رسالة جامعية
A Nuclear Magnetic Resonance Approach Towards Understanding Surface Modification and its Influence on Ni-rich Layered Oxides in Li-ion Batteries
| العنوان: | A Nuclear Magnetic Resonance Approach Towards Understanding Surface Modification and its Influence on Ni-rich Layered Oxides in Li-ion Batteries |
|---|---|
| المؤلفون: | Chen, Richard Lin Bin |
| بيانات النشر: | University of Cambridge Department of Chemistry Pembroke College |
| سنة النشر: | 2023 |
| المجموعة: | Apollo - University of Cambridge Repository |
| مصطلحات موضوعية: | Al2O3, coatings, Li-ion batteries, Ni-rich cathode, Nuclear Magnetic Resonance, X-ray diffraction, X-ray spectroscopy |
| الوصف: | Rechargeable lithium-ion batteries (LIBs) are crucial for transitioning towards a carbon neutral society. Nickel-rich layered oxides are the state-of-the-art material of choice, offering high practical capacities. However, accessing this high capacity induces structural degradation and parasitic electrolyte reactions at the surface. One strategy to mitigate this problem is surface modification with coating materials like Al 2 O 3 – cycling life is extended but the fundamental reasons behind the protection are not well understood. Therefore, the aim of the thesis is to identify the characteristics of coatings that contribute to this protection with polycrystalline LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) coated with Al 2 O 3 by atomic layer deposition (ALD) being studied. Varying the number of ALD cycles allows investigation of the influence of coating thickness (sub-nm differences) on surface degradation. Coupled with electrochemical cycling, it is revealed that an optimal coating thickness exists, balancing initial capacity with retentions. X-ray spectroscopy and diffraction confirm surface degradation is reduced with coating on the NMC811. Meanwhile, 27 Al solid state (ss)NMR indicates that the chemical evolution of the coating is not correlated with coating thicknesses. Detailed structural and chemical evolution of the Al 2 O 3 coating at different stages of the electrochemical cycling process is tracked using a multinuclear NMR approach. Probing dipolar interactions between 27 Al and 1 H/ 19 F/ 7 Li shows the coating is susceptible to reactions involving acidic and protic species from the electrolyte, but no lithiated alumina phase is formed. The changes are concomitant with stabilisation of the surface oxygen electronic structure by the coating, supported by less electrolyte degradation. Finally, the heat treatment and performance of Al 2 O 3 coated NMC811 is presented to provide insights into the effect of a range of coating structures. 27 Al ssNMR shows that heating induces Al doping into the bulk NMC ... |
| نوع الوثيقة: | doctoral or postdoctoral thesis |
| وصف الملف: | application/pdf |
| اللغة: | English |
| العلاقة: | https://www.repository.cam.ac.uk/handle/1810/363504Test; https://doi.org/10.17863/CAM.105541Test |
| DOI: | 10.17863/CAM.105541 |
| الإتاحة: | https://doi.org/10.17863/CAM.105541Test https://www.repository.cam.ac.uk/handle/1810/363504Test |
| حقوق: | All Rights Reserved ; https://www.rioxx.net/licenses/all-rights-reservedTest/ |
| رقم الانضمام: | edsbas.476AE5D5 |
| قاعدة البيانات: | BASE |
| DOI: | 10.17863/CAM.105541 |
|---|