Electrochemical Reduction of Silver Vanadium Phosphorous Oxide, Ag(2)VO(2)PO(4): Silver Metal Deposition and Associated Increase in Electrical Conductivity.

This report details the chemical and associated electrical resistance changes of silver vanadium phosphorous oxide (Ag(2)VO(2)PO(4), SVPO) incurred during electrochemical reduction in a lithium based electrochemical cell over the range of 0 to 4 electrons per formula unit. Specifically the cathode electrical conductivities and associated cell DC resistance and cell AC impedance values vary with the level of reduction, due the changes of the SVPO cathode. Initially, Ag(+) is reduced to Ag(0) (2 electrons per formula unit, or 50% of the calculated theoretical value of 4 electrons per formula unit), accompanied by significant decreases in the cathode electrical resistance, consistent with the formation of an electrically conductive silver metal matrix within the SVPO cathode.

Electrochemical reduction of silver vanadium phosphorous oxide, Ag(2)VO(2)PO(4): the formation of electrically conductive metallic silver nanoparticles.

As a cathode material, silver vanadium phosphorous oxide (Ag(2)VO(2)PO(4)) displays several notable electrochemical properties: large capacity, high current capability, and an effective delivery of high current pulses. These cell performance characteristics can be attributed to the presence of silver nanoparticles formed in-situ during the electrochemical reduction of Ag(2)VO(2)PO(4). Specifically, changes in the composition and structure of Ag(2)VO(2)PO(4) with reduction, especially the formation of silver nanoparticles, are detailed to rationalize a 15,000 fold increase in conductivity with initial discharge, which can be related to the power characteristics associated with Ag(2)VO(2)PO(4) cathodes in primary lithium batteries.