Defect chemistry and ion transport in low-dimensional-networked Li-rich anti-perovskites as solid electrolytes for solid-state batteries
Defect chemistry and ion transport in low-dimensional-networked Li-rich anti-perovskites as solid electrolytes for solid-state batteries
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低维网状富锂反钙钛矿固体电解质的缺陷化学和离子输运
DOI：
10.1039/d3ya00075c
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发表时间：
2023-05-18
期刊：
影响因子：
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通讯作者：
Dawson, James A.
中科院分区：
文献类型：
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作者：
Dutra, Ana Carolina Coutinho;Rudman, George E.;Dawson, James A.
固态电池因其巨大的潜在优势而备受关注，包括能量密度的提高和安全性的增强。这项技术的核心可以在其固体电解质中找到，因此它的进步本质上与发现和理解新型固体电解质材料有关。近年来，富锂反钙钛矿由于具有高的离子导电性、结构的多功能性和对锂金属的稳定性而成为很有前途的固体电解质候选材料。本文通过原子模拟研究了LixOxx-2(X=Cl或Br3-6)反钙钛矿结构中的缺陷形成、稳定性、锂离子输运和氟掺杂的能量学。我们的计算表明，这些材料通常以Li-卤化物肖特基缺陷对为主的本征缺陷。我们发现，与LixOBrx-2系列中的等价结构相比，LixOClx-2系列中的缺陷形成通常在能量上更有利。此外，我们的分子动力学模拟揭示了锂离子动力学与这些材料中的维度之间的强烈关系，即随着维度的降低，锂离子的扩散增加，活化能降低。观察到低维网络结构的Br基材料的Li离子扩散增强(300K时Li5OBr3和Li6OBr4分别为4.81×10(-9)和6.08×10(-9)cm(-2)S(-1))，而Cl基材料(Li5OCl3和Li6OCl4在300K时分别为9.85×10(-10)和2.06×10(-9)cm(-2)S(-1))，说明晶格极化率在这些软而不稳定的材料中的重要性。在F掺杂的LixOxx-2中观察到锂离子扩散的显著减少和活化能的增加进一步证明了这一点。这项工作揭示了反钙钛矿固体电解质中的缺陷、锂离子动力学和维度之间的关系。从3D到0D，随着维度的降低，缺陷浓度和离子输运显著增加。
Solid-state batteries are attracting significant attention due to their plethora of potential advantages, including energy density gains and safety enhancements. The heart of this technology can be found in its solid electrolytes and thus its progress is intrinsically attached to the discovery and understanding of novel solid electrolyte materials. In recent years, Li-rich anti-perovskites have become promising solid electrolyte candidates as they combine high ionic conductivity, structural versatility and stability against Li metal. Here, the energetics of defect formation, stability, Li-ion transport and fluorine doping in a range of LixOXx-2 (X = Cl or Br; x = 3-6) anti-perovskites with zero- to three-dimensional-networked structures are explored via atomistic simulations. Our calculations show that these materials generally present Li-halide Schottky defect pairs as the dominant native defects. We find that defect formation is generally energetically more favourable in the LixOClx-2 series compared to the equivalent structures in the LixOBrx-2 set. Additionally, our molecular dynamics simulations reveal the strong relationship between Li-ion dynamics and dimensionality in these materials, namely, increasing Li-ion diffusion and decreasing activation energy with reduced dimensionality. Enhanced Li-ion diffusion is observed for the low-dimensional-networked Br-based materials (4.81 x 10(-9) and 6.08 x 10(-9) cm(2) s(-1) for Li5OBr3 and Li6OBr4 at 300 K, respectively) compared to their Cl-based counterparts (9.85 x 10(-10) and 2.06 x 10(-9) cm(2) s(-1) for Li5OCl3 and Li6OCl4 at 300 K, respectively), illustrating the importance of lattice polarisability in these soft and unstable materials. This is further exemplified by the significant reduction in Li-ion diffusion and increase in activation energies observed in F-doped LixOXx-2.This work reveals the relationships between defects, Li-ion dynamics and dimensionality in anti-perovskite solid electrolytes. Significant increases in defect concentrations and ion transport are observed with decreasing dimensionality from 3D to 0D.