People's demands for batteries weren't high: provide energy for as long as needed, charge quickly, and not catch fire suddenly. However, a series of mobile phone battery fires in 2016 shook consumer confidence in lithium-ion batteries. Since their introduction in the 1980s, lithium-ion batteries have helped lead the development of modern portable electronics, but have been plagued by safety concerns. With growing interest in electric vehicles, researchers and industry insiders are searching for technologies to improve rechargeable batteries, technologies that can safely and reliably power cars, self-driving cars, robots, and other next-generation devices.
According to foreign media reports, a new study from Cornell University has improved the design of solid-state batteries. Solid-state batteries are inherently safer and have higher energy density than existing lithium-ion batteries, which rely on a flammable liquid electrolyte to rapidly transfer chemical energy stored in molecular bonds into electrical energy. Cornell researchers have transformed the liquid electrolyte into a solid polymer inside the electrochemical battery, utilizing the properties of both liquids and solids to overcome key limitations currently affecting battery design.
"Imagine a glass filled with ice cubes," said Qing Zhao, a postdoctoral researcher and lead author of the study. "Some ice cubes touch the glass, but there are gaps. However, if you fill the glass with water and freeze it, the interface is completely covered, and a strong bond can be established between the ice cubes and the water inside the glass. The same concept can be used in batteries to promote the high-rate transfer of ions from the solid surface of the battery electrode to the electrolyte without the need for flammable liquids."
The key to this approach lies in introducing special molecules that initiate polymerization within the electrochemical cell without compromising other battery functions. If the electrolyte is a cyclic ether, an initiator can be designed to tear the ring, thereby generating reactive monomer chains that are bonded together to produce long-chain molecules with essentially the same chemical properties as the ether. These robust polymers maintain a tight bond at the metal interface, much like ice cubes in a glass.
In addition to improving battery safety, solid-state electrolytes enable next-generation batteries to utilize metals such as lithium and aluminum as anodes, achieving greater energy storage compared to today's most advanced battery technologies. In this case, solid-state electrolytes prevent the formation of metal dendrites, which can lead to short circuits, overheating, and malfunctions. Despite the significant advantages of solid-state batteries, large-scale mass production has been hampered. High manufacturing costs and poor interface performance resulting from previous designs pose major technical obstacles. Furthermore, solid-state systems can stabilize battery thermal changes, eliminating the need for battery cooling.
According to researchers, on-site technology for producing novel polymer electrolytes promises to extend the cycle life of high-energy-density rechargeable metal batteries and improve their charging capabilities.
