Structural designs of advanced wood-based thick electrodes for high-performance eco-supercapacitors

Wood is an ecological natural polymer material with wide sources, abundant renewable and biodegradability. The unique structures and diverse chemical compositions endow wood with hierarchical pore structures, low tortuosity, favorable mechanical stability and adjustable functionality. In addition, the vertical channel structures provide superior electron mobility for wood-based materials, and the micrometer-scale pores facilitate the flow of electrolyte, rendering wood-based materials very suitable for electrode materials of energy storage devices, especially applicable to supercapacitors featuring high power density as well as environmental friendliness. In this review, we concisely summarize the latest progress of functional wood-based thick electrodes for eco-supercapacitors. Before discussing the structural regulation strategies, we also introduce the compositions and natural hierarchical structures of wood to explain why the wood-based materials are suitable for electrode materials of eco-supercapacitors. Then, we highlight the architectural designs and preparation strategies of wood-based thick electrodes to demonstrate their applications in eco-supercapacitors. Finally, ongoing challenges and upcoming tendencies in developing wood-based thick electrodes are presented aiming at accelerating the development of eco-supercapacitors and broadening the practical applications.