Direct lignin fuel cell for power generation

Lignin, the second most abundant component after cellulose in biomass, has been examined in this study as a fuel for a direct conversion into electricity using direct carbon fuel cell (DCFC). Two different types of industrial lignins were investigated: lignosulphonate (LS) and kraft lignin (KL), either directly in their commercial forms, after their blending with commercial active carbon (AC) or after alternation of their structures by a pH adjustment to pH 10. It has been found that the open circuit voltage (OCV) of the DCFC could reach around 0.7 V in most of the trials. Addition of active carbon increased the maximum current density from 43∼57 to 85∼101 mA/cm ². The pH adjustment not only increased the maximum current density but also reduced the differences between the two types of lignins, resulting in an OCV of 0.680-0.699 V and a maximum current density of 74∼79 mA/cm ² from both lignins. Typical power density was 12 (for KL +AC) and 24 mW cm ^-2 (for LS +AC). It has been concluded that a direct lignin fuel cell is feasible and the lignin hydrophilicity is critical for the cell performance.