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<p>This study systematically investigates the performance of MnO<sub>2</sub>​/EG composite electrodes, formed with expanded graphite (EG), to overcome the electrochemical limitations arising from the inherently low electrical conductivity of MnO<sub>2</sub>​. The composites, prepared with varying mass ratios from 0% to 40% EG content, are evaluated through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) analyses. The results reveal that the addition of EG effectively mitigates both the kinetic and structural limitations of MnO<sub>2</sub>​, leading to a synergistic enhancement in performance. Specifically, the M80E20 electrode, containing 20% EG, is identified as the optimal composition. It exhibits the highest specific capacitance of 328.7&#xa0;F g⁻¹ at 2 mV s⁻¹, the best rate capability with 47% capacitance retention at 100 mV s⁻¹, and superior cycling stability, showing 77% capacitance retention after 2000 cycles. Ragone analysis demonstrates that the symmetric device fabricated with this composite delivers a high energy and power density profile, suggesting that supercapacitor performance can be significantly enhanced. The findings indicate that the EG additive functions not merely as a conductive support but as a multifunctional structural backbone that accelerates ion and electron transport and preserves structural integrity.</p> Graphical Abstract <p></p>

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Systematic investigation of the electrochemical performance of MnO₂-based supercapacitors enabled by expanded graphite integration

  • 期刊论文

  • 发表日期：

    2026年3月1日

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  • Rukiye Taşdemir,
  • Zafer Çıplak,
  • Nuray Yıldız,
  • Kerim Yapici

摘要

This study systematically investigates the performance of MnO2​/EG composite electrodes, formed with expanded graphite (EG), to overcome the electrochemical limitations arising from the inherently low electrical conductivity of MnO2​. The composites, prepared with varying mass ratios from 0% to 40% EG content, are evaluated through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) analyses. The results reveal that the addition of EG effectively mitigates both the kinetic and structural limitations of MnO2​, leading to a synergistic enhancement in performance. Specifically, the M80E20 electrode, containing 20% EG, is identified as the optimal composition. It exhibits the highest specific capacitance of 328.7 F g⁻¹ at 2 mV s⁻¹, the best rate capability with 47% capacitance retention at 100 mV s⁻¹, and superior cycling stability, showing 77% capacitance retention after 2000 cycles. Ragone analysis demonstrates that the symmetric device fabricated with this composite delivers a high energy and power density profile, suggesting that supercapacitor performance can be significantly enhanced. The findings indicate that the EG additive functions not merely as a conductive support but as a multifunctional structural backbone that accelerates ion and electron transport and preserves structural integrity.

Graphical Abstract