High-Performance Ionic Liquid-Based Gel Polymer Electrolyte Incorporating Anion-Trapping Boron Sites for All-Solid-State Supercapacitor Application

Abstract

A high-performance boron-containing gel polymer electrolyte (GPE) with semi-interpenetrating polymer network structure was successfully prepared by a rapid and easy one-step polymerization process assisted with UV light, exploiting poly(ethylene oxide) as a polymer host, the novel borate ester monomer as the cross-linker, and LiClO and EMIMBF both as the plasticizer and electrolytic salt, respectively. Owing to the incorporation of anion-trapping boron sites, the ionic conductivity of the as-prepared GPE at room temperature can be up to 5.13 mS cm. In addition, the boron-containing GPE (B-GPE) exhibits favorable mechanical strength, excellent thermal stability, and extremely low flammability. Moreover, the all-solid-state symmetric supercapacitor using B-GPE as the electrolyte and reduced graphene oxide as the electrode was fabricated and exhibited a broad potential window (3.2 V). The all-solid-state symmetric supercapacitor based on B-GPE can still reach a high energy density of 27.62 W h kg with a power density of 6.91 kW kg at a high current density of 5 A g. After 5000 cycles at a current density of 1 A g, the all-solid-state supercapacitor with B-GPE displays a decent capacitance retention of 91.2%.

“All-in-Gel” design for supercapacitors towards solid-state energy devices with thermal and mechanical compliance

“…The ionic liquid has a wide temperature range in which it retains the liquid state, whilst the polymer matrix itself can provide ion transfer pathways, therefore, even at the low temperature of -40 o C, the ionogel device can still maintain a reasonable capacitive performance. The ionic conductivity of the polymer matrix can be attributed to the amorphous domains 33,34 ,leading to an improved performance compared to a conventional insulating separator 35,36 . Fig.…”

Ionic liquid electrolytes in electric double layer capacitors

“…10c . Jin et al [118] prepared a high-performance boron-containing GPE with semi-interpenetrating polymer network structure incorporating with the anion-trapping boron sites, which was beneficial to a better capacitance retention of 91.2%. One of the recent host polymers is the poly(ionic liquid) (PIL) by polymerizing the IL itself [119][120][121].…”

Multi‐walled carbon nanotubes incorporation into cross‐linked novel alkaline ion‐exchange membrane for high efficiency all‐solid‐state supercapacitors

“…Actually, SCs can be optimized by substituting for the liquid electrolyte with the solid electrolyte of conventional SCs such as the typical gel electrolytes (GEs) and ion‐exchange polymer electrolytes. GEs are commonly applied in SCs and exhibit the advantages of low corrosion and simple operation . Nevertheless, the poor mechanical properties of GE currently make the physical protection between the two electrodes insufficient.…”

“…GEs are commonly applied in SCs and exhibit the advantages of low corrosion and simple operation. [17][18][19][20][21] Nevertheless, the poor mechanical properties of GE currently make the physical protection between the two electrodes insufficient. For example, an alkaline gel polymer electrolyte composed of polyvinyl alcohol and kappacarrageenan (named PK AGPE) was proposed that showed a high hydroxide conductivity σ OH− but poor mechanical properties (the tensile strength [TS] was merely 2.22 MPa).…”