Sacrificial Mo–S modification and P-doping co-assisted activation strategy to enhance the electrochemical performance of cobalt carbonate hydroxide hydrate

Abstract

Electrochemical activation to induce micro-morphology reconstruction has been demonstrated to be an effective method to increase the specific surface area of electrode materials, thereby enhancing their specific capacity. Nevertheless, the change in micro-morphology is usually uncontrollable and it decreases the conductivity of the electrode materials. Accordingly, in this work, we propose a sacrificial Mo–S modification to address these problems. Mo–S acted as a sacrificial morphology-control layer to induce the formation of fluffy micro-sheets during activation, not only providing more active sites for the electrochemical reaction of the cobalt carbonate hydroxide hydrate (CCHH), but also reducing the internal resistance by preventing the active materials from falling off the electrode. However, it simultaneously increased the charge transfer resistance (R_ct) of the electrode. In this case, further P-doping treatment improved the R_ct. The obtained CCHH/Mo–S/P/A electrode delivered a high specific capacity of 4.29 C cm⁻² (1429 C g⁻¹) and outstanding cycling performance. In addition, the asymmetric supercapacitors assembled using the CCHH/Mo–S/P/A cathode and conductive carbon cloth (CC) anode showed a high energy density of 0.49 mW h cm⁻² at the power density of 8.9 mW cm⁻² as well as excellent cycling stability with 95% capacity retention after 10 000 cycles. This work provides a controllable morphology reconstruction strategy for establishing high-performance Co-based supercapacitor electrode materials.