Kinetic and interfacial characterization of lithium electrodes in organic electrolyte solutions

摘要

Kinetic parameters, such as polarization resistance, exchange current density, and transfer coefficient, for lithium electrodes in a few important lithium battery electrolyte solutions were determined at 27degreesC using the galvanostatic pulse technique and constant charge-step method. The solvents used were ethylene and diethyl carbonates mixtures and propylene carbonate. The electrolytes used were LiPF6, LiClO4, and LiBF4. The electrode capacitance was also measured. The effects of the electrolyte concentration and storage time on the polarization resistance and the electrode capacitance were examined. The data obtained for lithium in 1 M LiClO4/PC and 1 M LiPF6/EC-DEC (1:1) electrolyte solutions are consistent with those reported in the literature. During two days of storage, the polarization resistance of the lithium in the 1 M LiPF6/EC-DEC solutions only increased slightly, but the polarization resistance of the lithium in the 1 M LiPF6/PC solutions increased remarkably. The electrode capacitance, however, decreased during prolonged storage for the systems studied. A nickel microdisk electrode was also used to study the electrodeposition and electrodissolution of lithium in the 1 M LiPF6/EC-DEC (1:1) electrolyte solutions. The diffusion coefficient was also determined.