{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,14]],"date-time":"2026-10-14T04:48:23Z","timestamp":1791953303539,"version":"4.3.4"},"reference-count":127,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T00:00:00Z","timestamp":1790640000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100011033","name":"Agencia Estatal de Investigaci\u00f3n","doi-asserted-by":"publisher","award":["PID2024-157492OB-I00"],"award-info":[{"award-number":["PID2024-157492OB-I00"]}],"id":[{"id":"10.13039\/501100011033","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100011033","name":"Agencia Estatal de Investigaci\u00f3n","doi-asserted-by":"publisher","award":["PID2024-160428OB-I00"],"award-info":[{"award-number":["PID2024-160428OB-I00"]}],"id":[{"id":"10.13039\/501100011033","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100011033","name":"Agencia Estatal de Investigaci\u00f3n","doi-asserted-by":"publisher","award":["CPP2025-012434"],"award-info":[{"award-number":["CPP2025-012434"]}],"id":[{"id":"10.13039\/501100011033","id-type":"DOI","asserted-by":"publisher"}]},{"award":["PID2024-157492OB-I00"],"award-info":[{"award-number":["PID2024-157492OB-I00"]}],"id":[{"id":"https:\/\/ror.org\/003x0zc53","id-type":"ROR","asserted-by":"publisher"}]},{"award":["PID2024-160428OB-I00"],"award-info":[{"award-number":["PID2024-160428OB-I00"]}],"id":[{"id":"https:\/\/ror.org\/003x0zc53","id-type":"ROR","asserted-by":"publisher"}]},{"award":["CPP2025-012434"],"award-info":[{"award-number":["CPP2025-012434"]}],"id":[{"id":"https:\/\/ror.org\/003x0zc53","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>Portable air-breathing electrochemical devices, particularly polymer electrolyte membrane fuel cells (PEMFCs), offer simple, lightweight, and compact power generation by using atmospheric oxygen as the oxidant. Their performance, however, depends strongly on cathode plate geometry that governs reactant transport, thermal and water management, and mechanical integrity. Conventional manufacturing has historically restricted this architectural design space. This perspective examines how additive manufacturing (AM) enables three-dimensional geometries that can overcome these constraints. An open columnar cathode plate for air-breathing PEMFCs is used as a case study to show how manufacturing-enabled design can improve passive transport, increase the hydrogen conversion efficiency, and integrate multiple functions within a compact component. The same design philosophy can then be extended to metal\u2013air batteries, microbial fuel cells, direct methanol fuel cells, electrolyzers, CO2 electrochemical reactors, and electrochemical sensors. Finally, the remaining barriers and future opportunities associated with advanced materials, computational design, topology optimization, artificial intelligence, and digital manufacturing are discussed. Overall, AM is presented as a design-enabling platform for next-generation portable electrochemical devices.<\/jats:p>","DOI":"10.3390\/ma19194174","type":"journal-article","created":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T17:19:08Z","timestamp":1790702348000},"page":"4174","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Additive Manufacturing as a Design Enabler for Air-Breathing Electrochemical Devices: A PEM Fuel Cell Case Study"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3918-5415","authenticated-orcid":false,"given":"Pablo A.","family":"Garc\u00eda-Salaberri","sequence":"first","affiliation":[{"name":"Department of Chemical and Environmental Technology (ESCET), Universidad Rey Juan Carlos, C\/Tulip\u00e1n s\/n, 28933 M\u00f3stoles, Spain"},{"name":"Instituto de Investigaci\u00f3n de Tecnolog\u00edas para la Sostenibilidad, Universidad Rey Juan Carlos, C\/Tulip\u00e1n s\/n, 28933 M\u00f3stoles, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3740-3079","authenticated-orcid":false,"given":"Julia","family":"Ure\u00f1a","sequence":"additional","affiliation":[{"name":"Advanced Materials Department, Technology Centre of Metal-Mechanical and Transport (CETEMET), Avda. Primero de Mayo S\/N, 23700 Linares, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1589-6957","authenticated-orcid":false,"given":"Luis","family":"Duque","sequence":"additional","affiliation":[{"name":"Departamento de Energ\u00eda, Centre for Energy, Environment and Technology Research, Avda. Complutense 40, 28040 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Carlos","family":"Jarava-Barrera","sequence":"additional","affiliation":[{"name":"Departamento de Energ\u00eda, Centre for Energy, Environment and Technology Research, Avda. Complutense 40, 28040 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6822-4797","authenticated-orcid":false,"given":"Antonio M.","family":"Chaparro","sequence":"additional","affiliation":[{"name":"Departamento de Energ\u00eda, Centre for Energy, Environment and Technology Research, Avda. Complutense 40, 28040 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"463","DOI":"10.1039\/C8EE01157E","article-title":"The role of hydrogen and fuel cells in the global energy system","volume":"12","author":"Staffell","year":"2019","journal-title":"Energy Environ. Sci."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"126411","DOI":"10.1016\/j.energy.2022.126411","article-title":"A techno-economic comparative study of renewable energy systems based different storage devices","volume":"266","author":"Falama","year":"2023","journal-title":"Energy"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"485","DOI":"10.1016\/j.renene.2023.01.037","article-title":"Evaluating the sustainability of the hydrogen economy using multi-criteria decision-making analysis in Korea","volume":"204","author":"Hong","year":"2023","journal-title":"Renew. Energy"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"16509","DOI":"10.1016\/j.ijhydene.2016.02.057","article-title":"Advances in stationary and portable fuel cell applications","volume":"41","author":"Wilberforce","year":"2016","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Kundu, P.P., and Dutta, K. (2016). Hydrogen fuel cells for portable applications. Compendium of Hydrogen Energy, Woodhead Publishing.","DOI":"10.1016\/B978-1-78242-364-5.00006-3"},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Ferreira-Aparicio, P., Conde, J.J., and Chaparro, A.M. (2018). Fundamentals and components of portable hydrogen fuel-cell systems. Portable Hydrogen Energy Systems, Academic Press.","DOI":"10.1016\/B978-0-12-813128-2.00002-4"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"897","DOI":"10.1016\/j.rser.2015.07.157","article-title":"Approaches to polymer electrolyte membrane fuel cells (PEMFCs) and their cost","volume":"52","author":"Moreno","year":"2015","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"67","DOI":"10.1016\/j.jpowsour.2007.03.066","article-title":"Micro-fuel cells\u2014Current development and applications","volume":"170","author":"Kundu","year":"2007","journal-title":"J. Power Sources"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"7618","DOI":"10.1016\/j.ijhydene.2010.04.143","article-title":"Anodic behavior of zinc in Zn-MnO2 battery using ERDA technique","volume":"35","author":"Minakshi","year":"2010","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"116359","DOI":"10.1016\/j.apenergy.2020.116359","article-title":"Progress on open cathode proton exchange membrane fuel cell: Performance, designs, challenges and future directions","volume":"283","author":"Kurnia","year":"2021","journal-title":"Appl. Energy"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"529","DOI":"10.1016\/j.apenergy.2013.05.007","article-title":"Thermal modelling of the cathode in air-breathing PEM fuel cells","volume":"111","author":"Ismail","year":"2013","journal-title":"Appl. Energy"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"6242","DOI":"10.1016\/j.jpowsour.2011.04.020","article-title":"Critical importance of humidification of the anode in miniature air-breathing polymer electrolyte membrane fuel cells","volume":"196","author":"Hamel","year":"2011","journal-title":"J. Power Sources"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"118","DOI":"10.1016\/j.jpowsour.2007.01.073","article-title":"Engineering model of a passive planar air breathing fuel cell cathode","volume":"167","author":"Fabian","year":"2007","journal-title":"J. Power Sources"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"168","DOI":"10.1016\/j.jpowsour.2006.03.054","article-title":"The role of ambient conditions on the performance of a planar, air-breathing hydrogen PEM fuel cell","volume":"161","author":"Fabian","year":"2006","journal-title":"J. Power Sources"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"358","DOI":"10.1002\/fuce.200400034","article-title":"Modelling approach for planar self-breathing PEMFC and comparison with experimental results","volume":"4","author":"Schmitz","year":"2004","journal-title":"Fuel Cells"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"A1584","DOI":"10.1149\/1.2209567","article-title":"Species-Electrochemical Modeling of an Air-Breathing Cathode of a Planar Fuel Cell","volume":"153","author":"Hwang","year":"2006","journal-title":"J. Electrochem. Soc."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"58","DOI":"10.1016\/j.jpowsour.2006.06.093","article-title":"Effect of cathode separator structure on performance characteristics of free-breathing PEMFCs","volume":"162","author":"Tabe","year":"2006","journal-title":"J. Power Sources"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"367","DOI":"10.1016\/j.jpowsour.2007.02.091","article-title":"Concentration and ohmic losses in free-breathing PEMFC","volume":"173","author":"Matamoros","year":"2007","journal-title":"J. Power Sources"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"334","DOI":"10.1016\/j.jpowsour.2005.05.064","article-title":"Computational analysis of heat and mass transfer in a micro-structured PEMFC cathode","volume":"156","author":"Litster","year":"2006","journal-title":"J. Power Sources"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"721","DOI":"10.1016\/j.jpowsour.2006.11.056","article-title":"Three-dimensional heat and mass transfer analysis in an air-breathing proton exchange membrane fuel cell","volume":"164","author":"Wang","year":"2007","journal-title":"J. Power Sources"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"490","DOI":"10.1016\/j.apenergy.2014.08.113","article-title":"An efficient mathematical model for air-breathing PEM fuel cells","volume":"135","author":"Ismail","year":"2014","journal-title":"Appl. Energy"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"2077","DOI":"10.1108\/HFF-11-2018-0674","article-title":"Effects of hydrogen relative humidity on the performance of an air-breathing PEM fuel cell: A numerical study","volume":"30","author":"Chen","year":"2019","journal-title":"Int. J. Numer. Methods Heat Fluid Flow"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"168","DOI":"10.1016\/j.jpowsour.2008.03.076","article-title":"Dynamic modeling and simulation of air-breathing proton exchange membrane fuel cell","volume":"182","author":"Yalcinoz","year":"2008","journal-title":"J. Power Sources"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"17343","DOI":"10.1016\/j.ijhydene.2021.02.133","article-title":"A dynamic model of air-breathing polymer electrolyte fuel cell: A parametric study","volume":"46","author":"Calili","year":"2021","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"123827","DOI":"10.1016\/j.energy.2022.123827","article-title":"Air-breathing versus conventional polymer electrolyte fuel cells: A parametric numerical study","volume":"250","author":"Ismail","year":"2022","journal-title":"Energy"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1001","DOI":"10.1016\/j.renene.2022.06.092","article-title":"Dynamic models for air-breathing and conventional polymer electrolyte fuel cells: A comparative study","volume":"195","author":"Ismail","year":"2022","journal-title":"Renew. Energy"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"23463","DOI":"10.1016\/j.ijhydene.2020.10.258","article-title":"Performance evaluation of an air breathing PEM fuel cell in harsh environments\u2014A case study under Saudi Arabia\u2019s ambient condition","volume":"46","author":"Wilberforce","year":"2021","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"50","DOI":"10.1016\/j.apenergy.2012.02.003","article-title":"Effects of anisotropic permeability and electrical conductivity of gas diffusion layers on the performance of proton exchange membrane fuel cells","volume":"95","author":"Ismail","year":"2012","journal-title":"Appl. Energy"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"2334","DOI":"10.1149\/1.2085971","article-title":"Polymer Electrolyte Fuel Cell Model","volume":"138","author":"Springer","year":"1991","journal-title":"J. Electrochem. Soc."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"3849","DOI":"10.1016\/j.electacta.2006.11.002","article-title":"Mathematical Modelling of Ambient Air-Breathing Fuel Cells for Portable Devices","volume":"52","author":"Litster","year":"2007","journal-title":"Electrochim. Acta"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1254","DOI":"10.1149\/1.1836625","article-title":"Proton Conductivity of Nafion 117 as Measured by a Four-Electrode AC Impedance Method","volume":"143","author":"Sone","year":"1996","journal-title":"J. Electrochem. Soc."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"32","DOI":"10.1016\/S0378-7753(02)00542-6","article-title":"Review and analysis of PEM fuel cell design and manufacturing","volume":"114","author":"Mehta","year":"2003","journal-title":"J. Power Sources"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"113","DOI":"10.1016\/j.jpowsour.2004.12.048","article-title":"Adhesive copper films for an air-breathing polymer electrolyte fuel cell","volume":"144","author":"Jaouen","year":"2005","journal-title":"J. Power Sources"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"197","DOI":"10.1016\/j.jpowsour.2003.09.023","article-title":"Stability of planar PEMFC in printed circuit board technology","volume":"127","author":"Schmitz","year":"2004","journal-title":"J. Power Sources"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"459","DOI":"10.1016\/S0378-7753(03)00802-4","article-title":"Development of portable fuel cell arrays with printed-circuit technology","volume":"124","author":"Braithwaite","year":"2003","journal-title":"J. Power Sources"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"3997","DOI":"10.1016\/j.ijhydene.2013.06.082","article-title":"Influence of the gas diffusion cathode structure on the performance of an air-breathing proton exchange membrane fuel cell","volume":"39","author":"Chaparro","year":"2014","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"106351","DOI":"10.1016\/j.catcom.2021.106351","article-title":"Natural wood derived robust carbon sheets with perpendicular channels as gas diffusion layers in air-breathing PEMFCs","volume":"159","author":"Dang","year":"2021","journal-title":"Catal. Commun."},{"key":"ref_38","first-page":"694","article-title":"Sustainability of additive manufacturing: An overview on its energy demand and environmental impact","volume":"21","author":"Peng","year":"2018","journal-title":"Addit. Manuf."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"2767","DOI":"10.1149\/1.1837893","article-title":"Operating Proton Exchange Membrane Fuel Cells Without External Humidification of the Reactant Gases: Fundamental Aspects","volume":"144","author":"Srinivasan","year":"1997","journal-title":"J. Electrochem. Soc."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"60","DOI":"10.1016\/j.apenergy.2013.03.076","article-title":"A portable system powered with hydrogen and one single air-breathing PEM fuel cell","volume":"109","author":"Guelbenzu","year":"2013","journal-title":"Appl. Energy"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"11844","DOI":"10.1016\/j.ijhydene.2010.08.105","article-title":"The development of air-breathing proton exchange membrane fuel cell with a cylindrical configuration","volume":"35","author":"Lee","year":"2010","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"1065","DOI":"10.1007\/s12541-013-0143-6","article-title":"The Development of a Cylindrical Proton Exchange Membrane Fuel Cell with an Integrated Metal-Hydride Container","volume":"14","author":"Lee","year":"2013","journal-title":"Int. J. Precis. Eng. Manuf."},{"key":"ref_43","first-page":"1","article-title":"A polymer electrolyte membrane fuel cell system for powering portable computers","volume":"122","author":"Zobel","year":"2003","journal-title":"J. Power Sources"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"125","DOI":"10.1016\/j.apenergy.2012.12.056","article-title":"Performance evaluation of a polymer electrolyte membrane fuel cell system for powering portable freezer","volume":"105","author":"Han","year":"2013","journal-title":"Appl. Energy"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"382","DOI":"10.1016\/j.apenergy.2014.08.019","article-title":"Ultra compact direct hydrogen fuel cell prototype using a metal hydride hydrogen storage tank for a mobile phone","volume":"134","author":"Kim","year":"2014","journal-title":"Appl. Energy"},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"620","DOI":"10.1016\/j.renene.2017.06.027","article-title":"PEM fuel cell system control: A review","volume":"113","author":"Daud","year":"2017","journal-title":"Renew. Energy"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"1877","DOI":"10.1016\/j.renene.2019.06.003","article-title":"Numerical investigation of the effect of different layers configurations on the performance of radial PEM fuel cells","volume":"143","author":"Solati","year":"2019","journal-title":"Renew. Energy"},{"key":"ref_48","doi-asserted-by":"crossref","unstructured":"Ismail, M.S., Ingham, D.B., and Pourkashanian, M. (2018). Modeling of portable fuel cells. Portable Hydrogen Energy Systems, Academic Press.","DOI":"10.1016\/B978-0-12-813128-2.00004-8"},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"178","DOI":"10.1016\/j.mattod.2019.06.005","article-title":"Materials, Technological Status, and Fundamentals of PEM Fuel Cells\u2014A Review","volume":"32","author":"Wang","year":"2020","journal-title":"Mater. Today"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"81","DOI":"10.1016\/j.apenergy.2015.12.075","article-title":"A review of recent development: Transport and performance modeling of PEM fuel cells","volume":"165","author":"Wu","year":"2016","journal-title":"Appl. Energy"},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"10549","DOI":"10.1016\/j.ijhydene.2019.09.113","article-title":"Development of cylindrical PEM fuel cells with semi-cylindrical cathode current collectors","volume":"45","author":"Suseendiran","year":"2020","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"2506","DOI":"10.1016\/j.ijhydene.2009.12.158","article-title":"Investigations on fabrication and lifetime performance of self-air breathing direct hydrogen micro fuel cells","volume":"35","author":"Giddey","year":"2010","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"121","DOI":"10.1007\/s00542-003-0321-z","article-title":"A Novel Design and Microfabrication for a Micro PEMFC","volume":"10","author":"Hsieh","year":"2004","journal-title":"Microsyst. Technol."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"1537","DOI":"10.1016\/S0013-4686(03)00034-3","article-title":"Fabrication of a Miniature Twin-Fuel-Cell on Silicon Wafer","volume":"48","author":"Yu","year":"2003","journal-title":"Electrochim. Acta"},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"40","DOI":"10.1016\/S0378-7753(03)00618-9","article-title":"Fabrication of miniature silicon wafer fuel cells with improved performance","volume":"124","author":"Yu","year":"2003","journal-title":"J. Power Sources"},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"410","DOI":"10.1016\/S0378-7753(02)00393-2","article-title":"Design and fabrication of a micro fuel cell array with flip-flop interconnection","volume":"112","author":"Lee","year":"2002","journal-title":"J. Power Sources"},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"4698","DOI":"10.1016\/j.ijheatmasstransfer.2007.03.044","article-title":"Numerical studies on an air-breathing proton exchange membrane fuel cell","volume":"50","author":"Zhang","year":"2007","journal-title":"Int. J. Heat Mass Transf."},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"264","DOI":"10.1016\/j.jpowsour.2007.05.008","article-title":"Numerical studies on an air-breathing proton exchange membrane fuel cell stack","volume":"173","author":"Zhang","year":"2007","journal-title":"J. Power Sources"},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"210","DOI":"10.1016\/j.jpowsour.2006.10.055","article-title":"A model for a vertical planar air breathing PEM fuel cell","volume":"164","author":"Rajani","year":"2007","journal-title":"J. Power Sources"},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"205","DOI":"10.1016\/j.jpowsour.2004.06.044","article-title":"Effect of cathode structure on planar free-breathing PEMFC","volume":"138","author":"Hottinen","year":"2004","journal-title":"J. Power Sources"},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"563","DOI":"10.1016\/j.jpowsour.2005.01.083","article-title":"Three-dimensional modeling and experimental investigation for an air-breathing polymer electrolyte membrane fuel cell","volume":"145","author":"Ying","year":"2005","journal-title":"J. Power Sources"},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"572","DOI":"10.1016\/j.jpowsour.2005.02.066","article-title":"Three-dimensional analysis for effect of channel configuration on the performance of a small air-breathing PEMFC","volume":"145","author":"Ying","year":"2005","journal-title":"J. Power Sources"},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"1351","DOI":"10.1016\/j.ijhydene.2005.04.009","article-title":"Effects of cathode channel configurations on the performance of an air-breathing PEMFC","volume":"30","author":"Ying","year":"2005","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"162","DOI":"10.1016\/S0378-7753(03)00080-6","article-title":"Planar self-breathing fuel cells","volume":"118","author":"Schmitz","year":"2003","journal-title":"J. Power Sources"},{"key":"ref_65","doi-asserted-by":"crossref","first-page":"437","DOI":"10.1016\/j.jpowsour.2005.10.070","article-title":"Influence of cathode opening size and wetting properties of diffusion layers on the performance of air-breathing PEMFCs","volume":"154","author":"Schmitz","year":"2006","journal-title":"J. Power Sources"},{"key":"ref_66","doi-asserted-by":"crossref","first-page":"348","DOI":"10.1016\/j.jpowsour.2005.09.044","article-title":"Effects of cathode open area and relative humidity on the performance of air-breathing polymer electrolyte membrane fuel cells","volume":"158","author":"Jeong","year":"2006","journal-title":"J. Power Sources"},{"key":"ref_67","doi-asserted-by":"crossref","first-page":"7761","DOI":"10.1016\/j.ijhydene.2009.07.077","article-title":"Planar air breathing PEMFC with self-humidifying MEA and open cathode geometry design for portable applications","volume":"34","author":"Bussayajarn","year":"2009","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_68","doi-asserted-by":"crossref","first-page":"750","DOI":"10.1016\/j.renene.2020.12.075","article-title":"Numerical investigation of water droplet impact on PEM fuel cell flow channel surface","volume":"168","author":"Qin","year":"2021","journal-title":"Renew. Energy"},{"key":"ref_69","doi-asserted-by":"crossref","first-page":"21345","DOI":"10.1016\/j.ijhydene.2016.09.160","article-title":"The Effects of the Composition of Microporous Layers on the Permeability of Gas Diffusion Layers Used in Polymer Electrolyte Fuel Cells","volume":"41","author":"Orogbemi","year":"2016","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_70","doi-asserted-by":"crossref","first-page":"124103","DOI":"10.1016\/j.energy.2022.124103","article-title":"Modelling and analysis on effects of penetration of microporous layer into gas diffusion layer in PEM fuel cells: Focusing on mass transport","volume":"254","author":"Zhang","year":"2022","journal-title":"Energy"},{"key":"ref_71","doi-asserted-by":"crossref","first-page":"844","DOI":"10.1016\/j.ijthermalsci.2009.12.002","article-title":"Effect of Cathode Channel Dimensions on the Performance of an Air-Breathing PEM Fuel Cell","volume":"49","author":"Kumar","year":"2010","journal-title":"Int. J. Therm. Sci."},{"key":"ref_72","doi-asserted-by":"crossref","first-page":"457","DOI":"10.1016\/j.energy.2012.12.015","article-title":"A passive method of water management for an air-breathing proton exchange membrane fuel cell","volume":"51","author":"Kumar","year":"2013","journal-title":"Energy"},{"key":"ref_73","doi-asserted-by":"crossref","first-page":"671","DOI":"10.1016\/j.ijhydene.2009.10.086","article-title":"Effect of cathode design on the performance of an air-breathing PEM fuel cell","volume":"35","author":"Kumar","year":"2010","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_74","doi-asserted-by":"crossref","first-page":"293","DOI":"10.1016\/j.applthermaleng.2012.06.039","article-title":"Investigation of Fin Based Oxygen Supply Modules on the Performance of Air-Breathing Polymer Electrolyte Membrane Fuel Cells","volume":"50","author":"Chun","year":"2013","journal-title":"Appl. Therm. Eng."},{"key":"ref_75","doi-asserted-by":"crossref","first-page":"580","DOI":"10.1016\/j.jpowsour.2008.04.051","article-title":"Ag\u2013polytetrafluoroethylene composite coating on stainless steel as bipolar plate of proton exchange membrane fuel cell","volume":"182","author":"Fu","year":"2008","journal-title":"J. Power Sources"},{"key":"ref_76","doi-asserted-by":"crossref","first-page":"25630","DOI":"10.1016\/j.ijhydene.2017.05.114","article-title":"Application of open pore cellular foam for air breathing PEM fuel cell","volume":"42","author":"Baroutaji","year":"2017","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_77","doi-asserted-by":"crossref","first-page":"63","DOI":"10.1016\/j.energy.2011.10.023","article-title":"Water droplet accumulation and motion in PEM fuel cell mini-channels","volume":"39","author":"Carton","year":"2012","journal-title":"Energy"},{"key":"ref_78","doi-asserted-by":"crossref","first-page":"3961","DOI":"10.1016\/j.ijhydene.2015.01.091","article-title":"Enhanced water management in the cathode of an air-breathing PEMFC using a dual catalyst layer and optimizing the gas diffusion and microporous layers","volume":"40","author":"Liao","year":"2015","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_79","doi-asserted-by":"crossref","first-page":"14","DOI":"10.1016\/j.enconman.2012.03.018","article-title":"A PEM fuel cell with metal foam as flow distributor","volume":"62","author":"Tseng","year":"2012","journal-title":"Energy Convers. Manag."},{"key":"ref_80","doi-asserted-by":"crossref","first-page":"13060","DOI":"10.1016\/j.ijhydene.2012.05.008","article-title":"Effects of flow field design on the performance of a PEM fuel cell with metal foam as the flow distributor","volume":"37","author":"Tsai","year":"2012","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_81","doi-asserted-by":"crossref","first-page":"62","DOI":"10.1016\/j.jpowsour.2003.11.011","article-title":"Materials and design development for bipolar\/end plates in fuel cells","volume":"129","author":"Kumar","year":"2004","journal-title":"J. Power Sources"},{"key":"ref_82","doi-asserted-by":"crossref","first-page":"1315","DOI":"10.1016\/j.ijhydene.2023.08.291","article-title":"Air-breathing fuel cell with a columnar cathodic plate for the passive removal of water","volume":"52","author":"Folgado","year":"2024","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_83","doi-asserted-by":"crossref","first-page":"634","DOI":"10.1016\/j.jpowsour.2017.03.155","article-title":"Hydration and dehydration cycles in polymer electrolyte fuel cells operated with wet anode and dry cathode feed: A neutron imaging and modeling study","volume":"359","author":"Boillat","year":"2017","journal-title":"J. Power Sources"},{"key":"ref_84","doi-asserted-by":"crossref","first-page":"687","DOI":"10.1016\/j.ijheatmasstransfer.2018.07.030","article-title":"Analysis of representative elementary volume and through-plane regional characteristics of carbon-fiber papers: Diffusivity, permeability and electrical\/thermal conductivity","volume":"127","author":"Zenyuk","year":"2018","journal-title":"Int. J. Heat Mass Transf."},{"key":"ref_85","doi-asserted-by":"crossref","first-page":"440","DOI":"10.1016\/j.jpowsour.2015.07.034","article-title":"Effective diffusivity in partially-saturated carbon-fiber gas diffusion layers: Effect of local saturation and application to macroscopic continuum models","volume":"296","author":"Gostick","year":"2015","journal-title":"J. Power Sources"},{"key":"ref_86","doi-asserted-by":"crossref","first-page":"319","DOI":"10.1016\/j.ijheatmasstransfer.2015.02.073","article-title":"Effective diffusivity in partially-saturated carbon-fiber gas diffusion layers: Effect of through-plane saturation distribution","volume":"86","author":"Hwang","year":"2015","journal-title":"Int. J. Heat Mass Transf."},{"key":"ref_87","doi-asserted-by":"crossref","first-page":"4459","DOI":"10.1016\/j.ijhydene.2007.05.008","article-title":"Improvement of water management in air-breathing and air-blowing PEMFC at low temperature using hydrophilic silica nano-particles","volume":"32","author":"Jung","year":"2007","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_88","doi-asserted-by":"crossref","first-page":"63","DOI":"10.1016\/S0378-7753(02)00535-9","article-title":"The performance of PEM fuel cells fed with oxygen through the free-convection mode","volume":"114","author":"Li","year":"2003","journal-title":"J. Power Sources"},{"key":"ref_89","doi-asserted-by":"crossref","first-page":"16786","DOI":"10.1016\/j.ijhydene.2015.07.066","article-title":"Study of water accumulation dynamics in the channels of an open-cathode fuel cell through electro-thermal characterisation and droplet visualisation","volume":"40","author":"Obeisun","year":"2015","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_90","doi-asserted-by":"crossref","first-page":"228668","DOI":"10.1016\/j.jpowsour.2020.228668","article-title":"Thermal neutron radiography of a passive proton exchange membrane fuel cell for portable hydrogen energy systems","volume":"480","author":"Chaparro","year":"2020","journal-title":"J. Power Sources"},{"key":"ref_91","doi-asserted-by":"crossref","first-page":"24945","DOI":"10.1016\/j.ijhydene.2022.05.238","article-title":"Research progress of proton exchange membrane fuel cells utilizing in high altitude environments","volume":"47","author":"Song","year":"2022","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_92","doi-asserted-by":"crossref","first-page":"54","DOI":"10.1016\/j.applthermaleng.2013.02.036","article-title":"Evaluation of fin Structure Effects on a Heated Air-Breathing PEM Fuel Cell","volume":"56","author":"Williamson","year":"2013","journal-title":"Appl. Therm. Eng."},{"key":"ref_93","doi-asserted-by":"crossref","first-page":"1156","DOI":"10.1016\/j.jpowsour.2009.08.068","article-title":"Innovative water management in micro air-breathing polymer electrolyte membrane fuel cells","volume":"195","author":"Karst","year":"2010","journal-title":"J. Power Sources"},{"key":"ref_94","doi-asserted-by":"crossref","first-page":"861","DOI":"10.1016\/j.electacta.2018.09.089","article-title":"Implications of Inherent Inhomogeneities in Thin Carbon Fiber-Based Gas Diffusion Layers: A Comparative Modeling Study","volume":"295","author":"Zenyuk","year":"2019","journal-title":"Electrochim. Acta"},{"key":"ref_95","doi-asserted-by":"crossref","first-page":"11856","DOI":"10.1016\/j.ijhydene.2011.05.152","article-title":"Nonlinear orthotropic model of the inhomogeneous assembly compression of PEM fuel cell gas diffusion layers","volume":"36","author":"Vera","year":"2011","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_96","doi-asserted-by":"crossref","first-page":"636","DOI":"10.1002\/fuce.201900164","article-title":"Accelerating fuel cell development with additive manufacturing technologies: State of the art, opportunities and challenges","volume":"19","author":"Tai","year":"2019","journal-title":"Fuel Cells"},{"key":"ref_97","doi-asserted-by":"crossref","first-page":"12243","DOI":"10.1021\/acssuschemeng.3c00848","article-title":"Engineering lung-inspired flow field geometries for electrochemical flow cells with stereolithography 3D printing","volume":"11","author":"Vera","year":"2023","journal-title":"ACS Sustain. Chem. Eng."},{"key":"ref_98","doi-asserted-by":"crossref","first-page":"2783","DOI":"10.1021\/acs.chemrev.9b00783","article-title":"3D printing for electrochemical energy applications","volume":"120","author":"Browne","year":"2020","journal-title":"Chem. Rev."},{"key":"ref_99","doi-asserted-by":"crossref","first-page":"1700127","DOI":"10.1002\/aenm.201700127","article-title":"Emerging 3D-printed electrochemical energy storage devices: A critical review","volume":"7","author":"Tian","year":"2017","journal-title":"Adv. Energy Mater."},{"key":"ref_100","doi-asserted-by":"crossref","first-page":"4230","DOI":"10.1039\/C8TA11860D","article-title":"3D printed electrochemical energy storage devices","volume":"7","author":"Chang","year":"2019","journal-title":"J. Mater. Chem. A"},{"key":"ref_101","first-page":"e01317","article-title":"Advances in additive manufacturing of fuel cells: A review of technologies, materials, and challenges","volume":"43","author":"Singh","year":"2025","journal-title":"Sustain. Mater. Technol."},{"key":"ref_102","doi-asserted-by":"crossref","first-page":"125147","DOI":"10.1016\/j.ijheatmasstransfer.2023.125147","article-title":"Topology optimization of gas channels in proton exchange membrane fuel cells","volume":"222","author":"Xia","year":"2024","journal-title":"Int. J. Heat Mass Transf."},{"key":"ref_103","doi-asserted-by":"crossref","first-page":"235753","DOI":"10.1016\/j.jpowsour.2024.235753","article-title":"Machine learning-assisted design of flow fields for proton exchange membrane fuel cells","volume":"626","author":"Zhou","year":"2025","journal-title":"J. Power Sources"},{"key":"ref_104","doi-asserted-by":"crossref","first-page":"1089","DOI":"10.1016\/j.jpowsour.2005.12.046","article-title":"A study on cathode structure and water transport in air-breathing PEM fuel cells","volume":"159","author":"Jeong","year":"2006","journal-title":"J. Power Sources"},{"key":"ref_105","doi-asserted-by":"crossref","first-page":"133175","DOI":"10.1016\/j.fuel.2024.133175","article-title":"Modeling the performance of electrosprayed catalyst layers in the cathode of polymer electrolyte membrane fuel cells","volume":"380","author":"Duque","year":"2025","journal-title":"Fuel"},{"key":"ref_106","doi-asserted-by":"crossref","first-page":"134728","DOI":"10.1016\/j.energy.2025.134728","article-title":"Boosting the performance of polymer electrolyte membrane fuel cells with porous flow fields: Pros and cons","volume":"318","author":"Perego","year":"2025","journal-title":"Energy"},{"key":"ref_107","doi-asserted-by":"crossref","first-page":"459","DOI":"10.1016\/j.ijhydene.2008.09.088","article-title":"Air-breathing miniature planar stack using the flexible printed circuit board as a current collector","volume":"34","author":"Kim","year":"2009","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_108","doi-asserted-by":"crossref","first-page":"68","DOI":"10.1016\/j.jpowsour.2003.11.012","article-title":"Evaluation of planar free-breathing polymer electrolyte membrane fuel cell design","volume":"129","author":"Hottinen","year":"2004","journal-title":"J. Power Sources"},{"key":"ref_109","doi-asserted-by":"crossref","first-page":"021017","DOI":"10.1115\/1.3177381","article-title":"Optimization of passive air breathing fuel cell cathodes","volume":"7","author":"Babcock","year":"2010","journal-title":"J. Fuel Cell Sci. Technol."},{"key":"ref_110","doi-asserted-by":"crossref","first-page":"238460","DOI":"10.1016\/j.jpowsour.2025.238460","article-title":"Neutron radiography analysis of water management in a passive proton-exchange membrane fuel cell with superhydrophobic catalyst layers","volume":"659","author":"Duque","year":"2025","journal-title":"J. Power Sources"},{"key":"ref_111","doi-asserted-by":"crossref","first-page":"e284","DOI":"10.1002\/cey2.284","article-title":"A review on system and materials for aqueous flexible metal-air batteries","volume":"5","author":"Jiang","year":"2023","journal-title":"Carbon Energy"},{"key":"ref_112","doi-asserted-by":"crossref","first-page":"313","DOI":"10.1016\/j.nanoen.2016.06.031","article-title":"Toxicity, a Serious Concern of Thermal Runaway from Commercial Li-Ion Battery","volume":"27","author":"Sun","year":"2016","journal-title":"Nano Energy"},{"key":"ref_113","doi-asserted-by":"crossref","first-page":"2200323","DOI":"10.1002\/sstr.202200323","article-title":"Direct Ink Writing of 3D Zn Structures as High-Capacity Anodes for Rechargeable Alkaline Batteries","volume":"4","author":"Zhu","year":"2023","journal-title":"Small Struct."},{"key":"ref_114","doi-asserted-by":"crossref","first-page":"1014","DOI":"10.1007\/s42235-022-00173-5","article-title":"3D-Printed Bio-inspired Multi-channel Cathodes for Zinc\u2013air Battery Applications","volume":"19","author":"Men","year":"2022","journal-title":"J. Bionic Eng."},{"key":"ref_115","doi-asserted-by":"crossref","first-page":"1224","DOI":"10.1016\/j.bios.2006.04.029","article-title":"Biofuel cells\u2014Recent advances and applications","volume":"22","author":"Davis","year":"2007","journal-title":"Biosens. Bioelectron."},{"key":"ref_116","doi-asserted-by":"crossref","first-page":"2015","DOI":"10.1016\/j.bios.2006.01.030","article-title":"Biofuel cells and their development","volume":"21","author":"Bullen","year":"2006","journal-title":"Biosens. Bioelectron."},{"key":"ref_117","doi-asserted-by":"crossref","unstructured":"Theodosiou, P., Greenman, J., and Ieropoulos, I.A. (2020). Developing 3D-printable cathode electrode for monolithically printed microbial fuel cells. Molecules, 25.","DOI":"10.3390\/molecules25163635"},{"key":"ref_118","doi-asserted-by":"crossref","first-page":"543","DOI":"10.1016\/j.jpowsour.2015.02.112","article-title":"On the effects of assembly compression on the performance of liquid-feed DMFCs under methanol-limiting conditions: A 2D numerical study","volume":"285","author":"Vera","year":"2015","journal-title":"J. Power Sources"},{"key":"ref_119","first-page":"101219","article-title":"Additive manufacturing of titanium porous transport layers for efficient PEM water electrolysis","volume":"32","author":"McGregor","year":"2025","journal-title":"Mater. Today Sustain."},{"key":"ref_120","doi-asserted-by":"crossref","first-page":"160722","DOI":"10.1016\/j.cej.2025.160722","article-title":"The critical role of the anode porous transport layer\/catalyst layer interface of polymer electrolyte membrane water electrolyzers: A parametric analysis","volume":"509","author":"Chang","year":"2025","journal-title":"Chem. Eng. J."},{"key":"ref_121","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1016\/j.aca.2020.03.028","article-title":"Additive-manufactured (3D-printed) electrochemical sensors: A critical review","volume":"1118","author":"Cardoso","year":"2020","journal-title":"Anal. Chim. Acta"},{"key":"ref_122","doi-asserted-by":"crossref","first-page":"739","DOI":"10.1016\/j.jpowsour.2006.12.012","article-title":"A review of PEM hydrogen fuel cell contamination: Impacts, mechanisms, and mitigation","volume":"165","author":"Cheng","year":"2007","journal-title":"J. Power Sources"},{"key":"ref_123","doi-asserted-by":"crossref","first-page":"104","DOI":"10.1016\/j.jpowsour.2008.06.006","article-title":"A review of PEM fuel cell durability: Degradation mechanisms and mitigation strategies","volume":"184","author":"Wu","year":"2008","journal-title":"J. Power Sources"},{"key":"ref_124","doi-asserted-by":"crossref","first-page":"2975","DOI":"10.1007\/s00170-024-14694-2","article-title":"Microstructural and hardness characterization of stainless steel 316-Inconel 718 multimaterial developed by wire-based Directed Energy Deposition","volume":"135","year":"2024","journal-title":"Int. J. Adv. Manuf. Technol."},{"key":"ref_125","doi-asserted-by":"crossref","first-page":"9767","DOI":"10.1007\/s40964-025-01206-1","article-title":"Electron Beam Bonding: A novel method for joining additively manufactured carbon fiber thermoplastic composites with aluminum to produce multi-material joints for lightweight applications","volume":"10","author":"Raute","year":"2025","journal-title":"Prog. Addit. Manuf."},{"key":"ref_126","doi-asserted-by":"crossref","first-page":"e2546671","DOI":"10.1080\/17452759.2025.2546671","article-title":"Multi-material additive manufacturing: A computational design perspective","volume":"20","author":"Yu","year":"2025","journal-title":"Virtual Phys. Prototyp."},{"key":"ref_127","doi-asserted-by":"crossref","first-page":"10819","DOI":"10.1007\/s40964-025-01262-7","article-title":"Current approaches to digital twins in additive manufacturing: A systematic literature review","volume":"10","author":"Tudorache","year":"2025","journal-title":"Prog. Addit. Manuf."}],"container-title":["Materials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1944\/19\/19\/4174\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,10,14]],"date-time":"2026-10-14T04:15:41Z","timestamp":1791951341000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1944\/19\/19\/4174"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,29]]},"references-count":127,"journal-issue":{"issue":"19","published-online":{"date-parts":[[2026,10]]}},"alternative-id":["ma19194174"],"URL":"https:\/\/doi.org\/10.3390\/ma19194174","relation":{},"ISSN":["1996-1944"],"issn-type":[{"value":"1996-1944","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,29]]}}}