Polyelectrolyte Binder for Sulfur Cathode To Improve the Cycle Performance and Discharge Property of Lithium–Sulfur Battery

Abstract

To achieve the higher capacity and the better cycle performance of the lithium-sulfur (L-S) batteries, a copolymer electrolyte prepared via emulsifier-free emulsion polymerization was used as the binder for the sulfur cathode in this study. This polyelectrolyte binder has uniform dispersion and good Li conductivity in the cathode that can improve the kinetics of sulfur electrochemical reactions. As a result, the capacity and cycle performance of the battery are improved evidently when the cell is discharged to 1.8 V. Moreover, when the cell is discharged to 1.5 V, the difficult deposition of LiS will take place easily at 1.75 V, and the difficult transformation from solid LiS to solid LiS will progress smoothly and completely during the voltage range of 1.55-1.75 V, too. The capacity of this L-S battery discharged to 1.5 V is as much as 1700 mAh g, which is very close to the theoretical value of sulfur cathode. The knowledge acquired in this study is valuable not only for the design of an efficient new polyelectrolyte binder for sulfur cathode but also the discovery that the discharge degree is the main fact that limits the capacity to reach its theoretical value.

Carbon Nanofibers Grown on Carbon Felt as a Reinforced Current Collector for High‐Performance Lithium−Sulfur Batteries

“…Typically, all the profiles consist of two typical plateaus at 2.3 V and 2.1 V, which correspond to the formation of long‐chain polysulfides (Li 2 S 8∼4 ) and low‐order polysulfides (Li 2 S 4∼2 and Li 2 S). For the CF@CNFs−S/G cathode, it is worth emphasizing that another plateau at 1.75 V contribute parts of the discharge capacity, mainly owing to formation more of solid‐phase transition from Li 2 S 2 to Li 2 S and the reduction of LiNO 3 . And then the following charge curve exhibits a sharp increase of the voltage up to 2.35 V in the early stage at 0.1 C caused by the effect of insulating products (inset of Figure a).…”

Housing Sulfur in Polymer Composite Frameworks for Li–S Batteries

“…As mentioned earlier, the mechanical strength and adhesive properties of PEO frameworks suffer from swelling/ Reproduced with permission from Ref. [196]. Copyright 2018 Elsevier dissolution in organic electrolytes.…”

Water Reducer: A Highly Dispersing Binder for High‐Performance Lithium‐Sulfur Batteries†

“…As we can see, after 100 charge/discharge cycles, the sulfur cathode with SMF binder demonstrates the most stable charge/discharge plateaus and the lowest voltage gap, which benefits longer cycling performances. [ 38‐41 ] And from fitted electrode impedance spectra (EIS) in Figure 3f, in the high‐frequency region, the intercept on the real axis and a depressed semicircle are ascribed to electrolyte ohmic resistance ( R s ) and the charge transfer resistance ( R ct ), respectively. The tilted straight line in the low‐frequency region is ascribed to Warburg impedance.…”