A lithium-MXene composite anode with high specific capacity and low interfacial resistance for solid-state batteries

MXenes, a family of two-dimensional (2D) transition metal carbides, nitrides and carbonitrides, offer great potential for the rational design of many new composites due to their attractive properties and surface terminations. In this study, we present a new lithium-MXene composite (Li-MXene) anode design that substantially reduces interfacial Li ion transport resistance between Li metal anode and garnet solid-state electrolyte. When evaluated as electrodes in Li-MXene|garnet|Li-MXene symmetric cells, the interfacial resistance is negligible (5 Ω•cm2). By contrast, the pure Li-based counterpart shows poor contact with garnet, and thus induces a much larger interfacial resistance of 1291 Ω•cm2. Simultaneously, thanks to the existence of fluorinated functionalized surfaces on MXene, LiF was in-situ formed at the Li-MXene/garnet interface, which effectively isolated electron transport and suppressed the formation of dendritic Li. A high critical current density of up to 1.5 mA/cm2 has been enabled. These findings suggest the possibility of tuning the properties of Li metal anode by altering additives with different functional groups and also motivate future work employing MXene as additives towards new composites.