Highly flexible, freestanding tandem sulfur cathodes for foldable Li–S batteries with a high areal capacity

Li–S batteries with a high theoretical capacity are considered as the most promising candidate to satisfy the increasing demand for batteries with a high areal capacity. However, the low sulfur loading (<2 mg cm⁻²) and poor flexibility of current Li–S batteries limit their application in establishing foldable Li–S batteries with a high areal capacity. To solve this problem, we employ here a free-standing flexible tandem sulfur cathode with a remarkably high sulfur loading to demonstrate foldable, high-areal-capacity Li–S batteries. The design of the tandem cathode readily increases the sulfur loading and effectively retards the migration of polysulfides. Therefore, the Li–S cell employing the tandem cathode exhibits a high initial areal capacity of 12.3 mA h cm⁻² with stable cycling stability even with a high sulfur loading of up to 16 mg cm⁻². These tandem cathodes are promising for foldable Li–S cells with a high areal capacity and energy density.