Synergistic surface and bulk engineering with Li-rich dual-phase Li-Al alloy anode for rational regulation of lithium deposition

Abstract

Lithium (Li) metal has been regarded as one of the most promising anodes for the next-generation high-energy-density batteries. However, the large volumetric variation and uncontrollable Li dendrite growth have delayed the large-scale application. For the sake of ultrahigh theoretical capacity, low alloying potential, and small dimensional expansion, Li-Al alloy has come into sight as an appealing candidate for Li anode. Herein, as-prepared Li-rich dual-phase Li-Al alloys with abundant Li and Li9Al4 three-dimensional (3D) framework are fabricated via a one-step melting approach. Different from typical facial modification of Li anode, our Li-Al alloy can improve the electrochemical behavior of anode, fundamentally from surface and matrix prospect. Owing to the favorable lithiophilicity, increased specific surface, and regulated Li ion (Li+) flux, Li-Al symmetric cell presents excellent cyclic reversibility and stability (more than 1400 h, and smaller voltage hysteresis of 76 mV at 300th cycle), at the current density of 1 mA cm2 and areal capacity of 1 mAh cm2. Furthermore, Li-Al alloy anode is paired with LiFePO4 cathode to assemble full battery, which enables 250 cycles at 1.0 C with a high-capacity retention rate of 94.7 %. This contribution offers new insights into the feasible preparation of Li-Al alloy composite and in-depth understanding of working mechanism toward dendrite-free and minimum-volume-change Li anode.