Hybrid Electrolytes for Lithium Batteries

Abstract

Lithium-ion batteries, developed for powering consumer electronics, are being reconfigured for use in electric vehicles, and for backing-up home solar installations. The adoption of batteries in large-scale applications will accelerate if some of the key limitations of current lithium-ion technology can be addressed: cost, energy density, cycle-life, and safety. The limited cycle-life of current lithium-ion batteries is mainly due to the instability of the liquid electrolytes used therein. In this talk we will discuss solid electrolytes. No one solid has the properties needed for practical applications. Glass electrolytes (e.g. lithium-phosphorous-sulfur glasses) exhibit excellent ion transport properties but they are brittle and processes for their incorporation into large format batteries have not yet been established. One may add non-brittle components, but this reduces the conductivity of the electrolyte. Polymer electrolytes (e.g. mixtures of amorphous poly(ethylene oxide) and lithium salts) are soft and non-brittle, but have poor mechanical properties due to the coupling between segmental and ion motion. In this case, incorporating a stiff non-conducting block may be introduced to improve mechanical properties but this results in decreased conductivity. I will first discuss the general properties of hybrid electrolytes. This will be followed by a description of attempts to commercialize these materials.