EC-Less Electrolytes for High-Safety and Long-Life Nickel-Rich Lithium-Ion Batteries

High-nickel lithium-ion batteries are known for their high energy density, but face severe safety challenges. The initial heat and gas accumulation originate from the highly reductive lithiated anode at the anode-electrolyte interface within the cell, which finally triggers the intensive exothermic reactions. Herein, an ethylene carbonate-less (EC-less) electrolyte endowed with a bianionic coordination solvation structure is designed, which significantly enhances the thermal stability of LiNi0.8Co0.1Mn0.1O2|graphite (NCM811|Gr) pouch cells by mediating anode-electrolyte interfacial reactions. This bianionic structured EC-less electrolyte demonstrates superior reductive stability against the highly reactive lithiated anode, as evidenced by its elevated lowest unoccupied molecular orbital (LUMO) energy level. Material-level thermal analysis confirms that EC-less electrolyte markedly manipulates the electrolyte reduction reactions, achieving a 29.7% reduction in heat release (−225.5 J g −1 ) relative to conventional electrolyte (−320.8 J g −1 ). Further validation using 1 Ah NCM811|Gr pouch cells demonstrates that EC-less electrolyte enables the cell to maintain thermal inertness at 180 °C for 40 min, whereas a conventional cell experiences intensive thermal runaway at 160 °C. Furthermore, EC-less electrolyte facilitates the formation of an inorganic-rich interphase, and the pouch cell exhibits excellent electrochemical performance. This research highlights the potential of interfacial reaction engineering for safer high-nickel lithium batteries.