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In this paper, a Ni0.36Al0.10Cu0.30Fe0.24 metallic inert anode was proposed and the electrochemical behaviors were studied in molten K2CO3-Na2CO3 at 1023 K by polarization curves and Tafel plots. The results indicated that Ni0.36Al0.10Cu0.30Fe0.24 alloy was stable in carbonate due to the formation of a passivation film on the surface. The film was mainly composed of NiFe2O4 and Al2O3 with a dense structure, which inhibited further corrosion of anode. Moreover, oxygen gas and Fe-Ni alloy have been successfully generated through electrolysis with NiO-Fe2O3 pellet as cathode and Ni0.36Al0.10Cu0.30Fe0.24 alloy as anode under a potential of 1.9 V for 24 hours. Ni0.36Al0.10Cu0.30Fe0.24 alloy exhibited bright prospect as a potential candidate of inert anode for green metallurgical process. [ABSTRACT FROM AUTHOR]

A new Al-ion battery based on an affordable and nontoxic liquid electrolyte made from molten AlCl3/urea was assembled. As the cathode material, natural graphite shows two well-defined discharge voltage plateaus at about 1.9 and 1.5 V with a high specific capacity of 93 mA h g−1 and excellent coulombic efficiency (＞99%). The attractive capacity (about 78 mA h g−1) is retained even at a high current density of 1000 mA g−1. Moreover, no faster fading in capacity is observed after 500 cycles. This electrolyte could provide a new system for Al ion batteries, which can be used for large scale energy storage, owing to its cost advantages, high-rate capability and durability. [ABSTRACT FROM AUTHOR]

An aluminum-ion asymmetric supercapacitor was assembled utilizing a cathode made of multi-walled carbon nanotubes (MWCNTs) in an ionic liquid 1-ethyl-3-methylimidazolium chloride ([EMIm]Cl)-based electrolyte. Two types of energy-storage mechanisms, that is, electrochemical double-layer capacitance (adsorption/desorption of AlCl4− on the surface) and limited intercalation pseudocapacitance (intercalation/deintercalation of AlCl4− in the graphite layer) at low current density, were observed and characterized. Meanwhile, the specific capacitance and cyclic stability of this supercapacitor were also evaluated by using galvanostatically charging-discharging. The result demonstrates that the specific capacitance decreases with increasing current density, which corresponds to the two types of energy-storage mechanisms of this device. The corresponding retention rate of this device after 3500 cycles at current density of 0.4 A g−1 was 82.4 %, which shows good cyclic stability. [ABSTRACT FROM AUTHOR]

Producing graphene through the electrochemical reduction of CO2 remains a great challenge, which requires precise control of the reaction kinetics, such as diffusivities of multiple ions, solubility of various gases, and the nucleation/growth of carbon on a surface. Here, graphene was successfully created from the greenhouse gas CO2 using molten salts. The results showed that CO2 could be effectively fixed by oxygen ions in CaCl2-NaCl-CaO melts to form carbonate ions, and subsequently electrochemically split into graphene on a stainless steel cathode; O2 gas was produced at the RuO2-TiO2 inert anode. The formation of graphene in this manner can be ascribed to the catalysis of active Fe, Ni, and Cu atoms at the surface of the cathode and the microexplosion effect through evolution of CO in between graphite layers. This finding may lead to a new generation of proceedures for the synthesis of high value-added products from CO2, which may also contribute to the establishment of a low-carbon and sustainable world. [ABSTRACT FROM AUTHOR]

The synthesis and electrochemical performance derived from NaHTi3O7 have been investigated for use as an anode material for sodium-ion batteries. NaHTi3O7 nanotubes were fabricated by a hydrothermal method. Galvanostatic charge/discharge measurements were performed in a voltage range of 0.01–2.5 V vs. Na+/Na at different current densities, using the as-prepared NaHTi3O7 nanotubes as the working electrode. Typically, the initial discharge and charge capacities of NaHTi3O7 nanotubes were 381.80 mA h g−1 and 242.82 mA h g−1, respectively, at a current density of 20 mA g−1, and still retained a high specific capacity of 105.32 mA h g−1 and 100.65 mA h g−1 after 100 cycles. The electrode also exhibits outstanding rate capability with a reversible capacity as high as 300.95 mA h g−1 and 209.10 mA h g−1 at current densities of 50 mA g−1 and 100 mA g−1, respectively. The excellent electrochemical stability and high specific capacity of these nanostructured materials have been attributed to the three-dimensional flower-like morphology of NaHTi3O7 nanotubes. All of the findings demonstrate that NaHTi3O7 nanotubes have steady cycling performance and environmental and cost friendliness for use in next generation secondary batteries of sodium-ion batteries. [ABSTRACT FROM AUTHOR]

Due to their low cost, high abundance and eco-friendly features, Na-ion batteries are becoming alternative choices for rechargeable batteries, especially in large scale applications. Generally, the well-crystallized materials have many advantages over amorphous materials, such as long cycle life, high rate performance and other electrochemical properties. However, the amorphous FePO4 we report here exhibits outstanding cycling stability and rate performance which are derived from its amorphous nature and wafer-like porous morphology. A comparative study of amorphous and crystalline FePO4 has been carried out as cathode materials for Na-ion batteries. The present study not only reports a synthetic method which is facile, inexpensive, and scalable for mass production, but it also motivates further exploration of other amorphous materials for Na-ion batteries. [ABSTRACT FROM AUTHOR]

The titleompound is prepared by electro-deoxidation of a TiO2/SiO2 composite in molten CaCl2 electrolyte at 900 °C. [ABSTRACT FROM AUTHOR]

Understanding the interfacial dynamics during operation is critical for electrochemistry to make great advancements. However, breakthroughs on this topic under extreme conditions are very scarce. Here, as an example, we employ operando Raman spectroscopy to decode the interfacial dynamics of titanium electrolysis using a tailored instrument. Direct spectral evidence not only confirms the two-step reduction pathway and the key intermediate (TiF 5 2- ) in molten fluorides with high-temperature and strong-corrosion conditions but also unravels the origins of the undesirable shuttling effect of TiF 5 2- , which are the sluggish reduction kinetics and outward diffusion behavior of TiF 5 2- . Moreover, an insightful atomic scenario of the electric double layer (EDL) under varied potentials has been established. These quantitative understandings guide us to design economical-feasible regulation protocols─the rational combination of a high-concentration, low-valence Ti-ion electrolyte with appropriate applied potential. Impressively, the current efficiency is greatly promoted from 27.7 to 81.8% using our proposed protocols. Finally, this work also demonstrates a bottom-up technological research paradigm for extreme electrochemistry based on mechanism insights rather than phenomenological findings, which will accelerate the advancement of extreme electrochemistry.

Tungsten coatings have unique properties such as high melting points and hardness and are widely used in the nuclear fusion and aviation fields. In experiments, compared to pure Na 2 WO 4 molten salt, electrolysis with Na 2 WO 4 -WO 3 molten salt results in a lower deposition voltage. Herein, an investigation combining experimental and computational approaches was conducted, involving molecular dynamics simulations with deep learning, high-temperature in situ Raman spectroscopy and activation strain model analysis. The results indicated that the molten salt system's behaviour, influenced by migration and polarization effects, led to increased formation of Na 2 W 2 O 7 in the Na 2 WO 4 -WO 3 molten salt, which has a lower decomposition voltage and subsequently accelerated the cathodic deposition of tungsten. We analyzed the mechanism of the effect of the electric field on the Na 2 W 2 O 7 structure based on the bond strength and electron density. This research provides crucial theoretical support for the effect of electric field on tungsten in molten salt and demonstrates the feasibility of using machine learning-based DPMD methods in simulating tungsten-containing molten salt systems.

Nearly half of the elements in the periodic table are extracted, refined, or plated using electrodeposition in high-temperature melts. However, operando observations and tuning of the electrodeposition process during realistic electrolysis operations are extremely difficult due to severe reaction conditions and complicated electrolytic cell, which makes the improvement of the process very blind and inefficient. Here, we developed a multipurpose operando high-temperature electrochemical instrument that combines operando Raman microspectroscopy analysis, optical microscopy imaging, and a tunable magnetic field. Subsequently, the electrodeposition of Ti-which is a typical polyvalent metal and generally shows a very complex electrode process-was used to verify the stability of the instrument. The complex multistep cathodic process of Ti in the molten salt at 823 K was systematically analyzed by a multidimensional operando analysis strategy involving multiple experimental studies, theoretical calculations, etc. The regulatory effect and its corresponding scale-span mechanism of the magnetic field on the electrodeposition process of Ti were also elucidated, which would be inaccessible with existing experimental techniques and is significant for the real-time and rational optimization of the process. Overall, this work established a powerful and universal methodology for in-depth analysis of high-temperature electrochemistry.

Intermediate temperature NaCl-AlCl 3 -based Al-ion batteries are considered as a promising stationary energy storage system due to their low cost, high safety, etc. However, such a cheap electrolyte has a critical feature, i.e., strong corrosion, which results in the short cycle life of the conventional Al-metal anode and also limits the development of the NaCl-AlCl 3 -based Al-ion batteries. A noncorrosive electrolyte may be a good choice for addressing the above challenge, while it is difficult to obtain the electrolyte that has advantages of both noncorrosion and low cost. Therefore, here, we report a Ga-metal anode in the affordable NaCl-AlCl 3 electrolyte for constructing a long-life stationary Al-ion energy storage system. This featured liquid metal anode shows good alloying and dealloying processes between metallic Ga and Al, as well as renders superior stability of the interface between the electrolyte and the anode (e.g., smoothly running for over 580 h at 2 mA cm -2 ). No-corrosion and no-pulverization problems appear in this novel liquid/liquid interface. Those advantages demonstrate that the liquid Ga-metal anode has a great promise for the improvement of the NaCl-AlCl 3 -based Al-ion batteries for large-scale stationary energy storage applications.

Producing graphene through the electrochemical reduction of CO2 remains a great challenge, which requires precise control of the reaction kinetics, such as diffusivities of multiple ions, solubility of various gases, and the nucleation/growth of carbon on a surface. Here, graphene was successfully created from the greenhouse gas CO2 using molten salts. The results showed that CO2 could be effectively fixed by oxygen ions in CaCl2-NaCl-CaO melts to form carbonate ions, and subsequently electrochemically split into graphene on a stainless steel cathode; O2 gas was produced at the RuO2-TiO2 inert anode. The formation of graphene in this manner can be ascribed to the catalysis of active Fe, Ni, and Cu atoms at the surface of the cathode and the microexplosion effect through evolution of CO in between graphite layers. This finding may lead to a new generation of proceedures for the synthesis of high value-added products from CO2, which may also contribute to the establishment of a low-carbon and sustainable world., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)