Organic Dinitrates: Electrolyte Additives That Increase the Energy Densities of Lithium/Graphite Fluoride Batteries

Li/graphite fluoride (Li/CF<i>_x</i>) batteries display the highest energy densities among those of commercially available primary Li batteries but fail to satisfy the high-performance requirements of advanced applications. To address this drawback, two liquid organic dinitrates, namely, 1,4-butanediol dinitrate (BDE) and 2,2,3,3-tetrafluoro-1,4-butanediol dinitrate (TBD), were employed as high-energy energetic materials, and they were highly compatible with the electrolytes of Li/CF<i>_x</i> batteries. The use of Super P electrodes confirmed that the reduction reaction mechanisms of both nitrate ester-based compounds delivered considerable specific capacities, associated with discharge potentials matching that of the Li/CF<i>_x</i> battery. When considering the combined mass of the electrolyte and cathode as the active material, the overall energy densities of the Li/CF<i>_x</i> batteries increased by 25.3% (TBD) and 20.8% (BDE), reaching 1005.50 and 969.1 Wh/kg, respectively. The superior performance of TBD was due to the synergistic effects of the high electronegativities and levels of steric hindrance of the F atoms. Moreover, the nanocrystal LiF particles generated by TBD induced crack formation within the fluorinated graphite, increasing the lithium-ion accessible surface area and enhancing its utilization efficiency. These combined factors enhanced the reactivity of TBD and facilitated its involvement in electrochemical reactions, thus improving the capacity of the battery. The developed strategy enables the facile, cost-effective enhancement of the capacities of Li/CF<i>_x</i> batteries, paving the way for their practical use in energy-demanding devices.