text: In 1975, Peter V. Wright, a polymer chemist from Sheffield (UK), produced the first polymer electrolyte, which contained sodium and potassium salts in a polyethylene oxide (PEO) matrix. Later another type of polymer electrolytes, polyelectrolyte, was put forward, where ions moved through an electrically charged, rather than neutral, polymer matrix. Polymer electrolytes showed lower conductivities than glasses, but they were cheaper, much more flexible and could be easier machined and shaped into various forms. While ionic glasses are typically operated below, polymer conductors are typically heated above their glass transition temperatures. Consequently, both the electric field and mechanical deformation decay on a similar time scale in polymers, but not in glasses.
  Between 1983 and 2001 it was believed that the amorphous fraction is responsible for ionic conductivity, i.e., that (nearly) complete structural disorder is essential for the fast ionic transport in polymers. However, a number of crystalline polymers have been described in 2001 and later with ionic conductivity as high as 0.01 S/cm 30 °C and activation energy of only 0.24 eV.