Tunable Construction Of Nanoarchitectured Zn-and Fe-based Electrodes And Their Application In Aqueous Batteries

Energy crisis and environmental pollution have become the common problems in the global development.How to develop and utilize green,cheap,non-toxic,efficient and sustainable new energy has become a hot topic of current research.Lithium ion batteries?LIBS?,as the main power supply for portable devices and new energy vehicles,have the advantages of high voltage,high specific energy,long cycle life and low self discharge rate.However,there are still some problems in lithium-ion batteries,such as continuous capacity degradation,low power density,flammable electrolyte,environmental protection and limited lithium resources.Therefore,it has become a great challenge to design a new type of energy storage equipment which is safe,reliable,low-cost and excellent in performance.Aqueous secondary batteries?RABs?have attracted wide attention due to their advantages of high power density,high energy density,high safety,low cost and environmental protection.However,in the process of electrochemical reaction,the aqueous secondary battery is faced with the problem of electrode material dissolution,which leads to poor cycle stability of the battery.The electrolyte?peracid or peralkaline?has certain corrosiveness and low voltage.How to improve the performance of battery from the aspects of material innovation,electrode structure optimization,and the reasonable construction of electrolyte system has become an urgent problem to be explored and solved.In this paper,Zn-Mn and Ni-Fe secondary batteries are taken as the research objects.By optimizing the electrolyte and designing and constructing reasonable electrode structure,the energy storage performance and improvement of transition metal?Zn,Fe?based nano electrodes are studied.The research contents are as follows:1.Using cheap and low-cost manganese sulfate as raw material,the super long MnO₂ nanowires were prepared by hydrothermal reaction.The MnO@C nanoprecursor composite with carbon modified layer thickness of about 10 nm was obtained by dopamine coating and high temperature carbonization.Furthermore,the coaxial core-shell structure Mn₃O₄@C nanowire cathode material was obtained by oxidation.The one-dimensional coaxial core-shell structure can effectively alleviate the material pulverization problem caused by the electrode material volume expansion in the electrochemical reaction process,and the carbon modified layer can ensure the overall conductivity of the electrode,strengthen the electrode structure,improve the charge transfer efficiency,improve the cycle life and multiplier performance of the electrode.In addition,in order to solve the problem of zinc dendrite growth and improve the environmental protection of the electrochemical system,we also optimized the electrolyte,using ZnSO₄ to replace the traditional alkaline electrolyte,and adding MnSO₄(to supplement the loss of Mn²⁺in the process of charging and discharging)and Na₂SO₄?to improve the pH value of the electrolyte?,making the electrolyte close to neutral,inhibiting the generation of zinc dendrite,so as to improve the environmental protection of the electrochemical system Cycle stability of high secondary Zn-Mn Battery.In order to prove the application potential of the system in the field of energy storage,we further assembled Zn?CB//Mn₃O₄@C battery.2.Using waste chopsticks as raw materials,nano metal?such as Fe,Ni?@porous carbon fiber?CMFs?composites were obtained by"colloidal assisted"synthesis,and the pore forming mechanism of metal salt solution was explored.Then,the Fe@CMFs and Ni@CMFs composites were used as anode and cathode of Ni-Fe alkaline battery respectively.The composite has excellent electrochemical properties,such as good structural stability and cycle stability,high specific capacity,energy density and power density.In order to prove the application potential of the material in the energy storage system,we further assembled the Ni@CMFs?+?//Fe@CMFs?-?full cell.The device can output 1.2V voltage,with high specific capacity and good cycle stability.