Zr0.5Ti0.5O2(ZT) and Zr0.25Ti0.25Al0.5O2(ZTA) mixed oxides were prepared by co-precipitation method and characterized by low temperature adsorption-desorption,XRD and NH3-TPD. The activity of Pt/Zr0.5Ti0.5O2 and Pt/ Z...Zr0.5Ti0.5O2(ZT) and Zr0.25Ti0.25Al0.5O2(ZTA) mixed oxides were prepared by co-precipitation method and characterized by low temperature adsorption-desorption,XRD and NH3-TPD. The activity of Pt/Zr0.5Ti0.5O2 and Pt/ Zr0.5Ti0.5Al0.5O2 catalysts was evaluated using the simulated gases. The results show that ZTA samples exhibit higher specific surface area,larger pore volume and proper surface acidic amount and acidity in comparison with ZT. The results of the catalytic test indicate that Pt/ZT and Pt/ZTA catalysts exhibit excellent low-temperature catalytic activity and lower light-off temperatures of hydrocarbon,carbon monoxide and nitrogen oxides,especially better conversion for nitrogen oxides (NOx). The addition of Al2O3 into ZT enhanced the anti-aging property of Pt/ ZTA catalysts due to the excellent textural,structural,surface acidity and thermal stability.展开更多
采用两步干混-球磨方法制备了石墨烯掺杂改性的锂离子电池LiFePO_4/LiNi_(0.8)Co_(0.15)Al_(0.05)O_2复合正极材料,实现LiNi_(0.8)Co_(0.15)Al_(0.05)O_2材料的高容量和高安全性。借助X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、X...采用两步干混-球磨方法制备了石墨烯掺杂改性的锂离子电池LiFePO_4/LiNi_(0.8)Co_(0.15)Al_(0.05)O_2复合正极材料,实现LiNi_(0.8)Co_(0.15)Al_(0.05)O_2材料的高容量和高安全性。借助X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、X射线光电子能谱(XPS)以及电化学测试等表征手段对材料的晶体结构、微观形貌和电化学性能进行了较系统的研究。结果表明,石墨烯的存在实现了Li Fe PO4材料在LiNi_(0.8)Co_(0.15)Al_(0.05)O_2材料表面的完全包覆,形成致密的包覆层,进一步抑制LiNi_(0.8)Co_(0.15)Al_(0.05)O_2与电解液之间的副反应,提高活性材料利用率和循环性能。三者之间构成导电网络,加快电子渗透和传输,提高倍率性能。Li Fe PO4质量分数为20%的Li Fe PO4-Graphene/LiNi_(0.8)Co_(0.15)Al_(0.05)O_2样品具有最佳的容量性能和长循环性能,0.1C时放电容量达到202.5 m Ah·g^(-1),3C时放电容量仍然可保持在160.5 m Ah·g^(-1)。50℃在2.8~4.3 V,0.5C下循环100次后,容量保持率为91.9%,优于LiNi_(0.8)Co_(0.15)Al_(0.05)O_2和LiFePO_4/LiNi_(0.8)Co_(0.15)Al_(0.05)O_2样品的72.9%和82.0%。展开更多
用硅烷偶联剂加热分解的简便方法对锂离子电池正极材料LiNi_(0.8)Co_(0.15)Al_(0.05)O_2(NCA)的表面进行处理,利用XRD结合Rietveld精修、SEM、TEM、DSC、EIS和恒流充放电等方法对材料进行表征。结果显示,硅烷偶联剂经450℃加热分解后得...用硅烷偶联剂加热分解的简便方法对锂离子电池正极材料LiNi_(0.8)Co_(0.15)Al_(0.05)O_2(NCA)的表面进行处理,利用XRD结合Rietveld精修、SEM、TEM、DSC、EIS和恒流充放电等方法对材料进行表征。结果显示,硅烷偶联剂经450℃加热分解后得到的非晶态Si O2均匀包覆在材料表面,包覆不改变NCA的晶体结构,但明显改善了材料性能。在60℃环境中,0.2C、1C下包覆材料(简写为a-NCA)的放电比容量分别为176.4、158.9 m Ah·g-1,高于NCA的174.2、153.8 m Ah·g-1;50周循环后a-NCA的容量保持率为91.4%,远高于NCA的86.5%;同时,经包覆后材料的热稳定性大幅度提高。其原因是包覆层抑制了NCA在循环过程中与电解液发生副反应,有效降低了离子迁移的界面膜电阻,并抑制了晶体结构变化。展开更多
文摘Zr0.5Ti0.5O2(ZT) and Zr0.25Ti0.25Al0.5O2(ZTA) mixed oxides were prepared by co-precipitation method and characterized by low temperature adsorption-desorption,XRD and NH3-TPD. The activity of Pt/Zr0.5Ti0.5O2 and Pt/ Zr0.5Ti0.5Al0.5O2 catalysts was evaluated using the simulated gases. The results show that ZTA samples exhibit higher specific surface area,larger pore volume and proper surface acidic amount and acidity in comparison with ZT. The results of the catalytic test indicate that Pt/ZT and Pt/ZTA catalysts exhibit excellent low-temperature catalytic activity and lower light-off temperatures of hydrocarbon,carbon monoxide and nitrogen oxides,especially better conversion for nitrogen oxides (NOx). The addition of Al2O3 into ZT enhanced the anti-aging property of Pt/ ZTA catalysts due to the excellent textural,structural,surface acidity and thermal stability.
文摘采用两步干混-球磨方法制备了石墨烯掺杂改性的锂离子电池LiFePO_4/LiNi_(0.8)Co_(0.15)Al_(0.05)O_2复合正极材料,实现LiNi_(0.8)Co_(0.15)Al_(0.05)O_2材料的高容量和高安全性。借助X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、X射线光电子能谱(XPS)以及电化学测试等表征手段对材料的晶体结构、微观形貌和电化学性能进行了较系统的研究。结果表明,石墨烯的存在实现了Li Fe PO4材料在LiNi_(0.8)Co_(0.15)Al_(0.05)O_2材料表面的完全包覆,形成致密的包覆层,进一步抑制LiNi_(0.8)Co_(0.15)Al_(0.05)O_2与电解液之间的副反应,提高活性材料利用率和循环性能。三者之间构成导电网络,加快电子渗透和传输,提高倍率性能。Li Fe PO4质量分数为20%的Li Fe PO4-Graphene/LiNi_(0.8)Co_(0.15)Al_(0.05)O_2样品具有最佳的容量性能和长循环性能,0.1C时放电容量达到202.5 m Ah·g^(-1),3C时放电容量仍然可保持在160.5 m Ah·g^(-1)。50℃在2.8~4.3 V,0.5C下循环100次后,容量保持率为91.9%,优于LiNi_(0.8)Co_(0.15)Al_(0.05)O_2和LiFePO_4/LiNi_(0.8)Co_(0.15)Al_(0.05)O_2样品的72.9%和82.0%。
文摘用硅烷偶联剂加热分解的简便方法对锂离子电池正极材料LiNi_(0.8)Co_(0.15)Al_(0.05)O_2(NCA)的表面进行处理,利用XRD结合Rietveld精修、SEM、TEM、DSC、EIS和恒流充放电等方法对材料进行表征。结果显示,硅烷偶联剂经450℃加热分解后得到的非晶态Si O2均匀包覆在材料表面,包覆不改变NCA的晶体结构,但明显改善了材料性能。在60℃环境中,0.2C、1C下包覆材料(简写为a-NCA)的放电比容量分别为176.4、158.9 m Ah·g-1,高于NCA的174.2、153.8 m Ah·g-1;50周循环后a-NCA的容量保持率为91.4%,远高于NCA的86.5%;同时,经包覆后材料的热稳定性大幅度提高。其原因是包覆层抑制了NCA在循环过程中与电解液发生副反应,有效降低了离子迁移的界面膜电阻,并抑制了晶体结构变化。
