Recently, the research group led by Prof. Shangchao Lin from School of Mechanical Engineering in Shanghai Jiao Tong University published a paper, entitled 'Giant-Thermopower Ionogels for Multifunctional Energy Harvesting through Molecularly Selective Ionic Pairing and Hydrogen Bonding' in journal The Innovation Energy. In this study, selective ionic pairing and hydrogen bonding were cooperatively regulated by doping Na:TFSI and PEG into ionogels, resulting in a giant thermopower of 21.2 mV/K in quaternary inogels. The device assembled from the ionogels showed great potential in thermal sensing, low-grade heat energy recovery, and triboelectric nanogenerator. Master student Yisi Yin and Associate Professor Shangchao Lin are co-first authors of the paper, while Associate Professor Shangchao Lin and Professor Changying Zhao are co-corresponding authors.

The energy crisis has become an increasingly severe problem worldwide, driving our efforts for achieving carbon neutrality. Although sustainable energies, such as nuclear, solar, wind, and hydropower, are being developed rapidly, the reliance on traditional energy sources based on fossil fuels will last for a long time. However, the utilization efficiency of fossil fuels in electricity generation and power applications is generally below 40%, and thus enormous amount of low-grade heat (T < 130 ℃) is generated and wasted. The efficient utilization of energy is conducive to sustainable developments of society. Thermoelectric technology holds immense importance in the realm of sustainable energy due to its direct conversion of heat to electricity. Recently, ionogel-based or hydrogel-based ionic thermoelectric (i-TE) materials have attracted extensive attention due to their much higher thermopowers compared with the e-TE materials. We select a commonly used ionic liquid (IL)-based binary polymer ionogel as the starting material for demonstration, which involves block copolymer PVDF-HFP as the polymer matrix and IL 1-ethyl-3-methylimidazolium bis(trifluoro-methylsulfonyl)imide (EMIM:TFSI) as the electrolyte. On the basis of the binary ionogel, the Coulomb interaction and Lewis acid-base interaction were introduced respectively with the addition of Na:TFSI and PEG. Finally, the giant thermopower of 21.2 mV/K was obtained in the quaternary iongel.

Finally, the potential of the ionogels developed in this study for multi-functional energy harvesting is demonstrated, including ionic thermoelectric supercapacitors, highly sensitive thermal sensors, and friction nanogenerators. Overall, these results offer a promising solution to improve the thermoelectric properties in polymer-based ionic conductors. Additionally, this work also provides new physical insights into applications of ionic thermoelectric materials in low-grade energy harvesting and storage, thermal sensing, and self-powered electronic devices.

Prof. Shangchao Lin’s group is dedicated to the research of electronic/ionic thermoelectric materials and devices, barocaloric refrigeration and thermal cells, thermochemical heat storage, and solid-state hydrogen storage. In recent years, his group has published a series of research papers in Advanced Functional Materials, Science Advances, Chemical Engineering Journal and other international journals, as the first or corresponding author. The work was supported by the National Natural Science Foundation of China (NSFC) and the Thousand Talent Young Scholar Program of China.

Paper link：https://www.the-innovation.org/article/doi/10.59717/j.xinn-energy.2024.100048