Study On Layered Double Hydroxide And Selenide Electrode Materials For Aluminum Batteries

The increasing energy consumption,especially the massive use of fossil fuels,has negative impacts on the global environment and climate,posing a serious threat to sustainable development.Therefore,there is an urgent need to accelerate the growth of clean energy based on electrochemical energy storage systems.Lithium-ion batteries(LIBs)are confronted with many critical challenges,such as high cost and safety issues.and they cannot meet the growing market demand.It is urgent to design a new type of secondary battery system with low price,high energy density,and excellent safety performance.As an alternative to lithium-ion batteries,aluminum batteries(ABs)are intensively studied recently due to the abundant reserves of aluminum metal(82000 ppm),far beyond those of lithium metal(18 ppm).In addition,aluminum metal with low reactivity could be handled in the ambient environment,which endows ABs with safety performance.Owing to its three-electron redox,the aluminum anode can deliver the theoretical volumetric capacity of 8034 mA h cm-3,which is nearly four times that of lithium anode(2080 mA h cm-3).Because of their high charge density,aluminum ions would encounter strong electrostatic interactions with host materials,which would hinder ion diffusion and severely damage electrode structurem.Thus,limited cathode materials could intercalate aluminum ions reversibly,which becomes another stiff challenge to the practical application of ABs.Herein,we successfully synthesized nickel-iron layered double hydroxide(NiFe-LDH)microspheres with reduced grapheneoxide(rGO)via electrostatic self-assembly approach,prepared porous a-MnSe microspheres and a bimetallic selenide heterostructure by solvothermal method.The three materials used as cathode materials for aluminum batteries showed good electrochemical performance,as follows:1.NiFe-LDH was fabricated by the hydrothermal method,and reduced graphene oxide(rGO)was introduced via electrostatic self-assembly method.It is demonstrated that NiFe-LDH could provide large interlayer spacing for aluminum ions to interact,and the introduction of rGO endows NiFe-LDH with excellent structure stability and cycling performance.The characterization results reveal that the reversible Al3+insertion/extraction,along with the multielectron redox reactions,occurs in the NiFe-LDH/rGO during the cycling process.The aluminum battery with NiFe-LDH/rGO cathode delivers a high reversible capacity of 131 mA h g-1 at 1 A g-1 with nearly 100%Coulombic efficiency after 100 cycles2.The porous a-MnSe microspheres comprising uniform quasi-cubic nanocrystallites were prepared by a facile solvothermal method.The nanosized and porous structure of a-MnSe could offer numerous open channels and the short ionic transport path,which would efficiently mitigate volume changes and enhance electrochemical reaction kinetics.Moreover,the pseudocapacitive characteristic of Al3+storage in a-MnSe contributes to the fast kinetics of the cathode.It is demonstrated that the reversible Al3+insertion/extraction occurs in the a-MnSe cathode during the cycling process.The resulting aluminum battery based on the a-MnSe cathode,AlC13/[EMIm]Cl ionic liquid electrolyte,and aluminum anode exhibits an ultra-high reversible capacity of 408 mA h g-1 at 0.2 A g-1.Even for the current density at 1 A g-1,the discharge capacity of 131 mA h g-1 retained with the Coulombic efficiency of 97%over 150 cycles3.A bimetallic selenide heterostructure(ZnMn-Se)was synthesized by a solvothermal method.The superior reversible capacity and rate capability should be ascribed to the synergistic effect.ZnSe nanoparticles are tightly and uniformly covered on the surface of the MnSe cube,which improves the structural stability,relieves the stress during the cycling process,and increases the specific surface area of the active material.Benefiting from the phase boundaries,ZnMn-Se exerts low Al3+adsorption energy and fast diffusion kinetics.As expected.the aluminum battery with ZnMn-Se cathode delivers a high reversible capacity of 148 mA h g-1 at 1 A g-1 after 100 cycles.