Self-standing star-shaped tri-metallic oxides for pseudocapacitive energy storage electrode materials.

• Trimetallic oxides (CuMnCoO 4) was synthesized by hydrothermal method. • CuMnCoO 4 exhibits a high specific capacitance of 1715F g−1 at 1 A g−1). • Distinct morphology and combined synergistic effect are responsible for outstanding results. • The AS shows high power and energy density and long-term cycling life. Novel star-shaped trimetallic oxides (CuMnCoO 4) have been synthesized employing hydrothermal method and favorably compared to the Co 3 O 4 and bimetallic (MnCo 2 O 4) oxides. The star-shaped CuMnCoO 4 consisted of bundles of orderly layered and loosely interconnected nanoneedles with a hole in the center; each nanoneedle was composed of single-crystalline nanoparticles. Its distinctive structural features significantly increased the electrochemically active sites and facilitated the mass and charge transports. Furthermore, the three transition metal cations in the trimetallic oxide contributed to the multiple redox reactions. Consequently, CuMnCoO 4 exhibited a significantly enhanced capacitance (1,715F g−1 at 1 A g−1) and outstanding cycling stability, compared to those of Co 3 O 4 (742F g−1) and MnCo 2 O 4 (1,305F g−1). Additionally, an asymmetric supercapacitor (AS) (assembled with CuMnCoO 4 , as the positive electrode, and activated carbon (AC), as the negative electrode) exhibited a high energy density (E) of 40.1 W h kg−1, at a power density (P) of 799 W kg−1, thereby highlighting CuMnCoO 4 as a promising candidate for energy storage. This research can also pave the way for the study of new spinel-trimetallic compounds with EES applications. [ABSTRACT FROM AUTHOR]