Rechargeable Li-S batteries have become attractive for next-generation energy storage technology due to their high specific energy, low cost, and materials earth abundance. However, the Li-S technology has not been successfully commercialized because of several outstanding challenges including fast capacity fading, low Coulombic efficiency, and limited rate capability. Over the past few years, considerable efforts have been devoted to solving the challenges associated with the sulfur cathode. In this mini review, we summarize our recent advances in Li-S cathodes, such as the understanding of the nano-size effect in sulfur materials, the design of polymer functional additives, and the realization of a novel in situ wrapping approach for Li-S cathodes. The current Li-S technology calls for a rational design of the Li-S cathode that can lead to excellent overall performance of Li-S batteries. Sulfur is a promising cathode material, which is highly earth abundant and with a theoretical specific capacity as high as 1672 mAh g −1 . When the sulfur cathode couples with a lithium metal anode to assemble rechargeable lithium-sulfur (Li-S) batteries, their theoretical specific energy density can reach 2600 Wh kg −1 , which is 3-5 folds higher than those of state-of-the-art Li-ion batteries.1-3 Because of the high energy density and low cost, rechargeable Li-S batteries are promising for applications not only in consumer electronics but also in energy storage and electric vehicles. [4][5][6] Although the research on Li-S batteries has been ongoing for over three decades, two major challenges still remain in this field: one is the low specific capacity due to high electrical resistivity of elementary S and the solid reduction products ((Li 2 S 2 and Li 2 S)) in the cathodes; the other is the fast capacity fading owing to the shuttle effect, i.e. polysulfide intermediates formed during discharge/charge cycles dissolve in the electrolyte, diffuse to the anode, react with Li metal, and form insoluble Li 2 S 2 and Li 2 S at the anodic region, leading to the loss of lithium metal and sulfur cathodic materials. 7,8 In the past few years, researches have mainly focused on designing nanostructured sulfur host materials to address challenges related to poor electrical conductivity of S/Li 2 S 2 /Li 2 S.9-19 A quantum leap for the nanostructure approach was the utilization of ordered mesoporous carbon CMK-3 to trap sulfur, as reported by Nazar et al. in 2009. 20 The conductive mesoporous carbon framework precisely constrains the growth of sulfur within its channels and thus enables fast electronic and ionic transport. Following this work, Cui et al. designed a series of sulfur nanostructures with complicated host materials demonstrating excellent electrochemical performances.9 Various nanostructured host materials, including but not limited to carbon/sulfur, 11,14,16,17,21 polymer/sulfur, [22][23][24] and metal oxide/sulfur composites 12,25,26 have been investigated. These nanostructures provide new merits and opportunities: (1)...