AbstractWe report 7Li spin lattice relaxation times at 12.82 MHz over a range of temperatures for liquid electrolytes of various salt:polymer ratios, and compare the NMR correlation time obtained at the temperature of the T1 minimum with the conductivity relaxation time at the same temperature. We find that at low salt contents the two relaxation times have the same value, but beyond the “salt-inpolymer to polymer-in-salt transition” zone at the Tg maximum, the two times increasingly separate. This is taken as evidence for the onset of cation-matrix mobility decoupling, which maximizes at the pure salt extreme.