Scientists have developed a derivative of the lithium-ion cell that could prove useful in spaceflight and commercial applications in which it is planned to use oxygen batteries based on solid polymer electrolytes. This derivative cell, which contains a solid polymer electrolyte and an oxygen gas cathode, is designed for and operates best in an oxygen-rich atmosphere. (Inasmuch as the derivative cell as designed cannot store oxygen, the gas must be obtained from the environment.) Because the demand for portable electronic devices for scientific, educational, and even entertainment uses is constantly increasing, the need for rechargeable batteries as alternative means to power these devices is also increasing. Batteries based on the present derivative cell could be one such alternative means.
A unique feature of the polymer-electrolyte-based lithium cell is the way in which it utilizes (1) oxygen as an electroactive cathode (positive electrode) and (2) lithium — or another electroactive metal (e.g., magnesium, sodium, calcium, aluminum, or zinc) — as an anode (negative electrode). To implement this utilization scheme, the scientists sandwiched a lithium-ion-conductive solid polymer electrolyte film between a lithium anode and a composite carbon electrode that serves as the cathode current collector on which electroactive oxygen is reduced when the battery discharges to generate electric current. The simple design objective for these scientists was to devise a novel, solid-polymer-electrolyte-based lithium battery that could be used in spaceflight and industry.
The cathode current collector is, more specifically, made of a high-surface-area carbon (e.g., carbon black or graphite powder). In operation of the derivative cell, oxygen is reduced on the cathode collector. If lithium is the anode material, then the open-circuit potential of the cell is about 2.9 V, while the potential under load ranges between 2 and 2.9 V, depending on the load current. The theoretical specific energy of the cell is 5,200 Wh/kg — a value that makes the cell design useful, except in a vacuum, where it would be necessary to provide a self-contained supply of oxygen.
The design of the derivative cell can satisfy requirements of government and industry for rechargeable batteries that utilize oxygen gas cathodes. Because the design is experimental, anticipated cost savings cannot be surmised; however, the design holds promise and could provide another answer to the burgeoning need in the commercial marketplace and the U. S. space program for alternative forms of rechargeable batteries.
This work was done by Zhiping Jiang and Kuzhikalail Abraham of EIC Laboratories, Inc., for Johnson Space Center. For further information, access the Technical Support Package (TSP) free on-line at under the Materials category. www.nasatech.com/tsp
In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to
111 Downey Street
Norwood, MA 02062
Refer to MSC-22790, volume and number of this NASA Tech Briefs issue, and the page number.