Designing Lithiophilic Lithium Metal Surface by a Hybrid Covalent Organic Framework and MXene Coating

Abstract With the increasing demand for developing large‐energy‐density and safe batteries, a reliable lithium metal as an anode becomes more and more important in various lithium metal and solid‐state batteries. On the basis of better lithium regulation from MXene, a lithiophilic lithium metal surface is designed by introducing a 2D hybrid coating that consists of a thin covalent organic framework (COF‐1) modified MXene layer (denoted as COF‐MXene‐Li). The abundant lithiophilic boroxine sites on 2D COF‐1 attract lithium ions while the MXene further regulates lithium homogeneous nucleation and growth, thus preventing dendrite formation. The coin cell battery paired with LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) as cathode material displays 17% more capacity retention compared with pure lithium metal after 400 cycles at 0.5C.Over 81.4% capacity retention along with 99.96% Coulombic efficiency (CE) of a 1.0 Ah pouch cell versus LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA) after 250 cycles is received. The assembled 1.6 Ah pouch cell with NMC811 show an energy density of up to 366.7 Wh Kg −1 and an actual energy density based on the whole cell of up to 339.7 Wh Kg −1 . The improved cycling stability particularly in pouch cells opens broad applications for this hybrid coating modified lithium metal as anode electrode in a variety of large‐energy‐density battery systems.