Asymmetric pseudocapacitive electrodes for high energy density supercapacitor in aqueous electrolyte

An Asymmetric pseudocapacitor electrodes can achieve higher energy density than carbon-based materials. Ruthenium oxide is the most effective pseudocapacitor material, but it's very expensive and toxic. The use of cerium oxide (CeO₂), which is abundant with good redox properties could be a sustainable alternative for positive electrode. However, CeO₂'s low electronic conductivity limits its performance. To overcome this an asymmetric supercapacitor cell (ASC) was constructed using CeO₂ as the positive electrode and instead of carbon-based materials, MXene (Ti₃C₂T_x) was used as the negative electrode. MXene can deliver better capacitance due to the controllable layer spacing and excellent electronic conduction which can improve the overall conductivity of the ASC. CeO₂//MXene asymmetric cell achieved 122.27 Fg^-1 capacitance with 55.02 Wh Kg⁻¹ energy density, and retained 99.36 % initial capacitance after 10,000 cycles at 20 Ag^-1.