Preparation,Modification And Application Of Lithium Metal Anodes Preparation,Modification And Application Of Lithium Metal Anodes

The rapid development of electric vehicles,smart grids,electronic devices and other industries has put forward higher requirements on the energy density of lithium-ion batteries.The energy density of conventional lithium-ion batteries with graphite as the anode material has reached its limit,and it is difficult to improve it significantly.Replacing graphite anode with lithium metal anode is an effective method to improve the energy density of lithium batteries.Lithium metal is a potential anode material for lithium batteries due to the advantages of high theoretical capacity,lightweight,low electrochemical potential,good electronic conductivity and so on.However,there are still many issues in lithium metal anode,such as high chemical reactivity,large volume expansion effect,uncontrollable growth of lithium dendrites,poor interfacial stability.These issues lead to low Coulombic efficiency,poor cycling performance and low safety performance of batteries,and thus limit the practical application of lithium metal anode.So it is meaningful to modify the lithium metal anode.In this paper,several effective modification strategies have been put forward based on the existing issues of lithium metal anode.High-performance lithium metal anodes are prepared.Meanwhile,the application potential of the modified lithium metal anode in full cells is investigated.The main research content of this paper is as follows:(1)Lithiophilic GaInSnZn liquid metal was coated on Cu current collector using a coating method,and the Ga in liquid metal can spontaneously alloy with Cu to form Cu-Ga alloy.The alloying reaction can increase the wettability of liquid metal on Cu current collector,which can enable liquid metal to tightly attach on the surface of Cu current collector,effectively improving the lithiophilicity of Cu current collector.Liquid metal coating can obviously lower the lithium nucleation barrier during the electrochemical deposition process and promote the uniform lithium nucleation and growth.The growth of lithium dendrites is obviously inhibited.The Coulombic efficiency and cycling stability of batteries are obviously enhanced.Highly stable composite lithium metal anodes are prepared and can be successfully applied in full cells with LiFePO4 cathodes.(2)It is found that liquid metal can keep stable with MXene film after coating fluid and lithiophilic GaInSnZn liquid metal on flexible and freestanding Ti3C2Tx MXene film.Lithiophilic liquid metal on MXene film can lower the lithium nucleation overpotential and promote uniform lithium nucleation and growth.The flexible and freestanding MXene/liquid metal composite current collector can be used to construct highly stable and dendrite-free composite lithium metal anodes.The fabricated composite lithium metal anodes exhibit superior electrochemical performance in full cells with LiFePO4 cathodes.(3)A lithium-based alloy layer is constructed through the spontaneous alloying reaction between liquid metal and metallic lithium by coating fluid GaInSnZn liquid metal on the surface of lithium foil.The lithium-based alloy layer has corrosion-resistant ability,high conductivity and superior lithiophilicity.Under the regulation of the lithium-based alloy layer,the interfacial stability and electrochemical performance of the modified lithium metal anode are obviously improved in commercial carbonate electrolytes.In addition,the growth of lithium dendrites is effectively inhibited.The modified lithium meal anodes can work stably in high-voltage full cells with LiNi0.5Mn1.5O4 cathodes.(4)MXene/COF composite current collector is constructed by introducing lithiophilic COF-LZU1 nucleation seeds into flexible and freestanding Ti3C2Tx MXene current collector.COF-LZU1 nucleation seeds are distributed among the MXene framework.The lithium nucleation overpotential is effectively reduced due to the existence of lithiophilic COF-LZU1 nucleation seeds.Uniform,dense and dendrite-free lithium deposition is achieved.The fabricated composite lithium metal anodes can work stably in high-energy-density lithium-sulfur full cells.