| “The 2021 Government Work Report and The 14th Five-Year Plan”both propose to strive to achieve a carbon peak by 2030 and carbon neutralization by 2060.This places higher technical demands on establishing clean,low-carbon,safe,and effective energy systems,and further defines the strategic position of the development of new energy industries in green development.As the development strategy of“Electric China”is proposed,the research of electronic devices with high endurance and high security（such as new energy vehicles,portable laptops,smartphones,etc.）is directly related to the people’s good life.Lithium metal anode（LMA）is considered a promising anode material for high-energy-density batteries,which has a high theoretical specific capacity(3860m Ah g-1),low mass density(0.534 g cm-3),and low electrochemical redox potential（-3.04 V relative to standard hydrogen electrode）.However,the uncontrollable growth of lithium（Li）dendrites,the formation of“dead Li”and the“host-less”characteristics of Li metal limit its commercial application.Given the above problems,this research has made some efforts to improve the Li metal uneven deposition and alleviate the volume expansion of LMA by the three-dimensional（3D）structure design and the investigation of the Li metal deposition behavior on different composite anodes,to improve the Coulombic efficiency and cycle lifespan of LMA.The specific contents include the following three aspects:1.A polyvinylidene fluoride（PVDF）skeleton with a silver concentration gradient is designed as the three-dimensional host of LMA.In this unique structure,the PVDF skeleton insulated at the top inhibits the preferential top Li growth,while the high lithiophilic bottom region offers abundant Li nucleation sites to ensure the uniform Li lithium deposition from bottom to top.This gradient three-dimensional structure design can realize the efficient and stable cycle of LMA even in the high current and high surface capacity test system.2.Three different carbon-based composite anodes were prepared by the simple composite method.The deposition behavior,deposition morphology,and electrode volume expansion of Li metal in different carbon-based composite anodes are studied in detail.The composite mechanism of Li metal and different Li affinity sites is further explored,the electrochemical performance of Li metal three-dimensional carbon-based composite anode is improved,and a stable uniform Li metal growth mode is realized.3.To make the composite anode suitable for a more severe environment,the Li metal composite anode interface is optimized by introducing local high concentration electrolytes（LHCEs）.Compared with carbonates,LHCE with low viscosity,good wettability,and high conductivity can induce more uniform Li plating/stripping and further reduce the side reaction between Li metal and electrolyte.Therefore,it has achieved a stable cycle of more than 300 weeks in 0.5 m A cm-2-1 m Ah cm-2,realizes large-scale block uniform Li metal deposition,and greatly improve the high rate performance of 3D Li metal composite anode. |
