Structure Design Of Three-Dimensional Matrices And Interface Optimization For High Performance Lithium/Zinc Metal Anode

Renewable energy sources,such as solar energy,wind energy,tidal energy,play an important role in the further economy.However,their disadvantages of intermittently and randomness compel scientists to look for suitable energy storage devices to conserve the electric power generated from them.Undoubtedly,lithium-ion batteries（LIBs）are one of the most important and successful energy storage devices today,which stores and releases energy through the reversible conversion of electrical and chemical energy.However,the energy density of LIBs using traditional graphite as the anode has almost reached its theoretical value and hardly meets the growing demand for energy/power density.Therefore,advanced electrochemical energy storage systems beyond LIBs need to be developed.Compared with ion battery,metal-based batteries with metal as the anode have received extensive attention because they can break through the bottleneck of energy density from LIBs.Among them,lithium metal anodes（LMA）and zinc metal anode（ZMA）because of their advantages of ultra-high energy density and suitable redox potential,have become the preferred anode materials for organic and aqueous metal battery systems,respectively.Unfortunately,dendrite growth,interfacial side reactions,and volume changes during cycling,have greatly hindered the commercial development of metal-based batteries.Based on this,this thesis solves the scientific problem of Li/Zn metal anodes in terms of designing three-dimensional collectors for LMAs and regulating the interfacial chemistry of ZMA.The major contents and research results of this paper are as follows:1.Regulating Li nucleation/growth via implanting lithiophilic seeds onto flexible scaffolds enables highly stable Li metal anode.The well-distributed Mo₂C nanoparticles were evenly distributed on the lightweight cotton cloth（Mo₂C NPs@CC）via a simple,in-situ reduction-carbonization method to construct highly stable and dendrite-free LMA.The lithiophilic Mo₂C NPs can work well as nucleation sites to lower the nucleation overpotential of LMA and induce the formation of the thin and uniform Li nuclei layer,thus realizing the dense and smooth Li growth.Besides,the high conductivity of Mo₂C NPs ensures fast electron transfer in the whole electrode and balance the lithiophilicity and conductivity of Mo₂C NPs@CC.As a results,the assembled cell displays excellent cycling stability.This work provides a new insight for improving the lithiophilicity of carbon skeletons.2.Spatial confinement of vertical arrays of lithiophilic SnS₂nanosheets enables conformal Li nucleation/growth towards dendrite-free lithium metal anode.The vertical-aligned SnS₂nanosheet arrays were tightly anchored on the lightweight carbon scaffold by via the electrostatic adsorption and hot bath self-assembly method,for inducing uniform Li nucleation/growth under high current density（SnS₂NSA@CF）.Li₁₃Sn₅formed by alloying reaction between SnS₂nanosheets and Li metal,can work as lithiophilic seeds to guide Li metal uniformly deposited on nanosheet and then form a thin Li-nuclei layer.In the following Li growth process,the deposited Li metal will proceed on the initial Li-nuclei layer and spatially confine into the nanochannels of nanoarray to eliminate the volume change of LMA.Furthermore,the well-defined nanochannel of SnS₂NSA@CF can provide open space for facilitating the fast charge transfer.Consequently,SnS₂NSA@CF realizes high Li utilization and stable Li plating/stripping behavior.This work combines the nucleation behaviors with the charge transfer kinetics to solve the encountered issues of LMA and paves an effective avenue for realizing high-performance lithium metal batteries（LMBs）.3.Homogeneous Li⁺flux distribution enables highly stable and temperature-tolerant lithium anode.A lightweight carbon scaffold composed of parallel-aligned porous carbon fiber,has been proposed to construct stable and temperature-tolerant hybrid Li-carbon anode（HLCA）.The parallel-aligned porous carbon fiber can homogenize Li⁺flux,reduce the concentration polarization near the electrode,and form a stable solid electrolyte interphase（SEI）on the electrode surface,thus guiding smooth Li nucleation/growth.Benefited from the unique structure,the HLCA exhibits excellent cycle stability and long cycle life at the low or ambient temperatures.This work suggests that the carbon skeletons derived from the non-woven fabric can realize the practical application of LMBs.4.Polymeric molecular design towards horizontal Zn electrodeposits at constrained 2D Zn²⁺diffusion.A thin poly（anthraquinone）（PAQ）overlayer on the Zn surface in the manner of spontaneous polymerization reaction of anthraquinone diazonium tetrafluoroborate(AQN₂⁺BF₄^-)is proposed to construct the stable and dendrite-free ZMA（Zn@PAQ）.The PAQ overlayer can restrict the Zn²⁺2D diffusion and homogenize the electric field and the Zn²⁺concentration distribution.In addition,PAQ overlayer can guide parallel growth of Zn electrodeposits with preferred orientation along the（002）plane,thus facilitating uniform Zn nucleation and realizing a planar Zn deposition morphology underneath the overlayer.With the aid of PAQ overlayer,Zn dendrites growth,Zn metal corrosion,and interfacial side reactions are greatly suppressed.Consequently,Zn@PAQ exhibits high columbic efficiency and satisfactory cycle lifespan.This work not only brings new insight into protecting ZMA,but also provides experimental guidance on protecting the other analogous metal anodes.5.ZnF₂-riched inorganic/organic hybrid SEI film stabilizing Zn metal anode.FEC,as an electrolyte additive,can form a ZnF₂-riched inorganic/organic hybrid SEI film on ZMA surface.The FEC-derived hybrid SEI film not only has a strong affinity with Zn²⁺to avoid the formation of Zn dendrites and promote the uniform Zn metal deposition,but also acts as a physical barrier to block the direct contact between the anode and electrolyte and restrict the occurrence of side reactions.Furthermore,FEC additive can regulate the solvated structure of Zn²⁺,thereby reducing H₂O molecules reactivity and preventing the H₂O-induced side reaction from damaging ZMA.As a consequence,the ZMA harvests a long cycle lifespan and high columbic efficiency in the electrolyte that contains FEC additive.This work breaks the thinking orientations and provides innovative mentality in selecting electrolyte additive.