Synergistic Improvements in Ionic Conductivity, Diffusion Dynamics, and Transference Numbers for LaNiO3/MXene Supercapacitor Electrodes

Abstract

Supercapacitors are crucial for bridging energy storage gaps, offering rapid charge/discharge rates, long cycle life, and high power density, key for renewable energy systems and electric vehicles. This study incorporated MXene (Ti₃C₂T_x) into LaNiO₃ (PLNO) at 0, 10, 20, and 30 wt% via solvothermal synthesis. X-ray diffraction confirmed a simple cubic phase across all samples. BET analysis and FESEM revealed mesoporous structures and reduced grain sizes due to MXene inclusion, contributing to enhanced electrochemical performance. Elemental analysis via EDS matched expected stoichiometry. Cyclic voltammetry indicated battery-type behavior, with the LNO-III sample achieving the highest capacity of 541.60 C g⁻¹ at 2.5 mV s⁻¹. Galvanostatic charge/discharge profiles showed increasing discharge times with higher MXene content. The Ragone plot highlighted excellent energy and power densities of 84.30 Wh kg⁻¹ and 2125 W kg⁻¹ at 2.5 A g⁻¹. Long-term testing demonstrated strong cycle stability, with 88.12% retention over 10 000 cycles. Electrochemical impedance spectroscopy showed low charge transfer resistance (0.84 Ω), short relaxation time (17 ms), high ion diffusion rate (9.5 × 10⁻¹³ m² s⁻¹), good ionic conductivity (6.3 × 10⁻³ S cm⁻¹), and a transference number (t₊) of 0.3. These results confirm the potential of MXene-modified PLNO as a promising electrode for high-performance supercapacitors.