Molten salt synthesis of MnO2/Mn2O3 composite as a high-performance cathode material for rechargeable button zinc‑manganese ultra-high temperature battery

Herein, a novel rechargeable button zinc‑manganese ultra-high temperature battery is first reported for the efficient utilization and conversion of thermal and electrical energy. The battery system uses zinc anode , Zn-K-Cl molten salt electrolyte and MnO 2 /Mn 2 O 3 composite cathode to work at 300 °C. In this study, MnO 2 /Mn 2 O 3 composites were synthesized by molten salt method, and the crystal structure of the materials was adjusted by adding reduced graphene oxide (rGO). The results showed that the spherical nanoparticles and nanobelts of MnO 2 /Mn 2 O 3 composite cathode materials increased the active sites and ion transport channels of the electrochemical reaction , thus providing high coulombic efficiency. By modifying with rGO, the MnO 2 /Mn 2 O 3 (Mn-O-2) composite cathode material exhibits excellent electrochemical performance in the button zinc‑manganese ultra-high temperature battery. The as-prepared button ultra-high temperature battery exhibits a relatively high specific capacity (300 and 175 mAh g −1 at 1 mA cm −2 and 30 mA cm −2 ) and competent cyclability (> 95 % coulombic efficiency after 50 cycles). This work firstly and systematically reveals the role of the Mn cathode materials and shows that the application in button molten salt batteries.