The battery electric drive is an important component of sustainable mobility. However, this is associated with energy-intensive battery production and high demand for raw materials. The circular economy can be used to overcome these barriers. In particular, the secondary use of batteries in stationary energy storage systems (B2U storage systems) has been proposed for the circularity of electromobility. To implement such systems, a circular business model and a cross-industry ecosystem are required. However, the meaning, scope, and structure of these concepts have received little research to date. To close this gap, a theoretical construct for a circular business model based on the theory of business model, sustainability, circular economy, and ecosystem must be developed. On this basis, 16 expert interviews were conducted and analyzed using qualitative content analysis. Numerous challenges resulted from the analysis. The willingness to pay for B2U storage systems is limited, the availability of second-life batteries is restricted, and dismantling as well as testing the batteries is time-consuming. Product-service systems help to increase the willingness to pay and expand the value proposition and value capture, digital technologies realize cost-efficient value creation, and an effective ecosystem enables the expansion of battery procurement.