Fibrous Porous Composite Interlayer Derived from Soft Dendritic Colloids for Lithium-Sulfur Batteries

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Lithium-sulfur (Li-S) batteries have emerged as a highly promising energy storage technology, owing to their high theoretical energy density and being based on abundant resources. However, they are challenged by the undesirable diffusion of soluble lithium polysulfides (LiPSs) towards the lithium metal anode in electrolytes during discharge/charge cycles, which is commonly known as the shuttle behavior of LiPSs. This phenomenon ultimately leads to the degradation of the long-term Li-S batteries stability and severely limits their practical applications. To overcome this challenge, we propose the development of an innovative composite intermediate interlayer (MWCNT/SDC-PVDF) aimed at reducing charge transfer resistance and effectively capturing dissolved polysulfides.The novel polymer composite is synthesized using a recently introduced method to produce soft dendritic colloids (SDCs). The SDCs are generated through turbulent solvent-nonsolvent induced phase separation to precisely regulate the size and morphology of precipitated PVDF across varying length scales. The integration of multiple wall carbon nanotubes (MWCNT) and SDC-PVDF within a high-shear mixer enables the formation of a homogeneous composite mixture. The resulting matrix interlayer situated between the carbon nanotubes and the SDC-PVDF fibrillar polymer network exhibits a fibrous porous structure characterized by a substantial surface area higher than 103.04 m2g-1, effectively facilitating the entrapment and anchoring of LiPSs within this matrix. Furthermore, the porous framework also allows for re-utilising LiPSs in subsequent cycles to improve the irreversible of the Li-S cell.The flexible fibrous and porous MWCNT/SDC-PVDF interlayer, featuring a thin layer (∼ 55 μm ) and high conductivity, serves to mitigate cell polarization. A Li-S cell with the interlayer demonstrates a notable initial reversible capacity of 1,100 mAh g-1 at 0.2 C. The cell also achieved good capacity retention of 65% after 300 cycles at 0.2 C and 81% retention at 0.1 C after 150 cycles. Figure 1