Stability of aluminum in low-temperature electrolytes for Li-Ion batteries

摘要

The stability of aluminum at high positive potentials encountered udirng the charging of lithium-ion cells was investigated in solutions of lithium hexafluorophosphate and lithium methide in binary and ternary solvent mixtures of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate using the technique of controlled potential coulometry. It was found that a protective surface film was formed on aluminum electrodes in these solutions that protected them from further corrosion. The protective surface film was found to break down in lithium methide solutions at approx 4.25 V versus a lithium reference electrode resulting in increased corrosion of aluminum electrodes at higher potentials. In contrast to lithium methide solutions, the protective surface film formed on aluminum electrodes in lithium hexafluorophosphate solutions was found to be quite stable and did not break down at potentials up to approx 5 V.