Pengfei Xiao

High rate capability caused by surface cubic spinels in Li-rich layer-structured cathodes for Li-ion batteries.

Modified Li-rich layered cathode Li(Li0.2Mn0.54Ni0.13Co0.13)O2 has been synthesized by a simple strategy of using surface treatment with various amounts (0-30 wt.%) of Super P (carbon black). Based on detailed characterizations from X-ray diffraction (XRD), high resolution transmission electron microscope (HRTEM), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS), it is suggested that the phase transformation from Li2MnO3-type of structure to spinel-like phase take place at the surface regions of particles during post annealing process at 350 °C, leading to increase in both first coulombic efficiency and rate capability, from 78% and 100 mAh · g(-1) (charge capacity at 2500 mA · g(-1)) of the pristine material to 93.4% and 200 mAh · g(-1). The evidences of spinel formation and the reasons for electrochemical enhancement are systematically investigated.

HLA-B*13:01 and the dapsone hypersensitivity syndrome.

BACKGROUND Dapsone is used in the treatment of infections and inflammatory diseases. The dapsone hypersensitivity syndrome, which is associated with a reported mortality of 9.9%, develops in about 0.5 to 3.6% of persons treated with the drug. Currently, no tests are available to predict the risk of the dapsone hypersensitivity syndrome. METHODS We performed a genomewide association study involving 872 participants who had received dapsone as part of multidrug therapy for leprosy (39 participants with the dapsone hypersensitivity syndrome and 833 controls), using log-additive tests of single-nucleotide polymorphisms (SNPs) and imputed HLA molecules. For a replication analysis, we genotyped 24 SNPs in an additional 31 participants with the dapsone hypersensitivity syndrome and 1089 controls and performed next-generation sequencing for HLA-B and HLA-C typing at four-digit resolution in an independent series of 37 participants with the dapsone hypersensitivity syndrome and 201 controls. RESULTS Genomewide association analysis showed that SNP rs2844573, located between the HLA-B and MICA loci, was significantly associated with the dapsone hypersensitivity syndrome among patients with leprosy (odds ratio, 6.18; P=3.84×10(-13)). HLA-B*13:01 was confirmed to be a risk factor for the dapsone hypersensitivity syndrome (odds ratio, 20.53; P=6.84×10(-25)). The presence of HLA-B*13:01 had a sensitivity of 85.5% and a specificity of 85.7% as a predictor of the dapsone hypersensitivity syndrome, and its absence was associated with a reduction in risk by a factor of 7 (from 1.4% to 0.2%). HLA-B*13:01 is present in about 2 to 20% of Chinese persons, 1.5% of Japanese persons, 1 to 12% of Indians, and 2 to 4% of Southeast Asians but is largely absent in Europeans and Africans. CONCLUSIONS HLA-B*13:01 was associated with the development of the dapsone hypersensitivity syndrome among patients with leprosy. (Funded by the National Natural Science Foundation of China and others.).

High-Performance Lithium-Ion Cathode LiMn0.7Fe0.3PO4/C and the Mechanism of Performance Enhancements through Fe Substitution

LiMn1-xFexPO4/C (x = 0 and 0.3) with a uniform carbon coating and interspersed carbon particles was prepared by a high-energy ball-milling (HEBM)-assisted solid-state reaction. The as-synthesized LiMn0.7Fe0.3PO4/C delivered an excellent rate performance as a LiMnPO4 class of materials. Specifically, the specific discharge capacity was 164 mAh/g (96% of theoretical value) at the 0.05 C rate and 107 mAh/g at the 5 C rate (1 C = 170 mA/g). Electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT) measurements indicated improvements in the transport of electrons and Li(+) as well as the emergence of a single-phase region in lithium extraction and insertion reactions.

Li-rich Thin Film Cathode Prepared by Pulsed Laser Deposition

Li-rich layer-structured cathode thin films are prepared by pulsed laser deposition. X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), X-ray photoelectron spectroscopy (XPS) and electrochemical testing in half battery cells are used to characterize crystal structure, surface morphology, chemical valence states and electrochemical performance of these thin films, respectively. It is observed that partial layer to spinel transformation takes place during post annealing, and the layered structure further gradually transforms to spinel during electrochemical cycling based on the analysis of dQ/dV. Electrochemical measurement shows that the thin film electrode deposited at 350 mTorr and post-annealed at 800°C possesses the best performance.

Hollow microspherical LiFePO4/C synthesized from a novel multidentate phosphonate complexing agent

We report the electrochemical performance of hollow microspherical LiFePO4/C synthesized from a novel multidentate phosphonate complexing agent via a facile, up-scalable and template/surfactant-free route.