Humidity-controlled in situ rapid formation of multi-gradient inorganic nanoparticle layer in ambient air stabilizes lithium metal anodes

The perfect anode material for secondary batteries, lithium metal suffers from natural limits in sensitivity to the humid environment and dendrite formation. Herein, a multi-gradient lithium inorganic compounds (LICs) composite nanoparticle layer was in-situ generated on the surface of lithium after the lithium sheet was placed in an air with a humidity of 55 % for 150 s. The rapid infiltration of the electrolyte can be facilitated by the porous Li₂CO₃ in the higher layer. The H₂O molecules that are adsorbed on the surface of lithium can be limited to the LiOH∙H₂O lattice by the early formed LiOH, which is influenced by hydrogen bonds. In addition to expediting the rapid desolvation of Li⁺ through dipole interactions, the LiOH∙H₂O yielded by this “molecular confined” effect also facilitates the rapid decomposition of lithium compounds on the anode side, particularly LiNO₃. lithiophilic sites are more abundant in the lower stratum of Li₂O. The assembled LICs@Li||Cu half-cells demonstrated exceptional performance in testing, retaining a Coulombic efficiency of ∼97 % after 350 cycles. Furthermore, full-cell configurations employing high-loading cathode materials (LICs@Li||LFP) exhibited stable cycling for over 400 cycles at a 2 C rate under 70 % humidity conditions in ambient air. A reference method for the design of chemically stable lithium anodes is provided by this rapid response lithium metal protection strategy.