Ionic Transport in Natural Phyllosilicates

Electrochemical ion-insertion in anisotropic solids is conventionally important for high-performance energy harvesting systems and understanding the underlying coupled ion-electron transfer mechanism, transportation of guest ions, and the redox of these anisotropic solids are of utmost importance for the engineering of these energy harvesting systems [1]. Natural clay minerals (e.g., in the class of phyllosilicates) show great promise as anisotropic host solids for these applications but are still poorly understood and a clear atomistic picture of the underlying mechanisms is still missing. Especially, the direct relationship between the efficiency of energy conversion (e.g., from the salinity gradient between the sea water and saline water) and the layer charge of clay minerals is insufficient to design the clay-based energy materials, which can play a critical role in maximizing efficiency. In this work, using vermiculite as an archetypical but promising layered host material [2], we construct different supercell models with varying 3+/4+ ion ratios in the tetrahedral layers and examine the role of interlayer surface charges on ionic transport via first-principles derived machine-learning potential enabled molecular dynamics simulations [3]. Through this study, we will provide a first-step understanding of the underlying atomistic design rules in natural clay materials for energy applications, which has the potential to establish itself as design rules for efficient vermiculite-based energy material.<br/><br/>[1] S. Kim, S. J. Choi, K. Zhao, H. Yang, G. Gobbi, S. Zhang, and J. Li, <i>Nat. Commun.</i> <b>7</b>, 10146 (2016)<br/>[2] L. Cao, H. Wu, C. Fan, Z. Zhang, B. Shi, P. Yang, M. Qiu, N. A. Kahn, and Z. Jiang,<i> J. Mater. Chem. A</i> <b>9</b>, 14576 (2021)<br/>[3] A. P. Bartók, M. C. Payne, R. Kondor, and G. Csányi, <i>Phys. Rev. Lett.</i> <b>104</b>, 136403 (2010)