Solvation and Interfacial Engineering Enable -40 °C Operation of Graphite/NCM Batteries at Energy Density Over 270 wh/kg.

Li-ion batteries (LIBs) that can operate under low temperature (LT) conditions are essential for applications in orbital missions, subsea areas and electric vehicles. Unfortunately, severe capacity loss is witnessed due to tremendous kinetic barriers emerged at LT. Herein, to surmount such kinetic limitations, a low dielectric environment is tamed throughout bulk electrolyte, which efficaciously brought the Li + desolvation energy down to 30.76 KJ/mol. At the meantime, we proposed the adoption sodium cations (Na + ) as a hetero-cation additive, and further identified a Li-Na hybrid and fluoride-rich interphase via preferential reduction of Na + -(solvent/anion) clusters, which is found to efficiently facilitate Li + migration through the LiF/NaF grain boundaries. Based on a N/P ratio of 1.1, the graphite/LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM) full cell (cathode loading of ∼18.5 mg/cm 2 ) delivers a capacity high as 125.1 mAh/g under -20 °C with prolonged cycling to 100 cycles. Finally, a 270 Wh/Kg graphite/NCM pouch cell was assembled, and by elevating the cutoff voltage to 4.6 V, the cell affords a discharge capacity of 108.7 mAh/g under -40 °C during the initial cycles. With an eye to both fundamental and practical aspects, this work would propel additional advancements and allow LIBs to fill more roles under extreme operation temperature than ever before. This article is protected by copyright. All rights reserved.