A novel dual-protection interface based on gallium-lithium alloy enables dendrite-free lithium metal anodes

Lithium (Li) metal has been considered as an ideal anode for high-energy density rechargeable batteries. However, it faces huge obstacles toward practical application due to the growth of Li dendrites and the uncontrollable side reactions with electrolyte. Here, we demonstrate a novel gallium-lithium alloy based dual-protection interface layer for Li metal by a facile in-situ ion-exchange reaction that possesses long service life for effectively alleviating the extra consumption of active Li as well as homogenizing the Li deposition. Such dual-protected feature is attributed to its outstanding stability, excellent Li affinity and favorable charge transfer kinetics. By means of in-situ visualization electrodeposition studies, the modified Li metal (GaLi-Li) anode can effectively suppress the Li dendrite even under a high deposition capacity of 7 mAh cm⁻². Moreover, the GaLi-Li based symmetric cell achieves excellent cycling stability for over 1500 cycles at a high current density of 5 mA cm⁻². Pairing the GaLi-Li anodes with LiFePO₄ and LiNi_0.8Co_0.1Mn_0.1O₂ cathodes, the cells also realize better long-term cycling stability with higher discharge capacity than that of the bare Li. Our strategy offers a practical way to realize highly stable and safety Li metal batteries.