Kim, Hyeongwoo Park, Jae-Ho Kim, Sung-Chul Byun, Dongjin Chung, Kyung Yoon Kim, Hyung-Seok Choi, Wonchang 2024-01-19T15:04:22Z 2024-01-19T15:04:22Z 2021-09-04 2021-03-05 0925-8388 https://pubs.kist.re.kr/handle/201004/117271 P2-type Na0.67Ni0.33Mn0.67O2 (NNMO) is a state-of-the-art, high-energy and high-voltage cathode material in sodium-ion batteries. However, surface degradation effects, such as P2-O2 phase transformation, ordering of Na+/vacancy, electrolyte decomposition, and HF attack, limit its electrochemical stability. To counter these effects, we applied Mg1-xNixO (MgNiO) as a coating formed via wet-chemical coating to suppress unfavorable side reactions; surface doping of Mg2+ also occurs post-calcination, which is expected to reduce P2-O2 transition near the surface structure. MgNiO-NNMO exhibited outstanding cycling stability (70.08 mAh g(-1) over 200 cycles) and rate capability (39.41 mAh g(-1) at 5C over 800 cycles). The influence of Mg2+ doping was studied comprehensively through in situ and ex situ X-ray diffraction analysis. Furthermore, to characterize the protective role of the MgNiO coating in harsh conditions, we operated NNMO as Na half cells at a high temperature of 60 degrees C and high voltage of 4.5 V (vs. Na+/Na) for the first time; under these conditions, MgNiO-NNMO exhibited remarkable cycling stability (52.68 mAh g(-1) over 100 cycles) as compared to pristine NNMO (7.213 mAh g(-1) over 100 cycles). Surface analysis via X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy were also conducted to investigate the impact of electrolyte decomposition and HF attack. (C) 2020 Elsevier B.V. All rights reserved. English ELSEVIER SCIENCE SA Multiple effects of Mg1-xNixO coating on P2-type Na0.67Ni0.33Mn0.67O2 to generate highly stable cathodes for sodium-ion batteries Article 10.1016/j.jallcom.2020.157294 1 JOURNAL OF ALLOYS AND COMPOUNDS, v.856 JOURNAL OF ALLOYS AND COMPOUNDS 856 scie scopus 000627309500019 2-s2.0-85092529270 Chemistry, Physical Materials Science, Multidisciplinary Metallurgy & Metallurgical Engineering Chemistry Materials Science Metallurgy & Metallurgical Engineering Article LAYERED OXIDE CATHODE CYCLING STABILITY LONG-LIFE PERFORMANCE VOLTAGE SURFACE NA2/3NI1/3MN2/3O2 TRANSITION LITHIUM DIFFUSION Na0.67Ni0.33Mn0.67O2 Mg1-xNixO Surface modification Cathode materials Sodium-ion batteries