Dynamic characteristics and evolution laws of underground brine in Mahai salt lake of Qaidam Basin during mining process.

In the late stage of underground brine mining in salt lakes, the method of injecting fresh water is often used to extract the salt from the brine storage medium. This method of freshwater displacement breaks the original water-rock equilibrium and changes the evolution process of the original underground brine. To explore the mechanism of salt release in saline water-bearing media under conditions of relatively fresh lake water dissolution, this paper analyzes the changes in the chemical parameters of brine from 168 sampling points in the Mahai salt lake in the Qaidam Basin at three stages (before exploitation, during exploitation, and late exploitation) by correlation analysis, ion ratio analysis, and other methods and investigate the variations in porosity and the evolution laws of brine. The results show that the changes in the main ion content and brine mineralization during the exploitation process are small. The changes in Ca2+ content are significant due to the low solubility of calcium minerals, the precipitation of gypsum during the mixing process, and the adsorption of cations by alternating with Ca2+. Primary intergranular pore skeletons are easily corroded to form secondary pores, which increase the geological porosity. Na+ and Cl- are the dominant ions in the brine in the study area, but the concentration of Ca2 + decreased significantly under the influence of mining, by 41.7% in the middle period and 24.5% in the late period. The correlation between Ca2+ and salinity changes significantly in different mining stages, and the reason for the decrease of Ca2+ may be due to the influence of mineral dissolution, mixing, and anion-cation exchange. The porosity of the layer in the study area showed the opposite trend of Ca2+, and the porosity increased first and then decreased. The innovation of this paper lies in analyzing the reasons and mechanisms of the disturbance of artificial dissolution mining on stratum structure by comparing the hydrochemical characteristics and porosity of underground brine storage media in three different mining stages. The research in this paper provides a theoretical basis for the calculation of brine resource reserves and the sustainable development of underground brine in salt lake areas.

Hydrated Calcium Vanadate Nanoribbons with a Stable Structure and Fast Ion Diffusion as a Cathode for Quasi-Solid-State Zinc-Ion Batteries.

We demonstrated the use of hydrated calcium vanadate (CaV6O16·3H2O, denoted as CaVO-2) as a cathode for aqueous zinc-ion batteries (AZIBs). Nanoribbons of hydrated calcium vanadate facilitated shortening of the Zn2+ transport distance and accelerated zinc-ion insertion. The introduction of interlayer structure water increased the interlayer spacing of calcium vanadate and as a "lubricant". Ca2+ insertion also expanded the interlayer spacing and further stabilized the interlayer structure of vanadium-based oxide. The density functional theory results showed that the introduction of Ca2+ and structured water could effectively improve the diffusion kinetics, resulting in the rapid transport of zinc ions. As a result, AZIBs based on the CaVO-2 cathode offered high specific capacity (329.6 mAh g-1 at 200 mA g-1) and fast charge/discharge capability (147 mAh g-1 at 10 A g-1). Impressively, quasi-solid-state zinc-ion batteries based on the CaVO-2 cathode and polyacrylamide-cellulose nanofiber hydrogel electrolytes maintained an outstanding specific capacity and long cycle life (162 mAh g-1 over 10 000 cycles at 5 A g-1). This study provided a reliable strategy for metal-ion insertion and the structural water introduction of oxides to produce a high-quality cathode for ZIBs. Meanwhile, it provides ideas for the combination of vanadium-based materials and gel electrolytes to construct solid-state zinc-ion batteries.

Interfacial Engineering of MoS2/V2O3@C-rGO Composites with Pseudocapacitance-Enhanced Li/Na-Ion Storage Kinetics.

Molybdenum sulfide has been widely investigated as a prospective anode material for Li+/Na+ storage because of its unique layered structure and high theoretical capacity. However, the enormous volume variation and poor conductivity limit the development of molybdenum sulfide. The rational design of a heterogeneous interface is of great importance to improve the structure stability and electrical conductivity of electrode materials. Herein, a high-temperature mixing method is implemented in the hydrothermal process to synthesize the hybrid structure of MoS2/V2O3@carbon-graphene (MoS2/V2O3@C-rGO). The MoS2/V2O3@C-rGO composites exhibit superior Li+/Na+ storage performance due to the construction of the interface between the MoS2 and V2O3 components and the introduction of carbon materials, delivering a prominent reversible capacity of 564 mAh g-1 at 1 A g-1 after 600 cycles for lithium-ion batteries and 376.3 mAh g-1 at 1 A g-1 after 450 cycles for sodium-ion batteries. Theoretical calculations confirm that the construction of the interface between the MoS2 and V2O3 components can accelerate the reaction kinetics and enhance the charge-ionic transport of molybdenum sulfide. The results illustrate that interfacial engineering may be an effective guide to obtain high-performance electrode materials for Li+/Na+ storage.