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High-voltage spinel LiNi0.5Mn1.5O4 has been considered one of the most promising cathode materials for lithium-ion power batteries used in electrical vehicles (EVs) or hybrid electrical vehicles (HEVs) because the high voltage plateau at around 4.7 V makes its energy density (658 Wh kg?1) 30 and 25 % higher than that of conventional pristine spinel LiMn2O4 (440 Wh kg?1) or olivine LiFePO4 (500 Wh kg?1) materials, respectively. Unfortunately, LiNi0.5Mn1.5O4-based batteries with LiPF6-based carbonate electrolytes always suffer from severe capacity deterioration and poor thermostability because of the oxidization of organic carbonate solvents and decomposition of LiPF6, especially at elevated temperatures and water-containing environment. The major goal of this review is to highlight the recent advancements in the development of advanced electrolytes for improving the cycling stability and rate capacity of LiNi0.5Mn1.5O4-based batteries. Finally, an insight into the future research and further development of advanced electrolytes for LiNi0.5Mn1.5O4-based batteries is discussed. 相似文献
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使用基于密度泛函微扰理论的线性响应方法, 模拟研究了强激光辐照对闪锌矿结构的碳化硅晶体结构稳定性的影响. 通过计算在不同电子温度下3C-SiC晶体的声子色散曲线, 发现3C-SiC的横声学声子频率随电子温度的升高会出现虚频, 其临界电子温度是3.395 eV. 结果表明, 在强激光辐照下3C-SiC 晶体变得不稳定, 这与以前对金刚石结构的碳、硅和闪锌矿结构的砷化镓、锑化铟的研究结果非常类似. 电子温度在0–4.50 eV 范围内时, 3C-SiC晶体在Γ 点的LO-TO分裂度随电子温度的升高而增大, 超过4.50 eV后随电子温度的升高而减小. 这表明只有在足够强的激光辐照下, 电子激发才会削弱晶体的离子性强度. 相似文献
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Message passing algorithms, whose iterative nature captures complicated interactions among interconnected variables in complex systems and extracts information from the fixed point of iterated messages, provide a powerful toolkit in tackling hard computational tasks in optimization, inference, and learning problems. In the context of constraint satisfaction problems (CSPs), when a control parameter (such as constraint density) is tuned, multiple threshold phenomena emerge, signaling fundamental structural transitions in their solution space. Finding solutions around these transition points is exceedingly challenging for algorithm design, where message passing algorithms suffer from a large message fluctuation far from convergence. Here we introduce a residual-based updating step into message passing algorithms, in which messages with large variation between consecutive steps are given high priority in the updating process. For the specific example of model RB (revised B), a typical prototype of random CSPs with growing domains, we show that our algorithm improves the convergence of message updating and increases the success probability in finding solutions around the satisfiability threshold with a low computational cost. Our approach to message passing algorithms should be of value for exploring their power in developing algorithms to find ground-state solutions and understand the detailed structure of solution space of hard optimization problems. 相似文献
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Compression of the self-Q-switching in semiconductor disk lasers with single-layer graphene saturable absorbers 下载免费PDF全文
We demonstrate the first use of single layer graphene for compressing self-Q-switching pulses in semiconductor disk lasers. The gain region of the semiconductor disk laser used InGaAs quantum wells with a central wavelength of 1030 nm. Due to self saturable absorption of the quantum wells, the disk laser emitted at the self-Q-switching state with a pulse width of 13 μs. By introducing the single layer graphene as a saturable absorber into the V-shaped laser cavity, the pulse width of the self-pulse was compressed to 2 μs with a lower pump power of 300 mW. As the pump power was increased, multiple pulses with the pulse width of 1.8 μs appeared. The compression factor was about 7.2. 相似文献
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Recovery phenomenon is observed under negative gate voltage stress which is smaller than the previous degradation stress. We focus on the drain current to study the degradation and recovery of negative bias temperature instability (NBTI) with a real-time method. By this method, different recovery phenomena among different size devices are observed. Under negative recovery stress, the drain current gradually recovers for the large size devices and gets into recovery saturation when long recovery time is involved. For small-size devices, a step-like recovery of drain current is observed. The recovery of the drain current is mainly caused by the holes detrapping and tunnelling back to the channel surface which are trapped in oxide. The model of hole detrapping explains the recovery under negative voltage stress reasonably. 相似文献
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Zhang Qi Zhai Jian-Jun Zhang Yan-Rong Liu Ying-Mei Wang Liu-Fang Li Shu-Ben Liao Dai-Zheng Wang Geng-Lin 《Transition Metal Chemistry》2000,25(1):93-98
Six transition metal(II) complexes with 8-acetyl-4-methyl umbelliferone (AMUH), ML2 (L=AMU–; M=Mn, Co, Ni, Cu, Zn and Cd), have been synthesized and characterized by elemental analysis, electrical conductance, i.r., 1H-n.m.r. and u.v. spectroscopic techniques. The e.s.r. spectra show that CuL2 is anisotropic, with g2.05 and g2.26. The MnL2 species is characterized by a very broad g2 centered resonance without manganese hyperfine structure. The antioxidative and other biological activities of selected complexes were also investigated, indicating that both the ligand and complexes exhibit a scavenging effect on the superoxide radical (O2
–·) and a suppressing effect on the hydroxyl radical (·OH). The suppressing effect on ·OH is greater than the scavenging effect on O2
–·. The Cu and Mn complexes exhibit very significant suppression ratios for both radicals. However, the inhibitory effect on lipid peroxides results show that, in the initial stage, the Cu and Mn complexes exhibit obvious inhibitory effects on lipid peroxides, but after one hour, they begin to accelerate the lipid peroxides. Lower catalytic activity and instability when the complexes react with active oxygen may be responsible for this dual nature. The ligand and four transition metal(II) complexes selectively, obviously, inhibit the growth of HCT-8 and HL-60 tumour cell lines. They also exhibit a minor influence on the proliferation of B cells in higher concentration (10–5m), but only a weak effect on the proliferation of T cells of the BALB/C (nude rate) spleen cells. 相似文献
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用经典辐射理论对线偏振周期量级激光脉冲的线性Thomson散射进行分析,从理论上得到它可产生亚阿秒脉冲的结论. 计算显示,在电子相对论因子为50、激光脉冲中心波长为1μm、归一化光场强度为0.01的情况下,用包含1.5个光周期的激光脉冲,可获得0.2as(半高全宽)的散射脉冲输出. 还对光场载波包络初相φce和电子进入光场的初相φin对散射脉冲的影响作了分析讨论,结果表明,在适当的φce和φin条件下,能实现单个阿秒脉冲输出,并可对脉冲宽度和频率进行调谐.
关键词:
线性Thomson散射
周期量级激光脉冲
载波包络初相
阿秒脉冲 相似文献