JPH10144353A - Lithium secondary battery - Google Patents
Lithium secondary batteryInfo
- Publication number
- JPH10144353A JPH10144353A JP8305264A JP30526496A JPH10144353A JP H10144353 A JPH10144353 A JP H10144353A JP 8305264 A JP8305264 A JP 8305264A JP 30526496 A JP30526496 A JP 30526496A JP H10144353 A JPH10144353 A JP H10144353A
- Authority
- JP
- Japan
- Prior art keywords
- ptc element
- positive electrode
- lithium secondary
- secondary battery
- battery
- 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.)
- Withdrawn
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Classifications
-
- Y—GENERAL 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Secondary Cells (AREA)
- Connection Of Batteries Or Terminals (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、電池の出力低下が
小さく、安定した放電特性が得られ、過放電や過充電に
よる電池内部の温度上昇などの異常時に電流を適正値に
制御する安全機構を備えたリチウム二次電池に関するも
のである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety mechanism for controlling a current to an appropriate value in the event of an abnormality such as a decrease in battery output, a stable discharge characteristic, and an increase in temperature inside the battery due to overdischarge or overcharge. The present invention relates to a lithium secondary battery provided with:
【０００２】[0002]
【従来の技術】近年、パーソナルコンピュータ、ビデオ
カメラのポータブル化や携帯電話などの小型通信機が普
及するにつれて、これらの機器の電源となる電池に対し
て高性能化と信頼性の向上が求められるようになってき
ており、このような機器電源用の電池としてはエネルギ
ー密度の大きなリチウム二次電池が代表的である。2. Description of the Related Art In recent years, as personal computers and video cameras have become portable and small-sized communication devices such as portable telephones have become widespread, batteries for powering these devices are required to have higher performance and higher reliability. As such a battery for powering an apparatus, a lithium secondary battery having a large energy density is typical.
【０００３】現在、リチウム二次電池には取り扱い者の
不注意による外部電極の短絡による過放電による発火事
故、あるいは充電時の充電装置の故障や急速充電を正し
く行わなかったことによって、電池に過大電圧、過大充
電電流、逆接続電圧がかかり、電池内部の温度が上昇し
て電池が破裂するといった事故を防止するために、バイ
メタル式サーマルプロテクタ、あるいはPTC素子が限流
のための安全機構として装着されている。[0003] At present, lithium secondary batteries are overcharged due to fire accidents due to overdischarge due to short-circuiting of the external electrodes due to carelessness of the operator, or failure of the charging device during charging or improper rapid charging. A bimetal thermal protector or a PTC element is installed as a safety mechanism for current limiting to prevent accidents such as voltage, overcharge current, reverse connection voltage applied, battery internal temperature rise and battery explosion. Have been.
【０００４】このうち、PTC素子は、ある温度で急激に
抵抗値が増大して電流を抑制する抵抗体素子であり、従
来から、チタン酸バリウム(BaTiO3)に代表されるPTCセ
ラミック素子が知られているが、PTC素子のリチウム二
次電池への装着については、例えば(株)レイケムからPo
lyswitch(登録商標)ポリスイッチの名前で知られる導電
性ポリマーを用いた過電流及び加熱保護素子が主に用い
られている。Among these, the PTC element is a resistor element whose resistance value rapidly increases at a certain temperature to suppress the current, and a PTC ceramic element represented by barium titanate (BaTiO 3 ) is conventionally known. However, the mounting of the PTC element to the lithium secondary battery has been reported by Raychem Co., Ltd.
Overcurrent and thermal protection devices using conductive polymers known by the name lyswitch® polyswitch are mainly used.
【０００５】このようなPTC素子は、過電流や過大充電
電流などによって電池温度が上昇した異常状態では抵抗
値が大きくなって電流を制限し、異常が取り除かれた場
合には通常の抵抗値に戻るという特性を示し、バイメタ
ルサーマルプロテクタと比較すると、接点がなく、構造
が単純な固体素子であることから、小型化が可能であ
り、機械的動作を伴わないことから信頼性に優れるとい
う利点を有している。In such a PTC element, the resistance value increases in an abnormal state in which the battery temperature rises due to an overcurrent or an excessively large charging current to limit the current, and when the abnormality is removed, the PTC element returns to a normal resistance value. Compared to a bimetal thermal protector, it has the advantage that it has no contacts, is a solid structure with a simple structure, can be miniaturized, and has excellent reliability because it does not involve mechanical operation. Have.
【０００６】[0006]
【発明が解決しようとする課題】しかしながら、このよ
うな従来のPTC素子においては室温での抵抗率が約1Ω・c
mと大きいために、電池の内部抵抗が大きくなり、出力
損失が生じて放電特性を低下させ、電池寿命を短くする
という問題があった。また、従来のPTC素子において
は、素子の抵抗が上昇する転移温度が100℃〜140℃であ
るために、安全性に対して作動温度が高いという問題が
あった。さらに、従来のPTC素子を大型電池に装着する
と、素子の大面積化により素子内部での電流集中が起こ
り易く、これにより発熱が生じるために大型電池への装
着が困難であるという問題があった。However, such a conventional PTC element has a resistivity at room temperature of about 1Ω · c.
Because of the large m, the internal resistance of the battery increases, causing output loss, deteriorating discharge characteristics, and shortening the battery life. Further, in the conventional PTC element, since the transition temperature at which the resistance of the element increases is 100 ° C. to 140 ° C., there is a problem that the operating temperature is high for safety. Furthermore, when a conventional PTC element is mounted on a large battery, there is a problem that current concentration tends to occur inside the element due to an increase in the area of the element, thereby generating heat and making it difficult to mount the PTC element on a large battery. .
【０００７】[0007]
【課題を解決するための手段】本発明はこのような従来
技術の問題点に鑑みてなされたものであり、本発明によ
れば、リチウム(Li)、コバルト(Co)を主成分とする複合
金属酸化物を正極活物質とし、炭素質材料を負極活物質
とするリチウム二次電池において、酸化バナジウム(V2O
3)を主成分とし、酸化バナジウム(V2O3)のモル量に対し
て、クロム(Cr)含有量が0.5mol％以上1.0mol％以下であ
る組成を有する酸化バナジウム系PTC素子を装着したこ
とを特徴とするリチウム二次電池、が提供される。SUMMARY OF THE INVENTION The present invention has been made in view of such problems of the prior art, and according to the present invention, there is provided a composite comprising lithium (Li) and cobalt (Co) as main components. In a lithium secondary battery using a metal oxide as a positive electrode active material and a carbonaceous material as a negative electrode active material, vanadium oxide (V 2 O
3 ) A vanadium oxide-based PTC element having a composition in which chromium (Cr) content is 0.5 mol% or more and 1.0 mol% or less with respect to the molar amount of vanadium oxide (V 2 O 3 ) is mounted. A lithium secondary battery is provided.
【０００８】また、本発明に係わるリチウム二次電池に
用いるPTC素子としては、上記基本組成に対する任意成
分として、酸化バナジウム(V2O3)と酸化クロム(Cr2O3)
の合計した重量に対して、タングステン(W)を5wt％以
下、好ましくは5wt％であり、さらに、鉄(Fe)を1wt％以
下添加した組成を有することが好ましい。Further, as a PTC element used in the lithium secondary battery according to the present invention, vanadium oxide (V 2 O 3 ) and chromium oxide (Cr 2 O 3 )
It is preferable that the composition has a composition in which tungsten (W) is 5 wt% or less, preferably 5 wt%, and iron (Fe) is added in an amount of 1 wt% or less based on the total weight of
【０００９】[0009]
【発明の実施の形態】本発明のリチウム二次電池は、酸
化バナジウム(V2O3)を主成分とし、酸化バナジウム(V2O
3)のモル量に対して、クロム(Cr)含有量が0.5mol％以上
1.0mol％以下、酸化バナジウム(V2O3)と酸化クロム(Cr2
O3)の合計した重量に対して、任意成分として、タング
ステン(W)を5wt％以下、好ましくは約5wt％であり、さ
らに、鉄(Fe)を1wt％以下添加した組成を有する酸化バ
ナジウム系PTC素子を装着することを特徴とする。The lithium secondary battery of the embodiment of the present invention is vanadium oxide and (V 2 O 3) as a main component, vanadium oxide (V 2 O
3 ) The chromium (Cr) content is 0.5 mol% or more based on the molar amount of 3 ).
1.0 mol% or less, vanadium oxide (V 2 O 3 ) and chromium oxide (Cr 2
O 3 ), based on the total weight of the vanadium oxide-based composition having a composition in which tungsten (W) is 5 wt% or less, preferably about 5 wt%, and iron (Fe) is added in an amount of 1 wt% or less as an optional component. It is characterized by mounting a PTC element.
【００１０】このようなPTC素子を用いることにより、
電池の出力低下が小さく、放電特性が安定し、抵抗率の
転移温度が80℃〜100℃を示し、過放電や過充電による
電池内部の温度上昇などの異常時に電流を適正値に制御
する安全性及び信頼性の高いリチウム二次電池を得るこ
とができる。また、本発明のPTC素子を大型電池に装着
しても素子内に電流集中が起きず、発熱を生じないた
め、小型から大型電池まで装着することができる。[0010] By using such a PTC element,
Battery output drop is small, discharge characteristics are stable, resistivity transition temperature is 80 ° C to 100 ° C, and current is controlled to an appropriate value when abnormalities such as temperature rise inside battery due to overdischarge or overcharge. A highly reliable and reliable lithium secondary battery can be obtained. Further, even if the PTC element of the present invention is mounted on a large battery, current concentration does not occur in the element and no heat is generated, so that a small to large battery can be mounted.
【００１１】バナジウム酸化物(VO2、V2O5、V2O3)を主
成分としたPTC素子は、V-O系での半導体と金属の間の相
転移によってPTC特性を示すものであり、素材の作製方
法としては、一般的な試薬である五酸化バナジウム(V2O
5)を原料として、五酸化バナジウム(V2O5)の一部又は全
量を酸素分圧を制御した還元雰囲気で焼成することで二
酸化バナジウム(VO2)又は酸化バナジウム(V2O3)を得る
ことができる。こうした素子は、PTC特性を示す特定温
度用のセンサーや赤外線検出、あるいは温度警報などに
使用されている。A PTC element containing vanadium oxide (VO 2 , V 2 O 5 , V 2 O 3 ) as a main component exhibits PTC characteristics due to a phase transition between a semiconductor and a metal in the VO system. As a method for producing the material, vanadium pentoxide (V 2 O
5 ) as a raw material, vanadium pentoxide (VO 2 ) or vanadium oxide (V 2 O 3 ) by firing part or all of vanadium pentoxide (V 2 O 5 ) in a reducing atmosphere with controlled oxygen partial pressure. Obtainable. Such elements are used for sensors for specific temperatures indicating PTC characteristics, infrared detection, or temperature alarms.
【００１２】しかしながら、これまでに明らかとなって
いる酸化バナジウム系PTC素子組成では、例えば、特開
平４−３５００１号公報に開示されているように、室温
での抵抗率が小さくとも2.6mΩ・cm以上、転移温度が110
℃以上、抵抗増加率は大きくとも60倍程度であったこと
から、リチウム二次電池などの小さい抵抗値と大きな抵
抗増加率を必要とするPTC素子として用いることは困難
であった。また、素子の抵抗率が上昇する転移温度が11
0℃以上を示し、リチウム二次電池に用いるには作動温
度が高かった。また、特公平５−６４８４３号公報に
は、室温抵抗率1.5mΩ・cm、抵抗率変化120倍の酸化バナ
ジウム系PTC素子が開示されており、室温抵抗値として
は十分に小さい値であるが、抵抗増加率が小さく、リチ
ウム二次電池への装着には困難があった。However, in the vanadium oxide-based PTC element composition which has been clarified so far, for example, as disclosed in JP-A-4-35001, the resistivity at room temperature is as small as 2.6 mΩ · cm. The transition temperature is 110
Since the resistance increase rate was about 60 ° C. or more at most, it was difficult to use as a PTC element requiring a small resistance value and a large resistance increase rate such as a lithium secondary battery. The transition temperature at which the resistivity of the element increases is 11
The temperature was higher than 0 ° C., and the operating temperature was high for use in a lithium secondary battery. In addition, Japanese Patent Publication No. 5-64843 discloses a vanadium oxide-based PTC element having a room temperature resistivity of 1.5 mΩ · cm and a resistivity change of 120 times, and has a sufficiently small room temperature resistance value. The rate of increase in resistance was small, and it was difficult to mount it on a lithium secondary battery.
【００１３】本発明者は、この問題を解決するために、
まず、酸化バナジウム(V2O3)を主成分とするPTC素子の
組成の探索に当たって、電池を搭載する機器の使用温度
を考慮した。即ち、電子機器の一般的な作動温度である
ー30℃から60℃において、低い抵抗率を維持し、この温
度範囲上限の80℃以上で抵抗率変化が現れるような転移
点を有し、しかも500倍以上の抵抗率変化を有する組成
範囲のものがリチウム二次電池への装着に好ましいと考
えた。The present inventor has sought to solve this problem.
First, in searching for the composition of a PTC element containing vanadium oxide (V 2 O 3 ) as a main component, the operating temperature of equipment equipped with a battery was considered. That is, at a general operating temperature of electronic equipment of −30 ° C. to 60 ° C., a low resistivity is maintained, and a transition point at which a change in resistivity appears at 80 ° C. or more, which is the upper limit of this temperature range, and It was considered that a composition range having a resistivity change of 500 times or more is preferable for mounting on a lithium secondary battery.
【００１４】本発明者は、そこで上記の設定特性を有す
る材料の組成探索を行い、添加物としてクロム(Cr)、タ
ングステン(W)及び鉄(Fe)を加えることによって、詳し
くは、酸化バナジウム(V2O3)を主成分とし、酸化バナジ
ウム(V2O3)のモル量に対して、クロム(Cr)含有量が0.5m
ol％以上1.0mol％以下添加した組成を基本組成とし、好
ましくは、該基本組成に対する任意成分として、酸化バ
ナジウム(V2O3)と酸化クロム(Cr2O3)の合計した重量に
対して、タングステン(W)の添加量が5wt％以下、好まし
くは5wt％であり、さらに、鉄(Fe)の添加量が1wt％以下
である組成を有するPTC材料が、室温抵抗率が1〜2mΩ・c
m、転移温度が80〜100℃、抵抗率変化が500倍のPTC特性
を示すことを見い出し、本発明に到達した。The present inventor has conducted a search for the composition of a material having the above-mentioned set characteristics, and added chromium (Cr), tungsten (W) and iron (Fe) as additives, specifically, vanadium oxide ( V 2 O 3 ) as a main component, and the chromium (Cr) content is 0.5 m with respect to the molar amount of vanadium oxide (V 2 O 3 ).
ol% or more and 1.0 mol% or less as a basic composition, and preferably, as an optional component to the basic composition, based on the total weight of vanadium oxide (V 2 O 3 ) and chromium oxide (Cr 2 O 3 ). In addition, a PTC material having a composition in which the addition amount of tungsten (W) is 5 wt% or less, preferably 5 wt% and the addition amount of iron (Fe) is 1 wt% or less has a room temperature resistivity of 1 to 2 mΩ. c
m, a transition temperature of 80 to 100 ° C., and a change in resistivity of 500 times show PTC characteristics.
【００１５】ここで、酸化バナジウム(V2O3)に対する、
添加物としてのクロム(Cr)含有量は0.5mol％以上1.0mol
％以下が好ましい。これは、クロム(Cr)を添加すると、
クロム(Cr)含有量の増大に伴って抵抗率変化が大きくな
る一方で転移温度が低下する傾向が認められ、0.5mol％
未満では抵抗率変化が200倍以下であり、1.0mol％超で
は転移温度が50℃以下となって実用に適さなくなること
による。Here, for vanadium oxide (V 2 O 3 ),
Chromium (Cr) content as additive is 0.5mol% or more and 1.0mol
% Or less is preferable. This is because when chromium (Cr) is added,
As the chromium (Cr) content increases, the change in resistivity increases, while the transition temperature tends to decrease.
If it is less than 200, the change in resistivity is 200 times or less, and if it exceeds 1.0 mol%, the transition temperature becomes 50 ° C or less, which makes it unsuitable for practical use.
【００１６】また、酸化バナジウム(V2O3)の重量に対す
るタングステン(W)の添加量は5wt％以下とすることが好
ましく、約5wt％とすることがより好ましい。これは、
タングステン(W)の添加量の増加に伴って粒成長が抑制
され、特に5wt％の時に焼結体の開気孔率が0.4％と最も
小さくなり、平均粒径も5μｍ程度に抑制されること
で、研磨加工時の脱粒現象を防止でき、機械的強度の大
きな素子が得られるためである。これに対し、さらにタ
ングステン(W)の添加量を増加させた場合には、例え
ば、15wt％の添加で、開気孔率は1.8％まで増大すると
ともに、抵抗変化率の低下が生じたことからも、上記組
成が好ましいと判断される。The amount of tungsten (W) added to the weight of vanadium oxide (V 2 O 3 ) is preferably 5 wt% or less, more preferably about 5 wt%. this is,
As the amount of tungsten (W) added increases, grain growth is suppressed. Especially when the content is 5 wt%, the open porosity of the sintered body becomes the smallest at 0.4%, and the average grain size is also suppressed to about 5 μm. This is because it is possible to prevent the shedding phenomenon during the polishing process, and to obtain an element having high mechanical strength. On the other hand, when the addition amount of tungsten (W) is further increased, for example, the addition of 15 wt% increases the open porosity to 1.8% and also decreases the resistance change rate. It is determined that the above composition is preferable.
【００１７】次に、酸化バナジウム(V2O3)の重量に対す
る鉄(Fe)の添加量は1wt％以下が好ましい。これは、鉄
(Fe)が1wt％超では鉄(Fe)添加量の増大に伴って室温抵
抗率が増加し、抵抗変化率も小さくなり、さらには、粒
成長が促進され、例えば5wt％以上では粒径が20μｍに
達して研磨加工時に脱粒現象が生じて本発明におけるPT
C素子として必要な構造的特性を満たさなくなることに
よる。Next, the amount of iron (Fe) added to the weight of vanadium oxide (V 2 O 3 ) is preferably 1 wt% or less. This is iron
If (Fe) exceeds 1 wt%, the room temperature resistivity increases with an increase in the amount of iron (Fe) added, the resistance change rate decreases, and furthermore, grain growth is promoted. When the particle diameter reaches 20 μm, a grain drop phenomenon occurs during polishing, and the PT
This is because the structural characteristics required for the C element cannot be satisfied.
【００１８】こうして得られた素材を用いて作製したPT
C素子は、従来からの素材の約1Ω・cmの1/1000に当たる1
mΩ・cmという低抵抗率を有することから、これをリチウ
ム二次電池に装着することで、内部抵抗が小さく出力損
失が小さい特性を有し、放電安定性に優れ、かつ約500
倍という抵抗率変化特性を示す。このため、本発明のリ
チウム二次電池の電極が外部短絡した場合、過放電及び
充電時の過大充電電流を防止でき、極めて信頼性が高
い。また、素子の抵抗率が上昇する転移温度が80℃〜10
0℃と従来のPTC素子と比べて低いために、電池内部の温
度上昇に速やかに応答し、極めて安全性が高い。The PT produced using the material thus obtained
C element is equivalent to 1/1000 of the conventional material of about 1Ωcm 1
Since it has a low resistivity of mΩcm, by mounting it on a lithium secondary battery, it has the characteristics of low internal resistance and low output loss, excellent discharge stability, and about 500
It shows a resistivity change characteristic of twice. For this reason, when the electrode of the lithium secondary battery of the present invention is short-circuited externally, an excessive discharge current during overdischarge and charging can be prevented, and the reliability is extremely high. In addition, the transition temperature at which the resistivity of the element increases is 80 ° C to 10 ° C.
Since the temperature is 0 ° C, which is lower than that of the conventional PTC element, it responds quickly to the temperature rise inside the battery and is extremely safe.
【００１９】リチウム二次電池は、図1に示されるよう
に、正極板１と、負極３と負極リード２を一体とした負
極板とをセパレータ４を介して捲回したものを金属製の
ケース１２に挿入し、電解液を充填して、絶縁板１１と
ガスケット１０によって負極板の正極リード５への接触
を防止しながら、正極リード５をPTC素子９を介して正
極端子８に取り付けて密閉された構造を有しており、PT
C素子９として上記のPTC素子を装着して本発明が構成さ
れる。なお、図１において、６は防爆弁、７は排気孔、
１３は捲回された電極とケース１２を隔離する絶縁板を
示す。As shown in FIG. 1, a lithium secondary battery is formed by winding a positive electrode plate 1 and a negative electrode plate having a negative electrode 3 and a negative electrode lead 2 integrally with a separator 4 interposed therebetween. 12 and filled with an electrolytic solution. The positive electrode lead 5 is attached to the positive electrode terminal 8 via the PTC element 9 and sealed while preventing the negative electrode plate from contacting the positive electrode lead 5 by the insulating plate 11 and the gasket 10. The structure is
The present invention is configured by mounting the above-mentioned PTC element as the C element 9. In FIG. 1, 6 is an explosion-proof valve, 7 is an exhaust hole,
Reference numeral 13 denotes an insulating plate that separates the wound electrode from the case 12.
【００２０】本発明のリチウム二次電池においては、正
極活物質として、通常、コバルト酸リチウム(LiCoO2)と
いったリチウム(Li)とコバルト(Co)を主成分とする複合
酸化物が使用され、負極活物質にメソフェーズ小球体や
天然黒鉛などの炭素質材料が使用される。また、電解液
としては、有機溶媒に六フッ化リン酸リチウム電解質を
溶解したものが主に用いられる。In the lithium secondary battery of the present invention, a composite oxide containing lithium (Li) and cobalt (Co) as main components such as lithium cobalt oxide (LiCoO 2 ) is usually used as a positive electrode active material. Carbonaceous materials such as mesophase spheres and natural graphite are used as the active material. As the electrolytic solution, a solution obtained by dissolving a lithium hexafluorophosphate electrolyte in an organic solvent is mainly used.
【００２１】[0021]
【実施例】以下、本発明を実施例により詳細に説明する
が、本発明はこれらの実施例に限定されるものではな
い。EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.
【００２２】（実施例１）図２に試料作製の手順を示
す。出発原料としての酸化バナジウム(V2O3)を用いて、
酸化クロム(Cr2O3)、酸化鉄(Fe2O3)、酸化タングステン
(WO3)の粉末を表1に記載の通りに数種秤量し、これに水
又はアルコールを加えてよく混合し、球粉砕(直径5mm
φ)で24時間粉砕した(一時粉砕)。その後、600℃で2時
間、さらに1000℃で3時間仮焼した。その際、昇降温速
度を400℃/hrとした。仮焼により得られた試料に水又は
アルコールを加えて混合し、球粉砕(直径5mmφ)で6時間
粉砕した(二次粉砕)。(Example 1) FIG. 2 shows a procedure for preparing a sample. Using vanadium oxide (V 2 O 3 ) as a starting material,
Chromium oxide (Cr 2 O 3 ), iron oxide (Fe 2 O 3 ), tungsten oxide
(WO 3 ) Powders were weighed as described in Table 1, several kinds were weighed as described in Table 1, and water or alcohol was added thereto and mixed well.
(φ) for 24 hours (temporary grinding). Then, it was calcined at 600 ° C. for 2 hours and further at 1000 ° C. for 3 hours. At that time, the temperature rising / falling rate was 400 ° C./hr. Water or alcohol was added to the sample obtained by calcination, mixed, and crushed by ball crushing (diameter 5 mmφ) for 6 hours (secondary crushing).
【００２３】[0023]
【表１】 [Table 1]
【００２４】その後、粉砕した試料をプレス5t、CIP 7t
/cm2で成形し、ペレットを作製した。このペレットを水
素濃度100％とした雰囲気において、1650℃で4時間本焼
成して試料(直径50mmφ、厚さ3mm)を得た。その際、昇
降温速度を600℃/hrとした。次に、得られたペレットの
両面にカーボンペーストを塗布し、その両面に電極とな
るアルミニウム板(50mm×70mm、厚さ0.5mm)を貼り付け
た。さらに、アルミニウム板に電流、電圧を測定するた
めの端子を計４つクリップで挟んで取り付けた。このよ
うにして作製したペレットの抵抗率を四端子、定電圧に
よる直流法によって温度範囲ー100℃〜300℃の温度で測
定することで、転移点温度、抵抗率変化、室温抵抗率を
求めた。その際、温度は熱電対を用いて測定した。ま
た、試料中に含まれる添加物量は、誘導結合高周波プラ
ズマ発光分析(ICP)を用いて求めた。Then, the crushed sample is pressed 5t, CIP 7t
/ cm 2 to produce pellets. The pellets were fully fired at 1650 ° C. for 4 hours in an atmosphere having a hydrogen concentration of 100% to obtain a sample (diameter: 50 mmφ, thickness: 3 mm). At that time, the temperature rise / fall rate was set to 600 ° C./hr. Next, a carbon paste was applied to both surfaces of the obtained pellet, and an aluminum plate (50 mm × 70 mm, thickness 0.5 mm) serving as an electrode was attached to both surfaces. Furthermore, terminals for measuring current and voltage were mounted on the aluminum plate with a total of four clips. The transition point temperature, the change in resistivity, and the room temperature resistivity were determined by measuring the resistivity of the pellets prepared in this manner at a temperature in a temperature range of −100 ° C. to 300 ° C. by a DC method using four terminals and a constant voltage. . At that time, the temperature was measured using a thermocouple. The amount of the additive contained in the sample was determined by using inductively coupled high frequency plasma emission spectrometry (ICP).
【００２５】測定結果は表１に併記されている。表中の
括弧は作製した試料（焼成体）の誘導結合高周波プラズ
マ発光分析(ICP)による化学分析値である。図３には、
試料6、7、8(鉄(Fe)の添加量1wt％、3wt％、5wt％)と電気
抵抗−温度特性の変化図を示した。図3に示すように、
鉄(Fe)を3wt％以上添加すると、初期抵抗が上昇し、抵
抗ジャンプ率が低下した。各試料の微構造を走査型電子
顕微鏡(SEM)で観察すると、焼結粒径は、10μｍ以上
で、特に、鉄(Fe)を5wt％添加したときは、焼結粒径が2
0μｍ以上に成長し、粒内にクラックが観察された。こ
のことから、鉄(Fe)を添加する場合は、1wt％以下が好
ましい。The measurement results are also shown in Table 1. Parentheses in the table indicate chemical analysis values of the produced sample (fired body) by inductively coupled high frequency plasma emission spectrometry (ICP). In FIG.
Samples 6, 7, and 8 (1% by weight, 3% by weight, and 5% by weight of iron (Fe) added) and changes in electrical resistance-temperature characteristics are shown. As shown in FIG.
When iron (Fe) was added at 3 wt% or more, the initial resistance increased and the resistance jump rate decreased. When the microstructure of each sample was observed with a scanning electron microscope (SEM), the sintered particle size was 10 μm or more, especially when 5 wt% of iron (Fe) was added, the sintered particle size was 2 μm.
It grew to 0 μm or more, and cracks were observed in the grains. For this reason, when iron (Fe) is added, the content is preferably 1% by weight or less.
【００２６】図４には、試料9、10、11、12、13(タングステ
ン(W)の添加量0、3、5、10、15wt％)と電気抵抗−温度特性
の変化図を示した。図４に示されるように、タングステ
ン(W)の添加量は、5wt％以下が良好な特性を示した。各
試料の微構造を走査型電子顕微鏡(SEM)で観察すると、
タングステン(W)の添加量が0wt％では、焼結粒径が20μ
ｍ以上で、添加量を5wt％にすると、焼結粒径は、5〜10
μｍ前後にまで小さくなった。また、焼結体開気孔率
は、5wt％のとき0.4％と最も小さく、タングステン(W)
を15wt％まで添加すると、開気孔率は1.8％まで増大し
た。このことから、タングステン(W)の添加量を5wt％以
下、好ましくは、5wt％程度とすると、良好な電気特性
に加え、焼結の阻害と高い気孔率を防ぐことができる。FIG. 4 shows a change diagram of the samples 9, 10, 11, 12, and 13 (the added amount of tungsten (W) is 0, 3, 5, 10, and 15 wt%) and the electric resistance-temperature characteristics. As shown in FIG. 4, good characteristics were exhibited when the amount of tungsten (W) added was 5 wt% or less. Observing the microstructure of each sample with a scanning electron microscope (SEM),
When the amount of tungsten (W) added is 0 wt%, the sintered particle size is 20μ.
m and the addition amount is 5 wt%, the sintered particle size is 5-10
It became smaller to about μm. In addition, the open porosity of the sintered body is the smallest at 0.4% at 5 wt%, and tungsten (W)
To 15 wt% increased the open porosity to 1.8%. For this reason, when the added amount of tungsten (W) is 5 wt% or less, preferably about 5 wt%, it is possible to prevent sintering inhibition and high porosity in addition to good electric characteristics.
【００２７】図５には、タングステン(W)の添加量を5wt
％、鉄(Fe)の添加量を1wt％とし、クロム(Cr)の添加量
を変化させた場合の、試料番号1〜5の特性変化図を示し
た。表１に示す焼成体のICPによる化学分析値と図５か
ら明らかなように、クロム(Cr)含有量が0.5mol％以上1.
0mol％以下であり、タングステン(W)添加量が5wt％以
下、好ましくは約5wt％で、さらに、鉄(Fe)の添加量が1
wt％以下を含んだ試料番号3、4において、室温抵抗率が1
mΩ・cm、転移温度が80℃〜100℃、抵抗率変化が500倍程
度の特性を有するPTC素子が得られた。FIG. 5 shows that the addition amount of tungsten (W) is 5 wt.
%, And the addition amount of iron (Fe) was set to 1 wt%, and the characteristic change diagram of Sample Nos. 1 to 5 when the addition amount of chromium (Cr) was changed was shown. As is clear from the chemical analysis values by ICP of the fired body shown in Table 1 and FIG. 5, the chromium (Cr) content is 0.5 mol% or more.
0 mol% or less, the addition amount of tungsten (W) is 5 wt% or less, preferably about 5 wt%, and the addition amount of iron (Fe) is 1%.
In sample Nos. 3 and 4 containing wt% or less, the room temperature resistivity was 1
A PTC element having a characteristic of mΩ · cm, a transition temperature of 80 ° C. to 100 ° C., and a resistivity change of about 500 times was obtained.
【００２８】これらの組成範囲外では、例えば、試料番
号5のように、抵抗変化率は485倍と大きいけれども、転
移温度が50℃と低いことから、民生用の一般的な電子機
器用のリチウム二次電池への装着には無理がある。しか
しながら、このように転移温度は低いが、室温抵抗率が
小さく、また抵抗率変化が大きい組成の素子は、低い温
度領域でのみ使用されるような特殊な装置用電源の保護
素子として適用することが可能と考えられる。Outside of these composition ranges, for example, as shown in Sample No. 5, although the rate of change in resistance is as large as 485 times, the transition temperature is as low as 50 ° C., so that lithium for general electronic equipment for consumer use is poor. Mounting on a secondary battery is impossible. However, such a device with a low transition temperature, low room temperature resistivity, and a large change in resistivity should be applied as a protection device for a special device power supply that is used only in a low temperature range. It is considered possible.
【００２９】（実施例２）次に、本発明による酸化バナ
ジウム(V2O3)系PTC素子、市販のチタン酸バリウム(BaTi
O3)PTC素子及び株式会社レイケムから発売されているPo
lyswitch(登録商標)ポリスイッチの名前で知られる導電
性ポリマーを用いた過電流及び加熱保護素子を用いて、
図１に示した構造のリチウム二次電池を作製し、その際
に、電極部とPTC素子を十分密着させながら電池を組立
て、図６に示した回路においてリチウム二次電池の出力
特性を調べた。チタン酸バリウム(BaTiO3)PTC素子及び
ポリスイッチを装着したリチウム二次電池では、電池に
出力低下が大きく、酸化バナジウム(V2O3)系PTC素子を
装着したリチウム二次電池で最も電池出力の低下が小さ
かった。従って、本発明による酸化バナジウム(V2O3)系
PTC素子を装着したものが最も安定した放電特性を示し
た。Example 2 Next, a vanadium oxide (V 2 O 3 ) -based PTC element according to the present invention, a commercially available barium titanate (BaTi
O 3 ) PTC element and Po sold by Raychem Co., Ltd.
With overcurrent and overheat protection elements using a conductive polymer known by the name lyswitch® polyswitch,
A lithium secondary battery having the structure shown in FIG. 1 was manufactured. At that time, the battery was assembled while the electrode portion and the PTC element were sufficiently adhered to each other, and the output characteristics of the lithium secondary battery were examined in the circuit shown in FIG. . In lithium secondary batteries equipped with barium titanate (BaTiO 3 ) PTC elements and polyswitches, the output of the batteries greatly decreases, and the battery output is the highest in lithium secondary batteries equipped with vanadium oxide (V 2 O 3 ) PTC elements. The decrease was small. Therefore, the vanadium oxide (V 2 O 3 ) system according to the present invention
The one with the PTC element showed the most stable discharge characteristics.
【００３０】（実施例３）さらに、本発明による酸化バ
ナジウム(V2O3)系PTC素子、市販のチタン酸バリウム(Ba
TiO3)PTC素子及び株式会社レイケムから発売されている
Polyswitch(登録商標)ポリスイッチの名前で知られる導
電性ポリマーを用いた過電流及び加熱保護素子を用い
て、図１に示したリチウム二次電池を作製し、図６に示
した回路において過充電試験を行った。チタン酸バリウ
ム(BaTiO3)PTC素子及びポリスイッチを装着したリチウ
ム二次電池では、120℃〜150℃で作動したのに対し、本
発明による酸化バナジウム(V2O3)系PTC素子を装着した
リチウム二次電池では、80℃〜100℃で作動した。これ
は、転移温度が他のPTC素子よりも低いことで過電流に
よる素子の温度上昇をいち早く感知して過電流放電を阻
止した結果と考えられる。また、電流制御後の電流値は
ポリスイッチを用いた場合よりは大きいが、電池の破裂
や短絡線による発火は見られなかったことから、電池の
保護という面からは問題のなく制御されていることを確
認した。Example 3 Further, a vanadium oxide (V 2 O 3 ) -based PTC device according to the present invention, a commercially available barium titanate (Ba
TiO 3 ) PTC element and sold by Raychem Corporation
Using an overcurrent and heating protection element using a conductive polymer known as Polyswitch (registered trademark), the lithium secondary battery shown in FIG. 1 was fabricated and overcharged in the circuit shown in FIG. The test was performed. A lithium secondary battery equipped with a barium titanate (BaTiO 3 ) PTC element and a polyswitch was operated at 120 ° C. to 150 ° C., whereas a vanadium oxide (V 2 O 3 ) -based PTC element according to the present invention was attached. The lithium secondary battery operated at 80 ° C to 100 ° C. This is probably because the transition temperature is lower than that of the other PTC elements, and the temperature rise of the element due to the overcurrent is quickly detected to prevent the overcurrent discharge. In addition, the current value after current control is larger than that using a polyswitch, but since there was no ignition due to battery rupture or short-circuit wire, it was controlled without any problem in terms of battery protection. It was confirmed.
【００３１】[0031]
【発明の効果】以上述べたように、本発明の酸化バナジ
ウム(V2O3)系PTC素子を使用したリチウム二次電池によ
れば、電池の出力電圧が高く、放電特性が良好で電池寿
命が長く、しかも過放電や過充電による電池内部の温度
上昇によって引き起こされる破裂事故などを防ぐことが
可能である。また、素子の抵抗率上昇による転移温度が
80℃〜100℃であるために、電池内部の温度上昇に速や
かに対応し、極めて安全性が高くなる。このようなPTC
素子を装着する電池としては、リチウム二次電池に限ら
ず、その他の二次電池に適用できることは容易に想像さ
れる。また、本発明によるPTC素子は電池に限らず、小
さい抵抗のPTC素子を必要とする半導体作動回路や電子
機器の電流制御回路に組み込んで使用できることは言う
までもない。As described above, according to the lithium secondary battery using the vanadium oxide (V 2 O 3 ) -based PTC element of the present invention, the output voltage of the battery is high, the discharge characteristics are good, and the battery life is long. It is possible to prevent a rupture accident or the like caused by temperature rise inside the battery due to overdischarge or overcharge. In addition, the transition temperature caused by the increase in the resistivity of the element
Since the temperature is between 80 ° C. and 100 ° C., it responds quickly to the temperature rise inside the battery, and the safety becomes extremely high. PTC like this
The battery on which the element is mounted is not limited to the lithium secondary battery, and it is easily conceivable that the battery can be applied to other secondary batteries. Further, it goes without saying that the PTC element according to the present invention is not limited to batteries, and can be used by incorporating it into a semiconductor operating circuit or a current control circuit of an electronic device that requires a PTC element having a small resistance.
【図１】リチウム二次電池の構造を示す断面図である。FIG. 1 is a cross-sectional view illustrating a structure of a lithium secondary battery.
【図２】本発明に用いる酸化バナジウム(V2O3)系PTC素
子の作製手順の一例を示すフローチャートである。FIG. 2 is a flowchart showing an example of a procedure for manufacturing a vanadium oxide (V 2 O 3 ) -based PTC element used in the present invention.
【図３】本発明に用いる酸化バナジウム(V2O3)系PTC素
子のタングステン(W)添加量と、抵抗率−温度特性の関
係を示すグラフである。FIG. 3 is a graph showing the relationship between the amount of tungsten (W) added and the resistivity-temperature characteristics of a vanadium oxide (V 2 O 3 ) -based PTC element used in the present invention.
【図４】本発明に用いる酸化バナジウム(V2O3)系PTC素
子の鉄(Fe)添加量と、抵抗率−温度特性の関係を示すグ
ラフである。FIG. 4 is a graph showing the relationship between the amount of iron (Fe) added to a vanadium oxide (V 2 O 3 ) -based PTC element used in the present invention and the resistivity-temperature characteristics.
【図５】本発明に用いる酸化バナジウム(V2O3)系PTC素
子の抵抗率の温度依存性を示すグラフである。FIG. 5 is a graph showing the temperature dependence of the resistivity of a vanadium oxide (V 2 O 3 ) -based PTC element used in the present invention.
【図６】PTC素子の電流制御特性を調べるための回路図
である。FIG. 6 is a circuit diagram for examining a current control characteristic of a PTC element.
１…正極、２…負極リード、３…負極、４…セパレー
タ、５…正極リード、６…防爆弁、７…排気孔、８…正
極端子、９…ＰＴＣ素子、１０…ガスケット、１１…絶
縁板、１２…金属ケース、１３…絶縁板、２０…電流電
源、２１…記録計、２２…電圧計、２３…評価用実験電
池DESCRIPTION OF SYMBOLS 1 ... Positive electrode, 2 ... Negative electrode lead, 3 ... Negative electrode, 4 ... Separator, 5 ... Positive electrode lead, 6 ... Explosion-proof valve, 7 ... Exhaust hole, 8 ... Positive electrode terminal, 9 ... PTC element, 10 ... Gasket, 11 ... Insulating plate , 12 ... metal case, 13 ... insulating plate, 20 ... current power supply, 21 ... recorder, 22 ... voltmeter, 23 ... evaluation experimental battery
Claims (3)
る複合金属酸化物を正極活物質とし、炭素質材料を負極
活物質とするリチウム二次電池において、酸化バナジウ
ム(V2O3)を主成分とし、酸化バナジウム(V2O3)のモル量
に対して、クロム(Cr)含有量が0.5mol％以上1.0mol％以
下である組成を有する酸化バナジウム系PTC素子を装着
したことを特徴とするリチウム二次電池。1. A lithium secondary battery comprising a composite metal oxide containing lithium (Li) and cobalt (Co) as main components as a positive electrode active material and a carbonaceous material as a negative electrode active material, wherein vanadium oxide (V 2 O 3 ) A vanadium oxide-based PTC element having a composition in which chromium (Cr) content is 0.5 mol% or more and 1.0 mol% or less with respect to the molar amount of vanadium oxide (V 2 O 3 ) is mounted. A lithium secondary battery, characterized in that:
2O3)の合計した重量に対して、タングステン(W)を5wt％
以下添加した組成を有する酸化バナジウム系PTC素子を
装着したことを特徴とする請求項１記載のリチウム二次
電池。2. Vanadium oxide (V 2 O 3 ) and chromium oxide (Cr)
5 wt% of tungsten (W) based on the total weight of 2 O 3 )
2. The lithium secondary battery according to claim 1, further comprising a vanadium oxide-based PTC element having the following composition.
2O3)の合計した重量に対して、さらに、鉄(Fe)を1wt％
以下添加した組成を有する酸化バナジウム系PTC素子を
装着したことを特徴とする請求項１又は２記載のリチウ
ム二次電池。3. A vanadium oxide (V 2 O 3 ) and a chromium oxide (Cr)
2 O 3 ), and further add iron (Fe) by 1 wt%
The lithium secondary battery according to claim 1, further comprising a vanadium oxide-based PTC element having the following composition.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8305264A JPH10144353A (en) | 1996-11-15 | 1996-11-15 | Lithium secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8305264A JPH10144353A (en) | 1996-11-15 | 1996-11-15 | Lithium secondary battery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH10144353A true JPH10144353A (en) | 1998-05-29 |
Family
ID=17943016
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8305264A Withdrawn JPH10144353A (en) | 1996-11-15 | 1996-11-15 | Lithium secondary battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH10144353A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003168419A (en) * | 2001-09-19 | 2003-06-13 | Matsushita Electric Ind Co Ltd | Non-aqueous electrolyte secondary battery |
| JP2007533074A (en) * | 2004-05-19 | 2007-11-15 | エルジー・ケム・リミテッド | Battery safety element and battery equipped with the same |
| US8609286B2 (en) | 2007-11-13 | 2013-12-17 | Sony Corporation | Nonaqueous electrolyte secondary battery |
-
1996
- 1996-11-15 JP JP8305264A patent/JPH10144353A/en not_active Withdrawn
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003168419A (en) * | 2001-09-19 | 2003-06-13 | Matsushita Electric Ind Co Ltd | Non-aqueous electrolyte secondary battery |
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