Deciphering the Evolution of Current Distribution in Hybrid Silver Vanadium Oxide / Carbon Monofluoride Cathodes within Lithium Primary Batteries.

For batteries to function effectively all active material must be accessible requiring both electron and ion transport to each particle. A common approach to generating the needed conductive network is the addition of carbon. An alternative approach is the electrochemically induced formation of conductive reaction products generated with intimate contact to the active material. This study probes silver vanadium oxide (Ag2V4O11, SVO), carbon monofluoride (CFx), and hybrid SVO/CFx electrodes in lithium batteries. Ex situ XRD identifies Ag0 as a reduction product from SVO and LiF from CFx that can be followed as a function of depth-of-discharge (DOD). Spatially-resolved operando energy dispersive x-ray diffraction reveals that presence of SVO alleviates reaction heterogeneity in the electrodes which are electron transfer limited in the absence of sufficient Ag0. Synchrotron X-ray tomography reveals silver particles to be more closely spaced near the current collector indicating multiple nucleation sites for their formation. Finally, enthalpy potentials, determined via operando isothermal microcalorimetry describe the current distribution adding further insight to the discharge process of the two active materials. Taken together, these results provide a comprehensive understanding of hybrid SVO/CFx cathodes and give guidance on optimal compositions that balance power and energy density considerations.