High performance ultra-thin lithium metal anode enabled by vacuum thermal evaporation

Abstract

The passivation layer that naturally forms on the lithium metal surface contributes to dendrite formation in lithium metal batteries by affecting lithium nucleation uniformity during charging. Herein, we propose using vacuum thermal evaporation to produce a high-performance ultra-thin lithium metal anode (≤25 µm) with a native layer much thinner than that of extruded lithium. The evaporated lithium metal shows significantly reduced charge-transfer resistance, resulting in uniform and dense lithium plating in both carbonate and ether electrolytes. This study reveals that the evaporated lithium metal outperforms the extruded version in ether electrolyte and with LiFePO4 cathodes, showing a 30% increase in cycle life. Additionally, when paired with LiNi0.6Mn0.2Co0.2O2 cathodes in carbonate electrolyte, the evaporated anode’s cycle life is tripled compared to the extruded lithium metal. This demonstrates that vacuum thermal evaporation is a viable method for producing ultra-thin lithium metal anodes that prevent dendrite growth due to their excellent surface condition. The passivation layer that forms on the surface of lithium metal contributes to lithium nucleation uniformity during battery charging. Here, vacuum thermal evaporation produces an ultra-thin lithium metal anode with reduced charge-transfer resistance that results in a more homogeneous and denser lithium plating.