Apples to Apples: Shift from Mass Ratio to Additive Molecules per Electrode Area to Optimize Li-Ion Batteries

Electrolyte additives in liquid electrolyte batteries can trigger the formation of a protective interphase (SEI) atthe electrodes that aims to suppress side reactions at the electrodes. Studies of varying amounts of additives have been done over the last years, providing a comprehensive understanding of the impact of the electrolyte formulation on the lifetime of the cells. However, these studies mostly focus on the variation of the mass fraction of additive in the electrolyte while disregarding the ratio (radd) of the additive's amount of substance (nadd) to the electrode area (Aelectrode). Herein we utilize our extremely accurate automatic battery assembly system (AUTOBASS) to vary electrode area and amount of substance of the additive. The data provides strong evidence that reporting the mass ratios of electrolyte components is insufficient and the mol of additive relative to the electrodes' area should be reported. Herein, the two most utilized additives, namely fluoroethylene carbonate (FEC) and vinylene carbonate (VC) were studied. Each additive was varied from 0.1 wt.-% - 3.0 wt.-% for VC, and 5 wt.-% - 15 wt.-% for FEC for two mass loadings of 1 mAh/cm2 and 3 mAh/cm2. To engage the community to find better descriptors, such as the proposed radd, we publish the dataset alongside this manuscript. Codes and mechanical parts of the project: AutoBASS 2.0: GitHub - Helge-Stein-Group/AutoBASS at AutoBASS_2.0液态电解液电池中的电解液添加剂可在电极表面诱导形成保护性界面（SEI，固体电解质界面相），以抑制电极处的副反应。过往数年间，学界已针对不同添加剂用量开展大量研究，对电解液配方对电池循环寿命的影响形成了系统全面的认知。然而此类研究大多聚焦于电解液中添加剂的质量分数变化，却忽略了添加剂的物质的量（nadd）与电极面积（Aelectrode）的比值（radd）。 本研究采用精度极高的自动化电池组装系统（AUTOBASS），实现电极面积与添加剂物质的量的灵活调控。本数据集有力证明，仅报道电解液组分的质量比存在明显不足，需同时报道添加剂相对于电极面积的物质的量。本研究针对两种最常用的添加剂——氟代碳酸乙烯酯（FEC）与碳酸亚乙烯酯（VC）展开系统探究。针对1 mAh/cm²与3 mAh/cm²两种面容量负载工况，碳酸亚乙烯酯（VC）的添加量范围为0.1 wt.%至3.0 wt.%，氟代碳酸乙烯酯（FEC）的添加量范围则为5 wt.%至15 wt.%。为推动学界探索更优的性能表征参数（如本文提出的radd），我们随本学术稿件公开本数据集。 本项目的代码与机械部件： AutoBASS 2.0：GitHub - Helge-Stein-Group/AutoBASS at AutoBASS_2.0