Solid-state rigid-rod polymer composite electrolytes with nanocrystalline lithium ion pathways

• Published in: Nature materials 2021-05, Vol.20 (9)
• Main Authors: Wang, Ying, Zanelotti, Curt J., Wang, Xiaoen, Kerr, Robert, Jin, Liyu, Kan, Wang Hay, Dingemans, Theo J., Forsyth, Maria, Madsen, Louis A.
• Format: Article
• Language: English
• Subjects: ENERGY STORAGE; Materials chemistry; Materials for devices; Materials for energy and catalysis; Nanoscale materials; Soft materials
• ISSN: 1476-1122; 1476-4660

A critical challenge for next-generation lithium-based batteries lies in development of electrolytes that enable thermal safety along with use of high-energy-density electrodes. We describe molecular ionic composite (MIC) electrolytes based on an aligned liquid crystalline polymer combined with ionic liquids and concentrated Li salt. This high strength (200 MPa) and non-flammable solid electrolyte possesses outstanding Li+ conductivity (1 mS cm-1 at 25 °C) and electrochemical stability (5.6 V vs Li|Li+) while suppressing dendrite growth and exhibiting low interfacial resistance (32 Ω cm2) and overpotentials (≤ 120 mV @ 1 mA cm-2) during Li symmetric cell cycling. A heterogeneous salt doping process modifies a locally ordered polymer-ion assembly to incorporate an inter-grain network filled with defective LiFSI & LiBF4 nanocrystals, strongly enhancing Li+ conduction. Furthermore, this modular material fabrication platform shows promise for safe and high-energy-density energy storage and conversion applications, incorporating the fast transport of ceramic-like conductors with the superior flexibility of polymer electrolytes.