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[Display omitted] • A low-cost, green, selective electrolysis process for Li recovery from spent LiFePO 4. • High performance LiFePO 4 was synthesised by impurity removal regeneration process. • The electrolysis and regeneration process makes full use of spent LiFePO 4. In this paper, a green, efficient and low-cost process for the selective recovery of lithium from spent LiFePO 4 by anodic electrolysis is proposed. The leaching rates of Li, Fe and P under different conditions were explored and the optimal conditions are obtained. In the optimal conditions, Li, Fe and P leaching rates were 96.31%, 0.06% and 0.62% respectively. The Li/Fe selectivity was over 99.9%. The product obtained is isostructural FePO 4 and retains the original particle morphology. The FePO 4 obtained can be synthesised into LiFePO 4 /C by direct regeneration process or impurity removal regeneration process. The material synthesized by the latter process has a better electrochemical performance, with a discharge specific capacity of 144.5 mAh/g at 1.0C and a capacity retention of 92.0% over 500cycles. The superior performance can be attributed to an impurity removal process that reduced agglomeration and improved particle morphology. [ABSTRACT FROM AUTHOR]

Sulfur cathode materials in lithium–sulfur chemistry suffer from poor electronic conductivity and shuttle of lithium polysulfides during charging and discharging. Serious shuttle effects and the sluggish redox reaction kinetics of polysulfides severely limit the development of lithium–sulfur batteries with high sulfur loading, impeding the practical process of lithium–sulfur batteries. Herein, a honeycomb73x02010;structured CoF2@C is introduced as a functional layer adhered to the separator, achieving rapid lithium‐ion transport, high catalytic activity, and suppressed shuttle effect simultaneously. As a result, the cell with CoF2‐modified separator presents satisfactory cycle stability with a capacity decay of 0.076% per cycle within 300 cycles at 1 C rate with the sulfur loading of 2.0 mg cm−2. A low‐capacity decay of 0.088% per cycle for 200 cycles at 0.2 C is also achieved with sulfur loading of 3.0 mg cm−2. In addition, a high‐capacity retention of 697.5 mA g−1 is achieved with sulfur loading of 4.0 mg cm−2 and the electrolyte volume/sulfur mass (E/S) ratio of 8 μL mg−1. [ABSTRACT FROM AUTHOR]

Concentration of electrolyte has significant effects on performances of rechargeable batteries. Previous studies mainly focused on concentrated electrolytes. So far, only several recipes on low‐concentration electrolytes were studied, performing enhanced performance in advanced rechargeable batteries. Here, based on common electrolyte components, a low‐concentration electrolyte composed of 0.2 M lithium hexafluorophosphate (LiPF6) solvated in fluoroethylene carbonate (FEC) and ethyl methyl carbonate (EMC) is employed for high‐voltage Li metal battery. The synergistic working mechanisms of introducing fluorine‐containing solvent in the solvated structure and low salt concentration effect are revealed, resulting in LiF‐rich, uniform, and robust solid electrolyte interphase layer and fewer unfavorable decomposition products. As a result, this low‐concentration electrolyte significantly enhances electrochemical performances of Li||Li symmetric cells and high‐voltage LiCoO2||Li batteries. [ABSTRACT FROM AUTHOR]

Concentration of electrolyte has significant effects on performances of rechargeable batteries. Previous studies mainly focused on concentrated electrolytes. So far, only several recipes on low‐concentration electrolytes were studied, performing enhanced performance in advanced rechargeable batteries. Here, based on common electrolyte components, a low‐concentration electrolyte composed of 0.2 M lithium hexafluorophosphate (LiPF6) solvated in fluoroethylene carbonate (FEC) and ethyl methyl carbonate (EMC) is employed for high‐voltage Li metal battery. The synergistic working mechanisms of introducing fluorine‐containing solvent in the solvated structure and low salt concentration effect are revealed, resulting in LiF‐rich, uniform, and robust solid electrolyte interphase layer and fewer unfavorable decomposition products. As a result, this low‐concentration electrolyte significantly enhances electrochemical performances of Li||Li symmetric cells and high‐voltage LiCoO2||Li batteries. [ABSTRACT FROM AUTHOR]

• High Lithium Extraction Rate. • Success direct regeneration of de-lithiated product. • Mechanism about de-lithiation and regeneration processes. The recycling of spent lithium-ion batteries has become an urgent imperative. Electrochemical technology is emerging as an environmentally friendly approach for selectively extracting lithium from discarded cathode materials, garnering significant attention. However, the lack of a clear understanding of the structural evolution during the de-lithiation process, and the re-lithiation mechanism of transition-metal oxides after lithium extraction, hinder the direct regeneration of de-lithiated materials into battery-worthy materials. This limitation also impeds the further advancement of this promising technology. Here, for the first time the structural transformation associated with water-molecule intercalation during the electrochemical process of spent layer material (LiNi 0.55 Co 0.15 Mn 0.3 O 2) is demonstrated. X-ray diffraction technique monitors the structural evolution upon de-lithiation, revealing an unusual phase transformation from H3 to "H4" driven by water-molecule intercalation. This transformation triggers significant lattice expansion along c -axis and introduces notable lattice distortion in de-lithiated material. These characteristics render direct calcination for material regeneration impractical, due to lattice collapse from dehydration, obstructing lithium intercalation at high temperatures. Interestingly, low-temperature calcination can endow resynthesized materials with a well-ordered layer structure after creating a lithium-water-balance layer structure for de-lithiated materials by hydrothermal process. Consequently, the regenerated material delivers a capacity of 132.5 mAh/g at 5C. [ABSTRACT FROM AUTHOR]