Reversibility without over-potential of fluorinated graphite in lithium batteries

Abstract

When used as positive electrode in lithium batteries, fl uorinated carbons deliver capacities and energy densities that exceed those of other commercial primary batteries. In addition, these materials can be used over a wide range of temperatures, allowing them to diversify their utilization and have a lifespan of 15 years. However, when using the fluorinated carbon-based battery, a very stable compound, lithium fluoride, is formed and prevents the reversibility of the process, i.e. the use in secondary battery. Systems with a fluorinated carbon cathode are then called primary battery, non-rechargeable systems. In the present work, graphite fluorides with weakened covalency for the C–F bonds are considered as cathode in secondary lithium battery with polymer electrolyte. Such a combination of non-conventional graphite fluoride and polymer electrolyte allows the reversibility to be achieved without significant polarization contrary to the previous works in the literature. Non optimized reversible capacity of 65 mAh/g without high over-potential between the reduction and oxidation processes is achieved.