Improving the interfacial resistance in lithium cells with additives

Improved interfacial resistance was observed in lithium cells by the use of new additives. The additives, nitrile sucrose and nitrile cellulose and their lithium salts, were evaluated in polyvinylidene difluoride (PVDF) thin-film gelled electrolytes containing a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC). The electrochemical properties of the films with and without the additives were measured as a function of temperature and compared. The interfacial resistance (Rin) of the films with the additives was significantly lower than that without the additives, especially at sub-ambient temperatures. For example, the Rin at −20°C for the films with additives was around 7000 Ω cm2 and that for the films without the additives was >20,000 Ω cm2. Results obtained from using the additives in lithium-ion (Li-ion) cells show significant improvements in the low frequency resistance of the cells.