Battery Cell Engineer (R&D)

PolyJoule develops safe, sustainable energy storage built on conductive polymer chemistry; no rare earth metals, no fire risk, no compromises. From city buildings to business to homes, we bring reliable power to the places other batteries can't go. Job Description PolyJoule is seeking a Battery Cell Engineer to join our R&D team and lead the development and testing of prototype battery cells. This role involves assembling and optimizing cell designs, performing electrochemical testing, and analyzing performance data to accelerate material and product development. The position is based in Billerica, MA and requires in-person attendance. Responsibilities Assemble prototype battery cells (pouch and prismatic) using automated and manual techniques for electrode fabrication, cell stacking, tab welding, enclosure sealing, and electrolyte filling. Design and optimize electrode formulations, including slurry preparation and coating processes such as slot-die, doctor blade, and dip coating; oversee subsequent steps including calendaring, precision cutting for electrode geometry, and controlled drying to ensure uniformity and performance. Contribute to defining lab-scale assembly workflows for novel chemistries to enable rapid prototyping and process optimization. Conduct electrochemical performance testing, including charge/discharge cycling, rate capability, cyclic voltammetry, and impedance spectroscopy. Perform stress testing and accelerated aging protocols to evaluate durability under various conditions; analyze failure modes through post-mortem techniques (e.g., electrode morphology, separator integrity, and electrolyte decomposition) to identify root causes and inform design improvements. Collaborate with chemists and engineers to integrate new materials into functional cells; evaluate compatibility of electrodes, electrolytes, separators, and other components to ensure optimal performance, safety, and manufacturability in prototype and lab-scale assemblies. Maintain accurate documentation of fabrication parameters and test results, including detailed bills of materials (BOMs), comprehensive experiment records, and version-controlled files to ensure traceability, reproducibility, and alignment with quality standards. Support scale-up efforts and assist in transitioning successful designs to pilot production. Communicate technical results and milestones to leadership and cross-functional teams for decision-making. Participate in vendor and material sourcing, qualification, and technical due diligence for battery components. Qualifications Required Qualifications B.S. or M.S. in Chemical Engineering, Materials Science, Electrochemistry, or related field. Hands‑on experience with battery cell assembly and electrochemical testing. Familiarity with non‑aqueous and aqueous electrochemistry and battery characterization techniques. Strong analytical skills and proficiency with data analysis tools (Excel required). Ability to work independently and collaboratively in a fast‑paced R&D environment. Excellent organizational, documentation, and communication skills. Passion for innovation and sustainability in energy storage technologies. Preferred Qualifications Experience with advanced coating processes (slot-die, doctor blade, comma bar) and electrode fabrication workflows. Knowledge of failure mode analysis, stress testing, and accelerated aging protocols. Proficiency in programming/data analysis tools (Python, MATLAB). Familiarity with BOM management, experiment record‑keeping, and version control systems. Why Join PolyJoule? Work on groundbreaking battery technology in a dynamic, innovative environment. Contribute to sustainable energy solutions with real-world impact. Competitive compensation and benefits package. PolyJoule is committed to building a diverse and inclusive team where everyone feels valued and respected. #J-18808-Ljbffr PolyJoule, Inc.