The Preparation And Stabilization Of 3D Hollow Metal Oxide@Polymer Core-shell Nanotube Arrays As Anode For Lithium Ion Batteries

Nowadays as the applications have expanded to portable electronic devices and hybrid electronic vehicles,there is an increasing demand for lithium-ion batteries?LIBs?with high rate performance and long cycle life.Metal oxides are promising anode material candidates for LIBs due to their high theoretical capacity.However,the huge volume expansion during cycling processes would result in the destruction of electrode structure and poor cycle performance.Moreover,they always suffer from poor electronic conductivity,leading to bad charge/discharge performance at high rate.In order to achieve the goal of long life and high rate properties,structural design and modification is indispensable.In this paper,3D core-shell nanotube arrays anodes were constructed by utilizing ZnO nanowire arrays as the template,and furthermore SnO₂@PPy and Fe₂O₃@PPy nanotube arrays anodes were prepared.The mechanism of the enhanced electrochemical performance was investigated by morphology characterization and electrochemical analyses.The large internal void space in nanotube could buffer volume change due to the internal expansion,which is beneficial for the structural stability.As a result,SnO₂@PPy nanotube arrays anode exhibits better electrochemical performance than SnO₂ nanoparticle anode and bare SnO₂ nanotube arrays anode and a reversible capacity of 646 mA h g-1 was retained after 150 cycles at the current density of 100 mA g-1,corresponding to 63 % capacity retention.And the nanotube with thin shells could provide a short Li+ transport path,which helps to improved rate properties.Even at a high current density of 5000 mA g-1,the specific capacity of SnO₂@PPy anode still retains a value of 221 mA h g-1.Based on them,the Fe₂O₃@PPy nanotube arrays anode is easier to synthesize and more appropriate for quantity production.It is capable of retaining a high capacity of 665 mA h g-1 after 150 cycles at the current density of 100 mA g-1.It deliver the discharge capacity of 333 mA h g-1 at current density of 1600 mA g-1.The XPS spectrum of Fe₂O₃@PPy nanotube arrays demonstrates that core-shell structure is benifical for the improved reversible extent of electrochemical reaction.