A new approach for recycling waste rubber products in Li-S batteries

Vulcanized rubber products contain polymer backbones crosslinked with sulfur to improve mechanical strength. Burning of waste rubber products emits toxic gases, and recycling of rubber by breaking the C-S bond with costly reagents and heat is also haunted by environmental concerns. The crosslinked polymers can be extracted chemically at room temperature and, by a simple solution-drop method, used to prepare a bifunctional cathode layer on the cathode current collector of a Li-S battery. The C-S bond of the crosslinking sulfur can be broken reversibly in a discharge/recharge cycle to provide a sulfur source, and the broken carbon bond can capture a lithium polysulfide soluble in a liquid organic electrolyte by forming a C-Li-S bond during discharge. During charge, the Li is extracted and the C-S bond is reformed. However, added sulfur powder is also needed in the cathode of a Li-S battery. The data also provide a low-cost way to recycle waste rubber electrochemically.