Sodium alginate reinforced 3D lithiophilic Ag-Cu framework for ultrastable Li deposition

The implementation of lithium (Li) anode has been greatly hindered by the low columbic efficiency (CE) and safety concerns, and these are also the main issues in anode-free batteries. Using three-dimensional (3D) anode, such as copper foam (CF), can lower the areal current density and reduce the overpotential, but the larger interface will induce more SEI issues, and additionally, its lithiophobic and naturally curving surface leads to difficult Li nucleation and even more uneven Li deposition. In this paper, sandwich-structured SA@Ag@CF electrode is fabricated in which CF substrate is uniformly covered by nano-sized Ag particle and an extra sodium alginate (SA) layer is further loaded on it. Synergistic effect has been brought by thus-designed electrode, in which Ag much increases the Li-affinity, on the other hand, the tightly-absorbed SA reduces electrolyte contact, alleviates the volume variation and regulates the Li+ diffusion. Ultra-stable Li deposition on 3D substrate has been first realized by the SA@Ag@CF electrode in corrosive carbonate electrolyte. With the SA@Ag@CF anode, the full cells demonstrate much improved long-term stability and rate performance.