Wound bipolar lithium polymer batteries

#The present invention relates to bipolar batteries and more particularly, to a wound bipolar design for use in bipolar lithium batteries, such as high power lithium polymer batteries.

#In lithium/metal oxide battery cells, a liquid electrolyte fills the pores in the separator and electrodes, allowing lithium ions to pass between the electrodes, carrying the current, and to interact with active material throughout the electrodes.

#In a solid-polymer-electrolyte cell, an electrolyte sheet fills the entire space between the electrodes and the polymer is blended with the electrode material to form a nearly pore-free solid cell. An advantage of this design is that the electrolyte stays in place and will not creep to parts of the cell where it is not desired causing corrosion reactions that shorten cell life. Also, the design of a bipolar battery becomes plausible with a solid electrolyte whereas liquid electrolytes bridge the edges at the periphery of bipolar plates between cells causing rapidly destructive corrosion reactions.

#The present invention together with the above and other objects and advantages may best be understood from the following detailed description of the preferred embodiments of the invention illustrated in the drawings, wherein:

#FIG. 1 is a perspective view illustrating a lithium polymer bipolar wound stack assembly in accordance with the preferred embodiment;

#FIG. 2 provides a simplified cross sectional view of the lithium polymer bipolar stack assembly of FIG. 1 in accordance with the preferred embodiment;

#In accordance with features of the invention, a lithium polymer bipolar high power battery is provided that is appropriate for applications requiring high voltage, high power, and limited capacity. Even with the new electrolytes the area-specific impedance is expected to be 50 to 75 ohm-cm2 at 20° C., two or three times higher than for cells with liquid electrolytes. Therefore, the cells must have a large area even though the capacity is limited. In accordance with features of the invention, the large cell area is accomplished by making many wrappings of thin cell layers around a core.

#Having reference now to the drawings, in FIGS. 1, 2, 3A, 3B, 3C and 3E, there is shown an exemplary lithium polymer bipolar stack assembly generally designated as 100 in accordance with the preferred embodiment. The illustrated lithium polymer bipolar stack assembly 100 includes an eight cell arrangement; however, it should be understood that the present invention is not limited to the illustrated eight cell arrangement. In accordance with features of the invention, a selected number, such as between three through fifteen, thin cells are arranged in series in a bipolar configuration by simultaneously winding many appropriately ordered layers of material around a supporting core in an elliptical cylindrical shape to form the lithium polymer bipolar stack assembly 100 for a particular application.

#As shown in FIG. 1, the wound stack assembly 100 includes a stainless steel container 102. A positive terminal 104 and a negative terminal 106 are located near opposite sides at the top of the stainless steel container 102. A plurality of elastomer bands 108 is provided around the stack container 102. A multiple pin state-of-charge connector 110, such as a 7-pin connector for the eight cell, is located near the negative terminal 106 at the top of the stainless steel container 102.