Exploiting Natural Diatom Shells as an Affordable Polar Host for Sulfur in Li-S Batteries

Abstract

Given the high theoretical capacity (1,675 mAh g–1) and the inherent affordability and ubiquity of elemental sulfur, it stands out as a prominent cathode material for advanced lithium metal batteries. Traditionally, sulfur was sequestered within conductive porous carbons, rooted in the understanding that their inherent conductivity could offset sulfur’s non-conductive nature. This study, however, pivots toward a transformative approach by utilizing diatom shell (DS, diatomite)—a naturally abundant and economically viable siliceous mineral—as a sulfur host. This approach enabled the development of a sulfur-layered diatomite/S composite (DS/S) for cathodic applications. Even in the face of the insulating nature of both diatomite and sulfur, the DS/S composite displayed vigorous participation in the electrochemical conversion process. Furthermore, this composite substantially curbed the loss of soluble polysulfides and minimized structural wear during cycling. As a tes-tament to its efficacy, our Li-S battery, integrating this composite, exhibited an excellent cycling performance: a specific capacity of 732 mAh g–1 after 100 cycles and a robust 77% capacity retention. These findings challenge the erstwhile con-viction of requiring a conductive host for sulfur. Owing to diatomite’s hierarchical porous architecture, eco-friendliness, and accessibility, the DS/S electrode boasts optimal sulfur utilization, elevated specific capacity, enhanced rate capabilities at intensified C rates, and steadfast cycling stability that underscore its vast commercial promise. © 2024, Korean Electrochemical Society. All rights reserved.