Magnesium Anchoring Strategy for Stabilizing Graphene‐Hosted Lithium Metal Battery

Abstract

Lithium metal‐graphene host composite is a promising anode material for high‐energy‐density Li battery owing to its three‐dimensional structure, micro‐level controllable thickness and ultrahigh specific capacity. However, we discover that the hydroxyl/carboxyl functional groups in the reduced graphene oxide (rGO) host are likely to be reduced into lithium carbonate composition in the solid‐electrolyte interphase (SEI), which resulted in severe lithium dendrite growth that deteriorate its electrochemical performances. Here, we develop a magnesium anchoring strategy that selectively bond the Mg ion with the hydroxyl/carboxyl groups in rGO host, generating an electrolyte‐derived lithium fluoride‐dominant SEI instead of oxygen groups‐derived, lithium carbonate‐dominant SEI. By anchoring 0.60% of Mg in the rGO host using a facile compositing‐pyrolysis approach, Li dendrite growth in anode can be significantly suppressed, and the cycling stability of Li metal full cells can be prolonged by 200%. These findings give new insight into the mechanism of SEI formation in Li metal anode, and provide a new design strategy for restraining the reduced reaction of hydroxyl/carboxyl groups in graphene to stabilize the composite anode of lithium metal battery.