Electrolyte for high voltage Li/LiMn1.9Co0.1O4 cells

An electrolyte for high voltage lithium metal anode cells must simultaneously satisfy at least the following requirements; (i) high cycling efficiency on the lithium metal anode; (ii) higher oxidation potential than the charging voltage, and (iii) high specific conductivity. We have examined various electrolytes for lithium metal anode cells using a high voltage cathode, LiMn1.9Co0.1O4. Of the electrolytes resistant to high voltage that we used, a system containing 60 to 90 vol.% of dimethyl carbonate (DMC) mixed with ethylene carbonate (EC) and 1.0 M lithium hexafluorophosphate (LiPF6) provided the best cycling efficiency on a lithium metal anode, as well as a high specific conductivity around 10 mS cm−1 at 20 °C.