Ability of Li4Ti5O12 to suppress Li metal deposition under overpotential conditions confirmed by electrochemical surface plasmon resonance spectroscopy

Abstract

Undesirable Li metal deposition on the negative electrode increases the risks associated with the use of Li-ion batteries. Generally, spinel-type lithium-titanium oxide Li4Ti5O12 (LTO)-based negative electrodes are well known as safe dendrite-free options, due to their higher working potential. However, the ability of LTO-based materials to prevent Li metal deposition has not been well confirmed under sudden overpotential application. This study examines the behavior of Li metal electrodeposition under various overpotential conditions for unloaded and LTO-loaded Cu electrodes. Electrochemical surface plasmon resonance spectroscopy (EC-SPR) is used as the optical diagnostic technique, owing to its sensitivity in detecting Li metal deposition. Li metal deposition is easily detected for the unloaded Cu electrode at overpotential of − 0.2 V (voltage) versus Li counter electrode (LiCE), whereas no Li metal deposition occurs for the LTO-loaded Cu electrode under the same overpotential. The safety of LTO is investigated by analyzing the reaction kinetics.