Layer-on-layer construction of amorphous cobalt-lanthanum sulfide arrays in situ grown on MXene‒C3N5 matrix for high energy density supercapacitors

Abstract

Herein, a hierarchical multicomponent nanocomposite is established by in situ depositing vertically aligned Co-La-S nanoarrays on MXene‒N-rich C 3 N 5 ‒coated nickel foam (NF) by a convenient electrodeposition technique, forming a heterogeneous-structured layer-on-layer Co-La-S/MX-CN electrode for supercapacitors. The intimate-connected heterostructure yields unique hierarchical network architectures and large specific surface area, exposing rich electroactive sites and numerous short electrons/ions diffusion paths to guide Faradaic redox reactions. The conducting MX-CN junction and dense electronic interactions at the interface facilitate the electron transfer dynamics. Benefiting from the synergistic effect of intrinsic compositional and structural characteristics, the free-standing Co-La-S/MX-CN heterostructure electrode exhibits a high specific capacity of 1 016.6 C ​g −1 (1 848.3 ​F ​g −1 ) at 1 ​A ​g −1 , remarkable rate performance of ∼673 ​C ​g −1 (1 223.6 ​F ​g −1 ) at 50 ​A ​g −1 , and outstanding capacity retention of 80.2% after 8 000 cycles. Upon integration into an asymmetric hybrid supercapacitor (AHSC) device, the configured Co-La-S/MX-CN//MX-CN realizes an elevated energy density of 86 ​Wh kg −1 at a power density of 800 ​W ​kg −1 . After enduring 15 000 cycles at a higher discharge current (20 ​A ​g −1 ), the capacitance retention rate reaches 74.3%, revealing appreciable lifespan stability. This work underscores an attractive approach to exploring low-cost heterogeneous-structured nanomaterials for supercapacitor applications.