Recovery of Li, Ni, Co and Mn from spent lithium-ion batteries assisted by organic acids: Process optimization and leaching mechanism

The proper recycling of spent lithium-ion batteries(LIBs)can promote the recovery and utilization of valuable resources,while also negative environmental effects resulting from the presence of toxic and hazardous substances.In this study,a new environmentally friendly hydro-metallurgical process was proposed for leaching lithium(Li),nickel(Ni),cobalt(Co),and manganese(Mn)from spent LIBs using sulfuric acid with citric acid as a reductant.The effects of the concentration of sulfuric acid,the leaching temperature,the leaching time,the solid-liquid ratio,and the reducing agent dosage on the leaching behavior of the above elements were investigated.Key parameters were optimized using response surface methodology(RSM)to maximize the recovery of metals from spent LIBs.The maxim-um recovery efficiencies of Li,Ni,Co,and Mn can reach 99.08%,98.76%,98.33%,and 97.63%.under the optimized conditions(the sulfuric acid concentration was 1.16 mol/L,the citric acid dosage was 15wt%,the solid-liquid ratio was 40 g/L,and the temperature was 83℃ for 120 min),respectively.It was found that in the collaborative leaching process of sulfuric acid and citric acid,the citric acid initially provided strong reducing CO_(2)^(-),and the transition metal ions in the high state underwent a reduction reaction to produce transition metal ions in the low state.Additionally,citric acid can also act as a proton donor and chelate with lower-priced transition metal ions,thus speeding up the dissolution process.

Selective leaching of lithium from spent lithium-ion batteries using sulfuric acid and oxalic acid

Traditional hydrometallurgical methods for recovering spent lithium-ion batteries(LIBs)involve acid leaching to simultaneously extract all valuable metals into the leachate.These methods usually are followed by a series of separation steps such as precipitation,extraction,and stripping to separate the individual valuable metals.In this study,we present a process for selectively leaching lithium through the synergistic effect of sulfuric and oxalic acids.Under optimal leaching conditions(leaching time of 1.5 h,leaching temperature of 70°C,liquid-solid ratio of 4 mL/g,oxalic acid ratio of 1.3,and sulfuric acid ratio of 1.3),the lithium leaching efficiency reached89.6%,and the leaching efficiencies of Ni,Co,and Mn were 12.8%,6.5%,and 21.7%.X-ray diffraction(XRD)and inductively coupled plasma optical emission spectrometer(ICP-OES)analyses showed that most of the Ni,Co,and Mn in the raw material remained as solid residue oxides and oxalates.This study offers a new approach to enriching the relevant theory for selectively recovering lithium from spent LIBs.

Selective lithium recovery and regeneration of ternary cathode from spent lithium-ion batteries:Mixed HCl-H_(2)SO_(4) leaching-spray pyrolysis approach

The recycling of spent lithium-ion batteries(LIBs) is crucial for environmental protection and resource sustainability.However,the economic recovery of spent LIBs remains challenging due to low Li recovery efficiency and the need for multiple separation operations.Here,we propose a process involving mixed HCl-H_(2)SO_(4) leaching-spray pyrolysis for recycling spent ternary LIBs,achieving both selective Li recovery and the preparation of a ternary oxide precursor.Specifically,the process transforms spent ternary cathode(LiNi_(x)Co_yMn_(2)O_(2),NCM) powder into Li_(2)SO_(4) solution and ternary oxide,which can be directly used for synthesizing battery-grade Li_(2)CO_(3) and NCM cathode,respectively.Notably,SO_(4)^(2-) selectively precipitates with Li^(+) to form thermostable Li_(2)SO_(4) during the spray pyrolysis,which substantially improves the Li recovery efficiency by inhibiting Li evaporation and intercalation.Besides,SO_(2) emissions are avoided by controlling the molar ratio of Li^(+)/SO_(4)^(2-)(≥2:1),The mechanism of the preferential formation of Li_(2)SO_(4) is interpreted from its reverse solubility variation with temperature.During the recycling of spent NCM811,92% of Li is selectively recovered,and the regenerated NCM811 exhibits excellent cycling stability with a capacity retention of 81.7% after 300 cycles at 1 C.This work offers a simple and robust process for the recycling of spent NCM cathodes.

Preparation of lithium-ion battery anode materials from graphitized spent carbon cathode derived from aluminum electrolysis

Graphitized spent carbon cathode(SCC)is a hazardous solid waste generated in the aluminum electrolysis process.In this study,a flotation-acid leaching process is proposed for the purification of graphitized SCC,and the use of the purified SCC as an anode material for lithium-ion batteries is explored.The flotation and acid leaching processes were separately optimized through one-way experiments.The maximum SCC carbon content(93wt%)was achieved at a 90%proportion of−200-mesh flotation particle size,a slurry concentration of 10wt%,a rotation speed of 1600 r/min,and an inflatable capacity of 0.2 m^(3)/h(referred to as FSCC).In the subsequent acid leaching process,the SCC carbon content reached 99.58wt%at a leaching concentration of 5 mol/L,a leaching time of 100 min,a leaching temperature of 85°C,and an HCl/FSCC volume ratio of 5:1.The purified graphitized SCC(referred to as FSCC-CL)was utilized as an anode material,and it exhibited an initial capacity of 348.2 mAh/g at 0.1 C and a reversible capacity of 347.8 mAh/g after 100 cycles.Moreover,compared with commercial graphite,FSCC-CL exhibited better reversibility and cycle stability.Thus,purified SCC is an important candidate for anode material,and the flotation-acid leaching purification method is suitable for the resourceful recycling of SCC.

A review of cathode and electrolyte recovery from spent lithium-ion batteries: Recent technologies, processes and policies

Recently,lithium-ion batteries(LIBs),due to their superior performance,have been vastly applied in electronic,auto,and other industries,resulting in the generation of an increasing amount of spent LIBs.What’s worse,LIBs contained potentially toxic substances,including heavy metals,toxic and flammable electrolyte containing LiBF_(4),LiClO_(4),and LiPF_(6).Conventional disposal of spent LIBs via landfill or incineration exerts tremendous pressure on the environment.It was necessary to adopt efficient,low-cost,and environmentally friendly approaches to valorizing spent LIBs,which could not only alleviate the shortage of rare resources by recycling valuable ele-ments such as Cu,Li,Mn,Ni,Co,and Al,but also eliminate the pollution of harmful components in batteries and realize the recycling and sustainable industry related to consumer electronics and electric vehicles(EVs).Given this,this paper summarized the recycling technologies of spent LIBs,including pyrometallurgy(melting reduction and roasting methods)and hydrometallurgy(leaching,precipitation,extraction,ion-exchange,elec-trochemical,sol-gel methods),and electrolyte recycling(organic solvent extraction and supercritical extraction methods).Pyrometallurgy technologies had relatively decent metal recovery rates but were associated with high energy consumption and atmospheric emission issues.Hydrometallurgical technologies were more environ-mentally friendly and efficient in recovering spent LIBs,although disposing of the wastewater generated from the process remained a challenge.In addition,the different industrial processes and various countries’related policies of recycling spent LIBs were investigated.In the end,the outlooks and future directions of recycling spent LIBs were proposed.

Recovery of Co and Li from spent lithium-ion batteries by combination method of acid leaching and chemical precipitation

Cathode material of spent lithium-ion batteries was refined to obtain high value-added cobalt and lithium products based on the chemical behaviors of metal in different oxidation states. The active substances separated from the cathode of spent lithium-ion batteries were dissolved in H2SO4 and H2O2 solution, and precipitated as CoC2O4·2H2O microparticles by addition of （NH4）2C2O4. After collection of the CoC2O4·2H2O product by filtration, the Li2CO3 precipitates were obtained by addition of Na2CO3 in the left filtrate. The experimental study shows that 96.3% of Co （mass fraction） and 87.5% of Li can be dissolved in the solution of 2 mol/L H2SO4 and 2.0% H2O2 （volume fraction）, and 94.7% of Co and 71.0% of Li can be recovered respectively in the form of CoC2O4·2H2O and Li2CO3.

Pyrometallurgical recycling of end-of-life lithium-ion batteries

The global importance of lithium-ion batteries(LIBs)has been increasingly underscored with the advancement of high-performance energy storage technologies.However,the end-of-life of these batteries poses significant challenges from environmental,economic,and resource management perspectives.This review paper focuses on the pyrometallurgy-based recycling process of lithium-ion batteries,exploring the fundamental understanding of this process and the importance of its optimization.Centering on the high energy consumption and emission gas issues of the pyrometallurgical recycling process,we systematically analyzed the capital-intensive nature of this process and the resulting technological characteristics.Furthermore,we conducted an in-depth discussion on the future research directions to overcome the existing technological barriers and limitations.This review will provide valuable insights for researchers and industry stakeholders in the battery recycling field.

Reductive acid leaching of valuable metals from spent lithium-ion batteries using hydrazine sulfate as reductant

Hydrazine sulfate was used as a reducing agent for the leaching of Li,Ni,Co and Mn from spent lithium-ion batteries.The effects of the reaction conditions on the leaching mechanism and kinetics were characterized and examined.97%of the available Li,96%of the available Ni,95%of the available Co,and 86%of the available Mn are extracted under the following optimized conditions:sulfuric acid concentration of 2.0 mol/L,hydrazine sulfate dosage of 30 g/L,solid-to-liquid ratio of 50 g/L,temperature of 80℃,and leaching time of 60 min.The activation energies of the leaching are determined to be 44.32,59.37 and 55.62 k J/mol for Li,Ni and Co,respectively.By performing X-ray diffraction and scanning electron microscopy in conjunction with energy dispersive X-ray spectroscopy,it is confirmed that the main phase in the leaching residue is MnO2.The results show that hydrazine sulfate is an effective reducing agent in the acid leaching process for spent lithium-ion batteries.

Progresses in Sustainable Recycling Technology of Spent Lithium-Ion Batteries

The number of lithium-ion batteries(LIBs)is steadily increasing in order to meet the ever-growing demand for sustainable energy and a high quality of life for humankind.At the same time,the resulting large number of LIB waste certainly poses safety hazards if it is not properly disposed of and will seriously harm the environment due to its inherent toxicity due to the use of toxic substances.Moreover,the consumption of many scarce precious metal resources is behind the mass production of batteries.In the light of severe environmental,resources,safety and recycling problems,recycling spent LIBs have become an essential urgently needed action to achieve sustainable social development.This review therefore critically analyses the value and the need for recycling of spent LIBs from a variety of resources and the environment.A range of existing technologies for recycling and reusing spent LIBs,such as pretreatment,pyrometallurgy,hydrometallurgy,and direct recycled methods,is subsequently summarized exclusively.In addition,the benefits and problems of the methods described above are analyzed in detail.It also introduces recycling progress of other LIB components,such as anodes,separators,and electrolytes,as well as the high-value cathode.Finally,the prospects for recycling LIBs are addressed in four ways(government,users,battery manufacturers,and recyclers).This review should contribute to the development of the recycling of used LIBs,particularly in support of industrialization and recycling processes.

Hydrometallurgical recycling of valuable metals from spent lithium-ion batteries by reductive leaching with stannous chloride

The reductant is a critical factor in the hydrometallurgical recycling of valuable metals from spent lithium-ion batteries(LIBs).There is limited information regarding the use of SnCl_(2) as a reductant with organic acid(maleic acid)for recovering valuable metals from spent Li-CoO_(2) material.In this study,the leaching efficiencies of Li and Co with 1 mol·L^(−1) of maleic acid and 0.3 mol·L^(−1) of SnCl_(2) were found to be 98.67%and 97.5%,respectively,at 60°C and a reaction time of 40 min.We investigated the kinetics and thermodynamics of the leaching process in this study to better understand the mechanism of the leaching process.Based on a comparison with H_(2)O_(2) with respect to leaching efficiency,the optimal leaching parameters,and the activation energy,we determined that it is feasible to replace H_(2)O_(2) with SnCl_(2) as a leaching reductant in the leaching process.In addition,when SnCl_(2) is used in the acid-leaching process,Sn residue in the leachate may have a positive effect on the re-synthesis of nickel-rich cathode materials.Therefore,the results of this study provide a potential direction for the selection of reductants in the hydrometallurgical recovery of valuable metals from spent LIBs.

Regeneration of Al-doped LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) cathode material by simulated hydrometallurgy leachate of spent lithium-ion batteries

A uniform Al-doped LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) cathode material was prepared using a coprecipitation method to take advantage of the positive effect of Al on regenerated NCM(Ni,Co,Mn)cathode materials and ameliorate cumbersome and high-cost impurity removal processes during lithium-ion battery recycling.When the Al^(3+) content in the leachate was 1 at.%with respect to the total amount of transition metals(Ni,Co,and Mn),the produced Al-doped NCM cathode material increased concentrations of lattice oxygen and Ni^(2+).The initial specific capacity at 0.1C was 167.4 mA·h/g,with a capacity retention of 79.1%after 400 cycles at 1C.Further,this Al-doped sample showed improved rate performance and a smaller electrochemical impedance.These findings provide a reference for developing industrial processes to resynthesize cathode materials with improved electrochemical performance by incorporating Al^(3+) impurities produced during lithium-ion battery recycling.

Environmental and economic assessment of structural repair technologies for spent lithium-ion battery cathode materials

The existing recycling and regeneration technologies have problems,such as poor regeneration effect and low added value of products for lithium(Li)-ion battery cathode materials with a low state of health.In this work,a targeted Li replenishment repair technology is proposed to improve the discharge-specific capacity and cycling stability of the repaired LiCoO_(2) cathode materials.Compared with the spent cathode material with>50%Li deficiency,the Li/Co molar ratio of the regenerated LiCoO_(2) cathode is>0.9,which completely removes the Co_(3)O_(4) impurity phase formed by the decomposition of LixCoO_(2) in the failed cathode material after repair.The repaired LiCoO_(2) cathode mater-ials exhibit better cycling stability,lower electrochemical impedance,and faster Li^(+)diffusion than the commercial materials at both 1 and 10 C.Meanwhile,Li_(1.05)CoO_(2) cathodes have higher Li replenishment efficiency and cycling stability.The energy consumption and greenhouse gas emissions of LiCoO_(2) cathodes produced by this repair method are significantly reduced compared to those using pyrometallurgical and hydro-metallurgical recycling processes.

Solvent extraction and separation of cobalt from leachate of spent lithium-ion battery cathodes with N263 in nitrite media

To effectively separate and recover Co(Ⅱ) from the leachate of spent lithium-ion battery cathodes,we investigated solvent extraction with quaternary ammonium salt N263 in the sodium nitrite system.NO_(2)^(-)combines with Co(Ⅱ) to form an anion [Co(NO_(2))_(3)]^(-),and it is then extracted by N263.The extraction of Co(Ⅱ) is related to the concentration of NO_(2)^(-).The extraction efficiency of Co(Ⅱ) reaches the maximum of99.16%,while the extraction efficiencies of Ni(Ⅱ),Mn(Ⅱ),and Li(Ⅰ) are 9.27%-9.80% under the following conditions:30vol% of N263 and15vol% of iso-propyl alcohol in sulfonated kerosene,the volume ratio of the aqueous-to-organic phase is 2:1,the extraction time is 30 min,and1 M sodium nitrite in 0.1 MHNO_(3).The theoretical stages require for the Co(Ⅱ) extraction are performed in the McCabe–Thiele diagram,and the extraction efficiency of Co(Ⅱ) reaches more than 99.00% after three-stage counter-current extraction with Co(Ⅱ) concentration of 2544mg/L.When the HCl concentration is 1.5 M,the volume ratio of the aqueous-to-organic phase is 1:1,the back-extraction efficiency of Co(Ⅱ)achieves 91.41%.After five extraction and back-extraction cycles,the Co(Ⅱ) extraction efficiency can still reach 93.89%.The Co(Ⅱ) extraction efficiency in the actual leaching solution reaches 100%.

Technology for recycling and regenerating graphite from spent lithium-ion batteries

With the annual increase in the amount of lithium-ion batteries(LIBs),the development of spent LIBs recycling technology has gradually attracted attention.Graphite is one of the most critical materials for LIBs,which is listed as a key energy source by many developed countries.However,it was neglected in spent LIBs recycling,leading to pollution of the environment and waste of resources.In this paper,the latest research progress for recycling of graphite from spent LIBs was summarized.Especially,the processes of pretreatment,graphite enrichment and purification,and materials regeneration for graphite recovery are introduced in details.Finally,the problems and opportunities of graphite recycling are raised.

Priority recovery of lithium and effective leaching of nickel and cobalt from spent lithium-ion battery

The cathode materials of spent lithium-ion batteries(LIBs)were recovered via reductive roasting,Na_(2)CO_(3) leaching,and ammonia leaching.The effects of roasting parameters,Na_(2)CO_(3) leaching parameters,and ammonia leaching parameters on the leaching efficiencies of metals were explored.The results show that the mineral phase of spent LIBs is reconstructed during reductive roasting,and more than 99%of Li can be preferentially leached via Na_(2)CO_(3) leaching.Ni(99.7%)and Co(99.9%)can be leached via one-step ammonia leaching,and Mn cannot be leached.Thus,good leaching selectivity is achieved.The kinetic study shows that the leaching of Ni and Co conforms to chemical reaction control.

Lithium and manganese extraction from manganese-rich slag originated from pyrometallurgy of spent lithium-ion battery

Mn and Li were selectively extracted from the manganese-rich slag by sulfation roasting−water leaching.The extraction mechanisms of Mn and Li were investigated by means of XRD,TG−DSC,and SEM−EDS.73.71%Mn and 73.28%Li were leached under optimal experimental conditions:acid concentration of 82 wt.%,acid-to-slag mass ratio of 1.5:1,roasting temperature of 800°C,and roasting time of 2 h.During the roasting process,the manganese-rich slag first reacted with concentrated sulfuric acid,producing MnSO_(4),MnSO_(4)·H_(2)O,Li_(2)Mg(SO_(4))_(2),Al_(2)(SO_(4))_(3),and H_(4)SiO_(4).With the roasting temperature increasing,H_(4)SiO_(4) and Al_(2)(SO_(4))_(3) decomposed successively,resulting in generation of mullite and spinel.The mullite formation aided in decreasing the leaching efficiencies of Al and Si,while increasing the Li leaching efficiency.The formation of spinel,however,decreased the leaching efficiencies of Mn and Li.

Tailoring carbon chains for repairing graphite from spent lithium-ion battery toward closed-circuit recycling

Graphite, as a strategic mineral resource, the recycling from spent lithium-ion batteries(LIBs) has attracted considerable attention for meeting considerable economic value. However, closed-circuit recycling still suffers from the lack of effective repair methods. Considering the existing defects, a series of Cchain length carbons have been successfully introduced to repair spent graphite. Obviously, with the evolution of carbon resources, the thickness and pores of the coating layer were tailored with the functional groups. Benefitting from the increased active sites and created fold structure, their coulombic efficiency is obviously restored from 14% to 86.89%, while the stable capacity is kept at approximately 384.9 mAh gafter 100 cycles. Moreover, their excellent rate properties are kept about approximately 200 mAh gat2 C, meeting the standard of commercial materials. Supported by the detailed kinetic behaviors, the enhanced rate is mainly dominated by pseudocapacitive behaviors, accompanied by deepening redox reactions. Meanwhile, the cost of the proposed approach for recycling spent graphite is 894.87 $ t^(-1),and the recycling profit for regenerating graphite is approximately 7000 $ t^(-1). Given this, this work is anticipated to shed light on the closed-circuit recycling of spent graphite and offer significant strategies to repair graphite.

Upcycling the spent graphite/LiCoO_(2) batteries for high-voltage graphite/LiCoPO_(4)-co-workable dual-ion batteries

The worldwide proliferation of portable electronics has resulted in a dramatic increase in the number of spent lithium-ion batteries(LIBs).However,traditional recycling methods still have limitations because of such huge amounts of spent LIBs.Therefore,we proposed an ecofriendly and sustainable double recycling strategy to concurrently reuse the cathode(LiCoO_(2))and anode(graphite)materials of spent LIBs and recycled LiCoPO_(4)/graphite(RLCPG)in Li^(+)/PF^(-)_(6) co-de/intercalation dual-ion batteries.The recycle-derived dualion batteries of Li/RLCPG show impressive electrochemical performance,with an appropriate discharge capacity of 86.2 mAh·g^(-1) at25 mA·g^(-1) and 69%capacity retention after 400 cycles.Dual recycling of the cathode and anode from spent LIBs avoids wastage of resources and yields cathode materials with excellent performance,thereby offering an ecofriendly and sustainable way to design novel secondary batteries.

Extraction of lithium from the simulated pyrometallurgical slag of spent lithium-ion batteries by binary eutectic molten carbonates

The effective and low-temperature extraction of lithium from the pyrometallurgical slag of spent lithium-ion batteries(LIBs)remains a great challenge.Herein,potassium carbonate/sodium carbonate(K_(2)CO_(3)/Na_(2)CO_(3)),which could form a eutectic molten salt system at 720℃,was used as a roasting agent to extract lithium from pyrometallurgical slag.Lithium was successfully extracted from the slag by K_(2)CO_(3)/Na_(2)CO_(3) roasting followed by water leaching.Theoretical calculation results indicate that the lengths of Li-O bonds increase after K^(+)/Na^(+)adsorption,resulting in the easy release of Li^(+)from the LiAlSi_(2)O_(6) lattice after roasting with K_(2)CO_(3)/Na_(2)CO_(3).Thermogravimetry-differential scanning calorimetry results indicate that the eutectic phenomenon of K_(2)CO_(3) and Na_(2)CO_(3) could be observed at 720℃ and that the reaction of the slag and eutectic molten salts occurs at temperatures above 720℃.X-ray diffraction results suggest that Li^(+)in the slag is exchanged by K^(+)in K_(2)CO_(3) with the concurrent formation of KAlSiO_(4),while Na_(2)CO_(3) mainly functions as a fluxing agent.The lithium extraction efficiency can reach 93.87%under the optimal conditions of a roasting temperature of 740℃,roasting time of 30 min,leaching temperature of 50℃,leaching time of 40 min,and water/roasted sample mass ratio of 10:1.This work provides a new system for extracting lithium from the pyrometallurgical slag of spent LIBs.

Enhancement of leaching of cobalt and lithium from spent lithium-ion batteries by mechanochemical process

A mechanochemical method with SiO_(2)as the grinding aid was used to enhance the leaching efficiencies of Co and Li from spent lithium batteries(LIBs).Experiment results show that the optimal leaching efficiencies of 94.91%for Co and 97.22%for Li were obtained under the parameters of SiO_(2)/LiCoO_(2)mass ratio of 1:1,grinding speed of 500 r/min and grinding time of 30 min in citric acid.Characterization results indicate that the surficial properties of LiCoO_(2)were changed after mechanochemical grinding treatment due to the newly generated surfaces on LiCoO_(2).Meanwhile,the incompletely coordinated atomic structure and defective lattice structure lead to the activation of LiCoO_(2).The reduction effect of carbon black on Co^(3+)under the action of mechanical forces increases its leaching efficiencies in the citric acid solution.The proposed process was found efficiently to recover Co and Li from LiCoO_(2).