Extraction Of LiCl From Low-Purity Chlorides Through Solid Electrolyte Towards High-Purity Li2CO3 Production.

Lithium carbonate (Li2CO3) plays a crucial role in advancing state-of-the-art lithium-ion batteries (LIBs) for efficient energy storage. The primary source of lithium is lithium-rich brines, which have complex compositions. Conventional extraction processes from brines involve cumbersome methods that often lead to emissions and/or large volumes of wastewater. To address these environmental challenges, a novel and eco-friendly lithium extraction process under ambient pressure is necessary. In this project, we developed an electrolytic process utilizing a NASICON-type solid-state electrolyte (LATP) to extract lithium chloride from low-purity sources at a temperature of 380 °C. To reduce the melting points of the lithium sources, ZnCl2 was introduced as a fluxing agent. The electrolytic process effectively separated Li+ from other coexisting ions, but resulted in their mixture with Zn2+. Subsequently, purification and carbonation processes were employed to produce high-purity Li2CO3 (98.9 %). We also obtained high-purity Zn(OH)2 (>99.9 %) as a value by-product. Despite the formation of color centers that caused the LATP disk to change from white to black during the electrolytic process, it exhibited sufficient ionic conductivity for successful lithium extraction. Our environmentally friendly approach offers a promising pathway for efficient and sustainable lithium extraction, contributing to the advancement of LIB technology for energy storage applications.

Cable-Car Electrocatalysis to Drive Fully Decoupled Water Splitting.

The increasing demand for clean energy conversion and storage has increased interest in hydrogen production via electrolytic water splitting. However, the simultaneous production of hydrogen and oxygen in this process poses a challenge in extracting pure hydrogen without using ionic conducting membranes. Researchers have developed various innovative designs to overcome this issue, but continuous water splitting in separated tanks remains a desirable approach. This study presents a novel, continuous roll-to-roll process that enables fully decoupled hydrogen evaluation reaction (HER) and oxygen evolution reaction (OER) in two separate electrolyte tanks. The system utilizes specially designed "cable-car" electrodes (CCE) that cycle between the HER and OER tanks, resulting in continuous hydrogen production with a purity of over 99.9% and Coulombic efficiency of 98% for prolonged periods. This membrane-free water splitting system offers promising prospects for scaled-up industrial-scale green hydrogen production, as it reduces the cost and complexity of the system, and allows for the use of renewable energy sources to power the electrolysis process, thus reducing the carbon footprint of hydrogen production.

Ice as Solid Electrolyte To Conduct Various Kinds of Ions.

Water, considered as a universal solvent to dissolve salts, has been extensively studied as liquid electrolyte in electrochemical devices. The water/ice phase transition at around 0 °C presents a common phenomenon in nature, however, the chemical and electrochemical behaviors of ice have rarely been studied. Herein, we discovered that the ice phase provides efficient ionic transport channels and therefore can be applied as generalized solid-state ionic conductor. Solid state ionic conducting ices (ICIs) of Li+ , Na+ , Mg2+ , Al3+ , K+ , Mn2+ , Fe2+ , Co2+ , Ni2+ , Cu2+ , and Zn2+ , frozen from corresponding sulphate solutions, exhibit ionic conductivities ranging from ≈10-7  S cm-1 (Zn2+ ) to ≈10-3  S cm-1 (Li+ ) at temperatures spanning from -20 °C to -5 °C. The discovery of ICIs opens new insight to design and fabrication of solid-state electrolytes that are simple, inexpensive, and versatile.

A painted layer for high-rate and high-capacity solid-state lithium-metal batteries.

A flake-graphite painted layer (an electron/ion dual-conductive framework) was prepared by a spraying method and the resulting improved interface contact between a lithium-metal anode and garnet electrolyte was demonstrated. Experiments showed that a large decrease in the interface resistance, from 3062 to 40 Ω cm2, was obtained. Besides a long cycling performance, the new interface also endured a tremendous Li volume change of 4.8 µm cm-2 in each stripping/plating step.

Ultralow-temperature photochemical synthesis of atomically dispersed Pt catalysts for the hydrogen evolution reaction.

Efficient control of nucleation is a prerequisite for the solution-phase synthesis of nanocrystals. Although the thermodynamics and kinetics of the formation of metal nanoparticles have been largely investigated, fully suppressing the nucleation in solution synthesis remains a major challenge due to the high surface free energy of isolated atoms. In this article, we largely decreased the reaction temperature for ultraviolet (UV) photochemical reduction of H2PtCl6 solution to -60 °C and demonstrated such a method as a fast and convenient process for the synthesis of atomically dispersed Pt. We showed that the ultralow-temperature reaction efficiently inhibited the nucleation process by controlling its thermodynamics and kinetics. Compared with commercial platinum/carbon, the synthesized atomically dispersed Pt catalyst, as a superior HER catalyst, exhibited a lower overpotential of approximately 55 mV at a current density of 100 mA cm-2 and a lower Tafel slope of 26 mV dec-1 and had higher stability in 0.5 M H2SO4.

Promoting a highly stable lithium metal anode by superficial alloying with an ultrathin indium sheet.

Lithium dendrite growth remains one of the major hindrances for its practical application. Here, we develop an ultrathin indium sheet to construct a stabilized lithium-rich hybrid anode with fast interfacial ion transport. The artificial alloy layer demonstrates an enhanced ionic conductivity that is an order of magnitude higher than that of the pristine solid electrolyte interphase. With the reduced diffusion barrier and improved charge transfer at the artificial interface, the hybrid anode realizes uniform lithium electrodeposition and considerable dendrite suppression. When coupled with LiNi5Co3Mn2O2 cathodes, this hybrid anode shows impressive reversibility.

Ice Melting to Release Reactants in Solution Syntheses.

Aqueous solution syntheses are mostly based on mixing two solutions with different reactants. It is shown that freezing one solution and melting it in another solution provides a new interesting strategy to mix chemicals and to significantly change the reaction kinetics and thermodynamics. For example, a precursor solution containing a certain concentration of AgNO3 was frozen and dropped into a reductive NaBH4 solution at about 0 °C. The ultra-slow release of reactants was successfully achieved. An ice-melting process can be used to synthesize atomically dispersed metals, including cobalt, nickel, copper, rhodium, ruthenium, palladium, silver, osmium, iridium, platinum, and gold, which can be easily extended to other solution syntheses (such as precipitation, hydrolysis, and displacement reactions) and provide a generalized method to redesign the interphase reaction kinetics and ion diffusion in wet chemistry.

Scalable Synthesis of 2D Si Nanosheets.

2D Si nanomaterials have attracted tremendous attention due to their novel properties and a wide range of potential applications from electronic devices to energy storage and conversion. However, high-quality and large-scale fabrication of 2D Si remains challenging. This study reports a room-temperature and one-step synthesis technique that leads to large-scale and low-cost production of Si nanosheets (SiNSs) with thickness ≈4 nm and lateral size of several micrometers, based on the intrinsic delithiation process of chemically leaching lithium from the Li13 Si4 alloy. Together with experimental results, a combination of theoretical modeling and atomistic simulations indicates that the formation of single SiNS arises from spontaneous delamination of nanosheets from their substrate due to delithiation-induced mismatch. Subsequently, the synthesized Si nanosheets evolve from amorphous to nanocrystalline to crystalline structures during annealing at different temperatures. It is demonstrated that these SiNSs possess unique mechanical properties, in particular ultralow friction, in contrast to their bulk counterparts.

Uniform Lithium Deposition Induced by Polyacrylonitrile Submicron Fiber Array for Stable Lithium Metal Anode.

The lithium dendrite growth and low Coulombic efficiency (CE) during lithium plating/striping cycles are the main obstacles for practical applications of lithium metal anode. Herein, we demonstrate that polyacrylonitrile (PAN) submicron fiber array could guide the lithium ions to uniformly disperse and deposit onto current collector. The PAN submicron fiber array nearly does not increase the volume of electrode with ultralow mass. By this simple design, we achieved stable cycling of lithium metal anode with an average CE of ∼97.4% for 250 cycles at a current density of 1 mA cm-2 with total Li capacity of 1 mAh cm-2.

Cycling of a Lithium-Ion Battery with a Silicon Anode Drives Large Mechanical Actuation.

Lithium-ion batteries with a Si anode can drive large mechanical actuation by utilizing the dramatic volume changes of the electrode during the charge/discharge cycles. A large loading of more than 10 MPa can be actuated by a LiFePO4 ||Si full battery with a rapid response while the driving voltage is lower than 4 V.