Investigation on the Thermal Stability of Li₂MnSiO₄‐Based Cathodes for Li‐ion Batteries: Effect of Electrolyte and State of Charge

Abstract

Abstract The thermal stability of cathode materials and their compatibility with liquid electrolytes are crucial for designing safe Li‐ion batteries. Recently, Li 2 MnSiO 4 has been investigated as potential low‐cost high‐capacity cathode material. Although intrinsic safety is expected for Li 2 MnSiO 4 , a systematic investigation on the safety of this cathode material has not been reported so far. In this study, we report the thermal behavior of Li 2 MnSiO 4 ‐based electrodes studied by differential scanning calorimetry coupled with thermogravimetry (DSC–TG). The results show that the use of the standard LiPF 6 ‐based electrolyte leads to exothermic reactions with the electrochemically cycled electrodes and that only pristine cathodes before cycling show the expected thermal stability. The changes in oxidation state of Mn, Si, and C during cycling are studied by X‐ray photoelectron spectroscopy. We demonstrate that the electrolyte system controls the thermal behavior of Li 2 MnSiO 4 cathodes and that, unlike most common cathode materials, the discharged electrodes are less stable than those in the charged state in a fluorine‐based electrolyte.