Manipulation of porosity and electrochemical artificial separator interphase for durable lithium-sulfur batteries

Abstract

The diffusion and shuttle of polysulfides leading to fast capacity decay and poor cyclability have severely hindered the practical application of lithium-sulfur batteries (LSBs). Here, we used a double-effect strategy to improve the cycle stability and specific capacity of LSBs. That is, the hole effect with the alteration of the pore size of the mesoporous carbon spheres (MCS) as the cathode host materials, and the confinement effect with the usage of the carbon cloth (CC) as an intermediate layer in the middle of cathode and separator to inhibit the polysulfides diffusion and shuttle phenomenon. As a result, appropriate pore size and inner space were obtained by controlling the content of ammonium hydroxide solution (NH3·H2O) catalyst to 1000 μL (denoted as MCS-4) in the synthesis of MCS. When MCS-4 is used as the sulfur host material, the obtained electrode material with a CC interlayer modification showed distinguished electrochemical performance in cells, including a high initial discharge capacity (1250 mAh g−1 at 0.1 C) and long cycle stability (510 mAh g−1 at 2 C after 500 cycles and 507 mAh g−1 at 0.5 C after 1000 cycles).