Fabrication And Application Of Lithium Metal Anodes Based On Carbon Nanotube Films

With the rapid development of portable electronic devices and electric vehicles in recent years,energy storage devices,therefore,require higher energy density.Besides,the increasingly advancement of flexible wearable electronic devices also needs energy storage devices with high capacity,high stability and flexibility.However,it is hard for traditional lithium-ion batteries to meet these requirements.The lithium metal anode has drawn lots of attention due to its highest theoretical capacity(3,860 m Ah g^-1 or 2,061 m Ah cm^-3)and lowest electrochemical potential?3.04 V vs.SHE?.Nonetheless,lithium dendrites tend to grow during the charging/discharging process,resulting in low coulombic efficiency and poor cycle stability of the lithium metal anodes.To solve these problems,a three-dimensional?3D?framework made of carbon nanotubes?CNTs?was designed to stabilize the deposition of lithium and suppress the volume expansion during the lithium deposition.The application of the Li@CNT anode in flexible batteries was explored.Moreover,the performance of the lithium metal anode was largely improved by increasing the lithiophilicity of the 3D current collector,which was realized by modifying the CNTs with ZnO particles.The main achievements are as follows:?1?A dendrite-free lithium metal anode was prepared by using 3D carbon nanotube?CNT?film as the current collector.The good mechanical properties and electrical conductivity of single-walled carbon nanotubes?SWCNTs?effectively increased the specific surface area,promote electron conduction,homogenize the flux of lithium ions and accommodate huge volume changes.Thus,the generation of lithium dendrites was successfully suppressed.The soft-pack battery assembled by the Li@CNT anode was able to maintain stable voltage and capacity under bending conditions.?2?Based on the investigation of the influence of electric conductivity and lithiophicility on the lithium plating behavior on the 3D matrixes,ZnO modification was used to promote even Li deposition on CNT film.Thanks to the superior conductivity of CNTs and the lithiophilicity provided by ZnO and products of reaction between lithium and ZnO,the Li@ZnO/CNT anode exhibited high stability and excellent rate performance.In addition,facile synthesis of ZnO by hydrothermal method makes it convenient to control its size and amount,which is beneficial to the application of this method in other systems.In summary,CNT network can be used as a skeleton to deposit metallic lithium uniform Ly and maintain a proper flexibility,making it promising to support a free-standing and flexible lithium metal anode.When the CNTs are properly modified,the utilization efficiency of lithium can be improved,and a more efficient and stable metal lithium anode can be realized.