing demand for efficient and high-performance energy storage systems is driving the exploration of novel materials and composites. Traditional electrode materials often face limitations in terms of energy and power densities. This article demonstrates a novel spray-coated cathode electrode system composed of Ti₃C₂T_x MXene and zinc hydroxy fluoride/zinc oxide nanostars for energy storage applications in a neutral pH electrolyte (1M Na₂SO₄), thus avoiding corrosion problems related to water splitting reactions. Optimized Ti₃C₂T_x-nanostar electrodes exhibit superior specific capacitance, achieving 236 F g^-1 at 5 mV s^-1 in cyclic voltammetry and 139 F g^-1 at 5 mV s^-1 in galvanostatic charge-discharge measurements, which is superior to pure Ti₃C₂T_x (115 F g^-1 at 0.5 A g^-1) and pure nanostar (108 F g^-1 at 0.5 F g^-1) electrodes, used as reference. Additionally, an asymmetric Ti₃C₂T_x||Ti₃C₂T_x-nanostars supercapacitor device achieves a specific capacitance of 147 F g^-1 at 0.5 A g^-1, an energy density E_d ≈ 46 W h kg^-1 at a power density P_d ≈ 875 W kg^-1, and the highest P_d ≈ 16 650 W kg^-1 at E_d ≈ 14 W h kg^-1. These findings demonstrate that zinc oxide nanostars combined with delaminated Ti₃C₂T_x MXene hold a significant promise for efficient energy storage applications, leveraging the synergy between double-layer capacitance and pseudocapacitive effects.