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通过简单的酸冲洗在丰富的氧化物阴极材料中扩大界面稳定性

Srinivasan Ramakrishnan¹, Byungchun Park^1,2, Jue Wu^3,4

¹Department of Chemical and Biomolecular Engineering, University of California Berkeley, Berkeley, California 94720, United States.

Journal of the American Chemical Society

|April 10, 2020

概括

酸性表面处理有效地使丰富的氧化物阴极无活性,显著减少高压充电期间有害气体的演化. 这种简单的方法可以提高电池的循环和速度,而不会损失容量.

科学领域:

材料科学
电化学
能量储存

背景情况:

多层,和 (NMC) 氧化物是离子电池的高容量阴极.
高压运行 (>4.8V) 会导致界面降解和气体演变 (CO2,O2),限制电池的性能和安全性.
有效的表面被动化策略对于稳定的高压阴极运行至关重要.

研究的目的:

调查酸性表面处理对高电压的丰富NMC阴极性能的影响.
抑制不可逆转的气体演变并提高界面稳定性.
了解表面被动化和氧氧还原活性的基本机制.

主要方法:

富含的NMC层氧化物阴极材料的酸性表面处理.
电化学测试 (循环,速率能力) 达4.8V与Li+/0.
气体演变分析 (CO2,O2).
现场酸定位以量化氧氧还原参与.
使用X射线光电子光谱 (XPS) 和Mn L边缘X射线吸收光谱 (XAS) 进行表面表征.
通过OK边缘共振无弹性X射线散射 (RIXS) 进行氧氧还原行为分析.

主要成果:

在第一个充电过程中,酸性处理显著抑制了CO2 (~90%) 和O2 (~100%) 的演变.
处理消除了Li2CO3并使表面不受电解质降解而不会损失容量.
与未经处理的材料相比,观察到更好的长期循环和速度性能.
表面分析显示处理材料的Li+缺乏和部分Mn减少.
尽管抑制了不可逆转的气体进化,但晶格氧氧还原活性在很大程度上持续存在.

结论:

酸性表面处理是一种简单而有效的策略,用于使丰富的NMC阴极对抗界面不稳定性.
该处理优化了阴极表面,最大限度地减少了不可逆转的气体演变,并提高了电化学性能.
这种方法为提高高压离子电池的安全性和耐用性提供了可行的解决方案.

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