Phonon Engineering in Solid Polymer Electrolyte toward High Safety for Solid-State Lithium Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Rechargeable lithium-ion batteries (LIBs) are widely used but face safety and cycle life limitations.
• Current LIBs require improved thermal management to prevent thermal runaway (TR).

Purpose of the Study:

• To fabricate an ultrathin solid polymer electrolyte (SPE) with enhanced thermal conductivity for improved LIB safety.
• To investigate the effect of phonon scattering reduction on the thermal properties and safety of LIBs.

Main Methods:

• Fabrication of an ultrathin SPE using a composite of ionic liquid (1-ethyl-3-methylimidazolium dicyamide, EMIM:DCA), polyurethane (PU), and lithium salt on a polyethylene separator.
• Analysis of reduced phonon scattering through the introduction of EMIM:DCA to break PU polymer chain attractions.
• Measurement of thermal conductivity enhancement and evaluation of thermal runaway inhibition in LIBs.

Main Results:

• The composite SPE exhibited a six-fold increase in thermal conductivity due to reduced phonon scattering.
• The modified separator matrix provided improved Li+ mobility and a regular thermal diffusion channel.
• Effective inhibition of thermal runaway (TR) was observed in the fabricated LIBs.

Conclusions:

• Reducing phonon scattering through ionic liquid incorporation significantly enhances the thermal conductivity of SPEs.
• Phonon engineering offers a novel strategy for designing high-safety lithium-ion batteries.
• The developed SPE demonstrates potential for safer and more reliable LIB applications.