This review delves into the exploration of thermocouples and their utilization in generating thermal potential through the exploitation of the thermogalvanic effect. The thermogalvanic effect finds typical applications in thermoelectric cells, wherein redox couples such as\([{Fe(CN)}_{6}^{4-}\)/\({Fe(CN)}_{6}^{3-}],[\text{Fe}^{2+}/\text{Fe}^{3+}]\)and \([I^{-}/I_{3}^{-}]\) are employed to convert heat energy into electricity, as illustrated in Figure 2. Usually, these redox couples, along with electrolytes, can reach a certain degree of the Seebeck coefficient. The Seebeck coefficient of ionic thermoelectric materials based on the thermogalvanic effect is determined by Eq. (1) as follows:^[23]

where \(V,\ S,\ n\), and \(F\) represent the open circuit operating voltage of the ionic thermoelectric material, the partial molar entropy difference of the redox couple, the number of electrons transferred during the redox reaction, and the Faraday constant, respectively. When considering the Seebeck coefficient, the energy conversion efficiency of thermoelectric materials is often determined using the dimensionless quality factor, defined by Eq. (2) as follows:^[24]

where \(S\) represents the Seebeck coefficient, \(\sigma\)denotes the conductivity of the material, T represents the absolute temperature, and \(k\) represents the thermal conductivity. Specifically, \(k_{e}\) denotes the electron thermal conductivity while\(k_{l}\) is the lattice thermal conductivity. Indeed, achieving a highZT value corresponds to a higher energy conversion efficiency in thermoelectric materials. The difference in redox states significantly influences the entropy of ion partial moles between different valence states and determines its \(S\). Additionally,\(S^{2}\sigma\) can be interpreted as the thermoelectric power factor. To attain high ZT values, it is crucial to have a higher\(S^{2}\sigma\) while minimizing the\(k\). This insight highlights a direction for improving the thermogalvanic effect of ionic thermoelectric materials.