Abstract
Converting low-grade heat from environment into electricity shows great sustainability for mitigating the energy crisis and adjusting energy configurations. However, thermally rechargeable devices typically suffer from poor conversion efficiency when a semiconductor is employed. Breaking the convention of thermoelectric systems, we propose and demonstrate a new zinc ion thermal charging cell to generate electricity from low-grade heat via the thermo-extraction/insertion and thermodiffusion processes of insertion-type cathode (VO2-PC) and stripping/plating behaviour of Zn anode. Based on this strategy, an impressively high thermopower of ~12.5 mV K−1 and an excellent output power of 1.2 mW can be obtained. In addition, a high heat-to-current conversion efficiency of 0.95% (7.25% of Carnot efficiency) is achieved with a temperature difference of 45 K. This work, which demonstrates extraordinary energy conversion efficiency and adequate energy storage, will pave the way towards the construction of thermoelectric setups with attractive properties for high value-added utilization of low-grade heat.
Highlights
Converting low-grade heat from environment into electricity shows great sustainability for mitigating the energy crisis and adjusting energy configurations
After pyrolysis under argon atmosphere, the PDA and V-based species were evolved into hierarchical porous carbon (PC) matrix and anchored vanadium dioxide (VO2) along with gas escape, and the details can be seen in the “Methods” section
The VO2 is uniformly distributed in the VO2-PC sample with a high content of 65.4 wt% determined by the thermogravimetric analyses (Supplementary Fig. 3)
Summary
Converting low-grade heat from environment into electricity shows great sustainability for mitigating the energy crisis and adjusting energy configurations. Breaking the convention of thermoelectric systems, we propose and demonstrate a new zinc ion thermal charging cell to generate electricity from low-grade heat via the thermo-extraction/insertion and thermodiffusion processes of insertion-type cathode (VO2PC) and stripping/plating behaviour of Zn anode. Based on this strategy, an impressively high thermopower of ~12.5 mV K−1 and an excellent output power of 1.2 mW can be obtained. When introducing the concept of ZIBs into heat-to-electricity conversion, various mechanisms can be proposed through the synergistic effect among the thermogalvanic effect of Zn anodes and the thermodiffusion and thermoextraction of ions in electrolytes and cathodes, respectively (Fig. 1). The proof-of-concept set-up displays satisfying application potential for harvesting energy from waste heat due to its ultrahigh output voltage of ~1 V with only one unit
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