Magnesium Anchoring Strategy for Stabilizing Graphene-Hosted Lithium Metal Battery

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. A magnesium anchoring strategy is discovered to selectively bond the Mg ion with oxygen functional groups in graphene for preventing the formation of oxygen functional groups-derived lithium carbonate in solid-electrolyte interphase (SEI), thus building an electrolyte-derived LiF-dominated SEI for achieving uniform lithium deposition and stable cycling in Li metal battery.image (c) 2023 WILEY-VCH GmbH