Understanding Degradation in Single-Crystalline Ni-Rich Li-Ion Battery Cathodes

The growing demand for ever-higher-energy-density Li-ion batteries has accelerated the development of Ni-rich transition metal (TM) oxide cathodes. Despite their potential, unsolved degradation mechanisms continue to limit their practical capacity and cycle life. Single-crystalline morphologies have emerged as a promising solution, offering superior mechanical and structural stability compared to polycrystalline cathodes. Nevertheless, degradation still occurs, driven by atomic-scale instabilities, interfacial side reactions, and particle-level mechanical strain. To address these challenges, this review systematically examines cathode development from the atomic to cell level and provides critical insight into how different material design strategies can enhance long-term performance.