JP2003132945A - Secondary power supply - Google Patents

Secondary power supply

Info

Publication number
JP2003132945A
JP2003132945A JP2001326301A JP2001326301A JP2003132945A JP 2003132945 A JP2003132945 A JP 2003132945A JP 2001326301 A JP2001326301 A JP 2001326301A JP 2001326301 A JP2001326301 A JP 2001326301A JP 2003132945 A JP2003132945 A JP 2003132945A
Authority
JP
Japan
Prior art keywords
secondary power
negative electrode
lithium
positive electrode
power source
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.)
Granted
Application number
JP2001326301A
Other languages
Japanese (ja)
Other versions
JP4099970B2 (en
Inventor
Manabu Tsushima
学 對馬
Takeshi Morimoto
剛 森本
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AGC Inc
Original Assignee
Asahi Glass Co Ltd
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 Asahi Glass Co Ltd filed Critical Asahi Glass Co Ltd
Priority to JP2001326301A priority Critical patent/JP4099970B2/en
Priority to EP02005229A priority patent/EP1239495B1/en
Priority to DE60213696T priority patent/DE60213696T2/en
Priority to US10/092,988 priority patent/US6824923B2/en
Publication of JP2003132945A publication Critical patent/JP2003132945A/en
Application granted granted Critical
Publication of JP4099970B2 publication Critical patent/JP4099970B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

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; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries

Abstract

PROBLEM TO BE SOLVED: To provide a secondary power supply which is higher in capacity density and is superior in quick charge and discharge cycle reliability. SOLUTION: The secondary power supply comprises organic solvent system electrolytic solution including lithium salt and quarternary onium salt, a positive electrode including active carbon, and a negative electrode including lithium titanate. The quarternary onium salt includes one or more kinds selected from a group comprising a quarternary onium ion (C2H5)3(CH3)N+ and (C2H5)4P+, and one or more kinds selected from a group comprising counter anion PF6-, BF4-, ClO4-, N(SO2CF3)2- or the like.

Description

【発明の詳細な説明】Detailed Description of the Invention

【0001】[0001]

【発明の属する技術分野】本発明は、容量密度が高く、
大電流での充放電サイクル信頼性に優れる二次電源に関
する。
TECHNICAL FIELD The present invention has a high capacity density,
The present invention relates to a secondary power supply which has excellent charge / discharge cycle reliability at a large current.

【0002】[0002]

【従来の技術】有機溶媒系電解液を使用する二次電源
は、大別すると、電気二重層キャパシタ、リチウムイオ
ン二次電池、前2者以外の二次電源の3つに分けられ
る。
2. Description of the Related Art A secondary power source using an organic solvent-based electrolyte is roughly classified into an electric double layer capacitor, a lithium ion secondary battery, and a secondary power source other than the former two.

【0003】電気二重層キャパシタは、正極、負極とも
に活性炭を主体とする分極性電極を使用することに特徴
がある。電気二重層キャパシタの耐電圧は、水系電解液
を使用すると1.2V、有機溶媒系電解液を使用すると
2.5〜3.3Vである。電気二重層キャパシタの静電
エネルギーは耐電圧の2乗に比例するので、耐電圧の高
い有機溶媒系電解液の方が水系電解液より高エネルギで
ある。しかし、有機溶媒系電解液を使用した電気二重層
キャパシタでもそのエネルギー密度は鉛蓄電池等の二次
電池の1/10以下であり、さらなるエネルギー密度の
向上が必要とされている。
The electric double layer capacitor is characterized in that a polarizable electrode mainly composed of activated carbon is used for both the positive electrode and the negative electrode. The withstand voltage of the electric double layer capacitor is 1.2 V when an aqueous electrolytic solution is used, and 2.5 to 3.3 V when an organic solvent electrolytic solution is used. Since the electrostatic energy of the electric double layer capacitor is proportional to the square of the withstand voltage, the organic solvent-based electrolytic solution having a high withstand voltage has higher energy than the aqueous electrolytic solution. However, even an electric double layer capacitor using an organic solvent-based electrolytic solution has an energy density of 1/10 or less that of a secondary battery such as a lead storage battery, and further improvement in energy density is required.

【0004】一方、リチウムイオン二次電池は、リチウ
ム含有遷移金属酸化物を主体とする正極と、リチウムイ
オンを吸蔵、脱離しうる炭素材料を主体とする負極とか
らなる。充電によりリチウムイオンが正極から脱離し、
負極の炭素材料へ吸蔵され、逆に、放電により負極から
リチウムイオンが脱離し、正極にリチウムイオンが吸蔵
される。したがって、本質的には電解液中のリチウムイ
オンは電池の充放電に関与しない。リチウムイオン二次
電池は電気二重層キャパシタに比べて高電圧で作動でき
かつ高容量という性質を有するが、抵抗が高く、急速充
放電サイクルによる寿命が電気二重層キャパシタに比べ
著しく短い問題があった。
On the other hand, the lithium ion secondary battery comprises a positive electrode mainly composed of a lithium-containing transition metal oxide and a negative electrode mainly composed of a carbon material capable of absorbing and desorbing lithium ions. Lithium ions are desorbed from the positive electrode by charging,
It is occluded in the carbon material of the negative electrode, and conversely, lithium ions are desorbed from the negative electrode by discharge, and lithium ions are occluded in the positive electrode. Therefore, the lithium ions in the electrolytic solution do not essentially participate in the charging and discharging of the battery. Lithium ion secondary batteries have the property of operating at higher voltage and higher capacity than electric double layer capacitors, but they have high resistance and have a problem that the life due to rapid charge / discharge cycles is significantly shorter than that of electric double layer capacitors. .

【0005】これに対し、正極に活性炭を用い、負極に
リチウムイオンを吸蔵、脱離しうる炭素材料を用いた二
次電源は、従来の正極、負極ともに活性炭を用いた電気
二重層キャパシタより高電圧で作動できかつ高容量にで
きる。また、リチウムイオン二次電池のように、正極活
物質自体にリチウムイオンが吸蔵、脱離することがな
く、リチウムイオンの吸蔵、脱離にともなう正極の劣化
がないため充放電サイクルの信頼性に優れている。
On the other hand, a secondary power source using activated carbon for the positive electrode and a carbon material capable of absorbing and desorbing lithium ions for the negative electrode has a higher voltage than conventional electric double layer capacitors using active carbon. It can operate at high capacity. In addition, unlike the lithium-ion secondary battery, lithium ions do not occlude and desorb in the positive electrode active material itself, and there is no deterioration of the positive electrode due to the occluding and desorption of lithium ions, which improves the reliability of the charge / discharge cycle. Are better.

【0006】例えば、特開昭64−14882号公報に
は、活性炭を主体とする電極を正極とし、X線回折によ
る[002]面の面間隔が0.338〜0.356nm
である炭素材料にあらかじめリチウムイオンを吸蔵させ
た電極を負極とする上限電圧3Vの二次電源が提案され
ている。また、特開平8−107048号公報には、リ
チウムイオンを吸蔵、脱離しうる炭素材料にあらかじめ
化学的方法または電気化学的方法でリチウムイオンを吸
蔵させた炭素材料を負極に用いる電池が提案されてい
る。特開平9−55342号公報には、リチウムイオン
を吸蔵、脱離しうる炭素材料をリチウムと合金を形成し
ない多孔質集電体に担持させる負極を有する、上限電圧
4Vの二次電源が提案されている。
[0006] For example, in Japanese Patent Laid-Open No. 64-14882, an electrode mainly composed of activated carbon is used as a positive electrode, and a [002] plane spacing by X-ray diffraction is 0.338 to 0.356 nm.
A secondary power source having an upper limit voltage of 3 V in which a negative electrode is an electrode in which lithium ions are occluded in the carbon material is proposed. Further, JP-A-8-107048 proposes a battery using as a negative electrode a carbon material capable of occluding and desorbing lithium ions in which a carbon material is occluded in advance by a chemical method or an electrochemical method. There is. Japanese Unexamined Patent Publication No. 9-55342 proposes a secondary power source having an upper limit voltage of 4 V, which has a negative electrode in which a carbon material capable of absorbing and desorbing lithium ions is supported on a porous current collector that does not form an alloy with lithium. There is.

【0007】しかし、上記二次電源であっても、充放電
サイクルに伴って容量変化がみられた。
However, even with the above-mentioned secondary power source, a change in capacity was observed with charge / discharge cycles.

【0008】[0008]

【発明が解決しようとする課題】本発明は、高容量密度
を有し、急速充放電が可能で、充放電サイクル信頼性の
高い二次電源の提供を目的とする。
SUMMARY OF THE INVENTION It is an object of the present invention to provide a secondary power source having a high capacity density, capable of rapid charge / discharge, and having high charge / discharge cycle reliability.

【0009】[0009]

【課題を解決するための手段】本発明は、リチウム塩と
第4級オニウム塩とを含む有機溶媒系電解液と、活性炭
を含む正極と、チタン酸リチウム(LiTi
12)を含む負極と、を有することを特徴とする二
次電源を提供する。
The present invention is directed to an organic solvent electrolyte containing a lithium salt and a quaternary onium salt, a positive electrode containing activated carbon, and lithium titanate (Li 4 Ti).
5 O 12 ), and a negative electrode containing 5 O 12 ).

【0010】[0010]

【発明の実施の形態】本明細書において、負極と集電体
とを接合等により一体化させたものを負極体といい、正
極と集電体とを接合等により一体化させたものを正極体
という。また、本発明の二次電源(以下、本二次電源と
いう)は、正極に活性炭を含み、負極にリチウムイオン
を吸蔵、脱離しうるチタン酸リチウム(以下、単にチタ
ン酸リチウムという)を含む。二次電池も電気二重層キ
ャパシタも二次電源の1種であるが、本明細書では、正
極に活性炭を含み、負極にチタン酸リチウムを含む特定
の構成の二次電源を単に二次電源という。また、本明細
書において、チタン酸リチウムとはLiTi12
で表される化合物のことをいう。
BEST MODE FOR CARRYING OUT THE INVENTION In the present specification, the one obtained by integrating a negative electrode and a current collector by joining or the like is referred to as a negative electrode body, and the one obtained by integrating a positive electrode and a current collector by joining or the like is a positive electrode. Called the body. Further, the secondary power source of the present invention (hereinafter referred to as the present secondary power source) includes activated carbon in the positive electrode and lithium titanate (hereinafter, simply referred to as lithium titanate) capable of inserting and extracting lithium ions in the negative electrode. Both the secondary battery and the electric double layer capacitor are one type of secondary power source, but in the present specification, a secondary power source having a specific configuration including activated carbon in the positive electrode and lithium titanate in the negative electrode is simply referred to as the secondary power source. . In addition, in the present specification, lithium titanate means Li 4 Ti 5 O 12
Refers to a compound represented by.

【0011】本二次電源において、正極に含まれる活性
炭は、比表面積が600〜3000m/gであること
が好ましい。活性炭の種類は、特に制限されないが、下
記に挙げるような活性炭原料を炭化、賦活して使用する
ことが好ましい。活性炭原料としては、やしがら、フェ
ノール樹脂、石油コークス等が挙げられ、また活性炭原
料の賦活方法としては水蒸気賦活法、溶融アルカリ賦活
法等が挙げられる。なかでも、やしがらまたはフェノー
ル樹脂を原料として水蒸気賦活して得られる活性炭が特
に好ましい。正極の抵抗を低くするために、正極中に導
電材として導電性のカーボンブラックまたは黒鉛を含ま
せておくのも好ましく、導電材の量は正極中に0.1〜
20質量%含まれることが好ましい。
In this secondary power source, the activated carbon contained in the positive electrode preferably has a specific surface area of 600 to 3000 m 2 / g. The type of activated carbon is not particularly limited, but it is preferable to use activated carbon raw materials such as those listed below after carbonization and activation. Examples of the activated carbon raw material include coconut husk, phenol resin, petroleum coke, and the like, and examples of the activated carbon raw material activation method include a steam activation method and a molten alkali activation method. Among them, activated carbon obtained by activating steam of coconut husk or phenol resin as a raw material is particularly preferable. In order to reduce the resistance of the positive electrode, it is also preferable to include conductive carbon black or graphite as a conductive material in the positive electrode.
It is preferably contained in an amount of 20% by mass.

【0012】正極体の作製方法としては、例えば活性炭
粉末と導電材との混合物にバインダとしてポリテトラフ
ルオロエチレンを混合し、混練した後シート状に成形し
て正極とし、これを集電体に導電性接着剤を用いて固定
する方法がある。また、バインダとしてポリフッ化ビニ
リデン、ポリアミドイミド、ポリイミド等を溶解したワ
ニスに活性炭粉末と導電材粉末とを分散させ、この液を
ドクターブレード法等によって集電体上に塗工し、乾燥
して得てもよい。正極体の強度と容量等の特性とのバラ
ンスから、正極中に含まれるバインダの量は1〜20質
量%であると好ましい。
As a method for producing the positive electrode body, for example, a mixture of activated carbon powder and a conductive material is mixed with polytetrafluoroethylene as a binder, and the mixture is kneaded and then formed into a sheet to obtain a positive electrode. There is a method of fixing with an adhesive. Further, polyvinylidene fluoride as a binder, polyamide imide, dispersed active carbon powder and conductive material powder in a varnish in which polyimide or the like is dissolved, this liquid is applied on a current collector by a doctor blade method or the like, and obtained by drying. May be. The amount of the binder contained in the positive electrode is preferably 1 to 20% by mass in view of the balance between the strength and capacity of the positive electrode body.

【0013】本二次電源において、負極に含まれるチタ
ン酸リチウムとしてはLiTi12であれば特に
限定されないが、例えばLiOHとTiOをモル比
4:5となるように混合し、その混合物を700℃から
900℃までの温度で酸素雰囲気中10時間焼成して得
たものが使用できる。チタン酸リチウムの比表面積が
1.0〜3.0m/gであると好ましい。比表面積が
1.0m/g未満であると、電極反応に寄与する有効
面積が小さく、大電流による充放電に対応できないおそ
れがある。一方、比表面積が3.0m/gを超える
と、活性表面が大きくなり、表面での有機電解液の分解
によるクーロン効率の低下が起こるおそれがある。
In this secondary power source, the lithium titanate contained in the negative electrode is not particularly limited as long as it is Li 4 Ti 5 O 12 , but for example, LiOH and TiO 2 are mixed in a molar ratio of 4: 5, A product obtained by firing the mixture at a temperature of 700 ° C. to 900 ° C. for 10 hours in an oxygen atmosphere can be used. The specific surface area of lithium titanate is preferably 1.0 to 3.0 m 2 / g. When the specific surface area is less than 1.0 m 2 / g, the effective area that contributes to the electrode reaction is small, and there is a possibility that charging / discharging due to a large current cannot be supported. On the other hand, when the specific surface area exceeds 3.0 m 2 / g, the active surface becomes large, and the Coulombic efficiency may decrease due to the decomposition of the organic electrolyte solution on the surface.

【0014】正極と同様に、負極の内部抵抗を低くする
ために、負極中に導電材を含ませておくのも好ましい。
導電材の量は負極中に0.1〜20質量%含まれると好
ましい。導電材としては、カーボンブラックや気相成長
炭素繊維材料(VGCF)が挙げられる。
Similarly to the positive electrode, it is also preferable to include a conductive material in the negative electrode in order to reduce the internal resistance of the negative electrode.
The amount of the conductive material is preferably 0.1 to 20% by mass in the negative electrode. Examples of the conductive material include carbon black and vapor grown carbon fiber material (VGCF).

【0015】負極体の作製方法としては、チタン酸リチ
ウムと導電材とを混合し、ポリテトラフルオロエチレン
をバインダとして混練してシート状に成形して負極を形
成し、得られた負極を導電性接着剤を用いて集電体に接
着させる方法が挙げられる。
As a method for producing the negative electrode body, lithium titanate and a conductive material are mixed and kneaded with polytetrafluoroethylene as a binder to form a sheet to form a negative electrode. A method of using an adhesive to adhere to the current collector can be mentioned.

【0016】また、バインダとなる樹脂またはその前駆
体を有機溶媒に溶解させた溶液にチタン酸リチウムと必
要により用いられる導電材とを分散させ、集電体に塗工
し、乾燥させて得る方法もある。このようなバインダと
しては、カルボキシメチルセルロースとSBRゴムとの
混合バインダ、ポリフッ化ビニリデン、ポリアミドイミ
ドまたはポリイミドが挙げられる。これらの方法の中で
も集電体に塗工する方法がより好ましい。
A method in which lithium titanate and a conductive material used as necessary are dispersed in a solution prepared by dissolving a binder resin or a precursor thereof in an organic solvent, and applying it to a current collector, followed by drying. There is also. Examples of such a binder include a mixed binder of carboxymethyl cellulose and SBR rubber, polyvinylidene fluoride, polyamide imide or polyimide. Among these methods, the method of coating on the current collector is more preferable.

【0017】本二次電源において、負極中のバインダ量
としては、4〜30質量%が好ましい。バインダ量が4
質量%未満であると、バインダとしての効果が弱くな
り、負極と集電体との剥離が多くなる。一方、バインダ
が30質量%より多いと、負極の容量が小さくなる。
In the secondary power source, the amount of binder in the negative electrode is preferably 4 to 30% by mass. Binder amount is 4
If it is less than mass%, the effect as a binder becomes weak, and peeling between the negative electrode and the current collector increases. On the other hand, when the binder content is more than 30% by mass, the capacity of the negative electrode becomes small.

【0018】負極に含まれるチタン酸リチウムは、スピ
ネル型結晶構造を有し、充放電電位はLi/Li電位
に対して1.5V付近にあり、一方、正極に含まれる活
性炭はLi/Li電位に対して4.0V〜4.6Vま
で分極が可能であるため、前記正極と前記負極とを組み
合せた本二次電源の上限作動電圧は2.5V〜3.1V
であり、下限は1.5Vである。また、充放電の際、リ
チウムイオンの吸蔵・脱離による構造の変化が小さいた
め、チタン酸リチウムを使用すると安定で、耐久性のよ
い負極が得られる。
The lithium titanate contained in the negative electrode has a spinel type crystal structure, and the charge / discharge potential is around 1.5 V with respect to the Li + / Li potential, while the activated carbon contained in the positive electrode is Li + / Li . Since polarization is possible from 4.0 V to 4.6 V with respect to the Li potential, the upper limit operating voltage of the secondary power source in which the positive electrode and the negative electrode are combined is 2.5 V to 3.1 V.
And the lower limit is 1.5V. In addition, since the change in structure due to occlusion / desorption of lithium ions during charging / discharging is small, the use of lithium titanate can provide a stable and durable negative electrode.

【0019】安定したサイクル特性を得るためには、負
極の作動電位をLi/Li電位に対して1.5V付近
に維持する必要がある。なぜなら、負極が過充電された
場合、電位が1.5V以下に低下し、1.0Vより低い
電位になると、電解液の分解を引き起し、容量の低下が
起こる。負極の過充電を防ぐためには負極の容量を正極
の容量より大きく設定する必要がある。具体的には負極
と正極の容量比(=負極の容量/正極の容量)を1.0
5〜1.8の範囲にすることが好ましい。前記容量比が
1.05未満であると、大電流充電時に負極内のLiイ
オンの拡散が電流に追いつかなくなると負極近傍の電位
が低下し、電解液の分解を引き起すおそれがある。一
方、前記容量比が1.80を超えると、二次電源全体の
エネルギー密度が低下するおそれがある。質量あたりの
放電容量を比較すると、チタン酸リチウムの方が活性炭
より約5倍大きいので上記容量比となるように正極中の
活性炭の量と負極中のチタン酸リチウムの量を調整すれ
ばよい。
In order to obtain stable cycle characteristics, it is necessary to maintain the operating potential of the negative electrode at around 1.5 V with respect to the Li + / Li potential. This is because, when the negative electrode is overcharged, the potential drops to 1.5 V or less, and when the potential becomes lower than 1.0 V, the decomposition of the electrolytic solution is caused and the capacity decreases. In order to prevent overcharge of the negative electrode, it is necessary to set the capacity of the negative electrode larger than that of the positive electrode. Specifically, the capacity ratio of the negative electrode and the positive electrode (= capacity of the negative electrode / capacity of the positive electrode) is 1.0.
It is preferably in the range of 5 to 1.8. When the capacity ratio is less than 1.05, when the diffusion of Li ions in the negative electrode cannot catch up with the current during high current charging, the potential near the negative electrode lowers, which may cause decomposition of the electrolytic solution. On the other hand, when the capacity ratio exceeds 1.80, the energy density of the entire secondary power source may decrease. Comparing the discharge capacities per mass, since lithium titanate is about 5 times larger than activated carbon, the amount of activated carbon in the positive electrode and the amount of lithium titanate in the negative electrode may be adjusted so that the above capacity ratio is obtained.

【0020】本二次電源において、電解液はリチウム塩
と第4級オニウム塩(以下、単にオニウム塩と略す)と
を含む。なお、本明細書において、リチウム塩とはリチ
ウムイオンと対アニオンとを含むものをいい、オニウム
塩とは第4級オニウムイオンと対アニオンとを含むもの
をいう。リチウム塩を単独で含む電解液の電気伝導度は
低く、大電流密度の放電において放電容量を大きくでき
ない。一方、オニウム塩を単独で含む電解液の場合に
は、充放電に関与するリチウム塩が存在しないので、充
放電できず二次電源として成り立たない。
In this secondary power source, the electrolytic solution contains a lithium salt and a quaternary onium salt (hereinafter simply referred to as an onium salt). In addition, in this specification, a lithium salt means what contains a lithium ion and a counter anion, and an onium salt means what contains a quaternary onium ion and a counter anion. The electrolyte containing lithium salt alone has a low electric conductivity, and the discharge capacity cannot be increased in the discharge with a large current density. On the other hand, in the case of an electrolytic solution containing an onium salt alone, since there is no lithium salt involved in charging / discharging, charging / discharging cannot be performed and a secondary power source cannot be established.

【0021】リチウム塩とオニウム塩とを両方含むこと
により、電解液の電気伝導度を高くでき、大電流密度放
電における容量密度を大きくできる。
By including both the lithium salt and the onium salt, the electric conductivity of the electrolytic solution can be increased and the capacity density in large current density discharge can be increased.

【0022】本二次電源において、電解液中のリチウム
塩の量とオニウム塩の量には、特に制限はないが、(オ
ニウムイオン/リチウムイオン)のモル比が0.3〜2
であると電解液の電気伝導度を高くでき、しかも内部抵
抗を低くできるため好ましい。前記モル比が2を超える
と電解液中のリチウムイオンが少なくなり、充放電容量
が大きくできないので好ましくない。一方、前記モル比
が0.3未満であると、電解液の電気伝導度が高くなら
ないので好ましくない。モル比が0.5〜1.5である
とさらに好ましい。
In this secondary power source, the amount of lithium salt and the amount of onium salt in the electrolytic solution are not particularly limited, but the molar ratio of (onium ion / lithium ion) is 0.3 to 2
It is preferable that the electric conductivity of the electrolytic solution can be increased and the internal resistance can be decreased. If the molar ratio exceeds 2, the amount of lithium ions in the electrolytic solution decreases, and the charge / discharge capacity cannot be increased, which is not preferable. On the other hand, when the molar ratio is less than 0.3, the electric conductivity of the electrolytic solution does not increase, which is not preferable. More preferably, the molar ratio is 0.5 to 1.5.

【0023】本二次電源においてリチウム塩としては、
LiPF、LiBF、LiClO、LiN(SO
CF、LiN(SO、CF
Li、LiC(SOCF、およびLiPF
(Cからなる群から選ばれる1種以上が好
ましい。
As the lithium salt in the secondary power source,
LiPF 6 , LiBF 4 , LiClO 4 , LiN (SO
2 CF 3) 2, LiN ( SO 2 C 2 F 5) 2, CF 3 S
O 3 Li, LiC (SO 2 CF 3 ) 3 , and LiPF
One or more selected from the group consisting of 3 (C 2 F 5 ) 3 is preferable.

【0024】本二次電源においてオニウム塩の第4級オ
ニウムイオンとしては(C CH、(C
、および(Cからなる群
から選ばれる1種以上が好ましい。また、第4級オニウ
ムイオンの対アニオンとしては、PF 、BF
ClO 、N(SOCF 、N(SO
、CFSO 、C(SO
、およびPF(C からなる群
から選ばれる1種以上が好ましい。オニウム塩が(C
CH、(C、および(C
からなる群から選ばれる1種以上の第4
級オニウムイオンと、PF 、BF 、Cl
、N(SOCF 、N(SO
、CFSO 、C(SOCF
、およびPF(C からなる群から選ば
れる1種以上の対アニオンとを含むとさらに好ましい。
In this secondary power source, the quaternary onium salt is used.
As for the nickel ion, (CTwoH5) ThreeCHThreeN+, (C
TwoH5)FourN+, And (CTwoH5)FourP+A group of
One or more selected from are preferable. Also, 4th grade Oniu
As the counter anion of muion, PF6 , BFFour ,
ClOFour , N (SOTwoCFThree)Two , N (SOTwoC Two
F5)Two , CFThreeSOThree , C (SOTwoC
FThree)Three , And PFThree(CTwoF5)Three A group of
One or more selected from are preferable. Onium salt is (CTwo
H 5)ThreeCHThreeN+, (CTwoH5)FourN+, And (C
TwoH5)FourP+One or more fourth selected from the group consisting of
Grade onium ion and PF6 , BFFour , Cl
O Four , N (SOTwoCFThree)Two , N (SOTwoC
TwoF5)Two , CFThreeSOThree , C (SOTwoCFThree)Three
, And PFThree(CTwoF5)Three Selected from the group consisting of
It is more preferable to include one or more counter anions described above.

【0025】本二次電源において、有機溶媒系電解液中
のリチウム塩とオニウム塩とを含む電解質全体の濃度
は、リチウムイオンとオニウムイオンの合計が0.5〜
2.5mol/Lが好ましい。電解質全体の濃度が0.
5mol/L未満であると電解液の電気伝導度が低く、
内部抵抗も高くなるため好ましくなく、一方、電解質全
体の濃度が2.5mol/Lを超えると電解液の粘性が
高くなりすぎて好ましくない。電解質全体の濃度が0.
75〜2.0mol/Lであるとさらに好ましい。
In this secondary power source, the concentration of the whole electrolyte containing the lithium salt and the onium salt in the organic solvent electrolyte is such that the total of lithium ion and onium ion is 0.5 to
2.5 mol / L is preferable. The concentration of the whole electrolyte is 0.
If it is less than 5 mol / L, the electric conductivity of the electrolyte is low,
The internal resistance also increases, which is not preferable. On the other hand, when the concentration of the whole electrolyte exceeds 2.5 mol / L, the viscosity of the electrolytic solution becomes too high, which is not preferable. The concentration of the whole electrolyte is 0.
It is more preferably 75 to 2.0 mol / L.

【0026】また、本二次電源における電解液の溶媒と
しては、プロピレンカーボネート(以下、PCと略
す)、エチレンカーボネート、ブチレンカーボネート、
ジメチルカーボネート、エチルメチルカーボネート、ジ
エチルカーボネート、スルホラン、ジメトキシエタン等
が挙げられ、これらを単独で、または2種以上の混合溶
媒として使用できる。
As the solvent of the electrolytic solution in the secondary power source, propylene carbonate (hereinafter abbreviated as PC), ethylene carbonate, butylene carbonate,
Dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, sulfolane, dimethoxyethane and the like can be mentioned, and these can be used alone or as a mixed solvent of two or more kinds.

【0027】[0027]

【実施例】次に、例1〜例3により本発明をさらに具体
的に説明する。なお、例1〜例3のセル作製は、すべて
露点が−60℃以下のアルゴングローブボックス中で行
った。セルはアルミラミネートパックで、電極サイズは
2.5cm×4.0cmである。正極集電体厚みは40
μm、負極集電体厚みは15μm、セパレータ厚みは8
0μmである。
EXAMPLES Next, the present invention will be described more specifically with reference to Examples 1 to 3. The cells of Examples 1 to 3 were all manufactured in an argon glove box with a dew point of -60 ° C or lower. The cell is an aluminum laminate pack, and the electrode size is 2.5 cm × 4.0 cm. Positive electrode current collector thickness is 40
μm, negative electrode current collector thickness 15 μm, separator thickness 8
It is 0 μm.

【0028】[例1(実施例)]LiOHとTiO
モル比4:5となるように混合し、その混合物を800
℃で酸素雰囲気中10時間焼成して、比表面積2.0m
/gのチタン酸リチウム粉末を得た。得られたチタン
酸リチウム粉末と黒鉛化した気相成長炭素繊維をポリフ
ッ化ビニリデン(PVDF)の2−メチル−N−ピロリ
ドン溶液に分散させ、集電体に塗布し、乾燥させ、チタ
ン酸リチウム:気相成長炭素繊維:PVDF=70:1
0:20(質量比)の負極体を得た。これをさらにロー
ルプレス機でプレスし、電極層厚さを32μmとし、負
極体とした。
Example 1 (Example) LiOH and TiO 2 were mixed at a molar ratio of 4: 5, and the mixture was mixed with 800
Calcination in oxygen atmosphere at ℃ for 10 hours, specific surface area 2.0m
2 / g of lithium titanate powder was obtained. The obtained lithium titanate powder and graphitized vapor-grown carbon fiber were dispersed in a solution of polyvinylidene fluoride (PVDF) in 2-methyl-N-pyrrolidone, coated on a current collector, and dried to obtain lithium titanate: Vapor grown carbon fiber: PVDF = 70: 1
A negative electrode body of 0:20 (mass ratio) was obtained. This was further pressed by a roll press machine to have an electrode layer thickness of 32 μm to obtain a negative electrode body.

【0029】次に、コークスを原料として溶融KOH賦
活法によって得られた比表面積800m/gの活性炭
70質量%、導電性カーボンブラック20質量%、およ
びバインダとしてのポリテトラフルオロエチレン10質
量%からなる混合物をエタノールを加えて混練し、圧延
した後、200℃で2時間真空乾燥して正極シートを得
た。導電性接着剤を用いて集電体に接着し、260℃で
2時間真空乾燥して正極体とした。
Next, from 70% by mass of activated carbon having a specific surface area of 800 m 2 / g obtained by a molten KOH activation method using coke as a raw material, 20% by mass of conductive carbon black, and 10% by mass of polytetrafluoroethylene as a binder. Ethanol was added to the mixture, and the mixture was kneaded, rolled, and vacuum dried at 200 ° C. for 2 hours to obtain a positive electrode sheet. It was adhered to a current collector using a conductive adhesive and vacuum dried at 260 ° C. for 2 hours to obtain a positive electrode body.

【0030】上記で得られた正極体と負極体をポリプロ
ピレン製のセパレータを介して対向させ、0.75mo
l/LのLiBFと0.75mol/Lの(C
(CH)NBFを含むPC溶液に充分な
時間含浸させて二次電源のラミネートパックセルを得
た。この二次電源の初期容量密度(mAh/cm)を
2.7Vから1.5Vまでの範囲で電流10mA(1.
0mA/cm)と200mA(20mA/cm)で
測定した。その後45℃雰囲気において電圧範囲2.7
Vから1.5Vまでの範囲で200mAの充放電電流で
充放電サイクル試験を行い、500サイクル後の容量を
測定した。(初期容量密度−500サイクル後の容量密
度)/初期容量密度で容量減少率を算出した。結果を表
1に示す。
The positive electrode body and the negative electrode body obtained above were made to face each other with a polypropylene separator interposed therebetween, and 0.75 mo
1 / L of LiBF 4 and 0.75 mol / L of (C
A PC solution containing 2 H 5 ) 3 (CH 3 ) NBF 4 was impregnated for a sufficient time to obtain a laminated pack cell as a secondary power source. The initial capacity density (mAh / cm 3 ) of this secondary power source was 10 mA (1.
It was measured at 0 mA / cm 2 ) and 200 mA (20 mA / cm 2 ). After that, in a 45 ° C atmosphere, the voltage range is 2.7.
A charge / discharge cycle test was performed at a charge / discharge current of 200 mA in the range from V to 1.5 V, and the capacity after 500 cycles was measured. The capacity reduction rate was calculated by (initial capacity density-capacity density after 500 cycles) / initial capacity density. The results are shown in Table 1.

【0031】[例2(比較例)]例1において、電解液
を1.5mol/LのLiBFのみを含むPCに変更
した以外は、例1と同様にした。結果を表1に示す。
Example 2 (Comparative Example) The same as Example 1 except that the electrolytic solution was changed to PC containing only 1.5 mol / L LiBF 4 in Example 1. The results are shown in Table 1.

【0032】[例3(比較例)]例1において、負極を
正極と同じ活性炭とし、電解液を1.5mol/Lの
(C(CH)NBFを含むPCに変更し
た以外は、例1と同様にして電気二重層キャパシタを作
製し、評価した。結果を表1に示す。
Example 3 (Comparative Example) In Example 1, the negative electrode was the same activated carbon as the positive electrode, and the electrolytic solution was changed to PC containing 1.5 mol / L of (C 2 H 5 ) 3 (CH 3 ) NBF 4. An electric double layer capacitor was prepared and evaluated in the same manner as in Example 1 except for the above. The results are shown in Table 1.

【0033】[例4(比較例)]例1において、負極中
のチタン酸リチウムを炭素材料(大阪瓦斯社製、商品
名:MCMB6−28)とし、電解液を1.0mol/
LのLiBFのみを含むエチレンカーボネートとエチ
ルメチルカーボネートの混合溶媒(体積比で1:1)に
変更した以外は、例1と同様にした。結果を表1に示
す。
Example 4 (Comparative Example) In Example 1, the lithium titanate in the negative electrode was used as a carbon material (Osaka Gas Co., Ltd., trade name: MCMB6-28), and the electrolytic solution was 1.0 mol / min.
Example 1 was repeated except that the mixed solvent of ethylene carbonate and ethyl methyl carbonate containing only L LiBF 4 (1: 1 by volume ratio) was used. The results are shown in Table 1.

【0034】[0034]

【表1】 [Table 1]

【0035】[0035]

【発明の効果】本発明によれば、容量密度が大きく、か
つ急速充放電サイクル信頼性の高い二次電源を提供でき
る。
According to the present invention, it is possible to provide a secondary power source having a large capacity density and a high reliability in rapid charge / discharge cycles.

【0036】正負極ともに活性炭からなる電気二重層キ
ャパシタと電極質量あたりの容量を比べた場合、本二次
電源では、約150mAh/gと電気二重層キャパシタ
の約30mAh/gのほぼ5倍に相当する。また、チタ
ン酸リチウムは充放電時の電位変化が非常に平坦であ
り、二次電源の容量を最大限に引出すことができるた
め、電気二重層キャパシタより高容量密度が得られる。
Comparing the capacity per electrode mass with an electric double layer capacitor made of activated carbon for both positive and negative electrodes, this secondary power source has a capacity of about 150 mAh / g, which is approximately five times 30 mAh / g of the electric double layer capacitor. To do. In addition, lithium titanate has a very flat potential change during charging and discharging, and can maximize the capacity of the secondary power source, so that a higher capacity density than that of the electric double layer capacitor can be obtained.

【0037】一方、本二次電源は、充電により電解液中
のアニオンが正極の活性炭に吸着し、電解液中のリチウ
ムイオンが負極のチタン酸リチウムへ吸蔵される。そし
て放電により負極からリチウムイオンが脱離し、正極で
はアニオンが脱着する。すなわち、正極活性物質自体に
リチウムイオンが吸蔵、脱離することがないため、リチ
ウムイオン二次電池のように、リチウムイオンの吸蔵、
脱離にともなう正極の劣化が起こらない。
On the other hand, in the secondary power source, anions in the electrolytic solution are adsorbed by the activated carbon of the positive electrode by charging, and lithium ions in the electrolytic solution are occluded in lithium titanate of the negative electrode. Then, the lithium ions are desorbed from the negative electrode by the discharge, and the anions are desorbed from the positive electrode. That is, since lithium ions do not occlude and desorb in the positive electrode active material itself, it occludes lithium ions like a lithium ion secondary battery.
Degradation of the positive electrode due to desorption does not occur.

【0038】また、本二次電源は、負極にリチウムイオ
ンの吸蔵脱離に伴う寸法変化がほとんどないスピネル型
結晶構造を有するチタン酸リチウムを採用するため、負
極に炭素材料を採用した場合に比べて、寸法変化による
炭素表面の被膜が破壊される、または炭素粒子間の結合
が緩むなどの不具合がなく、これらの不具合による容量
の低下や内部抵抗の上昇を防ぐことができる。
In addition, since the secondary power source employs lithium titanate having a spinel type crystal structure in which a dimensional change due to absorption and desorption of lithium ions is hardly present in the negative electrode, compared with the case where a carbon material is employed in the negative electrode. As a result, there is no defect that the coating on the carbon surface is broken or the bond between the carbon particles is loosened due to the dimensional change, and it is possible to prevent a decrease in capacity and an increase in internal resistance due to these defects.

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Claims (4)

【特許請求の範囲】[Claims] 【請求項1】リチウム塩と第4級オニウム塩とを含む有
機溶媒系電解液と、活性炭を含む正極と、チタン酸リチ
ウム(LiTi12)を含む負極と、を有するこ
とを特徴とする二次電源。
1. An organic solvent electrolyte containing a lithium salt and a quaternary onium salt, a positive electrode containing activated carbon, and a negative electrode containing lithium titanate (Li 4 Ti 5 O 12 ). And a secondary power supply.
【請求項2】前記リチウム塩がLiPF、LiB
、LiClO、LiN(SOCF、Li
N(SO、Li(SOCF)、Li
C(SO CF、およびLiPF(C
からなる群から選ばれる1種以上である請求項1記載
の二次電源。
2. The lithium salt is LiPF.6, LiB
FFour, LiClOFour, LiN (SOTwoCFThree)Two, Li
N (SOTwoCTwoF5)Two, Li (SOThreeCFThree), Li
C (SO TwoCFThree)Three, And LiPFThree(CTwoF5)
Three2. One or more selected from the group consisting of
Secondary power supply.
【請求項3】前記第4級オニウム塩が(C
(CH)N、(C、および(C
からなる群から選ばれる1種以上の第4級
オニウムイオンと、PF 、BF 、ClO
N(SOCF 、N(SO
CFSO 、C(SOCF 、およびPF
(C からなる群から選ばれる1種以上の
対アニオンと、を含む請求項1または2記載の二次電
源。
3. The quaternary onium salt is (C 2 H 5 ).
3 (CH 3 ) N + , (C 2 H 5 ) 4 N + , and (C 2
H 5 ) 4 P +, one or more quaternary onium ions selected from the group consisting of PF 6 , BF 4 , ClO 4 ,
N (SO 2 CF 3) 2 -, N (SO 2 C 2 F 5) 2 -,
CF 3 SO 3 , C (SO 2 CF 3 ) 3 , and PF
The secondary power source according to claim 1 or 2, further comprising one or more counter anions selected from the group consisting of 3 (C 2 F 5 ) 3 .
【請求項4】前記電解液中の第4級オニウムイオン/リ
チウムイオンのモル比が0.3〜2である請求項1、2
または3記載の二次電源。
4. The quaternary onium ion / lithium ion molar ratio in the electrolytic solution is 0.3 to 2.
Or the secondary power source described in 3.
JP2001326301A 2001-03-09 2001-10-24 Secondary power supply Expired - Fee Related JP4099970B2 (en)

Priority Applications (4)

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JP2001326301A JP4099970B2 (en) 2001-10-24 2001-10-24 Secondary power supply
EP02005229A EP1239495B1 (en) 2001-03-09 2002-03-07 Secondary power source
DE60213696T DE60213696T2 (en) 2001-03-09 2002-03-07 Secondary energy source
US10/092,988 US6824923B2 (en) 2001-03-09 2002-03-08 Secondary power source having a lithium titanate

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JP4099970B2 JP4099970B2 (en) 2008-06-11

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