Hydrothermal leaching of ternary and binary lithium-ion battery cathode materials with citric acid and the kinetic study

Enhanced reducing capacity of citric acid for lithium-ion battery recycling under microwave-assisted leaching

The management and sustainable recycling of spent lithium-ion batteries (LIBs) holds critical importance from both economic and environmental standpoints. H2O2 and ascorbic acid are widely used inorganic and organic reductants in the hydrometallurgical process for battery recycling. In this study, citric acid, as a reductant, was found to have superior metal leaching efficiencies under microwave-assisted leaching than H2O2 and ascorbic acid. The enhanced performance was attributed not only to the inherent reducing property of citric acid but also to the chelation of citric acid with Cu and Fe, resulting in the formation of reductive radicals under microwave. The effect of acid type, H2SO4 concentration, citric acid concentration, solid-liquid (S/L) ratio, reaction time, and temperature were investigated. 99.5 % of Li, 99.7 % of Mn, 99.5 % of Co, and 99.3 % of Ni were leached from spent lithium nickel manganese cobalt oxides (NCM) battery black mass using 0.2 mol/L H2SO4 and 0.05 mol/L citric acid at 120 °C for 20 min with a fixed S/L ratio of 10 g/L in the microwave-assisted leaching process. Leaching kinetic results were best fitted with the Avrami model, suggesting that the microwave-assisted leaching process was controlled by diffusion. The leaching activation energies of Li, Mn, Co, and Ni were 30.11 kJ/mol, 27.48 kJ/mol, 21.32 kJ/mol, and 33.29 kJ/mol, respectively, providing additional evidence that supports the proposed diffusion-controlled microwave-assisted leaching mechanism. This method provided a green and efficient solution for spent LIBs recycling.

Improvement of Li and Mn bioleaching from spent lithium-ion batteries, using step-wise addition of biogenic sulfuric acid by Acidithiobacillus thiooxidans

Conventional spent lithium-ion battery (LIB) recycling procedures, which employ powerful acids and reducing agents, pose environmental risks. This work describes a unique and environmentally acceptable bioleaching method for Li and Mn recovery utilizing Acidithiobacillus thiooxidans, a sulfur-oxidizing bacteria that may produce sulfuric acid biologically. The novel feature of this strategy is the step-by-step addition of biogenic sulfuric acid, which differs significantly from conventional methods that use chemical reagents. We expected that gradually introducing biogenic sulfuric acid produced by A. thiooxidans would improve metal leaching at high pulp density. To investigate this, LIBs were disassembled and bioleached with or without a step-wise addition of the biogenic sulfuric acid approach. The impact on leaching efficiency, time, and ultimate product quality was assessed. Direct bioleaching yielded modest Li (43 %) and Mn (15 %) recoveries. However, bioleaching greatly increased metal recovery with the step-wise addition of biogenic acid. Li and Mn leaching efficiency were 93 % and 53 %, respectively, at a high pulp density of 60 g/L, while leaching time was reduced from 16 to 8 days. Following bioleaching, Mn(OH)2 and Li2CO3 were successfully precipitated from the leachate at more than 90 % purity. This study shows that gradually adding biogenic sulfuric acid can efficiently recover Li and Mn from waste LIBs. This approach has several environmental and economic advantages over conventional methods. The step-wise addition optimizes the leaching environment, increasing metal recovery rates while reducing the development of hazardous byproducts. This approach is environmentally friendly because it decreases greenhouse gas emissions and chemical waste. Economically, this technology offers potential cost savings through less chemical usage, shorter processing times, and lower energy needs, making it a more sustainable and cost-effective option for LIB recycling. This study shows that the step-wise addition of biogenic sulfuric acid may efficiently recover Li and Mn from wasted LIBs. This method provides a sustainable alternative to traditional procedures by limiting environmental impact while reducing process time and energy consumption.

Mixed crushing and competitive leaching of all electrode material components and metal collector fluid in the spent lithium battery

Hydrometallurgy is a primary method for recovering cathode electrode materials from spent lithium-ion batteries (LIBs). Most of the current research materials are pure cathode electrode materials obtained through manual disassembly. However, the spent LIBs are typically broken as a whole during the actual industrial recycling which makes the electrode materials combined with the collector fluid. Therefore, the competitive leaching between metal collector fluid and electrode material was examined. The pyrolysis characteristics of the electrode materials were analyzed to determine the pyrolysis temperature. The electrode sheet was pyrolyzed and then crushed for competitive leaching. The effect of pyrolysis was analyzed by XPS. The competitive leaching behavior was studied based on leaching agent concentration, leaching time and leaching temperature. The composition and morphology of the residue were determined to prove the competitive leaching results by XRD-SEM. TG results showed that 500 °C was the suitable pyrolysis temperature. XPS analysis demonstrated that pyrolysis can completely remove PVDF. Li and Co were preferentially leached during the competitive leaching while the leaching rates were 90.10% and 93.40% with 50 min leaching at 70 °C. The Al and Cu had weak competitive leachability and the leaching rate was 29.10% and 0.00%. XRD-SEM analysis showed that Li and Co can be fully leached with residual Al and Cu remaining. The results showed that the mixed leaching of electrode materials is feasible based on its excellent selective leaching properties.

Electrolyte Design for Low-Temperature Li-Metal Batteries: Challenges and Prospects

Electrolyte design holds the greatest opportunity for the development of batteries that are capable of sub-zero temperature operation. To get the most energy storage out of the battery at low temperatures, improvements in electrolyte chemistry need to be coupled with optimized electrode materials and tailored electrolyte/electrode interphases. Herein, this review critically outlines electrolytes' limiting factors, including reduced ionic conductivity, large de-solvation energy, sluggish charge transfer, and slow Li-ion transportation across the electrolyte/electrode interphases, which affect the low-temperature performance of Li-metal batteries. Detailed theoretical derivations that explain the explicit influence of temperature on battery performance are presented to deepen understanding. Emerging improvement strategies from the aspects of electrolyte design and electrolyte/electrode interphase engineering are summarized and rigorously compared. Perspectives on future research are proposed to guide the ongoing exploration for better low-temperature Li-metal batteries.

Progress on Separation and Hydrothermal Carbonization of Rice Husk Toward Environmental Applications

Owing to the increasing global demand for carbon resources, pressure on finite materials, including petroleum and inorganic resources, is expected to increase in the future. Efficient utilization of waste resources has become crucial for sustainable resource acquisition for creating the next generation of industries. Rice husks, which are abundant worldwide as agricultural waste, are a rich carbon source with a high silica content and have the potential to be an effective raw material for energy-related and environmental purification materials such as battery, catalyst, and adsorbent. Converting these into valuable resources often requires separation and carbonization; however, these processes incur significant energy losses, which may offset the benefits of using biomass resources in the process steps. This review summarizes and discusses the high value of RHs, which are abundant as agricultural waste. Technologies for separating and converting RHs into valuable resources by hydrothermal carbonization are summarized based on the energy efficiency of the process.

Leaching NCM cathode materials of spent lithium-ion batteries with phosphate acid-based deep eutectic solvent

Deep eutectic solvents (DESs) play an important role in efficient recovery of spent lithium-ion batteries (LIBs). In this study, we proposed an efficient and safe method by using a choline chloride-phenylphosphinic acid DES as a lixiviant for the leaching of LiNi_xCo_yMn_zO₂ (NCM) cathode active materials of spent LIBs. The leaching conditions were optimized based on the leaching time, liquid-solid ratio, and leaching temperature. Under optimal experimental conditions, the leaching efficiencies of Li, Co, Ni, and Mn reached 97.7 %, 97.0 %, 96.4 %, and 93.0 %, respectively. The kinetics of the leaching process were well-fitted using the logarithmic law equation. The apparent activation energies for Li, Co, Ni, and Mn have been reported to be 60.3 kJ/mol, 78.9 kJ/mol, 99.3 kJ/mol, and 82.1 kJ/mol, respectively. UV-visible spectroscopy and Fourier transform infrared analysis revealed that the coordination configurations of Ni and Co in the leaching solution were octahedral and tetrahedral, respectively. In addition, the PO bond in phenylphosphinic acid was involved in coordination during leaching. This finding may provide an effective and safe approach for leaching valuable metals from spent LIBs.

An Investigation upon Industry 4.0 and Society 5.0 within the Context of Sustainable Development Goals

In the literature, quite limited research exists on the subject of Society 5.0. The present study examined the existence of Society 5.0 and the effectiveness of Industry 4.0 and evaluated the efficiency of United Nations Development Goals (SDGs) in this process, especially in Turkey. The research was carried out based on data obtained through a survey form with 30 questions which was conducted with 335 academicians working at Kafkas University. The data were analyzed by means of exploratory factor analysis with the SPSS program, confirmatory factor analysis with AMOS, and structural equation modeling with Smart PLS. The analysis results indicated that SDG9, SDG10, SDG11, SDG12, SDG13, and SDG14 had a low influence (i.e., R2: 0.172) on the application of Industry 4.0 and Society 5.0. Moreover, it was observed that the participants were heavily affected by order of the day and gave responses to the questions with that impact. The study also revealed that Turkey did not have a leading philosophy in the field of Society 5.0 and Industry 4.0 and made progress by concentrating on out-dated processes.