Li-Si compound anodes enabling high-performance all-solid-state Li-ion batteries

초록

Silicon (Si) is an attractive high-capacity anode material for all-solid-state Li-ion batteries (ASSLIBs). However, significant volume change, low ionic/electronic conductivity, poor solid-electrolyte compatibility, and high stack pressure requirements limit its practical applications. To address these issues, we propose Li-Si compound anodes for ASSLIBs, selected based on formation energies predicted by density functional theory. Among the Li-Si compounds, Li7Si3 (Li2.33Si) exhibits the highest ionic conductivity along with high electronic conductivity, making it an ideal anode material. Moreover, its Li-storage mechanism (Li2.33 + alpha Si, 0 < alpha < 0.92) enables ultra-stable cycling with negligible volume change. A Li2.33Si|LiNi0.6Co0.2Mn0.2O2 full cell achieved high areal capacity, long cycle life, fast rate capability, wide operating temperature range, and low stack pressure, demonstrating that the Li2.33Si anode meets all the key requirements for high-performance anodes. Consequently, Li-Si compound anodes will serve as a key enabler for advancing ASSLIB technology, with the concept broadly extendable to other Li-based compounds.

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