![]() ![]() Meanwhile, volume changes during cycling and the generation of microcracks during cycling, and the generation of thicker cathode electrolyte interface (CEI) films on the surface are the main causes of cathode material degradation 4, 5. Furthermore, interfacial side reactions and dissolution of transition metals lead to the degradation of performance. In addition, the electrolyte solvent with a narrow electrochemical stability window will react with Ni 4+, leading to the oxidative decomposition of the electrolyte 3. ![]() Structural defects such as Li/transition metal atom mixing or oxygen vacancies will cause further phase transitions, surface reconfiguration, and accompanied by the evolution of oxygen 1, 2. Consequently, many researchers have investigated the origin of the degradation mechanism in NCM through advanced electron microscopy. Current electron microscopy allows the direct visual recognition of atom-level configuration information from the host crystal structure, lattice plane distortion to even single point defect, providing rich information of battery material processes and properties. The advanced electron microscopy investigations on the degradation mechanisms of NCM play indispensable roles in the design of high-energy-density lithium-ion battery materials. However, the rapid capacity fade over cycles of NCM severely hinders its development and applications. LiNi xCo yMn 1-x-yO 2 (NCM) has become one of the most popular cathode materials for current lithium-ion batteries due to its high capacity and cost-effectiveness. It also provides interesting hints for researchers to regenerate the electrochemical capacity and design better battery materials with longer life. This analysis sheds light on the defect evolution and chemical transformation correlated with layered material degradation. The space between the transition metal columns shrinks obviously, inducing dramatic capacity decay. The number of point defects in NCM523 is observed to experience a trend of increasing first and then decreasing in the degradation process. Then we developed a neural network model with a two-sequential attention block to recognize the crystal structure and locate defects in STEM images. Here, the single crystal NCM523 materials under different degradation states are characterized using scanning transmission electron microscopy (STEM). However, the rapid capacity fading of NCM severely hinders its development and applications. LiNi 0.5Co 0.2Mn 0.3O 2 (NCM523) has become one of the most popular cathode materials for current lithium-ion batteries due to its high-energy density and cost performance. ![]()
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