Lithium-sulfur (Li-S) batteries have gained great interest in recent years as possible substitutes for lithium-ion batteries because of their high theoretical capacity. However, these batteries present two main drawbacks: the polysulfide shuttle and the use of highly reactive lithium metal as the anode, which both lead to rapid capacity fading as cycling progresses. Pre-lithiated silicon anode has been considered as a superior alternative to the lithium metal to markedly check capacity fading and safety of the resulting cell. This is due to the fact that pre-lithiated silicon is much less reactive towards both electrolytes and polysulfide intermediates while providing comparable theoretical capacity (3580 mAh/g<sub>Si</sub>). However, the design of silicon anodes is still challenging due its very high volume expansion/contraction (~300%) during lithiation/delithiation cycles. In this study, we have synthesized several polypyrrole (PPy)-coated silicon anodes (Si@void@PPy) with adequate void spaces so that the anode structure remains intact during cycling. PPy has been selected because of its very high electrical conductivity compared to porous carbon and ease of synthesis at room temperature, thus preventing oxidation of silicon, which is very common in high temperature synthesis of Si@C. In addition to thorough characterization of these new anode materials, we will present the efficacy of using pre-lithiated silicon anode in Li-S cells by comparing the cycling data with traditional Li-S cells.

Synthesis and characterization of novel polypyrrole-coated silicon anodes for Li-batteries

ACS Spring 2022

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