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Aiming at the difficult-to-treat high-concentration phosphorus in the spent electroless nickel plating baths, the transformation trends of phosphorus species in catalytic oxidation-reduction, H2O2 oxidation, calcium hypochlorite oxidation, and Fenton oxidation treatment processes were monitored and analyzed. Subsequently, the coagulation/precipitation process was further used to remove TP from the wastewater, and the final TP removal effect was investigated. The experimental results showed that there was no obvious selectivity in the three oxidation treatments of H2O2 oxidation, calcium hypochlorite oxidation, and Fenton oxidation, and a certain concentration of difficult-to-treat H2PO2- remained in the wastewater after the reaction, with TP removal rates of 81.9%, 92.2%, and 96%, respectively. After catalytic oxidation-reduction treatment, almost all phosphorus species in the spent electroless nickel plating baths were converted to HPO32-, and the TP removal rate could reach 99.7% after calcium chloride precipitation treatment. Meanwhile, HPO32- was also a valuable resource that could be utilized. By adding Al2(SO4)3·18H2O to the wastewater treated by catalytic oxidation-reduction, aluminum phosphite products could be recovered, which was of great significance in wastewater treatment, green environmental protection and resource utilization.

The challenges posed by the low ionic conductivity at room temperature and the poor compatibility of the Li metal/electrolyte interface restrict the practical application of solid-state polymer electrolytes. Herein, a bifunctional heptafluorobutyric anhydride (HFA) additive has been proposed to overcome the abovementioned problems of the polyvinylidene fluoride (PVDF)-based polymer-in-salt solid electrolyte. The experimental data, density functional theory (DFT) calculations and the molecular dynamics (MD) simulations demonstrate that the HFA additive can promote the formation of nanometric aggregates (n-AGGs), which can construct a continuous and fast Li+ ion transport network in the solid electrolyte. Meanwhile, the HFA additive exhibits a lower LUMO energy level, and then it can contribute a LiF-rich SEI at the Li metal/electrolyte interface. As a result, the fabricated solid electrolytes with HFA additive can deliver an improved ion conductivity of 2.41 × 10−4 S cm−1 at room temperature, which makes the symmetric Li‖Li batteries show an ultra-long cycle life (≈1700 h at 0.1 mA h cm−2). Besides, the HFA-containing solid electrolytes show greatly enhanced cycle stability compared to the pristine electrolyte in the full cells when paired with a LiFePO4 cathode or high-voltage LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode. This work provides a critical insight into the mechanism of a new additive to enhance the electrochemical performances of PVDF-based polymer-in-salt solid-state electrolytes. [ABSTRACT FROM AUTHOR]

Lithium nitrate has been widely used to improve the interfacial stability of Li metal anode in ether electrolyte. However, the low solubility limits its application in carbonate electrolytes for high‐voltage Li metal batteries. Herein, nitrated polycaprolactone (PCL‐ONO2), which is prepared via the acylation of polycaprolactone diol (PCL‐diol) followed by the grafting of nitrate group, has been proposed as an electrolyte additive to introduce high‐concentration NO3− into carbonate electrolytes for the first time. The theoretical calculations and X‐ray photoelectron spectroscopy depth profiling demonstrate that the PCL‐ONO2 additive preferentially reacts with Li metal and in situ constructs a stable dual‐layered solid electrolyte interphase film, presenting an inner nitride‐rich layer and an outer flexible PCL‐based layer on the surface of Li metal anode. As a result, the Li metal anode delivers an impressive long‐term cycling performance over 1400 h at an elevated area capacity of 10.0 mAh cm−2 and an ultrahigh current density of 10.0 mA cm−2 in the Li symmetrical cells. Moreover, the PCL‐ONO2 additive enables the full cells constructed by coupling high‐loading LiFePO4 (20.0 mg cm−2) or LiNi0.5Co0.2Mn0.3 (16.5 mg cm−2) cathode and thin Li metal anode (≈50 µm) to demonstrate greatly improved cycling stability and rate capability. [ABSTRACT FROM AUTHOR]