A Flow-Through Membraneless Microfluidic Zinc-Air Cell

Area of Science:

• Electrochemistry
• Materials Science
• Microfluidics

Background:

• Development of efficient and durable energy storage devices is crucial for microscale applications.
• Membraneless microfluidic fuel cells offer advantages in simplicity and cost.
• Zinc-air cells are a promising technology due to high energy density.

Purpose of the Study:

• To demonstrate the proof of concept for a functional membraneless microfluidic zinc-air cell (μZAC).
• To investigate the effect of electrodeposited zinc thickness on electrode activity and durability.
• To evaluate inexpensive manganese-based materials as cathodes for improved cell performance.

Main Methods:

• Fabrication of porous carbon electrodes with varying zinc electrodeposition times using chronoamperometry.
• Optimization of cell parameters (KOH concentration, flow rate) using Pt/C cathode.
• Evaluation of α-MnO2 and Mn3O4 spinel as alternative cathodic materials.
• Characterization of electrode morphology using transmission electron microscopy (TEM).
• Analysis of material activity via density of state (DOS) calculations.

Main Results:

• Achieved functional membraneless microfluidic Zn-air cell (μZAC) with flow-through arrangement.
• Optimized Zn electrode thickness (3.3–34.8 μm) influenced cell performance.
• Manganese-based cathodes (α-MnO2 and Mn3O4) yielded high cell voltages (1.39 V and 1.35 V) and power densities (308 and 317 mW cm-2).
• α-MnO2 demonstrated superior performance compared to Mn3O4 and Pt/C, attributed to electronic structure.

Conclusions:

• The developed μZAC demonstrates a viable platform for microscale energy storage.
• Electrodeposition of Zn on porous carbon electrodes effectively modulates cell performance.
• Inexpensive manganese-based materials, particularly α-MnO2, offer competitive cathodic performance for μZACs.
• This work paves the way for cost-effective and efficient micro-energy devices.