Graphene membrane hosted compact lithium metal anode enabled by capillary force-tuned lithium infiltration

Abstract

Lithium metal anodes, the promising anodes for next-generation batteries, are troubled by the instability and safety issues induced by the dendrite growth. Three-dimensional hosts are widely used to accommodate lithium metal to solve the above problems. However, they are constantly challenged by large thickness and excess space in the host, lowering the volumetric energy density of batteries. Here, we used the reduced graphene oxide membrane (rGOM) assembled with small graphene oxide sheets as the host and obtained a compact, ultrathin (<20 μm) and free-standing lithium metal-rGO composite anode with good flexibility and high volumetric capacity. The overlap sites derived from the stacking of small size of GO act as abundant diffusion channels for the gas release during the spark reduction process, producing narrow interlamellar space in the rGOM and thus enhancing the capillary molten Li infusion to form a compact composite anode. These sites also guide the uniform deposition of Li metal on the surface and interior of the membrane, effectively suppressing the dendrite growth. This compact composite anode delivers a high volumetric capacity (1223 mAh cm−3) and stable cycling performance in the symmetrical cells and the full cells coupled with high mass loading LiFePO4 cathode under a low N/P ratio.