AbstractThe effects of salts in methyl difluoroacetate (MFA)‐based electrolytes on their ionic conductivity and their thermal stability were investigated. When LiPF6 was used as a salt, an MFA‐based electrolyte showed a higher ionic conductivity than an ethylene carbonate (EC) and dimethyl carbonate (DMC)‐based electrolyte from –30 to 25 °C. In DSC curves, while an MFA‐based electrolyte containing LiPF6 gave only negligible exothermic heat up to 400 °C, a large exothermic peak due to the electrolyte decomposition was observed at about 270 °C for an EC + DMC‐based electrolyte. The thermal stability of lithium metal and de‐lithiated LiCoO2 coexisting with an electrolyte of 1 mol dm–3 LiPF6/MFA is also reported.