Researchers have now replaced the standard graphite anode in a lithium-ion battery with a lumpy carbon-based material that maintains its rechargeable storage capacity down to -31 Degrees Fahrenheit!
Because they can store a lot of energy and have extended lifespans, lithium-ion batteries are ideal for powering rechargeable electronics. When temperatures drop below freezing, however, these energy sources’ electrical effectiveness suffers, and in extreme cases, they may fail to transfer any charge. Scientists have discovered that the flat orientation of graphite in the anode is what causes a lithium-ion battery’s energy storage capacity to diminish in the cold. To improve the anode’s charge transfer process, Xi Wang, Jiannian Yao, and colleagues modified the surface structure of a carbon-based material.
The researchers heated a cobalt-containing zeolite imidazolate framework (known as ZIF-67) to high temperatures to develop the novel material. The rough surfaces of the resulting 12-sided carbon nanospheres displayed good electrical charge transport capabilities. The scientists next put the material through its paces as an anode in a coin-shaped battery with lithium metal as the cathode.
At temperatures ranging from 77 degrees Fahrenheit to -4 degrees Fahrenheit, the anode displayed steady charging and discharging and maintained 85.9% of its room temperature energy storage capacity slightly below freezing. At freezing temperatures, lithium-ion batteries constructed using different carbon-based anodes, such as graphite and carbon nanotubes, held essentially no charge.
The anode built with rough nanospheres was still rechargeable after the researchers decreased the air temperature to -31 F, and upon discharge, it released nearly 100 percent of the charge put into the battery. According to the researchers, incorporating the rough nanosphere material into lithium-ion batteries could allow these energy sources to be used at extremely low temperatures.
Their study titled “Riemannian Surface on Carbon Anodes Enables Li-Ion Storage at −35 °C” is published in ACS Central Science. Click here to view the entire study.