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Argonne team develops new fluorinated sulfone electrolytes for high-voltage, high-energy Li-ion batteries

20 March 2017

Researchers at Argonne National Laboratory have synthesized a new class of fluorinated sulfone electrolytes to enable high-voltage, high-energy Li-ion batteries. A paper on their work is published in the RSC journal Energy & Environmental Science.

The Argonne researchers evaluated the physical and electrochemical properties of the new sulfone-based electrolytes in a high voltage LiNi0.5Mn0.3Co0.2O2/ graphite cell cycled at 4.6 V. The fluorinated sulfones—with an α-trifluoromethyl group—exhibit enhanced oxidation stability, reduced viscosity and superior separator wettability as compared to their non-fluorinated counterparts.

Lithium-ion batteries (LIBs) are ubiquitous power sources for consumer electronics due to high energy density and long cycle life. However, for electric vehicle market, a wider application of LIB technology has been hindered by the safety, high cost, and insufficient gravimetric energy density. To further increase the latter, new cathode materials are vigorously pursued.… Another strategy is to increase the operating voltage over 5 V … Cathode materials of this kind have been developed, too, including olivine-type LiNiPO4 and LiCoPO4 and spinel-type LiNi0.5Mn1.5O4 (LNMO) and LiCoMnO4. For the state-of-the-art LiNixMnyCozO2 (NMC) cathode, it is usually only charged to 4.2 V or 4.3 V which only utilizes its partial capacity (287 mAhg-1). Further increase in the charging voltage is also effective in enhancing its capacity and energy. However, to take full advantage of these high voltage high energy cathode materials, novel electrolytes with high oxidation stability would be required.

… The conventional lithium ion battery electrolyte is a 1.0-1.5 M lithium hexafluorophosphate (LiPF6) dissolved in a mixture of ethylene carbonate (EC) with dimethyl carbonate (DMC), diethyl carbonate (DEC), and/or ethyl methyl carbonate (EMC). Designed for 4-V application, this electrolyte decomposes rapidly at potentials exceeding 4.5 V circumscribing its application in high-voltage lithium ion cells. Therefore, the development of new and intrinsically more stable electrolytes has become a priority for LIB researchers.

… In this communication, we report a new class of trifluoromethyl (-CF3) sulfone-based electrolytes for high voltage high energy LIB.

—Su et al.

The team synthesized trifluoromethyl ethyl sulfone (FMES) and trilfuoromethyl propyl sulfone (FMPS) for use as electrolytes. FMES and FMIS exhibit properties such as reduced viscosity, enhanced wetting and decreased boiling point compared with their non-fluorinated counterparts EMS and MIS.

Su
Capacity vs cycle number for LiNi0.5Mn0.3Co0.2O2/graphite full cells cycled with 1.0 M LiPF6 DFEC/FMES, 1.0 M LiPF6 DFEC/FPMS 1.0 M LiPF6 DFEC/EMC, and Gen 2 electrolyte. (Cycling condition: C/10 for 2-cycle formation and then C/3 for 100 for cycling with 3.0-4.6 V cut-off voltage.) Credit: Su et al. Click to enlarge.

… this study offers a breakthrough technology for the high voltage high energy lithium ion battery field. Trifluoromethyl substituted fluorinated sulfones proved to be a promising next generation electrolyte for high voltage high energy application as evidenced by the long term cycling performance in NMC532/graphite cell cycled at 4.6 V. Our future research will be focused on further tailoring the graphite/electrolyte interface by appropriate additives or co-solvent and scrutinize the mechanism of the superior cell performance at high voltages.

—Su et al.

This research was supported by the Advanced Battery Research for Transportation Program (ABR), Vehicle Technologies Program, Office of Energy Efficiency and Renewable Energy, US Department of Energy.

Resources

  • Chi-Cheung Su, Meinan He, Paul C Redfern, Larry A Curtiss, Ilya Shkrob and Zhengcheng Zhang (2017) “Oxidatively Stable Fluorinated Sulfone Electrolytes for 5-V Lithium-ion Battery” Energy Environ. Sci. doi: 10.1039/C7EE00035A

March 20, 2017 in Batteries, Electric (Battery) | Permalink | Comments (7)

Comments

I knew that actual ev batteries like bolt and tesla were bad, that's why almost nobody is buying, less than 1% market share. Do like me and wait for a cheap and safe battery with triple the range that can be fast charged safely. Still today a small gas car is the best low cost solution for efficiency and value.

By the way doctor clark explain in this video that human co2 are completely irrelevant for the climate.

https://www.youtube.com/watch?v=gb08wPe4zEc

The energy density is still too low. Something like 600+ Wh/Kg is required for all weather extended range BEVs.

Passed the 1% some time ago, and growth is accelerating exponentially. Resistance is futile Fossil Man.

Harvey, how many Wh/kg do you believe this Argonne team has demonstrated with the electrolyte chemistry reported above?

Practical energy density is very variable and would depend on voltage used and number of full operation cycles. Remains to be demonstrated.

Yes, the article and chart reference voltage and cycles. You say in your first comment the energy density is too low. So clearly you've made an evaluation about what the energy density indicated by this summary of the research is.

You expressed your estimate of required energy density in Wh/kg. Ok, so I'm asking you what you believe the energy density, expressed in Wh/kg, is of the above mentioned chemistry?

Maybe you'll be surprised to learn how close this breakthrough is to your own ambitious standard, which would yield the rough equivalent to a 700 mile Chevy Bolt or 945 mile Tesla Model S 100D.

I still believe that batteries energy density will go from 1X (in or pre-2010) to 5X by 2030 or shortly thereafter.

The above storage technology will probably be fined tuned to produce 3X to 4X batteries by 2025 or so. That will be when all weather extended range (affordable) BEVs may be produced.

Meanwhile, one may buy an affordable short range BEV (as a second car) or invest over $100K for a TESLA S100D or S120D.

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