Kraft Lignin Modification and Application as Aqueous Binder for Carbon Anode in Lithium Battery

Although lithium batteries contribute to a green energy economy, most of the materials used in their production are fossil-based. A way to diminish the carbon footprint is by utilizing sustainable and biobased products like lignin, which is highly abundant in nature and vastly produced industrially as a low-value side product in the paper and pulp industry. In the current work, chemically modified Kraft lignins (KL) with different chemical functionalities such as carboxymethyl and sulfomethyl were applied as binder materials for preparing active carbon-based electrodes for lithium metal lab-scale battery cells. The optimization of the lignin binders through functionalization allowed for a significantly enhanced aqueous processability and performance of anodic electrodes composed of hard carbon as the electroactive material and carbon black as the conducting additive. Battery performances were comparable with the state-of-the-art biopolymer binders carboxymethylcellulose (CMC) reaching specific capacity values of 170 mA h g-1. The functionalization shows an alternative approach to the valorization of lignin in high-tech applications.