Nuclear magnetic resonance (NMR) is a technique that allows the probing of the dynamics of specific magnetically active nuclei. In the present study a polyethylene glycol network containing varying concentrations of LiClO4 have been studied using Li-7 NMR relaxation techniques. A plasticiser, tetraglyme, has been added to several samples to improve the mobility of the polymer and thus of the ionic species. The effects of tetraglyme and salt concentration on the cationic mobility and environment have been investigated using T-1 and T-2 relaxation experiments, with the presence of two cationic species of differing relaxation times (and possibly mobility) reported. The results are discussed with relevance to conductivity measurements made on similar samples.