Performance of polyphosphazene based gel polymer electrolytes in combination with lithium metal anodes

This work presents a detailed study of the electrochemical performance of a polyphosphazene based gel polymer electrolyte in a lithium metal polymer cell. The polyphosphazene MEEP was chosen because of its favorable properties, such as good thermal and electrochemical stability versus lithium metal. In combination with a liquid electrolyte, consisting of 0.7 mol L-1 LiBOB in EC/DMC, a high ionic conductivity of similar to 9.10(-4) S cm(-1) at 30 degrees C was achieved. The electrochemical stability window ranges between 0 V and 4.4 V vs. Li/Li+ reference electrode. The gel polymer was drop coated onto the electrode materials and cross-linked to achieve high mechanical stability. The gel polymer showed a very good interface stability at lithium metal electrodes in the prepared full cells, where a stable SEI was formed during initial contact. The full cell tests delivered a stable cycling behavior with more than 1300 cycles and capacities higher than 110 inAh g(-1) at high discharge rates of 2C(D) without any indication for short circuits caused by lithium dendrites. (C) 2014 Elsevier B.V. All rights reserved.