Ultrathin Polymer Electrolyte With Fast Ion Transport and Stable Interface for Practical Solid-state Lithium Metal...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Ultrathin solid-polymer electrolytes (SPEs) are crucial for developing high-energy-density and safe lithium-metal batteries (LMBs), offering an alternative to liquid electrolytes.
• Key challenges in SPE development include achieving high ionic conductivity and effective suppression of lithium dendrite growth.

Purpose of the Study:

• To propose a scalable fabrication method for high-performance ultrathin SPEs.
• To enhance the ionic conductivity and lithium dendrite retardant properties of SPEs for advanced LMBs.

Main Methods:

• Fabrication of an ultrathin (≈7.8 µm) polycarbonate-based electrolyte (UPCE) using a phase separation-derived porous scaffold of poly(vinylidene fluoride-co-hexafluoropropylene) (PVH).
• Electrolyte structural engineering with 1-fluoro-4-(1-methylethenyl)benzene (FMB) to modify Li+ solvation and promote a LiF-rich solid-electrolyte interphase (SEI).
• Characterization of ionic conductivity, critical current density, and cycling performance in Li-metal symmetric cells, Li|LiCoO2 cells, and pouch cells.

Main Results:

• The designed UPCE exhibits a high ionic conductivity of 4.8 × 10⁻⁴ S cm⁻¹ and an ultrahigh critical current density of 11.5 mA cm⁻² at 25 °C.
• Solid-state Li symmetric cells achieved ultralong cycling over 6000 hours at 0.5 mA cm⁻².
• Li|LiCoO2 cells demonstrated stable cycling over 1500 cycles at 4.5 V, and pouch cells reached a high energy density of 495 Wh kg⁻¹.

Conclusions:

• The developed UPCE, fabricated via scalable methods, addresses the critical challenges of ionic conductivity and dendrite suppression in ultrathin SPEs.
• This work presents a promising pathway for the commercialization of high-energy solid-state LMBs.