As lithium-ion batteries (LIBs) become vital energy source for daily life and industry applications, a large volume of spent LIBs will be produced after their lifespan. Recycling of LIBs has been considered as an effective closed-loop solution to mitigate both environmental and economic issues associated with spent LIBs. While reclaiming of transition metal elements from LIB cathodes has been well established, recycling of graphite anodes has been overlooked. Here, we show an effect upcycling method involving both healing and doping to directly regenerate spent graphite anodes. Specifically, using boric acid pretreatment and short annealing, our regeneration process not only heals the composition/structure defects of degraded graphite but also creates functional boron-doping on the surface of graphite particles, providing high electrochemical activity and excellent cycling stability. The efficient direct regeneration of spent graphite by using low cost, non-volatile and non-caustic boric acid with low annealing temperature provides a more promising direction for green and sustainable recycling of spent LIB anodes.
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Abstract A low‐carbon future demands more affordable batteries utilizing abundant elements with sustainable end‐of‐life battery management. Despite the economic and environmental advantages of Li‐MnO2batteries, their application so far has been largely constrained to primary batteries. Here, we demonstrate that one of the major limiting factors preventing the stable cycling of Li‐MnO2batteries, Mn dissolution, can be effectively mitigated by employing a common ether electrolyte, 1 mol/L lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in 1,3‐dioxane (DOL)/1,2‐dimethoxyethane (DME). We discover that the suppression of this dissolution enables highly reversible cycling of the MnO2cathode regardless of the synthesized phase and morphology. Moreover, we find that both the LiPF6salt and carbonate solvents present in conventional electrolytes are responsible for previous cycling challenges. The ether electrolyte, paired with MnO2cathodes is able to demonstrate stable cycling performance at various rates, even at elevated temperature such as 60°C. Our discovery not only represents a defining step in Li‐MnO2batteries with extended life but provides design criteria of electrolytes for vast manganese‐based cathodes in rechargeable batteries.
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Abstract As the dominant means of energy storage technology today, the widespread deployment of lithium‐ion batteries (LIBs) would inevitably generate countless spent batteries at their end of life. From the perspectives of environmental protection and resource sustainability, recycling is a necessary strategy to manage end‐of‐life LIBs. Compared with traditional hydrometallurgical and pyrometallurgical recycling methods, the emerging direct recycling technology, rejuvenating spent electrode materials via a non‐destructive way, has attracted rising attention due to its energy efficient processes along with increased economic return and reduced CO2footprint. This review investigates the state‐of‐the‐art direct recycling technologies based on effective relithiation through solid‐state, aqueous, eutectic solution and ionic liquid mediums and thoroughly discusses the underlying regeneration mechanism of each method regarding different battery chemistries. It is concluded that direct regeneration can be a more energy‐efficient, cost‐effective, and sustainable way to recycle spent LIBs compared with traditional approaches. Additionally, it is also identified that the direct recycling technology is still in its infancy with several fundamental and technological hurdles such as efficient separation, binder removal and electrolyte recovery. In addressing these remaining challenges, this review proposes an outlook on potential technical avenues to accelerate the development of direct recycling toward industrial applications.
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One major bottleneck of today's industrial hydrometallurgical lithium‐ion battery recycling processes is the limited operation efficiency, particularly for leaching Co, Li, and Ni elements. Boosting the leaching rate and solid to liquid (S/L) ratio can increase the productivity and yield of recycled materials, which can save chemicals and energy cost. Herein, the use of ethylene glycol (EG), a green and sustainable reducing agent, for the separation of spent cathode materials resulting in high leaching efficiencies for very high loadings is demonstrated. The dramatically improved leaching efficiency is attributed to the EG reducing moieties that enable better cathode reduction and dissolution. The separation process avoids the use of toxic organic solvents, making the overall leaching process greener. The leaching efficiency is shown to remain high despite the use of high loadings as compared to the state‐of‐the‐art works. The cathode separation process is then modified to allow for a facile separation of a cathode and anode mixture. This mixture is demonstrated to attain high leaching efficiencies at comparable loadings for cathode‐only process. This redox leaching‐based recovery process holds a potential for industry adoption due to the elimination of energy‐intensive pretreatment step and the high efficiencies obtained.
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Abstract Conventional templating synthesis confines the growth of seeds in rigid spaces to achieve faithful morphological replication. Herein, we explore the use of spherical shape‐deformable polymeric nanoshells to regulate the anisotropic growth of Ag nanoplates. The flexible shells deform adaptively to accommodate the initial overgrowth of the seeds but restrict the growth in the directions where the shells are fully stretched, eventually producing nanoplates with an unconventional circular profile. The diameter of the final Ag nanoplates can be precisely predicted by stretching and flattering the nanoshells into a plate‐like capsule while retaining their original internal surface area. Furthermore, unlike conventional templates, the polymer shells eventually turn themselves into a conformal coating that binds to the surface of the full‐grown Ag nanoplates and significantly enhances their stability against oxidative etching.
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Abstract Conventional templating synthesis confines the growth of seeds in rigid spaces to achieve faithful morphological replication. Herein, we explore the use of spherical shape‐deformable polymeric nanoshells to regulate the anisotropic growth of Ag nanoplates. The flexible shells deform adaptively to accommodate the initial overgrowth of the seeds but restrict the growth in the directions where the shells are fully stretched, eventually producing nanoplates with an unconventional circular profile. The diameter of the final Ag nanoplates can be precisely predicted by stretching and flattering the nanoshells into a plate‐like capsule while retaining their original internal surface area. Furthermore, unlike conventional templates, the polymer shells eventually turn themselves into a conformal coating that binds to the surface of the full‐grown Ag nanoplates and significantly enhances their stability against oxidative etching.