The electrolyte of a used lithium-ion battery from a hybrid electric vehicle (HEV) was investigated. The liquid electrolyte was collected through the pressure valve of these 5 Ah cells. It consists of (29.8 +/- 0.2) wt.% dimethyl carbonate (DMC), (21.7 +/- 0.1) wt.% ethyl methyl carbonate (EMC), (30.3 +/- 0.3) wt.% ethylene carbonate (EC) and (2.2 +/- 0.1) wt.% cyclohexyl benzene (CHB) which were identified with GC-MS and quantified with GC-FID. Li+ (1.29 +/- 0.04) mol L-1 and PF6- were determined with IC as the main ionic species in the solution. Furthermore, BF4- was clearly identified with IC-ESI-MS, IC-ICP-MS and B-11 NMR and quantified to a concentration of (120.8 +/- 8.3) mg L-1 with ICP-OES. The presence of POF3 (detected with GC-MS), F-, PO2F2-, HPO3F- and H2PO4- (determined with IC-ESI-MS) can be attributed to the reaction of the conducting salt LiPF6 via PF5 with traces of water. HPO3F- and H2PO4-, could only be observed in cells which were opened in a laboratory hood under exposure of air humidity. This experiment was done to simulate escaping electrolyte from an HEV battery pack. Furthermore, several alkyl phosphates (identified with GC-MS and IC-ESI-MS) are present in the solution due to further reaction of the different fluorinated phosphates with organic carbonates. (C) 2014 Elsevier B.V. All rights reserved.