Understanding the degradation of single-crystal LiNiO2 cathodes under stressed conditions

Single-crystalline LiNiO2 (SC-LNO) is a promising cobalt-free lithium-ion battery cathode candidate for future high-energy-density applications. FutureCat project researchers – including teams from the Universities of Warwick and Sheffield and Diamond Light Source – devised cathode engineering strategies to achieve high-performance with long lifetime under industrially relevant operating conditions. They investigated prototype high-mass-loading SC-LNO–graphite single-layer pouch cells cycled under stressed operating conditions using operando and postmortem X-ray characterisation techniques.

The study found that SC-LNO particle cracking is not a major contributor to the reduction of electrochemical performance. Even after prolonged and stressed cycling, the single-crystal particles remained structurally intact, with only limited cracking observed. Instead, the cycling-induced surface reconstruction at the cathode particles results in a dense rock salt-like layer, less than 10 nm thick, that creates a kinetic barrier that slows lithium-ion diffusion and reduces active lithium inventory, thus reducing performance. The bulk structural order is largely preserved with no notable bulk crystallographic changes.

The findings underscore the importance of cathode surface engineering to mitigate particle surface reconstruction, thereby extending cycle life in next-generation cobalt-free lithium-ion batteries.

The research, published in Advanced Energy Materials, provides critical design principles for improving SC-LNO performance and informs broader strategies for stabilising nickel-rich cathodes under high-voltage operation.

Image: Synthetic scale up of precursor materials for LiNiO₂ cathode material at WMG with Graduate Trainee Engineer Micheal Fu featured.

Case study published December 2025.