Cyclic chronopotentiometric studies of the LiAl anode in methyl acetate

Abstract

The applicability of methyl acetate as a solvent for ambient temperature lithium secondary batteries was investigated using cyclic chronopotentiometry. Methyl acetate was found to be stable towards lithium-aluminium alloys and cycling up to more than 300 cycles was obtained with about 90% cycling efficiency. Water and other organic impurities have been identified in methyl acetate and a thorough purification procedure has been used to reduce these to acceptable levels. LiAsF6, LiPF6, LiClO4 and LiBF4 were investigated for use as supporting electrolytes and LiAsF6 was found to be the best in terms of cycling efficiency, longer cycling numbers and yielding the lowest corrosion capacity loss rate. The development of the LiAl anode upon cycling was observed in parallel with the reduction in nucleation polarization potential, the increase in cycling efficiency, the lowering of concentration polarization at the electrode surface and the more ready acceptance of lithium deposition at the developed electrode. The optimum conditions for the development of the LiAl anode were found to exist at a current density of 5 mA cm−2 and a charge density of 0.5 C cm−2.