The widespread application of Li-ion batteries (LIBs) in electric vehicles requires high energy density and high stability of batteries in prolonged and diverse storage and service conditions. As one of the most practical and promising cathode materials for LIBs, Ni-rich layered oxide cathodes possess high capacity together with low cost. Nevertheless, due to its high sensitivity toward exposure to ambient air, structural evolution will occur accompanied with the generation of an impurity layer on the surface of the cathode. The structural instability of such Ni-rich cathodes in the storage process inevitably deteriorates their performance in subsequent service occasions. Herein, we carefully investigated the degradation mechanism of the Ni-rich cathode (LiNi_0.8Co_0.15Al_0.05O₂, NCA) after storage in the ambient air by means of in situ and ex situ characterization. The formed impurity layer on the surface of NCA has been determined as “residual lithium” composed of lithium carbonate and lithium bicarbonate, and nickel carbonate species due to the H⁺/Li⁺ exchange reaction followed by carbonation. Moreover, lithium and nickel extracted from the lattice to the surface further aggravated the formation of surface impurities, leaving a Li deficiency layer accompanied with spinel and rock salt phases near the surface. Simultaneously, the degraded NCA possessed increased c-axis and decreased a-axis lattice parameters, a lower degree of Ni/Li anti-sites and more surface Ni²⁺ ions, which caused the deterioration of its electrochemical performances. In addition, we proposed a facile method for regenerating the degraded NCA after ambient storage. By mixing the degraded NCA with a certain amount of additional lithium source and calcining the mixture in an oxygen atmosphere at a given temperature for a certain time, the degraded NCA was restored to its original state and regained superior electrochemical performances. It is highly expected that this work may help deepen the understanding of the storage failure and regeneration for Ni-rich cathode materials, and promote the practical industrialization and application of LIBs.

A series of Cu–Mn–SSZ-13 catalysts were obtained by co-exchange of Mn and Cu into SSZ-13 together (ion exchange under a mixed solution of Cu(NO₃)₂ and Mn(NO₃)₂) and compared with Cu–SSZ-13 catalysts on the selective catalytic reduction (SCR) of nitric oxide (NO) by ammonia. The effects of total ion exchange degree and the effect of Mn species on the structure and performance of catalysts before and after hydrothermal aging were studied. All fresh and aged catalysts were characterized with several methods including temperature-programmed desorption with NH₃ (NH₃-TPD), X-ray diffraction (XRD), ²⁷Al and ²⁹Si solid-state nuclear magnetic resonance (NMR), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and low-temperature N₂ adsorption–desorption techniques. The results showed that the increase of the total ion exchange degree can reduce the content of residual Brønsted acid sites of catalysts, thus relieved the dealumination and the decrease of crystallinity of the catalyst during hydrothermal aging. The moderate addition of a Mn component in Cu–Mn–SSZ-13 catalysts significantly increased the activity of NO conversion at low temperature range. The selected Cu(0.2)Mn(0.1)–SSZ-13 catalyst achieved a high NO conversion of >90% in the wide and low temperature range of 175–525 °C and also exhibited good N₂ selectivity and excellent hydrothermal stability, which was related to the inhibition of the Mn component on the aggregation of Cu species and the pore destruction of the catalyst during hydrothermal aging.

Dielectric barrier discharge (DBD) could generate non-thermal plasma (NTP) with the advantage of fast reactivity and high energy under atmosphere pressure and low-temperature. The presented work investigated the selective catalytic reduction (SCR) of nitric oxide (NO) using a combination of NTP and an Mn-Cu/ZSM5 catalyst with ammonia (NH₃) as a reductant. The experimental results illustrate that the plasma-assisted SCR process enhances the low-temperature catalytic performance of the Mn-Cu/ZSM5 catalyst significantly, and it exhibits an obvious improvement in the NO removal efficiency. The reaction temperature is maintained at 200 °C in order to simulate the exhaust temperature of diesel engine, and the 10% Mn-8% Cu/ZSM5 catalyst shows the highest NO removal performance with about 93.89% at an energy density of 500 J L⁻¹ and the selectivity to N₂ is almost 99%. The voltage, frequency and energy density have a positive correlation to NO removal efficiency, which is positively correlated with the power of NTP system. In contrast, the O₂ concentration has a negative correlation to the NO removal, and the NO removal efficiency cannot be improved when the NO removal process reaches reaction equilibrium in the NTP system.

Passive NOx adsorber (PNA) materials are primarily considered for reducing nitrogen oxide emissions during the low-temperature cold start of a motor vehicle. Pd/SSZ-13 has attracted considerable attention because of its outstanding hydrothermal stability and sulfur resistance. Optimizing the dispersion of precious metal Pd in Pd/SSZ-13 is crucial for enhancing PNA performance and nitrogen oxide adsorption capability. In this study, we prepared Pd/SSZ-13 using different methods and evaluated their influence on the NOx adsorption capability. The characterization results show that the dispersion of precious metal Pd in the Pd/SSZ-13 catalyst prepared by the quantitative ion-exchange method is as high as 92.13%, and the loading amount is as high as 98.93%. Pd predominantly exists as Pd2+, achieving near-total loading and further improving the catalyst’s NOx adsorption capacity. This study offers innovative approaches and methods for applying Pd/SSZ-13 as a PNA material, serving as a reference for its further optimization and performance enhancement. Continued research into the preparation and adsorption performance of Pd/SSZ-13 materials could offer solutions to reduce motor vehicle nitrogen oxide emissions.

Currently, selective catalytic reduction (SCR) systems have become an essential part in diesel engines, and urea crystallization is one of the most serious issues in SCR systems. In this paper, the urea deposit formation processes in the SCR system were investigated by numerical simulations based on a fluid–solid coupling method. The results show that the masses of the wall film and solid urea are larger at conditions with lower temperatures and higher injection rates. At higher temperatures, cyanate ions and ammonium ions are the most predominant compositions in the wall film, while at lower temperatures, solid urea is the main composition. It could also be deduced that the location of urea crystallization is more affected by the design of mixer at higher temperatures, whereas at lower temperatures, the location and installation angle of urea-water solution injector play a more important role.

Cu-SSZ-39 zeolite with an AEI structure exhibits excellent hydrothermal stability and can be a potential alternative to Cu-SSZ-13 zeolite SCR catalysts for NO_x removal in diesel vehicles. However, the inferior low-temperature performance of Cu-SSZ-39 leads to substantial NO_x emissions during the cold-start period, impeding its practical application. In this study, Ce-Mn oxide-modified Cu-SSZ-39 catalysts (CeMnO_x/Cu-SSZ-39) and references (CeO₂/Cu-SSZ-39 and MnO_x/Cu-SSZ-39) were prepared by the ion-exchange of Cu ions followed by impregnation of the oxide precursors, with the aim of enhancing the NH₃-SCR performance at low temperatures. The modified catalysts exhibited improved low-temperature activity and hydrothermal stability compared to the unmodified counterpart. In particular, CeMnO_x/Cu-SSZ-39 showed the highest activity among the three catalysts and achieved NO_x conversions above 90% within the temperature range of 180 °C to 600 °C, even after undergoing hydrothermal aging at 800 °C. Experimental results indicated that the synergistic effect between Ce and Mn in CeMnO_x improves the redox properties and acidity of the catalyst due to the presence of Ce³⁺, Mn⁴⁺, and abundant adsorbed oxygen species, which facilitate low-temperature SCR reactions. Furthermore, the interaction of CeMnO_x with Cu-SSZ-39 stabilizes the zeolite framework and hinders the agglomeration of Cu species during the hydrothermal aging process, contributing to its exceptional hydrothermal stability. The kinetics and NO oxidation experiments demonstrated that CeMnO_x provides access to fast SCR reaction pathways by oxidizing NO to NO₂, resulting in a significant increase in low-temperature activity. This study provides novel guidelines for the design and preparation of Cu-SSZ-39 zeolite with outstanding SCR performance over a wide temperature range.