Preparation And Electrochemical Performance Of High Energy Density Electrode Materials

Lithium-ion batteries(LIBs)have been widely studied due to its environmental friendliness,long cycle life,lofty specific energy and high output voltage.Graphite with theoretical specific capacity of 372 mAh g'1 is used as anode for LIBs,which cannot meet the demand of high specific energy batteries.It is urgent to develop high specific capacity electrode materials,such as lithium and silicon anode.For the silicon anode,the huge volume change during cycling process results in poor cycle stability.For the lithium anode,the growth of dendritic or mossy Li during cycling process leads to the inferior cycle life and serious safety issues.With low cost and abundant resources of potassium elements,potassium-ion batteries(KIBs)have attracted considerable attention.However,the radius of the potassium ion is larger than that of lithium ion,which is quite complicated to discover an appropriate high specific capacity electrode material that can accommodate huge volume expansion during potassium ion insertion/extraction process.In this work,nanoporous copper,silicon and antimony are successfully synthesized by vacuum distillation approach.Besides,the effects of technics parameter,precursor composition,vacuum temperature and time on microstructure and electrochemical performance of the product are investigated.(1)Nanoporous copper(NP-Cu)is prepared by vacuum distillation method from commercial brass foil.The effects of technics parameter on morphology and electrochemical property are explored.The voids of NP-Cu can be easily regulated by adjusting the distillation condition.The byproduct of zinc elements can be recycled.As a current collector,the optimized NP-Cu can inhibit the growth of Li dendrite and mitigate the huge volume change of Li metal anode during cycling process,resulting in stable SEI layer and electrode structure.As a result,the NP-Cu current collector can achieve an improved cycling stability.Besides,the Li@Cu|Li(Ni0.8Co0.1Mn0.1)O2 cell also exhibits an enhanced cycling capability,indicating its great potential for practical application.(2)Nanoporous silicon(NP-Si)is synthesized by vacuum distillation method from commercial MgzSi alloy.The effects of vacuum temperature and time on microstructure and electrochemical property are studied.The porosity and pore size of NP-Si can be easily controlled by adjusting the distillated temperature and time.The byproduct magnesium elements can be recycled.The optimized NP-Si anode for LIBs can accommodate large volume change and accelerate ion transport during the cycling process,exhibiting excellent cycling stability and rate property.These results suggest that the green,scalable,and controllable approach may offer a direction for the commercialization of Si anodes.This method may also be extended to construct other nanoporous materials.(3)Nanoporous antimony(NP-Sb)is composed by vacuum distillation method from commercial Zn-Sb alloy.The effects of Zn-Sb alloy composition and vacuum temperature on morphology and electrochemical capability are explored.The byproduct zinc elements can be recycled.The void structure of NP-Sb can be regulated by controlling the evaporation temperature and alloy proportion.The optimal NP-Sb anode for KIBs exhibits the improved electrochemical capability,attributing to that the unique porous structure can relieve large volume expansion and accelerate ion transport during the charge/discharge process.