Manipulating Polysulfide Conversion with Strongly Coupled Fe₃O₄ and Nitrogen Doped Carbon for Stable and High Capacity Lithium–Sulfur Batteries

Abstract

Li–S batteries are among the most promising energy storage technologies but their commercialization faces substantial challenges, largely due to difficulties in controlling their reaction pathways under practical conditions. Here, the synthesis of strongly coupled Fe3O4 and N‐doped carbon directly in flexible carbon cloth is demonstrated, as well as their novel use for hosting sulfur with outstanding performance for Li–S batteries. It is discovered that the synergistic effects of Fe3O4 and N‐carbon bring strong adsorption toward lithium polysulfide, and ensure nearly complete conversion of short‐chain polysulfide to Li2S during discharge. The Li2S solids generated on these novel hosts are extremely reactive and can be readily charged back to S without a noticeable overpotential. The critical roles of Fe3O4 and N‐doped carbon are studied and direct correlations are established between their surface concentration/crystallinity and the Li2S4 to Li2S conversion capacity. This novel manipulation of polysulfide conversion allows to fabricate freestanding and flexible sulfur cathodes that deliver a specific capacity of 1316 mAh g−1 at 0.1C and stable cycling for 1000 cycles at 0.2C under a high sulfur loading of ≈4.7 mg cm−2.

Nickel Hollow Spheres Concatenated by Nitrogen‐Doped Carbon Fibers for Enhancing Electrochemical Kinetics of Sodium–Sulfur Batteries

“…Against this background, for an anticipant cathode of Na‐S batteries, the sulfur host needs to meet the following requirements generally to alleviate the performance deterioration: first, the host should possess desirable electronic conductivity to counteract that of S; besides, abundant pore structure or hollow structure is needed to buffer the volume expansion of S and physically restrict the shuttle of polysulfide; finally, as proved by reported literatures that the polar material with intrinsic sulfiphilic property is necessary because of the excellent chemical adsorption for soluble polysulfide. Therefore, several homologous hosts have been explored to improve the electrochemical performances of RT Na‐S and Li‐S batteries, such as heteroatom‐doped porous carbon, metal oxides (TiO 2, MnO 2 , Fe 3 O 4 ), and metal sulfides (FeS 2 , Co 9 S 8 ) . But anyway, the adsorption of the polar surface for polysulfide is insufficient, and thus the shuttle effect of sodium polysulfide still exists.…”

Si@SnS2–Reduced Graphene Oxide Composite Anodes for High‐Capacity Lithium‐Ion Batteries

“…The lowest capacity decay rate and the highest discharge specific capacity were obtained at a current density of 200 mA g −1 ; as the specific current was increased stepwise from 200 to 400, 600, 800, 1000, 2000 and 3000 mA g −1 , the capacities after 200 cycles were 1480.1, 1186.4, 9846, 791.1, 703.1, 587.1 and 451.3 mAh g −1 , respectively. These results indicate that the micro/nanostructured Si@SnS 2 ‐rGO composite exhibits an efficient lithium ion storage performance …”

Chainmail Catalyst of Fe3O4@C/CNTO‐Modified Celgard Separator with Low Metal Loading for High‐Performance Lithium–Sulfur Batteries

“…The voltage ranged from −0.8 to 0.8 V with a scanning rate of 20 mV s −1 . As shown in the Figure e, compared with the battery with CNTO, the battery with Fe 3 O 4 @C/CNTO exhibits higher current illustrating the rapid conversion of LiPSs on the electrode . Figure f is the 3 th cycle discharge/charge profiles of the battery with Fe 3 O 4 @C/CNTO and CNTO under the current of 0.2 C. The battery with Fe 3 O 4 @C/CNTO shows a higher specific capacity of 1155 mA h g −1 than the CNTO sample of 1030 mA h g −1 , demonstrating the improvement of sulfur utilization.…”