【発明の詳細な説明】[Detailed description of the invention]
本発明は電池活物質に関する。さらに詳しく
は、式（C2F）oで表わされるフツ化黒鉛（以下、
C2Fという）の単独またはC2Fと式（CF）oで表わ
されるフツ化黒鉛（以下、CFという）の混合物
を主成分とし、その粉末Ｘ線回折図に未反応黒鉛
のピークが認められる電池活物質に関する。
CFまたはC2Fが電池活物質として有用である
ことは知られている。
たとえば特開昭54−9730号公報には、石油コー
クスを原料炭素に用いてえられるCFが良好な放
電特性や保存特性を有していることが記載されて
いる。
また、特開昭53−102893号公報および特開昭55
−28246号公報に、約０〜0.6のフランクリンのＰ
値を有する黒鉛と100〜760mmHgのフツ素ガスを
用い、300〜500℃の温度で該黒鉛が完全にフツ素
化するまで反応せしめてえられる（C2F）oで表わ
されるフツ化黒鉛が電池活物質として有用である
ことが記載されている。
本発明者らはより一層放電特性にすぐれた電池
活物質をうるべく鋭意研究を重ねた結果、黒鉛を
フツ素ガスによりフツ素化せしめてえられ、フツ
素含有率45重量％以上であるC2F単独またはC2F
とCFとの混合物を主成分とし、その粉末Ｘ線回
折図に未反応黒鉛のピークが認められる電池活物
質が前記従来のフツ化黒鉛よりも高い放電電位を
有していることを見出し、本発明を完成した。
本発明の電池活物質はC2F単独またはC2FとCF
との混合物を主成分として含み、その粉末Ｘ線回
折図に未反応黒鉛のピークが認められるもの、す
なわちフツ素化されていない黒鉛が残存している
ものである。
このように本発明の電池活物質の特徴とすると
ころは、詳細は不明であるが原料黒鉛が完全には
フツ素化されておらず未反応状態の黒鉛が中央部
付近に残存していることによるものと考えられ
る。したがつて黒鉛がC2F単独またはC2FとCFと
の混合物と単なる混合状態で存在しているのでは
ない。これは、後述の比較例３に示すようにC2F
単独またはC2FとCFとの混合物に原料黒鉛を物
理的に混合したものでは本発明の電池活物質のよ
うな放電電圧を高める効果がえられないことから
わかる（第３図参照）。本発明の電池活物質にお
いては、未反応黒鉛の粉末Ｘ線回折図におけるピ
ークは、（002）面の回折角（2θ）が26.5度付近に
明確に現われる。
この未反応の黒鉛のピークが認められないフツ
化黒鉛の放電電圧は後述の比較例１〜２に示すご
とく本発明の電池活物質の放電電圧よりも低いも
のでしかない（第３図参照）。
本発明に用いるフツ化黒鉛はフツ素含量45％
（重量％、以下同様）以上（微粉状C2F表面のＣ
の末端基にＦが２個以上結合した、いわゆる
The present invention relates to battery active materials. More specifically, graphite fluoride (hereinafter referred to as
The main component is C 2 F alone or a mixture of C 2 F and graphite fluoride (hereinafter referred to as CF) represented by the formula (CF) o , and a peak of unreacted graphite is observed in the powder X-ray diffraction diagram. The present invention relates to battery active materials. It is known that CF or C 2 F is useful as a battery active material. For example, JP-A-54-9730 describes that CF obtained by using petroleum coke as raw carbon has good discharge characteristics and storage characteristics. Also, JP-A-53-102893 and JP-A-55
-28246, Franklin's P of about 0 to 0.6
The fluorinated graphite represented by (C 2 F) o is obtained by reacting graphite having a certain value with fluorine gas of 100 to 760 mmHg at a temperature of 300 to 500°C until the graphite is completely fluorinated. It is described that it is useful as a battery active material. The inventors of the present invention have conducted intensive research to create a battery active material with even better discharge characteristics, and as a result, a C 2 F alone or C 2 F
We discovered that a battery active material whose main component is a mixture of fluorinated graphite and CF, and whose powder X-ray diffraction pattern shows a peak of unreacted graphite, has a higher discharge potential than the conventional graphite fluoride. Completed the invention. The battery active material of the present invention is C 2 F alone or C 2 F and CF.
The main component is a mixture of fluorinated graphite, and a peak of unreacted graphite is observed in the powder X-ray diffraction diagram, that is, unfluorinated graphite remains. As described above, a feature of the battery active material of the present invention is that, although the details are unknown, the raw material graphite is not completely fluorinated and unreacted graphite remains near the center. This is thought to be due to Therefore, graphite does not simply exist in a mixed state with C 2 F alone or with a mixture of C 2 F and CF. This is due to C 2 F as shown in Comparative Example 3 below.
This can be seen from the fact that graphite alone or a mixture of C 2 F and CF physically mixed with raw material graphite does not have the effect of increasing the discharge voltage like the battery active material of the present invention (see Figure 3). In the battery active material of the present invention, a peak in the powder X-ray diffraction diagram of unreacted graphite clearly appears at a diffraction angle (2θ) of the (002) plane of around 26.5 degrees. The discharge voltage of fluorinated graphite, in which the peak of unreacted graphite is not observed, is only lower than the discharge voltage of the battery active material of the present invention, as shown in Comparative Examples 1 and 2 described later (see Figure 3). . The fluorinated graphite used in the present invention has a fluorine content of 45%.
(wt%, same below) or more (fine powder C 2 F surface C
Two or more Fs are bonded to the terminal group of the so-called
【式】【formula】
【式】結合によつてもＦが結合しうる
ため、C2FとしてのＦ含有率約44.2％よりも高い
45％以上のＦ含有率でも未反応黒鉛が残存するば
あいがある）であり、58％以下であるのが好まし
い。フツ素含量の下限の45％という値は放電電圧
との関連では重要な限界ではないが、45未満のと
きは一般に電池容量が小さくなりすぎ、電池活物
質としての使用には望ましくない。58％を超える
ときは反応時に殆んどの黒鉛がフツ素化されてし
まい、未反応黒鉛を残すことが実質上できず、目
的とする放電電圧の向上効果がえられない。
本発明の電池活物質は、フツ化黒鉛部分に基づ
く粉末Ｘ線回折における（001）面の回折角（2θ）
のピークが9.9〜14.5度に現われ、ばあいによつ
ては10度付近にC2Fを示すピークまたはシヨルダ
ーが、また12〜14.5度付近にCFを示すピークま
たはシヨルダーが現われることがある。
本発明の電池活物質のフツ化黒鉛部分に基づく
粉末Ｘ線回折図の代表的な例を第４図に示す。ピ
ークが前記の範囲をはずれるときは、いずれも本
発明の目的とする放電電圧の向上効果がえられな
い。
本発明に用いる原料黒鉛としては、たとえば天
然黒鉛、人造黒鉛、人造鱗状黒鉛（たとえばロン
ザ社製KSシリーズ、Ｔシリーズなど）などがあ
げられる。
本発明の電池活物質は、原料黒鉛をフツ素ガス
（必要に応じフツ素ガスは希釈ガスと混合して用
いられる）によりフツ素化して製造される。
フツ素ガスまたはフツ素ガスと稀釈ガスとの混
合ガスは、フツ素ガスの分圧が0.1〜1atmとなる
ように反応器に室温で導入される。温度は室温か
ら徐々に昇温し、目的とする反応温度すなわち
300〜550℃、好ましくは330〜450℃に保持する。
反応はフツ素の消費量を経時的に測定しながら
行ない、その量から求めた反応進行度の変化率が
零になるまえに反応を停止する。
C2Fの生成は種々の要因によつて影響される
が、たとえば高温で反応せしめるほどCF／C2F
比が増大する。しかし、いずれのCF／C2F比の
ばあいでも、未反応の黒鉛は残さなければならな
い。
反応時間は原料黒鉛の結晶化度、粒子径、フツ
素ガスの圧力、反応温度などにより変わるが、通
常反応温度380℃では10〜50時間である。この反
応時間は従来のフツ化黒鉛を製造するばあいの同
温度での反応時間100〜200時間の1/4〜1/10であ
り、生産効率を大幅に向上せしめることができ
る。
原料黒鉛は通常反応温度で脱気し、水分を除去
しておくことが好ましい。
フツ素ガスと混合する稀釈ガスとしてはフツ素
および黒鉛と反応しないガスを用いる。具体例と
しては、たとえばチツ素ガス、パーフルオロカー
ボン、稀ガスなどがあげられる。
本発明の電池活物質にバインダ、導電材を配合
して電極材がえられる。それらの配合割合は、フ
ツ化黒鉛10部（重量部、以下同様）、バインダ１
〜４部、導電材0.5〜２部であるのが好ましい。
バインダとしては、たとえばポリテトラフルオ
ロエチレン（PTFE）などがあげられ、導電材と
してはたとえばアセチレンブラツク、ケツチエン
ブラツクなどの高電気伝導性のカーボンブラツク
あるいは天然黒鉛などがあげられる。
本発明の電池活物質を電池に用いるばあい、本
発明の電池活物質を正極とし、負極にたとえばリ
チウム、マグネシウム、カルシウム、アルミニウ
ムを単独またはこれらを主成分とする合金を用い
ることが好ましい。電解質としては用いる負極の
種類にもよるが、通常非水系を用いる。
本発明の電池活物質はフツ化黒鉛が有するすぐ
れた電池特性を保持したまま、未反応の黒鉛が残
つているにもかかわらず従来のフツ化黒鉛を用い
るばあいよりも放電電圧を高めることができると
いう驚くべき効果を奏するものである。しかも用
いるフツ化黒鉛が従来のものよりも1/4〜1/10と
いう短時間で製造できるため、生産効率も大幅に
向上せしめることができる。
つぎに実施例をあげて本発明の電池活物質を説
明するが、本発明はかかる実施例のみに限定され
るものではない。
実施例 １
マダガスカル産天然黒鉛（平均粒子径10μ）を
反応器に入れ380℃で30分間脱気して水分を除去
したのち、室温に冷却した。
ついでフツ素ガス（100％）を1atmで反応器に
導入し、380℃にまで昇温してフツ素ガスの消費
量を測定しながら反応せしめた。フツ素含量が
49.1％に達したとき反応を停止し（反応開始後20
時間経過していた）、やや灰色がかつた黒色粉末
状の生成物をえた。その比表面積は22.9m2／ｇ、
見掛比重は0.46であつた。このものの粉末Ｘ線回
析図を第１図に示す。
第１図に示すごとく、フツ化黒鉛に基づく
（001）面の回折線が10.62度付近に、黒鉛に基づ
く（002）面の回折線が26.55度付近に認められ、
両ピークの高さの比（フツ化黒鉛：黒鉛）は１：
１であつた。
粉末Ｘ線回折は、理学電気(株)製のGeigerflex
Rad 1A（スリツト系、DS：１度、RS：0.15mm、
SS：１度）を用い、Cukα線で電圧40KV、電流
30ｍＡ、0.05度ステツプ（１ステツプは4.0秒）
のステツプスキヤンで測定した。なお、Kβ線を
除くためにニツケルフイルタを用い、また2θ値は
ピークの両側の変曲点の中点とした。
ついでこの生成物10部、PTFE3部およびアセ
チレンブラツク１部を充分混練してニツケル網上
にプレスし、表面積1.57cm2の正極を作製した。負
極としてはリチウムのブロツクから表面積１cm2、
厚さ１mmに切り出し、それをニツケル網で保持し
たものを用い、電解質には１モルのホウフツ化リ
チウムのγ−ブチロラクトン溶液を用いた。放電
電圧の測定は25℃にて10KΩの定抵抗放電で行な
つた。えられた放電時間と端子電圧との関係を第
３図に示す。
実施例 ２
反応を400℃で15時間行なつたほかは実施例１
と同様に操作し、実施例１と同様の粉末状生成物
をえた。元素分析の結果フツ素含有量は50.5％で
あつた。これの粉末Ｘ線回折を行なつたところ、
フツ化黒鉛に基づく（001）面の回折線が10.50度
付近に、黒鉛に基づく（002）面の回折線が26.55
度付近に認められた。このものの粉末Ｘ線回折図
を第２図に示す。
比較例 １
反応を140時間（フツ素の消費は約100時間で終
了）行なつたほかは実施例１と同様にして反応を
行ない黒灰色粉末状の生成物をえた。元素分析の
結果フツ素含量は51.5％、見掛比重0.46、比表面
積50m2／ｇであつた。このものを粉末Ｘ線回折で
分析したところ、フツ化黒鉛に基づく（001）面
の回折線が10.08度に認められたが、黒鉛に基づ
く回折線は認められなかつた。
この生成物を用い実施例１と同様にして電池を
作製し、実施例１と同様にして放電電圧を調べ
た。えられた放電時間と端子電圧の関係を第３図
に示す。
比較例 ２
石油コークス（平均粒径10μ）を実施例１と同
様に反応器内で前処理し、フツ素ガス10％とチツ
素ガス90％の混合ガス（フツ素分圧0.1atm）を
導入し、400℃にてフツ素が消費されなくなるま
で反応を行なつた。反応時間は4.5時間であつた。
生成物は淡灰色の粉体であり、フツ素含量62.3
％、比表面積200m2／ｇ、見掛密度0.52であつた。
このものを粉末Ｘ線回折で分析したところ、フツ
化黒鉛に基づく（001）面の回折線が12.9度に認
められたが、黒鉛に基づく回折線は認められなか
つた。
この生成物を用い実施例１と同様にして電池を
作製し、実施例１と同様にして放電電圧を調べ
た。えられた放電時間と端子電圧との関係を第３
図に示す。
比較例 ３
比較例１でえられた生成物に２％の原料黒鉛を
添加し、機械的に混合したものを用いたほかは実
施例１と同様に電池を作製し、実施例１と同様に
して放電電圧を調べた。えられた放電時間と端子
電圧の閑係を第３図に示す。
第３図から明らかなとおり、フツ素含量が51.5
％で未反応黒鉛に基づく（002）面のＸ線回折線
が認められない比較例１の電池活物質に対して、
実施例１の電池活物質はフツ素含量が49.1％と低
いものであつても放電電圧が約150ｍＶも高いも
のである。
また単に原料黒鉛を物理的に混合しただけで
は、比較例３におけるごとくまつたく比較例１と
変化なく、放電電圧の向上がみられない。
さらに比較例２に示すごとく、未反応黒鉛を含
まないフツ素含量62.3％の電池活物質では、比較
例１および３よりもさらに放電初期の電圧が約
110ｍＶも低くなる。
なお、本発明の電池活物質を各種製造し、粉末
Ｘ線回析を行なつた。えられた結果のうち代表的
なもののフツ化黒鉛部分の回析図を第４図に示
す。[Formula] Since F can also be bonded through bonding, the F content as C 2 F is higher than approximately 44.2%.
Even if the F content is 45% or more, unreacted graphite may remain in some cases), and the F content is preferably 58% or less. Although the lower limit of the fluorine content of 45% is not an important limit in relation to the discharge voltage, when it is less than 45%, the battery capacity is generally too small and is not desirable for use as a battery active material. If it exceeds 58%, most of the graphite will be fluorinated during the reaction, leaving virtually no unreacted graphite, and the desired effect of improving the discharge voltage will not be achieved. The battery active material of the present invention has a diffraction angle (2θ) of the (001) plane in powder X-ray diffraction based on the graphite fluoride portion.
A peak or shoulder indicating C 2 F appears around 10 degrees, and a peak or shoulder indicating CF appears around 12 degrees to 14.5 degrees depending on the case. A typical example of a powder X-ray diffraction pattern based on the graphite fluoride portion of the battery active material of the present invention is shown in FIG. When the peak is outside the above range, the effect of improving the discharge voltage, which is the objective of the present invention, cannot be obtained. Examples of the raw material graphite used in the present invention include natural graphite, artificial graphite, and artificial scaly graphite (eg, Lonza's KS series, T series, etc.). The battery active material of the present invention is produced by fluorinating raw material graphite with fluorine gas (if necessary, the fluorine gas is mixed with a diluent gas). Fluorine gas or a mixed gas of fluorine gas and diluent gas is introduced into the reactor at room temperature so that the partial pressure of fluorine gas is 0.1 to 1 atm. The temperature is gradually raised from room temperature until the desired reaction temperature, i.e.
The temperature is maintained at 300-550°C, preferably 330-450°C. The reaction is carried out while measuring the amount of fluorine consumed over time, and the reaction is stopped before the rate of change in the degree of reaction progress determined from the amount becomes zero. The generation of C 2 F is influenced by various factors, but for example, the higher the reaction temperature, the more CF/C 2 F
ratio increases. However, for any CF/C 2 F ratio, unreacted graphite must remain. The reaction time varies depending on the crystallinity of the raw graphite, the particle size, the pressure of fluorine gas, the reaction temperature, etc., but is usually 10 to 50 hours at a reaction temperature of 380°C. This reaction time is 1/4 to 1/10 of the conventional reaction time of 100 to 200 hours at the same temperature when producing fluorinated graphite, and production efficiency can be greatly improved. The raw material graphite is preferably degassed at the normal reaction temperature to remove moisture. As the diluent gas to be mixed with the fluorine gas, a gas that does not react with fluorine and graphite is used. Specific examples include nitrogen gas, perfluorocarbon, rare gas, and the like. An electrode material can be obtained by blending a binder and a conductive material with the battery active material of the present invention. Their blending ratio is 10 parts of fluorinated graphite (by weight, the same applies hereinafter), 1 part of binder.
-4 parts, preferably 0.5-2 parts of the conductive material. Examples of the binder include polytetrafluoroethylene (PTFE), and examples of the conductive material include highly electrically conductive carbon black such as acetylene black and Kettien black, or natural graphite. When the battery active material of the present invention is used in a battery, it is preferable to use the battery active material of the present invention as a positive electrode and to use, for example, lithium, magnesium, calcium, aluminum alone or an alloy containing these as main components for the negative electrode. Although it depends on the type of negative electrode used as the electrolyte, a non-aqueous electrolyte is usually used. The battery active material of the present invention maintains the excellent battery properties of graphite fluoride, and can increase the discharge voltage more than when conventional graphite fluoride is used, even though unreacted graphite remains. It has an amazing effect. Moreover, since the graphite fluoride used can be produced in a time of 1/4 to 1/10 compared to conventional products, production efficiency can be greatly improved. Next, the battery active material of the present invention will be explained with reference to Examples, but the present invention is not limited to these Examples. Example 1 Natural graphite from Madagascar (average particle size 10 μm) was placed in a reactor and degassed at 380° C. for 30 minutes to remove moisture, and then cooled to room temperature. Next, fluorine gas (100%) was introduced into the reactor at 1 atm, the temperature was raised to 380°C, and the reaction was carried out while measuring the amount of fluorine gas consumed. Fluorine content
The reaction was stopped when it reached 49.1% (20
(after some time had elapsed), a slightly grayish black powder was obtained. Its specific surface area is 22.9m 2 /g,
The apparent specific gravity was 0.46. A powder X-ray diffraction diagram of this product is shown in FIG. As shown in Figure 1, the diffraction line of the (001) plane based on graphite fluoride is observed around 10.62 degrees, and the diffraction line of the (002) plane based on graphite is observed around 26.55 degrees.
The ratio of the heights of both peaks (graphite fluoride: graphite) is 1:
It was 1. Powder X-ray diffraction was performed using Geigerflex manufactured by Rigaku Denki Co., Ltd.
Rad 1A (slit type, DS: 1 degree, RS: 0.15mm,
SS: 1 degree), voltage 40KV and current with Cukα line
30mA, 0.05 degree steps (1 step is 4.0 seconds)
Measured using step scan. A Nickel filter was used to remove Kβ rays, and the 2θ value was set at the midpoint between the inflection points on both sides of the peak. Next, 10 parts of this product, 3 parts of PTFE, and 1 part of acetylene black were thoroughly kneaded and pressed onto a nickel mesh to prepare a positive electrode with a surface area of 1.57 cm 2 . As a negative electrode, the surface area is 1 cm 2 from a lithium block,
A piece cut out to a thickness of 1 mm and held with a nickel mesh was used, and a 1 mol γ-butyrolactone solution of lithium borofluoride was used as the electrolyte. The discharge voltage was measured at 25°C with a constant resistance discharge of 10KΩ. The relationship between the obtained discharge time and terminal voltage is shown in FIG. Example 2 Example 1 except that the reaction was carried out at 400°C for 15 hours.
The same procedure as in Example 1 was carried out to obtain a powdery product similar to that in Example 1. As a result of elemental analysis, the fluorine content was 50.5%. When I performed powder X-ray diffraction on this, I found that
The diffraction line of the (001) plane based on graphite fluoride is around 10.50 degrees, and the diffraction line of the (002) plane based on graphite is around 26.55 degrees.
It was found to be close to 100%. The powder X-ray diffraction pattern of this product is shown in FIG. Comparative Example 1 The reaction was carried out in the same manner as in Example 1, except that the reaction was carried out for 140 hours (the consumption of fluorine was completed in about 100 hours), and a black-gray powder product was obtained. As a result of elemental analysis, the fluorine content was 51.5%, the apparent specific gravity was 0.46, and the specific surface area was 50 m 2 /g. When this product was analyzed by powder X-ray diffraction, a diffraction line of the (001) plane based on graphite fluoride was observed at 10.08 degrees, but a diffraction line based on graphite was not observed. A battery was produced using this product in the same manner as in Example 1, and the discharge voltage was examined in the same manner as in Example 1. The relationship between the discharge time and terminal voltage obtained is shown in FIG. Comparative Example 2 Petroleum coke (average particle size 10μ) was pretreated in a reactor in the same manner as in Example 1, and a mixed gas of 10% fluorine gas and 90% nitrogen gas (fluorine partial pressure 0.1 atm) was introduced. The reaction was then carried out at 400°C until fluorine was no longer consumed. The reaction time was 4.5 hours.
The product is a light gray powder with a fluorine content of 62.3
%, specific surface area of 200 m 2 /g, and apparent density of 0.52.
When this product was analyzed by powder X-ray diffraction, a diffraction line of the (001) plane based on graphite fluoride was observed at 12.9 degrees, but a diffraction line based on graphite was not observed. A battery was produced using this product in the same manner as in Example 1, and the discharge voltage was examined in the same manner as in Example 1. The relationship between the obtained discharge time and terminal voltage is expressed in the third
As shown in the figure. Comparative Example 3 A battery was produced in the same manner as in Example 1, except that 2% raw graphite was added to the product obtained in Comparative Example 1 and mechanically mixed. The discharge voltage was investigated. Figure 3 shows the relationship between the discharge time and terminal voltage obtained. As is clear from Figure 3, the fluorine content is 51.5
%, compared to the battery active material of Comparative Example 1 in which no X-ray diffraction line of the (002) plane was observed based on unreacted graphite.
Even though the battery active material of Example 1 has a low fluorine content of 49.1%, the discharge voltage is as high as about 150 mV. Furthermore, simply by physically mixing the raw material graphite, as in Comparative Example 3, there was no significant change from Comparative Example 1, and no improvement in discharge voltage was observed. Furthermore, as shown in Comparative Example 2, in a battery active material with a fluorine content of 62.3% that does not contain unreacted graphite, the voltage at the initial stage of discharge is even lower than in Comparative Examples 1 and 3.
It becomes 110mV lower. Note that various battery active materials of the present invention were manufactured and subjected to powder X-ray diffraction. FIG. 4 shows a typical diffraction diagram of the fluorinated graphite portion of the results obtained.
【図面の簡単な説明】[Brief explanation of drawings]
第１図は実施例１でえられた本発明の電池活物
質の粉末Ｘ線回折図、第２図は実施例２でえられ
た本発明の電池活物質の粉末Ｘ線回折図、第３図
は実施例１および比較例１〜３でそれぞれ作製し
た電池の放電時間と端子電圧との関係を示すグラ
フ、第４図は本発明の電池活物質のフツ化黒鉛部
分に基づく代表的な粉末Ｘ線回折図である。
FIG. 1 is a powder X-ray diffraction diagram of the battery active material of the present invention obtained in Example 1, FIG. 2 is a powder X-ray diffraction diagram of the battery active material of the present invention obtained in Example 2, and FIG. The figure is a graph showing the relationship between discharge time and terminal voltage of the batteries prepared in Example 1 and Comparative Examples 1 to 3, respectively. Figure 4 is a graph showing a representative powder based on the graphite fluoride portion of the battery active material of the present invention. It is an X-ray diffraction diagram.