Synergistic Doping and Coating Strategy for Boosting Na0.7MnO2 Cathode Performance in Sodium-Ion Batteries

• ZnO, NiO, and Al 2 O 3 thin films were coated on P2-type Na 0.7 MnO 2 particles by atomic layer deposition. • The combination of ALD and thermal treatment can achieve thin film coating on particle surface and promote element doping into the near-surface lattice. • The incorporation of Zn, Al, and Ni results in localized bonding environments and improves structural stability and interfacial integrity. • Coated cathodes exhibited superior cycling stability, rate capability, and Na + diffusion kinetics. • The ALD-assisted doping strategy effectively suppressed cathode electrolyte interface formation. Advancing sodium-ion battery (SIB) technology requires novel approaches to optimize cathode materials for improved electrochemical performance. In this study, we employ atomic layer deposition (ALD) to precisely modify the surface of P2-type Na 0.7 MnO 2 cathodes with different coating materials including ZnO, NiO, and Al 2 O 3 , followed by post-annealing at 750°C for 10 hours. The strategic combination of ALD and thermal treatment can achieve thin film coating on particle surface and promote element doping into the near-surface lattice, as confirmed by electron energy loss spectroscopy (EELS) analysis. The incorporation of Zn, Al, and Ni results in localized Mn–O–M (M = Zn, Al, Ni) bonding environments, which enhance structural stability and interfacial integrity. ZnO-coated cathodes exhibited exceptional cycling stability, Al 2 O 3 coatings offered excellent rate performance, and NiO coatings provided a balanced improvement in stability and capacity retention. These findings show that the functional enhancement of Na 0.7 MnO 2 is highly reliant on the coating material selection, enabling tailored performance enhancements for specific application requirements. This study emphasizes ALD as a powerful tool for realizing the full potential of SIB cathodes, paving the way for more efficient, long-lasting, and scalable energy storage systems.