Prussian Blue Nanolayer-Embedded Separator for Selective Segregation of Nickel Dissolution in High Nickel Cathodes

Transition metal layered oxides (LiNiCoMn_1-O₂, NCM) have been considered as one of the most promising cathodes for lithium-ion batteries used in long-mileage electric vehicles and energy storage systems. Despite its potential interest, dissolved transition metal (TM) ions toward anode sides can catalyze parasitic reactions such as electrolytic decomposition and dendritic Li growth, ultimately leading to catastrophic safety hazards. In this study, we demonstrate that Prussian Blue (PB) nanoparticles anchored to a commercial PE separator significantly reduce cell resistance and effectively suppress TM crossover during cycling, even under harsh conditions that accelerate Ni dissolution. Therefore, using a PB-coated separator in a harsh condition to intentionally dissolve Ni²⁺ ions at a high cutoff potential of 4.6 V, NCM||graphite full cells maintain 50.8% of their initial capacity at the 150th cycle. Scalable production of PB-coated separator through the facile synthetic methods can help establish a new research direction for the design of high-energy-density batteries.