Abstract
A derivative of the aqueous Zn-ion batteries described in the previous lecture is the polymer version, which relies on the use of stretchable polymer gels based on gelatin and polyacrylonitrile, or on hydrogels, which are hydrophilic networks that can absorb large quantities of water and also dissolve salts to achieve high ionic conductivities. The result is flexible, self-repairing batteries. Beyond the electrolyte, the improvement of the Zn electrode has been the subject of much work aimed at limiting dendritic problems, as well as its corrosion, by playing on the morphology texture and others. We can mention either the manufacture of core-crown structures (Zn-coated C), or the formation of Zn-Ni alloys to shift the hydrogen release potential on zinc, and reduce corrosion as was done in the past by adding Hg. The use of controlled-porosity separators and super-concentrated electrolytes (1 m ZnTFSI)2 + 20 m LiTFSI + xH2O) has also been shown to minimize the formation of Zn dendrites. In this context, we should also mention the work carried out to reconfigure the Zinc electrode for rechargeability in KOH media , including the development of 3D architecture, sponge structures and even monolithic structures. These structures enable i) electrical conduction to be maintained during cycling, and ii) more efficient saturation/dehydration of the ZnO zincate and its more uniform distribution within the electrode, all of which result in improved performance. On this basis, aqueous Ni-Zn technology is regaining interest.
