Fluorine compounds are quite useful as energy conversion materials, in particular as primary and secondary lithium battery materials. Primary lithium battery with graphite fluoride cathode was commercialized in 1973, based on the research on graphite fluoride. Since then, it has been shown that fluorine compounds are useful and attractive materials for lithium batteries. The present account paper reports the historical aspects and update topics on fluorine compounds such as graphite fluorides, fluorine–graphite intercalation compounds and organo-fluorine compounds as energy conversion materials. Surface modification by fluorine is also reported.