Seebeck effect in a battery-type thermocell

We demonstrated that battery-type thermocells, which consist of two paste-type electrodes with the same active material and electrolyte, show the Seebeck effect. The magnitudes of electrochemical Seebeck coefficient (S) of the thermocells with several layered oxides were evaluated: -12.7 μV/K for Na_0.99CoO₂, -29.7 μV/K for Na_0.52MnO₂, -22.4 μV/K for Na_0.51Mn_0.5Fe_0.5O₂, and -6.8 μV/K for LiCoO₂. In the thermocell with Na_0.99CoO₂, time-dependence of the electromotive force (ΔV) at a constant temperature difference (ΔT) was well reproduced by a mean-field approach of the chemical potential (η) - Na⁺ concentration (x) relationship, indicating that the Na⁺ intercalation/deintercalation plays an intrinsic role in the electrochemical Seebeck effect.