Rational design and synthesis of nickel-cobalt-manganese trimetallic hydroxides with micro-flower like for high-performance asymmetric supercapacitors

The construction of high energy density and porous micro-nano structure is suitable for fast electron/ion transport, which motivates us to design electrode materials with hierarchical structures. However, the synthesis route of multi-metal hydroxides is still restricted due to the complexity and high cost. Herein, we use a rational design constructing nickel-cobalt-manganese hydroxides (Ni-Co-Mn-OH) micro-flower structure by using the one-pot hydrothermal. The Ni-Co-Mn-OH is consisting of ultrathin stacking nanosheets with a three-dimensional multi-order micro-flower structure. And its internal nanoporous channels can stimulate electron/ ion transfer. Toward the application in supercapacitor, when the molar ratio of Ni and Mn is 9.69:1, the prepared electrode presented superior capacitance performance (1135 F g(-1) at 1 A g(-1)) and excellent rate performance 97% retention at 20 A g(-1)) in the three electrode system. Moreover, the asymmetric supercapacitor was also fabricated, exhibiting excellent capacitance of 115 F g(-1) at 1 A g(-1), high energy density of 54.375 Wh.kg(-1 )at a power density of 0.3758 kW kg( -1). And the maximum power density could reach 7.5 kW kg(-1) and the energy density at this time was 12.08 Wh.kg(- 1).

Automated summary

This study focuses on the rational design and synthesis of electrode materials with high energy density and porous micro-nano structure. A nickel-cobalt-manganese hydroxide micro-flower structure was successfully constructed using a one-pot hydrothermal method. The resulting material exhibited superior capacitance and rate performance, making it highly suitable for applications in supercapacitors.