Surface engineering of commercial Ni foams for stable Li metal anodes

The short life span of lithium metal anodes (LMAs) due to dendrite growth and low coulombic efficiency (CE) has been regarded as the bottleneck in developing next-generation high-energy-density lithium metal based secondary batteries. Employing three-dimensional (3D) current collectors is one approach to reduce the effective current density and delay dendrite growth. Commercial Ni foam, in spite of its high electronic conductivity and 3D topology, has not been considered for this application due to its low specific surface area and lithiophobic nature. In this study, we develop a surface engineering strategy to uniformly coat lithiophilic AuLi₃ particles on Ni foam skeletons through lithiation of electrodeposited gold nanoparticles. In comparison with the bare Ni foam, the AuLi₃@Ni foam is more lithiophilic, significantly lowering the nucleation energy barrier and enhancing the uniformity for Li deposition. Such a structure results in effective suppression of Li dendrite growth in the void space of the foam. As a result, the AuLi₃@Ni foam current collector based LMAs can run for 740 h without cell failure in a symmetric cell. Furthermore, the Li-AuLi₃@Ni foam|LiFePO₄ full cell shows an excellent capacity retention of 43.8% with a high CE of 99.2% at 1C for 500 cycles. This work further illustrates the critical importance of surface lithiophilicity in guiding lithium cycling and suggests engineering the skeleton surface of commercial metal foam current collectors is important to improve 3D structured LMAs. © 2019 Elsevier B.V.