Highly electrocatalytic active amorphous Al2O3 in porous carbon assembled on carbon cloth as an independent multifunctional interlayer for advanced lithium-sulfur batteries

To realize practical applications of lithium-sulfur batteries, rational strategies have to be applied to overcome obstacles such as the shuttle effect and sluggish reaction kinetics of soluble long-chain lithium polysulfides (LPS). In this work, highly electrocatalytic active amorphous Al2O3 uniformly dispersed in porous carbon (Al2O3/C) anchored on carbon cloth (CC) was successfully fabricated. The resultant flexible Al2O3/C@CC was used as an independent interlayer for Li-S batteries, demonstrating strong physical confinement and chemical binding ability for LPS, as well as high catalytic activity for LPS conversion kinetics due to a synergistic effect of 3D conductive network, amorphous nature of Al2O3/C, porous structure and abundant active sites. The cells with such interlayer exhibit high specific capacity, superior cycling stability and rate capability, 903 mAh/g at 0.2C after 100 cycles and 810 mAh/g at 1.0C after 300 cycles can be achieved, moreover, 741 mAh/g can still be retained at a high rate of up to 5.0C. By contrast, Al-MOF grown on carbon cloth (Al-MOF@CC) exhibits limited performance improvement due to poor electrical conductivity, low structure stability, as well as limited ion diffusion rate and weak Lewis acid-base interactions due to lack of open channels.