Nav: Home

A cold-tolerant electrolyte for lithium-metal batteries emerges in San Diego

July 01, 2019

Improvements to a class of battery electrolyte first introduced in 2017 - liquefied gas electrolytes - could pave the way to a high-impact and long-sought advance for rechargeable batteries: replacing the graphite anode with a lithium-metal anode.

The research, published July 1, 2019 by the journal Joule, builds on innovations first reported in Science in 2017 by the same research group at the University of California San Diego and the university spinout South 8 Technologies.

2017 press release: http://jacobsschool.ucsd.edu/news/news_releases/release.sfe?id=2235

2017 Science paper: https://science.sciencemag.org/content/356/6345/eaal4263

Finding cost-effective ways to replace the graphite anode in commercial lithium-ion batteries is of great interest because it could lead to lighter batteries capable of storing more charge, via a 50 percent increase in energy density at the cell level. The increased energy density would come from a combination of factors including the lithium-metal anode's high specific capacity, low electrochemical potential, and light weight (low density).

As a result, switching to lithium-metal anodes would significantly extend the range of electric vehicles and lower the cost of batteries used for grid storage, explained UC San Diego nanoengineering professor Shirley Meng, a corresponding author on the new paper in Joule.

However, making the switch comes with technical challenges. The main hurdle is that lithium metal anodes are not compatible with conventional electrolytes. Two long-standing problems arise when these anodes are paired with conventional electrolytes: low cycling efficiency and dendrite growth.

So Meng and colleagues' approach was to switch to a more compatible electrolyte, called liquefied gas electrolytes.

Liquefied gas electrolytes in action

One of the tantalizing aspects of these liquefied gas electrolytes is that they function both at room temperature and at extremely low temperatures, down to minus 60 C. These electrolytes are made from liquefied gas solvents -- gases that are liquefied under moderate pressures -- which are far more resistant to freezing than standard liquid electrolytes.

In the 2019 paper in Joule, the researchers report on how, through both experimental and computational studies, they improve their understanding on some of the shortcomings of the liquefied gas electrolyte chemistry. With this knowledge, they were able to tailor their liquefied gas electrolytes for improved performance in key metrics for lithium-metal anodes, both at room temperature and minus 60 C.

In lithium-metal half-cell tests, the team reports that the anode's cycling efficiency (Coulombic efficiency) was 99.6 percent for 500 charge cycles at room temperature. This is up from the 97.5 percent cycling efficiency reported in the 2017 Science paper, and an 85 percent cycling efficiency for lithium metal anodes with a conventional (liquid) electrolyte.

At minus 60 C, the team demonstrated lithium-metal anode cycling efficiency of 98.4 percent. In contrast, most of conventional electrolytes fail to work below minus 20 C.

The UC San Diego team's simulation and characterization tools, many developed in the Laboratory for Energy Storage and Conversion led by Shirley Meng, allow the researchers to explain why lithium metal anodes perform better with liquefied gas electrolytes. At least part of the answer has to do with how the lithium particles deposit on the metal anode surface.

The researchers report the smooth and compact deposition of lithium particles on lithium-metal anodes when liquefied gas electrolytes are used. In contrast, when conventional electrolytes are used, needle-like dendrites form on the lithium metal anode. These dendrites can degrade the efficiency, cause short circuits, and lead to serious safety threats.

One measure of how densely lithium particles deposit on anode surfaces is porosity. The lower the porosity the better. The research team reports in Joule that porosity of lithium particle deposition on a metal anode is 0.90 percent at room temperature using liquefied gas electrolytes at room temperature. The porosity in the presence of conventional electrolytes jumps to 16.8 percent.

The race for the right electrolyte

There is currently a big push to find or improve electrolytes that are compatible with the lithium metal anode and are competitive in terms of cost, safety, and temperature range. Research groups have mainly been looking at highly-concentrated solvents (liquid) or solid-state electrolytes, but there is currently no silver bullet.

"As part of the battery research community, I am confident that we are going to develop the electrolytes that we need for lithium-metal anodes. I hope that this research inspires more research groups to take a serious look at liquefied gas electrolytes," said Meng.
-end-
Meng is also the corresponding author on a related article in the May 2019 issue of Trends in Chemistry "Key Issues in Hindering a Practical Lithium-Metal Anode."

Paper Title

High Efficiency Lithium Metal Anode Enabled by Liquefied Gas Electrolytes

Authors and Affiliations

Authors: Yangyuchen Yang 1, Daniel M. Davies 2, Yijie Yin 1, Oleg Borodin 3, 4*, Jungwoo Lee 2, 5, Chengcheng Fang 1, Marco Olguin 2, Yihui Zhang 1, Ekaterina S. Sablina 1, Xuefeng Wang 2, Cyrus S. Rustomji 5*, Y. Shirley Meng 1, 2, 6*

Affiliations
    1Materials Science and Engineering, University of California, San Diego, La Jolla, CA 92121, USA

    2Department of Nano Engineering, University of California, San Diego, La Jolla, CA 92121, USA

    3Electrochemistry Branch, Sensors and Electron Devices Directorate, U.S. Army Research Laboratory, Adelphi, MD 20783, USA

    4Joint Center for Energy Storage Research, U.S. Army Research Laboratory, Adelphi, MD 20783, United States

    5South 8 Technologies, Inc., San Diego, CA 92109, USA

    6Lead Contact
Funders and Acknowledgements:

This work was supported by South 8 Technologies under National Science Foundation NSF SBIR program (grant no. 1721646). Partial funding for the advanced characterization is provided by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy under the Battery500 Consortium. The authors gratefully acknowledge R. Chen for use of facilities for much of the scope of this work and thank Z. Liu from Ningbo Institute for the donation of the Li-ion Jelly Rolls. The cryo-FIB and SEM were developed and performed in part at the San Diego Nanotechnology Infrastructure (SDNI), a member of the National Nanotechnology Coordinated Infrastructure, which is supported by the National Science Foundation (grant no. ECCS-1542148). Y. Yang thanks I. C. Tran and T. Salk for their help and thoughtful discussions regarding XPS experiments performed at the University of California Irvine Materials Research Institute (IMRI) using instrumentation funded in part by the National Science Foundation Major Research Instrumentation Program (grant CHE-1338173). Work at ARL by O. Borodin was supported as part of the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences through IAA SN2020957. All experimental and computational data described in the paper are presented, curated, and archived in Cloud Storage system. Raw data and metadata are available upon request.

University of California - San Diego

Related Batteries Articles:

A seaweed derivative could be just what lithium-sulfur batteries need
Lithium-sulfur batteries have great potential as a low-cost, high-energy, energy source for both vehicle and grid applications.
Batteries from scrap metal
Chinese scientists have made good use of waste while finding an innovative solution to a technical problem by transforming rusty stainless steel mesh into electrodes with outstanding electrochemical properties that make them ideal for potassium-ion batteries.
Better cathode materials for lithium-sulphur-batteries
A team at the Helmholtz-Zentrum Berlin (HZB) has for the first time fabricated a nanomaterial made from nanoparticles of a titanium oxide compound (Ti4O7) that is characterized by an extremely large surface area, and tested it as a cathode material in lithium-sulphur batteries.
Bright future for self-charging batteries
Who hasn't lived through the frustrating experience of being without a phone after forgetting to recharge it?
Making batteries from waste glass bottles
Researchers at the University of California, Riverside's Bourns College of Engineering have used waste glass bottles and a low-cost chemical process to create nanosilicon anodes for high-performance lithium-ion batteries.
Batteries -- quick coatings
Scientists at Oak Ridge National Laboratory are using the precision of an electron beam to instantly adhere cathode coatings for lithium-ion batteries -- a leap in efficiency that saves energy, reduces production and capital costs, and eliminates the use of toxic solvents.
Lighter, more efficient, safer lithium-ion batteries
Researchers from Universidad Carlos III de Madrid and the Council for Scientific Research (initialed CSIC in Spanish) have patented a method for making new ceramic electrodes for lithium-ion batteries that are more efficient, cheaper, more resistant and safer than conventional batteries.
Clarifying how lithium ions ferry around in rechargeable batteries
IBS scientists observe the real-time ultrafast bonding of lithium ions with the solvents, in the same process that happens during charging and discharging of lithium batteries, and conclude that a new theory is needed.
A new approach to improving lithium-sulfur batteries
Researchers from the University of Delaware and China's Northwestern Polytechnical University, Shenzhen University and Hong Kong Polytechnic University have demonstrated a new polysulfide entrapping strategy that greatly improves the cycle stability of Li-S batteries.
Looking for the next leap in rechargeable batteries
USC researchers may have just found a solution for one of the biggest stumbling blocks to the next wave of rechargeable batteries -- small enough for cellphones and powerful enough for cars.

Related Batteries Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Anthropomorphic
Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#SB2 2019 Science Birthday Minisode: Mary Golda Ross
Our second annual Science Birthday is here, and this year we celebrate the wonderful Mary Golda Ross, born 9 August 1908. She died in 2008 at age 99, but left a lasting mark on the science of rocketry and space exploration as an early woman in engineering, and one of the first Native Americans in engineering. Join Rachelle and Bethany for this very special birthday minisode celebrating Mary and her achievements. Thanks to our Patreons who make this show possible! Read more about Mary G. Ross: Interview with Mary Ross on Lash Publications International, by Laurel Sheppard Meet Mary Golda...