Who We AreFactorial Energy is a pioneering U.S.-based solid-state battery company driving the future of energy storage and electrification. Partnered with global leaders including Mercedes-Benz, Stellantis, Hyundai, and Kia, Factorial is at the forefront of developing next-generation e-mobility platforms for commercial, defense, and consumer applications—spanning electric vehicles (EVs), drones, eVTOL aircraft, power tools, marine systems, robotics, and more. The company has achieved multiple industry firsts, including being the first to power a demonstration vehicle with a global OEM (Mercedes- Benz) which achieved over 1,200 km (749 mi) of range, and the first to earn UN 38.3 certification for automotive-sized lithium-metal solid-state cells, the first to deliver B-samples of automotive-sized solid-state batteries to major OEMs. The Opportunity:Factorial is looking for an Assembly Process Engineer/ Senior Engineer who will be responsible for the assembly process and equipment development for consumer lithium-ion battery applications. We leverage cutting-edge automated manufacturing to revolutionize consumer battery performance, cost, and scalability. This role requires experience in close cooperation with internal teams and external partners. This candidate will be involved from the beginning of process optimization for R&amp;D projects, pilot line scale-up, and through to low/high-volume production. The candidate must demonstrate excellent written and verbal communication skills to facilitate efficient communication between various departments/vendors.  In this role, you will:<ul><li>Responsible for the development and optimization of pouch stacking cell assembly processes, covering the entire process from post-stacking to sealing completion.</li><li>Lead or participate in key processes such as electrode alignment, stacking compaction, tab forming, and pre-sealing/final sealing. </li><li>Establish and maintain assembly SOPs, PFMEA, and Control Plans, defining CTQs and process windows. </li><li>Participate in the development of pouch cell assembly processes for silicon anodes, adapting structures and processes to accommodate silicon anode expansion characteristics. </li><li>Collaborate with R&amp;D to evaluate the impact of silicon anodes on stacking flatness, electrode slippage, and sealing reliability.</li><li>Support optimization of process parameters to mitigate assembly and reliability risks caused by volume changes.</li><li>Participate in the process introduction and scaling of new products from EVT/DVT/PVT to MP. </li><li>Identify yield and cycle time bottlenecks in the assembly process and develop ramp-up plans for mass production. </li><li>Support improvements in UPH, OEE, and yield during mass production (target yield increase of 2–5 pct).</li><li>Leverage mechanical assembly expertise to participate in the review of assembly fixtures, tooling, and automation solutions. </li><li>Assist equipment engineers in assembly equipment debugging, validation, and acceptance (FAT/SAT). </li><li>Possess engineering analysis capabilities for assembly precision, alignment tolerances, and stress conditions. </li><li>Use methodologies such as 5Why, Fishbone, and DOE to analyze assembly defects (e.g., tab misalignment, sealing defects, stacking wrinkles).</li><li>Drive cross-departmental (R&amp;D/Quality/Equipment) issue resolution.</li><li>Document assembly process experience to create replicable technical solutions.</li></ul>We are looking for people who have:<ul><li>Bachelor’s degree or higher in Mechanical Engineering, Materials, Automation, Electrochemistry, or related fields. </li><li>3+ years of experience in the lithium battery industry.</li><li>At least 2 years of experience in pouch stacking cell assembly processes.</li><li>Experience in full-cycle projects from process development to mass production (≥1 mass production project).</li><li>Familiarity with pouch stacking cell structures and key assembly control points.</li><li>Understanding and application of process development workflows (DFMEA→ PFMEA → CP → SOP). </li><li>Basic mechanical assembly knowledge, ability to interpret mechanical drawings, and understand assembly tolerances and mechanisms. </li></ul>Work Location:Cheonan, South Korea Factorial Energy is an equal opportunity employer that values diversity at all levels. All qualified applicants, regardless of personal characteristics, are encouraged to apply.To request a reasonable accommodation to complete an application, job interview, and/or to otherwise participate in the hiring process, please contact (<a href="mailto:recruitment@factorialenergy.com">recruitment@factorialenergy.com</a>)

Factorial is a dynamic venture-backed company dedicated to creating a sustainable future. With a passionate team of engineers and business professionals, Factorial is developing breakthrough solid-state batteries to offer longer range per charge and increased safety. The company entered joint development agreements with Mercedes-Benz, Stellantis, and Hyundai Motor Company and was recently featured in The Boston Globe and The New York Times.

Assembly Process Engineer/ Senior Engineer

About the Job

About the Company

Factorial Energy

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