Lignin‐Derived Ionic Conducting Membranes for Low‐Grade Thermal Energy Harvesting

Abstract

Wood‐based ionic conductive membranes have emerged as a new paradigm for low‐grade thermal energy harvesting applications due to their unique andtailorable structures. Herein, a lignin‐derivedionic conducting membrane with hierarchical aligned channels is synthesized viaa double network crosslinking approach. Their excellent thermal stability andsuperior swelling ratio allow their optimization as low‐grade heat recovery technologies. Several vertically aligned nanoscaleconfinements are found in the synthesized membranes, contributing towardenhanced ionic diffusion. Among all the combinations, the membrane comprising69.2 wt.% of lignin and infiltrated with 0.5 m KOH exhibits anexceptional ionic figure of merit (ZTi) of 0.25, relatively higher ionic conductivity(51.5 mS cm‒1), lower thermal conductivity(0.195 W m‒1·K), and a remarkable ionic Seebeck coefficientof 5.71 mV K‒1 under the application of an axialtemperature gradient. A numerical model is also utilized to evaluate theveracity of experimental observations and to gain a better understanding of thefundamental mechanisms involved in attaining such values. These results displaythe potential of lignin‐basedmembranes for future thermal energy harvesting applications and are a new facetin thermoelectric energy conversion which is certain to pave the way forfurther investigations on sustainable ionic conductive membranes.

Synthesis of PEDOT/CNTs Thermoelectric Thin Films with a High Power Factor

“…However, their scarcity in the Earth [ 7 ], toxicity [ 8 ], high production cost, and poor processability do not make them the ideal option for practical applications in the future. On the other hand, there is an increasing interest in organic materials due to several advantages over inorganic ones; some of them are eco-friendly, like lignin [ 9 ], and have low production costs, a light weight, easy production process, high abundance, low thermal conductivity (crucial for a high figure of merit), and high electrical conductivity [ 10 , 11 ]. Poly(3,4-ethylenedeoxythiophene) (PEDOT) is one of the most popular organic thermoelectric materials that have been intensively used during the last few years [ 12 , 13 , 14 , 15 ].…”

Lignin-Derived Materials for Sustainable Development of Ionic Thermoelectric Supercapacitors

“…Traditional methods for low-grade waste heat recovery fall short due to the low temperatures and high volumes of waste heat. New, efficient technologies are needed to harness this energy source sustainably [3][4][5].…”