Construction Of Lithiophilic And Antioxidative Copper Current Collectors For Lithium Metal Batteries

Lithium is considered as one of the most promising candidates for the next generation anodes due to its low reduction potential(-3.04 V)and high theoretical specific capacity(3860 mAh g-1).However,the application of lithium metal anodes is still limited by several issues resulted from the high reactivity,low surface energy and high diffusion barrier of lithium,such as the unstable solid electrolyte interface(SEI)layer,the large volumetric change,and the formation of lithium dendrites.Recently,the design of nanostructured copper current collectors is emerging as an effective strategy to protect lithium metal anodes by regulating Li deposition behaviors.Unfortunately,nanostructured copper current collectors have two major drawbacks:1)Copper is lithiophobic and possesses high nucleation overpotential.2)Nanostructured copper is easy to be oxidized.To solve these two problems,we developed a facile and effective method for constructing the lithiophilic and antioxidative copper current collector to improve the cycling stability of lithium metal anodes.The main research results were summarized as follow:(i)The surface of commercial copper foils was reconstructed by chemical modification.Compared with commercial copper foils,the surface of the modified copper foils is mainly composed of(110)crystal plane,which can improve the affinity of copper to lithium metal and reduce the nucleation overpotential of lithium.In addition,this strategy can be further expanded to the nanostructured copper current collectors,such as hierarchically structured copper foams and copper nanowires(Cu NWs).These copper current collectors have excellent storage stabilities.For instance,the modified Cu NWs can be stored in ethanol for more than 3 months,guaranteeing the preservation and transportation of Cu NWs current collectors.(ii)Lithiophilic and antioxidative Cu NWs(LA-Cu NWs)have been successfully used to construct porous current collectors for lithium metal batteries.Since lithiphilic LA-Cu NWs current collectors lowered local current density and enriched deposition sites,it can accommodate a large quantity of deposited lithium(e.g.,deposition areal capacity of 6 mAh cnm-2 without the presence of lithium dendrites at a high current density of 3 mA cm-2).The full cell assembled by the LA-Cu NWs/Li composite anode and high-LiFePO4 loading cathode(11 mg CIcm-2)delivered an ultra-long lifespan(>1000 cycles).Even with an areal LiFePO4 loading of 21 mg Cm-2,lithium metal batteries still exhibited good capacity retention after 300 cycles.(iii)A freestanding LA-Cu NWs paper was used as an interlayer for lithium metal batteries.Without the pre-electrodeposition of lithium,the LA-Cu NWs paper placed on the surface of lithium metal can effectively improve cycle performance of lithium metal batteries,opening up new opportunities for the practical application of copper current collectors.