Vásquez F A, Rosero-Navarro N C, Miura A, Jalem R, Goto Y, Nagao M, Tateyama Y, Tadanaga K, Calderón J A
CIDEMAT, Universidad de Antioquia, Street 70# 52-21, Medellín 050010, Colombia.
Division of Applied Chemistry, Faculty of Engineering, Hokkaido University, Sapporo 060-8628, Japan.
ACS Appl Mater Interfaces. 2021 Mar 31;13(12):14056-14067. doi: 10.1021/acsami.0c17886. Epub 2021 Mar 16.
The development of more sustainable societies has become an urgent goal worldwide. Electrical batteries are currently seen as one of the most important energy storage technologies for the development of decarbonized societies. However, many lithium-ion battery manufacturers currently utilize cobalt, a toxic and hazardous mineral, in their batteries. Lithium-deficient manganese nickel oxide spinels are considered promising candidates owing to their high potential and environmental friendliness. Their electrochemical performance highly depends on their average and local structures, such as phase purities, lattice parameters, and cation sites. Thus, a synthesis protocol should be designed to control these structural parameters to improve their electrochemical performance. In this study, we controlled the average and local structures of LiMnNiO spinels obtained by co-precipitation by optimizing their cooling rates. High-resolution techniques, including transmission electron microscopy, synchrotron X-ray diffraction, and Auger-composition analysis combined with density functional theory calculations, X-ray absorption spectroscopy, and electrochemical analysis, were used to understand the average and local structural variations and their effects on the electrochemical properties. As a result, the control of oxygen diffusion at different cooling rates can promote the rearrangement of the structure, resulting in a cation-disordered spinel with minimal variations in lattice parameters and composition. Excellent electrochemical properties were noted in the cation-disordered spinel with high crystallinity and a slightly oxygen-rich surface produced via optimized cooling rates.
发展更具可持续性的社会已成为全球紧迫目标。目前，电池被视为脱碳社会发展中最重要的储能技术之一。然而，许多锂离子电池制造商目前在其电池中使用钴这种有毒有害矿物。锂缺陷型锰镍氧化物尖晶石因其高潜力和环境友好性而被视为有前景的候选材料。它们的电化学性能高度依赖于其平均结构和局部结构，如相纯度、晶格参数和阳离子位点。因此，应设计一种合成方案来控制这些结构参数，以改善其电化学性能。在本研究中，我们通过优化冷却速率来控制共沉淀法制备的LiMnNiO尖晶石的平均结构和局部结构。使用了包括透射电子显微镜、同步辐射X射线衍射以及俄歇成分分析等高分辨率技术，并结合密度泛函理论计算、X射线吸收光谱和电化学分析，来了解平均结构和局部结构的变化及其对电化学性能的影响。结果表明，在不同冷却速率下控制氧扩散可促进结构重排，从而得到晶格参数和组成变化最小的阳离子无序尖晶石。通过优化冷却速率制备出的具有高结晶度和略富氧表面的阳离子无序尖晶石具有优异的电化学性能。
