Trace tungsten dopants curb voltage fade in lithium-rich cathodes

Researchers from China’s Nankai University have developed a novel method to mitigate voltage fade in lithium-rich layered oxide (LRLO) cathodes, a promising material for next-generation lithium-ion batteries used in electric vehicles and grid storage. Voltage fade, a major challenge in these high-energy batteries, results from structural instability, transition-metal migration, and oxygen loss during high-voltage cycling. The team introduced trace amounts (sub-1 atomic percent) of tungsten (W⁶⁺) dopants into tetrahedral interstitial sites within the cathode’s crystal lattice—an unconventional doping site compared to the typical octahedral positions. Advanced imaging techniques confirmed tungsten’s unique placement, which exerts long-range Coulomb repulsion that suppresses transition-metal migration and stabilizes the structure over a region much larger than typical atomic-scale effects. This tetrahedral-site doping significantly reduces lattice strain and prevents oxygen vacancy formation and oxygen release, key factors that trigger voltage fade. Experimental results showed that tungsten-doped cathodes