Metakoalin solid ionic conductor and a sodium-ion battery using the same

A method for assembling a sodium-ion battery comprising:

• layering a biochar-based anode, an NaNiO2 cathode, and a metakaolin electrolyte pellet on an aluminum current collector;
• wherein said biochar-based anode is formed by pelletizing biochar with a steel die to form biochar pellets;
• wherein said NaNiO2 cathode is formed by combining polyvinylidene difluoride, carbon black, and sodium nickel dioxide mixed with deionized water to form a slurry and laying said slurry onto an aluminum plate and drying said slurry;
• wherein said metakaolin electrolyte pellets are formed by compressing kaolinite powder into pellets and heating said pellets;
• wherein said biochar-based anode is layered first on said aluminum current collector, then said metakaolin solid electrolyte pellets are layered, then said NaNiO2 cathode is layered;
• and
• wherein said aluminum current collector is placed on a first spacer plate and into a positive bottom of a coin cell, a second spacer plate is placed on said NaNiO2 cathode, a spring is placed on said second spacer plate, and a negative lid of said coin cell is placed on top of said spring to close said coin cell.