Ceria for supercapacitors: Dopant prediction, and validation in a device

Ceria, its Eu-based (Ce0.9Eu0.1O2), and Cr-based (Ce0.9Cr0.1O2) derivatives are investigated as supercapacitor-electrode material. In this work, doping standalone is used to enhance specific capacitance by ~218% over pristine ceria. The Mott-Littleton method is used to predict the appropriate trivalent dopant (Cr in this case). The experimental study is found to be consistent with the prediction. Specifically, the XPS analysis indicates a higher vacancy concentration in the case of Ce0.9Cr0.1O2 vis-à-vis Ce0.9Eu0.1O2. The former material exhibits a maximum specific capacitance of 328 F g−1, which is ~3 times that of undoped-ceria; the rate capability is reasonable even at 10 A g−1. A Swagelok cell consisting of Ce0.9Cr0.1O2@Ni-foam shows ~100% capacitance retention even after 10,000 cycles. The cell exhibits a low steady-state leakage current of ~17 μA with an overall leakage charge of 49.72 μAh. This study indicates that the Mott-Littleton approach can be used to guide superior dopant selection for supercapacitor application.