Battery Technology and the Market

Batteries energize a diverse range of devices, from smoke alarms to the space satellites that are so essential for modern living. The continuing and growing need for energy-efficient devices and concerns about environmental degradation call for concerted measures to conserve, store, and develop non-polluting energy storage devices. Advanced battery technology is a practical way to address issues related to energy storage.

A number of battery-making technologies have evolved during this century. The traditional battery workhorse - the lead-acid battery - has adequately served the technological needs of a variety of industries. Other battery types, such as nickel-cadmium and nickel-metal-hydride, have also fulfilled the demands of niche products and systems. However, these battery chemistries possess low power and energy densities, inflict environmental damage, and are expensive. These concerns have driven research and development efforts toward an advanced type of battery chemistry, popularly known as lithium batteries.

Lithium is the lightest solid element and possesses the highest oxidation potential (a parameter critical for battery voltage). These attributes allow lithium batteries to offer higher power and energy densities (by almost five times) as compared to the standard, state-of-the-art lead-acid and nickel-metal-hydride batteries. However, the inclusion of lithium in a battery also poses some interesting challenges. During the last ten years, research efforts in the Electronic and Advanced Ceramics group (Metals and Ceramics division) have addressed these challenges under sponsorship of the Battery Branch of the Propulsion Directorate, at Wright-Patterson Air Force Base. The prominent challenge in achieving a safe, solid, practical, long-life lithium rechargeable battery is the electrolyte. In a lithium battery, the electrolyte resides between the anode (lithium metal or lithiated carbon) and cathode (lithiated cobalt oxide) and serves many critical functions. It must allow rapid movement of the lithium ion as the current is discharged into or drawn from an external circuit. To a large extent, the power and energy densities of a battery are determined by this property. The electrolyte must also remain mechanically, chemically, and thermally stable for the entire life of the battery. In addition, anode-electrolyte and cathode-electrolyte interfaces are active sites of electrode reactions. Ideally, these electrode reactions should be reversible, because irreversibility will lead to reduced life and fading capacity.

State-of-the-art lithium-ion batteries use a liquid, organic electrolyte. Scale-up of these liquid electrolyte lithium batteries for space, aircraft, and electric vehicle applications raises safety and cost issues. The solid polymer-ceramic composite electrolyte material developed by UDRI adequately addresses these issues.

The Electronic and Advanced Ceramics group has developed a polymer-ceramic composite electrolyte material that possesses most of the aforementioned attributes of electrolytes. The group has established an alliance with Eagle-Picher Technologies (EPT) LLC, of Joplin, Missouri to fabricate prototype composite electrolyte lithium batteries. EPT is a major producer of military and commercial aircraft batteries. The exploratory phase of the program was funded by the NASA Glenn Research Center in Cleveland. The UDRI-EPT team will continue the development of lithium batteries using solid electrolytes to satisfy the needs of space, aircraft, and electric vehicle applications under the Air Force Dual Use Science and Technology Program, a $1.5 million, three-year contract jointly sponsored by the NASA Glenn Research Center and the Air Force.

The first generation of lithium batteries is already being used in commercial products. The lithium-ion battery was introduced by Sony (Japan) in 1991 for laptop computers, cellular phones, and a variety of other electronic products. At present, the market for this product in Japan alone is $2.5 billion. Batteries developed by the UDRI-EPT team will be second-generation lithium batteries employing solid electrolytes with improved safety and cost performance.

December 1999
by Dr. Binod Kumar, Group Leader, Electronic and Advanced Ceramics