Synthesis of a copolymer with a dynamic disulfide network and its application to a lithium-ion capacitor polymer electrolyte

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2024-10, Vol.497, p.154430, Article 154430
• Main Authors: Nguyen, Trong Danh, Roh, Sojeong, Nguyen, My Thi Ngoc, Nam, Yeonjeong, Kim, Dong-Joo, Lim, Byungkwon, Yoon, Young Soo, Lee, Jun Seop
• Format: Article
• Language: English
• Subjects: Copolymer; Dielectric permittivity; Dynamic covalent bonding; Lithium-ion capacitor; Polymer electrolyte
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.154430

[Display omitted] •An ionic conducting disulfide network was synthesized based on polyethylene.•The copolymer can maintain the ionic conductivity of polyethylene glycol.•The copolymer network has a short chain segment relaxation time (5.18 × 10−5 s).•The melted network can penetrate the complicated surface of active material.•Lithium hybrid capacitor with copolymer as electrolyte performed excellently. Polymer electrolytes are being actively researched in energy storage applications because of their large operating potential range and cycle stability. Among them, poly(ethylene glycol) (PEG) is most commonly used to take advantage of the high ionic conductivity generated by polar functional groups in the structure. However, the polar functional group in the PEG structure has limitations that not only interfere with the movement of ions through interchain interaction, but also prevent the penetration of the polymer structure into the electrode material. In this paper, a copolymer into which a dynamic disulfide bonding network was introduced based on PEG was synthesized to control the polar functional effect of the polymer chain. The copolymer was then applied as a lithium-ion hybrid capacitor electrolyte. Due to the disconnection of the dynamic disulfide bond, the viscosity of the polymer electrolyte was reduced, allowing smooth penetration into the electrode material. The copolymer-based polymer electrolyte showed better energy storage performance and shorter relaxation time than a commercial PEG-based device (225 F g−1/5.18 × 10−5 s for copolymer and 166 F g−1/7.96 × 10−3 s for PEG). In addition, the copolymer not only preserved excellent ionic conductivity of PEG at a certain level (from 6.3 × 10−4 S cm−1 to 3.73 × 10−4 S cm−1) but also decreased the polarity of the material due to the presence of the nonpolar disulfide chain, thereby reducing crystallinity and dielectric permittivity (from 1460 to 246).