Graphene Foam Current Collector for High-Areal-Capacity\nLithium–Sulfur Batteries

Abstract

Extending lithium–sulfur battery\n(LSB) electrode architecture\ninto three dimensions (3D) has been proposed for more than a decade.\nA 3D lightweight and porous current collector that is capable of holding\nhigh amounts of sulfur (S) without any significant decrease in performance\nhas been elusive. Although many material solutions (such as sulfurized\npolyacrylonitrile or SPAN) have been identified for alleviating polysulfide\nformation and the so-called shuttle effect, their incorporation into\n3D current collectors with high capacity at the electrode level has\nnot yet been realized. Here, we show that graphene foams (GFs) are\nideally suited as 3D lightweight current collectors for LSBs and outperform\nthe conventional carbon-coated Al (Al/C) foils at the electrode level.\nSpecifically, we demonstrate that the open framework of GFs facilitates\nhigh mass loading of SPAN without any deterioration in capacity at\nthe active material level even at high S loading. At the electrode\nlevel, GF-SPAN cathodes exhibited capacities of ∼200 mAh g_electrode^–1 at 0.1C even with low S loadings (∼1.1 mg cm^–2), which is at least 3 times higher than conventional Al/C electrodes.\nMore importantly, we fabricated cells with a high mass loading of\n26.5 mg cm^–2 S by stacking multiple GFs to achieve\nan areal capacity as high as ∼20 mAh cm^–2 (at a current density of 3.0 mA cm^–2 up to 50\ncycles), which is at least 3 times higher than LSB areal capacity\n(6 mAh cm^–2) needed to displace LIBs.