Solid-state n-type thermodiffusion-assisted thermogalvanic cells with unprecedented thermal energy conversion

Abstract

Thermogalvanic (TG) cells are a promising technology for harvesting low-grade waste heat, but their practical applications have been hindered by low thermopower and output power density. Here, we report for the first time a solid-state n-type thermodiffusion (TD)-assisted TG cell based on a PEDOT:PSS/Fe(ClO₄)_2/3 polymer complex. The strategic design of the polymer complex, featuring electrostatic interactions between the PEDOT:PSS matrix and the Fe^2+/3+ ions, enables the liberation of ClO₄⁻ ions, enhancing thermodiffusion and ionic conductivity. This mechanism results in a remarkable ionic Seebeck coefficient of −40.05 mV K⁻¹ and a record-high normalized maximum power density of 56.57 mW m⁻² K⁻². The TD-assisted TG cell demonstrates excellent stability for >50 charge–discharge cycles. A 16-paired TG module generates 360 μW, sufficient to power commercial electronic devices. A wearable device showcases the practical applicability by harvesting body heat and producing 1.5 V. These findings represent a significant advancement in thermal energy harvesting and pave the way for practical TG-based energy conversion technologies.