Authors

Abstract

X-ray radiation damage on the measuring system has been a critical issue regularly for a long-time exposure to X-ray beam during the in-operando characterizations, which is particularly severe when the applied X-ray energy near the absorption edges (M, L, K, etc.) of the interest element. To minimize the negative effects raised by beam radiation, we employ quick X-ray absorption spectroscopy (QXAS) in studying the electrochemical reaction mechanism of Ni-rich layered structure cathode for lithium-ion batteries. With the advanced QXAS technique, the electronic structure and local coordination environment of the transition metals (TMs) are in-operando monitored with limited radiation damage. Compared to the conventional step-mode XAS, the QXAS can provide more reliable oxidation state change and more detailed local structure evolutions surrounding TMs (Ni and Co) in Ni-rich layered oxides. By leveraging these advantages of QXAS, we demonstrate that the Ni dominates the electrochemical process with the Co being almost electrochemically inactive. Reversible Ni ions movement between TM sites and Li sites is also revealed by the time-resolved QXAS technique.