Electrochemical energy storage in Mn2O3 porous nanobars derived from morphology-conserved transformation of benzenetricarboxylate-bridged metal-organic framework

Tailoring the morphology of mesoporous nanostructures toward performance enhancement plays a key role in developing efficient energy storage devices. Herein, we report the formation of well crystallized Mn2O3 mesoporous nanobars through simple exo-templating of a manganese 1,3,5-benzenetricarboxylate metal-organic framework (Mn-BTC MOF) by thermal treatment whereby the general morphology of the parent MOF is conserved, but with more voids and spaces. The parent Mn-BTC MOF was synthesized by solvothermal reaction of trimesic acid with manganese nitrate in alcoholic solution. The MOF-derived Mn2O3 was characterized by XRD, field-emission SEM, high-resolution TEM, and N-2 adsorption/desorption isotherm measurements. When examined as an anode material for lithium-ion batteries in the potential windows of 0.01-3.0 V and 0.01-2.0 V, high reversible specific capacities of 849 and 778 mAh g(-1) were obtained. It was found that the electrochemical processes are more reversible when cycled in the 2 V window. A steady capacity of similar to 410 mAh g(-1) was observed after 300 continuous cycles at similar to C/5.5 exhibiting good cycling stability in the 2 V window. When tested as a pseudocapacitor electrode in a three-electrode configuration, a specific capacitance of 250 F g(-1) at 0.2 A g(-1) could be achieved. Further, to demonstrate practical applicability, two-electrode asymmetric supercapacitor pouch cells were assembled with Mn2O3 as the positive electrode and commercial activated carbon as the negative electrode which showed an ultrahigh energy density of 147.4 W h kg(-1) at a power density of 1004 W kg(-1). The present work shows the potential of a MOF derived route for obtaining metal oxides with desired nano-architectures for electrochemical applications with high performance.