Preparation, Performance in Various Cell Configurations and Limitations of Novel Electrolyte Components for Liquid and Gel Polymer Electrolytes

Electrolytes in electrochemical devices have to enable fast transport of ions between the electrodes. In lithium, lithium-ion batteries and related cell systems, electrolytes have to fulfill several additional requirements beyond lithium ion transport. These requirements include “active” properties such as e.g., (i) SEI formation at the anode, (ii) interphase formation at the cathode, (iii) inhibition of corrosion of the Al current collector at the cathode and (iv) good contacting abilities (including wetting) with the electrodes and separator, as well as “passive” characteristics, such as e.g., (i) oxidation stability at the cathode, (ii) sufficient safety during normal operation and abuse, and (iii) sufficient low and high temperature performance. In this presentation, we will touch several of these topics by way of illustrative examples. a) Typical examples for novel components in the electrolyte field are SEI forming additives, which are applied and investigated in propylene carbonate (PC) based electrolytes. PC benefits from a good combination of electrolyte solvent properties. In absence of an effective SEI additive, graphite is however usually exfoliated by PC. Several SEI additives have been synthesized and developed. Examples are fluoro-organic compounds (cf. Figure 1) such as fluoro-acetone (FA) and Methyl tetrafluoro-2-(methoxy) propionate (MTFMP). 2,3