Exposure to light cathodes reduces the charge time by a factor of two in lithium-ion batteries
Researchers from the US Department of Energy's National Laboratory of Argon (DOE) report new charge accelerator of lithium-ion batteries for electric vehicles. Simply exposing a beam of concentrated light to a cathode – for example, white light from a xenon lamp – reduces the battery charge time by a remarkable factor of two or more. If commercialized, such technology could be a game changer for electric vehicles.
Electric vehicle owners are well aware of "range anxiety" as the charge level decreases or the location of the nearest charging station seems too remote. Fast charging remains a critical challenge if such vehicles ever conquer a large segment of the transportation market. It usually takes about eight hours to charge an empty car.
"We wanted to significantly shorten this charge response without damaging the electrodes from the higher current flow." – Christopher Johnson, Argon Distinguished Assistant
Special charging stations now exist that achieve ultra-fast electric charging vehicles, delivering much higher current to the battery. Leaking too much current for too short a time, however, impairs battery performance
Typically, vehicle lithium-ion batteries are slowly charged to produce a complete electrochemical reaction. This reaction involves removing lithium from the cathode and inserting it into the graphite anode.
"We wanted to significantly shorten this charge response without damaging the electrodes from the higher current flow," says Christopher Johnson, Argon Distinguished Assistant and Group
Today, lithium-ion batteries work in the dark, with the electrodes are put in a box. Argonne's photomobile technology would use a transparent container that allows concentrated light to illuminate the electrodes of the battery during charging.
To study the loading process, the research team made small lithium-ion cells ("coin cells") with transparent quartz windows, then they tested those cells with and without white light, which shined through the window toward the cathode.
"We assumed that white light would interact favorably with the typical cathode material during loading, and this appeared in our cell. tests, ”Johnson said. This cathode material is lithium manganese oxide, abbreviated as LiMn 2 O 4 (LMO).
The key ingredient in this favorable reaction is the interaction of light with LMO, a semiconductor material known to interact with light. While absorbing photons in light during charging, the manganese element in the LMO changes its charge state from trivalent to tetravalent (Mn 3+ to Mn 4+ ). In response, lithium ions are released more rapidly from the cathode than would occur without the photon excitation process.
"We assumed that white light would interact favorably with typical cathode material during loading, and this proved to be our cellular test. ”- Christopher Johnson, Argon Distinguished Fellow
This condition triggers the battery response faster. The team found that faster response leads to faster charging without compromising battery performance or cycle life. "Our cell tests showed a factor of two reducing the charging time when the light was on," says Johnson.
The research team did this work as part of the Center for Electrochemical Science for Energy (CEES), the DOE Energy Frontier Research Center (EFRC), led by Argon. "
" This study is a great example of how the goal of CEES to understand the processes of electrodes in lithium-ion batteries enables major advances that affect technology, "says Paul Fenter, CEES director and senior physicist at Chemical Sciences and Engineering. " "This is emblematic of the transformational impact that the EAFRD program can achieve."
Johnson added that "This discovery is the first of its kind to bring light and battery technology together and this intersection is good for the future of innovative Battery charging concepts. "
The DOE's Office of Vehicle Technology Service identified the DOE's fast charging as a critical challenge to secure mass acceptance of electric vehicles for the purpose of a 15-minute recharge time and this study could be the key to making it possible.
This study appeared in Nature Communications entitled "Photo-accelerated fast charge of lithium-ion batteries." In addition to Johnson, other Argon contributors are Anna Lee, Marton Vieros, Wesley M. Dose. , Jens Niklas, Oleg Poluektov, Richard D. Schaller, Hakim Iddir, Victor A. Maroni, Eungji Lee, Brian Ingram and Larry A. Kurti ss.
Reference: "Photo-Accelerated Fast Charging of Lithium-Ion Batteries" by Anna Lee, Marton Vieros, Wesley M. Dose, Jens Niklas, Oleg Poluektov, Richard D. Schaller, Hakim Iddir, Victor A. Maroni, Eungje Lee, Brian Ingram, Larry A. Curtiss and Christopher S. Johnson, October 30, 2019, Nature Communications .
DOI: 10.1038 / s41467-019-12863-6  This study was funded by the DOE's Department of Basic Energy Sciences and performed in part by the Center for Bulk Materials, US Department of Energy's Department of Energy.