Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Extending the potential window towards the 3V plateau below the typically used range could boost the effective capacity of LiMn2O4 spinel cathodes. . This usually leads to an “overdischarge” of the cathode, which can cause severe material damage due to manganese dissolution into the electrolyte and a critical volume expansion (induced by Jahn-Teller distortions). As those factors determine the stability and cycling lifetime for all-solid-state batteries, the operational window of LiMn2O4 is usually limited to 3.5 – 4.5 V vs. Li/Li+ in common battery cells. However, it has been reported that nano-shaped particles and thin films can potentially mitigate these detrimental effects. We report here that porous LiMn2O4 thin film cathodes with a certain level in off-stoichiometry show improved cycling stability for the extended cycling range of 2.0 – 4.5 V vs. Li/Li+. We argue through operando Spectroscopic Ellipsometry that the origin of this stability lies in the surprisingly small volume change in the layer during lithiation.