Berlin 2015 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 6: Functional Materials I: Battery Materials

MM 6.3: Talk

Monday, March 16, 2015, 10:45–11:00, TC 010

Self-forming Lithium Ion Batteries: Optimization of Ag-LiPON Devices — •Leila Raafat, Susann Nowak, and Guido Schmitz — Chair of Materials Physics, University of Stuttgart

Sandwiching the solid electrolyte lithium phosphorous oxynitride (LiPON) between two current collectors leads to a thin-film battery after initial charging (Liu et al., J. Electrochem. Soc. 155 (1), A8 (2008)). These electrochemically formed batteries are of particular interest, since the Li anode is internally electroplated without concern of its contamination. Three different devices of this design with a thickness of ca. 1μm were electrochemically investigated. We discovered that employing an inert anode current collector towards LiPON like copper (Cu), will lead to Cu/LiPON/Ag-devices which can withstand over 500 cycles showing a stable discharge capacity. Since dendrite formation at the interfaces of such a device is inevitable, short circuits can occur. Extending a concept reported by Yourey et al. (Electrochim. Acta 66, 193 (2012)), the formation of short circuits can be prevented by using a Li oxide based solid electrolyte interphase between the Li anode and LiPON. Therefore, we modified the devices by depositing a thin layer of lithium phosphate on the Cu current collector. This adjustment resulted in a significantly increased success rate and an improved cycle life; over 2000 cycles were measured. In order to understand the reactions happening within these batteries, the kinetics of the reaction layer are investigated depending on the cycle number.