Electrochemical Lithium Recovery Research Articles

Bifunctional Deionization and Lithium Recovery Via Four-Step Constant Voltage Operation of Hybrid Capacitive Deionization with Composite Electrodes

The efficient recovery of valuable resources from wastewater has become a crucial challenge in the era of a carbon-neutral society. Capacitive deionization (CDI) has been employed in electrochemical lithium recovery (ELR) processes, based on selective Li+ intercalation to LiMn2O4 (LMO). In this study, we propose a four-step constant voltage operation (forward/zero/reverse/zero) of bifunctional hybrid CDI to produce deionized water as well as Li+-rich concentrate within a cycle. This unique performance was enabled by composite electrodes with capacitive activated carbon cloth (ACC) impregnated with redox-active LMO and Ag, respectively, which were characterized and evaluated through material characterization and electroanalysis. The proposed CDI system demonstrated deionization (step 1; forward voltage) and selective Li+ enrichment (step 3; reverse voltage) without influent replacement. The performance of the CDI system was evaluated through single pass experiments with binary NaCl and LiCl solutions (10 mM each) under 1.0/0/-1.0/0 V operation, revealing supreme performance with mass loadings of 32.6 mg/cm2 for LMO and 3.3 mg/cm2 for Ag. Furthermore, the long-term stability of the system was confirmed, indicating its potential for practical implementation. The proposed bifunctional CDI system, combining ELR with water treatment, paves the way for advancing resource recycling from wastewater.

Increasing the stability of LiMn<sub>2</sub>O<sub>4</sub> electrodes under high-current-density conditions via SoC control in an electrochemical lithium recovery system

For efficient lithium recovery, the electrochemical lithium recovery (ELR) process that uses LiMn<sub>2</sub>O<sub>4</sub> (LMO) electrodes with selectivity for lithium ions, has been introduced. The electrochemical system is environmentally friendly and allows for the recovery of lithium at a high yield, but the issue of manganese dissolution in LMO electrodes, decreasing their stability, remains to be solved. Herein, we suggest a solution to the existing problem through a rapid lithium recovery method that also enhances the stability of LMO electrodes through the state-of-charge (SoC) control approach. The retained discharge capacity of the system with a high current density (0.4 A/g) remains at 99.2% at 60% SoC after 300 cycles. Compared to the results under full charge/discharge operation (44.2% after 300 cycles), the proposed method demonstrates the state-of-charge (SoC) control adjustments at high current density levels to enhance the recovery rate and stability of the electrode. Additionally, high lithium-ion selectivity with a similar recovery rate is maintained at a high current density under 60% SoC operation compared to 100% SoC in lithium recovery tests. These results indicate that the SoC control strategy can increase the efficiency of ELR by improving the stability of the electrode under high-rate operational conditions.

Structural stabilization of Cr-doped spinel LiMn2O4 for long-term cyclability towards electrochemical lithium recovery in original brine

Current explosive demand in raw lithium greatly boosts lithium mining, and electrochemical Li-extraction using spinel LiMn2O4 (LMO) from original brine has gained much attentions. In this study, Cr-doped LMO is prepared via a facile precipitation-calcination to elucidate the structural alterations and suppress Jahn-Teller distortion, and a novel hybrid capacitive deionization (HCDI) system of “Li-poor LiMn1.8Cr0.2O4||brine (recovery liquid)||activated carbon” is constructed for electrochemical Li-extraction. The results prove that Cr-doping effectively suppresses Mn3+ disproportionation induced by Jahn–Teller distortion, leading to a stabilized spinel framework for long lifespan. Importantly, the Cr-doping LMO realizes a stable (de)lithiation over 500 cycles with low manganese dissolution rate of 0.027 % per cycle. Meanwhile, the Li-extraction capacity can reach 22 mg g−1 in 1.0 M LiCl electrolyte with retention rate of 86.05 % after 500 cycles. In the assembled HCDI system, average Li-extraction capacity in brine reaches ∼15 mg g−1 after 15 cycles. Therefore, the HCDI system using Cr-doping LMO could introduce a new perspective for the industrial Li-extraction facing original brine.

Four-step constant voltage operation of hybrid capacitive deionization with composite electrodes for bifunctional deionization and lithium recovery

Efficient recovery of valuable resources from wastewater has emerged as a critical challenge in the era of carbon neutral society. Capacitive deionization (CDI) has been employed in electrochemical lithium recovery (ELR) processes based on selective Li+ intercalation to LiMn2O4 (LMO). We herein propose a four-step constant voltage operation (forward/zero/reverse/zero) of bifunctional hybrid CDI to produce deionized water as well as Li+-rich concentrate within a cycle. Especially, selective Li+ enrichment was possible without influent replacement since adsorption of competing ions and liberation of Li+ could occur simultaneously. This unique performance was enabled by composite electrodes on capacitive activated carbon cloth (ACC) impregnated with redox-active materials; LMO@ACC and Ag@ACC. Together with material characterization and electroanalysis on the composite electrodes, deionization (step 1; forward voltage) and Li+ enrichment (step 3; reverse voltage) by assembled LMO@ACC//Ag@ACC cell were evaluated by single pass experiments with binary NaCl and LiCl solution (10 mM each). Besides, a multi-stage operation with internal recycle confirmed long-term stability and continuous increase of Li purity for practical implementation. The advanced bifunctional CDI (ELR coupled with water treatment) paved a way to advance the resource recycle from wastewater.

Enhancement of the cycling stability of an electrochemical lithium recovery system via state-of-charge (SoC) control

Based on the lithium ion selective electrode, electrochemical lithium recovery (ELR) is a promising lithium recovery technology in which lithium ions are adsorbed and desorbed on the electrode. However, the stability of the ELR system is not sufficient for continuous lithium ion recovery. Here, we report a novel approach for improving the stability of the ELR system through the state-of-charge (SoC) control scheme. In this system, the electrode is composed of lithium manganese oxide (LiMn2O4, LMO) and silver (Ag), and lithium ions are captured in the LMO electrode. The stability of the LMO electrode is improved by using 60 % of the maximum capacity via SoC control. After 50 cycles, the 60 % SoC discharge capacity is maintained at 85.4 %, showing better performance compared to the 100 % SoC approach (60.0 % discharge capacity). In addition, the performance of lithium recovery with 60 % SoC control was more energy efficient with similar lithium ion capacity and selectivity compared to the 100 % SoC operation method. These results suggest that the SoC control scheme could be an efficient method to enhance the stability of ELR techniques.

Construction of porous disc-like lithium manganate for rapid and selective electrochemical lithium extraction from brine

In order to satisfy the growing global demand for lithium, selective extraction of lithium from brine has attracted extensive attention. LiMn 2 O 4 -based electrochemical lithium recovery system is one of the best choices for commercial applications because of its high selectivity and low energy consumption. However, the low ion diffusion coefficient of lithium manganate limits the further development of electrochemical lithium recovery system. In this work, a novel porous disc-like LiMn 2 O 4 was successfully synthesized for the first time via two-step annealing manganese (II) precursors. The as-prepared LiMn 2 O 4 exhibits porous disc-like morphology, excellent crystallinity, high Li + diffusion coefficient (average 7.6×10 −9 cm 2 ∙s −1 ), high cycle stability (after 30 uninterrupted extraction and release cycles, the crystal structure hardly changed) and superior rate capacity (93.5% retention from 10 mA∙g −1 −120 mA∙g −1 ). The porous structure and disc-like morphology further promote the contact between lithium ions and electrode materials. Therefore, the assembled electrochemical lithium extraction device with LiMn 2 O 4 as positive electrode and silver (Ag) as negative electrode can realize the rapid and selective extraction of lithium in simulated brine (adsorption capacity of lithium can reach 4.85 mg∙g −1 in 1 h). The mechanism of disc-like LiMn 2 O 4 in electrochemical lithium extraction was proposed based on the analysis of electrochemical characterization and quasi in situ XRD. This novel structure may further promote the practical application of electrochemical lithium extraction from brine.

Recent Advances in Lithium Extraction Using Electrode Materials of Li-Ion Battery from Brine/Seawater

With the rapid development of industry, the demand for lithium resources is increasing. Traditional methods such as precipitation usually take 1–2 years, and depend on weather conditions. In addition, electrochemical lithium recovery (ELR) as a green chemical method has attracted a great deal of attention. Herein, we summarize the systems of electrochemical lithium extraction and the electrode materials of the Li-ion battery from brine/seawater. Some representative work on electrochemical lithium extraction is then introduced. Finally, we prospect the future opportunities and challenges of electrochemical lithium extraction. In all, this review explores electrochemical lithium extraction from brine/seawater in depth, with special attention to the systems and electrode of electrochemical lithium extraction, which could provide a useful guidance for reasonable electrochemical-lithium-extraction.

(Invited) Surface Electrochemistry and Physicochemical Behaviors of Carbon and Compound Electrodes in Electrochemical Separation Systems

In recent years, electrochemical separation systems have received a great attention due to their excellent capabilities in environmental remediation, water desalination, and resource recovery. The performances of electrochemical separation systems are often interpreted in terms of capacity and selectivity, both of which are highly dependent on electrode materials. For instance, capacitive deionization (CDI) used for desalination of water employs activated carbon electrodes, as it enables capture and release of sodium chloride in large amounts. In addition, lithium-ion selective electrode such as delithiated LiMn2O4 (i.e. λ-MnO2) or LiFePO4 plays an essential role in selectivity of electrochemical lithium recovery systems. However, although the importance electrode materials cannot be overemphasized for such electrochemical separations, it is also true that we are yet to achieve a sufficient level of understanding on their behaviors in the systems, which is necessary to establish rational electrode-design strategies to enhance capacity and selectivity of the electrochemical separation systems. In this talk, our recent findings on surface electrochemistry of carbon electrodes in electrochemical desalination will be introduced, together with an overview on the non-favorable Faradaic reactions thoroughly characterized with the assistance of various X-ray and electrochemical techniques. Additionally, development of heteroatom-doped carbon material and how it resulted in a highly stable CDI performance will be presented. Moreover, I will talk about our efforts on characterization of physicochemical behavior of λ-MnO2 in electrochemical lithium recovery systems, based on which a significantly higher utilization rate of the electrode materials could be achieved.

Redox-Mediated Electrodialysis for Resource Recovery and Energy-Efficient Desalination

In the chemical and biochemical manufacturing industry, separation processes are amongst the most energy-demanding processes. Electrochemical separations have been growing in interest as promising candidates for both downstream processing for resource recovery and producing clean water due to their energy-efficient, environmentally benign, and modular features.1 Leveraging a sustainable redox reaction, we developed a redox-mediated electrodialysis system for energy-efficient desalination coupled with resource recovery of valuable resources such as lithium, and even biomolecules.2, 3 Our proposed redox-mediated electrodialysis system utilizes a reversible redox reaction as a driving force of salt removal at a much lower voltage than a water-splitting reaction (>1.2 V). As the redox materials are reduced or oxidized, all charged species migrate across the membranes to balance the charge in the electrolyte compartment. As the redox materials circulate in the cathode and anode compartments, they sustainably regenerated without additional regeneration steps, one of the major bottlenecks for industrializing the electrosorption system. We demonstrated the redox-mediated electrochemical system for resource recoveries such as simultaneous lithium recovery from brine3 and valorization of whey proteins and lactose from whey waste.2 Especially for the valorization of whey waste, our system treated 99% of salt from the whey solution within a single step and recovered > 98% of various whey proteins (e.g., valuable protein contents such as beta-lactoglobulin, alpha-lactalbumin, and lactose). The preliminary techno-economic analysis confirmed the economic potential of redox-mediated ED with 51−73% lower energy consumption compared to conventional ED. Overall. we envision the system can become a breakthrough in tackling the environmental challenges coupled with the limited resources. Kim, N.; Jeon, J.; Chen, R.; Su, X., Electrochemical separation of organic acids and proteins for food and biomanufacturing. Chemical Engineering Research and Design 2022, 178, 267-288.Kim, N.; Jeon, J.; Elbert, J.; Kim, C.; Su, X., Redox-mediated electrochemical desalination for waste valorization in dairy production. Chemical Engineering Journal 2022, 428, 131082.Kim, N.; Su, X.; Kim, C., Electrochemical lithium recovery system through the simultaneous lithium enrichment via sustainable redox reaction. Chemical Engineering Journal 2021, 420, 127715.

Electrode design and performance of flow-type electrochemical lithium recovery (ELR) systems

Due to increasing interests in carbon neutral engineering, global market demand for lithium compounds is steadily growing, which serve as key compounds in the battery production. As a sustainable alternative for lithium compound production, electrochemical lithium recovery (ELR) is being studied extensively in recent years. However, research efforts for ELR have been mainly devoted to the synthesis of electrode materials, leaving an open problem of comprehensively understanding the effects of multiple electrode design parameters on the system performances. In this study, to address such a problem systematically, the ELR system with λ-MnO2/LiMn2O4 (LMO) electrodes is numerically investigated at a low current density of 62.5 μA/cm2. Three electrode design parameters are selected, which are known as key parameters in the literature: effective radius of LMO particles (rp), volume fraction of LMO particles in electrodes (εs), and electrode thickness (δ). Under the parameter range considered, the specific mass of Li+ recovered (qLi+) took the value ranging from 35.71 mg/g to 37.66 mg/g, while the range covered by the net energy consumption (Wnet) was from 0.17 Wh/mol to 5.44 Wh/mol. Sensitivity analysis showed that, with increasing rp, qLi+ decreases and Wnet increases, while opposite correlations were observed for εs and δ. It was also shown that the maximum of qLi+ and the minimum of Wnet can be achieved only with small rp (regardless of εs and δ), making it the most important parameter.

Construction of truncated-octahedral LiMn2O4 for battery-like electrochemical lithium recovery from brine

The extraction of lithium from salt lakes or seawater has attracted worldwide attention because of the explosive growth of global demand for lithium products. The LiMn2O4-based electrochemical lithium recovery system is one of the strongest candidates for commercial application due to its high inserted capacity and low energy consumption. However, the surface orientation of LiMn2O4 that facilitates Li diffusion happens to be prone to manganese dissolution making it a great challenge to obtain high lithium inserted capacity and long life simultaneously. Herein, we address this problem by designing a truncated octahedral LiMn2O4 (Tr-oh LMO) in which the dominant (111) facets minimize Mn dissolution while a small portion of (100) facets facilitate the Li diffusion. Thus, this Tr-oh LMO-based electrochemical lithium recovery system shows excellent Li recovery performance with high inserted capacity (20.25 mg g−1 per cycle) in simulated brine. In addition, the dissolution rate of manganese per 30 cycles is only 0.44% and the capacity maintained 85% of the initial after 30 cycles. These promising findings accelerate the practical application of LiMn2O4 in electrochemical lithium recovery.

The counter electrode in electrochemical lithium recovery

Electrochemical lithium extraction methods have recently attracted significant attention as alternatives to the currently employed techniques. A considerable effort has been made to develop this technology, especially in searching Li-ion selective electrodes. However, much less attention has been paid to the counter electrodes. In general, these materials have been used as counterparts without considering their influence in the global method. This review summarizes the counter electrodes, analyzing their pros and cons. In addition, the energy efficiency of the various configurations was reported, while the other performance indices were not included because of the lack of data provided in the literature. Nevertheless, their potential influence in crucial parameters like purity, efficiency, or stability was estimated based on their electrochemical properties. This review demonstrates that specific studies on the counter electrodes and an effort to develop alternative materials are needed to push the current electrochemical lithium extraction method toward a new level.

Direct electrochemical lithium recovery from acidic lithium-ion battery leachate using intercalation electrodes

With the development of the electric vehicle industry, the demand for the lithium-ion battery (LIB) has considerably grown, and thus the recycling of LIB has become an important issue. Until now, only solvent extraction, leaching, and precipitation methods have been applied for lithium recovery from LIB leachate, but these methods need a series of separation of coexisting ions, and lithium is recovered in the final step of the recycling process. The electrochemical method is one of the promising methods for lithium recovery with several advantages such as high lithium selectivity, short reaction time, and low energy consumption. In this study, lithium is successfully recovered from actual industrial scale LIB leachate by electrochemical sorption using lithium manganese oxide (LMO) and activated carbon (AC) electrodes. The effects of current and electrochemical reaction time on lithium recovery from the LIB leachate are investigated and it is found that the lithium recovery capacity, purity, and the selectivity increase with higher current and longer reaction time. The maximum lithium recovery capacity of 3.51 mmol g −1 and energy consumption of 3.77 Wh mol −1 (13.6 kJ mol −1) is obtained during the electrochemical lithium recovery from the LIB leachate. The reusability of LMO/AC system is also tested and confirms that the lithium recovery capacity is maintained without the apparent degradation of the electrodes. This direct electrochemical lithium recovery from the LIB leachate could be more efficient than the established hydrometallurgical lithium recovery comprised of multiple separation steps of impurity elements.

Increasing the Stability of LiMn2O4 Against Harsh Conditions During Lithium Recovery from Real Brine Solutions

Brines are abundant waste products from desalination plants and have higher lithium contents than sea water (0.17 ppm). Herein, electrochemical lithium recovery from real brine solutions using Li‐selective LiMn2O4 is reported. Free‐standing electrodes are prepared completely solvent‐free. At low current densities, the complete theoretical capacity of 148 mAh g−1 can be utilized. The process is highly rate dependent due to the lithium concentration in the mm range. The high salt content of the brine depicts a challenging environment for electrodes and reactor materials. Competing earth‐alkali metals lead to scale formation blocking the electrode surface and reducing the electrode capacity for lithium uptake. The high chloride concentration enables the formation of chlorine Cl2 at potentials < 1 V versus Ag/AgCl competing with the deintercalation of lithium. A combination of commercial antiscalants was used to suppress the formation of CaCO3 at the electrode prolonging its cycle life. It is shown that a cation exchange membrane not only effectively blocks chloride ions from the electrode but also decreases the Li‐diffusion. Finally, the selectivity of the process is proven in a real brine with a low lithium content (0.7 mm), and an actual recovery experiment is conducted in a flow setup.

Electrochemical lithium recovery from brine with high Mg2+/Li+ ratio using mesoporous λ-MnO2/LiMn2O4 modified 3D graphite felt electrodes

Developing effective technologies for the extraction of lithium from seawater and salt-lake brines is paramount for sustainable lithium reuse in battery industries. Conventional adsorption technology for extracting lithium from brines has been limited due to the low adsorption rate and dissolution of adsorbents. Here, we report a novel flow-type electrochemical lithium recovery system based on mesoporous λ-MnO2/LiMn2O4 modified three-dimensional flow-through graphite felt electrodes. The mesoporous LiMn2O4 has a specific surface area of 183 m2/g, which provides a large solid-liquid interface for Li+ intercalation and deintercalation of LiMn2O4 phases. The three-dimensional graphite felt conductor could support abundant electroactive LiMn2O4 adsorbents and enhance the important diffusion and migration effects. In operation, a constant potential was applied on the cells to absorb Li+ by mesoporous λ-MnO2 from brine and desorb Li+ from mesoporous LiMn2O4 into recovery solution simultaneously. This system is successful to extract lithium of 75 mg/h per gram LiMn2O4, with a Li/Mg separation coefficient of 46 and energy consumption of 23.4 Wh/mol. This study highlights the remarkably electrochemical activity, quick mass-transfer kinetics, and excellent stability of the mesoporous LiMn2O4@GF electrode, and provides an energy-efficient method for the recovery of Li+ from brines with high Mg2+/Li+ ratios.

Layer spacing gradient (NaLi)1−xCoO2 for electrochemical Li extraction

Layer spacing gradient (NaLi)1−xCoO2 for electrochemical Li extraction

Electrochemical lithium recovery with lithium iron phosphate: what causes performance degradation and how can we improve the stability?

The reason for the capacity fading of LiFePO4 in lithium recovery is explored. And two approaches, reducing the content of oxygen and carbon coating, are put forward, and the mechanism of them are studied.

Short Review: Timeline of the Electrochemical Lithium Recovery System Using the Spinel LiMn2O4 as a Positive Electrode

Various lithium recovery technologies have been developed as securing lithium resources has become increasingly important. Among these technologies, the electrochemical lithium recovery (ELR) system is a rapid and eco-friendly extraction method that has been studied recently. In this paper, an ELR system using a spinel-type LiMn2O4 (LMO) is briefly reviewed. As LMO electrodes have high Li+ selectivity and stability compared to other lithium battery cathodes, they have been widely used as positive electrodes for the ELR system. This paper summarizes the system proposal, LMO electrode modification, system analysis, and industrial applications. Perspectives of the ELR technology are presented considering the progress of the research.

Electrochemical lithium recovery system through the simultaneous lithium enrichment via sustainable redox reaction

With the drastic increase in the demand for lithium, electrochemical lithium recovery has gained significant attention as an alternative for lime soda evaporation. Despite its high selectivity and efficiency, the industrial application of electrochemical systems remains limited because of its discontinuous operation and the low lithium concentration in the source water. Hence, this study proposes a redox-mediated system for selective lithium recovery in tandem with the continuous enrichment of the source water via a sustainable redox reaction. In the proposed system, the reversible redox reaction of ferri-/ferrocyanide enables continuous enrichment of the source water, while lithium-selective adsorbent (λ-MnO2) selectively recovers the enriched lithium simultaneously. The redox-mediated lithium recovery system successfully concentrated lithium ions up to 37 mM Li+ in an equimolar mixture of 5 mM Li+ and 5 mM Na+, and up to 0.6 mM Li+ even from extremely dilute lithium-containing solutions (0.1 mM Li+: 9.9 mM Na+). With the introduction of λ-MnO2 as a chemical adsorbent, this system exhibited an exceptional selectivity (selectivity coefficient (αLi-Na) of 57) toward lithium from an equimolar mixture, and high lithium selectivity coefficients (αLi-Na: 804 and αLi-Mg: 387) in a synthetic solution equivalent to the Salar de Atacama brine in Chile. Therefore, this study represents progress towards the industrial application of the lithium recovery process, with potential applications for critical metal recovery in general.

Understanding the Behaviors of λ-MnO2 in Electrochemical Lithium Recovery: Key Limiting Factors and a Route to the Enhanced Performance.

Recently developed electrochemical lithium recovery systems, whose operation principle mimics that of lithium-ion battery, enable selective recovery of lithium from source waters with a wide range of lithium ions (Li+) concentrations; however, physicochemical behaviors of the key component-Li+-selective electrode-in realistic operation conditions have been poorly understood. Herein, we report an investigation on a λ-MnO2 electrode during the electrochemical lithium recovery process with regards to the Li+ concentration in source water and operation rate of the system. Three distinctive stages of λ-MnO2 originating from different limiting factors for lithium recovery are defined with regard to the rate of Li+ supply from the electrolyte: depleted, transition, and saturated regions. By characterization of λ-MnO2 at different stages using diverse X-ray techniques, the importance of Li+ concentration in the vicinity of the electrode surface is revealed. On the basis of this understanding, increasing the density of the electrode/electrolyte interface is suggested as a realistic and general route to enhance the overall lithium recovery performance and is experimentally corroborated at a wide range of operation environments.