Chemical engineering professor Lynden Archer believes there needs to be a battery technology “revolution” – and thinks that his lab has fired one of the first shots.

“What we have now [in lithium-ion battery technology] is actually at the limits of its capabilities,” said Archer, the James A. Friend Family Distinguished Professor of Engineering in the Smith School of Chemical and Biomolecular Engineering. “The lithium-ion battery, which has become the workhorse in powering new electronics technologies, operates at over 90 percent of its theoretical storage capacity. Minor engineering tweaks may lead to better batteries with more storage, but this is not a long-term solution.

“You need a kind of radical mindset change,” he said, “and that means that you’ve got to almost start at the beginning.”

Snehashis “Sne” Choudhury, Ph.D. ’18, has come up with what Archer terms an “elegant” solution to a fundamental problem with rechargeable batteries that use energy-dense metallic lithium anodes: sometimes-catastrophic instability due to dendrites, which are spines of lithium that grow from the anode as ions travel back and forth through the electrolyte during charge and discharge cycles.

If the dendrite breaks through the separator and reaches the cathode, short-circuiting and fire can occur. Solid electrolytes have been shown to suppress dendrite growth mechanically, but at the expense of fast ion transport. Choudhury’s solution: Confine dendrite growth by the structure of the electrolyte itself, which can be controlled chemically.

Using a reaction procedure the Archer group introduced in 2015, they employ “cross-linked hairy nanoparticles” – a graft of silica nanoparticles and a functionalized polymer (polypropylene oxide) – to create a porous electrolyte that effectively lengthens the route ions must take to travel from the anode to the cathode and back, dramatically increasing the life of the anode.

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