A real-time monitoring of pre-overcharge in high‑nickel lithium ion batteries via plasma emission spectroscopy

Abstract

Using the calibration-free atomic spectroscopic technique on lithium (Li) I with its wavelengths at 610.35, 610.65, and 670.79 nm, Li ion signals at varying state of charge (SOC) from high‑nickel (>88 %) batteries with NCA (Ni-Co-Al) cathode and SCN (silicon carbon nanocomposite) anode are detected in real-time (<3 s). The laser-induced plasma spectroscopy (LIPS) revealed that moderate changes in the concentrations of Li and metals (Ni, Co, and Al) during the normal charging underwent an abrupt concentration change in Li as the SOC reached above 75 %. Verified by using SEM-EDS (Scanning Electron Microscopy-Energy Dispersive Spectrometer), this sudden decrease of Li ions in cathode is deemed as being indicative of the state of overcharge. The present work is aimed at developing a new opto-chemical SOC sensor while the experimental set up offers a new method for detecting the state of pre-overcharge in nickel-rich Li-ion batteries.