With the popularization and application of portable electronic equipment and electric vehicles, the electrochemical energy storage devices are facing new challenges. The application of conventional lithium-ion batteries are limited by lower theoretical capacity of electrode materials. It cannot meet the requirements of high energy density energy storage system. 

Lithium-sulfur (Li-S) batteries are regarded as one of the most attractive candidates for the next generation electrochemical energy storage devices. They centralize the advantages of high theoretical capacity, environmental sustainability, abundant sulfur resource and low-cost. Nevertheless, the commercialization of Li-S batteries is currently hampered by a multitude of intractable issues. 

The Advanced Energy Storage Materials and Technology Group from the Qingdao Institute of Bioenergy and Bioprocess Technology (QIBEBT), Chinese Academy of Sciences (CAS), developed a new reinforced-concrete-structure flexible sulfur-carrier, with green wood fiber and carbon nanotubes as sulfur host, and graphene as current collector. It greatly boosted the electrochemical performance of Li-S batteries. 

Using this electrode, the Li-S batteries exhibited an unprecedented discharge capacity as high as 1632 mAh g^-1 at 0.1C and enhanced capacity of 987 mAh g^-1 after 500 cycles at 1.0 C.

Furthermore, even up to the sulfur loading of 9.2 mg cm^-2, this electrode still maintained a highly reversible capacity of 668.8 mAh g^-1 at 0.5 C after 100 cycles, corresponding to 91.5% capacity retention. This lightweight and flexible electrode appears to be a scalable solution for high energy density of Li-S batteries. 

The study was published in Journal of Materials Chemistry A. And it was supported by the National Natural Science Foundation of China, the "Hundred Talents Program" of the Chinese Academy of Sciences, and DICP&QIBEBT. 

Structures and related schematic diagram of flexible sulfur-carrier. (Imaged by LIU Tao)