Ultrathin, flexible, solid polymer composite electrolyte enabled with aligned nanoporous host for lithium batteries

• Published in: Nature nanotechnology Vol. 14; no. 7; pp. 705 - 711
• Main Authors: Wan, Jiayu, Xie, Jin, Kong, Xian, Liu, Zhe, Liu, Kai, Shi, Feifei, Pei, Allen, Chen, Hao, Chen, Wei, Chen, Jun, Zhang, Xiaokun, Zong, Linqi, Wang, Jiangyan, Chen, Long-Qing, Qin, Jian, Cui, Yi
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.07.2019; Nature Publishing Group
• Subjects: 639/301/299/891; 639/638/161/891; Abuse; Chemistry and Materials Science; Composite materials; Conductivity; Cycles; Electrolytes; Electrolytic cells; ENERGY STORAGE; Flux density; Ion currents; Ions; Lithium; Lithium batteries; Lithium-ion batteries; MATERIALS SCIENCE; Molten salt electrolytes; Nanotechnology; Nanotechnology and Microengineering; Polyethylene; Polyethylene oxide; Polyethylenes; Polyimide resins; Polymer matrix composites; Polymers; Rechargeable batteries; Separators; Solid electrolytes; Solid state
• ISSN: 1748-3387; 1748-3395
• DOI: 10.1038/s41565-019-0465-3

The urgent need for safer batteries is leading research to all-solid-state lithium-based cells. To achieve energy density comparable to liquid electrolyte-based cells, ultrathin and lightweight solid electrolytes with high ionic conductivity are desired. However, solid electrolytes with comparable thicknesses to commercial polymer electrolyte separators (~10 μm) used in liquid electrolytes remain challenging to make because of the increased risk of short-circuiting the battery. Here, we report on a polymer–polymer solid-state electrolyte design, demonstrated with an 8.6-μm-thick nanoporous polyimide (PI) film filled with polyethylene oxide/lithium bis(trifluoromethanesulfonyl)imide (PEO/LiTFSI) that can be used as a safe solid polymer electrolyte. The PI film is nonflammable and mechanically strong, preventing batteries from short-circuiting even after more than 1,000 h of cycling, and the vertical channels enhance the ionic conductivity (2.3 × 10 −4  S cm −1 at 30 °C) of the infused polymer electrolyte. All-solid-state lithium-ion batteries fabricated with PI/PEO/LiTFSI solid electrolyte show good cycling performance (200 cycles at C/2 rate) at 60 °C and withstand abuse tests such as bending, cutting and nail penetration. A nanoporous polyimide film filled with a solid polymer electrolyte has high ionic conductivity and high mechanical strength. An all-solid-state battery made with an approximately 10-μm-thick film shows good cyclability at 60 °C and no dendrite formation.