Polyphenylene\nTetrasulfide as an Inherently Flexible Cathode Material for Rechargeable\nLithium Batteries

Abstract

Li-ion\nbatteries have transformed personal electronics from chunky devices\nto lightweight, flexible, and even wearable ones. Higher capacity\nand energy density, along with flexibility is offered by sulfur-based\ncathode materials. In this work, the condensation reaction of 1,4-benzenedithiol\nwith elemental sulfur has been utilized to synthesize polyphenylene\ntetrasulfide (PPTS) possessing a theoretical specific capacity of\n788 mAh g^–1. This elastic material can accommodate\na strain of up to 334%, while the carbon nanotube-based cathode can\nhandle strains of 107%. This good flexibility also comes with favorable\ncycling performance in a lithium battery with a high capacity (633\nmAh g^–1 at 1 C), good rate performance, high Coulombic\nefficiency (∼99.4%), and a low capacity decay (under 0.07%\nper cycle). Therefore, PPTS and its analogues offer promising cathodes\nfor flexible lithium batteries.