Strategic integration of MXene into FeMnO3 matrix for superior energy density in hybrid supercapacitors elucidated via Dunn's model

Abstract

Integration of carbonaceous materials with transition metal oxides has emerged as a promising avenue across various applications, particularly in the framework of energy storage. Here, we report the synthesis of FeMnO₃ (FMO) and its composite with 10, 20, and 30% Ti₃C₂/MXene contents (denoted as FMO-I, FMO-II, and FMO-III respectively) by employing facile hydrothermal and solvothermal methods, respectively. Structural analysis showed that FMO exhibits a well-defined cubic crystal structure with high crystallinity, while morphological investigation revealed flake- and thread-like structures contributing to increased porosity. The FMO-III sample exhibited a maximum surface area of 39.46 m² g⁻¹, with an average pore size of 16.7 nm, as determined by Brunauer–Emmett–Teller analysis. Cyclic voltammetric measurements were conducted with a potential window of 0.0–0.5 V and scan rates spanning from 2.5 to 25 mV s⁻¹, validating the hybrid type nature of the FMO/Ti₃C₂ electrodes based on Dunn's model. Meanwhile, FMO-III demonstrated a noteworthy specific capacity of 1084.81 C g⁻¹ at a current density (J) of 3.22 A g⁻¹, which aligns closely with a theoretical capacity of 1215.33 C g⁻¹. In addition, an exceptional energy density of 75.33 Wh kg⁻¹ coupled with a power density of 806.45 W kg⁻¹ was disclosed. The optimized electrode material exhibited outstanding cycling stability, retaining 95% of its capacity and a coulombic efficiency of 98% over 2k cycles. Correspondingly, the Nyquist plot revealed a minimum resistance value of 0.99 Ω with the ionic conductivity of approximately 9.0 × 10⁻² S cm⁻¹. Hence, these superior findings underscore the potential of FMO-III as an advanced electrode material for hybrid capacitor applications.