Inhibiting polysulfides with PDA / PEI‐functionalized separators for stable lithium‐sulfur batteries

Abstract

Summary Lithium‐sulfur batteries are considered the most promising candidates for energy storage materials in the future, but the shuttle of polysulfides has seriously affected the development of lithium‐sulfur batteries. Because the surface morphology of the material determines its structural properties to some extent. Therefore, the surface of celgard‐2400 is structurally modified by controlling the polymerization of dopamine to further improve the performance of the separator. Utilizing the effective adsorption performance of dopamine and the interaction with PEI, an effective network structure is formed. The polydopamine and polyethyleneimine (PDA/PEI) coating forms a good physical barrier while a large amount of N, O elements and polysulfides adsorb each other, which effectively inhibits the shuttle of polysulfides. After coating, the rapid increase of the electrolyte wettability and liquid absorption rate of the separator will provide a guarantee for lithium ion transmission. Through electrochemical tests, the initial capacity of the battery modified by PDA/PEI coating reached 1250 mAh g−1 at 0.2 C, and remained above 900 mAh g−1 after 100 cycles. While the rate performance and cycle stability are improved, the electrochemical impedance is also reduced. This solution can be prepared lot size is a promising improved technology.

Recent advances in modified commercial separators for lithium–sulfur batteries

“…While greater PAA grafting improved LiPS rejection via highly selective ionic sieving, the composite membrane exhibited greater hydrophobicity, which decreased electrolyte wettability and, consequently, ionic conductivity. In more recent work, Pei et al 144 similarly found that appending a polydopamine (PDA) layer to a Celgard membrane reduced average pore sizes by 35% (130 nm). However, the PP/PA membrane surface was rough with only PDA.…”

“…142 Hydrophilic functional groups in common polymers also improve electrolyte wettability for improved Li-ion conduction. 144 Despite all the benefits of using polymer modifiers, common polymer modifications alone are usually insufficient in mitigating the shuttle effect and do not significantly improve the rate capability of LSBs, limiting their charge rate and power density.…”

“…142 Hydrophilic functional groups in common polymers also improve electrolyte wettability for improved Li-ion conduction. 144 Despite all the benets of using polymer modi-ers, common polymer modications alone are usually insuf-cient in mitigating the shuttle effect and do not signicantly improve the rate capability of LSBs, limiting their charge rate and power density. Naon is the brand name of a popular and commercially available sulfonated tetrauoroethylene-based uoropolymercopolymer modied to reduce polysulde shuttling in LSBs via physical and electrostatic mechanisms.…”

Amino‐functionalized SiO 2 modified porous polyetherimide separator for high performance Li‐S batteries

“…[6][7][8][9][10][11][12] Of these, separator modification and functionalization provide an attractive solution by virtue of its simplicity and effectiveness. [13][14][15] As an important part of Li-S batteries, the separator prohibits the cutting-out of batteries and acts as the channel to transport lithium ions between electrodes. Currently, polyolefin microporous membranes prepared by melt-stretching method are commonly used for Li-S batteries as it owns advantages of high chemical stability and low interfacial impedance.…”

“…Aiming at these issues, numerous efforts have been devoted to this area 6‐12 . Of these, separator modification and functionalization provide an attractive solution by virtue of its simplicity and effectiveness 13‐15 …”