A reversible dual-graphite intercalation chemistry with simultaneous accommodation of Li⁺ and PF₆⁻ in graphitic structures is enabled for the first time by a high voltage electrolyte based on a fluorinated solvent and additive, which is capable of supporting the chemistry at 5.2 V with high efficiency. This all-graphite battery promises an energy storage device of low cost, high safety and high environmental friendliness that are critical for large scale energy harvesting/storage needs.