Lithophilic alloy and 3D grid structure synergistically reinforce dendrite-free Li–Sn/Cu anode for ultra-long cycle life lithium metal battery

Abstract

Lithium (Li) metal is considered the most promising anode material for the next generation of secondary batteries due to its high theoretical specific capacity and low potential. However, the application of Li anode in rechargeable Li metal batteries (LMBs) is hindered due to the short cycle life caused by uncontrolled dendrite growth. In this work, a dendrite-free anode (Li–Sn/Cu) is reinforced synergistically by lithophilic alloy, and a 3D grid structure is designed. Li⁺ diffusion and uniform nucleation are effectively induced by the lithophilic alloy Li₂₂Sn₅. Moreover, homogeneous deposition of Li⁺ is caused by the reversible gridded Li plating/stripping effect of Cu mesh. Furthermore, the local space electric field is redistributed throughout the 3D conductive network, whereby the tip effect is suppressed, thus inhibiting the growth of Li dendrites. Also, the volume expansion of the anode during cycling is eased by the 3D grid structure. The results show that the Li–Sn/Cu symmetric battery can stably cycle for more than 10,000 h at 2 mA·cm⁻² and 1 mAh·cm⁻² with a low overpotential. The capacity retention of the LiFePO₄ full battery remains above 90.7% after 1,000 cycles at 1C. This work provides a facile, low-cost, and effective strategy for obtaining Li metal batteries with ultra-long cycle life.

Graphical abstract