Abstract
Direct conversion of the tremendous and ubiquitous low-grade thermal energy into electricity by thermogalvanic cells is a promising strategy for energy harvesting. The environment is one of the richest and renewable low-grade thermal source. However, critical challenges remain for all-day electricity generation from environmental thermal energy due to the low frequency and small amplitude of temperature fluctuations in the environment. In this work, we report a tandem device consisting of a polypyrrole (PPy) broadband absorber/radiator, thermogalvanic cell, and thermal storage material (Cu foam/PEG1000) that integrates multiple functions of heating, cooling, and recycling of thermal energy. The thermogalvanic cell enables continuous utilization of environmental thermal energy at both daytime and nighttime, yielding maximum outputs as high as 0.6 W m−2 and 53 mW m−2, respectively. As demonstrated outdoors by a large-scale prototype module, this design offers a feasible and promising approach to all-day electricity generation from environmental thermal energy.
Highlights
Low-grade thermal energy (
Thermal resonators provide an approach to the conversion of temporal temperature differential to spatial temperature differential by using phase change materials (PCMs) and have the capability of being optimized at different target frequencies of temperature fluctuations [16], but the small amplitude of temperature fluctuations becomes a critical limitation when they are applied in practical environmental thermal energy harvesting
The top electrode achieves a high temperature via the PPy layer absorbing radiation from an ambient environment and natural sunlight, whereas the bottom electrode maintains a low temperature by storing latent heat in the PCM, yielding a large temperature differential (ΔT) across the Thermogalvanic cells (TGCs)
Summary
Low-grade thermal energy (
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