Electrochemical Performance and Stability of $Li_7 Si_2 S_7 I$ Solid Electrolytes in Solid-State Battery Cathode Composites

Le résumé fourni par la source

The development of solid electrolytes (SEs) for high-performance solid-state batteries (SSBs) requires not only favorable electrochemical stability but also interfacial compatibility with diverse cathode chemistries. In this study, we systematically benchmark recently discovered $Li_7Si_2S_7I$ against the well-established argyrodite $Li_{5.5}PS_{4.5}Cl_{1.5}$ as an SE in composite cathodes. Despite exhibiting comparable oxidative stability, $Li_7Si_2S_7I$ demonstrates markedly different behaviors depending on the cathode chemistry. In composite cathodes with uncoated $LiNi_{0.83}Co_{0.11}Mn_{0.06}O_2$ as the cathode active material and $Li_7Si_2S_7I$ as the electrolyte, rapid degradation occurs, with capacity retention dropping to 5% after 30 cycles, driven by fast degradation kinetics and interfacial instability toward the formation of $SiO_x$ species as a thermodynamic sink. In contrast, sulfur–carbon–$Li_7Si_2S_7I$ composite cathodes show good performance in half-cells, comparable to that of the argyrodite benchmark. The reversible oxidative redox processes of $Li_7Si_2S_7I$ in sulfur-based systems highlight its promise for Li–S and other oxygen-free battery chemistries. Overall, this work emphasizes the importance of a holistic approach to SE evaluation, integrating chemical and electrochemical stability with degradation kinetics, to inform the rational design of next-generation SSB materials.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.