Urchin-like Ce(HCOO)₃ Synthesized by a Microwave-Assisted Method and Its Application in an Asymmetric Supercapacitor

In this work, a series of urchin-like Ce(HCOO)₃ nanoclusters were synthesized via a facile and scalable microwave-assisted method by varying the irradiation time, and the structure-property relationship was investigated. The optimization of the reaction time was performed based on structural characterizations and electrochemical performances, and the Ce(HCOO)₃-210 s sample shows a specific capacitance as high as 132 F g^-1 at a current density of 1 A g^-1. This is due to the optimal mesoporous hierarchical structure and crystallinity that are beneficial to its conductivity, offering abundant Ce³⁺/Ce⁴⁺ active sites and facilitating the transportation of electrolyte ions. Moreover, an asymmetric supercapacitor based on Ce(HCOO)₃//AC was fabricated, which delivers a maximum energy density of 14.78 Wh kg^-1 and a considerably high power density of 15,168 W kg^-1. After 10,000 continuous charge-discharge cycles at 3 A g^-1, the ASC device retains 81.3% of its initial specific capacitance. The excellent comprehensive electrochemical performance of this urchin-like Ce(HCOO)₃ offers significant promise for practical supercapacitor applications.