Facile Preparation of Three-Dimensional Cubic MnSe₂/CNTs and Their Application in Aqueous Copper Ion Batteries

Transition metal sulfide compounds with high theoretical specific capacity and excellent electronic conductivity that can be used as cathode materials for secondary batteries attract great research interest in the field of electrochemical energy storage. Among these materials, MnSe₂ garners significant interest from researchers due to its unique three-dimensional cubic structure and inherent stability. However, according to the relevant literature, the performance and cycle life of MnSe₂ are not yet satisfactory. To address this issue, we synthesize MnSe₂/CNTs composites via a straightforward hydrothermal method. MnSO₄·H₂O, Se, and N₂H₄·H₂O are used as reactants, and CNTs are incorporated during the stirring process. The experimental outcomes indicate that the fabricated electrode demonstrates an initial discharge specific capacity that reaches 621 mAh g^-1 at a current density of 0.1 A g^-1. Moreover, it exhibits excellent rate capability, delivering a discharge specific capacity of 476 mAh g^-1 at 10 A g^-1. The electrode is able to maintain a high discharge specific capacity of 545 mAh g^-1 after cycling for 1000 times at a current density of 2 A g^-1. The exceptional electrochemical performance of the MnSe₂/CNTs composites can be ascribed to their three-dimensional cubic architecture and the 3D CNT network. This research aids in the progression of aqueous Cu-ion cathode materials with significant potential, offering a viable route for their advancement.