New method enables a view inside batteries

The Solid Electrolyte Interphase (SEI) inside both lithium-ion and lithium metal batteries is indispensable for successful battery cell operation and at the same time an analytical challenge. Up to now, its analysis has only been possible to a limited extent; knowledge about formation, composition, growth or reactions is incomplete. The MEET scientists Dr Peter Bieker, Jan Frederik Dohmann and Martin Winter, in close cooperation with Bastian Krueger, Luis Balboa and Gunther Wittstock from the Institute of Chemistry of the Carl von Ossietzky University Oldenburg, developed a novel battery cell design combined with an in-situ analysis methodology. This enables a comprehensive analysis of the interphase film under realistic conditions and significantly expands the method portfolio of battery cell analysis. Solid electrolyte interphase influences battery performance. The very-thin SEI layer forms between the anode (negative electrode) and electrolyte during charging and discharging and functions like a kind of sieve: it conducts well ions, but prevent transport of electrons and thus a continuous detrimental reaction of the negative electrode with the electrolyte components. It thus has a major influence on performance and safety of a battery and offers corresponding optimisation approaches for research.