Hebbian Research Articles

Development of an Adaptive Artifact Subspace Reconstruction Based on Hebbian/Anti-Hebbian Learning Networks for Enhancing BCI Performance.

Brain-computer interface (BCI) actively translates the brain signals into executable actions by establishing direct communication between the human brain and external devices. Recording brain activity through electroencephalography (EEG) is generally contaminated with both physiological and nonphysiological artifacts, which significantly hinders the BCI performance. Artifact subspace reconstruction (ASR) is a well-known statistical technique that automatically removes artifact components by determining the rejection threshold based on the initial reference EEG segment in multichannel EEG recordings. In real-world applications, the fixed threshold may limit the efficacy of the artifact correction, especially when the quality of the reference data is poor. This study proposes an adaptive online ASR technique by integrating the Hebbian/anti-Hebbian neural networks into the ASR algorithm, namely, principle subspace projection ASR (PSP-ASR) and principal subspace whitening ASR (PSW-ASR) that segmentwise self-organize the artifact subspace by updating the synaptic weights according to the Hebbian and anti-Hebbian learning rules. The effectiveness of the proposed algorithm is compared to the conventional ASR approaches on benchmark EEG dataset and three BCI frameworks, including steady-state visual evoked potential (SSVEP), rapid serial visual presentation (RSVP), and motor imagery (MI) by evaluating the root-mean-square error (RMSE), the signal-to-noise ratio (SNR), the Pearson correlation, and classification accuracy. The results demonstrated that the PSW-ASR algorithm effectively removed the EEG artifacts and retained the activity-specific brain signals compared to the PSP-ASR, standard ASR (Init-ASR), and moving-window ASR (MW-ASR) methods, thereby enhancing the SSVEP, RSVP, and MI BCI performances. Finally, our empirical results from the PSW-ASR algorithm suggested the choice of an aggressive cutoff range of c = 1-10 for activity-specific BCI applications and a moderate range of for the benchmark dataset and general BCI applications.

Current technology and industrialization status of cell-cultivated meat.

Interest and investment in cultivated meat are increasing because of the realization that it can effectively supply sufficient food resources and reduce the use of livestock. Nevertheless, accurate information on the specific technologies used for cultivated meat production and the characteristics of cultivated meat is lacking. Authorization for the use of cultivated meat is already underway in the United States, Singapore, and Israel, and other major countries are also expected to approve cultivated meat as food once the details of the intricate process of producing cultivated meat, which encompasses stages such as cell proliferation, differentiation, maturation, and assembly, is thoroughly established. The development and standardization of mass production processes and safety evaluations must precede the industrialization and use of cultivated meat as food. However, the technology for the industrialization of cultivated meat is still in its nascent stage, and the mass production process has not yet been established. The mass production process of cultivated meat may not be easy to disclose because it is related to the interests of several companies or research teams. However, the overall research flow shows that equipment development for mass production and cell acquisition, proliferation, and differentiation, as well as for three-dimensional production supports and bioreactors have not yet been completed. Therefore, additional research on the mass production process and safety of cultivated meat is essential. The consumer's trust in the cultivated meat products and production technologies recently disclosed by some companies should also be analyzed and considered for guiding future developments in this industry. Furthermore, close monitoring by academia and the government will be necessary to identify fraud in the cultivated meat industry.

High-Throughput Assembly of Compositionally Controlled 3D Cell Communities for Developmental Engineering.

Cell patterning for 3D culture has increased our understanding of how cells interact among themselves and with their environment during tissue morphogenesis. Building cell communities from the bottom up with size and compositional control is invaluable for studies of morphological transitions. Here, we detail Photolithographic DNA-programmed Assembly of Cells (pDPAC). pDPAC uses a photoactive polyacrylamide gel substrate to capture single-stranded DNA on a 2D surface in large-scale, highly resolved patterns using the photomask technology. Cells are then functionalized with a complementary DNA strand, enabling cells to be temporarily adhered to distinct locations only where their complementary strand is patterned. These temporary 2D patterns can be transferred to extracellular matrix hydrogels for 3D culture of cells in biomimetic microenvironments. Use of a polyacrylamide substrate has advantages, including a simpler photolithography workflow, lower non-specific cell adhesion, and lower stiction to ECM hydrogels during release of patterned hydrogels. The protocol is equally applicable to large (cm)-scale patterns and repetitive arrays of smaller-scale cell interaction or migration experiments.

Risk Assessment for Complex Systems Based on Fuzzy Cognitive Maps: A Case of the Biopharmaceutical Industry

Analyzing the supply chain (SC) of biopharmaceutical drugs can be challenging due to their complexity, the existence of a wide variety of risks, and the dynamics of the system. This paper presents a framework for evaluating the SC risks of Iranian biopharmaceutical companies based on cause‐and‐effect relationships and fuzzy cognitive maps (FCMs). We first interviewed several biopharmaceutical supply experts to learn about potential SC risks, causal relationships among FCM concepts, FCM structure, and FCM activation cycle. The most critical and relevant risks and significant elements of the SCs, such as cost, time, and quality, were identified as relevant FCM concepts. Then, we used failure mode and effects analysis (FMEA) and the FCM of the SC risks to assess the impacts of the biopharmaceutical SC risks on each other and on the crucial elements of the SCs. The Hebbian learning algorithms were then applied to train the FCM models. We tested different scenarios to evaluate the impacts of FCM concepts on the SC risks. The proposed approach can prioritize risk factors and, more importantly, predict and analyze the effect of each risk factor/risk group on other risks or the outcome of a given risk. The proposed FCM features and the knowledge gained from evaluating them can provide practical and helpful information to pharmaceutical companies to deal with their supply risks more efficiently.

Innovative Photovoltaic Cooling System

With the ever-increasing adoption of solar energy and the lack of space for PV installations, targeting maximum photovoltaic operational efficiencies has become essential. One of the key challenges faced by PV installations in warm climates is thermal management, which is caused by increasing temperatures due to PV conversion inefficiencies and limited ventilation possibilities in certain installations. Despite prior art, further improvement is still needed to provide a novel system that can offer more efficient and controllable temperature decrease of photovoltaic modules in both land and offshore installations. The present invention, termed IPCoSy, satisfies the aforementioned needs in the art by providing a novel system for cooling a solar panel assembly, including at least one photovoltaic module having a plurality of solar cells generating electrical power and a PV junction box attached to the back of the photovoltaic module. A part of this invention discloses a new type of PV module that is a modification of standard commercial modules. This new PV module incorporates a water chamber at the back of a solar cell assembly to regulate operational temperatures. Another part of this invention presents an after-market cooling system that can be fitted to existing standard PV modules to add the cooling effect. This part of the invention presents solid and flexible water tanks that can be fitted directly into a gap at the back of standard PV modules. Moreover, this invention presents details on parts that distinguish this cooling system from prior art, such as an internal stream spreader to obtain better fluid dynamics and external fittings that allow the PV module to be installed at any tilt angle without jeopardising the cooling effect. Finally, this invention discloses different application areas of this cooling system, such as residential and industrial water heating, reverse osmosis plants and offshore photovoltaic installations, showcasing the product's versatility, adaptability and large market suitability.

Complex Endosymbioses I: From Primary to Complex Plastids, Serial Endosymbiotic Events.

A considerable part of the diversity of eukaryotic phototrophs consists of algae with plastids that evolved from endosymbioses between two eukaryotes. These complex plastids are characterized by a high number of envelope membranes (more than two) and some of them contain a residual nucleus of the endosymbiotic alga called a nucleomorph. Complex plastid-bearing algae are thus chimeric cell assemblies, eukaryotic symbionts living in a eukaryotic host. In contrast, the primary plastids of the Archaeplastida (plants, green algae, red algae, and glaucophytes) possibly evolved from a single endosymbiosis with a cyanobacterium and are surrounded by two membranes. Complex plastids have been acquired several times by unrelated groups of eukaryotic heterotrophic hosts, suggesting that complex plastids are somewhat easier to obtain than primary plastids. Evidence suggests that complex plastids arose twice independently in the green lineage (euglenophytes and chlorarachniophytes) through secondary endosymbiosis, and four times in the red lineage, first through secondary endosymbiosis in cryptophytes, then by higher-order events in stramenopiles, alveolates, and haptophytes. Engulfment of primary and complex plastid-containing algae by eukaryotic hosts (secondary, tertiary, and higher-order endosymbioses) is also responsible for numerous plastid replacements in dinoflagellates. Plastid endosymbiosis is accompanied by massive gene transfer from the endosymbiont to the host nucleus and cell adaptation of both endosymbiotic partners, which is related to the trophic switch to phototrophy and loss of autonomy of the endosymbiont. Such a process is essential for the metabolic integration and division control of the endosymbiont in the host. Although photosynthesis is the main advantage of acquiring plastids, loss of photosynthesis often occurs in algae with complex plastids. This chapter summarizes the essential knowledge of the acquisition, evolution, and function of complex plastids.

A Cu hollow fiber with coaxially grown Bi nanosheet arrays as an integrated gas-penetrable electrode enables high current density and durable formate electrosynthesis.

While high current density formate (HCOO-) electrosynthesis from CO2 reduction has been achieved in a flow cell assembly, the inevitable flooding and salt precipitation of traditional gas-diffusion electrodes (GDEs) severely limit the overall energy efficiency and stability. In this work, an integrated gas-penetrable electrode (GPE) for HCOO- electrosynthesis was developed by coaxially growing vertically aligned high density Bi nanosheet arrays on a porous Cu hollow fiber (Bi NSAs@Cu HF) via controllable galvanic replacement. The interior porous Cu HF serves as a robust gas-penetrable and conductive host for continuously delivering CO2 gas to surface-anchored Bi NSAs, resulting in numerous well-balanced triphase active interfaces for the electrocatalytic CO2 reduction reaction (CO2RR). The most active Bi NSAs@Cu HF GPE exhibits a high HCOO- faradaic efficiency (FEHCOO-) of over 80% in a wide potential window (330 mV) with a linearly increased partial current density (jHCOO-) up to -261.6 mA cm-2 at -1.11 V vs. the reversible hydrogen electrode (RHE). The Bi NSAs@Cu HF GPE also sustains a FEHCOO- of >80% at a high total current density of -300 mA cm-2, corresponding to a jHCOO- of >-240 mA cm-2, for more than 60 h. This work provides new perspectives on designing efficient and durable integrated GPEs for a sustainable CO2RR on a large scale.

A study on the optimized area ratio of unit cell assembly for the broadband perfect sound absorption of acoustic metasurface

A study on the optimized area ratio of unit cell assembly for the broadband perfect sound absorption of acoustic metasurface

Controlled Sequential Assembly of DNA Nanoparticles Inside Cells Enabling Mitochondrial Interference

AbstractDeveloping artificial material systems to rationally interfere with organelles is emerging as a promising route to regulate the behaviors and fate of cells, thus providing new therapeutic strategies. Herein, a DNA nanoparticles (DNPs)‐based material system is reported, which achieves controlled sequential assembly inside cells, and realizes specific interference toward mitochondria. Two types of DNPs are synthesized via radical polymerization, followed with cascade hybridization chain reaction of hairpin DNA with Cyanine5 (Cy5) for mitochondrial targeting, and with complementary sequences for base pairing, respectively. DNPs with Cy5 (Cy5‐DNPs) first entered cells to target mitochondria, and the other DNPs with complementary sequences entered cells after an interval to sequentially assemble with Cy5‐DNPs into aggregates via base pairing. Mitochondrial interference is achieved, including increased reactive oxygen species, decreased membrane potential, abnormal elevation of Ca2+ level, decreased adenosine triphosphate, and attenuated cellular migration rate. In particular, by regulating the intervals of two types of DNPs entering cells, the mitochondrial interference degree is controllably modulated. This work achieves regulated organelles interference via the precise controlled self‐assembly of DNA nanostructures inside cells, which is envisioned to have great potential in precision biomedicine.

What Current Theories of Consciousness are Missing

Notwithstanding the power of the cell assembly concept, which holds that specific patterns of neuronal activity constitute the substrate of perceptual awareness that rises into consciousness, a explanatory gap remains between the phenomenological experience of consciousness and the brain processes from which that experience arises. A number of compelling and insightful theories have been offered that attempt to bridge that gap, but most of them fall short by failing to [a] specify which of many options other than hard-wired cell assemblies carry the information that becomes conscious, or [b] identify the brain mechanism for monitoring the functional events that become conscious. This Viewpoint article points to a number of possibilities that could be considered for both the substrate and monitor that give rise to consciousness.

Manipulating the Nanophase Separation of a Polymer-Salt Microfluid Generates an Advanced In Situ Separator for Component-Integrated Energy Storage Devices.

A polymer separator plays a pivotal role in battery safety, overall electrochemical performance, and cell assembly process. Traditional separators are separately produced from the electrodes and dominated by porous polyolefin thin films. In spite of their commercial success, today's separators are facing growing challenges with the increasing demand on the device safety and performance. As an attempt to address this urgent need, here, we propose a concept of in situ separator technology by manipulating the two-dimensional (2D) microfluid nanophase separation (2D-MFPS) of a poly(vinylidene difluoride)/lithium salt solution during drying. Particularly, nanophase separation is effectively regulated by low humidity, salt type, and compositions. For application studies, this 2D-MFPS is directly performed onto commercial electrodes under drying conditions with low humidity to fabricate a high-performance in situ separator with thickness and porous structures comparable to those of commercial Celgard separators. This in situ separator shows superior performance in high-temperature stability and wetting capability to a variety of liquid electrolytes. Finally, pouch cells with this in situ separator technology are successfully assembled with an extremely simplified separator-stacking-free process and demonstrate stable cycle performance due to the well-controlled porous structures and electrode-separator interface.

Insights into the Cell Division of Neospora caninum.

Neospora caninum is an apicomplexan protozoan parasite responsible for causing neosporosis in a range of animal species. It results in substantial economic losses in the livestock industry and poses significant health risks to companion and wild animals. Central to its survival and pathogenicity is the process of cell division, which remains poorly understood in this parasite. In this study, we explored the cell division of Neospora caninum using a combination of modern and classic imaging tools, emphasizing its pivotal role in perpetuating the parasite's life cycle and contributing to its ability to persist within host organisms. We described the intricacies of endodyogeny in Neospora caninum, detailing the dynamics of the cell assembly and the nuclear division by ultrastructure expansion microscopy and regular confocal microscopy. Furthermore, we explored the centrosome dynamics, the centrioles and the apicoplast through the advancement of the cell cycle. Our analysis described with unprecedented detail, the endodyogeny in this parasite. By advancing our understanding of these molecular mechanisms, we aimed to inspire innovative strategies for disease management and control, with the ultimate goal of mitigating the devastating impact of neosporosis on animal health and welfare.

Understanding the Role of Electrode Thickness on Redox Flow Cell Performance**

AbstractThe electrode thickness is a critical design parameter to engineer high performance redox flow cells by impacting the available surface area for reactions, current and potential distributions, and required pumping power. To date, redox flow cell assemblies employ repurposed off‐the‐shelf fibrous electrodes which feature a broad range of thicknesses. However, comprehensive guidelines to select the optimal electrode thickness for a given reactor architecture remain elusive. Here, we investigate the effect of the electrode thickness in the range of 200–1100 μm on the cell performance by stacking electrode layers in four different flow cell configurations – Freudenberg paper and ELAT cloth electrodes combined with flow‐through and interdigitated flow fields. We employ a suite of polarization, electrochemical impedance spectroscopy and pressure drop measurements together with pore network modeling simulations to correlate the electrode thickness for various reactor designs to the electrochemical and hydraulic performance. We find that thicker electrodes (420 μm paper electrodes and 812 μm cloth electrodes) are beneficial in combination with flow‐through flow fields, whereas when using interdigitated flow fields, thinner electrodes (210 μm paper electrodes and 406 μm cloth electrodes) result in a better current density and pressure drop trade‐off. We hope our findings will aid researchers and technology practitioners in designing their electrochemical flow cells under convective operation.

Redox-active electrolytes as a viable approach for the one-step assembly of metal-ion capacitors

The assembly of metal-ion capacitors is a very challenging task; the use of traditional metallic electrodes or sacrificial materials induces technical problems during cell assembly or affects its normal operation. Here, we report an efficient, one-step method for assembling metal-ion capacitors using redox-active electrolytes with thiocyanate-based salts. The addition of a redox-active salt compensates for the charge on the positive electrode while enabling the insertion of metal ions into the structure of the negative electrode. The proposed approach reduces assembly time and cost and results in increased specific energy compared to that from the traditional two-step assembled hybrid systems. Furthermore, we demonstrate that the proposed approach can be successfully implemented for sodium-ion and potassium-ion hybrid capacitors. Our results are supported by operando techniques and can potentially facilitate further research on metal-ion capacitors and applications of these devices.

Automated Electrolyte Formulation and Coin Cell Assembly for High-Throughput Lithium-Ion Battery Research

Battery research involving performance evaluation by battery cycling is a time-consuming process with sometimes large cell-to-cell variations. To enhance the rate of testing and reproducibility, automation is one accelerator that can be used. In this study, we introduce ODACell1 (Figure 1), an automated system for high-throughput electrolyte screening and Li-ion cell assembly.ODACell enables the assembly of Li-ion battery cells in ambient atmosphere. We use LiFePO4||Li4Ti5O12-based full cells with a dimethyl sulfoxide-based model electrolyte for demonstrating the automated system. We investigate the reproducibility of the automated system on this system as well as the influence of water on the performance of the model electrolyte when exposed to ambient air. Our system is uniquely equipped for combinatorial experimentation, combining electrolyte formulation, batch coin cell assembly, and cycling into a single system. The integration of multiple setups into a single unit is made possible, overcoming the incompatibility issues with integrating multiple, different automated systems together.While there are several other robotic systems besides ODACell for battery material acceleration, ODACell’s unique combination of robots incorporated in the robotic setup allow a broader set of tasks to be automated. For example, Clio by Dave et al. 2 focus on electrolyte formulation and characterization, lacking assembly of battery cells; AutoBASS by Zhang et al. 3 only automates battery assembly; and Poseidon by Svensson et al. 4 can automate electrolyte formulation, characterization, and coin cell assembly, but lack high-throughput batch processing.ODACell ensures high reproducibility, which is needed to establish robust models and determine accurate electrochemical and physical properties. The system assembled 131 coin cells, with a conservative fail rate of only 5%. The relative standard deviation of the discharge capacity after 10 cycles was 2% for the studied system. The investigation into the influence of water on cycling performance show overlapping performance trends between coin cells with 2 vol% and 4 vol% of water in the electrolyte highlighting the nontrivial relationship between water and cycling performance.In conclusion, ODACell is a promising tool for high-throughput electrolyte screening and Li-ion cell assembly. It builds upon previously published robotic setups by automating more of the research workflow. Our study highlights the importance of reproducibility in battery research and the complex relationship between water contaminants in electrolytes and cycling performance. ODACell has the potential to be a useful tool for advancing battery research by enhancing the rate of testing and reducing the variation of results.

(Invited) In Situ Characterization during Electrode Processing: The Role of Hidden Parameters

Micron and nano-sized functional materials play a key role for future technologies that are currently developed in the field of energy conversion (electrolysers, fuel cells) and electrocatalysis (N2 fixation, CO2 reduction reaction). While new materials with outstanding properties are continuously developed, they rarely find their way into – urgently needed – large scale production and industrial applications.1 One reason for this are hidden parameters that occur during ink formulation, coating (and decal transfer), cell assembly, and operation. We propose the development of coherent workflows that help us to identify reliable correlations. These should be developed for each electrocatalyst, bridging synthesis, electrode and gas diffusion electrode (GDE) / membrane electrode assembly (MEA) fabrication, and testing. All information, including “negative” results like crack formation, delamination, structural ageing and dissolution, must be reported until the relevant hidden parameters are deciphered, and the design chain is understood. Then, materials and electrodes derived from complementary processes and exhibiting subtle variations in composition and structure, can be evaluated against each other.However, this implies to fill the “blackbox” between technical catalysts and electrochemical testing in flow cells, GDEs or MEAs, with quantitative data on powders, ink formulations and coating properties. In the past years, we developed a toolbox of methods that starts from key control characteristics for technical catalysts, i.e., Pt/C for polymer electrolyte membrane fuel cells, that thereon enable the in situ analysis of ink formulations and pastes during the dispersion process and at application concentration.2,3 This is followed by the assessment of the resulting coatings from large-area crack analysis down to the level of surface roughness and pore size characteristics.4 Finally, this input is connected with performance and stability testing results to enable the comparison of different materials, the assessment of structure property relations, and ultimately to establish inline process control during electrode manufacturing. In this contribution, the developed methods will be summarized and related to their current limitations and prospects, in particular for unraveling hidden parameters during electrode fabrication and MEA assembly as well as in line process control. Literature [1] Siegmund, Daniel; Metz, Sebastian; Peinecke, Volker; Warner, Terence E.; Cremers, Carsten; Grevé, Anna; Smolinka, Tom; Segets, Doris; Apfel, Ulf-Peter; Crossing the Valley of Death : From Fundamental to Applied Research in Electrolysis, JACS Au 1 (2021), 527 – 535.[2] Bapat, Shalmali; Segets, Doris; Sedimentation Dynamics of Colloidal Formulations through Direct Visualization : Implications for Fuel Cell Catalyst Inks, ACS Applied Nano Materials 3 (2020), 7384 – 739.[3] Bapat, Shalmali; Giehl, Christopher; Kohsakowski, Sebastian; Peinecke, Volker; Schäffler, Michael; Segets, Doris; On the state and stability of fuel cell catalyst inks, Advanced Powder Technology 32 (2021), 3845 – 3859.[4] Jaster, Theresa; Albers, Simon; Leonhard, Armin; Kräenbring, Mena-Alexander; Lohmann, Heiko; Zeidler-Fandrich, Barbara; Özcan, Fatih; Segets, Doris; Apfel, Ulf-Peter; Enhancement of CO₂RR product formation on Cu-ZnO-based electrodes by varying ink formulation and post-treatment methods, JPhys Energy 5 (2023), 024001.

A Data-Driven Quality Control Method for Li-Ion Cells

The urgency to develop innovative electrochemical energy storage systems has increased exponentially as many governments across the world adopt net-zero strategies that rely heavily on transport electrification. This means that ensuring the repeatability and reproducibility of electrochemical data produced in battery research is one of the most important issues in the race to a carbon neutral economy. Li-ion batteries, the most mature and competitive battery technology currently available, has had some of its most significant advances in the discovery of new electrode materials, hence there is large research interest in this.Academic institutions have particular strengths and long experience in materials discovery, however, deployment of these materials in commercial devices lags behind for various reasons. One problem is the lack of quantitative parameters for quality control in electrochemical measurement as well as the difficulty of precisely evaluating cells prior to cycling. Cell assembly is a complex process with several steps, all of which could contribute to a faulty cell. Lack of reproducibility, especially when comparing from laboratory to laboratory, often ensue as a result. To optimize space and resource utilization many researchers do their testing in coin cells; the proliferation of best practice guides for coin-cell fabrication and measurement highlights the advantages of this cell format.(1-4) However, a simple quantitative method of quality control is still lacking.Figure 1: Graphical identification of outlier cells prone to poor cycling. OCV of pristine coin cells, NMC 811 half-cells. Outlier cells (black trace, bottom, red trace top) can be easily identified prior to cycling.In this presentation we demonstrate a proof-of-concept development of a quality control process based on the time evolution of the open circuit potential (OCV) of pristine Li-ion coin cells, and how that can be used to discard faulty cells before cycling. A pass/fail criterion is developed based on the OCV transients by fitting the behaviour of more than 20 different cells to a sigmoidal function, the goodness of fit is then compared. We found that cells that fall below a certain R2 value have shorter cycle life under the same cycling conditions. The threshold values showed a dependence on cell chemistry. Additionally, the graphical representation of the transients allows for identifying outliers that had significantly worse electrochemical performance (figure 1), therefore the goodness of fit can be used to quantitatively gauge the quality of the cells prior to cycling.The establishment of a quantitative pass/fail criterion makes the quality control process amenable to automation. To demonstrate this, we developed a Python program that takes experimental OCV transients as inputs to automate the data analysis. The program can process information from virtually hundreds of data files in a short period of time, easily identifying outlier cells. A spreadsheet file with the raw and transformed data, as well as with the generated plots is created for each transient OCV, allowing users to explore the data manually, if necessary.In summary, we have used data from a large number of coin cells to empirically fit a quantitative quality control parameter, establish a pass/fail criterion based on OCV transients, and develop code to greatly save time and resources and establish a statistical analysis of the effectiveness of the assembly process. This innovative data-driven approach showed great promise to improve repeatability and reproducibility in measuring the performance of new materials and cell-chemistries in a systematic and quantitative way.

The Through-Flow Electrochemical Cell - a Breakthrough Technology

The paper describes a new approach to energy-storage electrochemical cells that is “chemistry-agnostic” and promises to solve several problems of existing batteries. These problems include: Charging rates are too slowIntrinsic failure-mechanisms compromise safetyEnergy Density is inadequate for mobile applicationsLifetime is too short for large-scale permanent installations The key idea of the “Through-Flow Cell” is that the electrolyte is pumped continuously in a closed loop through a porous anode, porous separator, and porous cathode, in a direction aiding the active ionic flow. Although the idea of moving a liquid electrolyte is not new, there have not been any successful commercial products until now. It should not be confused with the “Flow-Battery”, an entirely different concept where two different fluids flow separately within anode and cathode. Previous attempts to develop a reliable Through-Flow Cell foundered on the difficulty of immobilizing active materials on the anode and cathode collectors while fluid flows freely through surrounding pore-spaces. I describe a new active-material encapsulation method to achieve that crucial objective, and a new more convenient cell configuration.Applications will include large grid-scale installations and could include high-power transportation vehicles such as trains and buses. The basic cell is configured as a stack-able, de-mountable, and repairable module. It is a completely self-contained package incorporating an adaptive electrolyte pumping system with optional heating and/or cooling to optimize efficiency in a wide range of environmental conditions. In grid-scale systems the ability to easily remove a low-performing cell from a stack, repair, and replace it is a very desirable feature that extends the life of a high-CAPEX installation almost indefinitely.The new cell design has a conservative capacity rating of 3000 Amp.hr (using 300 mA.hr/gm active materials) and a continuous current rating of 2000 Amps, with the cell voltage being determined by the chemistry employed. For the Lithium-ion chemistry with a nominal voltage of 3.7v it has 10 KW.hr energy capacity @ 90% discharge. A linear stack of 100 cells makes a battery storing 1 MW.hr on a rack 9 meters in length; easily accommodated in an enclosure the size of a shipping container that could contain up to eight such racks.For some people the idea of a battery with moving parts runs counter to notions of simplicity found in the standard sealed cylindrical cells. In practice, however, large assemblies of such cells require complex external liquid cooling and possibly fire-suppression systems. When individual cells fail, they are usually disconnected by blowing fuses, resulting in a steady degradation that is not easily repairable.In contrast to sealed cells, some unique advantages of the electrolyte circulation technique can be summarized as follows: Effective Mobility of active-species ions is dramatically boosted by the flow velocity, translating into reduced series resistance between electrodes. Peak charging or discharging currents can be ten times higher without overheating or loss of charge capacity when the flow velocity is only one centimeter per second.Flow direction is reversed when switching from charging to discharging, which reverses dendrite growth that is a potential source of catastrophic failure.The interior temperature of the cell can be directly controlled and excess heat removed from the electrolyte by an external heat-exchanger, or added in cold climates.The Anode and Cathode, being 3-Dimensional porous structures, incorporate greatly increased volumes of active material compared to typical 2-Dimensional foil electrodes.Electrolyte flowing across the surface of active material inside porous electrodes efficiently sweeps away ion-deficient liquid from within the Slipping-Plane near the Solid-Electrolyte Interface (SEI), reducing the parasitic Zeta-Potential. Results from a proof-of-principle laboratory cell using the Nickel Metal-Hydride chemistry will be briefly described, and a full-scale commercial cell design presented in more detail. The very important active-material encapsulation technique is also described along with its unique ability to tolerate large changes in volume of the active material without degradation. Current cylindrical “jelly-roll” format cells cannot tolerate significant volume change caused by ion-intercalation inside active materials without physical destruction.The new technology may enable complete replacement of Graphite by Silicon in the Anodes of Lithium-ion cells. Silicon has a charge capacity almost four times greater than Graphite, but expands up to 400%. In another example, Cathodes in the Lithium-Sulfur chemistry may tolerate far higher Sulfur loading with corresponding increased energy density.In summary, this new focus on the mechanics of energy-storage cells shows promise for a step-change increase in power-density, reliability, and safety. As described, the idea can be applied to any new improvement in chemistry that uses a liquid electrolyte as soon as it achieves maturity. Figure 1

Unintended Cation Crossover in CO2 Conversion MEA Cells: Causes and Effects

Membrane electrode assemblies in gas diffusion cells enable CO2 reduction at industrially relevant rates, yet their long-term operational stability is often limited by the formation of solid precipitates (e.g. K2CO3) in the cathode pores. This is a consequence of a combination of 1) local alkalization due to the electrochemical reaction, 2) generation of (bi)carbonate by chemical reaction of CO2 with the alkaline electrolyte, and 3) the presence of alkali metal cations. In catholyte-free, zero-gap cells using anion exchange membranes, the presence of electrolyte cations at the cathode is the result of unintended crossover from the anolyte, and a detailed understanding of the factors enabling this crossover is lacking. Here we show that the anolyte concentration governs the flux of cation migration through the membrane, and this substantially influences the behaviors of copper catalysts in catholyte-free CO2 electrolysers. Systematic variation of the anolyte ionic strength (using aqueous KOH or KHCO3) correlated with drastic changes in the observed product selectivity – most notably, at low ionic strength, Cu catalysts produced predominantly CO, in contrast to the mixture of C2+ products typically observed on Cu. In this talk, we examine the factors influencing ion crossover and the resulting effects on catalyst structure and activity, under conditions of both CO2 and CO reduction. Operando X-ray absorption spectroscopy and quasi in situ X-ray photoelectron spectroscopy were used to study how the catalyst is affected by operation conditions. Our results show that even in catholyte-free cells, cation effects (including unintended ones) can significantly influence reaction pathways, and this must be considered in future development of catalysts and devices.El-Nagar, G. A., Haun, F., Gupta, S., Stojkovikj, S. & Mayer, M. T. Unintended cation crossover influences CO2 reduction activity in Cu-based zero-gap electrolysers. Nature Communications14, 2062 (2023) doi: doi.org/10.1038/s41467-023-37520-x Figure 1

Novel Designs for 7-Layer Membrane Electrode Assembly in PEM Fuel Cells: A Systematic Investigation of Mass Transport and Charge Transfer Processes in PEM Fuel Cells

During the last decades, the focus of PEM fuel cell development in automobile applications has been mostly dedicated to the optimization of the catalyst-coated membrane (CCM). Nevertheless, the optimum design of other components like the gas diffusion layer, or gas flow fields can directly influence the overall performance of the PEM fuel cell. The gas diffusion layer (GDL) itself plays a crucial role in the water balance in a PEM fuel cell. Besides, an optimized combination of GDLs and gas flow fields leads to the efficient distribution of reactants on catalyst layers. Our main goal for the development of the 7-layer membrane electrode assembly in PEM fuel cells is to reduce the corresponding thickness. This will both improve the efficiency of mass, electrical, and heat transport processes and reduce materials and energy consumption during production. Thus, it will contribute in two ways to support the commercialization of PEM fuel cells.Further intentions of our new GDL designs are, on one hand, optimizing the capillary pressure gradient for a smooth discharge of saturated water between the catalyst layer and gas flow fields. On the other hand, enhancing the gas transport to the catalysts layer by reducing diffusion length. These could be obtained by innovative engineering of microporous structures in GDLs. Thus, following beyond the previous investigation of our research group to enhance the capillary pressure gradient, and subsequently, mass transport, in this study the design of the microporous layer is purposely varied by applying different mono disperse polymer particles as pore former. In addition, to reduce the cell width in a disruptive manner, two innovative architectures have been investigated. The first one consists in eliminating the gas diffusion medium (GDM) and thus keeping only the newly-designed MPLs. Consequently, in comparison with a conventional GDL, the uncompressed material thickness is reduced from approximately 200 µm to around 40 µm. The second cell architecture is based on the integration of the refined gas flow fields directly at the back of the GDL which enables us to get rid of “large” rib/channel designs used in state-of-art bipolar plates.In this contribution, the effect of new-designed MPLs, as well as the mechanically machined GDL on both mass transport and the charge transfer processes have been evaluated and significant performance gains have been obtained. Additionally, the scale-up possibility from the single-cell design to short-stack PEM fuel cells will be discussed.This work from the “DOLPHIN” project has received funding from the Fuel Cells and Hydrogen 2 Joint Undertaking (now Clean Hydrogen Partnership) under Grant Agreement No 826204. This Joint Undertaking receives support from the European Union’s Horizon 2020 Research and Innovation program, Hydrogen Europe and Hydrogen Europe Research.