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Sunday, July 30, 2023

Zinc/Bromine Secondary Cell/ Zinc Cases/ Halloysite Clay


             "Pile Batteries 4 Cells/6V  ( Zinc/Act Carbon/ MnO2/ alkaline) are still important.

              These cells are primary and start at 1.5V until the Mn +4 is reduced .  However, I have re-charged them for 25 cycles until the voltage drops sharply.  The zinc canister also oxidizes with leakage at that point.

              I recycle the graphite current collectors, salvage the zinc and was/dry the Cact/ manganese species for other projects.

              I am developing zinc/bromine secondary cells ( 1.80V open) with ZnSO4/ NaBr in water as electrolyte along with halloysite clay (kaolinf family member). This clay is nanotubular, absorbs the Br2 which forms by temporary dipole/ electrostatic interaction and provides tunnels for the ionic species involved.

             While waiting for zinc cannisters to arrive for fresch cell construction, I cut the base off a extinguished Zn /carbon zinc casing, gutted out the Cact paste, paper separator and washed / dried the zinc cylinder. I filled ith with a paste made from the clay and aq. species. I left the graphite rod in place to serve as the cathode. The zinc case is the anode and deposited zinc metal will repair the inner surface during cycles of charge.  Minimal zinc dendrites are expected to cause short-circuiting with Br2 contact.

                                                      Fast charge to 1.77V in minutes.

                                                        Inverted zinc casing with clay/ aq. electrolyte. the graphite rod (bottom) is the cathode.   The zinc case is the anode.  I inserted some paper in the cell and placed hot-glue to roughly seal the cell. I see no drippage from the bottom of the cell but have a beaker in place in case.


                    Source of the zinc cases/ graphite rods when the cells are "dead".


                           Top view of the bench-scale cell.   I ran a small DC 1.5V motor with the cell.

                           When zinc cases arrive, I will set up cells in series/ parallel  and collect data which I will publish here. 

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