Acid Scavenging via Ion-Exchange Resin Coating Enables Durable High-Temperature Sodium-Ion Batteries

O3-type layered transition metal oxides are regarded as frontrunners for sodium (Na)-ion batteries (NIBs) due to their high capacity and ease of synthesis, but their practical deployment is hindered by interfacial instability. Herein, we reveal that sulfate-based electrolyte additives, 1,3-propanediol cyclic sulfate (PCS) and 1,3,2-dioxathiolane 2,2-dioxide (DTD), effectively construct a robust cathode-electrolyte interphase (CEI) at 25 °C, but hydrolysis at 60 °C releases acidic protons. This acidity promotes the decomposition of NaPF 6 to generate corrosive HF, leading to aggressive lattice corrosion, CEI and transition metal (TM) dissolution. To overcome this dilemma, we applied a functional sodium-type ion-exchange resin coating on the cathode to scavenge protons via spontaneous ion exchange. This strategy effectively eliminates corrosive impurities and suppresses TM dissolution, significantly improving the high-temperature cycling stability. This work provides critical insights into electrolyte additive instability and establishes a facile solution for stabilizing electrode interfaces, paving the way for durable, high-performance NIBs.