Three-dimensional cationic covalent organic framework membranes for rapid and selective lithium extraction from saline water
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ToF-SIMS sputter depth profiling of interphases and coatings on lithium metal surfaces
Lithium metal as a negative electrode material offers ten times the specific capacity of graphitic electrodes, but its rechargeable operation poses challenges like excessive and continuous interphase formation, high surface area lithium deposits and safety issues. Improving the lithium | electrolyte interface and interphase requires powerful surface analysis techniques, such as ToF-SIMS sputter depth profiling.This study investigates lithium metal sections with an SEI layer by ToF-SIMS using different sputter ions. An optimal sputter ion is chosen based on the measured ToF-SIMS sputter depth profiles and SEM analysis of the surface damage. Further, this method is adapted to lithium metal foil with an intermetallic coating. ToF-SIMS sputter depth profiles in both polarities provide comprehensive insights into the coating structure. Both investigations highlight the value of ToF-SIMS sputter depth profiling in lithium metal battery research and offer guidance for future studies.
Solution-processable polymer membranes with hydrophilic subnanometre pores for sustainable lithium extraction
Membrane-based separation processes hold great promise for sustainable extraction of lithium from brines for the rapidly expanding electric vehicle industry and renewable energy storage. However, it remains challenging to develop high-selectivity membranes that can be upscaled for industrial processes. Here we report solution-processable polymer membranes with subnanometre pores with excellent ion separation selectivity in electrodialysis processes for lithium extraction. Polymers of intrinsic microporosity incorporated with hydrophilic functional groups enable fast transport of monovalent alkali cations (Li+, Na+ and K+) while rejecting relatively larger divalent ions such as Mg2+. The polymer of intrinsic microporosity membranes surpasses the performance of most existing membrane materials. Furthermore, the membranes were scaled up and integrated into an electrodialysis stack, demonstrating excellent selectivity in simulated salt-lake brines. This work will inspire the development of selective membranes for a wide range of sustainable separation processes critical for resource recovery and a global circular economy.
Solar-driven interfacial evaporation technologies for food, energy and water
Solar-driven interfacial evaporation technologies use solar energy to heat materials that drive water evaporation. These technologies are versatile and do not require electricity, which enables their potential application across the food, energy and water nexus. In this Review, we assess the potential of solar-driven interfacial evaporation technologies in food, energy and clean-water production, in wastewater treatment, and in resource recovery. Interfacial evaporation technologies can produce up to 5.3 l m–2 h−1 of drinking water using sunlight as the energy source. Systems designed for food production in coastal regions desalinate water to irrigate crops or wash contaminated soils. Technologies are being developed to simultaneously produce both clean energy and water through interfacial evaporation and have reached up to 204 W m–2 for electricity and 2.5 l m–2 h–1 for water in separate systems. Other solar evaporation approaches or combinations of approaches could potentially use the full solar spectrum to generate multiple products (such as water, food, electricity, heating or cooling, and/or fuels). In the future, solar evaporation technologies could aid in food, energy and water provision in low-resource or rural settings that lack reliable access to these essentials, but the systems must first undergo rigorous, scaled-up field testing to understand their performance, stability and competitiveness.
The evolution of lithium-ion battery recycling
Demand for lithium-ion batteries (LIBs) is increasing owing to the expanding use of electrical vehicles and stationary energy storage. Efficient and closed-loop battery recycling strategies are therefore needed, which will require recovering materials from spent LIBs and reintegrating them into new batteries. In this Review, we outline the current state of LIB recycling, evaluating industrial and developing technologies. Among industrial technologies, pyrometallurgy can be broadly applied to diverse electrode materials but requires operating temperatures of over 1,000 °C and therefore has high energy consumption. Hydrometallurgy can be performed at temperatures below 200 °C and has material recovery rates of up to 93% for lithium, nickel and cobalt, but it produces large amounts of wastewater. Developing technologies such as direct recycling and upcycling aim to increase the efficiency of LIB recycling and rely on improved pretreatment processes with automated disassembly and cleaner mechanical separation. Additionally, the range of materials recovered from spent LIBs is expanding from the cathode materials recycled with established methods to include anode materials, electrolytes, binders, separators and current collectors. Achieving an efficient recycling ecosystem will require collaboration between recyclers, battery manufacturers and electric vehicle manufacturers to aid the design and automation of battery disassembly lines.
Emerging organic electrode materials for sustainable batteries
Organic electrode materials (OEMs) possess low discharge potentials and charge‒discharge rates, making them suitable for use as affordable and eco-friendly rechargeable energy storage systems without needing metals such as lithium or sodium. OEMs can provide a sustainable energy economy by their development into stable and efficient next-generation high-power batteries. Despite the presence of several classes of OEMs, such as conducting polymers, 2D and 3D metal-organic frameworks, organolithium derivatives, 2D covalent organic frameworks, aromatic heterocyclic imides, and viologen derivatives, since their introduction in the 1960s, carbonyl-based molecules have maintained low discharge potentials and stable charging/discharging properties. Nevertheless, several redox-active organic molecules, including carbonyl derivatives, show poor electrochemical stability and ionic mobility in standard battery electrolytes, hampering their commercial use. Therefore, with the increased demand for renewable energy, the synthesis and testing of carbonyl-based OEMs continue to be performed in energy research. This review summarizes recent advances in developing carbonyl-based OEMs and their performance in rechargeable batteries.
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