A non-aqueous electrolyte solution for lithium or a lithium ion cell, which improves lithium ion cell capacity retention and enhances storage life thereof. The non-aqueous solution can be implemented in the context of an electrolyte system that includes a lithium salt dissolved in a solvent formed from a mixture of one or more cyclic esters, and/or one or more chain esters, and at least one lactam based solvent. Such a system is suited for use with electrochemical energy storage devices, which are based on non-aqueous electrolytes, such as high energy density batteries and/or high power electrochemical capacitors. Such an electrochemical storage devices is generally based on non-aqueous electrolytes that include lithium salt dissolved in a solvent system.