Application of W1.33CTz MXenes obtained by hydrothermal etching as an additive to enhance the electrochemical energy storage properties of binder-free Ti3C2Tx MXene films

Abstract

In this study, the electrochemical energy storage properties of Ti₃C₂T_x MXene films have been improved by the addition of W_1.33CT_z MXenes with ordered vacancies in their structure. The W_1.33CT_z i-MXene was obtained from the (W_2/3Y_1/3)₂AlC i-MAX phase by etching in a HCl/LiF mixture under hydrothermal conditions followed by delamination by the intercalation of tetramethylammonium ions. Ti₃C₂T_x/W_1.33CT_z composite electrode films were prepared from colloidal solutions, which were mixed in an appropriate ratio to achieve the W_1.33CT_z concentrations of 10, 20, 30 and 40 wt%. MXenes were characterized by XRD, SEM, TEM and XPS methods. The electrochemical energy storage properties of binder-free MXene films were studied by cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) methods. It has been shown that the addition of 20 wt% W_1.33CT_z can significantly improve the pseudocapacitive intercalation of electrolyte ions. The specific capacitance of Ti₃C₂T_x/W_1.33CT_z (20 wt%) electrodes in H₂SO₄, LiCl and KOH electrolytes was 375, 171 and 235 F g⁻¹, respectively, at a scan rate of 5 mV s⁻¹. The composite electrode showed good cycling stability (more than 93% capacity retention after 10 000 cycles). The results obtained indicated that the synthesised composite could be considered a promising electrode material for energy storage systems.