Deciphering cell chemistry of carbon fluoride cathode through borane-type electrolyte additive

Lithium carbon fluoride (Li°∥CF x ) batteries are the research hotspot amid the existing primary battery technologies, owing to their inherent safety and exceptionally theoretical energy density. From the perspective of bimolecular nucleophilic substitution (S N 2) reactions for the conversion process of CF x electrode, we herein delve into the impact of borane-type Lewis acid additive, as lithium fluoride (LiF) carrier, on their discharge behavior of the Li°∥CF x cells, utilizing two families of electrolytes with different electron-donicity, namely 1,2-dimethoxyethane (DME) and propylene carbonate (PC). The results show that the DME-based electrolytes empower the Li°∥CF x cells with higher specific capacities vs. the corresponding PC-based systems, irrespective of the borane-type Lewis acid additive concentration. This highlights the central impact of electrolyte solvents ( i.e. , donicity) on determining the discharge processes of CF x electrodes. Furthermore, for the DME-based electrolytes, the addition of a few percent (0.4 wt%) of borane-type additive leads to a significant improvement in the discharge capacity, demonstrating the necessity of carrying deposited LiF particles for the electrolytes with relatively high donicity. This work provides an explicit design concept concerning the optimization of the electrolyte configurations for further improving the electrochemical performance of Li°∥CF x and related battery systems.