Ternary Carbonate Research Articles

Experimental enhancement study of thermophysical properties of ternary carbonate phase change material with multi-dimensional nanoparticles

Carbonates have great application potential as heat transfer and thermal energy storage media in the development of future phase change materials. This paper gives thermophysical properties enhancement study on ternary carbonates in liquid state by adding aluminum oxide nanoparticles, multi-walled carbon nanotubes, graphene nanosheets, and experimentally evaluate the performance strengthen ability of multi-dimensional nanoparticles. The thermal diffusivities and specific heats of the prepared samples by the water solution method are determined using the laser flash technique and the differential scanning calorimetry at liquid state, respectively. A thermogravimetric analyzer is deployed for evaluate the high-temperature thermal stability of the composite ternary carbonates. Scanning electron microscopy and Fourier transform infrared spectroscopy techniques are utilized to examine the surface morphologies and chemical structures of the samples. The results indicate that there is a cooperative reinforcement impact on the thermophysical properties of ternary carbonate by utilizing zero-dimensional Al2O3 nanoparticles and two-dimensional graphene nanosheets, with a maximum improvement of 56.7 % for thermal conductivity, and 10.3 % for specific heat, which is apparently larger than adding any single nanoparticle. The composites exhibit superior thermal cycling stability after low-high temperature experiment, and samples can maintain thermal stability until 700 °C in the thermogravimetric analysis.

Hydrogen-Rich Syngas Production in a Ce0.9Zr0.05Y0.05O2−δ/Ag and Molten Carbonates Membrane Reactor

This study proposes a new dense membrane for selectively separating CO2 and O2 at high temperatures and simultaneously producing syngas. The membrane consists of a cermet-type material infiltrated with a ternary carbonate phase. Initially, the co-doped ceria of composition Ce0.9Zr0.05Y0.05O2−δ (CZY) was synthesized by using the conventional solid-state reaction method. Then, the ceramic was mixed with commercial silver powders using a ball milling process and subsequently uniaxially pressed and sintered to form the disk-shaped cermet. The dense membrane was finally formed via the infiltration of molten salts into the porous cermet supports. At high temperatures (700–850 °C), the membranes exhibit CO2/N2 and O2/N2 permselectivity and a high permeation flux under different CO2 concentrations in the feed and sweeping gas flow rates. The observed permeation properties make its use viable for CO2 valorization via the oxy-CO2 reforming of methane, wherein both CO2 and O2 permeated gases were effectively utilized to produce hydrogen-rich syngas (H2 + CO) through a catalytic membrane reactor arrangement at different temperatures ranging from 700 to 850 °C. The effect of the ceramic filler in the cermet is discussed, and continuous permeation testing, up to 115 h, demonstrated the membrane’s superior chemical and thermal stability by confirming the absence of any chemical interaction between the material and the carbonates as well as the absence of significant sintering concerns with the pure silver.

Corrosion of Commercial Alloys in Ternary Carbonate Melt at 700 and 750 °C -Role of LiFeO2 Formation

Corrosion of Commercial Alloys in Ternary Carbonate Melt at 700 and 750 °C -Role of LiFeO2 Formation

Dynamic Corrosion of Carbonate Salt for 3rd Generation CSP Plants

Eutectic ternary carbonate salt is one of the candidates for 3rd generation concentrated solar power (CSP) plants. Gen3 CSP targets higher operation temperatures, which strengthens the corrosivity issues associated to molten salts. Although there are corrosion studies for this carbonate salt in static conditions, the effect of salt flow is not fully understood. In this work, corrosion experiments under static and dynamic conditions are compared for SS310 subjected to ternary carbonate salt at 600ºC.
 The corrosion layer formed during static and dynamic tests were completely characterized by means of SEM-EDX and XRD (surface and cross-section). The corrosion products deposited in the salt during the experiment were analyzed by ICP-OES.
 The tests performed under dynamic conditions demonstrated an increase spallation of the corrosion layer. This spallation produced a thinner scale and exposed the Cr containing phase to the molten salt, fostering its dissolution. These results confirmed the significant effect of dynamic conditions on the corrosivity of eutectic ternary carbonate salt and the importance of assessing them in the design of 3rd generation CSP plants.

Theoretical prediction and experiment study on the thermo-physical properties of ternary carbonate for energy storage

This study calculated the optimal formula (sample A) of ternary carbonate based melting salt using a phase diagram firstly and other four sets of ternary carbonates with different ratios were prepared by changing the content of sodium carbonate and lithium carbonate. The results showed that sample A had better comprehensive thermophysical properties, the melting point, phase change enthalpy, upper limit temperature of thermal stability and stability were the optimal. Whose melting point and phase change enthalpy were 395.57 °C and 322.06 J/g, respectively. The specific heat capacity in the solid phase (330–380 °C) enhanced slightly from 1.38 J/(g·K) to 1.84 J/(g·K) with the increase of temperature, while in the liquid phase, the specific heat capacity was maintained at 1.5 J/(g·K). The ternary carbonate only underwent simple physical mixing without chemical reactions, the decomposition temperature and thermal conductivity of sample A were 885.73 °C and 1.325 W/(m·K), respectively. The ternary carbonates exhibited good thermal stability when continuously heating and heating-cooling cycles.

Optimal pre-treatment of a Ni-11Fe-10Cu anode for efficient molten salt electrolysis of carbon dioxide: Toward net-zero emission manufacturing

Molten salt electrolysis offers an attractive pathway to net-zero emission manufacturing, including the electrolysis of carbon dioxide to generate high value carbon materials. This is only possible with the development of an anode material which is active towards oxygen evolution at elevated temperatures and stable within the melt. Here, it is shown that optimal pre-treatment of a Ni-11Fe-10Cu alloy includes formation of an active oxide layer which incorporates the molten salt. The molten ternary carbonate electrolyte (Li-Na-K CO3) is investigated at 600 °C and pre-oxidation conditions considered include chemical oxidation of the alloy surface under air, and electrochemical oxidation of the surface below that of oxygen evolution, at the onset of metal oxide formation. It was seen that chemical oxidation forms oxides more likely to destabilise the electrode surface when subsequently exposed to the carbonate salt. The unmodified electrode was also significantly corroded due to the fast rate of surface oxidation when stepped to oxygen evolution potentials. Extended (5 h) electrochemical metal oxide formation also causes a build-up of a reactive sub-surface nickel oxide rich layer during pre-treatment, however short-term pre-treatment (1 h) was seen to have the best outcome in terms of both stability and oxygen evolution activity. This is attributed to the formation of a stable LiFeO2 film at the Ni-11Fe-10Cu alloy surface which is highly active towards oxygen evolution. Understanding the interaction between the electrode surface and molten salt chemically and electrochemically under varied polarisation, as carried out here, is crucial to allow progression of this technology for application to carbon capture and other low emission manufacturing approaches.

The conversion of organic sulfur and strontium into inorganic compounds during the molten salt oxidation of mixed resin

Molten salt oxidation (MSO) has the ability to capture sulfur and metal ions from radioactive mixed resin (MR). Nevertheless, the chemical conversion of sulfur (S) and strontium (Sr) in molten carbonate remains to be further investigated. Herein, MR doped with Sr2+ (Sr-MR) was used to replace spent mix resin containing radioactive 90Sr. The oxidation behaviors of MR and Sr-MR in ternary carbonate (Li2CO3-Na2CO3-K2CO3) were comparatively studied. Sr2+ could react with sulfur-containing species to form corresponding compounds in addition to the adsorption of SO2 by molten carbonate. The content of SO2 drops to 0 ppm at 800 °C, which indicates that the complete decomposition of sulfur-containing structures in Sr-MR and the efficient adsorption of SO2 by molten carbonate. Besides, Sr2+ could significantly promote the removal of organic sulfur, and the existence forms of strontium in molten salt are strontium sulfide (SrS, 350 °C), strontium oxide (SrO, 450 °C) and strontium carbonate (SrCO3, ≥ 550 °C). The presence of quaternary ammonium group (-N+(CH3)3) in Sr-MR indirectly stimulated the formation of sulfates from sulfur-containing compounds. The residual amounts of S and C in Sr-MR decreased to 1.44 % and 6.89 % at 650 °C, which were lower than that of pure MR under the same conditions. The proposed MSO system had excellent retention effects of Sr (98.51 %) and S (47.66 %) at 800 °C for 2.0 h, which provides a new perspective on the disposal of organic wastes containing sulfur radioactive metal ions.

Nanoadditives induced enhancement of thermal energy storage properties of molten salt: Insights from experiments and molecular dynamics simulations

Current concentrated solar power (CSP) plants use molten salts as heat storage and heat transfer medium. The thermal property enhancement of molten salts can increase the efficiency and lower the investment cost of CSP plants. In this study, the experiments and molecular dynamics (MD) simulations were employed to investigate the effect of doping Al2O3, SiO2 nanoparticles or multi-walled carbon nanotubes (MWCNTs) on the specific heat capacity (SHC) of ternary carbonate salt. The results show that the SHC of molten salt can be enhanced by adding nanoadditives. The addition of MWCNTs has the largest SHC enhancement in both solid and liquid states. Based on MD simulations, the radial distribution functions, number density distribution and vibrational density of states were further analyzed to reveal the effect of nanoadditive, base salt and interface thermal resistance between them on SHC at different temperatures. It is found that the nanoadditive agglomeration, the ion spacing of base salt, and the thermal resistance between base salt and nanoadditive is independent on temperature and cannot result in the enhanced SHC of liquid nanocomposites. Moreover, the thickness of interfacial layer changes with temperature. The thicker interfacial layer leads to the higher SHC of liquid nanocomposites. The interfacial layer also has a decisive influence on SHC of solid nanocomposites. The scanning electron microscopy images show that the layered, needle-like, and network-like interfacial layers are observed in Al2O3, SiO2 and MWCNT nanocomposites, respectively. The present findings are helpful to understand the mechanisms governing thermal energy storage, and provide guidelines for the performance optimization of molten salt based nanocomposites.

Laser-texturing of stainless steel as a corrosion mitigation strategy for high-temperature molten salts applications under dynamic conditions

Molten salts are utilized in a wide range of applications including nuclear, fuel cells, Carnot batteries, and Concentrated Solar Power (CSP). In order to enhance the profitability of next-generation CSP plants, increasing their efficiency is imperative. Ternary carbonate salts are capable of elevating the maximum CSP operating temperature, which results in improved power generation efficiency. However, higher temperatures lead to accelerated corrosion and more severe conditions for structural materials. In this study, nanosecond laser micromachining is investigated as a potential corrosion mitigation technique for molten carbonate salts in dynamic conditions. SS310 samples with laser-induced surface textures are subjected to the flow of molten Li2CO3–K2CO3–Na2CO3 at 600 °C for a period of 600 h. Laser treatment significantly impedes corrosion in SS310, as untreated samples display pitting and scaling, while minimal surface changes are noted on treated samples. Cross-sectional analysis of the samples reveals considerable peeling in the untreated samples and a 45% increase in the corrosion rate compared to the treated samples. The concentrations of Cr and Mg in the salt (determined through ICP analysis) are found to be twofold and fourfold higher than those in treated samples. Laser treatment renders Cr and Mg less accessible to the salt ions, particularly Li, which results in improved corrosion resistance.

Study on molten salt oxidation process of simulated Co doped cation exchange resins

Cation exchange resins (CERs) are widely applied to purify waste liquids generated during the operation of nuclear reactors. The radioactive nuclides 60Co and 58Co are important corrosion activation products in reactor cooling water. In this study, the simulated Co doped CERs were oxidized with ternary carbonate. According to the thermogravimetric analysis (TG), the decomposition of Co doped CERs includes three processes: 1. Elimination of the osmotic water; 2. Pyrolysis of sulfonic acid group; 3. Destruction of styrene–divinylbenzene copolymer. The X-Ray Diffraction (XRD) patterns indicate that sulfur mainly exists in the form of sulfate in waste salt. The Co2+ undergoes the path of CoS2 → Co3O4 with the increase of temperature and the transition point is 650 °C. Combined with Fourier Transform Infrared Spectrometer (FT-IR) spectra and X-ray Photoelectron Spectroscopy (XPS) analysis, sulfonic acid groups begin to decompose at 350 °C. During the molten salt oxidation process, most of the sulfur in sulfonic acid groups is entrapped by carbonate as the form of sulfate, and a little of which remains as sulfone group, sulfoxide group and sulfur bridge in residue. When the resins are oxidized at 800 °C, the retention rate of Co2+ is 97.3%, indicating that the molten salt oxidation can effectively remain Co2+ and convert it into a more stable substance.

Efficient fixation of Co2+ and organic sulfur from cation exchange resins into CaO enhanced molten Li2CO3-Na2CO3-K2CO3 system

The radioactive spent resins produced by the nuclear power plant contain a certain amount of 60Co. These spent resins are easy to generate volatile substances during the heat treatment process, resulting in the leakage of radionuclide. The molten salt oxidation (MSO) can effectively prevent the volatilization of Co, and can facilitate the removal of sulfur exists in the resins. In this work, ternary carbonate (Li2CO3-Na2CO3-K2CO3) was used as molten salt system, and CaO was used as a sulfur pollutant capture agent. The non-radioactive CoCl2 served as simulate radioisotopes, and the Co2+ doped cation exchange resins (Co-CERs) were obtained by the ion exchange method. The introduction of Co2+ promoted the further oxidation of the thermally stable structure SC, and the harmful gases SO2 and H2S generated during the MSO process were effectively absorbed by carbonate with the participation of CaO. The retention rate of S could reach 87.79 % with the addition of CaO at 800 °C, which was 1.81 % higher than that without CaO. The test results of X-ray diffraction (XRD), scanning electron microscope (SEM) and inductively coupled plasma mass spectrometry (ICP-MS) confirmed that the addition of CaO promoted the formation of sulfide and thermally stable CoSO4. The retention rate of Co2+ in waste salt reached 97.36 % at 800 °C. The CaO enhanced molten carbonate system can realize the efficient treatment of Co-CERs and possess potential applications on organic contaminant treatment.

Influence of oxygen equivalent on molten salt oxidation efficiency of mixed resin in Li2CO3-Na2CO3-K2CO3 melt

The disposal of spent radioactive ion exchange resin generated during the operation of nuclear facilities has always been a conundrum. The molten salt oxidation (MSO) for the treatment of mixed resin (MR) shows obvious superiority. In this work, ternary carbonate (Li2CO3-Na2CO3-K2CO3) and MR was used as the molten salt system and the oxidation target, respectively. The oxidation behavior of MR was analyzed by varying the temperature and oxygen equivalent during the MSO process. By studying the effect of different oxygen equivalents on the oxidation efficiency, the oxygen equivalent of 125% could make the oxidation efficiency of MR reach 99.99% at 800 °C. The composition of C, N and S containing exhaust gas produced through MSO process of MR with temperature were almost consistent with the simulation results. The exhaust gas was successfully adsorbed by molten carbonate to produce nitrate and sulfur compounds. The carbonate has good absorption to harmful gases such as SO2, CO, NO, etc. The content of SO2 from the highest 0.32% to 0, and 71.23% of sulfur in MR was trapped by molten carbonate as the form of sulfate. This work has important implications for reducing the potential harm of radioactive waste resin to the environment.

Laser-induced carbonization of stainless steel as a corrosion mitigation strategy for high-temperature molten salts applications

New heat transfer fluids are necessary to shift the operation temperature of concentrating solar power plants (CSP) to higher temperatures. Ternary carbonate salts (Li2CO3-K2CO3-Na2CO3) are a promising candidate. However, higher temperature translates to harsher operating conditions for CSP structural components as corrosion is more prevalent. In this work, we explore, for the first time, the use of laser micro-machining technology as a surface modification method to inhibit corrosion of CSP structural materials by molten salts. The corrosion behaviour of SS310 in molten ternary carbonate salt is investigated through static immersion for 600 h. Nanosecond laser treatment results in the adhesion of organic groups in the form of hydrocarbons. These then decompose into carbon and contribute to corrosion inhibition through carbonization and the formation of carbide layers. This is confirmed by the reduced diffusion of Li + ions in the SS310, the formation of denser corrosion products and the protection of chromium oxide layers.

Experimental study on heat storage and corrosion properties of ternary carbonate salt-based ZnO nanofluids for solar thermal energy storage

Experimental study on heat storage and corrosion properties of ternary carbonate salt-based ZnO nanofluids for solar thermal energy storage

Understanding Mechanisms of Ethylene Carbonate Gassing and Gas-Reducing Additives Using Isotopically Labeled Solvents

Gas generation during Li-ion battery operation remains a problem that can affect both safety and operational lifetime of the battery. Electrolyte solvents are a key source of gas generation1 and while gas-reducing additives have been identified, the underlying mechanisms require more study to fully understand the role between solvent structure and gas generation. Understanding of these gassing mechanisms can lead to optimized electrolyte systems with reduced gassing for the next generation of Li-ion batteries. Previous studies in the literature2 have detailed the use of 13C-labeled EC and DEC to identify the proportions of CO2 and CO that are derived from solvent sources, which in turn can help inform mechanistic understanding on gas generation in Li-Ion Batteries.As previously studied by Silatronix®, electrolytes containing organosilicon (OS) materials show significantly reduced gas generation during high temperature storage and cycling in pouch cells primarily through CO2 reduction.3 Studies utilizing simple carbonate blends indicated that EC was the primary source of CO2; therefore, it was hypothesized that OS materials reduce gassing by preventing EC decomposition during high temperature testing. In this work, 13C-labeling was used to identify the sources of gas species in ternary carbonate electrolytes after both first charge (SEI formation4) and high temperature storage (extended aging) to allow the effects of electrolyte additives gas reduction to be elucidated.Gas component analysis was performed using a calibrated GC-MS, providing identification and quantification of each gas species (labeled and unlabeled). These data give insight into how the labeled carbonate solvent may decompose into the observed gas phase products during the first charge (i.e., during SEI layer formation) and high temperature storage. Ethylene carbonate (EC) is found to be the primary source of ethylene generation, as well as a significant source of CO2 and CO. With the addition of OS, the most notable effect is that the previously seen reduction in all gas components is due to not only reduction of EC-related sources, but reduction in non-EC gas sources as well. 1 Rowden, B.; Garcia-Araez, N., A Review of Gas Evolution in Lithium-Ion Batteries. Energy Rep. 2020, 6, 10-18. 2Onuki, M.; Kinoshita, S.; Sakata, Y.; Yanagidate, M.; Otake, Y.; Ue, M.; Deguchi, M., Identification of the Source of Evolved Gas in Li-Ion Batteries using 13C-labeled Solvents. Journal of the Electrochemical Society 2008, 155, A794. 3 Guillot, S.L.; Usrey, M.; Peña-Hueso, A.; Kerber, B.; Zhou, L.; Du, P.; Johnson, T., Reduced Gassing In Lithium Ion Batteries With Organosilicon Additives. Journal of the Electrochemical Society 2021, 168, 030533. 4 Ktristiina Heiskanen, S.; Kim, J.; Lucht, B., Generation and Evolution of the Solid Electroyte Interphase of Li-Ion Batteries. Joule 2019, Volume 3 Issue 10, 2322.

Effect of dynamic conditions on high-temperature corrosion of ternary carbonate salt for thermal energy storage applications

Li2CO3–Na2CO3–K2CO3 salt is one of the candidates for 3rd generation concentrated solar power (CSP) plants, aiming to increase the operational temperature. This rise of temperature significantly increases the corrosion issue of molten salts. However, there is a lack of studies focused on the effect of salt flow on the corrosion kinetic for this ternary carbonate salt. In this work, corrosion experiments under static and dynamic conditions are compared for SS310 subjected to ternary carbonate salt at 600 °C. A complete characterization of the corrosion layer, surface and cross-section, was carried out by means of SEM-EDX and XRD, while the molten salts after the corrosion tests were analysed by ICP-OES and XPS. The dynamic experiment exhibited an enlarged spallation of the corrosion layer, leading to a thinner and less homogeneous scale. This feature exposed the chromium containing phase and considerably increased the extent of its dissolution into the salt. The obtained results remark that the detrimental effect of dynamic conditions on the corrosivity of molten carbonate salt cannot be neglected and must be taken into account in the design of 3rd generation CSP plants.

New nickel-rich ternary carbonate hydroxide two-dimensional porous sheets for high-performance aqueous asymmetric supercapattery

Transition metal carbonate hydroxides (M−CHs) are promising candidates for electrode materials in supercapattery, due to their low-cost preparation and high-energy features. However, they also suffer from ionic kinetics bottlenecks without efficient morphological design. Tailoring the chemical compositions and nanostructures of electrode materials to realize high performance is significant for meeting the current demand for electrical energy storage devices. Therefore, we present a simple hydrothermal method for constructing better electrochemically active M−CHs with ternary metal components and hierarchical nanostructures that are assembled by interwoven nanosheets. Benefiting from higher contents of Ni species and superior two-dimensional/three-dimensional (2D/3D) pore structures, the fabricated cobalt-nickel-zinc carbonate hydroxides with Co/Ni/Zn molar ratios of 2:3:1 (CoNiZn-231) delivered the best specific capacity of 1130.8 C g−1 at 1 A g−1, decent rate performance (67.2% in 1–10 A g−1), and excellent cycling performance (92.6% over 10,000 cycles) in comparison with the majority of mono/bimetallic materials. Then, an alkaline hybrid (CoNiZn-231//activated carbon (AC)) device is developed, which shows a high energy density of 31.62 Wh kg−1 at a power density of 646 W kg−1 and an excellent capacity retention of 99.27% after 10,000 cycles. Herein, the rational design of trimetallic compositions and hierarchical structures of carbonate hydroxides is described, which provides good choices for the synthesis of high-performance electrode materials in electrochemical energy storage applications.

Полевая электронная спектроскопия оксидных катодов

The results of studying the bulk and surface electronic structure of a graphite-oxide field cathode and an oxide thermal cathode using a cylindrical electrostatic dispersive energy analyzer are presented. Oxides based on ternary carbonate of alkaline earth metals were used. The energy spectra of electrons in the auto- and thermal automodes are obtained, and the possibility of studying the energy electronic band structure of an oxide thermal cathode by the method of field electron spectroscopy is shown.

Temperature effect and alloying elements impact on the corrosion behaviour of the alloys exposed to molten carbonate environments for CSP application

This investigation assesses the effect of the alloy composition and temperature in the corrosivity of the ternary carbonate eutectic, 32% Li2CO3, 33% Na2CO3, 35% K2CO3. To this end, an iron-based alloy, coded as 51Fe-24Cr-20Ni, and a nickel-based alloy, coded as 5Fe–23Cr-58Ni-8Mo, were exposed to the carbonate mixture for 500 h at 700 ºC, 750 ºC and 800 ºC under static atmospheric air. The results revealed that corrosion extension does not have a linear dependence on temperature. There are changes in the corrosion mechanism that depend on the temperature, but, in turn, they are directly influenced by the alloying elements of the material. The performance of the nickel-based substrate proved to be catastrophic at all the studied temperatures. The order from worst to best was 700 ºC > 750 ºC > 800 ºC. The presence of a high molybdenum concentration in the carbonate mixture in contact with this nickel-based alloy suggested that this element dissolution contributes to increasing the corrosivity of the mixture. By contrast, the iron-based alloy showed improved corrosion resistance, with an estimated corrosion rate in the order of hundreds of microns at the three temperatures. The best performance of the 51Fe-24Cr-20Ni alloy was achieved at 700 ºC, followed by that at 800 ºC, while the highest degradation was registered at 750 ºC. This investigation reinforced the idea of the complexity of the corrosion processes in molten carbonate. The equilibrium of corrosive species is very sensitive to an important number of parameters, meaning that modifications in the system conditions have a great impact on corrosivity. Hence, it is critical not to make assumptions when considering potential materials for carbonate containment in CSP technology.

Роль наноструктур в формировании эмиссионных свойств оксидно-никелевых катодов

The electronic and crystal structures of oxide-nickel compositions based on ternary barium-calcium-strontium carbonates containing nickel nanoparticles and nanocrystals of barium carbonate have been studied by electron spectroscopy and precision X-ray structural analysis. It was found that nickel nanoparticles have a significant effect on the parameters of the electronic structure of barium oxide crystallites formed in these compositions during their heat treatment. It is shown that X-ray diffraction analysis can be used as the basis for the method of quality control of ternary carbonates for their effective use in the composition of oxide-nickel cathodes.