密封双极性MH/Ni电池结构改进与研制

Nickel metal hydride batteries in bipolar design offer significant advantages as a power storage system for electric vehicles. This study deals with some aspects in structure design and development of bipolar nickel metal hydride batteries. An improvement on conventional bipolar structure was made, and some novel sealed bipolar nickel metal hydride batteries with 6 cells were assembled and studied. Testing results showed that the improved structure effectively protected the worst single cell of bipolar battery, and led to a better pressure and cycle performances of novel batteries compared with conventional ones. In addition, the improved bipolar batteries showed excellent discharge and recharge ability, and low resistance in electrochemical tests. As simulating hybrid electric vehicle working conditions, the batteries displayed good stability during pulse cycles, which indicated the possibility of being used on electric vehicles.     

金属氢化物-镍电池的回收与循环再利用

介绍了国内外废旧电池的回收概况以及火法和湿法回收金属氢化物 -镍电池的工艺流程。指出传统的火法或湿法回收工艺复杂 ,成本高 ,有价金属回收率低 ,且使用各种化学试剂又会对环境造成二次污染。提出在系统分析金属氢化物 -镍电池失效原因的基础上 ,探寻简单可行的非破坏性电池再生技术新途径     

高比容量镍氢电池的制备及电化学性能

Cylindrical nickel metal hydride （Ni-MH） battery with high specific volume capacity was prepared by using the oxyhydroxide Ni（OH）2 and AB5 type hydrogen storage alloy and adjusting the designing parameters of positive and negative electrodes. The oxyhydroxide Ni（OH）2 was synthesized by oxidizing spherical β-Ni（OH）2 with chemical method. The X-ray diffraction （XRD） patterns and the Fourier transform infrared （PT-IR） spectra indicated that 7-NiOOH was formed on the oxyhydroxide Ni（OH）2 powders, and some H2O molecules were inserted into their crystal lattice spacing. The battery capacity could not be improved when the oxyhydroxide Ni（OH）2 sample was directly used as the positive active materials. However, based on the conductance and residual capacity of the oxyhydroxide Ni（OH）2 powders, AA size Ni-MH battery with 2560 mA.h capacity and 407 W·h·L^-1 specific volume energy at 0.2C was obtained by using the commercial spherical β-Ni（OH）2 and AB5-type hydrogen-storage alloy powders as the active materials when 10% mass amount of the oxyhydroxide Ni（OH）2 with 2.50 valence was added to the positive active materials and subsequently the battery designing parameters were adjusted as well. The as-prepared battery showed 70% initial capacity after 80 cycles at 0.5C. The possibility for adjusting the capacity ratio of positive and negative electrodes from 1 ： 1.35 to 1 ： 1.22 was demonstrated preliminarily. It is considered the as-prepared battery can meet the requirement of some special portable electrical instruments.     

Electrochemical behavior of biphenyl as polymerizable additive for overcharge protection of lithium ion batteries

Electrochemical properties and working mechanism of biphenyl as a polymerizable electrolyte additive for overcharge protection of lithium ion batteries are studied by microelectrode voltammetry, charge-discharge measurements and SEM characterization of the overcharged cell’s components. The experimental results reveal that biphenyl can electrochemically polymerize at the overcharge potential of 4.5-4.75 V (versus Li/Li⁺) to form a layer of conductive film on the cathode surface and the polymer deposits may develop to penetrate the separator to reach the anode surface, resulting an internal short-circuit to prevent from the cell voltage runaway. On the other hand, the electro-oxidative polymerization of biphenyl produces excessive gas and heat, which help to enhance the sensitivities of electric disconnecting devices. In addition, it is also found that the use of biphenyl as an electrolyte additive does not significantly influence the normal performances of the lithium ion batteries.     

Methyl phenyl bis-methoxydiethoxysilane as bi-functional additive to propylene carbonate-based electrolyte for lithium ion batteries

Methyl phenyl bis-methoxydiethoxysilane (MPBMDS) was prepared and its effects were investigated as an additive in 1.0 mol dm⁻³ LiPF₆-propylene carbonate (PC)/dimethyl carbonate (DMC) (1:1, v/v) electrolyte for lithium ion batteries. The electrochemical properties of the electrolyte with MPBMDS were characterized by discharge/charge tests, cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The addition of MPBMDS can effectively prevent the decomposition and the co-intercalation of PC. In addition, burning tests showed that the addition of 4–13 wt.% MPBMDS to the bare PC-based electrolyte effectively reduces the flammability. This eco-friendly compound provides a new promising direction for the development of bi- or multi-functional additives for lithium ion batteries.     

Effect of the concentration of diphenyloctyl phosphate as a flame-retarding additive on the electrochemical performance of lithium-ion batteries

We selected diphenyloctyl phosphate (DPOF) as a flame-retardant and plasticizer, and studied the influence of different amounts of the DPOF additive on the electrochemical performance of lithium-ion batteries. The electrochemical cell performances of the additive-containing electrolytes in combination with a cell comprising an LiCoO₂ cathode and mesocarbon microbeads (MCMB) anode were tested in coin cells. The cyclic voltammetry (CV) results showed that the oxidation potential of the electrolyte containing DPOF in the concentration range from 10 to 30 wt.% is about 4.75-5.5 V versus Li/Li⁺. In the present work, a DPOF content of 10 wt.% in the 1.15 M LiPF₆/EC:EMC (4:6 by vol.%) electrolyte turned out to be the optimum condition for the improvement of the electrochemical cell performance, due to the decrease of the irreversible capacity during the first cycle and decrease of the charge-transfer resistance after 40 cycles.     

Effects of copper trifluoromethanesulphonate as an additive to propylene carbonate-based electrolyte for lithium-ion batteries

Addition of copper trifluoromethanesulphonate (CuTF) to propylene carbonate (PC)-based electrolyte effectively suppresses the cointercalation and decomposition of PC in the mesocarbon microbeads (MCMB) electrodes during the first lithiation process. During the first charging cycle, copper ions are reduced at a higher potential (2 V versus Li/Li⁺) than the potential of PC cointercalation and decomposition (0.6-0.8 V versus Li/Li⁺), and predominately form a porous copper layer over the MCMB surface, thereby obstructing PC to cointercalate. An increase in reversible capacity can be achieved by increasing the amount of CuTF. However, above a critical value, the copper layer inhibits the intercalation of lithium ions and lowers the capacity. The AC impedance data reveal that the passivation film and the charge-transfer resistance are both increased when the deposited copper is in excess. An optimum result may be obtained when the addition is approximately 5 wt.%. CuTF is a possibility for PC-based electrolyte additive in lithium-ion batteries.     

酞菁铁对MH/Ni电池浮充性能的影响

研究了酞菁铁(FePc)对金属氢化物-镍电池浮充性能的影响。添加适量FePc的电池具有较好的浮充浮放性能,其中添加1mgFePc的电池显示了最好的充电效率和循环性能;2000次浮充以后其内压升高速度也最低。     

All solid-state nickel/metal hydride battery with a proton-conductive phosphoric acid-doped silica gel electrolyte

All solid-state nickel/metal hydride (Ni/MH) battery was fabricated by using a proton-conductive phosphoric acid-doped silica gel as an electrolyte. The H₃PO₄-doped silica gel was dried in vacuum at various temperatures for 1 h before fabricating the battery in order to reduce the possibility of corrosion by water on the surface and in the micropores of the gel. The influence of drying temperature on the crystallinity, water content and conductivity of the gel was investigated. The conductivity depended on the drying temperature of the gel. The fabricated all solid-state Ni/MH battery was able to operate several tens of charge-discharge cycles at relatively high current density although the utilization of the battery was low.     

Possible use of ferrocyanide as a redox additive for prevention of electrolyte decomposition in overcharged nickel batteries

The redox reaction of ferrocyanide was investigated for possible use as a redox additive for the prevention of the electrolyte decomposition of aqueous secondary Ni-MH batteries in the overcharged condition. It was found that with the presence of ferrocyanide, the charging voltage can be leveled off just above the complete oxidation of the positive nickel electrode. As a result, the oxygen evolution was greatly suppressed and the internal pressure of the batteries was kept at low level even at prolonged overcharging. In addition, no detrimental effects of the redox additive were observed on the normal charge-discharge performance of Ni-MH batteries.     

Simple synthesis of surface-modified hierarchical copper oxide spheres with needle-like morphology as anode for lithium ion batteries

Hierarchical, nanostructured copper oxide spheres were synthesized in a stirred solution of cupric acetate and ammonium hydroxide. Cetyltrimethylammonium bromide (CTAB) was used as a surfactant to modify the surface morphology of CuO spheres. Ordered nano-needle arrays can be formed on the surface of the CuO spheres (instead of disordered nano-leaves) in the presence of CTAB. Each CuO sphere is about 2 μm in diameter and possesses a large number of nano-needles that are about 20-40 nm in width and more than 300 nm in length. The needle-like hierarchical structure can greatly increase the contact area between CuO and electrolyte, which provides more sites for Li⁺ accommodation, shortens the diffusion length of Li⁺ and enhances the reactivity of electrode reaction, especially at high rates. After 50 cycles, the reversible capacity of the prepared needle-like CuO can sustain 62.4% and 56.4% of the 2nd cycle at a rate of 0.1C and 1C, respectively.     

丁二腈作为电解液添加剂的研究

在1 mol/L 六氟磷酸锂/［碳酸乙烯酯（EC）+碳酸二甲酯（DMC）+碳酸甲乙酯（EMC）（体积比为1∶1∶1）］的电解液中加入添加剂丁二腈（SN）,用循环伏安（CV）、恒流充放电、电化学阻抗谱（EIS）等方法,研究了丁二腈对电解液的电化学窗口、电池的比容量、电池的首次充放电效率和电池的循环性能的影响。结果表明,在电解液中加入一定量的高纯度丁二腈,能提高电池的比容量、首次充放电效率和拓宽电解液的电化学稳定窗口,从而提高电解液的热稳定性,改善电解液的循环性能。     

环己苯过充添加剂在锂离子电池中的应用

本文分析了环己苯作为过充保护添加剂在锂离子电池中的应用。笔者采用对所组装的锂离子电池1C倍率过充电,锂离子电池循环性能测试,交流阻抗测试,电解液电导率以及电池自放电测试研究添加环己苯的量对锂离子电池的过充保护效果以及对电池性能的影响。同时,本文分析了环己苯作为过充保护剂的可能工作原理,发现当环己苯的含量大于5％时,能对锂离子电池起到良好的过充保护作用;高于7％时会对电池循环性能产生不良影响。同时环己苯会降低电解液电导率,导致电池自放电增加。笔者认为5％－7％是环己苯作为锂离子电池添加剂的适宜比例。     

Effect of 1-butyl-1-methylpyrrolidinium hexafluorophosphate as a flame-retarding additive on the cycling performance and thermal properties of lithium-ion batteries

1-Butyl-1-methylpyrrolidinium hexafluorophosphate (BMP-PF₆) was used as a flame-retarding additive in the liquid electrolyte, and the influence of BMP-PF₆ content on cycling performance and thermal properties of lithium-ion batteries was investigated. Self-extinguishing time and DSC studies demonstrated that the addition of BMP-PF₆ to the electrolyte provided a significant suppression in the flammability of the electrolyte and an improvement in the thermal stability of the cell. The optimum BMP-PF₆ content in the electrolyte was found to be 10 wt.% for improving safety without degrading cycling performance of the cell.     

Experimental and theoretical investigations on 4,5-dimethyl-[1,3]dioxol-2-one as solid electrolyte interface forming additive for lithium-ion batteries

4,5-Dimethyl-[1,3]dioxol-2-one (DMDO) was used as a novel electrolyte additive for lithium-ion batteries. The effect of DMDO on the formation of the solid electrolyte interface (SEI) on anode and cathode of MCMB/LiNi_0.8Co_0.2O₂ cells was investigated via a combination of electrochemical methods, X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations. It is found that cells with electrolyte containing 2% DMDO have better capacity retention than cells without DMDO and this improved performance is ascribed to the assistance of DMDO in forming better SEIs on anode and cathode. DMDO-decomposition products are identified experimentally on the surface of the anode and cathode and supported by theoretical calculations.     

Recycling of nickel–metal hydride batteries. II: Electrochemical deposition of cobalt and nickel

A combination of hydrometallurgical and electrochemical processes has been developed for the separation and recovery of nickel and cobalt from cylindrical nickel–metal hydride rechargeable batteries. Leaching tests revealed that a 4 mol dm^?3 hydrochloric acid solution at 95 °C was suitable to dissolve all metals from the battery after 3 h dissolution. The rare earths were separated from the leaching solution by solvent extraction with 25% bis(2‐ethylhexyl)phosphoric acid (D2EHPA) in kerosene. The nickel and cobalt present in the aqueous phase were subjected to electrowinning. Galvanostatic tests on simulated aqueous solutions investigated the effect of current density, pH, and temperature with regard to current efficiency and deposit composition and morphology. The results indicated that achieving an Ni? Co composition with desirable properties was possible by varying the applied current density. Preferential cobalt deposition was observed at low current densities. Galvanostatic tests using solutions obtained from treatment of batteries revealed that the aqueous chloride phase, obtained from the extraction, was suitable for recovery of nickel and cobalt through simultaneous electrodeposition. Scanning electron micrography and X‐ray diffraction analysis gave detailed information of the morphology and the crystallographic orientation of the obtained deposits. Copyright © 2004 Society of Chemical Industry     

Evaluation of electroactive intermediate states in anodic O2 evolution at chemically formed nickel oxide: Comparison with behaviour at nickel metal anodes

The behaviour of the kinetically involved intermediate states arising in the electrocatalysis of anodic oxygen evolution at chemically formed, high-area nickel oxide (NiO·OH) films on nickel metal as substrate is examined by means of analysis of potential (V) decay transients, following interruption of anodic polarization currents at various overpotentials. The potential decay behaviour is treated in terms of the dependence ofV(t) on log (time,t), and of ln (–dV/dt) as f[V(t)]. The pseudocapacitance associated with the potential-dependence of the coverage or surface density of the overpotential-deposited species involved as intermediates in the reaction at the oxide electrode surface is evaluated jointly from the potential decay and Tafel polarization behaviour, following procedures developed recently.In anodic O₂ evolution on oxide surfaces, such as NiO·OH, the intermediate states in the kinetics of the reaction are to be identified as OH or O species coupled with potential-dependent Ni(III) and Ni(IV) oxidation states of nickel, and the surface density of these states can be evaluated experimentally.The results obtained for anodic O₂ evolution on the chemically formed nickel oxide films are compared with the behaviour at anodically formed thin oxide films on nickel metal.     

The function of vinylene carbonate as a thermal additive to electrolyte in lithium batteries

The role of vinylene carbonate (VC) as a thermal additive to electrolytes in lithium ion batteries is studied in two aspects: the protection of liquid electrolyte species and the thermal stability of the solid electrolyte interphase (SEI) formed from VC on graphite electrodes at elevated temperatures. The nuclear magnetic resonance (NMR) spectra indicate that VC can not protect LiPF₆ salt from thermal decomposition. However, the function of VC on SEI can be observed via impedance and electron spectroscopy for chemical analysis (ESCA). These results clearly show VC-induced SEI comprises polymeric species and is sufficiently stable to resist thermal damage. It has been confirmed that VC can suppress the formation of resistive LiF, and thus reduce the interfacial resistance.     

氧化铜作锂离子电池负极材料的制备及性能研究

以Cu（NO₃）₂·3H₂O和氢氧化钠为原料,通过水热法制备氧化铜样品。采用X射线衍射法对其进行物相结构的表征。针对pH、反应时间和反应体系浓度等反应条件,对氧化铜样品的物相结构和电化学性能的影响进行了讨论。结果表明,采用该方法制备的氧化铜负极材料在0.1 C（67 mA/g）电流密度下首次充放电容量分别为406.5 mA·h/g和867.4 mA·h/g,在大倍率循环下具有较高的容量保持率。