Triple Salts Electrolyte for High Cyclability and High Capability in Practical Safe Nickel-Rich Batteries

The pursuit of extended driving ranges of electric vehicles has spurred the use of nickel-rich layered cathodes, yet raised safety concerns. Existing ethylene carbonate-free electrolytes improve safety but compromise electrochemical performances due to the delicate balance between anode interphases. We introduce a novel electrolyte composed of propylene carbonate (PC) and triple lithium salts, which synergistically reinforces both cathode and anode interfaces. PC's low kinetic reactivity with LiNi_0.8Mn_0.1Co_0.1O₂ (NCM811) at the cathode minimizes heat generation and oxygen evolution. To stabilize the anode, bis(fluorosulfonyl)imide (FSI^-) anions are integrated to construct an anion-driven interface, while difluoro(oxalato)borate (DFOB^-) is added to lower PC's de-solvation energy and prevent co-intercalation. NCM811/Graphite pouch cells utilizing this electrolyte show enhanced safety, cyclability, and rate capability, surviving 60 minutes at 180℃ without incident. Post-mortem analysis reveals suppressed parasitic reactions and the formation of a robust solid electrolyte interphase (SEI). This research offers a critical framework for the design of electrolytes tailored for high-energy lithium-ion batteries.