A Dual‐Salt/Dual‐Polymer Quasi‐Solid Electrolyte for High‐Performance Lithium–Oxygen Batteries

The practical application of lithium‐oxygen batteries (LOBs) is hindered by lithium dendrite growth, cathode product accumulation, and electrolyte leakage. Rather than addressing these issues in isolation, we design a strategy employing a quasi‐solid polymer electrolyte based on on a dual‐salt (LiTFSI and LiNO 3 ) and dual‐polymer (PVDF‐HFP/PEO) system, where LiNO 3 serves as a multifunctional filler to synergistically optimize the electrolyte, anode, and cathode. Theoretical calculations reveal that the C–H···F interactions between PEO and PVDF‐HFP optimize the Li + coordination environment, while LiNO 3 disrupts polymer chain ordering and expands amorphous regions. These combined effects enable the electrolyte to achieve a high ionic conductivity of 1.19 mS cm − 1 and a Li + transference number of 0.63 at room temperature. Furthermore, NO 3 − undergoes in situ reduction on the lithium anode surface, inducing the formation of a LiF‐rich SEI layer that effectively suppresses dendrite growth. Its derived NO 2 − /NO 2 redox mediators catalyze the decomposition of Li 2 O 2 , reducing the charge overpotential to 0.44 V and alleviating cathode passivation. Consequently, the multi‐walled carbon nanotube (MWCNT) cathode‐based LOBs achieve a high specific capacity of 14,076 mAh g − 1 and stable cycling for nearly 300 cycles. This provides a new paradigm for designing single‐component fillers to achieve multifunctional integration of electrolytes.