A multi-institutional collaboration led by Tongji University has identified the key factors governing oxygen evolution in LiOH-based nonaqueous lithium-oxygen batteries, and shown that a systematic approach to catalyst, electrolyte and current collector design can boost oxygen recovery from near zero to approximately 75%.
The study, published in Nature Communications, addresses one of the fundamental challenges holding back lithium-air battery technology. LiOH-based Li-O2 cells offer a theoretical energy density of 3,707 Wh/kg, several times that of conventional lithium-ion batteries, and are inherently more tolerant of moisture and CO2 than the alternative Li2O2 chemistry. But until now, their reversibility has been poor, with near-zero oxygen recovery upon charging.
What they found
The team, led by Tao Liu at Tongji University, systematically analyzed the parasitic chemistry that degrades LiOH-based cells. They identified surface-bound hydroxyl radicals (OH) as the primary reactive oxygen species, in contrast to Li2O2-based cells, where singlet oxygen (1O2) is the main culprit. Because OH is surface-bound rather than solution-phase, its reactivity can be modulated through catalyst surface engineering.
The hydroxyl radicals attack both the electrolyte and the carbon support. Using 13C-labeled carbon, the team traced 65% of evolved CO2 to carbon corrosion, with electrolyte decomposition accounting for the remaining 35%. Carbon corrosion begins at just 3.5 V, well within the charging voltage range.
Three-pronged optimization
The team developed three complementary strategies:
First, an Fe-Co-Ni layered double hydroxide (FeCoNi LDH) catalyst that binds OH strongly, steering it toward productive oxygen evolution rather than side reactions. Bader charge analysis showed that OH on iron active sites has higher charge transfer than on ruthenium, making it less reactive and aggressive.
Second, a sulfolane-based electrolyte with superior resistance to electrophilic *OH attack, confirmed by density functional theory calculations of Fukui indices, outperforming conventional ethers, DMSO and DMA.
Third, a gold current collector that eliminates the carbon corrosion pathway entirely at voltages above 3.5 V, removing the primary source of irreversibility.
Combined, these strategies boosted oxygen recovery to approximately 75%, from a baseline of near zero. The discharge product was confirmed as LiOH by in situ X-ray diffraction, with no detectable singlet oxygen.
A paradox revealed
The work reveals a counterintuitive insight: higher overpotential can actually drive OH toward productive oxygen evolution rather than parasitic reactions. Simply lowering the charge voltage, a typical optimization goal, is insufficient if it makes OH more reactive toward the electrolyte.
The study provides rational design principles for future LiOH-based lithium-air batteries: oxidation-resistant solvents, strongly *OH-binding catalysts and non-carbonaceous current collectors. If scaled, the 4-electron oxygen chemistry could eventually enable practical, open-air lithium-air batteries that eliminate the need for oxygen cylinders and gas purification systems.
Sources:
1. Tang L, Lu Z, Gao Z, Lou X, Li J, Wen Y, Chen J, Zhu Z, Luo S, Zhou L, Wei G, Chen Z, Zhao H, Li T, Peng L, Li F, Liu T. “Unravelling the key factors governing O2 evolution upon charging a reversible LiOH-based nonaqueous Li||O2 battery.” Nature Communications. 2026. DOI: 10.1038/s41467-026-75284-2