A new non-flammable electrolyte is emerging, promising safer, more reliable batteries, while nanoscale self-assembly still shapes its performance limits.
Researchers at the University of Tennessee, Knoxville, are investigating polymeric ionic liquids (PILs), a nonflammable electrolyte that promises safer lithium-ion and lithium-metal batteries. While PILs conduct ions efficiently at room temperature, their softness has traditionally made them difficult to use in practical devices. To overcome this, the team linked PILs to rigid polymers, creating block copolymers that spontaneously self-assemble into ordered nanoscale structures. These architectures enable both ion transport and structural strength, paving the way for safer, high-performance batteries.
However, imperfections in self-assembly or tiny “dead ends” within the nanostructures can block the flow of ions, limiting conductivity by up to two orders of magnitude. Over two years, Professor Gila Stein and Ph.D. student Samuel Adotey created more than a dozen variations, studying how changes in molecular design affect structure and ion mobility. Focusing on lamellar grains, layered, nanoscale sheets that form naturally in the block copolymers. They identified the defects that restrict ionic movement and demonstrated how to design around them.
The team’s work offers a clear path to materials that retain their ordered nanostructures while dramatically improving conductivity. These insights could extend beyond batteries, enabling safer, high-performing electrolytes for medical devices, thin-film transistors, actuators, and other technologies where both mechanical strength and ion transport are critical.
“This research enhances our understanding of how to design PIL block copolymers that retain their nanoscale structure under practical conditions,” says Adotey, “With the right molecular design, these materials could power next-generation batteries and devices that demand both safety and performance.”
