Pizza-like heterostructured Ti3C2Tx/Bi2S3@N-C with ultra-high specific capacitance as a potential electrode material for aqueous zinc-ion hybrid supercapacitors

Abstract The aqueous zinc-ion hybrid supercapacitor (ZIHC) has become an emerging energy storage device due to its safety and low cost. Herein, a new pizza-like heterostructure of Ti3C2Tx intercalated by N-doped-carbon-wrapped Bi2S3 is fabricated by in-situ growth. The specific capacitance of Ti3C2Tx/Bi2S3@N-C electrode is as high as 653 F g−1 at 1 A g−1, which is significantly higher than other binary composites or similar MXene-based materials in literature. The ZIHC are assembled with Ti3C2Tx/Bi2S3@N-C and Zn foil as electrodes, possessing high specific capacitance of 150.33 F g−1 at 1 A g−1, and a maximum energy density of 46.98 W h kg−1 at a power density of 750 W kg−1. The excellent performance of Ti3C2Tx/Bi2S3@N-C is mainly attributed to the synergistic effect of the three components: (a) highly conductive Ti3C2Tx as the substrate shortens the electron transport path; (b) the in-situ growth of Bi2S3 on Ti3C2Tx layers makes full use of Bi2S3 active sites; (c) the innovative introduction of dopamine can not only make Bi(NO)3 evenly dispersed, but also form the “cross-bridge” N-C film, which further improves the binding between Ti3C2Tx substrate and Bi2S3 and reduces the internal resistance greatly. This study proposes a new in-situ growth strategy for a ternary heterostructure, which may offer a new avenue for the development of high-performance electrode materials.