Enthalpy of mixing of liquid Ag-Li-Sb alloys Monika Bugajska a , Siegfried Fürtauer b , Hans Flandorfer b , Przemyslaw Fima a, ⁎ a Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta St., 30-059 Krakow, Poland b Department of Inorganic Chemistry - Functional Materials, University of Vienna, Althanstraße 14, 1090 Wien, Austria abstract article info Article history: Received 8 February 2018 Received in revised form 11 July 2018 Accepted 11 August 2018 Available online 11 August 2018 Ag-Li-Sb is a ternary system that has not yet been studied in terms of thermodynamic investigations. The partial and integral enthalpies of mixing of liquid Ag-Li-Sb alloys at 980 K were determined applying drop calorimetry. The investigations were performed along five sections by the addition of lithium to alloys with fixed Ag to Sb molar ratio of 1:1 and 1:4, by the addition of silver to alloys with fixed Li to Sb molar ratio equal to 1:9, 3:7 and 1:1. Experimental data were compared and discussed with Muggianu and Toop extrapolation models. From experimental ternary data the range of liquid at 980 K was deduced. © 2018 Elsevier B.V. All rights reserved. Keywords: Ag-Li-Sb Drop solution calorimetry Enthalpy of mixing Liquid alloys 1. Introduction Currently, lithium-ion batteries are the main source of power used in portable electronics and their specific energy hardly exceeds 250 Wh/kg. Alternative power supply with renewable energy sources like wind and solar energy as well as full-electric vehicles require energy storage sys- tems with high specific energy, energy and power densities. The low weight and high voltage of Li-ion batteries make them promising candi- dates for such applications [1,2]. However, they have to be improved mandatory in respect to their specific energy, energy and power density as well as lifetime and costs [3]. In the most common Li-ion batteries, cathodes are built of layered lithiated metal oxides while anodes are built of layered graphite, which upon lithiation forms LiC 6 [4]. These lithium-ion batteries are characterized by high voltage, high cyclability and reliability, no memory effect and low costs. Their capacity is suffi- cient for low power applications. To make Li-ion batteries suitable for high power applications as men- tioned above all parts of the battery have to be fundamentally improved, especially the electrodes charge capacities and kinetic performance. This is, however, not possible based on same materials which have been hith- erto used. Concerning the anodes, among the most promising new mate- rials are intermetallic compounds. The Li 3 Sb intermetallic compound has a relatively high theoretical capacity (660 mAh/g) [5], but due to drastic volume change upon lithiation and delithiation of Sb such electrodes de- grade after a few charge/discharge cycles. It has been found that alloying of Sb with other elements (either less active or inactive towards Li) limits volume expansion effects on the electrode material by the precipitation of an inactive matrix which buffers the mechanical stress [4]. Vaughey et al. [6] electrochemically studied lithiation of Ag 3 Sb at room temperature, but for a systematic investigation of such processes the knowledge of phase diagrams and thermodynamics is indispensable. Little is known regarding thermodynamics and phase relations in the ternary Ag-Li-Sb system. Bat- teries operate at −20 to 50 °C, however, experimental thermodynamic investigations are hardly practicable in this temperature regime. Never- theless, high temperature investigations of Ag-Li-Sb system can shed some light on this matter and provide the essential data for future ther- modynamic assessment of Ag-Li-Sb system with CALPHAD method and calculation of its phase diagram. Such a thermodynamic assessment al- lows the extrapolation of data down to lower temperatures. Therefore, our aim is to study mixing enthalpies of liquid Ag-Li-Sb alloys. 2. Literature survey According to a literature survey there are no thermodynamic data available for liquid ternary Ag-Li-Sb alloys. Thermodynamic properties of constituent binary alloys were reported earlier, on the other hand. 2.1. Ag-Li system There are only a few sets of thermodynamic data for liquid Ag-Li al- loys. Mixing enthalpy of liquid Ag-Li alloys was obtained calorimetrically by Predel et al. [7] at 1250 K, while Becker et al. [8] studied the activity of Li at 830 K with an electromotive force method (EMF) in the concentra- tion range of 0.435–0.95 mol fraction Li. Debski et al. [9] published a study of the mixing enthalpy of the Ag-Li liquid-alloy based on drop calo- rimetry at two temperatures, 1253 K and 873 K. Their studies were con- ducted over the entire range of lithium concentrations, and do not show any dependence on temperature. The integral enthalpy values from [9] are more negative in the concentration range x(Li) = 0.2–0.8, as Journal of Molecular Liquids 269 (2018) 501–510 ⁎ Corresponding author. E-mail address: p.fima@imim.pl (P. Fima). https://doi.org/10.1016/j.molliq.2018.08.067 0167-7322/© 2018 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Journal of Molecular Liquids journal homepage: www.elsevier.com/locate/molliq