This paper has the aim to demonstrate that Acoustic Emission (AE) is an appropriate technique to become a diagnostic tool for state of charge, state of health and state of security of lithium-ion cells. These issues are actually key parameters for both performance and durability improvement. The presented results deal with the monitoring of the SEI formation and the first lithium ion intercalation on the surface and inside the graphite electrode. AE events coming from different sources have thus been identified. A large number of acoustic emission events occur during the film formation corresponding to gas evolution and cracking processes happening at the electrode surface (lithium intercalation). The acoustic emission signals were analyzed and correlated with electrochemical phenomena taking place during the cell operation. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.045201jes]