Recovering lithium from solid waste is crucial to alleviating resource shortages. Lithium aluminosilicate glass-ceramics (LASG) and spent aluminum electrolyte (SAE) have become a research focus as potential strategic source owing to their high lithium content. This study innovatively exploits the high reactive fluorine characteristic of SAE to efficiently decompose the stable Si-O-Si(Al) mesh of petalite-type LASG, and K2SO4 is introduced to synergistically convert LiAlSi4O10 of LASG into LiF and Li2SO4. Then, selective lithium extraction and fluorine stabilization from both wastes were accomplished via the reaction of LiF and LiNa2AlF6 with gypsum, yielding lithium-bearing brine with minimal impurities at 97.05% extraction rate and harmless fluoride-stabilized slag. The co-roasting thermal profile is characterized by two endothermic stages: decomposition of LASG and a subsequent lithium-releasing phase transition. Combined micro-interface characterization and DFT calculations reveal strong SiF bonding interactions and significant charge redistribution at the SAE-LiAlSi4O10 interface, manifesting as distinct reaction layers, along with a marked enhancement from K2SO4 because of the stronger electron-donating ability of the Na0K1F slab. The waste-to-waste strategy significantly alleviates environmental pressures with hazardous waste while delivering economic viability, with a gross profit margin of 32.21%, and guiding efficient recovery of secondary lithium resource.

NvironAqueous zinc-iodine (Zn-I₂) batteries have emerged as a highly promising next-generation energy storage technology owing to their high theoretical capacity, intrinsic safety, emental friendliness, and cost-effectiveness. However, their practical implementation remains hindered by multiple challenges, including the polyiodide shuttle effect, zinc dendrite growth, and interfacial side reactions. As an effective strategy to address these issues, the development of electrolyte additives has witnessed significant progress in recent years. This review systematically summarizes recent advances in electrolyte additives, ranging from zinc anode interfacial regulation to iodine cathode stabilization, and provides an in-depth analysis of the underlying mechanisms and performance metrics of various additive categories. Specifically, zinc anode additives primarily function by modulating the Zn2+ solvation structure, optimizing the interfacial electric field distribution, and constructing artificial protective layers, thereby enabling uniform zinc deposition and suppressing parasitic reactions. Conversely, iodine cathode additives effectively anchor polyiodides and accelerate reaction kinetics through halogen bonding regulation, host-guest interactions, and redox mediation. Notably, multifunctional synergistic additives can simultaneously address the challenges at both electrodes, leading to a profound enhancement in overall battery performance. Finally, this review outlines future research directions, including the development of stimuli-responsive additives, the deepening of mechanistic understanding, and the promotion of industrial applications, aiming to provide theoretical guidance and practical references for the design of high-performance Zn-I₂ batteries.

High-temperature oxidation of prebaked anodes during aluminum electrolysis causes substantial carbon loss and increases greenhouse-gas emissions, posing a major challenge to low-carbon industrial development. Although applying coating can mitigate oxidation of anode, existing studies rarely provide a comprehensive evaluation of both room-temperature rheological properties and oxidation resistance over a broad temperature range. Herein, a novel slurry-based coating with temperature-adaptive oxidation resistance was developed through systematic composition optimization. Zeta potential and rheological analyses indicated that optimal dispersion stability was achieved with 0.5 wt% dispersant, while 0.25 wt% thixotropic agent enabled rapid viscosity recovery. A solid content of 75.7 wt% provided a balance between shear-thinning behavior and oscillatory stability, satisfying the requirements for slurry storage and spray application. Thermal analysis (TG-DSC/DIL) showed that the coating underwent densification below 400 °C, forming an early oxidation barrier. At approximately 700 °C, the coating softened and transformed into a bonding phase, which was inferred to accommodate thermal stress through plastic deformation and thereby suppress cracking. Finally, the net carbon consumption of the coated carbon blocks was only 1.14 wt% at 600 °C and 5.39 wt% at 960 °C, corresponding to reductions of 97.83% and 94.56%, respectively, compared with uncoated carbon blocks. Under a fluoride-containing vapor atmosphere, the corrected net carbon consumption was 5.40 wt%, which was nearly identical to that obtained in air at 960 °C. Coating surface analysis indicates that the volatile NaAlF4 will generate a dense aluminum silicate protective layer in situ while eroding the coating, thereby preventing further erosion of the coating by the fluorine vapor. Therefore, the proposed slurry-based coating combines favorable processability with temperature-adaptive oxidation resistance, showing promising potential for protecting prebaked carbon anodes in aluminum electrolysis cell.

In the electrolysis cell, the anode coating must exhibit the anti-air oxidation and anti-corrosion ability faced by the fluorine vapor. People have predominantly concentrated on the oxidation resistance of the coating, neglecting its ability to withstand fluorine vapor corrosion. In this work, we prepared a series of coatings and tested the protective properties for the first time at 960 degrees C in a mixed atmosphere of fluorine vapor and air. The online high-temperature perspective system results show that the coating remains intact during heating and constant temperature in the mixed atmosphere, indicating that the coating can effectively protect the anode. The test results indicate that the coating demonstrates optimal protective properties at a /3K/A(m(KAlSi3O8):m(Al2O3)) ratio of 1.5, corresponding to a mass loss of 2.32 wt% for the sample. This value is significantly lower than the respective mass loss rates of 11.48 wt%, 3.44 wt%, 4.32 wt%, and 7.58 wt% observed at /3 K/A values of 0.5, 1.0, 2.0, and 2.5. A high /3 K/A value correlates with reduced toughness, while a low /3 K/A value corresponds to diminished viscosity. In the fluorine vapor, the continuous phase on the outer surface reacts with fluorine to form Na3AlF6 and SiF4. At the same time, the flaky alumina resists the corrosion of the fluorine vapor and protects the anode from oxidation.

High-purity AlF3 was prepared by the combined process of leaching the raw material of waste aluminum electrolytes with aluminum chloride, electrolyzing the leaching solution, and then mixing with ammonium hydrogen fluoride for roasting. Under the optimal leaching conditions of a fluorine to aluminum molar ratio of 2.0, a liquid-to-solid ratio of 12, a temperature of 90 degrees C, and time of 4 h, the fluorine leaching rate can reach 99.15%. Under the action of electrolysis, the H+ is reduced to H-2 in the cathode, while the remaining OH- combines with AlF2+ and AlF2+ to precipitate aluminium hydroxyfluoride hydrate. The results show that electrolysis is beneficial to reduce the impurity content of aluminium hydroxyfluoride hydrate. When the current density is 0.2 A/cm(2), the temperature is 90 degrees C, the stirring speed is 200 r/min, and the electrolysis endpoint pH is 3.0, the total content of Na, K and Ca impurities in the precipitation is only 0.64 wt.%. Moreover, the hydrolysis can be inhibited effectively by adding ammonium hydrogen fluoride in the mixed-roasting process. When the mass ratio of aluminium hydroxyfluoride hydrate to ammonium hydrogen fluoride is 2:1, the purity of the AlF3 product is even 99.51 wt.%. Conducively, the high-purity AlF3 can be returned to the aluminum electrolysis industry or used as a reagent.

Numerous fluorine-containing hazardous solid wastes from the electrolytic aluminum process pose a serious threat to the ecosystem and human health. Currently, in the study of leaching on these wastes, Al and F are usually recovered by adjusting the pH of the leaching solution to precipitate aluminium hydroxyfluoride hydrate, which can be used to produce aluminum fluoride by roasting. However, aluminium hydroxyfluoride hydrate is often mingled with cryolite and other impurities when precipitating, which ultimately affects the purity of obtained aluminum fluoride by calcination. Interestingly, herein, the aluminium hydroxyfluoride hydrate residue was digested by fluorosilicic acid to effectively remove impurities and obtain a pure aluminum fluoride solution, from which the beta-AlF3 product was produced by crystallization at a high-temperature. The results show that under the conditions of a temperature of 60 degrees C, time of 35 min, initial fluorine-aluminum molar ratio of 3:1 and initial concentration of fluorosilicic acid of 18 %, the gross yield of fluorine is 86.2 %, and the recovery of silicon in the form of SiO2 is 95.2 %. During crystallization, the product changes from AlF3 & sdot;3H2O to beta-AlF3 with the increase of temperature. Under the conditions of a crystallization temperature of 150 degrees C, an initial concentration of aluminum fluoride of 191.10 g/L and a stirring speed of 200 rpm, beta-AlF3 of an average particle size of 43.22 mu m was obtained by adding 5 % seed. The contents of Al and F in beta-AlF3 products are 32.57 % and 61.49 % respectively, which meet the requirements of GB/T 4292-2017 (AF-0) about National Standards of China. According to DFT calculation, the beta-AlF3 tends to adsorb two or three water molecules in its cavity structure, which explains why the crystallized beta-AlF3 contains water of 5.10 % at 180 degrees C.

Spent cathode carbon (SCC) as a hazardous solid waste from the aluminum electrolysis industry, contains numerous valuable components, but poses a serious threat to ecological environment. Molten salt roasting is an efficient separation and purification method for SCC than directly leaching of hyfrometallurgy. However, the current treatment of SCC by molten salt roasting is under inert atmosphere and high temperature conditions, which causes high production costs and low product economics. Herein, a low-temperature molten salt roasting process with 550 degrees C and NaOH additive under air atmosphere-followed by water leaching and acid leaching in turn is proposed to deeply purify SCC. A single-factor optimal experiment indicates that most of the impurities, such as Na3AlF6, were removed after water leaching and the refractory substances like silica-aluminate, were further transformed by acid leaching, which results in a significant improvement in the purity of the recovered graphite (RG) from 43.55 wt% to 98.67 wt%. DFT calculations confirm that RG have a greater density of states (DOS) near the Fermi energy level and lower migration energy barriers for Li ion, which provides a theoretical foundation for the high-value utilization of RG in anode material for lithium batteries. The primary and second leach filtrates were combined to recover 96.55% fluorine from solution in the form of cryolite under optimum conditions, based on solution equilibrium chemistry calculations of Al and F complexes. The whole process features low cost and environmental protection, and basically completes harmless treatment of SCC and recovery of valuable components.

In the electrolysis cell, the anode coating must exhibit the anti-air oxidation and anti-corrosion ability faced by the fluorine vapor. People have predominantly concentrated on the oxidation resistance of the coating, neglecting its ability to withstand fluorine vapor corrosion. In this work, we prepared a series of coatings and tested the protective properties for the first time at 960 °C in a mixed atmosphere of fluorine vapor and air. The online high-temperature perspective system results show that the coating remains intact during heating and constant temperature in the mixed atmosphere, indicating that the coating can effectively protect the anode. The test results indicate that the coating demonstrates optimal protective properties at a βK/A(m(KAlSi3O8):m(Al2O3)) ratio of 1.5, corresponding to a mass loss of 2.32 wt% for the sample. This value is significantly lower than the respective mass loss rates of 11.48 wt%, 3.44 wt%, 4.32 wt%, and 7.58 wt% observed at βK/A values of 0.5, 1.0, 2.0, and 2.5. A high βK/A value correlates with reduced toughness, while a low βK/A value corresponds to diminished viscosity. In the fluorine vapor, the continuous phase on the outer surface reacts with fluorine to form Na3AlF6 and SiF4. At the same time, the flaky alumina resists the corrosion of the fluorine vapor and protects the anode from oxidation.

Air oxidation is the main cause of the excessive consumption of prebaked anodes, which not only wastes carbon resources but also increases carbon emissions. In this study, a quasi-molten coating with self-healing for prebaked anode by using the slurry method was proposed. This coating utilizes the viscous molten liquid phases to bond the carbon anode, absorbs thermal stress, insulates the carbon anode from the air, and provides self-healing capabilities at elevated temperatures, while the solid phase provides toughening properties. A series of oxidation experiments have shown that the coating has superior oxidation resistance than coatings reported in the literature. The anti-oxidation mechanism of the coating. image

Recently, there has been a growing interest in lithium-containing spent aluminium electrolyte (LSAE) as a po-tential new source of lithium. However, the current method of using strong inorganic acids for leaching lithium from LSAE has several drawbacks, which not only consume a lot of acids but raise safety and environmental concerns due to the release of HF. Herein, a novel process combining NaF fluorination roasting and Al2(SO4)3 leaching is proposed for the efficient extraction of lithium from LSAE. LSAE with NaF additive was first roasted at temperatures between 900 and 980 & DEG;C to convert Na2LiAlF6 into easily leachable LiF. Then, environmentally friendly Al2(SO4)3 solutions were used to selectively leach LiF from roasted LSAE. Gibbs free energy change calculated by DFT confirms the thermodynamic feasibility of the NaF fluorination roasting and Al2(SO4)3 leaching process, and it was found that Al2(SO4)3 could react more readily with LiF than with Na3AlF6. Under optimal process conditions, a lithium leaching rate of 94.05% was achieved. After leaching, 99.26% of Al and 97.21% of F in the leachate were recycled as AlF1.5(OH)1.5(H2O)0.375 precipitation by adding NaOH solution to adjust the pH to 6.6. Then, AlF3 and Al2O3 with metallurgical grade were obtained by roasting AlF1.5(OH)1.5(H2O)0.375 at temperatures between 500 and 600 & DEG;C. Lastly, Li2CO3, with a purity of 99.0%, was precipitated using Na2CO3 from lithium-containing leachate after purification and evaporation concentration. The overall Li recovery rate for the entire process is 86.2%. Collectively, this research proposes an efficient and environmentally friendly extraction process for lithium from LSAE.

Activated alumina is the most common adsorbent for purifying fluoride in water, however, little is known so far about the adsorption mechanisms and comparison of adsorption behaviors for F on different crystal phase alumina surfaces, which seriously obstacles the development of high-performance sorbents. Herein, employing the density functional theory approach, we have studied F adsorbed on α-Al2O3(0001), γ-Al2O3(110), and θ-Al2O3(010) surfaces. Results accentuate that the θ-Al2O3 (010) is the most reactive than ɑ-Al2O3 (0001) and γ-Al2O3 (110) for F adsorption and the high reactivity is mainly attributed to the high unsaturation level of Al atoms. Detailly, the most stable adsorption sites are top of Al1 site, bridge of Al6 and adjacent Al atom, and bridge of AlⅢ atoms for α, γ, θ-alumina, respectively. The bonding picture shows that the bonding between F and alumina surface is attributed to the hybridization between F-p orbitals and Al-s,p orbitals. In addition, the alumina surfaces are hydroxylated with water molecules when exposing to the atmosphere, exhibiting a great impact on the performance of purifying F element. Results suggest that the hydroxylated θ-Al2O3 (010) adsorbs F with the smallest adsorption energy than other hydroxylated alumina surfaces, exhibiting the lowest performance of purifying F element.

To solve the problems of high energy consumption, low efficiency and short service life of conventional rare earth reduction cells, a 20 kA new rare earth reduction cell (NRERC) was presented. The effects of the anode-cathode distance (ACD) and electrolyte height (EH) on the thermo-electrical behavior of the NRERC were studied by ANSYS. The results illustrate that the cell voltage drop (CVD) and the temperature will rise with a similar tendency when the ACD increases. Also, the temperature rises gradually with EH, but the CVD decreases. Ultimately, when the ACD is 115 mm and the EH is 380 mm, the CVD is 4.61 V and the temperature is 1109.8 °C. Under these conditions, the thermal field distribution is more reasonable and the CVD is lower, which is beneficial to the long service life and low energy consumption of the NRERC.

The effects of cryolite ratio (CR = NaF/AlF3) on the ionic structure, shear viscosity, and thermal conductivity of NaF-AlF3 molten salts were investigated by non-equilibrium molecular dynamics (NEMD) with Buckingham potential model. With the augment of CR, the [AlF6](3-) groups gradually decrease but [AlF5](2-) and [AlF4]- increase. The [AlF5](2-) groups are the dominant species at CR <= 2.4. The average bond length of Al-F clusters follows the order of [AlF6](3-)> [AlF5](2-)> [AlF4]-. The viscosity of NaF-AlF3 molten salt changes from 1.61 to 2.57 mPa:s with the increase of CR from 2.0 to 3.0. The molten salt shows great heat conduction when 2.4 <= CR <= 2.8. and thermal conductivity is about 0.81-1.28 W/(m:K). The simulation results are in good agreement with the experimental data available in the literature.

In the present study, the impact of surface roughness on the wettability behavior of Al droplets has been investigated via molecular dynamics (MD) simulations. In this work, amorphous carbon (AC) and graphite substrates with different depths and widths were considered. The results show that the increased width of grooves causes the transition of the wetting state from Cassie to Wenzel. Thermodynamic property analysis results indicate that the solid-liquid adhesion and the work done for the removal of the Al droplet from the solid surface decrease as the roughness increases. However, the adhesion in the Wenzel wetting state is better than that in the Cassie wetting state. Therefore, the contact angle increases with the increased roughness in the Cassie wetting systems, while in the Wenzel wetting systems, the contact angle is less than that in other rough systems. In addition, due to the heterogeneity of the surfaces, the density of Al droplets in the solid-liquid interface is decreased with the increased roughness. The anisotropic spreading of Al liquid can be explained by the MSD curves along the X and Y directions.

•DFT calculations were employed to study the adsorption of F/Cl on doped graphene.•F and Cl atoms can strongly adsorb on PG, VG and doped graphene.•F and Cl atoms preferentially adsorbed on the Top site of graphene.•F and Cl atoms prefer to adsorption on Al doped-graphene.•The co-adsorption of H2O and F/Cl atom has few impact on the adsorption of F/Cl.

In recent years, the tungsten-copper composite has attracted much attention due to many excellent performances. In the present work, the wetting behaviors of Cu droplets on W (1 0 0), (1 1 0) and (1 1 1) surfaces had been investigated by molecular dynamics (MD) simulations. Results show that a precursor film with single atomic layer will form on W surfaces. The precursor films showed the anisotropic diffusion due to the difference of diffusion barrios along different directions. Only on the W (1 1 0) surface, the precursor film presents a circle. The precursor film is an oval shape on the W (1 0 0) surface and that is similar to the shape of a triangle on W (1 1 1) surface but the shape of Cu droplet on the W (1 1 1) surface is a circle. The Cu droplet on the W (1 1 1) has the best wettability than others due to the effects of both precursor films and the alloying effect. The Cu droplet on the W (1 1 0) surface has the worst wettability. In addition, the potential of mean force (PMF) analysis was applied to further character the wettability. Besides, the effect of both temperature and substrate structure on wettability was also studied, which shows that the wettability increases with the increased temperature. Moreover, the grooved surface can greatly advance the wetting kinetics along the grooves direction, but in the perpendicular direction, the effect is opposite.

Nowadays, low-temperature aluminium electrolytes are reported to have good prospects for application in the industrial process of aluminium production. In this paper, low-temperature electrolytes containing potassium cryolite and sodium cryolite with a cryolite ratio of 1.3 were investigated by using first-principles molecular dynamics simulation. This calculation reproduces the ionic structure of low-temperature 1.3(KF + NaF)-AlF3 electrolytes, indicating that [AlF4]-, [AlF5]2- and [AlF6]3- are the fundamental aluminum-fluoro clusters and [AlF5]2- is the predominant species. The calculated results for the ionic structure indicate that molten 1.3(KF + NaF)-AlF3 electrolytes have a high ionic polymerization degree, which is unfavorable for the transport properties of low-temperature 1.3(KF + NaF)-AlF3 electrolytes. Fortunately, increasing the mass fraction of NaF can effectively reduce the polymerization degree of ionic structure and thus improve the ionic conductivity of low-temperature 1.3(KF + NaF)-AlF3 electrolytes, which is an important guiding factor for the component selection of low-temperature electrolytes in future. Also, DFT calculations were adopted to further analyse the small aluminum-fluoro complexes. The calculated Raman spectrum of the aluminum-fluoro complexes is excellently consistent with literature results. Our calculated ionic conductivity falls in between the estimated value of the empirical equation of different literature studies, demonstrating that our results may be more precise than the literature results. This further proves the practicability of our modified N-E equation.

We used the first-principles molecular dynamics simulations combined with the interatomic potential molecular dynamics to study the ionic structure and transport properties of KF-NaF-AlF3 fused salt. Simulation results show that the ionic structure of KF-NaF-AlF3 fused salt is principally dominated by the distorted five-coordinated [AlF5]2- and six-coordinated [AlF6]3- groups. When melting to a liquid, a part of the six-coordinated [AlF6]3- group dissociated into the four-coordinated [AlF4]- and five-coordinated [AlF5]2- groups. Four, five and six-coordinated aluminum-fluoro complexes coexist in KF-NaF-AlF3 fused salt, while the tetrahedral [AlF4]- groups are relatively rare. The content of the bridging fluorine atom is relatively small, about 5-11%, which indicates that the polymerization degree of the ionic structure of the KF-NaF-AlF3 fused salt system is lower. The KF-NaF-AlF3 fused salt has better liquidity and ionic conductivity due to the high self-diffusion coefficients of all particles in the fused salt system. KF can effectively break the F atom bridges, which reduces the polymerization degree of the ionic structure of the fused salt system and increases its ionic conductivity.

Molecular dynamics simulation had been performed to investigate the wetting properties of Al droplets on amorphous carbon surfaces and graphite surfaces. The effects of temperature, graphitization of substrate and roughness were considered. Our results show that the contact angles can be improved effectively with the increased temperature. Furthermore, the Al droplet on graphite surface has a better wettability than that on amorphous carbon surface. Similarly, the contact angle will also reduce with the increased degree of graphitization and the wetting state will change from the transition wetting state to the Cassie state when the roughness increases. In addition to the contact angles on the rough surface, the remaining contact angles are less than 90°, which is different from the previous reports. The free energy and thermodynamic properties analysis were applied to character the solid-liquid interface properties and explain the wettability. Another interesting finding is that the study reveals the reason of the poor wettability between Al liquid and cathode carbon blocks of aluminum electrolytic cell. These findings improve our understandings of the wetting behaviors of Al droplets on cathode carbon block surfaces at the atomistic level, which is profitable to develop the wettable cathode materials for aluminum electrolysis.

Studying the coalescence and wetting mechanisms of Al liquid on amorphous carbon and graphene from atomic level.