Molten-salt-mediated crystal facet engineering for high-performance single-crystal nickel-rich cathode materials in lithium-ion batteries

Nickel-rich layered oxide cathodes are promising candidates for lithium-ion batteries due to high energy density and cost efficiency. However, their utilization is constrained by structural instability, slow lithium-ion transport, and capacity degradation under high cut-off voltage cycling. This investigation employed a molten-salt-mediated synthesis strategy to fabricate single-crystal nickel-rich layered oxide cathodes (SCNCMs) with controlled crystallographic plane exposure. Anion-regulated crystal growth adjusted the (104) plane exposure to enhance Li⁺ ion diffusion and mitigate the formation of oxygen vacancies. Theoretical calculations and experimental results confirmed that increased (104) plane exposure improved electrochemical performance, mechanical strength, and cycling stability. Pouch-type full-cell tests demonstrated that the SCNCM prepared using KBr (SC-B) with a higher (104) exposure exhibited exceptional long-term cycling stability compared to that of the pristine SCNCM prepared using traditional KCl (SC-C). After 600 cycles, SC-B retained 82.11 % of its initial capacity, whereas SC-C lost over 65 %. SC-B also demonstrated superior rate capability under high-power conditions. Theoretical modeling revealed that facet modulation is crucial for lithium-ion distribution and stress evolution, highlighting the importance of crystallographic control on the cathode performance. These findings provide a framework for high-performance single-crystal cathodes and insights into the structural optimization of next-generation lithium-ion battery materials.