From Batteries to Agriculture, Stanford Energy Fellows' Ingenuity Illuminates

By Mark Golden and Eylül Bilgin

The first annual Stanford Energy Postdoctoral Fellowship Symposium opened with encouragement from Richard Swanson, founder of solar company SunPower and former Stanford University faculty member. "I find when I talk to students that they're very energizing, and I come away really pumped up," Swanson said, before playfully adding, "I hope you don't disappoint.”

Eight energy fellows presented their latest research results. Four Stanford professors, a Northwestern University professor, and Swanson gave mostly high-level observations about the future of sustainable, affordable, secure energy. The symposium demonstrated how inventive science becomes when combining disparate fields like batteries and carbon-neutral fuels, electric grids and markets, or plasma physics and agriculture. 

“Requiring new PhD’s to have at least two mentors in two different departments set the foundation for the program’s interdisciplinary structure, along with regular scientific interactions among all the fellows,” said Yi Cui, the faculty director of the postdoctoral fellowship, which he created in 2022 when he directed Stanford’s Precourt Institute for Energy.

Stolen electrons and solid-state batteries

Energy fellow John "Jack" Holoubek tackled two seemingly unrelated problems through electrolyte modification. CO2 electrolyzers waste current by producing hydrogen instead of intended products. Grid-scale zinc batteries, meanwhile, produce unwanted hydrogen because water molecules steal electrons. In both cases, Holoubek’s solution is to modify the electrolyte, not the metal. 

For the CO2 electrolyzer, he replaced sodium cations with a trivalent aluminum complex to get the desired products instead of hydrogen efficiently. For the zinc batteries, Holoubek designed a new low-cost organic electrolyte to eliminate hydrogen generation.

If liquid electrolytes cause headaches, why not ditch them? That is Yukio  Cho’s wager for using a solid electrolyte to advance lithium-sulfur batteries, the theoretical energy density of which could eclipse today’s lithium-ion cells. Historically, solid-state lithium-sulfur batteries have faced challenges, most notably the sluggish chemical movement that hampers their ability to store and release energy quickly.