Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Electrode
Reexamination Certificate
2001-10-16
2004-10-12
Ryan, Patrick (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Electrode
C429S231800, C429S231950
Reexamination Certificate
active
06803149
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a non-aqueous electrolytic solution secondary battery, and in particular relates to a non-aqueous electrolytic solution secondary battery where an electrode group having a positive electrode, a negative electrode and a separator, connecting portions which connect to respective terminals from the electrode group, and a non-aqueous electrolytic solution are accommodated in a battery container provided with an internal pressure releasing mechanism which releases internal pressure at a predetermined pressure and where the positive electrode is constituted by applying a positive electrode active material mixture including lithium-manganese complex oxide and conductive material on both surfaces of a foil-shaped positive electrode collector, and the negative electrode is constituted by applying a negative electrode active material mixture including carbon material on both surfaces of a foil-shaped negative electrode collector.
DESCRIPTION OF THE RELATED ART
Because a non-aqueous electrolytic solution secondary battery represented by a lithium-ion secondary battery has a high energy density as its merit, it is mainly used as a power source or power supply for portable equipment such as a VTR camera, a notebook type personal computer, a portable or cellar telephone or the like. The interior structure of this battery is generally of a winding type as described below. Each of a positive electrode and a negative electrode of the battery is formed in a strip-shape where active material is applied to a metal foil, and a winding group is spirally formed by winding the positive electrode and the negative electrode through a separator so as not to come in direct contact with each other. This winding group is accommodated in a cylindrical battery container or can, and, after the battery container is filled with electrolytic solution, it is sealed.
An ordinary cylindrical lithium-ion secondary battery has an external dimension of a diameter of 18 mm and a height of 65 mm, which is called 18650 type, and it is widely spread as a small-sized non-aqueous electrolytic solution secondary battery for a civilian use. Lithium cobaltate having a high capacity and a long life is mainly used as a positive electrode active material for the 18650 type lithium-ion secondary battery, and battery capacity of the 18650 type lithium-ion secondary battery is approximately 1.3 Ah to 1.7 Ah and battery power (output) is about 10 W or so.
Meanwhile, in order to cope with the environmental problems in the automotive industry, development of electric vehicle (EVs) whose power sources are confined completely to batteries so that there is no gas exhausting and development of hybrid electric vehicles (HEVs) where both internal combustion engines and batteries are used as their power sources have been facilitated and some of them have reached a practical state. Such a battery which is a power source for EV or HEV is required to have high power and high energy characteristics, and an attention is being paid to a lithium-ion battery as a battery which meets such requirements.
In order to spread these EVs and HEVs, it is essential to reduce the cost of such a battery. For this reason, it is required to use low-cost battery materials, where, in a case of a positive electrode active material, for example, a special attention is being paid to manganese oxides which are rich as natural resources and improvement of such batteries has been conducted for high performance thereof. Also, as the batteries for the EVs and HEVs, not only high capacity but also high power which affects acceleration of a vehicle, namely reduction of the internal resistance of the battery, are required. In order to increase the reaction area of the electrode, this requirement can be met by utilizing a lithium manganate having a large specific surface area as the positive electrode active material.
However, in a case of the lithium-ion battery, according to an increase in capacity and power, the safety is apt to lower. Particularly, as mentioned above, in the case that lithium manganate aiming at high power is used, such a tendency appears that a phenomenon of the battery becomes violent when it falls in an abnormal state. In a battery having high capacity and high power such as used for a power source for EV or HEV, since large current charging and large current discharging are performed, it is substantially difficult to provide within the battery a current shutting-off mechanism (a kind of a cutting-off switch) which actuates according to an increase in internal pressure at an abnormal time, such as employed in the 18650 type lithium-ion battery.
Also, in a case in which a large-sized non-aqueous electrolytic solution secondary battery is used as, for example, a power source for EV or HEV, safety must always be secured even at an abnormal time such as (1) at a time of overcharging due to failure in a charging control system, (2) at a time of crushing due to an accidental collision, (3) at a time of foreign matter spitting, (4) at a time of external short-circuiting or the like. That is, it is an important problem that behavior of the battery, when it has fallen into an abnormal state (at the abnormal time), does not injure a person or passenger and damage to a vehicle is suppressed to a minimum.
SUMMARY OF THE INVENTION
In view of the above circumstances, a first object of the present invention is to provide a non-aqueous electrolytic solution secondary battery which has high safety while maintaining high capacity and high power. Also, a second object of the present invention is to provide a non-aqueous electrolytic solution secondary battery which can secure safety even at an abnormal time of the battery.
In order to achieve the first object, according to a first aspect of the present invention, there is provided a non-aqueous electrolytic solution secondary battery where an electrode group having a positive electrode, a negative electrode and a separator, connecting portions which connect to respective terminals from the electrode group, and a non-aqueous electrolytic solution are accommodated in a battery container provided with an internal pressure releasing mechanism which releases internal pressure at a predetermined pressure and where the positive electrode is constituted by applying a positive electrode active material mixture including lithium-manganese complex oxide and conductive material on both surfaces of a foil-shaped positive electrode collector, and the negative electrode is constituted by applying a negative electrode active material mixture including carbon material on both surfaces of a foil-shaped negative electrode collector, wherein the lithium-manganese complex oxide is set such that an amount of elution of manganese into the non-aqueous electrolytic solution is 5% or less on the basis of the lithium-manganese complex oxide in a range where an electrode potential to metal lithium is 4.8 V or more, and the carbon material is graphite in/from which lithium ions can be occluded/released according to charging/discharging.
Also, in order to the first object, according to a second aspect of the present invention, there is provided a non-aqueous electrolytic solution secondary battery where an electrode group having a positive electrode, a negative electrode and a separator, connecting portions which connect to respective terminals from the electrode group, and a non-aqueous electrolytic solution are accommodated in a battery container provided with an internal pressure releasing mechanism which releases internal pressure at a predetermined pressure and where the positive electrode is constituted by applying a positive electrode active material mixture including lithium-manganese complex oxide and conductive material on both surfaces of a foil-shaped positive electrode collector, and the negative electrode is constituted by applying a negative electrode active material mixture including carbon material on both surfaces of a foil-shaped negative electrode collector, wherein the lithiu
Hironaka Kensuke
Koishikawa Yoshimasa
Nakai Kenji
Yagi Youshin
Mercado Julian
Oliff & Berridg,e PLC
Shin-Kobe Electric Machinery Co. Ltd.
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