Porous Iron-based Prussian Blue Derivatives:Preparation And Application In Lithium Batteries

With the development of science and technology,energy storage equipments related to new energy automobiles and a variety of electronic digital products have drawn more and more extensive attention.As representatives of clean energy,lithium batteries are favored by consumers because of their excellent comprehensive performance.In the development process of lithium batteries,electrode materials have always been an important factor restricting their performance and application.Therefore,it is extremely urgent to develop a new generation of lithium battery electrode materials.Metal-organic frameworks?MOFs?,a new class of organic-inorganic hybrid functional materials with high porosity,large surface area and morphology can be easily tuned upon selection of different metal cations and organic bridging ligands.As a subclass of MOFs,Prussian blue analogues?PBAs?with open frameworks have drawn much attention in energy storage fields due to their tridimensional ionic diffusion path,easy preparation,and low cost.In this thesis,the porous materials with varies structure,hollow FeFe?CN?6 and FeS2@Co9S8,were prepared by using FeFe?CN?6 as the precursor,and their electrochemical performance was studied as the electrode carrier of lithium battery.The thesis mainly includes tow sections as follows:We integrated hierarchical porous hollow FeFe?CN?6 nanospheres and conductive iodine-doped graphene?IG?into lithium-ion batteries?LIBs?system,FeFe?CN?6@IG.The hollow Prussian-blue type FeFe?CN?6 nanospheres with average particle size of 230 nm are uniformly and tightly encapsulated by IG sheets.As an anode material for LIBs,the fabricated FeFe?CN?6@IG exhibits high specific capacity,excellent rate property,and superior cycling stability.A reversible capacity can be maintained at 709 mAh g^-1 after 250 cycles at a current density of 1000 mA g^-1.Even at a current rate of 2000 mA g^-1,the capacity could reach 473mAh g^-1.This facile fabrication strategy may pave the way for constructing high performance Prussian blue-based anode materials for potential application in advanced lithium-ion batteries.We proposed and designed an efficient double-shelled sulfur host in which hollow FeS2nanocages are coated by a thin Co9S8 nanolayer.The FeS2-Co9S8 heterostructure can efficiently confine LiPSs due to the polar chemisorptive capability,and promote electron transfer for polysulfide transform into Li2S2/Li2S.Furthermore,such unique double-shelled hollow nanocage architecture can also accommodate the volumetric effect of sulfur upon cycling.As a result,the prepared S/FeS2-Co9S8/C electrode exhibits good rate capacities and stable cycling life up to 500 cycles at 0.5 C with a very low capacity decay rate of only?0.081%per cycle.