Data Scientist Machine Learning

Do you want to contribute to a more sustainable world? Are you excited to deploy data science and machine learning to help shape the future of battery technology and consequently the future of consumer electronics and mobility? Can you not wait to dive into a VC-backed deep tech scale-up with the ambition to change the world?

About LeydenJar

LeydenJar Technologies aims to become world’s innovation leader in advanced battery anodes to energize batteries for progress. High energy density of battery cells is an urgent and unmet need for a wide range of industries from consumer electronics to electric vehicles. By addressing the bottleneck of the battery anode, LeydenJar can improve this by 70% in an industry that can only improve 3% per year. Our pure silicon anode is regarded as the holy grail to achieve in the battery industry. Progress is not only about enabling new products, it also means a more sustainable supply chain, resilience and access to battery technology in geopolitical context and enabling electrification.

Our business model is to provide pure silicon anode rolls that fit directly in the battery plants of cell partners, allowing our clients to make step change in their product performance, or to allow new product categories such as e-flight. Our immediate focus in on the consumer electronics industry, with first automotive application development starting in shortly. To produce pure silicon anodes, we have crossed over from semicon thin film technology (plasma deposition) to anode production. This has given us a unique product quality that can last long without the problems associated with silicon as a battery material. To produce this material at scale we have pioneered roll to roll production tools that we will deploy in PlantOne in Eindhoven, expected to open in 2026. We will produce rolls and validate the production tools, allowing us to ramp up to large commercial production in PlantTwo (location to be determined). Ramping up to become a leading player in the battery market is an enormous opportunity, but also daunting development that requires a team of energy dense professional leaders. 

We are now looking for a Data Scientist with experience in Machine Learning to join our team and help us harness the power of data to drive innovation forward, improve our processes, and accelerate our commercialization.

Your mission
As a Data Scientist at LeydenJar, your mission is to transform raw data into key insights that drive innovation in materials and production. You will empower R&D, engineering, and operations teams with models and tools that uncover patterns, optimize performance, and accelerate decision-making. Your work will directly contribute to scaling the world’s most promising energy-dense battery anode technology.

Your primary location will be Leiden. You may also be required to work at our Eindhoven site as needed.

You will report to VP Battery under the CTO line. You will work especially closely together with the Battery R&D team, the Product Development team, the Battery Production Team, and fellow Data professionals.

In this versatile role for lots of aspects, you will have a chance to develop yourself by leading and supporting the various projects of this fast-growing company. This job is perfect for a data scientist who is interested in the world of atoms, not just bits!

Your responsibilities:

• Design, build, and validate machine learning models to support materials R&D, process optimization, and manufacturing scale-up.

• Perform exploratory data analysis and build visual dashboards that allow teams to spot patterns and opportunities.

• Collaborate closely with lab engineers and scientists to translate business questions into analytical solutions.

• Write clean, reusable Python code (pandas, numpy, scikit-learn, etc.).

• Support robust feature engineering, data wrangling, and statistical validation of experiments.

• Develop and maintain SQL queries to extract insights from structured relational databases.

• Apply statistical testing and inference to lab and pilot-scale data, including ANOVA, probability distributions, and Bayesian approaches where relevant.

• Work with sometimes messy, incomplete, or small datasets - common in cutting-edge lab environments - and turn them into actionable insights.

• Use Git and GitHub (branches, PRs, reviews) for collaborative model development.

• Communicate results and modeling approaches clearly to scientists, engineers, and business stakeholders with varying levels of technical expertise.

About you:

• PhD or Master in data science, statistics, physics, engineering, applied mathematics or a related field.

• Proven experience applying machine learning to extract insights and build predictive models, ideally within materials science or process development environments.

• Strong Python programming skills and hands-on experience with data science libraries (pandas, numpy, scikit-learn, matplotlib, seaborn).

• Solid understanding of statistics and probability, including hypothesis testing and model evaluation metrics.

• Experience working with SQL and managing complex queries, joins, and CTEs on structured databases.

• Ability to build compelling plots and dashboards (Power BI, matplotlib, seaborn).

• Experience with Git and collaborative coding practices is a plus.

• Comfortable communicating complex models and uncertainty to diverse stakeholders.

• Strong customer focus.

• Experience with Six Sigma is a plus.

• You are fluent in English.
  

Additional desirable experience:

• Experience working with small datasets or laboratory data.

• Exposure to Bayesian optimization or Gaussian process models.

• Familiarity with deployment tools (Flask/FastAPI, Docker) and model versioning.

• Experience using cloud platforms such as AWS (S3, SageMaker), GCP, or Azure.

Why LeydenJar?

🌟 Unleash your potential: Dive into a realm where personal growth meets ownership, with the backing to achieve your career aspirations.

💼 Benefits beyond the basics: Enjoy a treasure trove of perks, from a comprehensive pension plan to travel reimbursement, insurance coverage, and mental health support. And yes, there's fresh fruit every Monday because why not?

⏰ Work your way: Embrace the freedom of flexible hours and hybrid working, complemented by a generous 25 vacation days annually.

🍹 Thirsty for Fun: Join us every first Thursday for 'Thirsty Thursday,' where we unwind and share good vibes in a laid-back setting!

🎉 Fun with a purpose: Dive into our calendar of internal events, mixing business with pleasure, and fuel your personal development with exclusive trainings and courses.

Do you want to take on the challenge as Data Scientist? 

We are looking forward to your application!

If you'd like to learn more about LeydenJar amazing team, see below:

At LeydenJar we value diversity, and we provide equal opportunities to all applicants without regard to race, color, ethnicity, religion, gender, pregnancy/childbirth, age, national origin, sexual orientation, disability, etc. If there are two or more applicants of equal suitability for a certain position, LeydenJar can under circumstances decide to select applicants based on positive discrimination in full compliance with all relevant and applicable law.