Self-healing liquid metal layer as high-capacity and long cycle life anode for Al-ion batteries

Rechargeable Al-ion batteries (AIBs) with high capacity and Earth-abundant metal resources are gaining attention. However, the anode side of AIBs has been overlooked, with most using pure Al foil as the anode. In this study, a simple brush painting technique using eutectic Ga-In (EGaIn) liquid metal (LM) creates a high-performance AIBs anode. The EGaIn@Mo anode allows uniform and reversible plating/stripping of Al for over 10,000 h at 10 mAh cm−2 with 99.6 % average Coulombic efficiency. It enables half-cell operation at an ultrahigh areal capacity of 50 mAh cm−2 for over 1200 h. A full cell with EGaIn@Mo anode and graphite cathode maintains a reversible capacity of 82.8 mAh g−1 after approximately 6000 cycles at a high rate of 2 A g−2, exhibiting an ultralow capacity fading rate of 0.00064 % per cycle. Moreover, an anode-free cell lasts over 800 cycles with a specific capacity of 75.9 mAh g−1. This work demonstrates the potential of EGaIn LM coating for high-capacity AIBs and LM anode application.