In-situ Complementary XRD- and PDF-CT Investigation of NMC811 Heterogeneous Degradation

Nickel-rich Li(NiMnCo)O2 (NMC811) have emerged as the most promising successor to LiCoO2 cells, and could potentially facilitate ubiquitous adoption of lithium(Li)-ion batteries in mobile and transport devices. However, NMC811 suffers from instability at high voltages which contributes to significant capacity loss, with the underlying degradation mechanism being poorly understood. We propose to use the capabilities of ID15-A to perform a complete in-situ structural study employing X-ray diffraction (XRD) and pair-distribution-function (PDF) computed tomography (CT) to elucidate a full understanding of the heterogenous structural changes throughout the electrode. During cycling of the cells, we aim to obtain spatially-resolved data to understand how local nano-crystalline phenomena propagate the onset of inactive phases, and how the thickness of the electrode promotes regional chemical environments facilitating inhomogeneous cell activity with complimentary tomographic techniques.

富镍锂镍锰钴氧化物（Li(NiMnCo)O₂，简称NMC811）已成为钴酸锂（LiCoO₂）电池最具前景的替代材料，有望推动锂离子电池（lithium-ion battery）在移动设备和运输工具中的广泛应用。然而，NMC811在高电压下存在不稳定性，导致显著的容量衰减，其潜在的降解机制尚未被充分理解。我们拟利用ID15-A的能力，通过X射线衍射（XRD）、对分布函数（PDF）和计算机断层扫描（CT）技术开展全面的原位结构研究，以充分阐明电极内部异质结构变化的全貌。在电池循环过程中，我们拟通过互补的断层扫描技术获取空间分辨数据，以了解局部纳米晶现象如何引发惰性相的产生，以及电极厚度如何促进形成导致电池活性不均匀的区域化学环境。