Cross-Linked Composite Gel Polymer Electrolyte Based on an H-Shaped Poly(ethylene oxide)-Poly(propylene oxide) Tetrablock Copolymer with SiO2 Nanoparticles for Solid-State Supercapacitor Applications

Sohee Kim; Ji Hee Kim; Jae Hee Han; Jang Yong Lee; Soonyong So; Sang Jun Yoon; Hyung-Joong Kim; Kyu Tae Lee; Tae-Ho Kim

doi:10.1021/acsomega.1c01623

Cross-Linked Composite Gel Polymer Electrolyte Based on an H-Shaped Poly(ethylene oxide)-Poly(propylene oxide) Tetrablock Copolymer with SiO₂ Nanoparticles for Solid-State Supercapacitor Applications

ACS Omega. 2021 Jun 24;6(26):16924-16933. doi: 10.1021/acsomega.1c01623. eCollection 2021 Jul 6.

Authors

Sohee Kim^{1

2}, Ji Hee Kim^{1

3}, Jae Hee Han¹, Jang Yong Lee¹, Soonyong So¹, Sang Jun Yoon¹, Hyung-Joong Kim³, Kyu Tae Lee², Tae-Ho Kim¹

Affiliations

¹ Energy Materials Research Center, Korea Research Institute of Chemical Technology, 141 Gajeong-ro, Yuseong-gu, Daejeon 34114, Republic of Korea.
² School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea.
³ Department of Advanced Materials Engineering, Kongju National University, Cheonan 331-240, Republic of Korea.

Abstract

Achieving high ionic conductivity, wide voltage window, and good mechanical strength in a single material remains a key challenge for polymer-based electrolytes for use in solid-state supercapacitors (SCs). Herein, we report cross-linked composite gel polymer electrolytes (CGPEs) based on multi-cross-linkable H-shaped poly(ethylene oxide)-poly(propylene oxide) (PEO-PPO) tetrablock copolymer precursors, SiO₂ nanoparticles, and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, an ionic liquid (IL). Self-standing CGPE membranes with a high IL content were prepared using in situ cross-linking reactions between the silane groups present in the precursor and the SiO₂ surface. The incorporation of an optimal amount of SiO₂ increased the cross-linking density of the resulting CGPE while reducing polymer-chain ordering and, consequently, increasing both ionic conductivity and mechanical strength. As a result, the CGPE with 0.1 wt % SiO₂ exhibited a high ionic conductivity (2.22 × 10^-3 S cm^-1 at 25 °C), good tensile strength (453 kPa), and high thermal stability up to 330 °C. Finally, an all-solid-state SC assembled with the prepared CGPE showed a high operating voltage (3 V), a large specific capacitance (103.9 F g^-1 at 1 A g^-1), and excellent durability (94% capacitance retention over 10,000 charge/discharge cycles), which highlights its strong potential as a solid-state electrolyte for SCs.