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Ionic Liquid for electrochemical devices

aqueous synthesislithium batteriesPhosphonium ionic liquidsafe electrolytethermal-electrochemical stability

Introduction

The present invention relates to a salt (namely ionic liquid), liquid at room temperature, which combines high thermal and electrochemical stability. The invention further relates to a process for obtaining the ionic liquid (and a composition which comprises it) and its use as an electrolyte in an electrochemical device.

Technical features

Organic solvents are inherently flammable, volatile and, consequently, potentially harmful to the user and the environment. The present patent relates to a salt, called ionic liquid which, even below room temperature, is liquid. Ionic liquids are non-volatile and non-flammable fluids, which display interesting properties (solvent power, chemical/electrochemical/thermal stability, ion conduction, high specific heat, hydrophobicity/hydrophilicity). Therefore, they are considered alternative, reliable and safe solvents to the organic ones. The patented ionic liquid consists of a tetra-alkyl-phosphonium cation and a perfluoro-alkyl-sulphonyl-imide anion, proposed as a solvent and/or electrolyte additive for electrochemical devices and, in particular, lithium batteries. It is able to combine thermal (> 250 ° C) and electrochemical (> 5 V) stability never observed in commercial ionic liquids. Therefore, it would allow the batteries to operate at higher operating voltages than the commercial ones, allowing to increase the energy content of the device, in conditions of safety and reliability, even at high temperatures. The patented ionic liquid can be prepared through synthesis routes which use water as the only processing solvent and used in combination with traditional organic solvents and polymer materials.

Possible Applications

  • Electrochemical storage and energy conversion devices, in particular lithium batteries;
  • Separation/extraction processes (confined within suitable hosts), heat exchange fluid;
  • Lubricant.

Advantages

  • Increase the safety and reliability level in electrochemical devices;
  • Possibility of operating at voltages and temperatures not allowed to commercial electrochemical devices;
  • Preparation performed using water as the only processing solvent.