Polymer Electrolyte Research Articles

AI-Assisted Flow Field Design for Proton Exchange Membrane Fuel Cells: Progress and Perspective

AI-Assisted Flow Field Design for Proton Exchange Membrane Fuel Cells: Progress and Perspective

Supramolecular Crystals based Fast Single Ion Conductor for Long‐Cycling Solid Zinc Batteries

AbstractThe solid polymer electrolytes (SPEs) used in Zn‐ion batteries (ZIBs) have low ionic conductivity due to the sluggish dynamics of polymer segments. Thus, only short‐range movement of cations is supported, leading to low ionic conductivity and Zn2+ transference (tZn2+). Zn‐based supramolecular crystals (ZMCs) have considerable potential for supporting long‐distance Zn2+ transport; however, their efficiency in ZIBs has not been explored. The present study developed a ZMC consisting of succinonitrile (SN) and zinc bis (trifluoromethylsulfonyl) imide (Zn(TFSI)2), with a structural formula identified as Zn(TFSI)2SN3. The ZMC has ordered three‐dimensional tunnels in the crystalline lattices for ion conduction, providing high ionic conductivities (6.02×10−4 S cm−1 at 25 °C and 3.26×10−5 S cm−1 at −35 °C) and a high tZn2+ (0.97). We demonstrated that a Zn‖Zn symmetrical battery with ZMCs has long‐term cycling stability (1200 h) and a dendrite‐free Zn plating/stripping process, even at a high plating areal density of 3 mAh cm−2. The as‐fabricated solid‐state Zn battery exhibited excellent performance, including high discharge capacity (1.52 mAh cm−2), long‐term cycling stability (83.6 % capacity retention after 70000 cycles (7 months)), wide temperature adaptability (−35 to 50 °C) and fast charging ability. The ZMC differs from SPEs in its structure for transporting Zn2+ ions, significantly improving solid‐state ZIBs while maintaining safety, durability, and sustainability.

Synthesis and characterization of titanium oxynitride catalyst via direct ammonia nitridation of titanium polyacrylate for oxygen reduction reaction

AbstractA titanium oxynitride catalyst for the oxygen reduction reaction (ORR) in polymer electrolyte fuel cells was synthesized through the direct ammonia nitridation of titanium complexes. Titanium polyacrylate was employed as the catalyst precursor, and the effect of the calcination temperature between 600 and 1000 °C on the catalyst structure was studied. The catalysts were characterized via X-ray diffraction, X-ray absorption spectroscopy, transmission electron microscopy, cyclic voltammetry, and powder electrical resistivity measurements. The formation of titanium oxynitride particles and deposited carbon was observed for all the samples; however, significant variations in the catalyst structure and catalytic activity were also observed. With an increase in the calcination temperature, nitridation of titanium oxynitride progressed, and the conductivity of the catalyst powder increased. The highest rest potential and ORR current density were achieved with calcination at 800 °C. Importantly, the results suggest that maintaining an optimal nitrogen doping level within the catalyst particles, along with ensuring the formation of electroconductive deposited carbon, is essential for achieving a high ORR current. This work introduces the direct ammonia nitridation of metal complexes as a promising process for designing metal oxynitride catalysts.

Day-Ahead Optimization of Proton Exchange Membrane Electrolyzer Operations Considering System Efficiency and Green Hydrogen Production Constraints Imposed by the European Regulatory Framework

Clean hydrogen (H2) use (i.e., produced using either renewable or low-carbon energy sources) can help decarbonize energy-intensive industries, the transport sector, and the power sector. The European regulatory framework establishes that the production of green H2 must be supported either by the electricity grid through a power purchase agreement (PPA) or by intermittent renewable energy source (RES) plants owned by the hydrogen producer. Although the issue of the optimization of hydrogen production costs has already been approached, constraints related to the current regulatory framework and the modeling of nonlinear electrolyzer efficiency still represent open problems. In this paper, a mixed-integer linear programming (MILP) problem, assuming as the objective function the overall cost minimization of the allowed energy mix for green H2 production, is formulated. Two approaches are compared: in the first one, electrolyzers can only operate at 100% load, whereas the second one allows for more flexible electrolyzer scheduling, by enabling partial-load working operations. The simulation results of several scenarios considering different H2 production targets, forecasted RES production, and cost for PPAs demonstrate the effectiveness of the proposed methodology.

Dual-Sliding-Surface Robust Control for the PEMFC Air-Feeding System Based on Terminal Sliding Mode Algorithm

The proton exchange membrane fuel cell (PEMFC) is the most widely used fuel cell, but it also has some limitations. One of the research pain points is controlling the oxygen content in PEMFCs. A moderate excess of oxygen boosts electrochemical reaction efficiency, while an appropriate oxygen content ensures system stability. In this paper, a fourth-order nonlinear mathematical model of a PEMFC stack air supply system is established to solve the problem of optimal oxygen excess ratio (OER) control under dynamic load conditions. Based on the model, a nonsingular terminal sliding mode controller (NTSMC) based on a sliding mode observer (SMO) is proposed. The NTSM exhibits superior robustness and performance compared to other sliding mode structures. Meanwhile, the SMO accurately predicts system states, facilitating precise control actions. Additionally, the dual sliding mode surfaces enhance system stability against parameter uncertainties and external disturbances. Our results demonstrate that the proposed controller outperforms traditional ones in terms of robustness and performance, which significantly enhances PEMFC system efficiency and stability.

Recent progress offlexible solid-state supercapacitors: electrodes, electrolytes and practical application.

Flexible solid-state supercapacitors (FSSCs) have garnered significant attention due to their advantages, including lightness, adaptability, enhanced safety, and extensive operational potential windows. These features make them highly suitable as energy storage devices for the next generation of portable and flexible electronics. The recent surge in the development and remarkable breakthroughs in novel wearable electronics have further propelled research into FSSCs. Nevertheless, several pressing issues need to be addressed in this field, including synthesizing flexible electrode materials with superior electrochemical energy storage capabilities, enhancing the physicochemical properties of solid gel polymer electrolytes, particularly in extreme environments, and ensuring effective contact between electrodes and gel electrolytes. This paper presents an overview of the latest advancements in FSSCs, focusing on electrode materials and electrolytes. Additionally, it delves into the current challenges and future prospects of FSSCs.

Modulating RuO2 Electrocatalysis via Introducing Lanthanides for Enhanced Acidic Oxygen Evolution

AbstractThe low activity of ruthenium dioxide (RuO2) and the rapid dissolution of the ruthenium (Ru) site during acid oxygen evolution reaction (OER) at high current density restricts its application in proton exchange membrane (PEM) electrolyzers. In this work, a series of rare‐earth (RE) elements doped RuO2 nanorods is developed as high‐performance OER electrocatalysts. X‐ray absorption spectroscopy suggests that RE doping regulates the local coordination environment around Ru sites, lowers the valance of Ru, and shortens the Ru─O─Ru(M) bond length, which enhances structural stability. Among the RE‐RuO2 samples, Sm‐RuO2 exhibits remarkable performance with a low overpotential of 283 mV to reach 100 mA cm−2 and maintained stability for over 140 h at 10 mA cm−2. Moreover, the PEM electrolyzer using Sm‐RuO2 as the anode can be stably operated at 500 mA cm−2 for 15 h. Electrochemical analysis, X‐ray photoelectron spectroscopy, and in situ Raman spectroscopy show that Sm doping lowers the d‐band center, reduces the adsorption energy of O intermediates to enhance the OER activity, and restrains excessive oxidation of Ru sites while stabilizing lattice oxygen during the OER process, thereby enhancing OER stability. This work offers valuable insights into improving the stability of metal oxide catalysts in acidic electrolytes.

ZnO Quantum Dots as PEO-Based Solid Electrolytes Fillers for Lithium Metal Batteries.

PEO-based solid polymer electrolyte (PEO SPE) is regarded as one of the most promising solid electrolytes due to its exceptional flexibility, cost-effectiveness, and ease of integration. However, its commercialization is hindered by inadequate ionic conductivity and unstable interface. By incorporating proper ZnO quantum-dots (QDs) fillers with enhanced surface activity, the ion transport inner the PEO-based electrolyte can be improved along with enhanced REDOX kinetics at the Li/PEO interface. The ionic conductivity reaches 5.97×10-4 S cm-1 at 60 °C. Moreover, ZnO QDs exhibit a quantum size effect and possess lithiophilic characteristics that promote uniform nucleation and redeposition of Li+ while forming a stable Li-Zn alloy. This inhibits lithium dendrite formation and enhances the stability of Li anode. Li//Li cell with 3 % ZnO QDs works steadily for more than 2100 h at 60 °C with 0.1 mA cm-2. The assembled Li//LiFePO4 cell provides a reversible capacity of 134.91 mAh g-1 after200 cycles at 0.1 C.

A Promising Gel Polymer Electrolyte Composition Comprising a Green-Glyme Di(propylene glycol) Dimethyl Ether for Application in Sodium-Ion Batteries

A Promising Gel Polymer Electrolyte Composition Comprising a Green-Glyme Di(propylene glycol) Dimethyl Ether for Application in Sodium-Ion Batteries

Molecular Crowding Solid Polymer Electrolytes for Lithium Metal Battery by In Situ Polymerization

AbstractSolid‐state polymer electrolytes (SPEs) require high ionic conductivity and dense contact with the electrodes for high‐performance lithium‐metal solid‐state batteries. However, massive challenges such as poor ionic migration ability, low antioxidant ability, and lithium dendrite formation still remain unresolved. These issues severely restrict its practical applications. Herein, a new type of solid‐state polymer electrolyte with a molecular crowding feature is rationally designed by in situ polymerization of a precursor containing poly (ethylene glycol) diacrylate (PEGDA) and 1,2‐dimethoxyethane (DME). Noticeably, the prepared SPE expands the electrochemical window to 4.7 V with a high lithium‐ion transfer number of 0.55 and a superior ionic conductivity of 3.6 mS cm−1 at room temperature. As a result, the lithium symmetrical batteries achieve stable cycles with more than 3000 h with no lithium dendrites at a current density of 0.5 mA cm−2. Importantly, this design provides dense contact of solid‐state polymer electrolytes with the porous cathode and lithium anode, allowing the assembled winding‐type solid‐state pouch cells with outstanding cycling stability of 81.7% retention for more than 340 cycles at room temperature. It shows excellent adaption to widely practical technology with large‐scale battery production, offering a new solution for the future development of solid‐state polymer lithium‐metal batteries.

PEMFC Gas-Feeding Control: Critical Insights and Review

Proton exchange membrane fuel cells (PEMFCs) are currently a relatively mature type of hydrogen energy device due to their high efficiency and low noise compared to traditional power devices. However, there are still challenges that hinder the large-scale application of PEMFCs. One key challenge lies in the gas supply system, which is a complex, coupled nonlinear system. Therefore, an effective control strategy is essential for the efficient and stable operation of the gas control system. This paper aims to provide a comprehensive and systematic overview of the control strategies for PEMFC anode and cathode supply systems based on an analysis of 182 papers. The review covers modern control theories and optimization algorithms, including their design, objectives, performance, applications, and so on. Additionally, the advantages and disadvantages of these control methods are thoroughly evaluated and summarized.

Fe‐N‐C in Proton Exchange Membrane Fuel Cells: Impact of Ionomer Loading on Degradation and Stability

AbstractFe single atoms in N‐doped C (Fe‐N‐C) present the most promising replacement for carbon‐supported Pt‐based catalysts for the O2 reduction reaction at the cathode of proton exchange membrane fuel cells (PEMFCs). However, it remains unclear how the I/C ratio affects Fe‐N‐C degradation and the stability of single Fe atom active sites (FeNx). Here, an accelerated stress test (AST) protocol is combined with emerging electrochemical techniques for a porous Fe‐N‐C in PEMFC with a range of I/C ratios. The PEMFC current density degradation rates are found to be comparable; however, with increased I/C ratio the additional FeNx sites accessed are more stable, as shown by their higher active site stability number (electrons passed per FeNx lost) at the end of the AST protocol. Meanwhile, the initial rate of TOF decay is suppressed with increasing I/C. Electrochemical process changes are studied via distribution of relaxation times analysis. Minor changes in H+ and O2 transport resistance at low current density prove kinetic degradation dominants at high potentials. These findings demonstrate how electrochemical techniques can be combined with stability metrics to determine and deconvolute changes from the active site to device level electrochemical processes in PEMFCs.

Engineering Topological and Chemical Disorder in Pd Sites for Record-Breaking Formic Acid Electrocatalytic Oxidation.

Designing palladium-based formic acid oxidation reaction (FAOR) catalysts to achieve significant breakthroughs in catalytic activity, pathway selectivity, and toxicity resistance is both urgent and challenging. Here, these challenges are addressed by pioneering a novel catalyst design that incorporates both topological and chemical disorder, developing a new class of PdCuLaYMnW high-entropy amorphous alloys with a porous network (Net-Pd-HEAA) as a highly active, selective, and stable FAOR electrocatalyst. This novel Net-Pd-HEAA demonstrates record-breaking FAOR performance, achieving the mass and specific activities of 5.94 A mgPd -1 and 8.94mA cm-2, respectively, surpassing all previously reported Pd-based catalysts and showing strong competitiveness against advanced Pt-based catalysts. Simulataneously, Net-Pd-HEAA exhibits extraordinary stability in accelerated durability tests (ADT) and chronoamperometry (CA) tests. Advanced characterization and in situ, spectral analysis reveal that the extremely disordered atomic structure effectively regulates the geometric and electronic structure of the Pd sites, enhancing active intermediate coverage, facilitating dehydrogenation pathway, and inhibiting the production/adsorption of CO. Furthermore, when employed as the anode catalyst in proton exchange membrane water electrolysis (PEMWE), Net-Pd-HEAA only requires a potential of 1.28V to obtain a current density of 1 A cm-2, and operates stably in a highly corrosive electrolyte for over 100 h.

Parameter Analysis of Anion Exchange Membrane Water Electrolysis System by Numerical Simulation

Anion exchange membrane electrolysis, which combines the advantages of both alkaline electrolysis and proton-exchange membrane electrolysis, is a promising technology to reduce the cost of hydrogen production. The present work focused on the study of the electrochemical phenomena of AEM electrolysis and the investigation of the key factors of the AEM hydrogen production system. The numerical model is established according to electrochemical reactions, polarization phenomena, and the power consumption of the balance of plant components of the system. The effects of operation parameters, including the temperature and hydrogen pressure of the electrolyzer, electrolyte concentration, and hydrogen supply pressure on the energy efficiency are studied. The basic electrochemical phenomena of AEM water electrolysis cells are analyzed by simulations of reversible potential and activation, and ohmic and concentration polarizations. The results reveal that increasing the operating temperature and hydrogen production pressure of the AEM electrolyzer has positive effects on the system’s efficiency. By conducting an optimization analysis of the electrolyzer temperature—which uses the heat energy generated by the electrochemical reaction of the electrolyzer to minimize the power consumption of the electrolyte pump and heater—the AEM system with an electrolyzer operating at 328 K and 30 bar can deliver hydrogen of pressure up to 200 bar under an energy efficiency of 56.4%.

An Analysis of the Conceptual and Functional Factors Affecting the Effectiveness of Proton-Exchange Membrane Water Electrolysis

Hydrogen has the potential to decarbonize the energy and industrial sectors in the future, mainly if it is generated by water electrolysis. The proton-exchange membrane water electrolysis (PEMWE) system is regarded as a propitious technology to produce green hydrogen from water using power supplied by renewable energy sources. It offers many benefits, such as high performance, high proton conductibility, quick response, compact size, and low working temperature. Many conceptual and functional parameters influence the effectiveness of PEM, including temperature, pressure of anode and cathode regions, water content and wideness of the layer, and cathode and anode exchange current density. In addition, the anodic half-reaction (known as the oxygen evolution reaction (OER)) and cathodic half-reaction (known as the hydrogen evolution reaction (HER)) perform an important function in the development of PEMWE. The current study aims to present these parameters and discuss their impacts on the performance of PEM. Also, the PEM efficiency is presented. The different methods used to enhance the scattering of OER electrocatalysts and minimize catalyst loading to minimize the price of PEMWE are also highlighted. Moreover, the alternative noble metals that could be used as electrocatalysts in HER and OER to minimize the cost of PEM are reviewed and presented.

Multifunctional Nanocomposite Polymer‐integrated Ca‐doped CeO2 Electrolyte for Robust and High‐rate All‐solid‐state Sodium‐ion Batteries

AbstractDue to the seamless interfaces between solid polymer electrolytes (SPEs) and electrode materials, SPEs‐based all‐solid‐state sodium‐ion batteries (ASSSIBs) are considered promising energy storage systems. However, the sluggish Na+ transport and uncontrollable Na dendrite propagation still hinder the practical application of SPEs‐based ASSSIBs. Herein, Ca‐doped CeO2 (Ca−CeO2) nanotube framework is synthesized and integrated with poly (ethylene oxide) methyl ether acrylate‐perfluoropolyether copolymer (PEOA‐PFPE), resulting in multifunctional solid nanocomposite electrolytes (namely SNEs, i.e., PEOA‐PFPE/Ca−CeO2). Our investigations demonstrate that the fluorous effect incurred by the fluorine‐containing PEOA‐PFPE and the oxygen vacancy effect induced by the Ca−CeO2 framework could synergistically promote the dissociation of sodium salt, ultimately enhancing the Na+ mobility in SNEs. Besides, the resultant SNEs construct rapid Na+ transport channels and homogenize the Na deposition in SNEs/Na interface, which effectively prevents the Na dendrite growth. Furthermore, the assembled carbon‐coated sodium vanadium phosphate (NVP@C)||PEOA‐PFPE/Ca−CeO2||Na coin cell delivers impressive rate capability of 97.9 mAh g−1 at 2 C and outstanding cycling stability with capacity retention of 84.3 % after 300 cycles at 1 C. This work illustrates that constructing multifunctional SNEs via incorporating functional inorganic frameworks into fluorine‐containing SPEs could be a promising strategy for the commercialization of robust and high‐performance ASSSIBs.

Advanced Eutectogel Electrolyte for High‐Performance and Wide‐Temperature Flexible Zinc‐Air Batteries

AbstractDespite ongoing challenges, achieving further breakthroughs in the development of gel polymer electrolytes with a wide temperature range, excellent liquid retention capability and enhanced anode compatibility in flexible zinc‐air batteries (FZABs) remains a significant objective. This study presents a significant advancement in the development of choline chloride/ethylene glycol‐polyvinyl alcohol (ChCl/EG‐PVA) eutectogel electrolyte, tailored for high‐performance operation across a wide temperature range. Systematic in‐situ and ex‐situ characterizations and theoretical simulations confirm the formation of robust hydrogen bonding and denser polymer cross‐linked networks within the prepared eutectogel, leading to enhanced liquid retention ability (93.7 % after 96 h exposure to air) and ion transport capacity (ionic conductivity of 171.3 mS cm−1). Additionally, the zincophilicity nature of the choline cation in eutectogel effectively suppresses dendrites growth. The assembled FZAB utilizing this eutectogel electrolyte achieves a peak power density of 109.3 mW cm−2 and a cycle life of 90 h. Notably, the power density of FZAB is maintained as high as 38.2 mW cm−2 at −40 °C and 63.2 mW cm−2 at 50 °C, demonstrating its prominent suitability for applications in extreme temperature conditions. The design of eutectogel provides a novel way to achieve the high‐performance FZAB.

Polyvinyl Butyral Solid Electrolyte Film and Its Electrochromic Laminated Safety Glass.

In recent years, the application of electrochromic laminated safety glass has attracted more and more attention, relying on polyvinyl butyral (PVB) solid electrolyte film. Herein, the ionic conductivity (σ) of the PVB film has been improved by a cross-linked structure and blended with LiClO4, which can reach as high as 1.78 × 10-4 S cm-1 at room temperature. In addition, their excellent comprehensive characteristics have been confirmed, such as mechanical strength, high visible light transmittance (>90%), high bond strength (4.2 MPa), and excellent thermal stability. Based on the PVB film above, WO3-laminated electrochromic devices with 5 × 5 cm2 and 10 × 10 cm2 areas are constructed. They can remain stable after 20 000 cycles monitored by cyclic voltammetry curves, indicating the PVB solid polymer electrolyte (PSPE) with a cross-linked structure has the potential commercial viability of large-area electrochromic devices (ECDs).

Advanced Eutectogel Electrolyte for High-Performance and Wide-Temperature Flexible Zinc-Air Batteries.

Despite ongoing challenges, achieving further breakthroughs in the development of gel polymer electrolytes with a wide temperature range, excellent liquid retention capability and enhanced anode compatibility in flexible zinc-air batteries (FZABs) remains a significant objective. This study presents a significant advancement in the development of choline chloride/ethylene glycol-polyvinyl alcohol (ChCl/EG-PVA) eutectogel electrolyte, tailored for high-performance operation across a wide temperature range. Systematic in-situ and ex-situ characterizations and theoretical simulations confirm the formation of robust hydrogen bonding and denser polymer cross-linked networks within the prepared eutectogel, leading to enhanced liquid retention ability (93.7 % after 96 h exposure to air) and ion transport capacity (ionic conductivity of 171.3 mS cm-1). Additionally, the zincophilicity nature of the choline cation in eutectogel effectively suppresses dendrites growth. The assembled FZAB utilizing this eutectogel electrolyte achieves a peak power density of 109.3 mW cm-2 and a cycle life of 90 h. Notably, the power density of FZAB is maintained as high as 38.2 mW cm-2 at -40 °C and 63.2 mW cm-2 at 50 °C, demonstrating its prominent suitability for applications in extreme temperature conditions. The design of eutectogel provides a novel way to achieve the high-performance FZAB.

Composite Gel Polymer Electrolyte for High-Performance Flexible Zinc-Air Batteries.

Enhancing ionic conductivity and electrolyte uptake is of significance for gel polymer electrolytes (GPEs) for flexible zinc-air batteries (FZABs). Herein, a composite mesoporous silica/polyacrylamide (5 wt.% mPAM) GPE is constructed with comparable ionic conductivity to aqueous electrolytes, where the ionic conductivity is up to 337 mS cm-1, and the weight loss after exposing in air 72h is less than 18%, owing to the excellent electrolyte uptake and continuous ion migration network provided by the mesoporous silica fillers. When used as a quasi-solid-electrolyte, the rechargeable FZAB exhibited high electrochemical performance and structural stability, where the peak power density is up to 162.8mW cm-2, and the initial charge-discharge potential gap is as low as 0.62V, resulting in a long lifespan exceeding 110h, showcasing the combination of high durability, cost-effectiveness and easy production for practical applications.