Assembly Process Engineer

Factorial 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. 

Factorial Energy is seeking an Assembly Process Engineer to join our team in our Cheonan, South Korea location. This person will be responsible for the development, optimization, and scale-up of pouch cell assembly processes for our Silicon Power Cell line, covering the full assembly chain from post-stacking through final sealing. The ideal candidate brings deep hands-on expertise in pouch stacking cell assembly, is comfortable driving yield improvement and process standardization, and thrives in an early-stage, fast-moving manufacturing environment. 

• Lead development and optimization of pouch stacking cell assembly processes covering electrode alignment, stacking compaction, tab forming, pre-sealing, and final sealing 
• Define and maintain process windows for all key assembly parameters, establishing CTQs and process standards 
• Establish and maintain SOPs, PFMEA, and Control Plans for all assembly process steps 
• Adapt assembly structures and processes to accommodate silicon anode volume expansion characteristics, minimizing stacking flatness deviation and sealing reliability risks 
• Collaborate with R&D and electrode teams to evaluate silicon anode impact on stacking flatness, electrode slippage, and sealing integrity 
• Develop and validate process parameters to mitigate assembly and reliability risks caused by Si anode volume changes during cycling 
• Lead assembly process transfer from lab/pilot scale through EVT/DVT/PVT/MP stages 
• Identify yield and cycle time bottlenecks and develop ramp-up plans targeting 2–5% yield improvement 
• Support FAT/SAT and equipment qualification (IQ/OQ/PQ) for assembly equipment 
• Partner with equipment vendors on assembly fixture, tooling, and automation solution design and validation 
• Apply DOE, SPC, 5-Why, and fishbone analysis to identify root causes of assembly defects (tab misalignment, sealing defects, stacking wrinkles) 
• Drive cross-functional (R&D/Quality/Equipment) issue resolution and CAPA closure 
• Document assembly process experience to build replicable technical solutions 

• Have 3+ years of hands-on experience in lithium-ion pouch cell assembly process development or manufacturing 
• Have at least 2 years of experience in pouch stacking cell assembly processes 
• Have led or substantially contributed to at least one full NPI or mass production ramp-up project
• Have deep understanding of pouch stacking cell structures and key assembly control points 
• Have experience with silicon anode pouch cell assembly or high-expansion electrode systems preferred 
• Are familiar with process qualification frameworks (DFMEA → PFMEA → CP → SOP) 
• Have basic mechanical assembly knowledge; ability to interpret mechanical drawings and understand assembly tolerances
• Are proficient in DOE, SPC, and data analysis tools 
• Have experience with defect analysis methodologies (5-Why, fishbone, 8D) 
• Hold a Bachelor's degree or higher in Mechanical Engineering, Materials Science, Chemical Engineering, or related field 
• Have experience in pilot line or new production line setup from 0 to 1 (preferred) 
• Are familiar with IATF 16949 and APQP systems (preferred) 

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 (recruitment@factorialenergy.com)