Ionic thermoelectric materials and devices

TL;DR

This review discusses recent advances in ionic thermoelectric materials and devices, highlighting their potential for low-cost, large-area heat-to-energy conversion through ionic thermodiffusion and the ionic Seebeck effect.

Contribution

It provides a comprehensive overview of the state of the art, classifications, and future directions in ionic thermoelectrics, a promising new energy conversion technology.

Findings

Ionic thermoelectric materials can generate significantly larger voltages than electronic counterparts.

Most ionic thermoelectric materials are made of abundant elements, reducing costs.

The field is rapidly evolving with potential for large-scale, low-cost energy harvesting.

Abstract

The tremendous amount of wasted heat from solar radiation and industry dissipation has motivated the development of thermoelectric concepts that directly convert heat into electricity. The main challenge in practical applications for thermoelectrics is the high cost from both materials and manufacturing. Recently, breakthrough progresses in ionic thermoelectrics open up new possibilities to charge energy storage devices when submitted to a temperature gradient. The charging voltage is internally from the ionic Seebeck effect of the electrolyte between two electrodes. Hence electrolytes with high thermoelectric figure of merit are classified as ionic thermoelectric materials. Most ionic thermoelectric materials are composed of abundant elements, and they can generate hundreds of times larger thermal voltage than that of electronic materials. This emerging thermoelectric category brings new hope to fabricate low cost and large area heat-to-energy conversion devices, and triggers a renewed interest for ionic thermodiffusion. In this review, we summarize the state of the art in the new field of ionic thermoelectrics, from the driving force of the ionic thermodiffusion to material and application developments. We present a general map of ionic thermoelectric materials, discuss the unique characters of each type of the reported electrolytes, and propose potential optimization and future topics of ionic thermoelectrics.