报告题目：一维橄榄石 FePO₄主体中的离子嵌入和离子交换 Ion-insertion and Ion-exchange in One-dimensional Olivine FePO₄ Hosts

报  告  人：严港斌

报告时间：2024年7月10日（下午）13点30分

报告地点：新能源大楼315会议室

报告摘要：

The lithium supply challenge predominantly stems from the limitations of existing mining techniques in accessing lithium sources with intricate chemistry and low concentrations. Electrochemical intercalation presents an avenue for extracting lithium from diluted water sources. However, during the extraction process, the co-intercalation of lithium and its primary competitor, sodium ions, occurs. The comprehensive understanding of how host materials respond to this co-intercalation process remains an ongoing pursuit. Moreover, despite the well-acknowledged potential for lithium extraction, the reported selectivity for lithium can exhibit considerable disparity. This discrepancy in selectivity, as observed with olivine-type FePO₄, can span nearly three orders of magnitude, potentially arising from the diverse particle forms adopted (e.g., sizes, morphology, dominant facets, etc.).

In this talk, using one-dimensional (1D) olivine iron phosphate (FePO₄) as a model host, I will first introduce the co-intercalation behavior of lithium and sodium ions and the control of lithium selectivity through intercalation kinetic manipulations. By combining computational and experimental investigations, we noticed that lithium- and sodium-rich phases tend to separate in the host. Exploiting this mechanism, I will discuss how the sodium-ion intercalation energy barrier can be increased by using partially filled 1D lithium channels, generated via non-equilibrium solid-solution lithium seeding or remnant lithium in the solid solution phases. Furthermore, the lithium selectivity enhancement during co-intercalation shows a strong correlation with the fractions of solid-solution phases with high lithium content (i.e., Li_xFePO₄ with 0.5 ≤ x < 1). Finally, I will delve into the impact of different structural forms of the host material. Specifically, I will discuss how these structural variations can influence particle kinetics and chemo-mechanical responses during Li-Na co-intercalation, ultimately affecting the preference for lithium intercalation.

锂供应挑战主要源于现有采矿技术在获取化学性质复杂且浓度较低的锂源方面的局限性。电化学插层为从稀释水源中提取锂提供了一种途径。然而，在提取过程中，锂和其主要竞争对手钠离子会共同嵌入。全面了解宿主材料如何响应这种共同嵌入过程仍是一项持续的追求。此外，尽管锂提取潜力众所周知，但报道的锂选择性可能存在相当大的差异。正如橄榄石型 FePO₄所观察到的，这种选择性差异可能跨越近三个数量级，这可能是由于采用的颗粒形式不同（例如尺寸、形态、主要方面等）。

在本次报告中，报告人将使用一维 (1D) 橄榄石磷酸铁 (FePO₄) 作为模型主体，首先介绍锂和钠离子的共插层行为以及通过插层动力学操控来控制锂选择性。通过结合计算和实验研究，我们注意到锂和钠富集相在主体中倾向于分离。利用这种机制，将讨论如何通过使用部分填充的 1D锂通道来增加钠离子插层能垒，这些通道是通过非平衡固溶体锂接种或固溶体相中的残留锂产生的。此外，共插层过程中锂选择性的增强与高锂含量的固溶体相的分数 (即 0.5 ≤ x < 1的 Li_xFePO₄) 表现出很强的相关性。最后，深入研究主体材料不同结构形式的影响。

报告人简介：严港斌，芝加哥大学Pritzker分子工程学院博士，本科毕业于苏州大学威尼斯人 。曾获美国材料研究学会Materials Research Society研究生金奖（2023 spring）。目前研究兴趣包括电化学锂提取，能源资源的合理循环利用以及电催化。相关成果发表于Nat. Commun., PNAS, ACS Catal.等杂志上。