Achieving Direct Electrochemical Oxidation of Carbon below 600oC through a Novel Direct Carbon Fuel Cell

TL;DR

This paper presents a novel 3-D solid-state anode design enabling efficient direct electrochemical oxidation of solid carbon at temperatures below 600°C, significantly improving performance and carbon utilization in DCFCs.

Contribution

Introduction of a 3-D textile anode architecture that enhances performance and carbon utilization in direct carbon fuel cells operating below 600°C.

Findings

Maximum power densities of 143, 196, and 325 mW/cm² at 500, 550, and 600°C.

Steady operation with ~0.13 W/cm² power density at 500°C and 86% carbon utilization.

Enhanced performance due to synergistic conduction and 3-D anode structure.

Abstract

Direct carbon fuel cells (DCFCs) are highly efficient power generators fueled by abundant and cheap solid carbons. However, the limited formation of triple phase boundaries (TPBs) within fuel electrodes inhibits their performance even at high temperatures due to the limitation of mass transfer. It also results in low direct-utilization of the fuel. To address the challenges of low carbon oxidation activity and low carbon utilization simultaneously, a highly efficient, 3-D solid-state architected anode has been developed to enhance the performance of DCFCs below 600C. The cells with the 3-D textile anode, Gd:CeO2-Li/Na2CO3 composite electrolyte, and Sm0.5Sr0.5CoO3 (SSC) cathode have demonstrated excellent performance with maximum power densities of 143, 196, and 325 mW cm-2 at 500, 550, and 600C, respectively. At 500C, the cells could be operated steadily with a rated power density of ~0.13 W cm-2 at a constant current density of 0.15 A cm-2 with a carbon utilization over 86%. The significant improvement of the cell performance at such temperatures attributes to the high synergistic conduction of the composite electrolyte and the superior 3-D anode structure which offers more paths for carbon catalytic oxidation. Our results indicate the feasibility of direct electrochemical oxidation of solid carbon at 500-600C with a high carbon utilization, representing a promising strategy to develop 3-D architected electrodes for fuel cells and other electrochemical devices.