Controlling Interfacial Reduction Kinetics and Suppressing Electrochemical Oscillations in Li4Ti5O12 Thin-Film Anodes
Controlling Interfacial Reduction Kinetics and Suppressing Electrochemical Oscillations in Li4Ti5O12 Thin-Film Anodes
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DOI：
10.1002/adfm.202105354
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发表时间：
2021-08-06
影响因子：
19
通讯作者：
Huang, Zhigao
中科院分区：
文献类型：
--
作者：
Chen, Yue;Pan, Handian;Huang, Zhigao
了解相分离材料（如钛酸锂（LTO））中表面装饰效应的基本原理对于优化锂离子电池（LIB）性能非常重要。LTO多晶薄膜电极与掺杂的Al-ZnO（AZO）表面涂层装饰被用作理想的模型，以深入了解所涉及的机制。操作剪切力调制光谱是用来观察第一次的纳米级动态固体电解质界面（SEI）形成的电极表面上，证实了AZO涂层电化学转化成一个刚性，均匀的SEI层，保护表面从电解质诱导的分解。该AZO层及其所得的人工SEI层具有比未改性的表面更高的Li离子传输速率。这些层可以减少表面成核的障碍，并促进在Li 4 Ti 5 O 12可逆箭头Li 7 Ti 5 O 12相分离过程中锂离子的快速再分布，显著抑制LTO电极中的有序集体相分离行为（电化学振荡）。抑制的电压振荡表明更均匀的局部交换电流密度和脱嵌/嵌入状态与装饰电极，从而延长其电池效率和长期循环稳定性。这项工作突出了LIB材料的表面处理的最终重要性，以确定其界面化学和相变过程中的嵌入/脱嵌。
Understanding the fundamentals of surface decoration effects in phase-separation materials, such as lithium titanate (LTO), is important for optimizing the lithium-ion battery (LIB) performance. LTO polycrystalline thin-film electrodes with and without doped Al-ZnO (AZO) surface coating decoration are used as ideal models to gain insights into the mechanisms involved. Operando shear force modulation spectroscopy is used to observe for the first time the nanoscale dynamics of solid-electrolyte-interphase (SEI) formation on the electrode surfaces, confirming that the AZO coating is electrochemically converted into a stiff, homogenous SEI layer that protects the surface from the electrolyte-induced decomposition. This AZO layer and its resultant artificial SEI-layer have higher Li-ion transport rates than the unmodified surface. These layers can reduce barriers to surface nucleation and facilitate rapid redistribution of lithium-ions during the Li4Ti5O12 reversible arrow Li7Ti5O12 phase separation, significantly inhabiting the orderly collective phase-separation behavior (electrochemical oscillation) in the LTO electrode. The suppressed voltage oscillations indicate more homogeneous local exchange current density and de/intercalation states with the decorated electrodes, thereby extending their battery efficiency and long-term cycling stability. This work highlights the ultimate importance of surface treatment for LIB materials for determining their interfacial chemistry and phase transition during the intercalation/deintercalation.