UN Sustainable Development Goals 7 and 13. How sustainable are the metals in our journey to clean energy storage?

Affordable, reliable, and clean energy storage should be at the core of our society to enable fair global energy distribution

Recent progress, advances, and future prospects in Na–O2 batteries

An energy storage technology, that uses sustainable and abundant materials such as sodium and oxygen, known as Na-air/O2 battery (NAB), is desirable for our society and is a real alternative to current and dominant technologies such as Li-ion batteries. However, this technology (NAB) still requires more research to overcome some of the main issues that affect the battery components, electrodes, and electrolytes. Important breakthroughs have been published during the last decade to gain deep knowledge into the battery operation towards NAB commercialisation. In this opinion, we cover the most research in the charge and discharge mechanism, as well as the sudden death of NABs reported in the literature. The section on future directions will be a valuable guidance to the research society and the development of the NAB technology

Recent progress, advances, and future prospects in Na–O2 batteries

Recent progress, advances, and future prospects in Na–O2 batterie

Electrodialysis as a Method for LiOH Production: Cell Configurations and Ion-Exchange Membranes

AbstractLithium hydroxide (LiOH) is rapidly becoming the main precursor for layered oxide cathodes used in lithium ion batteries. Current hydrometallurgical method for LiOH production uses substantial amounts of chemicals and creates wastes, leaving behind a negative environmental footprint. Electrodialysis is emerging as a more sustainable technology for LiOH production, effectively eliminating the conventional chemical addition step and its subsequent waste management. Additionally, hydrogen is generated as a by‐product during the electrodialysis process. Various configurations of the electrodialysis cell have been employed to maximize the energy efficiency of the process and the purity of the LiOH product. Nonetheless, this review found that there is a lack of concerted effort in developing ion exchange membranes specific for LiOH production. Current membrane technologies are not tailored to LiOH production, with limited selectivity to lithium in relative to other monovalent cations, as well as relying heavily on harmful perfluoroalkyl (PFA)‐based polymeric membranes. In this review, special attention is given to the state of the art in the testing and development of membranes, i.e., cation and anion exchange membranes, bipolar membranes, as well as novel membranes that are potentially low‐cost, non‐fluorinated, lithium‐selective with high chemical stability and mechanical robustness

Quasi-solid-State Electrolytes for Low-Grade Thermal Energy Harvesting using a Cobalt Redox Couple

Quasi-solid-State Electrolytes for Low-Grade Thermal Energy Harvesting using a Cobalt Redox Coupl

Electrolytes for sodium batteries

This chapter presents an overview of different liquid and solid electrolytes employed for sodium batteries. It covers the basics in more depth and discusses the current status of ionic liquid (IL)-based electrolytes. The chapter outlines the challenges that remain to be solved to enable the realization of sodium batteries based on such electrolytes. Organic liquid electrolytes for sodium batteries typically consist of one or more sodium salts dissolved in one or more organic solvents. Organic ionic plastic crystals, the solid-state analogues of ILs, are emerging solid-state electrolytes that have advantageous properties, similar to ILs. ILs-based electrolytes present some unique properties that endows significant safety enhancements in comparison with conventional organic solvents, mostly related to higher decomposition temperatures. The IL-based electrolytes must also show an economic viability in comparison with conventional organic liquid electrolytes

The effect of solvent on the seebeck coefficient and thermocell performance of cobalt bipyridyl and iron ferri/ferrocyanide redox couples

© 2019 CSIRO. The conversion of thermal energy to electricity using thermoelectrochemical cells (thermocells) is a developing approach to harvesting waste heat. The performance of a thermocell is highly dependent on the solvent used in the electrolyte, but the interplay of the various solvent effects is not yet well understood. Here, using the redox couples [Co(bpy)3][BF4]2/3 (bpy = 2,2′-bipyridyl) and (Et4N)3/(NH4)4Fe(CN)6, which have been designed to allow dissolution in different solvent systems (aqueous, non-aqueous, and mixed solvent), the effect of solvent on the Seebeck coefficient (Se) and cell performance was studied. The highest Se for a cobalt-based redox couple measured thus far is reported. Different trends in the Seebeck coefficients of the two redox couples as a function of the ratio of organic solvent to water were observed. The cobalt redox couple produced a more positive Se in organic solvent than in water, whereas addition of water to organic solvent resulted in a more negative Se for Fe(CN)63-/4-. UV-vis and IR investigations of the redox couples indicate that Se is affected by changes in solvent-ligand interactions in the different solvent systems

Application of a water-soluble cobalt redox couple in free-standing cellulose films for thermal energy harvesting

Thermal energy harvesting using thermoelectrochemical cells (thermocells) is a sustainable method to produce electricity without carbon dioxide emissions. The solvent and redox couple used in the electrolyte play an important role in determining both the safety and performance of thermocells, and development of leak-free electrolytes with high performance is particularly important for transportable devices. Here, the application of aqueous and non-aqueous electrolytes containing the [Co(bpy)]2+/3+ redox couple in both liquid and solid forms was studied. Cellulose was used as an environmentally friendly material for solidification of the different liquid electrolytes. The properties and performance of the new aqueous [Co(bpy)]2+/3+ electrolytes was compared to those containing the Fe(CN)63−/4− couple, both in liquid and quasi-solid state electrolytes. Higher diffusivity for the cobalt redox ions was observed in the aqueous electrolyte compared to the non-aqueous electrolytes, while the Seebeck coefficient of the redox couple, which determines the open circuit voltage of the thermocell, was largest in the organic solvents. No significant effect of solidification on the Seebeck coefficient was observed

A New Quasi-Solid Polymer Electrolyte for Next-Generation Na-O₂ Batteries: Unveiling the Potential of a Polyamide-Polyether System

AbstractA novel quasi‐solid polymer electrolyte (QSPE) composed of polyamide (PA) and polyethylene oxide (PEO), commercially known as Pebax1657, and combined with 1 M sodium bis(trifluoromethanesulfonyl)imide (NaTFSI) in diethylene glycol dimethyl ether (diglyme, DEGDME), has been investigated for sodium–oxygen (Na–O2) batteries. Pebax1657 QSPE exhibits high ionic conductivity (6.57 × 10−4 S cm−1 at room temprerature ‐ RT), an oxidation onset potential of 4.69 V versus Na/Na⁺, and an enhanced Na⁺ transference number (tNa⁺ ≈ 0.40). Structural analysis (Raman spectroscopy, differential scanning calorimetry, X‐ray diffraction, small‐angle X‐ray scattering) confirms reduced PEO crystallinity and formation of orderly nanodomains, facilitating Na⁺ transport. Long‐term galvanostatic cycling in Na|Na symmetrical cells demonstrates stable overpotentials (≈80 mV) at 75 µA cm⁻2 for 210 h, outperforming conventional liquid electrolytes (≈110 h). Pebax1657 QSPE enables higher discharge capacities (2.60 mAh cm⁻2 at 75 µA cm⁻2; 2.11 mAh cm⁻2 at 150 µA cm⁻2) with lower overpotentials (≈0.2 V). It sustains 25 cycles at 75 µA cm⁻2 and 35 cycles at 150 µA cm⁻2 at 0.25 mAh cm⁻2, with a Coulombic Efficiency (CE) of 80–90%. Compared to the state of the art, Pebax1657 QSPE offers improved electrochemical stability, lower overpotentials, and better capacity retention. Its sustainability and versatility make it a strong candidate for Na–O2 batteries and other energy storage applications

Enhanced Dissolution of Metal Oxides in Hydroxylated Solvents – Towards Application in Lithium-Ion Battery Leaching

The recovery of critical metals from spent lithium-ion batteries (LIBs) is rapidly growing. Current methods are energy-intensive and hazardous, while alternative solvent-based strategies require more studies on their ‘green’ character, metal dissolution mechanism and industrial applicability. Herein, we bridged this gap by studying the effect of dilute HCl solutions in hydroxylated solvents to dissolve Co, Ni and Mn oxides. Ethylene glycol emerged consistently as the most effective solvent, dissolving up to four times more Co and Ni oxides than using aqueous acidic media, attributed to improved chloro-complex formation and solvent effects. These effects had a significant contribution compared to acid type and concentration. The highest Co dissolution (0.27 M) was achieved in 0.5 M HCl in 25 % (v/v) glycerol in water, using less acid and a significant amount of water compared to other solvent systems, as well as mild temperatures (40 °C). This solvent was applied to dissolve battery cathode material, achieving 100 % dissolution of Co and Mn and 94 % dissolution of Ni, following what was concluded to be a mixed mechanism. These results offer a simple alternative to current leaching processes, reducing acid consumption, enhancing atomic efficiency, and paving the way for optimized industrial hydrometallurgical processes leaning to ‘greener’ strategies