Designing Membrane Electrode Assembly for Electrochemical CO_(2)Reduction:a Review

Currently, the electrochemical CO_(2) reduction reaction (CO_(2) RR) can realize the resource conversion of CO_(2) , which is a promising approach to carbon resource use. Important advancements have been made in exploring the CO_(2) RR performance and mechanism because of the rational design of electrolyzer systems, such as H-cells, flow cells, and catalysts. Considering the future development direction of this technology and large-scale application needs, membrane electrode assembly (MEA) systems can improve energy use efficiency and achieve large-scale CO_(2) conversion, which is considered the most promising technology for industrial applications. This review will concentrate on the research progress and present situation of the MEA component structure. This paper begins with the composition and construction of a gas diff usion electrode. Then, the application of ion-exchange membranes in MEA is introduced. Furthermore, the eff ects of pH and the anion and cation of the anolyte on MEA performance are explored. Additionally, we present the anode reaction type in MEA. Finally, the challenges in this field are summarized, and upcoming trends are projected. This review should offer researchers a clearer picture of MEA systems and provide important, timely, and valuable insights into rational electrolyzer design to facilitate further development of CO_(2) electrochemical reduction.

Novel Perovskite Oxide Hybrid Nanofibers Embedded with Nanocatalysts for Highly Efficient and Durable Electrodes in Direct CO_(2) Electrolysis

The unique characteristics of nanofibers in rational electrode design enable effec-tive utilization and maximizing material properties for achieving highly efficient and sustainable CO_(2) reduction reactions( CO_(2)RRs)in solid oxide elec-trolysis cells(SOECs).However,practical appli-cation of nanofiber-based electrodes faces chal-lenges in establishing sufficient interfacial contact and adhesion with the dense electrolyte.To tackle this challenge,a novel hybrid nanofiber electrode,La_(0.6)Sr_(0.4)Co_(0.15)Fe_(0.8)Pd_(0.05)O_(3-δ)(H-LSCFP),is developed by strategically incorporating low aspect ratio crushed LSCFP nanofibers into the excess porous interspace of a high aspect ratio LSCFP nanofiber framework synthesized via electrospinning technique.After consecutive treatment in 100% H_(2) and CO_(2) at 700°C,LSCFP nanofibers form a perovskite phase with in situ exsolved Co metal nanocatalysts and a high concentration of oxygen species on the surface,enhancing CO_(2) adsorption.The SOEC with the H-LSCFP electrode yielded an outstanding current density of 2.2 A cm^(-2) in CO_(2) at 800°C and 1.5 V,setting a new benchmark among reported nanofiber-based electrodes.Digital twinning of the H-LSCFP reveals improved contact adhesion and increased reaction sites for CO_(2)RR.The present work demonstrates a highly catalytically active and robust nanofiber-based fuel electrode with a hybrid structure,paving the way for further advancements and nanofiber applications in CO_(2)-SOECs.

Interface and energy band manipulation of Bi2O3-Bi2S3 electrode enabling advanced magnesium-ion storage

Rechargeable magnesium-ion(Mg-ion)batteries have attracted wide attention for energy storage.However,magnesium anode is still limited by the irreversible Mg plating/stripping procedure.Herein,a well-designed binary Bi_(2)O_(3)-Bi_(2)S_(3)(BO-BS)heterostructure is fulfilled by virtue of the cooperative interface and energy band engineering targeted fast Mg-ion storage.The built-in electronic field resulting from the asymmetrical electron distribution at the interface of electron-rich S center at Bi_(2)S_(3) side and electron-poor O center at Bi_(2)O_(3) side effectively accelerates the electrochemical reaction kinetics in the Mg-ion battery system.Moreover,the as-designed heterogenous interface also benefits to maintaining the electrode integrity.With these advantages,the BO-BS electrode displays a remarkable capacity of 150.36 mAh g^(−1) at 0.67 A g^(-1) and a superior cycling stability.This investigation would offer novel insights into the rational design of functional heterogenous electrode materials targeted the fast reaction kinetics for energy storage systems.

Synergistic Coupling of Sulfide Electrolyte and Integrated 3D FeS_(2)Electrode Toward Long-Cycling All-Solid-State Lithium Batteries

FeS_(2)cathode is promising for all-solid-state lithium batteries due to its ultra-high capacity,low cost,and environmental friendliness.However,the poor performances,induced by limited electrode-electrolyte interface,severe volume expansion,and polysulfide shuttle,hinder the application of FeS_(2)in all-solid-state lithium batteries.Herein,an integrated 3D FeS_(2)electrode with full infiltration of Li6PS5Cl sulfide electrolytes is designed to address these challenges.Such a 3D integrated design not only achieves intimate and maximized interfacial contact between electrode and sulfide electrolytes,but also effectively buffers the inner volume change of FeS_(2)and completely eliminates the polysulfide shuttle through direct solid-solid conversion of Li2S/S.Besides,the vertical 3D arrays guarantee direct electron transport channels and horizontally shortened ion diffusion paths,endowing the integrated electrode with a remarkably reduced interfacial impedance and enhanced reaction kinetics.Benefiting from these synergies,the integrated all-solid-state lithium battery exhibits the largest reversible capacity(667 mAh g^(-1)),best rate performance,and highest capacity retention of 82%over 500 cycles at 0.1 C compared to both a liquid battery and non-integrated all-solid-state lithium battery.The cycling performance is among the best reported for FeS_(2)-based all-solid-state lithium batteries.This work presents an innovative synergistic strategy for designing long-cycling high-energy all-solid-state lithium batteries,which can be readily applied to other battery systems,such as lithium-sulfur batteries.

Enhanced electrochemical carbon dioxide reduction in membrane electrode assemblies with acidic electrolytes through a silicate buffer layer

The electrochemical reduction of CO_(2)holds considerable promise in combating global climate change while yielding valuable chemical commodities.Membrane electrode assemblies operating within acidic electrolyte have exhibited noteworthy advancements in CO_(2)utilization efficiency,albeit encountering formidable competition from the hydrogen evolution reaction.In our investigation,we introduced a silicate buffer layer,which yielded exceptional outcomes even using strong acid electrolyte.Notably,our approach yielded a CO Faradic efficiency of 90%and reached a substantial current density of 400 mA cm^(-2).Furthermore,our system displayed remarkable stability over a 12-hour duration,and achieved a high single-pass-conversion efficiency of 67%.Leveraging in-situ Raman analysis,we attributed these performance enhancements to the augmented CO_(2)adsorption and localized alkaline environment facilitated by the incorporation of the silicate buffer layer.We think the addition of buffer layer to adjust the microenvironment is essential to achieve high performance and keep stable in acid condition.

High Seebeck Coefficient Thermally Chargeable Supercapacitor with Synergistic Effect of Multichannel Ionogel Electrolyte and Ti_(3)C_(2)T_(x) MXene-Based Composite Electrode

Thermally chargeable supercapacitors can collect low-grade heat generated by the human body and convert it into electricity as a power supply unit for wearable electronics.However,the low Seebeck coefficient and heat-to-electricity conversion efficiency hinder further application.In this paper,we designed a high-performance thermally chargeable supercapacitor device composed of ZnMn_(2)O_(4)@Ti_(3)C_(2)T_(x)MXene composites(ZMO@Ti_(3)C_(2)T_(x) MXene)electrode and UIO-66 metal–organic framework doped multichannel polyvinylidene fluoridehexafluoro-propylene ionogel electrolyte,which realized the thermoelectric conversion and electrical energy storage at the same time.This thermally chargeable supercapacitor device exhibited a high Seebeck coefficient of 55.4 mV K^(−1),thermal voltage of 243 mV,and outstanding heat-to-electricity conversion efficiency of up to 6.48%at the temperature difference of 4.4 K.In addition,this device showed excellent charge–discharge cycling stability at high-temperature differences(3 K)and low-temperature differences(1 K),respectively.Connecting two thermally chargeable supercapacitor units in series,the generated output voltage of 500 mV further confirmed the stability of devices.When a single device was worn on the arm,a thermal voltage of 208.3 mV was obtained indicating the possibility of application in wearable electronics.

Influence of nano-CeO_2 on coating structure and properties of electrodeposited Al/α-PbO_2/β-PbO_2

Al/α-PbO2/β-PbO2 composite electrodes doped with rare earth oxide （CeO2） were prepared by anodic oxidation method investigate the influence of nano-CeO2 dopants on the properties of Al/α-PbO2/β-PbO2-CeO2 electrodes and the impact of α-PbO2 as the intermediate layer. The results show that using α-PbO2 as the intermediate layer will benefit the crystallization of β-PbO2 and β-PbO2 is more suitable as the surface layer than α-PbO2. CeO2 dopants change the crystallite size and crystal structure, enhance the catalytic activity, and even change the deposition mechanism of PbO2. The doping of CeO2 in the PbO2 electrodes can enhance the electro-catalytic activity, which is helpful for oxygen evolution, and therefore reduce the cell voltage.

Structures and electrochemical hydrogen storage performance of Si added A_2B_7-type alloy electrodes

In order to ameliorate the electrochemical hydrogen storage performance of La-Mg-Ni system A2B7-type electrode alloys, a small amount of Si was added. The La0.8Mg0.2Ni3.3Co0.2Six （x=0-0.2） electrode alloys were prepared by casting and annealing. The effects of adding Si on the structure and electrochemical hydrogen storage characteristics of the alloys were investigated systematically. The results indicate that the as-cast and annealed alloys hold multiple structures, involving two major phases of （La, Mg）2Ni7 with a Ce2Ni7-type hexagonal structure and LaNi5 with a CaCu5-type hexagonal structure as well as one residual phase LaNi3. The addition of Si results in a decrease in （La, Mg）2Ni7 phase and an increase in LaNi5 phase without changing the phase structure of the alloys. What is more, it brings on an obvious effect on electrochemical hydrogen storage characteristics of the alloys. The discharge capacities of the as-cast and annealed alloys decline with the increase of Si content, but their cycle stabilities clearly grow under the same condition. Furthermore, the measurements of the high rate discharge ability, the limiting current density, hydrogen diffusion coefficient as well as electrochemical impedance spectra all indicate that the electrochemical kinetic properties of the electrode alloys first increase and then decrease with the rising of Si content.

Electrochemical oxidation of aniline by a novel Ti/TiO_xH_y/Sb-SnO_2 electrode

Electrochemical oxidation of aniline in aqueous solution was investigated over a novel Ti/TiOxHy/Sb-SnO2 electrode prepared by the electrodeposition method.Scanning electron microscopy,X-ray diffraction,and electrochemical measurements were used to characterize its morphology,crystal structure,and electrochemical properties.Removal of aniline by the Ti/TiOxHy/Sb-SnO2electrode was investigated by ultraviolet-Visible spectroscopy and chemical oxygen demand（COD）analysis under different conditions,including current densities,initial concentrations of aniline,pH values,concentrations of chloride ions,and types of reactor.It was found that a higher current density,a lower initial concentration of aniline,an acidic solution,the presence of chloride ions（0.2wt%NaCl）,and a three-dimensional（3D） reactor promoted the removal efficiency of aniline.Electrochemical degradation of aniline followed pseudo-first-order kinetics.The aniline（200 mL of 100mg·L-（-1）） and COD removal efficiencies reached 100%and 73.5%,respectively,at a current density of 20 mA·cm-（-2）,pH of 7.0,and supporting electrolyte of 0.5 wt%Na2SO4 after 2 h electrolysis in a 3D reactor.These results show that aniline can be significantly removed on the Ti/TiOxHy/Sb-SnO2electrode,which provides an efficient way for elimination of aniline from aqueous solution.

LiCoO_2表面沉积ZrO_2涂层的结构和电化学性能

为了提高LiCoO2材料的电化学性能,采用浸渍的方法,在LiCoO2的表面沉积纳米ZrO2涂层.将Zr(OH)x(CH3COO)y溶解在去离子水中,然后浸入LiCoO2,经超声波处理,蒸发溶剂,最后高温焙烧后,得到产物.用X射线吸收近边光谱(XANES)对涂层后的LiCoO2结构进行测试,检测涂层对其结构的作用效果.循环伏安实验结果表明,涂层对电极材料的氧化和还原行为有影响.恒电流充放电结果表明,LiCoO2沉积ZrO2涂层后,常温下性能改变较小,但是可以提高其在较高温度(如55℃)下的充放电性能.

Effects of current density on preparation and performance of Al/conductive coating/α-PbO_2-Ce O_2-TiO_2/β-Pb O_2-MnO_2-WC-ZrO_2 composite electrode materials

Al/conductive coating/α-Pb O2-Ce O2-Ti O2/β-PbO 2-MnO 2-WC-Zr O2 composite electrode material was prepared on Al/conductive coating/α-PbO 2-Ce O2-Ti O2 substrate by electrochemical oxidation co-deposition technique. The effects of current density on the chemical composition, electrocatalytic activity, and stability of the composite anode material were investigated by energy dispersive X-ray spectroscopy（EDXS）, anode polarization curves, quasi-stationary polarization（Tafel） curves, electrochemical impedance spectroscopy（EIS）, scanning electron microscopy（SEM）, and X-ray diffraction（XRD）. Results reveal that the composite electrode obtained at 1 A/dm2 possesses the lowest overpotential（0.610 V at 500 A/m2） for oxygen evolution, the best electrocatalytic activity, the longest service life（360 h at 40 °C in 150 g/L H2SO4 solution under 2 A/cm2）, and the lowest cell voltage（2.75 V at 500 A/m2）. Furthermore, with increasing current density, the coating exhibits grain growth and the decrease of content of Mn O2. Only a slight effect on crystalline structure is observed.

微波-高分子网络法合成微米级LiCoO_2

报道了首次利用微波 高分子网络法合成锂离子蓄电池正极材料LiCoO2 的工艺条件。XRD及SEM测试结果表明 :微波 高分子网络法不仅合成速度快有效节约能源 ,而且颗粒度达到微米级且分散均匀。无需对材料进行任何机械研磨 ,有效克服了传统合成工艺颗粒度大 ,电化学活性点较低的缺点。电化学性能测试表明 :微波 高分子网络法合成的样品同时具有电化学容量高 ,放电平台高 (约 3.8V) ,循环衰减率低 ,循环稳定性好等优点 ,具有较好的推广应用前景。

不同厂家热电池FeS_(2)-CoS_(2)复合正极材料的比较研究

为了加快热电池FeS_(2)-CoS_(2)复合正极材料的优化及应用,采用两种不同厂家生产的CoS_(2)作为导电剂添加到FeS_(2)中,制备出FeS_(2)-CoS_(2)复合正极材料及其单体电池,并对两种CoS_(2)原材料、FeS_(2)-CoS_(2)复合正极材料的微观形貌、粒度分布、X射线衍射分析以及单体电池的放电性能进行了研究。结果表明,广东产的FeS_(2)-CoS_(2)正极材料具有更均匀的微观分布和较少的小粒度粒子,湖南产的FeS_(2)-CoS_(2)正极材料更适合小电流放电应用,而广东产的FeS_(2)-CoS_(2)正极材料更适合于高功率放电。此外,将两种FeS_(2)-CoS_(2)正极材料应用于某型号热电池并进行高低温放电测试,结果表明广东产的FeS_(2)-CoS_(2)正极材料在放电性能上优于湖南产的FeS_(2)-CoS_(2)正极材料。

纳米颗粒状MoO_(2)@碳纳米管复合纤维电极的制备及其电性能

设计了一种纳米颗粒状MoO_(2)@碳纳米管(CNT)复合纤维电极结构。通过简单的电化学沉积方法和一系列表征技术,将直径为10~50 nm MoO_(2)纳米颗粒均匀分散于CNT纤维束的表面及内部,获得了柔韧性、稳定性优异的纤维电极材料。研究了其作为水系锌离子电池正极材料的电性能和电化学行为。研究结果表明该纤维电极材料在900 mA/cm^(3)(4.7 A/g)电流密度下,常温循环1700周后,容量保持率为109%,-30℃低温下循环1000周后,容量保持率为103%,具有优异的常温和低温循环稳定性;1800 mA/cm^(3)(9.4 A/g)电流密度下,放电容量仍有17.5 mA·h/cm^(3)(91.5 mA·h/g),表现出优异的倍率性能。此外,研究得出Zn^(2+)嵌入/脱出过程主要发生在Mo—O—C键上,且整个充放电过程中主要在Mo^(6+)、Mo^(5+)和Mo^(4+)间发生了氧化还原反应,为开发新型纤维电极材料提供了新思路。

TUNGSTEN ELECTRODES CONTAINING THREE TYPES OF RARE EARTH OXIDES

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Emerging CoMn-LDH@MnO2 electrode materials assembled using nanosheets for flexible and foldable energy storage devices

CoMn layered double hydroxides(CoMn-LDH)are promising electrode materials for supercapacitors because of their excellent cyclic stability.However,they possess relatively low capacitances.In this work,hybrid CoMn-LDH@MnO2 products grown on Ni foams were obtained through a facile hydrothermal method.The as-synthesized samples employed as electrodes deliver a specific capacitance of 2325.01 F g^-1 at 1 A g^-1.An assembled asymmetric supercapacitor using these products as positive electrodes shows a maximum energy density of 59.73 W h kg^-1 at 1000.09 W kg^-1.The prominent electrochemical performance of the as-prepared electrodes could be attributes to hierarchical structures.These findings suggest that hybrid structures might be potential alternatives for future flexible energy storage devices.

Effect of Sb dopant amount on the structure and electrocatalytic capability of Ti/Sb-SnO_2 electrodes in the oxidation of 4-chlorophenol

Ti/Sb-SnO2 anodes were prepared by thermal decomposition to examine the influence of the amount of Sb dopant on the structure and electrocatalytic capability of the electrodes in the oxidation of 4-chlorophenol. The physicochemical properties of the Sb-SnO2 coating were markedly influenced by different amounts of Sb dopant. The electrodes, which contained 5% Sb dopant in the coating, presented a much more homogenous surface and much smaller mud-cracks, compared with Ti/Sb-SnO2 electrodes containing 10% or 15% Sb dopant, which exibited larger mud cracks and pores on the surface. However, the main microstructure remained unchanged with the addition of the Sb dopant. No new crystal phase was observed by X-ray diffraction （XRD）. The electrochemical oxidation of 4-chlorophenol on the Ti/SnO2 electrode with 5% Sb dopant was inclined to electrochemical combustion; while for those containing more Sb dopant, intermediate species were accumulated. The electrodes with 5% Sb dopant showed the highest efficiency in the bulk electrolysis of 4-chlorophenol at a current density of 20 mA/cm^2 for 180 min; and the removal rates of 4-chlorophenol and COD were 51.0% and 48.9%, respectively.

Ultrathin nanosheets of cobalt-nickel hydroxides hetero-structure via electrodeposition and precursor adjustment with excellent performance for supercapacitor

A homogeneous better-dispersed ultrathin nanosheets（ca. 5 nm） of cobalt-nickel layered double hydroxides（LDH） supported on nickel foam scaffold was synthesized using controllable electrodeposition approach for high efficiency electrode materials of new supercapacitor. The morphology and electrochemical performances of the samples can be controlled by adjusting the precursor ratio, i.e., Ni（OAc）2/Co（NO3）2 molar ratio in the electrodeposition approach. With the increase of this molar ratio, the electrochemical performances give a volcano trend. When the optimized molar ratio is 0.64/0.36, the hybrid delivered a high specific capacitance of 1587.5 F g-1 at a current density of 0.5 A g-1, with good rate capability（1155 F g-1 was retained even at 10 A g-1） and a robust recycle stability（remaining 91.5% after 1000 cycles at 5 A g-1）. The good performance could be attributed to the enlarged interlayer spacing, ultrathin nanosheets and synergistic effects between Co（OH）2 and Ni（OH）2. Furthermore, an asymmetric supercapacitor with a high energy density of 34.5 Wh kg-1 at 425 W kg-1 and excellent cycling stability of 85.4% after 5000 charge-discharge cycles at 2 A g-1 was fabricated. We believe that this fantabulous new electrode material would have encouraging applications in electrochemical energy storage and a wide readership.

微型薄膜锂离子电池正极材料LiCoO_2薄膜研究

研究了应用于微型全固态薄膜锂离子电池的正极材料钴酸锂LiCoO_2薄膜材料,采用磁控溅射法来制备,对其进行400℃退火处理后,进行XRD分析和SEM分析,表明在低气压条件下制备的薄膜呈非晶态,经过退火后,形成了排列致密的晶体结构,薄膜沿(003)晶面平行于基底择优生长;循环伏安测试和恒电流充放电测试表明,未经过退火处理的LiCoO_2薄膜不具有锂离子嵌入/脱出的可逆性,而经过退火处理的LiCoO_2薄膜从第二圈开始具有较好的可逆性。制备的LiCoO_2薄膜结晶状态优良、质地紧密、与衬底薄膜紧密接触、循环性能和循环充放电性能良好,可以用于微型全固态薄膜锂离子电池。

Enhancing Capacitance Performance of Ti3C2Tx MXene as Electrode Materials of Supercapacitor: From Controlled Preparation to Composite Structure Construction

Ti3C2Tx,a novel two-dimensional layer material,is widely used as electrode materials of supercapacitor due to its good metal conductivity,redox reaction active surface,and so on.However,there are many challenges to be addressed which impede Ti3C2Tx obtaining the ideal specific capacitance,such as restacking,re-crushing,and oxidation of titanium.Recently,many advances have been proposed to enhance capacitance performance of Ti3C2Tx.In this review,recent strategies for improving specific capacitance are summarized and compared,for example,film formation,surface modification,and composite method.Furthermore,in order to comprehend the mechanism of those efforts,this review analyzes the energy storage performance in different electrolytes and influencing factors.This review is expected to predict redouble research direction of Ti3C2Tx materials in supercapacitors.