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 past 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 ultrahigh sulfur loading (16 mg cm-2) 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 notably high capacity of 10.3 mAh cm-2 and 473 mAh cm-3 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-1, 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.