Li-Se battery: absence of lithium polyselenides in carbonate based electrolyte.

The lithiation mechanism of the Li-Se cell in a carbonate-based electrolyte is discussed. It is found that Se is directly reduced to Li2Se in discharge without intermediate phases detected by in situ X-ray diffraction or X-ray absorption spectroscopy. The reason is that the redox products Se and Li2Se, as well as lithium polyselenides are insoluble in the electrolyte.