Studies of the LiAl_yNi_(1-y)O_2 as Cathode Materials for Rechargeable Lithium Ion Batteries

本文采用固相反应法合成了一系列不同 y值的LiAlyNi1- yO2 材料 ,通过对其电化学性能的研究发现 ,在适当的烧结条件下 ,LixAl0 .2 5 Ni0 .75 O2 作为二次锂离子电池的正极材料 ,其耐过充性和循环性能都有明显改善 .当Li含量大于 1时 ,在高电位范围充放 (3- 4 .8V) 30次循环后仍保持着首次放电容量的 95 % ,而LiNiO2 在此电压范围内经 2 0次循环后却只有首次放电容量的 5 6 % .通过循环伏安实验表明 :性能改善的主要原因可能是由于充电过程中 ,Al3+ 的掺杂阻止了LixAl0 .2 5Ni0 .75 O2 随Li+ 离子过量脱出而发生晶型转变 .In this paper, we have synthesized series of single_phase LiAl yNi 1-y O 2 (differentive in value_y) by solid reaction. Through examining their electrothemical properties, found that, under a proper sintering condition, Li xAl 0.25 Ni 0.75 O 2 solution for cathode materials of rechargeable lithium ion batteries showed more pleasing properties in overcharge_resist and cycling life ( vs LiNiO 2). When x>1, the capacity can be kept 125mAh/g after 30 cycles under higher charged/discharged voltages ranging from 3.0 V to 4.8 V, whereas that of pure LiNiO 2 has only 61 nAh/g after 25 cycles. The results of CV for LiAl yNi 1-y O 2 and pure LiNiO 2 showed that this may be due to the Al 3+ doping and by preventing Li + from overcharging, Al 3+ conbined with Li + obviated the phase transmission during charged/discharged progress.作者联系地址：北京科技大学材料学院固体电解质研究室!北京100083,北京科技大学材料学院固体电解质研究室!北京100083,北京科技大学材料学院固体电解质研究室!北京100083,北京科技大学材料学院固体电解质研究室!北京100083Author's Address: Lab. for Solid State Ionics, Material Sci. Coll. of Univ. of Sci. & Techn., Beijing 100083, Chin

The Property Study of LiBOB-PC/DEC Electrolyte

合成锂离子电池新型电解质锂盐L iBOB,并与PC/DEC溶剂配成电解液.室温下研究了L iBOB-PC/DEC电解液电导率随锂盐浓度的变化规律及其用于L i/ARG电池充放电循环性能的最佳组成配比,为0.5mol.L-1L iBOB-PC/DEC(3∶7).应用交流阻抗和循环伏安法研究了该最佳电解液的电化学性质及其电极/界面状态,结果显示,石墨电极在这种电解液中可形成良好的SEI膜.The new electrolyte salt LiBOB for Li-ion battery was synthesized in laboratory,and series of electrolytes of LiBOB and PC/DEC was compounded.The conductivity of the electrolytes was compared by changing the temperature and concentration.The cycling performance of charging-discharging was also compared by the charging-discharging test,the results showed that the varying regularity of conductivities and cycling stability and capacity were not always identical,but there were a suitable electrolyte for Li/ARG cell.The A.C.impedance and CV were used to test the compatibility of the most suitable electrolyte and ARG anode.Conclusion can be drawn that the ARG anode can be protected very well by SEI film in 0.5 mol·L~(-1)LiBOB-PC/DEC(3∶7).作者联系地址：北京科技大学材料科学与工程学院无机非金属材料系,北京科技大学材料科学与工程学院无机非金属材料系,北京科技大学材料科学与工程学院无机非金属材料系,北京科技大学材料科学与工程学院无机非金属材料系 北京100083,北京100083,北京100083,北京100083Author's Address: Department of Inorganic Nonmetallic Materials,School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,Chin

Determination of Transport Number of the Modified LiClO_4- (PEO)_(20) Polymer Electrolyte

采用交流阻抗和恒电位计时电流法测定了ＬｉＣｌＯ４·（ＰＥＯ）２０·（ＰＣ）１２·（ＥＣ）１２高分子电解质的锂离子迁移数。在非水溶液和高分子电解质中，锂是热力学不稳定的，表面生成一层固体电解质钝化膜，严重地影响了锂离子迁移数的准确测定。本方法避免固体电解质钝化膜的影响，给出正确的锂离子迁移数测定值，实验表明，ＬｉＣｌＯ４·（ＰＥＯ）２０·（ＰＣ）１２·（ＥＣ）１２电解质的电导率为０．８×１０－３／ｃｍ，锂离子迁移数为０．３。In this work a combination method of A. C. Impedance and chronoamperometry was used to determine the lithium ion transport number of LiClO_4·(PEO)_(20)·(PC)_(12)·(EC)_(12) polymer electrolyte. It is known that lithium is thermodynamically unstable in non-aqueous or polymer electrolytes, leading to the formtion of a film on lithium surface, called as solid electrolyte interphase (SEI). The presence of SEI layer will greatly influence the experimental result of lithium ion transport number. The new method avoid the effect of SEI layer, and can give correct transport number of lithium ion in the electrolyte of DCIO_4·(PED)_(20)·(PC)_(12)·(EC)_(12). The exporimental result indicates that the conducrivity of the electrolyte is 0. 8 ×10￣(-3)s/cm, Li￣+ transport number is 0. 30 at 25℃.作者联系地址：北京科技大学，化工部北京化工研究院Author's Address: University of Science and Technology Beijing, Bijing, 100083Yang Leiling Beijing Research Institute of Chemical Industry, Bijing, 10001

Electrochemical Characterization of Positive Electrode Material LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2 in Different Electrolytes

应用低热固相合成法制备锂离子电池正极材料L iCo1/3N i1/3Mn1/3O2.研究该材料的结构与形貌,并比较它在商品L iPF6盐和在实验室合成的L iBOB(L iB(C2O4)2)盐电解液中的电化学性能.在L iPF6/EC+DMC+DEC电解液中,该材料表现出优良的电化学性能,其于0.5C、1C、1.5C、2C、3C放电倍率的初始比容量依次为167、163、163、157、147mAh/g,电池的循环性能也较好,说明低热固相合成的材料的有较好的高倍率性能.在L iBOB/EC+DEC+DE电解液中,0.5C倍率下比容量为160 mAh/g,较之L iPF6盐电解液的相差不大,但在高倍率下的比容量有所下降.Cathode materials LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2) were prepared by low-heating solid-state reaction.The micro-structure and morphology of as-synthesized materials have been investigated by using XRD and SEM.The compatibilities of LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2) with purchased LiPF_(6)/ EC+DMC+DEC electrolyte and prepared LiBOB/EC+DEC+EMC electrolyte have also been studied.The Li/LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2) batteries showed excellent electrochemical properties in the LiPF_(6)/ EC+DMC+DEC electrolyte.Reversible discharge capacities of 167、163、163、157、147mAh/g at 0.5C、1C、1.5C、2C、3C rate between 2.7~4.35 V,with stable cycling performances have been obtained.Comparatively,the specific capacity of 160 mAh/g at 0.5C was obtained in LiBOB/EC+DEC+DEC electrolyte,which was just a little lower than that in the other electrolyte.However,the high rate capability of the materials in LiBOB/EC+DEC+DEC was not as good as that in LiPF_(6)/EC+DMC+DEC,which needs to be improved in further studies.作者联系地址：北京科技大学材料科学与工程学院无机非金属材料系,北京科技大学材料科学与工程学院无机非金属材料系,北京科技大学材料科学与工程学院无机非金属材料系,北京科技大学材料科学与工程学院无机非金属材料系,北京科技大学材料科学与工程学院无机非金属材料系 北京100083,北京100083,北京100083,北京100083,北京100083Author's Address: Department of Inorganic Nonmetallic Materials,School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,Chin

Synthesis and Electrochemical Characteristics of Li[Li_(0.167)Mn_(0.583)Ni_(0.25)]O_2 Cathode Material

应用低热固相法制备镍锰复合正极材料Li[Li0.167Mn0.583Ni0.25]O2.XRD、FESEM和恒电流充放电测试表明,该材料结晶良好,可标定为α-NaFeO2型结构(空间群R3-m),颗粒粒径约为60~100 nm,粒度均匀细小.在2.5~4.4 V之间以0.5 C(100 mA/g)做充放电循环时,可逆比容量在120 mAh/g以上,循环性能非常稳定.如将截止电压升高到4.6 V,则比容量大大提高,最高可达234 mAh/g.上述充放电测试都出现了比容量随循环次数上升的现象.主要原因可归结为材料中Mn(Ⅳ)向Mn(Ⅲ)的转变,但在不同的电压范围内导致该转变的起因并不相同.The cathode material of Li[Li0.167Mn0.583Ni0.25]O2 was synthesized by low-heat solid state reaction.The results of XRD and FESEM indicated that the powders of the material were well crystallized with the uniform diameters ranging from 60 nm to 100 nm and could be indexed as α-NaFeO2 structure(R3-m space).Galvanostatic charge-discharge tests showed that the electrode delivered the capacity of about 120 mAh/g with good cyclability when cycled in 2.5~4.4V at 0.5C.When the cut-off potential was set up to 4.6V,the cathode delivered much larger capacities with the maximum of 234 mAh/g.It was observed that the discharge capacity gradually increased with the increment of the cycle number.The transformation between Mn(Ⅳ) and Mn(Ⅲ) could be responsible for the increasing capacity.However,the causes for this transformation in different potenticals varied.作者联系地址：北京科技大学材料科学与工程学院北京市新能源材料与技术重点实验室,北京科技大学材料科学与工程学院北京市新能源材料与技术重点实验室,北京科技大学材料科学与工程学院北京市新能源材料与技术重点实验室,北京科技大学材料科学与工程学院北京市新能源材料与技术重点实验室,北京科技大学材料科学与工程学院北京市新能源材料与技术重点实验室,北京科技大学材料科学与工程学院北京市新能源材料与技术重点实验室 北京100083,中钢集团洛阳耐火材料研究院,河南洛阳471039,北京100083,北京100083,北京100083,北京100083,北京100083Author's Address: 1.Beijing Key Lab.of New Energy Materials and Technologies,School of Material Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China;2.Sinosteel Luoyang Institute of Refractories Research,Luoyang 471039,Hennan,Chin