Study links air exposure during battery manufacturing to faster degradation

Exposing precursor materials to air during the manufacturing of high-nickel, manganese-coated cathode batteries can trigger chemical changes that accelerate battery degradation, according to a new study by researchers at Hanyang University in South Korea.

The scientists found that manganese, an element commonly used to stabilize high-nickel cathodes, can become a source of instability under certain manufacturing conditions. Storage of precursor materials in air-exposed environments oxidizes manganese on the particle surface, forming defective regions with what the researchers called “Jahn-Teller distorted” manganese species.

These distorted surfaces are more reactive, leading to electrolyte breakdown and other degradation processes, the study said. In nickel-rich battery systems, the researchers said this defect can nearly double the rate of capacity fading during extended cycling tests.

“We found that a manganese-rich shell, which is normally introduced to protect high-nickel cathodes, can instead become a catalyst for degradation if the precursor chemistry is not carefully controlled,” said Jin Ho Bang, professor in the Department of Energy and Bio Sciences at Hanyang University and lead of the study. “Even small variations in precursor storage history can substantially affect battery stability.”

The researchers said increasing the amount of excess lithium during synthesis suppressed the defect formation and restored stable manganese-oxygen bonding, allowing modified cathodes to retain more than 90% of their capacity in testing.

The study, “Precursor-driven Jahn-Teller distortion as a hidden origin of surface instability in Mn-stabilized Ni-rich cathodes,” was published in the journal Energy and Environmental Science.

The findings echo earlier research into how moisture exposure degrades nickel-rich battery materials, underscoring that precursor handling remains an underappreciated variable in cathode manufacturing.