期刊
ACS APPLIED MATERIALS & INTERFACES
卷 14, 期 4, 页码 5338-5345出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsami.1c21103
关键词
NaxTMO2; degradation and recovery; reactivity under ambient atmosphere; sodium-ion batteries
资金
- Startup Foundation for Hundred-Talent Program of Zhejiang University
- State Key Laboratory of Clean Energy Utilization at Zhejiang [ZJUCEU2020005]
- National Natural Science Foundation of China [U21A2075]
This study revealed the degradation mechanism of transition metal oxide cathode materials under ambient air, showing that CO2 insertion leads to the growth of Na2CO3 nanoseeds and subsequent structure degradation. The extent and pathways of degradation are highly influenced by crystal orientation, particle morphology, and ambient humidity. The degradation can be completely healed through optimal recalcination, resulting in improved air-stability and electrochemical performance.
The air-sensitivity of transition metal oxide cathode materials (NaxTMO2, TM: transition metal) is a challenge for their practical application in sodium-ion batteries for large-scale energy storage. However, the deterioration mechanism of NaxTMO2 under ambient air is unclear, which hinders the precise design of air-stable NaxTMO2. Here, we revealed the origin of NaxTMO2 degradation by capturing the initial degradation status and microstructural evolution under ambient atmospheres with optimal humidity. It was found that the insertion of CO2 into Na layers along (003) planes of NaxTMO2 led to initial growth of Na2CO3 nanoseeds between TM layers, which initiated fast structure degradation with surface cracks and extrusion of Na2CO3 out of NaxTMO2. The degradation extents and pathways for NaxTMO2 could be highly associated with crystal orientation, particle morphology, and ambient humidity. Interestingly, the deteriorated NaxTMO2 could be completely healed through optimal recalcination, showing even improved air-stability and electrochemical performance. This work provides a helpful perspective on the interfacical structure design of high-performance NaxTMO2 cathodes for sodium-ion batteries.
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