Patent Application
20150030903
The invention relates to an electrochemical cell and more particularly to a prismatic electrochemical cell having an improved bussing design and a method of manufacturing such a cell.
There are two types of prismatic cells: wound prismatic cells and stacked prismatic cells. For each design, end leads (typically made of bare foil) of the positive and negative plates are respectively attached to positive and negative bus straps provided on opposite sides of the prismatic cell with the bus straps being disposed substantially parallel to the plane of the prismatic cells. See U.S. Patent Publication No. 2012/0107668. As a result, the length of the end leads is relatively long. Since these end leads are the inactive portion of the cells, the resulting cell is inefficient, both from a performance perspective and a space perspective.
An exemplary embodiment of the invention is directed to an electrochemical cell, comprising: a prismatic electrode stack extending in a prismatic plane and having a plurality of positive electrode plates and a plurality of negative electrode plates stacked alternately with intervening separators therebetween. The positive electrode plates and the negative electrode plates are laterally offset so that end leads of the positive electrode plates extend from one side of the electrode stack and end leads of the negative electrode plates extend from an opposite side of the electrode stack. A positive bus strap is joined to the end leads of the positive electrode plates and a negative bus strap is joined to the end leads of the negative electrode plates such that said positive and negative bus straps and attaching portions of said end leads of the positive and negative electrode plates are disposed parallel to each other and perpendicular to the prismatic plane of the prismatic electrode stack. Further, a case may be provided for accommodating the prismatic electrode stack, the bus straps and liquid electrolyte.
Embodiments will be described below in more detail with reference to the accompanying drawings. The following detailed descriptions are provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein and equivalent modifications thereof. Accordingly, various changes, modifications, and equivalents of the methods, apparatuses, and/or systems described herein will be apparent to those of ordinary skill in the art. Moreover, descriptions of well-known functions and constructions may be omitted for increased clarity and conciseness.
The terms used in the description are intended to describe embodiments only, and shall by no means be restrictive. Unless clearly used otherwise, expressions in a singular from include a meaning of a plural form. In the present description, an expression such as “comprising” or “including” is intended to designate a characteristic, a number, a step, an operation, an element, a part or combinations thereof, and shall not be construed to preclude any presence or possibility of one or more other characteristics, numbers, steps, operations, elements, parts or combinations thereof.
The electrochemical cell 10 according to an embodiment of the invention is illustrated in
The end leads 20 of the positive electrode plates 14 are joined to a positive bus strap 24 and the end leads 22 of the negative electrode plates 16 are joined to a negative bus strap 26. That is, according to an exemplary embodiment, the positive and negative bus straps 24, 26 are disposed substantially parallel to each other and perpendicular to the prismatic plane of the prismatic electrode stack 12. In addition, the end leads 20, 22 are arranged such that the connection portions 21 thereof that are joined to the bus straps are parallel to the bus straps to allow them to be joined or welded to the bus straps.
As shown in
As shown in
The present invention is an improvement over the prior art in the following respects. For example, the design is simple and efficient allowing multiple electrode stacks to be electrically connected to each other with minimal manufacturing steps and minimal space. In addition, the non-active area of each electrode plate (i.e., the end leads) is minimized to thereby maximize the electrical efficiency of the cell. Other advantages of the invention would be apparent to a person of ordinary skill in the art.
The following is a description of a method of manufacturing an electrochemical cell according to the present invention.
Having obtained the prismatic electrode stack described above, a positive bus strap 24 is positioned adjacent the side edge portion of the positive electrode plate 14 and a negative bus strap 26 is positioned adjacent to the side edge portion of the negative electrode plate 16 at an orientation such that the bus straps are perpendicular to the prismatic plane.
Then, the end lead 20 of the positive electrode plate 14 is folded or curved such that a connecting portion 21 thereof is positioned parallel to and against the positive bus strap 24 and the end lead 22 of the negative electrode plate 16 is similarly folded or curved such that a connecting portion 21 thereof is positioned parallel to against the negative bus strap 26. Thereafter, the connecting portion 21 of the end lead 20 of the positive electrode plate 14 is joined or welded to the positive bus strap 24 and the connecting portion 21 of the end lead 22 of the negative electrode plate 16 is joined or welded to the negative bus strap 26.
Thereafter, the assembly, including the prismatic electrode stack and the positive and negative bus straps 24, 26, is inserted into a case. If additional electrode stacks are desired, they can be arranged parallel to each other and joined to the positive and negative bus straps in a similar manner and positioned in the case.
Although the inventive concept has been described above with respect to the various embodiments, it is noted that there can be a variety of permutations and modifications of the described features by those who are familiar with this field, without departing from the technical ideas and scope of the features, which shall be defined by the appended claims.
Further, while this specification contains many features, the features should not be construed as limitations on the scope of the disclosure or the appended claims. Certain features described in the context of separate embodiments can also be implemented in combination. Conversely, various features described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination.
