Achieving High Rate and Long Cycle Performance of Na2FePO4F Cathode Through Co-Modification of Ti Doping and Carbon Coating.

Layered Na2FePO4F (NFPF) cathode material has received widespread attention due to its green nontoxicity, abundant raw materials, and low cost. However, its poor inherent electronic conductivity and sluggish sodium ion transportation seriously impede its capacity delivery and cycling stability. In this work, NFPF by Ti doping and conformal carbon layer coating via solid-state reaction is modified. The results of experimental study and density functional theory calculations reveal that Ti doping enhances intrinsic conductivity, accelerates Na-ion transport, and generates more Na-ion storage sites, and pyrolytic carbon from polyvinylpyrrolidone (PVP) uniformly coated on the NFPF surface improves the surface/interface conductivity and suppresses the side reactions. Under the combined effect of Ti doping and carbon coating, the optimized NFPF (marked as 5T-NF@C) exhibits excellent electrochemical performance, with a high capacity of 108.4 mAh g-1 at 0.2C, a considerable capacity of 80.0 mAh g-1 even at high current density of 10C, and a high capacity retention rate of 81.8% after 2000 cycles at 10C. When assembled into a full cell with a hard carbon anode, 5T-NF@C also show good applicability. This work indicates that co-modification of Ti doping and carbon coating makes NFPF achieve high rate and long cycle performance for sodium-ion batteries.

A Web of Science-based scientometric analysis about mammalian target of rapamycin signaling pathway in kidney disease from 1986 to 2020.

BACKGROUND: The mammalian target of rapamycin (mTOR) signaling pathway is vital for the regulation of cell metabolism, growth and proliferation in the kidney. This study aims to show current research focuses and predict future trends about mTOR pathway in kidney disease by the methods of scientometric analysis. METHODS: We referred to publications from the Web of ScienceTM Core Collection (WoSCC) Database. Carrot2, VOSviewer and CiteSpace programs were applied to evaluate the distribution and contribution of authors, institutes and countries/regions of extensive bibliographic metadata, show current research focuses and predict future trends in kidney disease's area. RESULTS: Until July 10, 2020, there are 2,585 manuscripts about mTOR signaling pathway in kidney disease in total and every manuscript is cited 27.39 times on average. The big name of course is the United States. Research hot spots include "diabetic nephropathy", "kidney transplantation", "autosomal dominant polycystic kidney disease", "tuberous sclerosis complex", "renal cell carcinoma" and "autophagy". Seven key clusters are detected, including "kidney transplantation", "autosomal dominant polycystic kidney disease", "renal transplantation", "renal cell carcinoma", "hamartin", "autophagy" and "tuberous sclerosis complex". CONCLUSIONS: Diabetic nephropathy, kidney transplantation, autosomal dominant polycystic kidney disease, tuberous sclerosis complex, renal cell carcinoma and autophagy are future research hot spots by utilizing scientometric analysis. In the future, it is necessary to research these fields.

N/P-Dual-Doped Carbon-Coated Na3V2(PO4)2O2F Microspheres as a High-Performance Cathode Material for Sodium-Ion Batteries.

Na3V2(PO4)2O2F (NVPOF) is attracting great interest due to its large capacity and high working voltage. However, poor electronic conductivity limits the electrochemical performance of NVPOF. Herein, we fabricate N/P-dual-doped carbon-coated NVPOF microspheres (labeled as NVPOF@P/N/C) via a hydrothermal process followed by heat treatment. This microsphere-structured NVPOF@P/N/C composite has a relatively high tap density of 1.22 g/cm3. TEM and XPS results reveal that the dual-doped carbon layer is tightly coated on the NVPOF surface due to the bridging effect of P and has a good protective effect on NVPOF. Density functional theory (DFT) calculations confirm that a N/P-dual-doped carbon layer is advantageous to achieve higher electronic conductivity and lower migration activation energy than those of the undoped and single N- or P-doped carbon layer. As a cathode material for a sodium-ion battery (SIB), NVPOF@P/N/C exhibits high capacity (128 mAh/g at 0.5 C and 122 mAh/g at 2 C) and ultralong cycle performance (only 0.037% capacity fading rate per cycle in 500 cycles at 2 C). We believe that the NVPOF@P/N/C composite is appealing for high-performance SIBs with large energy density.

Polydopamine-Derived Nitrogen-Doped Carbon-Covered Na3V2(PO4)2F3 Cathode Material for High-Performance Na-Ion Batteries.

Nitrogen-doped carbon-covered Na3V2(PO4)2F3 (NVPF/C-PDPA) composites have been successfully prepared by self-polymerization of dopamine on the NVPF surface and subsequent sintering. The X-ray diffraction results show that the NVPF/C-PDPA has good crystallinity and introducing dopamine does not affect the lattice structure of NVPF. The high-resolution transmission electron microscopy, high-angle annular dark-field images, and energy dispersive X-ray spectroscopy analyses reveal that the NVPF/C-PDPA particles are covered by a complete and uniform covering layer, which is effective at preventing corrosion of NVPF in the electrolyte to greatly increase cycling stability. Furthermore, N-doping into the carbon layer can produce additional active sites to improve the capacity especially the rate capacity. Such a NVPF/C-PDPA electrode delivers a remarkable rate capacity (98.0 mA h g-1 at 10 C) and superior cycle performance (∼95.8% capacity retention at 10 C after 800 cycles). We believe that this work may be beneficial for accelerating the development of high-performance electrode materials and the commercialization of Na-ion batteries.

Anthracite-Derived Dual-Phase Carbon-Coated Li3V2(PO4)3 as High-Performance Cathode Material for Lithium Ion Batteries.

In this study, low cost anthracite-derived dual-phase carbon-coated Li3V2(PO4)3 composites have been successfully prepared via a traditional solid-phase method. XRD results show that the as-prepared samples have high crystallinity and anthracite introduction has no influence on the LVP crystal structure. The LVP/C particles are uniformly covered with a dual-phase carbon layer composed of amorphous carbon and graphitic carbon. The effect of the amount of anthracite on the battery performance of LVP as a cathode material has also been studied. The LVP/C composite obtained with 10 wt % anthracite (LVP/C-10) delivers the highest initial charge/discharge capacities of 186.1/168.2 mAh g-1 at 1 C and still retains the highest discharge capacity of 134.0 mAh g-1 even after 100 cycles. LVP/C-10 also displays an outstanding average capacity of 140.8 mAh g-1 at 5 C. The superior rate capability and cycling stability of LVP/C-10 is ascribed to the reduced particle size, decreased charge-transfer resistance, and improved lithium ion diffusion coefficient. Our results demonstrate that using anthracite as a carbon source opens up a new strategy for larger-scale synthesis of LVP and other electrode materials with poor electronic conductivity for lithium ion batteries.

Protective effect of regular physical activity on major depressive episodes in patients with early stages of chronic kidney disease.

Previous studies have demonstrated an association between physical activity (PA) and depression in diverse population. The purpose of our study is to examine if PA within the recommended level over time is associated with major depressive episode (MDE) in patients with early stages of chronic kidney disease (CKD) in Mainland China. Patients with stages 2-5 CKD not receiving dialysis were enrolled from a nephrology outpatient clinic between May 2014 and February 2016. Based on the patterns of PA over time, all patients were divided into four groups: persistently active, from inactive to active, from active to inactive, and persistently inactive. An MDE was diagnosed by using the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition)-based the Mini International Neuropsychiatric Interview. Among 150 patients, 34 had a current MDE (22.7%) and 116 did not (77.3%). After multivariable adjustment, patients being persistently active had significantly lower odds of having an MDE (odds ratio 0.102, 95% confidence interval, 0.022-0.467, p = .003) compared with those who were persistently inactive. Additionally, patients with diabetes mellitus had significantly higher odds of having an MDE (odds ratio 4.287, 95% confidence interval, 1.473-12.483, p = .008) compared with those without diabetes mellitus. Our results suggest a protective effect of regular PA on MDE in patients with early stages of CKD in Mainland China.