Self‐Assembled Networks for Regulating Lithium Polysulfides in Lithium‐Sulfur Batteries

Abstract

Inhibiting the shuttle effect caused by soluble lithium polysulfides (LiPSs) is of importance for lithium‐sulfur (Li−S) batteries. Here, a strategy was developed to construct protective layers by self‐assembly networks to regulate the LiPSs. 2,5‐Dichloropyridine (25DCP) holds two kinds of functional groups. Among them, the two C−Cl bonds were nucleophilic substituted by S in LiPSs to form long chains. The pyridine N interacted with Li in other LiPSs via Li bonds to form a short chain. As a result, the long chains were cross‐linked by the short chain to form an insoluble network. The as‐prepared network covered the sulfur electrode interface to suppress the shuttle effect of the subsequently generated LiPSs. Furthermore, 25DCP improved the redox dynamics by changing the energy level and electronic structure of the sulfur species. Therefore, the Li−S batteries with 25DCP exhibited good electrochemical performance. This work provides a feasible strategy for regulating the LiPSs.

Development of Multifunctional Cathode Binder via Inverse Vulcanization for Lithium–Sulfur Battery with Enhanced Capacity Retention

“…In other words, during the discharge process, sulfur was reduced to polysulfide by combining with lithium ions, and the long-chain polysulfide was dissolved in the liquid electrolyte, causing a shuttle effect. It may be conjectured that the cathode active material, i.e., sulfur, departed from the cathode. − Notably, compared to the conventional sulfur cathode, the VB monomer with inverse vulcanized sulfur not only showed a higher capacity of the cathode active material, but the capacity decayed very slowly with repeated cycles (Figure b). Moreover, the dual voltage plateaus in discharge (reduction) cycles virtually overlapped and persisted for all 50 cycles thus tested, suggestive of improved charge retention.…”