The People Running Innovative Battery Maker SES AI

Last year, Kang Xu, a top U.S. expert on battery electrolytes, noticed a stark change in how U.S. passport authorities were treating him when he returned from trips abroad. Born in China, Xu is a naturalized U.S. citizen, earned his doctorate in chemistry at Arizona State University, worked for 26 years—his entire career—as a scientist at the U.S. Army Research Lab, where he was known as Conrad, and wrote what many consider the seminal university textbook on electrolytes. But now, whenever he returned home from conferences overseas, airport authorities routinely separated him from American colleagues with whom he was traveling and questioned him: Why did you leave the country? Where did you go? Who did you meet? On successive trips, security officers searched Xu’s wallet and baggage. It seemed to him the authorities were only checking passengers with Chinese names. At the lab, too, Xu felt an atmosphere of suspicion amid a wave of federal investigations of Chinese scientists. Last summer, he decided to retire.

Before cutting the cord, Xu had been speaking with Qichao Hu, CEO of Massachusetts-based lithium metal battery developer SES AI. Xu’s expertise matched a position Hu was seeking to fill—someone to lead a machine-learning effort to discover new electrolytes, the critical component for preventing fires in lithium metal batteries. In August, Xu began work as SES AI’s chief scientist. “I retired in the midst of this geopolitical chaos,” Xu told me. “I became very unhappy. It was at that moment that Qichao extended his hand, and I am very happy here.”