High-nickel layered oxides are promising cathode materials for next-generation lithium-ion batteries due to their high energy density, but their structural instability at high voltages remains a critical challenge. This study investigates how Ni migration influences phase segregation, Li/Ni antisite defect accumulation, and mechanical degradation in LiNiO2 (LNO) through a combination of synchrotron X-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS), transmission electron microscopy (TEM), and density functional theory (DFT) calculations. The results reveal that at high voltages, Ni migrates into tetrahedral sites, leading to the formation of coexisting R3̅m phases with distinct lattice behaviors. This phase segregation induces inhomogeneous lithium distribution, internal stress, and strain accumulation, ultimately promoting microcrack formation and accelerating structural degradation. While Ni migration is partially reversible upon discharge, continuous cycling leads to the progressive accumulation of Li/Ni antisite defects, which disrupt Li-ion transport and further destabilize the structure. The findings describe the role of bulk Ni migration in phase segregation, linking atomic-scale lattice distortions to long-term performance limitations in high-Ni cathodes. These insights suggest strategies such as selective doping to mitigate Ni migration and improve the structural stability.
All-solid-state batteries (ASSBs) are regarded as a promising route to enhanced safety and energy density through the use of lithium metal anodes. However, lithium dendrite growth and interfacial instability between Li and the solid electrolyte (SE) remain critical bottlenecks. To address these issues, a spontaneously preformed solid electrolyte interphase (PSEI) on the surface of the SE strategy was devised. By incorporating lithium difluoro(oxalato)borate (LiODFB) as a tailored SE additive into Li5.5PS4.5Cl1.5, an in situ SEI is engineered that synergistically suppresses dendrite formation, stabilizes the Li/SE interface, and mitigates mechanical degradation. The resulting multifunctional PSEI, which consists of a hybrid organic–inorganic outer layer and an inorganic-rich inner layer, is found to both reduce the electronic conductivity of the SE (thus preventing Li nucleation within SEs) and accommodate mechanical degradation arising from Li plating/stripping to avoid contact loss. Consequently, Li–Li symmetric cells incorporating LPSC with PSEI achieved a critical current density (CCD) of 2.4 mA cm–2 and ultrastable cycling for over 3500 h at 0.2 mA cm–2. The Li-LiNi0.8Co0.1Mn0.1O2 full cells retained 80% capacity after 310 cycles at 0.5 C and can also operate stably under 4.5 V. This work establishes a rational interface design for SEs that integrates electronic and mechanical modulation with electrochemical stability to unlock the potential of lithium metal anodes in ASSBs.
PBT and PET are subjected to thermal-oxidative degradation and thermomechanical degradation during the process of melt blending, which affect the polymer structure and properties. The effect of feed properties of PET and the addition of modified nanoparticles on blends are a question worthy of discussion. This work describes the melting and thermal stability, the crystallization behavior and non-isothermal crystallization kinetic, the rheological behaviors and mechanical properties of several PBT/PET blends prepared by twin-screw melt extrusion. Results show that the molecular chain of the polyester blends obtained by stable extrusion are not significantly degraded, there is only one obvious melting peak and crystallization peak on the thermal analysis curves, and the melting point is lower than either of the two polyesters. An appropriate amount of SD can effectively reduce the crystallization rate of the PBT material and extend the crystallization time. The rheological behavior of PBT/PET blends is complicated than PET raw materials and SD, as well as the melt processing temperature and shear rate will all affect the rheological behavior of the blends. For example, at low shear rate, polyester blends with SD exhibit strong shear thinning behavior. In general, the SD content affects the rheological property of blends in a way similar to the law of influence on crystallization behavior. When SD content is 0.3 wt%, a polyester product with higher elongation at break than pure PBT can be obtained. This can provide a useful reference for preparing commercialized polyester blend products with good melt processability and elongation by simple blending.
危险品化学品经营许可证（带存储）