By Josh Perry, Editor [email protected]
Scientists at the City University of Hong Kong have created a new temperature-sensistive, sol-gel transition electrolyte from proton-incorporated poly(N-isopropylacrylamide-co-acrylic acid) (PNA) and included it in a rechargeable zinc-ion (Zn/α-MnO2) battery system.
Schematic illustration of the thermoresponsive Zn/α-MnO2 batteries with reversible sol-gel transition electrolye. (Science China Press)
According to a press release distributed by the university, “After heating above the low critical temperature, a gelation process occurs in the PNA sol-gel electrolyte and significantly inhibits the migration of zinc ions, leading to a decreased specific capacity and an increased internal resistance of the battery, thus shutting down the battery.”
Once the electrolyte and battery were cooled down to normal operating temperature, the transition electrolyte reverted back to liquid state and the battery was restored to normal performance.
“More importantly, unlike traditional strategies, the sol-gel electrolyte endows the thermoresponsive battery with dynamic charge/discharge rate performance at different temperature, which enabled a ‘smart’ thermal control for the battery,” the announcement continued.
The research was recently published in Science Bulletin. The abstract read:
“Thermal runaway has been a long-standing safety issue impeding the development of high-energy-density batteries. Physical safety designs such as employing circuit-breakers and fuses to batteries are limited by small operating voltage windows and no resumption of original working condition when it is cooled down.
“Here we report a smart thermoresponsive polymer electrolyte that can be incorporated inside batteries to prevent thermal runaway via a fast and reversible sol-gel transition, and successfully combine this smart electrolyte with a rechargeable Zn/α-MnO2 battery system.
“At high temperature, battery operation is inhibited as a result of the increased internal resistance caused by the gelation of liquid electrolyte. After cooling down, the electrolyte is spontaneously reversed to sol state and the electrochemical performance of the battery is restored.
“More importantly, sol-gel transition enables the smart battery to experience different charge-discharge rates under various temperature levels, providing a smart and active strategy to achieve dynamic and reversible self-protection.”
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