Two-dimensional molecular brush-functionalized porous bilayer composite separators toward ultrastable high-current density lithium metal anodes

Abstract

Lithium metal batteries have been considerably limited by the problems of uncontrolled dendritic lithium formation and the highly reactive nature of lithium with electrolytes. Herein, we have developed functional porous bilayer composite separators by simply blade-coating polyacrylamide-grafted graphene oxide molecular brushes onto commercial polypropylene separators. Our functional porous bilayer composite separators integrate the lithiophilic feature of hairy polyacrylamide chains and fast electrolyte diffusion pathways with the excellent mechanical strength of graphene oxide nanosheets and thus enable molecular-level homogeneous and fast lithium ionic flux on the surfaces of electrodes. As a result, dendrite-free uniform lithium deposition with a high Coulombic efficiency (98%) and ultralong-term reversible lithium plating/stripping (over 2600 h) at a high current density (2 mA cm−2) are achieved for lithium metal anodes. Remarkably, lithium metal anodes with an unprecedented stability of more than 1900 h cycling at an ultrahigh current density of 20 mA cm−2 are demonstrated.

Dendrite‐Free Lithium Plating Induced by In Situ Transferring Protection Layer from Separator

“…CE of Cu/Li cells is the most direct method to evaluate the effect of modification on the Li deposition behavior. Figure b compares the CE of Cu/Li cells with different treating methods from a wide variety of literature studies (Table S1, Supporting Information) 11a,b,13a,17,30,31. At the current densities of 0.5 and 1 mA cm −2 , the CE of the Cu/Li cells with PZT coating layer on PP surface can stabilize at 98–99%, which is superior to the results obtained by treating on the separator (refs.…”

“…Cu/Li cells were also assembled to further investigate the CE of Li deposition in the presence of PZT layer . The cells were cycled at various current densities of 0.5, 1.0, 2.0, and 5.0 mA cm −2 respectively.…”

Constructing a High‐Strength Solid Electrolyte Layer by In Vivo Alloying with Aluminum for an Ultrahigh‐Rate Lithium Metal Anode

“…One is designing a 3D current collector with a high specific surface area to reduce the local current density. The 3D collector includes electron‐conducting carbon materials that may or may not be lithiophilic (cellular graphene, Ag‐graphene, covalently connected graphite microtubes, carbon nanotubes, ZnO‐CNTs), ion‐conducting materials (AlF 3 ) and cation/anion regulation materials (polyethylene terephthalate nonwoven fabric, poly‐melamine‐formaldehyde, glass fiber, metal–organic framework, polyacrylamide‐grafted graphene oxide). In these cases, the current densities can be generally increased to 10–20 mA cm −2 .…”

Two‐Dimensional Material‐Functionalized Separators for High‐Energy‐Density Metal–Sulfur and Metal‐Based Batteries

“…The lithiophilicity of GO could be further enhanced by introducing additional polar agents. Wu and co‐workers coated polyacrylamide‐grafted graphene oxide onto PP separators . The composite separator enabled homogeneous and fast Li + flux on the surface of the electrode.…”