Inhibition of the detrimental effects of water impurities in lithium-ion batteries

The effect of dimethyl acetamide (DMAc) on the stability of LiPF6 based electrolytes contaminated with water impurities has been investigated. Addition of 1% DMAc to 1 M LiPF6 in 1: 1: 1 ethylene carbonate/diethyl carbonate/dimethyl carbonate (EC/DEC/DMC) with 0.5% water impurity was found to inhibit the generation of HF and other decomposition products. The presence of water results in a decrease in the first cycle efficiency and an increase in the capacity fade in following cycles. The addition of DMAc to water containing electrolytes has little effect on the first cycle efficiency, but it reduces the capacity fade of the batteries containing water impurities by 72%. (c) 2007 The Electrochemical Society.