WO(2)/LiCoO(2) and MoO(2)/LiCoO(2) electrochemical cells.

Electrochemical cells with transition metal oxide electrodes (molybdenum dioxide or tungsten dioxide negatives and lithium cobalt oxide positives) are being studied for use as ionic capacitors or low capacity rechargeable battery cells. Electrochemical and thermodynamic properties of these materials in non-aqueous electrolytic solutions were individually studied relative to lithium by galvanostatic cycling and microcalorimetric measurements. The negative electrode materials (molybdenum dioxide and tungsten dioxide) can reversibly intercalate up to 1/2 lithium per mole at average voltage of 1.5V and 0.9V versus a lithium reference, respectively. Lithium cobalt oxide showed reversibility over a wider composition range of lithium deintercalation at an average voltage of 4.2V with respect to a lithium reference. Early results on intercalation capacitors made without metallic lithium show high operating voltages (2.6V and 3.3V), and good cycling characteristics.