JP5190916B2 - Composite powder for electrode and method for producing the same - Google Patents

Composite powder for electrode and method for producing the same Download PDF

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JP5190916B2
JP5190916B2 JP2007065949A JP2007065949A JP5190916B2 JP 5190916 B2 JP5190916 B2 JP 5190916B2 JP 2007065949 A JP2007065949 A JP 2007065949A JP 2007065949 A JP2007065949 A JP 2007065949A JP 5190916 B2 JP5190916 B2 JP 5190916B2
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友成 竹内
光春 田渕
洋子 鍋島
和明 阿度
昌弘 鹿野
博之 蔭山
国昭 辰巳
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National Institute of Advanced Industrial Science and Technology AIST
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    • 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
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    • 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
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Description

本発明は、電極用複合粉末及びその製造方法に関する。   The present invention relates to a composite powder for electrodes and a method for producing the same.

近年の多様な機器やシステムの発展により、動力源としての電池(一次電池、二次電池、燃料電池、キャパシタ等)の高性能化の要求がますます高くなってきている。例えば、リチウム二次電池は、携帯通信機器、ノート型パソコン等の電子機器の電源を担う高エネルギー密度の二次電池として広く普及が進んでおり、また環境負荷低減の観点から自動車のモーター駆動用バッテリーとしても期待されている。このため、これら機器の高性能化に対応した高出力及び高エネルギー密度のリチウム二次電池の開発が求められている。   With the development of various devices and systems in recent years, there is an increasing demand for higher performance of batteries (primary batteries, secondary batteries, fuel cells, capacitors, etc.) as power sources. For example, lithium secondary batteries are widely used as high energy density secondary batteries that power electronic devices such as portable communication devices and laptop computers, and are used for driving motors in automobiles from the viewpoint of reducing environmental impact. It is also expected as a battery. For this reason, development of a lithium secondary battery having a high output and a high energy density corresponding to the high performance of these devices is required.

特に車載用としては、高電流密度での良好な充放電特性が求められるが、高電流密度で充放電を繰り返した際に容量劣化及びサイクル劣化が生じるという問題がある。例えば、車載用リチウム二次電池としては、アルミニウム添加ニッケルコバルト酸リチウム(LiNi0.8Co0.15 Al0.05)を正極活物質として用いるものが良く知られている。かかる車載用リチウム二次電池は理論容量が約260mAh/gと大きい。しかしながら、60℃の環境下、高電流密度で充放電を繰り返すと、正極の電気抵抗が増大してサイクル劣化を引き起こすという問題が指摘されている(非特許文献1)。 In particular, for vehicles, good charge / discharge characteristics at a high current density are required, but there is a problem that capacity deterioration and cycle deterioration occur when charge / discharge is repeated at a high current density. For example, an in-vehicle lithium secondary battery that uses aluminum-added lithium nickel cobalt oxide (LiNi 0.8 Co 0.15 Al 0.05 O 2 ) as a positive electrode active material is well known. Such an in-vehicle lithium secondary battery has a large theoretical capacity of about 260 mAh / g. However, it has been pointed out that when charging / discharging is repeated at a high current density in an environment of 60 ° C., the electrical resistance of the positive electrode increases to cause cycle deterioration (Non-Patent Document 1).

上記容量劣化及びサイクル劣化の原因としては、例えば、次の理由が考えられる。即ち、高電流密度で充放電を繰り返した際のリチウム脱離・挿入に伴う電極活物質の膨張・収縮によって導電材が電極活物質から剥離したり導電材どうしの導電ネットワークが切断したりすることにより、導電材の分布が不均一になると考えられる(非特許文献2)。   As the cause of the capacity deterioration and cycle deterioration, for example, the following reasons can be considered. That is, the conductive material may be separated from the electrode active material or the conductive network between the conductive materials may be disconnected due to the expansion / contraction of the electrode active material due to lithium desorption / insertion when charging / discharging is repeated at a high current density. Therefore, it is considered that the distribution of the conductive material becomes non-uniform (Non-Patent Document 2).

上記問題を改善するために、(1)電極活物質を微粒化して電極内のリチウムイオンの拡散距離を短くして活物質の利用率を上げる、(2)電極活物質に導電材を被覆又は接合して導電材の分布の不均一を緩和する、(3)導電材どうしの結合を強くして導電ネットワークを保持する、等の方法が考えられている。   In order to improve the above problems, (1) the electrode active material is atomized to shorten the diffusion distance of lithium ions in the electrode and increase the utilization of the active material. (2) The electrode active material is coated with a conductive material or Various methods have been considered, such as bonding to alleviate non-uniform distribution of the conductive material, and (3) strengthening the bonding between the conductive materials to maintain the conductive network.

例えば、特許文献1には、電極活物質と導電材を混合し、黒鉛型材を用いて50MPa程度までの加圧下、200〜800℃程度の温度で通電処理を行って電極活物質と導電材とを接合することが開示されている。この技術は上記(2)に対応するものであり、電極活物質と導電材とを接合して導電材の分布の不均一を緩和させている。   For example, in Patent Document 1, an electrode active material and a conductive material are mixed and subjected to a current treatment at a temperature of about 200 to 800 ° C. under a pressure of up to about 50 MPa using a graphite mold material. Is disclosed. This technique corresponds to the above (2), and the electrode active material and the conductive material are joined to alleviate the uneven distribution of the conductive material.

これまでに、高電流密度での充放電特性は徐々に改善されてきているが、各種機器の高性能化に追随すべく、高電流密度での充放電特性の更なる向上が求められている。かかる要求に応えるべく、電極活物質と導電材との接合強度を更に強くして導電ネットワークを更に強固なものとする技術の開発が望まれている。
特開2005−135723号公報 Y. Itou and Y. Ukyo, J. Power Sources, 146, 39 (2005). X.Zhang, P.N.Ross,Jr., R.Kostecki, F.Kong,S.Sloop, J.B.Kerr, K.Striebel, E.J.Cairns, and F.McLarnon, J.Electrochem. Soc., 148, A463 (2001).
So far, the charge / discharge characteristics at high current density have been gradually improved, but in order to follow the high performance of various devices, further improvement of charge / discharge characteristics at high current density is required. . In order to meet such a demand, development of a technique for further strengthening the conductive network by further strengthening the bonding strength between the electrode active material and the conductive material is desired.
JP 2005-135723 A Y. Itou and Y. Ukyo, J. Power Sources, 146, 39 (2005). X. Zhang, PNRoss, Jr., R. Kostecki, F. Kong, S. Sloop, JBKerr, K. Striebel, EJCairns, and F. McLarnon, J. Electrochem. Soc., 148, A463 (2001).

本発明は、重量エネルギー密度及び体積エネルギー密度を低下させることなく、高電流密度での充放電特性が改善された電極を得ることができる、電極活物質と導電材との接合
強度が改善された電極用複合粉末及びその製造方法を提供することを目的とする。
The present invention can obtain an electrode with improved charge / discharge characteristics at a high current density without reducing the weight energy density and volume energy density, and the bonding strength between the electrode active material and the conductive material is improved. It aims at providing the composite powder for electrodes, and its manufacturing method.

本発明者は、鋭意研究を重ねた結果、導電材と電極活物質とを含有する原料混合物を、少なくとも圧縮力と剪断力とを加えるメカノフュージョン処理に供することにより、電極活物質と導電材とを予め結着させ、更に特定条件で通電焼結させる場合には、上記目的を達成できることを見出し、本発明を完成するに至った。   As a result of intensive studies, the present inventor has provided a raw material mixture containing a conductive material and an electrode active material to a mechanofusion process that applies at least a compressive force and a shearing force, whereby the electrode active material and the conductive material The present inventors have found that the above-mentioned object can be achieved by binding in advance and conducting current sintering under specific conditions, and have completed the present invention.

即ち、本発明は、下記の電極用複合粉末及びその製造方法に関する。
1. 電極活物質どうしが導電材を介して接合している構造を有する電極用複合粉末であって、前記電極用複合粉末は、
(1)電極活物質と導電材とを含有する原料混合物をメカノフュージョン処理することによって前記電極活物質と前記導電材とを予め結着させ、次いで、
(2)前記結着後の原料混合物を、導電性を有する型に充填し、60MPa以上の加圧下において直流パルス電流を通電して焼結させることにより得られる、電極用複合粉末。
2. 前記メカノフュージョン処理は、前記原料混合物に少なくとも圧縮力と剪断力とを加え、前記電極活物質と前記導電材とを結着させる、上記項1に記載の電極用複合粉末。3. 前記メカノフュージョン処理は、回転するケーシングと前記ケーシング内に固定されたインナーピースとを備えるメカノフュージョン装置を用いる処理であって、
(1)前記ケーシングと前記インナーピースとの隙間距離は0.1〜10mmであり、
(2)前記ケーシング内に前記原料混合物を供給すると、前記原料混合物は遠心力により前記ケーシングの内壁面に押し付けられるとともに、前記インナーピースと前記内壁面の隙間で少なくとも圧縮力と剪断力とを加えられることにより、前記電極活物質と前記導電材とが結着し、
(3)前記処理は、前記ケーシング内に前記原料混合物を供給した後、前記ケーシングを1000〜8000rpmの速度で1〜30分間回転させることにより行う、上記項1に記載の電極用複合粉末。
4. 前記導電性を有する型は、タングステンカーバイドを含有する、上記項1〜3のいずれかに記載の電極用複合粉末。
5. 150MPa以上の加圧下において直流パルス電流を通電する、上記項1〜4のいずれかに記載の電極用複合粉末。
6. 前記電極活物質は、1)オリビン型構造の含リチウム化合物、2)層状岩塩型又は立方晶岩塩型の結晶構造を有する岩塩類縁構造の含リチウム化合物、及び3)スピネル型構造の含リチウム化合物からなる群から選択される少なくとも1種の正極活物質である、上記項1〜5のいずれかに記載の電極用複合粉末。
7. 前記電極活物質は、リン酸鉄リチウム;コバルト、マンガン及びニッケルからなる群から選択される少なくとも1種を固溶したリン酸鉄リチウム;リン酸コバルトリチウム;マンガン及びニッケルの少なくとも1種を固溶したリン酸コバルトリチウム;リン酸マンガンリチウム;ニッケルを固溶したリン酸マンガンリチウム;リン酸ニッケルリチウム;ニッケル酸リチウム;コバルト及びアルミニウムの少なくとも1種を固溶したニッケル酸リチウム;コバルト酸リチウム;鉄酸リチウム;チタン、マンガンの少なくとも1種を固溶した鉄酸リチウム;チタン酸リチウム;マンガン酸リチウム;及びクロムを固溶したマンガン酸リチウムからなる群から選択される少なくとも1種の正極活物質である、上記項1〜5のいずれかに記載の電極用複合粉末。
8. 前記電極活物質は、炭素、珪素、ゲルマニウム、スズ、鉛、アンチモン、アルミニウム、インジウム、リチウム、酸化スズ、チタン酸リチウム、窒化リチウム、インジウムを固溶した酸化錫、インジウム−錫合金、リチウム−アルミニウム合金及びリチウム−インジウム合金からなる群から選択される少なくとも1種の負極活物質である、上記項1〜5のいずれかに記載の電極用複合粉末。
9. 上記項1〜8のいずれかに記載の電極用複合粉末を含有する電極を備えた、一次電
池、二次電池、燃料電池又はキャパシタ。
10. 電極活物質どうしが導電材を介して接合している構造を有する電極用複合粉末の製造方法であって、
(1)電極活物質と導電材とを含有する原料混合物をメカノフュージョン処理することによって前記電極活物質と前記導電材とを予め結着させ、次いで、
(2)前記結着後の原料混合物を、導電性を有する型に充填し、60MPa以上の加圧下において直流パルス電流を通電して焼結させる工程を有する、製造方法。
11. 前記メカノフュージョン処理は、前記原料混合物に少なくとも圧縮力と剪断力とを加え、前記電極活物質と前記導電材とを結着させる、上記項10に記載の製造方法。
12. 前記メカノフュージョン処理は、回転するケーシングと前記ケーシング内に固定されたインナーピースとを備えるメカノフュージョン装置を用いる処理であって、
(1)前記ケーシングと前記インナーピースとの隙間距離は0.1〜10mmであり、
(2)前記ケーシング内に前記原料混合物を供給すると、前記原料混合物は遠心力により前記ケーシングの内壁面に押し付けられるとともに、前記インナーピースと前記内壁面の隙間で少なくとも圧縮力と剪断力とを加えられることにより、前記電極活物質と前記導電材とが結着し、
(3)前記処理は、前記ケーシング内に前記原料混合物を供給した後、前記ケーシングを1000〜8000rpmの速度で1〜30分間回転させることにより行う、上記項10に記載の製造方法。

以下、本発明の電極用複合粉末及びその製造方法について詳細に説明する。
That is, this invention relates to the following composite powder for electrodes, and its manufacturing method.
1. A composite powder for an electrode having a structure in which electrode active materials are joined via a conductive material, the composite powder for an electrode,
(1) The electrode active material and the conductive material are previously bound by subjecting the raw material mixture containing the electrode active material and the conductive material to mechanofusion treatment,
(2) A composite powder for an electrode obtained by filling the raw material mixture after the binding into a conductive mold and sintering it by applying a direct current pulse current under a pressure of 60 MPa or more.
2. The composite powder for an electrode according to Item 1, wherein in the mechanofusion treatment, at least a compressive force and a shearing force are applied to the raw material mixture to bind the electrode active material and the conductive material. 3. The mechanofusion process is a process using a mechanofusion apparatus including a rotating casing and an inner piece fixed in the casing,
(1) The gap distance between the casing and the inner piece is 0.1 to 10 mm,
(2) When the raw material mixture is supplied into the casing, the raw material mixture is pressed against the inner wall surface of the casing by centrifugal force, and at least a compressive force and a shearing force are applied between the inner piece and the inner wall surface. The electrode active material and the conductive material are bound together,
(3) The composite powder for an electrode according to item 1, wherein the treatment is performed by rotating the casing at a speed of 1000 to 8000 rpm for 1 to 30 minutes after supplying the raw material mixture into the casing.
4). The composite powder for an electrode according to any one of Items 1 to 3, wherein the conductive mold contains tungsten carbide.
5. Item 5. The composite powder for an electrode according to any one of Items 1 to 4, wherein a DC pulse current is applied under a pressure of 150 MPa or more.
6). The electrode active material is composed of 1) a lithium-containing compound having an olivine structure, 2) a lithium-containing compound having a rock salt-like structure having a layered rock salt type or cubic rock salt type crystal structure, and 3) a lithium containing compound having a spinel structure. Item 6. The composite powder for an electrode according to any one of Items 1 to 5, which is at least one positive electrode active material selected from the group consisting of:
7). The electrode active material is lithium iron phosphate; lithium iron phosphate in which at least one selected from the group consisting of cobalt, manganese, and nickel is dissolved; lithium cobalt phosphate; at least one of manganese and nickel is in solid solution Cobalt lithium phosphate; lithium manganese phosphate; lithium manganese phosphate in solid solution; nickel lithium phosphate; lithium nickelate; lithium nickelate in solid solution of at least one of cobalt and aluminum; lithium cobaltate; iron At least one positive electrode active material selected from the group consisting of lithium acid; lithium ironate in which at least one of titanium and manganese is dissolved; lithium titanate; lithium manganate; and lithium manganate in which chromium is dissolved For an electrode according to any one of Items 1 to 5, If powder.
8). The electrode active material includes carbon, silicon, germanium, tin, lead, antimony, aluminum, indium, lithium, tin oxide, lithium titanate, lithium nitride, indium tin oxide, indium-tin alloy, lithium-aluminum. Item 6. The composite powder for an electrode according to any one of Items 1 to 5, which is at least one negative electrode active material selected from the group consisting of an alloy and a lithium-indium alloy.
9. A primary battery, a secondary battery, a fuel cell or a capacitor, comprising an electrode containing the composite powder for an electrode according to any one of Items 1 to 8.
10. A method for producing a composite powder for an electrode having a structure in which electrode active materials are joined together via a conductive material,
(1) The electrode active material and the conductive material are previously bound by subjecting the raw material mixture containing the electrode active material and the conductive material to mechanofusion treatment,
(2) A manufacturing method comprising filling the raw material mixture after the binding into a conductive mold and applying a direct current pulse current under a pressure of 60 MPa or more to sinter.
11. The manufacturing method according to Item 10, wherein in the mechanofusion treatment, at least a compressive force and a shearing force are applied to the raw material mixture to bind the electrode active material and the conductive material.
12 The mechanofusion process is a process using a mechanofusion apparatus including a rotating casing and an inner piece fixed in the casing,
(1) The gap distance between the casing and the inner piece is 0.1 to 10 mm,
(2) When the raw material mixture is supplied into the casing, the raw material mixture is pressed against the inner wall surface of the casing by centrifugal force, and at least a compressive force and a shearing force are applied between the inner piece and the inner wall surface. The electrode active material and the conductive material are bound together,
(3) The manufacturing method according to Item 10, wherein the treatment is performed by rotating the casing at a speed of 1000 to 8000 rpm for 1 to 30 minutes after supplying the raw material mixture into the casing.

Hereinafter, the composite powder for electrodes of the present invention and the production method thereof will be described in detail.

1.電極用複合粉末
本発明の電極用複合粉末は、電極活物質どうしが導電材を介して接合している構造を有する電極用複合粉末である。当該構造としては、例えば、導電材が表面に付着した又は導電材によって被覆された電極活物質どうしが接合している構造が挙げられる。
1. Electrode Composite Powder The electrode composite powder of the present invention is an electrode composite powder having a structure in which electrode active materials are joined together via a conductive material. As the structure, for example, a structure in which a conductive material adheres to the surface or electrode active materials covered with the conductive material are joined to each other can be given.

上記構造を有する本発明の電極用複合粉末は、
(1)電極活物質と導電材とを含有する原料混合物をメカノフュージョン処理することによって前記電極活物質と前記導電材とを予め結着させ、次いで、
(2)前記結着後の原料混合物を、導電性を有する型に充填し、60MPa以上の加圧下において直流パルス電流を通電して焼結させることにより得られる。
The composite powder for an electrode of the present invention having the above structure is
(1) The electrode active material and the conductive material are previously bound by subjecting the raw material mixture containing the electrode active material and the conductive material to mechanofusion treatment,
(2) It is obtained by filling the raw material mixture after the binding into a conductive mold and sintering it by applying a direct current pulse current under a pressure of 60 MPa or more.

本発明の電極用複合粉末は、原料混合物をメカノフュージョン処理後、60MPa以上の加圧下で通電焼結することにより得るため、電極活物質と導電材との接合強度が大きく、これにより電極活物質と導電材との導電ネットワークが強固である。このような電極用複合粉末は、高電流密度で充放電を繰り返した場合でも導電ネットワークが損なわれ難く、各種電池及びキャパシタに適用し得る電極粉末として有用である。本発明の電極用複合粉末は、とりわけリチウム二次電池に対して有用性が高い。   Since the composite powder for electrodes of the present invention is obtained by subjecting the raw material mixture to electro-sintering under a pressure of 60 MPa or more after the mechanofusion treatment, the bonding strength between the electrode active material and the conductive material is large, thereby the electrode active material. And the conductive network of the conductive material is strong. Such a composite powder for an electrode is useful as an electrode powder that can be applied to various batteries and capacitors because the conductive network is hardly damaged even when charging and discharging are repeated at a high current density. The composite powder for electrodes of the present invention is particularly useful for lithium secondary batteries.

以下、本発明の電極用複合粉末について、リチウム二次電池の電極材料として適用する場合を例示しながら説明する。   Hereinafter, the electrode composite powder of the present invention will be described with reference to the case where it is applied as an electrode material for a lithium secondary battery.

≪電極活物質≫
電極活物質としては特に限定されず、従来、電池やキャパシタに適用されている正極・負極活物質が使用できる。
≪Electrode active material≫
It does not specifically limit as an electrode active material, The positive electrode and negative electrode active material conventionally applied to the battery and the capacitor can be used.

リチウム二次電池用電極活物質で具体例を挙げれば、正極活物質としては、例えば、
1)オリビン型構造の含リチウム化合物、
2)層状岩塩型又は立方晶岩塩型の結晶構造を有する岩塩類縁構造の含リチウム化合物、
3)スピネル型構造の含リチウム化合物、
等が挙げられる。
As specific examples of the electrode active material for lithium secondary battery, as the positive electrode active material, for example,
1) Lithium-containing compound having an olivine type structure,
2) Lithium-containing compounds having a rock salt related structure having a layered rock salt type or cubic rock salt type crystal structure,
3) a lithium-containing compound having a spinel structure,
Etc.

具体的には、1)オリビン型構造の含リチウム化合物としては、例えば、リン酸鉄リチウム;コバルト、マンガン及びニッケルの少なくとも1種を固溶したリン酸鉄リチウム;リン酸コバルトリチウム;マンガン及びニッケルの少なくとも1種を固溶したリン酸コバルトリチウム;リン酸マンガンリチウム;ニッケルを固溶したリン酸マンガンリチウム、リン酸ニッケルリチウム等が挙げられる。   Specifically, 1) Examples of lithium-containing compounds having an olivine type structure include lithium iron phosphate; lithium iron phosphate in which at least one of cobalt, manganese and nickel is dissolved; lithium cobalt phosphate; manganese and nickel And lithium cobalt phosphate in which at least one of them is dissolved; lithium manganese phosphate; lithium manganese phosphate in which nickel is dissolved, and lithium nickel phosphate.

2)層状岩塩型又は立方晶岩塩型の結晶構造を有する岩塩類縁構造の含リチウム化合物としては、例えば、ニッケル酸リチウム;コバルト及びアルミニウムの少なくとも1種を固溶したニッケル酸リチウム;コバルト酸リチウム;鉄酸リチウム;チタン、マンガンの少なくとも1種を固溶した鉄酸リチウム;チタン酸リチウム等が挙げられる。   2) Examples of the lithium-containing compound having a rock salt-like structure having a layered rock salt type or cubic rock salt type crystal structure include lithium nickelate; lithium nickelate in which at least one of cobalt and aluminum is dissolved; lithium cobaltate; Examples thereof include lithium ferrate; lithium ferrate in which at least one of titanium and manganese is dissolved, lithium titanate, and the like.

3)スピネル型構造の含リチウム化合物としては、例えば、マンガン酸リチウム;及びクロムを固溶したマンガン酸リチウム等が挙げられる。   3) Examples of the lithium-containing compound having a spinel structure include lithium manganate; and lithium manganate in which chromium is dissolved.

これらの正極活物質は単独又は2種以上を混合して使用できる。本発明では、電極用複合粉末の製造条件を好適化することにより、ニッケル、コバルト、マンガン等の高価数を採り得る遷移金属を活物質として用いる場合でも、その還元を抑制しつつ導電材と強固に接合して電極用複合粉末とすることができる。   These positive electrode active materials can be used individually or in mixture of 2 or more types. In the present invention, by optimizing the manufacturing conditions of the composite powder for electrodes, even when a transition metal capable of taking an expensive number such as nickel, cobalt, manganese, etc. is used as an active material, the conductive material and the conductive material are strongly suppressed while suppressing the reduction. To form a composite powder for an electrode.

負極活物質としては、例えば、炭素、珪素、ゲルマニウム、スズ、鉛、アンチモン、アルミニウム、インジウム、リチウム、酸化スズ、チタン酸リチウム、窒化リチウム、インジウムを固溶した酸化錫、インジウム−錫合金、リチウム−アルミニウム合金、リチウム−インジウム合金等が挙げられる。負極活物質も単独又は2種以上で使用できる。   Examples of the negative electrode active material include carbon, silicon, germanium, tin, lead, antimony, aluminum, indium, lithium, tin oxide, lithium titanate, lithium nitride, indium-dissolved tin oxide, indium-tin alloy, lithium -Aluminum alloy, lithium-indium alloy, etc. are mentioned. The negative electrode active materials can be used alone or in combination of two or more.

電極活物質は市販品を使用すればよいが、調製することもできる。例えば、コバルト酸リチウムは、炭酸コバルトと炭酸リチウムとを混合して800〜1000℃で焼成する方法などで調製できる。   A commercially available electrode active material may be used, but it can also be prepared. For example, lithium cobaltate can be prepared by a method in which cobalt carbonate and lithium carbonate are mixed and baked at 800 to 1000 ° C.

また、鉄含有マンガン酸リチウムは、例えば、次の手順で調製できる。即ち、Fe(NO・9HOとMnCl・4HOの混合水溶液を出発物質とし、これを−10℃に保持したLiOHの水−エタノール混合溶液に滴下して共沈物を作製後、沈殿を熟成する。かかる沈殿物にLiOH・HO、KOH及びKClOを加えて蒸留水中で混合後、220℃で5時間水熱処理を行う。水洗後、得られる沈殿物とLiOH水溶液を混合し、乾燥後、850℃まで1時間かけて昇温後、1分間保持する。この焼成物を水洗・濾過・乾燥することにより鉄含有マンガン酸リチウムは得られる(例えば、M. Tabuchi, Y.
Nabeshima, K. Ado, M. Shikano, H. Kageyama, and K. Tatsumi, IMLB 2006 Meeting Abstracts #5 (2006) )。
The iron-containing lithium manganate can be prepared, for example, by the following procedure. That, Fe (NO 3) 3 · 9H 2 and O and MnCl 2 · 4H 2 O mixed aqueous solution starting material, LiOH in water were kept at -10 ° C. - dropping to coprecipitate ethanol mixed solution After preparation, the precipitate is aged. LiOH.H 2 O, KOH and KClO 3 are added to the precipitate and mixed in distilled water, followed by hydrothermal treatment at 220 ° C. for 5 hours. After washing with water, the resulting precipitate and LiOH aqueous solution are mixed, dried, heated to 850 ° C. over 1 hour, and held for 1 minute. The fired product is washed, filtered, and dried to obtain iron-containing lithium manganate (for example, M. Tabuchi, Y.
Nabeshima, K. Ado, M. Shikano, H. Kageyama, and K. Tatsumi, IMLB 2006 Meeting Abstracts # 5 (2006)).

電極活物質の平均粒子径(電極用複合粉末における平均粒子径)は限定的ではないが、0.01〜50μm程度が好ましく、0.02〜30μm程度がより好ましい。なお、電極活物質の平均粒子径は、メカノフュージョン処理及び通電焼結に供する前後において、ほぼ同程度である。   The average particle size of the electrode active material (average particle size in the composite powder for electrodes) is not limited, but is preferably about 0.01 to 50 μm, more preferably about 0.02 to 30 μm. The average particle diameter of the electrode active material is approximately the same before and after being subjected to mechanofusion treatment and current sintering.

≪導電材≫
導電材(電子伝導性粉末)としては、電子伝導性を有する材料であれば限定的ではなく、例えば、炭素、炭素基導電化合物、鉄、鉄を含む合金、銅、銅を含む合金、アルミニウム、アルミニウムを含む合金、酸化鉄、酸化鉄を端成分とする固溶体等が挙げられる。導
電材としては、これらの材料の単独又は2種以上を混合して使用できる。
≪Conductive material≫
The conductive material (electron conductive powder) is not limited as long as it is a material having electronic conductivity. For example, carbon, a carbon-based conductive compound, iron, an alloy containing iron, copper, an alloy containing copper, aluminum, Examples thereof include alloys containing aluminum, iron oxide, and solid solutions having iron oxide as an end component. As a conductive material, these materials can be used alone or in combination of two or more.

上記の導電材のうち、炭素基導電化合物とは、主としてベンゼン骨格等の電子伝導経路を有し、炭素を主成分とする化合物である。例えば、ポリアセン、ポリパラフェニレン、ポリチオフェン等が挙げられる。   Among the conductive materials described above, the carbon-based conductive compound is a compound mainly having an electron conduction path such as a benzene skeleton and having carbon as a main component. For example, polyacene, polyparaphenylene, polythiophene and the like can be mentioned.

合金のうち、鉄を含む合金としては、例えば、Fe−Cr合金、Fe−Ni合金、Fe−Mg合金等が挙げられる。銅を含む合金としては、例えば、Ni−Cu合金、Cu−Sn合金、Cu−Zn合金等が挙げられる。アルミニウムを含む合金としては、例えば、Al−Zn合金、Al−Cu合金、Al−Mg合金等が挙げられる。合金中の各成分の割合は特に限定されず、適宜設定できる。   Among the alloys, examples of the alloy containing iron include an Fe—Cr alloy, an Fe—Ni alloy, and an Fe—Mg alloy. Examples of the alloy containing copper include a Ni—Cu alloy, a Cu—Sn alloy, and a Cu—Zn alloy. Examples of the alloy containing aluminum include an Al—Zn alloy, an Al—Cu alloy, and an Al—Mg alloy. The ratio of each component in the alloy is not particularly limited and can be set as appropriate.

酸化鉄を端成分とする固溶体としては、例えば、酸化鉄にZn、Mn、Ni、Al、Ti、Co等を固溶させたものが挙げられる。固溶量は特に限定されず、適宜設定できる。   As a solid solution having iron oxide as an end component, for example, a solid solution of iron, Zn, Mn, Ni, Al, Ti, Co or the like can be cited. The amount of solid solution is not particularly limited, and can be set as appropriate.

上記導電材のうち、炭素材料が好ましく、例えば、アセチレンブラック(AB)粉末を好適に使用できる。   Among the conductive materials, a carbon material is preferable. For example, acetylene black (AB) powder can be suitably used.

導電材の平均粒子径(電極用複合粉末における平均粒子径)は限定的ではないが、0.005〜10μm程度が好ましく、0.01〜1μm程度がより好ましい。なお、かかる導電材の平均粒子径は、電極活物質との混合物に対して行うメカノフュージョン処理及び通電焼結の前後においてほぼ同程度である。また、電極用複合粉末中における導電材含有量は0.01〜30重量%程度が好ましく、0.02〜25重量%程度がより好ましい。   The average particle diameter of the conductive material (average particle diameter in the composite powder for electrodes) is not limited, but is preferably about 0.005 to 10 μm, and more preferably about 0.01 to 1 μm. In addition, the average particle diameter of this electrically conductive material is substantially the same before and after the mechano-fusion treatment performed on the mixture with the electrode active material and the electric current sintering. The conductive material content in the composite powder for electrodes is preferably about 0.01 to 30% by weight, more preferably about 0.02 to 25% by weight.

≪電極用複合粉末≫
本発明の電極用複合粉末は、前記電極活物質どうしが前記導電材を介して接合している構造を有する。例えば、導電材が表面に付着した又は導電材によって被覆された電極活物質どうしが接合している構造が挙げられる。
≪Electrode composite powder≫
The composite powder for electrodes of the present invention has a structure in which the electrode active materials are joined via the conductive material. For example, there is a structure in which electrode active materials attached to the surface or covered with the conductive material are joined to each other.

このような電極用複合粉末の密度は限定的ではないが、例えば、タップ密度が0.8g/cm以上が好ましく、1g/cm以上がより好ましい。なお、本明細書におけるタップ密度は、約0.2gの試料(ここでは電極用複合粉末)を25mlのメスシリンダーに入れて100回タップを行った後、測定した密度である。 The density of such composite powder for electrodes is not limited, but for example, the tap density is preferably 0.8 g / cm 3 or more, and more preferably 1 g / cm 3 or more. In addition, the tap density in this specification is a density measured after putting about 0.2 g of a sample (here, composite powder for electrodes) into a 25 ml graduated cylinder and tapping 100 times.

本発明の電極用複合粉末は、電極活物質と導電材との関係において強固な接合強度(強固な導電ネットワーク)を有している。そして、電極活物質どうしは導電材を介して接合ている。この様な電極用複合粉末は、各種電池やキャパシタの電極材料として有用であり、重量エネルギー密度及び体積エネルギー密度を低下させることなく、高電流密度での充放電特性を高めた電極を作製することができる。   The electrode composite powder of the present invention has a strong bonding strength (a strong conductive network) in the relationship between the electrode active material and the conductive material. The electrode active materials are joined to each other through a conductive material. Such a composite powder for electrodes is useful as an electrode material for various batteries and capacitors, and it is possible to produce an electrode with improved charge / discharge characteristics at a high current density without lowering the weight energy density and volume energy density. Can do.

具体的には、本発明の電極用複合粉末は、一次電池、二次電池、燃料電池、キャパシタ用の電極粉末として有用である。   Specifically, the composite powder for electrodes of the present invention is useful as an electrode powder for primary batteries, secondary batteries, fuel cells, and capacitors.

例えば、有機電解液系電池に適用する場合には、金属箔(又は金属メッシュ)上に電極用複合粉末からなる層を形成して正極シート及び/又は負極シートを得た後、正極シート及び負極シートで電解液を染み込ませたセパレータを挟むことにより、高電流密度で高容量を示す充放電サイクル特性に優れたリチウム二次電池を作製できる。尚、電極用複合粉末にバインダ(例えば、ポリビニリデンフルオライド等)を混練することにより、より容易に金属箔(又は金属メッシュ)上に電極用複合粉末層を形成できる。   For example, when applied to an organic electrolyte battery, a positive electrode sheet and / or a negative electrode sheet are obtained after forming a layer made of a composite powder for electrodes on a metal foil (or metal mesh), and then the positive electrode sheet and the negative electrode By sandwiching a separator soaked with an electrolyte solution with a sheet, a lithium secondary battery excellent in charge / discharge cycle characteristics exhibiting a high capacity at a high current density can be produced. The electrode composite powder layer can be more easily formed on the metal foil (or metal mesh) by kneading a binder (for example, polyvinylidene fluoride) in the electrode composite powder.

例えば、有機電解液系リチウム二次電池を作製する場合には、電極用複合粉末とバインダ(例えば、ポリビニリデンフルオライドなど)と混錬して電極合剤を形成し、正極シート及び/又は負極シートを得た後、正極シート及び負極シートで電解液を染み込ませたセパレータを挟むことにより、高電流密度で高容量を示す充放電サイクル特性に優れたリチウム二次電池を作製できる。   For example, when producing an organic electrolyte lithium secondary battery, an electrode mixture is formed by kneading a composite powder for an electrode and a binder (for example, polyvinylidene fluoride, etc.), and a positive electrode sheet and / or a negative electrode After the sheet is obtained, a lithium secondary battery excellent in charge / discharge cycle characteristics exhibiting a high capacity at a high current density can be produced by sandwiching a separator impregnated with an electrolytic solution between the positive electrode sheet and the negative electrode sheet.

2.電極用複合粉末の製造方法
本発明の電極用複合粉末の製造方法は、
(1)電極活物質と導電材とを含有する原料混合物をメカノフュージョン処理することによって前記電極活物質と前記導電材とを予め結着させ、次いで、
(2)前記結着後の原料混合物を、導電性を有する型に充填し、60MPa以上の加圧下において直流パルス電流を通電して焼結させる工程を有する。
2. Method for producing composite powder for electrode The method for producing a composite powder for an electrode of the present invention comprises:
(1) The electrode active material and the conductive material are previously bound by subjecting the raw material mixture containing the electrode active material and the conductive material to mechanofusion treatment,
(2) A step of filling the raw material mixture after the binding into a conductive mold, and applying a direct current pulse current under a pressure of 60 MPa or more to sinter.

原料混合物における電極活物質と導電材との混合比としては、導電材の量を、電極活物質及び導電材の合算量の0.01〜30重量%とすればよく、0.02〜25重量%が好ましい。導電材の量が0.01重量%未満では、電極活物質の電子伝導性の向上が不十分となり、良好な充放電サイクル特性が得られないおそれがある。30重量%以上では、電極活物質の重量比率及び体積比率の低下に伴って、電池の重量出力密度及び体積出力密度が低下するため好ましくない。   As a mixing ratio of the electrode active material and the conductive material in the raw material mixture, the amount of the conductive material may be 0.01 to 30% by weight of the total amount of the electrode active material and the conductive material, and 0.02 to 25% by weight. % Is preferred. When the amount of the conductive material is less than 0.01% by weight, the improvement of the electron conductivity of the electrode active material becomes insufficient, and good charge / discharge cycle characteristics may not be obtained. If it is 30% by weight or more, the weight output density and the volume output density of the battery decrease with a decrease in the weight ratio and volume ratio of the electrode active material, which is not preferable.

≪メカノフュージョン処理≫
メカノフュージョン処理は、複数の異なる粒子間に機械的エネルギー(機械的歪力)を加えて、異なる粒子どうしを結着させる処理であり、本発明では原料混合物に少なくとも圧縮力と剪断力とを加えることによって電極活物質と導電材とを結着させる処理である。
≪Mechanofusion process≫
The mechanofusion process is a process in which mechanical energy (mechanical strain force) is applied between a plurality of different particles to bind the different particles. In the present invention, at least a compression force and a shear force are applied to the raw material mixture. This is a process for binding the electrode active material and the conductive material.

上記処理は、通常、図4の概略図に示されるようなメカノフュージョン装置により行う。図4の装置は、高速回転可能なケーシング(容器)1とその内部に固定された半円柱状のインナーピース2(摩擦部材)とスクレーパー3(掻き取り部材)とを有する。図4中の4は原料混合物である。図4には図示されていないが、摩擦熱による異常昇温を防止するために、ケーシングを取り囲むように冷却機が設置されていてもよい。   The above processing is usually performed by a mechanofusion apparatus as shown in the schematic diagram of FIG. The apparatus of FIG. 4 includes a casing (container) 1 that can rotate at high speed, a semi-cylindrical inner piece 2 (friction member), and a scraper 3 (scraping member) fixed inside the casing. 4 in FIG. 4 is a raw material mixture. Although not shown in FIG. 4, a cooler may be installed so as to surround the casing in order to prevent abnormal temperature rise due to frictional heat.

ケーシング1内に原料混合物を供給し、ケーシング1を高速回転させると、原料混合物はケーシング1の内壁面に遠心力により押し付けられて層4を形成する。ケーシング1の回転条件は限定的ではないが、1000〜8000rpmが好ましく、2000〜7000rpmがより好ましい。ケーシング1が回転中、原料混合物はインナーピース2とケーシング1との隙間(クリアランス)で少なくとも圧縮力及び剪断力を受ける。機械的歪力を受けた原料混合物は、スクレーパー3により掻き取られて再び原料混合物4に混じる。この処理を連続的に繰り返すことにより、電極活物質と導電材の分散性が均一化するとともに、両者が徐々に強く結着する。   When the raw material mixture is supplied into the casing 1 and the casing 1 is rotated at a high speed, the raw material mixture is pressed against the inner wall surface of the casing 1 by centrifugal force to form the layer 4. Although the rotation conditions of the casing 1 are not limited, 1000-8000 rpm is preferable and 2000-7000 rpm is more preferable. While the casing 1 is rotating, the raw material mixture receives at least a compressive force and a shearing force in a gap (clearance) between the inner piece 2 and the casing 1. The raw material mixture subjected to the mechanical strain is scraped off by the scraper 3 and mixed with the raw material mixture 4 again. By repeating this process continuously, the dispersibility of the electrode active material and the conductive material is made uniform, and the two are gradually strongly bonded.

上記クリアランスは0.1〜10mm程度が好ましく、0.2〜8mm程度がより好ましい。また、処理時間は回転条件に応じて設定するが1〜30分程度が好ましく、1〜25分程度がより好ましい。回転数が1000rpm未満又は処理時間が1分未満の場合には、結着程度が不十分になるおそれがある。他方、回転数が8000rpm超過又は処理時間が30分超過の場合には、電極活物質や導電材の過度な変形や温度上昇による変性等が生じる可能性がある。   The clearance is preferably about 0.1 to 10 mm, and more preferably about 0.2 to 8 mm. Moreover, although processing time is set according to rotation conditions, about 1 to 30 minutes are preferable and about 1 to 25 minutes are more preferable. If the rotational speed is less than 1000 rpm or the processing time is less than 1 minute, the degree of binding may be insufficient. On the other hand, when the rotational speed exceeds 8000 rpm or the processing time exceeds 30 minutes, there is a possibility that the electrode active material or the conductive material is excessively deformed or modified due to a temperature rise.

メカノフュージョン装置としては、例えば、特開昭63−42728号公報に記載の粉粒体処理装置が挙げられ、具体的には、ホソカワミクロン(株)製のメカノフュージョンシステムが好適である。   Examples of the mechanofusion apparatus include a powder and particle processing apparatus described in Japanese Patent Application Laid-Open No. 63-42728. Specifically, a mechanofusion system manufactured by Hosokawa Micron Corporation is suitable.

≪通電焼結法≫
通電焼結法(通電接合法)としては、放電プラズマ焼結法、放電焼結法、プラズマ活性化焼結法等と称される直流パルス電流を通電する加圧焼結法であればよい。具体的には、所定の形状の導電性を有する型に試料を充填し、加圧しながらパルス状ON−OFF直流電流を通電することによって、加圧下における通電焼結を行うものであればよい。かかる通電焼結装置及びその作動原理は、例えば、特開平10−251070号公報などに開示されている。
≪Electrical sintering method≫
The electric current sintering method (electric current joining method) may be a pressure sintering method in which a direct current pulse current referred to as a discharge plasma sintering method, a discharge sintering method, a plasma activated sintering method or the like is applied. Specifically, any material may be used as long as it conducts current sintering under pressure by filling a predetermined mold with a conductive mold and applying a pulsed ON-OFF direct current while applying pressure. Such an electric sintering apparatus and its operating principle are disclosed in, for example, Japanese Patent Laid-Open No. 10-251070.

放電プラズマ焼結機の模式図を図5に示す。図5に示される放電プラズマ焼結機1は、試料2を装填するダイ(型)3と上下一対のパンチ4及び5とを有する。パンチ4及び5は、それぞれパンチ電極6及び7に支持されており、このパンチ電極6及び7を介して、ダイ3に装填された試料2に必要に応じて加圧しながらパルス電流を供給できる。試料2に与える電流の種類としてはパルス電流が好ましい。パルス通電によって、試料2及びその近傍(ダイ3及び上下部パンチ4及び5)が加熱され、その加熱及びパルス電流の両方の効果により通電焼結体が得られる。   A schematic diagram of the spark plasma sintering machine is shown in FIG. A discharge plasma sintering machine 1 shown in FIG. 5 includes a die (die) 3 on which a sample 2 is loaded and a pair of upper and lower punches 4 and 5. The punches 4 and 5 are supported by punch electrodes 6 and 7, respectively, and a pulse current can be supplied through the punch electrodes 6 and 7 while pressing the sample 2 loaded on the die 3 as necessary. A pulse current is preferable as the type of current applied to the sample 2. The sample 2 and its vicinity (the die 3 and the upper and lower punches 4 and 5) are heated by pulse energization, and an energized sintered body is obtained by the effects of both the heating and the pulse current.

以下、電極活物質及び導電材の結着粉末(「結着混合物」とも言う)を、通電焼結機の電子伝導性型材内に充填後、60MPa以上の加圧下において通電焼結する手段について具体的に説明する。   Hereinafter, specific description will be given of a means for conducting current sintering under a pressure of 60 MPa or more after filling an electrode active material and a binder powder of a conductive material (also referred to as a “binding mixture”) into an electron conductive mold of the current sintering machine. I will explain it.

通電処理に用いる電子伝導性型材としては、電子伝導性を有し、60MPa以上の圧力条件に耐え得るものであれば特に限定されない。例えば、タングステンカーバイド、鉄、銅、アルミニウム合金(例えばAl−Cu−Mg系合金)等を好適に使用できる。上記の型材の中でも特にタングステンカーバイド(WC)は超硬型材であるため耐圧性が高く、しかも通電焼結時における電極活物質の還元を抑制し易い観点から好ましい。   The electron conductive mold used for the energization treatment is not particularly limited as long as it has electron conductivity and can withstand pressure conditions of 60 MPa or more. For example, tungsten carbide, iron, copper, an aluminum alloy (for example, an Al—Cu—Mg alloy) or the like can be preferably used. Among the above mold materials, tungsten carbide (WC) is a cemented carbide mold material, so that it has high pressure resistance and is preferable from the viewpoint of easily suppressing reduction of the electrode active material during current sintering.

電子伝導性型材に直流パルス電流を印加することにより、充填された結着混合物の粒子間隙に生じる放電現象を利用して、放電プラズマ、放電衝撃圧力等による粒子表面の浄化活性化作用及び電場により生じる電界拡散効果やジュール熱による熱拡散効果、加圧による塑性変形圧力等が粒子接合の駆動力となって電極活物質どうしが導電材を介して接合される。具体的には、パルス電流の印加により、導電材の一部が気化して電極活物質表面に付着(被覆)し、そこに粒子の状態の導電材が接着し、これらが連続して起こることで電極活物質が導電材を介して強固に接合する。電極活物質の焼結もごく一部で起こることも考えられるが、電極活物質どうしが隣接して焼結するよりも導電材を介して接合していく場合が殆どであると考えられる。   By applying a direct current pulse current to the electron conductive mold material, it is possible to utilize the discharge phenomenon generated in the particle gap of the filled binding mixture, and to activate the purification of the particle surface by discharge plasma, discharge impact pressure, etc. and the electric field. The generated electric field diffusion effect, the thermal diffusion effect due to Joule heat, the plastic deformation pressure due to pressurization, etc. serve as the driving force for particle bonding, and the electrode active materials are bonded together via the conductive material. Specifically, when a pulse current is applied, a part of the conductive material is vaporized and adheres (covers) to the surface of the electrode active material, and the conductive material in the form of particles adheres to it, which continuously occurs. Thus, the electrode active material is firmly bonded via the conductive material. Although it is conceivable that only a part of the electrode active material is sintered, it is considered that the electrode active materials are joined together via a conductive material rather than being sintered adjacent to each other.

電流を供給する際の条件としては、結着混合物に60MPa以上の圧力をかけて(加圧下に)通電する。好ましくはパルス電流を供給することが望ましい。圧力としては、60MPa以上とするが、150MPa以上(例えば150〜1000MPa)、300MPa以上(例えば300〜1000MPa)がより好ましい。耐圧条件を備えれば500MPa以上(例えば500〜1000MPa)でもよい。電極活物質と導電材との接合を十分なものとするためには、高圧条件が望ましいが、50000MPa程度を上限とする。   As a condition for supplying current, a current of 60 MPa or higher is applied to the binder mixture (under pressure). It is preferable to supply a pulse current. The pressure is 60 MPa or more, but 150 MPa or more (for example, 150 to 1000 MPa) or 300 MPa or more (for example, 300 to 1000 MPa) is more preferable. It may be 500 MPa or more (for example, 500 to 1000 MPa) as long as the pressure resistance condition is provided. In order to achieve sufficient bonding between the electrode active material and the conductive material, high pressure conditions are desirable, but the upper limit is about 50000 MPa.

また、結着混合物に電流を供給する際のダイ3(図5参照)の温度は、電極活物質及び導電材の種類や粒径などに応じて適宜選択することができるが、通常100〜800℃、好ましくは150〜700℃程度である。100℃未満では電極活物質と導電材との接合が不十分となる場合がある。800℃以上では導電材又は電子伝導性型材の還元による電極活物質の分解が起こり得るため好ましくない。従って、150〜700℃程度の加熱が好適である。   Further, the temperature of the die 3 (see FIG. 5) at the time of supplying current to the binding mixture can be appropriately selected according to the type and particle size of the electrode active material and the conductive material, but is usually 100 to 800. ° C, preferably about 150 to 700 ° C. If it is less than 100 degreeC, joining of an electrode active material and a electrically conductive material may become inadequate. Above 800 ° C., the electrode active material may be decomposed by reduction of the conductive material or the electron conductive mold material, which is not preferable. Therefore, heating at about 150 to 700 ° C. is preferable.

加熱のために印加するパルス電流は、例えばパルス幅2〜3ミリ秒程度で、周期は3Hz〜300kHz程度のパルス状ON−OFF直流電流を用いればよい。電流値は型材の種類及び大きさにより異なるが、例えば内径10mmのタングステンカーバイド型材を用いた場合には300〜1000A程度、内径20mmの型材を用いた場合には500〜3000A程度が好適である。処理時は、型材温度をモニターしながら電流値を増減させ、所定の温度を管理できるように電流値を制御するか、もしくは投入電気エネルギー量(Wh値)を制御すればよい。   The pulse current applied for heating may be a pulsed ON / OFF direct current having a pulse width of about 2 to 3 milliseconds and a period of about 3 Hz to 300 kHz. The current value varies depending on the type and size of the mold material. For example, about 300 to 1000 A is preferable when a tungsten carbide mold material having an inner diameter of 10 mm is used, and about 500 to 3000 A is preferable when a mold material having an inner diameter of 20 mm is used. During processing, the current value may be increased or decreased while monitoring the mold temperature, and the current value may be controlled so that a predetermined temperature can be managed, or the input electric energy amount (Wh value) may be controlled.

通電焼結による焼結時間については、使用する結着混合物の量、焼結温度などによって異なるので、一概に規定できないが、通常、上記した加熱温度範囲に1分〜2時間程度保持すればよい。   The sintering time by electric current sintering varies depending on the amount of the binder mixture to be used, the sintering temperature, etc., and thus cannot be specified in general, but usually it should be kept in the above heating temperature range for about 1 minute to 2 hours. .

このようにして得られた本発明の電極用複合材料は、電極用複合材料に対する導電材の重量比が、1:0.0001〜0.3程度、好ましくは1:0.0002〜0.25程度である。   In the electrode composite material of the present invention thus obtained, the weight ratio of the conductive material to the electrode composite material is about 1: 0.0001 to 0.3, preferably 1: 0.0002 to 0.25. Degree.

所定の温度で通電焼結処理を行った混合粉は冷却後、型材から取り出し、乳鉢等で軽く粉砕することにより導電材が接合した電極活物質を回収することができる。多量の接合処理を行う場合には、大きな型材を用い、上記のプロセスをスケールアップすればよい。このようにして本発明の電極用複合粉末は得られる。   The mixed powder that has been subjected to the electric current sintering treatment at a predetermined temperature is cooled, taken out from the mold material, and lightly pulverized with a mortar or the like, whereby the electrode active material to which the conductive material is bonded can be recovered. When a large amount of bonding processing is performed, the above process may be scaled up using a large mold material. Thus, the composite powder for electrodes of the present invention is obtained.

上記では、電極活物質及び導電材の結着混合物を通電焼結法で処理して電極用複合粉末を製造する方法について説明した。尚、1)上記した電極活物質及び導電材の結着混合物からなる層を金属箔(又は金属メッシュ)上に形成したシート、前記1)のシートを巻き取って得られるロール状物を通電焼結法で処理する場合には、本発明の電極用複合粉末が金属箔上に層状に付着した電極材料を効率的に製造できる。上記混合粉末にバインダ(例えば、ポリビリニデンフルオライド等)を添加した場合には、金属箔(又は金属メッシュ)上に電極用複合粉末層をより形成し易くなる。バインダの添加量は特に限定されず、電極活物質及び導電材の種類等に応じて適宜調整すればよい。通常は、バインダは通電焼結により除去されるが、炭化した状態で残留した場合には、本発明における導電材と同様に取り扱えばよい。   In the above description, the method for producing the composite powder for an electrode by treating the binder mixture of the electrode active material and the conductive material by the electric current sintering method has been described. Incidentally, 1) a sheet obtained by winding the above-mentioned electrode active material and conductive material binding layer on a metal foil (or metal mesh), and a roll obtained by winding the sheet of the above 1) is electro-baked. In the case of processing by the sintering method, it is possible to efficiently produce an electrode material in which the composite powder for electrodes of the present invention adheres in layers on a metal foil. When a binder (for example, polyvinylidene fluoride) is added to the mixed powder, it becomes easier to form a composite powder layer for an electrode on a metal foil (or metal mesh). The addition amount of the binder is not particularly limited, and may be appropriately adjusted according to the types of the electrode active material and the conductive material. Normally, the binder is removed by electric sintering, but if it remains in a carbonized state, it may be handled in the same manner as the conductive material in the present invention.

本発明の電極用複合粉末は、原料混合物をメカノフュージョン処理後、60MPa以上の加圧下で通電焼結することにより得るため、電極活物質と導電材との接合強度が大きく、これにより電極活物質と導電材との導電ネットワークが強固である。このような電極用複合粉末は、高電流密度で充放電を繰り返した場合でも導電ネットワークが損なわれ難く、各種電池及びキャパシタに適用し得る電極粉末として有用である。本発明の電極用複合粉末は、とりわけリチウム二次電池に対して有用性が高い。   Since the composite powder for electrodes of the present invention is obtained by subjecting the raw material mixture to electro-sintering under a pressure of 60 MPa or more after the mechanofusion treatment, the bonding strength between the electrode active material and the conductive material is large, thereby the electrode active material. And the conductive network of the conductive material is strong. Such a composite powder for an electrode is useful as an electrode powder that can be applied to various batteries and capacitors because the conductive network is hardly damaged even when charging and discharging are repeated at a high current density. The composite powder for electrodes of the present invention is particularly useful for lithium secondary batteries.

以下に実施例及び比較例を示して本発明を具体的に説明する。但し、本発明は実施例に限定されない。   The present invention will be specifically described below with reference to examples and comparative examples. However, the present invention is not limited to the examples.

実施例1
鉄含有LiMnO(組成式Li1.2Fe0.4Mn0.4)を合成した。
Example 1
Iron-containing Li 2 MnO 3 (compositional formula Li 1.2 Fe 0.4 Mn 0.4 O 2 ) was synthesized.

先ず、Fe(NO・9HOとMnCl・4HOの混合水溶液(モル比でFe:Mn=1:1)を出発物質とし、これを−10℃に制御されたLiOHの水−エタノ
ール混合溶液に滴下して共沈物を作製した。その後、混合溶液に空気泡を送りながら撹拌することで沈殿を一夜間熟成した。これを濾過後、得られる共沈物にLiOH・HO、KOH、KClOを加えて蒸留水中で混合し、220℃、5時間水熱処理を行った。水洗後、得られる沈殿物とLiOH水溶液を混合し、乾燥後、850℃まで1時間かけて昇温後、1分間保持した。この焼成物を水洗・濾過・乾燥することにより目的の鉄含有マンガン酸リチウム(Li1.2Fe0.4Mn0.4)を得た。
First, (a molar ratio of Fe: Mn = 1: 1) Fe (NO 3) 3 · 9H 2 O and MnCl 2 · 4H 2 O mixed aqueous solution of a starting material, LiOH in which this is controlled to -10 ° C. A coprecipitate was prepared by dropping into a water-ethanol mixed solution. Thereafter, the precipitate was aged overnight by stirring while sending air bubbles to the mixed solution. After filtration, LiOH.H 2 O, KOH and KClO 3 were added to the resulting coprecipitate and mixed in distilled water, followed by hydrothermal treatment at 220 ° C. for 5 hours. After washing with water, the resulting precipitate and a LiOH aqueous solution were mixed, dried, heated to 850 ° C. over 1 hour, and held for 1 minute. The fired product was washed, filtered, and dried to obtain the target iron-containing lithium manganate (Li 1.2 Fe 0.4 Mn 0.4 O 2 ).

上記鉄含有LiMnOを電極活物質とし、市販のアセチレンブラック(AB)粉末を導電材とし、両者を重量比で97:3となるよう混合して原料混合物とした。電極活物質の比表面積は21.8m/gで、球換算粒径で約0.05μmであった。AB粉末の比表面積は約70m/gで、球換算粒径で約0.04μmであった。次に、原料混合物をホソカワミクロン(株)製メカノフュージョン装置 AMS−Miniに投入し、クリアランス1mm、ケーシング回転速度6970rpmとし、2分間メカノフュージョン処理を行った。 The iron-containing Li 2 MnO 3 was used as an electrode active material, a commercially available acetylene black (AB) powder was used as a conductive material, and both were mixed at a weight ratio of 97: 3 to obtain a raw material mixture. The specific surface area of the electrode active material was 21.8 m 2 / g, and the spherical equivalent particle size was about 0.05 μm. The specific surface area of AB powder was about 70 m 2 / g, and the spherical equivalent particle size was about 0.04 μm. Next, the raw material mixture was put into a mechanofusion apparatus AMS-Mini manufactured by Hosokawa Micron Co., Ltd., and a mechanofusion treatment was performed for 2 minutes with a clearance of 1 mm and a casing rotational speed of 6970 rpm.

次に、結着後の原料混合物を内径10mmのWC型材に充填し、通電焼結機内にセットして約20Paまで減圧後、窒素ガスを大気圧になるまで導入した。次いで、WC型材を約500MPaで加圧しながら約400Aのパルス電流(パルス幅2.5ミリ秒のON−OFF直流電流、周期29Hz)を通電した。WC型材近傍は約50℃/分の昇温速度で加熱され、パルス電流の通電開始約5分後に270℃に到達した。この温度で約20分間保持した後、電流の通電と加圧を停止し、自然放冷させた。室温に冷却後、Li1.2Fe0.4Mn0.4−AB複合粉末(焼結体)を型材から取り出し、電極用粉末を得た。 Next, the bonded raw material mixture was filled in a WC type material having an inner diameter of 10 mm, set in an electric current sintering machine, depressurized to about 20 Pa, and then introduced with nitrogen gas to atmospheric pressure. Next, a pulse current of about 400 A (ON-OFF DC current with a pulse width of 2.5 milliseconds, cycle 29 Hz) was applied while the WC mold was pressed at about 500 MPa. The vicinity of the WC mold was heated at a heating rate of about 50 ° C./min, and reached 270 ° C. about 5 minutes after the start of pulse current application. After holding at this temperature for about 20 minutes, the current application and pressurization were stopped and the mixture was allowed to cool naturally. After cooling to room temperature, Li 1.2 Fe 0.4 Mn 0.4 O 2 —AB composite powder (sintered body) was taken out of the mold material to obtain electrode powder.

複合粉末は黒色であり、X線回折パターンでは2θ=26°近傍にAB由来の幅広のハローが認められ、それ以外のピークは六方晶系の層状岩塩型鉄含有マンガン酸リチウムの単位胞(空間群R3m)で指数付けできた。   The composite powder is black, and in the X-ray diffraction pattern, a broad halo derived from AB is observed in the vicinity of 2θ = 26 °, and the other peaks are hexagonal layered rock salt type iron-containing lithium manganate unit cells (space Index was possible with group R3m).

≪充放電特性≫
電極用粉末をリチウム二次電池の正極材料として用い、負極にリチウム金属、集電体にアルミニウムメッシュ、電解液としてLiPFをエチレンカルボネート/ジメチルカルボネート混合液に溶解させたものを用いて、電流密度42.5mA/g(1/3C)〜3825mA/g(30C)、カットオフ2.0〜4.8Vにおける定電流測定で充放電試験を行った。
≪Charge / discharge characteristics≫
Using the electrode powder as a positive electrode material of a lithium secondary battery, using lithium metal as a negative electrode, aluminum mesh as a current collector, and LiPF 6 dissolved in an ethylene carbonate / dimethyl carbonate mixture as an electrolyte, A charge / discharge test was conducted by constant current measurement at a current density of 42.5 mA / g (1/3 C) to 3825 mA / g (30 C) and a cutoff of 2.0 to 4.8 V.

図1に、リチウム二次電池の放電容量を、1/3Cでの容量を100%とした時の各レートにおける容量維持率として示す。5C未満のレートでは、メカノフュージョン処理のみの場合(比較例1)、通電処理のみの場合(比較例2)及びメカノフュージョン、通電焼結処理のいずれの処理も施さない場合(比較例3)とほぼ同等の容量を示したが、5C以上の高電流密度においてはこれら3つの場合に比べ、容量の増大が認められた。図2には1C、5C、20Cでの放電曲線を示すが、比較の3例に比べいずれも放電容量が高く、特に5C以上の高電流密度において放電平均電位が高いことが特徴で、活物質−導電材間の接合が良好で電子伝導性が充分に確保されていることを示唆している。   FIG. 1 shows the discharge capacity of the lithium secondary battery as the capacity maintenance rate at each rate when the capacity at 1/3 C is 100%. At a rate of less than 5C, the case of only mechanofusion processing (Comparative Example 1), the case of only energization processing (Comparative Example 2), and the case of not performing any of mechanofusion and electroconductive sintering processing (Comparative Example 3) Although almost the same capacity was shown, an increase in capacity was recognized at a high current density of 5 C or more compared to these three cases. FIG. 2 shows discharge curves at 1C, 5C, and 20C, all of which have a higher discharge capacity than the three comparative examples, and are particularly characterized by a high discharge average potential at a high current density of 5C or more. -It suggests that the bonding between the conductive materials is good and the electron conductivity is sufficiently secured.

以上より、本発明の電極用複合粉末は、高電流密度で高エネルギー密度を示し、優れたレート特性を有するリチウム二次電池の正極材料として好適に使用できることが分かる。   From the above, it can be seen that the composite powder for an electrode of the present invention can be suitably used as a positive electrode material of a lithium secondary battery having a high current density and a high energy density and having excellent rate characteristics.

比較例1(通電処理なし)
実施例1と同じ電極活物質Li1.2Fe0.4Mn0.4を用い、これとABを重量比97:3で秤量し、実施例1と同様に、ケーシング回転6970rpmで2分間メ
カノフュージョン処理を行った。
Comparative Example 1 (no energization process)
The same electrode active material Li 1.2 Fe 0.4 Mn 0.4 O 2 as in Example 1 was used, and this and AB were weighed at a weight ratio of 97: 3. Mechanofusion treatment was performed for a minute.

得られた粉末を用い、実施例1と全く同様にしてリチウム二次電池を作製し、同様の条件で充放電試験を行った。結果は図1及び図2に示す通り、メカノフュージョン処理を行わない場合(比較例3)に比べ放電容量及び放電平均電圧の増大が一部認められるものの、実施例1の場合ほどには増大効果は認められず、メカノフュージョン法のみでは充放電特性の改善効果は小さいことが分かった。   Using the obtained powder, a lithium secondary battery was produced in exactly the same manner as in Example 1, and a charge / discharge test was performed under the same conditions. As a result, as shown in FIGS. 1 and 2, although some increase in discharge capacity and average discharge voltage is recognized as compared with the case where the mechanofusion treatment is not performed (Comparative Example 3), the increase effect is as high as in the case of Example 1. It was found that the effect of improving the charge / discharge characteristics was small by the mechano-fusion method alone.

以上より、Li1.2Fe0.4Mn0.4とAB粉末からメカノフュージョン法を用いて複合粉末を作製しても、更に通電処理を加えた複合粉末ほどには両者の接合を強化することはできず、高電流密度で高エネルギー密度を示し、優れた充放電特性を有するリチウム二次電池を作製することは困難であることが分かった。 From the above, even if composite powder is prepared from Li 1.2 Fe 0.4 Mn 0.4 O 2 and AB powder using the mechano-fusion method, the composite powder to which further energization treatment is applied can be bonded to both. It has been found that it is difficult to produce a lithium secondary battery that cannot be strengthened, exhibits a high energy density at a high current density, and has excellent charge / discharge characteristics.

比較例2(メカノフュージョン処理なし)
実施例1と同じ電極活物質Li1.2Fe0.4Mn0.4を用い、これとABを重量比97:3で秤量し、メノウ乳鉢で混練した。これを内径10mmのタングステンカーバイド治具に充填し、実施例1と同様に、500MPaの加圧下、270℃で20分間、通電処理を行った。
Comparative Example 2 (without mechanofusion treatment)
Using the same electrode active material Li 1.2 Fe 0.4 Mn 0.4 O 2 as in Example 1, this and AB were weighed at a weight ratio of 97: 3 and kneaded in an agate mortar. This was filled in a tungsten carbide jig having an inner diameter of 10 mm, and in the same manner as in Example 1, energization treatment was performed at 270 ° C. for 20 minutes under a pressure of 500 MPa.

得られた粉末を用い、実施例1と全く同様にしてリチウム二次電池を作製し、同様の条件で充放電試験を行った。結果は図1及び図2に示す通り、通電処理を行わない場合(比較例3)に比べ放電容量及び放電平均電圧の増大が一部認められるものの、実施例1の場合ほどには増大効果は認められず、通電処理のみでは充放電特性の改善効果は小さいことが分かった。   Using the obtained powder, a lithium secondary battery was produced in exactly the same manner as in Example 1, and a charge / discharge test was performed under the same conditions. As shown in FIG. 1 and FIG. 2, although the increase in the discharge capacity and the discharge average voltage is partially recognized as compared with the case where the energization process is not performed (Comparative Example 3), the increase effect is as high as in the case of Example 1. It was not recognized, and it turned out that the improvement effect of a charge / discharge characteristic is small only by energization processing.

以上より、Li1.2Fe0.4Mn0.4とAB粉末から通電焼結法を用いて複合粉末を作製しても、更にメカノフュージョン法を加えた複合粉末ほどには両者の接合を強化することはできず、高電流密度で高エネルギー密度を示し、優れた充放電特性を有するリチウム二次電池を作製することは困難であることが分かった。 From the above, even if a composite powder was produced from Li 1.2 Fe 0.4 Mn 0.4 O 2 and AB powder using an electric current sintering method, the composite powder to which the mechano-fusion method was further added was more effective. It has been found that it is difficult to produce a lithium secondary battery that cannot enhance the bonding, exhibits a high energy density at a high current density, and has excellent charge / discharge characteristics.

比較例3(メカノフュージョン処理・通電処理なし)
実施例1と同じ電極活物質Li1.2Fe0.4Mn0.4を用い、これとABを重量比97:3で秤量し、メノウ乳鉢で混練した。
Comparative Example 3 (without mechanofusion treatment / energization treatment)
Using the same electrode active material Li 1.2 Fe 0.4 Mn 0.4 O 2 as in Example 1, this and AB were weighed at a weight ratio of 97: 3 and kneaded in an agate mortar.

得られた粉末を用い、実施例1と全く同様にしてリチウム二次電池を作製し、同様の条件で充放電試験を行った。結果は図1及び図2に示す通り、実施例1の場合に比べ、いずれの電流密度でも放電容量、放電平均電圧が低い値であった。   Using the obtained powder, a lithium secondary battery was produced in exactly the same manner as in Example 1, and a charge / discharge test was performed under the same conditions. As a result, as shown in FIGS. 1 and 2, compared to the case of Example 1, the discharge capacity and the discharge average voltage were low at any current density.

以上より、Li1.2Fe0.4Mn0.4とAB粉末を単に混合したのみでは、高電流密度で高エネルギー密度を示し、優れた充放電特性を有するリチウム二次電池を作製することは困難であることが分かった。 From the above, a lithium secondary battery having a high current density and high energy density and having excellent charge / discharge characteristics can be produced by simply mixing Li 1.2 Fe 0.4 Mn 0.4 O 2 and AB powder. It turned out to be difficult.

実施例2
電極活物質として平均粒子径9.4μmのLiNi0.8Co0.15Al0.05を用意した。
Example 2
LiNi 0.8 Co 0.15 Al 0.05 O 2 having an average particle size of 9.4 μm was prepared as an electrode active material.

LiNi0.8Co0.15Al0.05と市販のアセチレンブラック(AB)粉末を重量比で97:3となるよう秤量し、これらをホソカワミクロン(株)製メカノフュージョン AMS−Miniに投入し、クリアランス1mm、ケーシング回転6970rpmで10分間メカノフュージョン処理を行った。 LiNi 0.8 Co 0.15 Al 0.05 O 2 and commercially available acetylene black (AB) powder were weighed to a weight ratio of 97: 3, and these were put into Mechanofusion AMS-Mini manufactured by Hosokawa Micron Corporation. Then, a mechanofusion treatment was performed for 10 minutes at a clearance of 1 mm and a casing rotation of 6970 rpm.

これを内径10mmのWC型材に充填し、通電焼結機内にセットして約20Paまで減圧後、窒素ガスを大気圧になるまで導入した。次いで、WC型材を約500MPaで加圧しながら約400Aのパルス電流(パルス幅2.5ミリ秒のON−OFF直流電流、周期29Hz)を通電した。WC型材近傍は約50℃/分の昇温速度で加熱され、パルス電流の通電開始約5分後に250℃に到達した。この温度で約20分間保持した後、電流の通電と加圧を停止し、自然放冷させた。室温に冷却後、LiNi0.8Co0.15Al0.05−AB複合粉末(焼結体)を型材から取り出し、電極用粉末を得た。 This was filled into a WC type material having an inner diameter of 10 mm, set in an electric current sintering machine, reduced in pressure to about 20 Pa, and then introduced with nitrogen gas to atmospheric pressure. Next, a pulse current of about 400 A (ON-OFF DC current with a pulse width of 2.5 milliseconds, cycle 29 Hz) was applied while the WC mold was pressed at about 500 MPa. The vicinity of the WC mold was heated at a rate of temperature increase of about 50 ° C./min, and reached 250 ° C. about 5 minutes after the start of pulse current application. After holding at this temperature for about 20 minutes, the current application and pressurization were stopped and the mixture was allowed to cool naturally. After cooling to room temperature, LiNi 0.8 Co 0.15 Al 0.05 O 2 -AB composite powder (sintered body) was taken out of the mold material to obtain electrode powder.

複合粉末は黒色であり、X線回折パターンでは2θ=26°近傍にAB由来の幅広のハローが認められ、それ以外のピークは六方晶系の層状岩塩型ニッケルコバルト酸リチウムの単位胞(空間群R3m)で指数付けできた。   The composite powder is black, and in the X-ray diffraction pattern, a broad halo derived from AB is observed in the vicinity of 2θ = 26 °, and the other peaks are unit cells (space group of hexagonal layered rock salt type nickel cobalt oxide lithium). R3m).

≪充放電特性≫
電極用粉末をリチウム二次電池の正極材料として用い、負極にリチウム金属、集電体にアルミニウムメッシュ、電解液としてLiPFをエチレンカルボネート/ジメチルカルボネート混合液に溶解させたものを用いて、電流密度50mA/g(1/3C)〜9000mA/g(60C)、カットオフ2.0〜4.2Vにおける定電流測定で充放電試験を行った。
≪Charge / discharge characteristics≫
Using the electrode powder as a positive electrode material of a lithium secondary battery, using lithium metal as a negative electrode, aluminum mesh as a current collector, and LiPF 6 dissolved in an ethylene carbonate / dimethyl carbonate mixture as an electrolyte, A charge / discharge test was conducted by constant current measurement at a current density of 50 mA / g (1/3 C) to 9000 mA / g (60 C) and a cutoff of 2.0 to 4.2 V.

図3に、1C、10C、30C、60Cでのリチウム二次電池の放電曲線を示す。10C以下のレートでは、メカノフュージョン処理のみの場合(比較例4)、及びメカノフュージョン、通電焼結処理のいずれの処理も施さない場合(比較例5)に比べやや低い容量及び低い放電平均電圧を示したが、30C以上の高電流密度においてはこれら2つの比較例に比べ、容量の増大及び放電平均電圧の向上が認められた。これは、活物質−導電材間の接合が良好で電子伝導性が充分に確保されていることを示唆している。   FIG. 3 shows discharge curves of the lithium secondary battery at 1C, 10C, 30C, and 60C. At a rate of 10 C or less, a slightly lower capacity and a lower discharge average voltage are obtained compared to the case of only mechanofusion treatment (Comparative Example 4) and the case of not performing any of mechanofusion and current sintering treatment (Comparative Example 5). As shown, at a high current density of 30 C or higher, an increase in capacity and an improvement in discharge average voltage were recognized as compared with these two comparative examples. This suggests that the bonding between the active material and the conductive material is good and the electron conductivity is sufficiently ensured.

以上より、本発明の電極用複合粉末は、高電流密度で高エネルギー密度を示し、優れたレート特性を有するリチウム二次電池の正極材料として好適に使用できることが分かる。   From the above, it can be seen that the composite powder for an electrode of the present invention can be suitably used as a positive electrode material of a lithium secondary battery having a high current density and a high energy density and having excellent rate characteristics.

比較例4(通電処理なし)
実施例2と同じ電極活物質LiNi0.8Co0.15Al0.05を用い、これとABを重量比97:3で秤量し、実施例2と同様に、ケーシング回転6970rpmで10分間メカノフュージョン処理を行った。
Comparative example 4 (no energization treatment)
The same electrode active material LiNi 0.8 Co 0.15 Al 0.05 O 2 as in Example 2 was used, and this and AB were weighed at a weight ratio of 97: 3. Mechanofusion treatment was performed for a minute.

得られた粉末を用い、実施例2と全く同様にしてリチウム二次電池を作製し、同様の条件で充放電試験を行った。結果は図3に示す通り、メカノフュージョン処理を行わない場合(比較例5)に比べ放電容量及び放電平均電圧の増大が30C以上の高電流密度において認められるものの、実施例2の場合ほどには増大効果は認められず、メカノフュージョン法のみでは充放電特性の改善効果は小さいことが分かった。   Using the obtained powder, a lithium secondary battery was produced in exactly the same manner as in Example 2, and a charge / discharge test was performed under the same conditions. As shown in FIG. 3, although the increase in the discharge capacity and the discharge average voltage is recognized at a high current density of 30 C or more as compared with the case where the mechanofusion treatment is not performed (Comparative Example 5), the result is as high as in the case of Example 2. The increase effect was not recognized, and it was found that the mechano-fusion method alone had little effect on improving the charge / discharge characteristics.

以上より、LiNi0.8Co0.15Al0.05とAB粉末からメカノフュージョン法を用いて複合粉末を作製しても、更に通電処理を加えた複合粉末ほどには両者の接合を強化することはできず、高電流密度で高エネルギー密度を示し、優れた充放電特性を有するリチウム二次電池を作製することは困難であることが分かった。 From the above, even if a composite powder is produced from LiNi 0.8 Co 0.15 Al 0.05 O 2 and AB powder using the mechanofusion method, the composite powder to which further energization treatment is applied can be bonded to both. It has been found that it is difficult to produce a lithium secondary battery that cannot be strengthened, exhibits a high energy density at a high current density, and has excellent charge / discharge characteristics.

比較例5(メカノフュージョン処理・通電処理なし)
実施例2と同じ電極活物質LiNi0.8Co0.15Al0.05を用い、これとABを重量比97:3で秤量し、メノウ乳鉢で混練した。
Comparative Example 5 (without mechanofusion treatment / energization treatment)
Using the same electrode active material LiNi 0.8 Co 0.15 Al 0.05 O 2 as in Example 2, this and AB were weighed at a weight ratio of 97: 3 and kneaded in an agate mortar.

得られた粉末を用い、実施例2と同様にしてリチウム二次電池を作製し、同様の条件で充放電試験を行った。結果は図3に示す通り、実施例2の場合に比べ、特に30C以上の高電流密度において放電容量、放電平均電圧が低い値であった。   Using the obtained powder, a lithium secondary battery was produced in the same manner as in Example 2, and a charge / discharge test was performed under the same conditions. As a result, as shown in FIG. 3, the discharge capacity and the discharge average voltage were lower than those of Example 2 particularly at a high current density of 30 C or more.

以上より、LiNi0.8Co0.15Al0.05とAB粉末を単に混合したのみでは、高電流密度で高エネルギー密度を示し、優れた充放電特性を有するリチウム二次電池を作製することは困難であることが分かった。 From the above, a lithium secondary battery having high current density and high energy density and excellent charge / discharge characteristics can be produced by simply mixing LiNi 0.8 Co 0.15 Al 0.05 O 2 and AB powder. It turned out to be difficult.

実施例1、比較例1〜3で作製したリチウム二次電池の1/3C〜30Cにおける放電容量を、1/3Cでの放電容量を100%とした容量維持率で示した図である。It is the figure which showed the discharge capacity in 1 / 3C-30C of the lithium secondary battery produced in Example 1 and Comparative Examples 1-3 by the capacity | capacitance maintenance factor which made the discharge capacity in 1 / 3C 100%. 実施例1、比較例1〜3で作製したリチウム二次電池の1C、5C、20Cにおける放電特性を示す図である。It is a figure which shows the discharge characteristic in 1C, 5C, and 20C of the lithium secondary battery produced in Example 1 and Comparative Examples 1-3. 実施例2、比較例4〜5で作製したリチウム二次電池の1C、10C、30C、60Cにおける放電特性を示す図である。It is a figure which shows the discharge characteristic in 1C, 10C, 30C, 60C of the lithium secondary battery produced in Example 2 and Comparative Examples 4-5. メカノフュージョン装置の概略図である。It is the schematic of a mechanofusion apparatus. 放電プラズマ焼結機の概略図である。It is the schematic of a discharge plasma sintering machine.

符号の説明Explanation of symbols

1.ケーシング
2.インナーピース(摩擦部材)
3.スクレーパー(掻き取り部材)
4.原料混合物
1. Casing 2. Inner piece (friction member)
3. Scraper
4). Raw material mixture

Claims (12)

電極活物質どうしが導電材を介して接合している構造を有する電極用複合粉末であって、前記電極用複合粉末は、
(1)電極活物質と導電材とを含有する原料混合物をメカノフュージョン処理することによって前記電極活物質と前記導電材とを予め結着させ、次いで、
(2)前記結着後の原料混合物を、導電性を有する型に充填し、60MPa以上の加圧下において直流パルス電流を通電して焼結させることにより得られる、電極用複合粉末。
A composite powder for an electrode having a structure in which electrode active materials are joined via a conductive material, the composite powder for an electrode,
(1) The electrode active material and the conductive material are previously bound by subjecting the raw material mixture containing the electrode active material and the conductive material to mechanofusion treatment,
(2) A composite powder for an electrode obtained by filling the raw material mixture after the binding into a conductive mold and sintering it by applying a direct current pulse current under a pressure of 60 MPa or more.
前記メカノフュージョン処理は、前記原料混合物に少なくとも圧縮力と剪断力とを加え、前記電極活物質と前記導電材とを結着させる、請求項1に記載の電極用複合粉末。   The composite powder for an electrode according to claim 1, wherein in the mechanofusion treatment, at least a compressive force and a shearing force are applied to the raw material mixture to bind the electrode active material and the conductive material. 前記メカノフュージョン処理は、回転するケーシングと前記ケーシング内に固定されたインナーピースとを備えるメカノフュージョン装置を用いる処理であって、
(1)前記ケーシングと前記インナーピースとの隙間距離は0.1〜10mmであり、
(2)前記ケーシング内に前記原料混合物を供給すると、前記原料混合物は遠心力により前記ケーシングの内壁面に押し付けられるとともに、前記インナーピースと前記内壁面の隙間で少なくとも圧縮力と剪断力とを加えられることにより、前記電極活物質と前記導電材とが結着し、
(3)前記処理は、前記ケーシング内に前記原料混合物を供給した後、前記ケーシングを1000〜8000rpmの速度で1〜30分間回転させることにより行う、請求項1に記載の電極用複合粉末。
The mechanofusion process is a process using a mechanofusion apparatus including a rotating casing and an inner piece fixed in the casing,
(1) The gap distance between the casing and the inner piece is 0.1 to 10 mm,
(2) When the raw material mixture is supplied into the casing, the raw material mixture is pressed against the inner wall surface of the casing by centrifugal force, and at least a compressive force and a shearing force are applied between the inner piece and the inner wall surface. The electrode active material and the conductive material are bound together,
(3) The composite powder for an electrode according to claim 1, wherein the treatment is performed by rotating the casing at a speed of 1000 to 8000 rpm for 1 to 30 minutes after supplying the raw material mixture into the casing.
前記導電性を有する型は、タングステンカーバイドを含有する、請求項1〜3のいずれかに記載の電極用複合粉末。   The composite powder for an electrode according to any one of claims 1 to 3, wherein the conductive mold contains tungsten carbide. 150MPa以上の加圧下において直流パルス電流を通電する、請求項1〜4のいずれかに記載の電極用複合粉末。   The composite powder for an electrode according to any one of claims 1 to 4, wherein a direct-current pulse current is passed under a pressure of 150 MPa or more. 前記電極活物質は、1)オリビン型構造の含リチウム化合物、2)層状岩塩型又は立方晶岩塩型の結晶構造を有する岩塩類縁構造の含リチウム化合物、及び3)スピネル型構造の含リチウム化合物からなる群から選択される少なくとも1種の正極活物質である、請求項1〜5のいずれかに記載の電極用複合粉末。   The electrode active material is composed of 1) a lithium-containing compound having an olivine structure, 2) a lithium-containing compound having a rock salt-like structure having a layered rock salt type or cubic rock salt type crystal structure, and 3) a lithium containing compound having a spinel structure. The composite powder for an electrode according to any one of claims 1 to 5, which is at least one positive electrode active material selected from the group consisting of: 前記電極活物質は、リン酸鉄リチウム;コバルト、マンガン及びニッケルからなる群から選択される少なくとも1種を固溶したリン酸鉄リチウム;リン酸コバルトリチウム;マンガン及びニッケルの少なくとも1種を固溶したリン酸コバルトリチウム;リン酸マンガンリチウム;ニッケルを固溶したリン酸マンガンリチウム;リン酸ニッケルリチウム;ニッケル酸リチウム;コバルト及びアルミニウムの少なくとも1種を固溶したニッケル酸リチウム;コバルト酸リチウム;鉄酸リチウム;チタン、マンガンの少なくとも1種を固溶した鉄酸リチウム;チタン酸リチウム;マンガン酸リチウム;及びクロムを固溶したマンガン酸リチウムからなる群から選択される少なくとも1種の正極活物質である、請求項1〜5のいずれかに記載の電極用複合粉末。   The electrode active material is lithium iron phosphate; lithium iron phosphate in which at least one selected from the group consisting of cobalt, manganese, and nickel is dissolved; lithium cobalt phosphate; at least one of manganese and nickel is in solid solution Cobalt lithium phosphate; lithium manganese phosphate; lithium manganese phosphate in solid solution; nickel lithium phosphate; lithium nickelate; lithium nickelate in solid solution of at least one of cobalt and aluminum; lithium cobaltate; iron At least one positive electrode active material selected from the group consisting of lithium acid; lithium ironate in which at least one of titanium and manganese is dissolved; lithium titanate; lithium manganate; and lithium manganate in which chromium is dissolved It is for the electrode according to any one of claims 1 to 5. If powder. 前記電極活物質は、炭素、珪素、ゲルマニウム、スズ、鉛、アンチモン、アルミニウム、インジウム、リチウム、酸化スズ、チタン酸リチウム、窒化リチウム、インジウムを固溶した酸化錫、インジウム−錫合金、リチウム−アルミニウム合金及びリチウム−インジウム合金からなる群から選択される少なくとも1種の負極活物質である、請求項1〜5のいずれかに記載の電極用複合粉末。   The electrode active material includes carbon, silicon, germanium, tin, lead, antimony, aluminum, indium, lithium, tin oxide, lithium titanate, lithium nitride, indium tin oxide, indium-tin alloy, lithium-aluminum. The composite powder for an electrode according to any one of claims 1 to 5, which is at least one negative electrode active material selected from the group consisting of an alloy and a lithium-indium alloy. 請求項1〜8のいずれかに記載の電極用複合粉末を含有する電極を備えた、一次電池、二次電池、燃料電池又はキャパシタ。   A primary battery, a secondary battery, a fuel cell or a capacitor, comprising an electrode containing the composite powder for an electrode according to claim 1. 電極活物質どうしが導電材を介して接合している構造を有する電極用複合粉末の製造方法であって、
(1)電極活物質と導電材とを含有する原料混合物をメカノフュージョン処理することによって前記電極活物質と前記導電材とを予め結着させ、次いで、
(2)前記結着後の原料混合物を、導電性を有する型に充填し、60MPa以上の加圧下において直流パルス電流を通電して焼結させる工程を有する、製造方法。
A method for producing a composite powder for an electrode having a structure in which electrode active materials are joined together via a conductive material,
(1) The electrode active material and the conductive material are previously bound by subjecting the raw material mixture containing the electrode active material and the conductive material to mechanofusion treatment,
(2) A manufacturing method comprising filling the raw material mixture after the binding into a conductive mold and applying a direct current pulse current under a pressure of 60 MPa or more to sinter.
前記メカノフュージョン処理は、前記原料混合物に少なくとも圧縮力と剪断力とを加え、前記電極活物質と前記導電材とを結着させる、請求項10に記載の製造方法。   The manufacturing method according to claim 10, wherein the mechanofusion treatment applies at least a compressive force and a shearing force to the raw material mixture to bind the electrode active material and the conductive material. 前記メカノフュージョン処理は、回転するケーシングと前記ケーシング内に固定されたインナーピースとを備えるメカノフュージョン装置を用いる処理であって、
(1)前記ケーシングと前記インナーピースとの隙間距離は0.1〜10mmであり、
(2)前記ケーシング内に前記原料混合物を供給すると、前記原料混合物は遠心力により前記ケーシングの内壁面に押し付けられるとともに、前記インナーピースと前記内壁面の隙間で少なくとも圧縮力と剪断力とを加えられることにより、前記電極活物質と前記導電材とが結着し、
(3)前記処理は、前記ケーシング内に前記原料混合物を供給した後、前記ケーシングを1000〜8000rpmの速度で1〜30分間回転させることにより行う、請求項10に記載の製造方法。
The mechanofusion process is a process using a mechanofusion apparatus including a rotating casing and an inner piece fixed in the casing,
(1) The gap distance between the casing and the inner piece is 0.1 to 10 mm,
(2) When the raw material mixture is supplied into the casing, the raw material mixture is pressed against the inner wall surface of the casing by centrifugal force, and at least a compressive force and a shearing force are applied between the inner piece and the inner wall surface. The electrode active material and the conductive material are bound together,
(3) The manufacturing method according to claim 10, wherein the treatment is performed by rotating the casing at a speed of 1000 to 8000 rpm for 1 to 30 minutes after supplying the raw material mixture into the casing.
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