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

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• The demand for safer batteries drives research into all-solid-state lithium-ion cells.
• Achieving high energy density requires ultrathin, lightweight solid electrolytes with high ionic conductivity.
• Manufacturing thin solid electrolytes (<10 μm) comparable to commercial separators is challenging due to short-circuit risks.

Purpose of the Study:

• To design and demonstrate a novel polymer-polymer solid-state electrolyte for safer lithium-ion batteries.
• To overcome the limitations of existing thin-film solid electrolytes.
• To enhance ionic conductivity and mechanical stability in solid electrolytes.

Main Methods:

• Fabrication of an 8.6-μm-thick nanoporous polyimide (PI) film.
• Infusion of polyethylene oxide/lithium bis(trifluoromethanesulfonyl)imide (PEO/LiTFSI) into the PI film's vertical channels.
• Testing of the PI/PEO/LiTFSI solid electrolyte in all-solid-state lithium-ion batteries.
• Evaluation of battery performance, cycling stability, and abuse tolerance (bending, cutting, nail penetration).

Main Results:

• The PI/PEO/LiTFSI composite exhibits an ionic conductivity of 2.3 × 10^-4 S cm^-1 at 30°C.
• The nonflammable and mechanically robust PI film prevents short-circuiting for over 1,000 hours.
• All-solid-state lithium-ion batteries demonstrated good cycling performance (200 cycles at C/2 rate) at 60°C.
• The solid electrolyte successfully passed rigorous abuse tests.

Conclusions:

• The developed polymer-polymer solid-state electrolyte offers a promising solution for safer and high-performance lithium-ion batteries.
• The combination of a mechanically strong, nonflammable polymer matrix and conductive polymer electrolyte enhances safety and stability.
• This design facilitates the creation of ultrathin, lightweight solid electrolytes for next-generation energy storage devices.