Polyamidoamine dendrimer-based binders for high-loading lithium-sulfur battery cathodes

Lithium-sulfur (Li-S) batteries are regarded as one of the most promising candidates for next generation energy storage. To realize their practical application, however, a high S active material loading is essential. The binder material used for the cathode is therefore crucial as this is a key determinant of the bonding interactions between the active material (S) and electronic conducting support (C), as well as the maintenance of intimate contact between the electrode materials and current collector. Here, we investigated the application of polyamidoamine (PAMAM) dendrimers as functional binders in Li-S batteries. Utilizing the high degree of surface functionalities, interior porosities, and polarity of the PAMAM dendrimers, it is demonstrated that high S loadings (>4 mg cm(-2)) can be easily achieved using simple processing methods. An exceptional electrochemical cycling performance was obtained as compared to cathodes with conventional linear polymeric binders such as carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR), which was attributed to better interfacial interactions between the dendrimers and the C/S composite materials, as well as better electrolyte wetting due to the dendrimer spherical molecular, porous architectures. Furthermore, the dendrimer-based binders also physically and chemically trapped the polar polysulfides, thus demonstrating the significant utility of this new nanosized binder architecture. (C) 2015 Elsevier Ltd. All rights reserved.