Samples of LiNi0.95-xCoxAl0.05O2 （x = 0.10 and 0.15） and LiNiO2, synthesized by the solid-state reaction at 725℃ for 24 h from LiOH-H2O, Ni2O3, Co2O3, and AI（OH）3 under an oxygen stream, were characterized by TG-...Samples of LiNi0.95-xCoxAl0.05O2 （x = 0.10 and 0.15） and LiNiO2, synthesized by the solid-state reaction at 725℃ for 24 h from LiOH-H2O, Ni2O3, Co2O3, and AI（OH）3 under an oxygen stream, were characterized by TG-DTA, XRD, SEM, and electrochemical tests. Simultaneous doping of cobalt and aluminum at the Ni-site in LiNiO2 was tried to improve the cathode performance for lithium-ion batteries. The results showed that co-doping （especially, 5 at.% A1 and 10 at.% Co） definitely had a large beneficial effect in increasing the capacity （186.2 mA.h/g of the first discharge capacity for LiNio.s.42OoaoAlo.0502） and cycling behavior （180.1 mA-h/g after 10 cycles for LiNio.85CooaoAlo.osO2） compared with 180.7 mA.h/g of the first discharge capacity and 157.7 mA.h/g of the tenth discharge capacity for LiNiO2, respectively. Differen- tial capacity versus voltage curves showed that the co-doped LiNio.95_xCoxmlo.osO2 had less intensity of the phase transitions than the pristine LiNiO2.展开更多
Samples of LiNi0.95-xCoxAl0.05O2（x=0.10 and 0.15） and LiNiO2,synthesized by the solid-state reaction at 725?℃ for 24?h from LiOH·H2O,Ni2O3,Co2O3,and Al（OH）3 under an oxygen stream,were characterized by TG-DT...Samples of LiNi0.95-xCoxAl0.05O2（x=0.10 and 0.15） and LiNiO2,synthesized by the solid-state reaction at 725?℃ for 24?h from LiOH·H2O,Ni2O3,Co2O3,and Al（OH）3 under an oxygen stream,were characterized by TG-DTA,XRD,SEM,and electrochemical tests. Simultaneous doping of cobalt and aluminum at the Ni-site in LiNiO2 was tried to improve the cathode performance for lithium-ion batteries. The results showed that co-doping （especially,5% Al and 10% Co in atomic fraction） definitely had a large beneficial effect in increasing the capacity （186.2?mA·h/g of the first discharge capacity for LiNi 0.85 Co 0.1 0Al 0.05 O2） and cycling behavior (180.1?mA·h/g after 10 cycles for LiNi0.95-xCoxAl0.05O2) compared with 180.7?mA·h/g of the first discharge capacity and 157.7?mA·h/g of the tenth discharge capacity for LiNiO2,respectively. Differential capacity versus voltage curves showed that the co-doped LiNi0.95-xCoxAl0.05O2 had less intensity of the phase transitions than the pristine LiNiO2.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
基金The project is financially supported by the National Natural Science Foundation of China (No. 20371038).
文摘Samples of LiNi0.95-xCoxAl0.05O2 （x = 0.10 and 0.15） and LiNiO2, synthesized by the solid-state reaction at 725℃ for 24 h from LiOH-H2O, Ni2O3, Co2O3, and AI（OH）3 under an oxygen stream, were characterized by TG-DTA, XRD, SEM, and electrochemical tests. Simultaneous doping of cobalt and aluminum at the Ni-site in LiNiO2 was tried to improve the cathode performance for lithium-ion batteries. The results showed that co-doping （especially, 5 at.% A1 and 10 at.% Co） definitely had a large beneficial effect in increasing the capacity （186.2 mA.h/g of the first discharge capacity for LiNio.s.42OoaoAlo.0502） and cycling behavior （180.1 mA-h/g after 10 cycles for LiNio.85CooaoAlo.osO2） compared with 180.7 mA.h/g of the first discharge capacity and 157.7 mA.h/g of the tenth discharge capacity for LiNiO2, respectively. Differen- tial capacity versus voltage curves showed that the co-doped LiNio.95_xCoxmlo.osO2 had less intensity of the phase transitions than the pristine LiNiO2.
文摘Samples of LiNi0.95-xCoxAl0.05O2（x=0.10 and 0.15） and LiNiO2,synthesized by the solid-state reaction at 725?℃ for 24?h from LiOH·H2O,Ni2O3,Co2O3,and Al（OH）3 under an oxygen stream,were characterized by TG-DTA,XRD,SEM,and electrochemical tests. Simultaneous doping of cobalt and aluminum at the Ni-site in LiNiO2 was tried to improve the cathode performance for lithium-ion batteries. The results showed that co-doping （especially,5% Al and 10% Co in atomic fraction） definitely had a large beneficial effect in increasing the capacity （186.2?mA·h/g of the first discharge capacity for LiNi 0.85 Co 0.1 0Al 0.05 O2） and cycling behavior (180.1?mA·h/g after 10 cycles for LiNi0.95-xCoxAl0.05O2) compared with 180.7?mA·h/g of the first discharge capacity and 157.7?mA·h/g of the tenth discharge capacity for LiNiO2,respectively. Differential capacity versus voltage curves showed that the co-doped LiNi0.95-xCoxAl0.05O2 had less intensity of the phase transitions than the pristine LiNiO2.
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。
