Cathode Support Research Articles

The beneficial effects of straight open large pores in the support on steam electrolysis performance of electrode-supported solid oxide electrolysis cell

This study is aimed at improving the electrochemical performance of electrode-supported solid oxide electrolysis cells (SOECs) by optimizing the pore structure of the supports. Two planar NiO–8 mol% yttria-stabilized zirconia supports are prepared, one by the phase-inversion tape casting, and the other by conventional tape casting method using graphite as the pore former. The former contains finger-like straight open large pores, while the latter contains randomly distributed and tortuous pores. The steam electrolysis of the cells with different microstructure cathode supports is measured. The cell supported on the cathode with straight pores shows a high current density of 1.42 A cm−2 and a H2 production rate of 9.89 mL (STP) cm−2 min−1 at 1.3 V and 50 vol % humidity and 750 °C, while the cell supported on the cathode with tortuous pores shows a current density of only 0.91 A cm−2 and a H2 production rate of 6.34 mL cm−2min−1. It is concluded that the introduction of large straight open pores into the cathode support allows fast gas phase transport and thus minimizes the concentration polarization. Furthermore, the straight pores could provide better access to the reaction site (the electrode functional layer), thereby reducing the activation polarization as well.

In Situ Mg/MgO-Embedded Mesoporous Carbon Derived from Magnesium 1,4-Benzenedicarboxylate Metal Organic Framework as Sustainable Li-S Battery Cathode Support.

Development of advanced carbon cathode support with the ability to accommodate high sulfur (S) content as well as effective confinement of the sulfur species during charge–discharge is of great importance for sustenance of Li–S battery. A facile poly(vinylpyrrolidone)-assisted solvothermal method is reported here to prepare Mg–1,4-benzenedicarboxylate metal organic framework (MOF) from which mesoporous carbon is derived by thermal treatment, where the hexagonal sheetlike morphology of the parent MOF is retained. Existence of abundant pores of size 4 and 9 nm extended in three dimensions with zigzag mazelike channels helps trapping of S in the carbon matrix through capillary effect, resulting in high S loading. When tested as a cathode for lithium–sulfur battery, a reversible specific capacity of 1184 mAh g–1 could be achieved at 0.02 C. As evidenced by X-ray photoelectron spectroscopy, in situ generated Mg in the carbon structure enhances the conductivity, whereas MgO provides support to S immobilization through chemical interactions between Mg and sulfur species for surface polarity compensation, restricting the dissolution of polysulfide into the electrolyte, the main cause for the “shuttle phenomenon” and consequent capacity fading. The developed cathode shows good electrochemical stability with reversible capacities of 602 and 328 mAh g–1 at 0.5 and 1.0 C, respectively, with retentions of 64 and 67% after 200 cycles. The simple MOF-derived strategy adopted here would help design new carbon materials for Li–S cathode support.

(Invited) Durability Evaluation of PEM Fuel Cells for Automotive Application

Proton exchange membrane fuel cells (PEMFC) technology is already in commercialization phase for automotive applications. However, the biggest challenges for its successful mass commercialization are cost and durability. Current PEMFC technology can meet the lifetime targets but the cost to achieve it can be very high due to material’s cost and system level mitigation complexities. Understanding of the membrane electrode assemblies (MEA) degradations using relevant durability accelerated tests at early stages of development is essential. PEMFCs for automotive applications goes through thousands of cycles during normal operation of the vehicle over the expected life span of 10 years. These cycles include a combination of load or voltage cycles, start and stop cycles, humidity cycles and temperature cycles. Study have shown that start-stop cycling accounts for 44% of operation mode while load cycling and idling for 28% each (1). Under these cycles, fuel cells suffer from severe degradations of its main components; cathode, anode, membrane and bipolar plates. The PEMFC cathode can degrade during start-stop operation via carbon corrosion (2). Cathode degradation can be mitigated by using stable materials or by applying system mitigations. System mitigation by a voltage limiting control (VLC) can be one of the effective measures (3). The VLC can, however, lead to voltage spikes (high positive potentials) at the anode during fuel cell start-up and shut-down. Moreover, during fuel (H2) starvation conditions, the potential at the anode can give rise to high positive potentials leading to anode catalyst layer degradation. During idling operation mode, PEMFC is at or near open circuit conditions which is known to accelerate proton exchange membrane (PEM) decomposition especially under low humidification (4). Peroxy-radicals originating from hydrogen peroxide produced at the anode catalyst surface cause the PEM degradation (5). Pt band formation in the membrane is also known to promote peroxide formation leading to membrane decomposition (6-7). Several accelerated protocols are currently being used to evaluate the durability of PEMFC. At Nissan, our durability protocols are focused on understanding the material degradation under relevant automotive cycles and correlating single cell durability to the stack level. Start-stop accelerated protocol to evaluate the cathode support durability consist of potential cycling from 1.0 V to 1.5 V using triangular waveform for 1000 cycles with diagnostics conducted intermittently after certain number of cycles. Cathode catalyst durability is evaluated using load cycling accelerated protocol wherein the potential is cycled between 0.6 V to 0.95 V to simulate peak load and OCV/idle using a square wave profile with 3 second hold at each potential. The upper potential is known to have significant impact on catalyst degradation (8). Load cycling is performed for 10,000 cycles with diagnostics conducted intermittently. Anode degradation under cell reversal condition is evaluated using a protocol designed to simulate high voltage spikes at the anode. Cell reversal cycling is performed by applying a load of 0.2 A/cm2 for 1 sec while flowing N2 at the anode and air at the cathode while measuring the cell voltage under the applied load for a total of 200 cycles. Membrane durability is evaluated using humidity cycling (mechanical durability) and potential hold at open circuit (chemical durability). Membrane’s chemical durability is evaluated at 90 °C and 30% RH under hydrogen and oxygen by operating MEA at open circuit. The target of OCV hold test is 500 hrs while maintaining potential above 0.8 V. Mechanical durability of membrane is evaluated by cycling RH to simulate dry condition (0%) and wet condition (100%) for target of 20,000 cycles. All these accelerated tests are performed at ambient pressure and summarized in the Table 1 below. Acknowledgments: The author would like to gratefully acknowledge Nissan Technical Center North America Fuel Cell Research team members (Dr. Amod Kumar, Dr. Ramesh Yadav and Dr. Cenk Gumeci) and Nissan Motor Co. Ltd Japan Fuel Cell research team members (Dr. Atsushi Ohma, Dr. Yoshihisa Furuya) for technical discussions and data.

Tuning the Adsorption of Polysulfides in Lithium–Sulfur Batteries with Metal–Organic Frameworks

The dissolution of polysulfide (PS) intermediates during discharge is a well-known obstacle to achieving long cycle life in lithium–sulfur batteries. Prior work has shown that PS dissolution can be partially suppressed via physical encapsulation of sulfur and PS within a porous cathode support. Metal–organic frameworks (MOFs) are crystalline, nanoporous materials with extremely high surface areas, whose structure and composition can be varied extensively. MOFs are promising cathode support materials because the encapsulation afforded by MOF pores can be augmented by chemical adsorption of PS onto coordinately unsaturated metal sites (CUS). Here, we demonstrate that this additive approach—restricting PS dissolution by combining encapsulation and adsorption within a MOF—can be tuned to maximize PS anchoring via metal substitution on the CUS. Optimal MOF compositions are pinpointed by computationally screening 16 metal-substituted variants of M2(dobdc) (MOF-74) for their ability to chemically anchor prototyp...

Lowering the co-sintering temperature of cathode–electrolyte bilayers for micro-tubular solid oxide fuel cells

Abstract To prevent undesirable reactions between the cathode and electrolyte materials in cathode-supported solid oxide fuel cells (SOFCs), the co-sintering temperature of these two layers must be lowered. In the present work, we employed different strategies to lower the co-sintering temperature of cathode–electrolyte bilayers for micro-tubular SOFCs by increasing the cathode sintering shrinkage and adding sintering aids to the electrolyte. Strontium-doped lanthanum manganite (LSM) and yttria-stabilized zirconia (YSZ) were used as the cathode and electrolyte materials, respectively. To facilitate densification of the electrolyte layer by controlling the shrinkage of the cathode support, the particle size of the LSM powder was reduced by high-energy ball milling and different amounts of micro-crystalline cellulose pore former were used. Sintering aids, namely NiO and Fe 2 O 3 , were also added to the YSZ electrolyte to further improve its low-temperature sintering. Our results indicate that with the improvement in the cathode support shrinkage and use of the small amounts of sintering aids, the cathode–electrolyte co-sintering temperature can be reduced to 1250–1300 °C. It was also observed that the presence of the sintering aids helps to reduce the reactivity between the LSM cathode and YSZ electrolyte.

Research on the performance of tubular cathode for direct ethanol fuel cell

Through the gel-casting process, the tubular cathode for direct ethanol fuel cell (DEFC) is prepared using the mesocarbon microbeads (MCMB) and graphite as the main raw materials. According to the tubular cathode’s physical performance and electrical property tests, the performance of cathode tube is studied at different graphite proportions. As shown by the results of strength test, the strength of cathode tube is better with a graphite ratio from 0 to 40%. It can be found that the linear and volumetric shrinkage of tubular cathode support will decrease with the increment of the graphite content. As displayed by the electrical property tests, the charge transmission ability is extremely close when the graphite surpasses 30%. With 40% of graphite doping ratio, the electrode electrochemical reaction will be reinforced when the temperature gets higher. In the meanwhile, the electricity capacity will be higher when the air flow rate is 100 mL min–1.

Mechanical and Durable Properties of Ni-YSZ Electrode Under High Temperature for Solid Oxide Electrolysis Stack

Many researches based on SOFC development and high temperature electrolysis (HTE) have been reported in the last couple of decades. HTE is one of the most clean and efficient technologies for manufacturing large amounts of hydrogen from water with oxygen. The processing and structure of HTE is closely related to the knowledge and concept of solid oxide fuel cells (SOFCs). Specially, it is very important to evaluate the durability’s properties of oxide electrolysis stacks under high temperature as well as steam environment to apply HTE. Unfortunately, no study has been reported the durable properties of oxide electrolysis stacks at high temperature as well as steam environment. For the reason, the aim of this work is to realize the durable properties (ex, high temperature strength fatigue and creep) at high temperature of 600°C~850°C for oxide electrolysis stacks which consists of 55%NiO-45%YSZ(8mol%Y2O3) composition. NiO-YSZ cathode supports were prepared in the shape of flat tubes by extrusion method. The pre-sintered NiO-YSZ flat tubes were dip-coated in YSZ slurry to secure the interconnector area with a masking fluid and then were sintered at 1400°C for 3h. The creep properties showed decreasing tendency with increasing applied load in range of 40~80MPa and temperature in range of 600°C~800°C. The life time of fatigue at 850°C under Ar-4%H2O environment was decreased with increasing applied load.

Intrinsic Conductivity in Magnesium-Oxygen Battery Discharge Products: MgO and MgO2

Non-aqueous magnesium-oxygen (or ‘Mg-air’) batteries are attractive next generation energy storage devices due to their high theoretical energy densities, low cost, and potential for rechargeability. Prior experiments identified magnesium oxide, MgO, and magnesium peroxide, MgO2, as the primary discharge products in a Mg/O2 cell. Charge transport within these nominally-insulating compounds is expected to limit battery performance, yet these transport mechanisms are either incompletely understood (MgO2) or remain a matter of debate (MgO). The present study characterizes the conductivity associated with intrinsic (point) defects within both compounds using first-principles calculations. For MgO, negative Mg vacancies and hole polarons localized on oxygen anions were identified as the dominant charge carriers. Nevertheless, the large formation energies associated with these carriers suggest that their equilibrium concentrations are low. Furthermore, a large asymmetry exists in the carrier mobility: Mg vacancies are essentially immobile at room temperature, while hole polarons are highly mobile. Importantly, the calculated formation and mobility data for MgO are in remarkable agreement with the three “Arrhenius branches” observed in conductivity experiments, and thus clarify the long-debated transport mechanisms within these regimes. In the case of MgO2, electronic charge carriers alone – electron and hole polarons – are the most prevalent. Similar to MgO, the concentration of carriers in MgO2 is low, and poor mobility further limits conductivity. We conclude that: (i.) sluggish charge transport in MgO or MgO2 will limit battery performance when these compounds cover the cathode support, and (ii.) what little conductivity exists is primarily electronic in nature (i.e., polaron hopping). Artificially increasing the carrier concentration is suggested as a strategy for improving battery performance.

Demonstrating the potential of yttrium-doped barium zirconate electrolyte for high-performance fuel cells

In reducing the high operating temperatures (≥800 °C) of solid-oxide fuel cells, use of protonic ceramics as an alternative electrolyte material is attractive due to their high conductivity and low activation energy in a low-temperature regime (≤600 °C). Among many protonic ceramics, yttrium-doped barium zirconate has attracted attention due to its excellent chemical stability, which is the main issue in protonic-ceramic fuel cells. However, poor sinterability of yttrium-doped barium zirconate discourages its fabrication as a thin-film electrolyte and integration on porous anode supports, both of which are essential to achieve high performance. Here we fabricate a protonic-ceramic fuel cell using a thin-film-deposited yttrium-doped barium zirconate electrolyte with no impeding grain boundaries owing to the columnar structure tightly integrated with nanogranular cathode and nanoporous anode supports, which to the best of our knowledge exhibits a record high-power output of up to an order of magnitude higher than those of other reported barium zirconate-based fuel cells.

A Highly-Performed, Dual-Layered Cathode Supported Solid Oxide Electrolysis Cell for Efficient CO2 Electrolysis Fabricated by Phase Inversion Co-Tape Casting Method

Efficient conversion of CO2 to fuels through electrolysis is a promising approach for energy storage and CO2 utilization. In this study, Ni-YSZ cathode support with hierarchically oriented finger-like macro-pores is fabricated by phase inversion co-tape casting method to minimize the concentration polarization and enhance the cell performance. More important, an active cathode functional layer is introduced between support and electrolyte in order to decrease the activation polarization and further improve the cell performance. A bilayered YSZ/GDC electrolyte is also employed to achieve high ionic conductivity and low electronic conductivity, and thereby to improve the cell efficiency and lower the operation temperature. Consequently, the electrolyzer exhibits a relatively high electrolysis current density of −1.107 A cm−2 and a significantly low electrode polarization resistance of 0.32 Ωcm2 at 700°C and 1.3 V when the cathode and anode are exposed to 67%CO2-33%CO and ambient air, respectively, resulting from remarkably decreased concentration and activation polarization. Thermodynamics calculations imply that the cells may suffer from the carbon coke issue in the CO-rich atmospheres, but no evidence of coking has been observed by SEM and Raman Spectroscopy, indicating that further work should be done to deeper understand the coking issue during the CO2 electrolysis process.

A novel cathode architecture using Cu nanoneedle arrays as the cathode support for AAEMFC application

A novel cathode architecture using vertically aligned Cu nanoneedle arrays (NNAs) as an ordered support for alkaline anion-exchange membrane fuel cell (AAEMFC) application is developed.

A Study on Sintering Inhibition of La0.8 Sr0.2 MnO3-∂ Cathode Material for Cathode-Supported Fuel Cells

In this work, the effects of different sintering inhibitors added to La0.8Sr0.2MnO3-∂ (LSM) were studied to obtain an optimum cathode material for cathode-supported type of Solid oxide fuel cell (SOFC) in terms of phase stability, mechanical strength, electric conductivity and porosity. Four different sintering inhibitors of Al2O3, CeO2, NiO and gadolinium doped ceria (GDC) were mixed with LSM powder, sintered at 1300°C and then they were evaluated. The phase stability, sintering behavior, electrical conductivity, mechanical strength and microstructure were evaluated in order to assess the performance of the mixture powder as cathode support material. It has been found that the addition of Al2O3 undesirably decreased the electrical conductivity of LSM; other sintering inhibitors, however, showed sufficient levels of electrical conductivity. GDC and NiO addition showed a promising increase in mechanical strength of the LSM material, which is one of the basic requirements in cathode-supported designs of fuel cells. However, NiO showed a high reactivity with LSM during high temperature (1300°C) sintering. So, this study concluded that GDC is a potential candidate for use as a sintering inhibitor for high temperature sintering of cathode materials. Key words: Cathode support, Sintering inhibition, SOFC

In Situ Analysis of the Li–O2 Battery with Thermally Reduced Graphene Oxide Cathode: Influence of Water Addition

The Li–O2 battery technology holds the promise to deliver a battery with significantly increased specific energy compared to today’s Li-ion batteries. As a cathode support material, reduced graphene oxide has received increasing attention in the Li–O2 battery community due to the possibility of increased discharge capacity, increased battery cyclability, and decreased charging overpotential. In this article we investigate the effect of water on a thermally reduced graphene oxide cathode in a Li–O2 battery. Differential electrochemical mass spectroscopy reveals a decreased electron count for batteries with 1000 ppm water added to the electrolyte in comparison to dry batteries, indicating additional parasitic electrochemical or chemical processes. A comparable capacity of the wet and dry batteries indicates that the reaction mechanism in the Li–O2 battery also depends on the surface of the cathode and not only on addition of water to the electrolyte as demonstrated by the solution-based mechanism. In situ s...

Improved gas diffusion within microchanneled cathode supports of SOECs for steam electrolysis

Gas diffusion limitation within Ni/YSZ cathode supports of solid oxide electrolysis cells (SOECs) during steam electrolysis has been reported in previous studies. In this study, a microchanneled cathode support has been prepared by a mesh-templating phase-inversion process to improve the gas diffusion. Numerous channels with one end open on the cathode surface cross the support and are stopped on the other side of the support by a porous layer which acts as a cathode functional layer. The integrated structure is ideal for achieving both fast gas diffusion and a long three-phase-boundary for performing the cathode reactions. Compared with conventional cathode supports, the microchanneled cathode support produced higher current densities at low steam concentrations of feed gas during steam electrolysis, which is attributed to the fast gas diffusion achieved within the channels. Therefore, the microchannel structure of cathode supports can increase hydrogen yield and steam utilization efficiency.

Surface Modification of Solid Oxide Fuel Cell Cathodes Using Atomic Layer Deposition

The operating temperature of solid oxide fuel cells (SOFCs) is heading towards lower operating temperature region (< 650 °C) to achieve shorter start-up time, economical use of interconnect materials and avoiding undesirable reaction at the interface. However, at low operating temperature, sluggish oxygen reduction reaction (ORR) at the cathode surface impedes the overall kinetics of electrochemical processes of SOFC, which hinders the practical usage of SOFC in low temperature region. To improve the ORR kinetics, surface modification of the SOFC cathode has been suggested. Surface modification is conducted by distributing catalyst materials on the cathode support. Atomic layer deposition (ALD) is an excellent method for surface modification thanks to its step coverage, precise thickness control and low deposition temperature (< 250 °C) properties. In this study, we modified the surface of La0.6Sr0.4CoO3 (LSC) using ALD CoOx and studied the electrochemical performance of the SOFC cell with the surface modified cathode. As a result, the polarization resistance related to ORR at the cathode was increased after surface modification with CoOx, causing decreased power density. The details of the result will be presented in the conference in addition to the comparison to other surface modification experiment with ALD LSC treatment on La0.6Sr0.4Co0.2Fe0.8O3 cathode.

Fabrication and Characterization of LSM/YSZ/GDC Tri-Composite Cathode-Supported Tubular Solid Oxide Direct Carbon Fuel Cell

The purpose of this study was to fabricate a porous and high mechanical strength cathode support for solid oxide direct carbon fuel cells. Therefore, the effect of Gd0.1Ce0.9O2-δ (GDC) addition on the phase stability, sintering behavior, thermal expansion, porosity, electrical conductivity, and mechanical strength of La0.65Sr0.3MnO3-δ/(Y2O3)0.08(ZrO2)0.92 (LSM/YSZ) composite was evaluated. The sintering temperature and the porosity of LSM/YSZ composite were observed to increase with an increase in the amount of GDC, on the contrary, the electrical conductivity and the mechanical strength was decreased. An LSM/YSZ/GDC tri-composite with optimized properties was selected to fabricate the tubular cathode-supported SOFCs (LSM/YSZ/GDC|YSZ|NiO/YSZ) through extrusion and co-firing. A special chamber was designed for the DCFC operation of the tubular cell. Electrochemical characterization was done by measuring the polarization curves and electrochemical impedance spectroscopy using dry hydrogen or the syngas produced by in situ steam gasification of carbon black.

Mechanical and Durable Properties of Ni-YSZ Electrode Under High Temperature for Solid Oxide Electrolysis Stack

Many researches based on SOFC development and high temperature electrolysis (HTE) have been reported in the last couple of decades. HTE is one of the most clean and efficient technologies for manufacturing large amounts of hydrogen from water with oxygen. The processing and structure of HTE is closely related to the knowledge and concept of solid oxide fuel cells (SOFCs). Specially, it is very important to evaluate the durability’s properties of oxide electrolysis stacks under high temperature as well as steam environment to apply HTE. Unfortunately, no study has been reported the durable properties of oxide electrolysis stacks at high temperature as well as steam environment. For the reason, the aim of this work is to realize the durable properties (ex, high temperature strength fatigue and creep) at high temperature of 600°C~850°C for oxide electrolysis stacks which consists of 55%NiO-45%YSZ(8mol%Y2O3) composition. NiO-YSZ cathode supports were prepared in the shape of flat tubes by extrusion method. The pre-sintered NiO-YSZ flat tubes were dip-coated in YSZ slurry to secure the interconnector area with a masking fluid and then were sintered at 1400°C for 3h. The creep properties showed decreasing tendency with increasing applied load in range of 40~80MPa and temperature in range of 600°C~800°C. The life time of fatigue at 850°C under Ar-4%H2O environment was decreased with increasing applied load.

Fabrication and Characterization of Strontium-Doped Lanthanum Manganite Cathode Supports for Micro-Tubular Solid Oxide Fuel Cells

Strontium-doped lanthanum manganite (LSM) is a preferred cathode material for solid oxide fuel cells (SOFCs) owing to its good electrocatalytic properties for oxygen reduction reaction, high electronic conductivity, and thermal/chemical stability in oxidizing environments. However, for fabricating cathode-supported SOFCs, co-sintering of the electrolyte layer with the LSM support is a challenging step. Although LSM is compatible with the most common zirconia-based electrolytes at SOFC operating temperatures, it reacts with zirconia at higher temperatures to form electrically insulating secondary phases, namely lanthanum zirconate and strontium zirconate. Thus, to avoid the reaction between LSM and zirconia, the co-sintering temperature must be below 1250 °C, which is relatively low for obtaining a dense electrolyte layer. Additionally, it is important to maintain a good porosity of the LSM support to minimize gas diffusion losses through it. In the present work, we attempted to optimize the fabrication process of micro-tubular LSM supports by controlling several parameters such as the slurry composition, pre-sintering temperature, and sintering/co-sintering profiles. The mechanical and electrical properties of the fabricated LSM supports were characterized. Our results are expected to be helpful for achieving high-performance cathode-supported micro-tubular SOFCs with conventional materials.

Tuning Polysulfide Adsorption in Li-S Positive Electrodes with Metal Organic Frameworks.

A central problem limiting the performance of Lithium-Sulfur (Li-S) batteries is the soluble nature of polysulfide intermediates. To minimize the dissolution of polysulfides (PS) various cathode materials have been proposed. It has been argued that desirable cathodes have high surface areas and strongly adsorb polysulfides. Both of these properties are exhibited by Metal Organic Frameworks (MOFs), which are widely recognized for their ability to capture molecular species such as CO2 or methane. Although many MOFs are known, the compound known as MOF-74 is an especially attractive cathode support due to its regular porosity, high surface area (~1000m2/g), and high density of coordinately unsaturated metal sites (CUSs) which serve as binding sites for adsorbates. Here, we use first-principles computation to identify metal-substituted compositions of MOF-74, “M-MOF-74,” that maximize PS adsorption. Adsorption energies were evaluated for S8 rings, Li2S4, and Li2S across 16 metal substituted variants of M-MOF-74 (M=Be, Mg, Ca, Sr, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Sn). The most promising candidates for use as Li-S cathodes are identified, and the factors that control adsorption are discussed.

Electrocatalytic dechlorination of chloropicolinic acid mixtures by using palladium-modified metal cathodes in aqueous solutions

In China, chloropicolinic acid (ClPA) mixtures comprising 3,5,6-trichloropicolinic acid, 3,6-dichloropicolinic acid (3,6-D), 3-ClPA, and 6-ClPA are discharged as organic wastes at a rate of approximately 300 tons per year. In this work, we developed an aqueous phase electrocatalytic hydrogenation (ECH) system based on Pd catalyst to dechlorinate the ClPA mixtures into picolinic acid (PA) at room temperature. Firstly, we evaluated the influence of cathode support and Pd loading on the catalytic performance of cathodes, as well as the effects of operating parameters on the intermediate product selectivity and dechlorination efficiency of the ECH process with 3,6-D as the target compound. Secondly, we analyzed the ECH dechlorination mechanism of 3,6-D with regard to the surface condition of cathode and catholyte pH, and the rate-limiting step of the dechlorination process was also discussed. Finally, we assessed the practicability of the ECH system to dechlorinate the ClPA mixtures into PA by using a plate-and-frame cell. Results demonstrated that Pd/Ni foam cathodes with Pd loading of 2.25–3.6mgcm−2 exhibited the optimum ECH dechlorination performance, and the basic aqueous solution and high 3,6-D concentration favored the ECH process. The ClPA mixtures with 47gL−1 concentration (the total concentration of ClPAs was approximately 250mM) can be selectively dechlorinated into PA with 99% yield, 76.3% current efficiency, and 2.47kWhkg−1 PA specific electric energy consumption at a current density of 208Am−2 in a 1.25M NaOH aqueous solution.