Structural Design Of Nanoporous Zinc Metal Electrode And Its Application To Rechargeable Aqueous Batteries

Rechargeable aqueous zinc metal batteries（RAZMBs）have great potential in the field of large-scale renewable energy storage due to the abundant zinc raw resources,low cost,and high safety.However,the non-uniform deposition of zinc and chemical corrosion/hydrogen evolution lead to the poor electrochemical reversibility of the Zn metal electrode,hindering its practical application.In view of the above problems,this thesis proposed a method to fabricate a three-dimensional nanoporous Zn metal electrode（p Zn）with controllable pore size.The main research progresses are as follows:1.An alloying-deallying method was developed for preparing three-dimensional nano-porous zinc metal.Metal lithium foil and metal zinc foil solid-phase contact are used for alloying reaction to form Li Zn alloy in an inert gas environment,and nano-porous zinc metal is obtained after dealloying reaction.the precise control of the nanopore structure size can be achieved by controlling the reaction temperature.The three-dimensional nanoporous zinc electrodes have good mechanical stability;the three-dimensional open nanoporous structure provided a rich electrochemical active specific surface area,by which the zinc metal electrodes can have stable deposition/dissolution behaviors in the electrochemical cycle test of the symmetric batteries.No dendrites were observed on the surface,and it is relatively flat without significant volume changes.The three-dimensional nanoporous zinc anodes havesmall voltage polarization,stable cycling performance（the polarization voltage is only 40m V）and long cycling life（capacity retention rate maintained 76% in 1500 cycles）during the dissolution/deposition.2.The influence of the pore structure size on the electrolyte in the local micro-area of the metal zinc electrode interface infiltrated has been analyzed and studied by the electrolyte through theoretical simulation and experimental methods.The study found that by adjusting the pore size（40 nm）in the three-dimensional porous zinc metal electrode,the space charge effect in the nanoporous structure can be precisely adjusted to form an enhanced electrolyte solution in the micro-area of the porous interface.The enhanced micro-area concentrated electrolyte inhibits side reactions such as hydrogen evolution reaction existing in conventional porous electrodes,and effectively improves the electrochemical cycle stability of the three-dimensional porous zinc anode.The nanoporous zinc electrodes showed a high corrosion potential of-0.975 V and a low corrosion current density of 4.0 m A cm^-2.After the immersion experiment（7 days and 25 days）,only a small amount of corrosion products such as zinc hydroxide on the electrode surface were abserved.