Atomic modulation of Na⁺ transport channels to enhance rate and cycling performance of tunnel-type sodium manganese oxides

Tunnel-structured Na_0.44MnO₂ is considered a promising cathode material for large-scale sodium-ion batteries due to its low cost, excellent air stability, and compatibility with sodium compensation strategies; however, its practical application is hindered by sluggish Na⁺ diffusion kinetics and poor cycling stability arising from intrinsically constrained ion migration pathways and increased structural disorder during cycling. In this work, a tunnel-type Na_0.44Mn_0.89Cu_0.01Ti_0.1O₂ cathode is rationally designed via atomic modulation, which effectively widens Na⁺ diffusion channels and constructs preferential transport pathways, thereby reducing the Na⁺ migration energy barrier and improving the rate performance. Meanwhile, the ordering of Mn–O bonds is improved during charge–discharge processes, leading to enhanced structural stability and prolonged cycling life. As a result, the material delivers a high capacity retention of 90.4% after 1000 cycles at a high current density of 600 mA g⁻¹, demonstrating that the dual-substitution strategy is an effective approach for developing high-rate and long-lifespan cathode materials for rechargeable sodium-ion batteries.