Amphiphilic surfactants: A mechanistic insight into the enhancement of silicon anodes in lithium-ion batteries

Abstract

This study effectively enhances the structural stability and electrochemical performance of silicon anodes by incorporating betaine into the silicon anode material. After the introduction of betaine, a coating layer is formed on the surface of nano Si, which buffers the expansion and contraction of silicon particles, reducing mechanical stress caused by volume changes. No significant cracking and fragmentation were observed after 200 cycles. Concurrently, the incorporation of betaine significantly improved cycling stability, rendering the alloying and dealloying processes more stable, and mitigating the occurrence of side reactions, thereby reducing polarization during cycling. The addition of betaine also effectively improved the transfer capabilities of lithium ions and electrons, enhancing reaction kinetics. After the modification with betaine, the Si-LiFePO₄ (LFP) battery maintained over 80 % of its capacity after 500 cycles at 2C, while the pristine Si exhibited a specific capacity of only 3.11 mAh g^-1 by the 10th cycle. This research provides a new analytical perspective on the application of surfactants in silicon anode materials and offers insights for the development of advanced lithium-ion batteries with superior performance.