Microwave Synthesized In2S3@CNTs with Excellent Properties inLithium‐Ion Battery and Electromagnetic Wave Absorption

The three‐dimensional nanoflower‐like β‐In₂S₃ composited with carbon nanotubes (CNTs) has been synthesized by a single mode microwave‐assisted hydrothermal technique. The In₂S₃ and CNTs nanocomposites (In₂S₃@CNTs) were investigated as the anode materials of lithium batteries (LIBs) and the electromagnetic wave absorption materials. For LIBs applications, the In₂S₃@CNTs nanocomposite exhibited excellent cycling stability with a high reversible charge capacity of 575 mA⋅h⋅g^–1 after 300 cycles at 0.5 A⋅g^–1. In addition, the In₂S₃@CNTs used as electromagnetic wave absorber displayed a maximum reflection loss of –42.75 dB at 11.96 GHz with a thickness of 1.55 mm.     

Polyimides as cathodic materials in lithium batteries: Effect of the chemical structure of the diamine monomer

Polyimides are being investigated as alternative, environmentally friendly and safe organic electrode materials for lithium and sodium batteries. However, further improvements need the proper chemical design of these polymers. In this paper, the effect of chemical structure of polyimides on their performance as cathodic materials in lithium batteries was investigated in detail. More in particular, we studied polyimides based on seven different diamine monomers in combination with best performing naphthalenic dianhydride monomer. The first set included the so‐called cardo diamines possessing additional redox‐active carbonyl group with the goal to enhance the theoretical capacity of the polymer. Second, several aromatic diamines including additional functionalities such as cyclic amides, anthrone, or quinolidinium groups were investigated. Finally, aliphatic diamines, containing oxyethylene moieties and thus capable to increase the ionic conductivity of the resulting polymer system, were explored. Among the different polyimides, the “cardo” one based on naphthalenic dianhydride and aromatic aniline phthalein with an additional carbonyl group showed the best results in terms of battery performance. Such polyimide was capable to deliver up to 130 mAhg⁻¹ specific capacity (87% of the theoretical value) at 25 °C and at a current density of 250 mAg⁻¹ during 100 charge/discharge cycles. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 714–723     

电动汽车与锂离子电池

文章简要介绍了混合动力汽车、插电式混合动力汽车、纯电动汽车和锂离子动力电池及其关键材料。发展电动汽车可以大幅度降低人们对石油的依赖和改善城市空气质量。锂离子电池性能优越,为电动汽车的发展提供了支撑。近期,新一代锂离子动力电池正极材料即将走向应用,可使电动汽车里程增加一倍,材料选择和电池设计及制造工艺与电池储存能量、寿命、安全等密切相关, 尊道而重德,可做出“好”电池。     

Investigation on PVDF-HFP microporous membranes prepared by TIPS process and their application as polymer electrolytes for lithium ion batteries

Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) microporous membranes were prepared via thermally induced phase separation (TIPS) process. Then they were immersed in a liquid electrolyte to form polymer electrolytes. The effects of polymer content in casting solution on the morphology, crystallinity, and porosity of the membranes were studied by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and a mercury porosimeter, respectively. Ionic conductivity, lithium-ion transference number, and electrochemical stability window of corresponding polymer electrolytes were characterized by AC impedance spectroscopy, DC polarization/AC impedance combination method, and linear sweep voltammetry, respectively. The results showed that spherulites and “net-shaped” structure coexisted for the membranes. Polymer content had no effect on crystal structure of the membranes. The maximum transference number was 0.55. The temperature dependence of ionic conductivity followed the Vogel–Tammann–Fulcher (VTF) relation. The maximum ionic conductivity was 2.93 × 10⁻³ Scm⁻¹ at 20 °C. Electrochemical stability window was stable up to 4.7 V (vs. Li⁺/Li).     

Germanium‐Based Nanomaterials for Rechargeable Batteries

Germanium‐based nanomaterials have emerged as important candidates for next‐generation energy‐storage devices owing to their unique chemical and physical properties. In this Review, we provide a review of the current state‐of‐the‐art in germanium‐based materials design, synthesis, processing, and application in battery technology. The most recent advances in the area of Ge‐based nanocomposite electrode materials and electrolytes for solid‐state batteries are summarized. The limitations of Ge‐based materials for energy‐storage applications are discussed, and potential research directions are also presented with an emphasis on commercial products and theoretical investigations.     

Investigations of the catalytic properties of manganese oxides for the oxygen reduction reaction in alkaline media

The oxygen reduction reaction (ORR) was studied in KOH electrolyte on different manganese oxides, dispersed on a carbon powder (MnO_x/C). The oxides were prepared by different methods, for producing MnO, Mn₃O₄ and MnO₂ as major phases dispersed on the Vulcan XC-72 carbon. The oxides were characterized by XRD (X-ray diffraction) and in situ XANES (X-ray absorption near edge structure). The electrochemical measurements were made using cyclic voltammetry and steady state polarization curves carried out in an ultra-thin layer rotating ring/disk electrode. The results have shown lower activity for the ORR on the MnO_x/C species compared to that on Pt/C, but higher activity compared to that of pure Vulcan carbon. Formation of involving 2e⁻ per O₂ molecule is the main path of the ORR in the studied MnO_x/C catalysts but, at low overpotentials and rotation rates the number of electrons is raised to 4 due to the occurrence of a disproportionation reaction. Large differences of electrocatalytic activity were seen for the different oxide species, and these were related to the presence of a Mn(IV) phase and the occurrence of a mediation processes involving the reduction of Mn(IV) to Mn(III), followed by the electron transfer of Mn(III) to oxygen.     

Detecting unalloyed tin in LiSn2(PO4)3-based anodes with Mössbauer spectroscopy

The first discharge of the Li⁺ ion anode material LiSn₂(PO₄)₃ was investigated with Mössbauer spectroscopy and electrochemical techniques. Mössbauer spectroscopy provided insight into the structure of the tin atoms of the fully discharged anode materials. Spectra consist of overlapping peaks, which are assigned to noncrystalline β-Sn and Li–Sn alloy domains. An analysis of the relative intensities of the Mössbauer spectra shows the relative abundance of β-Sn increases at the expense of the Li–Sn alloy as the discharge rate increases. Cell polarization occurs at higher discharge rates, leading to inefficient electrode utilization and poor cycling performance. Sluggish Li⁺ ion diffusion through the amorphous Li₃PO₄ network that is formed early in the discharge process might be responsible for the poor electrochemical performance and the accumulation of unalloyed tin.     

Structural and electrochemical properties of high-capacity Ml-Mg-Ni-based hydrogen storage alloys

The Ml-Mg-Ni-based (Ml = La-rich mixed lanthanide) hydrogen storage alloy Ml_0.88Mg_0.12Ni_3.0-Mn_0.10Co_0.55Al_0.10 was prepared by inductive melting. The micro-structure was analyzed by XRD and SEM. The alloy consists mainly of CaCu₅-type phase, Ce₂Ni₇-type phase and Pr₅Co₁₉-type phase. The electrochemical measurements show that the maximum discharge capacity is 386 mAh/g, 16.3% higher than that of the commercial AB₅-type alloy (332 mAh/g). At discharge current density of 1 100 mA/g, high rate dischargeability is 62%, while that of the AB5-type alloy is only 45%. The discharge capacity decreases to 315 mAh/g after 300 charge/ discharge cycles, 81.5% of the maximum discharge capacity. __________ Translated from Journal of Xi’an Jiao Tong University, 2008, 42(3) (in Chinese)