Abstract
Efficient low-grade heat recovery can help to reduce greenhouse gas emission as over 70% of primary energy input is wasted as heat, but current technologies to fulfill the heat-to-electricity conversion are still far from optimum. Here we report a direct thermal charging cell, using asymmetric electrodes of a graphene oxide/platinum nanoparticles cathode and a polyaniline anode in Fe2+/Fe3+ redox electrolyte via isothermal heating operation. When heated, the cell generates voltage via a temperature-induced pseudocapacitive effect of graphene oxide and a thermogalvanic effect of Fe2+/Fe3+, and then discharges continuously by oxidizing polyaniline and reducing Fe3+ under isothermal heating till Fe3+ depletion. The cell can be self-regenerated when cooled down. Direct thermal charging cells attain a temperature coefficient of 5.0 mV K−1 and heat-to-electricity conversion efficiency of 2.8% at 70 °C (21.4% of Carnot efficiency) and 3.52% at 90 °C (19.7% of Carnot efficiency), outperforming other thermoelectrochemical and thermoelectric systems.
Highlights
Efficient low-grade heat recovery can help to reduce greenhouse gas emission as over 70% of primary energy input is wasted as heat, but current technologies to fulfill the heat-toelectricity conversion are still far from optimum
The cell VOC drives the oxidation of PANI anode to produce electrons through the external circuit; the majority of electrons are carried by the reduction reaction of Fe3+ to Fe2+ in cathode side, which protects the functional groups of GO from being reduced and significantly enhances the discharge capacity of direct thermal charging cell (DTCC)
In this work, we report efficient conversion of low-grade heat to electricity with an electrochemical cell, which consists of asymmetric GO/PtNPs and PANI electrodes with Fe2+/Fe3+ redox electrolyte
Summary
Efficient low-grade heat recovery can help to reduce greenhouse gas emission as over 70% of primary energy input is wasted as heat, but current technologies to fulfill the heat-toelectricity conversion are still far from optimum. We report a direct thermal charging cell, using asymmetric electrodes of a graphene oxide/platinum nanoparticles cathode and a polyaniline anode in Fe2+/Fe3+ redox electrolyte via isothermal heating operation. Efficient recovery of low-grade heat is vital to abate greenhouse-gas emissions and promises potential economic and environmental benefits Current technologies such as solid-state thermoelectric devices (TEs) and liquid-based thermoelectrochemical cells (TECs) are capable of converting heat into electricity, but their conversion efficiency (ηE) is either too low or system is too complex for economical deployment. The two electrochemical processes at both low and high temperatures in a cycle can be discharged by current flow in reverse direction, but the efficiency lower than 1% (10% of ηCarnot) and the use of expensive ion-selective membrane are concerns[11]. The introduction of ammonia stream is a serious concern regarding the leakage, stability, and safety
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