随着电动汽车的发展,迫切需要具有高安全性、高能量密度、高功率、大容量、长寿命、高环保、低成本等优点的锂离子电池。层状结构的富锂锰基正极材料由于具有比容量高、平台电压高、热稳定性好、价格低廉的特点而被认为是有希望的未来...随着电动汽车的发展,迫切需要具有高安全性、高能量密度、高功率、大容量、长寿命、高环保、低成本等优点的锂离子电池。层状结构的富锂锰基正极材料由于具有比容量高、平台电压高、热稳定性好、价格低廉的特点而被认为是有希望的未来电动汽车候选正极材料之一。尽管其拥有很高的比容量,但仍存在着首次循环不可逆容量高、倍率性能差等问题,纳米化是改进材料倍率性能的一种有效手段。本文以Ni O,Co_3O_4,Mn CO_3和Li_2CO_3为原料,成功制备得到了纳米级的锂离子电池正极材料Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_2。通过X射线衍射(XRD)、扫描电子显微镜(SEM)和充放电测试对所得样品的结构、形貌及电化学性能进行了表征。结果表明,合成的Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_2材料具有层状结构,一次颗粒均匀、细小,平均颗粒尺寸约为90 nm,并具有良好的电化学性能,在2.0~4.8 V以0.1C充放电时,首次放电比容量达到284 m Ah·g^(-1),首次库伦效率为86.1%。材料同时拥有良好的倍率性能,1.0C放电容量达到240 m Ah·g^(-1),3.0C放电容量达到210 m Ah·g^(-1)。展开更多
The Li-rich layered oxides show a higher discharge capacity over 250 mAh/g and have been developed into a promising positive material for lithium ion batteries. A rare earth metal oxyfluoride YOF-coated Li[Lio.2Mno.54...The Li-rich layered oxides show a higher discharge capacity over 250 mAh/g and have been developed into a promising positive material for lithium ion batteries. A rare earth metal oxyfluoride YOF-coated Li[Lio.2Mno.54Ni0.13Co0.13]O2 composites have been synthesized by a simple wet chem- ical method. Crystal structure, micro-morphology and element valence of the pristine and YOF-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 materials are characterized by XRD, SEM, TEM, and XPS. The results indicate that all materials exhibit a typical layered structure, and are made up of small and homogenous parti- cles ranging from 100 nm to 200 nm. In addition, YOF layer with a thickness of approximately 3-8 nm is precisely coated on the surface of the Li[Li0.2Mn0.54Ni0.13Co0.13]02. Constant current charge/discharge tests at various current densities show that the electrochemical performance of 2 wt% YOF-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 has been improved significantly. 2 wt% YOF-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 delivers the highest discharge capacity of 250.4 mAh/g at 20 mA/g among all the samples, and capacity retention of 87% after 100 charge/discharge cycles at 200 mA/g while that of the pristine one is only 81.6%. The superior electrochemical performance of 2wt% YOF-coated sample is ascribed to YOF coating layer, which could not only reduce side reactions between the electrode and liquid electrolyte, but also promote lithium ion migration.展开更多
在Li1.2Mn0.54Ni0.13Co0.13O2的制备过程中,通过扫描电镜（SEM）对前驱体MCO3（M=Mn,Ni,Co）颗粒大小及形貌进行了考察,对共沉淀体系的工艺参数优化结果如下：pH值为7.08.0,氨水浓度为0.27 mol/L,采用4 m L/min并流加料、磁力搅拌条件下...在Li1.2Mn0.54Ni0.13Co0.13O2的制备过程中,通过扫描电镜（SEM）对前驱体MCO3（M=Mn,Ni,Co）颗粒大小及形貌进行了考察,对共沉淀体系的工艺参数优化结果如下：pH值为7.08.0,氨水浓度为0.27 mol/L,采用4 m L/min并流加料、磁力搅拌条件下,60℃下反应6 h。展开更多
Li-rich Li[Li0.2Mn0.54Ni0.13Co0.13]02（LMNC） powders were synthesized by a gel-combustion method. The related microstructure, electrochemical performance and electrochemically induced phase evolution were characteriz...Li-rich Li[Li0.2Mn0.54Ni0.13Co0.13]02（LMNC） powders were synthesized by a gel-combustion method. The related microstructure, electrochemical performance and electrochemically induced phase evolution were characterized. The 900℃ calcined powders have a hexagonal layered structure with high ordered degree and low cationic mixing level. The calcined materials as cathode electrode for Li-ion battery deliver the high electrochemical properties with an initial discharge capacity of 243.5 mA. h. g-1 at 25 mA.g-1 and 249.2 mA-h.g-1 even after 50 cycles. The electrochemically induced phase evolution investigated by a transmission electron microscopy indicates that Li＋ ions deintercalated first from the LiMO2 （M = Mn, Co, Ni） component and then from Li2MnO3 component in the LMNC during the charge process, while Li＋ ions intercalated into Li1-xMO2 component followed by into MnO2 component during the discharge process.展开更多
以过渡金属硫酸盐和一水合氢氧化锂为原料,采用共沉淀-高温固相烧结法制备富锂正极材料Li[Li0.2Ni0.13Co0.13Mn0.54]O2。通过XRD、SEM和电池充放电测试方法考察了产物结构和性能,结果表明：在水浴50℃下控制p H=11合成的前驱体具有很好...以过渡金属硫酸盐和一水合氢氧化锂为原料,采用共沉淀-高温固相烧结法制备富锂正极材料Li[Li0.2Ni0.13Co0.13Mn0.54]O2。通过XRD、SEM和电池充放电测试方法考察了产物结构和性能,结果表明：在水浴50℃下控制p H=11合成的前驱体具有很好的分散性,且在950℃下烧结得到了优越的电化学性能;在0.1C（1C=300 m A/g）充放电时,首次放电比容量为258.9 m Ah/g（2.0~4.8 V）,首次充放电效率为75.6%;在1C充放电时,首次放电比容量为204.6 m Ah/g,循环10次后放电比容量为179.9 m Ah/g;2C倍率下仍保持了141.4 m Ah/g的放电比容量。展开更多
利用XRD、SEM、EDS、BET、激光粒度、循环伏安、恒流充放电、交流阻抗方法研究了葡萄糖为碳源对溶胶凝胶法制备Li1.2Ni0.13Co0.13Mn0.54O2正极材料的结构、形貌以及电化学性能的影响。结果表明:与前驱体中未加入葡萄糖所制备的材料相比...利用XRD、SEM、EDS、BET、激光粒度、循环伏安、恒流充放电、交流阻抗方法研究了葡萄糖为碳源对溶胶凝胶法制备Li1.2Ni0.13Co0.13Mn0.54O2正极材料的结构、形貌以及电化学性能的影响。结果表明:与前驱体中未加入葡萄糖所制备的材料相比,掺葡萄糖后样品颗粒分布相对均匀,粒径变小,D50从11.56减小至9.94μm,比表面积增加近1倍。经0.05C充放电活化后,未掺葡萄糖和掺葡萄糖样品0.2C放电比容量分别为183.4、211.6 m Ah·g-1,2C容量分别为其0.2C的62.2%、77.6%。1C循环50次后放电比容量分别为133.3、173.6 m Ah·g-1,容量保持率分别为95.1%、100%。掺葡萄糖可降低首次不可逆容量损失,提高材料的倍率性能与循环稳定性,减少电荷传递阻抗、Warburg阻抗以及双电层弥散效应,但不改变材料的晶型结构。展开更多
以乙酸盐(乙酸锂、乙酸钠、乙酸钴、乙酸镍、乙酸锰等)为原材料,采用球磨辅助高温固相法制备Li_(1.0)Na_(0.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_2正极材料。借助XRD、SEM等表征材料的结构和形貌,利用循环伏安、恒流充放电、交流阻抗等方法...以乙酸盐(乙酸锂、乙酸钠、乙酸钴、乙酸镍、乙酸锰等)为原材料,采用球磨辅助高温固相法制备Li_(1.0)Na_(0.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_2正极材料。借助XRD、SEM等表征材料的结构和形貌,利用循环伏安、恒流充放电、交流阻抗等方法研究材料的电化学性能。结果表明,钠的掺杂导致颗粒表面光滑度降低,形成Na_(0.77)Mn O_(2.05)新相。0.05C活化过程中,掺钠样品和未掺钠样品首次放电比容量分别为258.4 m Ah·g^(-1)和215.8 m Ah·g^(-1),库伦效率分别为75.2%和72.8%;2C放电比容量分别为116.3 m Ah·g^(-1)和106.2 m Ah·g^(-1)。研究发现,掺钠可减小首次充放电过程的不可逆容量,提高容量保持率;改善倍率性能与容量恢复特性;降低SEI膜阻抗和电荷转移阻抗;掺钠后样品首次循环就可以基本完成Li_2Mn O_3组分向稳定结构的转化,而未掺杂的样品需要两次循环才能逐步完成该过程;XPS结果表明,掺钠样品中Ni^(2+)、Co^(3+)、Mn^(4+)所占比例明显提高,改善了样品的稳定性和电化学性能;循环200次后的XRD结果表明掺钠与未掺钠材料在脱嵌锂反应中的相变化过程基本一致,良好有序的层状结构遭到破坏是循环过程中容量衰减的主要原因。展开更多
文摘随着电动汽车的发展,迫切需要具有高安全性、高能量密度、高功率、大容量、长寿命、高环保、低成本等优点的锂离子电池。层状结构的富锂锰基正极材料由于具有比容量高、平台电压高、热稳定性好、价格低廉的特点而被认为是有希望的未来电动汽车候选正极材料之一。尽管其拥有很高的比容量,但仍存在着首次循环不可逆容量高、倍率性能差等问题,纳米化是改进材料倍率性能的一种有效手段。本文以Ni O,Co_3O_4,Mn CO_3和Li_2CO_3为原料,成功制备得到了纳米级的锂离子电池正极材料Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_2。通过X射线衍射(XRD)、扫描电子显微镜(SEM)和充放电测试对所得样品的结构、形貌及电化学性能进行了表征。结果表明,合成的Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_2材料具有层状结构,一次颗粒均匀、细小,平均颗粒尺寸约为90 nm,并具有良好的电化学性能,在2.0~4.8 V以0.1C充放电时,首次放电比容量达到284 m Ah·g^(-1),首次库伦效率为86.1%。材料同时拥有良好的倍率性能,1.0C放电容量达到240 m Ah·g^(-1),3.0C放电容量达到210 m Ah·g^(-1)。
基金financially supported by the National Basic Research Program of China(Grant no.2015CB251100)
文摘The Li-rich layered oxides show a higher discharge capacity over 250 mAh/g and have been developed into a promising positive material for lithium ion batteries. A rare earth metal oxyfluoride YOF-coated Li[Lio.2Mno.54Ni0.13Co0.13]O2 composites have been synthesized by a simple wet chem- ical method. Crystal structure, micro-morphology and element valence of the pristine and YOF-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 materials are characterized by XRD, SEM, TEM, and XPS. The results indicate that all materials exhibit a typical layered structure, and are made up of small and homogenous parti- cles ranging from 100 nm to 200 nm. In addition, YOF layer with a thickness of approximately 3-8 nm is precisely coated on the surface of the Li[Li0.2Mn0.54Ni0.13Co0.13]02. Constant current charge/discharge tests at various current densities show that the electrochemical performance of 2 wt% YOF-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 has been improved significantly. 2 wt% YOF-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 delivers the highest discharge capacity of 250.4 mAh/g at 20 mA/g among all the samples, and capacity retention of 87% after 100 charge/discharge cycles at 200 mA/g while that of the pristine one is only 81.6%. The superior electrochemical performance of 2wt% YOF-coated sample is ascribed to YOF coating layer, which could not only reduce side reactions between the electrode and liquid electrolyte, but also promote lithium ion migration.
文摘在Li1.2Mn0.54Ni0.13Co0.13O2的制备过程中,通过扫描电镜（SEM）对前驱体MCO3（M=Mn,Ni,Co）颗粒大小及形貌进行了考察,对共沉淀体系的工艺参数优化结果如下：pH值为7.08.0,氨水浓度为0.27 mol/L,采用4 m L/min并流加料、磁力搅拌条件下,60℃下反应6 h。
文摘Li-rich Li[Li0.2Mn0.54Ni0.13Co0.13]02（LMNC） powders were synthesized by a gel-combustion method. The related microstructure, electrochemical performance and electrochemically induced phase evolution were characterized. The 900℃ calcined powders have a hexagonal layered structure with high ordered degree and low cationic mixing level. The calcined materials as cathode electrode for Li-ion battery deliver the high electrochemical properties with an initial discharge capacity of 243.5 mA. h. g-1 at 25 mA.g-1 and 249.2 mA-h.g-1 even after 50 cycles. The electrochemically induced phase evolution investigated by a transmission electron microscopy indicates that Li＋ ions deintercalated first from the LiMO2 （M = Mn, Co, Ni） component and then from Li2MnO3 component in the LMNC during the charge process, while Li＋ ions intercalated into Li1-xMO2 component followed by into MnO2 component during the discharge process.
文摘以过渡金属硫酸盐和一水合氢氧化锂为原料,采用共沉淀-高温固相烧结法制备富锂正极材料Li[Li0.2Ni0.13Co0.13Mn0.54]O2。通过XRD、SEM和电池充放电测试方法考察了产物结构和性能,结果表明：在水浴50℃下控制p H=11合成的前驱体具有很好的分散性,且在950℃下烧结得到了优越的电化学性能;在0.1C（1C=300 m A/g）充放电时,首次放电比容量为258.9 m Ah/g（2.0~4.8 V）,首次充放电效率为75.6%;在1C充放电时,首次放电比容量为204.6 m Ah/g,循环10次后放电比容量为179.9 m Ah/g;2C倍率下仍保持了141.4 m Ah/g的放电比容量。
文摘利用XRD、SEM、EDS、BET、激光粒度、循环伏安、恒流充放电、交流阻抗方法研究了葡萄糖为碳源对溶胶凝胶法制备Li1.2Ni0.13Co0.13Mn0.54O2正极材料的结构、形貌以及电化学性能的影响。结果表明:与前驱体中未加入葡萄糖所制备的材料相比,掺葡萄糖后样品颗粒分布相对均匀,粒径变小,D50从11.56减小至9.94μm,比表面积增加近1倍。经0.05C充放电活化后,未掺葡萄糖和掺葡萄糖样品0.2C放电比容量分别为183.4、211.6 m Ah·g-1,2C容量分别为其0.2C的62.2%、77.6%。1C循环50次后放电比容量分别为133.3、173.6 m Ah·g-1,容量保持率分别为95.1%、100%。掺葡萄糖可降低首次不可逆容量损失,提高材料的倍率性能与循环稳定性,减少电荷传递阻抗、Warburg阻抗以及双电层弥散效应,但不改变材料的晶型结构。
文摘以乙酸盐(乙酸锂、乙酸钠、乙酸钴、乙酸镍、乙酸锰等)为原材料,采用球磨辅助高温固相法制备Li_(1.0)Na_(0.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_2正极材料。借助XRD、SEM等表征材料的结构和形貌,利用循环伏安、恒流充放电、交流阻抗等方法研究材料的电化学性能。结果表明,钠的掺杂导致颗粒表面光滑度降低,形成Na_(0.77)Mn O_(2.05)新相。0.05C活化过程中,掺钠样品和未掺钠样品首次放电比容量分别为258.4 m Ah·g^(-1)和215.8 m Ah·g^(-1),库伦效率分别为75.2%和72.8%;2C放电比容量分别为116.3 m Ah·g^(-1)和106.2 m Ah·g^(-1)。研究发现,掺钠可减小首次充放电过程的不可逆容量,提高容量保持率;改善倍率性能与容量恢复特性;降低SEI膜阻抗和电荷转移阻抗;掺钠后样品首次循环就可以基本完成Li_2Mn O_3组分向稳定结构的转化,而未掺杂的样品需要两次循环才能逐步完成该过程;XPS结果表明,掺钠样品中Ni^(2+)、Co^(3+)、Mn^(4+)所占比例明显提高,改善了样品的稳定性和电化学性能;循环200次后的XRD结果表明掺钠与未掺钠材料在脱嵌锂反应中的相变化过程基本一致,良好有序的层状结构遭到破坏是循环过程中容量衰减的主要原因。
