Effect of Carbon Additives on the Rate Performance of Redox Polymer Materials for Lithium Metal Batteries

Materials with fast charging and discharging capability are highly desirable for the development of high-power batteries. In this study, we present a composite consisting of a poly(anthraquinonyl sulfide) and reduced graphene oxide (PAQS@rGO). The composite is synthesized by an in situ method and aims to be used as a high-power electrode material for lithium metal batteries. Other carbon additives including Ketjen black and activated carbon are also investigated as a comparison. The results suggest that the high electronic conductivity of the rGO and its unique morphology serving as anchor sites render it the optimal additive for the polymer. Highly reversible capacity and stable cyclability are obtained with the PAQS@rGO sample. The advantages of the in situ synthesis method over the simple mixing method for the preparation of the polymer composite are also explored. A better contact between the polymer and the carbon additives and thus lower polarization (IR) is achieved with the in situ synthesis method. Although the rGO additive improves the electronic conductivity of the composite, a proper amount of conductive carbon additives is still necessary for the full utilization of the composite. Since the PAQS@rGO composites possess a porous honeycomb morphology, small particles of carbon black are able to penetrate into the pores and thus build a better electron transfer network than the crumpled rGO sheet. This in situ synthesis with rGO as carbon additives is proven to be a universal method for the preparation of similar polymers.