Microreactor Strategy to Capture Sulfur for Lithium–Sulfur Batteries

The limited conductivity and shuttle effect tie the sulfur cathode down. Carbon nanofibers (CNFs) offer long-range conductivity with cost effectiveness but fail for the wanted backing since they are intertwined with each other, which makes it difficult for sulfur to permeate the mass of the CNF matrix. Dissolving or melting sulfur and immersing it in the bulk of CNFs cannot avoid sulfur segregation. By nanosizing sulfur and loading it into the bulk of the CNFs with the assistance of surfactants, we propose a microreactor strategy to address these challenges. Due to the spatial constraints within the S@CNF microreactors, the nanostructured sulfur can be sintered at high temperatures without significant mass loss. As a result, not only is the electrical conductivity improved but also the shuttle effect is obviously confined in microreactors, enhancing cycle performance at an elevated S/C ratio of 8:2. The diffusion coefficient and activation energy characterized by the Randles–Sevcik equation and operando approaches, respectively, validate the enhancement of dynamics, which can be ascribed to the promoting effect of electronic transitions on ionic diffusion. The analysis of optical and electrochemical band gaps confirms this point of view. Thereby, using the microreactor strategy, we turn the adverse mass of the CNFs into favorable factors.