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The propensity of Li to form irregular and nonplanar electrodeposits has become a fundamental barrier for fabricating Li metal batteries. Here, a planar, dendrite‐free Li metal growth on 2D Ti3C2Tx MXene is reported. Ab initio calculations suggest that Li forms a hexagonal close‐packed (hcp) layer on the surface of Ti3C2Tx via ionic bonding and the lattice confinement. The ionic bonding weakens gradually after a few monolayers, resulting in a nanometers‐thin transition region of hcp‐Li. Above this transition region, the deposition is dominated by plating of body‐centered cubic (bcc) Li via metallic bonding. Formation of a dense and planar Li metal anode with preferential growth along the (110) facet is explained by the lattice matching between Ti3C2Tx and hcp‐Li and then with bcc‐Li, as well as preferred thermodynamic factors including the large dendrite formation energy and small migration barrier for Li. The prepared Li metal anode shows stable cycling in a wide current density range from 0.5 to 10.0 mA cm–2. The LiFePO4‖Li full cell fabricated with this Li metal anode exhibits only 9.5% capacity fading after 500 charge–discharge cycles at 1 C rate.

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