Bidirectional ion-supply interface enables efficient active material utilization in wood-derived thick electrodes for...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• High-volumetric-energy thick electrodes are crucial for compact energy storage devices.
• Conventional carbon scaffolds limit electrolyte access, hindering ion kinetics and bulk utilization in thick electrodes.

Purpose of the Study:

• To design a novel wood-derived carbon/NH4V4O10 composite with a bidirectional ion-supply interface.
• To improve electrolyte access and ion transport in thick electrodes for enhanced energy storage.

Main Methods:

• Fabrication of a wood-derived carbon/NH4V4O10 composite with a bidirectional ion-supply interface.
• Electrochemical characterization including cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy (EIS).
• Warburg analysis to quantify ion transport coefficients.

Main Results:

• The composite exhibited a bidirectional ion-supply interface, creating ion-enrichment zones on both sides of the electrode.
• Achieved a 415% increase in active-material utilization at 17.6 mg cm⁻² and eliminated "dead volume".
• Demonstrated a volumetric capacitance of 37.1 F cm⁻³ at 1 mA cm⁻², a 16-fold increase in the apparent NH4+ transport coefficient, and a hybrid capacitor energy density of 4.1 mWh cm⁻³.

Conclusions:

• The bidirectional ion-supply interface significantly enhances NH4+ transport and active material utilization in thick electrodes.
• The activated carbon scaffold acts as an electrolyte reservoir, maximizing active site accessibility.
• This design provides a blueprint for high-loading, high-energy-density ammonium-ion storage systems.