Exploring the cycle behavior of electrodeposited vanadium oxide electrochemical capacitor electrodes in various aqueous environments

Electrodeposited vanadium oxide has emerged as a potential electrochemical capacitor material due to its attractive initial pseudocapacitive performance. However, it suffers from capacitive degradation upon charge/discharge cycling in aqueous electrolytes. Possible degradation mechanisms, including material dissolution, are discussed. To test these possible mechanisms, an agar gel coating is deposited on the films to reduce mass transport between the electrode/electrolyte interface. The electrochemical cycling behavior of vanadium oxide films with various surface treatments is investigated at different pH. Quantitative compositional analysis and morphological studies provide additional insight into the mechanism responsible for capacitive degradation.

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► Electrodeposited vanadium oxide films were tested in multiple aqueous environments.
► The morphology is pH-dependent and does not exhibit smoothing upon cycling.
► Material dissolution is the primary cause of capacitive degradation upon cycling.
► The dissolved species are determined for each pH environment tested.