Preparation of mulberry‐like RuO 2 electrode material for supercapacitors

As a newly emerging excellent energy storage device, supercapacitors have been widely studied due to their unique advantages. Electrode material is one of the key components that determine the performance of a supercapacitor. Among the various electrode materials of supercapacitors, RuO 2 has attracted great attention in the scientific community due to its high theoretical energy storage capability and excellent stability. However, most RuO 2 materials suffer the problem of low specific surface area, causing a much lower actual capacitance value compared to the theoretical performance of the material. In this work, a mulberry‐like RuO 2 electrode material with large specific surface area (159.4 m 2 ·g −1 ) was successfully synthesized by a facial hydrothermal method. The electrochemical characterization has shown that the RuO 2 possesses a high specific capacitance of 400 F·g −1 at a current density of 0.2 A·g −1 and good capacitance retention rate of 84.7% after 6000 charge/discharge cycles under a current density of 10 A·g −1 . The energy densities and power densities of the RuO 2 ‐AC supercapacitor vary from 25.0 to 11.7 Wh·kg −1 and 160 to 10,560 W·kg −1 at current density ranging from 0.2 to 10.0 A·g −1 , respectively.