Structure and Charge Regulation Strategy Enabling Superior Cyclability for Ni-Rich Layered Cathode Materials.

Ni-rich layered oxides are significantly promising cathode materials for commercial high-energy-density lithium-ion batteries. However, their major bottlenecks limiting their widespread applications are capacity fading and safety concerns caused by their inherently unstable crystal structure and highly reactive surface. Herein, surface structure and bulk charge regulation are concurrently achieved by introducing high-valence Ta5+ ions in Ni-rich cathodes, which exhibit superior electrochemical properties and thermal stability, especially a remarkable cyclic stability with a capacity retention of 80% for up to 768 cycles at a 1C rate versus Li/Li+ . Due to the partial Ta enrichment on surface, the regulated surface enables high reversibility of Li+ insertion/extraction by preventing surface Ni reduction in deep charging. Moreover, bulk charge regulation that boosts charge density and its localization on oxygen remarkably suppresses microcracks and oxygen loss, which in turn prevents the fragmentation of the regulated surface and structural degradation associated with oxygen skeleton. This study highlights the significance of an integrated optimization strategy for Ni-rich cathodes and, as a case study, provides a novel and deep insights into the underlying mechanisms of high-valence ions substitution of Ni-rich layered cathodes.

Principle understanding towards synthesizing Fe/N decorated carbon catalysts with pyridinic-N enriched and agglomeration-free features for lithium-oxygen batteries.

Metal-N-decorated carbon catalysts are cheap and effective alternatives for replacing the high-priced Pt-based ones in activating the reduction of oxygen for metal-air or fuel cells. The preparation of such heterogeneous catalysts often requires complex synthesis processes, including harsh acid treatment, secondary pyrolysis processes, etching, etc., to make the heteroatoms evenly dispersed in the carbon substrates to obtain enhanced activities. Through combined experimental characterizations, we found that by precise control of the precursors added, a Fe/N uniformly distributed, agglomeration-free Fe/N decorated Super-P carbon material (FNDSP) can be easily obtained by a one-pot synthesis process with distinctly higher pyridinic-N content and elevated catalytic activity. An insight into this phenomenon was carefully demonstrated and also verified in Li-O2 batteries, which delivered a high discharging platform of 2.85 V and can be fully discharged with a capacity of 5811.5 mA h gcarbon+catalyst -1 at the cut-off voltage of 2.5 V by the low-cost Super-P modified catalyst.

High-discharge-voltage lithium-rich layered-oxide cathode materials based on low oxygen vacancy.

We prepare the lithium-rich layered oxide Li1.2Mn0.54Co0.13Ni0.13O2 with a 3.65 V average-discharge voltage by using lithiated homologous spinel Li0.4Mn0.54Ni0.13Co0.13O1.6 in an O2 atmosphere. In addition, we discuss how oxygen vacancies affect the discharge voltage.

Intramuscular injection of bone marrow mononuclear cells contributes to bone repair following midpalatal expansion in rats.

Healing from injury requires the activation and proliferation of stem cells for tissue repair. Previous studies have demonstrated that bone marrow is a central pool of stem cells. The present study aimed to investigate the route undertaken by bone marrow mononuclear cells (BMMCs) following BMMC transplantation by masseter injection in a rat model of midpalatal expansion. The rats were divided into five groups according to the types of midpalatal expansion, incision and BMMC transplantation. Samples of midpalatal bone from the rats in each group were used for histological and immunohistochemical assessments to track and evaluate the differential potentials of the transplanted BMMCs in the masseter muscle and midpalatal bone. Bromodeoxyuridine was used as a BMMC tracing label, and M­cadherin was used to detect muscle satellite cells. The BMMCs injected into the masseter were observed, not only in the masseter, but also in the blood vessels and oral mucosa, and enveloped the midpalatal bone. A number of the BMMCs transformed into osteoblasts at the boundary of the neuromuscular bundle, and were embedded in the newly formed bone during midpalatal bone regeneration. The results of the present study suggested that BMMCs entered the circulation and migrated from muscle to the bone tissue, where they were involved in bone repair. Therefore, BMMCs may prove useful in the treatment of various types of cancer.