| Recently,the rapid changes in technology in all walks of life have increased the demand for energy.The development of new,high-efficiency,low-cost,and highenergy-density secondary battery systems is an important method to solve large-scale electric energy storage applications in the future.Due to the ideal theoretical specific capacity(3 860 mAh g-1),low density(0.534 g cm-3),and lower electrochemical potential(-3.04 V vs standard hydrogen electrode)of lithium metal,the research and development of high-energy-density energy storage systems has always occupied an extremely significant status,which is one of the important reasons why many researchers have always devoted themselves to the research of lithium metal batteries(LMBs).However,when lithium metal or lithium alloy is used as the anode,the disadvantages should not be ignored.For example,the lithium dendritic growth,lithium corrosion,dead lithium and volume expansion during the charge-discharge process.These problems can cause short circuits,rapid decay of battery capacity and even explosions,so the commercial use of lithium metal as an anode is greatly limited.To deal with above difficulties,this paper carries out several structural designs for the current collector of lithium anode,so as to promote the practical application in our life.The specific research is as follows:(1)Honeycomb copper metal micromesh(CMM)are prepared by micro-nano processing techniques such as photolithography and electrodeposition as the current collector substrate.The honeycomb mesh has the characteristics of ultra-thin,ultralight,ultra-flexible,and high conductivity,and the micron-level grid structure can control the electric field distribution.A layer of lithiophilic CuxO nanowires are modified on the surface of CMM(CMMC)by combining the wet chemical etching method and annealing treatment with the CMM as the substrate.By integrating the advantages of the honeycomb mesh and the nanowires three-dimensional structure,CMMC shows more excellent performance in electrochemical tests compared with pure copper foil and pure CMM.In the half-cell test,the CMMC electrode cycles stably for 2 000 cycles with a high Coulombic efficiency of 99%,and the CMMC-Li‖CMMC-Li symmetric cell operates with a stable low overpotential of 12 mV for 2 000 h.To demonstrate the practical application value of the CMMC-Li electrode,a CMMCLi‖LiFePO4 full cell exhibits a high capacity of 166.6 mAh g-1 at 0.2 C when it is matched with a highly loaded LiFePO4(8.56 mg cm-2)cathode.(2)A layer of copper nanoparticles(CMM@Cu)are attached to the surface of CMM by combining the wet chemical etching method and the hydrogen reduction method with the CMM as the substrate.The CMM@Cu thin film(CMC-ZL)decorated with lithiophilic lithium-zinc alloy rods are obtained by electroplating metal zinc and lithium in sequence by the continuous electrodeposition method.The CMC-ZL anode exhibits extraordinary electrochemical performance in LMBs due to its special honeycomb grid structure and low nucleation overpotential of Li-Zn alloy rods.In the symmetrical battery test,CMC-ZLIICMC-ZL always maintains a stable voltage profile and cycles stably for nearly 1 500 h with ultra-low overpotential.When matched with a highly loaded LiFePO4(10 mg cm-2)cathode,a high capacity of 140 mAh g-1 is demonstrated at 0.2 C. |
