Silicon is a promising active material for the anode in lithium-ion batteries (LIB), since it enables much higher energy densities than graphite – the state-of the art material for LIB-anodes. However, the utilization of silicon brings many challenges, which originate mainly from the enormous volume change between the lithiated and delithiated state (300%). One of the consequences is a constant re-formation of the solid electrolyte interphase (SEI), which is accompanied by a loss of active Li+. This leads to a strong capacity fading, which results in a very short cycle life. [1]
An efficient and economical approach to tackle these problems is the utilization of additives in the electrolyte. Additives are small molecules or salts that decompose during the first cycles of the battery life resulting in an interphase with modified composition and thereby an improved SEI. Depending on the additive the SEI can reduce the impedance of the cell and help to maintain the structural stability of the anode. [2]
In this work a new additive was synthesized and electrochemically tested with a silicon-based anode. Improvements regarding capacity retention were found in full-cell measurements. Hence, after 100 cycles the additive showed a 94 % increased capacity retention and an increase in cycle live before reaching SoH80 of 21 %. Scanning electron microscopy (SEM) images of lithiated and delithiated electrodes show smaller cracks on the surface and a smaller increase in electrode thickness when using the additive compared to the electrode treated with the base electrolyte. This phenomenon shows an increased cohesive force of the new formed SEI mitigating the effects of the enormous volume expansion in the electrode. At high magnification new surface materials on the electrode components could be found.

[1] Zuo X., Zhu J., Müller-Buschbaum P. & Cheng Y.-J. Silicon based lithium-ion battery anodes: A chronicle perspective review. Nano Energy. 31, 213-143; 10.1016/j.nanoen.2016.11.013 (2017)
[2] Eshetu, G.G., Zhang, H., Judez, X. et al. Production of high-energy Li-ion batteries comprising silicon-containing anodes and insertion-type cathodes. Nat Commun 12, 5459; 10.1038/s41467-021-25334-8 (2021)