Thermal regimes of Li‐ion conductivity in β‐eucryptite

While it is well‐established that ionic conduction in lithium aluminosilicates proceeds via hopping of Li ions, the nature of the various hoping‐based mechanisms in different temperature regimes has not been fully elucidated. The difficulties associated with investigating the conduction have to do with the presence of grains and grain boundaries of different orientations in these usually polycrystalline materials. Herein, we use electrochemical impedance spectroscopy (EIS) to investigate the ion conduction mechanisms in β‐eucryptite, which is a prototypical lithium aluminosilicate. In the absence of significant structural transitions in grain boundaries, we find that there are three conduction regimes for the one‐dimensional ionic motion along the c axis channels in the grains, and determine the activation energies for each of these temperature regimes. Activation energies computed from molecular statics calculations of the potential energy landscape encountered by Li ions suggest that at temperatures below 440°C conduction proceeds via cooperative or correlated motion, in agreement with established literature. Between 440°C and 500°C, the activation barriers extracted from EIS measurements are large and consistent with those from atomistic calculations for uncorrelated Li ion hopping. Above 500°C the activation barriers decrease significantly, which indicates that after the transition to the Li‐disordered phase of β‐eucryptite, the Li ion motion largely regains the correlated character.     

Elimination of boron and lithium coexisting in geothermal water by adsorption-membrane filtration hybrid process

Direct release of geothermal waters to the environment may cause some damages to some plants because they contain toxic species such as boron, arsenic, fluoride etc. along with valuable minerals including lithium. In this study, a hybrid process combining adsorption and membrane filtration was used to separate boron and lithium simultaneously from geothermal water. According to the results obtained, separation efficiencies for lithium and boron from geothermal water were 100% and 83% using boron selective ion exchange resin Dowex XUS-43594.00 and lithium selective λ-MnO₂ adsorbent, respectively. The kinetic data of lithium and boron adsorption have been evaluated using pseudo-first order and pseudo-second-order kinetic models.     

基于UKF和AH法的磁悬浮人工心脏泵用锂电池SOC估计复合算法

针对锂电池的非线性特性,提出电池状态模型在不同循环次数、不同温度下的具体改进方法;提出安时积分法和无迹卡尔曼滤波算法结合的锂电池荷电状态(state of charge, SOC)复合估计算法,分析新算法的收敛速度、估计精度以及算法复杂度。试验表明,这种复合算法复杂度低,精度高,能快速实现锂电池SOC的准确估计,估算误差为4.036 2%,适合实时在线计算。     

Conductive Nanocrystalline Niobium Carbide as High‐Efficiency Polysulfides Tamer for Lithium‐Sulfur Batteries

Rational design of functional interlayer is highly significant in pursuit of high‐performance Li‐S batteries. Herein, a nanocrystalline niobium carbide (NbC) is developed via a facile and scalable autoclave technology, which is, for the first time, employed as the advanced interlayer material for Li‐S batteries. Combining the merits of strong polysulfides (PS) anchoring with high electric conductivity, the NbC‐coated membrane enables efficiently tamed PS shuttling and fast sulfur electrochemistry, achieving outstanding cyclability with negligible capacity fading rate of 0.037% cycle^?1 over 1500 cycles, superb rate capability up to 5 C, high areal capacity of 3.6 mA h cm^?2 under raised sulfur loading, and reliable operation even in soft‐package cells. This work offers a facile and effective method of promoting Li‐S batteries for practical application.     

Copper Sulfide (CuxS) Nanowire‐in‐Carbon Composites Formed from Direct Sulfurization of the Metal‐Organic Framework HKUST‐1 and Their Use as Li‐Ion Battery Cathodes

Li‐ion batteries containing cost‐effective, environmentally benign cathode materials with high specific capacities are in critical demand to deliver the energy density requirements of electric vehicles and next‐generation electronic devices. Here, the phase‐controlled synthesis of copper sulfide (Cu_xS) composites by the temperature‐controlled sulfurization of a prototypal Cu metal‐organic framework (MOF), HKUST‐1 is reported. The tunable formation of different Cu_xS phases within a carbon network represents a simple method for the production of effective composite cathode materials for Li‐ion batteries. A direct link between the sulfurization temperature of the MOF and the resultant Cu_xS phase formed with more Cu‐rich phases favored at higher temperatures is further shown. The Cu_xS/C samples are characterized through X‐ray diffraction (XRD), thermogravimetric analysis (TGA), transmission electron microscopy, and energy dispersive X‐ray spectroscopy (EDX) in addition to testing as Li‐ion cathodes. It is shown that the performance is dependent on both the Cu_xS phase and the crystal morphology with the Cu_1.8S/C‐500 material as a nanowire composite exhibiting the best performance, showing a specific capacity of 220 mAh g^?1 after 200 charge/discharge cycles.     

A poly(ethylene terephthalate) nonwoven sandwiched electrospun polysulfonamide fibrous separator for rechargeable lithium ion batteries

A poly(ethylene terephthalate) nonwoven sandwiched electrospun polysulfonamide (PSA) fibrous separator was developed for application in lithium‐ion batteries (LIBs). The poly(ethylene terephthalate) nonwoven served as a mechanical support and the PSA layers provided the separators with nanoporous structures. This novel composite separator possessed better thermal stability and electrolyte wettability than commercial polypropylene separator and the sandwiched nonwoven endowed the separator with an improved mechanical strength (17.7 MPa) compared to the pure electrospun PSA separator. The cells assembled with this composite separator displayed excellent discharge capacity (122.0 mAh g^?1 after 100 cycles) and discharge C‐rate capacity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44907.     

From hydrated layered-spinel lithium manganate composite to high-performance spinel LiMn2O4: A novel synthesis tuned by the concentration of LiOH

To obtain high-performance spinel LiMn₂O₄, various types of hydrated layered-spinel lithium manganate composites have been controllably synthesized through the hydrothermal process. It is found that the composition and morphology of these intermediate products can be tuned by the concentration of LiOH: Li⁺ act as the template and OH^- provide the required alkaline environment. In particular, the nanostructure varies from nanowires to nanosheets at different levels, depending on the phase ratio of the spinel phase ranging from 0% to 100%. Phase purity and the corresponding electrochemical properties of the as-prepared LiMn₂O₄ products are further tailored through the subsequent heat treatment. With the optimized LiOH concentration of 0.08 M, the resulting LiMn₂O₄ cathode material exhibits the best electrochemical performance with the initial discharge capacity of 121.7 mA h g⁻¹ at 1 C and 117.8 mA h g⁻¹ at 30 C, while a retention over 90% can be achieved after 1500 cycles. This study will help deepen understanding of the function mechanisms and further direct the novel synthesis from hydrated layered-spinel lithium manganate composites to high-performance spinel LiMn₂O₄ cathode materials.     

缓冲质子源LiNbO3波导折射率计算及实验

为实现铌酸锂退火质子交换(APE)波导折射率分布的准确计算,选择含苯甲酸锂的苯甲酸缓冲液作为质子交换质子源,高温退火制作了波导样本.针对该工艺过程建立退火质子交换波导模型,包括非线性扩散模块和光学数值仿真模块,分别计算APE波导折射率及其模式有效折射率.以测得的样本波导模式有效折射率和计算的有效折射率差的均方根构建评价函数(FOM),结合遗传算法提取该工艺条件下质子扩散参数,实现了不同交换深度和退火时间波导折射率分布及其光学特性的一体化计算.实验表明:FOM小于0.001,计算折射率分布同IWKB方法测得结果吻合较好,最大偏差约0.002.     

Multi‐Atomic Layers of Metallic Aluminum for Ultralong Life Lithium Storage with High Volumetric Capacity

Metallic aluminum (Al) have been explored as potential anode materials for lithium storage because of its high theoretical capacity (993 mAh g^–1) and low voltage plateaus. Al possesses high electric conductivity, low cost and environmental friendliness. Unfortunately, Al suffers from huge volume change (>100%) during the lithiation/delithiation process, which inevitably results in the pulverization of electrode and rapid capacity decay during cycling processes. To circumvent above issues, a simple but efficient strategy is demonstrated to fabricate free‐standing multi‐atomic layers of metallic Al by harnessing the good ductility of Al under pressure. The resultant multi‐atomic Al layers are ultrathin, ≈3 nm, and have a large aspect ratio. Such unique features enable multi‐atomic Al nanosheets to construct uniform and compact films with graphene. Thus, the hybrid films with different ratios are achieved, in which the notorious volume change of metallic Al can be efficiently circumvented via the good flexibility of graphene, and the density of whole electrode can be significantly enhanced. As a consequence, the optimized multi‐atomic Al layers‐graphene (AlL‐G) film exhibits a very high volumetric capacity of 1089 mAh cm^–3, high‐rate capability and ultralong cycle life up to 20 000 cycles for lithium storage.     

Prestoring Lithium into Stable 3D Nickel Foam Host as Dendrite‐Free Lithium Metal Anode

Lithium metal is considered a “Holy Grail” of anode materials for high‐energy‐density batteries. However, both dendritic lithium deposition and infinity dimension change during long‐term cycling have extremely restricted its practical applications for energy storage devices. Here, a thermal infusion strategy for prestoring lithium into a stable nickel foam host is demonstrated and a composite anode is achieved. In comparison with the bare lithium, the composite anode exhibits stable voltage profiles (200 mV at 5.0 mA cm^?2) with a small hysteresis beyond 100 cycles in carbonate‐based electrolyte, as well as high rate capability, significantly reduced interfacial resistance, and small polarization in a full‐cell battery with Li₄Ti₅O₁₂ or LiFePO₄ as counter electrode. More importantly, in addition to the fact that lithium is successfully confined in the metallic nickel foam host, uniform lithium plating/stripping is achieved with a low dimension change (merely ≈3.1%) and effective inhibition of dendrite formation. The mechanism for uniform lithium stripping/plating behavior is explained based on a surface energy model.