JP2000188132A - Nonaqueous electrode secondary battery - Google Patents

Nonaqueous electrode secondary battery

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Publication number
JP2000188132A
JP2000188132A JP10365035A JP36503598A JP2000188132A JP 2000188132 A JP2000188132 A JP 2000188132A JP 10365035 A JP10365035 A JP 10365035A JP 36503598 A JP36503598 A JP 36503598A JP 2000188132 A JP2000188132 A JP 2000188132A
Authority
JP
Japan
Prior art keywords
battery
lithium
secondary battery
positive electrode
non
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP10365035A
Other languages
Japanese (ja)
Inventor
Kazuhiro Nakamitsu
Toru Tabuchi
和弘 中満
田渕  徹
Original Assignee
Gs Melcotec Kk
ジ−エス・メルコテック株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Gs Melcotec Kk, ジ−エス・メルコテック株式会社 filed Critical Gs Melcotec Kk
Priority to JP10365035A priority Critical patent/JP2000188132A/en
Publication of JP2000188132A publication Critical patent/JP2000188132A/en
Application status is Pending legal-status Critical

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Classifications

    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage
    • Y02E60/12Battery technologies with an indirect contribution to GHG emissions mitigation
    • Y02E60/122Lithium-ion batteries

Abstract

[PROBLEMS] To provide a non-aqueous electrolyte secondary battery having high safety and high energy density. A battery is charged at an initial charging voltage so that an open circuit voltage of the battery after 10 minutes from stopping charging is in a range of 4.3V to 4.7V. [Effect] By performing the first charge under these conditions, the positive electrode active material is maintained in a highly oxidized state for a certain period of time, during which a portion having a high reactive point of the positive electrode active material reacts with the electrolytic solution, and the subsequent activity is increased. Control the reaction. During the initial charging under these conditions, excess lithium reacts with the electrolyte on the negative electrode surface to form a sufficient protective film, and thereafter, the reaction between the lithium and the electrolyte on the negative electrode In a non-aqueous electrolyte secondary battery, rapid heat generation of the battery can be prevented even in the event of an abnormality such as an internal short circuit, and a high energy density and improved safety of the battery can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte secondary battery having a light weight and a high energy density.

[0002]

2. Description of the Related Art In recent years, with the rapid miniaturization and diversification of portable cellular phones and portable electronic devices for consumer use, a small, lightweight, high energy density and repetitive long-term repetition has been required for batteries as power sources. There is a strong demand for the development of a rechargeable secondary battery. Non-aqueous electrolyte secondary batteries such as lithium secondary batteries and lithium ion secondary batteries are the most promising secondary batteries that satisfy these requirements, and active research is being conducted. The positive electrode active material of the nonaqueous electrolyte secondary battery includes a general formula Li such as titanium disulfide, vanadium pentoxide, lithium cobalt composite oxide such as molybdenum trioxide, lithium nickel composite oxide, and spinel type lithium manganese oxide. Various compounds represented by x MO 2 (where M is one or more transition metals) have been studied.
Among them, lithium cobalt composite oxide, lithium nickel composite oxide, spinel type lithium manganese oxide, and the like are charged and discharged at a very noble potential of 4 V (vs Li / Li + ) or more. A battery having a high discharge voltage can be realized. As the negative electrode active material of the nonaqueous electrolyte secondary battery, various types of materials such as metallic lithium and alloys containing lithium and carbon materials capable of inserting and extracting lithium have been studied. When used, there is an advantage that a battery having a long cycle life is obtained and safety is high. In the electrolyte of the nonaqueous electrolyte secondary battery, generally, a supporting salt such as LiBF 4 or LiPF 6 is used as a mixed solvent of a high dielectric constant solvent such as ethylene carbonate or propylene carbonate and a low viscosity solvent such as dimethyl carbonate or diethyl carbonate. A dissolved electrolyte is used. In such a non-aqueous electrolyte battery, there has been a great problem of preventing overcharging, overdischarging, internal short circuit, and the like due to a reduction in size and capacity, that is, a dramatic increase in volume energy density. As a measure to prevent overcharge, a method of controlling a charging voltage by a charger and a measure to prevent an overdischarge by controlling a cutoff voltage at the time of discharge have become mainstream. Also, in preparation for a failure of control of the charger or the like or the occurrence of a large current due to an internal short circuit, the battery side is provided with a safety valve and a current cut-off means that are opened when a predetermined battery internal pressure is reached. At present, examples include a method of mounting a protection circuit and a protection element, a method of utilizing thermal obstruction of a separator, and the like. However, the use of protection circuits and protection elements greatly imposes restrictions on miniaturization and cost reduction of battery packs, and the heat clogging of the separator uses the exothermic reaction at the time of non-safety. May not work effectively if the occurrence occurs rapidly.

[0003]

In general, as a measure for preventing overcharge, a method of controlling a charging voltage by a charger is adopted. However, when a charger fails, a non-aqueous electrolyte secondary battery must be used. When a predetermined amount of electricity or more is charged, the battery generates heat, and in the worst case, ignition may occur. The main cause of the unsafeness of the nonaqueous electrolyte secondary battery during overcharge is that the positive electrode active material such as lithium-containing transition metal composite oxides that occlude and release lithium and / or lithium ions is charged with lithium during overcharge. When the battery temperature reaches the critical temperature, oxygen is released from the unstable cathode active material due to the desorption, and when the battery temperature reaches the critical temperature, the oxygen and the electrolyte solvent become very A large exothermic decomposition reaction causes thermal runaway. In such a non-aqueous electrolyte secondary battery, when the power supply circuit or the charging device of the electronic device fails and becomes overcharged, or when the user performs an unusual handling, an abnormal inside the battery may occur. Heat is generated, and in extreme cases, the battery may be damaged or ignited.
Effectively suppresses heat generation so that the battery does not cause thermal runaway,
There is a demand for ensuring the safety of batteries.

[0004]

According to the present invention, there is provided a positive electrode containing a substance capable of occluding and releasing lithium and / or lithium ions, a negative electrode including a substance capable of occluding and releasing lithium and / or lithium ions, and a supporting salt. In the non-aqueous electrolyte secondary battery composed of the contained electrolyte and the first charge, the open circuit voltage of the battery after the charge is stopped is 4.3 V to 4.7.
By charging the battery in the range of V, the safety of the battery is ensured, heat generation and damage of the battery are prevented, and a battery having a high energy density and excellent discharge characteristics is provided. Here, the “first charge” means the first charge after the battery is assembled and the electrolyte is injected.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is intended to prevent the heat and damage of a non-aqueous electrolyte secondary battery by limiting initial charging conditions, thereby ensuring the safety of the battery. In the nonaqueous electrolyte secondary battery according to the present invention, the details of the mechanism for achieving the safety of the battery are not clear, but in the initial charge, the positive electrode active material is charged at a high charging voltage of 4.3 V to 4.7 V. It is considered that a portion having a high reaction active point of the positive electrode active material reacts with the electrolytic solution while the positive electrode active material is maintained for a certain period of time in the high oxidation state, thereby suppressing the active reaction thereafter. In addition, during the initial charging under the above conditions, excess lithium reacts with the electrolyte on the negative electrode surface to form a sufficient protective film, and thereafter, the reaction between lithium and the electrolyte on the negative electrode. Can be suppressed. Therefore, even when an abnormality such as an internal short circuit occurs, rapid heat generation of the battery can be prevented, and the safety of the battery can be improved. Further, under the condition of the first charge of the present invention, a more dense protective film can be formed on the negative electrode surface, and therefore, excellent discharge performance can be obtained. As the positive electrode active material of the nonaqueous electrolyte secondary battery according to the present invention, any compound can be used as long as it can absorb and release lithium and / or lithium ions. In particular, Li x MO 2 (where M Preferably represents one or more transition metals) alone or in combination of two or more.
Further, from the height of the discharge voltage, as the transition metal M, C
It is more preferable to use a transition metal selected from the group consisting of o, Ni and Mn. The negative electrode is a compound that absorbs and / or releases lithium and / or lithium ions, such as coke, glassy carbon, graphite, non-graphitizable carbon, pyrolytic carbon, carbon fiber, and metallic lithium, lithium alloy, and polyacene. Can be used alone or in combination of two or more. However, it is particularly preferable to use a carbonaceous material from the viewpoint of high safety. As the solvent of the non-aqueous electrolyte, ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, trifluoropropylene carbonate, γ-butyrolactone, sulfolane, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran,
2-methyltetrahydrofuran, 3-methyl-1,3-
Dioxolan, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, dimethyl carbonate,
Non-aqueous solvents such as diethyl carbonate, ethyl methyl carbonate, dipropyl carbonate and methyl propyl carbonate can be used alone or in a mixed solvent thereof. The non-aqueous electrolyte is used by dissolving a supporting salt in these non-aqueous solvents. As the supporting salt, LiClO
4, LiPF 6, LiBF 4, LiAsF 6, LiCF 3 C
O 2 , LiCF 3 SO 3 , LiCF 3 CF 2 SO 3 , LiCF
3 CF 2 CF 2 SO 3 , LiN (SO 2 CF 3 ) 2 , LiN
(SO 2 CF 2 CF 3 ) 2 , LiN (COCF 3 ) 2 and L
A salt such as iN (COCF 2 CF 3 ) 2 or a mixture thereof can be used.

[0006] Instead of such a liquid electrolyte, a solid ion-conductive polymer electrolyte can also be used. When the polymer electrolyte membrane is made of polyethylene oxide, polyacrylonitrile, polyethylene glycol, or a modified product thereof, it is lightweight and flexible, and is advantageous when used for a wound electrode plate. Further, the ion conductive polymer electrolyte membrane and the organic electrolyte can be used in combination. In addition to the polymer electrolyte, known electrolytes such as an inorganic solid electrolyte, a mixed material of an organic polymer electrolyte and an inorganic solid electrolyte, or an inorganic solid powder bound by an organic binder can be used as the electrolyte.

The non-aqueous electrolyte secondary battery according to the present invention is usually composed of a combination of a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte, and the separator is a porous polyvinyl chloride film. Such a porous polymer membrane or a lithium ion or ion conductive polymer electrolyte membrane can be used alone or in combination.
Furthermore, as the shape of the battery, cylindrical, square, coin type,
Various shapes such as a button type and a laminate type can be used.

EXAMPLES The present invention will be described below with reference to preferred examples, but it goes without saying that the present invention is not limited to the following examples without departing from the gist of the present invention. A prismatic nonaqueous electrolyte secondary battery according to the present invention was produced using lithium cobaltate as a positive electrode active material and a carbon material as a negative electrode active material. FIG. 1 is a diagram showing a cross-sectional structure of a prismatic nonaqueous electrolyte secondary battery according to the present invention. In FIG. 1, 1 is a non-aqueous electrolyte secondary battery,
2 is a wound electrode group, 3 is a positive electrode, 4 is a negative electrode, 5 is a separator, 6 is a battery case, 7 is a battery cover, 8 is a safety valve, 9 is a positive terminal, and 10 is a positive lead. The wound electrode group 2 is housed in a battery case 6, a safety valve 8 is provided in the battery case 6, and the battery cover 7 and the battery case 6 are sealed by laser welding. Positive electrode terminal 9 is connected to positive electrode 3 via positive electrode lead 10, and negative electrode 4 is connected to the inner wall of battery case 6 by contact. The positive electrode is LiCo as an active material.
A slurry was prepared by mixing 90 parts by weight of O 2, 5 parts by weight of acetylene black as a conductive material, and 5 parts by weight of polyvinylidene fluoride as a binder to form a positive electrode mixture, and dispersing the mixture in N-methyl-2-pyrrolidone. Was prepared. This slurry is uniformly applied to a 20 μm thick aluminum current collector,
After drying, the positive electrode 3 was produced by compression molding with a roll press. The negative electrode is made of a carbon material 9 as an active material.
A slurry was prepared by mixing 0 parts by weight and 10 parts by weight of polyvinylidene fluoride to prepare a negative electrode mixture and dispersing the mixture in N-methyl-2-pyrrolidone. The slurry was uniformly applied to a 10 μm-thick copper current collector, dried, and then compression-molded by a roll press to produce a negative electrode 4. As the separator 5, a microporous polyethylene film having a thickness of about 25 μm was used. In the electrolyte,
LiPF in a 1: 1 mixed solvent (volume ratio) of ethylene carbonate (EC) and ethyl methyl carbonate (EMC)
A non-aqueous electrolyte solution in which 6 was dissolved in 1.0 M was used. The battery thus manufactured was subjected to constant current and constant voltage charging for a total charging time of 5 hours as initial charging. As the conditions for the constant current and constant voltage charging, the constant current was set to 1 C, and the constant voltages were set to 4.3 V, 4.5 V, and 4.7 V, respectively. The open circuit voltages of the batteries immediately after the charging was stopped were 4.3 V and 4.5 V, respectively.
V and 4.7V. Thereafter, the battery was allowed to stand for 10 minutes, and the charge and discharge characteristics and safety of the battery after discharging at a constant discharge current were examined. As a comparative example, a battery prepared in the same manner as in the example was charged for the first time, and a constant current and constant voltage charge was performed for a total charging time of 5 hours. As the conditions for the constant current and constant voltage charging, the constant current was set to 1 C, and the constant voltages were set to 4.1 V and 4.9 V, respectively. After the charging was stopped, the circuit voltages of the batteries were 4.1 V and 4.9 V, respectively. Thereafter, the battery was allowed to stand for 10 minutes, and the charge and discharge characteristics and safety of the battery after discharging at a constant discharge current were examined. [Charge / Discharge Characteristics] The above battery was fully charged at 25 ° C. by constant current charging at a current of 1 C up to 4.1 V and then constant voltage charging at 4.1 V for a total of 3 hours. State. Subsequently, a discharge test was performed. In the discharge test, each battery was discharged to 2.75 V at a current of 1 C at −20 ° C., −10 ° C., 0 ° C., 25 ° C., and 45 ° C. FIG. 2 shows the discharge capacity at each temperature in the example and the comparative example. In FIG. 2, the symbol ○ indicates that the voltage of the first charge is 4.1.
V, the symbol △ is the battery with the initial charge voltage of 4.3 V, the symbol □ is the battery with the initial charge voltage of 4.5 V, the symbol ▽ is the battery with the initial charge voltage of 4.7 V, The symbol x indicates each discharge capacity of the battery whose initial charge voltage is 4.9 V. It is clear from FIG. 2 that the higher the initial charge voltage, the higher the discharge capacity at low temperatures. However, since the battery having the highest initial charge voltage of 4.9 V has a low discharge characteristic at a low temperature, the initial charge voltage is preferably in the range of 4.3 to 4.7 V in the embodiment. This is considered to be because when the initial charge is extremely high, the active material of the positive electrode is deteriorated and the discharge characteristics are deteriorated. [Nail penetration safety test]
Constant current charging was performed to a constant current of 4.5 V with a current of C, and then constant voltage charging of 4.5 V for a total of 3 hours. In the subsequent nail penetration test, for each of the 10 batteries, an iron nail having a diameter of 2.5 mm was penetrated from the side surface of each battery, and the state of the batteries thereafter was observed. Table 1 shows the results of the nail penetration safety test (Examples and Comparative Examples).

[0008]

[Table 1]

As shown in Table 1, the initial charge was 4.1 V and 4.
In the case of 9V, smoke and smoke were generated.
Those performed in the range of 3 V to 4.7 V had higher safety than others, and ignition and fumes were not recognized. From this, the first charging voltage is 4.3 V as shown in the embodiment.
It is desirable to make the range of -4.7V.

[0010]

According to the non-aqueous electrolyte secondary battery of the present invention, the initial charge is performed at a high voltage of 4.3 V to 4.7 V. By performing the initial charge under such conditions, the positive electrode active material is held in a highly oxidized state for a certain period of time, during which a portion having a high reaction active point of the positive electrode active material reacts with the electrolytic solution,
It is considered that the active reaction thereafter is suppressed. In addition, during the initial charging under such conditions, excess lithium reacts with the electrolyte on the negative electrode surface to form a sufficient protective film, and thereafter lithium on the negative electrode and the electrolyte are mixed with each other. Reaction can be suppressed. As a result, in the non-aqueous electrolyte secondary battery according to the present invention, it is possible to prevent rapid heat generation of the battery even at the time of abnormality such as an internal short circuit, and to improve the safety of the battery at a high energy density. Become.
Therefore, the industrial value of the present invention is extremely high.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross-sectional structure of a prismatic battery of an example of the present invention and a comparative example.

FIG. 2 is a diagram showing the discharge capacity at each temperature of the batteries of Examples and Comparative Examples of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Non-aqueous electrolyte secondary battery 2 Electrode group 3 Positive electrode plate 4 Negative electrode plate 5 Separator 6 Case 7 Lid 8 Safety valve 9 Positive electrode terminal 10 Positive electrode lead

Claims (1)

    [Claims]
  1. A positive electrode containing a compound capable of occluding and releasing lithium or / and lithium ions, and lithium or / and / or lithium ions.
    And a negative electrode containing a compound that occludes and releases lithium ions, and an electrolyte, wherein the open circuit voltage of the battery is 4.3 to 4.7 V 10 minutes after the initial charging is stopped. Electrolyte secondary battery.
JP10365035A 1998-12-22 1998-12-22 Nonaqueous electrode secondary battery Pending JP2000188132A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP10365035A JP2000188132A (en) 1998-12-22 1998-12-22 Nonaqueous electrode secondary battery

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP10365035A JP2000188132A (en) 1998-12-22 1998-12-22 Nonaqueous electrode secondary battery

Publications (1)

Publication Number Publication Date
JP2000188132A true JP2000188132A (en) 2000-07-04

Family

ID=18483280

Family Applications (1)

Application Number Title Priority Date Filing Date
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Country Status (1)

Country Link
JP (1) JP2000188132A (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003007342A (en) * 2001-06-25 2003-01-10 Hitachi Maxell Ltd Manufacturing method of secondary nonaqueous battery
US7071653B2 (en) * 2003-05-30 2006-07-04 Matsushita Electric Industrial Co., Ltd. Method for charging a non-aqueous electrolyte secondary battery and charger therefor
WO2006123572A1 (en) * 2005-05-17 2006-11-23 Sony Corporation Positive electrode active material and process for producing the same, and battery
KR101354342B1 (en) 2005-04-04 2014-01-22 소니 주식회사 Battery
US9054374B2 (en) 2005-05-17 2015-06-09 Sony Corporation Cathode active material, method of manufacturing the same and battery

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003007342A (en) * 2001-06-25 2003-01-10 Hitachi Maxell Ltd Manufacturing method of secondary nonaqueous battery
US7071653B2 (en) * 2003-05-30 2006-07-04 Matsushita Electric Industrial Co., Ltd. Method for charging a non-aqueous electrolyte secondary battery and charger therefor
KR101354342B1 (en) 2005-04-04 2014-01-22 소니 주식회사 Battery
WO2006123572A1 (en) * 2005-05-17 2006-11-23 Sony Corporation Positive electrode active material and process for producing the same, and battery
CN104064729A (en) * 2005-05-17 2014-09-24 索尼株式会社 Positive Electrode Active Material And Process For Producing The Same, And Battery
US9054374B2 (en) 2005-05-17 2015-06-09 Sony Corporation Cathode active material, method of manufacturing the same and battery

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