Pros
Battery cells is a field with a great potential considering the energy shift. Salaries are being paid at the end of each month.
Cons
In a nutshell. Do not even think about joining the group, unless you know personally a person in the management beforehand. You will work in a literally toxic environment. There will be no room for professional development or salary rise, your supervisor will typically have much less experience/degrees but of course better connections in management, you will end up one morning being suddenly fired (even if you have done great things for the company) and you will never know why, anyway this company is used to hire (and then fire) people to justify their EU funding, the best case scenario would be that you will continue to work off the books. They could potentially spread out false-negative information about you to your future employers.