Defect-regulated MnS@Ni_0.654Co_0.155Se_1.234S_0.101 structures: A novel approach to unlock energy storage potential in supercapacitors

Transition metal sulfides (TMSs) have significant potential in energy storage applications due to their high theoretical capacity and diverse reaction mechanisms. However, performance limitations in supercapacitors arise from various intrinsic defects, including low active material utilization and poor cycling stability caused by unstable electrical conductivity. To address these issues, this paper incorporates selenium atoms into sulfides, aiming to leverage selenium's high conductivity to enhance the electroactivity of transition metal sulfides. This approach improves both the conductivity of sulfides and the ion transport rate as well as enhances structural stability. Furthermore, a hierarchically porous structure of metal-organic framework (MOF) is synergistically optimized to augment the composite's energy storage capacity. The resulting MnS@NiCoSeS-1 composite demonstrates excellent electrochemical performance, achieving a specific capacity of 901.0 C g^-1 at 1 A g^-1 in a three-electrode configuration, with a capacity retention of 82.6 % after 10,000 cycles at 3 A g^-1. Additionally, the hybrid supercapacitor (HSC) constructed from this composite exhibits a high specific energy of 78.85 Wh kg^-1 at a power density of 775.2 W kg^-1. These findings validate the effectiveness of co-doping strategies for optimizing active material utilization and provide novel insights into the design of supercapacitors with both high energy and power densities.