Enhancement of the Li ion transfer reaction at the LiCoO2 interface by 1,3,5-trifluorobenzene

This work presents a method of enhancing the kinetics of the interfacial reaction using 1,3,5-trifluorobenzene (TFB) which is used as an electron acceptor due to its locally biased polarity and as a source of rearranging the layer of the electrolyte around LiCoO₂ electrode, not a SEI layer source. The full cells with TFB show a decrease in irreversible capacity loss during the first charge-to-discharge process, regardless of the SEI layer formation, and also show better discharge properties even at high rate conditions. The charge transfer resistance (R_ct) of the LiCoO₂ half cell with TFB shows the smaller resistance than that of the TFB free half cell, and the activation energy calculated from the R_ct was 24.7 kJ/mol for the TFB free half cell and 19.3 kJ/mol for the half cell with TFB. In addition, the film resistance of the half cell with TFB shows higher value when the temperature is below 283 K. Since R_ct is related to the transfer resistance of the solvated Li⁺ ions on the surface of the LiCoO₂ electrode, it will help design the electrolyte to improve the transfer velocity of Li⁺ ions around the cathode electrode for high power Li ion battery.     

Synthesis and electrical properties of the (PVA)0.7(KI)0.3·xH2SO4 (0 ≤ x ≤ 5) polymer electrolytes and their performance in a primary Zn/MnO2 battery

Solid acid polymer electrolytes (SAPE) were synthesised using polyvinyl alcohol, potassium iodide and sulphuric acid in different molar ratios by solution cast technique. The temperature dependent nature of electrical conductivity and the impedance of the polymer electrolytes were determined along with the associated activation energy. The electrical conductivity at room temperature was found to be strongly depended on the amorphous nature of the polymers and H₂SO₄ concentration. The ac (100 Hz to 10 MHz) and dc conductivities of the polymer electrolytes with different H₂SO₄ concentrations were analyzed. A maximum dc conductivity of 1.05 × 10⁻³ S cm⁻¹ has been achieved at ambient temperature for electrolytes containing 5 M H₂SO₄. The frequency and temperature dependent dielectric and electrical modulus properties of the SAPE were studied. The charge transport in the present polymer electrolyte was obtained using Wagner's polarization technique, which demonstrated the charge transport to be mainly due to ions. Using these solid acid polymer electrolytes novel Zn/SAPE/MnO₂ solid state batteries were fabricated and their discharge capacity was calculated. An open circuit voltage of 1.758 V was obtained for 5 M H₂SO₄ based Zn/SAPE/MnO₂ battery.     

An optimized Ni doped LiFePO4/C nanocomposite with excellent rate performance

Both Ni doping and carbon coating are adopted to synthesize a nano-sized LiFePO₄ cathode material through a simple solid-state reaction. It is found that the Ni²⁺ has been successfully doped into LiFePO₄ without affecting the phospho-olivine structure from the XRD result. The images of SEM and TEM show that the size of particles is distributed in the range of 20-60 nm, and all the particles are coated with carbon completely. The results of XPS show the valence state of Fe and Ni in the LiFePO₄. The electronic conductivity of the material is as high as 2.1 × 10⁻¹ S cm⁻¹, which should be ascribed to the coefficient of the conductive carbon network and Ni doping. As a cathode material for lithium-ion batteries, the Ni doped LiFePO₄/C nanocomposite delivers a discharge capacity of 170 mAh g⁻¹ at 0.2 C, approaching the theoretical value. Moreover, the material shows excellent high-rate charge and discharge capability and long-term cyclability. At the high rates of 10 and 15 C, this material exhibits high capacities of 150 and 130 mAh g⁻¹, retaining 95% after 5500 cycles and 93% after 7200 cycles, respectively. Therefore, the as-prepared material is capable of such large-scale applications as electric vehicles and plug-in hybrid electric vehicles.     

Graphene as a conductive additive to enhance the high-rate capabilities of electrospun Li4Ti5O12 for lithium-ion batteries

Spinel Li₄Ti₅O₁₂ (LTO) is a promising candidate anode material for Li-ion batteries due to its well-known zero-strain merits. To improve the electronic properties of spinel LTO, which are intrinsically poor, we processed the material into a nanosized architecture to shorten the distance for Li-ion and electron transport using the versatile electrospinning method. Graphene was chosen as an effective carbon coating to improve the surface conductivity of the nanocomposites. The as-prepared graphene-embedded LTO anode material showed improved discharging/charging and cycling properties, particularly at high rates, such as 22 C, which makes the nanocomposite an attractive anode material for applications in electric vehicles.     

Electrochemical properties of heat-treated polymer-derived SiCN anode for lithium ion batteries

Silicon-carbon-nitrogen material (SiCN) is pyrolyzed from polysilylethylenediamine (PSEDA) derivation, followed by a heat-treating process at 1000 °C in Ar atmosphere. This heat-treated SiCN material has an excellent electrochemical performance as an anode for lithium ion batteries. Charge-discharge cycle measurements show that the heat-treated SiCN material exhibits a high first cycle discharge capacity of 829.0 mAh g⁻¹ and stays between 400 and 370 mAh g⁻¹ after 30 cycles. The discharge capacity remains above 300 mAh g⁻¹ at the high current density of 80 and 160 mA g⁻¹. These values are higher than untreated SiCN and commercial graphite anodes, which indicates that the heat-treating process improves the charge-discharge capacity, cycle stability and high-rate ability of SiCN anode. It is seemed that changes of SiCN structure, the formation of loose nano-holes on material surface and the formation of graphitic carbon phase in heat-treating process contribute to the improvement of electrochemical properties for SiCN anode.     

On the electrochemical performance of anthracite-based graphite materials as anodes in lithium-ion batteries

The electrochemical performance as potential negative electrode in lithium-ion batteries of graphite materials that were prepared from two Spanish anthracites of different characteristics by heat treatment in the temperature interval 2400-2800 °C are investigated by galvanostatic cycling. The interlayer spacing, d₀₀₂, and crystallite sizes along the c axis, L_c, and the a axis, L_a, calculated from X-ray diffractometry (XRD) as well as the relative intensity of the Raman D-band, I_D/I_t, are used to assess the degree of structural order of the graphite materials. The galvanostatic cycling are carried out in the 2.1-0.003 V potential range at a constant current and C/10 rate during 50 cycles versus Li/Li⁺. Larger reversible lithium storage capacities are obtained from those anthracite-based graphite materials with higher structural order and crystal orientation. Reasonably good linear correlations were attained between the electrode reversible charge and the materials XRD and Raman crystal parameters. The graphite materials prepared show excellent cyclability as well as low irreversible charge; the reversible capacity being up to ∼250 mA h g⁻¹. From this study, the utilization of anthracite-based graphite materials as negative electrode in lithium-ion batteries appears feasible. Nevertheless, additional work should be done to improve the structural order of the graphite materials prepared and therefore, the reversible capacity.     

正弦波放电电源在蓄电池组充放电中的应用

介绍几种常规蓄电池放电方式,以SC220-30型正弦波并网放电电源装置在蓄电池组充放电中的应用为例,经过放电试验阐述其回馈电能等功能特点。     

阀控式密封铅酸蓄电池充电终止控制方法的研究

为了使阀控式密封铅酸蓄电池在充电完成时能够及时终止充电过程,且尽量减少误操作对电池造成的损害,本文首先对常规的充电终止控制方法进行了论证与分析,然后对比了常规充电终止方法的优缺点并根据实际要求提出了一种适合于VRLA蓄电池充电终止控制的改进综合法。     

大数据驱动的动力电池健康状态估计方法综述

动力电池健康状态估计是电池管理系统关键算法之一,对提高动力电池能量利用效率、降低电池热失控风险,以及动力电池的维保和残值评估具有重要意义。对比分析试验法、模型法、数据驱动法的优势和不足,并以数据驱动方法为核心,分别从动力电池健康状态数据集构建、健康状态特征参数提取、健康状态估计模型三个方面对现阶段健康状态估计方法的理论基础和技术方案进行综述。总结常用的大数据采集方法以及数据预处理方法,明确大数据在健康状态评估中的意义。比较现有健康状态特征提取方法,对其优劣以及适用场景做了分析。阐述不同健康状态估计模型的基本原理,提出模型融合是未来技术发展方向。最后,面向未来大数据实车应用场景,对动力电池健康状态估计方面存在的问题和发展前景进行了总结和展望。     

锌-铝长效防腐涂层在核电乏燃料贮存罐中的应用

乏燃料贮存罐的腐蚀破坏可能导致灾难性事故,其维护的特殊性,要求一种长效安全的防护技术。简述了钢铁在海洋大气中的腐蚀,对比分析了几种钢铁表面防护方法,探讨Zn-Al合金防腐蚀机理。在上述基础上,推荐了关于乏燃料贮存罐长效防腐蚀建议方案。