Conclusions from Round Table Discussion during IUT of ESAT 2021 Electrolyte Thermodynamics challenges - from industrial needs to academic research

Electrolyte thermodynamics is considered one of the most challenging areas of applied thermodynamics. It is an area with a wide range of applications in science and engineering. There are numerous models, both activity coefficients and equations of state, but despite great successes and achievements of many models for several applications there is little consensus on which are the more generally applicable approaches. There are many controversial aspects, both related to models and to fundamentals. Over many years the Working Party of the Thermodynamics and Transport Properties of the European Federation of Chemical Engineering has organized IUT (Industrial Use of Thermodynamics) workshops in different topics of actual interest. The most recent of these IUTs, 5^th in the series, was held (virtually) during the ESAT 2021 conference in Paris. Panellists and participants from both Academia and Industry attended allowing to include views from a very wide spectrum. This manuscript summarizes the most important points from this workshop in terms of status and needs for electrolyte data and models and concludes with some recommendations for the community, which we hope can accelerate future studies in the field. The target of this work is not to present a general account of successes and shortcomings of electrolyte thermodynamic models, rather it is mostly to focus on the expert views of the IUT participants from industry and academia related to the challenges concerning data, models and applications of electrolyte thermodynamics.