2D porous Nb ₄ N ₅ @Nb ₂ C heterojunctions for high-performance Li-ion batteries

Abstract Constructing transition metal nitrides (TMNs) with a 2D porous structure is an effective strategy to alleviate their volume expansion and self-aggregation issues, eventually enhancing their electrochemical performance. However, very few studies have been reported up to now. Herein, 2D porous Nb ₄ N ₅ @Nb ₂ C heterojunctions are successfully synthesized from Nb ₂ C MXene precursor by employing a two-step nitridation method in NH ₃ atmosphere. Owing to the abundant active sites, fast Li-ions diffusion paths, and sufficient buffer space for releasing volume expansion, 2D porous Nb ₄ N ₅ @Nb ₂ C heterojunctions achieve high rate performance and excellent cycling stability, maintaining 109.2 mAh g ⁻¹ at 2 A g ⁻¹ after 800 cycles. This work provides a facile strategy for building 2D porous TMNs and their heterojunctions with excellent electrochemical performances.