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 LiPF6-containing carbonate-based electrolyte. This electrolyte design triggers the fluoroethylene 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 degrees C. The assembled hybrid full cell shows an impressive specific capacity retention 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.

Automated summary

A synthetic approach combining AlCl3 Lewis acid and fluoroethylene carbonate is used to create an electrolyte design that forms a mechanically robust and ionically conductive Al-rich interphase. This design overcomes the interface problems between solid electrolytes and Li anodes/cathodes, resulting in a high critical current density and stable cycling performance. The assembled hybrid full cell demonstrates an impressive specific capacity retention, making it a promising direction for the development of safe, long-lasting, and high-energy solid-state lithium-metal batteries.