New Hybrid Electrolyte For Solid-State Lithium Batteries

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The researchers also demonstrated that their hybrid electrolyte should be stable with two of the most promising next-generation cathode candidates that are being developed, sulfur and high-voltage cathodes such as lithium nickel manganese cobalt oxide.

“People would like to use 5-volt cathodes, but electrolytes that are stable against those 5-volt cathodes are not readily available,” Balsara said. “We have demonstrated this electrolyte is stable at 5 volts, though we have not incorporated the hybrid electrolyte in the cathode yet.”

Further experiments demonstrated that the hybrid electrolyte can be well suited to work with a sulfur cathode, which operates at a relatively low voltage but has the advantages of being high capacity and very inexpensive. A major failure mode in lithium-sulfur cells with conventional liquid electrolytes is the dissolution of intermediate compounds formed as sulfur in the cathode is converted to lithium sulfide into the electrolyte. However, the intermediates were found to be insoluble in the glass-polymer electrolyte.

“Although much work remains to be done, we believe that our work opens a previously unidentified route for developing hybrid solid electrolytes that will address the current challenges of lithium batteries,” the researchers wrote in the PNAS article.

Funding for the research at Berkeley Lab was provided by DOE’s Office of Science through the Joint Center for Energy Storage Research, a DOE Energy Innovation Hub. Part of the work was done at the Stanford Synchrotron Radiation Lightsource at SLAC National Accelerator Laboratory and at the Advanced Light Source at Berkeley Lab, both DOE Office of Science User Facilities.

Balsara was one of the co-founders of battery startup Seeo, founded in 2007 to develop a solid block copolymer electrolyte. Balsara and DeSimone have also co-founded a startup company called Blue Current, which aims to commercialize a perfluoropolyether-based nonflammable electrolyte they developed together.

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