Advanced energy storage performance based on a hairly hydrangea-like Co3-Mn O4 with high absorption capacity

Structural design and regulation of absorption capacity play important roles for improving energy storage performance of bimetallic oxides in supercapacitors (SCs). Herein, three-dimensional Co 3 -x Mn x O 4 (0< x <3) with different Co/Mn molar ratios are synthesized by hydrothermal method. Scanning electron microscopy (SEM) demonstrates the changes of the morphology of Co 3 -x Mn x O 4 (0< x <3) with different Co/Mn molar ratios, in which the Co 3 -x Mn x O 4 ( x =1.09) exhibits a hairly hydrangea-like morphology and thus provides a reduced contact resistance and an effective ion transition ability proved by the electrochemical measurements. Meanwhile, by theoretical calculations we prove that the addition of Mn adequately improves the absorption capacity of OH − on Co 3 -x Mn x O 4 and thereby boosts the reaction activity. Therefore, when the Co 3 -x Mn x O 4 ( x =1.09) is used as a SCs electrode, it performs a high specific capacitance of 326 F g -1 at a current density of 1 A g -1 . Moreover, an assembled asymmetric supercapacitor (Co 3 -x Mn x O 4 ( x =1.09)@NF//AC@NF) demonstrates enhanced performances, such as an energy density of 17.77 Wh Kg -1 at a power density of 400 W Kg -1 , an outstanding cycling stability with 83.3% retention over 10000 cycles at a current density of 2 A g -1 and so on. Related studies indicate the potential applications of Co 3 -x Mn x O 4 in the future smart micro/nano energy storage devices. • A hairly hydrangea-like Co 3-x Mn x O 4 (x=1.09) was synthesized successfully. • Theoretical calculations proved that the addition of Mn adequately improves the absorption capacity of OH − on Co 3-x Mn x O 4 . • Specific capacitance of 326 F g -1 was performed at a current density of 1 A g -1 . • Energy density of 24.60 Wh Kg -1 was reached at a power density of 276.72 W Kg -1 . • 83.3% of specific capacitance was retained after 10000 cycles at a current density of 2 A g -1 .