A polyaniline and Nafion® composite film as a rechargeable battery

The charge-discharge characteristics of polyaniline (PAn)-Nafion^®-PAn composite films used as rechargeable batteries were investigated. The batteries were formed chemically by sandwiching Nafion^® between two thin layers of PAn-Nafion^® composite in equilibrium with various electrolytes. It was found that cells with LiClO₄ in propylene carbonate as electrolyte showed the highest capacity. The charge and discharge performance of the battery was almost independent of the choice of anions but was significantly affected by cation size. This may indicate that the insertion or removal of charge-compensating electrolyte cations from the composite layer was responsible for the redox of PAn during the charge and discharge cycles.     

Synthesis and characterization of olivine LiNiPO4 for aqueous rechargeable battery

LiNiPO₄ belongs to a family of olivine type compounds, with members LiMPO₄ where M = Fe, Mn, Co or Ni are transition metals. The lithium nickel phosphate was prepared and characterized in order to evaluate a new potential cathode material for our ongoing research in aqueous rechargeable batteries. Annealing the final product is critical in obtaining the stoichiometric LiNiPO₄ pure phase; conventional cooling to a room temperature leads to an indication of Li₃PO₄ and NiO secondary phases as impurities. The synchrotron infrared radiation (SR-IR) as a source for IR spectroscopy pins down the differences in the chemical bonding for annealed and conventional cooled LiNiPO₄ samples. The cyclic voltammetric and galvanostatic studies showed annealed LiNiPO₄ is electrochemically active from which lithium ions can be de-intercalated during oxidation process leading to an amorphous NiPO₄ and a minor product of nickel(II) hydroxide (β-NiOOH). During subsequent reduction, lithium ions are not fully intercalated, however, the structure is reversible and adequate for multiple cycles. The high potential in LiNiPO₄ looks to be very attractive in terms of high energy density, given the efficiency is improved.     

Li-LiFePO4 rechargeable polymer battery using dual composite polymer electrolytes

A composite polymer electrolyte, formed by dispersing into a poly(ethylene oxide)-lithium salt matrix two additives, i.e. calyx(6)pyrrole, (CP) acting as an anion trapper and superacid zirconia, S-ZrO₂ acting as a conductivity promoter, has been tested as a separator in a new type of rechargeable lithium battery using lithium iron phosphate as the cathode. The choice of the electrolyte was motivated by its favourable transport properties both in terms of lithium ion transference number and of total ionic conductivity. The choice of the cathode was motivated by the value of its operating voltage which falls within the stability window of the electrolyte. The performance of the battery was determined by cycling tests carried out at various rates and at various temperatures. The results demonstrate the good rate capability of the battery which can operate at high charge-discharge efficiency even at 1 C rate and that it can be cycled at 90 °C with a satisfactory initial capacity of the order of 90 mAh g⁻¹. These values outline the practical relevance of the composite electrolyte membrane and of its use as separator in a lithium battery. H. H. Sumathipala—On leave from Department of Physics University of Kelaniya, Kelaniya, Sri Lanka.     

Performance improvement of a MH/MnO2 rechargeable battery

Several important features have been introduced to make the MH/MnO₂ system competitive with other rechargeable batteries. These include improvement in cell construction, the adoption of a good hydrophilic separator, the adoption of a new charging regime and the substitution of the multicycle step formation procedure for the single-cycle step formation procedure. Test results show that the performance of the MH/MnO₂ cell is significantly improved. 400 cycles can be expected at 100 DOD and 1100 cycles can be obtained at 60 DOD. The high rate capability of the MH/MnO₂ cell is also improved.     

锂离子二次电池电解质四氟硼酸锂制备技术研究进展

四氟硼酸锂由于具有较好的热稳定性,因而在锂离子二次电池电解液中的使用比例越来越大。介绍了国内外锂离子二次电池电解质四氟硼酸锂的制备技术研究进展,包括4种制备方法,即气-固反应法、水溶液法、混合溶剂法、氟化氢溶液反应法。总结了各种制备方法的优缺点,并且展望了四氟硼酸锂的发展方向。指出制备高纯度的四氟硼酸锂将是未来的研究重点之一,同时四氟硼酸锂在离子液体中的使用,以及和其他新型锂盐特别是含氟磺酰锂盐的配合使用都将是今后的研究重点。     

Development of a 100 W rechargeable bipolar zinc/oxygen battery

A bipolar filter press-type electrically rechargeable Zn/O2 battery has been developed. Reticulated copper foam served as substrate for the zinc deposit on the anodic side, and La0.6Ca0.4CoO3-catalysed bifunctional oxygen electrodes were used on the cathodic side of the cells. The 100cm2 unit cell had an open circuit voltage of 1.4V (O2) in moderately alkaline electrolyte. The open circuit voltage and the peak power measured for a stack containing seven cells were sim 10V and sim 90W, respectively. The current-potential behaviour was determined as a function of the number of bipolar cells, and the maximum discharge capacity was determined at different discharge rates.     

Cathodic performance of VOPO4 with various crystal phases for Li ion rechargeable battery

Cathodic performance of six different VOPO₄ phases for Li ion rechargeable battery was investigated. It was found that VOPO₄ exhibits a high flat discharge potential of 3.7 V for Li ion electrochemical intercalation and de-intercalation excepting for β- and ε-types. On the other hand, slightly higher flat discharge potential of 3.9 and 3.8 V was observed for β- and ε-types. Capacity for Li intercalation is strongly related with the crystal structure of VOPO₄. In particular, δ-phase exhibits the largest reversible capacity of ca. 130 mAh/g among the examined VOPO₄. High capacity for Li intercalation in δ-phase VOPO₄ hardly decreased over 30 times of charge and discharge cycles. Although the reversible capacity decreased with increasing the current density for charge and discharge, large capacity of 80 mAh/g was still sustained at 0.4 mA/cm² for δ-type VOPO₄.     

可充镁电池电解质研究现状

综述了可充镁电池电解质材料的研究进展;介绍了有机格氏试剂盐系列电解质和可传导镁离子的聚合物电解质(GPE);简述了相应的制备工艺和存在的主要问题;最后提出可充镁电池电解质的发展趋势.     

Intercalation dynamics in rechargeable battery materials: General theory and phase-transformation waves in LiFePO4

A general continuum theory is developed for ion intercalation dynamics in a single crystal of rechargeable-battery composite electrode material. It is based on an existing phase-field formulation of the bulk free energy and incorporates two crucial effects: (i) anisotropic ionic mobility in the crystal and (ii) surface reactions governing the flux of ions across the electrode/electrolyte interface, depending on the local free energy difference. Although the phase boundary can form a classical diffusive “shrinking core” when the dynamics is bulk-transport-limited, the theory also predicts a new regime of surface-reaction-limited (SRL) dynamics, where the phase boundary extends from surface to surface along planes of fast ionic diffusion, consistent with recent experiments on LiFePO₄. In the SRL regime, the theory produces a fundamentally new equation for phase transformation dynamics, which admits traveling-wave solutions. Rather than forming a shrinking core of untransformed material, the phase boundary advances by filling (or emptying) successive channels of fast diffusion in the crystal. By considering the random nucleation of SRL phase-transformation waves, the theory predicts a very different picture of charge/discharge dynamics from the classical diffusion-limited model, which could affect the interpretation of experimental data for LiFePO₄.     

环保型锂离子电池正极材料LiFePO_4的研究进展

综述了L iFePO4的结构特征、充放电机理、合成方法、改性以及电解质的选择等方面的研究,指出对L iFe-PO4的充放电机理进行理论建模,探索可进行工业化生产的制备方法是目前的研究重点。     

Modeling of an electrically rechargeable alkaline Zn-air battery

The charging and discharge behavior of an electrically rechargeable alkaline Zn-air battery consisting of a porous Zn/ZnO electrode on the negative side and a porous O₂ electrode on the positive side has been investigated. Galvanostatic experiments have been performed and a one-dimensional numerical model has been developed to analyze these experimental data. The cell voltages, the Zn electrode potentials versus Zn reference, and the O₂ electrode potentials versus Zn reference calculated with this model are in fairly good agreement with the corresponding experimental values. The unwanted redistribution of Zn per cycle is predicted to decrease with increasing cycle number. The numerical model is expected to be useful when optimizing zinc cell designs for specific applications.     

A rechargeable redox battery utilizing ruthenium complexes with non-aqueous organic electrolyte

A new-type redox battery has been developed. Some ruthenium complexes in organic electrolyte solution were utilized as the electrode active materials. A single cell consisting of [Ru(bpy)₃]²⁺ complex in acetonitrile solution had an open circuit voltage of 2.6 V and a discharge current of 5 mA cm^–2 (at a smooth carbon electrode). The characteristics of this type of cell were much influenced by such factors as the diaphragm material and the concentration of the complex. A cell with flowing electrolyte was also constructed and its charge-discharge performance was examined.     

Polymer microsphere embedded Si/graphite composite anode material for lithium rechargeable battery

Si/graphite composite materials embedded with polymer microsphere as an elastic inactive phase were prepared by high-energy mechanical milling and investigated as a high capacity anode material for lithium rechargeable battery. Improved capacity retention was achieved with the composite. In situ measurement of the electrode thickness revealed that the swelling of the electrode became smaller with the increase of polymer microsphere content. It is believed that polymer microsphere played a buffering role of accommodating the mechanical strains induced by silicon expansion during lithiation, resulting in the suppression of the volume expansion of the electrode, which improved the cycle performance of the electrode.     

Effects of conductive ceramic on the electrochemical performance of ZnO for Ni/Zn rechargeable battery

A novel ZnO/conductive-ceramic nanocomposite was prepared by a homogeneous precipitation method. The conductive ceramic with the nominal chemical composition of (ZnO)_0.92(Bi₂O₃)_0.054(Co₂O₃)_0.025(Nb₂O₅)_0.00075(Y₂O₃)_0.00025, as the nucleation sites of ZnO, was prepared by ball milling and surface modification process and its effects on electrochemical performance of ZnO were investigated by charge/discharge cycling, slow rate cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Compared with pure ZnO, the ZnO/conductive-ceramic electrode exhibited improved electrochemical properties, such as superior cycle stability, higher discharge capacity and utilization ratio. When the conductive ceramic content reached 14 wt.%, the discharge capacity of the ZnO/conductive-ceramic nanocomposite hardly declined over 50 cycling test, the average utilization ratio could reach 99.5%, and the electrodes had no obvious weight loss after cycling tests.     

离子液体电解质在锂二次电池中的应用

锂二次电池作为动力电池,被寄予厚望。但锂二次电池面临的安全隐患也是不容忽视的,是当前亟需解决的问题,而这与电解质的性质有着紧密的联系。离子液体由于具有较宽电化学窗口、良好的导电性、高热稳定性、几乎无挥发及不燃烧等优良的特性,正在作为一种新型绿色替代溶剂被电化学领域所关注。离子液体的不燃烧特性,对于替代传统有机电解质具有十分重要的意义。本文阐述了新型溶剂“离子液体”作为电解质在锂二次电池中的应用,其中重点阐述了在碳、硅、钛酸锂(Li₄Ti₅O₁₂)、磷酸亚铁锂(LiFePO₄)、钴酸锂LiCoO₂、镍锰酸锂(LiNi_xMn_yO_z),镍钴锰锂(LiNi_xCo_yMn_zO_w)及在锂硫(Li-S)电池中的应用。     

Reducing atmosphere improves the conductivity of NaTi2(PO4)3/C material for hybrid aqueous rechargeable lithium-ion battery anode

Hybrid aqueous rechargeable lithium-ion batteries (HARLIBs) have lower cost and better safety performance than conventional lithium-ion batteries (organic electrolytes). The challenge faced by HARLIBs are the narrow selection of anode and cathode materials, and overcoming the problems of capacity decay of anode and cathode materials in aqueous electrolytes. NaTi₂(PO₄)₃, which has a stable three-dimensional open framework structure, shows certain applicability in HARLIBs, but its inherent low electronic conductivity leads to poor utilization of active materials and inferior rate performance. In this article, we propose an experimental method that can improve the conductivity of NaTi₂(PO₄)₃/C, and study the electrochemical performance of NaTi₂(PO₄)₃/C aqueous half-cell and NaTi₂(PO₄)₃/C||LiMn₂O₄ hybrid aqueous full cell. The results show that Ti³⁺/oxygen vacancies can endow NaTi₂(PO₄)₃/C with higher conductivity and improve the specific capacity and rate capability (69 mAh·g^?1, 7C). At 1C, the second discharge specific capacity is 98.46 mAh·g^?1. After 100 cycles, the Rct was 2.92 × 10^?2 Ω. The NaTi₂(PO₄)₃/C//LiMn₂O₄ full cell can provide a discharge specific capacity of up to 101.07 mAh·g^?1. The synthesized NaTi₂(PO₄)₃/C material can be applied to the anode electrode of hybrid aqueous lithium-ion full cell.     

Dual carbon-confined Na2MnPO4F nanoparticles as a superior cathode for rechargeable sodium-ion battery

Na₂MnPO₄F has drawn worldwide attention as cathode materials for sodium-ion batteries with great promise due to its high theoretical capacity (124 mAh g⁻¹) and working voltage plateau (3.6 V). Unfortunately, its electrochemical performances are largely limited by the intrinsic low electron conductivity and sluggish diffusion of Na⁺. Herein, a reduced graphite oxide nanosheets and nano-carbon co-modified Na₂MnPO₄F nanocomposite is prepared via a simple hydrothermal method. And the composite possesses a three-dimensional “pellets-on-sheets” structure, in which core-shell structured nanoparticles (Na₂MnPO₄F nanoparticles coated by carbon coating layers) are uniformly anchored on the surface of well-dispersed reduced graphite oxide nanosheets. Such unique structure is favorable for fast Na⁺ and electron transports and supplies sufficient active sites for Na⁺ insertion. As the cathode of sodium-ion battery, the as-prepared dual carbon-modified Na₂MnPO₄F composite exhibits a super discharge capacity of 122 mAh g⁻¹ at 0.05 C and high rate-performance (42 mAh g⁻¹ at 2 C) as well as long cycle performance (77% capacity retention after 200 cycles at 0.1 C). Meanwhile, it presents two obvious potential platforms of about 3.7 V and 3.5 V during the charge and discharge process, respectively, revealing its potential applications in high energy density batteries.     

Characteristics of an aqueous rechargeable lithium battery (ARLB)

Electrochemical performance of an aqueous rechargeable lithium battery (ARLB) containing a LiV₃O₈ (negative electrode) and LiCoO₂ (positive electrode) in saturated LiNO₃ aqueous electrolyte was studied. These two electrode materials are stable in the aqueous solution and intercalation/deintercalation of lithium ions occurs within the window of electrochemical stability of water. The obtained capacity of this cell system is about 55 mAh/g based on the mass of the positive electrode, which is lower than the corresponding one in the non-aqueous lithium ion battery. However, its specific capacity can be compared with those of the lead acid and Ni-Cd batteries. In addition, initial results show that this cell system is good in cycling.     

Hydrothermal synthesis of LiMn2O4/C composite as a cathode for rechargeable lithium-ion battery with excellent rate capability

A spinel LiMn₂O₄/C composite was synthesized by hydrothermally treating a precursor of manganese oxide/carbon (MO/C) composite in 0.1 M LiOH solution at 180 °C for 24 h, where the precursor was prepared by reducing potassium permanganate with acetylene black (AB). The AB in the precursor serves as the reducing agent to synthesize the LiMn₂O₄ during the hydrothermal process; the excess of AB remains in the hydrothermal product, forming the LiMn₂O₄/C composite, where the remaining AB helps to improve the electronic conductivity of the composite. The contact between LiMn₂O₄ and C in our composite is better than that in the physically mixed LiMn₂O₄/C material. The electrochemical performance of the LiMn₂O₄/C composite was investigated; the material delivered a high capacity of 83 mAh g⁻¹ and remained 92% of its initial capacity after 200 cycles at a current density of 2 A g⁻¹, indicating its excellent rate capability as well as good cyclic performance.     

非化学计量比尖晶石型锂离子电池正极材料的合成与表征

采用阴阳离子复合掺杂,以共沉淀法、超声共沉淀法、Pechini法和高温固相法合成掺杂锰酸锂前驱体,使用三段热处理方式,即650℃预烧、780℃烧结、550℃回火制备掺杂非化学计量尖晶石Li _1.05 Co _0.05 Ni _0.05 Mn _1.9 O _3.9 F _0.1 .通过化学容量分析测定Mn含量和平均价态,用粒度分布、电镜扫描（SEM）、X射线衍射（XRD）、电化学性能测试对产物进行表征.结果表明产物的Mn含量和平均价态与理论值吻合.比较各种合成方法,超声共沉淀法产物的粒径分布最窄、比表面积最小（0.96 m²•g^-1）、晶型完整、衍射强度最大、结晶性能最佳、晶格常数a为0.821 nm、晶粒尺寸L为57.78 nm.经装配电池电化学性能测定,超声共沉淀法产物的初始容量更高,循环性能更稳定,经30次循环后容量衰减仅9.3％.