Trace Y Doping Regulated Bulk/Interfacial Reactions of P2‐Layered Oxides for Ultrahigh‐Rate Sodium‐Ion Batteries
Yong Li, Qinhao Shi, Xuan Yu, Fanghua Ning, Guoliang Liu, Xuan Wang, Juan Wang, Yunhua Xu, Yufeng Zhao
Abstract
Abstract P2‐phase layered cathodes play a pivotal role in sodium‐ion batteries due to their efficient Na + intercalation chemistry. However, limited by crystal disintegration and interfacial instability, bulk and interfacial failure plague their electrochemical performance. To address these challenges, a structural enhancement combined with surface modification is achieved through trace Y doping. Based on a synergistic combination of experimental results and density functional theory (DFT) calculations, the introduction of partial Y ions at the Na site (2d) acts as a stabilizing pillar, mitigating the electrostatic repulsions between adjacent TMO 2 slabs and thereby relieving internal structural stress. Furthermore, the presence of Y effectively optimizes the Ni 3d‐O 2p hybridization, resulting in enhanced electronic conductivity and a notable rapid charging ability, with a capacity of 77.3 mA h g −1 at 40 C. Concurrently, the introduction of Y also induces the formation of perovskite nano‐islands, which serve to minimize side reactions and modulate interfacial diffusion. As a result, the refined P2‐Na 0.65 Y 0.025 [Ni 0.33 Mn 0.67 ]O 2 cathode material exhibits an exceptionally low volume variation (≈1.99%), an impressive capacity retention of 83.3% even at −40 °C after1500 cycles at 1 C.