Synthesis, Properties and In-situ XRD Study of High Capacity Layer Metal Oxide of Li-ion Batteries

动力市场是碳排放的重灾区之一，寻找取代化石能源的可持续绿色储能体系是当今世界环保经济的一大驱动力。目前锂离子电池已占据了便携式电子设备市场，然而，现有锂离子电池无法满足高动力配置对于输出功率与续航能力的要求，因此，研发高性能正极材料十分必要。富锂锰基层状氧化物xLi2MnO3·(1-x)LiMO2（M=Mn，Fe，Co，Ni，etal）与富镍层状氧化物Li[Ni1-x-yCoxMny]O2（1-x-y≥0.5）因为在高电压（>4.50V，vs.Li/Li+）下能释放超过200mAh/g的比容量，因此能满足高比能量的需求。然而，在高电压状态下，富锂锰基层状氧化物不仅在首周放电后就损失了大量的不可...Power market is one of the major bodies which could result in serious carbon emissions. Searching for sustainable green energy storage system to replace fossil energy is one of the main driving force in the world environmental economy nowadays. At present, lithium ion battery (LIB) has dominated in the portable electronic equipment market. However, the current LIB can’t meet the output power and c...学位：理学博士院系专业：化学化工学院_物理化学学号：2052013015386

Synthesis of Nanostructured LiNi_(1/3)Co_(1/3)Mn-(1/3)O-2 by AmmoniaEvaporation-Induced Synthesis and Its Electrochemical Properties as a Cathode Material for a High-Power Li-Ion Battery

采用氨蒸发诱导法成功制备出纳米结构lInI1/3CO1/3Mn1/3O2正极材料,借助X射线衍射(Xrd)分析、扫描电镜(SEM)、透射电镜(TEM)、高分辨率透射电镜(HrTEM)、能量分散谱(EdS)和比表面测试等表征手段及恒电流充放电测试研究了其晶体结构、微观形貌和电化学性能.研究表明该方法制备出的材料具有良好的α-nAfEO2层状结构,阳离子混排程度低.纳米片交错堆积而成核桃仁状形貌,片与片之间形成许多纳米孔,而且纳米片的侧面属于{010}活性面,能够提供较多的锂离子的脱嵌通道.在室温下及3.0-4.6 V充放电范围内,该材料在电流密度为0.5C、1C、3C、5C和10C时放电比容量分别为172.90、153.95、147.09、142.16和131.23MAH？g-1.说明其具有优异的电化学性能,非常有潜力用于动力汽车等高功率密度锂离子电池中.We report on an ammonia-evaporation-induced synthetic method for nanostructured LiNi1/3Co1/3Mn1/3O2 cathode material.Powder X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), high- resolution transmission electron microscopy(HRTEM), energy- dispersive X- ray spectroscopy(EDS), Brunauer-Emmett-Teller nitrogen sorption, and galvanostatic charge-discharge tests were applied to analyze the crystal structure, micromorphology, and electrochemical properties of nanostructured LiNi1/3Co1/3Mn1/3O2.The results show that it has a well-ordered layered α-NaFeO2 with little cation mixing.A walnutkernel- like morphology is formed by nanosheets, leading to a nanoporous material.The lateral plane of nanosheets are {010}-faceted, which could provide multiple channels for Li+-ion migration.The electrochemical properties of the lithium cells used this material as cathode are excellent: the specific discharge capacity at 0.5C,1C, 3C, 5C and 10 C is, respectively, up to 172.90, 153.95, 147.09, 142.16, and 131.23 mAh?g-1between 3.0and 4.6 V at room temperature.These excellent features will make the nanostructured LiNi1/3Co1/3Mn1/3O2 become a positive electrode material of potential interest for useful applications, such as in electric vehicles and hybrid electric vehicles.四川大学青年基金(2011SCU11081); 教育部高校博士学科点科研基金(20120181120103)资助项目~

Aqueous Solution-Evaporation Route Synthesis and Phase Structural Research of the Li-Rich Cathode Li_(1.23)Ni_(0.09)Co_(0.12)Mn_(0.56)O_2 by In-Situ XRD

采用水溶-蒸发法成功合成了锂离子电池lI1.23nI0.09CO0.12Mn0.56O2正极材料.通过扫面电镜(SEM)、非原位X射线衍射(Xrd)、原位Xrd观察材料形貌、表征材料结构,并测试电极电化学性能.结果显示,材料为粒径330nM的多边形结构,是层状的固溶体—lI2MnO3结构,该正极0.1C首周期放电比容量250.8 MAH·g-1,40周期循环容量保持率86.5%.通过原位Xrd可确证电极在首周期放电过程产生少量lI0.9MnO2新相,在其后多周期循环过程电极层状结构趋于向尖晶石结构发生转变致使电极电化学性能恶化.此外,晶格参数C首周期充电过程先增后减在4.54 V左右保持稳定,放电与第2周期充电过程其值逐渐下降;晶格参数A则经历了下降平稳再升高的过程,该数值的变化均对应于相应电化学行为.The Li-rich Li 1.23 Ni0.09 Co0.12 Mn0.56 O2 material was synthesized via aqueous solution-evaporation route.The structure and morphology of the material were characterized by means of XRD and SEM.The results indicated that the single particle of the product was polygonal with the size of 330 nm and the structure was layered solid solution with a certain amount of Li2 MnO3.Electrochemical tests showed that the first discharge capacity of the Li-rich layered material was 250.8 mAh·g-1at 0.1C,the capacity retention was 86.5% after 40 cycles.Through in-situ XRD study a new phase Li0.9 MnO2 which would cause electrochemical properties deteriorated due to its structure transformation from layered to spinel came out with a small amout during the first discharge cycle.Moreover, the value of c-parameter increased first and decreased before 4.54 V, and remained stable till the end of the first charge, and then reduced from the first discharge to the second charge continually.However, the value of a-parameter underwent a falling-steady-rising course.The change in the values of the lattice parameters corresponded to the variation of electrochemical behaviors.国家自然科学基金项目(No.21273184); 科技部863项目(No.2011AA11A254); 973计划项目(No.2009CB220102)项目资

Structural and Dynamics Studies of Spinel LiNi_(0.5)Mn_(1.5)O_4 Cathode Material during Initial Charge/Discharge Processes

以nAOH为沉淀剂,采用共沉淀法制备尖晶石lI nI0.5Mn1.5O4正极材料,使用X-射线衍射(Xrd)、傅里叶转换红外光谱(fTIr)和扫描电镜(SEM)分析材料结构与表面形貌.结果表明,该材料属于空间群的无序尖晶石lI nI0.5Mn1.5O4材料,由八面体粒子团聚成3~6μM的大粒子.恒电流充放电结果显示,材料在0.1C倍率下首周放电比容量为121.5 M AH·g-1,经过150周充放电后,材料比容量无明显衰减,其容量保持率为99%.用PITT和原位Xrd联用技术研究了充放电过程中材料的结构与锂离子扩散系数之间的关系.PITT法测得材料中锂离子的扩散系数为10-10~10-11CM2·S-1.The spinel Li Ni0.5Mn1.5O4 material was synthesized by co-precipitation method with Na OH as a precipitant.The structure and morphology of the as-prepared Li Ni0.5Mn1.5O4 materials were characterized by means of XRD, FTIR and SEM.The results indicated that the material belonged to Fd3軈m space group and consisted of octahedral particles with the sizes of 3 ~ 6 μm.Electrochemical tests showed the first discharge specific capacity of 121.5 m Ah·g-1at 0.1C.After 150 cycles, about 99% of reversible capacity was retained for the Li Ni0.5Mn1.5O4 material.A combining potentiostatic intermittent titration technique(PITT) with in-situ XRD measurement was applied for discussing the relationship between lattice parameter and the diffusion coefficient of lithium ion(DLi+) during the first charging-discharging processes.The DLi+value measured by PITT was in the range of 10-10~ 10-11cm2·s-1.国家自然科学基金项目(No.21273184;No.21321062); 973项目(No.2015CB251102)资

Aqueous Solution-Evaporation Route Synthesis and Phase Structural Research of the Li-Rich Cathode Li1.23Ni0.09Co0.12Mn0.56O2 by In-Situ XRD

采用水溶-蒸发法成功合成了锂离子电池Li1.23Ni0.09Co0.12Mn0.56O2正极材料. 通过扫面电镜(SEM)、非原位XRD、原位XRD观察材料形貌表征材料结构，并测试电极电化学性能. 结果显示，材料为粒径330 nm的多边形结构，是层状的固溶体—Li2MnO3结构，该正极0.1C首周期放电比容量250.8 mAh·g-1，40周期循环容量保持率86.5%. 通过原位XRD可确证电极在首周期充放电过程产生少量Li0.9MnO2新相，在其后多周期循环过程电极层状结构趋于向尖晶石结构发生转变致使电极电化学性能恶化. 此外，晶格参数c首周期充电过程先增后减在4.54 V左右保持稳定，放电与第2周期充电过程其值逐渐下降；晶格参数a则经历了下降平稳再升高的过程，该数值的变化均对应于相应电化学行为.The Li-rich Li1.23Ni0.09Co0.12Mn0.56O2 material was synthesized via aqueous solution-evaporation route. The structure and morphology of the material were characterized by means of XRD and SEM. The results indicated that the single particle of the product was polygonal with the size of 330 nm and the structure was layered solid solution with a certain amount of Li2MnO3. Electrochemical tests showed that the first discharge capacity of the Li-rich layered material was 250.8 mAh·g-1 at 0.1C，the capacity retention was 86.5% after 40 cycles. Through in-situ XRD study a new phase Li0.9MnO2 which would cause electrochemical properties deteriorated due to its structure transformation from layered to spinel came out with a small amount during the first charge-discharge cycle. Moreover, the value of c-parameter increased first and decreased before 4.54 V, and remained stable till the end of the first charge, and then reduced from the first discharge to the second charge continually. However, the value of a-parameter underwent a falling-steady-rising course. The change in the values of the lattice parameters corresponded to the variation of electrochemical behaviors.国家自然科学基金（No. 21273184）、科技部863（No. 2011AA11A254）和973（No. 2009CB220102）项目资助作者联系地址：1. 厦门大学化学化工学院化学系，福建 厦门 361005；2. 厦门大学能源研究院，福建 厦门 361005Author's Address: 1. Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Fujian Xiamen 361005; 2. School of Energy Research, Xiamen University, Fujian Xiamen 361005通讯作者E-mail：[email protected]

Structural and Dynamic Studies of Spinel LiNi0.5Mn1.5O4Cathode Material during Initial Charge/Discharge Processes

以NaOH为沉淀剂，采用共沉淀法制备尖晶石LiNi0.5Mn1.5O4正极材料，使用X-射线衍射（XRD）、傅里叶转换红外光谱（FTIR）和扫描电镜（SEM）分析材料结构与表面形貌. 结果表明，该材料属于空间群的无序尖晶石LiNi0.5Mn1.5O4材料，由八面体粒子团聚成3 ~ 6 μm的大粒子. 恒电流充放电结果显示，材料在0.1C倍率下首周放电比容量为121.5 mAh·g-1，经过150周充放电后，材料比容量无明显衰减，其容量保持率为99%. 用PITT和原位XRD联用技术研究了充放电过程中材料的结构与锂离子扩散系数之间的关系. PITT法测得材料中锂离子的扩散系数为10-10 ~ 10-11 cm2·s-1.The spinel LiNi0.5Mn1.5O4 material was synthesized by co-precipitation method with NaOH as a precipitant. The structure and morphology of the as-prepared LiNi0.5Mn1.5O4 materials were characterized by means of XRD、FTIR and SEM. The results indicated that the material belonged to space group and consisted of octahedral particles with the sizes of 3 ~ 6 μm. Electrochemical tests showed the first discharge specific capacity of 121.5 mAh·g-1 at 0.1C. After 150 cycles, about 99% of reversible capacity was retained for the LiNi0.5Mn1.5O4 material. A combining potentiostatic intermittent titration technique (PITT) with in-situ XRD measurement was applied for discussing the relationship between lattice parameter and the diffusion coefficient of lithium ion (DLi+) during the first charging-discharging processes. The DLi+ value measured by PITT was in the range of 10-10 ~ 10-11 cm2·s-1国家自然科学基金项目（No. 21273184，No. 21321062）及973项目（No. 2015CB251102）资助作者联系地址：1. 厦门大学化学化工学院化学系，福建 厦门 361005；2. 厦门大学能源研究院，福建 厦门 361005Author's Address: 1. Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China; 2. School of Energy Research, Xiamen University, Xiamen 361005, Fujian, China通讯作者E-mail：[email protected]