Stanford University Creates First Shutdown Restart Lithium Ion Battery

Summary: Nanotechnology and a synthesis of organic and polymer materials allow Stanford University to create the first shutdown restart lithium ion battery.

Stanford University's safe and reversible lithium ion battery is safeguarded by a thin polymer film embedded with graphene-coated nickel nanoparticles: "Stanford researchers have developed a thin polyethylene film that prevents a lithium-ion battery from overheating, then restarts the battery when it cools. The film is embedded with spiky nanoparticles of graphene-coated nickel.": Zheng Chen, Stanford University, usage restriction: one-time usage, via EurekAlert!

The first shutdown restart lithium ion battery relies on coating an electrode with thin polyethylene film embedded with graphene-covered spiky nickel nanoparticles for temperature-responsive shutoffs and restarts, according to an online article Monday, Jan. 11, 2016, by 11 Stanford University researchers in Nature Energy.

“People have tried different strategies to solve the problem of accidental fires in lithium-ion batteries,” co-author and Stanford University chemical engineering professor Zhenan Bao explains in a Stanford University news release issued on the date of publication. “We’ve designed the first battery that can be shut down and revived over repeated heating and cooling cycles without compromising performance.”

The Stanford team of researchers affiliated with the university’s departments of Chemical Engineering and of Materials Science and Engineering draw upon nanotechnology and a synthesis of organic and polymer materials in designing the first shutdown restart lithium ion battery (LIB). Their lithium-ion battery is safeguarded by a thermoresponsive polymer switching material (TRPS) that embeds graphene-coated spiky nickel nanoparticles in a thin polyethylene film. The thin TRPS layer coats at least one of the two current collector electrodes in Stanford University's safe lithium-ion battery.

Under acceptable operating temperatures, the graphene-coated spiky nickel nanoparticles remain in contact to conduct electricity. Temperature increases beyond the set operating range cause the polymer film to expand. Expansion separates the nickel nanoparticles. Electrical conductivity ceases with separation of the nickel nanoparticles, and the battery shuts down. With temperature decreases, the polymer film contracts. When contact between the graphene-coated nickel nanoparticles is restored, the battery safely restarts.

“We can even tune the temperature higher or lower depending on how many particles we put in or what type of polymer materials we choose,” explains Zhenan Bao in Stanford University's news release. “For example, we might want the battery to shut down at 50 C [122 degrees Fahrenheit] or 100 C [212 degrees Fahrenheit].”

Typically, a lithium-ion battery features an electricity-conducting medium, known as an electrolyte, in gel or liquid form, for carrying charged particles between two electrodes. High performance, reliable lithium-ion batteries have valuable applications for consumer electronics, electrical vehicles and grid energy storage. Improvements in LIB energy density over the past two decades yield an increased energetic response to such battery abuses as overcharging and shorting. Energy density refers to the amount of energy stored, per unit volume, in a space or system.

Safety presents a major challenge to large-scale use of high-energy-density lithium-ion batteries. Good lithium-ion battery performance still tends to be limited by such variables as current density, temperature and voltage. At abnormal, abuse-caused temperatures greater than 300 degrees Fahrenheit (150 degrees Celsius), as internal cell pressure and temperature increase, lithium-ion batteries are prone to thermal runaway, in which cascades of temperature increases lead to such catastrophes as permanent battery damage, explosion and fire.

In their article describing the first shutdown restart lithium ion battery, titled “Fast and Reversible Thermoresponsive Polymer Switching Materials for Safer Batteries,” the research team concludes: “Compared with previous approaches, our design provides a reliable, fast, reversible strategy that can achieve both high battery performance and improved safety. Therefore, this strategy holds great promise for practical battery applications.”

Spiky graphene-coated nickel nanoparticles shut down overheated batteries and restart cooled batteries (Zheng Chan/Stanford University): News from Science @NewsfromScience via Twitter Jan. 11, 2016

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Stanford University's thin polymer film: Zheng Chen, Stanford University, usage restriction: one-time usage, via EurekAlert! @ http://www.eurekalert.org/multimedia/pub/106404.php?from=315823

Spiky graphene-coated nickel nanoparticles shut down overheated batteries and restart cooled batteries (Zheng Chan/Stanford University): News from Science @NewsfromScience via Twitter Jan. 11, 2016, @ https://twitter.com/NewsfromScience/status/686575128495390720

For further information:

Amine, Khalil. "Batteries: Polymers switch for safety." Nature.com > Nature Energy > News and Views.
Available @ http://www.nature.com/articles/nenergy201518

Bashir, Hira. "Stanford Scientists Create New Battery That Won't Overheat And Catch Fire." I4U > News > Latest Science News. Jan. 12, 2016.
Available @ http://www.i4u.com/2016/01/102847/stanford-scientists-create-new-battery-won-t-overheat-and-catch-fire

Chen, Zheng, et al. "Fast and reversible thermoresponsive polymer switching materials for safer batteries." Nature Energy, vol. 1 (2016): 15009. Published online Jan. 11, 2016. DOI: 10.1038/nenergy.2015.9
Available @ http://www.nature.com/articles/nenergy20159

"New Stanford battery shuts down at high temperatures and restarts when it cools." EurekAlert! > Public Releases. Jan. 11, 2016.
Available @ http://www.eurekalert.org/pub_releases/2016-01/su-nsb010716.php

News from Science @NewsfromScience. "An inexpensive plastic film could help prevent batteries from catching fire." Twitter. Jan. 11, 2016.
Available @ https://twitter.com/NewsfromScience/status/686575128495390720

Shwartz, Mark. "New Stanford battery shuts down at high temperatures and restarts when it cools." Stanford News Service. Jan. 11, 2016.
Available @ http://news.stanford.edu/pr/2016/pr-safe-battery-toggle-011116.html

Stanford Precourt Institute for Energy. "Safe & reliable lithium-ion battery." YouTube. Jan. 11, 2016.
Available @ http://www.youtube.com/watch?v=Mk7DHn_DxUw