Ionics最新文献

Solid-state electrolytes are gaining attention as safer alternatives to conventional liquid electrolytes in lithium- and sodium-ion batteries, particularly for large-scale applications. Among them, sodium-based systems offer cost and resource advantages. Halide-based solid electrolytes allow compositional tuning via homovalent halide substitution, which has been shown to enhance ionic conductivity in both Li⁺ and Na⁺ systems. Recent studies on NaAlBr₄ suggest that Na⁺ mobility can be improved through halide substitution and non-stoichiometry. However, the effects of Br⁻/I⁻ exchange in sodium aluminum halides remain largely unexplored. This study provides the effects of Br⁻ substitution on the conduction properties of NaAlI₄, particularly for the activation energy for ion conduction. Br⁻ substitution was systematically investigated across the full compositional range. A complete solid solution was confirmed, accompanied by lattice shrinkage with increasing Br⁻ content, reflecting the replacement of larger I⁻ ions with smaller Br⁻ ions. The activation energy for Na⁺ conduction varied with Br⁻ fraction, peaking at Br⁻/I⁻ = 1.0. From the variation in lattice parameters, it was suggested that the NaI6 prism undergoes a pincer-like deformation rather than uniform shrinkage, with the strongest deviation from ideality observed in the Br⁻ 40–70% range. This structural distortion was correlated with increased hopping barriers, likely hindering Na⁺ migration along the a and b axes. Although Br⁻ substitution alone was not favorable for Na⁺ conduction, the introduction of excess Na⁺ significantly enhanced conductivity, reaching 1.5 × 10⁻⁵ S/cm at 303 K. These findings highlight the interplay between halide composition, lattice distortion, and ionic transport, offering insights for the design of high-performance Na⁺ conductors.

Vanadium oxyphosphate (VOPO₄) is a promising cathode material for zinc-ion batteries (ZIBs), but its capacity is critically limited by the irreversible oxidation of electrochemically active V⁴⁺ to inactive V⁵⁺ during cycling. To address this challenge, we introduce 2-hydroxyphosphonoacetic acid (HPAA) as a multifunctional additive for polyacrylamide (PAM) gel electrolyte. Leveraging its reducing properties, HPAA effectively preserves a higher proportion of V⁴⁺ with redox activity during charge/discharge process. X-ray photoelectron spectroscopy (XPS) analysis confirms this interfacial modulation by HPAA, revealing increased concentration of V⁴⁺ and decreased concentration of V⁵⁺ on cycled cathodes, indicating a more reactive surface. Furthermore, HPAA lowers the reaction energy barrier for the V⁴⁺/V⁵⁺ redox couple and mitigates vanadium dissolution, collectively optimizing the reaction kinetics. Electrochemical impedance spectroscopy (EIS) analysis with the equivalent circuit confirms that HPAA reduces ion diffusion resistance, boosting the Zn²⁺ diffusion coefficient to 7.0676 cm² s^− 1. Consequently, the HPAA-modified PAM gel electrolyte enables VOPO₄ cathode delivers a significantly enhanced discharge capacity of 387 mAh g^− 1 at 0.1 A g^− 1 and retains 163 mAh g^− 1 after 100 cycles. This work unveils a novel strategy utilizing organophosphonic reductants to regulate vanadium valence states in cathode interface, providing crucial insights for designing high-capacity ZIBs.

Polyethylene oxide (PEO) is regarded as the most promising candidate for the next generation solid polymer lithium metal batteries (LMBs). However, it suffers from low mechanical strength and limited electrochemical stability window (ESW), which restricts its application in high energy density LMBs. In this work, polycaprolactone (PCL) is chosen as the main matrix to fabricate a blending polymer-based electrolyte with PEO, which shows an improved electrochemical performance with a high lithium ion transference number of 0.65. The improvement can be attributed to the competition between ester and ether groups of different polymer chains, which can both interact with lithium ions to release more free cations. Moreover, the high-voltage resistance of PCL can broaden the electrochemical stability window to 4.8 V of PCL/PEO solid electrolyte to match LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cathode, and its high-temperature resistance ensure a satisfying dimensional stability for the assembled NCM811||Li cell to operate at 55 ℃, with a high initial specific capacity of 210 mAh/g and a retention of 95% within 100 cycles. Compared to other blending systems, the PCL/PEO blend exhibits superior compatibility, mechanical properties, and electrochemical stability, offering a promising strategy for the commercialization of high-voltage, safe, and high-energy-density solid-state lithium metal batteries operable at elevated temperatures.

Hydrogen, a key clean energy carrier, is strategically vital for carbon neutrality and sustainable energy systems. Water electrolysis, a promising hydrogen production method, depends on the HER and OER. Given freshwater scarcity, seawater electrolysis has gained attention due to seawater’s abundance. In transition metal phosphides (TMPs), phosphorus’s high electronegativity facilitates proton capture and lowers hydrogen desorption barriers. Developing phosphide heterostructures with optimized electronic states is crucial for enhancing seawater splitting efficiency. Here, we synthesized FeP₄/CoP heterostructures from CoFe-PBA and FeCo-LDH precursors via hydrothermal and phosphidation methods. The hollow nanobox-structured catalyst exhibits outstanding OER performance in simulated seawater, requiring only 320 mV overpotential for 10 mA·cm⁻² with excellent stability. This work presents a simple heterostructure design strategy to boost seawater electrocatalysis, guiding future catalyst development.

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With the rapid increase in retired lithium iron phosphate (LiFePO₄, LFP) batteries and the rising demand for carbon neutrality, efficient and sustainable recycling of spent LFP cathodes has become a pressing research priority. This review systematically compares three representative recycling approaches—pyrometallurgical, hydrometallurgical, and direct regeneration—highlighting their respective mechanisms, advantages, and limitations. Pyrometallurgy, while industrially mature, suffers from high energy consumption and elemental loss. Hydrometallurgy enables high recovery yields but generates significant chemical waste. In contrast, direct regeneration preserves the cathode structure and offers notable advantages in energy efficiency, environmental impact, and cost-effectiveness. Life cycle assessment results based on the EverBatt model show that direct regeneration significantly reduces greenhouse gas emissions and process costs compared to other methods. Finally, the review outlines current challenges and research directions toward scalable, green, and economically viable LFP recycling technologies.

A gradient thermal reduction approach was employed to facilitate the large-scale production of high-quality, cost-effective reduced graphene oxide (RGO). The RGO was then combined with carbon nanotubes (CNTs) and carbon black (Super-P) to form a ternary conductive additive system for LiFePO₄ (LFP)-based lithium-ion batteries (LIBs). This type of composite significantly enhanced the electrochemical performance of the LIBs. By incorporating RGO along with CNTs and Super-P, a three-dimensional (3D) "point–line–plane" conductive network was successfully constructed. This structure efficiently reduced the charge transfer resistance (Rct = 37.99 Ω) and enhanced the Li⁺ diffusion coefficient (D = 7.78 × 10^–13 cm² s⁻¹). The optimized cathode exhibited remarkable discharge capacity of 163.3 mAh g⁻¹ at 0.1C under room temperature and 95 mAh g⁻¹ at 6C. Moreover, it maintained a high capacity retention rate of 99.6% after 100 cycles at -15 °C and 0.3C. This work provides a practical strategy for utilizing large-scale production of RGO for developing high-performance LIBs.

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Titanium niobate (TiNb₂O₇, TNO) has attracted increasing attention as a next-generation anode material for lithium-ion batteries (LIBs), due to its relatively high working potential, structural stability, and theoretical capacity surpassing that of graphite. However, its low intrinsic electronic conductivity and limited lithium-ion diffusion remain critical challenges that hinder its widespread application. To address these limitations, we employed a morphology-engineering strategy based on surfactant-assisted synthesis using Pluronic F127. TNO samples were prepared via a one-pot solvothermal method with varying concentrations of F127 (2, 5, and 8 wt%), and the influence of morphology on electrochemical performance was systematically investigated. The optimized sample containing 5 wt% F127 exhibited uniformly distributed nanoparticles assembled into hierarchical microspheres. This tailored structure resulted in enhanced electrochemical behavior, delivering a high discharge capacity of 195 mAh/g at 1 C with 90% capacity retention after 200 cycles, and 67 mAh/g at 20 C. Additionally, a comparative life cycle assessment (LCA) revealed that although the use of F127 introduced a slight increase in environmental impact, it significantly improved electrochemical performance, highlighting the trade-off between performance and sustainability. These results demonstrate the effectiveness of F127-assisted morphology control as a scalable, eco-conscious strategy for high-performance LIB anode materials.

Zinc-ion batteries offer environmentally friendly and reliable energy storage alternatives. They may also lower the cost of producing next-generation battery technologies. Transition metal oxide-based materials have large theoretical capacities, are abundant in nature, are inexpensive, and have effective redox reactions, making them promising cathode materials for zinc-ion batteries. V₂O₅ and V₂O₅-based materials are being studied for cathode materials in zinc ion batteries due to their high theoretical capacitance and efficient electrochemical properties. Researchers are exploring doping, composite synthesis, and electrolyte optimization for improving the electrochemical potential of zinc-ion batteries. The functioning of zinc-ion batteries, the possibilities of V₂O₅-based materials as cathodes, certain V₂O₅-based hybrid materials, substantial and continuing studies, and future challenges have been adequately covered in this article.

To achieve better accuracy in SOH and RUL estimation, this paper proposes a hybrid neural network framework based on Nonlinear AutoRegressive with eXogenous inputs (NARX) and bidirectional long short-term memory (BiLSTM). Specifically, firstly, by analyzing the battery characteristic curve, three indirect health indicators (HIs) are extracted: constant voltage charging current, constant current charging voltage, and constant current charging time. In order to reduce the size and noise of the extracted HIs, a stacked autoencoder method is proposed to reduce the size and noise of the extracted HIs, and the correlation between the HIs and capacity is analyzed by using the correlation method. Secondly, a hybrid neural network is proposed to establish the SOH and RUL estimation framework. The NARX model embeds BiLSTM memory, which considers the context information of the sequence in the time expansion model, providing a shorter path for the propagation of gradient information, reducing the long-term dependence on recurrent neural networks. Finally, the proposed model is validated on different datasets, and the experimental results showed that the SOH estimation error is limited to < 2% MAE, and the RUL estimation error is controlled within ± 3 cycles, which has good advantages and estimation ability.

Recycling spent lithium iron phosphate (LiFePO₄) batteries, ubiquitous in electric vehicles and energy storage, is crucial for sustainability. However, the prevalent carbon coating, essential for battery performance, presents significant challenges during recycling processes. The melt growth of LiFePO₄ crystals from a carbon-decorated LiFePO₄ amorphous powder precursor via the Bridgman method was studied. The electrochemical performance of the regenerated LiFePO₄ materials is significantly degraded which should be attributed to the presence of Fe-related defects. The results suggest decarbonization as a necessary step for achieving phase-pure crystalline LiFePO₄ from wasted LiFePO₄ batteries.