Before a lithium-ion battery leaves the factory, it must pass through formation: an initial series of charge and discharge cycles that builds the protective layers governing its lifetime performance. The step accounts for roughly one third of production costs and about a quarter of factory floor space, yet manufacturers have had no live view of the chemistry involved. Cornell researchers, working with the upstate New York battery company Charge CCCV (C4V), have now provided one.
Writing in Energy Storage Materials, the team led by chemical engineer Vibha Kalra paired operando Raman spectroscopy, which tracks interface chemistry during operation, with operando electrochemical impedance spectroscopy, which measures how the layers' resistance evolves. The combination revealed that slower charging produced more uniform, inorganic-rich protective layers, that discharge rates could safely be increased, and that key resistance measurements stabilised after about one and a half cycles.
From these observations the researchers derived two accelerated manufacturing protocols, which performed comparably to C4V's conventional process when tested at the company's Binghamton facility. The approach reduces formation time by up to 60 per cent and overall power use by an estimated 10 to 15 per cent, with projected savings of up to 100 million dollars annually for a factory producing more than 10 gigawatt-hours of cells. The work was supported through the National Science Foundation's Energy Storage Engine in upstate New York.