Ag4V2O6F2 (SVOF): a high silver density phase and potential new cathode material for implantable cardioverter defibrillators.
The electrochemical reactivity of the cathode material Ag 4V 2O 6F 2 (SVOF) versus lithium, with a particular emphasis on the lithium insertion mechanism, was studied by means of the complementary techniques in situ X-ray diffraction, electron paramagnetic resonance, and high-resolution transmisssion electron microscopy. This study confirms the initial reports of a high capacity for SVOF of 148 mAh/g above 3 V and that the reduction of silver above 3 V (vs Li (+)/Li (0)) leads to a loss of SVOF crystallinity until it becomes completely amorphous between the third and fourth lithiums inserted. Next, vanadium is reduced between 2.5 and 1.5 V (vs Li (+)/Li (0)) for the fifth and sixth lithiums inserted. In addition, the polarization within the cathode is significantly lower for the vanadium reduction than for the silver reduction. The silver metal morphologies consisted of nanoparticles ( approximately 5 nm diameter) and dendrites and were both seen in samples of lithiated SVOF.
Sauvage
Frédéric
F
Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA.
Bodenez
Vincent
V
Vezin
Hervé
H
Albrecht
Thomas A
TA
Tarascon
Jean-Marie
JM
Poeppelmeier
Kenneth R
KR
D017147:Defibrillators, Implantable; D004563:Electrochemistry; D004578:Electron Spin Resonance Spectroscopy; D008094:Lithium / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D012834:Silver / Q000737:chemistry*; D018030:Silver Compounds / Q000737:chemistry*; D017968:Vanadium Compounds / Q000737:chemistry*; D014961:X-Ray Diffraction
D018030:Silver Compounds; D017968:Vanadium Compounds; D012834:Silver; D008094:Lithium