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Wang X.-S.,Henan Polytechnic University | Wang X.-S.,Tsinghua University | Wang X.-S.,Huadong Institute of Lithium Ion Battery | Cui S.-W.,Hebei Normal University | And 4 more authors.
Journal of Adhesion Science and Technology | Year: 2014

Using Gibbs method of dividing surfaces, the contact angle of a drop on a flat homogeneous rough non-deformable solid substrate is investigated. For this system, a new generalized Youngs equation for the contact angle, including the influences of line tension and which valid for any dividing surface between liquid phase and vapor phase is derived. Under some assumptions, this generalized Youngs equation reduces to the Wenzels equation or Rosanovs equation valid for the surface of tension. © 2013 © 2013 Taylor & Francis. Source


Cao J.,University of South China | Cao J.,Tsinghua University | Wang L.,Tsinghua University | Shang Y.,Tsinghua University | And 8 more authors.
Electrochimica Acta | Year: 2013

The presented contribution aims at investigating the role of nano-TiO 2 dispersibility in affecting the performance of PVDF-HFP based composite polymer electrolytes (CPEs) for Li-ion cells. Four types of polymer electrolytes containing pristine PVDF-HFP gel polymer electrolyte (GPE), PVDF-HFP/nano-TiO2 CPE, PVDF-HFP/nano-TiO2-PMMA CPE and PVDF-HFP/high-dispersed nano-TiO2-PMMA CPE membranes are obtained by phase inversion. The effect of nano-TiO2 dispersibility on performances of PVDF-HFP based CPEs in terms of ionic conductivity, C-rate and cycling performance is investigated. The results demonstrate that the dispersibility of nano-TiO2 is a key factor to affect the performance of PVDF-HFP based CPEs, and the improvement of the dispersibility of nano-TiO2 can remarkably enhance the electrochemical performances of cells assembled with the corresponding CPEs. © 2013 Elsevier Ltd. All rights reserved. Source


Jin Y.,Tsinghua University | Wang L.,Tsinghua University | Shang Y.,Tsinghua University | Gao J.,Tsinghua University | And 3 more authors.
Electrochimica Acta | Year: 2015

The monodisperse Co3O4 mesoporous microdisks have been successfully prepared through a facile solvothermal synthesis method and subsequent heating treatment. The Co3O4 microdisks are polycrystalline, and have an average diameter of around 2 μm with an thickness of 300 nm. The specific surface area of Co3O4 mesoporous microdisks is about 108.9 m2 g-1 with a narrow pore size distribution centered at round 9.68 nm. The as-prepared Co3O4 mesoporous microdisks as anode material in lithium ion batteries exhibit a stable specific discharge-charge capacity of 765 and 749 mAh g-1 after 30 cycles at a current density of 100 mA g-1. The good electrochemical properties could be attributed to the unique mesoporous structure of Co3O4 materials. © 2014 Elsevier Ltd. All rights reserved. Source


Hu A.-J.,Henan Polytechnic University | Wang X.-S.,Henan Polytechnic University | Wang X.-S.,Huadong Institute of Lithium Ion Battery | Lv B.-Z.,Henan Polytechnic University
Journal of Computational and Theoretical Nanoscience | Year: 2015

Using Gibbs method of dividing surfaces, wetting of a nanodroplet on homogeneous and spherical smooth solid substrate is investigated. For this solid-liquid-vapor system, a new generalized Young's equation for the contact angle of nanodroplet on homogeneous spherical solid substrate including the influences of line tension is derived. Under some assumptions, this generalized Young's equation reduces to the Rusanov's equation. © 2015 American Scientific Publishers. Source


Yang J.,Tsinghua University | Zhao P.,Tsinghua University | Shang Y.,Tsinghua University | Shang Y.,Huadong Institute of Lithium Ion Battery | And 5 more authors.
Electrochimica Acta | Year: 2014

N,N′-4,4′-diphenylmethane-bismaleimide (BMI) is attempted to enhance the high-voltage performance for lithium-ion batteries. When 0.1% (m/v) BMI is added into the control electrolyte, the high-voltage cycling performance of LiCoO2/Li cells is improved evidently while charging the cell up to 4.5 V rather than the conventional 4.2 V. Analysis of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) demonstrate that an interface film forms on the cathode surface from BMI in electrolyte. AC impedance spectra and charge/discharge test were tested after incubation of the charged cell at 60 C. Linear sweep voltammetry (LSV) is used to test the electrochemical stability window of the electrolyte with BMI addition. The results demonstrate that the improvement of high-voltage performance is attributed to the surface film on cathode. In addition, the BMI addition does not cause damage in conventional performance with 4.2 V electrochemical window. The BMI-containing electrolyte provides high-voltage cycling performance with 4.5 V electrochemical window, making LiCoO2 battery a simple and promising system for applications with high energy density. © 2014 Elsevier Ltd. Source

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