Theoretical study on stability and ion transport property with halide doping of Na3SbS4 electrolyte for all-solid-state batteries
Theoretical study on stability and ion transport property with halide doping of Na3SbS4 electrolyte for all-solid-state batteries
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DOI：
10.1039/d1ta07292g
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发表时间：
2021-12-01
影响因子：
11.9
通讯作者：
Tateyama, Yoshitaka
中科院分区：
文献类型：
--
作者：
Jalem, Randy;Gao, Bo;Tateyama, Yoshitaka
全固态钠离子电池（ASS-NIB）是一种新型电池，具有替代传统全固态锂离子电池的潜力。在此，我们将重点放在Na3SbS4（一种被报道用于ASS-NIB应用的候选固体电解质）上，并进行了全面的理论研究，主要基于密度泛函理论计算，以评估（电）化学稳定性、缺陷化学和Na离子输运性质。计算结果表明，当与层状阴极化合物（如NaCrO2）接触时，Na3SbS4中的硫倾向于跨界面迁移，导致界面原子重排、界面无序和/或分解。该材料还预测在还原电压条件下（0 V vs. Na+/Na）会分解，与实验结果一致。应力和电子密度分布的动力学建模表明，在典型电沉积表面粗糙度下，Na3SbS4与Na金属阳极之间的界面会导致枝晶的萌生和生长。除了控制Na空位浓度外，通过DFT分子动力学（MD）计算预测了卤化物在S位点的掺杂会直接影响Na+离子的活化能。这可以归因于Na位点到位点通路瓶颈的大小调制。Cl和Br卤化物掺杂剂都具有较低的DFT-MD Na+离子活化能（在4% Na空位时类似于0.1 eV），被认为有希望优化电导率。热力学分析表明，影响Na3SbS4最终电导率的可能因素是：二次相和固有缺陷。总的来说，我们的发现为固体电解质的合理设计提供了有价值的见解。
All-solid-state Na ion battery (ASS-NIB) is a new class of battery which is a potential alternative to the conventional all-solid-state Li ion battery. Herein, we focused on Na3SbS4, a reported candidate solid electrolyte for ASS-NIB application, and performed a comprehensive theoretical study, primarily based on density functional theory calculations, to evaluate (electro)chemical stability, defect chemistry, and Na ion transport property. The calculated results reveal that when in contact with a layered cathode compound (e.g., NaCrO2), sulfur in Na3SbS4 tends to migrate across the interface, leading to interface atomic rearrangement, interface disordering and/or decomposition. The material is also predicted to decompose under reductive voltage conditions (0 V vs. Na+/Na), in agreement with experiment. Kinetic modeling for stresses and electron density distribution showed that the interface between Na3SbS4 and Na metal anode under typical electrodeposition surface roughness would lead to dendrite initiation and growth. Aside from controlling Na vacancy concentration, halide doping at the S site was predicted by DFT molecular dynamics (MD) calculations to directly affect the Na+ ion activation energy. This can be ascribed to the size modulation of the Na site-to-site pathway bottleneck. Cl and Br halide dopants are both determined to be promising for conductivity optimization, with low DFT-MD Na+ ion activation energy (similar to 0.1 eV at 4% Na vacancy). Thermodynamic analysis shows the possible factors that can influence the final conductivity of Na3SbS4: secondary phases and intrinsic defects. Overall, our findings offer valuable insights for the rational design of solid electrolytes.