Polyphenylene Tetrasulfide as an Inherently Flexible Cathode Material for Rechargeable Lithium Batteries

Li-ion batteries have transformed personal electronics from chunky devices to lightweight, flexible, and even wearable ones. Higher capacity and energy density, along with flexibility is offered by sulfur-based cathode materials. In this work, the condensation reaction of 1,4-benzenedithiol with elemental sulfur has been utilized to synthesize polyphenylene tetrasulfide (PPTS) possessing a theoretical specific capacity of 788 mAh g–1. This elastic material can accommodate a strain of up to 334%, while the carbon nanotube-based cathode can handle strains of 107%. This good flexibility also comes with favorable cycling performance in a lithium battery with a high capacity (633 mAh g–1 at 1 C), good rate performance, high Coulombic efficiency (∼99.4%), and a low capacity decay (under 0.07% per cycle). Therefore, PPTS and its analogues offer promising cathodes for flexible lithium batteries.