【摘 要】
：
P2-type layered oxide Na0.67Fe0.5Mn0.5O2 is recognized as a very promising cathode material for sodium-ion batteries due to the merits of high capacity,high voltage,low cost,and easy preparation.However,its unsatisfactory cycle and rate performances remai
【机 构】
：
School of Materials Science and Engineering,Engineering Research Center of High Performance Copper A
论文部分内容阅读
P2-type layered oxide Na0.67Fe0.5Mn0.5O2 is recognized as a very promising cathode material for sodium-ion batteries due to the merits of high capacity,high voltage,low cost,and easy preparation.However,its unsatisfactory cycle and rate performances remain huge obstacles for practical applications.Here,we report a strategy of SnO2 modification on P2-type Na0.67Fe0.5Mn0.5O2 to improve the cycle and rate performance.Scanning electron microscope(SEM) and transmission electron microscope(TEM) images indicate that an insular thin layer SnO2 is coated on the surface of Na0.67Fe0.5Mn0.5O2 after medication.The coating layer of SnO2 can protect Na0.67Fe0.5Mn0.5O2 from corrosion by electrolyte and the cycle performance is well enhanced.After 100 cycles at 1 C rate(1 C=200 mA/g),the capacity of SnO2 modified Na0.67Fe0.5Mn0.5O2 retains 83 mA·h/g(64％ to the initial capacity),while the capacity for the pristine Na0.67Fe0.5Mn0.5O2 is only 38 mA·h/g(33.5％ to the initial capacity).X-Ray photoelectron spectroscopy reveals that the ratio of Mn4+ increases after SnO2 modification,leading to less oxygen vacancy and expanded lattice.As a result,the capacity of Na0.67Fe0.5Mn0.5O2 increases from 178 mA·h/g to 197 mA·h/g after SnO2 modification.Furthermore,the rate performance of Na0.67Fe0.5Mn0.5O2 is enhanced with SnO2 coating,due to high electronic conductivity of SnO2 and expanded lattice after SnO2 coating.The capacity of SnO2 modified Na0.67Fe0.5Mn0.5O2 at 5 C increases from 21 mA·h/g(pristine Na0.67Fe0.5Mn0.5O2) to 35 mA·h/g.
其他文献
The preparation of high-resolution micro-patterns is urgently demanded for developing opto-/electric-devices in various applications.Generally,solution processes have been commonly used for fabricating micro-patterned surfaces for its mild operation condi
Extracorporeal membrane oxygenation(ECMO) has emerged as a viable treatment in severe cases of acute respiratory distress syndrome,acute respiratory failure,and adult respiratory distress syndrome.However,thromboembolic events stemming from the use of ECM
本篇文章主要以机会信号辐射源定位为应用背景,以多普勒频率的变化率为观测量,介绍矩阵乘法的实际应用.
Fluorine is present in the hydroxyapatite mineral in natural tooth enamel,which plays a key role in the prevention of dental caries.The aim of this study is to synthetize the fluorinated urchin-like serried hydroxyapatite(FnUHA) particles with different d
Poly(lactic-co-glycolic acid)(PLGA) microparticles represent an important class of materials used for drug delivery.Current synthesis frequently uses conventional emulsion,where dichloromethane(DCM) is used as the organic phase solvent.Due to the health a
薄壁注塑聚丙烯是一种高附加值聚丙烯新产品.近年来,国内各生产厂家,采用气相法聚合反应工艺和本体气相法聚合工艺均实现了薄壁注塑聚丙烯新产品开发.本文阐述了薄壁注塑专用树脂的特点,以及利用现有工艺开发该类树脂专用料的重要性.从聚合工艺角度,对近五年来国内薄壁注塑专用树脂的研发和生产情况进行了讨论;比较了几种聚合工艺的特点,对研发和生产过程中所使用的催化剂、工艺参数以及产品特点进行了总结,并对薄壁注塑聚丙烯未来的发展趋势进行了展望.
Alkynylplatinum(Ⅱ) bzimpy complexes of trimethylammonium-benzylethynyl ligand have been synthesized and characterized.Complexes with long alkyl chains have been found to exhibit interesting self-assembly properties in the acetonitrile solution.The amphiph
Improving the permeate flux but retaining the rejection of thin-film composite(TFC) polyamide nanofiltration(NF) membrane is a high requirement for desalination.In this work,a calcium ion(Ca2+) coordinated polyamide(PA) NF membrane was prepared by directl
The growth of single-walled carbon nanotubes(SWCNTs) on substrates has attracted great interests because of the potential applications in various fields.Carbon monoxide(CO)was used as the carbon source for the growth of SWCNTs on silicon substrates.Random
Graphene nanoribbons with zigzag edges(ZGNRs) have attracted much attention for their spin-polarized edge states predicted more than 15 years ago.Since the ZGNRs are fabricated on metal substrates using molecular precursors,due to their strong coupling wi