二维超声复合电解/放电展成加工试验研究

为了提高铝基复合材料的表面成型质量和加工效率,提出了应用低电压、低电流密度的二维超声复合电解/放电展成加工(2UE/DM)技术。利用镀覆金刚石磨粒的工具侧面对复合材料进行3种不同工艺对比试验和3组参数下的性能试验,测量了铝基陶瓷增强复合材料(SiCp/Al)在质量分数0.5%的NaNO3溶液中展成加工时的电流、材料去除率(MRR)和表面粗糙度,探究了工具转速、电压和振幅对加工效率和质量的影响。结果表明,工件振动周期性改变加工间隙,单位周期内的放电频率增加了2倍;5000 r/min时放电频率减少,而表面粗糙度比1000 r/min降低了13.2%;在电压为6 V时,材料去除率达到0.89 mm^(3)/min,比3 V电压时增加45.9%,但较高电压导致裸露更多增强颗粒,比3 V时的表面粗糙度高出1.4μm;振幅增至5μm时,表面粗糙度比2μm时降低了17.5%,具有较高的加工质量。

SiC_(p)/Al二维超声复合电解/放电加工的表面生成机理及试验研究

针对复合材料高质量的加工要求,结合各加工技术的优点,本文提出二维超声复合电解/放电加工技术(2UECM/EDM),并对其表面生成机理进行深入研究。利用二维超声辅助磨削加工时单磨粒的运动轨迹对加工表面沟槽的加宽作用和电解/放电加工的整平作用,通过研磨面积比(δ_(s))来分析复合材料表面形貌和表面粗糙度(Ra)的变化规律,并进行了复合材料SiC_(p)/Al维超声复合电解/放电加工的表面生成机理对比试验。结果表明,单周进给距离、电压和二维超声振幅等参数影响加工表面质量。其中,表面粗糙度与磨粒单周进给距离的变化趋势一致;较高电压时电解/放电加工效应显著,导致增强颗粒裸露进而增加了Ra;轴向和切向二维振动共同作用下显著增大δ_(s)值,而其值在1.8附近时Ra出现明显的转折变化趋势。因此,当δ_(s)大于1.8时的工具和工件振幅以及较低电压参数,加工时对增强颗粒的拖曳和碾压可以显著降低表面不平度、较大幅度提高工件表面质量。

Discharge behavior and electrochemical properties of Mg-Al-Sn alloy anode for seawater activated battery

Mg-Al-Sn alloy is one of the new developed anode materials for seawater activated batteries. The potentiodynamic polarization, galvanostatic discharge and electrochemical impedance spectroscopy of Mg-6%Al-1%Sn and Mg-6%Al-5%Sn(mass fraction) alloys in seawater were studied and compared with the commercial AZ31 and AP65 alloys. The results show that the Mg-6%Al-1%Sn alloy obtains the most negative discharge potential of average-1.611V with a electric current density of 100 mA/cm2. EIS studies reveal that the Mg-Al-Sn alloy/seawater interfacial electrochemical process is determined by an activation controlled reaction. The assembled prototype batteries with Mg-6%Al-1%Sn alloy as anodes and Ag Cl as cathodes exhibit a satisfactory integrated discharge properties.

Preparation of porous Mg electrode by electrodeposition

In order to obtain a porous Mg electrode with a stable skeleton, organic Mg fuel cell （OMFC）, the electrochemical behavior of Mg deposition on Cu and Ni metallic substrates in 1 mol/L EtMgBr/THF solution was investigated by SEM, EDS and electrochemical methods. The experimental results show that Mg can be electrodeposited on both substrates, as a continuous layer on a Cu substrate. Accordingly, an approach for producing a porous Mg electrode with a stable skeleton of OMFC was proposed by means of electrodeposition of Mg on a foamed Ni substrate with a layer of Cu pre-plating. The discharge performance of this porous Mg electrode of OMFC is superior to that of a planar Mg electrode.

Excess Heat Power Registration in High Voltage Electrolysis Cell Experiments

Experimental research of the heat and high-energy processes occurring in the cathode solid medium in the high voltage electric discharge system （electrolysis cell and glow discharge device） is presented. The experiments were carried out： Electrolysis in heavy water with a Pd cathode, electrolysis in light water with Ni and Pd cathodes, the glow discharge in deuterium with a Pd cathode. Excess heat was observed in experiments with high-voltage electrolysis （1,000 V or more）. The experiments showed that the maximum excess heat power values of 5-8 W for glow discharge and 180-280 W for high-voltage electrolysis and heat efficiency up to 170% for glow discharge, and 800% for high-voltage electrolysis. The production of impurity nuclide yield showing a shift of up to a few per cent from natural isotopic abundances was detected by spark mass spectrometry and by secondary ionic mass spectrometry. The authors propose based on these experimental results a phenomenological model for low energy nuclear reaction.

TEMPO-substituted polyacrylamide for an aqueous electrolyte-typed and organic-based rechargeable device

A hydrophilic radical polymer, poly（2,2,6,6-teteramethylpiperidinyloxyl-4-yl acrylamide） （PTAm）, was synthesized via oxidation of the corresponding precursor polymer, poly（2,2,6,6-teteramethylpiperidine-4-yl acrylamide）. Electrochemical properties of the PTAm layer were characterized in three aqueous electrolytes of sodium chloride （NaCl）, sodium tetrafluoroborate （NaBF4）, and sodium hexafluorophosphate （NaPF6） to optimize its activity as an organic cathode. The counter anion species significantly affected the capacity and the cycle performance of the PTAm layer. The PTAm layer in the presence of BF4？ displayed quantitative redox capacity beyond 1 μm layer thickness and maintained the discharging capacity of 110 mAh g-1 （97% vs. the calculated capacity） even after 1000 cycle charging/discharging, which could be ascribed to its appropriate affinity to the aqueous electrolyte without any dissolution into the electrolyte. A totally organic-based rechargeable cell was fabricated using PTAm and poly（N-4,4＇-bipyridinium-N-decamethylene dibromide） as the cathode and the anode, respectively, and the aqueous electrolyte of NaBF4. The cell gave a plateau voltage at 1.2 V both on charging and discharging and an excellent charging/discharging cyclability of ＆gt;2000 with high coulombic efficiency of ＆gt;95%.

Al4B2O9 nanorods-modified solid polymer electrolytes with decent integrated performance

With the proliferation of energy storage and power applications, electric vehicles particularly, solid-state batteries are considered as one of the most promising strategies to address the ever-increasing safety concern and high energy demand of power devices. Here, we demonstrate the Al4B2O9 nanorods-modified poly(ethylene oxide) (PEO)-based solid polymer electrolyte (ASPE) with high ionic conductivity, wide electrochemical window, decent mechanical property and nonflammable performance. Specifically, because of the longer-range ordered Li+ transfer channels conducted by the interaction between Al4B2O9 nanorods and PEO, the optimal ASPE (ASPE-1) shows excellent ionic conductivity of 4.35×10^−1 and 3.1×10^−1 S cm^−1 at 30 and 60℃, respectively. It also has good electrochemical stability at 60℃ with a decomposition voltage of 5.1 V. Besides, the assembled LiFePO4//Li cells show good cycling performance, delivering 155 mA h g−1 after 300 cycles at 1 C under 60℃, and present excellent low temperature adaptability, retaining over 125 mA h g^−1 after 90 cycles at 0.2 C under 30℃. These results verify that the addition of Al4B2O9 nanorods can effectively promote the integrated performance of solid polymer electrolyte.

Universal lithiophilic interfacial layers towards dendrite-free lithium anodes for solid-state lithium-metal batteries

Solid-state lithium-metal-batteries(SSLMBs)using garnet Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)as the solid electrolyte are expected to conquer the safety concerns of high energy Li batteries with organic liquid electrolytes owing to its nonflammable nature and good mechanical strength.However,the poor interfacial contact between the Li anode and LLZTO greatly restrains the practical applications of the electrolyte,because large polarization,dendritic Li formation and penetration can occur at the interfaces.Here,an effective method is proposed to improve the wettability of the LLZTO toward lithium and reduce the interfacial resistance by engineering universal lithiophilic interfacial layers.Thanks to the in-situ formed lithiophilic and ionic conductive Co/Li_(2)O interlayers,the symmetric Li/CoO-LLZTO/Li batteries present much smaller overpotential,ultra-low areal specific resistance(ASR,12.3 X cm^(2)),high critical current density(CCD,1.1 mA cm^(-2)),and outstanding cycling performance(1696 h at a current density of 0.3 mA cm^(-2))at 25℃.Besides,the solid-state Li/CoO-LLZTO/LFP cells deliver an excellent electrochemical performance with a high coulombic efficiency of~100%and a long cycling time over 185 times.Surprisingly,the high-voltage(4.6 V)solid state Li/CoO-LLZTO/Li_(1.4)Mn_(0.6)Ni_(0.2)Co_(0.2)O_(2.4)(LMNC622)batteries can also realize an ultra-high specific capacity(232.5 mAh g-1)under 0.1 C at 25℃.This work paves an effective way for practical applications of the dendrite-free SSLMBs.

Naphthalene decomposition in a DC corona radical shower discharge

The naphthalene decomposition in a corona radical shower discharge (CRS) was investigated, with attention paid to the influences of voltage and initial naphthalene density. The OH emission spectra were investigated so as to know the naphthalene decomposing process. The by-products were analyzed and a decomposing theory in discharge was proposed. The results showed that higher voltage and relative humidity were effective on decomposition. The initial concentration affected the decomposing efficiency of naphthalene. When the initial naphthalene density was 17 mg/m3, the decomposition rate was found to be 70% under 14 kV. The main by-products were carbon dioxide and water. However, a small amount of carbonic oxide, 1,2-ethanediol and acetaldehyde were found due to the incomplete oxidization.

Reversible LiOH chemistry in Li-O_(2)batteries with free-standing Ag/δ-MnO_(2)nanoflower cathode

The low energy efficiency and poor cycle stability arising from the high aggressivity of discharge products toward organic electrolytes limit the practical applications of Li-O_(2)batteries(LOBs).Compared with the typical discharge product Li_(2)O_(2),LiOH shows better chemical and electrochemical stability.In this study,a free-standing cathode composed of hydrangea-likeδ-MnO_(2)with Ag nanoparticles(NPs)embedded in carbon paper(CP)(Ag/δ-MnO_(2)@CP)is fabricated and used as the catalyst for the reversible formation and decomposition of LiOH.The possible discharge mechanism is investigated by in situ Raman measurement and density functional theory calculation.Results confirm thatδ-MnO_(2)dominantly catalyzes the conversion reaction of discharge intermediate LiO_(2)*to LiOH and that Ag particles promote its catalytic ability.In the presence of Ag/δ-MnO_(2)@CP cathode,the LOB exhibits enhanced specific capacity and a high discharge voltage plateau under humid O_(2)atmosphere.At a current density of 200 mA g^(−1),the LOB with the Ag/δ-MnO_(2)@CP cathode presents an overpotential of 0.5 V and an ultra-long cycle life of 867 cycles with a limited specific capacity of 500 mA h g^(−1).This work provides a fresh view on the role of solid catalysts in LOBs and promotes the development of LOBs based on LiOH discharge product for practical applications.

In-situ production of ozone and ultraviolet light using a barrier discharge reactor for wastewater treatment

A dielectric barrier discharge (DBD) reactor consisting of water-filled dielectric tube electrodes was used for the treatment of wastewater. The inner dielectric tube, which acted as the discharging electrode, was filled with an aqueous electrolyte solution. The outer dielectric tube, which served as the other electrode, was in contact with the wastewater, which was grounded. The present reactor system was energy-efficient for the production of ozone, not only because the perfect contact between the aqueous electrode and the dielectric surface minimized the loss of the electrical energy, but also because the DBD reactor was cooled by the wastewater. In addition, the ultraviolet (UV) light produced in the DBD reactor was able to assist in the wastewater treatment since the quartz tube used as the dielectric material was UV-transparent. The performance of the present DBD system was evaluated using a synthetic wastewater formed from distilled water and an azo dye, amaranth. The experimental parameters were the concentration of the electrolyte in the aqueous electrode, the discharge power, the initial pH of the wastewater and the concentration of hydrogen peroxide added to the wastewater. The wastewater treatment system was found to be effective for achieving decomposition of the dye.