Ag_3.2VP_1.5O_7.8: A high voltage silver vanadium phosphate cathode material

Herein we report the first study of the electrochemical reduction of a high Ag/V ratio silver vanadium phosphorous oxide, Ag_3.2VP _1.5O_7.8. Based on XRD, magnetic susceptibility, AC impedance and conductivity data, a three step mechanism is proposed. The initial reduction by 2.0 electron equivalents is consistent with the reduction of Ag⁺ to Ag⁰ accompanied by a 9 order of magnitude increase in conductivity and decrease in AC impedance. From 2.0 to 3.0 electron equivalents, the reduction of vanadium begins in parallel with Ag⁺ to Ag⁰ reduction. Continuation of reduction past 3.0 electron equivalents leads to further reduction of the vanadium center. Lithium cells based on Ag_3.2VP_1.5O_7.8 cathodes showed promising performance attributes including significant delivered capacity above 3.0 V and good performance under pulse conditions.