Journal of Power Sources最新文献

Zinc-ion capacitors (ZICs) have garnered significant attention due to their ability to balance energy density and power density. The properties of electrolytes greatly influence the electrochemical performance of ZICs, and the oxidation potential (OP) of electrolytes can be used to determine the most suitable electrolyte for ZICs. However, traditional methods for exploring OP are time-consuming and inefficient, making it difficult to effectively determine the most suitable electrolyte for ZICs. Herein, we propose a machine learning-assisted method that combines deep learning with the traditional machine learning algorithm Gradient Boosting Regression (GBR), which we refer to as DeepGBR. This method can accurately predict the OP of electrolytes even when dealing with complex features and small datasets. Furthermore, with the assistance of deep learning, the accuracy of the predictions improves as the dataset size increases. We further validated the model with four common electrolyte molecules, finding that the predicted results are highly consistent with the theoretical values. The results show that acetonitrile has a high OP, which can achieve high energy density and long-cycle stability when used as an electrolyte solvent for ZICs. This work provides a certain reference for the database modeling strategy of electrolytes for electrochemical energy storage devices.

Developing a self-rechargeable transparent electrochromic energy storage device (EESD) is highly demanding for advancing electrochromic technology and energy harvesting capabilities. In this study, we introduce a room-temperature photo-annealing method to fabricate electrospun titanium oxide (TiO₂) nanofibers, serving as an ion-storage layer (ISL) on the counter electrode. By monitoring the composition and morphology of the precursor before and after ultraviolet/ozone irradiation, we confirm the formation of oxide nanostructures in electrospun TiO₂ nanofibers, which enhances ion transport in the fabricated EESDs. The structural and surface properties of the photo-annealed ISL are comprehensively analyzed using various characterization techniques. Enhanced electrochromic performances are evidenced through cyclic voltammetry, spectroelectrochemical measurements, and charge storage assessments. The Zn-based EESDs with ISL (ISL Zn-EESDs) display rapid electrochemical kinetics, high charge-storing capacities, and long lifespans, with open-circuit potential of 1.2 V, optical contrast of 77 %, discharge capacity of 92 mA h/g, coloration efficiency of 58.63 cm²/C, and 99.9 % efficiency retention up to 250 cycles in both flat and bent states. Furthermore, the practical viability of the ISL Zn-EESDs is demonstrated by powering an LED lamp for several minutes. This approach highlights the potential of ISL Zn-EESDs for developing flexible smart windows, opening up a range of promising applications.

The research on temperature and heat flux during mode switching process of unitized regenerative fuel cells is importance. Thus, in this paper, the local temperature and heat flux are measured during mode switching using self-made thin film sensors, and heat transfer coefficient is also obtained. The results of the experiment exhibit that the temperature and heat flux change significantly during mode switching, and periodically change with periodic mode switching, the heat generation is greater than the heat dissipation inside the cell. During mode switching, the temperature and heat flux are higher in upstream, and the temperature and local heat transfer coefficient increase along main gas flow direction. The fuel cell current density has a great influence on heat transfer when cell mode switches. At different current density, the temperature and heat flux show different changing trend when the cell switches from electrolytic cell mode to the fuel cell mode. These experimental results can provide guidance to make fuel cell run more efficiently in practical application.

Metal-supported solid oxide fuel cells (MS-SOFCs) prepared by plasma spraying exhibit promising potential for scale-up applications, where the key lies in breaking through the challenges of limited lifetime and durability. Although electrochemical impedance spectroscopy (EIS) has been widely used to unfold the complex electrode processes in electrochemical reactions, there are still some concerns concerning the in-depth understanding and scientific evaluation of the degradation mechanism of cell long-term performance. In this study, the contribution of each resistance to the overall performance degradation is separately determined by coupled equivalent circuit model (ECM) based on the deconvolution of recorded EIS data at different DC biases. It is found that the deterioration of cathode surface oxygen exchange and O²⁻ conduction causes more than 64 % of the total resistance increase, followed by the anode charge transfer reaction and gas-phase transport (24.91 %), and then the ohmic resistance (9.73 %). However, the correlation between the output voltage drop of MS-SOFC under load and the gas-phase diffusion resistance gradually increases, indicating a shift in the cell degradation mechanism. Combined with the post-test characterization of the aged cell, it can be inferred that the degradation is mainly attributed to the densification of the anodic microstructure and the cathodic elemental segregation. Additionally, attention should be paid to the effects of the thickening of the metal substrate oxide layer and thermal mismatch on the structural stability of MS-SOFC.

The proton exchange membrane fuel cell (PEMFC) requires an “activation” process to optimize its function to a consistent level. This paper offers a comprehensive exploration of the fundamental principles, activation techniques, and characterization methods involved in the activation process. Initially, existing literature is reviewed to identify activation mechanisms, with a focus on modifying the membrane electrode assembly (MEA) morphology. This includes adjusting factors like catalyst layer porosity, catalyst activity, shape, size, and chain orientation of polymers. Various activation methods are then analyzed, including pre-activation by steam, plasma, acid, or compression. Conditions such as dynamic operation, high pressure/temperature, and supersaturation are found to enhance activation kinetics. For automotive PEMFC stacks, meeting producer-specified rated beginning-of-life (BOL) performance is crucial prior to integration into vehicles. This discussion covers progress in reducing conditioning times, often to 4 h or less, without the need for additional inert gases. It examines techniques for creating oxidizing and reducing conditions through approaches such as cathode starvation, cyclic voltammetry, short circuiting, or switching reactants. The paper also discusses the limitations of traditional activation characterization methods, emphasizing the need for enhanced reproducibility through modern electrochemical characterization, postmortem analysis, and the examination of cell output species.

VS₂ is a potential anode material for lithium-ion batteries (LIBs) due to its advantageous properties. Herein, a novel three-dimensional (3D) VS₂/reduced graphene oxide (rGO) heterostructure (VS₂-rGO) was fabricated by in-situ assembly of caterpillar-like VS₂ nanosheets on rGO. This 3D VS₂-rGO with a well-defined heterojunction interface is engineered to mitigate the volumetric expansion of VS₂ during Li ⁺ intercalation/deintercalation cycles. This optimized design promotes enhanced conductivity across the heterojunction, facilitating efficient electron and ion transport. The VS₂-rGO electrode shows higher reversible capacity and better rate performance (644.02 mA h g⁻¹ at 0.1 A g⁻¹ after 140 cycles, 526.66 mA h g⁻¹ at 2 A g⁻¹) as compared to the pure VS₂ electrode (433.69 mA h g⁻¹ at 0.1 A g⁻¹ after 140 cycles, 63.91 mA h g⁻¹ at 2 A g⁻¹). Ex-situ XRD analysis suggests that the Li ⁺ storage mechanism in the VS₂-rGO electrode involves the initial intercalation, followed by intercalation and conversion. The lower Li ⁺ diffusion barrier within the VS₂-rGO heterojunction (0.183 eV) compared to the VS₂ layers (0.225 eV), as predicted by first-principles calculations, resulting the enhanced Li ⁺ transport kinetics and improved cycling performance of the VS₂-rGO electrode material. This work offers novel perspectives for the influence of heterojunctions on LIBs.

Zinc metal batteries are expected to be the next generation of energy storage devices due to their high safety, but their application is hampered by irreversible hydrogen evolution reaction and surface side reactions of zinc anodes. Here, a zwitterionic hydrogel electrolyte is reported based on polymerization of acrylamide and 1-(3-Sulfopropyl)-2-Vinylpyridinium betaine, and it exhibits the following advantages: the sulfonic acid group of 1-(3-Sulfopropyl)-2-Vinylpyridinium betaine can be preferentially adsorbed on metal Zinc to avoid side reactions and refine the affinity at the zinc-electrolyte interface; and the coordination of the negatively charged sulfonic acid group with Zn²⁺ alters the solvation structure of Zn²⁺, which further improves the restriction ability of side reactions. Consequently, Zn||Zn symmetric batteries can be stabilized for 1, 200 h of plating stripping at 1 mA cm⁻². Zn||Cu batteries exhibit an impressive average coulombic efficiency of 99.8 % over a remarkable span of 1, 800 cycles at a current density of 15 mA cm⁻². Furthermore, the Zn||MnO₂/Carbon nanotube batteries have been cycled more than 2, 000 cycles at a current density of 0.5 A g⁻¹, and the zinc hybrid capacitors for more than 18, 000 cycles at 1 A g⁻¹. And an ionic skin (i-skin) based on acrylamide and 1-(3-Sulfopropyl)-2-Vinylpyridinium betaine of polymer hydrogel electrolyte is assembled and it can stably detect physiological signals.

Flow-through electrolyzer can improve the efficiency of hydrogen production from alkaline water splitting and determining the optimal electrolyte velocity through electrode pores is crucial for reducing energy consumption. In this study, an energy consumption model of flow-through electrolyzer considering mass transfer overpotential (E_mass) has been developed. The model of E_mass due to gas hold-up (ϕ) in the electrolyzer accounts for the density, viscosity, surface tension, linear velocity, and current density. The model-predicted value is in good agreement with the experimental results, which indicated that the increase of velocity effectively reduces ϕ and E_mass. Then, Voltage-Current curve models combining reversible voltage, activation overpotential, ohmic overpotential, and E_mass are developed. Based on this, an energy consumption model, combining both consumption from electrolyzer and pumps, is established to evaluate the overall energy consumption of hydrogen production. It can be calculated the E_mass at 400 mA cm⁻², 6 M KOH, 353 K can be reduced from 0.363 V to 0.048 V if the circulation velocity rises from 0.001 m s⁻¹ to 0.1 m s⁻¹. The model predicts that total energy consumption is 4.36 kWh Nm⁻³ with energy consumption for pump being 0.02 kWh Nm⁻³ at 400 mA cm⁻² and 0.063 m s⁻¹.

Owing to its extremely high theoretical capacity (4200 mAh g⁻¹), silicon (Si) has emerged as a promising candidate for lithium-ion batteries (LIBs) anodes. However, challenges such as a volumetric expansion of up to 300 % and poor electrical conductivity have impeded its application. Here, hollow core-shell Si-PEI@ZIF-67 synthesized via a simple one-pot method utilizing the unique properties of ZIF-67, including its porous nature, high surface area, and well-ordered structure, ZIF-67 coating effectively mitigates the volume expansion of nano-Si during cycles. Hollow core-shell structure can accelerate ion transfer and alleviate volume expansion. Moreover, Co²⁺ enrichment in the coating promotes the formation of a strong cross-linking network with the binder sodium alginate. This interaction not only enhances the adhesion between active material and current collector but also accelerates ion transport. Si-PEI@ZIF-67 composites demonstrate outstanding lithium storage performance in LIBs, achieving a stable capacity of 1134.4 mAh g⁻¹ after 500 cycles at 1000 mA g⁻¹. In addition, the discharge capacity of 828.7 mAh g⁻¹ is maintained after 200 cycles at the high current density of 5000 mA g⁻¹. The innovative synthesis method, utilizing ZIF-67 as a coating for nano-Si and establishing an interconnected network with the binder, offers a novel approach for other anodes.

Owing to its excellent theoretical specific capacity, Sb₂S₃ captures widespread attention in the energy-storage field. However, it still suffers from volume expansion and sluggish electrochemical kinetics. Meanwhile, considering serious pollution and complex chemical preparation processes, stibnite is regarded as “first-hand” materials, displaying enormous energy-storage application potential; however, it is still limited by low-purity and high crystallinity. Herein, stibnite is purified and regenerated through physical chemical and vacuum gas-phase melting strategy to form high-properties stibnite-based electrode materials. Assisted by the introduction of lithium nitrate as an active medium, abundant sites and effective structural traits are formed, effectively promoting the reversibility of electrochemical kinetic processes. Utilized as lithium-ion battery anodes, the as optimized samples have a capacity of approximately 656.8 mAh g⁻¹ with a capacity retention rate of 89.9 % at 0.5 A g⁻¹. Even at 5.0 A g⁻¹, the capacity of 483.3 mAh g⁻¹ could be remained after 100 cycles. Supported by a detailed kinetic analysis, the enhancement of the surface-controlling behavior and the reduction of capacitive resistance are confirmed. Herein, the as-regenerated phase and the introduced oxide-based catalyst are beneficial to alleviate polysulfide shuttling and volume expansion, further accelerating ion/electron transfer behaviors. This work is expected to shed light on strategies to design promising mineral-based anodes for lithium-ion batteries.