Electrochemical recovery of cobalt and copper from spent Li-ion batteries as multilayer deposits

In this work, spent Li-ion batteries were used to form cobalt and copper multilayers by electrodeposition. The effects of pH on the nucleation and growth mechanism, morphology and crystalline structure were studied. The instantaneous nucleation mechanism occurs at pH 2.7 and progresses at pH 5.4 for cobalt electrodeposition on platinum, vitreous carbon and aluminum. Copper can be electrodeposited on cobalt by an instantaneous mechanism at pH 2.7 and progressively at pH 5.4. Using scanning electron microscopy, we verified a more porous electrodeposit at pH 5.4 than at pH 2.7. X-ray diffractograms showed the peaks of Cu₂O, CuO and the Co and Cu cubic centered face structures for both pH values at a charge density of 2.00 and 10.0 C cm⁻². The electric circuit obtained by electrochemical impedance spectroscopy for Co-Cu multilayer growth at both pH 2.7 and 5.4 with a charge density equal to 2.0 and 10.0 C cm⁻² on Al has the form R_s(R_pQL). The presence of the constant phase element (Q) is attributed to the irregularity of the Co-Cu multilayer electrodeposits, and the inductive element (L) is associated with cobalt dissolution in acidic solution.     

Hydrometallurgical separation of rare earth elements, cobalt and nickel from spent nickel-metal-hydride batteries

The separation of rare earth elements, cobalt and nickel from NiMH battery residues is evaluated in this paper. Analysis of the internal content of the NiMH batteries shows that nickel is the main metal present in the residue (around 50% in weight), as well as potassium (2.2-10.9%), cobalt (5.1-5.5%), rare earth elements (15.3-29.0%) and cadmium (2.8%). The presence of cadmium reveals that some Ni-Cd batteries are possibly labeled as NiMH ones. The leaching of nickel and cobalt from the NiMH battery powder with sulfuric acid is efficient; operating variables temperature and concentration of H₂O₂ has no significant effect for the conditions studied. A mixture of rare earth elements is separated by precipitation with NaOH. Finally, solvent extraction with D2EHPA (di-2-ethylhexyl phosphoric acid) followed by Cyanex 272 (bis-2,4,4-trimethylpentyl phosphinic acid) can separate cadmium, cobalt and nickel from the leach liquor. The effect of the main operating variables of both leaching and solvent extraction steps are discussed aiming to maximize metal separation for recycling purposes.     

A study of the separation of cobalt from spent Li-ion battery residues

Separation of the main metals contained in spent Li-ion batteries has been investigated using a treatment route consisting of the following steps: manual dismantling, acid leaching, precipitation with NH₄OH and liquid–liquid extraction using Cyanex 272 [bis(2,4,4-trimethylpentyl) phosphinic acid] as the extractant agent. Aluminium, cobalt, lead and lithium were the main metal species identified in the residue. Lead was found solely in the anode of the battery, so this metal can be separated manually from the other metal species, which were found to predominate in the cathode. The following operational variables were investigated in the acid leaching step: temperature, solid/liquid ratio, H₂SO₄ concentration and H₂O₂ concentration which was used as the oxidizing agent. Around 55% of aluminium, 80% of cobalt and 95% of lithium were leached from the cathode when leaching solutions with H₂O₂ were carried out. In the precipitation step, NH₄OH was added to the leach liquor to raise the pH and aluminium was partially separated from cobalt and lithium at pH 5. After filtration, the aqueous solution was submitted to a purification step by liquid–liquid extraction with Cyanex 272 and around 85% of cobalt was separated.     

Electrochemical recycling of cobalt from cathodes of spent lithium-ion batteries

In this work, cobalt from spent cellular telephone Li-ion batteries was recovered by electrochemical techniques. According to X-ray diffraction results, the composition of the positive electrode is LiCoO₂, Co₃O₄, C, and Al. The largest charge efficiency found was 96.90% at pH 5.40, potential applied of −1.00 V and a charge density of 10.0 °C cm⁻². The charge efficiency in the electrochemical recycling of cobalt decreases with the decrease in pH. The energy dispersive X-ray analysis (EDX) measurements of the electrodeposits showed that the surface is constituted of 100% cobalt. Scanning electron microscopy (SEM) showed a three-dimensional nucleus growth.     

Electrodeposition of cobalt from spent Li-ion battery cathodes by the electrochemistry quartz crystal microbalance technique

Information about the cobalt electrodeposition mechanism at different pH values was obtained using an electrochemistry quartz crystal microbalance (EQCM) technique as well as potentiodynamic and potentiostatic techniques. Potentiodynamic and potentiostatic electrodeposition of ionic cobalt at pH 5.40 occurs via a direct reduction mechanism. The mass/charge relation was found to be 33.00 g mol⁻¹. At pH 2.70, electrodeposition under potentiodynamic conditions occurs via a mechanism of cobalt reduction with the formation of adsorbed hydrogen. Potentiostatic analysis verified that cobalt reduction occurs simultaneously via direct reduction and with the formation of adsorbed hydrogen. The ratio mass/charge (M/z) is 13.00 g mol⁻¹ for potentiodynamic conditions and 26.00 g mol⁻¹ for potentiostatic conditions and potentiodynamic conditions. The cobalt electrodissolution occurs directly to Co²⁺ in pH 2.7 and through of the intermediary Co⁺ that is oxidized to Co²⁺ in pH 5.4.     

Mechanical properties of copper current collection foils of Li-ion batteries

集流体作为锂离子电池电极的重要组成部分,其力学性能对电极结构的设计和优化至关重要.通过表征负极用铜箔集流体的力学性能(弹性模量,屈服强度和断裂强度等),实现对集流体的合理,可靠使用,为优化电极结构提供指导.本文分别研究了三种不同厚度压延铜箔和电解铜箔的力学性能,发现电解铜箔和压延铜箔的弹性模量分别为70 GPa和50 GPa左右.铜箔的屈服强度随厚度减小而增大,表现出越薄越强的趋势.使用扫描电镜(SEM)观察微拉伸试验后的不同厚度铜箔集流体的断裂面,发现电解铜箔的断裂方式为脆性断裂,压延铜箔为韧性断裂.     

Hydrometallurgical process for recovery of cobalt from waste cathodic active material generated during manufacturing of lithium ion batteries

The paper presents a new leaching-solvent extraction hydrometallurgical process for the recovery of a pure and marketable form of cobalt sulfate solution from waste cathodic active material generated during manufacturing of lithium ion batteries (LIBs). Leaching of the waste was carried out as a function of the leachant H₂SO₄ concentration, temperature, pulp density and reductant H₂O₂ concentration. The 93% of cobalt and 94% of lithium were leached at suitable optimum conditions of pulp density: 100 g L⁻¹, 2 M H₂SO₄, 5 vol.% of H₂O₂, with a leaching time 30 min and a temperature 75 °C. In subsequent the solvent extraction study, 85.42% of the cobalt was recovered using 1.5 M Cyanex 272 as an extractant at an O/A ratio of 1.6 from the leach liquor at pH 5.00. The rest of the cobalt was totally recovered from the raffinate using 0.5 M of Cyanex 272 and an O/A ratio of 1, and a feed pH of 5.35. Then the co-extracted lithium was scrubbed from the cobalt-loaded organic using 0.1 M Na₂CO₃. Finally, the cobalt sulfate solution with a purity 99.99% was obtained from the cobalt-loaded organic by stripping with H₂SO_4.     

Research progress of water-based binder for Li-ion batteries

黏结剂是影响锂离子电池电化学性能的重要组成部分,合适的黏结剂可以提高黏结强度进而降低黏结剂的用量,并提高电化学性能以及一定程度地抑制膨胀,同时水性黏结剂的使用不仅降低成本,更有利于保护环境.本文综述了水性黏结剂在锂离子电池正,负极中的应用,及其良好的电化学性能和广阔的应用前景, 阐述了不同锂离子电池电极黏结剂的特征和优缺点,说明可以代替有机溶剂型黏结剂聚偏氟乙烯的使用,分析了锂离子电池电极黏结剂的未来发展方向.     

Amorphous ATO and amorphous ATO based composite anodes for Li-ion batteries

In this study, amorphous antimony doped tin oxide (ATO) coatings on Cr coated stainless steel and multiwall carbon nanotube (MWCNT) buckypaper substrates were prepared using a radio frequency (RF) magnetron sputtering process as anode materials in lithium-ion batteries. The MWCNT anode, amorphous SnO₂:Sb anode and amorphous SnO₂:Sb-MWCNT nanocomposite anode have shown first discharge capacities of 446 mA h g⁻¹, 1064 mA h g⁻¹ and 1462 mA h g⁻¹, respectively. The best cycling performance were observed for amorphous SnO₂:Sb-MWCNT nanocomposite anode.     

A Fe Mössbauer spectroscopy study of cobalt ferrite conversion electrodes for Li-ion batteries

The reverse micelles method has been employed to obtain cobalt ferrite samples. The effect of the type of surfactant and volumetric proportion of the aqueous and organic phases on the electrochemical behavior has been evaluated. The sample prepared using Span 80 as a surfactant and equivalent volumes of the aqueous and organic phases showed the highest capacity values and rate capabilities. It has been correlated to the better stability of the faradaic conversion process upon cycling for this sample. Based on the ⁵⁷Fe Mössbauer spectra of discharged electrodes, this result has been associated to the preservation of reduced iron atoms into the core of the particles. The metallic atoms are ready to be oxidized, thus sustaining the reversible electrochemical reaction in further cycles.     

Theoretical evaluation of high-energy lithium metal phosphate cathode materials in Li-ion batteries

Lithium metal phosphates (olivines) are emerging as long-lived, safe cathode materials in Li-ion batteries. Nano-LiFePO₄ already appears in high-power applications, and LiMnPO₄ development is underway. Current and emerging Fe- and Mn-based intercalants, however, are low-energy producers compared to Ni and Co compounds. LiNiPO₄, a high voltage olivine, has the potential for superior energy output (>10.7 Wh in 18650 batteries), compared with commercial Li(Co,Ni)O₂ derivatives (up to 9.9 Wh). Speculative Co and Ni olivine cathode materials charged to above 4.5 V will require significant advances in electrolyte compositions and nanotechnology before commercialization. The major drivers toward 5 V battery chemistries are the inherent abuse tolerance of phosphates and the economic benefit of LiNiPO₄: it can produce 34% greater energy per dollar of cell material cost than LiAl_0.05Co_0.15Ni_0.8O₂, today's “standard” cathode intercalant in Li-ion batteries.     

Partial self-sacrificing templates synthesis of sandwich-like mesoporous CN@Fe3O4@CN hollow spheres for high-performance Li-ion batteries

Integrating carbonaceous materials onto nano-scaled porous metal oxides to form shell-core-shell hollow structure has good prospects in the development of high-performance electrode materials for Li-ion battery, but it still remains challenging. Herein, with Fe₃O₄ hollow nanospheres as partial self-templates, we construct sandwich-like double nitrogen-doped C-shelled porous Fe₃O₄ hollow spheres by pyrolyzing polypyrrole (PPY) which is in situ polymerized on the interior and the exterior shells of Fe₃O₄ hollow spheres. And the polymerization time of PPY have important influence on thickness of carbon layer in the composites and further change their electrochemical performance. The shell-core-shell hollow structure offers highly contact between carbon and porous Fe₃O₄ and provides amount of volume stress buffer nanospaces during electrochemical processes, which promotes electron transport effectively and keeps good structural stability. The obtained sandwich-like double N-doped C-shelled porous Fe₃O₄ hollow spheres (CN@Fe₃O₄@CN HSs) are prepared as Li-ion battery anode and show an ultrahigh reversible specific capacity, high rate capability, remarkable cycle stability, excellent capacity retention (high capacity of 1048 mA h g⁻¹ after 300 cycles at 0.1 A g⁻¹, which is about 99.1% of the capacity in the 2nd cycle) and high coulombic efficiency (about 99% over 300 cycles). This research shows great potential of the sandwich-like shell-core-shell hollow structure in Li-ion batteries.     

The anode environmentally friendly for water electrolysis based in LiCoO2 recycled from spent lithium-ion batteries

In this paper, a new anode for oxygen evolution reaction was developed from recycling of spent Li-ion cathode. After heating at 400 °C for 24 h, the spent cathode has LiCoO₂ and Co₃O₄ in its composition. This new material was mixed with graphite and conformed in tablet for application as anode in oxygen evolution reaction in alkaline solution (NaOH 6.0 mol L⁻¹). The concentrations of cathode in this mixture were 0, 10, 20 and 50% in mass. The best condition was 10% in mass. Under this condition the evolution of oxygen reaches 1010 mA cm⁻², however, for pure graphite the current density reaches only 600 mA cm⁻². Thus, this work offers an optimal choice for the waste generated by the Li-ion batteries.     

Illustration of experimental,machine learning,and characterization methods for study of performance of Li-ion batteries

The development of fault diagnosis of Li-ion batteries used in electric vehicles is vital. In this perspective, the present work conducted a comprehensive study for the evaluation of coupled and interactive influence of charging ratio, number of cycles, and voltage on the discharge capacity of Li-ion batteries to predict the life of battery. The charging-discharging experimental tests on Li-ion batteries have been performed. The data such as charging ratio, number of cycles, voltage, and discharge capacity of Li-ion batteries are measured. Machine learning approach of neural networks is then applied on the obtained data to compute the effects, normal distribution, parametric analysis, and sensitivity analysis of the input parameters on the capacity of battery. It can be noticed that discharge capacity increased with an increase in full voltage. Further, it has been observed from the sensitivity analysis that the full voltage is most relevant parameters to the capacity of the battery. Additionally, scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) of the electrodes before and after experiments have been performed, to investigate the elemental dissolution due to the charging/discharging cycles. The findings and analysis from the proposed study shall facilitate experts in making decisions on the remaining life and charging capacity of the battery.     

Low-temperature behavior of graphite-tin composite anodes for Li-ion batteries

The challenge of increasing low-temperature performances of anodes for Li-ion batteries is faced by preparing graphite-tin composite electrodes. The anodes are prepared by mixing partially oxidized graphite with nanometric Sn powder or by coating the oxidized graphite electrode with a thin Sn layer. Long-term cycling stability and intercalation/deintercalation performances of the composite anodes in the temperature range 20 °C to −30 °C are evaluated. Kinetics is investigated by cyclic voltammetry and electrochemical impedance spectroscopy, in the attempt to explain the role of Sn in reducing the overall electrode polarization at low temperature. Two possible mechanisms of action for bulk metal powder and surface metal layer are proposed.     

Studies on the degradation of Li-ion batteries by the use of microreference electrodes

Li-ion batteries made by the Lithylene technology were investigated after extensive cycling for a mechanistic understanding of the capacity fade phenomena. The batteries cycled 500 times at 0.5 C were found to lose 13% of their original capacity, which was solely due to the loss of active materials. The negative electrode maintained its capacity to contain Li⁺ ions from the positive electrode. The loss of positive electrode materials was attributed to formation and thickening of the surface layer and structure disorder evidenced by XRD measurements. In situ impedance measurements revealed that the positive electrode was also responsible for the impedance rise upon cycling. The charge transfer resistance was found to be the most influential factor in the battery impedance, which increased exponentially during cycling. This increase was proved not due to the decrease of positive electrode surface area but resulted from growth of the surface layer.     

Hierarchical porous cobalt oxide array films prepared by electrodeposition through polystyrene sphere template and their applications for lithium ion batteries

Hierarchical porous cobalt oxide (Co₃O₄) array films are successfully prepared by electrodeposition through polystyrene sphere monolayer template. The as-prepared Co₃O₄ array films exhibit three typical porous structures from non-close-packed bowl array to close-packed bowl array and hierarchical two layer array structures. These Co₃O₄ array films have a hierarchical porous structure, in which the skeleton is composed of ordered arrays possessing nanoporous walls. A possible growth mechanism of porous Co₃O₄ array films is proposed. As anodes for Li ion batteries, the as-prepared Co₃O₄ array films exhibit quite good cycle life and high capacity. The first discharge capacity for the three Co₃O₄ array films is 1511, 1475, 1463 mAh g⁻¹, respectively, and their initial coulombic efficiencies are as high as 72%. The specific capacity after 50 cycles for the three electrodes is 712, 665 and 640 mAh g⁻¹ at 1C rate, corresponding to 80%, 75%, 72% of the theoretical value (890 mAh g⁻¹), respectively.     

Constructing Janus SnSSe and graphene heterostructures as promising anode materials for Li-ion batteries

Developing efficient anode materials for Li-ion batteries is becoming increasingly important but is still challenging to collect relevant information about their adsorption and diffusion. Herein, by means of density functional theory (DFT) computations, the Janus SnSSe, and graphene van der Waals heterostructures (ie, SSnSe/G and SeSnS/G) are systematically investigated by first principles calculations, aiming at constructing promising anode materials for Li-ion batteries (LIBs). The results have demonstrated that the SnSSe/G heterostructures exhibits a semimetal-to-metal transition after incorporating Li, indicating enhanced conductivity compared to monolayer Janus SnSSe or graphene. Moreover, the SnSSe/G heterostructures can maintain favorable structural stability and ultrahigh stiffness well after applying the strain or adsorption of lithium atoms, thereby ensuring the pulverization resistance. In addition, the energy barriers of Li atoms diffusion are very low, which are expected to achieve a fast charge/discharge rate. Meanwhile, the estimated storage capacity of Li on SnSSe/G heterostructures could achieve 472.66 mA h g^?1, which greatly improves the storage capacity. These interesting results show that Janus SnSSe/G heterostructures could be used as excellent anode materials for LIBs.     

Direct synthesis and coating of advanced nanocomposite negative electrodes for Li-ion batteries via electrospraying

A direct approach for the synthesis and coating of advanced nanocomposite negative electrodes via a single-step process at low temperature is presented. Metal-oxide/PVdF nanocomposites are obtained in one step by electrospray pyrolysis of precursor solutions containing dissolved metal salts together with polyvinylidene fluoride (PVdF) as binder. In this way, small oxide nanoparticles are generated and dispersed in situ in the binder creating nanocomposite structures, while being coated at once as thin electrode layers on stainless steel coin cell cans. The intimate contact between the nanoparticles and the binder favours enhanced adhesion of the materials in the overall electrode structure and adequate electrochemical performances are obtained without any conductive additive. Three nanocomposite oxide/PVdF materials (i.e. SnO₂, CoO and Fe₂O₃) are reported here as preliminary examples of negative electrodes. The results show that this approach is suitable, not only for the fabrication of nanocomposite electrodes for Li-ion batteries, but also for other novel applications.     

Improvement of electrochemical and structural properties of LiMn2O4 spinel based electrode materials for Li-ion batteries

Spinel LiMn₂O₄ and LiM_0.02Mn_1.98O₄ (where M is Zn, Co, Ni and In) were produced via facile sol–gel method and Cu/LiMn₂O₄, Cu/LiM_0.02Mn_1.98O₄, Ag/LiMn₂O₄ and Ag/LiM_0.02Mn_1.98O₄ binary composite electrode materials were produced via electroless coating techniques as a positive electrode material for Li-ion batteries. The phase composition, morphology and electrochemical properties of the synthesized materials were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), cyclic voltammometry (CV), galvanostatic charge–discharge tests and electrochemical impedance spectroscopy (EIS). The synthesized cathode active materials are characterized as single phase spinel LiMn₂O₄ with degree of crystallization and uniform particle size distribution. Best results were obtained with electrodes substituted with In and an initial discharge capacity of 134 mAhg⁻¹ after 50 cycles. The improvement in the cycling performance may be attributed to stabilization of spinel structure by smaller lattice constant when manganese ion was partially substituted with In³⁺ ions. EIS analysis also confirms that the obvious improvement in Ag coating is mainly attributed to the accelerated phase transformation from layered phase to spinel phase and highly stable electrolyte/electrode interface due to the suppression of electrolyte decomposition.