Carbon-Based Interlayers

The unrivaled energy demands urge researchers to work beyond Li–ion battery technology such as Li–S, Zn–air, and Al–air batteries. The high theoretical capacity (1675 mAh/g), energy density (2600 Wh/kg), and abundance of sulfur make Li–S batteries more appealing in the field of electrochemical energy storage systems. However, the viable industrialization of the Li–S batteries is posed by the sluggish polysulfide conversion kinetics, insulating nature, volume expansion of the sulfur cathodes, and low cyclability. Therefore, the design of efficient sulfur host cathode materials, separators, novel electrolyte designs, and multifunctional interlayers are integral to the repression of the polysulfide shuttle effect as well as enhancing the conductivity of the sulfur in high-performance Li–S batteries. The progress of functional interlayers has opened up new pathways toward better-performing Li–S batteries. The interlayer, a free-standing membrane inserted between the cathode and the separator or a separator coating, plays a critical role in enhancing the cell's overall performance. An exemplary interlayer function as a retarding layer for polysulfide diffusion provides an efficient pathway for lithium ions, buffers the volume changes of the sulfur cathode, and acts as an upper current collector. Carbon nanomaterials like graphene, carbon nanotube, carbon nanofiber, and activated porous carbon with superior structural and functional features are widely preferred as potential interlayer candidates. This chapter outlines the recent progress in carbon-based interlayer configurations in Li–S batteries. The design and modifications of interlayer using carbon nanomaterials and their effects on the electrochemical performance of Li–S batteries are discussed in detail, which can facilitate the eventual realization of commercial Li–S batteries.