Synthesis And Electrochemical Performance Study Of Antimony-based Anode Materials For Lithium Ion Batteries

Among kinds of electrochemical energy storage devices,lithium-ion batteries are widely used in daily life due to their high energy density,long cycle life,environmental protection,and portability.However,currently commercial lithium-ion batteries use graphite as the anode electrode material.Its lower theoretical specific capacity(372 mA h g^-1)can no longer meet the needs of human society for high density energy storage devices.Compared to graphite anodes,antinomy-based materials have a higher theoretical specific capacity(660 mA h g^-1)and a safer deintercalation lithium platform（0.5-0.8 V）.However,during the continuous charge and discharge process,the antinomy-based material has a serious volume expansion（>150%）,which easily causes the material structure to collapse and then lead to the capacity of battery decays too fast.Therefore,the topic of this research mainly optimizes the antinomy-based materials from the aspects of carbon coating and alloying to improve the electrochemical performance of these materials.Sb@C/EG composites,NiSb/C nanosheet composites and SnSb/N-C nanosheet composites were synthesized by freeze drying,high temperature calcination method as well as the sodium chloride template method.Characterized by electrochemical performance test,the main research contents and results are as follows:（1）Sb@C/EG composite was synthesized by freeze-drying and high-temperature calcination.Sb@C nanoparticles were uniformly embedded in the graphite sheets.The coating of carbon layer can significantly increase the conductivity of the total material while effectively alleviating the volume expansion of the metal crucible.In that case,the obtained material shows good rate and cycling performance.It can reach 480 mA h g^-1 even after 600 cycles under the current density of 1.0 A g^-1.（2）NiSb/C nanosheet composite was synthesized by simple freeze drying and high temperature calcination using a sodium chloride stencil method.Among the synthetic materials,NiSb nanoparticles are uniformly distributed on the carbon nanosheets.This special structure shortens the ion diffusion distance and effectively solves the problem of volume expansion and structural collapse of this material.At the same time,the addition of nickel metal can act as an inert framework,which is beneficial to maintain the morphology of this material.The stability of the structure demonstrates excellent electrochemical performance.Had a capacity of 405 mA h g^-1 after 1000 cycles at a current density of 1.0 A g^-1.（3）SnSb/N-C nanosheet composite was synthesized by freeze-drying and high-temperature calcination using sodium chloride template method.SnSb nanoparticles were uniformly distributed on nitrogen-doped carbon nanosheets.This structure effectively alleviated the volume expansion of SnSb nanoparticles,and achieve more excellent cycle stability.At the same time,the introduction of electrochemically active material metal tin can effectively increase the lithium storage capacity of the material,thereby achieving higher capacity.It can deliver a high capacity of 537.5 mA h g^-1 after 1000 cycles at a current density of 1.0 A g^-1.