Electrochemical performance of asymmetric supercapacitor with binder-free CoxMn3-xSe4 and radish-derived carbon electrodes using K3[Fe (CN)6] additive in electrolyte

For the development of high-energy portable electronic devices with long cycling life, herein, we provide an effective strategy of using a small quantity of K-3[Fe(CN)(6)] as a redox additive in aqueous KOH solution as the electrolyte, which greatly enhances the energy storage performance of positive electrode via faradaic transitions of redox pair at the electrode-electrolyte interface. Construction of nanoarchitectured CoxMn(3)-xSe(4) arrays on conductive carbon cloth (CC) substrate (CC/CMS arrays) by a facile one-step potentiostatic electrodeposition (chronoamperometry) process and their structural, morphological, and electrochemical characterizations are successfully demonstrated. The allied electron transport mechanism of K-3[Fe(CN)(6)] further enhancing the electrochemical performance of optimized CC/CMS array positive electrode in the KOH + K-3[Fe(CN)(6)] electrolyte is discussed in detail. Moreover, the novel CC/CMS-based asymmetric supercapacitor (ASC) device is assembled employing biomass-derived radish carbon (Radish-C) negative electrode (i.e., CC/CMS//Radish-C ASC) and separately evaluated in the electrolytes with and without redox additive. In the redox additive KOH + K3[Fe(CN)6] electrolyte, the ASC device delivers higher specific capacity (85.7 mAh g(-1)), energy density (64.3 Wh kg (-1)), and long-term charge-discharge lifespan (98.8% retention after 10,000 cycles) than that in the pristine KOH electrolyte. The practicality of CC/CMS//Radish-C ASC device in the redox additive electrolyte is also established in this work.

Automated summary

In this study, a strategy of using potassium ferricyanide as a redox additive in the electrolyte is proposed, which greatly enhances the energy storage performance of the positive electrode. Nanoarchitectured CoxMn(3)-xSe(4) arrays are successfully fabricated and applied in a novel asymmetric supercapacitor.