Dendrite-free lithium anode enabled by lithium atom preferred orientation on Al[sbnd]Li alloy

Abstract

Li-rich composite alloys have received increasing attention as a method of inhibiting lithium dendrites. The Al-Li alloy has earned favor as a viable option to stabilize Li metal anodes due to its low cost, low flammability, natural abundance, and ease of operation. However, the mechanism responsible for the inhibition of lithium dendrites in the Al-Li alloy has yet to be thoroughly researched. Through Density Functional Theory (DFT) calculations, we analyzed the adsorption energies of Li atoms on various lattice planes of bare Li metal and Al-Li alloy. We discovered that Al-Li alloy provides higher absorption energies of Li atoms, ultimately leading to the preferred orientation of lithium atoms on Al-Li alloy. Experimental data confirmed our hypothesis, the symmetric cells with an Al-Li alloy demonstrated superior cycling properties over 140 hours, particularly at a current density of 5 mA cm−2, compared to the bare Li anode. Furthermore, full cells with an LiFePO4 (LFP) cathode exhibited better cycle and rate performance. This work provides a reasonable explanation for the inhibition of lithium dendrites on Al-Li alloy.