## 1 Introduction  
Thermal energy storage (TES) is a key tool in the different systems for generation of thermal solar energy [1], thereby providing greater flexibility, dispatchability, and reliability to the electrical system. The easy integration of TES makes concentrating solar power (CSP) dispatchable and unique among all other renewable energy-generating alternatives [2]. A typical TES system is based on sensible heat, which consists of heating a chemical compound and storing it at a high temperature, in order to pass to a common cycle of electricity generation. The viability of solar energy storage technologies will depend on the improvement of different variables, such as temperature, corrosion, materials, operating conditions, among others [1; 2; 3; 4]. One of the great challenges for TES in the framework of the new forms of solar thermal energy generation will be linked to the increase in the temperature of the working fluid in the ranges of 550-750 \({}^{\circ}\)C [5]. Therefore, one of the most important lines of research in this sense is related to TES materials, and the behaviour of heat transfer fluids (HTF) for different applications of TES systems [6] at high temperature. HTF can be found in different conditions of use and application in concentrated solar power (CSP) plants [7]. One of them is molten salts, which have excellent operating and working conditions allowing them to store energy. Solar thermal plants have been operating under a thermal storage system based on a binary mixture composed of 60 wt.% NaNO\({}_{3}\)-40 wt.% KNO\({}_{3}\) (solar salt), which has allowed the construction of several commercial plants that can store up to 15 h of energy [8]. [PERSON] et al. [9] have proposed an eutectic ternary nitrate salt with a composition of 30 wt.% LiNO\({}_{3}\)-13 wt.% NaNO\({}_{3}\)-57 wt.% KNO\({}_{3}\), commonly referred to as (LiNaK)NO\({}_{3}\), as a candidate nitrate salt. The use of (LiNaK)NO\({}_{3}\) enables an increase in the operating temperature of commercial CSP to 550 \({}^{\circ}\)C [10]. On the other hand, it also shows us that the addition of lithium nitrate LiNO\({}_{3}\) in the ternary eutectic mixture (LiNaK)NO\({}_{3}\), could be one of the most promising solar thermal storage materials due to its excellent thermal properties where, for example, the heating capacity of this mixture is between 14% and 21% more than the commercial solar salt. One of the main issues involved with the use of molten salts is that the corrosion produced in the materials used at high temperatures for solar applications and corrosion mitigation strategies must be applied in order to reduce the degradation of containment materials, providing a lifetime for CSP plants of 30 years or more. [PERSON] and [PERSON] [11] showed the effect of corrosion in solar salt (KNa)NO\({}_{3}\) according to the loss of mass for three different stainless steels, 316, 316 L, and 304, at 5000 h of exposure and 565 \({}^{\circ}\)C, obtaining excellent corrosion resistance results for the materials mentioned; it also means that the corrosion products identified by an optical microscope correspond to oxide layers, which are found from the outer surface to the substrate mainly composed of Fe\({}_{2}\)O\({}_{3}\) and (FeCr)\({}_{3}\)O\({}_{4}\). [PERSON] et.al [10] examined the corrosion behaviour of various steels with different amounts of chromium when exposed to LiNO\({}_{3}\)-NaNO\({}_{3}\)-KNO\({}_{3}\) eutectic salt melt at 550 \({}^{\circ}\)C. In addition, this article shows the effects of increased mass on steels with different chromium contents, such as SB450 (0.2% Cr), T22 (2.25 Cr-1 Mo), T5 (5 Cr-0.5 Mo), T9 (9 Cr-1 Mo) and X20 (12 Cr-1 Mo), when exposed to a mixture of (LiNaK)NO\({}_{3}\) ternary salt at 550 \({}^{\circ}\)C. These tests showed that a higher chromium content lead to the formation of (FeCr)\({}_{3}\)O\({}_{4}\) in steels, blocking the external diffusion of iron from the steel substrate.