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.     

Effects of heteroatoms on electrochemical performance of electrode materials for lithium ion batteries

Recent studies of lithium ion batteries focus on improving electrochemical performance of electrode materials and/or lowering cost. Doping of active materials with heteroatoms is one promising method. This paper reviews the effects of heteroatoms on anode materials such as carbon- and tin-based materials, and cathode materials such as LiCoO₂, LiNiO₂, LiMn₂O₄ and V₂O₅. There are favorable and unfavorable effects, which depend on the species and physicochemical states of heteroatoms and the parent electrode materials. In the application of lithium ion batteries advantageous factors should be exploited, unwelcome side effects should be avoided as far as possible. Considerable gains towards improved electrochemical performance of the electrode materials have been achieved. Nevertheless, there are still problems needing further investigation including theoretical aspects, which will in the meanwhile stimulate the investigation for better electrode materials.     

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 wide-spread 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 effi-ciency of Ni-Co-Mn is less than 4.0％.The new process shows a high selectivity of lithium ion.FTIR spec-troscopy 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.     

Enhancing the electrochemical performance of d-Mo2CTx MXene in lithium-ion batteries and supercapacitors by sulfur decoration

With the development of the energy industry, electrochemical energy storage technology is increasingly involved in developing innovations in the field. The materials of the electrode have a significant influence on the performance of energy storage devices. For this purpose, two-dimensional MXene with excellent electrical conductivity, mechanical strength, and a variety of possible surface-active terminations are attracting much attention. In the present work, S-decorated d-Mo₂CT_x (d-Mo₂CT_x--S) is designed. The first-principles calculations reveal that it may possess good energy storage characteristics. Due to the decoration with S, unique morphology and structure are obtained, conferring stability, optimized Li⁺ storage, improved charge transport, and lithium-ion adsorption capabilities. Compared with d-Mo₂CT_x, d-Mo₂CT_x--S exhibits higher discharge capacity (623 mAh g⁻¹ at 1 A g⁻¹) as lithium-ion electrode material and higher specific capacitance (561 F g⁻¹ at 1 A g⁻¹). As a supercapacitor, the material also shows excellent cyclic stability (20,000 charge-discharge cycles). This work may inspire the exploration of other MXene and new surface functionalization methods to improve the performance of MXene as electrode materials for new energy devices.     

Preparation and electrochemical performance of flower-like hematite for lithium-ion batteries

Flower-like hematite (α-Fe₂O₃) has been successfully prepared by heat-treatment from the iron(III)-oxyhydroxide precursor, which is obtained by the hydrolysis of FeCl₃ solution in the presence of NaClO. In this process, no templates or catalysts are required. SEM and TEM characterizations confirm that micro-flowers are composed of several dozen self-assembled nanopetals with the thickness of about 20 nm. On the basis of the morphology investigations in time-dependent experiments, the possible growth mechanism of the flower-like α-Fe₂O₃ is proposed, which is similar to a two-stage growth process. Furthermore, as an anode electrode material for rechargeable lithium-ion batteries, the flower-like α-Fe₂O₃ exhibits excellent electrochemical performance, which can be attributed to the high surface area induced by the flower-like structure, the short lithium diffusion length and the restriction of volume change of the Li⁺ insertion/extraction.     

Delafossite CuCrO2 nanoparticles as possible electrode material for electrochemical supercapacitor

Delafossites are popularly known materials for thermoelectric and electrochemical device applications due to their layered structural features. In this paper, delafossite CuCrO₂ nanoparticles (NPs) have been synthesized using a simple chemical procedure and are investigated as a supercapacitor material. To determine the phases of delafossite CuCrO₂ NPs, the morphological and phase formation experiments were conducted using diffraction patterns and microscopic analysis. The cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) studies were performed to evaluate the supercapacitative behavior of delafossite CuCrO₂ NPs. As prepared delafossite CuCrO₂ NPs based electrode showed an outstanding electrochemical property as compared to annealed delafossite CuCrO₂ NPs at 300–500 °C. A good specific capacitance of ～464.7 Fg^-1 at 0.01 Vs^-1 was found for the fabricated supercapacitor using non-annealed delafossite CuCrO₂ NPs based electrode, which was further validated by GCD results. The electrochemical supercapacitor fabricated with both non-annealed and annealed delafossite CuCrO₂ NPs displayed considerably the outstanding cycling stability by maintaining up to ～88% after 5000 cycles. This work sets the pace for a new and efficient method of preparing delafossite CuCrO₂ for high-performance electrochemical supercapacitors.     

Improving the electrochemical performance of polyaniline electrode for supercapacitor by chemical oxidative copolymerization with p-phenylenediamine

A series of poly(aniline-co-p-phenylenediamine) (P(ANI-co-PPDA)) copolymers were synthesized via the chemical oxidative polymerization of aniline with p-phenylenediamine (PPDA) as the comonomer. The structure and morphology of the P(ANI-co-PPDA) copolymers prepared with different feeding ratio of PPDA under different polymerizing temperature were compared with the two homopolymers polyaniline (PANI) and poly(p-phenylenediamine) (PPPDA). It is interesting to find that the electrical conductivity, specific capacitance and cycling stability of the P(ANI-co-PPDA) copolymer electrode materials were obviously improved with certain feeding ratio of PPDA, compared with those two homopolymers.     

Preparation and electrochemical performance of polyaniline-based carbon nanotubes as electrode material for supercapacitor

Nitrogen-containing carbon nanotubes (CNTs) with open end and low specific surface area were prepared via the carbonization of polyaniline (PANI) nanotubes synthesized by a rapidly mixed reaction. On the basis of analyzing the morphologies and structures of the original and carbonized PANI nanotubes, the electrochemical properties of PANI-based CNTs obtained at different temperatures as electrode materials for supercapacitors using 30 wt.% aqueous solution of KOH as electrolyte were investigated by galvanostatic charge/discharge and cyclic voltammetry. It was found that the carbonized PANI nanotubes at 700 °C exhibit high specific capacitance of 163 F g⁻¹ at a current density of 0.1 A g⁻¹ and excellent rate capability in KOH solution. Using X-ray photoelectron spectroscopy measurement the nitrogen state and content in PANI-CNTs were analysed, which could play important roles for the enhancement of electrochemical performance. When the appropriate content of nitrogen is present, the presence of pyrrole or pyridone and quaternary nitrogen is beneficial for the improvement of electron mobility and the wettability of electrode.     

A green approach for cohesive recycling and regeneration of electrode active materials from spent lithium-ion batteries

The implementation of the green energy transition by reducing reliance on fossil fuels has fueled the burgeoning demand for lithium-ion batteries in grid-level energy storage systems and electric vehicles. The growth of portable electronic devices has also contributed to this exponential demand, creating both logistical and environmental challenges in the supply of raw materials such as lithium and the management of end-of-life batteries. Current recycling methods for spent batteries are both energy-intensive and inefficient. To address these issues, a green approach using organic acid mixtures has been proposed to reclaim lithium from spent cathodes and recover and purify graphite from spent anodes, while also regenerating its structure. The effectiveness of this method is demonstrated through the use of organic acid mixtures to leach and reclaim lithium from NCM 622 batteries. On the anode side, a curing–leaching strategy using organic acids is employed to purify spent graphite, which is subsequently calcined to enhance its interlayer structure conducive to better intercalation of Li⁺ and improve electrochemical performance. Additionally, recovered graphite is tailored with carbon using water bath carbonization to repair structural defects caused by lithium intercalation and improve electrochemical performance while augmenting the regenerated graphite's quality, equipping it to be reused in batteries or upcycled applications.     

Feasibility of bamboo-based activated carbons for an electrochemical supercapacitor electrode

This study focused on the preparation and electrochemical properties of bamboo-based activated carbons (ACs) through carbonization and subsequent activation with steam and non-aqueous electrolyte solutions. The specific surface areas and the capacitances of samples ranged from 445 to 1,025 m²/g and from 5 to 60 F/g, respectively, depending on the activation conditions. The sample activated at 900 ‡C for 60 min under our experimental conditions exhibited the highest capacitance and the largest specific surface area.     

废旧锂离子电池回收处理技术与资源化再生技术进展

近年来,随着消费电子商品、电动车和大规模储能市场的快速发展,作为目前占据最多市场份额的锂离子电池的产量也随之快速增长,随之产生的废旧锂离子电池的数量和重量呈现出了井喷式的上涨。从其巨大的数量、环境保护和资源再生的角度来看,废旧锂离子电池都具有很高的回收价值和潜力。本文主要从实验室研究和工业应用两个角度总结了目前主要的回收处理方法和流程,重点介绍了利用废旧锂离子电池电极材料重新再生和合成新的电极材料的研究进展。目前废旧锂离子电池回收处理存在的问题主要是：电极材料的复杂多样性导致分离提纯过程困难,回收过程易产生二次污染以及回收的经济激励不足。未来的发展趋势在于结合绿色环保和低成本经济,研究高效的回收处理工艺流程。     

Dual-functional C-composited Na3.16Fe2.42(P2O7)2 cathode toward superior electrochemical performance for sodium-ion batteries

The development of a polyanion cathode for sodium-ion batteries is expected to accelerate the application of sodium-ion batteries in large-scale energy storage systems. However, the poor electrode conductivity is still a great challenge. In this paper, the novel carbon composite polyanion compound Na_3.16Fe_2.42(P₂O₇)₂@C (NFP@C) is developed through high-energy ball milling followed by annealing. The porous NFP nanoparticles modified with dual-functional C-composited for amorphous carbon coating and carbon nanofibers interpenetrating deliver excellent capacity retention of 85.3% after 1000 cycles at 5 C, which is more outstanding than pure NFP. X-ray diffraction, in situ galvanostatic intermittent titration techniques, electrochemical impedance spectroscopy, and cyclic voltammetry were performed to investigate the stability and sodium diffusion of NFP@C. The results show that the systematic and comprehensive dual-functional conductive network modification enables NFP exhibit excellent electronic and ionic conductivities, thereby improving the rate capability and cycling stability. Furthermore, a soft package sodium-ion full battery assembled based on NFP@C reveals a high-capacity retention of 95.2% for 150 cycles at 0.5C. This carbon composite strategy is simple and efficient and could be easily and widely extended to other cathodes in grid-scale energy storage applications.     

Synthesis and characterization of MnCo2O4 microspheres based air electrode for rechargeable sodium-air batteries

In this work, the nanosized porous MnCo₂O₄ microspheres were synthesized by a hydrothermal method and their electrochemical behaviors were investigated based on a carbon supported composite air electrode for rechargeable sodium-air batteries. Under dry air test condition, the MnCo₂O₄/C air electrode demonstrated a stable working voltage of around 2.1 V vs. Na⁺/Na and a high initial discharge capacity of 7709.4 mA h g⁻¹, based on the active material mass, at a current density of 0.1 mA cm⁻². By a limit on the depth of discharge, the cell exhibited a specific capacity of 1000 mA h g⁻¹ with a high cycling stability up to 130 cycles. The considerable electrocatalytic activity suggests that the as-proposed MnCo₂O₄ is a highly efficient catalyst as air electrode for rechargeable sodium-air batteries.     

Direct regeneration of LiNi0.5Co0.2Mn0.3O2 cathode material from spent lithium-ion batteries

At present, metal ions from spent lithium-ion batteries are mostly recovered by the acid leaching procedure, which unavoidably introduces potential pollutants to the environment. Therefore, it is necessary to develop more direct and effective green recycling methods. In this research, a method for the direct regeneration of anode materials is reported, which includes the particles size reduction of recovered raw materials by jet milling and ball milling, followed by calcination at high temperature after lithium supplementation. The regenerated LiNi_0.5Co_0.2Mn_0.3O₂ single-crystal cathode material possessed a relatively ideal layered structure and a complete surface morphology when the lithium content was n(Ni + Co + Mn):n(Li) = 1:1.10 at a sintering temperature of 920 ℃, and a sintering time of 12 h. The first discharge specific capacity was 154.87 mA·h·g^-1 between 2.75 V and 4.2 V, with a capacity retention rate of 90% after 100 cycles.     

Performance of LiNi1/3Co1/3Mn1/3O2 prepared from spent lithium-ion batteries by a carbonate co-precipitation method

Spherical LiNi_1/3Co_1/3Mn_1/3O₂ cathode particles were resynthesized by a carbonate co-precipitation method using spent lithium-ion batteries (LIBs) as a raw material. The physical characteristics of the Ni_1/3Co_1/3Mn_1/3CO₃ precursor, the (Ni_1/3Co_1/3Mn_1/3)₃O₄ intermediate, and the regenerated LiNi_1/3Co_1/3Mn_1/3O₂ cathode material were investigated by laser particle-size analysis, scanning electron microscopy–energy-dispersive spectroscopy (SEM-EDS), thermogravimetry–differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), inductively coupled plasma–atomic emission spectroscopy (ICP-AES), and X-ray photoelectron spectroscopy (XPS). The electrochemical performance of the regenerated LiNi_1/3Co_1/3Mn_1/3O₂ was studied by continuous charge–discharge cycling and cyclic voltammetry. The results indicate that the regenerated Ni_1/3Co_1/3Mn_1/3CO₃ precursor comprises uniform spherical particles with a narrow particle-size distribution. The regenerated LiNi_1/3Co_1/3Mn_1/3O₂ comprises spherical particles similar to those of the Ni_1/3Co_1/3Mn_1/3CO₃ precursor, but with a narrower particle-size distribution. Moreover, it has a well-ordered layered structure and a low degree of cation mixing. The regenerated LiNi_1/3Co_1/3Mn_1/3O₂ shows an initial discharge capacity of 163.5 mA h g^?1 at 0.1 C, between 2.7 and 4.3 V; the discharge capacity at 1 C is 135.1 mA h g^?1, and the capacity retention ratio is 94.1% after 50 cycles. Even at the high rate of 5 C, LiNi_1/3Co_1/3Mn_1/3O₂ delivers the high capacity of 112.6 mA h g^?1. These results demonstrate that the electrochemical performance of the regenerated LiNi_1/3Co_1/3Mn_1/3O₂ is comparable to that of a cathode synthesized from fresh materials by carbonate co-precipitation.     

Catalytic performance improvement of volatile organic compounds oxidation over MnOx and GdMnO3 composite oxides from spent lithium-ion batteries:Effect of acid treatment

In this work,cathode materials of spent lithium-ion ternary batteries are recovered and used as metal precursor to prepare multi-metal oxides MnOx(SY)and GdMnO3(SY)via combustion method and sol-gel method,respec-tively.Furthermore,a series of MnOx(SY)-n and GdMnO3(SY)-n(n=0.05,0.10,1.00,4.00,n represents the dilute HNO3 concentration)catalysts are fabricated by acid treatment of MnOx(SY)and GdMnO3(SY)samples and cat-alytic activities of oxygenated VOCs oxidation over all the prepared catalysts are investigated.Catalytic evaluation results show that acid-treated MnOx(SY)-0.10 and GdMnO3(SY)-0.05 samples perform the optimum VOCs re-moval efficiency respectively,which may be attributed to their obvious enhancement of physicochemical prop-erties.In detail,MnOx(SY)-0.10 and GdMnO3(SY)-0.05 samples exhibit the larger specific surface area,bigger amount of surface high-valence metal ions(Mn4+,Co3+,Ni3+),more abundant adsorbed oxygen species and better low-temperature reducibility,which can play a crucial role in the significant improvement of VOCs oxida-tion.In situ DRIFTS results imply that the possible main intermediates are-OCO,-COO and-C-O species produced during VOCs oxidation.Possible by-products are further determined via TD/GC-MS analysis.     

Structural,magnetic and magnetostrictive properties of Co1-xLixFe2O4 synthesized by cathode materials of spent Li-ion batteries

In this study, we investigated the effects of substituting Li⁺ for Co²⁺ at the B sites of the spinel lattice on the structural, magnetic and magnetostrictive properties of cobalt ferrites. The Li⁺ substituted cobalt ferrites, Co_1-xLi_xFe₂O₄, with x varying from 0 to 0.7 in 0.1 increments, were synthesized with a sol-gel auto-combustion method using the cathode materials of spent Li-ion batteries. X-ray diffraction analysis revealed that all the Co_1-xLi_xFe₂O₄ nanopowders had a single-phase spinel structure and the lattice parameters decreased with increasing Li⁺ content, which can be proved by slight shifts towards higher diffraction angle values of the (311) peak. Field emission scanning electron microscopy was used to observe the fractured inner surface of the sintered cylindrical rods and the increased porosity resulted in a decreased magnetostriction. The oxidation states of Co and Fe in the cobalt ferrite samples were examined by X-ray photoelectron spectroscopy. High resolution transmission electron microscopy micrographs showed that most particles were roughly spherical and with sizes of 25–35?nm. Li⁺ substitution had a strong effect on the saturation magnetization and coercivity, which were characterized with a vibrating sample magnetometer. The Curie temperature was reduced due to the decrease in magnetic cations and the weakening of the exchange interactions. The magnetostrictive properties were influenced by the incorporation of Li⁺ at the B sites of the spinel structure and correlated with the changes in porosity, magnetocrystalline anisotropy and the cation distribution.     

Electrochemical recycling of cobalt from spent cathodes of lithium-ion batteries: its application as supercapacitor

The supercapacitive behavior of the metallic cobalt recycled from Li-ion batteries has been studied in this work. The reversibility of both redox process (Co^II/Co^III) and (Co^III/Co^IV) in KOH 6 mol L⁻¹ is very high and promising for capacitive applications in electrochemical devices. The specific capacitances calculated from cyclic voltammetry and electrochemical impedance spectroscopy show a good agreement, giving the value of 625 Fg⁻¹. The electrode morphology presents a high porosity, thus an electrical equivalent circuit composed of two parallel resistance and capacitance elements in series was proposed. The specific capacitance values calculated from charge/discharge curves at 0.23 and 2.3 mA/cm² are 601 and 384 Fg⁻¹, respectively. Thereby, it was observed that metallic cobalt recycled from ion-Li batteries is compatible with other supercapacitive materials. This shows that cobalt recycling from Li-ion batteries is economically and environmentally viable for application in supercapacitor devices.     

Enhanced electrochemical performance of core-shell Li4Ti5O12/PTh as advanced anode for rechargeable lithium-ion batteries

A nanocomposite of Li₄Ti₅O₁₂ particles coated with polythiophene (PTh) was fabricated as advanced anode for rechargeable lithium-ion batteries. The conducting PTh layer was successfully coated on the surface of Li₄Ti₅O₁₂ through the in-situ oxidative polymerization method. Benefiting from the core-shell structure, specific capacities as high as 171.5, 168.2 and 151.1 mA h g⁻¹ at 0.2, 1 and 10 C are obtained in the Li₄Ti₅O₁₂/PTh composite. The electrochemical results also show that the Li₄Ti₅O₁₂/PTh exhibits remarkably improved cycling performance as compared with the Li₄Ti₅O₁₂ anode. Moreover, the charge-transfer resistance of Li₄Ti₅O₁₂/PTh electrode is much lower than that of the bare Li₄Ti₅O₁₂, revealing that the PTh coating can significantly increase the electron conductivity between the Li₄Ti₅O₁₂ particles. The excellent electrochemical performance of the as-fabricated Li₄Ti₅O₁₂/PTh composite can be ascribed to the PTh layer which can suppress the dissolution of active material into the LiPF₆ electrolyte and enhance the electron conductivity of Li₄Ti₅O₁₂ nanocrystals. Thus, the Li₄Ti₅O₁₂/PTh composite is an advanced anode for use in high performance lithium-ion batteries application.     

退役锂离子电池电化学还原浸出及热力学研究

近年来锂离子电池的需求量快速增长,产生了大量退役锂离子电池（LIBs）。回收退役LIBs对保障中国的清洁能源安全具有重要意义。电化学浸出退役LIBs正极材料是一种绿色经济的回收方法。目前,电化学法回收退役LIBs存在浸出时间长、电流效率低、槽压高的问题。基于此,提出了一种牺牲阳极的电化学还原回收退役LIBs的方法。该方法以退役LIBs正极材料为阴极,以铜板为阳极,在盐酸体系下进行电化学浸出。在最佳条件下锂离子和钴离子的浸出率均达到99.9%、电流效率高达99.8%、槽压小于0.427 V。使用基于Eh-pH和Matlab的热力学计算方法,对电化学还原浸出体系进行了热力学研究。研究结果表明,温度升高,配合物种类增多、配位物种占比增大,有助于浸出反应平衡正向移动。