Dataset for: Predicting stable lithium iron oxysulphides for battery cathodes

Cathode materials that have high specific energies and low manufacturing costs are vital for the scaling up of lithium-ion batteries (LIBs) as energy storage solutions. Fe-based intercalation cathodes are highly attractive because of the low-cost and the abundance of the raw materials. However, existing Fe-based materials, such as LiFePO4 suffer from low capacity due to the large size of the polyanions. Turning to mixed anion systems can be a promising strategy to achieve higher specific capacity. Recently, anti-perovskite structured oxysulphide Li2FeSO has been synthesised and reported to be electrochemically active.
In this work, we perform an extensive computational search for iron-based oxysulphides using ab initio random structure searching (AIRSS). By performing an unbiased sampling of the Li-Fe-S-O chemical space, several new oxysulphide phases have been discovered which are predicted to be less than 50 meV/atom from the convex hull and potentially accessible for synthesis.
Among the predicted phases, two anti-Ruddlesden-Popper structured materials  Li2Fe2S2O  and  Li4Fe3S3O2
have been found to be attractive as they have high theoretical capacities with calculated average voltages 2.9 V and 2.5 V respectively. With band gaps as low as about 2.0 eV, they are expected to exhibit good electronic conductivities.
By performing nudged-elastic band calculations, we show that the Li-ion transport in these materials takes place by hopping between the nearest neighbouring sites with low activation barriers between 0.3 eV and 0.5 eV.
The richness of new materials yet to be synthesised in the Li-Fe-S-O phase field illustrate the great opportunity in these mixed anion systems for energy storage applications and beyond.

The dataset includes the structure searching results and outputs of further property calculations. The analysis codes are also included as Jupyter Notebooks.

Also hosted on GitHub.

Preprint hosted on ChemRxiv.

高比能量且制造成本低廉的正极材料，对于锂离子电池（LIBs）作为储能解决方案的规模化应用至关重要。铁基插层正极材料因原料成本低廉且储量丰富而极具吸引力。然而，现有铁基材料（如磷酸铁锂）因聚阴离子体积较大而存在容量偏低的问题。转向混合阴离子体系或是实现更高比容量的可行策略。近期，反钙钛矿结构氧硫化物Li₂FeSO已被成功合成，并被报道具有电化学活性。

本研究通过从头算随机结构搜索（AIRSS）对铁基氧硫化物开展了系统性的计算筛选。通过对Li-Fe-S-O化学空间进行无偏采样，我们发现了多个新型氧硫化物相，经预测其与形成焓凸包的能量差低于50 meV/原子，具备可合成的潜力。

在预测得到的物相中，两种反鲁德尔斯登-波普尔结构材料Li₂Fe₂S₂O和Li₄Fe₃S₃O₂颇具研究价值：二者均具有较高的理论比容量，计算得到的平均放电电压分别为2.9 V和2.5 V；其带隙低至约2.0 eV，预计具备良好的电子导电性。

通过爬坡弹性带计算，我们证实此类材料中的锂离子传输通过最近邻位点跃迁实现，其活化能垒介于0.3 eV至0.5 eV之间。

Li-Fe-S-O相区中尚有大量未被合成的新型材料，这表明此类混合阴离子体系在储能及其他应用领域中存在巨大的发展机遇。

本数据集包含结构搜索结果及后续物性计算的输出结果，配套的分析代码以Jupyter笔记本形式提供。

本数据集同时托管于GitHub平台。

预印本发布于ChemRxiv平台。