Lignosulfonate molecular anchoring of polyaniline for high performance sodium-ion battery anodes

Abstract

Organic electrode materials (OEMs), particularly conductive polymers, are attractive because of their high theoretical capacities and molecular tunability. However, practical implementation is often limited by complicated synthesis/processing and, more critically, dissolution in organic electrolytes, which causes active-material loss and rapid capacity fading. Here, we report a facile and green molecular-anchoring strategy to fabricate a polyaniline/sulfonated lignin (PANI/SL) composite anode, in which sulfonated lignin serves as a biomolecular template and dopant to build a dissolution-resistant, noncovalently integrated conductive network. As a result, the PANI/SL anode delivers exceptional cycling stability, retaining 99.2% of its capacity after 3800 cycles at 2.0 A g-1. Mechanistic studies indicate that the sodium storage originates from C=N and C=O groups together with π–Na+ interactions. Moreover, the robustness of this anchoring design is further validated by scale-up experiments. By overcoming electrolyte-driven dissolution and the associated cycling instability, this work establishes a general design principle for stabilizing OEMs through the high-value utilization of byproducts, thereby advancing sustainable, high-rate sodium-ion battery technologies.