Design And Energy Storage Study Of Cu-based Oxide And Sulfide

The development of the world economy requires the support of energy.The rapid consumption of fossil fuels and the increasingly prominent environmental problems of the past few decades,especially the smog that has been intensified in China in recent years,have made people aware of the importance of developing clean energy.It is an urgent task to releasing the dependence on traditional energy sources and solving environmental pollution.Researchers are devoted into the developing of renewable energy sources such as solar cells,fuel cells,and wind energy.Electrochemical energy storage technologies,such as supercapacitors,batteries,fuel cells,etc.,have attracted much attention due to the ability of storing intermittent energy sources.While,these technologies exhibit some limitations.For example,the cycle life of air battery is inferior and the energy density of the supercapacitor is low.The new secondary battery has quickly gained market share due to its high safety and stability,the ability to store and convert clean energy to provide a constant source of energy.At present,secondary batteries have been broadly applied in mobile fields such as portable electronic products and electric vehicles.However,current lithium-ion battery technology is hard to meet the growing energy demand,especially in recent years,the country has vigorously developed new energy vehicles.Batteries are the bottleneck for the development of new energy vehicles.It is important to develop batteries with small weight,large capacity,long storage period,wide temperature range and reliable performance.At present,the research on cathode materials has entered a bottleneck period.Researchers have turned their attention to improving the performance of anode materials and developing sodium ion batteries.According to the energy storage mechanism,anode materials can be divided into three types,namely,the insertion type,the conversion type and the alloying mechanism.Three mechanisms have their own advantages and disadvantages.The insertion-type anodes have a low theoretical capacity;materials followed alloying mechanism exhibit a large capacity,but the large volume expansion is an issue;the conversion-type materials present a higher theoretical capacity and potential electrochemical advantages,which has aroused great research interest.Among the conversion-type anode materials,Cu-based oxides have attracted people's attention because of the high capacity,abundant reserves,low price,environmental friendliness,and ease of production.However,the conversion-type materials also have disadvantages.For example,most of the negative electrode materials followed this mechanism have a large volume expansion during charge and discharge,and the metal oxides are semiconductor material,and the conductivity is low,which would cause a decrease in cycling performance and rate performance.In view of the reserve limitation of lithium and the impossiblilty of lithium-ion batteries to satisfy the future energy demand,people are trying to develope sodium ion batteries while improving the performance of lithium-ion batteries due to the sodium has similar properties to lithium and more reserves.Metal oxides such as Fe O,Co O,CuO and Ni O have little electrochemical activity in sodium ion batteries,while metal sulfide/selenide(MXs)has been studied as a lithium ion battery electrode material because of its easy-to-control morphology.Therefore,we researched the performance of Cu S anode material in sodium ion battery.In this paper,the electrochemical properties of Cu-based oxides/sulfides are highly improved,benefiting from the structure and composition of electrode materials.The developed sample preparation methods are simple and suitable for mass production.1.Ag ion kinetically tailored surface and interface engineering of Cu2 O nanocrystals to modulate the Li-ion battery performance.Ag ion kinetics regulates the surface interface of Cu2 O nanocrystals to improve the performance of lithium ion batteries.Nanomaterials have small particle size,large void space and large specific surface area and shorten the ion diffusion distance.Large-scale application of nanostructured electrode materials may increase battery costs.Therefore,it is necessary to develop inexpensive and industrially acceptable methods to synthesize nanostructured materials.In addition,it is difficult for a single material to achieve long cycle life and excellent rate performance simutaneously.Multicomponent materials can fully untilize their respective properties.In the preparation process,the addition of very small amount of Ag+ can decrease the size of Cu2 O drastically.Simultaneously,the metal particle of Ag is also attached to the surface of Cu2 O.Ag-Cu2 O combines the benefits of nanostructure and conductive material.The proposed method is very simple and clean.As anode materials,and the cycling performance of Cu2 O is significantly improved,which is mainly attributed to the synergistic effect of nanostructure and conductive material on Cu2 O.2.One-pot synthesis of uniform Cu2O–CuO–TiO2 hollow nanocages with highly stable lithium storage properties.Hollow structure has high porosity,low density,and can shortened the charge transport distance,which is widely used in applications such as secondary batteries,supercapacitors,dye-sensitized solar cells,photocatalysis,and fuel cells.For lithium-ion batteries,the hollow structure provides more lithium storage sites,providing free space to reduce the volume change caused by repeated intercalation and deintercalation of lithium,reducing the degree of pulverization of the active material,thereby significantly improving the cycling performance of the electrode.Furthermore,the thin shell layer of the hollow structure can shorten the diffusion distance of ions and electrons and improve the rate performance.We continue to develop a method for preparation of various materials and specific structures simultaneously.Hydrothermal treatment was applied to obtain a Cu2 O hollow nanocage structure combined with TiO2 buffer layer.In this approach,Cu2 O works as a self-template,and HF released by hydrolysis of Ti F4 serves as an etchant.The application of Cu2O-CuO-TiO2 hollow nanocage in lithium ion battery has greatly improved the cycling performance and stability of the battery.The enhanced properties can be ascribed to the synergistic effect of individual components and the hollow structure.3.Facile synthesis of Cu S@r GO anode for sodium ion battery.Many methods used in lithium batteries for improving the performance can evoke designs for sodium battery electrodes,including the preparation of nano-sized materials and composite materials.In the synthesis process,a certain amount of r GO is fully dispersed into the precursor,and r GO@Cu S nanosheet is obtained in one step by the solvothermal method method.The Cu S nanosheets are in good contact with r GO.RGO can not only improve the conductivity of electrode material,but also serve as a support to keep the structure.There are also some literatures on nanostructured Cu S anode material,while their preparation often involves complex processes,such as vulcanization process.The electrode of r GO@Cu S exhibited a superior cycling stability,a specific capacity of 227 m Ah g-1 can be retained after 1000 cycles at a current density of 5A g-1.