On April 7, the latest research result on the failure mechanism of lithium battery cathode materials "Real-Time Observation of Chemomechanical Breakdown in a Layered Nickel-Rich Oxide Cathode Realized by In Situ Scanning Electron Microscopy" by Researcher Zhang Yuefei and Associate Researcher Lv Junxia from the Institute of Solid Microstructure and Performance of the Facultyof Materials and Manufacturing of BJUT was published on ACS Energy Letters of American Chemical Society, a top journal in the international energy science (ACS Energy Lett.6 (2021) 1703−1710, link to the paper: https://doi.org/10.1021/acsenergylett.1c00279, impact factor 19.003). BJUT is the first completion organization and the only corresponding organization, and Cheng Xiaopeng, class 2017 doctoral student from the Faculty of Materials and Manufacturing, is the first author.

The layered nickel-rich ternary material NMC has become one of the most popular power battery cathode materials with its high energy density and low cost, and is widely used in various types of new energy vehicles. In-situ scanning electron microscopy (in-situ SEM) was used as the main method in this study. Under the actual operating conditions of lithium-ion batteries, the formation and propagation of micro-cracks in the NMC-811 particles during the charge and discharge cycle were directly observed. The internal cracks of NMC secondary particles under high-voltage charge and discharge present a periodic growth pattern of "growth-pause-growth" with the charge and discharge cycles. The panoramic image with resolution-level nanometer generated by that early crack of the layered cathode material during charging and discharging is displayed for the first time in the actual charging and discharging process of lithium ion batteries. This research lays an important theoretical foundation for the development of durable lithium-ion power batteries of high-energy density.