title: Silver Vanadium Diphosphate Ag2VP2O8: Electrochemistry and Characterization of Reduced Material providing Mechanistic Insights.
abstract: Silver vanadium phosphorous oxides (AgwVxPyOz) are notable battery cathode materials due to their high energy density and demonstrated ability to form in-situ Ag metal nanostructured electrically conductive networks within the cathode. While analogous silver vanadium diphosphate materials have been prepared, electrochemical evaluations of these diphosphate based materials have been limited. We report here the first electrochemical study of a silver vanadium diphosphate, Ag2VP2O8, where the structural differences associated with phosphorous oxides versus diphosphates profoundly affect the associated electrochemistry. Reminiscent of Ag2VO2PO4reduction,in-situformation of silver metal nanoparticles was observed with reduction of Ag2VP2O8. However, counter to Ag2VO2PO4reduction, Ag2VP2O8demonstrates a significant decrease in conductivity upon continued electrochemical reduction. Structural analysis contrasting the crystallography of the parent Ag2VP2O8with that of the proposed Li2VP2O8reduction product is employed to gain insight into the observed electrochemical reduction behavior, where the structural rigidity associated with the diphosphate anion may be associated with the observed particle fracturing upon deep electrochemical reduction. Further, the diphosphate anion structure may be associated with the high thermal stability of the partially reduced Ag2VP2O8materials, which bodes well for enhanced safety of batteries incorporating this material.
authors: Department Materials Science and Engineering, Stony Brook University (SUNY), Stony Brook, NY 11794 ; Global and Regional Solutions Directorate, Brookhaven National Laboratory, Upton, NY 11973 ; Department of Chemistry, Stony Brook University (SUNY), Stony Brook, NY 11794.
authors: Esther S
authors: ES
authors: Takeuchi
authors: Department of Chemical and Biological Engineering, University at Buffalo (SUNY), Buffalo, NY 14260.
authors: Chia-Ying
authors: CY
authors: Lee
authors: Department of Chemical and Biological Engineering, University at Buffalo (SUNY), Buffalo, NY 14260.
authors: Po-Jen
authors: PJ
authors: Chen
authors: Department Materials Science and Engineering, Stony Brook University (SUNY), Stony Brook, NY 11794.
authors: Melissa C
authors: MC
authors: Menard
authors: Department Materials Science and Engineering, Stony Brook University (SUNY), Stony Brook, NY 11794 ; Department of Chemistry, Stony Brook University (SUNY), Stony Brook, NY 11794.
authors: Amy C
authors: AC
authors: Marschilok
authors: Department of Chemistry, Stony Brook University (SUNY), Stony Brook, NY 11794.
authors: Kenneth J
authors: KJ
authors: Takeuchi
keywords: cathode; electrochemical reduction; implantable medical device; lithium battery; primary battery; silver vanadium diphosphate