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Sodium-ion batteries have emerged as the most promising alternative to lithium-ion batteries due to the advantages of high natural abundance, low cost, environmental friendliness, and retention of charge capacity at low temperatures. However, novel anode and cathode materials need to be developed. In this work, Sandia octahedral molecular sieves – a class of ion exchangers with the general formula, Na2Nb2−xMIVxO6−x(OH)x·H2O (M = Ti, Zr; x = 0.04–0.40) – are introduced as novel anode materials for sodium-ion battery applications. In this study, sodium niobium titanium oxide, Na2Nb1.6Ti0.4O5.6(OH)0.4·H2O (Na-NTO), is prepared by a simple hydrothermal method, followed by exchange of the Na+ ion in the SOMS structure by one of the eleven selected divalent or monovalent cations, after which the electrochemical properties of the ion-exchanged SOMS materials are investigated and compared with those of the unexchanged SOMS material. Exchanging sodium for divalent zinc delivered an enhanced specific capacity (196 mAh g−1 at 10 mA g−1vs. 89 mAh g−1 for Na-NTO) at every current density, whereas exchange for cadmium delivered a high capacity retention of 72% at 50 mA g−1 after 100 cycles. The enhanced electrochemical performance is related to their lower ionic radii (compared to Na+), higher selectivity, optimal pore size and higher Na+-ion diffusion coefficient. While the performances of the materials investigated here are comparatively low, the present work provides an in-depth study of the effect of partial ion-replacement on electrochemical performance.

This study explores strategies to maximize salinity gradient power (SGP) generation using reverse electrodialysis (RED), focusing on key operating parameters under Swedish environmental conditions. Herein, using a full-factorial experimental design, seawater salinity, flow velocities, and water temperature is varied across three levels to assess their impact on SGP output. machine learning methods predict power density (PD), including 1) ensemble learning with decision tree (DT), 2) gaussian process regression (GPR), and 3) artificial neural network (ANN). Fivefold cross-validation confirms the ANN's high accuracy (root mean squared error (RMSE): 1.173%, R2: 99.35%), closely followed by GPR (RMSE: 1.95%, R2: 99.17%). A feature and trend pattern analysis among the input factors reveals sea salinity as the primary influence on PD, with temperature as the secondary contributor. Complementing this, a life cycle assessment examines the environmental impact of RED systems, identifying the Seawater River RED and brine-wastewater treatment plant RED systems as having environmental effects, particularly on ozone layer depletion and freshwater toxicity. Carbon fiber-based (CF) electrodes, especially lignin CF, demonstrate a lower impact, yet concerns remain over key sustainability challenges. These findings highlight SGP's potential as a viable renewable source, highlighting areas for future material selection and system efficiency improvements.

Developing monovalent anion-selective membranes (MAPMs) faces challenges, including the trade-off between flux and selectivity, membrane stability, and cost-effective fabrication. Overcoming these requires advanced material design and scalable techniques. Here, we introduce in situ interfacial polymerization (ISIP) to prepare MAPMs. Base membranes are synthesized via superacid polymerization and modified with anion channels and -NH2 groups. During ISIP, trimesoyl chloride reacts with surface -NH2 groups, forming a partially crosslinked structure with -COOH groups to regulate ion transport via electrostatic interactions. This results in low membrane resistance (4.7 Ω cm2) and selective transport of weakly hydrated ions (Cl−, Br−, NO3−), while strongly hydrated ions (SO42−, F−) face higher barriers. MAPMs demonstrate high performance, achieving a limiting current density (>90 mA cm−2), Cl− flux (1.98 mol m−2 h−1 at 5 mA cm−2), and selectivity (244 for Cl−/SO42−), confirming effective hydration dynamics control and balanced performance. Simulations reveal how charge distribution affects ion migration pathways.

Complete discharge of spent lithium-ion batteries (LIBs) is a crucial step in LIB recycling, with the physical discharge method being particularly noted for its high discharge efficiency and environmental friendliness. However, previous studies and standards have focused on the performances of the discharge methods, neglecting the battery materials changes caused by discharge. Here we demonstrate that although prolonged discharge of spent batteries keeps the voltage around 0 V, an obvious current flow can be still observed, resulting from the dissolution and subsequent deposition of the copper foil. The deposited copper, primarily in the forms of Cu, Cu2O, and CuO, shows a gradient distribution on the surface of the anode and cathode active materials. This copper deposition significantly compromises the electrochemical performance of the discharged battery, with evident deterioration observed in the first charge-discharge capacity, cycling performance, and coulombic efficiency when compared to the original battery. This study provides guidance for the discharge methods and offers new insights into the materials failure mechanisms during discharge of spent batteries.

A biobased anode material for sodium-ion batteries (SIBs) was prepared through the simple pyrolysis of Scotch pine cones (Pinus sylvestris, SPC), followed by a heteroatom doping modification. The resulting nitrogen-doped hard carbon exhibited a high reversible capacity of 273 mA·h·g-1 at a current density of 25 mA·g-1 compared to the undoped material (197 mA·h·g-1). X-ray diffraction analysis shows that the produced hard carbon from the biomass is highly amorphous in nature, and high-resolution transmission electron microscopy images reveal the presence of localized graphite-like structures that are found to be beneficial for the storage and transport of Na+ ions during charging/discharging. Experimental results demonstrated that the increased specific surface area (SBET = 424 m2·g-1), high micropore volume (0.177 cm3·g-1), and expanded interlayer spacing (>3.7 Å) and a high Na+-ion diffusion coefficient (3.08 × 10-16 cm2·s-1) facilitated the diffusion of sodium ions, leading to a high capacity retention of 80% after 250 cycles for the SPC-N material over the undoped one, SPC (71%). This study highlights the potential of low-cost, widely available biobased Scotch pine cones as an alternative anode material to enhance the sustainability of SIB production.

Current lithium-ion battery recycling extracts valuable metals while discarding much of the battery’s leftover value. An emerging strategy called direct battery regeneration upends this model, restoring the battery’s performance without taking it apart — presenting a more efficient, sustainable option for end-of-life batteries.

Elemental extraction from spent lithium-ion batteries (LIBs) is considered the most mature and inevitable recycling route. However, industrial hydrometallurgy (Hydro) and pyrometallurgy (Pyro) strategies necessitate complex processes with high energy and chemical consumption, leading to significant environmental impacts and reduced profitability. Here, a strategy for low-consumption recycling of spent LIBs using the batteries’ intrinsic energy through thermal runaway is presented. Direct thermal runaway heats the battery to promote cathode thermal reduction, thereby changing the thermodynamics and sluggish kinetics of element extraction. Taking LiMn_0.64Ni_0.29Co_0.07O₂ batteries as an example, thermal runaway battery recycling can save at least 37.9% and 55.7%, respectively, in energy and chemical consumption compared to Pyro and Hydro, and can reduce greenhouse gas emissions by 54.6% and 44.5%, respectively. This results in a profit of 1.94 $ kg⁻¹ battery, which is comparatively higher than the 1.14 $ kg⁻¹ for Hydro and 0.79 $ kg⁻¹ for Pyro recovery strategies.

Recently, niobium-based oxides have attracted attention as anode materials for sodium-ion battery (SIB) applications due to their rate and stability performance. However, reports on T-phase Nb2O5 anode materials for SIB applications are rare. In this work, a simple and straightforward solid-state reaction to prepare a T-Nb2O5 anode material using niobic acid, Nb2O5.nH2O, is proposed. Further, the active particles are successfully embedded in a carbon matrix derived from citric acid to enhance the electrochemical performance, with scanning electron microscopy demonstrating improved grain-to-grain contact following carbon coating. As a result, the coated sample (NC-1, mass ratio of 1:1 between niobic acid and citric acid) exhibits a high reversible capacity of 240 mA.h g−1 at a current density of 25 mA g−1, compared to the uncoated sample (178 mA.h. g−1) due to increased surface area and porosity, better grain connectivity, and a more uniform carbon distribution. In addition, the carbon-coated sample displays a high rate capability of 180 mA.h g−1 at 200 mA g−1 and also delivers good cycling stability over 100 cycles with more than 99% Coulombic efficiency. The improved electrochemical performance is attributed to the presence of additional structural defects, enhanced particle contact, large pore volume, and high initial Coulombic efficiency.

Since the invention of the phase inversion technique, substantial efforts have been dedicated to improve polymeric membrane formation, aiming for better control of membrane characteristics, and optimization of membrane structure enabling the preparation of polymeric membranes with tailored properties for specific separation applications. Despite the great efforts that have been made so far in polymeric membrane formation by phase inversion, there are still significant knowledge gaps that merits special attention. In this chapter, our objective is to highlight some of these gaps identified during the edition of this book establishing future research directions.

This study presents the fabrication of double-layer electrospun nanofibrous membranes (DL-ENMs) using polyvinylidene fluoride (PVDF) and polyether sulfone (PES) based polymers with different degrees of hydrophilicity (PES, sulfonated PES, and PES with hydroxyl terminals). A comparative analysis was carried out with single-layer electrospun nanofiber membranes (SL-ENM) with a total thickness of about 375 μm. Using feed solutions, including sodium chloride, sodium nitrate, and simulated nuclear wastewater (SNWW), the performance of DL-ENMs was evaluated for desalination and radionuclide decontamination by direct contact membrane distillation (DCMD) and air gap membrane distillation (AGMD) techniques. The results showed that DL-ENMs, especially those incorporating a sulfonated PES-based hydrophilic layer, exhibited superior permeate fluxes, reaching values of 72.72 kg/m²h and 73.27 kg/m²h in the DCMD using aqueous feed solutions of NaCl and NaNO₃, respectively, and 70.80 kg/m²h and 41.96 kg/m²h using aqueous feed solutions of SNWW in DCMD and AGMD, respectively. Both SL-ENMs and DL-ENMs exhibited high rejection efficiencies and decontamination factors for the feed solutions (>99.9%). In addition, the prepared ENMs were exposed to gamma radiation to evaluate their applicability in real-life applications. The result of irradiation revealed the negative impact of gamma radiation on the fluorine content of PVDF which could be a critical point in using PVDF as a hydrophobic material for decontaminating nuclear wastewater by membrane distillation.