Characterization of Li–Mg–B alloy/LiNO3–KNO3–KNO2–Ca(NO3)2/MnO2 system for potential use as geothermal and oil/gas borehole battery

• A novel quaternary eutectic melting around 109.5 °C—LiNO3–KNO3–KNO2–Ca(NO3)2—is used as electrolytes.
• The compatibility of these materials is determined by simultaneous TGA–DTA.
• Discharge characteristics of Li–Mg–B alloy/MnO2 couples in the electrolyte are investigated.
• The discharge capacity of single cells is not affected by discharge rate.

A novel quaternary eutectic, LiNO3–KNO3–KNO2–Ca(NO3)2, is developed for the potential use in geothermal and oil/gas borehole battery. The chemical compatibility of the material is examined by the simultaneous thermogravimetric analysis and differential thermal analysis. The MnO2 cathodes present in single cells with Li–Mg–B alloy anodes are characterized using the eutectic electrolyte at 150–300 °C and a current density of 10–30 mA cm− 2. The discharge capacity of the battery is not affected by discharge rate; however, it is significantly affected by the operating temperature.