Suppressing the P2−O2 phase transformation and Na+/vacancy ordering of high-voltage manganese-based P2-type cathode by cationic codoping

Author(s):  
Feng Li ◽  
Yuhang Tian ◽  
Yanyun Sun ◽  
Peiyu Hou ◽  
Xianqi Wei ◽  
...  
2013 ◽  
Vol 160 (4) ◽  
pp. A564-A568 ◽  
Author(s):  
Tomoaki Takasaki ◽  
Kazuya Nishimura ◽  
Takashi Mukai ◽  
Tsutomu Iwaki ◽  
Kaduo Tsutsumi ◽  
...  

2015 ◽  
Vol 17 (25) ◽  
pp. 16388-16397 ◽  
Author(s):  
Sondes Bauer ◽  
Lea de Biasi ◽  
Sven Glatthaar ◽  
Leonel Toukam ◽  
Holger Geßwein ◽  
...  

LiNi0.5Mn1.5O4 spinel cathode was studied during the first discharge cycle using combined full field TXM and XANES techniques to follow the chemical phase transformation as well as the microstructural evolution of cathode materials upon operation within an electrochemical cell.


2021 ◽  
Author(s):  
Ruihan Yang ◽  
Mengke Guan ◽  
Ruirui Zhao ◽  
Qiong Luo

The key for the application of LiCoO2 as lithium-ion battery electrode under high voltage is to suppress the irreversible phase transformation from the layered to the spinel/rocksalt structure during cycling....


Author(s):  
L. D. Ackerman ◽  
S. H. Y. Wei

Mature human dental enamel has presented investigators with several difficulties in ultramicrotomy of specimens for electron microscopy due to its high degree of mineralization. This study explores the possibility of combining ion-milling and high voltage electron microscopy as a means of circumventing the problems of ultramicrotomy.A longitudinal section of an extracted human third molar was ground to a thickness of about 30 um and polarized light micrographs were taken. The specimen was attached to a single hole grid and thinned by argon-ion bombardment at 15° incidence while rotating at 15 rpm. The beam current in each of two guns was 50 μA with an accelerating voltage of 4 kV. A 20 nm carbon coating was evaporated onto the specimen to prevent an electron charge from building up during electron microscopy.


Author(s):  
Lee D. Peachey ◽  
Clara Franzini-Armstrong

The effective study of biological tissues in thick slices of embedded material by high voltage electron microscopy (HVEM) requires highly selective staining of those structures to be visualized so that they are not hidden or obscured by other structures in the image. A tilt pair of micrographs with subsequent stereoscopic viewing can be an important aid in three-dimensional visualization of these images, once an appropriate stain has been found. The peroxidase reaction has been used for this purpose in visualizing the T-system (transverse tubular system) of frog skeletal muscle by HVEM (1). We have found infiltration with lanthanum hydroxide to be particularly useful for three-dimensional visualization of certain aspects of the structure of the T- system in skeletal muscles of the frog. Specifically, lanthanum more completely fills the lumen of the tubules and is denser than the peroxidase reaction product.


Author(s):  
L. E. Thomas ◽  
J. S. Lally ◽  
R. M. Fisher

In addition to improved penetration at high voltage, the characteristics of HVEM images of crystalline materials are changed markedly as a result of many-beam excitation effects. This leads to changes in optimum imaging conditions for dislocations, planar faults, precipitates and other features.Resolution - Because of longer focal lengths and correspondingly larger aberrations, the usual instrument resolution parameter, CS174 λ 374 changes by only a factor of 2 from 100 kV to 1 MV. Since 90% of this change occurs below 500 kV any improvement in “classical” resolution in the MVEM is insignificant. However, as is widely recognized, an improvement in resolution for “thick” specimens (i.e. more than 1000 Å) due to reduced chromatic aberration is very large.


Author(s):  
T. Mukai ◽  
T. E. Mitchell

Radiation-induced homogeneous precipitation in Ni-Be alloys was recently observed by high voltage electron microscopy. A coupling of interstitial flux with solute Be atoms is responsible for the precipitation. The present investigation further shows that precipitation is also induced at thin foil surfaces by electron irradiation under a high vacuum.


Author(s):  
J. S. Lally ◽  
R. Evans

One of the instrumental factors often limiting the resolution of the electron microscope is image defocussing due to changes in accelerating voltage or objective lens current. This factor is particularly important in high voltage electron microscopes both because of the higher voltages and lens currents required but also because of the inherently longer focal lengths, i.e. 6 mm in contrast to 1.5-2.2 mm for modern short focal length objectives.The usual practice in commercial electron microscopes is to design separately stabilized accelerating voltage and lens supplies. In this case chromatic aberration in the image is caused by the random and independent fluctuations of both the high voltage and objective lens current.


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