A new universal force-field for the Li2S-P2S5 system
A new universal force-field for the Li2S-P2S5 system
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DOI：
10.1039/d1cp05393k
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发表时间：
2022-01-07
影响因子：
3.3
通讯作者：
Taniguchi, Taketoshi
中科院分区：
文献类型：
--
作者：
Ariga, Shunsuke;Ohkubo, Takahiro;Taniguchi, Taketoshi
硫代磷酸锂电解质是一种很有应用前景的全固态电池材料。用从头算分子动力学（AIMD）方法研究了单晶和玻璃态化合物的离子导电机制。然而，真实的材料的复杂性（例如，具有晶界和多相玻璃陶瓷的材料）导致AIMD模拟具有高计算成本。为了克服这种计算限制，我们开发了一种新的原子间势的经典分子动力学（CMD）模拟的锂固态电解质。训练数据集由代表性硫化物电解质（β-Li 3 PS4、γ-Li 3 PS4、Li 4P 2S 6、Li 7 P3 S11和Li 7 PS 6晶体以及70 Li（2）S-30 P（2）S（5）玻璃）生成。使用II类和Stillinger-Weber势的函数形式，通过最小化CMD和AIMD结果之间的原子力、应力和势能差异来优化所有参数。随后的验证表明，优化的参数可以再现Li+的动力学以及晶体和玻璃态材料的结构。Li 7 P3 S11晶体的离子电导率约为等化学计量70 Li（2）S-30 P（2）S（5）玻璃的5倍，表明使用开发的力场进行的CMD模拟准确地再现了AIMD中Li 7 P3 S11的有效导电路径。所开发的力场参数使得在CMD框架中模拟包括非晶-结晶界面和多相玻璃陶瓷的复杂材料成为可能。
Lithium thiophosphate electrolyte is a promising material for application in all-solid-state batteries. Ab initio molecular dynamics (AIMD) simulations have been used to investigate the ion conduction mechanisms in single-crystalline and glassy compounds. However, the complexity of real materials (e.g., materials with grain boundaries and multiphase glass-ceramics) causes AIMD simulations to have high computational cost. To overcome this computational limitation, we developed a new interatomic potential for classical molecular dynamics (CMD) simulations of Li solid-state electrolytes. The training datasets were generated from representative sulfide electrolytes (beta-Li3PS4, gamma-Li3PS4, Li4P2S6, Li7P3S11, and Li7PS6 crystals and 70Li(2)S-30P(2)S(5) glass). Using the functional forms of the Class II and Stillinger-Weber potentials, all parameters were optimized by minimizing the differences in forces on atoms, stresses, and potential energies between the CMD and AIMD results. Subsequent validation showed that the optimized parameters can reproduce the dynamics of Li+ as well as the structures of the crystalline and glassy materials. The ionic conductivity of Li7P3S11 crystal was approximately five times that of the isostoichiometric 70Li(2)S-30P(2)S(5) glass, indicating that CMD simulations using the developed force-field accurately reproduced the effective conduction path in Li7P3S11 from AIMD. The developed force-field parameters make it possible to simulate complex materials including amorphous-crystalline interfaces and multiphase glass-ceramics in the CMD framework.