Progressing to Solid-State Lithium Batteries

A research group led by professor Jan D. Miller of the University of Utah’s Department of Metallurgical Engineering has received a $191,700 grant to aid the development and commercialization of a solid polymer electrolyte/electrode technology for lithium batteries.

Commercial lithium batteries were first introduced in 1991 by the Sony Corporation and are used in a wide range of portable electronic, medical and military devices as well as hybrid and electric vehicles. These lithium batteries can provide multiple usages and have had satisfactory performance; however, liquid electrolytes have, in some instances, demonstrated solvent leakage and flammability.

The Miller group has developed a new nanocomposite material for advanced solid polymer electrolyte and electrode design and fabrication of cathodes for lithium batteries that improves safety, increases energy density and reduces complexity and cost of manufacturing compared to conventional liquid or gel electrolytes currently in use.

A key component of the new electrolyte is halloysite, a super-fine aluminosilicate mineral and natural nanotube material that is a unique Utah resource available from Applied Minerals. The halloysite nanocomposite solid-state electrolyte is a thin, almost transparent membrane that will make possible the use of high energy all solid-state lithium batteries over a wide range of temperatures.

The Miller group has filed for patents on the halloysite nanotube technology based on preliminary results demonstrating its important advantages.

The university’s Technology & Venture Commercialization (TVC) is currently working with the Miller group on a possible transfer of the technology to a battery manufacturer or to a spin-out company. In the past, TVC has supported the Miller group by conducting marketing research and analysis to determine potential markets for commercialization and with grant writing.

Moving forward, Miller and his group will use the research grant in hopes of delivering a safe, adaptable, high-performing halloysite nanotube solid polymer electrolyte, electrode and corresponding lithium battery for a lower price than what is currently available on the market.

Nano Energy Journal – Natural halloysite nano-clay electrolyte for advanced all-solid-state lithium-sulfur batteries

Highlights

• Natural halloysite nanotubes (HNT) are directly used as solid electrolyte filler.
• Oppositely charged HNT surfaces enhance lithium ionic conductivity.
• Application of the HNT electrolyte is demonstrated by high energy Li-S battery.
• Sustainable high energy storage is revealed at a reduced cost.

Abstract

Solid polymer electrolytes (SPEs) show increasing potential for application in high energy lithium sulfur batteries due to good flexibility and high safety. However, low room temperature ionic conductivity of SPEs has become the main limitation. Herein, a novel SPE film using natural halloysite nano-clay has been fabricated, which exhibits exceptional ionic conductivity of 1.11×10−4 S cm−1 and lithium ion transference number of 0.40 at 25 °C. The mechanism of enhanced lithium ion transport is considered. The oppositely charged halloysite nanotube surfaces separate lithium salt into lithium ions that are absorbed on the negatively charged outer silica surface, and anions may be accommodated on the positively charged inner aluminol surface. So, an ordered 3D structure for free lithium ion transport is suggested. This potential application of the natural halloysite nano-clay has been demonstrated by an all-solid-state lithium-sulfur battery over a wide temperature range of 25–100 °C. These results reveal the possibility of realizing sustainable high energy storage at a reduced cost.

Professor Miller’s group of researchers has demonstrated how the incorporation of DRAGONITE (Applied Materials created halloysite clay)into a polymer electrolyte prevents crystallization over a range of operating temperatures and, consequently, eliminates the resulting conductivity losses experienced by today’s solid-state Li battery technologies. This breakthrough is due primarily to the unique surface properties of DRAGONITE’s nano-tubular morphology, which creates multi-dimensional pathways that enhance the conductivity of electrolyte materials.

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