Self-supporting composite anodes with three-dimensional network by wood-derived hard carbon in rechargeable metallic magnesium batteries

Rechargeable metallic magnesium batteries (RMBs) are expected to be a potential replacement for lithium counterparts. Yet, exotic electrolyte components forming passing layers on magnesium (Mg) surfaces usually leads to ultrahigh overpotential for reversible Mg chemistry. Here a novel self-supporting composite was constructed to address this issue by using chemically activated natural jujube wood-derived hard carbons (a-JHCs) with a three-dimensional (3D) network like skeleton as the artificial Mg-ions (Mg²⁺)-conducting interphase, achieving selective Mg²⁺ transport. Different from the traditional artificial solid-electrolyte interphase (SEI), the porous a-JHCs allows for 3D ion-conduction, thereby improving ion transport efficiency. Meanwhile, interfacial characteristics of a-JHCs have been demonstrated to suppress the intrusion of Mg deposits into micro-porous separators, allowing the Mg plating/stripping reaction beneath the interface. The artificial interface with low electronic conductivity significantly stabilizes the Mg electrode in conventional organic electrolytes. We show this proof-of-concept enables the reversible cycling of a Mg||V₂O₅ full-cell in the water-containing, and also opens the door to electrolytes previously considered as non-compatible with Mg.