@article{Ding2025, 
author = {Xiang Ding and Weiwu Yuan and Junwei Lin and Haonan Li and Xiao Yang and Liangwei Liu and Yi Xiao and Fang Chen and Lili Han},
title = {In-situ surface coating and subsurface gradient doping contrives P2-Na0.67Ni0.33Mn0.67O2 single crystal with highly stable interface and structure},
year = {2025},
journal = {Nano Research Energy},
volume = {4},
pages = {e9120203},
keywords = {sodium-ion batteries, high-performance, P2-Na0.67Ni0.33Mn0.67O2, subsurface gradient doping, in-situ surface coating},
url = {https://www.sciopen.com/article/10.26599/NRE.2025.9120203},
doi = {10.26599/NRE.2025.9120203},
abstract = {P2-Na0.67Ni0.33Mn0.67O2 cathode holds the merits of high working voltage/capacity, facile manufacture, and similar large-scale production to Li layered oxides. However, it suffers from issues of irreversible P2–O2 phase transition at a high voltage (>4.0 V), interfacial instability, and particle cracks after repeated cycle. Herein, in-situ formed MgO surface coating layer and Mg2+ subsurface gradient doping is obtained by Mg3(PO4)2 decomposition under 900 ℃. The as-formed in-situ surface coating and subsurface doping effects simultaneously guarantee the high-stability of material interface and structure. HRTEM and HAADF-STEM images clearly show the surface coating layer is 2‒5 nm and subsurface gradient doping depth is 3‒5 nm, rather than bulk doping. In-situ XRD patterns and in-situ DRT analysis profoundly clarify the enhanced electrochemical reaction stability and structural reversibility. Theoretical calculations elucidate superior electronic and spatial structures after in-situ surface coating and subsurface doping engineering. As a result, the optimized cathode shows ascendant discharge capacity of 100.3 mAh·g–1 at 1C with 80.8% retention during 500 cycles. It displays much improved rate capability of 81.5 mAh·g–1 at 5C. Revealing excellent cycling stability and potential applications for high-performance sodium-ion batteries.}
}