Thermal stability of lithium-ion battery electrolytes

The thermal decomposition of LiPF 6 in the solid state and as solutions in dialkylcarbonates has been investigated. The thermal decomposition of LiPF 6 was investigated with differential scanning calorimatry (DSC) suggesting decomposition to LiF and PF 5. In solution, PF 5 reacts with dialkylcarbonates to form a variety of decomposition products including carbon dioxide (CO 2), ethers (R 2O), alkylfluorides (RF), phosphorus oxyfluoride (OPF 3), and fluorophosphates (OPF 2OR, OPF(OR) 2). The structure of the decomposition products are supported by nuclear magnetic resonance (NMR) spectroscopy and gas chromatography with mass selective detection (GC–MS).