Mg-Al layered double hydroxides modified N-doped porous carbon nanofibers film as cathodic interlayer for high performance Li-S batteries

Lithium-sulfur (Li-S) battery as a promising energy storage technology has attracted extensive concern. However, their practical performance is seriously limited by the dissolution and diffusion of long-chain polysulfides. In this study, a multifunctional cathodic interlayer was constructed, which composed by Mg-Al layered double hydroxides (MALDHs) modified N-doped honeycomb-like porous carbon nanofibers (NPCNFs). The NPCNFs in the prepared interlayer can combine the physical confinement of the porous structure and the chemical role of the nitrogen atoms to suppress the dissolved lithium polysulfide (LiPS). Furthermore, highly conductive interlayer contains NPCNFs can be regarded as a second current collector, and the hierarchical pores is beneficial to adapt the volume change during the redox process. More importantly, the obtained polar MALDHs not only can strongly interact with LiPS by chemical combination, but also enhance the redox kinetics by forming cooperative interface. As a result, the Li-S cells with the cathodic interlayers obtains a high initial discharge capacity of 1452 mAh g(-1) at 0.2 C, superior rate capability up to 2 C rate with a capacity of 952 mAh g(-1) and excellent long-term cycling stability by maintaining a low average capacity fading (0.065% per cycle) during 500 cycles at 1 C. Therefore, the interlayer contains MALDH@NPCNFs has extraordinary potential to be used in high-performance Li-S batteries. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

A multifunctional cathodic interlayer composed of Mg-Al layered double hydroxides modified N-doped honeycomb-like porous carbon nanofibers was constructed to suppress dissolved lithium polysulfides and enhance redox kinetics. The interlayer with NPCNFs acts as a second current collector, adapts to volume changes during redox processes, and shows great potential for use in high-performance Li-S batteries, demonstrating high initial discharge capacity, superior rate capability, and excellent long-term cycling stability.