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Abstract: Mesoporous carbons are prepared from a mixture of the soluble starch with needle-like nano-sized Mg(OH)2 particles. The samples structures are characterized by TEM, nitrogen adsorption at 77K and XRD. The electrochemical performance for electrochemical capacitors is evaluated in a 6M KOH aqueous solution. The resultant carbons show a disordered pore structure with interweaving straight nano-tunnels that resembled the shape of the template, and possess a high surface area more than 1000m2 g−1 and a large pore volume. The special one dimensional morphology of templates cause a graphitization effect on the carbon in partial region, different from catalytic graphitization mechanism of transition metal particles. Due to those characteristics, the samples exhibit good electrochemical performances used for electrochemical capacitors electrode, especially excellent power capability. The sample carbonized at 950°C for 6h retain a capacitance of 126Fg−1 even at a high current density of 40Ag−1. [Copyright &y& Elsevier]

Abstract: This paper introduces a silicon three-dimensional (3D) micro supercapacitor, featured by using self-supporting nano porous composite materials and interdigital electrodes with high-aspect-ratio. A way to prepare self-supporting materials has been developed, and composites that contain an activated carbon as the active component have been studied and designed to meet the requirements for adequate specific capacitance, good conductivity and strong structure. By combining the designed composite with microfabrication techniques, a micro supercapacitor with high-aspect-ratio interdigital electrodes has been achieved. Electrochemical characterization results of the prototype with NaNO3 electrolyte demonstrate that the 3D supercapacitor exhibits an outstanding overall performance. A large capacitance of 90.7mFcm−2 and a fast power of 51.5mWcm−2 are calculated. Robust stability and high charge/discharge efficiency are also observed. Moreover, this study provides a scalable device built by compatible fabrication method, which is applicable to the integration of high-performance supercapacitors on chip. [Copyright &y& Elsevier]

Abstract: This paper demonstrates an asymmetric micro supercapacitor with superior overall performance that combines the advantages of both MnO2 positive electrode and carbon negative electrode for energy storage on a chip. Nano-structured MnO2 with rough surface is synthesized as active material for micro electrode. A self-supporting composite containing MnO2 and another containing nanoporous activated carbon (AC) are separated in an interdigital structure by using micro-electro-mechanical systems (MEMS) fabrication technologies. Measurements of the prototype show that the asymmetric micro supercapacitor has well-performed capacitive behavior, and its working voltage range is extended from 1 V to 1.5 V in aqueous electrolyte due to the MnO2–AC configuration. Calculations prove that it stores much higher energy densities than symmetric ones using either MnO2 or AC. Moreover, this work provides an attractive approach to achieve various asymmetric micro energy storage systems on chips. [Copyright &y& Elsevier]