Periodic Reporting for period 1 - TE-IonicPolyGels (Study of functionalised Pluronic® polymer doping in thermoelectric ionic polymer gels for tuning of ionic Seebeck coefficient and application in harvesting heat to electricity)
Reporting period: 2022-11-01 to 2024-10-31
The project TE-IonicPolyGels is focuses development of thermoelectric ionic polymer gels (TEIPGs) that harvest environmental waste heat or cold into electricity. This is sustainable way of harvesting renewable energy and to utilize it for specific applications through chemical engineering of TEIPGs by selective use of polymer and ions. Although, TEIPGs are latest generation of TE-materials as it holds importance for printable properties that enable it to ease in the TE-device fabrication process and wearable electronics applications. Due to availability of large library of polymers, solvents, ionic liquids and metal-ion or non-metal ions, it expects huge freedom in achieving high TE-performance compositions. But these TEIPGs work based on principal of Soret effect, where TEIPG between two electrodes, generate electricity by ionic thermo-diffusion under influence of heat gradient across the TEIPG. Hence, achieving suitable ionic dissociation, selective anion/cation diffusion, tuning of Seebeck coefficient magnitude, and control of thermal conductivity are bottleneck problems to be solved in the field.
The overall objective of this project is to achieve batter strategies to design the TEIPGs by introducing new dopants and polymer/ion combination to tune the ion dissociation in polymer matrix and improving TE performance/Seebeck coefficient. Further, to utilize these ionic polymer gels to energy storage devices. This technology enables the sustainable energy harvesting and will contribute to overcome exiting problems available due to use of fossil fuels which make huge impact on society.
The overall objective of this project is to achieve batter strategies to design the TEIPGs by introducing new dopants and polymer/ion combination to tune the ion dissociation in polymer matrix and improving TE performance/Seebeck coefficient. Further, to utilize these ionic polymer gels to energy storage devices. This technology enables the sustainable energy harvesting and will contribute to overcome exiting problems available due to use of fossil fuels which make huge impact on society.
In this project, we demonstrated TE behaviour of halide ions in aqueous TEIPGs developed from biocompatible polymer scaffold of polyethylene oxide and polypropylene oxide block-copolymer. To analyse this composition, TE-performance is compared with homo-polymer based TEIPG and block-copolymer based TEIPG. in this unique composition, controlled hydrophilic and hydrophobic behaviour contributes to effective dissolution and dissociation of ions and contribute to selective ion diffusion for better TE performance. Further, hybrid ionic polymer gel is utilized as electrolyte in zinc-ion battery (ZIB) to improve electrode-electrolyte interface and flexible wearable device.
We achieved free-standing, printable TEIPG as described in Figure 1a, where TEIPG is printed on glass substrate with two carbon electrodes to build the TE device. This gel can also be printed on flexible plastic substrate and possess good flexibility. Figure 1b summarizes TE performance of best device in terms of potential versus time profile under influence of 15 oC temperature difference between two electrodes. It results robust, reversible and repetitive voltage profile with output of 275 (+/- 10) mV from single leg. Such performance can be utilized to harvest heat gradient from environmental cold and human body heat by wearable TE-device fabricated with multiple legs.
We achieved free-standing, printable TEIPG as described in Figure 1a, where TEIPG is printed on glass substrate with two carbon electrodes to build the TE device. This gel can also be printed on flexible plastic substrate and possess good flexibility. Figure 1b summarizes TE performance of best device in terms of potential versus time profile under influence of 15 oC temperature difference between two electrodes. It results robust, reversible and repetitive voltage profile with output of 275 (+/- 10) mV from single leg. Such performance can be utilized to harvest heat gradient from environmental cold and human body heat by wearable TE-device fabricated with multiple legs.
Beyond the state of the art, we identified that, instead of homopolymer matrix, co-polymer matrix in aqueous media plays important role to selectively diffuse the ions under heat flux. TEIPG based on halide ions with homopolymer shows Seebeck coefficient of 0.007 mV K-1, while similar halide ions in co-polymer network reached to 8.94 mV K-1. The amphiphilic nature of TEIPG promotes the ionic conductivity and diffusion of ions. This TEIPG is promised over existing state of the art available aqueous halide solution based thermoelectric composition. Further, in another application, halide based TEIPG was utilized to accelerate the catalytic conversion of Zn-S battery energy storage and availing amphiphilic synergy to implement robust interface and flexibility in device. To further commercial and endues success to society for these developed materials, efforts need towards IPR, scale-up, technology transfer, and validation to produce it in bulk.