A viscous oligomer multifunctional separator coating to enable high specific energy lithium-sulfur battery

• Published in: Ionics 2024, Vol.30 (6), p.3223-3229
• Main Authors: Hu, Lina, Wang, Xuhui, Bai, Maohui, Song, Hongjia, Fu, Zhao, Zhong, Xiangli, Wang, Jinbin
• Format: Article
• Language: English
• Subjects: Bonding strength; Carbonyl groups; Carbonyls; Chemical bonds; Chemistry; Chemistry and Materials Science; Commercialization; Condensed Matter Physics; Effectiveness; Electrochemistry; Energy Storage; Ion concentration; Lithium; Lithium batteries; Lithium ions; Lithium sulfur batteries; Oligomers; Optical and Electronic Materials; Polymer coatings; Polymers; Polymethyl methacrylate; Polysulfides; Rechargeable batteries; Renewable and Green Energy; Separators; Specific energy; Storage batteries; Storage capacity
• ISSN: 0947-7047; 1862-0760
• DOI: 10.1007/s11581-024-05531-3

Lithium-sulfur (Li–S) batteries, with high energy density (2600 Wh/kg), are emerging as one of the most potential battery systems. However, the challenges posed by Li dendrite formation and polysulfide shuttling have impeded their commercialization. To address these issues, we develop a multifunctional separator featuring poly(methyl methacrylate) (PMMA) polymer coatings (PP@PMMA), synthesized via in-situ bond opening polymerization of oligomers catalyzed by Li + ions. This approach allows for the uniform application of the viscous PMMA oligomer onto the separator without requiring additional binders. Furthermore, the diffusion of liquid polysulfide is inhibited by the strong chemical bonding between the carbonyl group of PMMA gel polymer electrolyte (GPE) and lithium sulfide. Additionally, it also enhances the adsorption of solvents and promotes Li-ion conduction, thereby increasing the ion concentration of the interface layer and inhibiting the growth of dendrites. As a result, the Li||Li symmetric cell with PP@PMMA separator exhibits stable cycling for 1000 h, and the Li|Cu asymmetric cell achieves an average coulomb efficiency of 98.2% over 300 cycles. When applied to the 5000 mAh high specific energy Li–S pouch cell, the Li–S pouch cell with PP@PMMA can obtain a capacity retention rate of 97.6% after 100 cycles, while pristine Li–S battery is fully effective after only 35 cycles. Moreover, the optimized separator also mitigates self-discharge in Li–S batteries, and the storage capacity of 120 h is improved by 22%. The multifunctional separator can not only be applied in Li metal batteries but also promote the practical application of other Li-ion secondary batteries.