Li(Ni(0.8)Co(0.1)Mn(0.1))O(2) (NCM811) was synthesized using alkali chlorides as a flux and the performance as a cathode material for lithium ion batteries was examined. Primary particles of the powder were segregated and grown separately in the presence of liquid state fluxes, which induced each particle to be composed of one primary particle with well-developed facet planes, not the shape of agglomerates as appears with commercial NCMs. The new NCM showed far less gas emission during high temperature storage at charged states, and higher volumetric capacity thanks to its high bulk density. The material is expected to provide optimal performances for pouch type lithium ion batteries, which require high volumetric capacity and are vulnerable to deformation caused by gas generation from the electrode materials.
The formation of vacancies and the structural stability of layered lithium nickel oxide (LNO)-based cathode materials are investigated. The thermodynamic stability of oxygen and lithium vacancies and their most stable configurations are examined by first-principles density functional theory calculations. The underlying chemical mechanism is analyzed by a molecular orbital method. The weaker ionic bonding between Ni and O than between Co and O is found to be the main cause for the imperfect structure of LNO crystals. On the basis of these calculations, phase diagrams of the Li−(Ni,Co)−O system were simulated. The crystals containing vacancies are included as independent phases in the simulation. This approach enabled investigation of the relationship between the processing conditions and vacancy formation. The O and Li vacancy pairs are simulated to appear with high temperature processing. On the basis of the calculation of energy barriers, we speculate that these vacancy pairs provide an alternative migration route for Ni ions, which causes the observed structural instability. The effect of oxygen partial pressure was also examined. The first-principles calculation results were compared with experimental results, which showed excellent agreement confirming the validity of the models and calculation methods used in this study.
Background There is an increasing interest in HER2-low breast cancer with promising data from clinical trials using novel anti-HER2 antibody–drug conjugates. We explored the differences in clinicopathological characteristics and survival outcomes between HER2-low and HER2-IHC 0 breast cancer. Methods Using nationwide data from the Korean Breast Cancer Registry between 2006 and 2011, 30,491 patients with stages I to III breast cancer were included in the analysis: 9,506 (31.2%) in the HER2-low group and 20,985 (68.8%) in the HER2-IHC 0 group. Kaplan–Meier and Cox proportional hazards regression survival analysis were used to compare breast cancer-specific survival between the two groups. Results HER2-low breast cancer was more frequent in patients with hormone receptor-positive breast cancer than in those with triple-negative breast cancer. In patients with hormone receptor-positive breast cancer, HER2-low breast cancer was associated with fewer T4 tumors, higher histological grade, and a negative lymphatic invasion. In patients with triple-negative breast cancer, HER2-low breast cancer was associated with a high lymph node ratio and positive lymphatic invasion. HER2-low breast cancer was significantly associated with a lower Ki-67 labeling index. No significant difference was observed in overall survival between the two groups. HER2-low breast cancer showed significantly better breast cancer-specific survival than HER2-IHC 0 breast cancer, regardless of the hormone receptor status. In multivariate analysis, the impact of low HER2 expression on breast cancer-specific survival was significant only in triple-negative breast cancer (HRs, 0.68; 95% CI, 0.49–0.93; P = 0.019). Conclusions These findings suggest that the biology and clinical impact of low HER2 expression can differ according to the hormone receptor status and support the need for further investigation on the understanding of the biology of HER2-low breast cancer.
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