Kang Joonhee, Han Byungchan
Department of Energy Systems Engineering, DGIST , Daegu 42988, Republic of Korea.
Department of Chemical and Biomolecular Engineering, Yonsei University , Seoul 03722, Republic of Korea.
J Phys Chem Lett. 2016 Jul 21;7(14):2671-5. doi: 10.1021/acs.jpclett.6b01050. Epub 2016 Jun 30.
Using first-principles density functional theory calculations and ab initio molecular dynamics (AIMD) simulations, we demonstrate the crystal structure of the Li7P2S8I (LPSI) and Li ionic conductivity at room temperature with its atomic-level mechanism. By successively applying three rigorous conceptual approaches, we identify that the LPSI has a similar symmetry class as Li10GeP2S12 (LGPS) material and estimate the Li ionic conductivity to be 0.3 mS cm(-1) with an activation energy of 0.20 eV, similar to the experimental value of 0.63 mS cm(-1). Iodine ions provide an additional path for Li ion diffusion, but a strong Li-I attractive interaction degrades the Li ionic transport. Calculated density of states (DOS) for LPSI indicate that electrochemical instability can be substantially improved by incorporating iodine at the Li metallic anode via forming a LiI compound. Our methods propose the computational design concept for a sulfide-based solid electrolyte with heteroatom doping for high-voltage Li ion batteries.
通过第一性原理密度泛函理论计算和从头算分子动力学（AIMD）模拟，我们展示了Li7P2S8I（LPSI）的晶体结构以及其在室温下的锂离子传导率及其原子水平的机制。通过依次应用三种严格的概念方法，我们确定LPSI与Li10GeP2S12（LGPS）材料具有相似的对称类，并估计锂离子传导率为0.3 mS cm(-1)，活化能为0.20 eV，与0.63 mS cm(-1)的实验值相似。碘离子为锂离子扩散提供了额外的路径，但强烈的Li-I吸引相互作用会降低锂离子传输。LPSI的计算态密度（DOS）表明，通过在锂金属阳极处通过形成LiI化合物掺入碘，可以显著改善电化学不稳定性。我们的方法提出了一种用于高压锂离子电池的具有杂原子掺杂的硫化物基固体电解质的计算设计概念。
