Methyl Acetate Boosts the Low-Temperature Performance of Li 4 Ti 5 O 12 /Graphite Dual-Ion Batteries.

Methyl acetate (MA) is a suitable solvent for low-temperature electrolyte solutions, but its poor stability against lithium metal is a big problem. Herein, a simple and cheap solution of LiPF 6 dissolved in MA was successfully employed for Li 4 Ti 5 O 12 /graphite dual-ion batteries (DIBs). This cell has a long cycle life with 93.1% capacity retention after 1000 cycles. Moreover, it has superior performance at low temperatures (-40 °C) compared to other reported DIBs. The storage behavior of PF 6 - solvated by MA in graphite cathode has been investigated in detail by in situ X-ray diffraction (XRD) in combination with electrochemical dilatometry (ECD).