Strong Capillarity, Chemisorption, and Electrocatalytic Capability of Crisscrossed Nanostraws Enabled Flexible, High-Rate, and Long-Cycling Lithium–Sulfur Batteries

Abstract

The development of flexible lithium–sulfur (Li–S) batteries with high energy density and long cycling life are very appealing for the emerging flexible, portable, and wearable electronics. However, the progress on flexible Li–S batteries was limited by the poor flexibility and serious performance decay of existing sulfur composite cathodes. Herein, we report a freestanding and highly flexible sulfur host that can simultaneously meet the flexibility, stability, and capacity requirements of flexible Li–S batteries. The host consists of a crisscrossed network of carbon nanotubes reinforced CoS nanostraws (CNTs/CoS-NSs). The CNTs/CoS-NSs with large inner space and high conductivity enable high loading and efficient utilization of sulfur. The strong capillarity effect and chemisorption of CNTs/CoS-NSs to sulfur species were verified, which can efficiently suppress the shuttle effect and promote the redox kinetics of polysulfides. The sulfur-encapsulated CNTs/CoS-NSs (S@CNTs/CoS-NSs) cathode in Li–S batteries exhibits superior performance, including high discharge capacity, rate capability (1045 mAh g–1 at 0.5 C and 573 mAh g–1 at 5.0 C), and cycling stability. Intriguingly, the soft-packed Li–S batteries based on S@CNTs/CoS-NSs cathode show good flexibility and stability upon bending.