Solvent extraction fractionation of Li-ion battery leachate containing Li, Ni, and Co

Progress, Key Issues, and Future Prospects for Li-Ion Battery Recycling

The overuse and exploitation of fossil fuels has triggered the energy crisis and caused tremendous issues for the society. Lithium-ion batteries (LIBs), as one of the most important renewable energy storage technologies, have experienced booming progress, especially with the drastic growth of electric vehicles. To avoid massive mineral mining and the opening of new mines, battery recycling to extract valuable species from spent LIBs is essential for the development of renewable energy. Therefore, LIBs recycling needs to be widely promoted/applied and the advanced recycling technology with low energy consumption, low emission, and green reagents needs to be highlighted. In this review, the necessity for battery recycling is first discussed from several different aspects. Second, the various LIBs recycling technologies that are currently used, such as pyrometallurgical and hydrometallurgical methods, are summarized and evaluated. Then, based on the challenges of the above recycling methods, the authors look further forward to some of the cutting-edge recycling technologies, such as direct repair and regeneration. In addition, the authors also discuss the prospects of selected recycling strategies for next-generation LIBs such as solid-state Li-metal batteries. Finally, overall conclusions and future perspectives for the sustainability of energy storage devices are presented in the last chapter.

Solvent Extraction for Separation of 99.9% Pure Cobalt and Recovery of Li, Ni, Fe, Cu, Al from Spent LIBs

In this work, hydrometallurgical recycling of metals from high-cobalt-content spent lithium-ion batteries (LIBs) from laptops was studied using precipitation and solvent extraction as alternative purification processes. Large amounts of cobalt (58% by weight), along with nickel (6.2%), manganese (3.06%) and lithium (6.09%) are present in LiCoO2 and Li2CoMn3O8 as prominent Co-rich phases of the electrode material. The pregnant leach solution (PLS) that was generated by leaching in the presence of 10% H2O2 using 50 g/L pulp density at 80 °C for 4 h contained 27.4 g/L Co, 3.21 g/L Ni, 1.59 g/L Mn and 3.60 g/L Li. The PLS was subjected to precipitation at various pH using 2 M NaOH but the purification performance was poor. To improve the separation of Mn and other impurities and in order to avoid the loss of cobalt and nickel, separation studies were carried out using a solvent extraction technique using di-(2-ethylhexyl) phosphoric acid (D2EHPA) and bis-(2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272). Overall, this study examines the fundamentals of separating and synthesizing 99.9% pure Co sulfate from leach liquor of spent laptop LIBs with remarkably high cobalt content.

Fractionation of Transition Metals by Solvent Extraction and Precipitation from Tannic Acid-Acetic Acid Leachate as a Product of Lithium-Ion Battery Leaching

Solvent extraction and precipitation schemes are applied to isolate copper, cobalt, manganese and nickel from leachate, produced from spent lithium-ion battery leaching using tannic acid-acetic acid as lixiviant. The metal separation and purification were developed based on a ketoxime (LIX® 84-I) and a phosphinic acid (Cyanex® 272) extraction system. Aside from the leachate’s initial pH, which dictates the metal isolation flowsheet, other parameters affecting metal extraction rate, such as phase ratio, extractant concentration, and acid stripping will be evaluated. Copper was selectively removed from leachate at pH 3, using LIX® 84-I 10% v/v followed by cobalt and manganese co-extraction from the raffinate using Cyanex® 272 10% v/v at pH 5. After both metals were stripped using sulfuric acid 0.2 M, manganese was quantitatively precipitated out from the strip solution using potassium permanganate or sodium hypochlorite. Nickel was isolated using LIX® 84-I from raffinate at pH 5, producing a lithium- rich solution for further treatment. No third phase was formed during the extraction, and sulfuric acid was proved suitable for organic phase regeneration.

Recycling of cathode material from spent lithium-ion batteries: Challenges and future perspectives

The intrinsic advancement of lithium-ion batteries (LIBs) for application in electric vehicles (EVs), portable electronic devices, and energy-storage devices has led to an increase in the number of spent LIBs. Spent LIBs contain hazardous metals (such as Li, Co, Ni, and Mn), toxic and corrosive electrolytes, metal casting, and polymer binders that pose a serious threat to the environment and human health. Additionally, spent LIBs may serve as an economic source for transition metals, which could be applied to redesigning under a closed-circuit recycling process. Thus, the development of environmentally benign, low cost, and efficient processes for recycling of LIBs for a sustainable future has attracted worldwide attention. Therefore, herein, we introduce the concept of LIBs and review state-of-art technologies for metal recycling processes. Moreover, we emphasize on LIB pretreatment approaches, metal extraction, and pyrometallurgical, hydrometallurgical, and biometallurgical approaches. Direct recycling technologies combined with the profitable and sustainable cathode healing technology have significant potential for the recycling of LIBs without decomposition into substituent elements or precipitation; hence, these technologies can be industrially adopted for EV batteries. Finally, commercial technological developments, existing challenges, and suggestions are presented for the development of effective, environmentally friendly recycling technology for the future.

Solvent extraction for recycling of spent lithium-ion batteries

Up to now, solvent extraction not only recycle valuable metals (i.e., Ni, Co, Mn and Li) from the leach liquor of spent cathode materials, but also apply to treat spent electrolyte. This paper summarizes the development of solvent extraction in the field of recycling spent lithium-ion batteries (LIBs) from the aspects of principle, technology and industrialization. Meanwhile, the paper also comments on the challenges and opportunities for the solvent extraction facing in the recycling of spent LIBs.

A lattice defect-inspired leaching strategy toward simultaneous recovery and separation of value metals from spent cathode materials

Efficient recycling of high-value metals from spent cathode materials is important in that it not only alleviates the severe shortage of raw material supply but also addresses the environmental and safety issues associated with the disposal of these materials. Here, we report a selective leaching strategy by virtue of the defect-induced lattice instability. In contrast to the traditional "primary leaching - multistep separation" process, this technique enables simultaneous recovery and separation of value metals from the waste cathode by selective dissolution. The feasibility of this technique was first demonstrated by density functional theory (DFT) calculations, and then confirmed by laboratory studies in which a spent LiNi_1/3Co_1/3Mn_1/3O₂ material was successfully recycled, where the recoveries of Li, Ni/Co and Mn reached close to 100%, 99.5%/98.2% and 100%, respectively, without the need for a separation step. The recovery of Li, Ni/Co and Mn uses oxalic acid, phosphoric acid and sulfuric acid as leaching agents, respectively. We believe that this work has both practical and theoretical significance, in that the strategy has the potential to be expanded to the recovery/recycling of many other spent materials, and that the atomic-scale insight on the relation between vacancies and lattice stability offers new perspective for developing advanced recycling strategies.

Precipitation and Crystallization Used in the Production of Metal Salts for Li-Ion Battery Materials: A Review

Li-ion battery materials have been widely studied over the past decades. The metal salts that serve as starting materials for cathode and production, including Li2CO3, NiSO4, CoSO4 and MnSO4, are mainly produced using hydrometallurgical processes. In hydrometallurgy, aqueous precipitation and crystallization are important unit operations. Precipitation is mainly used in the processes of impurity removal, separation and preliminary production, while controlled crystallization can be very important to produce a pure product that separates well from the liquid solution. Precipitation and crystallization are often considered in the development of sustainable technologies, and there is still room for applying novel techniques. This review focuses on precipitation and crystallization applied to the production of metal salts for Li-ion battery materials. A number of novel and promising precipitation and crystallization methods, including eutectic freeze crystallization, antisolvent crystallization, and homogeneous precipitation are discussed. Finally, the application of precipitation and crystallization techniques in hydrometallurgical recycling processes for Li-ion batteries are reviewed.

Lithium recovery from effluent of spent lithium battery recycling process using solvent extraction

A novel process of lithium recovery from effluent of spent lithium batteries recycling by solvent extraction was proposed. The β-diketone extraction system used in the experiment was composed of benzoyltrifluoroacetone (HBTA), trioctylphosphine oxide (TOPO) and kerosene. The effective parameters such as solution pH value, saponification degree, initial lithium concentration and phase ratio were evaluated by experiments. More than 90% of lithium could be extracted by saponified organic phase through three-stage countercurrent extraction. The loaded organic phase was first eluted by dilute HCl solution to remove nontarget sodium, and then stripped by 6 mol/L HCl at a large phase ratio to obtain lithium-rich solution with 4.322 mol/L lithium. The lithium-rich solution from the process could be used to prepare lithium carbonate or lithium chloride. The stripped organic phase can be recycled and no crud or emulsification was observed during the process. The extraction mechanism of HBTA-TOPO was investigated via FT-IR spectroscopy, and the results indicated the two extractants showed strong synergistic effect. The thermodynamic study revealed lithium extraction is an exothermic process, which meant lower temperature promotes extraction of lithium. This work provided a novel approach to recover lithium from effluent of spent lithium battery recycling.

Recovery of Lithium from Simulated Secondary Resources (LiCO3) through Solvent Extraction

Lithium extraction is currently too inefficient to be economical or marketable. The objective of this work was to find the best extractant and the most inexpensive approach to recover lithium chemically from lithium ion batteries containing other desired metals using the solvent extraction technique. The extraction efficiency of various extracting types was investigated. The highest extraction efficiency of lithium ion from aqueous solution was obtained with bis(2-ethylhexyl) phosphate (DEHPA), with 75% recovery. Studying the effects of selected extractants in this experiment, it was found that the acidic extractant group provided better extraction efficiency than solvating extractants. Further investigation of influential variables was carried out, including extraction time, pH of aqueous solution, and initial concentration. The results indicate that 6 h of extraction brings the system to equilibrium, and pH 1.5 is the best for extraction efficiency.

Challenges to Future Development of Spent Lithium Ion Batteries Recovery from Environmental and Technological Perspectives

Spent lithium ion battery (LIB) recovery is becoming quite urgent for environmental protection and social needs due to the rapid progress in LIB industries. However, recycling technologies cannot keep up with the exaltation of the LIB market. Technological improvement of processing spent batteries is necessary for industrial application. In this paper, spent LIB recovery processes are classified into three steps for discussion: gathering electrode materials, separating metal elements, and recycling separated metals. Detailed discussion and analysis are conducted in every step to provide beneficial advice for environmental protection and technology improvement of spent LIB recovery. Besides, the practical industrial recycling processes are introduced according to their advantages and disadvantages. And some recommendations are provided for existing problems. Based on current recycling technologies, the challenges for spent LIB recovery are summarized and discussed from technological and environmental perspectives. Furthermore, great effort should be made to promote the development of spent LIB recovery in future research as follows: (1) gathering high-purity electrode materials by mechanical pretreatment; (2) green metals leaching from electrode materials; (3) targeted extraction of metals from electrode materials.

Closed Loop Recycling of Electric Vehicle Batteries to Enable Ultra-high Quality Cathode Powder

The lithium-ion battery (LIB) recycling market is becoming increasingly important because of the widespread use of LIBs in every aspect of our lives. Mobile devices and electric cars represent the largest application areas for LIBs. Vigorous innovation in these sectors is spurring continuous deployment of LIB powered devices, and consequently more and more LIBs will become waste as they approach end of life. Considering the significant economic and environmental impacts, recycling is not only necessary, but also urgent. The WPI group has successfully developed a closed-loop recycling process, and has previously demonstrated it on a relatively small scale 1 kg spent batteries per experiment. Here, we show that the closed-loop recycling process can be successfully scaled up to 30 kg of spent LIBs from electric vehicle recycling streams, and the recovered cathode powder shows similar (or better) performance to equivalent commercial powder when evaluated in both coin cells and single layer pouch cells. All of these results demonstrate the closed-loop recycling process has great adaptability and can be further developed into industrial scale.

Toward sustainable and systematic recycling of spent rechargeable batteries

A comprehensive and novel view on battery recycling is provided in terms of the science and technology, engineering, and policy.