Highly efficient utilization of walnut shell biochar through a facile designed portable direct carbon solid oxide fuel cell stack

The direct carbon solid oxide fuel cell (DC-SOFC) is a green and efficient energy conversion device with all-solid-state structure, which can convert carbon fuel into electricity directly. Recently, using biomasses as fuels for DC-SOFC has become fascinating due to their abundance and renewable property. However, it usually provides inferior performance compared to that with gas fuel feeding (hydrogen). Here, we report a promising and high-performing tubular segmented-in-series YSZ electrolyte-supported DC-SOFC stack. Thereinto, the YSZ electrolyte supports are fabricated by dip-coating and both pure walnut shell biochar and Fe-loaded biochar are used as fuels. The single cell can achieve a maximum power density of 147 mWcm(-2) at 800 degrees C and it is improved to 205 mW cm(-2) as FenOm catalyst is loaded on the biochar fuel. Furthermore, a two-cell-stack of DC-SOFC operated with Fe-loaded walnut shell char is assembled and tested. It delivers an outstanding performance, with an OCV of 1.98 V, an output power of 1.11 W and a maximum volumetric power density of 505 mW cm(-3) at 800 degrees C, indicating high potentials for developing into a high performance battery for portable or distributed applications. (C) 2021 Elsevier Ltd. All rights reserved.