Department of Materials Science and Engineering , Northwestern University , 2220 Campus Drive , Evanston , Illinois 60208 , United States.
Chemical Sciences and Engineering Division , Argonne National Laboratory , 9700 S. Cass Avenue , Argonne , Illinois 60439 , United States.
ACS Appl Mater Interfaces. 2018 Apr 25;10(16):13479-13490. doi: 10.1021/acsami.8b00394. Epub 2018 Apr 12.
Embedding a lithiated cobalt oxide spinel (LiCoO, or LiCoO) component or a nickel-substituted LiCoNi O analogue in structurally integrated cathodes such as xLiMnO·(1- x)LiM'O (M' = Ni/Co/Mn) has been recently proposed as an approach to advance the performance of lithium-ion batteries. Here, we first revisit the phase stability and electrochemical performance of LiCoO synthesized at different temperatures using density functional theory calculations. Consistent with previous studies, we find that the occurrence of low- and high-temperature structures (i.e., cubic lithiated spinel LT-LiCoO; or LiCoO ( Fd3̅ m) vs trigonal-layered HT-LiCoO ( R3̅ m), respectively) can be explained by a small difference in the free energy between these two compounds. Additionally, the observed voltage profile of a Li/LiCoO cell for both cubic and trigonal phases of LiCoO, as well as the migration barrier for lithium diffusion from an octahedral (O) site to a tetrahedral site (T) in Fd3̅ m LT-LiCoO, has been calculated to help understand the complex electrochemical charge/discharge processes. A search of LiCo MO lithiated spinel (M = Ni or Mn) structures and compositions is conducted to extend the exploration of the chemical space of Li-Co-Mn-Ni-O electrode materials. We predict a new lithiated spinel material, LiNiCoO ( Fd3̅ m), with a composition close to that of commercial, layered LiNiCoAlO, which may have the potential for exploitation in structurally integrated, layered spinel cathodes for next-generation lithium-ion batteries.
将嵌锂钴氧化物尖晶石（LiCoO，或 LiCoO）组件或镍取代的 LiCoNiO 类似物嵌入结构整合的阴极中，例如 xLiMnO·(1- x)LiM'O（M'=Ni/Co/Mn），最近被提议作为提高锂离子电池性能的一种方法。在这里，我们首先使用密度泛函理论计算重新考察了在不同温度下合成的 LiCoO 的相稳定性和电化学性能。与之前的研究一致，我们发现低温和高温结构（即立方尖晶石 LT-LiCoO；或 LiCoO（Fd3̅m）与 HT-LiCoO（R3̅m））的出现可以用这两种化合物之间自由能的微小差异来解释。此外，还计算了 Li/LiCoO 电池中观察到的 LiCoO 立方相和三角相的电压曲线，以及从八面体（O）位置到 Fd3̅m LT-LiCoO 中的四面体位置（T）的锂离子扩散迁移势垒，以帮助理解复杂的电化学充放电过程。对 LiCoMO 嵌锂尖晶石（M=Ni 或 Mn）结构和组成进行了搜索，以扩展对 Li-Co-Mn-Ni-O 电极材料化学空间的探索。我们预测了一种新的嵌锂尖晶石材料 LiNiCoO（Fd3̅m），其组成接近商用层状 LiNiCoAlO，这可能有潜力用于下一代锂离子电池的结构整合层状尖晶石阴极。
