Home Science & Technology A new hybrid electrolyte for high-performance lithium-ion batteries

A new hybrid electrolyte for high-performance lithium-ion batteries


Photograph (left), scanning electron microscope image (center), and schematic illustration of composite electrolyte structure (right), respectively. Author: Grewal and Yabu.

Lithium-ion batteries (LIBs) are widely used batteries that support today’s ITC society, including smartphones and electric vehicles. LIBs are repeatedly charged and discharged by lithium ions passing back and forth between the positive and negative electrodes, with the lithium ion electrolyte acting as a passageway for the ions.

Commonly organic electrolytes such as liquid ethylene carbonate (EC) and their gels were used as Li-ion electrolyte due to their voltage resistance and ionic conductivity. However, how liquids and gels are flammable, it is preferable to switch to safer polymer solid electrolytes.

Polymeric solid electrolytes such as polyethylene glycol (PEG) have been proposed as shock-resistant Li-ion electrolytes. However, PEG-based polymer electrolytes crystallize side by side room temperaturewhich caused the Li-ion conductivity to drop significantly to about 10-6 S/cm at room temperature.

To solve this problem, the research team invented a new type of polymer solid electrolyte by combining a porous polymer membrane with pores of several microns and a polymer electrolyte based on polyethylene glycol and PEG that can be photocross-linked. The polymer solid electrolyte realized a wide potential window (4.7 V), a high lithium-ion conductivity of 10-4 S/cm class which is equivalent to liquid and sufficient for practical use and high Li-ion transfer number (0.39).

A new hybrid electrolyte for high-performance lithium-ion batteries

Temperature dependence of composite electrolytes of honeycomb film of different sizes on ionic conductivity. Author: Grewal and Yabu

Lithium ions that pass into the electrolyte move in different directions due to natural diffusion. The distance is from several μm to 10 μm and does not always move linearly between the electrodes, which is one of the reasons for the decrease in ionic conductivity. Therefore, in this study, the performance of solid polymer electrolytes based on photocrosslinked PEGs was improved by combining them with micron-sized porous membranes.

This polymer solid electrolyte not only shows high performance as an electrolyte, but is also expected to be effective in suppressing the formation of Li dendrites (dendritic crystals), which can cause ignition, due to the inclusion of a porous membrane. Thanks to the implementation of a safe, High performance LIBs, this achievement will contribute to the realization of sustainable energy supply, which is the seventh goal of the SDGs.

The study was published in iScience.

Composite solid-state electrolyte for high-voltage lithium-metal batteries developed in situ

Additional information:
Manjit Singh Grewal et al., Enhancement of Ionic Conductivity and Li-Ion Transport of Photocrosslinked Polymer with Hexagonal Porous Film Hybrids, iScience (2022). DOI: 10.1016/j.isci.2022.104910

Citation: New hybrid electrolyte for high-performance lithium-ion batteries (2022, September 7) Retrieved September 7, 2022, from https://phys.org/news/2022-09-hybrid-electrolyte-high-li-ion-batteries .html

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