Porous dimanganese trioxide microflowers derived from microcoordinations for flexible solid-state asymmetric supercapacitors

Dimanganese trioxide microflowers are easily obtained from a Mn(ii) 8-hydroxyquinoline microcoordination after calcination in air. We also look into the possible formation mechanism of the flower-like morphology, and find that the reaction time affects the morphology of the coordination. Furthermore, the as-prepared porous Mn₂O₃ microflowers are made of many nanoplates which form many nanogaps and nanochannels. Interestingly, the assembled electrode based on the as-prepared porous Mn₂O₃ microflowers proves to be a high-performance electrode material for supercapacitors. The electrode shows a specific capacitance of 994 F g^-1, which can work well even after 4000 cycles at 0.75 A g^-1. More importantly, the porous Mn₂O₃ microflowers and activated carbons are assembled into a high-performance flexible solid-state asymmetric supercapacitor with a specific capacitance of 312.5 mF cm^-2. The cycle test shows that the device can offer 95.6% capacity of the initial capacitance at 2.0 mA cm^-2 after 5000 cycles with little decay. The maximum energy density of the device can achieve 6.56 mWh cm^-3 and the maximum power density can also achieve 283.5 mW cm^-3, which are among the best results for manganese based materials.