Empowering lithium-ion storage: unveiling the superior performance of niobium-based oxide/perovskite heterojunction with built-in electric field.

The increasing demand for high-performance electrode materials in lithium-ion batteries has driven significant attention towards NbO due to its high working voltage, large theoretical capacity, environmental friendliness, and cost-effectiveness. However, inherent drawbacks such as poor electrical conductivity and sluggish electrochemical reaction kinetics have hindered its lithium storage performance. In this study, we introduced KCaNbO into NbO to form a heterojunction, creating a built-in electric field to enhance the migration and diffusion of Li, effectively promoting electrochemical reaction kinetics. Under the regulation of the built-in electric field, the charge transfer resistance of the KCaNbO/NbO anode decreased by 3.4 times compared to pure NbO, and the Li diffusion coefficient improved by two orders of magnitude. Specifically, the KCaNbO/NbO anode exhibited a high capacity of 276 mAh g under 1 C, retaining a capacity of 128 mAh g even at 100 C. After 3000 cycles at 25 C, the capacity degradation was only 0.012% per cycle. Through combined theoretical calculations and experimental validation, it was found that the built-in electric field induced by the heterojunction interface contributed to an asymmetric charge distribution, thereby improving the rates of charge and ion migration within the electrode, ultimately enhancing the electrochemical performance of the electrode material. This study provides an effective approach for the rational design of high-performance electrode materials.