Overcoming Ion Transport Barrier by Plasma Heterointerface Engineering: Epitaxial Titanium Carbonitride on Nitrogen‐Doped TiO₂for High‐Performance Sodium‐Ion Batteries

Abstract Anatase TiO₂is a promising anode material for lithium‐ion batteries (LIBs) and sodium‐ion batteries (SIBs) due to its high specific capacity, low cost, and excellent cycle stability. However, low electrical conductivity and poor Na⁺ion transport in TiO₂limit its practical applications. Here, substantially boosted Na⁺ion transport and charge transfer kinetics are demonstrated by constructing a near‐ideal non‐rectifying titanium carbonitride/nitrogen‐doped TiO₂(TiC_xN_1–x/N‐TiO₂) heterostructure. Owing to the fast plasma effects and metastable hybrid phases, the TiC_xN_1–xis epitaxially grown on TiO₂. Energy band engineering at the interface induces high electron densities and a strong built‐in electric field, which lowers the Na⁺diffusion barrier by a factor of 1.7. As a result, the TiC_xN_1–x/N‐TiO₂electrode exhibits excellent electrochemical performance. The reversible specific capacities at rates of 0.1 and 10 C reach 312.3 and 173.7 mAh g⁻¹, respectively. After 600 cycles of charge and discharge at 10 C, the capacity retention rate is 98.7%. This work discovers an effective non‐equilibrium plasma‐enabled process to construct heterointerfaces that can enhance Na⁺ion transport and provides generic guidelines for the design of heterostructures for a broader range of energy storage, separation, and other devices that rely on controlled ionic transport.