Trash to Treasure: Transforming Waste Polystyrene Cups into Negative Electrode Materials for Sodium Ion Batteries

Modern society generates a huge amount of plastic wastes that are posing potential disasters to our environment and society. For example, waste polystyrene (PS), such as used PS cups and packing materials, is mainly disposed into landfills. It is very challenging to recycle PS economically. PS cannot be carbonized under conventional conditions, because PS is completely decomposed into toxic gases at moderate temperature instead of carbonization. Here, we demonstrated a facile procedure to transform waste PS cups collected from a local coffee shop into disordered carbon in a sealed reactor at moderate temperature but under high pressure. The as-obtained disordered carbon demonstrated interesting electrochemical characteristics for reversible storage of sodium ions. A highly reversible capacity of 116 mAh g–1 could be achieved for at least 80 cycles. Our preliminary results demonstrated that the trash of waste PS cups could be facilely transformed into treasure of promising negative electrode materials for sodium ion batteries, offering an alternative and sustainable approach to manage the waste PS issue.