Achieving Unprecedent Coulombic Efficiency with Prelithiated Porous Si@C Anodes and Polymeric Electrolytes

As an alternative to lithium metal, this article employs porous silicon‐graphite (Si@C) composite anodes in combination with polymeric solid electrolytes made entirely of Poly(ethylene oxide) and (Lithium bis(trifluoromethanesulfonyl)imide), and LiFePO 4 composite cathodes. The low initial coulombic efficiency (ICE) of the full cells is improved via prelithiation of the anode. In fact, anodes with a prelithiation degree of 50% achieve the highest ICE reported in the literature (99.88%) up to date. However, these cells experience a faster capacity loss. The differential capacity plots reveal the different alloying and intercalation processes. The degree of anode prelithiation is responsible of sustaining the activity of the Fe 2+ / 3+ redox couple, which directly impacts the cell capacity and its retention. This Si‐solid‐state batterie. concept has the potential to revolutionize the transportation sector and bring us closer to a fully sustainable future.