The Design,Construction And Electrochemical Performance Of Flexible Znic-Cobalt Alkaline Batteries

With the deteriorating environmental conditions and the huge demand for renewable energy,as well as the growing pursuit of portable electronic products,flexible and wearable energy storage with high energy/power density,long-term durability,low cost and good safety devices are receiving more and more attention.In the past few decades,researchers have made considerable efforts to develop alkali metal ion batteries（Li⁺,Na⁺,K⁺）.However,a series of intrinsic problems with alkali metal ion batteries,such as the increase in the price of alkali metal（in particular for lithium salts）,the toxicity and flammability of organic electrolytes,severely limit their further widespread use.In particular,high safety is a more important consideration when applied as a flexible energy storage device to wearable electronic devices（such as skin sensors）that may be exposed to the skin.In order to better develop flexible energy storage devices,the safety and electrochemical performance of the flexible energy storage devices under the premise of ensuring their electrochemical performance are pursued.Aqueous electrolytes are usually used in flexible supercapacitors,which is a potential replacement for flammable alkali metal ion batteries because of its safety and cost effectiveness,but their relatively low energy density is far from being adequate for a wide range of applications.Zinc-based batteries are considered to be a powerful candidate for solving the energy storage dilemma between alkali metal ion batteries and supercapacitors due to their unique high output voltage advantages,high theoretical capacity(825 mAh g^-1),eco-friendliness and low cost.The aqueous electrolyte used can provide higher ionic conductivity and better safety than organic electrolytes,thus resulting in higher rate performance.However,two key issues have seriously hampered their widespread application.One is the formation and growth of zinc dendrites,which greatly shortens the cycle life of zinc-based batteries（usually less than 500 cycles）and has an important impact on the cycle performance,rate performance and safety of the battery.The other is the use of high weight zinc foil as negative electrodes in conventional zinc-based batteries,reducing energy density and limiting their use in flexible energy storage devices.Therefore,it is our research goal to develop a more stable anode material to avoid zinc dendrite while increasing the reversible capacity of the cathode material and finally apply it to the field of flexible energy storage.This project aims to explore a viable method for manufacturing cost-effective,dendritic,high-safety,flexible zinc-based batteries through careful design of nanostructures.The electrochemical properties are improved by optimizing anode and cathode at the same time.The main ideas and research results of this topic are as follows:（1）This reasearch first grow a three-dimensional core-shell ZnO@C array as a skeleton on carbon cloth,and then uniformly deposit zinc on the skeleton by electrochemical deposition,and finally synthesize flexible ZnO@C-Zn anode of Zn-Co battery.（2）The high-perforamnce Co（CO₃）_0.5（OH）_x·0.11H₂O@CoMoO₄ nanowire grow on carbon cloth by a simple hydrothermal method.The prepared electrode can provide an ultra-high area specific capacity of 0.72 mAh cm^-22 at a current density of 1mA cm^-2(0.36 A g^-1).Even at a high current density of 64 mA cm^-2(23.02 A g^-1),the capacity remains at 0.42 mAh cm^-2(152.2 mAh g^-1)and the capacity retention rate is67.6%.（3）Further based on the PVA gel electrolyte,the subject assembled a fibrous flexible device exhibiting excellent electrochemical performance and flexibility.It can power a range of electronic devices and demonstrates tremendous potential for practical applications.