Preparation And Performance Study Of Metal Lithium Anode Based On Tin Oxide Modified Three-dimensional Current Collector

Lithium ion batteries?LIBs?have attracted much attention as one of the most mature energy storage methods in the world.Moreover,the energy density of LIBs is gradually approaching the limit,so that it has become a hot topic to develop an energy storage devices with higher energy density.Lithium metal batteries?LMBs?,with a higher energy density and faster ion transmission speed,have become the most popular choice to LIBs.Due to the high chemical activity of the lithium metal anode,it is easy to produce lithium dendrites during the cycle and infinite volume change,which hinder its development.Tin-based anode materials such as tin dioxide?SnO₂?will alloy with lithium during cycling,which causes dramatic volume changes,shedding from the current collector and further capacity decline.The solution strategies for tin-based materials mainly include nanotechnology and compounding with other materials.Although the construction of a stable conductive skeleton in the lithium metal anode can further improve the above problems,but the conductive skeleton mainly composed of metal or carbon materials generally does not have lithium-loving properties.Based on the above factors,a three-dimensional current collector coated with tin dioxide?SnO₂?was constructed by water bath method to maintain a three-dimensional structure while maintaining good lithium wettability to obtain a lithium metal anode with a three-dimensional conductive framework.The research work of this thesis mainly covers the following two aspects:Firstly,an ultrastable carbon textiles?CTs?-based host with excellent infiltration for both metallic Li has been designed and exhibits more flat voltage profiles,lower stripping/plating overpotential,and better cycling stability both in symmetric cell and full cell configurations,even in additive-free carbonate-based electrolyte compared with pure Li electrodes.The highly conductive and mechanically robust three-dimensional CTs not only offer a stable scaffold against hyperactive lithium but also enable uniform nucleation and growth during stripping/plating process,which effectively suppress the dendrite growth and stabilize the electrode dimension.This facile strategy provides new insights into the design of stable hosts with prestored alkali metal to address the multifaceted issues in LMBs.Next,SnO₂ deposited Ni foam?SNF?,by in-situ growth of SnO₂ on the surface of the nickle foam,is employed to construct two distinct lithiophilic architectures namely,Li coated SNF skeletons and Li infiltrated SNF frameworks.The cycling stability and dendritic behavior of these lithiophilic architectures are systematically compared.Both of these lithiophilic architectures significantly outperformed bare Li foils in terms of cycling performance and electrode dimension stability.The fully covered lithiophilic host with Li infiltrated SNF frameworks shows much better cycling stability and lower hysteresis than the porous lithiophilic host with Li coated skeletons,especially at high current densities and large stripping/plating capacities.In full-cell configurations,the batteries based on Li infiltrated SNF frameworks also show significantly higher rate capabilities than Li coated SNF skeletons counterpart.Our results provide a better choice to design stable lithiophilic hosts for high-rate and high-capacity lithium metal anodes.