Lithiophilic Mo₃N₂/MoN as multifunctional interlayer for dendrite-free and ultra-stable lithium metal batteries

The formation of lithium dendrite and the unstable electrode/electrolyte interface, especially at high rates, are the dominant obstacles impeding the implementation of lithium metal batteries (LMBs). To tackle these fundamental challenges, here we propose a lithiophilic Mo₃N₂/MoN heterostructure (designated as MoN_x) interlayer for dendrite-free and ultra-stable lithium metal anodes for the first time. The MoN_x interlayer presents excellent electrolyte wettability, fast lithium diffusion kinetics and strong mechanical strength, which function synergistically to inhibit lithium dendrite growth. During cycling, an in-situ formation of Li₃N-rich solid electrolyte interphase layer and metallic Mo phase can regulate the Li-ion conductivity and Li metal deposition, thus indicating uniform and compact Li plating. Above ameliorating features accompany an ultra-long-life of 2000 h at a high current density of 5 mA cm^-2 for the MoN_x-Li anode. The feasibility of the MoN_x-Li anode in LMB is further confirmed in conjunction with LiFePO₄ cathodes. The full cells deliver exceptionally high-capacity retentions of above 82.0% after 500 cycles at 1C and 425 cycles at 3C, which are among the best thus far reported for LMBs. This work provides both new insights towards functional interlayer design and effective transition-metal nitrides for practical LMBs.