An electrolyte can be pretreated by contacting with an oxide species (e.g., SiO2, SiOx, where 1≤x≤2, TiO2). The electrolyte comprises LiPF6 and a carbonate solvent. A reaction occurs to form a pretreated electrolyte comprising a compound selected from the group consisting of: MaPx′OyFz, MaPx′OyFzCnHm, and combinations thereof, where when P in the formula is normalized to 1 so that x′ is equal to about 1, 0