Vulcanized polyacrylonitrile is an alternative to carbon-sulfur cathodes where the carbon and sulfur are covalently bonded resulting in much improved stability. Although water-soluble binders are being used widely to stabilize carbon-sulfur cathodes, we observe here that oxygen-rich water-soluble binder can instead facilitate the high-rate performance of vulcanized polyacrylonitrile cathode. In this study, oxygen-rich water-soluble sodium carboxymethyl cellulose (NaCMC) is selected as binder for vulcanized polyacrylonitrile (PANS) cathode. Comparing with traditional oxygen-free PVDF binder, NaCMC shows a preference in fixing active materials and enabling better surface wettability. A high capacity of 938 mA h/g for sulfur is retained after 450 cycles at 0.9C (1C=1675 mA/g). In addition the capacity from NaCMC electrode at 4.5 C rate reaches 677 mA h/g, which is much higher than that obtained with PVDF binder (nearly zero at 4.5C). Our study here reveals the facilitated redox chemistry of PANS cathode by using oxygen-rich binders. The origin is believed relevant to the affinity of oxygen functional groups to lithium polysulfides in terms of chemical adsorption and interfacial charge transfer.
