Background

Lithium-ion batteries can contain either organic or inorganic electrolyte solutions. Conventional organic electrolyte solutions are susceptible to spontaneous combustion, making room temperature ionic liquids the safer and electrochemically superior electrolyte alternative. Ionic liquid electrolytes also form favorable passivation layers on a variety of high-energy electrode materials which helps protect those materials from degradation and improves the utilization of the active material. However, the high viscosity of the solution and the lower ionic conductivity reduces the performance of ionic liquids at high charge and discharge rates. This poor rate capability is one of the major disadvantages for ionic liquid electrolytes.

Technology Overview

Researchers at the University of Colorado, have developed two methods for improving the performance of ionic liquid electrolytes in lithium-ion batteries. They found that using higher concentrations of a lithium salt significantly increases kinetic capabilities of the ionic liquid electrolytes at high charge/discharge rates (). The significantly higher concentrations of the salt improves the performance of the half cell rates. Secondly, the use of ambient heating during cycling also improves the overall cycling performance of these electrolyte solutions. Cycling the cells at slightly elevated temperatures improves the capacities of all the ionic liquid cells, especially at high rates.

Stage of Development

Proof of concept

Benefits

Improved performance
Improved capacitance

Applications

Lithium-ion batteries

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Methods to Improve Performance of Ionic Liquid Electrolytes in Lithium-Ion Batteries