Steric Coordinated Electrolytes for Fast-charging and Low-temperature Energy-dense Lithium-ion Batteries

Abstract

Electrolytes are known as the dominant factors for fast-charging affordability and low-temperature capability of lithium-ion batteries (LIBs). Unfortunately, the current electrolytes can hardly simultaneously satisfy all the required characteristics, including sufficient ion transport, high oxidation/reduction interfacial stability, and fast de-solvation process over a wide-temperature range. Here, we report a solution by designing electrolyte solvents that coordinate with Li+ in steric configuration. The steric coordinated electrolytes (SCEs) can overcome the dilemma of quasi-planer coordinated ether electrolytes that has to be weakly coordinated with Li+ to avoid solvent co-intercalation towards graphite (Gr) anode, therefore enabling the merits including sufficiently dissociation of Li-salt with high ionic conductivity, low de-solvation energy, and forming electrode-electrolyte interphase with low energy barrier. As results, the SCEs with only single-salt and single-solvent (trimethoxymethane) achieve fast kinetics towards Gr anode and high oxidation stability. The LiNi0.8Co0.1Mn0.1O2 (NCM811)||Gr LIBs can reach 80% state of the charge in 6 min, and the Ah-level energy-dense pouch cells (4.5-volt) retain 82.96% (500 cycles) and 85.94% (200 cycles) of initial capacities at room temperature and -20°C, respectively. Our work deepens the fundamental understanding of Li-ion solvation structures and affords an effective approach to design sustainable fluro-free electrolytes for battery systems.