A low temperature and high-power density lignin flow fuel cell via an efficient CoMn-LDH electrocatalyst with superhydrophilic intercalation

Abstract

Lignocellulose flow fuel cells are promising technologies for large scale generation of renewable electricity at low temperature. However, most of them have low electron transfer kinetics and require pre-reaction and redox mediators in anolytes for a liquid-phase catalytic reaction, which leads to low power density, energy consumption and resource waste. Herein, we develop a new low temperature and high-power density lignin flow fuel cell (LFFC) catalyzed by CoMn-LDH electrocatalysts with superhydrophilic intercalation on the anode to efficiently degrade lignin and transfer electrons rapidly. The experiments and DFT calculations show that CoMn-LDH exhibits high adsorption capacity for lignin due to its superhydrophilic intercalation, and has good electrical conductivity due to the greater overlap of antibonding orbitals and high continuity at the Fermi level. Moreover, the abundant oxygen defects of CoMn-LDH can depolymerize lignin effectively. Thus, the prepared CoMn-LDH electrocatalyst enables fast charge transfer and high catalytic efficiency. The power density of the designed LFFC reached 269.3 mW cm⁻², and the generated electrical energy is 294.7 mW h based on 1.0 g of lignin, which are obviously higher than those of the reported LFFCs. Furthermore, it can work stably for more than 9 h at 0.3 V and 413.5 mA cm⁻², and successfully power a 1.5 V LED pattern with only a 1 cm² active membrane. It presents a promising approach for developing high-power density LFFCs towards a sustainable society.