Formation of an Electroactive Polymer Gel Film upon Lithiation and Delithiation of PbSe

Because lead telluride (PbTe) was found to rapidly and reversibly lithiate to form Li+-conductive Li2Te and a series of Li-Pb alloys, we explored the reversibility and rate of lithiation of PbSe. As expected, PbSe was also reversibly lithiated to Li2Se and Li-Pb alloys, but the electrode was less stable and could not be cycled as rapidly. When the electrode was cycled at a slow rate, an electroactive polymer gel film derived of the 1 M LiPF6 in 1:1 fluoroethylene carbonate/ diethyl carbonate (w/w) electrolyte built up in the initial 25 cycles. Electroreduction and electrooxidation of this film added to the capacity by as much as 300 mAh g(-1) above its theoretical value. (C) 2016 The Electrochemical Society. All rights reserved.