Huachi Xu

Dendrite growth in the recharging process of zinc- air batteries

To improve the cycling performance of rechargeable zinc–air batteries, the dendritic morphology of electrodeposited zinc should be effectively controlled. It is of crucial importance to understand the formation mechanism of the zinc dendritic structure. Here we show that an electrochemical phase-field model is established to simulate dendrite growth of electrodeposited zinc, and several measures including the pulsating current and the electrolyte flow are taken to suppress dendrite growth in the charging process. The results demonstrate that dendrite propagation is mainly controlled by diffusion dependent on overpotential and surface energy anisotropy, and dendritic morphology can also give rise to non-uniform distribution of the electric field and ion concentration in the electrolyte. The proposed model and solutions will be available for studying dendrite growth of metal–air batteries as well as metal electrodeposition.

Magnetic field induced motion behavior of gas bubbles in liquid.

The oxygen evolution reaction generally exists in electrochemical reactions. It is a ubiquitous problem about how to control the motion of oxygen bubbles released by the reaction. Here we show that oxygen bubbles during oxygen evolution reaction exhibit a variety of movement patterns in the magnetic field, including directional migration and rotational motion of oxygen bubbles when the magnet in parallel with the electrode, and exclusion movement of oxygen bubbles when the magnet perpendicular to the electrode. The results demonstrate that the direction of oxygen bubbles movement is dependent upon the magnet pole near the electrode, and the kinetics of oxygen bubbles is mainly proportional to intensity of the electromagnetic field. The magnetic-field induced rotational motion of oxygen bubbles in a square electrolyzer can increase liquid hydrodynamics, thus solve the problems of oxygen bubbles coalescence, and uneven distribution of electrolyte composition and temperature. These types of oxygen bubbles movement will not only improve energy saving and metal deposition for energy storage and metal refinery, but also propel object motion in application to medical and martial fields.