The three-dimensional porous network polytetrafluoroethylene （PTFE） thin films were achieved by a vacuum technique through evaporating the pure PTFE powders. The surfaces of PTFE thin films showed various morphologi...The three-dimensional porous network polytetrafluoroethylene （PTFE） thin films were achieved by a vacuum technique through evaporating the pure PTFE powders. The surfaces of PTFE thin films showed various morphologies by adjusting the evaporation temperature and the corresponding contact angle ranging from 133° to 155°. Further analyses of surface chemical composition and morphology by FTIR and FE-SEM revealed that the origin of hydrophobicity for the PTFE thin films could be ascribed to the fluorine-containing groups and the surface morphologies, indicating that abundant -CF2 groups and network structures with appropriate pore sizes played a vital role in superhydrophobicity. By characterization of UV-Vis, the films also showed high transmittance and antireflection effect. The films prepared by this simple method have potential applications such as waterproof membrane and self-cleaning coating.展开更多
Si@SiO_(x)/C复合负极具有较高比容量,被认为是锂离子电池实际工业应用中最有前途的负极材料.然而,由于硅的严重体积形变,复合负极的循环稳定性依然面临巨大挑战.本工作通过释放负极冗余容量中高度可逆的锂储存能力,提高了复合负极的循...Si@SiO_(x)/C复合负极具有较高比容量,被认为是锂离子电池实际工业应用中最有前途的负极材料.然而,由于硅的严重体积形变,复合负极的循环稳定性依然面临巨大挑战.本工作通过释放负极冗余容量中高度可逆的锂储存能力,提高了复合负极的循环稳定性.基于LiF与不同活性材料之间的界面分离能差,我们针对复合负极提出了一种LiF引发的选择性锂化策略.LiF在Si@SiO_(x)上发生再沉积并富集,分离LiC_(x)和Li_(15)Si_(4)的形成电位,进而促进锂离子在石墨中的存储(未修饰前复合负极中石墨的容量未被充分利用).因此,在不牺牲比容量的前提下,全电池获得了更好的倍率性能和循环性能.超高面容量(NCA/S450,4.9 mA h cm^(-2))的全电池经300次循环后,容量保持率从66.1%显著提高到94.2%.选择性锂化策略在实际工业应用中更加可行,不需要改变现有的电池制造工艺.本研究为长循环寿命硅/石墨复合负极的开发开辟了新途径.展开更多
基金This study was financially supported by the high-tech project of MOST （Grant No. 2014AA032802） and the national sci-tech support plan of the National Natural Science Foundation of China （NSFC Grant Nos. 51272273 and 51272271）.
文摘The three-dimensional porous network polytetrafluoroethylene （PTFE） thin films were achieved by a vacuum technique through evaporating the pure PTFE powders. The surfaces of PTFE thin films showed various morphologies by adjusting the evaporation temperature and the corresponding contact angle ranging from 133° to 155°. Further analyses of surface chemical composition and morphology by FTIR and FE-SEM revealed that the origin of hydrophobicity for the PTFE thin films could be ascribed to the fluorine-containing groups and the surface morphologies, indicating that abundant -CF2 groups and network structures with appropriate pore sizes played a vital role in superhydrophobicity. By characterization of UV-Vis, the films also showed high transmittance and antireflection effect. The films prepared by this simple method have potential applications such as waterproof membrane and self-cleaning coating.
基金supported by the Key-Area Research and Development Program of Guangdong Province(2020B090919005)the National Key R&D Program of China(2017YFE0127600)+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA22010600)Taishan Scholars Program for Young Expert of Shandong Province(tsqn 202103145)the National Natural Science Foundation of China(22179135)the Finance Science and Technology Project of Hainan province(ZDKJ202014)。
文摘Si@SiO_(x)/C复合负极具有较高比容量,被认为是锂离子电池实际工业应用中最有前途的负极材料.然而,由于硅的严重体积形变,复合负极的循环稳定性依然面临巨大挑战.本工作通过释放负极冗余容量中高度可逆的锂储存能力,提高了复合负极的循环稳定性.基于LiF与不同活性材料之间的界面分离能差,我们针对复合负极提出了一种LiF引发的选择性锂化策略.LiF在Si@SiO_(x)上发生再沉积并富集,分离LiC_(x)和Li_(15)Si_(4)的形成电位,进而促进锂离子在石墨中的存储(未修饰前复合负极中石墨的容量未被充分利用).因此,在不牺牲比容量的前提下,全电池获得了更好的倍率性能和循环性能.超高面容量(NCA/S450,4.9 mA h cm^(-2))的全电池经300次循环后,容量保持率从66.1%显著提高到94.2%.选择性锂化策略在实际工业应用中更加可行,不需要改变现有的电池制造工艺.本研究为长循环寿命硅/石墨复合负极的开发开辟了新途径.
