Basic properties and battery performances of the novel high temperature stable lithium salt (Li2B12F12, Dilithium Dodecafluorododecaborate; Li2DFB) were studied using a Mn-based cathode and anode composed of a hard carbon and graphite mixture. The effect of co-solvents (mainly linear carbonate in electrolyte formulation of PC/EC/co-solvent (5/30/65vol% mixture)) on conductivity, viscosity, charge–discharge capacities, rate performance, temperature performance, cycle life and storage life at 60°C was investigated. Conductivity of Li2DFB electrolyte increased with reducing its viscosity by changing co-solvent and increasing the volume of the higher dielectric solvent. Li2DFB electrolytes showed comparable discharge capacity and columbic efficiency against LiPF6 electrolyte. Li2DFB electrolytes improved the storage life and cycle life of a Mn-based cell at 60°C.