Impact of tripropyl borate on life and impedance of lithium-ion cells

Tripropyl borate was investigated as a low cost anion receptor to improve the performance of lithium-ion cells. The impact of tripropyl borate was examined using lithium-ion cells comprising a negative electrode of mesocarbon microbeads, a positive electrode of Li1.1[Mn1/3Ni1/3Co1/3]0.9O2 and an LiPF6-based electrolyte. It was found that the performance of the cells was improved by adding a proper amount of tripropyl borate (≤0.1 wt%) to the LiPF6-based electrolyte. However, a small amount of gas was observed from cells with high contents of tripropyl borate when cycled at 55 °C, and as a result, the performance of the cells deteriorated.