分子自组装法制备具有可控浸润性的铜表面简

通过简单浸泡的方法在铜基底上制备出了具有微纳米复合结构的氧化铜,再利用混合硫醇溶液[含HS(CH2)9CH3和 HS(CH2)11OH]对浸泡后的表面进行修饰,通过控制溶液中HS(CH2)11OH的浓度,制备出一系列具有不同浸润性的铜表面,实现表面从超疏水到超亲水的有效调控. 研究发现,表面浸润的可控性源于表面复合结构与不同化学组成的协同作用,微纳米复合结构的存在为表面浸润性的调节提供了必要的条件.     

气相色谱/质谱测定皮革及其制品中乙二醇醚类有机溶剂的残留量

建立了同时测定皮革及其制品中12种乙二醇醚类有机溶剂残留量的气相色谱/质谱-选择离子监测方法。以乙酸乙酯为萃取溶剂,在45℃下超声萃取皮革及其制品中的乙二醇醚类有机溶剂,萃取液经固相萃取柱净化后进行气相色谱/质谱-选择离子监测法测定,外标法定量。在信噪比（S/N）=3的条件下,乙二醇单乙醚（EGEE）的检出限为0.10 mg/kg,其余11种乙二醇醚类有机溶剂的检出限均小于0.05 mg/kg。在3个加标水平下,该方法的平均加标回收率为81.2%~95.5%,相对标准偏差（RSD）为1.4%~6.6%（n=9）。该方法简便快捷,灵敏度高,检出限远远低于欧盟法规《化学品的注册、评估、授权和限制》（REACH）的限量要求,适用于皮革及其制品中乙二醇醚类有机溶剂残留量的测定,为制定相关检测标准提供了参考。     

Preparation of honeycomb porous La0.6Sr0.4Co0.2Fe0.8O3−δ-Gd0.2Ce0.8O2−δ composite cathodes by breath figures method for solid oxide fuel cells

Honeycomb porous La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ-Gd_0.2Ce_0.8O_2−δ (LSCF-GDC) composite cathodes are prepared using the breath figures (BFs) method with nontoxic and easily available water droplets as templates. The fabrication of honeycomb porous membranes is realized in a relatively humid environment, using a volatile solvent. The microstructure and morphology of the membranes produced are investigated by scanning electron microscopy (SEM). The SEM micrographs suggest that experimental conditions, such as ambient temperature, relative humidity, and concentration of polymer and LSCF-GDC powder, which have direct influence on the solvent evaporation affects the pore structure of the porous membranes. Electrochemical impedance spectroscopy (EIS) is used to evaluate the polarization resistance of LSCF-GDC composite cathodes prepared at different experimental conditions. The honeycomb porous LSCF-GDC composite cathode showing average pore diameter of 10 μm illustrates the lowest polarization resistance.     

回火处理对LiNi1/3Co1/3Mn1/3O2结构和电化学性能的影响

以硝酸锂、四水合乙酸镍、四水合乙酸钴、四水合乙酸锰、氨水和草酸为原料,通过共沉淀-燃烧法合成了锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2,采用XRD、SEM和充放电试验对合成产物进行了表征,研究了回火处理对合成产物结构和电化学性能的影响.实验结果表明,嫩烧反应形成的LiNi1/3C1/3Mn31/3O2结...     

The influence of Li sources on physical and electrochemical properties of LiNi<Subscript>0.5</Subscript>Mn<Subscript>1.5</Subscript>O<Subscript>4</Subscript> cathode materials for lithium-ion batteries

LiNi_0.5Mn_1.5O₄ cathode materials were successfully prepared by sol–gel method with two different Li sources. The effect of both lithium acetate and lithium hydroxide on physical and electrochemical performances of LiNi_0.5Mn_1.5O₄ was investigated by scanning electron microscopy, Fourier transform infrared, X-ray diffraction, and electrochemical method. The structure of both samples is confirmed as typical cubic spinel with Fd3m space group, whichever lithium salt is adopted. The grain size of LiNi_0.5Mn_1.5O₄ powder and its electrochemical behaviors are strongly affected by Li sources. For the samples prepared with lithium acetate, more spinel nucleation should form during the precalcination process, which was stimulated by the heat released from the combustion of extra organic acetate group. Therefore, the particle size of the obtained powder presents smaller average and wider distribution, which facilitates the initial discharge capacity and deteriorates the cycling performance. More seriously, there exists cation replacement of Li sites by transition metal elements, which causes channel block for Li ion transference and deteriorates the rate capability. The compound obtained with lithium hydroxide exhibits better electrochemical responses in terms of both cycling and rate properties due to higher crystallinity, moderate particle size, narrow size distribution and lower transition cation substitute content.     

Hierarchical Mn3O4 Anchored on 3D Graphene Aerogels via C−O−Mn Linkage with Superior Electrochemical Performance for Flexible Asymmetric Supercapacitor

Flexible asymmetric supercapacitors are more appealing in flexible electronics because of high power density, wide cell voltage, and higher energy density than symmetric supercapacitors in aqueous electrolyte. In virtues of excellent conductivity, rich porous structure and interconnected honeycomb structure, three dimensional graphene aerogels show great potential as electrode in asymmetric supercapacitors. However, graphene aerogels are rarely used in flexible asymmetric supercapacitors because of easily re-stacking of graphene sheets, resulting in low electrochemical activity. Herein, flower-like hierarchical Mn₃O₄ and carbon nanohorns are incorporated into three dimensional graphene aerogels to restrain the stack of graphene sheets, and are applied as the positive and negative electrode for asymmetric supercapacitors devices, respectively. Besides, a strong chemical coupling between Mn₃O₄ and graphene via the C-O-Mn linkage is constructed and can provide a good electron-transport pathway during cycles. Consequently, the asymmetric supercapacitor device shows high rate cycle stability (87.8 % after 5000 cycles) and achieves a high energy density of 17.4 μWh cm⁻² with power density of 14.1 mW cm⁻² (156.7 mW cm⁻³) at 1.4 V.     

Designing Solid Electrolyte Interfaces towards Homogeneous Na Deposition: Theoretical Guidelines for Electrolyte Additives and Superior High-Rate Cycling Stability

Metallic Na is a promising metal anode for large-scale energy storage. Nevertheless, unstable solid electrolyte interphase (SEI) and uncontrollable Na dendrite growth lead to disastrous short circuit and poor cycle life. Through phase field and ab initio molecular dynamics simulation, we first predict that the sodium bromide (NaBr) with the lowest Na ion diffusion energy barrier among sodium halogen compounds (NaX, X=F, Cl, Br, I) is the ideal SEI composition to induce the spherical Na deposition for suppressing dendrite growth. Then, 1,2-dibromobenzene (1,2-DBB) additive is introduced into the common fluoroethylene carbonate-based carbonate electrolyte (the corresponding SEI has high mechanical stability) to construct a desirable NaBr-rich stable SEI layer. When the Na||Na₃V₂(PO₄)₃ cell utilizes the electrolyte with 1,2-DBB additive, an extraordinary capacity retention of 94 % is achieved after 2000 cycles at a high rate of 10 C. This study provides a design philosophy for dendrite-free Na metal anode and can be expanded to other metal anodes.     

Influences of synthesis route and preparation process on the electrochemical properties of Fe-doped strontium cobaltite

SrCo_0.8Fe_0.2O_3-δ (SCF), as a promising cathode material for intermediate temperature solid oxide fuel cells, possesses a high catalytic activity for the reduction of O₂ to 2O²⁻. The SCF powder was successfully synthesized by the solid state reaction method and Pechini method and characterized using XRD, particle analysis, and electrochemical performance measurements. Smaller-particle-size SCF materials (SCF-P) with single phase are obtained at lower synthesis temperature by the Pechini method and possess better electrochemical performance as compared with those prepared by the solid state reaction method. The reason is that the Pechini method involves the mixing of elements at atomic level, so pure SCF phase formation can be accelerated and showed high electrocatalytic activity. The preparation procedure of SCF cathode was firstly investigated using electrochemical impedance spectroscopy. Results show that the total polarization resistance and the low-frequency resistance decrease gradually with the reduction of the calcination temperature for the SCF cathodes. The SCF-P cathode sintered at 1,000 °C possesses the highest porosity and the best electrochemical performance. It is the result of a comprehensive function of three-phase boundary length, porosity of cathode, and the adhesion between cathode and electrolyte. The charge-transfer process, together with the adsorption, dissociation, and diffusion of oxygen, has a strong influence on the whole reaction process of the cathode. The influence of binder amounts on the performance of the SCF-P cathodes was also studied.     

Improvement of high-voltage cycling behavior of Li(Ni1/3Co1/3Mn1/3)O2 cathodes by Mg, Cr, and Al substitution

To improve the electrochemical properties of Li[Ni_1/3Co_1/3Mn_1/3]O₂ at high charge end voltage (4.6 V), a series of the mixed transition metal compounds, Li(Ni_1/3Co_{1/3 − x} Mn_1/3M _x )O₂ (M = Mg, Cr, Al; x = 0.05), were synthesized via hydroxide coprecipitation method. The effects of doping Mg, Cr, and Al on the structure and the electrochemical performances of Li[Ni_1/3Co_1/3Mn_1/3]O₂ were compared by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), galvanostatic charge–discharge tests, and electrochemical impedance spectroscopy. The XRD results show that all the samples keep layered structures with R3m space group as the Li[Ni_1/3Co_1/3Mn_1/3]O₂. SEM images show that all the compounds have spherical shapes and the Cr-doped sample has the largest particle size. Furthermore, galvanostatic charge–discharge tests confirm that the Cr-doped electrode shows improved cycling performance than the undoped material. The capacity retention of Li(Ni_1/3Co_{1/3 − 0.05}Mn_1/3Cr_0.05)O₂ is 97% during 50 cycles at 2.8∼4.6 V. The improved cycling performance at high voltage can be attributed to the larger particle size and the prevention of charge transfer resistance (R _ct) increase during cycling.     

分子自组装法制备具有可控浸润性的铜表面

通过简单浸泡的方法在铜基底上制备出了具有微纳米复合结构的氧化铜, 再利用混合硫醇溶液[含HS(CH₂)₉CH₃和 HS(CH₂)₁₁OH]对浸泡后的表面进行修饰, 通过控制溶液中HS(CH₂)₁₁OH的浓度, 制备出一系列具有不同浸润性的铜表面, 实现表面从超疏水到超亲水的有效调控. 研究发现, 表面浸润的可控性源于表面复合结构与不同化学组成的协同作用, 微纳米复合结构的存在为表面浸润性的调节提供了必要的条件.