Glass sealing of electrochemical storage cell structures

#This invention relates to the production of sealed electrochemical storage cells, and, more particularly, to the glass sealing of such cells.

#Rechargeable cells are electrochemical devices for storing and retaining an electrical charge and later delivering that charge as useful power. A number of such cells are usually connected together to form a battery having specific voltage or current delivery capability. Each cell includes an anode, a cathode, and an electrolyte separating the anode and the cathode. The most familiar types of electrochemical cells utilize a solid anode and a solid cathode, with a liquid electrolyte.

#In another type of electrochemical cell, the anode and cathode are liquids, and the electrolyte is a solid ceramic material. One such electrochemical cell is the sodium-sulfur cell, which has a sodium anode, a sulfur cathode, and a solid electrolyte of beta double prime (Beta") aluminum oxide (alumina). Beta double prime aluminum oxide is formed from aluminum oxide, sodium oxide, and sometimes other oxides such as lithium oxide and magnesium oxide. The presence of the sodium permits sodium ion charge carriers to diffuse through the solid electrolyte at elevated temperatures during battery charging and discharging cycles.

#FIG. 1 is an exploded perspective view of a sectioned sodium-sulfur electrochemical storage cell;

#FIG. 2 is a perspective view of a sectioned first seal configuration for the weld ring to the housing frame;

#FIG. 3 is a perspective view of a sectioned second seal configuration for the weld ring to the housing frame;

#FIG. 1 depicts the structure of an electrochemical storage cell 20. Except for the sealing structures and techniques, the storage cell 20 is similar to that disclosed in U.S. Pat. No. 5,053,294, and complete details of materials and constructions may be found there. Only the portions relevant to the present invention will be discussed here.

#The storage cell 20 is generally of a flat, disk-like configuration. It includes a cylindrically symmetric housing frame 22, which is preferably made of alpha aluminum oxide. The housing frame 22 has an internal surface 24, an internal shoulder 26 in the internal surface 24, an external surface 28, and opposing ends 30.

#A flat plate solid electrolyte 32 is dimensioned to fit within the circumference of the housing frame 22 and to seat against one side of the internal shoulder 26. The electrolyte is preferably made of beta double prime (Beta") aluminum oxide (alumina). It is typically from about 0.015 to 0.040 inches thick. The electrolyte 32 is bonded to the shoulder 26 with a first glassy seal 33.