NEST · Nanowires for Energy STorage

Among today challenges that of energy needs is one of the most important. An obvious question is its production but the need of energy storage systems is almost as large. Renewable energies will not have an impact unless we find an efficient way to store the electricity that they produce. Energy should be available everywhere and at any time, this translates in a strong need for energy containers in the form of electrochemical storage. In this context, the NEST project aims to demonstrate and develop a new kind of integrated supercapacitors, electrochemical capacitors (ECs), as well as novel pseudocapacitors devices able to drastically enhance the energy storage capacity. The primary target of the project is to produce a micro-supercapacitor with integrated electrodes compatible with microelectronics process that can withstand solder reflow (280°C for few minutes). We will associate the high surface area of a new kind of silicon nanostructures, to the high thermal stability of ionic liquids used as the electrolyte. We propose to integrate Si nanowires with sub-nanostructures such as silicon branches and nano-diamond coatings. Diamond coating will bring the additional advantage to allow using protonic electrolyte while keeping a wide 2-3 V electrochemical window. In addition to the giant surface area provided by the nanotree design, even higher capacitance will be achieved by using redox-active coating such as metal oxides and electro-conducting polymers (ECPs). As a result, this combination will lead to highly reversible surface redox reaction with electrochemical double layer capacitance. These new devices well adapted to peak power demand and storage while improving energy capacity will enhance the energy efficiency and consequently will increase the competitiveness of Europe’s industries.