清洁能源化学与材料实验室知识库

Novel three-dimensional (3D) hybrid materials, i.e., free-standing 3D graphene-supported MnO₂ nanosheets, are prepared by a simple and controllable solution-phase assembly process. Characterization results show that MnO₂ nanosheets are uniformly anchored on a 3D graphene framework with strong adhesion and the integral hybrids show desirable mechanical strength. Such unique structure of 3D graphene/MnO₂ hybrids thus provides the right characteristics of binder-free electrode materials and could enable the design of different kinds of high-performance energy storage devices. Especially, an advanced asymmetric supercapacitor is built by using a 3D graphene/MnO₂ hybrid and a 3D graphene as two electrodes, and it is able to work reversibly in a full operation voltage region of 0−3.5 V in an ionic liquid electrolyte and thus exhibits a high energy density of 68.4 Wh/kg. As the cathode materials for Li−O₂ and Li−MnO₂ batteries, the 3D graphene/MnO₂ hybrids exhibit outstanding performances, including good catalytic capability, high reversible capacity and desirable cycling stability. The results presented here may pave a way for new promising applications of such 3D graphene/MnO₂ hybrids in advanced electrochemical energy storage devices.