During charging and discharging of Li-ion batteries the thickness of the cell increases reversible due to intercalation (“breathing”) and non-reversible due to ageing effects (“swelling”). This may influence crash safety and lifetime of a battery module. Within project BonuS these aspects will be investigated scientifically based on numerical simulations and experimental methods on the laboratory scale. In future, the scientific insights of this research project may enable the development of significantly improved battery modules with respect to safety and lifetime.