The development of cathode materials with excellent electrochemical properties is crucial for the application of hybrid supercapacitors. NiC₂O₄·2H₂O cathode material was synthesized by a precipitation method, and its microstructure, morphology and electrochemical performance were investigated. The results show that NiC₂O₄·2H₂O exhibits a unique polyhedral particle structure, the particle sizes are 0.5-2.0 μm, and each particle is composed of polycrystals, thus achieving a high specific capacity of 1 096.2 F/g at a current density of 1 A/g. The assembled nickel oxalate//activated carbon hybrid supercapacitor still maintains an energy density of 10.2 Wh/kg at a high power density of 3.7 kW/kg. Connecting two hybrid devices in series can light up green and yellow LEDs. This demonstrates that NiC₂O₄·2H₂O has potential application prospects in electrochemical energy storage as a novel, low-cost and environmentally friendly cathode material.

High-magnesium Portland cement clinker with MgO content of 6% was synthesized with chemical reagent. The effect of cooling method (i.e., furnace cooling, air cooling and liquid-nitrogen quenching) on the mineral composition, C₃S crystal type, solid solubility of MgO, and formation of periclase of high-magnesium Portland clinkers with different alumina modulus (IM) (i.e., 0.64, 1.10 and 3.00) was investigated. The samples were characterized by X-ray powder diffraction with Rietveld method, petrographic method and scanning electron microscopy. The results show that a rapid cooling can stabilize C₃S crystal into M3 type, and prevent the transformation of C₃S crystal from M3 to T3 type. And this has a little effect on the change of IM. The content of C₃S is relatively high in the clinker with a low IM and by furnace cooling, and the clinker with a high IM and by liquid-nitrogen quenching. Rapid cooling rate inhibits the crystallization of periclase, and the inhibition effect is more dominant in a low IM clinker. Clinker quenching can keep the morphology of C₃S intact, and promote periclase to turn into a fine round granule.

To investigate the occurrence of periclase in clinker aluminate and reveal the hydration mechanism, aluminates were synthesized via MgO doping at various contents. Their structure and hydrates were characterized by scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. The results indicate that higher sintering temperature and MgO content improve the formation and stability of C₄AF and C₁₂F₇. A phase separation occurs in molten aluminum phase. The black phase includes the main minerals like C₃A and periclase, while glass and yellow phases both have a low MgO content. The hydration heat of aluminate phase in the first day decreases with the increase of MgO content, indicating that MgO doping decreases the hydration rate of aluminate phase. In addition, the layered double hydroxides with a Mg∶Al ratio of 2 or 3 appear in the hydration products of aluminate incorporated with MgO.

In order to obtain stable and dispersed calcium silicate hydrate (C-S-H) crystal nucleus, improve its crystal nucleus-inducing effect on cement hydration, and realize the efficient utilization of cement clinker. Polycarboxylate superplasticizers (PCE) with different proportions of acrylic acid (AA) and silane group (KH570) were prepared via free radical polymerization to disperse calcium silicate hydrate (C-S-H) seeds. The corresponding C-S-H/PCE seeds were synthesized by a solution precipitation method. The grain size/size distribution, the stability of C-S-H/PCE seeds and the bonding mode of PCE on C-S-H interface were investigated. The results show that the PCE with an appropriate proportion of KH570 can effectively control the grain size of C-S-H/PCE seeds. The adsorption mode of PCE on C-S-H surface changes from Ca²⁺ complexation to a more stable Si—O—Si chemical bond, and the grain size of C-S-H/PCE seeds firstly decreases and then increases with the increase of KH570 ratio. At a KH570 to AA ratio of 1, the adsorption layer thickness of PCE on the surface of C-S-H is 2.5 nm, the grain size of C-S-H/PCE seeds is 60 nm and the stability is optimum. The PCE undergoes an intramolecular dehydration condensation process under alkaline condition with further increasing the proportion of KH570, forming a reticulated silicone resin structure, which is unfavorable for the regulation of grain size of C-S-H/PCE seeds.

The influence of cold CaCl₂ solution on the setting behavior, strength development, mineralogical composition, microstructure, and chloride content of calcium sulphoaluminate (CSA) cement at -10 ℃ was investigated. The results show that there is a significant and persistent temperature peak in CSA cement pastes mixed with 16% and 28% cold CaCl₂ solution, so CSA cement can hydrate continuously. The temperature peak retards from 90 min to 150 min as the solution concentration increases from 16% to 28%. The pastes with 16% CaCl₂ solution set quickly and the compressive strength is high (initial setting time 15 min and final setting time 24 min, compressive strength 41.0 MPa at 1 day and 85.2 MPa at 28 days); while the pastes with 28% CaCl₂ solution set slowly and the compressive strength is low (initial setting time 85 min and final setting time 155 min, compressive strength 24.3 MPa at 1 day and 57.7 MPa at 28 days). Ettringite is the primary hydration product and its morphology is needle in hydrated pastes with 16% CaCl₂ solution. The Friedels salt turns to be dominant and the morphology is hexagonal plate in hydrated pastes with 28% CaCl₂ solution. There is little binding chloride for 16% CaCl₂ solution and 0.95% binding chloride for 28% CaCl₂ solution. In the presence of CaCl₂ solution, the CSA cement can hydrate continuously at -10 ℃. Furthermore, a shorter setting time and a higher strength can be obtained in CSA cement pastes mixed with 16%-20% CaCl₂ solution.

Tin-based oxides and their alloys with high specific capacities are considered as promising anode materials for Na-ion batteries. However, the tin-based oxides and their alloys suffer from a large volume variation and particle agglomeration during the charge-discharge process, resulting in electrode pulverization, capacity fading, and poor rate performance. In this paper, Bi/SnO_x particles anchored on an ultrathin carbon layer (Bi/SnO_x@C) were synthesized by a sodium chloride template method, and a uniform Bi/SnO_x@C heterostructure is constructed. The ultrathin carbon layer can effectively inhibit the agglomeration of Bi/SnO_x particles and increase the specific surface area of the electrode material, providing more active sites. Bi/SnO_x can also contribute the more specific capacity. The synergistic effect of ultrathin carbon layer and Bi/SnO_x composite can effectively improve the cycling stability, which is of great significance for the construction of high-performance electrode materials.

It is essential for the quality of concrete to carry out reasonable and adequate curing during the construction of concrete. The conventional external curing methods such as watering and coating, which are commonly used at present, have some problems of limited curing depth and dependence on the shape and construction part of the member. The internal curing method can solve these problems well and has a good application potential for the parts and structures that are easy to shrink, crack and inconvenient for external curing. This review represented recent development on the internal curing materials, and focused on the types of super absorbent polymer (SAP) as the promising internal curing materials and the mechanism of water absorption/release and the corresponding volume change. The water absorption/release behavior of SAP in cementitious materials and its influencing factors were summarized. The influence of SAP on the hydration process, pore structure and macroscopic properties of cementitious materials was discussed. In addition, the future direction of using SAP as an internal curing material for concrete was also envisaged.

Magnesium oxychloride cement (MOC) has some advantages like light weight, early strength, low thermal conductivity, and fire resistance, but poor water resistance restricts the application of MOC in civil, construction and other fields. This paper was to improve the water resistance of MOC by using soluble sulfates containing different metal cations as additives. The effect of soluble metal cations on the setting time and compressive strength of MOC was investigated. The phase composition, microstructure and pore structure of modified MOC were characterized by X-ray diffraction, scanning electron microscopy, and mercury intrusion porosimetry. The results show that Al³⁺, Fe²⁺, Cu²⁺ ions and free OH^- ions in the MOC slurry can preferentially form a precipitate, inhibiting the formation of Mg(OH)₂, delaying the hydration of MgO, prolonging the setting time, reducing the total porosity of the MOC matrix, and improving the water resistance of MOC. In addition, SO₄^2- ions can also improve the stability of 5Mg(OH)₂·MgCl₂·8H₂O after soaking in water through the adsorption and coordination with Mg²⁺ ions in 5Mg(OH)₂·MgCl₂·8H₂O.

Manganese silicate nanomaterials have attracted attention due to their high specific surface area, large pore volume, adjustable pore size and good biocompatibility. Manganese silicate nanomaterials with various morphologies such as hollow nanospheres, solid nanospheres, and core-shell nanospheres are synthesized. Hollow manganese silicate nanomaterials can be applied in cancer diagnosis, cancer therapy, synergistic cancer therapy, etc.. This review mainly introduced the synthesis and applications of manganese silicate nanomaterials. Moreover, the future prospects for development of manganese silicate nanomaterials were discussed.

In order to improve the rheology and stability of ultra-high performance concrete containing coarse aggregate (CA-UHPC), the effects of silica fume, coarse aggregate, and steel fiber contents on the rheological properties of CA-UHPC were investigated, and the relationship among the rheological parameters, fiber, and coarse aggregate distribution was established. The results show that CA-UHPC usually exhibits a shear-thinning behavior. The modified Bingham model has more accurate fitting results of rheological parameters, and the fluidity required for the rheological properties test can be controlled at 450-690 mm. Increasing the silica fume content increases the yield stress, decreases the viscosity, and weakens the shear-thinning behavior. Increasing the coarse aggregate content firstly decreases and then increases the yield stress and viscosity, and intensifies the shear-thinning behavior. And increasing the steel fiber content increases the yield stress and viscosity, and intensifies the shear-thinning behavior. The number of steel fiber decreases from the top to the bottom of samples, while the proportion of coarse aggregate increases. The uniform dispersion degree of coarse aggregate increases with the increase of coarse aggregate content, but steel fibers deteriorate the uniform dispersion degree of coarse aggregate. The uniform distribution degree of steel fiber and coarse aggregate firstly increases and then decreases with the increase of steel fibers content.