Study of lithium conducting single ion conductor based on polystyrene sulfonate for lithium battery application

•Lithium-ion-conducting poly(4-lithium styrene sulfonic acid) was synthesized.•Free-standing polymer electrolyte films were fabricated and the processing method was optimized.•High ionic conductivity of 1.4 × 10−3S/cm achieved.•Lithium ion transport mechanism was elucidated using NMR and electrochemical techniques.