Assembly Process Engineer/ Senior Engineer

Factorial Energy is an American solid-state battery company headquartered in Billerica, Massachusetts, focused on developing high-performance energy storage solutions for electric mobility, defense, and AI-driven robotics applications. The company designs and manufactures solid-state batteries that overcome the fundamental limitations of conventional lithium-ion technology, including energy density constraints, weight penalties, and safety concerns associated with liquid electrolytes. Factorial's batteries have demonstrated real-world capability, including powering a vehicle on a drive exceeding 1,200 kilometers on a single charge using solid-state cells. Factorial's mission centers on advancing American technology leadership, economic resilience, and domestic industrialization of next-generation battery technology. The company positions its work as critical to U.S. national security, energy independence, and global competitiveness across the automotive, defense, and robotics sectors. With over 10 years of research and development and more than 150 patents and patent applications, Factorial has built a deep intellectual property portfolio and established partnerships with four top-tier automotive manufacturers, including Stellantis. What distinguishes Factorial is its capital-efficient manufacturing approach: its technology is approximately 80 percent drop-in compatible with existing lithium-ion production infrastructure, significantly reducing the cost and disruption required for partners to transition to solid-state production. The company also employs a proprietary dry-coating process to further enhance manufacturing efficiency and reduce costs. Recent milestones include securing its first commercial aerospace battery order and completing successful flight tests with partner Tulip.

Who We Are

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. 

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&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:

• Responsible for the development and optimization of pouch stacking cell assembly processes, covering the entire process from post-stacking to sealing completion.
• Lead or participate in key processes such as electrode alignment, stacking compaction, tab forming, and pre-sealing/final sealing. 
• Establish and maintain assembly SOPs, PFMEA, and Control Plans, defining CTQs and process windows. 
• Participate in the development of pouch cell assembly processes for silicon anodes, adapting structures and processes to accommodate silicon anode expansion characteristics. 
• Collaborate with R&D to evaluate the impact of silicon anodes on stacking flatness, electrode slippage, and sealing reliability.
• Support optimization of process parameters to mitigate assembly and reliability risks caused by volume changes.
• Participate in the process introduction and scaling of new products from EVT/DVT/PVT to MP. 
• Identify yield and cycle time bottlenecks in the assembly process and develop ramp-up plans for mass production. 
• Support improvements in UPH, OEE, and yield during mass production (target yield increase of 2–5 pct).
• Leverage mechanical assembly expertise to participate in the review of assembly fixtures, tooling, and automation solutions. 
• Assist equipment engineers in assembly equipment debugging, validation, and acceptance (FAT/SAT). 
• Possess engineering analysis capabilities for assembly precision, alignment tolerances, and stress conditions. 
• Use methodologies such as 5Why, Fishbone, and DOE to analyze assembly defects (e.g., tab misalignment, sealing defects, stacking wrinkles).
• Drive cross-departmental (R&D/Quality/Equipment) issue resolution.
• Document assembly process experience to create replicable technical solutions.

We are looking for people who have:

• Bachelor’s degree or higher in Mechanical Engineering, Materials, Automation, Electrochemistry, or related fields. 
• 3+ years of experience in the lithium battery industry.
• At least 2 years of experience in pouch stacking cell assembly processes.
• Experience in full-cycle projects from process development to mass production (≥1 mass production project).
• Familiarity with pouch stacking cell structures and key assembly control points.
• Understanding and application of process development workflows (DFMEA→ PFMEA → CP → SOP). 
• Basic mechanical assembly knowledge, ability to interpret mechanical drawings, and understand assembly tolerances and mechanisms. 

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 ([email protected])