Construction Of Functionalized Fe-based Composites For Advanced Electrochemical Energy Storage Systems

The increasing environmental concerns as well as the booming in renewable energies and electric vehicles enable the continual thriving on the exploitation of matched electrochemical energy-storage systems(EESSs)with efficient,green,cheap and safety features.Recently,when compared with Co,Mn,V,etc.Fe-based nanomaterials have received great attention in EESSs because Fe is inherently abundant,no-toxic and eco-friendly nature.The Fe-based nanomaterials can exhibit prominent electrochemical properties when applied in aqueous or lithium/sodium ion batteries.Therefore,high performance and low cost Fe-based nanomaterials show great prospects in practical application.Nevertheless,their realization of high output capacities can merely be achieved upon total reversible redox reactions of Fe³⁺/Fe⁰.Along with three-electron electrochemical conversions,unavoidable multi-phase changes would give rise to huge actives volumetric expansions/pulverization,and thereby continuous deteriorations in electrode cycleability,rate capability and Coulombic efficiency.Hence,the reasonable design of low-cost and long-lifespan Fe-based materials has become a great challenge for the current scientific research.In this thesis,we herein use cheap precursor and develop feasible method to make Fe-based materials(Fe,Fe₂N),and further unveil its evolution mechanism.The main contents are listed as follows:The prominent accomplishment of electrochemical energy storage devices is closely bound up with the advent of state-of-the-art techniques to make optimal electrode systems.Herein,we demonstrate a unique popcorn-inspired strategy to develop all-conductive and highly puffed Fe(?)carbon nanopopcorns as superb anodes for rechargeable Ni/Fe batteries.Temperature-dependent systematic studies unveil the nanopopcorn evolution mechanism is governed by typical phase variation from Fe₂O₃ nanosphere into dispersed Fe⁰nanodebris,whose formation prompts the catalytic reconstruction/conversion from hydrocarbons to graphitic nanolayers while triggering the explosion-like instant puffing process beyond 700 ^oC.The as-built Fe(?)carbon hybrids with favorable loosened structures,open-up/enlarged surface areas and intrinsically conducting nature enable great electrochemical performances.This work sheds a fundamental light on arts to configure puffed electrodes for advanced electrodes in various important applications while holding a great promise for high-rate/capacity aqueous rechargeable batteriesThe recycle/reuse of wastes is significant for green and sustainable development of our society.Herein,we present the mass production of Fe@C nanoparticles(NPs)with plastic and rusty wastes for making high-capacity anodes of Ni–Fe batteries.The total conversion is achieved by a facile one-step chemical vapor deposition process,where plastics decomposition offers rich hydrocarbons and iron rust-derived Fe₂O₃ are reduced to Fe NPs,in-situ launching the catalytic growth of carbon(C)shells on their surfaces.All Fe NPs are thereby tightly sealed by C layers,whose thickness can be controlled by tuning the reaction time.Benefiting from superb reactivity/conductivity of Fe core and good stability/robustness of C shell,such unique Fe@C hybrid configurations exhibit excellent energy storage properties.This paradigm work may guide us to massive and smart evolution of disposable/useless wastes into useful materials for energy-related applications.Smart evolution of domestic wastes into competitive battery materials at less expense is a rational strategy of“killing two birds with one stone”,and would be never better especially for grid-scale sustainable energy-storage utilizations wherein achieving great energy density is less crucial than environmental friendliness and fabrication cost.To check whether this concept is viable enough for real applications,we herein select wastes-evolved iron nitride(Fe₂N),a conductive conversion-type anode material usable for both Li-/Na-ion batteries(LIBs/SIBs),as a paradigm study.Among stepwise synthetic procedures,each Fe₂N nanoactive evolved from rusty and PE plastic wastes is evenly configured within a robust carbon matrix,which is definitely in favor of either LIBs or SIBs application.To judge their promise in practical usage,we further choose the economical/commercialized Li Fe PO₄,and phase-stable Na₃V₂(PO₄)₃ as pairing cathodes to build full LIBs and SIBs.This work may provide an encouraging“wastes-to-battery”approach for energy-related fields,and moreover pave the way to advance more techniques for sustainable applications beyond.