In order to improve the accuracy of the GRU neural network model in predicting the remaining useful life (RUL) of lithium-ion batteries, the GRU model was optimized based on PCA-GWO and then applied in the prediction. The results show that compared with the traditional GRU model, the PCA-GWO-GRU model presents higher prediction accuracy. When the starting point of the prediction is 90% of the original data, the prediction accuracy can reach the highest, with the corresponding RMSE of 0.004 9, MAE of 0.003 6, and R² of 0.986 3.

A kind of hydrogen storage alloy of La_0.7R_0.1Mg_0.2Ni_3.35Al_0.15 (R=La/Nd/Sm) was synthesized with induction melting method, and the effect of La substituted with rare earth element Nd/Sm on the phase structure, microstructure, and electrochemical performance of the hydrogen storage alloy was explored. The results show that the substitution of Nd or Sm for La doesn't change the phase composition of the hydrogen storage alloy, which is still composed of LaNi₅, (LaMg)₂Ni₇, and (LaMg)₅Ni₁₉ phases, but leads to higher abundance of LaNi₅ and (LaMg)₅Ni₁₉ phases, and lower abundance of (LaMg)₂Ni₇ phase in the hydrogen storage alloy. The hydrogen storage alloy, with La, Nd and Sm as R, deliver the maximum discharge capacities of 377 mAh/g, 382 mAh/g and 376 mAh/g, respectively, after the second charge-discharge cycle. With La substituted with Nd or Sm, the hydrogen storage alloy has its high-rate discharge capacity, the charge retention rate after 24 hours, and capacity retention rate after 100 cycles all improved to some extent, among which the hydrogen storage alloy with Nd as R is the best in all corresponding performance. Moreover, the substitution of La with Nd or Sm can make the hydrogen storage alloy with higher exchange current density and higher coefficient of hydrogen diffusion. Its high-rate discharge performance, exchange current density and hydrogen diffusion coefficient are all in in the same trend, indicating that high-rate discharge performance of the hydrogen storage depends on both exchange current density and hydrogen diffusion coefficient.

With vanadium pentoxide and citric acid as raw materials, a kind of 3D flower-like VO₂(B) electrode material with large specific surface area and excellent structural stability was prepared by adopting hydrothermal synthesis. The crystal structure and morphology of the VO₂(B) electrode material were characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope, and the electrochemical properties of VO₂(B) electrode material were measured by constant current charge and discharge, as well as cyclic voltammetry. The results show that the first specific dischage capacity of 3D flower-like VO₂(B) electrode material is 227 mAh/g at a current density of 0.1 A/g. It delivers the first specific discharge capacity of 151 mAh/g at a high current density of 1 A/g, and retains 79.6% of this capacity after 300 charge-discharge cycles, exhibiting a good rate performance.

As for the open-pit slope with fault structure, studies on its deformation and failure characteristics were carried out by means of remote sensing images, field investigation and numerical simulation, and its safety factor was also calculated, so as to explore the influence of fault structure on slope stability. Then, based on the analysis of deformation and failure process of slope, the failure rule for open-pit slope with fault structure was discussed. It is found that the landslide hazard occurring on the north slope of the open-pit mine is attributed to an internal factor of fault structure combined with an external factor of unloading by underground mining. Under the combined action of disturbance by underground mining and cutting by F15 fault, a landslide is prone to occur along the fault structure, and then the failure zone will be gradually expanded. The deformation and displacement of upper slope above the F15 fault structure becomes relatively larger, and proceeds towards the eastern bottom along the F15 fault structure. The F15 fault structure changes the deformation and failure trend of the upper part of the northern slope. It is shown that when the safety factor of open-pit slope is 1.45, F15 fault zone is the potential sliding plane, and no larger deformation has occurred along the fault zone of the northern slope.

With silicon material (BFSi) extracted from blast furnace slag as silicon source and polyacrylonitrile (PAN) as carbon source, a kind of silicon-carbon anode material for lithium-ion batteries was synthesized. And the influence of ratio of silicon to polyacrylonitrile on the BFSi@C material was investigated. Results show that BFSi@C synthesized with BFSi and PAN in a mass ratio of 3∶1 delivers an initial charge capacity of 1 884.99 mAh/g at a current density of 0.5 A/g. After 100 cycles, it still delivers a specific charge capacity of 1 509.32 mAh/g, with a capacity retention rate of 80.07%. Moreover, it presents excellent rate performance at high current densities. Compared with commercial silicon materials, BFSi@C demonstrates higher cycle capacity and superior rate performance, delivering a specific capacity up to 538.31 mAh/g at a current density of 5 A/g.

With tetraethyl orthosilicate as silicon source and cetyltrimethylammonium bromide (CTAB) as a surfactant and pore-forming agent, a carbon-coated mesoporous hollow silicon oxide as anode material was synthesized by adopting the modified stöber method and carbonthermal reduction. The results show that different volume ratio of ethanol to water can bring important impact to the particle size, morphology and performance of SiO_x nanospheres. With ethanol and water in a low volume ratio, the obtained nanomaterial has a low sphericity and becomes oval; as the ratio increases, the nanomaterial becomes larger in size; with ethanol and water in a ratio of 0.45, the obtained SiO_x nanospheres are around 300 mm in size. The button batteries assembled with such nanospheres deliver a reversible specific capacity of 813 mAh/g after 200 cycles at a current density of 100 mA/g, and 704 mAh/g after 1 200 cycles at 500 mA/g, retaining 82% of this capacity, with a capacity attenuation rate of 0.015% after each cycle.

Cathode and anode materials in spent lithium iron phosphate battery powder are difficult to be separated by flotation. In order to solve this problem, it was proposed that lithium iron phosphate battery powder was pretreated by oxidative roasting, and then subjected to a flotation process for seperation between the cathode and anode materials of lithium iron phosphate. The results show that after lithium iron phosphate battery powder is pretreated by oxidative roasting at 500 ℃ for 30 minutes, the subsequent flotation process can lead to the graphite-based anode material with carbon grade up from 47.63% to 97.70%, and the cathode material with carbon grade down from 24.00% to 1.01%, presenting a significant separation effect. In comparison, the battery powder without pretreatment has cobweb-like long carbon-chain organic matter on its surface, which causes adhesion between cathode and anode materials of batteries, resulting in poor separation effect by flotation. The pretreatment of oxidative roasting can effectively eliminate the long carbon-chain organic matter on those cathode and anode materials, thus enhancing the difference in surface properties between cathode and anode materials. As a result, the enhanced flotation separation effect makes graphite-based anode material recycled from spent lithium iron phosphate batteries.

Based on comparison of cadmium immobilization with 4 types of minerals originated from 14 places in Hunan Province, four kinds of natural and efficient remediation materials (including limestone from Yujiaao of Ningxiang County, low-grade manganese ore from Nanmuchong of Xiangtan County, bentonite from Mazongling of Taoyuan County, and sepiolite from Xingang of Shimen County) were selected. The kinetic rate of cadmium immobilization by these four natural minerals is in the following descending order: bentonite > limestone > sepiolite > manganese ore. The cadmium adsorption by four kinds of minerals increases as the initial cadmium mass concentration increases. With cadmium mass concentration no higher than 10.0 mg/L, the cadmium adsorption by these four minerals is in the following descending order: limestone > bentonite > manganese ore > sepiolite; with cadmium mass concentration exceeding 10.0 mg/L, the cadmium adsorption by these four minerals is in the following descending order: bentonite > limestone > manganese ore > sepiolite. The adsorption behavior follows Langmuir adsorption model, and the maximum adsorption capacities of bentonite, limestone, manganese ore and sepiolite are 29.38 mg/g, 14.51 mg/g, 9.67 mg/g and 5.27 mg/g respectively. With pH of solution within the range of 6 to 9, the removal efficiency of cadmium by four minerals is in the following descending order: limestone > bentonite > manganese ore > sepiolite. It is concluded that the cadmium immobilization with natural minerals is related to chemical composition of minerals, initial cadmium mass concentration, and pH value.

A cathode material (NaNi_0.5Mn_0.5O₂) for sodium-ion batteries was synthesized by adopting solid-state, co-precipitation and sol-gel methods, and the effects of synthesis methods on crystal structure, microscopic morphology and electrochemical performance of the cathode material were also explored. The results show that the materials synthesized respectively by those three methods all have O3-type structure, but exhibit different morphology. The cathode material synthesized by solid-state method has a special layered structure, which is conducive to sodium ion de-intercalation. The cathode materials synthesized by solid-state, co-precipitation and sol-gel methods, respectively, deliver an initial specific discharge capacity of 96.1 mAh/g, 92.8 mAh/g and 92.3 mAh/g at 0.1C, with retention rate of 64.3%, 46.5% and 36.5% respectively after 100 cycles at 0.5C. It is concluded that the solid-state synthesis is an appropriate method.

Flash flotation technique was introduced to an experiment to recover crystalline graphite. The influence of impeller speed, superficial aeration rate and foam layer thickness on the flash flotation indices of graphite was investigated. The results show that flotation with impeller speed of 750 r/min, superficial aeration rate of 0.3 m³/(m²·min) and foam layer thickness of 20 mm can bring a better flotation performance of graphite. According to the particle size analysis and microscopic observation analysis of concentrate, the flash flotation displays good recovery of the graphite in a particle size range of 0.074-0.180 mm, which is dominated by flake graphite monomer and rich intergrowth. As the flash flotation technique favors the collection of useful minerals from the classification underflow in advance, the probability of overgrinding can be reduced and the flake morphology can be therewith reserved. Therefore, flash flotation technique is expected to be commercially applied in the flotation recovery of crystalline graphite.