Presence of Li Clusters in Molten LiCl-Li

A Porous Li-Al Alloy Anode toward High-Performance Sulfide-Based All-Solid-State Lithium Batteries

Compared to lithium (Li) anode, the alloy/Li-alloy anodes show more compatible with sulfide solid electrolytes (SSEs), and are promising candidates for practical SSE-based all-solid-state Li batteries (ASSLBs). In this work, a porous Li-Al alloy (LiAl-p) anode is crafted using a straightforward mechanical pressing method. Various characterizations confirm the porous nature of such anode, as well as rich oxygen species on its surface. To the best knowledge, such LiAl-p anode demonstrates the best room temperature cell performance in comparison with reported Li and alloy/Li-alloy anodes in SSE-based ASSLBs. For example, the LiAl-p symmetric cells deliver a record critical current density of 6.0 mA cm-2 and an ultralong cycling of 5000 h; the LiAl-p|LiNi0.8Co0.1Mn0.1O2 full cells achieve a high areal capacity of 11.9 mAh cm-2 and excellent durability of 1800 cycles. Further in situ and ex situ experiments reveal that the porous structure can accommodate volume changes of LiAl-p and ensure its integrity during cycling; and moreover, a robust Li inorganics-rich solid electrolyte interphase can be formed originated from the reaction between SSE and surface oxygen species of LiAl-p. This study offers inspiration for designing high-performance alloy anodes by focusing on designing special architecture to alleviate volume change and constructing stable interphase.

Li deposited on LiCl: an efficient reducing agent

Lithium was deposited onto lithium chloride powder in a ∼5% weight/weight ratio and demonstrated to be an effective reducing reagent.

Design and performance of high-temperature furnace and cell holder for in situ spectroscopic, electrochemical, and radiolytic investigations of molten salts

To facilitate the development of molten salt reactor technologies, a fundamental understanding of the physical and chemical properties of molten salts under the combined conditions of high temperature and intense radiation fields is necessary. Optical spectroscopic (UV-Vis-near IR) and electrochemical techniques are powerful analytical tools to probe molecular structure, speciation, thermodynamics, and kinetics of solution dynamics. Here, we report the design and fabrication of three custom-made apparatus: (i) a multi-port spectroelectrochemical furnace equipped with optical spectroscopic and electrochemical instrumentation, (ii) a high-temperature cell holder for time-resolved optical detection of radiolytic transients in molten salts, and (iii) a miniaturized spectroscopy furnace for the investigation of steady-state electron beam effects on molten salt speciation and composition by optical spectroscopy. Initial results obtained with the spectroelectrochemical furnace (i) and high-temperature cell holder (ii) are reported.

Revealing 3D Morphological and Chemical Evolution Mechanisms of Metals in Molten Salt by Multimodal Microscopy

Growing interest in molten salts as effective high-temperature heat-transfer fluids for sustainable energy systems drives a critical need to fundamentally understand the interactions between metals and molten salts. This work utilizes the multimodal microscopy methods of synchrotron X-ray nanotomography and electron microscopy to investigate the 3D morphological and chemical evolution of two-model systems, pure nickel metal and Ni-20Cr binary alloy, in a representative molten salt (KCl-MgCl₂ 50-50 mol %, 800 °C). In both systems, unexpected shell-like structures formed because of the presence of more noble tungsten, suggesting a potential route of using Ni-W alloys for enhanced molten-salt corrosion resistance. The binary alloy Ni-20Cr developed a bicontinuous porous structure, reassembling functional porous metals manufactured by dealloying. This work elucidates better mechanistic understanding of corrosion in molten salts, which can contribute to the design of more reliable alloys for molten salt applications including next-generation nuclear and solar power plants and opens the possibility of using molten salts to fabricate functional porous materials.

Minimising oxygen contamination through a liquid copper-aided group IV metal production process

This paper demonstrates for the first time the fabrication of Zr-Cu alloy ingots from a Hf- free ZrO₂ precursor in a molten CaCl₂ medium to recover nuclear-grade Zr. The reduction of ZrO₂ in the presence of CaO was accelerated by the formation of Ca metal in the intermediate stage of the process. Tests conducted with various amounts of ZrO₂ indicate that the ZrO₂ was reduced to the metallic form at low potentials applied at the cathode, and the main part of the zirconium was converted to a CuZr alloy with a different composition. The maximum oxygen content values in the CuZr alloy and Zr samples upon using liquid Cu were less than 300 and 891 ppm, respectively. However, Al contamination was observed in the CuZr during the electroreduction process. In order to solve the Al contamination problem, the fabrication process of CuZr was performed using the metallothermic reduction process, and the produced CuZr was used for electrorefining. The CuZr alloy was further purified by a molten salt electrorefining process to recover pure nuclear-grade Zr in a LiF-Ba₂ZrF₈-based molten salt, the latter of which was fabricated from a waste pickling acid of a Zr clad tube. After the electrorefining process, the recovered Zr metal was fabricated into nuclear-grade Zr buttons through arc melting following a salt distillation process. The results suggest that the removal of oxygen from the reduction product is a key reason for the use of a liquid CaCu reduction agent.

Spontaneous colloidal metal network formation driven by molten salt electrolysis

The molten salt-based direct reduction process for reactive solid metal outperforms traditional pyrometallurgical methods in energy efficiency. However, the simplity and rapidity of this process require a deeper understanding of the interfacial morphology in the vicinity of liquid metal deposited at the cathode. For the first time, here we report the time change of electrode surface on the sub-millisecond/micrometre scale in molten LiCl-CaCl₂ at 823 K. When the potential was applied, liquid Li-Ca alloy droplets grew on the electrode, and the black colloidal metal moved on the electrode surface to form a network structure. The unit cell size of the network and the number density of droplets were found to depend on the applied potential. These results will provide important information about the microscale mixing action near the electrode, and accelerate the development of metallothermic reduction of oxides.