Li-Alloy texture creates in-built Li(110) epitaxy in a thin Li-metal anode allowing high depth-of-discharge cycling in carbonate electrolyte

A thin Li metal anode is imperative for practical lithium metal batteries (LMBs). Fabricating and stabilizing <50 pm Li-metal anode is daunting due to the poor processability of Li and its inherent instability in liquid electrolytes. Here, we found that doping Li with 8.9 at% Sn yields a Li-Li22Sn5 dual-phase alloy with impressive processability that allows rolling of <40 pm thin foils. Intriguingly, in the thin Li-Sn foil, the rolling process built a strong Li22Sn5(822) texture that can regulate Li electro-crystallization along the densely packed Li(110) facets. Such in-built Li(110) epitaxy is a result of >99% lattice match of Li(110)-Li22Sn5(822) and gives rise to a greatly stabilized Li growth front due to the low binding energy of solvated-Li+ with Li(110) surface. Partial de-alloy treatment can fully activate the in-built Li(110) epitaxy, achieving stable plate-strip cycling in symmetric cells over 300 h at 80% depth-of-discharge (DOD). Stable 2.5 mAh/cm2 full pouch cells in carbonate electrolyte (EC: EMC: DEC = 1:1:1, 5 % FEC) were achieved at a low N:P ratio of 2.1. Conversely, conventional Li-Sn and neat Li, even possessing more abundant active Li, quickly failed. The uncovered critical crystallography-electrochemistry correlation in textured Li-alloys sheds light on thin Li-metal anode development.

Automated summary

Researchers found that doping Li with 8.9 at% Sn can create a Li-Li22Sn5 dual-phase alloy with impressive processability, allowing the fabrication of thin foils. The textured Li-alloy exhibits stable plate-strip cycling and improved performance.