Multifunctional single-ion block copolymer electrolytes (BCEs) based on polyanionic block copolymers comprising polystyrene segments were successfully prepared at our lab. With a lithium-ion transport number close to unity, these BCEs showed excellent mechanical properties and an electrochemical stability window spanning 5V versus Li+/Li0. A prototype battery using this polyelectrolyte outperforms a conventional battery based on a polymer electrolyte especially at high temperatures. Using SAXS measurements, nanoscale structured polyanionic-BCE has been proved. The proposed SANS experiment aims at investigating the evolved morphological modification of this solid-state electrolytes as well as the electrode-electrolyte interface stability during galvanostatic charge/discharge cycling in Li/electrolyte/ LiFePO4 cell at two different temperatures. The in situ SANS investigation along with the measured battery performance at different discharge/charge rates will also provide important information on possible formation of oriented 1D-ion conductive polymeric materials.