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  • 1
    Online Resource
    Online Resource
    Formation of oxygen vacancy clusters in Li-rich Mn-based cathode Materials of lithium-ion batteries: First-principles calculations
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2023
    In:  Acta Physica Sinica Vol. 72, No. 7 ( 2023), p. 078201-
    Details
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 72, No. 7 ( 2023), p. 078201-
    Abstract: Using the first-principles method, the formation energy values of O-vacancy clusters of two Li-rich Mn-based ternary cathode materials of lithium ion battery with different amounts of nickel , i.e. Li〈sub〉1.2〈/sub〉Ni〈sub〉0.32〈/sub〉Co〈sub〉0.04〈/sub〉Mn〈sub〉0.44〈/sub〉O〈sub〉2〈/sub〉 (space group 〈inline-formula〉〈tex-math id="M2"〉\begin{document}$R\bar{3}m)$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="7-20222300_M2.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="7-20222300_M2.png"/〉〈/alternatives〉〈/inline-formula〉 and Li〈sub〉1.167〈/sub〉Ni〈sub〉0.167〈/sub〉Co〈sub〉0.167〈/sub〉Mn〈sub〉0.5〈/sub〉O〈sub〉2〈/sub〉 (space group 〈i〉C〈/i〉2/〈i〉m〈/i〉), are calculated. Results show that the formation energy of oxygen vacancy cluster of the material with less nickel content Li〈sub〉1.167〈/sub〉Ni〈sub〉0.167〈/sub〉Co〈sub〉0.167〈/sub〉Mn〈sub〉0.5〈/sub〉O〈sub〉2〈/sub〉 can be always higher than that of the material Li〈sub〉1.2〈/sub〉Ni〈sub〉0.32〈/sub〉Co〈sub〉0.04〈/sub〉Mn〈sub〉0.44〈/sub〉O〈sub〉2〈/sub〉 with higher nickel content. This indicates that the oxygen vacancy clusters are more likely to form in cathode material with higher nickel content. The formation energy of the oxygen vacancy cluster near the transition metal is always greater than that near the lithium ion, indicating that the removal of oxygen tends to occur near the Li ion. Lower temperature and higher partial pressure can increase the formation energy of oxygen vacancy cluster, and therefore inhibit the formation of oxygen vacancy cluster. In addition, the formation energy values of oxygen vacancy clusters with the transition metals in the materials replaced by other transition metals (i.e., Ti and Mo) are also calculated. The results show that, in addition to the case of Ni replaced by Ti near the double oxygen vacancies near the Li-ion in Li〈sub〉1.2〈/sub〉Ni〈sub〉0.32〈/sub〉Co〈sub〉0.04〈/sub〉Mn〈sub〉0.44〈/sub〉O〈sub〉2〈/sub〉, all the remaining cases of the transition metals Ni or Mn replaced by Ti or Mo always increase the formation energy of the O-vacancy cluster. Therefore, the doping should be able to inhibit the loss of oxygen and improve the structural stability of material.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    URL: Article
    DOI: 10.7498/aps.72.20222300
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2023
    Location Call Number Limitation Availability
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    Online Resource
  • 2
    Online Resource
    Online Resource
    Regulation and mechanism of graphene electrode bending on negative differential resistance of 2-phenylpyridine molecular devices
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2023
    In:  Acta Physica Sinica Vol. 72, No. 3 ( 2023), p. 038502-
    Details
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 72, No. 3 ( 2023), p. 038502-
    Abstract: Combining non-equilibrium Green’s function with density functional theory, we study the electronic transport properties of the molecular devices comprised of 2-phenylpyridine and zigzag graphene nanoribbon (ZGNR) electrodes. The 〈i〉I-V〈/i〉 characteristics and transmission coefficients under external voltage biases are analyzed, and the results show that the negative differential resistance (NDR) is effectively adjusted by the bending of ZGNR electrode, which reduces the peak voltage (〈i〉V〈/i〉〈sub〉p〈/sub〉) and increases the peak-valley ratio (PVR) of the device. When the electrode bending angle is 15°, the PVR of device M2 is a maximum value of 12.84 and 〈i〉V〈/i〉〈sub〉p〈/sub〉 is 0.1 V, which is low enough for practical applications. The transmission spectra, the density of states and the real-space scattering state distribution at 〈i〉E〈/i〉〈sub〉f 〈/sub〉 of device under zero bias explain that the weaker coupling between the molecules and the electrodes is caused by the bending of the ZGNR electrode, which might be responsible for the adjustability of NDR. The analysis shows that the bending of the electrode changes the electronic structure between the 2-phenylpyridine molecule and the ZGNR electrode, and then changes the wave functions overlap between them, the coupling between the molecule and the electrodes gets weaker. An external bias can induce the level to shift. The transmission coefficient for the weaker coupling between the molecules. The electrodes can fluctuate wildly from level to level, and large NDR effect under very low bias is obtained with the variation of external bias. Therefore, for highly symmetric molecular devices, the electronic transport properties can be effectively adjusted by changing the coupling between the central molecule and the electrodes. Our investigations indicate that the 2-phenylpyridine molecular device with ZGNR electrodes may have potential applications in the field of low-power dissipation molecules device.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    URL: Article
    DOI: 10.7498/aps.72.20221212
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2023
    Location Call Number Limitation Availability
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    Online Resource
  • 3
    Online Resource
    Online Resource
    Electronic structures and molecular doping of germanane regulated by hydrogen vacancy clusters
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2023
    In:  Acta Physica Sinica Vol. 72, No. 12 ( 2023), p. 127101-
    Details
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 72, No. 12 ( 2023), p. 127101-
    Abstract: Germanane is expected to substitute for existing silicon-based or germanium-based material. Germanane is regarded as an ideal candidate for next-generation semiconductor material due to its suitable band gap, high electron mobility, better environmental stability, small electrical noise and ultrathin geometry. In this work, the effects of different configuration and concentration of hydrogen vacancy cluster on the electronic properties of germanane and its molecular doping are systematically investigated through the first-principles method based on density functional theory and none-quilibrium Green’s function. The results show that the hydrogen vacancy clusters with different configurations can induce magnetism with different characteristics in Germanane〈sub〉Dehydrogenated-〈i〉x〈/i〉H〈/sub〉 (G〈sub〉D-〈i〉x〈/i〉H〈/sub〉) system, and the magnetic moments are consistent with the predictions of Lieb’s theorem. Moreover, the p-type-liked doping effects caused by defective state under G〈sub〉D-〈i〉x〈/i〉H〈/sub〉 (〈i〉x〈/i〉 = 1, 4, 6) systems can be realized in their spin-down band structures. The corresponding energy values for exciting electron would gradually decrease with the increase of the concentration of hydrogen vacancy clusters under different configurations. After adsorbing tetrathiafulvalene (TTF) molecules, G/TTF and G〈sub〉D-〈i〉x〈/i〉H〈/sub〉/TTF (〈i〉x〈/i〉 = 1, 2, 6) systems exhibit molecular doping characteristics induced by the TTF molecules. More importantly, for G〈sub〉D-〈i〉x〈/i〉H〈/sub〉/TTF (〈i〉x〈/i〉 = 1, 6) system, the different molecular doping types can be introduced in spin-up and spin-down band structures due to the hybridization composed of molecular orbitals and defective states under spin polarization. Further calculations of their transport properties indicate that germanane-based device with Armchair and Zigzag configurations both exhibit intensive isotropy, and the performance of 〈i〉I-V〈/i〉 characteristics can be dramatically enhanced owing to the carrier doping by TTF adsorption.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    URL: Article
    DOI: 10.7498/aps.72.20230170
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2023
    Location Call Number Limitation Availability
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    Online Resource
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