Pseudocapacitive Behavior of Ce Modified CoO through a Galvanostatic Charge–Discharge Test: Distinguishing between Surface-Control and Diffusion-Control Current

This paper presents an attempt on deconvoluting diffusion-control current (i_d) and surface-control current (i_s) from total current in a galvanostatic charge–discharge (GCD) test. Using this strategy, the pseudocapacitive behavior of nanosized Ce-CoO dispersed on graphene support was studied in detail. The results show that i_d is greatly affected by operating potential and occupies some proportion of the total pseudocapacitive current. The main functions of Ce in the composite material include promoting the proportion of i_s or inhibiting i_d and finally stimulating a specific capacitance (C_s) value increased from 192 to 726 F g^–1. The Bode curve in the low-frequency region also proves that Ce can promote the performance of pseudocapacitance.