锂离子电池电极材料表界面结构的原子尺度表征

锂离子电池充放电过程中,锂离子的传输要穿过多种表面和界面,表界面的性质对电池的功率密度、能量密度、充放电效率、使用寿命、循环稳定性等具有重要的影响。表界面一般具有与体相不同的结构,在原子尺度上直接观察不同电化学状态下电极表界面的结构,有助于从更深层次认识电化学反应机理和性能演化规律,对于改善锂离子电池性能具有重要的指导意义。阐述了球差校正透射电子显微成像技术在研究电极材料表界面结构原子尺度研究中的应用,介绍了特殊的相界面、SEI、表面相变、表面掺杂等,探讨了表界面原子尺度结构与性能的内在关联,提出了改善电池性能的针对性建议,并对锂离子电池未来的发展从提高能量密度、避免固液界面副反应和改善电池性能三个方面进行了展望。

锂离子电池含硫无机电极材料研究进展

锂离子电池含硫无机电极材料包括二元金属硫化物、硫氧化物、Chevrel相化合物、尖晶石硫化物、聚阴离子型磷硫化物等。综述了含硫无机材料作为锂离子电池电极材料的研究现状,展望其发展趋势,并指出聚阴离子型磷硫化物等新型材料的重大研究价值。

金属有机骨架(MOFs)作为电极材料在二次锂离子电池中的应用

金属有机骨架(MOFs)具有独特且稳定的多孔纳米结构,它有容量大、稳定性高、种类丰富等优点,是一种很有潜力的锂离子电池电极材料。本文对MOFs材料及其衍生材料作为锂离子电池负极和正极材料的相关研究工作分别进行了论述,同时对其发展方向和应用前景进行了展望。

Synthesis of Ni_(0.8)Co_(0.1)Mn_(0.1)(OH)_2 precursor and electrochemical performance of LiNi_(0.8)Co_(0.1)Mn_(0.1)O_2 cathode material for lithium batteries

Spherical and homogeneously mixed metal hydroxide Ni0.8Co0.1Mn0.1（OH）2 precursor was successfully synthesized by co-precipitation method in a simple and small vessel with the volume of 1L.The conditions of synthetic process including amount of chelating agent,stirring speed and temperature were studied.LiNi0.8Co0.1Mn0.1O2 samples were obtained by calcinating the precursors.The crystal structure,morphology and electrochemical properties were investigated by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,charge-discharge test,AC impedance and cyclic voltammetry.In the voltage range of 2.8-4.3 V,the initial discharge capacities of LiNi0.8Co0.1Mn0.1O2 at 0.1C and 1C rates were 199 and 170 mA·h/g,respectively.After 80 cycles at 1C,the discharge capacity retention was 92%,suggesting its promising application as the cathode material for Li-ion batteries.

Synthesis and properties of single-crystal Ni-rich cathode materials in Li-ion batteries

Single-crystal Ni-rich cathode material LiNi0.88Co0.09Al0.03O2(SC) was synthesized by a high-temperature solid-state calcination method. Physicochemical properties of primary and delithiated SC samples were investigated by X-ray diffractometry, X-ray photoelectron spectroscopy, and transmission electron microscopy. Electrochemical performance was characterized by long-term cycling, cyclic voltammetry, and in-situ impedance spectroscopy. The results indicated that high temperature rendered layered oxides to lose lithium/oxygen in the interior and exterior, and induced cationic disordering. Besides, the solid-phase synthesis process promoted phase transformation for electrode materials, causing the coexisting multi-phase in a single particle. High temperature can foster the growth of single particles, but it caused unstable structure of layered phase.

Facile synthesis of hierarchically structured manganese oxides as anode for lithium-ion batteries

Developing high-performance lithium ion batteries(LIBs)using manganese oxides as anodes is attractive due to their high theoretical capacity and abundant resources.Herein,we report a facile synthesis of hierarchical spherical MnO2 containing coherent amorphous/crystalline domained by a simple yet effective redox precipitation reaction at room temperature.Further,flower-like CoMn2O4 constructed by single-crystalline spinel nanosheets has been fabricated using MnO2 as precursor.This mild methodology avoids undesired particle aggregation and loss of active surface area in conventional hydrothermal or solid-state processes.Moreover,both MnO2 and CoMn2O4 nanosheets manifest superior lithium-ion storage properties,rendering them promising applications in LIBs and other energy-related fields.

Enhancement of lithium storage capacity and rate performance of Se-modified MnO/Mn3O4 hybrid anode material via pseudocapacitive behavior

To improve rate and cycling performance of manganese oxide anode material,a precipitation method was combined with thermal annealing to prepare the Mn O/Mn3O4/Se Ox(x=0,2)hybrid anode by controlling the reaction temperature of Mn2O3 and Se powders.At 3 A/g,the synthesized Mn O/Mn3O4/Se Ox anode delivers a discharge capacity of 1007 m A·h/g after 560 cycles.A cyclic voltammetry quantitative analysis reveals that 89.5%pseudocapacitive contribution is gained at a scanning rate of 2.0 m V/s,and the test results show that there is a significant synergistic effect between Mn O and Mn3O4 phases.

Preparation and effects of W-doping on electrochemical properties of spinel Li_4Ti_5O_(12) as anode material for lithium ion battery

W-doped Li4TisO12 in the form of Li4Ti4.95W0.osO12 was firstly synthesized via solid state reaction. X-ray diffraction （XRD） and scanning electron microscope （gEM） were employed to characterize the structure and morphology of Li4Ti4.psW0.05Ol2. W-doping does not change the phase composition and particle morphology, while remarkably improves its cycling stability at high charge/discharge rate. Li4Ti4.95W0.05O12 exhibits an excellent rate capability with a reversible capacity of 131.2 mA.h/g at 10C and even 118.6 mA.h/g at 20C. The substitution of W for Ti site can enhance the electronic conductivity of Li4TisO12 via the generation of mixing Ti4＋/Ti3＋, which indicates that Li4Ti4.psW0.05O12 is promising as a high rate anode for the lithium-ion batteries.

Effects of carbon sources on electrochemical performance of Li_4Ti_5O_(12)/C composite anode materials

Li4Ti5O12/C composite materials were synthesized by two-step solid state reaction method with glucose, sucrose, and starch as carbon sources, respectively. The effects of carbon sources on the structure, morphology, and electrochemical performance of Li4Ti5O12/C composite materials were investigated by SEM, XRD and electrochemical tests. The results indicate that carbon sources have almost no effect on the structure of Li4Ti5O12/C composite materials. The initial discharge capacities of the Li4Ti1O12/C composite materials are slightly lower than those of as-synthesized Li4Ti5O12. However, Li4Ti5O12/C composite materials show better electrochemical rate performance than the as-synthesized Li4Ti5O12. The capacity retention （79%） of the Li4Ti5O12/C composite materials with starch as carbon source, is higher than that of Li4Ti5O12/C composite materials with glucose and sucrose as carbon source at current rate of 2.0C.

Synthesis and electrochemical characterization of LiNi_(0.78)Co_(0.2)Al_(0.02)O_2 cathode material in a novel co-precipitation method

LiNi0.78 Co0.2 Al0.02O2 cathode materials were prepared with a novel co-precipitation method followed by heat-treating. The properties of the materials were characterized. XRD patterns showed that no secondary phase appeared and the hexagonal lattice parameter c of LiNi0.rsCoo.2AI^0202 was larger than that of LiNi0.8Co0.2O2. The SEM images indicated that the powders of the material were submicron size. The results of the ICP-AES analysis proved that elemental compositions of the material were similar to those of the targeted one. Cyclic voltammetry （3.0- 4. 2 V） illustrated that the new material had good lithium-ion intercalation/de-intercalation performance. The results of galvanostatic cycling showed that the initial specific discharge capacity of the prepared material was 181.4 mAh/g, and the specific discharge capacity was 177.3 mAh/g after 100 cycles （0. 2C, 3.0 - 4. 2 V, vs. Li^＋/Li） with the capacity retention ratio of 97.7%.

Synthesis and electrochemical performance of Li_3V_2(PO_4)_3 by optimized sol-gel synthesis routine

Li3V2（PO4）3 samples were synthesized by sol-gel route and high temperature solid-state reaction. The influence of Li3V2（PO4）3 as cathode materials for lithium-ion batteries on electrochemical performances was investigated. The structure of Li3Va（PO4）3 as cathode materials for lithium-ion batteries and morphology of Li3V2（PO4）3 were characterized by X-ray diffractometry （XRD） and scanning electron microscopy （SEM）. Electrochemical performances were characterized by charge/discharge and AC impedance measurements. Li3V2（PO4）3 with smaller grain size shows better performances in terms of the discharge capacity and cycle stability. The improved electrochemical properties of Li3V2（PO4）3 are attributed to the refined grains and enhanced electrical conductivity. AC impedance measurements also show that the Li3V2（PO4）3 synthesized by sol-gel route exhibits significantly decreased charge-transfer resistance and shortened migration distance of lithium ions.

Orthorhombic 3-LiV2O5 as Cathode Materials in Lithium Ion Batteries： Synthesis and Property

The rod-like and bundle-like v-LiV205 were synthesized via a simple solvothermal process- ing. The rod-like 7-LiV205 with diameter of 500-800 nm and the bundle-like architectures are composed of several of order-attached rods with diameter of 100-600 nm. ＂y-LiV205 were synthesized using LiOH.H20, NH4VO3, HNO3, C2H5OH without and with PVP as raw materials. At the same time, the actual formation mechanism of Y-LiV205 was also investigated. As the cathode materials for lithium ion batteries, the bundle-like Y-LiV205 prepared with PVP delivers a better electrochemical performance, which has an initial dis charge capacity of 269.3 mAh/g at a current density of 30 mA/g and is still able to achieve 228 mAh/g after the 20th cycle. The good electrochemical properties of the as-synthesized Y-LiV205 coupled with the simple, relatively low temperature, and low cost of the prepara tion method may make this material a promising candidate as a cathode material for lithium ion batteries.

Preparation and electrochemical properties of Co_3O_4/graphite composites as anodes of lithium ion batteries

Co3O4/graphite composites were synthesized by precipitation of cobalt oxalate on the surface of graphite and pyrolysis of the precipitate, and the effects of graphite content and calcination temperature on the electrochemical properties of the composites were investigated. The samples were characterized by thermogravimetry and differential thermal analysis （TG/DTA）, X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, cyclic voltammetry （CV）, electrochemical impedance spectroscopy （EIS） and charge/discharge measurements. With increasing the graphite content, the reversible capacity of the Co3O4/graphite composites decreases, while cycling stability improves dramatically, and the addition of graphite obviously decreases the average potential of lithium intercalation/deintercalation. The reversible capacity of the composites with 50% graphite rises from 583 to 725 mA-h/g as the calcination temperature increases from 300 to 500 ℃, and the Co304/graphite composites synthesized at 400 ℃ show the best cycling stability without capacity loss in the initial 20 cycles. peaks, corresponding to the lithium intercalaction/deintercalation for The CV profile of the composite presents two couples of redox graphite and Co3O4, respectively. EIS studies indicate that the electrochemical impedance decreases with increasing the graphite content.

Synthesis and electrochemical performance of Li_2Mg_(0.15)Mn_(0.4)Co_(0.45)SiO_4/C cathode material for lithium ion batteries

The synthesis, structure and performance of Li2Mg0.15Mn0.4Co0.45SiO4/C cathode material were studied. The Li2Mg0.15Mn0.4Co0.45SiO4/C solid solution with orthorhombic unit cell （space group Pmn21） was synthesized successfully by combination of wet process and solid-state reaction at high temperature, and its electrochemical performance was investigated primarily. Li2Mg0.15Mn0.4Co0.45SiO4/C composite materials deliver a charge capacity of 302 mA-h/g and a discharge capacity of 171 mA.h/g in the first cycle. The discharge capacity is stabilized at about 100 mA-h/g after 10 cycles at a current density of 10 mA/g in the voltage of 1.5-4.8 V vs Li/Li^＋. The results show that Mg-substitution for the Co ions in Li2Mn0.4Co0.6SiO4 improves the stabilization of initial structure and the electrochemical nerformance.

Preparation and electrochemical performance of Li_2Mn_(0.5)Fe_(0.5)SiO_4 cathode material with sol-gel method for lithium ion batteries

Li2Fe0.5Mn0.5SiO4 material was synthesized by a citric acid-assisted sol-gel method. The influence of the stoichiometric ratio value of n(citric acid) to n(Fe2+-Mn2+) on the electrochemical properties of Li2Fe0.5Mn0.5SiO4 was studied. The final sample was identified as Li2Fe0.5Mn0.5SiO4 with a Pmn21 monoclinic structure by X-ray diffraction analysis. The crystal phases components and crystal phase structure of the Li2Fe0.5Mn0.4SiO4 material were improved as the increase of the stoichiometric ratio value of n(citric acid) to n(Fe2+-Mn2+). Field-emission scanning electron microscopy verified that the Li2Fe0.5Mn0.5SiO4 particles are agglomerates of Li2Fe0.5Mn0.5SiO4 primary particles with a geometric mean diameter of 220 nm. The Li2Fe0.5Mn0.5SiO4 sample was used as an electrode material for rechargeable lithium ion batteries, and the electrochemical measurements were carried out at room temperature. The Li2Fe0.5Mn0.5SiO4 electrode delivered a first discharge capacity of 230.1 mAh/g at the current density of 10 mA/g in first cycle and about 162 mAh/g after 20 cycles at the current density of 20 mA/g.

Evaluating the performance of nanostructured materials as lithium-ion battery electrodes

The performance of the lithium-ion cell is heavily dependent on the ability of the host electrodes to accommodate and release Li＋ ions from the local structure. While the choice of electrode materials may define parameters such as cell potential and capacity, the process of intercalation may be physically limited by the rate of solid-state Li＋ diffusion. Increased diffusion rates in lithium-ion electrodes may be achieved through a reduction in the diffusion path, accomplished by a scaling of the respective electrode dimensions. In addition, some electrodes may undergo large volume changes associated with charging and discharging, the strain of which, may be better accommodated through nanostructuring. Failure of the host to accommodate such volume changes may lead to pulverisation of the local structure and a rapid loss of capacity. In this review article, we seek to highlight a number of significant gains in the development of nanostructured lithium-ion battery architectures （both anode and cathode）, as drivers of potential next-generation electrochemical energy storage devices.

Cu_2O nanowires as anode materials for Li-ion rechargeable batteries

Li-ion batteries are a key technology for multiple clean energy applications.In this study,Cu2O nanowires were obtained by the reduction of cupric acetate with pyrrole.The resulting Cu2O nanowires exhibited excellent reversible capacities of 470mAh g-1 at rate of 1 C after 100 cycles.The results show that the Cu2O nanowires had more capacity than materials previously reported.No fading was observed over 100 cycles of charging and discharging.The compound metal Cu and incorporation of the conducting polymer polypyrrole(PPy)improved the conductivity of Cu2O and enhanced the stability of the electrode during cycling.The results from this study imply that Cu2O nanowires with high capacity and good cycle retention could be excellent candidates as anode materials for Li-ion rechargeable batteries.

The strategies of advanced cathode composites for lithium-sulfur batteries

Lithium-sulfur batteries have been widely nominated as one of the most promising next-generation electrochemical storage systems due to its low cost, high capacity and energy density. However, its practical application is still hindered by poor cycling lifetime, low Coulombic efficiency, instability and small scales. In the last decade, the electrochemical performances of the lithium-sulfur batteries have been improved by developing various novel nanoarchitectures as qualified hosts, and enhancing the sulfur loading with effective encapsulating strategies. The review summarizes the major sulfur cooperating strategies of cathodes based on background and latest progress of the lithium-sulfur batteries. The novel cooperating strategies of physical techniques and chemical synthesis techniques are discussed in detail. Based on the rich chemistry of sulfur, we paid more attention to the highlights of sulfur encapsulating strategies. Furthermore, the critical research directions in the coming future are proposed in the conclusion and outlook section.

Anisotropic lithium-ion migration and electro-chemo-mechanical coupling in Sb_(2)Se_(3) single crystals

Harvesting the promising high energy density of advanced electrode materials in lithium-ion batteries is critically dependent on a mechanistic understanding on how the materials function and degrade along with the battery cycling.Here,we tracked phase transformations during(de)lithiation of Sb_(2)Se_(3) single crystals using in situ high-resolution transmission electron microscopy(HRTEM)technique,and revealed electro-chemo-mechanical evolution at the reaction interface.The effect of this electro-chemo-mechanical coupling has a complicated interplay on the lithiation kinetics and causes various types of defects at the reaction front,including dislocation dipoles,antiphase boundaries,and cracks.In return,the formed cracks and related defects build a path for fast diffusion of lithium ions and trigger a highly anisotropic lithiation at the twisted reaction front,giving rise to the formation of presumably "dead" Sb_(2)Se_(3) nanodomains in amorphous Li_(x)Sb_(2)Se_(3).The detailed mechanistic understanding may facilitate the rational design of high-capacity electrode materials for battery applications.

Thiourea-based polyimide/RGO composite cathode:A comprehensive study of storage mechanism with alkali metal ions

Although organic electrode materials have merits of abundant resources,diverse structures and environmental friendliness,their performance for electrochemical energy storage is far insufficient.In this work,a thiourea-based polyimide/reduced graphene oxide(PNTCSA/RGO)composite was synthesized via a condensation polymerization method.As a cathode material in lithium-ion batteries,excellent performance is demonstrated with high reversible capacity(144.2 mA h g^−1),high discharge voltage(∼2.5 V),and long cycling life(over 2000 cycles at 500 mA g^−1),which are comparable to those of other well documented in organic electrodes.Encouraging electrochemical performance is also demonstrated for sodium ion batteries(a cycling life of 800 cycles at 500 mA g^−1),while poor performance is delivered in potassium ion batteries.Theoretical studies reveal that the active sites are carbonyl groups for all alkali ions but one inserted alkali metal ion is shared by two carbonyl groups from the two neighbor units.More importantly,K ions have stronger interaction with S atoms than Li/Na ions,which may lead to poor structure reversibility and account for the poor cycling performance.Our findings provide a fundamental understanding of polyimide based polymer electrodes and help to design and develop high performance organic electrode materials for alkali metal ion batteries.