Cu-containing Li-rich Alloys As Li-metal Anode Materials

Today’s energy landscape is undergoing major changes,with increasing demand for low-carbon renewable energy.The traditional lithium-ion battery with graphite anode is restricted by theoretical capacity and cannot meet human needs more and more.There is an urgent need to develop batteries with high energy density.Lithium metal batteries have attracted people’s attention with their extremely high theoretical capacity of 3860 m Ah g^-1.Lithium metal anodes are considered as promising anode materials in the future.However,the safety problems caused by dendrites and the volume change during the cycling have always hindered the commercialization of lithium metal anodes.Therefore,finding an effective protection strategy to inhibit the growth of dendrites has become a top priority.The protection strategy based on the traditional dealloying method to construct the 3D structure anode can inhibit the growth of dendrites to a certain extent,but the preparation process is complicated and it is not suitable for large-scale production.In this paper,the method of heating and melting is used to prepare the lithium alloy foil to form a porous framework after in-situ delithiation.The alloy foil is directly used as a self-supporting material,eliminating current collectors.The main research contents are as follows:Firstly,we found in our experiments that heating Cu and Li foils at the same time would dissolve both.Li-Cu alloys prepared after cooling are flexible and self-supporting and can be directly used as anode materials.Compared with pure lithium anodes,Li-Cu alloy anodes have shown good performance in half-cells and full-cells.SEM was used to explore the morphology of Li-Cu alloy anode after cycling.During the cycling process,the Li-Cu alloy exists a 3D framework,which reduces the local current density and induces uniform deposition of lithium ions.However,in the deep delithiation process,it was found that the 3D framework collapsed and pulverized,and then the cell failed.In the following research,we made further modifications to the Li-Cu anode.Secondly,Li-Cu-Ag ternary alloy anodes with different silver concentration gradients were designed and prepared by melting and rolling process.The bottom of the electrode is rich in lithophilic sites,which guide the bottom-up lithium deposition,improve the lithophilicity and stability of the electrode,and extend the cycling life of the electrode.In-situ optical microscopy,EIS and SEM characterization proved that Li-Cu-Ag ternary alloy anode has good ion transport and the ability to inhibit dendrite growth.At a current density of 0.5 m A cm^-2,the Li_92.5Cu₅Ag_2.5 symmetric cell has good cycling stability within 1200 h.The Li_92.5Cu₅Ag_2.5 anode paired with Li Fe PO₄ cathode,charged and discharged 1000 cycles at 2 C.The capacity retention rate is about 94%.