Layered F-doped cathode materials 0.3 Li_2 MnO_3-0.7 LiMn1/3Ni1/3CO1/3)O2-xF_x(x = 0, 0.01, 0.02, 0.03, 0.04,0.05) microspheres made up of nanosized primary grains were prepared through co-precipitation me...Layered F-doped cathode materials 0.3 Li_2 MnO_3-0.7 LiMn1/3Ni1/3CO1/3)O2-xF_x(x = 0, 0.01, 0.02, 0.03, 0.04,0.05) microspheres made up of nanosized primary grains were prepared through co-precipitation method. The sample of x = 0.02 demonstrates a large discharge capacity of226 mAh g-1 over 100 cycles at 0.1 C and excellent rate performance with discharge capacity of 96 mAh g-1 at 5.0 C and room temperature. Particularly, this material shows much enhanced electrochemical performances even at high temperature of 55 ℃. It delivers a quite high discharge capacity of 233.7 mAh·g-1 at 1.0 C with capacity retention as high as 97.9% after 100 cycles. The results demonstrate that the fluorine incorporation stabilizes the cathode structure and maintains stable interfacial resistances.展开更多
Since lithium-ion battery with high energy density is the key component for next-generation electrical vehicles, a full understanding of its thermal behaviors at different discharge rates is quite important for the de...Since lithium-ion battery with high energy density is the key component for next-generation electrical vehicles, a full understanding of its thermal behaviors at different discharge rates is quite important for the design and thermal management of lithium-ion batteries (LIBs) pack/module. In this work, a 25 Ah pouch type Li[Ni0.7 Co0.15Mn0.15]O2/graphite LIBs with specific energy of 200 Wh.kg-1 were designed to investigate their thermal behaviors, including temperature distribution, heat generation rate, heat capacity and heat transfer coefficient with environment. Results show that the temperature increment of the charged pouch batteries strongly depends on the discharge rate and depth of discharge. The heat generation rate is mainly influenced by the irreversible heat effect, while the reversible heat is important at all discharge rates and contributes much to the middle evolution of the tem- perature during discharge, especially at low rate. Subse- quently, a prediction model with lumped parameters was used to estimate the temperature evolution at different discharge rates of LIBs. The predicted results match well with the experimental results at all discharge rates. Therefore, the thermal model is suitable to predict the average temperature for the large-scale batteries under normal operating conditions.展开更多
用气相沉积法(CVD)和转移法制备了石墨烯,用超声分散及搅拌的方法分别制备了导电碳黑(SP)导电浆料,导电碳黑(SP)、碳纳米管(CNTs)复合导电浆料(SP/CNTs)及导电碳黑(SP)、碳纳米管(CNTs)和石墨烯(G)复合导电浆料(SP/CNTs/G),通过扫描电镜...用气相沉积法(CVD)和转移法制备了石墨烯,用超声分散及搅拌的方法分别制备了导电碳黑(SP)导电浆料,导电碳黑(SP)、碳纳米管(CNTs)复合导电浆料(SP/CNTs)及导电碳黑(SP)、碳纳米管(CNTs)和石墨烯(G)复合导电浆料(SP/CNTs/G),通过扫描电镜(SEM)、四探针测试、恒流充放电测试、循环伏安测试(CV)和电化学阻抗谱测试(EIS)等方法研究了导电剂对锂离子电池正极材料LiNi0.5Co0.2Mn0.3O_2的表面形貌、电阻率和电化学性能的影响。结果表明:添加质量分数2%复合导电剂SP/CNTs/G的样品电阻率较小,0.2 C首次充放电比容量分别为201.93 m Ah·g–1和180.29 m Ah·g–1,首次充放电效率为89.28%。3.0C循环5次后的放电比容量为161.45 m Ah·g–1,容量保持率仍有89.69%,1.0C循环50次后放电比容量为166.97 m Ah·g–1,容量保持率为96.65%,倍率和循环性能优良。展开更多
采用高温固相法烧结制备得到正极材料Li Ni0.5Co0.2Mn0.3O2,通过X射线衍射(XRD)、扫描电镜(SEM)以及循环伏安(CV)、交流阻抗(EIS)等电化学性能测试手段,探讨高温烧结工艺中不同锂源对材料结构、形貌及电化学性能的影响,结果表明,采用Li...采用高温固相法烧结制备得到正极材料Li Ni0.5Co0.2Mn0.3O2,通过X射线衍射(XRD)、扫描电镜(SEM)以及循环伏安(CV)、交流阻抗(EIS)等电化学性能测试手段,探讨高温烧结工艺中不同锂源对材料结构、形貌及电化学性能的影响,结果表明,采用Li OH作为锂源合成的材料与采用其他锂源相比,具有较好的层状结构和电化学性能.该材料在0.1C倍率下的首次充放电容量和库伦效率较高(172.7 m Ah/g,89.08%),在0.5C、1C倍率下循环50次后,材料的放电容量仍保持在144.5 m Ah/g和136.2 m Ah/g.展开更多
基金financially supported by the National Natural Science Foundation of China (No. 51372136)the NSFC-Guangdong United Fund (No. U1401246)
摘要Layered F-doped cathode materials 0.3 Li_2 MnO_3-0.7 LiMn1/3Ni1/3CO1/3)O2-xF_x(x = 0, 0.01, 0.02, 0.03, 0.04,0.05) microspheres made up of nanosized primary grains were prepared through co-precipitation method. The sample of x = 0.02 demonstrates a large discharge capacity of226 mAh g-1 over 100 cycles at 0.1 C and excellent rate performance with discharge capacity of 96 mAh g-1 at 5.0 C and room temperature. Particularly, this material shows much enhanced electrochemical performances even at high temperature of 55 ℃. It delivers a quite high discharge capacity of 233.7 mAh·g-1 at 1.0 C with capacity retention as high as 97.9% after 100 cycles. The results demonstrate that the fluorine incorporation stabilizes the cathode structure and maintains stable interfacial resistances.
基金financially supported by the Program from Ministry of Science and Technology of China(No.2011AA11A254)the National High Technology Research and Development Program of China(No.2012AA110102)
摘要Since lithium-ion battery with high energy density is the key component for next-generation electrical vehicles, a full understanding of its thermal behaviors at different discharge rates is quite important for the design and thermal management of lithium-ion batteries (LIBs) pack/module. In this work, a 25 Ah pouch type Li[Ni0.7 Co0.15Mn0.15]O2/graphite LIBs with specific energy of 200 Wh.kg-1 were designed to investigate their thermal behaviors, including temperature distribution, heat generation rate, heat capacity and heat transfer coefficient with environment. Results show that the temperature increment of the charged pouch batteries strongly depends on the discharge rate and depth of discharge. The heat generation rate is mainly influenced by the irreversible heat effect, while the reversible heat is important at all discharge rates and contributes much to the middle evolution of the tem- perature during discharge, especially at low rate. Subse- quently, a prediction model with lumped parameters was used to estimate the temperature evolution at different discharge rates of LIBs. The predicted results match well with the experimental results at all discharge rates. Therefore, the thermal model is suitable to predict the average temperature for the large-scale batteries under normal operating conditions.
摘要用气相沉积法(CVD)和转移法制备了石墨烯,用超声分散及搅拌的方法分别制备了导电碳黑(SP)导电浆料,导电碳黑(SP)、碳纳米管(CNTs)复合导电浆料(SP/CNTs)及导电碳黑(SP)、碳纳米管(CNTs)和石墨烯(G)复合导电浆料(SP/CNTs/G),通过扫描电镜(SEM)、四探针测试、恒流充放电测试、循环伏安测试(CV)和电化学阻抗谱测试(EIS)等方法研究了导电剂对锂离子电池正极材料LiNi0.5Co0.2Mn0.3O_2的表面形貌、电阻率和电化学性能的影响。结果表明:添加质量分数2%复合导电剂SP/CNTs/G的样品电阻率较小,0.2 C首次充放电比容量分别为201.93 m Ah·g–1和180.29 m Ah·g–1,首次充放电效率为89.28%。3.0C循环5次后的放电比容量为161.45 m Ah·g–1,容量保持率仍有89.69%,1.0C循环50次后放电比容量为166.97 m Ah·g–1,容量保持率为96.65%,倍率和循环性能优良。
摘要采用高温固相法烧结制备得到正极材料Li Ni0.5Co0.2Mn0.3O2,通过X射线衍射(XRD)、扫描电镜(SEM)以及循环伏安(CV)、交流阻抗(EIS)等电化学性能测试手段,探讨高温烧结工艺中不同锂源对材料结构、形貌及电化学性能的影响,结果表明,采用Li OH作为锂源合成的材料与采用其他锂源相比,具有较好的层状结构和电化学性能.该材料在0.1C倍率下的首次充放电容量和库伦效率较高(172.7 m Ah/g,89.08%),在0.5C、1C倍率下循环50次后,材料的放电容量仍保持在144.5 m Ah/g和136.2 m Ah/g.