Unveiling the Correlation Between Structural Stability and Electrochemical Characteristics of Single Crystalline Layered Ni‐Rich Cathodes

Abstract Single crystalline (SC) Ni‐rich layered lithium metal oxides are promising cathode materials for lithium‐ion batteries due to their high theoretical capacity (> 200 mAh g ⁻¹ ) and reduced cobalt composition. However, electrochemical behavior of Ni‐rich materials is underexplored and requires a better understanding to address existing challenges such as elongated Li‐ion diffusion pathways and unstable cycling performance. In this study, SC cathode materials with 83% and 90% Ni content are electrochemically cycled at 1 C from 3 to 4.5 V for up to 300 charge/discharge cycles to investigate changes in impedance, non‐faradaic and faradaic electrochemical active surface areas, and structural evolution. Non‐faradaic electrochemical active surface area (ECSA) measurement increases from 1.81 to 3.30 m ² g ⁻¹ for smaller particles sized NCM 90 (3.12 µm) and 3.14 to 3.52 m ² g ⁻¹ for larger particles sized NCM 83 (6.18 µm) after 300 cycles. Faradaic ECSA for NCM 83 increased by 34.4% at the reduction stage, whereas NCM 90 reduced by 61.46% contributing to recurring surface reconstruction and microcracking. Micro‐computed tomography reveals greater material loss in NCM 83 (≈4.5%) compared to NCM 90 (≈2%), attributed to larger particle size. These insights shed new light on surface and structural changes in SC high‐Ni cathodes and their effects on electrochemical performance.