The electronic nonconductivity of S and shuttle effect of soluble polysulfides are two fundamental issues that limit the application of lithium-sulfur (Li-S) batteries. Regarding these issues, herein, a sponge-like Ketjen black (KB)-triphenylphosphine sulfide (TPS) multifunctional modification layer was proposed to coat the separator of the advanced Li-S batteries. The layer was formed by an in situ spontaneous reaction between triphenylphosphine (TPP) of the conventional KB-TPP layer and Li2S6 solution. This functional layer can ensure a high e(-) and Li+ conductivity while inhibiting the diffusion of soluble polysulfides. As a result, the redox activity, rate capability, and cycling stability of the batteries are significantly enhanced. Comparing with the discharge capacities at 2C for the PE separator, introducing the KB-TPS functional layer was beneficial for the capacity retentions of the cells, since the capacity increased from 16.1% to 66.6% at the same C-rate. A capacity degeneration rate of 0.045% per cycle was obtained for the cell with an S area density of 3.6 mg cm(-2). This work is a step forward in the exploration of advanced Li-S batteries, being a valuable reference for the study of related systems.