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It has been well recognized that Li2CO3 is inevitably formed at the surface of nickel rich layered compounds (NRLC) upon storage in air which is usually considered to be detrimental to the performance. Actually, its formation may have been triggered during synthesis of NRLC. However, little is known of its formation during synthesis of NRLC in air and its interaction behaviors with electrolyte during electrochemical process. Herein, we successfully tailor Li2CO3 surface phase simply by controlling calcination time during synthesis of structurally well ordered LiNi0.9Mn0.1O2 particles with great similarity in structure, morphology, size and crystallinity in air using a facile sol-gel method. The thickness of Li2CO3 layer is for the first time observed to decrease with increased calcination time, accompanied by the reduced Ni2+ at surface. More oxygen vacancies caused by more Ni2+ owing to the difficulty of oxidizing Ni2+ to Ni3+ at the surface are proposed here to be responsible for the formation of more Li2CO3 for shorter calcination times. Li2CO3 surface phase is evidenced to favor not only suppressing the H2/H3 phase transition but alleviating the interaction of LiNi0.9Mn0.1O2 with electrolyte because of the coating effect, which therefore improves the cycling stability of LiNi0.9Mn0.1O2 at low rates. Therefore, this study not only provides a new insight into the surface changes of LiNi0.9Mn0.1O2 with calcination time at high temperature during synthesis in air, but opens up a new avenue to tailoring Li2CO3 surface phase as desired by controlling the oxidization extent of Ni2+ to Ni3+ to modulate oxygen vacancies at surface through employing different oxidizing atmospheres or calcination times for performance improvement or exploration of novel preparation approaches of high performance NRLC.

The water activities of the MgCl2–RbCl–H2O ternary system and its sub-binary systems have been measured with the isopiestic method at 323.15 K. The measured water activities for the MgCl2–H2O and RbCl–H2O sub-binary systems agree well with the results reported in literature. The measured equal water activity lines of the MgCl2–RbCl–H2O ternary system are not straight lines, which means the mixing behavior of the solutions do not obey Zdanovskii’s rule. The solubility of the MgCl2–RbCl–H2O ternary system has been determined with the Flow-Cloud-Point method at 323.15 K, and the measured results are roughly consistent with values reported in the literature. The Pitzer model was selected to correlate the water activity and solubility data measured in this work. The predicted water activities and solubility isotherm for the MgCl2–RbCl–H2O ternary system at 323.15 K, with binary solution parameters only, both deviated from the experiment values. The ternary solution Pitzer model parameters were obtained by fitting the measured water activities in the ternary system. The water activities and solubility isotherms of the MgCl2–RbCl–H2O ternary system at 323.15 K were calculated including both binary and ternary solution parameters. The calculated water activities are consistent with the experimental values. The calculated solubility isotherms are roughly consistent with experiment values, except they deviate somewhat in the RbCl crystallization region.

A sort of novel microencapsulated phase change materials (PCMs) has attracted much attention for energy storage. However, the solar energy utilization efficiency of traditional microcapsulated PCMs is still not very high up to date. In this work, new core@shell structured paraffin@SiO2/Ti4O7 composite microcapsules were developed to harvest environmental full-spectrum sunlight by smart and rational design using a sol-gel method. The SiO2 shell not only prevented the leakage of paraffine, but also improves its thermal conductivity. The black 300 nm Ti4O7 particles, which were successfully embedded into the SiO2 shell, can achieve the efficient absorption of sunlight and simultaneously high conversion from light to thermal. The resultant paraffin@SiO2/Ti4O7 microcapsules retained most enthalpy of paraffin, increased its stability, and exhibited an excellent thermal energy storage performance. The thermal conductivity of paraffin@SiO2/Ti4O7 microcapsules was significantly enhanced by 334.87% (1.322 W m−1 K−1) compared with 0.304 W m−1 K−1 of one for paraffin. When the mass fraction of Ti4O7 nanoparticles is 3 wt% of paraffin, these paraffin@SiO2/Ti4O7 microcapsules exhibited remarkable 85.36% of photo-thermal storage efficiency compared with 24.14% of one for paraffin. Due to their huge superiority of high efficient use of abundant solar energy in natural resources, these new photo-driven PCMs are very promising materials for solar-to-thermal conversion and energy storage.

Water activities for the CaCl2–SrCl2–H2O ternary system and its sub-binary system were elaborately determined using an isopiestic vapor-pressure method at 323.15 K. The solubility of the titled ternary system at 323.15 K was also determined by the isothermal equilibrium method. The Pitzer–Simonson–Clegg (PSC) model was used for correlating the determined water activity and solubility data, simulating the thermodynamic properties, and predicting the solubility isotherm of the titled system. The reliability of the determined solubility results in this work was evaluated by comparing with the solubility isotherms calculated with the PSC model. The model simulation results showed that the thermodynamic properties and solubility can be predicted with binary parameters only. The experiment and simulation results showed that the equilibrium solid phase in the CaCl2–SrCl2–H2O ternary system are pure salts, and no solid solution was found at 323.15 K.

Water activities in the ternary system CsCl–MgCl2–H2O and its sub-binary systems at 323.15 K were elaborately measured by an isopiestic method. Moreover, the solubility of the CsCl–MgCl2–H2O system at 323.15 K was also measured by the flow-cloud-point method. A Pitzer model was used to predict the measured water activity and solubility data. The binary parameters for the CsCl–H2O system at 323.15 K were obtained by fitting the measured water activities for this binary system. The calculated water activity and solubility isotherms for the CsCl–MgCl2–H2O system at 323.15 K, with binary parameters only, deviated from the experimental values. This means that it is insufficient with binary parameters only to predict the water activity and calculate the solubility isotherms of the CsCl–MgCl2–H2O system at 323.15 K. The calculated solubility isotherms with both binary and mixing parameters, obtained by fitting the measured water activity, also deviated from experimental values. A new set of reasonable ternary pa...

Water activities for the ternary system of KCl–SrCl2–H2O and its sub-binary system SrCl2–H2O were elaborately measured using an isopiestic method at 323.15 K. The solubility isotherms for the KCl–SrCl2–H2O system were determined by the isothermal equilibrium method. It is found that the measured isopiestic composition lines for the KCl–SrCl2–H2O system deviated from the Zdanovskii rule, especially at a lower water activity. The Pitzer–Simonson–Clegg model was used to correlate the measured water activity and solubility data, simulate the thermodynamic properties, and predict the solubility of the ternary system. The reliability of the solubility data measured in this work was evaluated by comparing with the solubility isotherms calculated with the Pitzer–Simonson–Clegg model. The measured water activity and solubility results are of great importance for predicting the phase diagram of other multicomponent systems that related to this ternary system.

Water activities for the MgCl2–RbCl–H2O ternary system and its sub-binary MgCl2–H2O and RbCl–H2O systems at 298.15 K have been measured using the isopiestic method. The measured results for the binary systems agree well with literature data. The measured equal water activity lines for the MgCl2–RbCl–H2O ternary system deviate from Zdanovskii’s rule. The solubilities for the MgCl2–RbCl–H2O ternary system also have been measured using a isothermal visual first/last crystal method, and the results are consistent with one reported set of solubility data. Pitzer’s model was selected to correlate the measured water activity and solubility data and the parameters reported in the literature are re-examined by comparing the model-calculated equal water activity lines and solubilities with experimental values measured in this work. New and reasonable parameters are obtained by fitting the water activity and solubility data measured in this work and those reported in the literature. The water activities and solubilities were simulated with the new parameters and the results show that the Pitzer model can successfully represent the thermodynamic properties and be used to calculate the solubility isotherms.

Water activities of the CsCl–MgCl2–H2O ternary system and its sub-binary systems were elaborately measured by an isopiestic method at 298.15 K. The solubility of this ternary system at 298.15 K was also measured by two different methods, namely isothermal method and Flow-Cloud-Point method. The solubilities measured by the two different methods were consistent with each other. A Pitzer model was used to represent the thermodynamic properties and calculate the solubility isotherms for the CsCl–MgCl2–H2O ternary system at 298.15 K. Both the equal water activity lines and the solubility isotherms are calculated with parameters reported in literature. It was found that only the calculated equal water activity lines with the parameters reported by Scharge et al. are consistent with the experimental values of this work. However, all the calculated solubility isotherms deviated from the experimental data in this work. New set of ternary parameters were obtained by fitting the water activities and solubility data...

Water activities of the CuCl2−MCl2−H2O (M = Mg, Ca) ternary systems and their sub-binary systems have been measured by the isopiestic method at 298.15 K. The maximum concentrations of the CuCl2−H2O, MgCl2−H2O and CaCl2−H2O binary systems are 5.28 mol•kg−1, 5.25 mol•kg−1 and 6.61 mol•kg−1, respectively. The concentrations of mixture solution rang from 0.91 mol•kg−1 to 5.69 mol•kg−1 for CuCl2−MgCl2−H2O system, and 1.29 mol•kg−1 to 6.87 mol•kg−1 for CuCl2−CaCl2−H2O system. The measured water activities of the sub-binary systems are consistent with the experimental results reported in literature. The measured equal water activities in the ternary systems strongly deviate from the Zdanovskii-Stokes-Robinson (ZSR) lines. The Pitzer model, Pitzer-Simonson-Clegg (PSC) model and Reaction model were selected to correlate and predict the water activity obtained in this work and the solubility reported in literature for the CuCl2−MCl2−H2O (M = Mg, Ca) ternary systems at 298.15 K. It was found that, the Pitzer model and PSC model cannot consistently represent these thermodynamic properties, with the binary and mixing parameters that already reported or fitted in this work. However, the Reaction model, representing the different competition association ability of common-anions and water molecules with different cations, can successfully predictethe water activity and solubility isotherms in these ternary systems at 298.15 K with binary parameters only. Applying the Reaction model, some examples of the Cu-bearing species distribution as a function of MgCl2 (CaCl2) molalities are given and used to account for how the structure variation of a electrolyte solution influences its macroproperties.

This study is part of a series of studies on the development of a multi-temperature thermodynamically consistent model for salt lake brine systems. Under the comprehensive thermodynamic framework proposed in our previous study, the thermodynamic properties of the binary systems (i.e., NaCl+H2O, KCl+H2O, MgCl2+H2O and CaCl2+H2O) are simulated by the Pitzer–Simonson–Clegg (PSC) model. Various thermodynamic properties (i.e., water activity, osmotic coefficient, mean ionic activity coefficient, enthalpy of dilution and solution, relative apparent molar enthalpy, heat capacity of aqueous phase and solid phases) are collected and fitted to the model equations. The thermodynamic properties of these systems are reproduced or predicted by the obtained model parameters. Comparison to the experimental or model values in the literature suggests that the model parameters determined in this study can describe all of the thermodynamic and phase equilibria properties over wide temperature and concentration ranges. This modeling study of binary systems provides a solid basis for property predictions of salt lake brines under complicated conditions.

The solubility of the LiCl–SrCl2–H2O system along with its sub-binary systems LiCl–H2O and SrCl2–H2O at 323.15 K and 348.15 K has been measured via the Isothermal Dissolve Equilibrium (IDE) method. The gauged solubility for the LiCl–H2O and SrCl2–H2O binary systems is consistent with the result reported in literature. In view of the measured solubility and corresponding liquid-solid line results for the LiCl–SrCl2–H2O system at 323.15 K, exist four equilibrium solid phases, i.e. LiCl·H2O, SrCl2·H2O, SrCl2·2H2O and SrCl2·6H2O, and four corresponding independent crystallization regions for these solid phases, three invariant points E1, E2, E3 for LiCl·H2O and SrCl2·H2O, SrCl2·H2O and SrCl2·2H2O, SrCl2·2H2O and SrCl2·6H2O, respectively. For the solubility of this ternary system at 348.15 K, there are only three equilibrium solid phases, i.e. LiCl·H2O, SrCl2·H2O and SrCl2·2H2O, accordingly two invariant points, E1 for LiCl·H2O and SrCl2·H2O and E2 for SrCl2·H2O and SrCl2·2H2O. No existence of SrCl2·6H2O solid phase in this ternary system at 348.15 K. The comparison of the phase diagram at 323.15 K and 348.15 K indicates that, with the increase of temperature, the crystallization region of SrCl2·6H2O disappeared, however crystallization region of SrCl2·H2O became larger obviously.

Actuated by the needs of high power electronic devices heat dissipation, diamond/Cu composites with excellent thermal dissipation properties have been considered as the next generation of thermal management material. Herein, an easy-to-operate intermittently electroplated method is developed for coating micro-sized particles and successfully applied to prepare Cu-coated diamond powders for the first time. The Cu coating is covered evenly and densely on the diamond particles surface, and its volume fraction in diamond/Cu composite powders could be precisely controlled by adjusting the plating time. The dense diamond/Cu composites bulks with varied Cu volume fractions were obtained by hot-press sintering process. The as-sintered microstructures of diamond/Cu bulks present that diamond particles are bonded strongly by Cu shell layer, which is conducive to promoting densification capacity. The maximal diamond/Cu composite bulk possesses high thermal conductivity of 638 W/(m·K) and low coefficient of thermal expansion (CTE) of 4.11 × 10−6/K at 55 vol% diamond. The bending strength of 45 vol% diamond/Cu composite reaches 276 MPa. The combination of these excellent thermal and mechanical properties, coupled with the simple, efficient powder-preparation process, demonstrate the large potential of intermittently electroplated method applying in the development of thermal management material.