Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Electrode
Reexamination Certificate
2000-09-25
2002-09-10
Kalafut, Stephen (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Electrode
C429S211000, C429S233000
Reexamination Certificate
active
06447950
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an electrode for a battery in which an electrode tab is connected, a method of manufacturing the same, and a battery having the electrode. The present invention is characterized by a novel connection structure and a connection method of a collector and an electrode tab.
The tab referred to in the present invention is generally called a (positive electrode or negative electrode) reed, a connection reed, a (positive electrode or negative electrode) terminal or the like, and it is contacted or connected with the collector to provide electrical connection between the collector and the outside.
BACKGROUND ART
According to miniaturization and weight reduction of electronic appliances such as various OA appliances, VTR cameras, portable phones and the like in recent years, a high performance of a secondary battery used in these electronic appliances has been required. In order to meet such a requirement, the development of a lithium ion secondary battery that occludes or releases lithium as a non-aqueous electrolyte battery having a high discharge potential and a high discharge capacity has been rapidly conducted, and it has been put to practical use.
Each of electrodes, a positive electrode and a negative electrode of a non-aqueous electrolyte battery is constructed of an electrode active material layer, a collector and an electrode tab. The electrode active material layer is generally formed by mixing an active material with a binder to form an electrode coating-material (mixture), applying the same onto the collector and drying it. The tab is contacted or connected with the collector to provide electrical connection between the collector and the outside. It is ordinarily connected with the collector through welding. Further, another end of the tab is welded with an external can or cap of the battery.
For example, in a lithium ion secondary battery, an electrochemical reaction occurs in an active material layer. At this time, electricity is passed through a collector and a tab, and withdrawn to the outside or supplied from the outside. That is, at the time of charging, electricity supplied to an external can or cap is passed to the collector through the tab. From the collector, electricity is passed to the active material in the electrode active material layer, and the electrochemical reaction occurs to allow charging. At the time of discharging, the order in the charging is inverted. The chemical reaction occurs with the active material in the electrode active material layer, and electricity obtained here is passed from the collector to the tab and from the tab to the external can or cap to allow discharging.
In the lithium ion secondary battery, generally, an aluminum foil is used in a positive electrode and a copper foil in a negative electrode in the collector. Further, generally, aluminum is used in a positive electrode and nickel or the like in a negative electrode in the tab. And, an active material layer is not formed on a part of the surface of the collector, and the tab is connected with this portion through welding.
The tab and the collector are welded by a method such as spot welding, laser welding or the like. However, a large-sized welding device is required.
Moreover, as described in, for example, Japanese Laid-Open Patent Publication No. 9-213,338/1997, when a collector is formed as a thin film on a resin film or a resin sheet, it is almost impossible to weld a tab with this thin film collector.
When connection is conducted with an adhesive as a connection method other than welding, the electrical connection between the tab and the collector is extremely worsened (that is, an electrical resistance is extremely increased). Further, when the connection is conducted with a conductive paste, it is put between the tab and the collector. Accordingly, there are disadvantages that a solvent is hardly removed to make the drying difficult, a curing temperature is high, and so forth.
DISCLOSURE OF THE INVENTION
OBJECTS OF THE INVENTION
Thus, the object of the present invention is to provide, upon solving the problems of the prior art, an electrode for a battery in which a collector and an electrode tab are connected by a novel connection structure without impairing electrical connection, and a method of manufacturing the electrode quite simply. Further, another object of the present invention is to provide a battery having this electrode for the battery.
SUMMARY OF THE INVENTION
The present inventors have assiduously conducted investigations. Consequently, the inventor has focussed on the fact that graphites tend to adhere to each other when a pressure is applied thereto, and have found that a collector and a tab can be connected by applying a pressure with graphite interposed therebetween. This finding has led to the completion of the invention.
That is, the present invention is an electrode for a battery comprising an electrode active material layer, a collector and an electrode tab, the collector and the tab being connected via a graphite layer.
Further, the present invention is a method of manufacturing an electrode for a battery comprising an electrode active material layer, a collector and an electrode tab by connecting the collector with the electrode tab, which method comprises forming a graphite layer on the surface of the collector to be connected with the tab and/or the surface of the tab to be connected with the collector, overlapping the portions to be connected of the collector and the tab on each other with the graphite layer interposed between the connector and the tab, and applying a pressure to the overlapped portions of the collector and the tab to connect the collector with the tab.
The electrode and the method of manufacturing the same in the present invention can be applied to both electrodes, a positive electrode and a negative electrode.
Further, the present invention is a battery having the electrode for the battery of the present invention or the electrode for the battery obtained by the method of the present invention as a positive electrode and/or a negative electrode.
Still further, the present invention is a non-aqueous electrolyte battery having the electrode for the battery of the present invention or the electrode for the battery obtained by the method of the present invention as a positive electrode and/or a negative electrode.
REFERENCES:
patent: 5476734 (1995-12-01), Pulley et al.
patent: 57158962 (1982-09-01), None
patent: 03272565 (1991-12-01), None
patent: 04249863 (1992-09-01), None
patent: 09213338 (1997-08-01), None
Alejandro R
Kalafut Stephen
Rader & Fishman & Grauer, PLLC
TDK Corporation
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