## 1 Introduction  
In the last years, an opportunity has been identified to obtain higher power-generation efficiencies in concentrated solar power (CSP) plants using supercritical CO\({}_{2}\) (sCO\({}_{2}\)) Brayton power cycle. The CSP technology needs to integrate high-temperature storage materials able to work in the range of 550 \({}^{\circ}\)C to 750 \({}^{\circ}\)C [1]. For this purpose, the selection of high-temperature molten salt chemistry is needed and due to their low cost and high decomposition temperature, molten chlorides have been proposed as a feasible option. However, these molten salts introduce important drawbacks related to their very corrosive nature on typical containment materials. According to [PERSON] et al. [1], the cost for the chloride salt system is dominated by the cost of the material to contain the storage material hot salt tank (70%) due to the expense and size of this tank. In this case, the cold tank would be built using austenitic stainless steel since the operating temperature for this tank would be 520 \({}^{\circ}\)C. This cost simulation was carried out using Haynes 230 alloy in the hot tank and AISI 347 in the cold storage tank. It is clear that a corrosion mitigation strategy is necessary to use low-cost alloys in the CSP storage tanks. With this aim, cathodic protection has been proposed in the literature [2, 3] to mitigate corrosion of alloys in molten salts, using a sacrificial metal that more easily \"corrodes\" is used to prevent corrosion of the alloy or its components. It was shown that the major corrosion mechanism of alloys in molten salts is the selective oxidation of chromium [4]. It usually occurs at the grain boundaries [5; 6]. Such experimental observation is confirmed by electrochemical impedance spectroscopy (EIS) measurement showing a phase angle no higher than 45 \({}^{\circ}\)C which indicates that the corrosion of alloys in molten salts has fast reaction kinetics and it is usually mass-transfer limited. It was shown that Cr\({}^{3+}\) is less thermodynamically stable than the cations in the molten MgCl\({}_{2}\)-KCl mixture (i.e., Mg\({}^{2+}\) and K\({}^{+}\)) such that Cr in the alloy will not react with Mg\({}^{2+}\) and/or K\({}^{+}\) to form Cr\({}^{3+}\)[7; 8]. However, Cr\({}^{2+}\) is more thermodynamically stable, which means that Cr in the alloy tends to react, forming Cr\({}^{2+}\). The oxidation of Cr to form Cr\({}^{2+}\) accounts for the major corrosion mechanism of Cr-containing alloys. In this case, some authors [2; 9] have proposed the addition of Mg metal into the chloride molten salt mixture, since the reduction potential of the alloy components can be modified, obtaining that the main anodic current belongs to the oxidation of this metal, avoiding the oxidation of the target alloy. The corrosion rates of Haynes 230, Haynes 163, and Incoloy 800H were experimentally obtained as a function of wt.% of Mg added (from 0% to 1.15%). In all three cases, the corrosion rates were significantly reduced and the results from experiments and modeling agreed very well. Specifically, the corrosion rate of Haynes 230 at 850 \({}^{\circ}\)C was reduced to less than 15 \(\mu\)m/y with 1.15 wt.% Mg addition compared to the baseline test without Mg addition. A key effect of this behavior is the formation of magnesium oxide (MgO) on the cathode, which can be related to the electrode passivation, obtaining a lower electrolysis current [2]. Corrosion products formed in Mg metal can introduce a new set of impurities in the molten salt, affecting the thermal properties of this material so the proposal of new cathodic elements needs to be addressed. In this research, a first approach of a new cathodic element (Al metal) is proposed in order to mitigate corrosion. Al metal presents a reduction potential voltage (Al\(\rightarrow\)Al\({}^{3+}\)) of \(-\)1.662V, acting as an anode in contact with the common elements present in superalloys Ni\(\rightarrow\)Ni\({}^{2+}\) (1.59 V) or Cr\(\rightarrow\)Cr\({}^{2+}\) (1.33 V).