Due to the unique physical and chemical properties,rare earth elements(REEs)play a significant role in the high-tech field.In the past few decades,the rare earth reserve in China has been gradually decreasing and more...Due to the unique physical and chemical properties,rare earth elements(REEs)play a significant role in the high-tech field.In the past few decades,the rare earth reserve in China has been gradually decreasing and more pressure has been exerted on the global rare earth supply for the increasing demand of REEs,which indicates that it is essential to recycle secondary resources to meet the rare earth demand.As for rare earth molten salt electrolytic slag(REMES),although its high rare earth content has potential huge economic value,its high fluorine content of approximately 10 wt%-20 wt%can pollute the environment.Three methods are used to treat REMES.Hydro metallurgical and pyro-hydrometallurgical methods have gotten a big success for solving most of the hydrometallurgical problems,while some problems,like long route and waste water,need to be solved.Vacuum distillation is a new and promising method with a short process due to its harmlessness and high efficiency,but has shortcomings such as high energy consumption and material adaptability.This review presents these above three treatment methods,and the challenges and chances of using the recovery technique of REMES in an environmentally friendly way.展开更多
The alumina solubility in the title system within the composition range of KR{m（K3AlF6）/[m（K3AlF6）＋ m（Na3AlF6）]} 10%―50%, a ternary Na3AlF6-K3AlF6-AlF3 molten system with 23%―29%（mass fraction） AlF3 was inv...The alumina solubility in the title system within the composition range of KR{m（K3AlF6）/[m（K3AlF6）＋ m（Na3AlF6）]} 10%―50%, a ternary Na3AlF6-K3AlF6-AlF3 molten system with 23%―29%（mass fraction） AlF3 was investigated by measuring the mass loss of a rotating sintered corundum disc. And the following empirical equation was derived when superheat degree was no more than 60 °C： w（Al2O3）sat=A×（T/1000）B, where A= –1.85774＋ 26.754234w（AlF3）–0.3683–0.00783KR2.363＋0.010266KR2.3048＋0.7902w（AlF3）0.00652, B=112.4625–53.2567w（AlF3）0.4236＋ 5.1079w（AlF3）0.9241＋0.01542w（AlF3）1.3540. Considering both higher alumina solubility and not too high superheat de gree are required, alumina solubility of different compositions at not the same temperature but the same superheat degree was studied, which will be more industrial helpful for selecting prospective compositions. The results show that the composition deserved to be further tested in lower temperature cells is 10%―30% KR and 23%―26%（mass fraction） AlF3.展开更多
NiCl_(2) with high theoretical voltage and thermal decomposition temperature attracts much attention as cathode material for thermal batteries with the requirement of high power density, high energy density and long w...NiCl_(2) with high theoretical voltage and thermal decomposition temperature attracts much attention as cathode material for thermal batteries with the requirement of high power density, high energy density and long work time. Unfortunately, the practical utilization of thermal batteries with NiCl_(2) cathode is limited by their poor electrochemical performance under large current, even with the conventional Li F-Li Cl-Li Br all-lithium molten salt electrolyte which proposes ultrahigh lithium ion conductivity. In this work, an unexpected ionic exchange reaction between NiCl_(2) and Li Br in Li F-Li Cl-Li Br was found, which would be the main reason for the poor electrochemical behavior of thermal batteries with NiCl_(2) cathode and Li F-Li Cl-Li Br molten salt. On this basis, Li F-Li Cl-Li_(2)SO_(4), another all-lithium molten salt free of Li Br, was investigated as the new electrolyte for NiCl_(2) cathode. For the single cell of Li(Si)/Li F-Li Cl-Li_(2)SO_(4)/NiCl_(2), a discharge capacity of 377 mA h g^(-1)(with a cut-off voltage of 1.2 V) was achieved with large current density(500 mA cm^(-2)) applied at 520℃, which is almost twice of that of Li(Si)/Li F-Li Cl-Li Br/NiCl_(2)(190 mA h g^(-1)) at the same conditions.展开更多
The electrolytic codeposition of lanthanum-cobalt in the melt consisting of urea-NaCl-NaAc-CoCl2-LaCl3 was studied by means of cyclic voltammetry, electron probe analyser, X-ray diffraction. Cathodic potential, curren...The electrolytic codeposition of lanthanum-cobalt in the melt consisting of urea-NaCl-NaAc-CoCl2-LaCl3 was studied by means of cyclic voltammetry, electron probe analyser, X-ray diffraction. Cathodic potential, current density, La3+/Co2+ molar ratio in the melt and the electrode substrates all exercise influence on the content of lanthanum deposied. The deposites consist of cobalt and lanthanum, but they don't form any intermetallic compound.展开更多
A new process was proposed to extract rare earth elements(REEs),Li and F from electrolytic slag of rare earth molten salt by synergistic roasting and acid leaching.Firstly,the thermodynamic analysis of roasting reacti...A new process was proposed to extract rare earth elements(REEs),Li and F from electrolytic slag of rare earth molten salt by synergistic roasting and acid leaching.Firstly,the thermodynamic analysis of roasting reaction was carried out,then the effects of roasting factors on leaching REEs,Li and F in slag were investigated.In additions,the mineral phase and morphology of molten salt slag,roasting slag and acid leaching slag were characterized,and the migration mechanism of REES,Li and F minerals in roasting and leaching process was analyzed.The results show that the synergistic roasting and activation of molten salt slag by CaO and Al_(2)(SO_(4))_(3)are thermodynamically feasible.The optimum roasting conditions are as follows:molten salt slag of 20 g,Al_(2)(SO_(4))_(3)of 31.25 g and CaO of 6.25 g,roasting temperature of 1173.15 K and reaction time of 2 h,under this condition,the leaching rates of Nd,Pr,Gd,Li and F are 92.47%,91.56%,91.08%,96.69%and 96.8%,respectively.X-ray powder diffraction(XRD)and scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDS)analysis show that the rare earth fluoride(REF3)in molten salt slag transforms into soluble rare earth oxide(REO)after roasting and activation.After leaching,the leaching residue is mainly strip CaSO4,indicating that REES,Li and F can be fully extracted from molten salt slag.展开更多
Lithium-iodine(Li-I_(2))battery exhibits high potential to match with high-rate property and large energy density.However,problems of the system,such as evident sublimation of iodine elements,dissolution of iodine spe...Lithium-iodine(Li-I_(2))battery exhibits high potential to match with high-rate property and large energy density.However,problems of the system,such as evident sublimation of iodine elements,dissolution of iodine species in electrolyte,and lithium anode corrosion,prevent the practical use of rechargeable Li-I_(2)batteries.In this work,a molten Li-I_(2)typical cell design which has distinct advantages based on the solid-state garnet electrolyte with the eutectic iodate cathode is firstly developed.The U-shaped ceramic electrolyte tube can separate Li anode from the eutectic iodate cathode,so as to better tackle the above-mentioned inherent challenges for the liquid electrolyte systems.Without self-discharging and lithium anode corrosion,this solid-state battery system demonstrates high safety margin and excellent electrochemical performance.Also,the simple battery structure also indicates the easy assembly process and recycling of electrode materials.With the cathode loading of 593 mg in a single cell,an energy density of~506.7 Wh·kg^(-1)was achieved at 1 C and a long-term cycling life for 2,000 cycles also displays negligible capacity decay.展开更多
基金Project supported by the National Key R&D Program of China(2020YFC1909003)。
文摘Due to the unique physical and chemical properties,rare earth elements(REEs)play a significant role in the high-tech field.In the past few decades,the rare earth reserve in China has been gradually decreasing and more pressure has been exerted on the global rare earth supply for the increasing demand of REEs,which indicates that it is essential to recycle secondary resources to meet the rare earth demand.As for rare earth molten salt electrolytic slag(REMES),although its high rare earth content has potential huge economic value,its high fluorine content of approximately 10 wt%-20 wt%can pollute the environment.Three methods are used to treat REMES.Hydro metallurgical and pyro-hydrometallurgical methods have gotten a big success for solving most of the hydrometallurgical problems,while some problems,like long route and waste water,need to be solved.Vacuum distillation is a new and promising method with a short process due to its harmlessness and high efficiency,but has shortcomings such as high energy consumption and material adaptability.This review presents these above three treatment methods,and the challenges and chances of using the recovery technique of REMES in an environmentally friendly way.
基金Supported by the National Basic Research Program of China(No.2005CB623703)the National High-Tech Research and Development Program of China(No.2008AA030503)
文摘The alumina solubility in the title system within the composition range of KR{m（K3AlF6）/[m（K3AlF6）＋ m（Na3AlF6）]} 10%―50%, a ternary Na3AlF6-K3AlF6-AlF3 molten system with 23%―29%（mass fraction） AlF3 was investigated by measuring the mass loss of a rotating sintered corundum disc. And the following empirical equation was derived when superheat degree was no more than 60 °C： w（Al2O3）sat=A×（T/1000）B, where A= –1.85774＋ 26.754234w（AlF3）–0.3683–0.00783KR2.363＋0.010266KR2.3048＋0.7902w（AlF3）0.00652, B=112.4625–53.2567w（AlF3）0.4236＋ 5.1079w（AlF3）0.9241＋0.01542w（AlF3）1.3540. Considering both higher alumina solubility and not too high superheat de gree are required, alumina solubility of different compositions at not the same temperature but the same superheat degree was studied, which will be more industrial helpful for selecting prospective compositions. The results show that the composition deserved to be further tested in lower temperature cells is 10%―30% KR and 23%―26%（mass fraction） AlF3.
基金supported by the National Nature Science Associate Foundation (NSAF) of China (Grant No. U1930208)the Laboratory of Precision Manufacturing Technology+2 种基金China Academy of Engineering Physics (Grant No. ZD17006,ZM18002)the National Natural Science Foundation of China (Grant Nos. 11804312 and 21703215)the Science and Technology Innovation Foundation of Institute of Electronic Engineering (Grant No. S201904)。
文摘NiCl_(2) with high theoretical voltage and thermal decomposition temperature attracts much attention as cathode material for thermal batteries with the requirement of high power density, high energy density and long work time. Unfortunately, the practical utilization of thermal batteries with NiCl_(2) cathode is limited by their poor electrochemical performance under large current, even with the conventional Li F-Li Cl-Li Br all-lithium molten salt electrolyte which proposes ultrahigh lithium ion conductivity. In this work, an unexpected ionic exchange reaction between NiCl_(2) and Li Br in Li F-Li Cl-Li Br was found, which would be the main reason for the poor electrochemical behavior of thermal batteries with NiCl_(2) cathode and Li F-Li Cl-Li Br molten salt. On this basis, Li F-Li Cl-Li_(2)SO_(4), another all-lithium molten salt free of Li Br, was investigated as the new electrolyte for NiCl_(2) cathode. For the single cell of Li(Si)/Li F-Li Cl-Li_(2)SO_(4)/NiCl_(2), a discharge capacity of 377 mA h g^(-1)(with a cut-off voltage of 1.2 V) was achieved with large current density(500 mA cm^(-2)) applied at 520℃, which is almost twice of that of Li(Si)/Li F-Li Cl-Li Br/NiCl_(2)(190 mA h g^(-1)) at the same conditions.
文摘The electrolytic codeposition of lanthanum-cobalt in the melt consisting of urea-NaCl-NaAc-CoCl2-LaCl3 was studied by means of cyclic voltammetry, electron probe analyser, X-ray diffraction. Cathodic potential, current density, La3+/Co2+ molar ratio in the melt and the electrode substrates all exercise influence on the content of lanthanum deposied. The deposites consist of cobalt and lanthanum, but they don't form any intermetallic compound.
基金Project supported by the National Key R&D Program"Solid Waste Recycling"Key Project(2020YFC1909000,2020YFC1909003)the National Natural Science Foundation of China(52064019)the Key Fund of Jiangxi Provincial Department of Science and Technology(2019ACBL20015)。
文摘A new process was proposed to extract rare earth elements(REEs),Li and F from electrolytic slag of rare earth molten salt by synergistic roasting and acid leaching.Firstly,the thermodynamic analysis of roasting reaction was carried out,then the effects of roasting factors on leaching REEs,Li and F in slag were investigated.In additions,the mineral phase and morphology of molten salt slag,roasting slag and acid leaching slag were characterized,and the migration mechanism of REES,Li and F minerals in roasting and leaching process was analyzed.The results show that the synergistic roasting and activation of molten salt slag by CaO and Al_(2)(SO_(4))_(3)are thermodynamically feasible.The optimum roasting conditions are as follows:molten salt slag of 20 g,Al_(2)(SO_(4))_(3)of 31.25 g and CaO of 6.25 g,roasting temperature of 1173.15 K and reaction time of 2 h,under this condition,the leaching rates of Nd,Pr,Gd,Li and F are 92.47%,91.56%,91.08%,96.69%and 96.8%,respectively.X-ray powder diffraction(XRD)and scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDS)analysis show that the rare earth fluoride(REF3)in molten salt slag transforms into soluble rare earth oxide(REO)after roasting and activation.After leaching,the leaching residue is mainly strip CaSO4,indicating that REES,Li and F can be fully extracted from molten salt slag.
文摘Lithium-iodine(Li-I_(2))battery exhibits high potential to match with high-rate property and large energy density.However,problems of the system,such as evident sublimation of iodine elements,dissolution of iodine species in electrolyte,and lithium anode corrosion,prevent the practical use of rechargeable Li-I_(2)batteries.In this work,a molten Li-I_(2)typical cell design which has distinct advantages based on the solid-state garnet electrolyte with the eutectic iodate cathode is firstly developed.The U-shaped ceramic electrolyte tube can separate Li anode from the eutectic iodate cathode,so as to better tackle the above-mentioned inherent challenges for the liquid electrolyte systems.Without self-discharging and lithium anode corrosion,this solid-state battery system demonstrates high safety margin and excellent electrochemical performance.Also,the simple battery structure also indicates the easy assembly process and recycling of electrode materials.With the cathode loading of 593 mg in a single cell,an energy density of~506.7 Wh·kg^(-1)was achieved at 1 C and a long-term cycling life for 2,000 cycles also displays negligible capacity decay.
