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Although, the use of hydrocarbon membranes is one of the ways to reduce the cost of polymer electrolyte membrane fuel cells, it cannot be practically adopted due to its low mechanical durability under a dynamic wet/dry operation. Here, we present an externally-reinforced hydrocarbon membrane achieved by a three dimensional interlocking interfacial layer which forms a strong interfacial bonding between the hydrocarbon membrane and the catalyst layers. Although a conventional hydrocarbon membrane is easily delaminated from gas diffusion electrodes, the use of the three dimensional interlocking interfacial layer, prepared with a polystyrene nanoparticle template method, enhances the interfacial adhesion by 207 times. The hydrocarbon membrane, tightly connected to the gas diffusion electrodes by the three dimensional interlocking interfacial layers, has a humidity cycling durability that is 1.9 times higher in the membrane electrode assembly level by restricting the dimensional change of the membrane. Furthermore, due to the proton conducting property of the three dimensional interlocking interfacial layer, the external reinforcement does not cause any power performance losses.

A multiblock copolymer containing a highly sulfonated poly(phenylene sulfide sulfone) (sPPSS) hydrophilic oligomer and a partially fluorinated perfluorocyclobutyl (PFCB)-containing hydrophobic oligomer was synthesized. The sharp contrast between the hydrophilic and hydrophobic moieties induced a well-developed phase separation, which was observed in the transmission electron microscopy (TEM) images within the polymer electrolyte membrane (PEM). The increased chain mobility from the flexible ether and PFCB groups afforded facile thermal annealing of the membrane. Thermal annealing induced polymer chain packing of the hydrophobic moieties, enhancing the hydrophilic/hydrophobic phase separation. The fabricated membranes exhibited higher proton conductivity compared with those of conventional hydrocarbon PEM possessing a random copolymer architecture, while their dimensional swelling was suppressed. Additionally, under low humidification (a relative humidity (RH) of 50%), the sulfonated–fluorinated membrane achieved a high proton conductivity of up to 41.9 mScm−1. A high adhesion strength of 32.7 mNcm−1 was also observed, indicating strong interfacial compatibility in the membrane electrode assembly (MEA) due to its structural affinity for the contacting perfluorosulfonated binder. The enhanced hydrophilic/hydrophobic phase separations facilitated fuel cell performances of 1.13 and 0.61 Acm−2 at 0.6 V and 65 °C under 100% and 50% RH conditions, respectively, in addition to achieving stable chemical and physical durabilities.

We report solid-state fabric supercapacitors with polymer electrolyte composites (PEC). The fabric supercapacitors were comprised of a fiber-shape PEC and electrodes. The PEC was formulated by mixing a network-forming polymer, poly(vinylidene fluoride-co-hexafluoropropylene) and a room temperature ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. By using a simple electrospinning technique, we could successfully fabricate a free-standing fiber-shape PEC. The electrospun PEC showed high ionic conductivity of 0.48 mS/cm and mechanical strength of 2.4 MPa. The electrodes were produced by two-step processes consisting of electrospinning and spray coating. By using these spun electrolyte composites and electrodes, fabric supercapacitors with a sandwich structure were fabricated. The resulting device exhibited typical capacitive energy storage characteristics and the measured specific capacitance was 6.72 mF/cm2. Moreover, the device maintains its structure and electrochemical performance under repeated bending stress. This work can offer a new option for developing solid-state energy storage devices for smart textile and wearable electronic applications.

A poly (ethylene-co-vinyl acetate) (EVA)/polyimide (PI)/EVA (PIE) tri-layer separator with thermal stability and a shutdown function is fabricated for use in sodium-ion battery (SIB) applications. Porous EVA layers are coated on both sides of an electrospun-PI, acting as a supporting layer, through a dip-coating process accompanying a thermally induced phase separation in which polyethylene-block-poly (ethylene glycol) is used as a polymeric pore generator to obtain an open porous morphology. Excellent thermal stability of the PIE tri-layer separator is demonstrated, with two simultaneous incompatible thermal behaviors, i.e., a negligible thermal shrinkage of up to 200 °C, and a rapid thermal shutdown at approximately 100 °C. In addition, the PIE tri-layer separator shows a higher ionic conductivity and larger electrolyte uptake of the sodium liquid electrolyte than a commercial olefin separator, leading to better cycling performance when assembled into SIB coin cells. All these outstanding properties of PIE tri-layer separator demonstrate that its promise as a candidate separator for use in SIBs.

We synthesized novel sulfonated poly(arylene ether sulfone)s (SPAESs) multi-block copolymer membranes containing highly sulfonated hydrophilic blocks. Two different kinds of multi-block SPAESs sharing the same structure of hydrophobic blocks were proposed to investigate the membrane properties based on the effects of the hydrophilic blocks bearing sulfonic acids. The higher local concentration and acidity of the sulfonic acid groups in the hydrophilic block induced higher proton conductivity. The block SPAESs showed comparable proton conductivities to those of the state-of-the-art perfluorinated sulfonic acid (PFSA) membranes, and their transmission electron microscopy (TEM) images revealed a well-developed phase separation. In particular, the SPAES 4 X10Y10 membrane showed excellent proton conductivity, which was higher than that of the PFSA over the entire relative humidity (RH) range at 80 °C. Moreover, the multi-block SPAES membranes showed a comparable fuel cell performance to the Nafion membranes, even at 50% and 30% RH.

방향족 친핵성 치환반응을 이용하여 멀티블록형 sulfonated poly(arylene ether sulfone)(SPAES) 공중합체를 합성하였다. 서로 다른 말단(F- 또는 OH-말단)을 가지는 친수성 및 소수성 올리고머를 합성한 후 이를 이용하여 고분자 전해질 막을 합성하였다. 각기 다른 말단이 블록공중합체의 분자량에 미치는 영향을 분석하였고, 서로 다른 친수성구조가 블록고분자의 특성에 어떠한 영향을 미치는지 분석하였다. 합성된 멀티블록고분자는 70%이상의 습도에서 나피온 막과 비슷하거나 우수한 이온전도도를 나타내었고, 특히 SPAES 9의 경우 전습도 영역에서 SPAES 10보다 높은 이온전도도를 보였는데, 이는 친수성 블록내의 술폰산기의 부분 농도가 높아짐에 따라 친수성-소수성 간의 상분리가 발달되어 이온전도도가 향상된 것으로 보인다. 【Multi-block sulfonated poly(arylene ether sulfone) (SPAES) copolymer was synthesized via nucleophilic aromatic substitution reaction for proton exchange membrane fuel cell application. After synthesizing the hydrophilic and hydrophobic precursor oligomers having different end-groups (F-terminated or OH-terminated), the effect of end group on the molecular weight was investigated. Hydrophilic oligomers with hydroquinone showed better performance as fuel cell membranes. SPAES membranes showed comparable proton conductivity to that of Nafion at $80^{\circ}C$ and above 70% RH. In particular, SPAES 9 with hydroquinone showed higher proton conductivity than SPAES 10 in the whole RH range studied. Increased local concentration of sulfonic acids within hydrophilic block might develop the hydrophilic-hydrophobic phase separation in the block copolymers.】