Platform Technology Lab and ‡Energy Lab, Samsung Advanced Institute of Technology , 130 Samsung-ro, Suwon, Gyeonggi-do 16678, Republic of Korea.
ACS Appl Mater Interfaces. 2017 May 31;9(21):17822-17834. doi: 10.1021/acsami.7b00260. Epub 2017 May 18.
Ni-rich layered oxides are attractive materials owing to their potentially high capacity for cathode applications. However, when used as cathodes in Li-ion batteries, they contain a large amount of Li residues, which degrade the electrochemical properties because they are the source of gas generation inside the battery. Here, we propose a computational approach to designing optimal coating materials that prevent gas evolution by removing residual Li from the surface of the battery cathode. To discover promising coating materials, the reactions of 16 metal phosphates (MPs) and 45 metal oxides (MOs) with the Li residues, LiOH, and LiCO are examined within a thermodynamic framework. A materials database is constructed according to density functional theory using a hybrid functional, and the reaction products are obtained according to the phases in thermodynamic equilibrium in the phase diagram. In addition, the gravimetric efficiency is calculated to identify coating materials that can eliminate Li residues with a minimal weight of the coating material. Overall, more MP and MO materials react with LiOH than with LiCO. Specifically, MPs exhibit better reactivity to both Li residues, whereas MOs react more with LiOH. The reaction products, such as Li-containing phosphates or oxides, are also obtained to identify the phases on the surface of a cathode after coating. On the basis of the Pareto-front analysis, PO could be an optimal material for the reaction with both Li residuals. Finally, the reactivity of the coating materials containing 3d/4d transition metal elements is better than that of materials containing other types of elements.
富镍层状氧化物因其作为阴极应用的高容量潜力而备受关注。然而，当将其用作锂离子电池的阴极时，其中含有大量的 Li 残留，这会降低电化学性能，因为它们是电池内部产生气体的来源。在这里，我们提出了一种计算方法来设计最佳的涂层材料，通过从电池阴极表面去除残留 Li 来防止气体逸出。为了发现有前途的涂层材料，我们在热力学框架内研究了 16 种金属磷酸盐 (MP) 和 45 种金属氧化物 (MO) 与 Li 残留、LiOH 和 LiCO 的反应。根据密度泛函理论使用混合泛函构建了一个材料数据库，并根据相图中热力学平衡的相获得反应产物。此外，还计算了重量效率以确定可以用最小的涂层材料重量去除 Li 残留的涂层材料。总的来说，与 LiCO 相比，更多的 MP 和 MO 材料与 LiOH 反应。具体而言，MP 对两种 Li 残留都表现出更好的反应性，而 MO 则与 LiOH 反应更剧烈。还获得了反应产物，例如含 Li 的磷酸盐或氧化物，以识别涂覆后阴极表面的相。基于帕累托前沿分析，PO 可能是与两种 Li 残留反应的最佳材料。最后，含 3d/4d 过渡金属元素的涂层材料的反应性优于含其他类型元素的材料。
