Search

The rapid demand growth of lithium-ion batteries (LIBs) will inevitably lead to a shortage of related metal resources. Recycling valuable metals from spent LIB has become imperative. Here, we propose a non-hazardous, reliable, and efficacious process for in situ recovery of valuable components from spent LiNi0.5Co0.2Mn0.3O2 cathode. First, the cathode sheets pre-acquired by disassembly are thermally treated in CO2 atmosphere, and the intact Al foils with obvious metallic luster are recovered. The lithium component (Li2CO3) is preferentially dissolved in water, and the recovery efficiency reached 92.84 %. Meanwhile, the residues concentrated with Ni, Co, and Mn components are easily dissolved in sulfuric acid solution without any additional heat treatment, and no explosive gases are generated. Then, by comparing the thermal reduction characteristics of cathode materials under different atmospheres (Air, Ar, and H2/Ar), the mechanism of pyrolysis of cathode materials under CO2 atmosphere and the role of CO2 in the thermal reduction process are systematically studied. This work not only provides a novel method for the recycling of spent cathode materials but also guarantees the safety of related personnel and properties.

An all annealing-free solution-manufacturing is regarded as a technological advancement for the development of flexible organic solar cells (OSCs), which can prevent the distortion of plastic substrates, avoid destroying the active components of the devices, and simplify the device fabrication. Here, we report an efficient all annealing-free solution-processed flexible OSC integrated on a soft polyethylene (PE) substrate. The transparent anodes, hole-transport layers, active layers and electron-transport layers are solution-processed at room temperature without thermal annealing treatments. Thanks to both the as-developed gentle superacid doping and air-drying treatments at room temperature that enable a high-merit flexible anode on the soft PE substrates, the annealing-free flexible OSCs yield a high efficiency of 14.66% along with a high power-per-weight of 6.33 W g−1, which is close to that (15.73%) of thermally annealed rigid OSCs based on indium tin oxide anodes. Due to the mild annealing-free solution-processing and the soft PE substrates having an extremely low Young's modulus of only 0.2 GPa, the flexible OSCs maintain a high flexibility in a harsh bending test.

Gel polymer electrolytes (GPEs) have attracted ever-increasing attention in Li-ion batteries, due to their great thermal stability and excellent electrochemical performance. Here, a flexible poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based GPE doped with an appropriate proportion of the PEO and SiO2 is developed through a universal immersion precipitation method. This porous PVDF-HFP-PEO-SiO2 GPE with high ionic conductivity and lithium-ion transference number (tLi+) can enhance the electrochemical performance of LiFePO4 cells, leading to superior rate capability and excellent cycling stability. Moreover, the PVDF-HFP-PEO-SiO2 GPE effectively inhibits the lithium dendrite growth, thereby improving the safety of Li-ion batteries. In view of the simplicity in using the gel polymer electrolyte, it is believed that this novel GPE can be used as a potential candidate for high-performance Li-ion batteries.

The cyclability of lithium-ion batteries (LIBs) is often affected by the components of the solid electrolyte interphase (SEI) layer which is generated from electrochemical decomposition of electrolyte. Here, lithium difluorophosphate (LiPO2F2) is studied in this work. When 1.6 wt% LiPO2F2 additive is incorporated into the reference electrolyte, the capacity retention of graphite/Li half-cell is increased from 82.53% to 98.04% and the capacity retention of LiCoO2/Li half-cell is increased from 89.60% to 97.53% after 160 cycles. Electrochemical impedance spectroscopy (EIS) indicates that the SEI layer containing LiPO2F2 can decrease the surface impedance of cells in the last stage cycle. In situ atomic force microscopy (AFM), DFT calculations and X-ray photoelectron spectroscopy (XPS) results show that LiPO2F2 is deposited on the surface of both LiCoO2 and graphite electrodes, which effectively protects the graphite anode and suppresses the degradation of the cathode during the long-term cycling of LIBs.