Highly Efficient, Dendrite-Free Zinc Electrodeposition in Mild Aqueous Zinc-Ion Batteries through Indium-Based Substrates

Quasi-neutral aqueous zinc-ion (Zn-ion) batteries are nowadays among the most promising energy storage devices for smart-grid applications. However, their practical use remains hindered by the low Zn electrodeposition efficiency at the negative electrode, which is especially reduced due to the parasitic evolution of gaseous hydrogen. Indium is a non-toxic metal showing poor hydrogen evolution kinetics, but it is also very expensive. Therefore, an optimized mixture of bismuth and indium particles has been used as the substrate for the Zn electrodeposition and dissolution reaction to increase its reversibility and its efficiency in a quasi-neutral ZnSO4 solution. This strategy not only allowed to prolong the cycle life of a full Zn-ion cell of 10 times at 0.5 C due to the suppression of the hydrogen evolution reaction, as proved by the operando DEMS analysis, but also led to very homogeneous zinc deposits over prolonged cycling at realistic charge and current densities.