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

Activating Carbon and Oxygen Bonds for Low-Temperature Thermal Decomposition of Spent Lithium-Ion Battery Cathode Materials

The temperature for complete disintegration of spent lithium-ion battery (LIB) cathode materials is typically in a range of 750-1400 °C, resulting in intensive energy consumption and high carbon emissions. Here, we promote the bond activation of oxygen in LiNi0.5Co0.2Mn0.3O2 and carbon in graphite electrodes, achieving rapid gasification and thermal decomposition of active crystals at lower temperatures in the absence of other activating agents. The activation of C and O bond leads to the storage of internal energy and the transition of the crystalline phase (single crystal to polycrystal) of the active crystals. Density functional theory modeling confirms that the CO adsorption energy is significantly higher with Ca-Oa (-3.35 eV, C and O activation) than with no activation (-1.66 eV). The differential charge results show that the bond activation model has the highest charge accumulation and consumption, improving the electron transfer. The Bader charge transfer between Ca-Oa and CO is also the largest, with a value of 0.433 |e|. Therefore, synchronous activation of C and O bonds can reduce the decomposition temperature of active crystals by 200 °C and allows a low-temperature pyrolysis recycling of retired LIB cathode materials. Our research provides a potential strategy for low-carbon recycling of retired LIBs worldwide.

An ultra-fast reaction process for recycling lithium ion batteries via galvanic cell interaction

The efficient realization of a closed-loop process is an ultimate goal for reusing spent lithium-ion batteries (LIBs), yet the complicated recycling processes of leaching and purification in an acid atmosphere are totally different compared with the regeneration method of the cathode precursor in alkali solution, inevitably resulting in the redundant consumption of acid/ammonia solutions and increased burden for a green environment. Herein, considering the advantages of selective extraction and similar chemical surroundings for recovery and regeneration, ammonia-leaching has been proposed to achieve short-process closed-loop recycling with effective impurity removal. Particularly, benefiting from the galvanic cell interaction, the sluggish reaction rate and relatively harsh reaction conditions of ammonia-leaching are well addressed. High leaching efficiency can be achieved within 10 min, where nearly 80% valuable metals are extracted in the initial 1 min. Notably, this leaching solution, after purification, can be used to directly synthesize the cathode precursor through the commercial alkali co-precipitation method. This process is superior to the acid leaching system, which requires the use of acid-base solutions back and forth to adjust pH for metal extraction and material regeneration. Compared to the traditional solid-to-liquid reaction with a shrinking core model, the solid-to-solid reaction with galvanic cell interaction substantially addresses the inherent issue of sluggish leaching efficiency, exhibiting much stronger competitiveness in the leaching rate and environment cost. Thus, it provides prospects to achieve large-scale recycling and regeneration of spent LIBs simultaneously in the whole-process alkali-atmosphere.

Fundamentals of the recycling of spent lithium-ion batteries

This review discusses the critical role of fundamentals of battery recycling in addressing the challenges posed by the increasing number of spent lithium-ion batteries (LIBs) due to the widespread use of electric vehicles and portable electronics, by providing the theoretical basis and technical support for recycling spent LIBs, including battery classification, ultrasonic flaw detection, pretreatment (e.g., discharging, mechanical crushing, and physical separation), electrolyte recovery, direct regeneration, and theoretical calculations and simulations. Physical chemistry principles are essential for achieving effective separation of different components through methods like screening, magnetic separation, and flotation. Electrolyte recovery involves separation and purification of electrolytes through advanced physical and chemical techniques. Direct regeneration technology restores the structure of electrode materials at the microscopic scale, requiring precise control of the physical state and crystal structure of the material. Physical processes such as phase changes, solubility, and diffusion are fundamental to techniques like solid-state sintering, eutectic-salt treatment, and hydrothermal methods. Theoretical calculations and simulations help predict the behaviour of materials during recycling, guiding process optimization. This review provides insights into understanding and improving the recycling process, emphasizing the central role of physical chemistry principles in addressing environmental and energy issues. It is valuable for promoting innovation in spent LIB recycling processes and is expected to stimulate interest among researchers and manufacturers.

Potential-Regulated Design for Direct Recycling of Degraded LiFePO4 Cathode

The rapid proliferation of power sources equipped with lithium-ion batteries poses significant challenges in terms of post-scrap recycling and environmental impacts, necessitating urgent attention to the development of sustainable solutions. The cathode direct regeneration technologies present an optimal solution for the disposal of degraded cathodes, aiming to non-destructively re-lithiate and straightforwardly reuse degraded cathode materials with reasonable profits and excellent efficiency. Herein, a potential-regulated strategy is proposed for the direct recycling of degraded LiFePO4 cathodes, utilizing low-cost Na2SO3 as a reductant with lower redox potential in the alkaline systems. The aqueous re-lithiation approach, as a viable alternative, not only enables the re-lithiation of degraded cathode while ignoring variation in Li loss among different feedstocks but also utilizes the rapid sintering process to restore the cathode microstructure with desirable stoichiometry and crystallinity. The regenerated LiFePO4 exhibits enhanced electrochemical performance with a capacity of 144 mA h g-1 at 1 C and a high retention of 98% after 500 cycles at 5 C. Furthermore, this present work offers considerable prospects for the industrial implementation of directly recycled materials from lithium-ion batteries, resulting in improved economic benefits compared to conventional leaching methods.

Recycling scale inhibitor wastes into pH-responsive complexes to treat wastewater produced from spent lithium-ion battery disposal

A large amount of organophosphorus-containing wastewater is produced in spent lithium-ion battery disposal. Forward osmosis (FO) offers unique advantages in purifying this kind of wastewater if suitable draw solutes - the core of FO technology, are available. Herein we synthesize several pH-sensitive zinc complexes, namely ZnATMP-iNa (i = 0, 1, 2, 3, 4), from ZnSO4 and amino tris(methylene phosphonic acid) (ATMP) obtained from scale inhibitor wastes for organophosphorus-containing wastewater remediation. Among these ZnATMP-iNa, ZnATMP-3Na best meets the standards of an ideal draw solute. This makes ZnATMP-3Na outperform other reported draw solutes. 0.6 M ZnATMP-3Na produces a water flux of 12.7 LMH, 136 % higher than that of NaCl and a solute loss of 0.015 g/L, lower than that of NH4HCO3 (0.83 g/L). In organophosphorus-containing wastewater treatment, ZnATMP-3Na has higher water recovery efficiency (8.3 LMH) and sustainability than NaCl and NH4HCO3, and is sufficient to handle large quantities of wastewater. Remarkably, the pH-responsive property allows ZnATMP-3Na to be readily recovered through pH-control and reused in FO. The ionic property, expanded cage-like structure and easy-recycling make ZnATMP-3Na achieve sustainable FO separation and superior to other draw solutes. This study provides inspiration for draw solute design from wastes and extends FO application to organophosphorus-containing wastewater remediation.

Regenerated Ni-Doped LiCoO2 from Spent Lithium-Ion Batteries as a Stable Cathode at 4.5 V

In the context of the increasing number of spent lithium-ion batteries, it is urgent to explore cathode regeneration and upcycling solutions to reduce environmental pollution, promote resource reuse, and meet the demand for high-energy cathode materials. Here, a closed-loop recycling method is introduced, which not only reclaims cobalt and lithium elements from spent lithium-ion batteries but also converts them into high-voltage LiCoO2 (LCO) materials. This approach involved pretreatment, chlorination roasting, water leaching, and ion doping to regenerate nickel-doped LCO (Ni-RLCO) materials. The doping of nickel effectively enhances the electrochemical stability of the LCO cathode at 4.5 V. The Ni-RLCO cathode exhibited a high discharge specific capacity of 185.28 mAh/g at a rate of 0.5 C with a capacity retention of 86.3% after 50 cycles and excellent rate capacity of 156.21 mAh/g at 2 C. This work offers a approach in significance for upcycling spent LCO into high-energy-density batteries with long-term cycling stability under high voltage.

Coupling Ferricyanide/Ferrocyanide Redox Mediated Recycling Spent LiFePO4 with Hydrogen Production

Replacing the oxygen evolution reaction with thermodynamically more favorable alternative oxidation reactions offers a promising alternative to reduce the energy consumption of hydrogen production. However, questions remain regarding the economic viability of alternative oxidation reactions for industrial-scale hydrogen production. Here, we propose an innovative cost-effective, environment-friendly and energy-efficient strategy for simultaneous recycling of spent LiFePO4 (LFP) batteries and hydrogen production by coupling the spent LFP-assisted ferricyanide/ferrocyanide ([Fe(CN)6 ]4- /[Fe(CN)6 ]3- ) redox reaction. The onset potential for the electrooxidation of [Fe(CN)6 ]4- to [Fe(CN)6 ]3- is low at 0.87 V. Operando Raman and UV/Visible spectroscopy confirm that the presence of LFP in the electrolyte allows for the rapid reduction of [Fe(CN)6 ]3- to [Fe(CN)6 ]4- , thereby completing the [Fe(CN)6 ]4- /[Fe(CN)6 ]3- redox cycle as well as facilitating the conversion of spent LiFePO4 into LiOH ⋅ H2 O and FePO4 . The electrolyzer consumes 3.6 kWh of electricity per cubic meter of H2 produced at 300 mA cm-2 , which is 43 % less than conventional water electrolysis. Additionally, this recycling pathway for spent LFP batteries not only minimizes chemical consumption and prevents secondary pollution but also presents significant economic benefits.

Selective Recovery of Cathode Materials from Spent Lithium-Ion Battery Material with a Near-Room-Temperature Separation

Effective separation of cathode materials from the current collector is a critical step in recycling a spent lithium-ion battery (LIB). This typically necessitates the decomposition or dissolution of the organic binder, poly(vinylidene fluoride) (PVDF), to achieve efficient recovery of cathode materials. However, this process requires a high decomposition temperature, typically between 400 and 600 °C, and can lead to side reactions, such as current collector oxidation/brittleness, decomposition of cathode materials, and formation of metal fluorides. In this study, we propose that non-thermal plasma (NTP) treatment can be used to achieve an extremely high separation of cathode materials and aluminum current collector at near room temperature. Instead of relying on PVDF decomposition, which requires high temperatures, PVDF can be deactivated by partially breaking down long molecular chains with appropriate NTP conditions. With a total treatment time of around 2000 s and an environmental temperature of approximately 80 °C, minor side reactions can be avoided. The separation rate can reach up to 95.69%, and high-quality cathode materials can be obtained with only 0.02 wt % aluminum impurity content. This research could potentially offer a new approach toward minimizing recycling steps and reducing energy consumption in the recycling of spent LIBs. It could also be extended to the recovery of a broader range of electronic wastes.