Controllable Preparation And Energy Storage Properties Of Porous Metal Oxides/Selenides

With the rapid development of science and technology,the application field of energy storage devices is extensive and irreplaceable(such as electric vehicles,electronic bracelet and so on).The development of energy storage devices is important for sustainable conversion of energy.However,with the energy and environmental were excessive depletion and deterioration,finding the sustainable and renewable new energy became the focus of research in recent years.Preparing the high-efficiency and practical energy storage devices are extensive research by researchers,such as supercapacitors,zinc-ion batteries,lithium-ion batteries,etc.The research creates more possibilities for the development of sustainable energy.The electrode material of devices is a key factor for preparing high performance energy storage devices.Porous materials have the large surface area and excellent permeability.During the charging and discharging process of supercapacitors,the porous structure can buffer the volume change of electrode material,thus reducing the loss of active substances.Based on the above problems,this work researched and prepared the porous metal organic frameworks(MOFs)derived materials and Prussian blue analogs(PBAs).And used carbon nanotube(CNT)films as the base to design three kinds of electrode materials.The influence of morphology,composition and structure for the electrochemical performance of electrodes was explored in this work.(1)CoSe₂ two-dimensional nanosheet structure is designed and successfully prepared by a facile two-step hydrothermal method.Using the Co-MOF as a template to prepare a two-dimensional nanosheet structure can retain the excellent characteristics of MOF materials.At the same time,the two-dimensional nanosheet structure is conducive to the effective transmission of ions and electrons,and can adapt to the process of structural change in electrochemical reactions.This structure has better electrochemical cycling performance.A flexible all-solid asymmetric supercapacitor is assembled with CoSe₂/CNT as the positive electrode and FeSe₂/CNT as the negative electrode.The stable output voltage can reach 1.8V,and when current density is 5 m A cm^-2,the area specific capacitance can provide up to 593.5m F cm^-2.The energy density can achieve 0.25m Wh cm^-2,after 4000 cycles the capacitance retention rate still achieves 85.29%.(2)Cu O-Co₃O₄ three-dimensional hollow cubic nanostructures is designed and successfully prepared by aged at ambient temperatures.The Cu O-Co₃O₄ is a kind of transition metal oxides(TMO).It is prepared by using PBAs materials as a template.The Cu O-Co₃O₄ not only has the high capacity and safety,but also maintains the advantages of hollow nanostructure,such as large surface area,multi-interface and multi-porosity.The Fe₂O₃ hollow cubic nanostructures was obtained by the same preparation method.The Cu O-Co₃O₄and Fe₂O₃are assembled a flexible all-solid asymmetric supercapacitor of Cu O-Co₃O₄/CNT//Fe₂O₃/CNT.The energy density can achieve 48.77 Wh kg^-1,after 6000 cycles the capacitance retention rate still has 73.68%,which compared to the initial capacity.This result proves the asymmetric supercapacitor has long cycle life and superior stability.(3)Mn Co O three-dimensional porous nanosphere structure is designed and successfully prepared by a facile one-step hydrothermal method.The porous structured Mn Co O is prepared by using the Mn Co-PBA as template.This structure can effectively increase the contact area and adapt to the volume change during charge and discharge.Meanwhile,the stability of the structure can maintain.Water-based rechargeable zinc-ion batteries(ZIBs)is prepared by combined with Mn Co O/CNT electrodes and zinc sheet electrodes.The test results show that the ZIBs have a wide voltage range of 1V,and the discharge specific capacity achieves 236.84m Ah g^-1 at a current density of 0.4 A g^-1.When the current density increased to 4.5 A g^-1,the discharge specific capacity still maintains to 76.49mAh g^-1.