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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. [ABSTRACT FROM AUTHOR]

Given its safer working potential and higher theoretical capacity, Li3VO4 has become a potential alternative anode material to graphite. However, the hydrophilicity, low electrical conductivity, and unsatisfactory reaction kinetics of the Li3VO4 anode pose a challenge. In this paper, a graphene-wrapped Li3VO4@rGO hybrid was prepared using a novel efficient uniform rotation solvothermal (URS) method. Graphene with high electrical conductivity accelerates the reaction kinetics of the anode material to improve its rate performance. The URS method restrains the agglomeration of particles to shorten the diffusion paths of Li+. The uniform reaction obtained by this method and the lamellar shape of graphene synergistically enlarge the specific surface area of Li3VO4 to supply additional active sites for the extraction/insertion of Li+. Therefore, Li3VO4@rGO–R exhibits superior cycling performance (249.5 mA h g−1 after 4000 cycles at 5 A g−1) and rate performance (243.3 mA h g−1 at 10 A g−1). This study provides a versatile and efficient method for enhancing the electrochemical performance of anode materials. [ABSTRACT FROM AUTHOR]

The H 2 V 3 O 8 /MXene film shows excellent electrochemical properties as cathode material for aqueous zinc-ion batteries and solid-state zinc-ion batteries. [Display omitted] • H 2 V 3 O 8 /MXene film has been synthesized by hydrothermal method and coating method. • Combination MXene and H 2 V 3 O 8 synergistically improves electrochemical properties. • The H 2 V 3 O 8 /MXene film shows excellent performance for AZIBs and solid-state ZIBs. In this study, freestanding H 2 V 3 O 8 /MXene (HVO/MX) film were synthesized by high temperature mixing hydrothermal method and coating method. The composite film exhibits good electrical conductivity and flexibility. In addition, HVO/MX film shows excellent electrochemical properties when used as cathode material for aqueous zinc ion batteries (ZIBs) and solid-state ZIBs. The aqueous ZIBs assembled from the HVO/MX film shows satisfactory specific capacity (highest specific capacity can reach 346 mAh/g at 10 A/g) and cycling performance. Surprisingly, the assembled quasi-solid-state batteries can work well at room temperature and low temperature conditions. The battery maintained a high discharge specific capacity of 180 mAh/g after 3000 cycles at 25 °C. The outstanding performance of the HVO/MX film assembled battery is due to its good electrical conductivity, zinc-ion diffusion rate and simple battery structure. This work provides a novel route for the preparation of self-supporting cathode materials for different battery system. [ABSTRACT FROM AUTHOR]

In this study, we demonstrated the co-modification of oxygen vacancies and heterojunctions in VO 2 (B) (V O –VO 2 /MXene) as a cathode material for zinc-ion batteries (ZIBs). VO 2 nanobelts are uniformly distributed on MXene nanosheets, which providing complete electron transport channels during the insertion or de-insertion of Zn2+. The formation of oxygen vacancies provides additional active sites and enhances the conductivity of VO 2. Density functional theory calculations reveal that the oxygen vacancies effectively facilitate reversible intercalation/deintercalation process, which results in rapid intra-crystal zinc ion diffusion. The combination of V O –VO 2 with MXene introduces an interfacial electric field, ultimately leading to synergistic enhancement in electrochemical activity. The V O –VO 2 /MXene composite exhibits the highest specific capacity (287 mAh g−1) at 10 A g−1 and excellent cycling lifespan (253 mAh g−1 after 3000 cycles) for ZIBs. This work provides a reliable strategy for the co-modification of metal oxide electrodes with oxygen vacancies and heterostructures. [Display omitted] • VO 2 /MXene heterojunctions with oxygen vacancies were synthesized via HTMM. • Oxygen vacancy and heterointerfaces lead to the superior zinc ion diffusion kinetic. • The synergistic effect of oxygen vacancy and heterointerfaces was demonstrated. • ZIBs shows high specific capacity, excellent rate capability and good cycle lifespan. [ABSTRACT FROM AUTHOR]