Resolving Chemical and Spatial Heterogeneities at Complex Electrochemical Interfaces in Li-Ion Batteries
Resolving Chemical and Spatial Heterogeneities at Complex Electrochemical Interfaces in Li-Ion Batteries
复制标题
解决锂离子电池中复杂电化学界面的化学和空间异质性
DOI：
10.1021/acs.chemmater.1c03185
复制
发表时间：
2022
影响因子：
8.6
通讯作者：
Marbella, Lauren E.
中科院分区：
文献类型：
--
作者：
Hestenes, Julia C.;May, Richard;Sadowski, Jerzy T.;Munich, Naiara;Marbella, Lauren E.
富镍过渡金属氧化物的高比容量已经引起了人们对提高锂离子电池（LIB）能量密度的极大兴趣。尽管这些材料的潜力，富Ni阴极遭受界面不稳定性，导致活性材料表面的晶体重排以及在电化学循环期间在复合材料表面上形成阴极电解质界面（CEI）层。虽然晶体结构的变化可以用基于衍射的方法检测到，但探测无序、异质CEI层的化学性质是具有挑战性的。在这项工作中，我们使用的组合ofex situssolid-state核磁共振（SSNMR）光谱和X射线光电子显微镜（XPEEM）提供化学和空间信息，在纳米尺度上，对沉积在LiNi0.8Mn0.1Co0.1O2（NMC 811）复合阴极薄膜上的CEI。XPEEM元素图提供了对电解质分解产物的横向排列的深入了解，这些电解质分解产物包括CEI和顺磁相互作用（用电子顺磁共振（EPR）和弛豫测量进行评估），在13 C SSNMR中提供了关于CEI从NMC 811颗粒向外的径向排列的信息。使用这种方法，我们发现LiF，Li 2CO 3和含羧基的结构直接附加到NMC 811活性颗粒上，而在原位1H和19 F溶液NMR实验期间检测到的可溶性物质（例如，碳酸烷基酯、HF和乙烯基化合物）随机沉积在复合材料表面上。我们表明，结合situssolution NMR内的ofex situSSNMR和XPEEM的组合方法，允许空间分辨，顺磁性表面的分子水平表征和新的见解电解质氧化机制在多孔电极膜。
The high specific capacities of Ni-rich transition-metal oxides have garnered immense interest for improving the energy density of Li-ion batteries (LIBs). Despite the potential of these materials, Ni-rich cathodes suffer from interfacial instabilities that lead to crystallographic rearrangement of the active material surface as well as the formation of a cathode electrolyte interphase (CEI) layer on the composite surface during electrochemical cycling. While changes in crystallographic structure can be detected with diffraction-based methods, probing the chemistry of the disordered, heterogeneous CEI layer is challenging. In this work, we use a combination ofex situsolid-state nuclear magnetic resonance (SSNMR) spectroscopy and X-ray photoemission electron microscopy (XPEEM) to provide chemical and spatial information, on the nanometer length scale, on the CEI deposited on LiNi0.8Mn0.1Co0.1O2(NMC811) composite cathode films. XPEEM elemental maps offer insight into the lateral arrangement of the electrolyte decomposition products that comprise the CEI and paramagnetic interactions (assessed with electron paramagnetic resonance (EPR) and relaxation measurements) in13C SSNMR provide information on the radial arrangement of the CEI from the NMC811 particles outward. Using this approach, we find that LiF, Li2CO3, and carboxy-containing structures are directly appended to NMC811 active particles, whereas soluble species detected duringin situ1H and19F solution NMR experiments (e.g., alkyl carbonates, HF, and vinyl compounds) are randomly deposited on the composite surface. We show that the combined approach ofex situSSNMR and XPEEM, in conjunction within situsolution NMR, allows spatially resolved, molecular-level characterization of paramagnetic surfaces and new insights into electrolyte oxidation mechanisms in porous electrode films.