| Both metal oxide and lithium metal have been widely concerned because of their high theoretical capacities in lithium ion battery anode materials.Among them,metal oxides are the promising anode materials for lithium ion battery because of their environmental friendliness and low operating voltage.However,the poor conductivity and volume changes of metal oxides during charging and discharging greatly deteriorate cycle life of batteries.Due to the synergistic effect between the two metals,the binary metal oxides containing two metals exhibit good conductivity.In order to further improve the lithium storage performance of materials,binary metal oxides with suitable stable structure need to be designed.In addition,lithium metal material has low density(0.534 g cm-3)and the most negative redox potential（-3.04 V vs.SHE）,which is the most potential anode material for high-performance lithium-ion batteries.However,lithium dendrites and dead lithium generated on the lithium metal anode during the process of repeated charging and discharging can puncture the membrane and block ion transfer,respectively,resulting in heat inside the battery,further triggering a fire.In order to solve the problem of uneven deposition of lithium,a uniform lithiophilic metal oxide layer is constructed on the surface of the current collector,which can effectively induce uniform deposition and stripping of lithium in the negative electrode.In this paper,aiming at the issues of binary metal oxides,the strategies of microwave preparation combined with calcination treatment,and electrostatic adsorption to control the structure of materials are proposed,respectively.By optimizing the preparation parameters,the conductivity and structural stability of materials are improved,and the binary metal oxides show good electrochemical performance.Based on the lipophilicity of metal oxides and the advantages of high theoretical capacity of lithium metals,the lithium metal anode materials modified by metal oxides are developed,which effectively alleviate the problem of uneven deposition of lithium.In view of the issues of the stability and homogeneity of lithiophilic metal oxides in lithium anode,strategies are proposed to improve the cyclic stability of lithium deposition/stripping by adjusting the material properties of lithiophilic layer and optimizing the surface state of three-dimensional current,and effectively avoid the formation of lithium dendrite and dead lithium.The research results are as follows:1.Cotton-like zinc cobalate and porous magnesium cobalate with stable structures are successfully prepared by microwave preparation and calcination,which improve the electrochemical properties of the materials.The zinc cobalate precursor prepared by microwave method formed the cotton-like structure and then tended to agglomerate with the increase of calcination temperature.In the calcination temperature range of350～500 oC,the electrochemical properties of cotton-like zinc cobalate prepared at400 oC are the best:showing high maintained specific capacity of 673.5 m Ah g-1 after50 cycles for constant current charge and discharge at the current density of 200 m A g-1,with a capacity retention of 78.5%.The magnesium cobalate precursor prepared by microwave method forms porous sheets and then turns into nanoparticles with the increase of calcination temperature.In the calcination temperature range of 500～650oC,the magnesium cobalate prepared at 600 oC exhibits the best capacity performance:after 100 cycles at the current density of 200 m A g-1,it still has the capacity of 1130.1m Ah g-1,and the capacity retention is 96.3%.2.A flower cluster-like Sb2WO6/r GO（r GO:reduced graphene oxide）composite is prepared by the electrostatic adsorption of oxygen functional groups on two-dimensional GO（graphene oxide）surface with metal ions to guide the growth of Sb2WO6 on GO surface,which improve the conductivity and structural stability of the oxide.Compared to pure Sb2WO6 with particle morphology,Sb2WO6/r GO with flower cluster morphology exhibits the better structural stability.And,GO is reduced to r GO,which could improve the electrical conductivity of Sb2WO6.At the current density of 2A g-1,the Sb2WO6/r GO composite maintains the capacity of 545.2 m Ah g-1;when the current density is 200 m A g-1 and the charge-discharge cycle is 150 cycles,the capacity of Sb2WO6/r GO composite is 577.1 m Ah g-1.The capacities are obviously higher than that of pure Sb2WO6.3.The synthesized Ti3C2Tx MXene/Ti O2 exhibits decent conductivity and structure stability.Compared with nano Ti O2 modified copper collector（nano Ti O2modified copper collector is shortened to Nano Ti O2@Cu）,Ti3C2Tx MXene/Ti O2modified copper collector（abbreviated as:MXene/Ti O2@Cu）can guide the uniform and compact deposition of lithium.In the performance test of symmetrical batteries,during cycling at the current density of 3 m A cm-2 and deposition capacity of 3 m Ah cm-2,the Nano Ti O2@Cu shows larger unstable overpotentials less than 250 h,MXene/Ti O2@Cu can cycle smoothly for 500 h.4.A three-dimensional carbon framework with Zn O and oxygen vacancy uniform modification is designed and fabricated,as a lithium anode collector,which effectively reduce the local current density and improve the cyclic stability of the electrode material under large current currents.The lithiophilic zinc oxide can control the deposition of lithium ion the surface of carbon frame,and the oxygen vacancy promotes the transport of lithium ion on the surface of carbon frame.The synergistic effect of the two both can effectively inhibit the formation of lithium dendrite and improve the cyclic stability of lithium anode.The prepared carbon frame with deposited lithium is assembled into a symmetric battery,during cycling at the current density of 5 m A cm-2 and the deposition capacity of 5 m Ah cm-2,the unmodified three-dimensional carbon frame can only cycle stably for about 480 h,the carbon frame modified with zinc oxide and oxygen vacancy can cycle steadily for 1500 h. |
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