Mixed Ether Electrolytes for Secondary Lithium Batteries with Improved Low Temperature Performance

Tetrahydrofuran (THF): 2‐methyl‐tetrahydrofuran mixed solutions, despite their lower conductivity, have allowed significantly better low temperature performance in cells than have . 13C NMR data suggest that this may be related to the structurally disordered Li+‐solvates that exist in the mixed ether solutions. High cycling efficiencies for the Li electrode in solutions have been achieved by the use of 2Me‐F as an additive. A 5 Ah capacity cell has been cycled more than 100 times at 100% depth‐of‐discharge, with the cell capacity remaining at over 3 Ah at the 100th cycle.