AC-IMPEDANCE BEHAVIOR OF LITHIUM ELECTRODE IN ORGANIC ELECTROLYTE-SOLUTIONS CONTAINING ADDITIVES

Effects of organic additives on the ac impedance behaviour of rechargeable lithium electrode in propylene carbonate dissolving LiClO4 (PC/LiClO4) have been studied. Addition of 2-methylfuran, 2-methylthiophene or benzene to the electrolyte solution improved the coulombic efficiencies of lithium during deposition/dissolution cycles, and decreased the electrical resistance at the electrode-electrolyte interface. The time constant of ac impedance at the interface without the additives kept constant during the electrode immersion, whereas the time constant in the solution containing 2-methylfuran or 2-methylthiophene varied with the immersion time. Addition of benzene to the electrolyte did not change the time constant of the impedance. The impedance profiles during the deposition/dissolution cycles suggested some surface reaction in the solution with 2-methylfuran or 2-methylthiophene and an adsorption process in the solution containing benzene.