Review—Reference Electrodes in Li-Ion and Next Generation Batteries: Correct Potential Assessment, Applications and Practices

This review provides an accessible analysis of the processes on reference electrodes and their applications in Li-ion and next generation batteries research. It covers fundamentals and definitions as well as specific practical applications and is intended to be comprehensible for researchers in the battery field with diverse backgrounds. It covers fundamental concepts, such as two- and three-electrodes configurations, as well as more complex quasi- or pseudo- reference electrodes. The electrode potential and its dependance on the concentration of species and nature of solvents are explained in detail and supported by relevant examples. The solvent, in particular the cation solvation energy, contribution to the electrode potential is important and a largely unknown issue in most the battery research. This effect can be as high as half a volt for the Li/Li+ couple and we provide concrete examples of the battery systems where this effect must be taken into account. With this review, we aim to provide guidelines for the use and assessment of reference electrodes in the Li-ion and next generation batteries research that are comprehensive and accessible to an audience with a diverse scientific background.

On problem of using copper electrodes to maintain protection against corrosion of steel hulls of ships and vessels

The paper focuses on the reasons for the lack of proper control of the operation of the electrochemical protective systems of sea vessels, such as the absence of convenient technical equipment, primarily the reference electrodes, as well as the imperfection of the silver chloride reference electrode. There is considered the approach to the development of easy-to-use reference electrodes. A standard silver chloride reference electrode was used as the first electrode; experimental electrodes made of a copper wire strand stripped of insulation were used as the second and third electrodes. The experimental vessel is docked in the commercial port of Petropavlovsk-Kamchatsky. The corrosion protection of the ship’s hull was evaluated by measuring the potentials between the metal hull and the reference electrode at a given point. The measurements were performed at a time interval from 06/10/2021 to 06/18/2021, evaluating the control of the hull corrosion protection was made by taking 50 successive measurements, which were entered into the control tables. It has been stated that the results of ship’s hull sacrificial protection control by using experimental copper electrodes from cabling comply with the regulatory requirements. The ship’s crew didn’t have any financial, organizational or technical problems, which could usually arise from the operation of standard silver chloride reference electrodes. It has been inferred that using regulated and non-regulated electrodes in the organization of corrosion control on ships and metal offshore structures is possible.

Formation of lithiated gold and its use for the preparation of reference electrodes — an EQCM study

Lithiated gold wires can be used to build reference electrodes with outstanding potential stabilities over several days and even over the course of one year. These electrodes are well suited for investigations in the context of lithium-ion batteries (LIBs). In this work, a detailed procedure for the preparation of such electrodes with tailored mechanical properties, which can be fitted gastight into electrochemical cells using commercially available fittings, is given. The electrochemical lithiation process is studied using the electrochemical quartz crystal microbalance (EQCM) technique, and the differences in lithiation of wire type and thin film type gold electrodes are discussed. All experiments were carried out with two different electrolytes, namely, a LiPF6 and a lithium bis(trifluoromethane sulfonyl) imide (LiTFSI)-based electrolyte, and we conclude that for a higher lithiation rate and long-term stability, the use of LiTFSI-based electrolyte in the preparation phase is beneficial. The EQCM data provides a better insight in the analysis of film formation processes, like the buildup of the solid electrolyte interphase (SEI) during the lithiation, the rate of deposition of metallic lithium, or additional information on the kinetics of Li-Au alloy formation.

To problem of using aluminum electrodes to maintain corrosion protection of steel hulls of ships and vessels

The article highlights the test results of a non-standard reference electrode made of a stripped of insulation strand of aluminum wiring, which were conducted on board an auxiliary marine vessel PM-15. The potential of the ship’s hull was measured at the same control point using three reference electrodes: silver chloride electrode No. 1; aluminum electrode No. 2; aluminum electrode No. 3. The vessel’s hull potential was measured over five days. All three reference electrodes were used daily. With the help of each electrode, fifty parallel measurements of the potential of the ship’s hull were carried out with a time interval between measurements of 5 seconds. To assess the accuracy of the measurement results, they were processed statistically. The factors that must be taken into account in the development of technologies for manufacturing non-standard reference electrodes are listed: using available inexpensive materials; avoiding expensive equipment in manufacturing the reference electrode; eliminating complex methods of storage of reference electrodes on ships. There has been given a diagram of measuring electrical circuits including the steel hull, a bulwark, a multimeter, a clamping device, switches, a silver chloride reference electrode, aluminum wires, etc. The results of the study can be used on sea-going vessels to organize the control of the protective effect of the hulls of ships and vessels in the absence of standard reference electrodes.