Synergistic Approach toward Developing Highly Compatible Garnet-Liquid Electrolyte Interphase in Hybrid Solid-State Lithium-Metal Batteries

The hybrid solid-liquid electrolyte concept is one of the best approaches for counteracting the interface problems between solid electrolytes and Li anodes/cathodes. However, a solid-liquid electrolyte layer forming at the interfaces degrades battery capacity and power during a longer cycle due to highly reactive chemical and electrochemical reactions. To solve this problem in the present study, a synthetic approach is demonstrated by combining AlCl3 Lewis acid and fluoroethylene carbonate as additives in a conventional LiP6-containing carbonate-based electrolyte. This electrolyte design triggers the fluoroethylen carbonate polymerization by AlCl3 addition and can also form a mechanically robust and ionically conductive Al-rich interphase on the surface of Li7La2.75Ba0.25Zr1.75Ta0.25O12 garnet-type structured solid electrolytes, Li anodes and LiNi0.6Mn0.2Co0.2O2 cathodes. Benefitting from this approach, the assembled Li symmetric cell exhibits a remarkably high critical current density of 4.2 mA cm−2, and stable long-term cycling over 3000 h at 0.5 mA cm−2 at 25 °C. The assembled hybrid full cell shows an impressive specific capacity retentio of 92.2% at 1 C till 200 cycles. This work opens a new direction in developing safe, long-lasting, and high-energy hybrid solid-state lithium-metal batteries.