JP3047409B2 - Lithium secondary battery - Google Patents
Lithium secondary batteryInfo
- Publication number
- JP3047409B2 JP3047409B2 JP1232391A JP23239189A JP3047409B2 JP 3047409 B2 JP3047409 B2 JP 3047409B2 JP 1232391 A JP1232391 A JP 1232391A JP 23239189 A JP23239189 A JP 23239189A JP 3047409 B2 JP3047409 B2 JP 3047409B2
- Authority
- JP
- Japan
- Prior art keywords
- activated carbon
- lithium secondary
- secondary battery
- ratio
- group
- 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.)
- Expired - Fee Related
Links
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)
- Battery Electrode And Active Subsutance (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は，優れた体積容量効率を有するリチウム二次
電池に関する。Description: TECHNICAL FIELD The present invention relates to a lithium secondary battery having excellent volumetric capacity efficiency.
活性炭からなる分極性電極では，充放電時の活性炭表
面と電解質イオンとの物理的，化学的反応により，電池
などの容量値，充放電特性が支配される。In a polarizable electrode made of activated carbon, the capacity and charge / discharge characteristics of a battery or the like are controlled by a physical or chemical reaction between the activated carbon surface and electrolyte ions during charge / discharge.
活性炭とリチウムとの組み合わせによる系（リチウム
二次電池）においては，充放電時において活性炭表面に
電気二重層が形成，消去される。In a system using a combination of activated carbon and lithium (lithium secondary battery), an electric double layer is formed and erased on the activated carbon surface during charging and discharging.
そして，リチウム二次電池は比較的体積容量効率が大
きいところから，その利用が拡大されつつある。The use of lithium secondary batteries is expanding due to their relatively large volumetric efficiency.
しかしながら，表面が平滑な水銀（Hg）における，そ
の表面電気二重層容量が40μF/cm2であることから判断
すると,2000m2/gの比表面積を有する活性炭繊維クロス
を用いた二次電池では，この値の10％程度の放電容量し
か得られていない。However, judging from the surface electric double layer capacity of mercury (Hg) with a smooth surface of 40 μF / cm 2 , a secondary battery using activated carbon fiber cloth with a specific surface area of 2000 m 2 / g, Only a discharge capacity of about 10% of this value is obtained.
本発明はかかる問題点に鑑み，更に優れた体積容量効
率を有するリチウム二次電池を提供しようとするもので
ある。SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a lithium secondary battery having more excellent volumetric capacity efficiency.
本発明は，正極に活性炭を用いるリチウム二次電池に
おいて，上記活性炭はその表面に酸性基を導入してな
り，またその表面における炭素元素数に対する酸素元素
数の比が0.1以上であることを特徴とするリチウム二次
電池にある。The present invention is characterized in that in a lithium secondary battery using activated carbon for the positive electrode, the activated carbon has an acidic group introduced on its surface, and the ratio of the number of oxygen elements to the number of carbon elements on its surface is 0.1 or more. Lithium secondary battery.
本発明において，活性炭表面に導入する酸性基として
は，カルボキシル基（−COOH），スルホン基（−SO3H）
などがある。また，かかる酸性基の導入方法としては，
過塩素酸，硫酸，フルオロスルホン酸（FSO3H），トリ
フルオロスルホン酸（CF3SO3H），過酸化水素，加熱空
気等の酸化剤により，活性炭を酸化処理する方法があ
る。In the present invention, the acidic groups to be introduced on the activated carbon surface include a carboxyl group (—COOH) and a sulfone group (—SO 3 H).
and so on. In addition, as a method for introducing such an acidic group,
There is a method of oxidizing activated carbon using an oxidizing agent such as perchloric acid, sulfuric acid, fluorosulfonic acid (FSO 3 H), trifluorosulfonic acid (CF 3 SO 3 H), hydrogen peroxide, and heated air.
また，活性炭表面には，上記酸性基と共に極性基を導
入することもできる。そして，極性基としてニトロ基
（−NO2）を用いた場合には，特に放電容量が向上す
る。また酸性基と極性基との導入法としては，過塩素酸
と硝酸との混酸，硫酸と硝酸との混酸などの硝酸を含む
液により，活性炭を処理する方法がある。Further, a polar group can be introduced into the activated carbon surface together with the acidic group. Then, when a nitro group (-NO 2) as the polar groups are in particular the discharge capacity is improved. As a method for introducing an acidic group and a polar group, there is a method in which activated carbon is treated with a liquid containing nitric acid such as a mixed acid of perchloric acid and nitric acid or a mixed acid of sulfuric acid and nitric acid.
また，本発明において重要なことは，炭素元素数に対
する酸素元素数の比（以下,O/C比という）が0.1以上で
あるということである。該O/C比が0.1未満では体積容量
効率の向上が少ない（第１図参照）。このO/C比は，上
記のごとく酸化処理した活性炭の表面を例えばXPS（Ｘ
線光電子分光法）により分析することにより，知ること
ができる。What is important in the present invention is that the ratio of the number of oxygen elements to the number of carbon elements (hereinafter referred to as O / C ratio) is 0.1 or more. When the O / C ratio is less than 0.1, the improvement in volumetric capacity efficiency is small (see FIG. 1). This O / C ratio can be determined by, for example, using XPS (X
It can be known by analyzing by line photoelectron spectroscopy).
また，本発明のリチウム二次電池に用いる活性炭は，
活性炭繊維クロスの他，活性炭粒子，活性炭繊維フェル
トなどの，いわゆる活性炭と称されるものを用いる。ま
た，該活性炭としては，フェノール系,PAN系，レーヨン
系，ピッチ系などがある。The activated carbon used in the lithium secondary battery of the present invention is:
In addition to the activated carbon fiber cloth, what is called activated carbon such as activated carbon particles and activated carbon fiber felt is used. Examples of the activated carbon include phenol-based, PAN-based, rayon-based, and pitch-based.
本発明によれば，体積容量効率に優れたリチウム二次
電池を提供することができる。According to the present invention, it is possible to provide a lithium secondary battery having excellent volume capacity efficiency.
このように優れた体積容量効率を発揮する理由は，次
のように考えられる。The reason why such excellent volumetric efficiency is exhibited is considered as follows.
即ち，リチウム二次電池は，活性炭表面へのイオンの
吸着による表面電気二重層に電荷を蓄え，イオンの吸脱
着により充放電を行うものである。したがって，活性炭
表面のイオンの吸着点が多い程，放電容量を増大させる
ことができる。That is, in the lithium secondary battery, charge is stored in the surface electric double layer by adsorption of ions to the surface of activated carbon, and charge and discharge are performed by adsorption and desorption of ions. Therefore, the discharge capacity can be increased as the number of ion adsorption points on the activated carbon surface increases.
本発明においては，活性炭表面に前記のごとく酸性基
を導入し，かつO/C比を0.1以上としたので，上記吸着点
を増加させることができ，電解質イオンとの親和性が向
上するのである。それ故，特に放電時に，リチウムイオ
ンととの親和性が向上すると考えられる。In the present invention, since the acidic group is introduced into the activated carbon surface as described above, and the O / C ratio is set to 0.1 or more, the adsorption point can be increased, and the affinity with the electrolyte ion is improved. . Therefore, it is considered that the affinity with lithium ions is improved particularly during discharging.
換言すれば，放電時には，リチウムイオン（Li+）
は，活性炭の表面に吸着されるが，活性炭表面は，上記
のごとく酸性基が導入され，かつO/C比が0.1以上の状態
にあり，リチウムイオンが吸着し易い酸素元素が増えて
いる。そのため，吸着サイトが増加し，放電容量が増加
するのである。In other words, when discharging, lithium ions (Li + )
Is adsorbed on the surface of activated carbon, but on the activated carbon surface, the acidic groups are introduced as described above and the O / C ratio is 0.1 or more, and the oxygen element to which lithium ions are easily adsorbed is increasing. Therefore, the number of adsorption sites increases and the discharge capacity increases.
本発明にかかる活性炭を具備したリチウム二次電池を
作製し，その放電容量を測定した。また，併せて比較実
験も行った。A lithium secondary battery including the activated carbon according to the present invention was manufactured, and its discharge capacity was measured. In addition, comparative experiments were also performed.
まず，以下の実施例，比較例に用いたリチウム二次電
池は，第２図に示すごとく，正極１と負極２と両者の間
に介設したセパレータ３とよりなる。また，これらの外
側面にはガスケット６を介して正極ケース４を配設し，
更に負極上面には負極ケース５を設けてなる。First, the lithium secondary batteries used in the following examples and comparative examples include a positive electrode 1, a negative electrode 2, and a separator 3 interposed therebetween as shown in FIG. Further, a positive electrode case 4 is disposed on these outer surfaces via a gasket 6,
Further, a negative electrode case 5 is provided on the upper surface of the negative electrode.
上記正極１は，厚み0.75mm,直径15mmのフェノール系
活性炭繊維クロスを８枚差ね，その中に電解液が含浸さ
せてある。該電解液は，過塩素酸リチウム（LiClO4）を
0.7モル／で，炭酸プロピレン（PC）に溶解させたも
のである。電解液含浸後は，正極ケース４の上方をかし
める。正極ケース４は，ステンレス鋼である。The positive electrode 1 includes eight phenol-based activated carbon fiber cloths having a thickness of 0.75 mm and a diameter of 15 mm, and impregnated with an electrolyte. The electrolyte is lithium perchlorate (LiClO 4 ).
0.7 mol / dissolved in propylene carbonate (PC). After the impregnation with the electrolyte, the upper part of the positive electrode case 4 is swaged. The positive electrode case 4 is made of stainless steel.
負極２は，厚み0.2mmのリチウム板と厚み0.4mmのアル
ミニウム板とを，電池ケース内で圧着し，上記電解液存
在下で合金化させたものである。セパレータ３は，厚み
0.25mmのポリプロピレン不織布である。負極ケース５
は，ステンレス鋼である。また，ガスケット６は，正極
ケース４と負極ケース５の絶縁及び正極ケース４の側壁
上方をかしめたときのシール材の役目をなす。The negative electrode 2 is obtained by crimping a lithium plate having a thickness of 0.2 mm and an aluminum plate having a thickness of 0.4 mm in a battery case and alloying in the presence of the electrolyte. Separator 3 has a thickness
It is a 0.25 mm polypropylene nonwoven fabric. Negative electrode case 5
Is stainless steel. Further, the gasket 6 serves as an insulating material between the positive electrode case 4 and the negative electrode case 5 and a sealing material when the upper side of the side wall of the positive electrode case 4 is swaged.
下記の実施例，比較例においては，上記正極の活性炭
繊維に対して，種々の処理を施し，そのリチウム二次電
池おける放電容量を測定した。また，活性炭表面におけ
るO/C比も測定した。上記放電容量（mAh）は,3.2V（ボ
ルト）で24時間充電後,6KΩの抵抗を介して2Vまで放電
したときの値を示す。O/C比は前記XPSにより分析した。In the following Examples and Comparative Examples, the activated carbon fiber of the positive electrode was subjected to various treatments, and the discharge capacity of the lithium secondary battery was measured. The O / C ratio on the activated carbon surface was also measured. The discharge capacity (mAh) indicates a value when the battery is charged to 3.2 V (volts) for 24 hours and then discharged to 2 V through a 6 KΩ resistor. The O / C ratio was analyzed by the XPS.
測定の結果を，第１表及び第１図に示す。 The results of the measurement are shown in Table 1 and FIG.
第１実施例 活性炭繊維クロスを，過塩素酸70％水溶液中,80％,1
時間の条件下で，処理した。これにより，その表面に酸
性基としてのカルボキシル基を導入した。First Example Activated carbon fiber cloth was placed in a 70% aqueous solution of perchloric acid at 80%, 1%.
Treated under time conditions. This introduced a carboxyl group as an acidic group on the surface.
第２実施例 活性炭繊維クロスを，濃硫酸中,80％,1時間の条件下
で，処理した。これにより，その表面に，スルホン基を
導入した。Second Example Activated carbon fiber cloth was treated in concentrated sulfuric acid at 80% for 1 hour. As a result, sulfone groups were introduced on the surface.
第３実施例 活性炭繊維クロスを，過酸化水素30％水溶液中80％,1
時間の条件下で，処理した。これによりその表面に酸性
基としてのカルボキシル基を導入した。Third Example Activated carbon fiber cloth was treated with 80%
Treated under time conditions. This introduced a carboxyl group as an acidic group on the surface.
第４実施例 活性炭繊維クロスを，空気中,450℃,1時間の条件下で
酸化処理した。これによりその表面に酸性基としてのカ
ルボキシル基を導入した。Fourth Example An activated carbon fiber cloth was oxidized in air at 450 ° C. for 1 hour. This introduced a carboxyl group as an acidic group on the surface.
第５実施例 活性炭繊維クロスを，過塩素酸と硝酸とを１対１（モ
ル比）で混合した混酸の中に浸漬し,80℃において加熱
した。これにより，活性炭表面に酸性基としてのカルボ
キシル基と，極性基としてのニトロ基を導入した。Fifth Example Activated carbon fiber cloth was immersed in a mixed acid obtained by mixing perchloric acid and nitric acid at a molar ratio of 1: 1 and heated at 80 ° C. As a result, a carboxyl group as an acidic group and a nitro group as a polar group were introduced on the activated carbon surface.
第６実施例 活性炭繊維クロスを，硫酸と硝酸とを１対１（モル
比）で混合した混酸の中に浸漬し,80℃において加熱し
た。これにより，活性炭表面には，酸性基としてのスル
ホン基と，極性基としてのニトロ基を導入した。Sixth Example Activated carbon fiber cloth was immersed in a mixed acid obtained by mixing sulfuric acid and nitric acid at a molar ratio of 1: 1 and heated at 80 ° C. As a result, a sulfone group as an acidic group and a nitro group as a polar group were introduced into the activated carbon surface.
比較例１ 活性炭繊維クロスには，何の酸化処理もしなかった。Comparative Example 1 The activated carbon fiber cloth was not subjected to any oxidation treatment.
比較例２ 活性炭繊維クロスを，塩酸20％水溶液中,80％,1時間
の条件下で，処理した。この場合，活性炭の表面には，
特に何も導入されない。Comparative Example 2 Activated carbon fiber cloth was treated in a 20% aqueous hydrochloric acid solution at 80% for 1 hour. In this case, the surface of the activated carbon
Nothing is specifically introduced.
比較例３ 活性炭繊維クロスを，真空中において,900℃で,1時間
加熱処理した。この場合も，活性炭の表面には，何も導
入されていない。Comparative Example 3 An activated carbon fiber cloth was heat-treated at 900 ° C. for 1 hour in a vacuum. In this case also, nothing was introduced on the surface of the activated carbon.
上記の測定結果を，第１〜第６実施例についてはNo.1
〜６の，比較例１〜３はNo.C1〜C3の各番号を付して，
第１表，第１図に示した。The above measurement results were compared with No. 1 for the first to sixth embodiments.
Comparative Examples 1 to 3 of Nos. 6 to 6 are assigned Nos. C1 to C3,
The results are shown in Table 1 and FIG.
第１表及び第１図より知られるごとく，本発明にかか
る活性炭を用いたリチウム二次電池（実施例１〜６）
は，いずれもO/C比が0.1以上である。そして,O/C比が0.
1以上のものは10mAh以上の放電容量を示している。 As is known from Table 1 and FIG. 1, lithium secondary batteries using activated carbon according to the present invention (Examples 1 to 6)
Have an O / C ratio of 0.1 or more. And the O / C ratio is 0.
A value of 1 or more indicates a discharge capacity of 10 mAh or more.
このうちカルボキシル基を導入したNo.1,酸性基とし
てのカルボキシル基又は酸性基と極性基としてのニトロ
基とを導入したNo.5,6はより高い放電容量を示してい
る。Among them, No. 1 in which a carboxyl group was introduced and Nos. 5 and 6 in which a carboxyl group or an acidic group as an acidic group and a nitro group as a polar group were introduced show higher discharge capacity.
これに対して，何の処理もしていない従来のリチウム
二次電池（No.C1）は9.2mAhであり，更に，塩酸，真空
加熱したもの（No.C2,C3）はそれより低い放電容量を示
している。In contrast, the conventional lithium secondary battery without any treatment (No. C1) has a discharge capacity of 9.2 mAh, and the hydrochloric acid and vacuum-heated batteries (No. C2, C3) have a lower discharge capacity. Is shown.
以上のごとく，本発明によれば，酸性基を導入すると
共に,O/C比を0.1以上とすることにより，優れた体積容
量効率を発揮するリチウム二次電池を得ることができ
る。As described above, according to the present invention, a lithium secondary battery exhibiting excellent volumetric capacity efficiency can be obtained by introducing an acidic group and making the O / C ratio 0.1 or more.
図は実施例を示し，第１図はO/C比と放電容量の関係を
示す線図，第２図はリチウム二次電池の断面図である。 １……正極,2……負極 ３……セパレータ,4……正極ケース， ５……負極ケース,6……ガスケット，FIG. 1 shows an embodiment, FIG. 1 is a diagram showing a relationship between an O / C ratio and a discharge capacity, and FIG. 2 is a sectional view of a lithium secondary battery. 1 ... Positive electrode, 2 ... Negative electrode 3 ... Separator, 4 ... Positive electrode case, 5 ... Negative electrode case, 6 ... Gasket,
Claims (1)
おいて，上記活性炭はその表面に酸性基を導入してな
り，またその表面における炭素元素数に対する酸素元素
数の比が0.1以上であることを特徴とするリチウム二次
電池。1. A lithium secondary battery using activated carbon for a positive electrode, wherein said activated carbon has an acidic group introduced on its surface, and that the ratio of the number of oxygen elements to the number of carbon elements on its surface is 0.1 or more. Characteristic lithium secondary battery.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1232391A JP3047409B2 (en) | 1989-09-07 | 1989-09-07 | Lithium secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1232391A JP3047409B2 (en) | 1989-09-07 | 1989-09-07 | Lithium secondary battery |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0395856A JPH0395856A (en) | 1991-04-22 |
| JP3047409B2 true JP3047409B2 (en) | 2000-05-29 |
Family
ID=16938509
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1232391A Expired - Fee Related JP3047409B2 (en) | 1989-09-07 | 1989-09-07 | Lithium secondary battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3047409B2 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4016481B2 (en) * | 1998-05-14 | 2007-12-05 | ソニー株式会社 | Solid electrolyte battery |
| KR20020076532A (en) * | 2001-03-29 | 2002-10-11 | 대림티앤씨(주) | Vacuum floor washer |
| JP4406832B2 (en) * | 2004-03-24 | 2010-02-03 | 株式会社デンソー | Lithium secondary battery electrode and lithium secondary battery |
| JP2005347164A (en) * | 2004-06-04 | 2005-12-15 | Toyota Motor Corp | Lithium secondary battery and positive electrode for lithium secondary battery |
| CN106252581B (en) * | 2010-12-23 | 2021-01-22 | 纳米技术仪器公司 | Surface-mediated lithium ion exchange energy storage device |
| JP6306836B2 (en) * | 2013-08-29 | 2018-04-04 | 株式会社キャタラー | Carbon materials for hybrid capacitors |
-
1989
- 1989-09-07 JP JP1232391A patent/JP3047409B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0395856A (en) | 1991-04-22 |
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