Interface-engineered CoMoN/MXene hybrids with enhanced discharge ion-transport characteristics for advanced supercapattery applications

Abstract The development of advanced energy storage systems (ESSs) that integrate the high energy density of batteries with the high-power density of supercapacitors has attracted considerable attention. In this study, an interface-engineered cobalt molybdenum nitride (CoMoN)/Ti 3 C 2 T x MXene hybrid with a hierarchical nanosheet-stacked architecture (CMN5M) is reported for high-performance supercapattery applications. Electrochemical analyses reveal distinct ion storage behaviors in the pristine CoMoN and hybrid electrodes. Diffusion coefficient ( M D ) analysis based on galvanostatic intermittent titration technique (GITT) reveals distinct ion-transport characteristics during charging and discharging. Pristine CoMoN exhibits relatively higher apparent ion diffusivity during charging, whereas the CoMoN/MXene hybrid shows enhanced apparent ion transport during discharge. These differences suggest that the conductive MXene framework and engineered interfaces facilitate ion transport in the hybrid electrode, with possible K⁺ participation during the discharge process. Ex situ characterization further confirms reversible surface phase evolution between CoOOH and Co(OH) 2 during charge-discharge cycling, forming a mixed-phase interface that contributes to structural stability and sustained electrochemical performance at high current densities. Supported by density functional theory (DFT) migration barrier calculations, Raman analysis, and suppressed Mo dissolution, the results demonstrate that MXene plays a role in enhancing ion transport kinetics. This study provides mechanistic insight into interface-regulated ion transport in bimetallic nitride/MXene hybrids and highlights their potential for advanced hybrid energy storage systems.