Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Electrode
Patent
1995-04-20
1997-08-19
Maples, John S.
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Electrode
429209, H01M 438
Patent
active
056586914
DESCRIPTION:
BRIEF SUMMARY
SPECIFICATION
1. Technical Field
The present invention relates to an electrode for batteries and to a rechargeable secondary battery using the same.
2. Background Art
With wide spreading of portable devices such as video cameras and note type personal computers, compact and high capacity secondary batteries are more and more demanded. Most of the secondary batteries presently used are nickel-cadmium batteries using alkaline electrolytic solutions. However, these conventional batteries have a low battery voltage of about 1.2 V and it is difficult to promote energy density. To overcome this problem, high energy secondary batteries employing lithium metal having the poorest potential have been studied.
However, with the secondary batteries employing lithium metal as the anode, the lithium grows in the form of branches of a tree (dendrite) as a result of repetition of charging and discharging, the batteries have a danger to fire because of short circuit. Further, since lithium metal having high activity is used, the batteries are intrinsically dangerous and so problematic for personal uses. Recently, lithium ion secondary batteries employing various materials made of carbon which overcome the problem on safety and which exhibit high energy characteristic to lithium batteries were proposed. These batteries exploit the fact that the carbon material is doped with lithium ions and becomes the same potential as lithium metal so that it can be used as an anode in place of lithium metal. The batteries employing the carbon material doped with lithium ion are free from the problem of formation of dendrite and are highly safe because lithium metal is not used at all, so that they are now actively studied.
Secondary batteries employing the electrodes which utilize the doping of lithium ion to carbon material are described in, for example, Japanese Laid-open Patent Application (Kokai) Nos. 62-90863 and 62-122066. The carbon material employed in these known batteries is in the form of powder, so that a polymer binder such as Teflon or vinylidene fluoride is needed to form an electrode. However, if carbon fibers or a structure made of carbon fibers are used as the carbon material in place of the carbon powder, the electrode can be constructed without using the binder and with a small amount of carbon material. Further, in view of the chemical stability to electrolytes, structural stability to volume expansion due to the doping, and characteristics on repetition of charging and discharging, it is said that carbon fibers and structures made of carbon fibers are excellent. Secondary batteries employing such an electrode are known and described in, for example, Japanese Laid-open Patent Applications (Kokai) Nos. 60-54181 and 62-103991.
On the other hand, intercalation (or doping) in carbon materials has been studied for a long time and a number of discoveries have been accumulated. However, it used to be believed that the carbon materials in which intercalation can be attained are restricted to those highly graphitic carbon (i.e., those having high degree of crystallinity). However, it was discovered recently that intercalation can also be attained in carbon materials having low degree of crystallinity, such as baked organic materials, and such carbon materials are now more and more drawing attention.
However, about the mechanism of intercalation in carbon materials, a number of points have not been clarified and a guiding principle to look for a high performance carbon material for secondary batteries has not been established. Thus, the carbon materials are now being developed by repetition of trial and error. The policies for looking for the high performance carbon material include a policy to look for an amorphous carbon material, as well as a crystal carbon material. However, in the prior art, charging and discharging capacities of the carbon materials are insufficient, so that the capacities of the batteries employing such a carbon materials are also small accordingly.
An object of the present invention is to overcome the
REFERENCES:
patent: 5246794 (1993-09-01), Blomgren et al.
Proceedings of the Symposium on High Power, Ambient Temperature Lithium Batteries, Phoenix, AZ. The Electrochemical Society, 13 Oct. 1991, Pennington, NJ; pp. 80-89, N Imanishi et al., "The Structure and Charge-Discharge Characteristics of Mesophase-Pitch based Carbons".
Supplementary European Search Report Sep. 1995.
Ono Keizo
Saruyama Hideo
Suzuki Tatsuhiko
Tsukamoto Jun
Yamasaki Katsumi
Maples John S.
Toray Industries Inc.
LandOfFree
Electrode for battery and process for producing electrode for ba does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electrode for battery and process for producing electrode for ba, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electrode for battery and process for producing electrode for ba will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1103512