Rational Design of Highly Packed, Crack-Free Sulfur Electrodes by Scaffold-Supported Drying for Ultrahigh-Sulfur-Loaded Lithium-Sulfur Batteries.

Despite the notable progress in the development of rechargeable lithium-sulfur batteries over the last decade, achieving high performance with high-sulfur-loaded sulfur cathodes remains a key challenge on the path to the commercialization of practical lithium-sulfur batteries. This paper presents a novel method by which to fabricate a crack-free sulfur electrode with an ultrahigh sulfur loading (16 mg cm) and a high sulfur content (64%). By introducing a porous scaffold on the top of a cast of sulfur cathode slurry, the formation of cracks during the drying of the cast can be prevented due to the lower volume shrinkage of the skin. The scaffold-supported sulfur cathode delivers a notably high capacities of 10.3 mAh cm and 473 mAh cm after a prolonged cycle, demonstrating that the crack-free structure renders more uniform redox reactions at such high sulfur loading. The highly packed, crack-free feature of the sulfur cathode is advantageous, given that it reduces the electrolyte uptake to as low as an E/S ratio of 4 μL mg, which additionally contributes to the high energy density. Therefore, the scaffold-supported drying fabrication method as presented here provides an effective route by which to design practically viable, energy-dense lithium-sulfur batteries.