Progress,challenges,and prospects of spent lithium-ion batteries recycling:A review

The recycling and reutilization of spent lithium-ion batteries(LIBs)have become an important measure to alleviate problems like resource scarcity and environmental pollution.Although some progress has been made,battery recycling technology still faces challenges in terms of efficiency,effectiveness and environmental sustainability.This review aims to systematically review and analyze the current status of spent LIB recycling,and conduct a detailed comparison and evaluation of different recycling processes.In addition,this review introduces emerging recycling techniques,including deep eutectic solvents,molten salt roasting,and direct regeneration,with the intent of enhancing recycling efficiency and diminishing environmental repercussions.Furthermore,to increase the added value of recycled materials,this review proposes the concept of upgrading recycled materials into high value-added functional materials,such as catalysts,adsorbents,and graphene.Through life cycle assessment,the paper also explores the economic and environmental impacts of current battery recycling and highlights the importance that future recycling technologies should achieve a balance between recycling efficiency,economics and environmental benefits.Finally,this review outlines the opportunities and challenges of recycling key materials for next-generation batteries,and proposes relevant policy recommendations to promote the green and sustainable development of batteries,circular economy,and ecological civilization.

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.

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.

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.

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.

Surplus energy utilization of spent lithium-ion batteries for high-profit organolithiums

It is challenging to efficiently and economically recycle many lithium-ion batteries(LIBs)because of the low valuation of commodity metals and materials,such as LiFePO_(4).There are millions of tons of spent LIBs where the barrier to recycling is economical,and to make recycling more feasible,it is required that the value of the processed recycled material exceeds the value of raw commodity materials.The presented research illustrates improved profitability and economics for recycling spent LIBs by utilizing the surplus energy in lithiated graphite to drive the preparation of organolithiums to add value to the recycled lithium materials.This study methodology demonstrates that the surplus energy of lithiated graphite obtained from spent LIBs can be utilized to prepare high-value organolithiums,thereby significantly improving the economic profitability of LIB recycling.Organolithiums(R-O-Li and R-Li)were prepared using alkyl alcohol(R-OH)and alkyl bromide(R-Br)as substrates,where R includes varying hindered alkyl hydrocarbons.The organolithiums extracted from per kilogram of recycled LIBs can increase the economic value between$29.5 and$226.5 kg^(−1) cell.The value of the organolithiums is at least 5.4 times the total theoretical value of spent materials,improving the profitability of recycling LIBs over traditional pyrometallurgical($0.86 kg^(−1) cell),hydrometallurgical($1.00 kg^(−1) cell),and physical direct recycling methods($5.40 kg^(−1) cell).

Review of preferentially selective lithium extraction from spent lithium batteries: Principle and performance

Lithium,as the lightest and lowest potential metal,is an ideal "battery metal" and the core strategic metal of the new energy industry revolution.Recovering lithium from spent lithium batteries(LIBs)has become one of the significant approaches to obtaining lithium resources.At present,the lithium extraction being generally placed at the last step of the spent LIBs recovery process has puzzles such as high acid consumption,low Li recovery purity and low recovery efficiency.Selective lithium extraction at the first step of the recovery process can effectively solve those puzzles.Since lithium leaching is a non-spontaneous reaction requiring additional energy to achieve,it is found that these methods can be divided into five ways according to the different types of energy driving the reaction occurring:(ⅰ)electric energy driving lithium extraction;(ⅱ) chemical energy driving lithium extraction;(ⅲ) mechanical energy driving lithium extraction;(ⅳ) thermal energy driving lithium extraction;(ⅴ) other energy driving lithium extraction.Through the analysis of the principle,reaction process and results of recovering lithium methods can provide a few directions for scholars’ subsequent research.It is necessary to speed up the exploration of the principle of these methods.It is expected that this study could provide a reference for the research on the selective lithium extraction.

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.

Upcycling end of lithium cobalt oxide batteries to electrocatalyst for oxygen reduction reaction in direct methanol fuel cell via sustainable approach

Recycling spent lithium-ion batteries(SLIBs)has become essential to preserve the environment and reclaim vital resources for sustainable development.The typical SLIBs recycling concentrated on separating valuable components had limitations,including high energy consumption and complicated separation processes.This work suggests a safe hydrometallurgical process to recover usable metallic cobalt from depleted LiCoO_(2)batteries by utilizing citric acid as leachant and hydrogen peroxide as an oxidizing agent,with ethanol as a selective precipitating agent.The anode graphite was also recovered and converted to graphene oxide(GO).The above components were directly resynthesized to cobaltintegrated nitrogen-doped graphene(Co@NG).The Co@NG showed a decent activity towards oxygen reduction reaction(ORR)with a half-wave potential of 0.880 V vs.RHE,almost similar to Pt/C(0.888 V vs.RHE)and with an onset potential of 0.92 V vs.RHE.The metal-nitrogen-carbon(Co-N-C)having the highest nitrogen content has decreased the barrier for ORR since the reaction was enhanced for Co@NG-800,as confirmed by density functional theory(DFT)simulations.The Co@NG cathode catalyst coupled with commercial Pt-Ru/C as anode catalyst exhibits excellent performance for direct methanol fuel cell(DMFC)with a peak power density of 34.7 mW cm^(-2)at a discharge current density of120 m A cm^(-2)and decent stability,indicating the promising utilization of spent battery materials in DMFC applications.Besides,lithium was recovered from supernatant as lithium carbonate by coprecipitation process.This work avoids sophisticated elemental separation by utilizing SLIBs for other renewable energy applications,lowering the environmental concerns associated with recycling.

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.

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.

Selective recovery of lithium from spent lithium iron phosphate batteries using oxidation pressure sulfuric acid leaching system

Oxidation pressure leaching was proposed to selectively dissolve Li from spent LiFePO_(4) batteries in a stoichiometric sulfuric acid solution.Using O_(2) as an oxidant and stoichiometric sulfuric acid as leaching agent,above 97% of Li was leached into the solution,whereas more than 99% of Fe remained in the leaching residue,enabling a relatively low cost for one-step separation of Li and Fe.And then,by adjusting the pH of leachate,above 95% of Li was recovered in the form of the Li_(3)PO_(4) product through iron removal and chemical precipitation of phosphate.

Effective regeneration of high-performance anode material recycled from the whole electrodes in spent lithium-ion batteries via a simplified approach

Along with the extensive application of energy storage devices,the spent lithium-ion batteries(LIBs)are unquestionably classified into the secondary resources due to its high content of several valuable metals.However,current recycling methods have the main drawback to their tedious process,especially the purification and separation process.Herein,we propose a simplified process to recycle both cathode(LiCoO_(2))and anode(graphite)in the spent LIBs and regenerate newly high-performance anode material,CoO/CoFe2O4/expanded graphite(EG).This process not only has the advantages of succinct procedure and easy control of reaction conditions,but also effectively separates and recycles lithium from transition metals.The 98.43%of lithium is recovered from leachate when the solid product CoO/CoFe2O4/EG is synthesized as anode material for LIBs.And the product exhibits improved cyclic stability(890 mAh g^(-1) at 1 A g^(-1) after 700 cycles)and superior rate capability(208 mAh g^(-1) at 5 A g^(-1)).The merit of this delicate recycling design can be summarized as three aspects:the utilization of Fe impurity in waste LiCoO_(2),the transformation of waste graphite to EG,and the regeneration of anode material.This approach properly recycles the valuable components of spent LIBs,which introduces an insight into the future recycling.

A novel strategy of lithium recycling from spent lithium-ion batteries using imidazolium ionic liquid

In light of the increasing demand for environmental protection and energy conservation,the recovery of highly valuable metals,such as Li,Co,and Ni,from spent lithium-ion batteries(LIBs)has attracted widespread attention.Most conventional recycling strategies,however,suffer from a lack of lithium recycling,although they display high efficiency in the recovery of Co and Ni.In this work,we report an efficient extraction process of lithium from the spent LIBs by using a functional imidazolium ionic liquid.The extraction efficiency can be reached to 92.5%after a three-stage extraction,while the extraction efficiency of Ni-Co-Mn is less than 4.0%.The new process shows a high selectivity of lithium ion.FTIR spectroscopy and ultraviolet are utilized to characterize the variations in the functional groups during extraction to reveal that the possible extraction mechanism is cation exchange.The results of this work provide an effective and sustainable strategy of lithium recycling from 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).

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.

Recovery and regeneration of LiFePO_(4)from spent lithium-ion batteries via a novel pretreatment process

The recycling of spent LiFePO_(4)batteries has received extensive attention due to its environmental impact and economic benefit.In the pretreatment process of spent LiFePO_(4)batteries,the separation of active materials and current collectors determines the difficulty of the re-covery process and product quality.In this work,a facile and efficient pretreatment process is first proposed.After only freezing the electrode pieces and immersing them in boiling water,LiFePO_(4)materials were peeled from the Al foil.Then,after roasting under an inert atmosphere and sieving,all the cathode and anode active materials were easily and efficiently separated from the Al and Cu foils.The active materials were subjected to acid leaching,and the leaching solution was further used to prepare FePO_(4)and Li_(2)CO_(3).Finally,the battery-grade FePO_(4)and Li_(2)CO_(3)were used to re-synthesize LiFePO_(4)/C via the carbon thermal reduction method.The discharge capacities of re-synthesized LiFePO_(4)/C cathode were 144.2,139.0,133.2,125.5,and 110.5 mA·h·g−1 at rates of 0.1,0.5,1,2,and 5 C,which satisfies the requirement for middle-end LiFePO_(4)batteries.The whole process is environmental and has great potential for industrial-scale recycling of spent lithium-ion batteries.