文摘
A highly conductive sulfur cathode is crucial for improving the kinetic performance of a Li–S battery. The encapsulation of sulfur in porous nanocarbons is expected to benefit the Li+ migration, yet the e– conduction is still to be improved due to a low graphitization degree of a conventional carbon substrate, especially that pyrolyzed from carbohydrates or polymers. Aiming at facilitating the e– conduction in the cathode, here we propose to use ketjen black, a highly graphitized nanocarbon building block to form a conductive network for electrons in a biomass-derived, hierarchically porous carbon sponge by a easily scaled-up approach at a low cost. The specifically designed carbon host ensures a high loading and good retention of active sulfur, while also provides a faster electron transmission to benefit the lithiation/delithiation kinetics of sulfur. The sulfur cathode prepared from the carbon network shows excellent cycling and rate performance in a Li–S battery, rendering its practicality for emerging energy storage opportunities such as grids or automobiles.