Partial Oxidation Synthesis of Prussian Blue Analogues for Thermo-Rechargeable Battery

Abstract

A thermo-rechargeable battery or tertiary battery converts thermal energy into electric energy via an electrochemical Seebeck coefficient. The manufacturing of the tertiary batteries requires a pre-oxidation step to align and optimize the cathode and anode potentials. The pre-oxidation step, which is not part of the secondary battery manufacturing process, makes the manufacturing of tertiary batteries complex and costly. To omit the pre-oxidation step, we used partially oxidized Prussian blue analogs, i.e., NaxCo[Fe(CN)6]yzH2O (Co-PBA) and NaxNi[Fe(CN)6]yzH2O (Ni-PBA), as cathode and anode materials. The modified tertiary battery without the pre-oxidation step shows good thermal cyclability between 10 ∘C and 50 ∘C without detectable deterioration of the thermal voltage (Vcell) and discharge capacity (Qcell).