Past research on team boundary work has focused on a “cold,” information-exchange perspective to explain why boundary activities affect team innovation. Although the theory is widely accepted, empirical studies on the actual mechanism are scant and produce inconsistent results. Drawing from Interaction Ritual Theory (Collins, 2004), we propose a “warm,” affective perspective that emphasizes team emotional energy - a shared feeling of enthusiasm among team members - as a mechanism linking boundary work and team innovation. Moreover, we examine a theory-driven contextual factor -team role overload - that modifies the hypothesized mediated relationship. Based on field data from four different sources of 89 automotive research and development teams (comprising 724 employees, 89 direct supervisors and 18 managers), we found that both team boundary-spanning and boundary-buffering activities are associated with higher levels of team emotional energy, which, in turn, are related to greater levels of team innovation. Moreover, the mediated relationship of boundary-buffering activities, team emotional energy and team innovation is moderated by team role overload, such that the mediated relationship is stronger when team role overload is higher. Our study contributes to the literature by broadening our understanding of why boundary work is effective and when it matters most.