Cellulose-based separator woven by double-layer-configuration fibers for high S-load Li-S batteries

Abstract

Lithium-sulfur (Li-S) battery with high theoretical energy density, has been the most promising next-generation energy storage devices. However, the capacity of the high S-loaded cathode decays rapidly due to the shuttling of soluble polysulfide intermediates between the two electrodes, which seriously inhibits its development. In this work, polyacrylonitrile (PAN) and cellulose composite film (PAN@CE) is designed, which is woven by double-layer configuration fiber. The outer layer of fiber is mainly composed of cellulose, and the inner layer is mainly PAN. From DFT calculations and experiments, the double-layer configuration enriched with nitrogen and oxygen groups can effectively inhibit the shuttle of soluble polysulfides. Meanwhile, the interlaced network structure of PAN@CE improves the electrolyte wettability and provides abundance transport paths for ions. In addition, the film also has good thermal stability. Hence, the cycling stability of Li-S batteries with PAN@CE as separator has been greatly improved. Cellulose-based Li-S battery with 9.1 mg S loading and an E/S ratio of 6.2 μL mg−1 is assembled. Its initial area capacity is 5.67 mAh cm−2. After 200 long cycles, the area capacity keeps above 4.0 mAh cm−2.