Li-LiAl alloy composite with memory effect as high-performance lithium metal anode

摘要

Li metal is considered to be one of the most superior battery anode materials in high energy storage devices. However, Li dendrite generation and infinite dimensional change during long-term cycling limit its practical applications. To solve these problems, we design a thermal infusion strategy to prepare a Li-LiAl alloy composite based on the strong bonding force between Al and liquid Li. Compared with bare Li, Li-LiAl electrode exhibits a stable voltage profile and maintains an extremely low overpotential of 15 mV after 550 cycles at 1 mA cm(-2). When Li(4)Ti(5)O(12)or LiFePO4 are used as the counter electrodes to assemble full cells, the batteries show high capacities and stable cycling performance. Through scanning electron microscope image observation, it is found that Li-Al 3D skeleton could be formed when Li is stripped. During Li planting process, Li returns in the skeleton structure, and no Li dendrites formed on the surface of the electrode, indicating the memory effect of Li migration. It is possible that Li and Li-Al alloy have strong affinity and tend to re-deposit on the surface of Li-Al alloy. This kind of structure plays an important role in maintaining stability and improving the electrochemical performance of the Li-Al composite.