Supercapacitors are playing a very relevant role in many applications due to their capability to supply high power density and long durability. However, there is a growing demand to increase their energy density, in gravimetric and volumetric basis. There are different strategies to increase supercapacitor performance by improving the active materials used in the electrodes, the type of electrolyte used or even the configuration employed in the cell. In this work, a combination of these strategies is presented with the use of different active materials, electrolytes and symmetric vs asymmetric configuration. The supercapacitor with asymmetric configuration using the graphene-doped carbon xerogel in the negative electrode and the manganese oxide in the positive electrode, along with the use of Na+-form Aquivion electrolyte membrane as solid electrolyte, seems to be a promising combination to obtain a substantial enhancement of both gravimetric and volumetric capacitance. Furthermore, the device presents great stability in a wide operational voltage window from 0 to 1.8 V and with a neutral pH polymer electrolyte which contributes to improve the performance, safety and long cycle life of the device.

We report the effect of using rutile and anatase TiO2 as precursors in the synthesis of ceramic Li1.3Al0.3Ti1.7(PO4)3 (LATP) NASICON-type electrolyte for solid-state lithium batteries. Anatase TiO2 enables LATP crystallization at lower temperatures while rutile TiO2 leads to a purer and more crystalline LATP phase. We believe these findings are an important contribution towards the development of more effective and less expensive synthesis of Ti-based solid electrolyte materials.

The goal of present work is to verify the possibility that an ionomer solution of Nafion may be efficiently used in the preparation of polymer electrolyte membranes and carbon composite electrodes for all solid double layer capacitors (DLCs). The membranes were prepared by a casting procedure starting from the Nafion solution. The electrodes were obtained spreading a carbon-Nafion ink on a carbon paper substrate by a printing method. The Nafion solution used in carbon based electrode preparation, has a double function of binding and proton conducting material. Three different electrolyte separators were investigated in capacitor configuration: a commercial Nafion 115, a Nafion membrane prepared by a recasting method and a porous glass fiber matrix impregnated with a 1 M H2SO4 solution. The membrane and electrodes assemblies (MEA) had thicknesses of 0.6-0.8 mm and active geometric area of 4 cm2. The performances of the investigated DLCs were evaluated by cyclic voltammetry (CV), DC charge-discharge (CCD) measurements and electrochemical impedance spectroscopy (EIS). Proton conductivity values of 5.7?10-2 and 3.1?10-2 S?cm-1 were obtained at room temperature with Nafion 115 and recast Nafion membrane respectively. The related value recorded with the acid impregnated porous matrix was 2?10-1 S?cm-1. A specific capacitance of 13.2 F/g was obtained by the capacitor using the Nafion recast membrane and electrodes containing carbon with a specific surface area of 1500 m-2 g-1. This value is 70% of specific capacitance obtained with the capacitor using sulfuric acid and about 140% of that of Nafion 115. Further studies are in progress in the perspective of an optimisation of polymer electrolyte membranes, electrode preparation as well as in the build up of a DLC with enhanced performance.