Liquid Phase Exfoliated MoS₂ Nanosheets Percolated with Carbon Nanotubes for High Volumetric/Areal Capacity Sodium-Ion Batteries

The search for high-capacity, low-cost electrode materials for sodium-ion batteries is a significant challenge in energy research. Among the many potential candidates, layered compounds such as MoS2 have attracted increasing attention. However, such materials have not yet fulfilled their true potential. Here, we show that networks of liquid phase exfoliated MoS2 nanosheets, reinforced with 20 wt % single-wall carbon nanotubes (SWNTs), can be formed into sodium-ion battery electrodes with large gravimetric, volumetric, and areal capacity. The MoS2/SWNT composite films are highly porous, electrically conductive, and mechanically robust due to its percolating carbon nanotube network. When directly employed as the working electrode, they exhibit a specific capacity of >400 mAh/g and volumetric capacity of ∼650 mAh/cm(3). Their mechanical stability allows them to be processed into free-standing films with tunable thickness up to ∼100 μm, corresponding to an areal loading of 15 mg/cm(2). Their high electrical conductivity allows the high volumetric capacity to be retained, even at high thickness, resulting in state-of-the-art areal capacities of >4.0 mAh/cm(2). Such values are competitive with their lithium-ion counterparts.