Preparation of 2D composite materials for high performance electrochemical extraction of Lithium and precious metals from brine

Project: Research

Project Details


With the increase in worldwide consumption of lithium owing to its use in electronic devices, it is necessary to develop less energy-intensive alternatives for Li production meet its rapidly growing demand.. In the case of brines, Li for instance, is usually removed by precipitation using aluminum salts [1] or by the adsorption of Li on selective metallic materials, such as H1.6Mn1.6O4[2][3], Li1.6Mn1.6O4 [4], MnO2[5], and H2TiO3[6]. However, the adsorption method suffers from low adsorption capacity and poor regeneration [7]. Diethyl ether and alcohols can be used to extract Li by the liquid-liquid extraction method. The solvent extraction method is effective for the extraction of Li from brines, which have a high Mg2+/Li+ ratio. However, this method is neither economically viable nor environmentally friendly because it requires enormous quantities of organic solvents. Furthermore, recycling organic solvents is challenging and energy intensive [8]. Although these methods are well established and show good recovery and selectivity, they require pre- and post-treatments to improve the extraction efficiency and regenerate the materials, respectively. This results in the consumption of large quantities of chemicals [9]. Therefore, there is an urgent need to develop efficient, cost-effective, and environmentally friendly technologies. Among the emerging technologies, electrochemical metal–capturing systems for metals extraction are considered extremely promising owing to their tunability, reversibility, selectivity, cyclability, and high capability to capture metals[10] [11]. Electrochemical methods have proven to be effective in extracting minerals from brine and seawater with low energy consumption[12]. During electrochemical processes, the electrode material used usually selectively intercalates metals ions. For instance, electrodes of λ-MnO2/Pt exhibit selective intercalation of Li with a maximum insertion capacity of 11 mg/g over a period of 2.2 h [13]. Currently, several researchers are investigating the extraction of precious metals by various materials, and to the best of our knowledge, relatively few studies employ layered double hydroxides (LDHs) as electrodes for lithium extraction. Two-dimensional materials called layered double hydroxides (LDHs) are typically made up of positively charged brucite-like host layers and charge balancing inter-layer anions, and their usual formula is [(MII)1−x(MIII)x(OH)2]x+(Am−x/m)·nH2O] [14] In terms of materials for energy storage and conversion, layered double hydroxides (LDHs), which have architectures based on two-dimensional lamellar layers and interlayer charge compensating anion, are somewhat promising [[15]], [[16]]. In contrast, the hydroxide group on LDHs and the anions in the interlayer are unfavorable for the adsorption of metal ions, resulting in a lack of active sites for accommodating cations. As a result, only a limited capacity can be reached by employing pure LDHs [[17]]. Although prior research has established that LDHs are faradic pseudocapacitive materials for alkaline Supercapacitors based on the redox behavior of host layers, these materials have a narrow potential window (0.5 V) and poor stability due to the significant oxygen evolution reaction in a high-pH medium [18] A new class of electrochemical energy storage materials may be created if LDHs can be efficiently modified to act as host matrix for the intercalation of various earth-abundant cations. It was shown That the hydrogen-vacancy enriched LDHs exhibit a two-dimensional open channel with an effective activation site for several cations’ intercalation, such as Na+, K+, and Zn2+ [[19]]. In addition, the potential window of activated LDH can also be expanded to 0–1 V in a neutral aqueous electrolyte. Herein we propose a new approach to increase the electroactivity of the LDH material by simple electrochemical activation followed by the incorporation of polyaniline. This last is known to be conductive which will influence the conductivity of the LDH material. The activated LDH material will be used as the negative electrode for lithium electrochemical extraction. Scheme 1 It is important to note that the interlayer distance decreases due to the active hydrogen vacancy production accompanying the deintercalation of anion. Normally, cation transport would be hampered by the LDHs' small interlayer spacing [20]. In this situation, the hydrogen-vacancy produced alongside the reduced interlayer spacing serves as activation sites for the reversible intercalation of metal ions
Effective start/end date16/02/2331/12/23


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