Cornell finds a way to cut a costly battery factory step by up to 60% by watching it in real time

Cornell University researchers have found a way to shorten one of the slowest and most expensive steps in making lithium-ion batteries by up to about 60%, the Cornell Chronicle reported on 28 October. The work, done with the battery company Charge CCCV (C4V), was published in Energy Storage Materials.

The slow first charge of every battery

Before a new battery leaves the factory, it goes through formation: its first charge and discharge cycles, during which protective layers build up inside the cell. Formation accounts for about one-third of production costs, a quarter of factory floor space and a quarter of electricity use, according to the article.

Manufacturers usually tune formation by trial and error. “Evaluating formation processes is typically very trial and error,” said Vibha Kalra, professor of chemical engineering at Cornell and the study's principal investigator.

Watching the protective layer form

Instead of testing batteries only after formation, the team watched the process as it happened, using two techniques at once: operando Raman spectroscopy, which uses laser light to identify the chemicals forming inside the cell, and electrochemical impedance spectroscopy, which measures its electrical resistance.

They found that charging more slowly produced more uniform protective layers rich in inorganic compounds, that the discharge steps could be sped up, and that key resistance measurements settled after just 1.5 cycles. Based on that, they designed two faster formation protocols that kept battery performance comparable to C4V's conventional process. Lead author Jantakan Nedsaengtip did the work as a master's student.

“Formation time is a high-cost part of battery manufacturing, and this work of the Kalra group is a great step forward.” — Stan Whittingham, 2019 Nobel laureate in chemistry, NSF Energy Storage Engine

Estimated savings, not yet a factory result

C4V estimates the change could cut a battery plant's overall power use by 10% to 15%, and that a factory producing more than 10 gigawatt-hours of batteries a year could save up to $100 million in formation costs. Shalabh Gupta, C4V's system engineering manager, described those figures as estimates. “This work demonstrates why strong partnerships between research institutions and cell manufacturers are so important for moving the battery industry forward,” he said. The tests used battery materials supplied by C4V, and the protocols were validated at its facility in Binghamton, New York, not on a full production line.

The research is part of the Upstate New York Energy Storage Engine, a regional innovation program funded by the US National Science Foundation and led by Binghamton University, with Cornell as a core partner. The article did not say when C4V might use the faster protocols in production. Cheaper batteries matter for grid storage too; in India, ACME Solar switched on 437 MWh of battery storage in Rajasthan.