CU researchers closer to battery breakthrough

 Battery technology developed at the University of Colorado at Boulder that could enable electric vehicles to travel twice as far on a charge has moved closer to becoming a commercial reality.

The Technology Transfer Office at CU has completed an agreement with Solid Power — a spinoff company founded by Se-Hee Lee and Conrad Stoldt, both associate professors of mechanical engineering — to develop and bring to market a solid-state rechargeable battery. Solid Power recently was awarded a $3.4 million grant from the Department of Energy to develop a battery that extends electric vehicle driving range.

The lithium-ion rechargeable batteries standard in electric vehicles — as well as a host of such consumer electronics as mobile telephones and laptop computers —generate electricity when lithium ions move back and forth between electrodes in a liquid electrolyte solution. Engineers and chemists have long known using lithium metal as the anode in a rechargeable battery rather than the carbon materials used as the anode in conventional lithium-ion batteries increases energy density. But using lithium metal, a highly reactive solid, in conjunction with a liquid electrolyte is hazardous because it increases the chance of a reaction that can result in a fire or explosion. Lithium-ion batteries also require packaging to protect and cool them.

Lee and Stoldt solved the safety concerns of using lithium metal by eliminating the liquid electrolyte. Instead, the pair built a solid-state battery that uses a ceramic electrolyte to separate the lithium metal anode from the cathode. Because the solid-state battery is safer, it requires less protective packaging, which in turn reduces weight and extends range.

Research into the development of solid-state batteries has gone on for a couple of decades, but it has been difficult to create a solid electrolyte that allowed the ions to pass through as easily as a liquid electrolyte. “The last decade has seen a resurgence in the development of new solid electrolytes with ionic conductivities that rival their liquid counterparts,” Stoldt said.

The critical innovation added by Lee and Stoldt that allows their solid-state lithium battery to out-perform standard lithium-ion batteries is the construction of the cathode, the part of the battery that attracts the positively charged lithium ions once they’re discharged from the lithium metal. Instead of using a solid mass of material, Lee and Stoldt created a composite cathode — essentially small particles of cathode material held together with solid electrolyte and infused with an additive that increases electrical conductivity. This configuration allows ions and electrons to move more easily within the cathode.

 Last year, Lee and Stoldt partnered with Douglas Campbell, a small business and early stage product development veteran, to spin out Solid Power.

“We’re very excited about the opportunity to achieve commercial success for the all solid-state rechargeable battery,” said Campbell, president of Solid Power. “We’re actively engaging industrial commercial partners to assist in commercialization and expect to have prototype products ready for in-field testing within 18 to 24 months.”