A 3D conductive carbon interlayer with ultrahigh adsorption capability for lithium-sulfur batteries

Abstract

To improve the cycling performance of the Li-S batteries, a 3D interwoven hollow interlayer with extremely high electrolyte adsorption capability up to 9.64 g g−1 was simply prepared by carbonization of cotton fabric (CCF). For comparison, an interlayer coated on separator was obtained by the slurry-coating method of powdery CCF. The key role of the adsorption capability is confirmed by comparing the electrochemical performance of Li-S batteries with these two interlayers. In the Li-S batteries with 3D CCF interlayer, massive dissolved polysulfides, together with the electrolyte, can be adsorbed and confined in the 3D CCF interlayer, providing substantial extra active sites and alleviating the shuttle effect effectively. As a result, the Li-S batteries with 3D CCF interlayer show much enhanced utilization of active materials (1346.9 mAh g−1 at 0.1C), prolonged cycle life (capacity retention of 80% after 100 cycles), and improved rate performance (553.2 mAh g−1 at 4C). Even for cathodes with high sulfur loading of 5 mg cm−2, the cells with 3D CCF interlayer perform a high capacity of 1085 mAh g−1 and retain 870.6 mAh g−1 after 75 cycles at 0.5 mA cm−2. These results not only provide a sustainable, low cost and easy-prepared 3D CCF interlayer, but also offer a promising strategy based on interlayer with high adsorption capability in designing high-performance Li-S batteries.