Preparation Of Ni-Based Hollow-Structured Binary Transition Mental Oxides And Lithium Storage Performance Research

As a novel energy storage device,lithium-ion batteries（LIBs）have been widely used in various kinds of portable electronic devices now.However,the specific capacity of graphite anode materials used in the commercial lithium-ion batteries is very low,the theoretical value is 372 mA h g-1,but in practical applications,the value is always far below it.Furthermore,the charge-discharge voltage platform of graphite is too low,which is easy to cause the generation of lithium dendrites during the overcharge of battery.The lithium dendrites will impale the separator and cause the battery short circuit,even lead to an explosion of the battery.Thus,it is of great importance to develop a kind of lithium-ion battery anode materials of high capacity and high security.Among numerous lithium-ion battery anode materials,transition metal oxide has attracted widely attention and research because of its high specific capacity and high security.However,the electrical conductivity of transition metal oxide is poor,and the volume change during charge-discharge is very large,which greatly restrict its practical application.Therefore,the paper focused on the two defects and aimed at improving the electrical conductivity and the structural stability of transition metal oxide.The works were carried out as following:The Co-doped hollow-structured NiCo₂O₄/MWCNT composite and the Cu-doped hollow-structured Cu₃NiO₄/MWCNT composite were synthesized via the simple“impregnation-reduction-oxidation” method.The charge-discharge voltage platform of Ni-based oxide is low,which will enhance the overall energy density of the battery.The adulteration of Co will enhance the specific capacity of the material,the adulteration of Cu,on the one hand,will enhance the cycling stability of the material,on the other hand,will reduce the preparation cost of the material.The hollow structure will effectively relieve the volume change of the material during charge-discharge,and the addition of MWCNT will enhance the electrical conductivity of the material.And more importantly,due to the synergetic effect and the complementarity of the different mental elements,the lithium storage performance of the material will be enhanced further.The NiCo₂O₄/MWCNTcomposite retained the high specific discharge capacity of 1159.2 m A h g-1 over 200 cycles at a current density of 0.5 A g-1,which showed the excellent high capacity performance;and the Cu₃NiO₄/MWCNT composite still retained the high specific discharge capacity of 400 m A h g-1 over 1000 cycles at a high current density of 0.5 A g-1,the capacity decay was only0.023% per cycle,which showed the excellent cycling stability.