Tin dioxide (SnO2) containing electrodes showed significantly lower radical induced polymer degradation under single cell open circuit voltage (OCV) treatment than SnO2 free electrodes. A backbone related segment was detected under 100% RH, and an oxygen containing side chain segment was detected under 6% RH by F-19 NMR. Fluoride ion release was observed in both cases. Low humidity induces greater damage to the polymer under OCV. (C) 2014 Elsevier B.V. All rights reserved.