Ion–polyether coordination complexes: crystalline ionic conductors for clean energy storage

Ion-polyether complexes are the solid state analogues of crown ether and cryptand complexes. They represent a fascinating class of coordination compounds in their own right, with the ability to support ionic conductivity and the potential to be used as electrolytes in all-solid-state rechargeable lithium batteries. Here the recent discovery of ionic conductivity in crystalline ion-polyether complexes, when for 30 years such materials were considered to be insulators, is described, along with their closely related structural chemistry.