On the road to fire-free, lithium-ion batteries made with asphalt
Lithium-ion batteries can be found in everything from cell phones to hoverboards, but these power sources have recently made headlines for the fires they have inadvertently caused. To address these safety hazards, scientists report in ACS Nano that they are paving the way to better batteries with a naturally occurring form of asphalt.
Since the lithium-ion battery first hit the market in 1991, it has become the industry standard due to its light weight and high efficiency. But the lithium-ion battery can act as its own worst enemy. As lithium ions move between electrodes in the battery, some stray. These rogue ions create microfibers, known as dendrites, that increase the risk of fires. To address this issue, scientists are looking to develop a different material to pair with lithium. Researchers have been pursing graphene and advanced nanomaterials as options because they block dendrite formation. But these routes have stalled due to high costs and other complicating factors. James M. Tour and colleagues wanted to go in a different direction and see if a natural, low-cost asphalt, which has a structure similar to graphene, would be a good alternative.
The team started by mixing asphalt with graphene nanoribbons to boost its conductivity. They then coated copper foil, the traditional lithium-ion battery substrate, with the asphalt-nanoribbon mixture. Next, lithium was plated uniformly onto the substrate, allowing for equal distribution of the ions. Testing showed that the resulting device had a higher conductivity than traditional lithium-ion batteries. In addition, the asphalt battery was more than 10 times faster at recharging than current commercial batteries. And the simple, inexpensive method the researchers developed resulted in no dendrite formation, an outcome that could one day contribute to a safer battery.
The authors acknowledge funding from the U.S. Air Force Office of Basic Research, Celgard LLC, Merck KGaA and Prince Energy.
The authors declare the following competing financial interest: Rice University has filed patents on the processes described in the paper. Those patents are under license or to be licensed by companies in which none of the authors are employees, officers or directors. An author has stock in one of the companies, and all potential conflicts are monitored by regular disclosure to the Rice University Office of Sponsored Projects and Research Compliance.
The abstract that accompanies this study is available here.
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