JP6757704B2 - Method for manufacturing negative electrode active material for lithium ion capacitors - Google Patents

Description

本発明は、リチウムイオンキャパシタに用いられる負極活物質の製造方法に関する。 The present invention relates to a method for producing a negative electrode active material used in a lithium ion capacitor.

リチウムイオンキャパシタは、正極に活性炭、負極にプレドープした炭素材料を使用し、リチウムイオン電池と電気二重層キャパシタの特質を併せ持つデバイスであり、リチウムイオン電池に比べて出力密度が高く、電気二重層キャパシタに比べてエネルギー密度が高いことから、風力発電、太陽光発電における電力平準化、瞬時電圧低下補償装置、フォークリフト等の建設機械、交通・輸送関係の各種移動体などの分野で利用が期待されている。 A lithium-ion capacitor is a device that uses activated carbon for the positive electrode and a pre-doped carbon material for the negative electrode, and has the characteristics of a lithium-ion battery and an electric double-layer capacitor. It has a higher output density than a lithium-ion battery and is an electric double-layer capacitor. Since the energy density is higher than that of the above, it is expected to be used in fields such as wind power generation, power leveling in solar power generation, instantaneous voltage drop compensation device, construction machinery such as forklifts, and various moving objects related to transportation. There is.

交通・輸送分野の自動車用電源としてリチウムイオン電池が広く利用されているが、高出力特性に難点があり、また充放電を繰り返すと劣化するという問題がある。これ補完できると思われる電気二重層キャパシタは、出力特性や充放電の繰り返し特性は満足できるものの、エネルギー密度が十分に高くないという難点がある。
これに対し予め負極材料にリチウムイオンをドープ（プレドープ）した炭素材料を用いたリチウムイオンキャパシタは、負極を高容量化、低電位化できるため、エネルギー密度を従来の電気二重層キャパシタの４倍以上にでき、高温負荷や、長期の充放電サイクルなどにも優れた特性を発揮するとされている。 Lithium-ion batteries are widely used as a power source for automobiles in the transportation field, but they have a problem of high output characteristics and deterioration when charging and discharging are repeated. The electric double layer capacitor, which seems to be able to complement this, is satisfied with the output characteristics and the repetitive charge / discharge characteristics, but has a drawback that the energy density is not sufficiently high.
On the other hand, a lithium ion capacitor using a carbon material in which lithium ions are pre-doped into the negative electrode material in advance can increase the capacity and lower the potential of the negative electrode, so that the energy density is four times or more that of a conventional electric double layer capacitor. It is said that it exhibits excellent characteristics even in high temperature loads and long-term charge / discharge cycles.

リチウムイオンキャパシタの従来の負極活物質には、ハードカーボン、ソフトカーボン等の比較的結晶性の低い材料が使用されていたこともあり、負極活物質の内部抵抗を十分に低く抑えることは困難であり、期待される用途の内の一部の利用に止まっていた。 Since materials with relatively low crystallinity such as hard carbon and soft carbon have been used for the conventional negative electrode active material of lithium ion capacitors, it is difficult to keep the internal resistance of the negative electrode active material sufficiently low. Yes, it was limited to some of the expected uses.

リチウムイオンキャパシタの普及を図るうえでも負極活物質の内部抵抗を十分に低く抑えることが必要であり、その手段の一つとして負極活物質である炭素材料の電気抵抗値を低く抑えることも必要である。 In order to popularize lithium ion capacitors, it is necessary to keep the internal resistance of the negative electrode active material sufficiently low, and as one of the means, it is also necessary to keep the electrical resistance value of the carbon material, which is the negative electrode active material, low. is there.

特開２００８−１３０８９０号公報JP-A-2008-130890 特許第５０４１３５１号公報Japanese Patent No. 5041351 特開２０１５−７００３２号公報Japanese Unexamined Patent Publication No. 2015-70032

炭素学 基礎物性から応用展開まで、田中和義他、化学同人（２０１１）From basic physical properties to application development, Kazuyoshi Tanaka et al., Kagaku-Dojin (2011) 新・炭素工業 石川敏功、長沖 通、近代編集社（昭和５５年）New Carbon Industry Toshinori Ishikawa, Michi Nagaoki, Modern Editing Company (1980) 新・炭素材料入門 炭素材料学会編（１９９６）Introduction to New Carbon Materials Society of Carbon Materials (1996) 炭素材料工学 稲垣道夫、日刊工業社（昭和６０年）Carbon Materials Engineering Michio Inagaki, Nikkan Kogyosha (1985)

従来、リチウムイオンキャパシタの負極活物質として用いられてきたのは、フェノール樹脂、フラン樹脂、及び光学的等方性ピッチの溶融時に空気を吹き込む等して架橋構造を付加した後に炭素化して得たハードカーボン、ピッチを炭素化して得たソフトカーボン、もしくはカーボンブラックやこれらの複合物等の高速充放電に対応可能な結晶性の低い材料である。高速充放電に対応する効果を高めるため、活物質の粒子径を小さくしたり、比表面積を大きくする工夫もとられている。ところが結晶性が低く比較的電気抵抗値が高い材料であるため、リチウムイオンキャパシタの内部抵抗が高いものとなる。
本発明は、これに対して、リチウムイオンキャパシタの性能に影響を与えずにリチウムイオンキャパシタの内部抵抗を低下させ、リチウムイオンキャパシタの高容量化とエネルギー密度の向上をもたらすリチウムイオンキャパシタの負極活物質を提供することを目的とする。 Conventionally, the negative electrode active material of a lithium ion capacitor has been obtained by carbonizing after adding a crosslinked structure by blowing air when melting a phenol resin, a furan resin, and an optically isotropic pitch. It is a material having low crystallinity capable of high-speed charging and discharging such as hard carbon, soft carbon obtained by carbonizing pitch, carbon black, and composites thereof. In order to enhance the effect of high-speed charging and discharging, measures have been taken to reduce the particle size of the active material and increase the specific surface area. However, since the material has low crystallinity and a relatively high electrical resistance value, the internal resistance of the lithium ion capacitor is high.
On the other hand, the present invention reduces the internal resistance of the lithium ion capacitor without affecting the performance of the lithium ion capacitor, and brings about an increase in the capacity of the lithium ion capacitor and an improvement in energy density. The purpose is to provide the substance.

Ｘ線回折による炭素結晶網面層の面間距離ｄ_{（００２）}が０．３４００〜０．３７７０ｎｍの低結晶炭素粒子の内部にｄ_{（００２）}が０．３３５４〜０．３３６０ｎｍ、平均粒子径が０．８〜３．０μｍの黒鉛粒子を少なくとも一粒子包含する複合粒子で、平均粒子径２．０〜６．０μｍ、最大粒子径５０μｍ以下、ＢＥＴ法比表面積５．０〜１５．０ｍ^２／ｇ、孔径２ｎｍ以下のマイクロ孔の細孔容積が全細孔容積の２％以下、液体窒素温度における窒素の吸脱着による窒素ガスの最大吸着量１０ｃｍ^３／ｇ以上、亜麻仁油吸油量９０〜１５０ｍｌ／１００g、タップ密度０．２５ｇ／ｃｍ^３以上であるリチウムイオンキャパシタ用負極活物質である。 The interplanetary distance d ₍₀₀₂₎ of the carbon crystal network layer by X-ray diffraction is 0.3400 to 0.3770 nm inside the low crystal carbon particles, d ₍₀₀₂₎ is 0.3354 to 0.3360 nm, and the average particle diameter is A composite particle containing at least one graphite particle of 0.8 to 3.0 μm, having an average particle diameter of 2.0 to 6.0 μm, a maximum particle diameter of 50 μm or less, and a BET method specific surface area of 5.0 to 15.0 m ² /. g, The pore volume of micropores with a pore diameter of 2 nm or less is 2% or less of the total pore volume, the maximum adsorption amount of nitrogen gas by adsorption and desorption of nitrogen at liquid nitrogen temperature is 10 cm ³ / g or more, and flaxseed oil absorption amount 90 to 150 ml It is a negative electrode active material for a lithium ion capacitor having a tap density of 0.25 g / cm ³ or more and a tap density of 0.25 g / cm.

黒鉛のｄ_{（００２）}は、０．３３５４〜０．３３６０ｎｍであり、電気抵抗率は０．１ｍΩｃｍ（１μΩｍ）と低く、金属と言ってよいほどの値を示す。人造黒鉛の場合は、一般に炭素化温度（黒鉛化温度）が２８００℃以上では、ｄ_{（００２）}は０．３３５４〜０．３３６０ｎｍとなり低い電気抵抗値を示すが、逆に炭素化温度が２８００℃より低くなるに従い、得られた黒鉛の結晶化度は低下していき、これに従ってｄ_{（００２）}は、０．３３６０ｎｍより大きくなり、これに応じて電気抵抗値も増大する。
低結晶炭素とは、炭化温度が８００〜１３００℃であり、ｄ_{（００２）}は０．３４００〜０．３７７０ｎｍとなり電気抵抗値は高くなる。
従来用いられてきた低結晶炭素にｄ_{（００２）}が０．３３５４〜０．３３６０ｎｍである黒鉛粉末を包含させることによって表面状態を変えることなく低抵抗化を達成したものである。 The d _{(002) of} graphite is 0.3354 to 0.3360 nm, and the electrical resistivity is as low as 0.1 mΩcm (1 μΩm), which is a value that can be said to be a metal. In the case of artificial graphite, generally, when the carbonization temperature (graphiteization temperature) is 2800 ° C. or higher, d ₍₀₀₂₎ is 0.3354 to 0.3360 nm, which shows a low electrical resistance value, but conversely, the carbonization temperature is 2800 ° C. As the value becomes lower, the crystallinity of the obtained graphite decreases, and d ₍₀₀₂₎ becomes larger than 0.3360 nm accordingly, and the electric resistance value increases accordingly.
Low crystalline carbon has a carbonization temperature of 800 to 1300 ° C., d ₍₀₀₂₎ of 0.3400 to 0.3770 nm, and a high electrical resistance value.
By including graphite powder having d ₍₀₀₂₎ of 0.3354 to 0.3360 nm in the conventionally used low crystalline carbon, low resistance is achieved without changing the surface state.

低結晶炭素の内部に包含される人造黒鉛又は天然黒鉛の粒子は、負極活物質である炭素材料の電気抵抗値を低く抑える目的のため、結晶化度が高いほど好ましい。即ち炭素網面層の面間距離ｄ_{（００２）}が小さいほど良く、０．３３５４〜０．３３６０ｎｍであるものが適宜選択される。
０．３３５４ｎｍ未満のものは、黒鉛の結晶構造上ありえず、０．３３６０ｎｍより大きいものは、結晶化度が十分に高いとは言えず好ましくない。なお、ｄ_{（００２）}が０．３３５４〜０．３３６０ｎｍの場合、多くは炭素網面層が積層した厚さを示すＬｃ、及び炭素網面の広がりを示すＬａは、１００ｎｍより大となり好ましい。ただし、ＬｃあるいはＬａのどちらか、又はＬｃ及びＬａ共に１００ｎｍに満たない場合でも使用することは可能である。 The particles of artificial graphite or natural graphite contained inside the low crystalline carbon are preferably those having a high degree of crystallinity for the purpose of suppressing the electric resistance value of the carbon material which is the negative electrode active material. That is, the smaller the interplanetary distance d _{(002) of the} carbon network layer is, the better, and those having 0.3354 to 0.3360 nm are appropriately selected.
If it is less than 0.3354 nm, it is impossible due to the crystal structure of graphite, and if it is larger than 0.3360 nm, the crystallinity cannot be said to be sufficiently high and it is not preferable. When d ₍₀₀₂₎ is 0.3354 to 0.3360 nm, Lc indicating the thickness of the laminated carbon network layer and La indicating the spread of the carbon network surface are preferably larger than 100 nm in most cases. However, it is possible to use either Lc or La, or even when both Lc and La are less than 100 nm.

人造黒鉛又は天然黒鉛粒子の粒径は、体積累積平均粒子径が、０．８〜３．０μｍであることが好ましい。０．８μｍより小さいものは工業的に量産するのが難しいため入手困難であり、３．０μｍより大きいと焼成後の粉砕で目的の粒径を得るために低結晶炭素に包含されている黒鉛粒子自体までも粉砕してしまい、活性な粉砕面が露出し、電解液の分解、ガス発生を促すので好ましくない。また用いる黒鉛粒子の形状については特に限定するものではなく、扁平状、破砕状、球状、繊維状、及びその他の形状のものを使用しても特に問題になることはない。黒鉛粒子の形状により吸油量や比表面積が異なるので、ピッチと黒鉛粒子の配合量を適宜調整する必要がある。
また黒鉛粒子は、人造黒鉛、天然黒鉛それぞれ単独で用いても、併用しても、粒度の異なる２種以上を併用しても、粒形及び種類の異なる２種以上を併用してもよい。 The particle size of the artificial graphite or natural graphite particles preferably has a volume cumulative average particle size of 0.8 to 3.0 μm. Those smaller than 0.8 μm are difficult to obtain because it is difficult to mass-produce them industrially, and those larger than 3.0 μm are graphite particles contained in low crystalline carbon in order to obtain the desired particle size by pulverization after firing. Even itself is crushed, the active crushed surface is exposed, and decomposition of the electrolytic solution and gas generation are promoted, which is not preferable. Further, the shape of the graphite particles to be used is not particularly limited, and flat, crushed, spherical, fibrous, and other shapes may be used without any particular problem. Since the oil absorption amount and the specific surface area differ depending on the shape of the graphite particles, it is necessary to appropriately adjust the pitch and the blending amount of the graphite particles.
Further, as the graphite particles, artificial graphite and natural graphite may be used alone, in combination, two or more kinds having different particle sizes may be used in combination, or two or more kinds having different grain shapes and types may be used in combination.

低結晶炭素の前駆体として用いるピッチは、人造黒鉛電極等の一般的な人造黒鉛材を製造する場合に用いるバインダーピッチが適当であり、密度は１．２６〜１．３０ｇ／ｃｍ^３、軟化点が８０〜１２０℃、含有するキノリン不溶分が７〜１５％、トルエン不溶分が２５〜４０％、固定炭素は５３〜６５％である。
また、一般に軟化点が８０〜１２０℃のバインダーピッチを８００〜１２００℃で炭化した場合の残炭率は、概ね６５〜７０％である。 As the pitch used as a precursor of low crystalline carbon, the binder pitch used when producing a general artificial graphite material such as an artificial graphite electrode is suitable, the density is 1.26 to 1.30 g / cm ³ , and the softening point. The temperature is 80 to 120 ° C., the quinoline insoluble content is 7 to 15%, the toluene insoluble content is 25 to 40%, and the fixed carbon content is 53 to 65%.
Further, in general, when a binder pitch having a softening point of 80 to 120 ° C. is carbonized at 800 to 1200 ° C., the residual carbonization ratio is approximately 65 to 70%.

ピッチと黒鉛粒子の配合については、重量換算で、炭化後のピッチの残炭率を考慮するとピッチ１００重量部に対して黒鉛粒子が２５０〜５００重量部が好ましく、より好ましくは３００〜４００重量部である。黒鉛粒子が５００重量部より多いと低結晶炭素中に黒鉛粒子を十分に包含させることが難しい。黒鉛粒子の一部でも露出したまま負極を作成した場合、負極上で電解液の分解を十分に抑制することが難しくガス発生を防ぎにくくなるので好ましくなく、２５０重量部より少ないと焼成品が硬い大きな塊となり、粉砕しづらくなるとともに粉砕により目的の粒径を得るために低結晶炭素中に包含された黒鉛粒子自体までも粉砕され、また、ピッチ由来の低結晶炭素の粉砕頻度も高くなり、比表面積が大きくなるなどして電解液の分解を促すので好ましくない。 Regarding the composition of the pitch and the graphite particles, in terms of weight, 250 to 500 parts by weight of the graphite particles is preferable with respect to 100 parts by weight of the pitch, and more preferably 300 to 400 parts by weight, considering the residual carbonization ratio of the pitch after carbonization. Is. If the number of graphite particles is more than 500 parts by weight, it is difficult to sufficiently include the graphite particles in the low crystalline carbon. When the negative electrode is prepared with even a part of the graphite particles exposed, it is difficult to sufficiently suppress the decomposition of the electrolytic solution on the negative electrode and it is difficult to prevent gas generation. Therefore, if it is less than 250 parts by weight, the baked product is hard. It becomes a large lump, which makes it difficult to crush, and even the graphite particles themselves contained in the low crystal carbon are crushed in order to obtain the desired particle size by crushing, and the frequency of crushing the low crystal carbon derived from the pitch increases. It is not preferable because it promotes the decomposition of the electrolytic solution by increasing the specific surface area.

炭化によりピッチは、熱分解と重縮合が進行し、有機物であるピッチが無機物である炭素に変化する。用いるピッチの性状及び炭化温度により残炭率は変動するが、一般に軟化点が８０〜１２０℃のバインダーピッチを８００〜１２００℃で炭化した場合の残炭率は、概ね６５〜７０％である。予め残炭率を考慮してピッチと黒鉛粒子の配合量を適宜調整すればよい。低結晶炭素中に本発明において使用する体積累積平均粒子径が、０．８〜３．０μｍの黒鉛粒子を十分に包含させるためには、低結晶炭素と黒鉛粒子の重量比が１対３．５〜１対７．２である。 Due to carbonization, the pitch undergoes thermal decomposition and polycondensation, and the pitch, which is an organic substance, changes to carbon, which is an inorganic substance. The residual carbonization rate varies depending on the properties of the pitch used and the carbonization temperature, but in general, the residual carbonization rate when a binder pitch having a softening point of 80 to 120 ° C. is carbonized at 800 to 1200 ° C. is approximately 65 to 70%. The pitch and the blending amount of the graphite particles may be appropriately adjusted in consideration of the residual coal ratio in advance. In order to sufficiently include graphite particles having a volume cumulative average particle diameter of 0.8 to 3.0 μm used in the present invention in the low crystalline carbon, the weight ratio of the low crystalline carbon to the graphite particles is 1: 3. It is 5 to 1 to 7.2.

本発明は、リチウムイオンキャパシタの内部抵抗を低くすることを目的とするものであり、結晶性が高く電気抵抗値が低い黒鉛粒子を主体の低結晶炭素内に包含させることにより、リチウムイオンキャパシタの内部抵抗の低下をもたらすものである。黒鉛粒子は、その表面でリチウムのプレドープ時に電解液の分解を促進させ、ガス発生の原因となるので、低結晶炭素の内部に包含させて表面に露出することがないようにしたものである。 An object of the present invention is to reduce the internal resistance of a lithium ion capacitor, and by including graphite particles having high crystallinity and a low electric resistance value in the main low crystal carbon, the lithium ion capacitor can be provided. It brings about a decrease in internal resistance. Graphite particles promote the decomposition of the electrolytic solution at the time of pre-doping lithium on the surface thereof and cause gas generation. Therefore, the graphite particles are included inside the low crystalline carbon so as not to be exposed on the surface.

炭素材料における組織は、炭素原子で構成された小さな六角網面が面配向し、その領域がどの程度の大きさで、どのような集合状態であるかで表され、偏光顕微鏡下で異方性を持つ面配向領域の集合体として観察される。具体的には偏光顕微鏡下で観察すれば、光学的異方性の部分は試料台を回転させながら観察すると黄色、ピンク色、青色、再び黄色の順に色が変化するが、等方性の部分はピンク色のままである。
本発明においては、ピッチ由来の低結晶炭素は光学的等方性を示し、これに包含される黒鉛粒子は光学的異方性を示す。本発明により得られた負極活物質粉末を硬化剤が添加されたエポキシ樹脂に分散させた後、放置・硬化・研磨により黒鉛粒子の断面を観察することによって粒子の構造、低結晶炭素中に包含された黒鉛粒子を粒子毎に確認することができる。 The structure of a carbon material is represented by the plane orientation of a small hexagonal network composed of carbon atoms, the size of the region, and the aggregated state, and is anisotropic under a polarizing microscope. It is observed as an aggregate of plane orientation regions with. Specifically, when observed under a polarizing microscope, the optically anisotropic part changes color in the order of yellow, pink, blue, and yellow again when observed while rotating the sample table, but the isotropic part. Remains pink.
In the present invention, the low crystalline carbon derived from the pitch exhibits optical isotropic properties, and the graphite particles included therein exhibit optical anisotropy. The negative electrode active material powder obtained by the present invention is dispersed in an epoxy resin to which a curing agent has been added, and then the structure of the particles is included in the low crystalline carbon by observing the cross section of the graphite particles by leaving, curing, and polishing. The graphite particles can be confirmed for each particle.

高速充放電に対応する効果を高めるため、有効な大きさの細孔が寄与する比表面積が大きいことも大切である。
本発明の負極活物質の細孔構造は、図１に示されるように、液体窒素温度における窒素ガスの吸脱着における等温吸着線において、窒素ガスの相対圧（Ｐ／Ｐ_０）が、０．８前後までは窒素ガスの吸着量が少なく、０．８を超えると急激に増大する。
窒素ガスの吸脱着における等温吸着線において、窒素ガスの相対圧（Ｐ／Ｐ_０）が、０．９９付近で窒素ガスの吸着量が１０ｃｍ^３／ｇ以上である。
ＢＥＴ法比表面積は、５．０〜１５．０ｍ^２／ｇである。
細孔直径２ｎｍ以下のマイクロ孔の比表面積０．５ｍ^２／ｇ以下、マイクロ孔の細孔容積が、全細孔容積の２％以下である。 It is also important that the specific surface area contributed by the pores of effective size is large in order to enhance the effect corresponding to high-speed charging and discharging.
In the pore structure of the negative electrode active material of the present invention, as shown in FIG. 1, the relative pressure (P / P ₀ ) of nitrogen gas is ₀ in the isotherm adsorption isotherm in the adsorption / desorption of nitrogen gas at the liquid nitrogen temperature. The amount of nitrogen gas adsorbed is small up to around 8, and increases sharply when it exceeds 0.8.
In the isotherm adsorption line for adsorption and desorption of nitrogen gas, the relative pressure (P / P ₀ ) of nitrogen gas is around 0.99, and the adsorption amount of nitrogen gas is 10 cm ³ / g or more.
The BET method specific surface area is 5.0 to 15.0 m ² / g.
The specific surface area of the micropores having a pore diameter of 2 nm or less is 0.5 m ² / g or less, and the pore volume of the micropores is 2% or less of the total pore volume.

本発明の負極活物質の粒度分布は、体積累積平均粒子径が、０．８〜３．０μｍの黒鉛粒子を低結晶炭素に包含させて成る複合粒子として、より効果的に高速充放電に対応させるため、製造可能な粒子径を考慮すると、Ｄ_１０が１．０〜３．５μｍ、Ｄ_５０（平均粒子径）が２．０〜６．０μｍ、Ｄ_９０が４．０〜１５．０μｍ、Ｄ_１００（最大粒子径）が５０μｍ以下である。 The particle size distribution of the negative electrode active material of the present invention corresponds to high-speed charging and discharging more effectively as composite particles formed by including graphite particles having a volume cumulative average particle diameter of 0.8 to 3.0 μm in low crystalline carbon. Considering the particle size that can be produced, D ₁₀ is 1.0 to 3.5 μm, D ₅₀ (average particle size) is 2.0 to 6.0 μm, and D ₉₀ is 4.0 to 15.0 μm. D ₁₀₀ (maximum particle size) is 50 μm or less.

本発明の負極活物質は、バインダー、導電助剤、及び分散媒を混合してスラリーを調製後金属箔の集電体に塗布するが、この際分散安定性の良いスラリーを作ることが大切である。また活物質に求められる特性指標としては吸油量が挙げられ、スラリーの分散安定性や、塗布直後の塗膜のエッジ部の変形を防ぐためには適当な吸油量範囲があり、亜麻仁油吸油量９０〜１５０ｍｌ／１００gが好ましい。また、この時活物質のタップ密度は、０．２５ｇ／ｃｍ^３以上である。 In the negative electrode active material of the present invention, a binder, a conductive auxiliary agent, and a dispersion medium are mixed to prepare a slurry, which is then applied to a metal leaf current collector. At this time, it is important to prepare a slurry having good dispersion stability. is there. In addition, the characteristic index required for the active material is the oil absorption amount, and there is an appropriate oil absorption amount range in order to prevent the dispersion stability of the slurry and the deformation of the edge portion of the coating film immediately after application, and the linseed oil oil absorption amount is 90. ~ 150 ml / 100 g is preferable. At this time, the tap density of the active material is 0.25 g / cm ³ or more.

本発明のリチウムイオンキャパシタ用負極活物質の製造方法について以下に述べるが、一例を挙げるものであって、必ずしもこの方法に依らずともピッチの内部に黒鉛粒子が少なくとも１粒包含された前駆体が得られるのであれば他の方法を用いても構わない。 The method for producing the negative electrode active material for a lithium ion capacitor of the present invention will be described below, but only an example is given, and a precursor containing at least one graphite particle inside the pitch is not necessarily used by this method. Other methods may be used as long as they can be obtained.

＜混合撹拌＞
ピッチの内部に黒鉛粒子が少なくとも１粒包含された前駆体を得るため、所定量のピッチと黒鉛粒子をピッチの軟化点以上の温度で加熱ニーダー等を用い混合撹拌を行う。軟化点が８０〜１２０℃のピッチが好適に用いられるため、この場合は軟化点以上の温度１４０〜１８０℃で加熱しながら１〜３時間混合撹拌を行う。 <Mixing and stirring>
In order to obtain a precursor in which at least one graphite particle is contained in the pitch, a predetermined amount of pitch and graphite particles are mixed and stirred at a temperature equal to or higher than the softening point of the pitch using a heating kneader or the like. Since a pitch having a softening point of 80 to 120 ° C. is preferably used, in this case, mixing and stirring are performed for 1 to 3 hours while heating at a temperature of 140 to 180 ° C. above the softening point.

＜炭化＞
ピッチと黒鉛粒子の混合撹拌物を炭化するため、金属容器に仕込んで、非酸化性雰囲気中で５〜１０℃/ｈで昇温しながら最終的に８００〜１２００℃で１〜１０時間保持して焼成する。焼成時の雰囲気は、非酸化性雰囲気であれば問題なく、例えば窒素雰囲気、炭酸ガス雰囲気、アルゴン雰囲気、ピッチの熱分解により生じた非酸化性の自己雰囲気が挙げられる。 <Carbonization>
In order to carbonize the mixed mixture of pitch and graphite particles, it is placed in a metal container and held at 800 to 1200 ° C. for 1 to 10 hours while raising the temperature at 5 to 10 ° C./h in a non-oxidizing atmosphere. And bake. The atmosphere at the time of firing has no problem as long as it is a non-oxidizing atmosphere, and examples thereof include a nitrogen atmosphere, a carbon dioxide gas atmosphere, an argon atmosphere, and a non-oxidizing self-atmosphere generated by thermal decomposition of pitch.

＜粉砕＞
焼成により炭化された後、金属容器から取り出して粉砕を行う。最終的にはジェットミル、インペラーミル、ターボミル、ピンミル、ＡＣＭパルベライザー等を使用して時間当たりの投入量、粉砕歯の回転数、連続式またはジェットミルの場合は空気量等を適宜調節して粉砕し、所定に仕上げるが、金属容器から取り出したものが大きな塊である場合は、必要に応じてジョークラッシャー、ロートプレックス、オリエントミル、ハンマークラッシャー等を用いて予備粉砕を行うことができる。
本発明では、株式会社セイシン企業製のインペラーミルＩＭＰ−４００型を粉砕機として使用し、原料投入速度は、３５ｋｇ／ｈ、インペラーの回転数３５６０ｒｐｍ、風量３５ｍ^３／ｍｉｎで実施した。
粉砕時のパワーが不足していると所定の粒度が得られず、逆にパワーが過剰で過粉砕となると低結晶炭素内に包含させた黒鉛粒子の表面あるいは断面が露出するので好ましくない。 <Crushing>
After being carbonized by firing, it is taken out of a metal container and crushed. Finally, use a jet mill, impeller mill, turbo mill, pin mill, ACM palberizer, etc. to appropriately adjust the input amount per hour, the number of rotations of the crushed teeth, and the amount of air in the case of a continuous type or jet mill. However, if the product is a large lump taken out from the metal container, it can be pre-crushed by using a jaw crusher, a rotoplex, an Orient mill, a hammer crusher or the like, if necessary.
In the present invention, an impeller mill IMP-400 manufactured by Seishin Enterprise Co., Ltd. was used as a crusher, and the raw material input speed was 35 kg / h, the impeller rotation speed was 3560 rpm, and the air volume was 35 m ³ / min.
If the power at the time of pulverization is insufficient, a predetermined particle size cannot be obtained, and conversely, if the power is excessive and over-pulverization occurs, the surface or cross section of the graphite particles contained in the low crystal carbon is exposed, which is not preferable.

＜篩＞
粉砕物は、粗粉を含んでいるので、粗粉除去のため目開き３２乃至３８μｍの網を張った振動篩、超音波篩等により処理を行う。なお、気流式の分級機を使うこともできるが、得率の観点からは好ましくない。 <Sieve>
Since the pulverized product contains coarse powder, it is treated with a vibrating sieve, an ultrasonic sieve, or the like having a mesh with an opening of 32 to 38 μm in order to remove the coarse powder. Although an airflow type classifier can be used, it is not preferable from the viewpoint of profitability.

本発明に使用する原料であるピッチ、黒鉛粒子、及び本発明品である低結晶炭素の中に黒鉛粒子を内包するリチウムイオンキャパシタ用負極活物質の各物性、性能はそれぞれ後述する方法により測定した。 The physical properties and performance of the pitch, graphite particles, which are the raw materials used in the present invention, and the negative electrode active material for a lithium ion capacitor, which contains graphite particles in the low crystalline carbon of the present invention, were measured by the methods described below. ..

＜粒度＞
平均粒径、及び粒度分布の測定は、日機装株式会社製レーザー回折式粒度分布測定装置ＭＴ３３００ＥＸを用いて水に分散剤として微量の界面活性剤を添加し、試料を超音波分散させた状態で測定した。試験に供される粉体の全体積を１００％として累積カーブを求め、その累積カーブが小粒子径側から大粒子径側に向けて積算したときの１０、５０、９０、及び１００％となる点の粒子径をそれぞれＤ_１０、Ｄ_５０、Ｄ_９０、Ｄ_１００（μｍ）とした。なお、Ｄ_５０が平均粒径、Ｄ_１００が最大粒子径を表す。 <Particle size>
The average particle size and particle size distribution are measured by adding a small amount of surfactant as a dispersant to water using the laser diffraction type particle size distribution measuring device MT3300EX manufactured by Nikkiso Co., Ltd. and ultrasonically dispersing the sample. did. The cumulative curve is calculated with the total volume of the powders used in the test as 100%, and the cumulative curve is 10, 50, 90, and 100% when integrated from the small particle diameter side to the large particle diameter side. The particle diameters of the points were D ₁₀ , D ₅₀ , D ₉₀ , and D ₁₀₀ (μm), respectively. Note that D ₅₀ represents the average particle size and D ₁₀₀ represents the maximum particle size.

＜ピッチの密度＞
ピッチの密度測定法は、ＪＩＳ Ｋ ２４２５に示されている。軟化点が７０〜９０℃のピッチの密度は、２０℃において、１．２６〜１．２７ｇ／ｃｍ^３である。本発明で用いたピッチは、軟化点が１０５℃であり、密度は１．３０ｇ／ｃｍ^３である。 <Pitch density>
A method for measuring pitch density is shown in JIS K 2425. The density of pitches with softening points of 70 to 90 ° C. is 1.26 to 1.27 g / cm ³ at 20 ° C. The pitch used in the present invention has a softening point of 105 ° C. and a density of 1.30 g / cm ³ .

＜ピッチの軟化点＞
ＪＩＳ Ｋ ２２０７「石油アスファルト」あるいはＪＩＳ Ｋ ２４２５「クレオソート油・加工タール・タールピッチ試験方法（環球法）」に規定された軟化点試験法によりグリセリンを使用して測定した。
環球法では、熱媒体として８０℃までは水、それ以上はグリセリンを使用する。軟化点を測定する自動測定装置も普及していて例えば、田中科学機器製作株式会社製ａｓｐ−６、アントンパールジャパン株式会社製ＲＫＡ５、第一理化株式会社製ＥＸ−７１９ＰＤ４等がある。その他の方法として、ＪＩＳ法とのバイアスを補正したメトラー軟化点測定法による測定も行われている。装置としてはメトラートレド株式会社のＤＰ７０、ＤＰ９０がある。 <Pitch softening point>
Measurement was performed using glycerin by the softening point test method specified in JIS K 2207 "Petroleum asphalt" or JIS K 2425 "Creosote oil / processed tar / tar pitch test method (ring ball method)".
In the ring-and-ball method, water is used as a heat medium up to 80 ° C., and glycerin is used above that. Automatic measuring devices for measuring softening points are also widespread, and examples thereof include asp-6 manufactured by Tanaka Kagaku Kikai Seisakusho Co., Ltd., RKA5 manufactured by Anton Paar Japan K.K., and EX-719PD4 manufactured by Daiichi Rika Co., Ltd. As another method, the measurement by the meterer softening point measurement method in which the bias with the JIS method is corrected is also performed. As the device, there are DP70 and DP90 of METTLER TOLEDO Co., Ltd.

＜負極活物質及び黒鉛粒子の真密度＞
Ｍｉｃｒｏｍｅｒｉｔｉｃｓ社製真密度測定装置ＡｃｃｕＰｙｃ１３３０−１を用いた低容積膨張法（ヘリウムガス置換法）により求めた。 <True density of negative electrode active material and graphite particles>
It was determined by a low volume expansion method (helium gas substitution method) using the true density measuring device AccuPyc1330-1 manufactured by Micromeritics.

＜Ｘ線回折試験結果＞
炭素網面層の面間距離ｄ_{（００２）、}炭素網面層が積層した厚さを示すＬｃ及び炭素網面の広がりを示すＬａは、株式会社リガク製Ｕｌｔｉｍａ３システムにより、ＣｕＫα線を用い、Ｘ線管球への印加電圧は４０ｋＶ、電流は２０ｍＡとした。計数管の走査速度は２°／分、走査範囲は１０°から９０°で、０．０２°間隔で測定した。ｄ_{（００２）}の値は、回折角２θが２６°付近の（００２）面のピークの位置（角度）と、内部標準として予め加えた回折角２θが２８°付近の金属ケイ素の（１１１）面のピーク位置（角度）とから、Ｌｃの値は、回折角２θが２６°付近の（００２）面のピークの半値幅と、内部標準として予め加えた回折角２θが２８°付近の金属ケイ素の（１１１）面のピークの半値幅とから、Ｌａの値は、回折角２θが７７．６°付近の（１１０）面のピークの半値幅と、内部標準として予め加えた回折角２θは７６．４°付近の金属ケイ素の（３３１）面のピークの半値幅とから、それぞれ学振法に基づいて計算して求めた。 <X-ray diffraction test results>
The interplanetary distance d _{(002) of the} carbon network layer, Lc indicating the thickness of the laminated carbon network layer, and La indicating the extent of the carbon network surface are X-rays using CuKα rays by the Ultra3 system manufactured by Rigaku Co., Ltd. The voltage applied to the wire tube was 40 kV, and the current was 20 mA. The scanning speed of the counter was 2 ° / min, the scanning range was 10 ° to 90 °, and measurements were taken at 0.02 ° intervals. The value of d ₍₀₀₂₎ is the position (angle) of the peak of the (002) plane whose diffraction angle 2θ is near 26 ° and the (111) plane of metallic silicon whose diffraction angle 2θ is about 28 °, which is added in advance as an internal standard. From the peak position (angle) of, the Lc value is the half width of the peak of the (002) plane whose diffraction angle 2θ is near 26 ° and the metal silicon whose diffraction angle 2θ is about 28 °, which is added in advance as an internal standard. From the half width of the peak of the (111) plane, the value of La is the half width of the peak of the peak of the (110) plane where the diffraction angle 2θ is around 77.6 °, and the diffraction angle 2θ added in advance as an internal standard is 76. It was calculated from the half width of the peak of the (331) plane of metallic silicon near 4 °, respectively, based on the Gakushin method.

＜比表面積、細孔容積、及び最大吸着量＞
比表面積、細孔容積、及び最大吸着量は、窒素ガスの吸脱着により測定し、測定装置は、Ｍｉｃｒｏｍｅｒｉｔｉｃｓ社製の自動比表面積／細孔分布測定装置ＴｒｉＳｔａｒ３０００を用いて液体窒素温度にて実施した。 <Specific surface area, pore volume, and maximum adsorption amount>
The specific surface area, pore volume, and maximum adsorption amount were measured by adsorption and desorption of nitrogen gas, and the measuring device was carried out at liquid nitrogen temperature using an automatic specific surface area / pore distribution measuring device TriStar3000 manufactured by Micromeritics. ..

比表面積は、吸着等温線から得られた窒素ガス吸着量を、単分子層として評価して計算するＢＥＴの多点法によって求めた。
Ｐ／Ｖ（Ｐ_０−Ｐ）＝（１／ＶｍＣ）＋{（Ｃ−１）／ＶｍＣ}（Ｐ/Ｐ_０）・・（１）
Ｓ＝ｋＶｍ ・・・・・・・・・・・・・・・・・・・・・・・・・・・（２）
Ｐ₀ ：飽和蒸気圧
Ｐ ：吸着平衡圧
Ｖ ：吸着平衡圧Ｐにおける吸着量
Ｖｍ ：単分子層吸着量
Ｃ ：吸着熱などに関するパラメーター
Ｓ ：比表面積
ｋ ：窒素単分子占有面積：０．１６２ｎｍ^２ The specific surface area was determined by the multipoint method of BET, which is calculated by evaluating the amount of nitrogen gas adsorbed from the adsorption isotherm as a monolayer.
P / V (P _0- P) = (1 / VmC) + {(C-1) / VmC} (P / P ₀ ) ... (1)
S = kVm ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (2)
P ₀ : Saturated vapor pressure P: Adsorption equilibrium pressure V: Adsorption amount at adsorption equilibrium pressure P Vm: Adsorption amount of monolayer layer C: Parameters related to heat of adsorption, etc. S: Specific surface area k: Nitrogen single molecule occupied area: 0.162 nm ²

全細孔容積は、吸着等温線から得られた平衡相対圧Ｐ/Ｐ₀＝０．９９付近の飽和吸着ガス量から求めた。
孔径２ｎｍ以下のマイクロポア容積は、窒素ガスの吸着膜の厚さｔに対して吸着量をプロットしたｔ-プロット法により求めた。吸着膜の厚さは、０．３５〜０．５０ｎｍの範囲でＨａｒｋｉｎｓ＆Ｊｕｒａの式
ｔ＝〔１３．９９／｛０．０３４-ｌｏｇ（Ｐ／Ｐ_０）｝〕^0.5 ・・・・・・・（３）
により求めた。
Ｐ_０ ：飽和蒸気圧
Ｐ ：吸着平衡圧 The total pore volume was determined from the amount of saturated adsorbed gas near the equilibrium relative pressure P / P ₀ = 0.99 obtained from the adsorption isotherm.
The micropore volume having a pore size of 2 nm or less was determined by a t-plot method in which the adsorption amount was plotted against the thickness t of the nitrogen gas adsorption film. The thickness of the adsorption membrane is in the range of 0.35 to 0.50 nm, and the Harkins & Jura formula t = [13.99 / {0.034-log (P / P ₀ )}] ^0.5 ... 3)
Obtained by.
P ₀ : Saturated vapor pressure P: Adsorption equilibrium pressure

＜吸油量＞
吸油量は、株式会社あさひ総研製の吸収量測定器Ｓ−４１０型を使用し、亜麻仁油を用いてＪＩＳ Ｋ６２１７に従って測定した。試料粉末を撹拌しながら亜麻仁油を供給し、その時のトルクの変化を測定する。トルクは、試料粉末のストラクチャーによって変化するが、最大トルクの７０％を終点として読み取り、試料１００ｇ当たりの亜麻仁油量に換算して求めた。 <Oil absorption>
The oil absorption was measured according to JIS K6217 using flaxseed oil using an absorption measuring device S-410 manufactured by Asahi Soken Co., Ltd. Linseed oil is supplied while stirring the sample powder, and the change in torque at that time is measured. The torque varies depending on the structure of the sample powder, but 70% of the maximum torque was read as the end point and converted into the amount of linseed oil per 100 g of the sample.

＜タップ密度＞
１００ｍｌのメスシリンダーに試料を正確に３０ｇ量り取って投入し、ストローク１０ｍｍで７００回タッピングした後の体積から計算した。 <Tap density>
It was calculated from the volume after exactly 30 g of the sample was weighed and put into a 100 ml graduated cylinder and tapped 700 times with a stroke of 10 mm.

＜初回充放電容量＞
初回充電容量は、負極活物質１００重量部に対して結着剤としてＳＢＲとＣＭＣとをそれぞれ２重量部ずつ併せて水系スラリーを調製し、銅箔上にドクターブレードを用いて塗布し、１２０℃で乾燥し、ロールプレスを掛けた後、φ１２に打ち抜き厚さ６０μｍの電極とした。これに対極としてリチウム金属を用い、セパレーターを介して対向させ、電極群とした後、１Ｍ ＬｉＰＦ_６／ＥＣ：ＤＥＣ（３：７）の電解液を加えてコインセルを形成し、電流値０．５ｍＡ／ｃｍ^２で電圧値が０．０１Ｖになるまで定電流充電を行った後、電流値が０．０１ｍＡ／ｃｍ^２になるまで定電圧充電を行った。充電終了後、電流値０．５ｍＡ／ｃｍ２で定電流放電を行い、電圧値が１．５Ｖとなったところで放電を終了した。 <Initial charge / discharge capacity>
For the initial charge capacity, prepare an aqueous slurry by combining 2 parts by weight each of SBR and CMC as a binder with respect to 100 parts by weight of the negative electrode active material, and apply it on a copper foil using a doctor blade at 120 ° C. After drying with, and applying a roll press, an electrode having a thickness of 60 μm was punched into φ12. A lithium metal is used as a counter electrode, and the electrodes are opposed to each other via a separator to form an electrode group, and then an electrolytic solution of 1M LiPF ₆ / EC: DEC (3: 7) is added to form a coin cell, and a current value of 0.5 mA is formed. After constant current charging at / cm ² until the voltage value reached 0.01 V, constant current charging was performed until the current value reached 0.01 mA / cm ² . After the charging was completed, a constant current discharge was performed at a current value of 0.5 mA / cm2, and the discharge was completed when the voltage value reached 1.5 V.

従来用いられてきたフェノール樹脂、フラン樹脂、及び光学的等方性ピッチの溶融時に空気を吹き込む等して架橋構造を付加した後に炭素化して得たハードカーボンや、ピッチを炭素化して得たソフトカーボン、カーボンブラックを用いた結晶性が低くて比較的電気抵抗値が高い低結晶炭素材料の中に結晶性が高くて電気抵抗値が低い黒鉛粒子を包含させたことによりリチウムイオンキャパシタの内部抵抗を低下させることができた。 Hard carbon obtained by carbonizing the conventionally used phenol resin, furan resin, and optically isotropic pitch after adding a crosslinked structure by blowing air at the time of melting, or soft obtained by carbonizing the pitch. The internal resistance of a lithium-ion capacitor is obtained by including graphite particles with high crystallinity and low electrical resistance in a low-crystal carbon material using carbon and carbon black, which has low crystallinity and relatively high electrical resistance. Was able to be reduced.

実施例１の液体窒素温度における窒素ガスの等温吸着線図。The isotherm adsorption diagram of nitrogen gas at the liquid nitrogen temperature of Example 1. 比較例３の液体窒素温度における窒素ガスの等温吸着線図。FIG. 6 is an isothermal adsorption diagram of nitrogen gas at the liquid nitrogen temperature of Comparative Example 3.

以下に本発明の実施例及び比較例を述べる。
＜実施例１＞
密度１．３０ｇ／ｃｍ^３、軟化点１０５℃、キノリン不溶分１１％の石炭系光学的等方性のバインダーピッチ１００重量部とＤ_１０＝１．５５μｍ、Ｄ_５０＝２．４９μｍ、Ｄ_９０＝４．２３μｍ、Ｄ_１００＝７．０７μｍ、炭素網面の層間距離ｄ_{（００２）}が０．３３６０ｎｍ、ＢＥＴ比表面積が２２．６１ｍ^２／ｇ、亜麻仁油吸油量１０６ｍｌ／１００ｇ、真密度が２．２３ｇ／ｃｍ^３、タップ密度が０．２１ｇ／ｃｍ^３の人造黒鉛粒子３３０重量部を加熱ニーダーに投入し１６０℃で３時間混捏した。この混捏物を金属製容器に移した後、非酸化性雰囲気中５℃／ｈで昇温し、１０００℃で２時間保持して焼成した。次いで粉砕し、目開き３８μｍの篩を通すことによりＤ_１０＝２．３２μｍ、Ｄ_５０＝４．２６μｍ、Ｄ_９０＝８．４２μｍ、Ｄ_１００＝１６．５８μｍの低結晶炭素の内部に黒鉛粒子が包含された炭素粒子を得た。得られた炭素粒子のｄ_{（００２）}は、０．３３６０ｎｍ、ＢＥＴ比表面積は５．６５ｍ^２／ｇ、亜麻仁油吸油量は１１９ｍｌ／１００ｇ、真密度は２．１３ｇ／ｃｍ^３、タップ密度は０．４３ｇ／ｃｍ^３であった。
実施例１の液体窒素温度における窒素ガスの吸脱着における等温吸着線図を図１に示す。窒素ガスの相対圧（Ｐ／Ｐ_０）が、０．８前後までは窒素ガスの吸着量が少なく、０．８を超えると急激に増大するのが認められ、窒素ガスの吸脱着における等温吸着線図において、窒素ガスの相対圧（Ｐ／Ｐ_０）が、０．９９付近での窒素ガスの吸着量が４０ｃｍ^３／ｇである。 Examples and comparative examples of the present invention will be described below.
<Example 1>
Density 1.30 g / cm ³ , softening point 105 ° C, quinoline insoluble content 11%, carbon-based optically isotropic binder pitch 100 parts by weight and D ₁₀ = 1.55 μm, D ₅₀ = 2.49 μm, D ₉₀ = 4.23 μm, D ₁₀₀ = 7.07 μm, carbon mesh surface interlayer distance d ₍₀₀₂₎ is 0.3360 nm, BET specific surface area is 22.61 m ² / g, flaxseed oil absorption is 106 ml / 100 g, true density is 2. 330 parts by weight of artificial graphite particles having a tap density of 23 g / cm ³ and a tap density of 0.21 g / cm ³ were put into a heating kneader and kneaded at 160 ° C. for 3 hours. After transferring this kneaded product to a metal container, the temperature was raised at 5 ° C./h in a non-oxidizing atmosphere, and the mixture was held at 1000 ° C. for 2 hours for firing. Then, by pulverizing and passing through a sieve having a mesh size of 38 μm, graphite particles are formed inside low crystalline carbon of D ₁₀ = 2.32 μm, D ₅₀ = 4.26 μm, D ₉₀ = 8.42 μm, and D ₁₀₀ = 16.58 μm. The encapsulated carbon particles were obtained. The d ₍₀₀₂₎ of the obtained carbon particles was 0.3360 nm, the BET specific surface area was 5.65 m ² / g, the linseed oil oil absorption was 119 ml / 100 g, the true density was 2.13 g / cm ³ , and the tap density was 0. It was .43 g / cm ³ .
FIG. 1 shows an isothermal adsorption diagram of nitrogen gas adsorption / desorption at the liquid nitrogen temperature of Example 1. When the relative pressure (P / P ₀ ) of nitrogen gas is low up to around 0.8, the amount of nitrogen gas adsorbed is small, and when it exceeds 0.8, it is observed to increase rapidly, and isotherm adsorption during adsorption and desorption of nitrogen gas. In the diagram, the relative pressure (P / P ₀ ) of nitrogen gas is around 0.99, and the amount of nitrogen gas adsorbed is 40 cm ³ / g.

＜実施例２＞
実施例１で用いた人造黒鉛粒子に代えて、Ｄ_１０＝１．６６μｍ、Ｄ_５０＝２．７４μｍ、Ｄ_９０＝４．８０μｍ、Ｄ_１００＝８．３９μｍ、炭素網面の層間距離ｄ_{（００２）}が０．３３５４ｎｍ、ＢＥＴ比表面積が１７．０５ｍ^２／ｇ、亜麻仁油吸油量１０１ｍｌ／１００ｇ、真密度が２．２３ｇ／ｃｍ^３、タップ密度が０．２７ｇ／ｃｍ^３の天然黒鉛粒子にした他は、実施例１と同様に行った。
Ｄ_１０＝２．６４μｍ、Ｄ_５０＝５．０８μｍ、Ｄ_９０＝９．９７μｍ、Ｄ_１００＝１９．６６μｍ、ｄ_{（００２）}は、０．３３５４ｎｍ、ＢＥＴ比表面積は７．４８ｍ^２／ｇ、吸油量は１３３ｍｌ／１００ｇ真密度は２．１９ｇ／ｃｍ^３、タップ密度は０．３７ｇ／ｃｍ^３の低結晶炭素の内部に黒鉛粒子が包含された炭素粒子を得た。 <Example 2>
Instead of the artificial graphite particles used in Example 1, D ₁₀ = 1.66 μm, D ₅₀ = 2.74 μm, D ₉₀ = 4.80 μm, D ₁₀₀ = 8.39 μm, the interlayer distance d ₍₀₀₂₎ of the carbon mesh surface. ₎ Is 0.3354 nm, BET specific surface area is 17.05 m ² / g, flaxseed oil absorption amount is 101 ml / 100 g, true density is 2.23 g / cm ³ , and tap density is 0.27 g / cm ³ . Others were the same as in Example 1.
D ₁₀ = 2.64 μm, D ₅₀ = 5.08 μm, D ₉₀ = 9.97 μm, D ₁₀₀ = 19.66 μm, d ₍₀₀₂₎ is 0.3354 nm, BET specific surface area is 7.48 m ² / g, oil absorption. Carbon particles in which graphite particles were contained inside low crystalline carbon having an amount of 133 ml / 100 g and a true density of 2.19 g / cm ³ and a tap density of 0.37 g / cm ³ were obtained.

＜比較例１＞
実施例１で用いた人造黒鉛粒子をそのまま用いた。 <Comparative example 1>
The artificial graphite particles used in Example 1 were used as they were.

＜比較例２＞
実施例１で用いたピッチ１００重量部とアセチレンブラック（ＢＥＴ比表面積：３９．０ｍ^２／ｇ、ｄ_{（００２）}：０．３５３９ｎｍ、平均粒子径４８ｎｍ、）７４重量部とを用いて実施例１と同様の処理を行い、Ｄ_１０＝１．５６μｍ、Ｄ_５０＝２．６２μｍ、Ｄ_９０＝４．７３μｍ、Ｄ_１００＝８．３９μｍ、ｄ_{（００２）}は０．３５３９ｎｍ、ＢＥＴ比表面積は２４．４８ｍ^２／ｇ、吸油量は７９ｍｌ／１００ｇ、タップ密度は０．５０ｇ／ｃｍ^３の低結晶炭素の粒子を得た。 <Comparative example 2>
Example 1 using 100 parts by weight of the pitch used in Example 1 and 74 parts by weight of acetylene black (BET specific surface area: 39.0 m ² / g, d ₍₀₀₂₎ : 0.3539 nm, average particle size 48 nm). D ₁₀ = 1.56 μm, D ₅₀ = 2.62 μm, D ₉₀ = 4.73 μm, D ₁₀₀ = 8.39 μm, d ₍₀₀₂₎ is 0.3539 nm, and the BET specific surface area is 24. Low crystalline carbon particles having a tap density of 48 m ² / g, an oil absorption of 79 ml / 100 g, and a tap density of 0.50 g / cm ³ were obtained.

＜比較例３＞
実施例１で用いたピッチ１００重量部とＤ_１０＝２．６０μｍ、Ｄ_５０＝７．３４μｍ、Ｄ_９０＝１５．９０μｍ、Ｄ_１００＝３２．７８μｍ、ｄ_{（００２）}は０．３４５５ｎｍ、ＢＥＴ比表面積は８．６７ｍ^２／ｇの仮焼された石炭系コークス５００重量部とを用いて実施例１と同様の処理を行い、Ｄ_１０＝５．５８μｍ、Ｄ_５０＝１１．２２μｍ、Ｄ_９０＝２１．８７μｍ、Ｄ_１００＝３８．８６μｍ、ｄ_{（００２）}は０．３４５５ｎｍ、ＢＥＴ比表面積は２．０２ｍ^２／ｇ、吸油量８４ｍｌ／１００ｇ、タップ密度は０．７５ｇ／ｃｍ^３の低結晶炭素の粒子を得た。
液体窒素温度における窒素ガスの吸脱着における比較例３の等温吸着線図を図２に示す。窒素ガスの相対圧（Ｐ／Ｐ_０）が、１．０付近で僅かに上昇するが、実施例のような急激な窒素ガスの吸着量の上昇は認められなかった。 <Comparative example 3>
100 parts by weight of pitch used in Example 1, D ₁₀ = 2.60 μm, D ₅₀ = 7.34 μm, D ₉₀ = 15.90 μm, D ₁₀₀ = 32.78 μm, d ₍₀₀₂₎ is 0.3455 nm, BET ratio. The same treatment as in Example 1 was carried out using 500 parts by weight of calcined coal-based coke having a surface area of 8.67 m ² / g, and D ₁₀ = 5.58 μm, D ₅₀ = 11.22 μm, D ₉₀ =. 21.87 μm, D ₁₀₀ = 38.86 μm, d ₍₀₀₂₎ is 0.3455 nm, BET specific surface area is 2.02 m ² / g, oil absorption is 84 ml / 100 g, tap density is 0.75 g / cm ³ low crystalline carbon Obtained particles of.
FIG. 2 shows an isothermal adsorption diagram of Comparative Example 3 in the adsorption / desorption of nitrogen gas at the liquid nitrogen temperature. The relative pressure of nitrogen gas (P / P ₀ ) slightly increased around 1.0, but the rapid increase in the amount of nitrogen gas adsorbed as in the examples was not observed.

＜比較例４＞
実施例１で用いたピッチ１００重量部と、人造黒鉛粒子２２０重量部を用いて実施例１と同様の処理を行ったが、焼成後は一体化した強固な塊となり、金属容器から取り出すこともできなかったため中止した。 <Comparative example 4>
The same treatment as in Example 1 was carried out using 100 parts by weight of the pitch used in Example 1 and 220 parts by weight of artificial graphite particles, but after firing, it became an integrated strong mass and could be taken out from the metal container. I couldn't do it, so I canceled it.

表１に実施例及び比較例のピッチ由来の低結晶炭素のｄ_{（００２）}、ピッチと混合した人造黒鉛粒子またはカーボンブラック等の炭素粒子のｄ_{（００２）}、焼成して得られた炭素粒子の平均粒子径、最大粒子径、吸油量、及びタップ密度を示す。
Table 1 Examples and the low-crystalline carbon from a pitch of Comparative Example d _(002), carbon particles such as artificial graphite particles or carbon black mixed with a pitch d _(002), carbon particles obtained by firing Shows average particle size, maximum particle size, oil absorption, and tap density.

表１において、比較例１は黒鉛粒子のみで低結晶炭素を含まないので、ピッチ由来の低結晶炭素のｄ_{（００２）}欄は空白としてあり、包含された粒子のｄ_{（００２）}の欄は、実施例１の人造黒鉛粒子のｄ_{（００２）}である。また、比較例２は、ピッチとアセチレンブラックを混合したものであり、包含された粒子のｄ_{（００２）}欄には、アセチレンブラックのｄ_{（００２）}の値が記入してあり、比較例３は仮焼コークスのｄ_{（００２）}の値である。 In Table 1, the Comparative Example 1 does not include a low crystalline carbon only graphite particles, the d ₍₀₀₂₎ column of the low crystalline carbon from pitch have as a blank, column d ₍₀₀₂₎ of the inclusion particles It is d ₍₀₀₂₎ of the artificial graphite particle of Example 1. Further, Comparative Example 2 is a mixture of pitch and acetylene black, and the value of d ₍₀₀₂₎ of acetylene black is entered in the d ₍₀₀₂₎ column of the _contained particles, and Comparative Example 3 is It is a value of d ₍₀₀₂₎ of calcined coke.

表２は、実施例と比較例の炭素粒子の比表面積、全細孔容積、マイクロ孔容積、マイクロ孔容積の全細孔容積に対する割合、窒素ガス吸着量等の特性を示すものである。
Table 2 shows the characteristics such as the specific surface area of the carbon particles of Examples and Comparative Examples, the total pore volume, the micropore volume, the ratio of the micropore volume to the total pore volume, and the amount of nitrogen gas adsorbed.

表３は、実施例及び比較例の炭素粒子を負極活物質として用いたリチウムイオンキャパシタの特性を示すものである。
Table 3 shows the characteristics of lithium ion capacitors using carbon particles of Examples and Comparative Examples as a negative electrode active material.

表３に実施例１、２、比較例１、２、及び３の初回充放電容量測定結果を示す。
実施例１及び２は、初回放電容量が人造黒鉛のみからなる比較例１の３６０ｍＡｈ／ｇより低いものの、３３５ｍＡｈ／ｇを超え、充放電効率は、８６％を超えて比較例１より高い値を示している。比較例２、３では充放電効率が低く、初回放電容量は２５０ｍＡｈ／ｇを下回るものであった。 Table 3 shows the initial charge / discharge capacity measurement results of Examples 1 and 2, Comparative Examples 1, 2 and 3.
In Examples 1 and 2, although the initial discharge capacity is lower than 360 mAh / g of Comparative Example 1 composed of only artificial graphite, it exceeds 335 mAh / g, and the charge / discharge efficiency exceeds 86% and is higher than that of Comparative Example 1. Shown. In Comparative Examples 2 and 3, the charge / discharge efficiency was low, and the initial discharge capacity was less than 250 mAh / g.

＜低炭素粒子内の黒鉛粒子の確認方法＞
実施例１、２で得られた活物質粒子をフッ素樹脂板の上に内径φ２５×外形φ３０×高さ２５ｍｍのフッ素樹脂製リングを置き、このリング内に活物質粒子を投入し、埋込用樹脂のエポキシ樹脂の主剤と硬化剤を体積比９：１で混合して上部から流し入れた。活物質粒子とエポキシ樹脂主剤と硬化剤の体積比は、この時点において、１：９：１であった。これを室温（２０〜２５℃）にて１０時間放置し、エポキシ樹脂を硬化させて樹脂中に活物質粒子が分散した樹脂硬化体を得た。次いで樹脂硬化体を複数個の活物質粒子の断面が露出するまで複数の研磨紙を使用して研磨して鏡面に仕上げた。
これを試料として偏光顕微鏡による観察を倍率の変更、及び試料台を回転することによる試料粉末断面に対する偏光の入射角度の変更をおこなって観察した。
観察の結果、光学的等方性を示すピンク色の低結晶炭素部分の内側に黄色、ピンク色、青色、再び黄色の順に色が変化する光学的異方性を示す黒鉛粒子部分が実施例１、２とも観察された。 <Method of confirming graphite particles in low carbon particles>
The active material particles obtained in Examples 1 and 2 are placed on a fluororesin plate with a fluororesin ring having an inner diameter of φ25 × an outer diameter of φ30 × a height of 25 mm, and the active material particles are put into the ring for embedding. The main agent of the epoxy resin and the curing agent were mixed at a volume ratio of 9: 1 and poured from above. The volume ratio of the active material particles to the epoxy resin main agent to the curing agent was 1: 9: 1 at this time. This was left at room temperature (20 to 25 ° C.) for 10 hours to cure the epoxy resin to obtain a cured resin product in which the active material particles were dispersed in the resin. The cured resin was then polished with a plurality of abrasive papers until the cross sections of the plurality of active material particles were exposed to give a mirror surface.
Using this as a sample, observation with a polarizing microscope was carried out by changing the magnification and changing the incident angle of polarized light with respect to the cross section of the sample powder by rotating the sample table.
As a result of observation, in Example 1 a graphite particle portion showing optical anisotropy in which the color changes in the order of yellow, pink, blue, and yellow again inside the pink low crystal carbon portion showing optical isotropicity. Both and 2 were observed.

比較例１、２、３の粒子に対して実施例と同様の観察を行ったところ、比較例１では、光学的異方性を示す粒子（黒鉛粒子）のみが観察された。比較例２については、光学的等方性を示すピンク色の中に、黒鉛やコークスを同様に観察した場合に認められる明白に青色や黄色と判別される光学的異方性部分と比べるとはるかに不鮮明で、注視することによってようやく青色や黄色と認識される光学的異方性の微小部位が観察された。比較例３については、実施例と同様に光学的等方性を示す低結晶炭素部分の内側に光学的異方性を示すコークス粒子部分が観察された。 When the same observations as in Examples were performed on the particles of Comparative Examples 1, 2 and 3, only the particles showing optical anisotropy (graphite particles) were observed in Comparative Example 1. In Comparative Example 2, it is far more than the optically anisotropic part that is clearly discriminated as blue or yellow, which is observed when graphite or coke is observed in the same pink color showing optical isotropicity. A minute part of optical anisotropy, which was unclear and was finally recognized as blue or yellow by gazing, was observed. In Comparative Example 3, a coke particle portion showing optical anisotropy was observed inside the low crystal carbon portion showing optical isotropicity as in the example.

Claims (2)

Ｘ線回折による炭素結晶網面層の面間距離ｄ_{（００２）}が、０．３４００〜０．３７７０ｎｍの低結晶炭素の内部にｄ_{（００２）}が０．３３５４〜０．３３６０ｎｍ、平均粒子径が０．８〜３．０μｍの黒鉛粒子を少なくとも一粒以上包含する平均粒子径２．０〜６．０μｍであり、低結晶炭素と黒鉛粒子の重量比が１対３．５〜１対７．２であることを特徴とするリチウムイオンキャパシタ用負極活物質を得る製造方法であって、
所定量のピッチと黒鉛粒子を撹拌混合し、この混合物を非酸化性雰囲気中で５〜１０℃/ｈで昇温して８００〜１２００℃で１〜１０時間保持して焼成し、ピッチ内に包含させた黒鉛粒子が表面に露出しない程度に焼成物を粉砕し、この粉砕物活物質粒子をエポキシ樹脂で固め、得られた樹脂硬化体を研磨紙で研磨して鏡面に仕上げ、偏光顕微鏡によって黒鉛粒子の存在を確認するリチウムイオンキャパシタ用負極活物質の製造方法。 The interplanetary distance d ₍₀₀₂₎ of the carbon crystal network layer by X-ray diffraction is 0.3400 to 0.3770 nm inside the low crystal carbon, d ₍₀₀₂₎ is 0.3354 to 0.3360 nm, and the average particle size is The average particle size is 2.0 to 6.0 μm, which includes at least one graphite particle of 0.8 to 3.0 μm, and the weight ratio of low crystalline carbon to graphite particles is 1: 3.5 to 1: 7. A manufacturing method for obtaining a negative electrode active material for a lithium ion capacitor, which is characterized by being 2.
A predetermined amount of pitch and graphite particles are stirred and mixed, and the mixture is heated at 5 to 10 ° C./h in a non-oxidizing atmosphere and held at 800 to 1200 ° C. for 1 to 10 hours for firing. The fired product is crushed to the extent that the included graphite particles are not exposed on the surface, the crushed material active material particles are hardened with an epoxy resin, and the obtained cured resin is polished with abrasive paper to give a mirror surface, and then by a polarization microscope. A method for producing a negative electrode active material for a lithium ion capacitor for confirming the presence of graphite particles. 請求項１において、リチウムイオンキャパシタ用負極活物質をエポキシ樹脂で固めた試料の調製は、リチウムイオンキャパシタ用負極活物質粒子をフッ素樹脂板の上にフッ素樹脂製リングを置き、このリング内に活物質粒子を投入し、埋込用樹脂のエポキシ樹脂の主剤と硬化剤を体積比９：１で混合して得るものであるリチウムイオンキャパシタ用負極活物質の製造方法。 In claim 1, in the preparation of a sample in which the negative electrode active material for a lithium ion capacitor is hardened with an epoxy resin, a fluorine resin ring is placed on a fluorine resin plate and the negative electrode active material particles for a lithium ion capacitor are activated in the ring. A method for producing a negative electrode active material for a lithium ion capacitor, which is obtained by charging material particles and mixing a main agent of an epoxy resin for embedding resin and a curing agent at a volume ratio of 9: 1.