Synthesis Of Hollow Multi-shelled Structural Cu For Application In Lithium Metal Battery

Lithium metal has received widespread attention because of its low redox potential（relative to standard hydrogen electrode-3.040 V）,high theoretical specific capacity(～3860 mAh g^-1),and low density(～0.59 g cm^-3).However,lithium metal cathodes are prone to dendritic growth during charging/discharging,resulting in lithium pulverization and volume expansion,and lithium dendrites may cause internal short circuits in the battery and cause safety hazards.Meanwhile,the fresh lithium exposed during the charging and discharging process will form a solid electrolyte interface（SEI）film by side reaction with the electrolyte,therefore,lithium metal batteries generally have the disadvantages of poor cycling performance and low safety.These inherent limitations are even more acute under low temperature conditions.This paper is designed to construct dynamic intelligent three-dimensional（3D）collectors（DI-Cu-HoMSs）using a copper hollow multishell layer structure（Cu HoMS）,whose higher effective specific surface area can effectively reduce the local current and increase the mass transfer active sites,and whose multiple shell layers can balance ion diffusion and uniform current distribution,thus effectively inhibiting lithium dendrite growth and improving the safety and cycling stability of the battery.The main research results of this thesis are as follows.（1）By increasing the concentration of metal precursor,prolonging the adsorption time and increasing the calcination rate,the single,double and triple CuO HoMS with the size of 1～1.5μm were successfully prepared by sequential templating method.Cu HoMS was obtained by reduction in sodium borohydride solution,and the physicochemical properties of CuO HoMS and Cu HoMS were compared.The results showed that the specific surface area after the reduction of CuO HoMS to Cu HoMS.（2）The electrochemical properties of Cu HoMS with single,double and triple shells and Cu nanoparticles（NP）as lithium anode skeleton was investigated.The results show that Cu HoMS as lithium anode skeleton has better cycling stability and higher coulombic efficiency.Among them,the best battery performance was exhibited when tri-shell layer Cu HoMS（3S-Cu-HoMSs）was used as 3D skeleton.At 30℃,the half cell can cycle stably 300 times,and the average coulombic efficiency is up to 99%;When the temperature is-40℃,the coulombic efficiency can still over 85%after 50cycles.In addition,when the full cell is assembled with LiCoO₂ cathode of the whole battery,the specific capacity of the first cycle reaches t 134 mAh g^-1 at 0.1C and the specific capacity can be stabilized above 113 mAh g^-1 after 50 cycles.This is due to the DI-Cu-HoMSs based on 3S-Cu-HoMSs can provide the highest effective specific surface area,which can effectively reduce the local current,inhibit the growth of lithium dendrite,tend to uniform deposition of lithium isotropic,and effectively improve the coulombic efficiency and cycle life of lithium battery.This work provides a new design strategy to improve the stability and safety of lithium metal batteries at low temperature.