Improving the Conductivity of Graphite-Based Lithium-Ion Battery Anodes Using Polyaniline–Alginate Blends

Abstract

This investigation shows the effect of blending sodium alginate (NaAlg) and a conducting polymer, polyaniline (PANI), in lithium-ion battery (LIB) anodes. We demonstrate here that inclusion of the PANI into the binder improves the connectivity of the composite, resulting in better performance. Additionally, the blends are easily formulated without sophisticated methods or additional equipment. When these binders were combined into electrodes, the conductivity rose by between 3-and 5fold compared with the unmodified NaAlg, depending on the PANI loading. The conducting polymer did not significantly change the thermal stability or cycling of the cells, but it did improve the Coulombic efficiency. During electrochemical testing, it was found that cells containing PANI within the binders exhibited evidence of essential processes, such as SEI formation and lithium intercalation. Evidence of side reactions was observed, predicted to be the lithiation of PANI to create lithium emeraldinate within the polymeric regions, which could increase the Coulombic efficiency of the cells and allow for the decrease in impedance contributions after extensive cycling. Capacities and rate capabilities comparable to anodes prepared using graphite and commercial binders PVDF and CMC/SBR were also observed. Crucially, after cycling, the NaAlg/PANI binder could be fully removed from the active material with mild ultrasonic agitation in water.