نتایج جستجو برای: cathode material
تعداد نتایج: 376491 فیلتر نتایج به سال:
Lithium-ion secondary batteries (LIBs) store electric energy via Li+ deintercalation from cathode materials. The Li+ deintercalation frequently drives a first-order phase transition of the cathode material as a result of the Li-ordering or Li-concentration effect and causes a phase separation (PS) into the Li-rich and Li-poor phases. Here, we performed an in situ microscopic investigation of th...
Micro-electrical discharge machining is an evolution of conventional EDM used for fabricating three-dimensional complex micro-components and microstructures with high precision capabilities. The material removal process has stochastic nature and is still not fully understood. This paper presents experimental results on observing the material removal rate (MRR) in dependence of alternating machi...
Utilization of LiFePO4 as a cathode material for Li-ion batteries often requires size nanonization coupled with calcination-based carbon coating to improve its electrochemical performance, which, however, is usually at the expense of tap density and may be environmentally problematic. Here we report the utilization of micron-sized LiFePO4, which has a higher tap density than its nano-sized sibl...
The key properties of a successful cathode material, such as the structural stability during delithiation, the battery voltage, and the Li mobility, were investigated for Al-doped Li–Mn–Ni oxide structures, using density-functional theory and the nudged-elastic band method. The rhombohedral layered structure of LiMn0.5Ni0.5O2 with zigzag and flower arrangements of transition metal atoms as well...
Through first-principles computations, we investigated Li4NiTeO6, which is a new layered Ni-based cathode material for Li ion batteries, by focusing on the sequence of Li removal when it is charged. According to our computations, Li4NiTeO6 exhibits satisfactory structural stability with a volume change of 7.2% and electrical conductivity similar to Li2MnO3. We also examined the electronic confi...
A charge of 2.3 × 1011 electrons in 2.5 ns at a laser wavelength of 757 nm with a corresponding quantum efficiency (QE) of 2.0% measured at 752 nm was extracted from a −120 kV biased, 20 mm diameter, GaAs–AlGaAs superlattice photocathode. The maximum electron polarization measured with material from the same wafer, but in a different system, was 71% at 757 nm for a QE of 1.0% measured at 752 nm...
The benefit of LiFePO4 as a cathode material in rechargeable batteries has sparked considerable research interest. The 2015 Research Experience for Undergraduates (REU) in Physics at Howard University provided an opportunity to examine the electrical conductivity of carbon-coated LiFePO4.4-Point Probe resistivity testing shows that the cathode has an electrical conductivity value of σ=1.45 x 10...
The performance of Cell-Batt Li-ion cells and Sony 18650 cells using non-stoichiometric spinel and LiCoO2, respectively, as positive electrode material has been studied under several modes of charging. During cycling, the cells were opened at intermittent cycles and extensive material and electrochemical characterization was done on the active material at both electrodes. Capacity fade of spine...
Sulfur is an exciting cathode material with high specific capacity of 1,673 mAh/g, more than five times the theoretical limits of its transition metal oxides counterpart. However, successful applications of sulfur cathode have been impeded by rapid capacity fading caused by multiple mechanisms, including large volume expansion during lithiation, dissolution of intermediate polysulfides, and low...
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