US Patent 10109844 Dual weld plug for an electrochemical cell

The present invention is directed to an electrochemical cell having plate electrodes housed inside a mating “clamshell” casing. When mated together, the casing components are form-fitting with respect to the internal battery structure so as to reduce the overall size of the electrochemical package. A header assembly containing both a glass-to-metal seal opening for a terminal lead and an electrolyte fill opening is used in conjunction with the clamshell casing. The electrolyte fill opening is constructed with an elongated opening with at least two different radii. A first and second sealing element is welded within the electrolyte fill opening at different depths within the header to block the flow of electrolyte and form a hermetic seal.