In Situ Constructed Spinel Layer Stabilized Upcycled LiCoO2 for High Performance Lithium-Ion Batteries.

With ever-increasing requirements for cathodes in the lithium-ion batteries market, an efficiency and eco-friendly upcycling regeneration strategy is imperative to meet the demand for high-performance cathode materials. Herein, a facile, direct and upcycling regeneration strategy is proposed to restore the failed LiCoO2 and enhance the stability at 4.6 V. Double effects combination of relithiation and outside surface reconstruction are simultaneously achieved via a facile solid-phase sintering method. The evolution process of the Li-supplement and grain-recrystallization is systematically investigated, and the high performance of the upcycled materials at high voltage is comprehensively demonstrated. Thanks to the favorable spinel LiCoxMn2-xO4 surface coating, the upcycled sample displays outstanding electrochemical performance, superior to the pristine cathode materials. Notably, the 1% surface-coated LiCoO2 achieves a high discharge-specific capacity of 207.9 mA h g-1 at 0.1 C and delivers excellent cyclability with 77.0% capacity retention after 300 cycles. Significantly, this in situ created spinel coating layer can be potentially utilized for recycling spent LiCoO2, thus providing a viable, promising recycling strategy insights into the upcycling of degraded cathodes.

Acid-free mechanochemical process to enhance the selective recycling of spent LiFePO4 batteries.

With the large-scale application of LiFePO4 (LFP) in energy storage and electric vehicles, the recycling of spent lithium LFP batteries has gained more attention. However, recycling spent LFP is less economically feasible owing to the poor economic value of Fe products, which causes a problem for both the efficiency and economy. This work proposes a highly economical acid-free mechanochemical approach for the efficient and selective extraction of lithium (Li) from spent LFP battery cathode materials. The selective release of 98.9 % of Li from the LFP crystal structure is achieved at a reaction time of 5 h, a rotational speed of 500 rpm, and sodium citrate (Na3Cit) to LFP mass ratio of 10. Meanwhile, Fe is reserved in the form of FePO4 in the olivine structure. The use of Na3Cit as a co-milling agent ensures a pollution-free recovery process and efficient extraction of Li+. The chelation of Li+ with organic ligands (Cit3-) is the key to the efficient selective recovery of Li+ from the olivine LFP structure via the mechanochemical process. The economic analysis indicates that the method is feasible and ensures industrial viability. The acid-free mechanochemical (MC) process reported in this work provides a novel route to selectively recover Li from spent LFP efficiently and highly economically.

A New Insight into the Capacity Decay Mechanism of Ni-Rich Layered Oxide Cathode for Lithium-Ion Batteries.

Understanding the mapping relationship between electrochemical characteristics and physicochemical properties of layered LiNi0.80 Co0.15 Al0.05 O2 (NCA) cathodes is important to develop high energy density lithium-ion batteries (LIBs). Combining in situ and ex situ characterization, the effect of the H2-H3 phase transition on the capacity decay and aging mechanism of NCA materials are systematically investigated. With the increase of cut-off voltage, the cathode electrolyte interphase (CEI) on the NCA interface shows an evolutionary path of formation-thickening-rupture. This phenomenon is closely related to the H2-H3 phase transition. The volumetric stresses and strains caused by the H2-H3 phase transition accelerate the formation and expansion of secondary particle microcracks in the electrode material, leading to the growth of interfacial CEI variations. The capacity of the electrode material can decrease even if the material does not experience the H2-H3 phase transition due to the persistence of interfacial side reactions with calendar aging from long cycles. This work opens up a valuable perspective for the study of the mapping relationship between phase transition and electrochemical properties in Ni-rich layered oxide cathodes and provides guidance for developing high capacity and long cycle life LIBs.

Closed-loop selective recycling process of spent LiNixCoyMn1-x-yO2 batteries by thermal-driven conversion.

The consumption of lithium-ion batteries raises raw material demand for and the pressure on ecological sustainability. Metals can be recovered in shorter paths while considerably boosting material use, hence selective recycling of specific elements is becoming a hotspot. This paper proposes a thermally-driven closed-loop recycling process for scrap LiNi1/3Co1/3Mn1/3O2 cathodes, in which Li is efficiently extracted by water leaching. Then, by combining the leaching residue with Li2CO3, a solid-phase synthesis is carried out, with Li being targeted to heal into Ni-Co-Mn-O to construct the layered structure. The electrochemical performance of the resynthesized cathode material is comparable to that of the commercial LiNi0.5Co0.2Mn0.3O2 (NCM523) material. During the thermal-driven conversion, solid-state processes can be observed. To ensure charge conservation, Li+ in the unstable layered structure is released and mixed with SO42- to produce Li2SO4, and lattice oxygen escapes and transforms with Ni2+ to generate NiO. For the resynthesized process, the spherical shape of Ni-Co-Mn-O is largely retained. Notably, sulfur is remained in the form of SO42- throughout the closed-loop process and is therefore free of contamination. The thermal-driven conversion recycling process revealed in this study will encourage researchers to ensure more efforts in efficient and selective recovery for sustainable energy storage of rechargeable batteries.

Resolving the Structural Defects of Spent Li1- x CoO2 Particles to Directly Reconstruct High Voltage Performance Cathode for Lithium-Ion Batteries.

Effective and scalable recycling of spent lithium-ion batteries is an urgent need to address the environmental pollution and resource consumption caused by improper disposal. Herein, a practical solution is presented to recover and increase the stability of the layered structure from scrap Li1- x CoO2 via high-temperature supplementation of Li and Mg doping, without an extra synthesis step or cost. All the regenerated products exhibit better electrochemical performance compared with the commercial cathode material. Within the voltage window of 3.0-4.6 V, 5% Mg-recovery LiCoO2 (LMCO) exhibits a high discharge capacity of 202.9 mA h g-1 at 0.2 C, and 3% Mg-recovery LiCoO2 shows enhanced capacity retention of 99.5% at 0.2 C after 50 cycles and maintains 96.8% at 1 C after 100 cycles. This is because high-temperature supplementing metal ions is beneficial for eliminating the cracks and nano-impurity particles on the surface of spent materials, thereby restoring the layered structure and electrochemical performance. The excellent electrochemical performances of Mg-recovery LiCoO2 are attributed to Mg ions doping, which can inhibit the release of lattice oxygen and stabilize the surface structure. This process maximizes the utilization of the spent materials and provides a novel perspective for the non-constructive recovery of spent materials.

Hierarchical Triple-Shelled MnCo2 O4 Hollow Microspheres as High-Performance Anode Materials for Potassium-Ion Batteries.

Metal oxide anode materials generally possess high theoretical capacities. However, their further development in potassium-ion batteries (KIBs) is limited by self-aggregation and large volume fluctuations during charge/discharge processes. Herein, hierarchical MnCo2 O4 hollow microspheres (ts-MCO HSs) with three porous shells that consist of aggregated primary nanoparticles are fabricated as anode materials of KIBs. The porous shells are in favor of reducing the diffusion path of K-ions and electrons, and thus the rate performance can be enhanced. The unique triple-shelled hollow structure is believed to provide sufficient contact between electrolyte and metal oxides, possess additional active storage sites for K-ions, and buffer the volume change during K-ions insertion/extraction. A high specific capacity of 243 mA h g-1 at 100 mA g-1 in the 2nd cycle and a highly improved rate performance of 153 mA h g-1 at 1 A g-1 are delivered when cycled between 0.01 and 3.0 V. In addition, the transformation of substances during charging/discharging processes are intuitively demonstrated by the in situ X-ray diffraction strategy for the first time, which further proves that the unique structure of ts-MCO HSs with three porous shells can significantly enhance the potassium ions storage performance.

Glucose oxidase-based biocatalytic acid-leaching process for recovering valuable metals from spent lithium-ion batteries.

An environmentally benign leaching process for recovering valuable metals from the cathodes of spent lithium-ion batteries was developed. Glucose oxidase produced by Aspergillus niger can oxidize glucose to give the leaching agent gluconic acid. The presence of gluconic acid was proven by mass spectrometry. The cathode material morphology was characterized by X-ray diffractometry and scanning electron microscopy, and the efficiencies with which valuable metals were leached from the Li(NixCoyMnz)O2 material were determined by inductively coupled plasma optical emission spectroscopy. More than 95% of the Co, Li, Mn, and Ni were leached from spent lithium-ion batteries using a solid/liquid ratio of 30 g/L, 1 M gluconic acid leaching solution, a 1 vol% H2O2 reductant solution, a temperature of 70 °C, and a reaction time of 80 min. The leaching kinetics were perfectly described by the Avrami equation. The apparent activation energies for leaching of Li, Ni, Co, and Mn were determined as 41.76, 42.84, 43.59, and 45.35 kJ/mol, respectively, indicating that the surface chemical reaction is the rate-controlling step during this leaching process. This mild biocatalysis-aided acid leaching process is a promising method for effectively recovering valuable metals from spent lithium-ion batteries.

Conversion Mechanisms of Selective Extraction of Lithium from Spent Lithium-Ion Batteries by Sulfation Roasting.

With the undergoing unprecedented development of lithium-ion batteries (LIBs), the recycling of end-of-life batteries has become an urgent task considering the demand for critical materials, environmental pollution, and ecological impacts. Selective recovery of targeted element(s) is becoming a topical field that enables metal recycling in a short path with highly improved material efficiencies. This research demonstrates a process of selective recovery of spent Ni-Co-Mn (NCM)-based lithium-ion battery by systematically understanding the conversion mechanisms and controlling the sulfur behavior during a modified-sulfation roasting. As a result, Li from complex cathode components can be selectively extracted with high efficiency by only using water. Notably, the sulfur driven recovery processes can be divided into two stages: (i) part of the structure of NCM523 was destroyed, and Ni, Co, and Mn were reduced to divalent in different degrees to form sulfate (NiSO4, CoSO4, MnSO4) when reacting with H2SO4 at ambient temperature; (ii) with increasing temperature, Li ions in the unstable layered structure are released and combined with SO42- in the transition metal sulfate to form Li2SO4, and the sulfates of transition metals react to form Ni0.5Co0.2Mn0.3O1.4. Studies have shown sulfur can be recirculated thoroughly in the form of SO42-, which in principle avoids secondary pollutions. By controlling the appropriate conversion temperature, we envisage that the sulfation selective roasting recovery technology could be easily applied to other spent lithium-ion battery materials. Besides, this work may also provide a unique platform for further study on the efficient extracting of other mineral resources.

Sustainable Recycling Technology for Li-Ion Batteries and Beyond: Challenges and Future Prospects.

Tremendous efforts are being made to develop electrode materials, electrolytes, and separators for energy storage devices to meet the needs of emerging technologies such as electric vehicles, decarbonized electricity, and electrochemical energy storage. However, the sustainability concerns of lithium-ion batteries (LIBs) and next-generation rechargeable batteries have received little attention. Recycling plays an important role in the overall sustainability of future batteries and is affected by battery attributes including environmental hazards and the value of their constituent resources. Therefore, recycling should be considered when developing battery systems. Herein, we provide a systematic overview of rechargeable battery sustainability. With a particular focus on electric vehicles, we analyze the market competitiveness of batteries in terms of economy, environment, and policy. Considering the large volumes of batteries soon to be retired, we comprehensively evaluate battery utilization and recycling from the perspectives of economic feasibility, environmental impact, technology, and safety. Battery sustainability is discussed with respect to life-cycle assessment and analyzed from the perspectives of strategic resources and economic demand. Finally, we propose a 4H strategy for battery recycling with the aims of high efficiency, high economic return, high environmental benefit, and high safety. New challenges and future prospects for battery sustainability are also highlighted.

A green and effective room-temperature recycling process of LiFePO4 cathode materials for lithium-ion batteries.

Nowadays LiFePO4 cathode develops rapidly for its advantages of long life span, low cost and non-toxicity, especially in electrical vehicle markets. Because of its stable olivine structure, LiFePO4 is difficult to be recycled by the conventional hydrometallurgical processes as for LiCoO2 or LiNixCoyMnzO2. Pyrometallurgical processes consume much energy and release toxic gases. Herein, an effective room-temperature process based on the mechanochemical treatment is proposed to extract metals from LiFePO4. Spent LiFePO4 is co-grinded with low-cost citric acid agent in a ball mill. After grinding, the mixture is dissolved in deionized water and filtrated. With addition of H2O2, the extraction efficiency of Li reaches as high as 99.35%. Conversely, Fe is hardly extracted with a low extraction efficiency of only 3.86%, indicating a selective recovery of valuable Li element. In addition, when H2O is used instead of H2O2, the mechanochemical reaction changes and the extraction efficiencies of Li and Fe at optimal conditions reach 97.82% and 95.62%, respectively. The Fe impurity is removed as Fe(OH)3 precipitation by adding NaOH, and Li is recycled as Li2CO3 after reaction with saturated Na2CO3 at 95 °C. This simple and easily-operated process has little negative impact on the environment and has great potential in industrial applications.

Toward sustainable and systematic recycling of spent rechargeable batteries.

Ever-growing global energy needs and environmental damage have motivated the pursuit of sustainable energy sources and storage technologies. As attractive energy storage technologies to integrate renewable resources and electric transportation, rechargeable batteries, including lead-acid, nickel-metal hydride, nickel-cadmium, and lithium-ion batteries, are undergoing unprecedented rapid development. However, the intrinsic toxicity of rechargeable batteries arising from their use of toxic materials is potentially environmentally hazardous. Additionally, the massive production of batteries consumes numerous resources, some of which are scarce. It is therefore essential to consider battery recycling when developing battery systems. Here, we provide a systematic overview of rechargeable battery recycling from a sustainable perspective. We present state-of-the-art fundamental research and industrial technologies related to battery recycling, with a special focus on lithium-ion battery recycling. We introduce the concept of sustainability through a discussion of the life-cycle assessment of battery recycling. Considering the forecasted trend of a massive number of retired power batteries from the forecasted surge in electric vehicles, their repurposing and reuse are considered from economic, technical, environmental, and market perspectives. New opportunities, challenges, and future prospects for battery recycling are then summarized. A reinterpreted 3R strategy entailing redesign, reuse, and recycling is recommended for the future development of battery recycling.

Process for recycling mixed-cathode materials from spent lithium-ion batteries and kinetics of leaching.

A "grave-to-cradle" process for the recycling of spent mixed-cathode materials (LiCoO2, LiCo1/3Ni1/3Mn1/3O2, and LiMn2O4) has been proposed. The process comprises an acid leaching followed by the resynthesis of a cathode material from the resulting leachate. Spent cathode materials were leached in citric acid (C6H8O7) and hydrogen peroxide (H2O2). Optimal leaching conditions were obtained at a leaching temperature of 90 °C, a H2O2 concentration of 1.5 vol%, a leaching time of 60 min, a pulp density of 20 g L-1, and a citric acid concentration of 0.5 M. The leaching efficiencies of Li, Co, Ni, and Mn exceeded 95%. The leachate was used to resynthesize new LiCo1/3Ni1/3Mn1/3O2 material by using a sol-gel method. A comparison of the electrochemical properties of the resynthesized material (NCM-spent) with that synthesized directly from original chemicals (NCM-syn) indicated that the initial discharge capacity of NCM-spent at 0.2 C was 152.8 mA h g-1, which was higher than the 149.8 mA h g-1 of NCM-syn. After 160 cycles, the discharge capacities of the NCM-spent and NCM-syn were 140.7 mA h g-1 and 121.2 mA h g-1, respectively. After discharge at 1 C for 300 cycles, the NCM-spent material remained a higher capacity of 113.2 mA h g-1 than the NCM-syn (78.4 mA h g-1). The better performance of the NCM-spent resulted from trace Al doping. A new formulation based on the shrinking-core model was proposed to explain the kinetics of the leaching process. The activation energies of the Li, Co, Ni, and Mn leaching were calculated to be 66.86, 86.57, 49.46, and 45.23 kJ mol-1, respectively, which indicates that the leaching was a chemical reaction-controlled process.