ResearchCopyright: © Peter Winandy
Energy storage and conversion are becoming more and more important for developing our energy system towards renewable energies. On the one hand, energy storage materials contribute to decentralizing the grid and thus strengthen self-sufficient homes. Additionally, high performance energy storage systems are a key for mobile applications as well as electric vehicles. On the other hand, energy conversion enables the implementation of novel value chains which are not based on the petrochemical industry. Exemplary, excess energy of renewable energy systems can be used to use the harmful greenhouse gas CO2 as a sustainable carbon source and synthesizing fuels or other products of the chemical industry electrochemically. The ambitious goal of limiting the global warming to less than 2°C compared to pre-industrial time cannot be reached without improved energy storage materials and energy conversion technologies.
Different approaches to store and converse energy are realized. In the field of batteries we are focusing our research especially on metal-air systems and all solid state batteries. In the field of electrochemical CO2 reduction and electrocatalysis we focus on low-temperature electrolysis.
In order to create metal-air systems and all solid state batteries with high energy densities, longer lifetime, and improved cycling stability at the same time as thermal stability and safety an exact understanding of mechanisms and processes in energy materials under electrochemical load is necessary. Degradation, interfacial properties and intercalation/deintercalation occur on a molecular level and hence, high resolution microscopy is employed by advanced Scanning Probe Microscopy as our primary methodology. Advantages of electrochemical Atomic Force Microscopy are the ability to perform experiments under operando/in-situ conditions as well as recording various sample characteristics such as morphology, adhesion, Young´s modulus or electrical conductivity simultaneously and with high spatial resolution under controlled electrochemical conditions. To characterize air and moisture sensitive materials as well, our instrument is implemented into a glove box system.
We are confident that awareness of mechanisms and processes of mechanical and electrochemical nature at interfaces in energy storage materials will contribute significantly to the improvement of next generation batteries.
During the low-temperature electrolysis the rather unreactive CO2 can be electrocatalytically converted. In order to selectively and efficiently conduct the electrochemical CO2 reduction, an understanding of the electrocatalysis as a key technology is essential. For example, the catalytic activity is influenced by nanoscale interfacial phenomena such as adsorption/desorption, electron transfer, solvation/desolvation, and electrostatic interactions. These phenomena are based on the local structure of the catalyst. Due to the high spatial resolution, operando/in-situ electrochemical scanning probe microscopies can be used to analyse the influence of the local catalyst conditions such as surface orientation, distance between neighboured clusters, steps, and defects on the activity. At the same time not the entire surface of a catalyst is equally reactive and hence, the identification of active sites of catalysts is of particular importance.
We are convinced that our methodology enhances the understanding of electrocatalytic processes significantly and thus, contributes to the improvement of low-temperature electrolysis.