Gradient-Heterogeneous Lithium/Lithium–Magnesium Alloy for a Highly Stable Lithium Metal Anode

The lithium metal anode is considered a promising anode material due to its high specific capacity. However, the high reactivity and nonuniform deposition of Li metal pose significant challenges to the advancement of Li metal batteries. In this study, we introduce a straightforward and efficient approach to fabricate a heterogeneous Li/Li-Mg alloy anode with an Mg gradient distribution. Compared with homogeneous Li-Mg alloys, gradient-heterogeneous Li/Li-Mg alloys can offer a higher electrochemical activity surface area. Besides, the rich-Li alloy on the surface of alloy particles adeptly prevents the passivation effect, and the interior-rich Mg alloy guarantees the structural stability of the electrode. The symmetrical cell utilizing the gradient-heterogeneous Li/Li-Mg alloy exhibits stable cycling performance exceeding 7000 h. When paired with a SPAN cathode, the full cell retains 95% of its reversible capacity over 500 cycles. This study presents a straightforward and efficient approach to further the development of Li metal batteries.