A team led by Prof. Yan Lu, HZB, and Prof. Arne Thomas, Technical University of Berlin, has developed a material that enhances the capacity and stability of lithium-sulphur batteries. The material is based on polymers that form a framework with open pores (known as radical-cationic covalent organic frameworks or COFs). The service life of Li-S batteries thus increases to over 1,500 cycles with a capacity loss of only 0.027% per cycle. This durability of Li-S batteries has not yet been achieved with COF materials or other purely organic catalysts. Typically, Li–S batteries exhibit less than 1,000 cycles, according to reports from the past few years.