“Rigid Exterior, Soft Interior” Design Enables High‐Voltage Polyether Electrolytes for Quasi‐Solid‐State Batteries

QSSB shows a Coulombic efficiency of ∼100% and an extremely high capacity retention of 95.4% after 600 cycles at 3C. A capacity retention of over 96.3% after 400 cycles at 1C are further realized in 4.5 V Li||NCM811 QSSB.