Identification of alkylated phosphates by gas chromatography-mass spectrometric investigations with different ionization principles of a thermally aged commercial lithium ion battery electrolyte.

The thermal aging process of a commercial LiPF6 based lithium ion battery electrolyte has been investigated in view of the formation of volatile phosphorus-containing degradation products. Aging products were analyzed by GC-MS. Structure determination of the products was performed by support of chemical ionization MS in positive and negative modes. A fraction of the discovered compounds belongs to the group of fluorophosphates (phosphorofluoridates) which are in suspect of potential toxicity. This is well known for relative derivatives, e.g. diisopropyl fluorophosphate. Another fraction of the identified compounds belongs to the group of trialkyl phosphates. These compounds may provide a positive impact on the thermal and electrochemical performance of Li-based batteries as repeatedly described in the literature.

Ionic liquids as stationary phases in gas chromatography--an LSER investigation of six commercial phases and some applications.

The separation properties of six novel stationary phases for gas chromatography, commercially available from Sigma-Aldrich (Supelco) and based on ionic liquids (ILs), were investigated. The linear solvation energy relationship model (LSER) was used to describe the molecular interactions between these stationary phases and 30 solutes. The solutes belong to different groups of compounds, like haloalkanes, alcohols, ketones, aromatics, aliphatics, and others. A good description of different interactions, as described by the LSER model, could be achieved. The calculated values of system constants for the ionic liquid phases were compared with constants of commonly used standard phases like a 5 % phenyl/95 % dimethyl siloxane and a polyethylene glycol phase. The solute descriptors are in good agreement with those found by previous authors who have used the LSER model for 44 different ionic liquids as stationary phase. The experiments were carried out at two temperatures to evaluate the influence on the phase parameters and separation characteristics. The interactions of different functional groups with the IL phases are discussed. These novel IL phases are a promising replacement of or an addition to common polar phases. Based on the evaluated phase properties, several possibilities for applications of these novel phases are shown.