In some designs, it may be advantageous to have a total salt concentration in the electrolyte in the range from around 0.8M to around 2.0M (preferably, in the range from around 1.0M to around 1.8M), while utilizing a mixture of two or more salts. It may be further advantageous in some designs for at least one of the salts to comprise LiPF₆. In some designs, a non-LiPF₆ salt may be LiFSI salt. Furthermore, in the case of the electrolyte comprising both LiPF₆ salt and LiFSI salt, the ratio of the molar fractions of LiPF₆ and LiFSI salts may preferably be in the range from around 20:1 to around 2:1. The exact optimal ratio for particular applications may depend on the electrode characteristics (e.g., thickness, amount of binder, density, anode and cathode composition and capacity, etc.), electrolyte solvent mix utilized and/or cycling regime (e.g., temperature, cell voltage range, etc.). It may further be advantageous in certain applications for the electrolyte solvent to comprise a mixture of LMP and RMP solvents and (optionally) ADD solvents. In some designs, it may also be advantageous for the LMP solvent or solvent mix to comprise ester(s).