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In situ lithiated ALD niobium oxide for improved long term cycling of layered oxide cathodes: A thin-film model study
ChemRxiv Pub Date : 2021-01-21
Abdessalem Aribia, Jordi Sastre, Xubin Chen, Evgeniia Gilshtein, Ayodhya N. Tiwari, Yaroslav E. Romanyuk

Protective coatings applied to cathodes help to overcome interface stability issues and extend the cycle life of Li-ion batteries. However, within 3D cathode composites it is difficult to isolate the effect of the coating because of the additives and non-ideal interfaces. In this study we investigate niobium oxide (NbOx) as cathode coating in a thin-film model system, which provides simple access to the cathode-coating-electrolyte interface. The conformal NbOx coating was applied by atomic layer deposition (ALD) onto thin-film LiCoO2 cathodes. The cathode/coating stacks were annealed to lithiate the NbOx and ensure sufficient ionic conductivity. A range of different coating thicknesses were investigated to improve the electrochemical cycling with respect to the uncoated cathode. At a NbOx thickness of 30 nm, the cells retained 80% of the initial capacity after 493 cycles at 10 C, more than doubling the cycle life of the uncoated cathode film. At the same thickness, the coating also showed a positive impact on the rate performance of the cathode: 47% of the initial capacity was accessible even at ultrahigh charge-discharge rates of 100 C. Using impedance spectroscopy measurements, we found that the enhanced performance is due to suppressed interfacial resistance growth during cycling. Elemental analysis using TOF-SIMS and XPS further revealed a bulk and surface contribution of the NbOx coating. These results show that in situ lithiated ALD NbOx can significantly improve the performance of layered oxide cathodes by enhancing interfacial charge transfer and inhibiting surface degradation of the cathode, resulting in better rate performance and cycle life.

中文翻译:

原位锂化ALD铌氧化物改善层状氧化物阴极的长期循环:薄膜模型研究

应用于阴极的保护涂层有助于克服界面稳定性问题并延长锂离子电池的循环寿命。但是,在3D阴极复合材料中,由于添加剂和非理想的界面,很难隔离涂层的效果。在这项研究中,我们研究了氧化铌(NbOx)作为薄膜模型系统中的阴极涂层,该系统可轻松访问阴极涂层-电解质界面。通过原子层沉积(ALD)将共形NbOx涂层施加到薄膜LiCoO2阴极上。使阴极/涂层堆叠退火以使NbOx锂化并确保足够的离子电导率。研究了一系列不同的涂层厚度以改善相对于未涂层阴极的电化学循环。在NbOx厚度为30 nm时,在10 C进行493次循环后,电池保留了80%的初始容量,是未涂层阴极膜的循环寿命的两倍多。在相同的厚度下,涂层也对阴极的速率性能产生了积极的影响:即使在100 C的超高放电速率下,初始容量的47%仍可达到。使用阻抗谱测量,我们发现性能得到了提高这是由于在循环过程中抑制了界面电阻的增长。使用TOF-SIMS和XPS进行的元素分析进一步揭示了NbOx涂层的体积和表面贡献。这些结果表明,原位锂化ALD NbOx可以通过增强界面电荷转移并抑制阴极的表面降解来显着改善层状氧化物阴极的性能,
更新日期:2021-01-21
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