Construction And Performance Study Of Lithium Anode In Lithium Metal Batteries For Ship Energy Storage

The rapid development of the shipping industry has promoted international economic exchanges.However,the environmental pollution caused by ship exhaust emissions is also obvious.In order to reduce environmental pollution and achieve the targets of“carbon peak”and“carbon neutral”,the efficient utilization of fossil fuel oil and the application of renewable energy such as solar energy and wind energy on new-type hybrid power system and electric propulsion system are the development trend of ship power.To ensure the efficient operation of oil-fired generator and the stability of ship microgrid power system,ships are equipped with energy storage system is imperative.Lithium metal batteries such as lithium sulfur batteries and lithium oxygen batteries with lithium metal as the anodes have the advantages of high energy density,stable voltage,long life,and environmental friendliness,which break through the bottleneck of low energy density of traditional lithium-ion batteries with graphite as the anode.Lithium metal batteries are new-generation high-performance energy storage system with development prospect.However,when lithium metal is used as the anode materials of lithium metal batteries,lithium dendrites and volume change are generated during cycling,which can lead to capacity attenuation and safety hazards.the growth of lithium dendrites is closely related to the deposition process of lithium from ionic form to solid form.The deposition process of lithium involves nucleation and growth of lithium.In this paper,according to the mechanism of lithium dendrites growth,focusing on the lithium dendrites growth and volume expansion,starting with regulating uniform deposition of lithium,lithium metal anodes with different structure have been constructed to inhibit lithium dendrites growth and relieve volume expansion.The main research contents and results are as follows:（1）A Li-Sn composite anode with Sn powder uniformly distributed in lithium metal was prepared by a rolling method.lithiophilic Sn₂₂Li₅ alloy particles is in situ generated between Sn powder and Li to form.After lithium is stripped,the uniformly distributed Li₂₂Sn₅ alloy particles on the surface of the lithium metal can regulate the local current density.The surface of the Li-Sn electrode is smooth after 5 cycles at a current density of 1 m A cm^-2.The surface of the lithium foil anode has obvious agglomeration of deposited lithium.In the symmetrical battery test,the Li-Sn electrode shows a lifetime of 1200 h without significant voltage fluctuations.（2）A nitrogen-doped carbon fiber membrane was introduced as the interlayer between lithium metal and separator when assembling the cells.The composite anode is prepared during cycling.The interlayer with 3D structure and lithium sites can not only alleviate the volume change of lithium metal,but also direct lithium to deposit uniformly.The symmetric cell can stably cycle for 1200 h at the current density of 1 m A cm^-2.（3）An electrical insulation-conductive double-layer structure current collector was prepared with the significantly difference of conductivity of the metal-organic framework materials before and after carbonization.The carbonized ZIF-67 is converted into nitrogen-doped porous carbon with uniformly distributed Co nanoparticles,and acted as the bottom layer to dynamically store lithium.The ZIF-67 is insulating,and lithium ions in the electrolyte can pass freely through the regularly distributed pore structure.The ZIF-67 can plays a rore in uniformizing the ion current in the upper layer.The volume change rate is only136%after depositing lithium in a double-layer structure electrode with a surface capacity of5 m Ah cm^-2.The surface of the double-layer electrode structure is smooth,and the ZIF-67particles on the surface are still clearly distinguishable after 100 cycles.The symmetrical cell assembled with the double-layer electrode structure can be cycled stably for more than 1150 h with a voltage hysteresis of 11 m V at a current density of 1 m A cm^-2.（4）Nickel foam（NF）with rich internal three-dimensional space is used to accommodate the deposited lithium to achieve the purpose of suppressing volume expansion.Due to the poor lithophilicity of nickel foam,a honeycomb-like Ni₃N nanosheet arrays decorated nickel foam（Ni₃N@NF）was prepared by hydrothermal method and subsquent heat treatment.The Ni₃N@NF-Li composite anode was prepared by electroplating lithium into Ni₃N@NF.The Ni₃N nanosheet arrays can increases the specific surface area,which can reduce the local current density.The excellent lithophilicity of Ni₃N@NF nanosheets exhibit a lower nucleation barrier than NF during the depositing lithium,and induce the directional deposition of lithium on the three-dimensional framework.Experimental results show that the symmetrical cell assembling by Ni₃N@NF-Li can cecle more than 1500 h at a current density of 1 m A cm^-2.