An Ultra-Thin Crosslinked Carbonate Ester Electrolyte for 24 V Bipolar Lithium-Metal Batteries

Fabrication of an ultrathin solid electrolyte with high conductance is essential to achieve high energy density of solid-state batteries. As solid polymer electrolytes (SPEs) are characterized by good ductility, ease of manufacturing, and low cost, the current solvent-based casting pathway suffers from the difficulty in controlling the thickness. In addition, the low ionic conductivity and narrow electrochemical window of the polyether-type SPEs further hinder their practical applications. We fabricate an ultra-thin solid-polymer electrolyte by in situ polymerization of carbonate ester vinyl ethylene carbonate and poly(ethylene glycol) diacrylate using a porous polypropylene membrane as a support. The obtained solid electrolyte is of only 8 mu m and possesses an unprecedented ionic conductance of 83.3 mS at room temperature. Furthermore, the electrolyte is compatible with Li metal and can suppress dendrite growth. An all-solid-state lithium battery based on LiFePO4 cathode can operate stably for over 150 cycles with 86% capacity retention. The non-fluidic nature of the electrolyte further enables the fabrication of an energy-dense 24 V bipolar pouch cell which demonstrates extreme flexibility and safety. No voltage drop is observed upon folding and cutting. This in situ polymerized ultra-thin electrolyte provides a promising platform for the fabrication of high-energy solid-state batteries and also a potential candidate for flexible batteries.

Automated summary

The fabrication of an ultrathin solid electrolyte with high conductance is crucial for achieving high energy density in solid-state batteries. Researchers have successfully synthesized an ultra-thin solid-polymer electrolyte with unprecedented ionic conductance by in situ polymerization of carbonate ester vinyl ethylene carbonate and poly(ethylene glycol) diacrylate. This electrolyte exhibits compatibility with Li metal and can suppress dendrite growth, demonstrating excellent stability and flexibility.