Chemistry: electrical current producing apparatus – product – and – With nonbattery electrical component electrically connected...
Patent
1998-10-23
2000-09-12
Nuzzolillo, Maria
Chemistry: electrical current producing apparatus, product, and
With nonbattery electrical component electrically connected...
429163, 429 96, 429100, H01M 1400, H01M 200, H01M 1046
Patent
active
061175765
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to battery devices. More particularly, the invention relates to a battery device including a lithium ion battery and a protection circuit board.
PRIOR ARTS
There is a demand toward reducing the size and weight of power batteries due to recent size and weight reductions in electronic appliances, including handy phones. In order to meet such a demand, a secondary battery (may be hereinafter called merely "lithium ion battery") has been developed that utilizes for its negative pole a material capable of being doped with and/or de-doped of lithium or lithium ions. This lithium ion battery, which is high in power voltage and light in weight with suppressed self-discharge characteristics, has being placed into practical applications.
The secondary battery of this kind, however, has a characteristic that its electrode member experiences repeated expansion and contraction during charge and discharge of electricity. Under such a situation, various considerations have been made so far, as to how is solved the technical problem caused by expansion and contraction in the electrode material.
For example, there is a proposal in Japanese Patent Laying-open No. H7-134984 [H01M 4/02, 4/58, 10/40] laid open to public on May 23, 1996, wherein a cylindrical secondary battery is structured by an electrode body in a spiral form so that the pressure exerted between the positive and negative electrodes are moderated even where thermal expansion in volume is caused in the electrode material to a full extent. Meanwhile, Japanese Patent Laying-open No. H7-220754 [10/38, 10/38] laid open to public on Aug. 18, 1996 proposes that an electrode body is structured by a layered body bundled by a thermally-contractable tube to absorb volumetric expansion caused upon electricity charging and discharging, thereby preventing the layered body from being deformed. The latter prior art further includes a resilient ring between the vessel and the lid or a corrugated portion in the vessel itself so that the electrode body is allowed to expand and contract, thus maintaining the form of the layered body.
In this manner, various proposals have been made in order to maintain the electrode body structure in a manner free from effects of expansion and contraction of the electrode body.
Meanwhile, the lithium ion batteries as above often have a protection circuit to suppress the battery from going into overworking. Such a protection circuit is usually arranged directly on the battery as shown in FIG. 1 due to the requirement to reduce the size and weight of the above-mentioned electronic appliances, thus achieving space savings.
There is shown in FIG. 1 a prior art battery device 1, which includes a lithium ion battery 12 having a layered body (not shown) in a flattened cylindrical form. This lithium ion battery 12 has a positive pole lead 14 exposed in a top surface and a negative pole lead 16 exposed in a bottom surface. A circuit board 20 built with a protection circuit 18 is arranged in contact with a side surface of the battery 12. The circuit board 20 has connection strips 2 and 4 electrically connected to the protection circuit 18. These connection strips 2 and 4 are formed, for example, by nickel thin sheets and electrically connected respectively to the positive pole lead 14 and the negative pole lead 16.
In the battery device 1 of FIG. 1, the use of the lithium ion battery 1 results in repeated expansion and contraction in the layered body (not shown), as stated before. There is, however, no expansion and contraction in the circuit board 20 and the connection strips 2 and 4. As a result, stresses are applied to these parts. If such stresses be applied to structurally weak portions, such as the points fixing connection strips 2 and 4 on the circuit board 20, or to the circuit board 20 itself, there may be cases that cracks occur in circuit parts such as the protection circuit 18 or the circuit board 20.
Under such situations, conventionally various improvements have been tried in order to increase
REFERENCES:
patent: 5472804 (1995-12-01), Austin et al.
Martin Angela J.
Nuzzolillo Maria
Rohm & Co., Ltd.
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