Recovery of cathode materials from spent lithium-ion batteries and their application in preparing multi-metal oxides for the removal of oxygenated VOCs: Effect of synthetic methods

LiCoO2 impregnated nano-hierarchical ZSM-5 assisted catalytic upgrading of Kraft lignin-derived liquefaction bio-oil

In this study, Kraft lignin-derived bio-oil was upgraded with LiCoO2 or Co3O4-impregnated hierarchical nano-ZSM-5 catalysts. The synthesized catalysts were characterized by N2-Ads-Des, XRD, XPS, NH3-TPD, FTIR, FESEM and ICP-OES analyses. Upon incorporation of LiCoO2 and Co3O4 onto the HZSM-5 support, the MFI structure of HZSM-5 remained intact. All the catalysts displayed a combination of Type-I and -IV isotherms. The upgraded bio-oil showed a significant increase in the amounts of alkylated guaiacols owing to the reduction in unsubstituted guaiacols, alkenyl guaiacols, and homovanillic acid. Hydrogenation, alkylation, and deoxygenation were the plausible bio-oil upgrading pathways. With the increase in cobalt content, weak acidity decreased through all the catalysts, while LiCoO2 provided supplementary acid sites that increased the total acidity of LiCoO2/HZSM-5 compared to the Co3O4/HZSM-5 catalyst. LiCoO2/HZSM-5 with a low cobalt content (5% and 10% Co) displayed high selectivity for the production of alkylated guaiacols owing to their strong acidity. The upgraded bio-oils showed an increase in carbon and hydrogen followed by a decrease in oxygen content. The maximum higher heating value (∼29.83 MJ kg-1) was obtained for the 10% Co (LiCoO2)/HZSM-5 catalyst. In general, LiCoO2/HZSM-5 outperformed the Co3O4/HZSM-5 catalyst. XRD of the spent 10% Co (LiCoO2)/HZSM-5 suggested the complete loss of lithium from the catalyst with the retention of the MFI structure of the HZSM-5 support. In this study, it was successfully demonstrated that the main constituent of the cathode material of spent lithium-ion batteries i.e. LiCoO2 could be employed to synthesize a novel and cheap catalyst for bio-oil upgrading while addressing the e-waste management issue in a sustainable manner.

Catalytic degradation of benzene over non-thermal plasma coupled Co-Ni binary metal oxide nanosheet catalysts

Non-thermal plasma (NTP) has been demonstrated as one of the promising technologies that can degrade volatile organic compounds (VOCs) under ambient condition. However, one of the key challenges of VOCs degradation in NTP is its relatively low mineralization rate, which needs to be addressed by introducing catalysts. Therefore, the design and optimization of catalysts have become the focus of NTP coupling catalysis research. In this work, a series of two-dimensional nanosheet Co-Ni metal oxides were synthesized by microwave method and investigated for the catalytic oxidation of benzene in an NTP-catalysis coupling system. Among them, Co₂Ni₁O_x achieves 60% carbon dioxide (CO₂) selectivity (S_CO2) when the benzene removal efficiency (RE_benzene) reaches more than 99%, which is a significant enhancement compared with the CO₂ selectivity obtained without any catalysts (38%) under the same input power. More intriguingly, this S_CO2 is also significantly higher than that of single metal oxides, NiO or Co₃O₄, which is only around 40%. Such improved performance of this binary metal oxide catalyst is uniquely attributed to the synergistic effects of Co and Ni in Co₂Ni₁O_x catalyst. The introduction of Co₂Ni₁O_x was found to promote the generation of acrolein significantly, one of the key intermediates found in NTP alone system reported previously, suggest the benzene ring open reaction is promoted. Compared with monometallic oxides NiO and Co₃O₄, Co₂Ni₁O_x also shows higher active oxygen proportion, better oxygen mobility, and stronger low-temperature redox capability. The above factors result in the improved catalytic performance of Co₂Ni₁O_x in the NTP coupling removal of benzene.

The Foreseeable Future of Spent Lithium-Ion Batteries: Advanced Upcycling for Toxic Electrolyte, Cathode, and Anode from Environmental and Technological Perspectives

With the rise of the new energy vehicle industry represented by Tesla and BYD, the need for lithium-ion batteries (LIBs) grows rapidly. However, owing to the limited service life of LIBs, the large-scale retirement tide of LIBs has come. The recycling of spent LIBs has become an inevitable trend of resource recovery, environmental protection, and social demand. The low added value recovery of previous LIBs mostly used traditional metal extraction, which caused environmental damage and had high cost. Beyond metal extraction, the upcycling of spent LIBs came into being. In this work, we have outlined and particularly focus on sustainable upcycling technologies of toxic electrolyte, cathode, and anode from spent LIBs. For electrolyte, whether electrolyte extraction or decomposition, restoring the original electrolyte components or decomposing them into low-carbon energy conversion is the goal of electrolyte upcycling. Direct regeneration and preparation of advanced materials are the best strategies for cathodic upcycling with the advantages of cost and energy consumption, but challenges remain in industrial practice. The regeneration of advanced graphite-based materials and battery-grade graphite shows us the prospect of regeneration of anode. Furthermore, the challenges and future development of spent LIBs upcycling are summarized and discussed from technological and environmental perspectives.

Applications of Spent Lithium Battery Electrode Materials in Catalytic Decontamination: A Review

For a large amount of spent lithium battery electrode materials (SLBEMs), direct recycling by traditional hydrometallurgy or pyrometallurgy technologies suffers from high cost and low efficiency and even serious secondary pollution. Therefore, aiming to maximize the benefits of both environmental protection and e-waste resource recovery, the applications of SLBEM containing redox-active transition metals (e.g., Ni, Co, Mn, and Fe) for catalytic decontamination before disposal and recycling has attracted extensive attention. More importantly, the positive effects of innate structural advantages (defects, oxygen vacancies, and metal vacancies) in SLBEMs on catalytic decontamination have gradually been unveiled. This review summarizes the pretreatment and utilization methods to achieve excellent catalytic performance of SLBEMs, the key factors (pH, reaction temperature, coexisting anions, and catalyst dosage) affecting the catalytic activity of SLBEM, the potential application and the outstanding characteristics (detection, reinforcement approaches, and effects of innate structural advantages) of SLBEMs in pollution treatment, and possible reaction mechanisms. In addition, this review proposes the possible problems of SLBEMs in practical decontamination and the future outlook, which can help to provide a broader reference for researchers to better promote the implementation of “treating waste to waste” strategy.

Catalytic Degradation of Toluene over MnO2/LaMnO3: Effect of Phase Type of MnO2 on Activity

Series of α, β, γ, δ type MnO2 supported on LaMnO3 perovskite was developed by a one-pot synthesis route. Compared with α-MnO2, β-MnO2, γ-MnO2, δ-MnO2 and LaMnO3 oxides, all MnO2/LaMnO3 showed promotional catalytic performance for toluene degradation. Among them, α-MnO2/LaMnO3 holds the best active and mineralization efficiency. By the analysis of N2 adsorption-desorption, XPS and H2-TPR, it can be inferred that the improved activity should be ascribed to the higher proportion of lattice oxygen, better low-temperature reducibility and larger specific surface area. Besides, the byproducts from the low-temperature reaction of toluene oxidation were detected by a TD/GC-MS, confirming the presence of the intermediates. Combined with the in-situ DRIFTS, the catalytic degradation path of toluene oxidation has also been discussed in depth.

Synthesis of fatty acid-based ammonium ionic liquids and their application for extraction of Co(II) and Ni(II) metals ions from aqueous solution

Leaching of cobalt and nickel into diverse water streams has become an environmental hazard and is continuously impacting human health through the food chain. Solvent extraction is the most widely accepted for separating these metals, but traditional extractants employed in conjunction with molecular diluents often lack selectivity and caused major environmental hurdles. Therefore, the development of cost-effective, environmentally friendly technologies for recovering these heavy metals has been strongly encouraged in recent years. Herein, two halogens free, low viscous, biocompatible fatty acid-based hydrophobic ionic liquids (ILs), i.e., methytrioctylammonium oleate, methytrioctylammonium linoleate were synthesized, analytically characterized and employed for recovery of cobalt, Co(II) and nickel, Ni(II) from their aqueous solutions. Extraction behaviour of Co(II) and Ni(II) was further evaluated by varying equilibrium time, ILs molar concentration, metal loading, and temperature. Thermodynamic parameters such as enthalpy change and Gibbs free energy change were also studied during extraction process. Slope analysis suggested that the extraction mechanism was an exothermic process that followed ion-transfer from the aqueous phase to the organic phase. Results showed that both fatty acid based-ILs were found to be capable of extracting >99% of Co(II) and Ni(II) from aqueous solutions at 298 K, in 15 min of shaking time using a 1:1 (org: aq.) ratio at low concentrations of 2.5-10 g L^-1. Furthermore, for methyltrioctylammonium oleate IL, Co(II) extraction was selectively preferred over Ni(II) extraction when the metal concentration was increased to above to 10 g L^-1. The stripping results showed that 2 M H₂SO₄, and 2 M HCl successfully stripped out >99% of Co(II) and Ni(II) from the organic phase, respectively compared to HNO₃.

Transformation and migration mechanism of fluorine-containing pollutants in the pyrolysis process of spent lithium-ion battery

Pyrolysis is an effective method to remove organics (e.g. electrolytes and binders) from spent lithium-ion battery (LIB). In this study, the co-pyrolysis characteristics of fluorine-containing substances and active materials from LIB were investigated using thermogravimetric-differential scanning calorimetry (TG-DSC), infrared spectroscopy (IR), and mass spectrometry (MS) analysis. Associated with the pyrolysis, active materials adsorb the residues of electrolyte on the surface and into the pores (20-200 °C), while polyvinylidene fluoride (PVDF) forms a liquid film to cover the local surface of active materials (400-500 °C). These interactions prevent deep removal of organics, leaving fluorine-containing contaminants in active materials. The barrier effect of PVDF liquid mesophase on the removal of organics with secondary liquidous phase formation during pyrolysis was confirmed by in situ optical observation. The migration behavior of fluorine element during the pyrolysis of black mass (BM) from spent LIB was also investigated. With pyrolysis temperature increasing from 100 °C to 600 °C, the dissociable fluorine content in pyrolyzed BM increased from 1.4 wt% to 3.7 wt%. The fluorine-containing contaminants in BM cannot be removed completely by simply increasing pyrolysis temperature. This study provides a better understanding on the transformation of fluorine-containing pollutants during the pyrolysis of BM.

Sustainably recycling spent lithium-ion batteries to prepare magnetically separable cobalt ferrite for catalytic degradation of bisphenol A via peroxymonosulfate activation

A selective separation-recovery process based on tuning organic acid was proposed to the resource recycling of spent lithium-ion batteries (LIBs) for the first time. The low-cost preparation of CoFe₂O₄, reuse of waste acid and recovery of Li can be realized in this process, simultaneously. Li and Co in spent LIBs can be leached efficiently using citric acid as a leaching agent, and separated effectively from leaching solution by tuning oxalic acid content. The results from the characterizations of the prepared CoFe₂O₄ (CoFe₂O₄-LIBs) show that it possesses higher ratio of Co(II)/Co(III) and Fe(II)/Fe(III), larger surface specific area and more number of acid sites in comparison with pure CoFe₂O₄. Besides, CoFe₂O₄-LIBs was used to activate peroxymonosulfate (PMS) for the degradation of bisphenol A (BPA). Interestingly, its degradation performance is superior to that of pure CoFe₂O₄ and the related Co-based catalysts. The excellent degradation performance can be maintained in presence of inorganic ions (e.g., Cl^-, HCO₃^-, H₂PO₄^- and NO₃^-) with high concentration or humic acid. Moreover, surface-bound SO₄^∙- is considered as the main reactive species for the degradation of BPA. More importantly, CoFe₂O₄-LIBs can be readily recycled by using an external magnet and own superior ability of regeneration.

Improved catalytic oxidation of propylene glycol methyl ether over Sm-Mn and Sm-Co perovskite-based catalysts prepared by the recycling of spent ternary lithium-ion battery

The spent ternary lithium-ion batteries were utilized as the precursors to prepare Sm-Mn and Sm-Co perovskite oxides (SmMnO₃-spent ternary lithium-ion battery [STLIB] and SmCoO₃-STLIB) for the first time. Their catalytic activities were evaluated by catalytic oxidation of propylene glycol methyl ether. Compared with that of the catalysts synthesized by analytical reagents, the catalytic activities of SmMnO₃-STLIB and SmCoO₃-STLIB had been significantly enhanced. The analysis of X-ray photoelectron spectroscopy (XPS) showed that the molar ratios of Mn⁴⁺/Mn³⁺ and O_ads/O_latt of SmMnO₃-STLIB were higher than that of pure SmMnO₃ and the Co³⁺/Co²⁺ ratios of SmCoO₃-STLIB was much larger than that of pure SmCoO₃. The hydrogen temperature-programmed reduction (H₂-TPR) and N₂ adsorption-desorption tests determined that the reducibilities and specific surface areas of SmMnO₃-STLIB and SmCoO₃-STLIB were also superior to pure catalysts. Ultimately, the by-products of the catalytic oxidation of propylene glycol methyl ether over SmMnO₃-STLIB were also detected by gas chromatography-mass spectrometry (GC-MS). This work will provide a demonstration for the resource utilization of spent lithium ions batteries and the analysis of the increased activity obtained by using spent lithium ions batteries as the precursors to prepare catalysts.