Resistance components of liquid thermoelectric converter composed of [Fe(CN)6]3−/[Fe(CN)6]4− aqueous electrolyte and graphite-dispersing electrodes

Abstract

Liquid thermoelectric converter (LTE) converts environmental heat into electric power via the electrochemical Seebeck coefficient α. Here, we systematically investigated components of device resistance R, i.e., solute (R_s), charge-transfer (R_ct), and diffusion (R_dif) resistances, of LTE composed of 0.8 M Na₄[Fe(CN)₆]/K₃[Fe(CN)₆] aqueous electrolyte and graphite-dispersing electrodes. R⁻¹_ct and R_dif⁻¹ linearly increase with t in the thin t region (t ≤ 40 μm) reflecting the increase in electrochemical active surface area (EASA). The maximum power W_max of the ferro/ferri LTE (t = 97 μm) reaches 0.76 W m⁻² at ΔT = 50 K, suggesting the effectiveness of the graphite-dispersing electrode in ferro/ferri LTE.