Li‐Ion storage and diffusivity in sulfurized polybutadiene containing covalently bound sulfur as a polysulfide shuttle‐free cathode material for Li-S batteries

Abstract

In this work, a new polymer has been explored as a cathode host for lithium‐sulfur batteries (LSBs). Sulfurized polybutadiene materials were synthesized by a single‐step, scalable, and easily tailored heat treatment method. The optimized synthesis process allows for high sulfur loadings of up to 50 wt %. Thermogravimetric analysis‐mass spectrometry (TGA‐MS) and X‐ray photoelectron spectroscopy (XPS) studies confirm that the sulfur is covalently bound to the polymeric backbone, which overcomes the otherwise common capacity‐fading polysulfide shuttle effect of lithium‐sulfur (LSBs) batteries. The absence of free elemental sulfur in the synthesized active materials allows for a stable capacity of up to 1200 mAh g -1 at a rate of C/20. The porous polymer networks reduce the pulverization of the cathode during cycling, resulting in long‐term cycling stability of 1500 continuous galvanostatic charge/discharge (GCD) cycles. Capacity contribution studies depict that at a scan rate of 1 mV s -1 , the sulfurized polybutadiene cathode‐based cells have 65 % capacitive and 35 % diffusive contribution of the total charge stored. A comprehensive study on Li‐ion storage with capacity contribution and diffusion studies of polysulfide shuttle‐free sulfurized polybutadiene cathode material for LSBs is presented.