Homogeneous Li+ flux realized by an in situ-formed Li–B alloy layer enabling the dendrite-free lithium metal anode

Abstract

Severe Li dendrite growth, “dead” Li accumulation, and infinite volume changes during repeated cycling significantly hinder the practical applications of lithium metal anodes (LMAs). To solve the above-mentioned concerns, a lithiophilic Li–B alloy layer is constructed to modify the lithiophobic Ni foam (NF) to lithiophilic via an in situ alloying reaction of Ni₃B (Ni₃B/B@NF). The in situ formation of Li–B alloy can not only provide enriched nucleation sites for inducing Li metal conformal growth along the lithiophilic alloying layer with reduced nucleation overpotential but also homogenize Li⁺ flux for lowering concentration polarization near the electrode, thus inhibiting the Li dendrite growth achieving dendrite-free Li deposition morphology. In addition, the 3D porous NF with a high specific surface area can largely reduce the local current density and synergistically impede the growth of dendritic Li. Moreover, NF offers enough space for accommodating deposited metal Li, relieving volume fluctuation during the Li plating/stripping process. As a consequence, the symmetric battery with the Ni₃B/B@NF electrode presents a low overpotential of 11 mV and stably cycles for 820 h at a current density of 1 mA cm⁻² with a fixed capacity of 2 mA h cm⁻². In addition, the assembled full cell exhibits improved cycling stability and rate performance, confirming the application perspective of Ni₃B/B@NF in stabilizing LMAs.