Interconnecting EDOT-Based\nPolymers with Native Lignin\ntoward Enhanced Charge Storage in Conductive Wood

The 3D micro- and nanostructure of wood has extensively\nbeen employed\nas a template for cost-effective and renewable electronic technologies.\nHowever, other electroactive components, in particular native lignin,\nhave been overlooked due to the absence of an approach that allows\naccess of the lignin through the cell wall. In this study, we introduce\nan approach that focuses on establishing conjugated-polymer-based\nelectrical connections at various length scales within the wood structure,\naiming to leverage the charge storage capacity of native lignin in\nwood-based energy storage electrodes. We demonstrate that poly(3,4-ethylenedioxythiophene)–poly(styrenesulfonate)\nPEDOT/PSS, integrated within the cell wall lumen, can be interfaced\nwith native lignin through the wood cell wall through in situ polymerization\nof a water-soluble S-EDOT monomer. This approach increases the capacitance\nof the conductive wood to 315 mF cm<sup>–2</sup> at a scan\nrate of 5 mV s<sup>–1</sup>, which is seven and, respectively,\ntwo times higher compared to the capacitance of conductive wood made\nwith the single components PEDOT/PSS or S-PEDOT. Moreover, we show\nthat the capacitance is contributed by both the electroactive polymers\nand native lignin, with native lignin accounting for over 70% of the\ntotal charge storage capacity. We show that accessing native lignin\nthrough in situ creation of electrical interconnections within the\nwood structure offers a pathway toward sustainable, wood-based electrodes\nwith improved charge-storage capacity for applications in electronics\nand energy storage.