Abstract
Blocking the zincate ion ([Zn(OH)4]2–) and limiting its reaction with the cathode material are key requirements for improving the energy density and rechargeability of alkaline zinc manganese dioxide (Zn|MnO2) batteries. Zincate is the soluble anode discharge product, which undergoes a side reaction with the reduced cathode material to form a resistive and irreversible spinel material. Such a side reaction prevents deeper discharge of MnO2, reduces the battery’s achievable energy, and prevents it from further cycling. In this article, we report the design and fabrication of an ion-selective graphene oxide/poly(vinyl alcohol) composite membrane and demonstrate its superiority in suppressing zincate ion crossover while minimally impairing the conduction of hydroxyl ions (OH–). With this advanced separator, near full utilization of the MnO2 electrode’s two-electron capacity (∼617 mA h/g-MnO2) with a high areal capacity of 20 mA h/cm2 is reported for both primary and secondary cells. In the primary cell, the energy density is almost doubled, and in the rechargeable cell, a cycle life of 300 cycles is achieved, which is more than 3 times better than the case with no zincate blocking separator.
Published Version
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