Fluorinated carbons (graphite and carbonaceous nanomaterials) are used for a long time as electrode materials in primary lithium battery. The industrial applications of such battery are rapidly growing in the areas of smart energy. These applications require the increase of their energy consumption, related to their new functionalities. The conventional technologies of primary lithium batteries (Li/SOCl2, Li/MnO2, Li/SO2Cl2, Li/SO2) will not allow to answer to those future developments. Among the considered future cathode materials, fluorinated carbons (CFx) have a number of benefits, especially weight and volume energy densities, that explain their renewed interest. Nevertheless, the development of new fluorinated materials is still necessary. C-F bonds are the electrochemical active sites during the discharge according to the irreversible reaction CFx + xLi � C + xLiF. The growth of LiF outside the carbon lattice onto the sheet edges of graphite may result in a partial exfoliation and loss of the electrical contact (i.e. loss of active material); the faradic yield and the energy density then decrease.The present work focuses on a new concept: the presence of porosity in CFx allows a better distribution of LiF particles because of their growth onto the porosity, which acts a container for LiF. Exfoliation is then avoided. Moreover, this distribution of LiF into the porosity results in a significant decrease of the electrode polarization. Finally, an increase in the discharge voltage in primary lithium battery compared to conventional fluorinated carbons in relation with the weakening of the C-F bonding. New materials were synthesized using an original route that consists in a chemical exfoliation of graphite fluoride obtained at room temperature thank to a catalytic atmosphere (F2(g)/HF(g)/IF5(g) mixture). Fast deintercalation of residual intercalated species (IF5, IF6-, IF7) results in a partial exfoliation. Those porous products are post-fluorinated and used as electrode.

Improvement of primary lithium battery working with fluorinated carbons

248th National Meeting (2014)

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