Low-temperature fusion fabrication of Li-Cu alloy anode with in situ formed 3D framework of inert LiCu_x nanowires for excellent Li storage performance

具有自组装三维纳米线结构的锂铜合金作为高性能复合金属锂电极

The commercialization of rechargeable Li metal batteries is hindered by dendrite growth and volumetric variation. Herein, we report a Li-rich dual-phase Li-Cu alloy with built-in 3 D conductive skeleton to replace conventional planar Li anode. The Li-Cu alloy is simply prepared by fusion of Li and Cu metals at a relatively low-temperature of 500 °C, followed by a cooling process where phase-segregation leads to metallic Li phase distributed in the network of LiCu_x solid solution phase. Different from the common Li alloy, the electrochemical alloying reaction between Li and Cu metals is not observed. Therefore, the lithiophilic LiCu_x nanowires guides conformal plating of Li and the porous framework provides superior dimensional stability for the anode. This unique ferroconcrete-like structure of Li-Cu alloy enables dendrite-free Li plating for an expanded cycling lifetime. Constructing a new type of Li alloy with in situ formed electrochemically inactive framework is a promising and easily scaled-up strategy toward practical application of Li metal anodes.

金属锂负极的枝晶生长和体积变化等问题阻碍了金属锂二次电池的商业化应用.该论文报道了一种具有自组装导电骨架结构的富锂双相锂铜合金作为复合金属锂电极.金属锂和金属铜在500°C下形成熔融合金,在冷却过程中发生相分离,锂铜固溶体自组装形成纳米线网络结构,金属锂单质填充在骨架结构间隙,形成双相合金,一步合成复合金属锂电极.该方法简化了复合金属锂电极的制备过程,并且可以通过改变锂铜合金的比例调控骨架的形貌.锂铜固溶体骨架呈现电化学惰性并具有一定的亲锂性,能够增强金属锂电极的机械强度、维持电极结构稳定、为锂沉积提供空间、诱导锂均匀沉积、抑制锂枝晶生长.富锂双相锂铜合金作为复合金属锂电极能够有效提高电池的库伦效率、延长电池循环寿命.构建新型富锂合金的方法有利于大规模生产复合金属锂电极和金属锂负极的实际应用.