Organofluorophosphates (OFPs) have been reported to pose substantial health hazards due to their structural similarities to pesticides and nerve agents. They can be categorized into two compound groups i) non-acidic and ii) acidic OFPs. OFPs have already been reported to be formed in lithium-ion batteries (LIBs) after long time cycling. While still being problematic in regards to safety the impact of the OFPs formed after 100 cycles is rather low. This study illustrates the existence of OFPs after the formation process of LIBs using fluoroethylene carbonate (FEC) as an electrolyte additive in a two months old electrolyte. Here only 10 charge/discharge cycles resulted in a substantial amount of formed OFPs. The age of the electrolyte had an impact on the formation of the OFPs as a freshly prepared electrolyte only showed the existence of OFPs after 10 cycles with a higher Cut-Off-voltage of 4.8 V (compared to 4.2 V in the older electrolyte). Utilizing the excellent separation ability and the high mass resolution of high-performance liquid chromatography high-resolution mass spectrometry (HPLC-HRMS) it was possible to identify three non-acidic and two acidic OFPs. A number of NMR-experiments were carried out with the base-electrolyte to investigate the origin of the OFPs due to the different behavior regarding the age of the electrolyte. The knowledge of these compounds being formed in the formation process of the LIBs is of interest for future safety assessments of electrolytes containing FEC as an additive.