Li Plating on Carbon Electrode Surface Probed by Low-Field Dynamic Nuclear Polarization 7Li NMRSupported by the National Key Research and Development Program of China (Grant No. 2018YFC0115000), the National Natural Science Foundation of China (Grant No. 21603267), and the Chinese Academy of Sciences (Grant No. YZ201677 and YZ201551).

Abstract

Lithium deposition on graphite electrode not only reduces fast-charging capability of lithium ion batteries but also causes safety trouble. Here, a low-field 7Li dynamic nuclear polarization (DNP) is used to probe Li plating on the surfaces of three types of carbon electrodes: hard carbon, soft carbon and graphite. Owing to the strong Fermi contact interaction between 7Li and conduction electrons, the 7Li nuclear-magnetic-resonance (NMR) signal of Li metal deposited on electrode surface could be selectively enhanced by DNP. It is suggested that low-field 7Li DNP spectroscopy is a sensitive tool for investigating Li deposition on electrodes during charging/discharging processes.