Spatially uniform deposition of lithium metal in 3D Janus hosts

Three-dimensional (3D), high-specific-surface-area, and porous current collectors are strongly considered as the hosts of lithium deposition to avoid dendrite growth of lithium metal in rechargeable batteries. However, a major hurdle in these hosts is the poor affinity of lithium in non-polar framework and favorable lithium deposition toward the conductive separator-facing surface while leaving the interior voids empty. Herein, we demonstrate an effective strategy to address the issue of spatially heterogeneous lithium deposition in 3D Janus current collectors by modifying its separator-away surface with low Li/Li+ over-potential nanoparticles as nucleation sites to guide lithium deposition. The metallic lithium preferentially nucleates around the gold nanoparticles that are sputtered on the separator-away surface of the carbon paper. The lithium metal then grows along the adjacent carbon fiber and renders it spatially homogeneous for deposition/dissolution during the repeated charge/discharge processes. The Janus gold nanoparticle-modified carbon paper (Au/CP) electrode exhibits an excellent Coulombic efficiency of 99.1% over 100 cycles at 1.0 mA cm⁻2 in the ether electrolyte, while the pristine carbon paper (CP) and stainless steel foil (SS) electrodes exhibit Coulombic efficiencies of less than 80.0% after 74 and 59 cycles, respectively. The strategy is universal and similar results are obtained when replacing gold, carbon paper, and ether electrolyte with zinc oxide, nickel foam, and carbonate electrolyte, respectively. Therefore, this strategy presents a general approach to regulate lithium ion distribution, nucleation, and deposition behavior for long-lifespan lithium metal batteries.