Prismatic cell construction

Abstract

An electrochemical cell is disclosed, having a sealed prismatic housing with two opposing, internal side surfaces defining therebetween an internal cavity having width and length. One of the side surfaces defines a convex arc, and the other of the side surfaces has a center portion opposing the convex arc of the one side surface, and features extending toward the one side surface and straddling the convex arc. An electrode stack is contained within the internal cavity of the housing, having positive and negative electrode sheets arranged in face-to-face relation. The electrode stack is arranged between the side surfaces of the housing such that the stack is retained between the one side surface and the extending features of the other side surface, and deflected to follow the convex arc to maintain contact pressure between the positive and negative electrode sheets. The stack is thus stretched across an inwardly crowned surface of the housing. The invention can, by maintaining good intersheet contact pressure within the stack, provide good overall active material utilization (for high cell capacity) and can help to inhibit housing distension of cells with broad sides. Methods of construction are also disclosed.

Description

technical field [0001] The present invention relates to prismatic electrochemical cells and housing structures thereof. Background technique [0002] The shape of electrochemical cells is generally classified as prismatic or cylindrical. As the name suggests, a cylindrical battery has a cylindrical casing. Examples of common cylindrical cells are standard alkaline cells in sizes AA, AAA, C and D. A prismatic cell has a prismatic case shape such as a parallelepiped. Examples of common prismatic batteries include standard 12-volt car batteries. [0003] Many common types of batteries have an internal electrode configuration where the electrodes are in a sheet-like configuration, where the positive and negative electrode materials are stacked together and separated by an insulating separator plate. One reason for this face-to-face plate arrangement is to create a high diffusion region between paired electrodes. [0004] Ideally, adjacent electrode sheets in an electrode st...

AI Technical Summary

Problems solved by technology

If the sides of the case are not built sufficiently to resist this applied bending moment, the above effects will be added to the effect of the internal cavity pressure and cause undesirable deformation of the overall cell shape.

Of course, their stiffness can be increased by increasing the thickness of the side walls of the case, but this usually comes at the cost of increased weight and, for a standard size battery, a loss of internal cavity volume

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