Sodium-Ion Storage in Carbon Nanomaterials / Sino-German Center Part

The search for efficient, reliable and low-cost electrochemical energy stores is an on-going and societally highly relevant task. As lithium-ion battery (LIB) technology more and more approaches its intrinsic limits, a range of alternatives is currently being studied. This also includes sodium-ion batteries (NIBs) that are largely motivated by the abundance of sodium. Even without sodium’s abundance, there is a clear and general need to develop potential alternatives to conventional LIB technology as a massive increase in materials supply is expected once electrification of transport and stationary energy storage enter the mass market. Using carbon materials in NIBs is therefore a straightforward approach to render batteries based on abundant elements. The use of carbon materials in NIBs is, however, poorly understood and so far does not meet all relevant criteria for application (capacity, kinetics, coulombic efficiency, redox potential). Overall, there is a clear need for more fundamental understanding of storing sodium-ions in carbon structure. Here, the project aims at making some important contributions. Carbon materials with tailored structure and chemical composition will be synthesized and their ion storage behavior in sodium (and lithium) cells will be evaluated with the aim to provide insights into the complex storage phenomena as well as the underlying physical-chemical principles. As a main content of the project, the influence of surface chemistry, morphology and hetero atom doping on the kinetics and thermodynamics of the charge storage mechanism as well as on the surface film formation (solid electrolyte interphase, SEI) will be studied. This way, we aim at overcoming current limitations for carbon materials for sodium-ion batteries and will also be able to judge on whether carbon nanomaterials remain model systems or can really contribute to the development of practical NIBs.