Boosted Polysulfide Conversion by Co, Mn Bimetallic-Modulated Nitrogen–Carbon Material for Advanced Lithium–Sulfur Batteries

Abstract

Lithium–sulfur batteries (LSBs) are regarded as one of the most promising future generation rechargeable battery energy storage devices due to their high theoretical specific capacity and energy density. However, the development of LSBs is largely influenced by the shuttle effect and slow kinetics of lithium polysulfides, which seriously hinder their commercial applications. Based on this, we propose a bimetallic modulating strategy to synthesize carbon tube embedded with Co and Mn bimetals anchored on a nitrogen-doped carbon nanosheet (Co/Mn-GC@N–C) function separator to catalytic polysulfide conversion and enhance the electrochemical performance. Co/Mn-GC@N–C possesses high electrical conductivity and large specific surface area, which can offer a lot of active sites for anchoring polysulfides, stimulating their redox reaction and quickening the electrode reaction kinetics. The comprehensive test results show that the cell with Co/Mn-GC@N–C exhibits a specific discharge capacity of 1215 mAh g–1 at 0.5C and a high Coulombic efficiency of 99.4% after 300 cycles; even the Co/Mn-GC@N–C cell with a high sulfur loading of 6.6 mg cm–2 shows a high area capacity of 5 mAh cm–2. Therefore, this bimetallic modulating strategy provides an option for the design of advanced high-performance lithium–sulfur battery separator materials.

Improvement of Redox Kinetics of Dendrite-Free Lithium–Sulfur Battery by Bidirectional Catalysis of Cationic Dual-Active Sites

“…As shown in Figure a, the CV curve of the 3DCS-FMO battery had the highest current density intensity, and the current density decreased in the order 3DCS-FMO@C > 3DCS-MO@C > PP. Thus, the modified separator can effectively enhance the charge and polysulfide transport, which was beneficial to the sulfur redox reaction kinetics . The enhanced bidirectional reaction kinetics was further characterized by Tafel plots.…”

“…Polysulfide-free lithium−sulfur electrolytes were used, which ruled out the influence of polysulfides on lithium dendrites. 51,52 As shown in Figure 7a, the commercial PP separator had a significantly high overpotential after 100 cycles, which was due to the formation of "dead lithium" on the lithium surface. Consequently, the SEI film on the lithium anode surface decomposed to form an unstable electrolyte− anode interface.…”

In Situ Generation of Co-Decorated Carbon Nanotubes by Zeolitic Imidazolate Frameworks to Facilitate High-Performance Lithium–Sulfur Batteries

“…Li–S batteries are considered to be a promising energy storage system due to the high theoretical capacity (1675 mAh g –1 ), high theoretical energy density (2600 Wh kg –1 ), environmental friendliness, low cost, and easy availability. − However, Li–S batteries still face many challenges, such as the poor conductivity of S 8 and Li 2 S, volume expansion of S 8 , the “shuttle effect” of soluble polysulfides (LiPSs, Li 2 S n , 4 ≤ n ≤ 8) in the electrolyte, and sluggish redox kinetics of LiPSs during their conversion reaction. − These inherent shortcomings restrict their commercial application.…”

Room temperature‐responsive poly(vinyl hydroxyalkyl ether‐alt‐dialkyl maleate)‐based vitrimers with dynamic boronic ester bonds

“…CANs can be divided into two types per the mechanism. One is the dissociation mechanism, such as the reversible Diels–Alder reaction, whereas the other involves the reassociation mechanism, like disulfide exchange and dynamic ester exchange, and so forth 14–18 . Vitrimers, as a subset of CANs, containing dynamic covalent bonds, were groundbreakingly proposed by Leibler and his coworkers in 2011 19 .…”