期刊
JOURNAL OF ALLOYS AND COMPOUNDS
卷 856, 期 -, 页码 -出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.jallcom.2020.157294
关键词
Na0.67Ni0.33Mn0.67O2; Mg1-xNixO; Surface modification; Cathode materials; Sodium-ion batteries
资金
- Basic Science Research Program of the National Research Foundation (NRF) - Ministry of Science & ICT and Future Planning [NRF2020M3H4A3081893]
- Korea Institute of Science and Technology [2E30212]
P2-type NaNiMnO2 (NNMO) is a high-energy and high-voltage cathode material in sodium-ion batteries, but surface degradation effects limit its electrochemical stability. By applying Mg1-xNixO (MgNiO) as a coating, cycling stability and rate capability of NNMO can be significantly improved.
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.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据