Revealing the key role of non-solvating diluents for fast-charging and low temperature Li-ion batteries

Fast-charging and low temperature operation are of vital importance for the further development of lithium-ion batteries (LIBs),which is hindered by the utilization of conventional carbonate-based electrolytes due to their slow kinetics,narrow operating temperature and voltage range.Herein,an acetonitrile (AN)-based localized high-concentration electrolyte (LHCE) is proposed to retain liquid state and high ionic conductivity at ultra-low temperatures while possessing high oxidation stability.We originally reveal the excellent thermal shielding effect of non-solvating diluent to prevent the aggregation of Li+solvates as temperature drops,maintaining the merits of fast Li+transport and facile desolvation as at room temperature,which bestows the graphite electrode with remarkable low temperature performance(264 m A h g-1at-20°C).Remarkably,an extremely high capacity retention of 97%is achieved for high-voltage high-energy graphite||NCM batteries after 250 cycles at-20°C,and a high capacity of110 m A h g-1(71%of its room-temperature capacity) is retained at-30°C.The study unveils the key role of the non-solvating diluents and provides instructive guidance in designing electrolytes towards fastcharging and low temperature LIBs.