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
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LiNi_(0.5)Co_(0.2)Mn_(0.3)O_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
Layered F-doped cathode materials 0.3 Li_2 MnO_3-0.7 LiMn_(1/3)Ni_(1/3)CO_(1/3))O_(2-x)F_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 LiMn_(1/3)Ni_(1/3)CO_(1/3))O_(2-x)F_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
As promising,low-cost alternatives of lithiumion batteries for large-scale electric energy storage,sodiumion batteries(SIBs)have been studied by many researchers.However,the relatively large size of Na+leads to sluggi...As promising,low-cost alternatives of lithiumion batteries for large-scale electric energy storage,sodiumion batteries(SIBs)have been studied by many researchers.However,the relatively large size of Na+leads to sluggish diffusion kinetics and poor cycling stability in most cathode materials,restricting their further applications.In this work,we demonstrated a novel K+-intercalated Mn/Ni-based layered oxide material(K0.7Mn0.7Ni0.3O2,denoted as KMNO)with stabilized and enlarged diffusion channels for high energy density SIBs.A spontaneous ion exchange behavior in forming K0.1Na0.7Mn0.7Ni0.3O2between the KMNO electrode and the sodium ion electrolyte was clearly revealed by in situ X-ray diffraction and ex situ inductively coupled plasma analysis.The interlayer space varied from 6.90 to 5.76?,larger than that of Na0.7Mn0.7Ni0.3O2(5.63?).The enlarged ionic diffusion channels can effectively increase the ionic diffusion coefficient and simultaneously provide more K+storage sites in the product framework.As a proof-of-concept application,the SIBs with the as-prepared KMNO as a cathode display a high reversible discharge capacity(161.8 mA h g-1at0.1 A g-1),high energy density(459 W h kg-1)and superior rate capability of 71.1 mA h g-1at 5 A g-1.Our work demonstrates that the K+pre-intercalation strategy endows the layered metal oxides with excellent sodium storage performance,which provides new directions for the design of cathode materials for various batteries.展开更多
文摘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.
文摘用气相沉积法(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LiNi_(0.5)Co_(0.2)Mn_(0.3)O_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。
基金financially supported by the National Natural Science Foundation of China (No. 51372136)the NSFC-Guangdong United Fund (No. U1401246)
文摘Layered F-doped cathode materials 0.3 Li_2 MnO_3-0.7 LiMn_(1/3)Ni_(1/3)CO_(1/3))O_(2-x)F_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supported by the National Natural Science Foundation of China(51872218 and 51832004)the National Key R&D Program of China(2016YFA0202603)the Fundamental Research Funds for the Central Universities(WUT:2017III009)。
文摘As promising,low-cost alternatives of lithiumion batteries for large-scale electric energy storage,sodiumion batteries(SIBs)have been studied by many researchers.However,the relatively large size of Na+leads to sluggish diffusion kinetics and poor cycling stability in most cathode materials,restricting their further applications.In this work,we demonstrated a novel K+-intercalated Mn/Ni-based layered oxide material(K0.7Mn0.7Ni0.3O2,denoted as KMNO)with stabilized and enlarged diffusion channels for high energy density SIBs.A spontaneous ion exchange behavior in forming K0.1Na0.7Mn0.7Ni0.3O2between the KMNO electrode and the sodium ion electrolyte was clearly revealed by in situ X-ray diffraction and ex situ inductively coupled plasma analysis.The interlayer space varied from 6.90 to 5.76?,larger than that of Na0.7Mn0.7Ni0.3O2(5.63?).The enlarged ionic diffusion channels can effectively increase the ionic diffusion coefficient and simultaneously provide more K+storage sites in the product framework.As a proof-of-concept application,the SIBs with the as-prepared KMNO as a cathode display a high reversible discharge capacity(161.8 mA h g-1at0.1 A g-1),high energy density(459 W h kg-1)and superior rate capability of 71.1 mA h g-1at 5 A g-1.Our work demonstrates that the K+pre-intercalation strategy endows the layered metal oxides with excellent sodium storage performance,which provides new directions for the design of cathode materials for various batteries.
