The Preparation And Performance Study Of Ni-based Oxides And Its Composites As Anodes For Lithium Ion Batteries

With the increasing demand for clean and sustainable energy,the high-capacity energy storage systems have been developed rapidly.Lithium-ion batteries?LIBs?dominate the consumer electronics market due to their light weight,long cycle life,low self-discharge,low cost,low pollution,and high energy and power density.Nevertheless,as commercial anode material of lithium-ion batteries,the theoretical capacity of graphite is very low,which is only 372 mAh g^-1.It is urgent to develop novel anode materials with high-capacity LIBs.Over the past few decades,transition metal oxides?TMOs?have been considered as potential anode materials due to their high theoretical capacity(¹000 mAh g^-1)and excellent lithium storage capacity.To overcome the dramatic volume expansion and improve the ion/electron conductivity of TMOs,several strategies are taken,such as fabricating nanostructure,structural optimization,and composite modification.In this work,NiO-based nanomaterials are used as the main research object.To improve the conductivity and structural stability of the obtained anode materials,the NiO has been combined with metal or other oxides,which can improve the electrochemical properties.The main research content and the research results obtained are as follows:The NiO nanoparticles and scaly NiO/Ni composites as anode materials were prepared through hydrothermal reaction followed by thermal treatment under different atmospheres.As anode materials for LIBs,the NiO/Ni composites exhibited excellent cycling performance and rate performance.The reversible specific capacity can still maintain 844.7 mAh g^-11 after 80 cycles at the current density of 200 mA g^-1,and the retention rate of the capacity is 107.92%.The effect of reaction temperature and pyrolysis temperature has also discussed.The NiO/Ni composites prepared at a solvothermal temperature of 160°C and a pyrolysis temperature of 350°C exhibits the best electrochemical performance.A variety of metal oxides and their comosites were prepared through hydrothermal reaction followed by thermal treatment,such as single-component of NiO,Co₃O₄ and three-component of Ni O-Co₃O₄-Fe₂O₃ composites,two-component of NiO-Co₃O₄ composites.As anode materials of LIBs,NiO-Co₃O₄-Fe₂O₃ composites and NiO-Co₃O₄ composites show superior electrochemical performance.The reversible capacity can still maintain1360.2 and 1169.3 mAh g^-11 after 100 cycles at a current density of 200 mAh g^-1,respectively.At the same time,the effect of the ratio of nickel acetate and cobalt acetate in the preparation of NiO-Co₃O₄ composites and the effect of the molar amounts of ferric nitrate in the preparation of NiO-Co₃O₄-Fe₂O₃ composites are also investigated.When the molar ratio of 1:3,the electrochemical performance of the prepared Ni O-Co₃O₄ composites can be obtained,and when the molar amount of iron nitrate is 0.4 mmol,the electrochemical properties of the prepared NiO-Co₃O₄-Fe₂O₃ composites are the best.The NiO-ZnO composites were obtained through hydrothermal reaction followed by calcining treatment,which exhibited excellent electrochemical performance compared with NiO and ZnO.The reversible capacity of NiO-ZnO can still maintain978.3 mAh g^-1after 200 cycles at the current density of 200 mA g^-1,which is much higher than NiO(550.8 mAh g^-1)and ZnO(211.4 mAh g^-1).When estimated at current densities of 0.1,1,0.2,0.5,1,2,3,and 0.1 A g^-11 for 10 cycles,it shows excellent rate performance and deliveres the average reversible specific capacities of738.53,735.54,714.26,688.14,630.82,571.79,and 773.69 mAh g^-1,respectively.At the same time,the effect of the pyrolysis temperature are also discussed.the best electrochemical performance of NiO-ZnO can be obtained when the pyrolysis temperature is 500°C.