The In-situ Growth Of Metallic Compound As Anodes For Lithium Ion Batteries

Transition metal compounds show potential application as anode for Li-ion batteriesowing to their high theoretical capacity (500~1000mAh g-1) based on a novel redoxreaction mechanism. However, they suffer from low electronic conductivity and structuredestruction in cycling, which results in unsatisfied electrochemical performance.Improving the electronic conductivity and structure integrity in cycling are the key issuesto enhance the electrochemical performance of transition metal compounds. Threedimensional porous metal foams show good electronic conductivity and structure stability,which can distinctly improve the electrochemical performance of transition metalcompounds when using as composite electric substrates. In this paper, we report thepreparation of transition metal compounds on Ni and Cu foams via in situ methods. Theelectrochemical performance of the composite materials as non-binder anodes for Li-ionbatteries and the inner factors that affect the electrochemical performance was studied. Theresults are as follows:NiO/Ni and Li3VO4/Ni composite architecture were prepared via hydrothermalpretreatment and subsequent sintering using Ni foam as substrate. After100cycles at0.15C, the charge and discharge capacities of NiO/Ni are704and721mAh g-1, respectively.After60cycles at various rates from0.06to10C, the discharge capacity of NiO/Ni canrestore to745mAh g-1when lowering the current to0.06C. The excellent electrochemicalperformance of the NiO/Ni originates from electrochemical activation and electrochemicalreconstruction that lead to the formation of a new porous architecture in cycling; After100cycles at0.3C, the charge and discharge capacities of Li3VO4/Ni are378and379mAh g-1,respectively. After50cycles at various rates from0.4to15C, the discharge capacity ofLi3VO4/Ni can restore to404mAh g-1when lowering the current to0.4C. The excellentelectrochemical performance of the Li3VO4/Ni is relevant to the formation of a uniquearchitecture that consists of nanoparticles in cycling.CuхO/Cu (x=1,2), Cu2O/Cu and Cu2S/Cu were prepared via thermal oxidation,hydrothermal and low temperature sulfuration methods using Cu foam as substrates, whichshow excellent electrochemical performance as anodes for Li-ion batteries. After50cyclesat various rates from0.2to12C, the capacity retention of the CuхO/Cu (x=1,2) canmaintain104%when lowering the current to0.2C. The superior electrochemicalperformance of the CuхO/Cu (x=1,2) is relevant to electrochemical activation andelectrochemical reconstruction that lead to the formation of a special porous architecture in cycling; After50cycles at various rates from0.2to35C, the capacity retention of theCu2O/Cu can maintain98.9%when lowering the current to0.2C; After60cycles atvarious rates from0.3to60C, the capacity retention of the Cu2S/Cu can maintain97.8%when lowering the current to0.3C.In situ growth can improve the contact between transition metal compounds and metalfoams, which can effectively suppress the pulverization and aggregation of transition metalcompounds and induce the electrochemical reconstruction in cycling, improving theelectrochemical performance.