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.

A synthetic strategy for magnetite ͑Fe 3 O 4 ͒ crystallite size control is reported, along with the detailed characterization and electrochemical measurements of Fe 3 O 4 samples of varying crystallite sizes. Nanocrystalline Fe 3 O 4 is prepared by coprecipitation induced by triethylamine from aqueous iron͑II͒ and iron͑III͒ chloride solutions of varying concentrations. Variation of the iron͑II͒ and iron͑III͒ concentrations results in crystallite size control of the Fe 3 O 4 products. Materials characterization of the Fe 3 O 4 samples is reported, including X-ray diffraction, transmission electron microscopy, particle size, and saturation magnetization results. A strong correlation between discharge capacity and voltage recovery behavior vs magnetite crystallite size was observed when tested as an electrode material in lithium electrochemical cells.

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This report details the chemical and associated electrical resistance changes of silver vanadium phosphorous oxide (Ag2VO2PO4, 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 Ag0 (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. As Ag+ reduction progresses, V5+ reduction initiates; once the SVPO reduction process progresses to where the reduction of V5+ to V4+ is the dominant process, both the cell and cathode electrical resistances then begin to increase. If the discharge then continues to where the dominant cathode reduction process is the reduction of V4+ to V3+, the cathode and cell electrical resistances then begin to decrease. The complex cathode electrical resistance pattern exhibited during full cell discharge is an important subject of this study.

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