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Due to high absorbance of UV light and low solid loading, the stereolithography-based additive manufacturing of gray-colored and dense Si3N4 ceramic is of significant difficulty and challenge. The effects of geometric properties of ceramic powders on the curing performance were investigated by studying the absorption difference of the Si3N4 ceramic particles with different colors and particle sizes and ultraviolet light. The results show that the transmission of ultraviolet light and curing performance of the darker Si3N4 ceramic slurry are much poor. Under the same particle size, the Si3N4 ceramic slurry using lighter particles presents the smaller scattering coefficient. The scattering coefficient (∼202) of the gray powder with ∼0.8 μm average particle size is the smallest. Under the same color, the larger the particle size, the smaller the scattering coefficient. The smallest scattering coefficient of the white powder with ∼2.0 μm average particle size is ∼110.

Nickel hydroxide (Ni(OH)2) is one of the most attractive electrode materials for supercapacitor applications due to its intrinsically high redox capacitance. However, the electrochemical performanc...

Silicon nitride (Si3N4) ceramic slurry with high-solid loading, low-viscosity and high curing depth was prepared by using a surface modifier (silane coupling agent) directly as the dispersant. The effect of the interaction between modified Si3N4 powders and prepolymer on rheological property, kinetic stability, wettability and curing property of the slurry was investigated. The stereolithography forming mechanism of the modified Si3N4 ceramic slurry was elucidated. It is revealed that the epoxy group of KH560 can easily form an ether covalent bond with the hydroxyl group of bisphenol A epoxy acrylate (EA). This makes submicron sized Si3N4 powder well-dispersed in the premixed liquid and leads to improved rheological properties and kinetic stability of the ceramic slurry. In particular, the ether covalent bond formed between surface modified Si3N4 powder and EA reduces the surface tension of the slurry and enhances the wettability of the cured slurry layer. KH560 acts as a molecular bridge linking EA to Si3N4 powder surface and forms an EA shell structure. Therefore, the refractive index difference between the Si3N4 powder and prepolymer reduces significantly by two orders of magnitude, leading to an increase in the curing depth. These findings could be crucial for the stereolithographic fabrication of high refractive index ceramics parts with high precision and complex geometries.

Photocurable gray-colored Si3N4 ceramic slurry with high solid loading, suitable viscosity and high curing depth is critical to fabricate dense ceramic parts with complex shape and high surface precision by stereolithography technology. In the present study, Si3N4 ceramic slurry with suitable viscosity, high solid loading (45 vol %) and curing depth of 50 μm was prepared successfully when surface modifier KH560 (1 wt%) and dispersant Darvan (1 wt%) were used. The slurry exhibits the shear thinning behavior. Based on the Beer-Lambert formula, Dp (the attenuation length) and Ec (the critical energy dose) of Si3N4 ceramic slurry with solid loading of 45 vol % were derived as 0.032 mm and 0.177 mJ/mm2, respectively. Si3N4 ceramic green parts with complex shape and high surface precision were successfully fabricated by stereolithography technology. After optimizing the debinding and sintering process for green parts, dense Si3N4 ceramics with 3.28 g/cm3 sintering density were fabricated. The microhardness and fracture toughness of as-sintered Si3N4 ceramics are ~14.63 GPa and ~5.82 MPa m1/2, respectively, which are comparable to those of the samples by traditional dry-pressed and pressureless sintering technology. These results show that ceramic stereolithography technology could be promising to fabricate high performance ceramics, especially for gray-colored monolithic Si3N4 ceramics.

In this work, the anion in situ doped nickel hydroxide nanoparticles were electrochemically synthesized by different nickel salt solution. NO3−, Cl− and SO42− can be in situ intercalated into the cathodically deposited Ni(OH)2 sample (α-phase), while CH3COO− cannot be in situ intercalated into the cathodically deposited Ni(OH)2 sample (β-phase). The doping effect on the electrochemical performances of the synthesized sample is related with both of the size and the structure characteristic of the doped anions. On one side, the enlargement of lattice spacing is beneficial to H+/OH− transfer, and on the other side, the steric hindrance effect is restrictive to H+/OH− transfer. However, the NO3− intercalated Ni(OH)2 sample has the largest lattice spacing and the highest electrochemical performances due to its special planar structure characteristic and the effect on the dissociation energy of O-H bond in the charge-discharge process of Ni(OH)2.

Herein, we prepared a novel nickel iron-layered double hydroxide/reduced graphene oxide/nickel foam (NiFe-LDH/RGO/NF) electrodes by two step electrodeposition processes for oxygen evolution reaction (OER). The modification of NF by RGO increased the interface conductivity and electrochemical active surface areas (ECSA) of the electrode. The NiFe-LDH/RGO/NF electrode has shown higher catalytic activity with a lower overpotential of 150 mV at the current density of 10 mA cm −2 . The NiFe-LDH/RGO/NF electrode has also shown a small Tafel slope of 35 mV per decade due to the synergy effect between the larger ECSA and the conductive RGO interface. Furthermore, the electrodes exhibits almost 10 h stability under a general current density of 10 mA cm −2 .

Reduced graphene oxide (rGO)-modified copper foil composite material was prepared by electrocoagulation of graphene oxide (GO) and a subsequent chemical reduction process. The effects of deposition voltages and the reduction time on the morphology, structure and electrochemical performances of the sample are investigated. The uniform surface morphology of GO/Cu sample obtained at a deposition voltage of 2.5 V. However, the appropriate chemical reduction not only improves the electrical conductivity of GO/Cu, but also enhances anticorrosion performance. At the optimized deposition voltages (2.5 V) and reduction time (20 min), the rGO/Cu shows the highest anticorrosive property and good conductivity. The protective efficiency of rGO/Cu is up to 98% (vs bare copper) as compared with 60% of GO/Cu according to Tafel analyses. The conductivity of rGO/Cu is close to bare copper according to the electrochemical impedance spectroscopy (EIS) results of Ni(OH)2/rGO/Cu and measurement of surface resistivity. We consider that rGO/Cu is a suitable material for realizing the copper foil manufacture with high corrosion resistance without sacrificing conductivity.

In this study, α-Ni(OH)2 with controllable pristine crystal size is directly electrodeposited on a substrate of Ti wire mesh to fabricate the integrated electrode. The nanoscale effects on morphology, microstructure and electrochemical performance of the cathodic deposited α-Ni(OH)2 are studied. The results show that the morphology of α-Ni(OH)2 varies from irregular honeycomb-like nanopieces, ball-shaped particles to oval nanoplates as the cathodic deposition current density increases. The nanostructure diversity of the cathodic deposited α-Ni(OH)2 is due to the different nanosize which directly depends on the cathodic deposition current density. The electrochemical performances of the cathodic deposited α-Ni(OH)2 increase with the decrease of the pristine crystal size of α-Ni(OH)2. The oval α-Ni(OH)2 nanoplates consisting of nanosheets with a pristine crystal size of 3 ∼ 5 nm × 5 ∼ 7 nm show the ultrahigh specific capacities of ∼348 mAh g−1 and ∼312.5 mAh g−1 at charge/discharge current density of 5 A g−1 and 100 A g−1, respectively, and over 70% specific capacity still remains after 1000 cycles, while the irregular honeycomb-like α-Ni(OH)2 consisting of nanosheet with a pristine crystal size of 10 ∼ 15 nm × 15 ∼ 20 nm shows only ∼260 mAh g−1 specific capacity at 5 A g−1 and ∼150 mAh g−1 at 100 A g−1. The ultrahigh electrochemical performances are attributed to the nanoscale and the defective nanostructure of the cathodic deposited α-Ni(OH)2.

Controlled synthesis of efficient core-shell non-precious metal catalysts for oxygen reduction reaction (ORR) is undoubtedly crucial but challenging for the extensive application of fuel cells and metal-air batteries. Herein, we prepared a core-shell structured Fe/FeCx nanoparticles and porous carbon composited catalyst (Fe/FeCx@NC) via a facile two-step heat treatment strategy. The Fe/FeCx@NC-800−0.5 prepared with secondary anneal at 800 °C for 0.5 h exhibits superior ORR performance to the commercial Pt/C in terms of comparable onset potential, higher half-wave potential, and outstanding long-term durability in alkaline media. Through combining the physical and electrochemical characterizations of Fe/FeCx@NC-T−t with different anneal temperature and precursors, the outstanding ORR performance of Fe/FeCx@NC-800−0.5 is caused by the synergistic effect between Fe/FeCx core and enriched pyridinic N- and graphitic N-doped carbon shell as well as porous carbon with large specific surface area. The structure-activity relationship of core-shell structured Fe–N–C catalysts for ORR provides directions for the development of advanced nonprecious metals catalysts.

Si/C materials are considered as the most promising anodes for the next generation lithium ion batteries. However, the Si/C anodes with high Coulombic efficiency are still a challenge. Here, pomegranate-like Si@C microspheres are successfully prepared with inexpensive AlSi alloy by surface modification, coating with resin, carbonization and acid etching processes. As high as 84.98% initial Coulombic efficiency (ICE) and 100% Coulombic efficiency are obtained for the sample (Si40@C3), and the specific capacity still maintained over 620 mAh g−1 with capacity retention of 70.4% over 250 cycles. The excellent electrochemical performance could be attributed to the distinctive pomegranate-like Si@C structure, which either stabilizes the porous structure of Si particle by inhibiting the volume expansion and pulverization or improves the electrochemical property by the appropriate carbon coating layer. This would provide a helpful guide to synthesize the Si/C anode with high ICE and Coulombic efficiency and stable cycling.

Electrolytic water splitting, consists of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), still has many challenges because of the high cost and scarity of the indispensable noble metal catalysts. Herein, the costless and effective NiFe layered double hydroxide (NiFe-LDH), supported on the Ti3C2Tx modified 3D nickel foam (NF), is used instead of noble metal to intensify the transfer ability of the charges as well as ions in the OER catalysis process. The prepared NiFe-LDH/Ti3C2Tx/NF electrode has a lower overpotential (240 ​mV ​at 50 ​mA ​cm−2) and Tafel slope (82 ​mV dec−1) as compared with that of IrO2/Ti3C2Tx/NF(400 ​mV, 252 ​mV dec−1). Meanwhile, it has a good endurance and stability with a negligible voltage changing after 15 ​h of testing. The work provides reference for the synthetic of catalyst with high catalytic kinetics and activity in the field of electrolytic water splitting.

Highly ordered TiO 2 nanotube arrays (NTAs) with excellent stability and large specific surface area make them competitive using as supercapacitor materials. Improving the conductivity of TiO 2 is of great concern for the construction of high-performance supercapacitors. In this work, we developed a novel approach to improve the performance of TiO 2 materials, involving the fabrication of Al-doped TiO 2 NTAs by a simple electrochemical cathodic polarization treatment in AlCl 3 aqueous solution. The prepared Al-doped TiO 2 NTAs exhibited excellent electrochemical performances, attributing to the remarkably improved electrical conductivity (i.e., from approx. 10 kΩ to 20 Ω). Further analysis showed that Al 3+ ions rather than H + protons doped into TiO 2 lattice cause this high conductivity. A MnO 2 /Al–TiO 2 composite was evaluated by cyclic voltammetry, and achieved the specific capacitance of 544 F g −1 , and the Ragone plot of the sample showed a high power density but less reduction of energy density. These results indicate that the MnO 2 /Al–TiO 2 NTAs sample could be served as a promising electrode material for high -performance supercapacitors.

Magneli phase titanium sub-oxide conductive ceramic Ti n O2n−1 was used as the support for Pt due to its excellent resistance to electrochemical oxidation, and Pt/Ti n O2n−1 composites were prepared by the impregnation-reduction method. The electrochemical stability of Ti n O2n−1 was investigated and the results show almost no change in the redox region after oxidation for 20 h at 1.2 V (vs NHE) in 0.5 mol/L H2SO4 aqueous solution. The catalytic activity and stability of the Pt/Ti n O2n−1 toward the oxygen reduction reaction (ORR) in 0.5 mol/L H2SO4 solution were investigated through the accelerated aging tests (AAT), and the morphology of the catalysts before and after the AAT was observed by transmission electron microscopy. At the potential of 0.55 V (vs SCE), the specific kinetic current density of the ORR on the Pt/Ti n O2n−1 is about 1.5 times that of the Pt/C. The LSV curves for the Pt/C shift negatively obviously with the half-wave potential shifting about 0.02 V after 8000 cycles AAT, while no obvious change takes place for the LSV curves for the Pt/Ti n O2n−1. The Pt particles supported on the carbon aggregate obviously, while the morphology of the Pt supported on Ti n O2n−1 remains almost unchanged, which contributes to the electrochemical surface area loss of Pt/C being about 2 times that of the Pt/Ti n O2n−1. The superior catalytic stability of Pt/Ti n O2n−1 toward the ORR could be attributed to the excellent stability of the Ti n O2n−1 and the electronic interaction between the metals and the support.

The titanium dioxide nanotube array (TiO2-NTA) is prepared by a two-step anodic oxidation method and annealed at 450 ∘C subsequently. The Al-inserted TiO2-NTA is prepared by polarizing the TiO2-NTAs electrode at 0.4 mA for 2 min in 1 mol/L AlCl3. The results show that the Al-inserted sample still remains pure anatase TiO2 phase (by XRD) and keeps intact nanotube array structure (by FE-SEM). The X-ray photoelectron spectroscopy (XPS) analysis indicates that the insertion of Al3+ into TiO2-NTAs facilitates in the reduction of Ti4+ to Ti3+. Electrochemical investigation on the Al3+ insertion process reveals that presence of Cl− ions plays vital role for the effective insertion and de-insertion of Al3+ into/from the TiO2-NTA.

A series of Ni modified MnOx/C composites were synthesized by introducing NaBH4 to MnO2/C aqueous suspension containing Ni(NO3)2. The physical properties and the activity of the composites toward the oxygen reduction reaction (ORR) were investigated via transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and the electrochemical techniques. The results show that the higher activity of the composites toward the ORR is correlated with the higher content of MnOOH species transformed from Mn(II) on the surface of the composite. The main nickel species in the composites is Ni(OH)2, while Ni(OH)2 shows little activity toward the ORR. However, introducing Ni(OH)2 with proper amount into the MnOx/C improves the distribution of the active material MnOx, which contributes to a surface with more MnOOH. The optimal composite is of the Ni/Mn atomic ratio of 1:2 and the MnOx loading of 28 wt.%. The maximum power density of the zinc–air battery with the optimized Ni modified MnOx/C as the cathode catalyst reaches up to 122 mW cm−2, much higher than the one with the MnOx/C as the air cathode catalyst (89 mW cm−2), and slightly higher than those with the Pd/C and Pt/C as the cathode catalysts.

In this work, we successfully synthesized Ni(OH)2 thin film electrode in situ doped with CNTs/rGO by cathodic electrodeposition on titanium mesh. The doping effects of CNTs and/or rGO, and the technical conditions, are investigated. The doping of CNTs/rGO can greatly improve the electrochemical performance by forming the porous structure and the conductive network in the Ni(OH)2 thin film. The highest capacity, 429.5 mAh/g at a current density of 5 A/g, is achieved for the electrode with 0.24 mg/cm2 Ni(OH)2 and codoped with CNTs and rGO, as compared with only 323.9 mAh/g for undoped electrode. Even at 100 A/g, the specific capacity can still remain 347.5 mAh/g (vs. 221.5 mAh/g for the undoped electrode), and after 1000 cycles, the retention rate of the specific capacity is 74.9% as compared with only 42.7% for the undoped electrode. Even with higher loading amounts of 1.92 mg/cm2 Ni(OH)2, the specific capacity retention rate of the codoped electrode is still much higher than that of the undoped electrode. The high electrochemical performance can be attributed to the better ion/electron transfer ability of the codoped electrode. In conclusion, by the cathodic electrodeposition and in situ doping of CNTs/rGO, the porous structure and the conductive network in Ni(OH)2 film can be constructed, which can improve the ion/electron transfer ability, therefore, the high performance film electrode with higher loading amount of Ni(OH)2 can be prepared.

The Magneli phase titanium sub-oxides conductive ceramic particles were added to Zn electrodes for use in Ni/Zn batteries. X-ray diffraction analysis indicated that the basis of the conductive ceramic was Ti4O7 and transmission electron microscopy showed that the particles were uniform in shape and size. The electrochemical performance of a Zn electrode with the conductive ceramic as the conductive additive was investigated by charge/discharge cycling test, cyclic voltammetry, and Tafel plot. Compared with a Zn electrode with acetylene black and without conductive additive, the electrode with conductive ceramic showed better cycling stability, higher discharge capacity, and corrosion resistance.

The steady and dynamic rheological behaviors of precipitated calcium carbonate (PCC) suspension in polyethylene glycol (PEG) were investigated on a TA AR2000ex rheometer. Under steady shear consistency index K and flow exponent N of suspensions with different volume fractions were determined. The shear-thinning and the discontinuous shear-thickening behavior were observed at different constant frequencies from 10 to 100 rad/s. The relationship between the complex viscosity and the constant frequency were determined. As the volume fraction increases, flow exponent N shows a rapid increase, and it increases dramatically when the discontinuous shear-thickening takes place, while consistency index K decreases. Dynamic oscillatory shear experiments were conducted at constant strain amplitude and constant frequency, respectively. For the frequency sweep, the system shows viscous property in entire range of the frequency investigated, and the complex viscosity shows discontinuous jump at a critical frequency of 10 rad/s. For the strain sweep, on the other hand, at low strain the elastic modulus is strongly dependent on the strain, and the viscous modulus is independent of the strain. But at the critical strain point both of the moduli show an abrupt jump and the system transits from elastic to viscous at a strain of 0.1.

The shear thinning and shear thickening rheological properties of PCC/PEG suspension were investigated with the increase of oscillatory amplitude stress at different constant frequencies. The results show that the complex viscosity was initially independent of stress amplitude and obvious shear thinning occurred, then dramatic shear thickening took place after reaching the minimum viscosity. Typically, in a constant frequency of 5 rad/s, the elastic modulus, viscous modulus, and tan ( is the out-of-phase angle) vs. the stress amplitude was investigated. It is found that the elastic modulus initially appeared to be independent of stress amplitude and then exhibited a rapid decrease, but the viscous modulus was independent of amplitude stress at lower amplitude stress. After reaching the minimum value the viscous modulus showed a rapid increase. On the other hand, tan increased from 0.6 to 92, which indicates that the transition from elastic to viscous had taken place and tan showed a steep increase when shear thickening occurred. Lissajous plots are shown for the dissipated energy vs. different maximum stress amplitude in the shear thinning and shear thickening regions. The relationship of dissipated energy vs. maximum stress amplitude was determined, which follows a power law. In the shear thinning region the exponent was 1.91, but it steeply increases to 3.97 in the shear thickening region.

A novel composite alkaline polymer electrolyte based on poly(vinyl alcohol) (PVA) polymer matrix, titanium dioxide (TiO2) ceramic fillers, KOH, and H2O was prepared by a solution casting method. The properties of PVA–TiO2–KOH alkaline polymer electrolyte films were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and AC impedance techniques. DSC and XRD results showed that the domain of amorphous region in the PVA polymer matrix augmented when TiO2 filler was added. The SEM result showed that TiO2 particles dispersed into the PVA matrix although some TiO2 aggregates of several micrometers were formed. The alkaline polymer electrolyte showed excellent electrochemical properties. The room temperature (20 °C) ionic conductivity values of typical samples were between 0.102 and 0.171 S cm−1. The Zn–Ni secondary battery with the alkaline polymer electrolyte PVA–TiO2–KOH had excellent electrochemical property at the low charge–discharge rate.

Hydroxyapatite (HA) was selected as dopant and synthesized by a sonochemical method in this study. PVA–HA–KOH–H 2 O composite alkaline solid polymer electrolyte (ASPE) was prepared by solution casting method. Two different doping routes, i.e., the physical mixing (PM) and in situ synthesis (ISS) were considered. The influences of the ASPE composition such as HA content, KOH content and water content on the conductivity were investigated. The ASPE prepared by ISS route has a porous structure which is important for ion transfer. Accordingly, the conductivity of the ASPE prepared by ISS is higher than that of by PM. A highest conductivity of about 0.1 S/cm is reached for ASPE prepared by ISS route at 70% water content for m (PVA): m (KOH): m (HA) = 10:14:10 system, higher than that of by PM route, 0.08 S/cm. The nickel/zinc cell shows better electrochemical properties assembled with the ASPE prepared by ISS approach than by PM approach.

The zirconium phosphate (ZrP)/Nafion1135 composite membranes were prepared by impregnating method and characterized by SEM, XRD, ac impedance and electron probe microanalysis (EPMA) techniques. The results show that ZrP(α-Zr(HPO4)2·H2O) deposited both on Nafion1135 membrane surface and in its inner structure, and the amount of deposited ZrP increases with the immersion time. A test of membrane resistance shows that the membrane resistance increases with the immersion time greatly in C V O 2 + : C H + = 0.009:0.1 mol L−1 H2SO4 + VOSO4 solution than in 0.05 mol L−1 H2SO4 solution. Subsequently, the proton diffusion coefficient D ¯ H + and VO2+ diffusion coefficient D ¯ V O 2 + in membrane are evaluated. It is found that both D ¯ H + and D ¯ V O 2 + decrease with the immersion time based on the retarding effect of the deposited ZrP. The proton diffusion coefficient in Nafion1135 was determined to be 3.412 × 10−12 m2 s−1, and a slightly lower value of 2.827 × 10−12 m2 s−1 was found in Nafion1135/ZrP5 membrane. However, the VO2+ diffusion coefficient D ¯ V O 2 + of the Nafion1135 membrane, 4.012 × 10−13 m2 s−1, is much higher than that of 1135/ZrP5 composite membrane, 0.3226 × 10−13 m2 s−1. The results show that the composite membrane has better permselectivity as to H+ and VO2+ than Nafion®1135 membrane.

The influence of the dopant Bentonite, on the ionic conductivity of the PVA-KOH-H 2 O alkaline solid polymer electrolyte (ASPE) is studied. The results show that the addition of Bentonite has both positive and negative effects on the ionic conductivity of ASPE. At lower KOH and H 2 O contents, the addition of Bentonite can break the continuous ion conducting phase of the ASPE, and therefore decrease the ASPE conductivity. However, the addition of Bentonite can also increase the KOH content in PVA matrix. This greatly increases the conductivity of the ASPE especially at higher water content. A highest ionic conductivity of 0.11 S cm −1 is reached at room temperature. A maximum ionic conductivity value is observed at relative lower water content for different amount of Bentonite-doped ASPE. The temperature dependence of the ionic conductivity is of the Arrhenius type. The ion transfer activation energy Ea , in the order of 4–6 kJ mol −1 , heavily depends on the Bentonite content. XRD and SEM tests show that PVA in the Bentonite-doped ASPE is of amorphous structure, and there are lots of interspaces in the composite ASPE inner structure. The composite electrolyte has good electrochemical stability window and good charged–discharge property in secondary Zn–Ni cells at low charge–discharge rate.

The viscoelastic behavior and the ability of dissipating energy of fumed silica dispersions in ethylene glycol, propylene glycol, and butylene glycol have been studied under oscillation stress shear. The systems show linear viscoelastic, shear thinning, and shear thickening behaviors as the shear stress (σ) increases. In linear viscoelastic region, the storage modulus (G′) and loss modulus (G″) remain unchanged; in shear thinning region, G′ decreases and the sequence of the decreasing degree of G′ is EG/SiO2>PG/SiO2> BG/SiO2; however, G″ remains unchanged with σ increasing; in shear thickening region, both G′ and G″ increase as σ increases. The magnitude of G″ is larger than that of G′ over the studied range of stress, indicating that the dispersions mainly possess viscous property, and the energy dissipated is larger than the energy stored. The dissipated energies (Ed) of EG/SiO2, PG/SiO2, and BG/SiO2 dispersions increase with the maximum strain (γ0) increasing in a second power relation under low shear stress; however, in the shear thickening region, the Ed of EG/SiO2, PG/SiO2, and BG/SiO2 dispersions show an exponential increase with γ0 increasing by the exponents of n=2.79, 4.93, and 4.88, respectively.

A novel gel of imidazole/(HPO3)3 was synthesized and incorporated into sulfonated poly (ether ether ketone) (SPEEK) to fabricate composite proton exchange membranes. The composite membranes were characterized by alternating current impedance (AC), thermogravimetry (TG), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscope (SEM) and mechanical property test. Based on the electrochemical performance investigation, the proton conductivity of the membrane is intimately correlated with the temperature and the mass ratio of imidazole/(HPO3)3 in the composite. The SPEEK/imidazole/(HPO3)3−4 composite membrane (with 44.4 wt % of imidazole/(HPO3)3) has the optimized performance at 135°C. Mover, the strength of the composite membranes is almost comparable to that of Nafion membrane. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41946.