Intrinsic structural optimization of zinc anode with uniform second phase for stable zinc metal batteries

Abstract

Aqueous zinc metal batteries are plagued by the unstable interfacial chemistry of zinc anode due to the hydrogen evolution and other side reactions at the anode/electrolyte interface. Hence, a novel stable Zn|Sn alloy anode with homogeneous second phase and localized electron effect is designed via large-scale alloying strategy. This Zn|Sn alloy by intrinsic structural optimization is quite different from other Zn-Sn composite anodes. The theoretical analysis and postmortem/operando experimental proofs indicate that alloy anode displays a weaken hydrogen evolution reaction and a smooth surface without by-products and dendrite, in the sharp contrast to the bare one. This is due to the localized electron effect of homogeneous second phase that constrain the reduction, diffusion and aggregation of hydrogen ions. Benefiting from these features, the Zn|Sn alloy anode enables a long cyclic life of more than 2200 h and a high average coulombic efficiency of 97.53% in symmetric batteries, as well as, a long cycling stability over 1000 cycles in full batteries. The concept could be readily extended to other metal anodes, demonstrating that rational regulation of alloy anode with homogeneous second phase is a promising route to prolong the service life of ZMBs.