Cobalt-free, high-nickel batteries have been marketed as a cheaper and greener route to longer-range electric vehicles, but new research from Hanyang University shows that a manufacturing step long considered routine can quietly undermine that promise. A team at the university’s ERICA campus has found that exposing battery precursor materials to air alters the chemistry of manganese, the very element added to stabilise high-nickel cathodes, creating surface defects that can nearly double the rate of capacity fading during extended cycling. The findings, published in Energy and Environmental Science on 23 June 2026 following online release on 13 May 2026, also point to a fix: adjusting lithium content during synthesis can suppress the defects and restore stability. Modified cathodes produced this way retained more than 90% of their capacity, offering manufacturers a practical route to more durable, high-energy batteries without redesigning production lines.

A Weakness Hidden In Plain Sight

The research, led by Professor Jin Ho Bang alongside PhD scholar JinHa Shim, examined manganese-coated nickel-core cathodes, a design intended to protect high-nickel materials while reducing reliance on expensive and ethically fraught cobalt. The team discovered that storing precursor materials in air-exposed conditions oxidises manganese on particle surfaces, producing defective regions rich in what the researchers describe as Jahn-Teller distorted manganese species. These distorted surfaces prove highly reactive, driving electrolyte decomposition, transition-metal dissolution and damaging reactions with the graphite anode.

In nickel-rich systems, the consequences are pronounced: the hidden defect accelerates capacity loss during extended cycling tests, effectively undermining the protective role manganese was meant to play.

Manganese As Catalyst, Not Cure

The study reframes manganese’s role in high-nickel battery chemistry, showing that under uncontrolled precursor conditions, the element intended to shield the cathode can instead become the source of instability.

Prof. Jin Ho Bang, Professor of Energy and Bio Sciences at Hanyang University, said:

“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,” explains Prof. Bang, “Even small variations in precursor storage history can substantially affect battery stability.”

A Practical Fix Without Costly Redesign

Rather than pointing manufacturers toward expensive coatings or overhauled production lines, the team’s solution centres on a comparatively simple adjustment: increasing the amount of excess lithium during synthesis. This suppresses the formation of the defective surface phase and restores stable manganese-oxygen bonding, allowing cathodes to hold on to the vast majority of their capacity over extended use.

The researchers argue that eliminating cobalt from battery chemistry, while valuable, is not by itself sufficient to guarantee durability. Understanding how manganese chemistry evolves during manufacturing, they suggest, matters just as much.

Prof. Jin Ho Bang, Professor of Energy and Bio Sciences at Hanyang University, added:

“Our results show that even minor variations in precursor history can have major consequences for battery performance, making precursor management an important consideration for large-scale manufacturing,”

Implications Beyond The Car Park

The team’s conclusions extend beyond passenger vehicles. Batteries built to this improved standard could also serve large-scale energy storage systems, which similarly require stable, high-energy cells to support renewable energy applications as grids lean further on intermittent generation.

By tracing the problem back to precursor handling rather than the finished cell, the study gives manufacturers a lever they can pull early in production, potentially extending vehicle battery lifetimes and strengthening the broader case for cobalt-free chemistries as the industry scales up. The work was carried out at Hanyang University ERICA, and published through Energy and Environmental Science, a journal of the Royal Society of Chemistry.