JP2020184473A - Method for producing negative electrode active material composite for nonaqueous secondary battery - Google Patents

Method for producing negative electrode active material composite for nonaqueous secondary battery Download PDF

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JP2020184473A
JP2020184473A JP2019088751A JP2019088751A JP2020184473A JP 2020184473 A JP2020184473 A JP 2020184473A JP 2019088751 A JP2019088751 A JP 2019088751A JP 2019088751 A JP2019088751 A JP 2019088751A JP 2020184473 A JP2020184473 A JP 2020184473A
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俊充 田中
Toshimitsu Tanaka
俊充 田中
岩崎 秀治
Hideji Iwasaki
秀治 岩崎
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Kuraray Co Ltd
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Abstract

To provide a method for producing a negative electrode active material for nonaqueous secondary batteries, the negative electrode active material being excellent in charge/discharge characteristics and being applicable to nonaqueous secondary batteries such as, for example, lithium ion secondary batteries and sodium ion secondary batteries.SOLUTION: A method for producing a negative electrode active material for nonaqueous secondary batteries includes the steps of: (1) mixing an aqueous solution containing a compound having a conjugated polyvalent carboxylic acid salt (COOM) structure showing water solubility, favorably a metal constituting a carboxylic acid salt of the compound being an alkaline metal element, with a carbon material to obtain a mixture; and (2) distilling off water in the mixture.SELECTED DRAWING: None

Description

本発明は、非水系二次電池用負極活物質複合体を製造する方法に関する。 The present invention relates to a method for producing a negative electrode active material composite for a non-aqueous secondary battery.

従来、リチウムイオン二次電池をはじめとした非水系二次電池用負極活物質としては、黒鉛やハードカーボンなどの炭素材料が知られている。また、新しい非水系二次電池用負極活物質として、有機化合物であるテレフタル酸ジリチウムが、検討されている。(非特許文献1)。このような有機化合物を用いた非水系二次電池用負極活物質として、特許文献1には、芳香族環構造とカルボン酸アニオン部とを有する芳香族化合物を含む有機骨格層と、前記カルボン酸アニオン部に含まれる酸素にアルカリ金属元素が配位して骨格を形成するアルカリ金属元素層を有する非水系二次電池用負極活物質を用いた電極について、電極に加熱処理を施すことでより高い充放電容量を発現したことが記載されている。また、特許文献2には、芳香族環構造および前記芳香族環構造の末端に結合した2以上のCOOX基(XはLiまたはNaである。)を有する化合物である有機活物質材料と、炭素材料とを遊星ボールミルを用いて複合化した化合物を、ナトリウムイオン二次電池用負極活物質として用いると、処理前に比べて高い充放電容量を発現したことが記載されている。 Conventionally, carbon materials such as graphite and hard carbon are known as negative electrode active materials for non-aqueous secondary batteries such as lithium ion secondary batteries. Further, as a new negative electrode active material for a non-aqueous secondary battery, dilithium terephthalate, which is an organic compound, is being studied. (Non-Patent Document 1). As a negative electrode active material for a non-aqueous secondary battery using such an organic compound, Patent Document 1 describes an organic skeleton layer containing an aromatic compound having an aromatic ring structure and a carboxylic acid anion portion, and the carboxylic acid. For electrodes using a negative electrode active material for non-aqueous secondary batteries, which has an alkali metal element layer in which an alkali metal element coordinates with oxygen contained in the anion portion to form a skeleton, the electrode is made higher by heat treatment. It is described that the charge / discharge capacity was expressed. Further, Patent Document 2 describes an organic active material which is a compound having an aromatic ring structure and two or more COOX groups (X is Li or Na) bonded to the end of the aromatic ring structure, and carbon. It is described that when a compound obtained by combining a material with a planetary ball mill as a negative electrode active material for a sodium ion secondary battery, a higher charge / discharge capacity was exhibited as compared with that before the treatment.

特開2014−216211号公報Japanese Unexamined Patent Publication No. 2014-162211 特開2015−037016号公報Japanese Unexamined Patent Publication No. 2015-037016

ネイチャー マテリアルズ (Nature materials),2009年,8巻,p.120−125Nature Materials, 2009, Volume 8, p. 120-125

しかしながら、特許文献1に開示されている方法では、電極を焼成処理すると、加熱により電極が収縮し、電極の形状が不規則化し、安全性が担保できない、電極厚みも変化し抵抗増加により充放電容量が得られないという問題がある。また、特許文献2に開示されている方法では、負極活物質と炭素材料との導電パスの形成が不十分なため、十分な充放電特性が得られないという問題がある。そこで、本発明の目的は、十分な充放電容量を有する、例えばリチウムイオン二次電池などの非水系二次電池に適用できる非水系二次電池用負極活物質の製造方法を提供することにある。 However, in the method disclosed in Patent Document 1, when the electrode is fired, the electrode contracts due to heating, the shape of the electrode becomes irregular, safety cannot be guaranteed, the electrode thickness changes, and charging / discharging occurs due to an increase in resistance. There is a problem that the capacity cannot be obtained. Further, the method disclosed in Patent Document 2 has a problem that sufficient charge / discharge characteristics cannot be obtained because the formation of a conductive path between the negative electrode active material and the carbon material is insufficient. Therefore, an object of the present invention is to provide a method for producing a negative electrode active material for a non-aqueous secondary battery, which has a sufficient charge / discharge capacity and can be applied to a non-aqueous secondary battery such as a lithium ion secondary battery. ..

本発明によれば、上記の目的は、
[1](1)水溶性を示す共役多価カルボン酸塩構造を有する化合物を含む水溶液を炭素材料と混合して混合物を得る工程、および
(2)前記混合物中の水を留去する工程を含む、非水系二次電池用負極活物質の製造方法、
[2]前記化合物のカルボン酸塩を構成する金属がアルカリ金属元素である、上記[1]の製造方法、
[3]前記化合物の炭素数が4〜14である、上記 [1]または[2]の製造方法、
[4]前記化合物の構造は、次式(I)〜(III)で表される化合物から選択される少なくとも一つである、上記[1]〜[3]のいずれかの製造方法、
を提供することにより達成される。
According to the present invention, the above object is
[1] (1) A step of mixing an aqueous solution containing a compound having a conjugated polyvalent carboxylate structure showing water solubility with a carbon material to obtain a mixture, and (2) a step of distilling off water in the mixture. Method of manufacturing negative electrode active material for non-aqueous secondary batteries, including
[2] The production method according to the above [1], wherein the metal constituting the carboxylate of the compound is an alkali metal element.
[3] The production method according to [1] or [2] above, wherein the compound has 4 to 14 carbon atoms.
[4] The production method according to any one of the above [1] to [3], wherein the structure of the compound is at least one selected from the compounds represented by the following formulas (I) to (III).
Is achieved by providing.

Figure 2020184473
(I)
Figure 2020184473
(I)

(式中、mは1〜2の整数を表し、Mは金属元素を表し、RおよびRはそれぞれ独立して置換基として水酸基、ハロゲンおよびカルボキシル基からなる群から選ばれる少なくとも一つを有してもよい炭素数1から2のアルキル基、水素、カルボキシル基または塩化されたカルボキシル基のいずれかを表す) (In the formula, m represents an integer of 1 to 2, M represents a metal element, and R 1 and R 2 each independently have at least one selected from the group consisting of a hydroxyl group, a halogen, and a carboxyl group as substituents. Represents either an alkyl group having 1 to 2 carbon atoms, hydrogen, a carboxyl group, or a chloride carboxyl group which may have one)

Figure 2020184473
(II)
Figure 2020184473
(II)

(式中、nは1~2の整数を表し、Mは金属元素を表し、R、R、RおよびRはそれぞれ独立して置換基として水酸基、ハロゲンおよびカルボキシル基からなる群から選ばれる少なくとも一つを有してもよい炭素数1から2のアルキル基、水素、カルボキシル基または塩化されたカルボキシル基のいずれかを表す) (In the formula, n represents an integer of 1 to 2, M represents a metal element, and R 3 , R 4 , R 5 and R 6 are independently substituted groups consisting of a hydroxyl group, a halogen and a carboxyl group. Represents either an alkyl group having 1-2 carbon atoms, hydrogen, a carboxyl group, or a chloride carboxyl group, which may have at least one selected)

Figure 2020184473
(III)
Figure 2020184473
(III)

(式中、Mは金属元素を表し、R、R、R、R10、R11およびR12はそれぞれ独立して置換基として水酸基、ハロゲンおよびカルボキシル基からなる群から選ばれる少なくとも一つを有してもよい炭素数1から2のアルキル基、水素、カルボキシル基または塩化されたカルボキシル基のいずれかを表す) (In the formula, M represents a metal element, and R 7 , R 8 , R 9 , R 10 , R 11 and R 12 are at least one independently selected from the group consisting of hydroxyl groups, halogens and carboxyl groups as substituents. Represents either an alkyl group having 1 to 2 carbon atoms, hydrogen, a carboxyl group, or a chloride carboxyl group which may have one)

本発明により、十分な充放電容量を示す、例えばリチウムイオン、ナトリウムイオン二次電池などの非水系二次電池に適用できる非水系二次電池用負極活物質の製造方法を提供することができる。 INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a method for producing a negative electrode active material for a non-aqueous secondary battery, which exhibits a sufficient charge / discharge capacity and can be applied to a non-aqueous secondary battery such as a lithium ion or sodium ion secondary battery.

本発明の非水系二次電池用負極活物質の製造方法は、水溶性を示す共役多価カルボン酸塩構造(前記カルボン酸塩部分は通常、カルボン酸金属塩であり、COOMと表記できる。Mは金属元素を表す。)を有する化合物を含む水溶液を炭素材料と混合して混合物を得る工程および(2)前記混合物中の水を留去する工程を含むことを特徴とする。 The method for producing a negative electrode active material for a non-aqueous secondary battery of the present invention has a conjugated polyvalent carboxylic acid salt structure exhibiting water solubility (the carboxylic acid salt portion is usually a carboxylic acid metal salt and can be referred to as COOM. Is characterized by including a step of mixing an aqueous solution containing a compound having a metal element) with a carbon material to obtain a mixture, and (2) a step of distilling off water in the mixture.

工程(1)で用いられる水溶液は例えば以下のようにして調製することができる。共役多価カルボン酸の分散液に共役多価カルボン酸塩を構成する金属(M)を有する化合物を含む水溶液を混合する。前記混合の際30℃〜90℃程度に加熱しても良い。前記混合により、共役多価カルボン酸塩構造を有する化合物が形成され、前記混合液の水をエバポレーター等で留去して共役多価カルボン酸塩構造を有する化合物を得る。この化合物を水に溶解することで前記水溶液を得ることができる。前記分散液中の分散媒が水である場合には、混合液をそのまま水溶液として用いてもよい。 The aqueous solution used in the step (1) can be prepared, for example, as follows. An aqueous solution containing a compound having a metal (M) constituting the conjugated polyvalent carboxylic acid salt is mixed with a dispersion of the conjugated polyvalent carboxylic acid. At the time of the mixing, it may be heated to about 30 ° C. to 90 ° C. By the mixing, a compound having a conjugated polyvalent carboxylic acid salt structure is formed, and water in the mixed solution is distilled off with an evaporator or the like to obtain a compound having a conjugated polyvalent carboxylic acid salt structure. The aqueous solution can be obtained by dissolving this compound in water. When the dispersion medium in the dispersion is water, the mixed solution may be used as it is as an aqueous solution.

水溶性を示す共役多価カルボン酸塩構造を有する化合物の炭素数は、水溶性を示すものであれば特に限定されるものではなく、4〜30が好ましく、4〜20がより好ましく、入手性、原料となる化合物の安定性、電池内での構造安定性が優れる観点から、4〜14がさらに好ましい。ここで、水溶性を示すとは20℃で100gの水に1g以上溶解することを意味する。水溶性を示す共役多価カルボン酸塩構造を有する化合物中のカルボン酸塩部分はCOOMとしても表現できる。Mは金属元素を示し、好適にはアルカリ金属元素であり、例えば、Li、Na、Kが挙げられる。電池駆動電圧の観点から、中でも、Li,Naが好ましい。前記化合物中、水溶性を示す共役多価カルボン酸塩構造を有する化合物のCOOM基の数は2以上であり、前記化合物の結晶構造を構成する安定性の観点から、2〜4であることが好ましく、2であることがより好ましい。COOM基の数が2である場合、その結合位置は芳香族環構造の結合箇所間の距離が最大となる位置であることが好ましい。共役多価カルボン酸塩構造を有する化合物は、水酸基、フッ素、塩素等のハロゲン、非共役のカルボン酸などの官能基を有していてもよい。共役カルボン酸塩構造を有する化合物が芳香族環を有する場合、水溶性の観点から芳香環の数は1〜2が好ましく、1であることがより好ましい。芳香族環の環構造は、その環構造を構成する元素が炭素のみである芳香族炭化水素であっても、ヘテロ原子を有する芳香族複素環であってもよく、上記芳香族環構造中の芳香族環は、五員環、六員環、七員環、八員環などの構造が挙げられる。中でも、充放電特性をより優れたものとする観点から、五員環、六員環であることが好ましい。前記水溶性を示す共役多価カルボン酸塩構造を有する化合物としては、具体的には下記式(I)〜(III)の構造が挙げられる。 The carbon number of the compound having a conjugated polyvalent carboxylic acid salt structure exhibiting water solubility is not particularly limited as long as it exhibits water solubility, and is preferably 4 to 30, more preferably 4 to 20, and availability. From the viewpoint of excellent stability of the compound as a raw material and structural stability in the battery, 4 to 14 are more preferable. Here, showing water solubility means that 1 g or more is dissolved in 100 g of water at 20 ° C. The carboxylate moiety in the compound having a conjugated polyvalent carboxylate structure showing water solubility can also be expressed as COOM. M represents a metal element, preferably an alkali metal element, and examples thereof include Li, Na, and K. From the viewpoint of battery drive voltage, Li and Na are particularly preferable. Among the compounds, the number of COOM groups of the compound having a conjugated polyvalent carboxylate structure showing water solubility is 2 or more, and from the viewpoint of stability constituting the crystal structure of the compound, it may be 2-4. It is preferably 2, and more preferably 2. When the number of COOM groups is 2, the bonding position is preferably the position where the distance between the bonding points of the aromatic ring structure is maximized. The compound having a conjugated polyvalent carboxylic acid salt structure may have a functional group such as a hydroxyl group, a halogen such as fluorine or chlorine, or a non-conjugated carboxylic acid. When the compound having a conjugated carboxylate structure has an aromatic ring, the number of aromatic rings is preferably 1 to 2 and more preferably 1 from the viewpoint of water solubility. The ring structure of the aromatic ring may be an aromatic hydrocarbon in which the element constituting the ring structure is only carbon, or an aromatic heterocycle having a hetero atom, and may be an aromatic heterocycle in the above aromatic ring structure. Examples of the aromatic ring include structures such as a five-membered ring, a six-membered ring, a seven-membered ring, and an eight-membered ring. Above all, a five-membered ring or a six-membered ring is preferable from the viewpoint of making the charge / discharge characteristics more excellent. Specific examples of the compound having a conjugated polyvalent carboxylic acid salt structure exhibiting water solubility include the structures of the following formulas (I) to (III).

Figure 2020184473
(I)
Figure 2020184473
(I)

(式中、mは1~2の整数を表し、RおよびRはそれぞれ独立して置換基として水酸基、ハロゲンおよびカルボキシル基からなる群から選ばれる少なくとも一つを有してもよい炭素数1から2のアルキル基、水素、カルボキシル基または塩化されたカルボキシル基のいずれかを表す) (In the formula, m represents an integer of 1 to 2, and R 1 and R 2 may each independently have at least one selected from the group consisting of a hydroxyl group, a halogen and a carboxyl group as a substituent. Represents either 1 to 2 alkyl groups, hydrogen, carboxyl groups or chloride carboxyl groups)

Figure 2020184473
(II)
Figure 2020184473
(II)

(式中、nは1~2の整数を表し、R、R、RおよびRはそれぞれ独立して置換基として水酸基、ハロゲンおよびカルボキシル基からなる群から選ばれる少なくとも一つを有してもよい炭素数1から2のアルキル基、水素、カルボキシル基または塩化されたカルボキシル基のいずれかを表す) (In the formula, n represents an integer of 1 to 2, and R 3 , R 4 , R 5 and R 6 each independently have at least one selected from the group consisting of hydroxyl groups, halogens and carboxyl groups as substituents. It represents either an alkyl group having 1 to 2 carbon atoms, hydrogen, a carboxyl group, or a chloride carboxyl group).

Figure 2020184473
(III)
Figure 2020184473
(III)

(式中、R、R、R、R10、R11およびR12はそれぞれ独立して置換基として水酸基、ハロゲンおよびカルボキシル基からなる群から選ばれる少なくとも一つを有してもよい炭素数1から2のアルキル基、水素、カルボキシル基または塩化されたカルボキシル基のいずれかを表す)なお、前記塩化されたカルボキシル基は通常、カルボン酸金属塩基であり、COOMで表すことができる。
具体的な化合物としてはマレイン酸ジリチウム、フマル酸ジリチウム、テレフタル酸ジリチウム、2,6−ナフタレンジカルボン酸ジリチウム、マレイン酸ジナトリウム、フマル酸ジナトリウム、テレフタル酸ジナトリウム、2,6−ナフタレンジカルボン酸ジナトリウムが挙げられる。中でもフマル酸ジリチウム、テレフタル酸ジリチウムが、得られる非水系二次電池用負極活物質の重量あたりの理論容量を向上できる点で好ましい。
(In the formula, R 7 , R 8 , R 9 , R 10 , R 11 and R 12 may each independently have at least one selected from the group consisting of hydroxyl groups, halogens and carboxyl groups as substituents. (Represents any of an alkyl group having 1 to 2 carbon atoms, hydrogen, a carboxyl group, and a chloride carboxyl group) The chlorided carboxyl group is usually a metal carboxylate base and can be represented by COOM.
Specific compounds include dilithium maleate, dilithium fumarate, dilithium terephthalate, dilithium 2,6-naphthalenedicarboxylic acid, disodium maleate, disodium fumarate, disodium terephthalate, and di-naphthalenedicarboxylic acid Examples include sodium. Of these, dilithium fumarate and dilithium terephthalate are preferable because they can improve the theoretical capacity per weight of the obtained negative electrode active material for a non-aqueous secondary battery.

前記共役多価カルボン酸塩を構成する金属(M)を有する化合物としては、アルカリ金属化合物が好ましい。アルカリ金属化合物としては、アルカリ金属水酸化物、アルカリ金属酸化物等が挙げられる。中でも、水酸化物が水との反応性、安全性の観点から好ましい。アルカリ金属としては、Li、Na、K等が挙げられ、中でも、Li、Naが得られる負極活物質の重量あたりの理論容量を向上できる点で好ましい。 As the compound having a metal (M) constituting the conjugated polyvalent carboxylate, an alkali metal compound is preferable. Examples of the alkali metal compound include alkali metal hydroxides and alkali metal oxides. Of these, hydroxides are preferable from the viewpoint of reactivity with water and safety. Examples of the alkali metal include Li, Na, K and the like, and among them, Li and Na are preferable in that the theoretical capacity per weight of the negative electrode active material obtained can be improved.

塩化して水溶性を示す共役多価カルボン酸を有する化合物としては、例えば、マレイン酸、フマル酸、シトラコン酸、メサコン酸、ムコン酸、アコンチン酸、テレフタル酸、2−メチルーテレフタル酸,1,2,4−ベンゼントリカルボン酸、1,2,4,5−ベンゼンテトラカルボン酸、4,4‘−ビフェニルジカルボン酸,2,6−ナフタレンジカルボン酸が挙げられる。中でも、マレイン酸、フマル酸、テレフタル酸,2,6−ナフタレンジカルボン酸が操作性、入手容易性、重量当たりの電池容量の観点から好ましい。 Examples of the compound having a conjugated polyvalent carboxylic acid that is chloride and water-soluble include maleic acid, fumaric acid, citraconic acid, mesaconic acid, muconic acid, acontic acid, terephthalic acid, 2-methyl-terephthalic acid, 1, Examples thereof include 2,4-benzenetricarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid, 4,4'-biphenyldicarboxylic acid and 2,6-naphthalenedicarboxylic acid. Of these, maleic acid, fumaric acid, terephthalic acid, and 2,6-naphthalenedicarboxylic acid are preferable from the viewpoints of operability, availability, and battery capacity per weight.

水溶性を示す共役多価カルボン酸塩構造を有する化合物を含む水溶液中の化合物濃度は、化合物によって好ましい濃度は異なるが、1質量%以上が好ましく、5質量%以上がより好ましい。また、水溶液への前記化合物の溶解性や炭素材料と混合する際の粘度を適切なものとする観点から、20質量%以下が好ましく、10質量%以下がより好ましい。濃度が低すぎると水溶性を示す共役多価カルボン酸塩構造を有する化合物が炭素材料上に析出する際に、先に析出した部分に順次析出し大きな結晶体となり、分散性を担保できないことや、工程(2)における水の留去に時間がかかり、複合する際の効率が悪くなることがある。 The concentration of the compound in the aqueous solution containing the compound having a conjugated polyvalent carboxylic acid salt structure showing water solubility varies depending on the compound, but is preferably 1% by mass or more, more preferably 5% by mass or more. Further, from the viewpoint of making the solubility of the compound in an aqueous solution appropriate and the viscosity when mixed with a carbon material, 20% by mass or less is preferable, and 10% by mass or less is more preferable. When a compound having a conjugated polyvalent carboxylic acid salt structure that shows water solubility when the concentration is too low is precipitated on a carbon material, it is sequentially precipitated in the previously precipitated portion to form a large crystal, and dispersibility cannot be guaranteed. , It takes time to distill off water in the step (2), and the efficiency of compounding may be deteriorated.

本発明において、水溶性を示す共役多価カルボン酸塩構造を有する化合物と担体となる炭素材の混合比としては、結晶性の違いから化合物によって好ましい混合比は異なるが、一般に、炭素材に対して水溶性を示す共役多価カルボン酸塩構造を有する化合物を複合化するという観点から、通常炭素材に対して水溶性を示す共役多価カルボン酸塩構造を有する化合物が、100:1〜1:1の範囲、より好ましくは、50:1〜1.2:1の範囲、さらに好ましくは、10:1から1.5:1の範囲である。炭素材比率が多くなると電池活物質実質的な濃度が下がり、電池容量が小さくなり、炭素比率が小さくなると、導電性を持たない水溶性を示す共役多価カルボン酸塩構造を有する化合物が結晶として析出する割合が多くなり、結果的に電池容量が低下するため好ましくない。 In the present invention, the preferable mixing ratio of the compound having a conjugated polyvalent carboxylic acid salt structure showing water solubility and the carbon material as a carrier differs depending on the compound due to the difference in crystallinity, but generally, it is based on the carbon material. From the viewpoint of compounding a compound having a conjugated polyvalent carboxylic acid salt structure exhibiting water solubility, a compound having a conjugated polyvalent carboxylic acid salt structure exhibiting water solubility in a carbon material is usually 100: 1-1. The range is 1, more preferably 50: 1 to 1.2: 1, and even more preferably 10: 1 to 1.5: 1. When the carbon material ratio increases, the substantial concentration of the battery active material decreases, the battery capacity decreases, and when the carbon ratio decreases, a compound having a conjugated polyvalent carboxylic acid salt structure showing water solubility without conductivity becomes crystals. It is not preferable because the rate of precipitation increases and the battery capacity decreases as a result.

工程(1)では、水溶性を示す共役多価カルボン酸塩構造を有する化合物を含む水溶液と、炭素材料とを混合する。混合する方法としては、水溶性を示す共役多価カルボン酸塩構造を有する化合物を含む水溶液に炭素材料を添加して混合してもよいし、炭素材料に水溶液を添加して混合してもよい。添加の方法も特に制限されず、一方を逐次的に添加しながら混合しても、一括で添加して混合しても構わない。混合の方法としても特に制限されることはなく、一般的な攪拌、遊星攪拌など混合によって剪断力のかからない方法で混合することもできるし、ニーダーなどの混錬器やフィルミックス等の薄膜旋回法などの剪断力で分散、混合する方法でも構わない。前記混合液中の固形分濃度は5質量%以上であることが好ましく、10質量%以上であることがより好ましく、15質量%以上であることがさらに好ましく、20質量%以上であることが特に好ましい。また、80質量%以下であることが好ましく、60質量%以下であることがより好ましく、50質量%以下であることがさらに好ましく、30質量%以下であることが特に好ましい。固形分濃度が高すぎると、複合時に炭素材料に水溶性を示す共役多価カルボン酸塩構造を有する化合物が偏在し、不均一な複合体と恐れがあり、低すぎる濃度では、水の蒸発に要するエネルギー量が多く経済的でないだけでなく、剪断力を利用して分散させる場合には、剪断力がかかりにくく結果的に不均一な複合体となり、充放電容量が低下する場合がある。前記範囲とすることで、より均一に複合化することができる。 In step (1), an aqueous solution containing a compound having a conjugated polyvalent carboxylate structure exhibiting water solubility and a carbon material are mixed. As a method of mixing, a carbon material may be added to an aqueous solution containing a compound having a conjugated polyvalent carboxylate structure showing water solubility and mixed, or an aqueous solution may be added to the carbon material and mixed. .. The method of addition is not particularly limited, and one of them may be added sequentially and mixed, or one of them may be added and mixed all at once. The mixing method is not particularly limited, and it can be mixed by a method that does not apply shear force by mixing such as general stirring and planetary stirring, or a thin film swirling method such as a kneader or a kneader or a fill mix. A method of dispersing and mixing with a shearing force such as the above may be used. The solid content concentration in the mixed solution is preferably 5% by mass or more, more preferably 10% by mass or more, further preferably 15% by mass or more, and particularly preferably 20% by mass or more. preferable. Further, it is preferably 80% by mass or less, more preferably 60% by mass or less, further preferably 50% by mass or less, and particularly preferably 30% by mass or less. If the solid content concentration is too high, compounds having a conjugated polyvalent carboxylic acid salt structure that shows water solubility in the carbon material at the time of compounding are unevenly distributed, which may result in a heterogeneous complex. Not only is it uneconomical because it requires a large amount of energy, but when it is dispersed using shearing force, it is difficult for shearing force to be applied, resulting in a non-uniform composite, and the charge / discharge capacity may decrease. By setting the above range, it is possible to combine more uniformly.

前記炭素材料としては電子伝導性材料であれば特に限定されず、例えば、天然黒鉛( 鱗状黒鉛、鱗片状黒鉛) や人造黒鉛などの黒鉛、アセチレンブラック、カーボンブラック、ケッチェンブラック、カーボンウィスカ、ニードルコークス、炭素繊維の中から1種類を使用しても、複数を混合して使用しても構わない。中でも、電子伝導性及び集電極に塗工して電極化する際の塗工性の観点より、カーボンブラックまたはアセチレンブラックが好ましい。 The carbon material is not particularly limited as long as it is an electron conductive material, for example, graphite such as natural graphite (scaly graphite, scaly graphite) or artificial graphite, acetylene black, carbon black, ketjen black, carbon whisker, needle. One type of coke or carbon fiber may be used, or a plurality of types may be mixed and used. Of these, carbon black or acetylene black is preferable from the viewpoint of electron conductivity and coatability when the collector electrode is coated to form an electrode.

次に工程(2)について説明する。この工程では前記混合物中の水を留去する。水を留去する方法としては、特に限定されるものではなく、混合物を加熱して水を蒸発させる方法、混合物を減圧下に置いて水を蒸発させる方法などが挙げられる。さらに、混合物を加熱し水を蒸発させる方法としては、熱風に曝して加熱する方法でも、ヒーター等により直接的に加熱する方法でも構わない。水を留去させる温度としては、気流による伝熱、ヒーターによる伝熱、さらに常圧下、減圧下によって、さらに使用した水溶性を示す共役多価カルボン酸塩構造を有する化合物の結晶水の持ち様によっても異なるが、通常40℃から300℃の範囲、より好ましくは、60℃から250℃の範囲である。低すぎる温度では、水の留去に時間を要し、経済性が損なわれるため好ましくなく、高すぎる温度では水溶性を示す共役多価カルボン酸塩構造を有する化合物の熱分解により目的物を遺失してしまう恐れがある。本発明では、一旦水を留去した複合物をさらに熱処理することによって乾燥をより追い込むことにより、複合化を強固なものとすることができる。熱処理の温度としては、250℃〜450℃が好ましい。熱処理時間としては、2時間〜4時間が好ましい。 Next, step (2) will be described. In this step, the water in the mixture is distilled off. The method for distilling water is not particularly limited, and examples thereof include a method of heating the mixture to evaporate the water, a method of placing the mixture under reduced pressure to evaporate the water, and the like. Further, as a method of heating the mixture and evaporating water, a method of exposing to hot air for heating or a method of directly heating with a heater or the like may be used. As the temperature at which water is distilled off, the water of crystallization of the compound having a conjugated polyvalent carboxylic acid salt structure showing water solubility is further used by heat transfer by an air flow, heat transfer by a heater, and further under normal pressure and reduced pressure. Generally, it is in the range of 40 ° C. to 300 ° C., more preferably in the range of 60 ° C. to 250 ° C. If the temperature is too low, it takes time to distill water and the economy is impaired, which is not preferable. If the temperature is too high, the target product is lost due to thermal decomposition of a compound having a conjugated polyvalent carboxylate structure showing water solubility. There is a risk of doing it. In the present invention, the composite can be strengthened by further heat-treating the composite from which water has been distilled off to further drive the drying. The temperature of the heat treatment is preferably 250 ° C to 450 ° C. The heat treatment time is preferably 2 hours to 4 hours.

本発明では、炭素材に水溶性を示す共役多価カルボン酸塩構造を有する化合物水溶液を添加混合(工程(1))次いで、水を留去する工程(2)を複数回行い、複合化しても構わない。 In the present invention, an aqueous solution of a compound having a conjugated polyvalent carboxylate structure showing water solubility is added to and mixed with a carbon material (step (1)), and then a step of distilling off water (2) is performed a plurality of times to form a composite. It doesn't matter.

さらに、本発明では後述する電極化の行程を、工程(2)に含み、カルボキシメチルセルロースなどの増粘剤、スチレン-ブタジエンラバーのような結着剤を添加し、直接銅箔などの集電極上に塗工乾燥して、活物質である複合体と電極作成を一気に行うこともできる。その際、増粘剤、結着剤の量は特に制限されるものではないが、通常増粘剤は複合体100質量部に対して0.1〜5質量部、より好ましくは、0.3〜3質量部、結着剤は0.1〜5質量部、より好ましくは、0.3〜3質量部を使用する。 Further, in the present invention, the step of electrodeification described later is included in the step (2), a thickener such as carboxymethyl cellulose and a binder such as styrene-butadiene rubber are added, and the electrode is directly placed on a collecting electrode such as a copper foil. It is also possible to apply and dry the material at once to create a composite and electrodes that are active materials. At that time, the amounts of the thickener and the binder are not particularly limited, but the thickener is usually 0.1 to 5 parts by mass, more preferably 0.3, based on 100 parts by mass of the composite. ~ 3 parts by mass, the binder is 0.1 to 5 parts by mass, more preferably 0.3 to 3 parts by mass.

本発明の製造方法で得られた複合体は炭素材料に水溶性を示す共役多価カルボン酸塩構造を有する化合物が表面に付着した状態を有する。炭素材表面に有するカルボキシル基などの官能基と水溶性を示す共役多価カルボン酸塩構造を有する化合物間の具体的な状態は明らかではないが、前記化合物の粒子上に炭素材料が吸着した状態あるいは炭素材料上に前記化合物が一部化学的に結合された状態となっていると推測される。 The composite obtained by the production method of the present invention has a state in which a compound having a conjugated polyvalent carboxylic acid salt structure showing water solubility in a carbon material is attached to the surface. The specific state between the functional group such as a carboxyl group on the surface of the carbon material and the compound having a conjugated polyvalent carboxylate structure showing water solubility is not clear, but the state in which the carbon material is adsorbed on the particles of the compound. Alternatively, it is presumed that the compound is partially chemically bonded to the carbon material.

本発明で得られる負極活物質は非水電解質二次電池の電極(負極)に用いられる。前記電極は、たとえば、前記負極活物質と結着剤とを混合し、適当な溶剤を加えてペースト状の電極合剤としたものを集電体の表面に塗布・乾燥し、必要に応じて圧縮して形成することで得ることができる。結着剤は例えば、PVDF(ポリフッ化ビニリデン)、ポリテトラフルオロエチレン等のように電解液と反応しないものであれば特に限定されない。中でもPVDFは、活物質表面に付着したPVDFがリチウムイオン移動を阻害することが少なく、良好な入出力特性が得られるため好ましい。結合剤の添加量が多すぎると、得られる電極の抵抗が大きくなるため、電池の内部抵抗が大きくなり電池特性を低下させることがある。また、結合剤の添加量が少なすぎると、負極材料の粒子相互間および集電材との結合が不十分になることがある。結合剤の好ましい添加量は、使用するバインダーの種類によっても異なるが、例えばPVDF系のバインダーでは好ましくは複合体100部に対して1〜30部、より好ましくは、5〜20部である。集電体は、導電性材料からなるものであれば特に制限されないが、例えば、鉄、銅、アルミニウム、ニッケル、ステンレス鋼、チタン、タンタル、金、白金などの金属材料を使用することができる。これらは、1種類を単独で用いてもよく、2種類以上を任意の比率で組み合わせて用いてもよい。 The negative electrode active material obtained in the present invention is used as an electrode (negative electrode) of a non-aqueous electrolyte secondary battery. For the electrode, for example, the negative electrode active material and the binder are mixed, an appropriate solvent is added to form a paste-like electrode mixture, which is applied and dried on the surface of the current collector, and if necessary. It can be obtained by compressing and forming. The binder is not particularly limited as long as it does not react with the electrolytic solution, such as PVDF (polyvinylidene fluoride) and polytetrafluoroethylene. Among them, PVDF is preferable because PVDF adhering to the surface of the active material does not hinder the movement of lithium ions and good input / output characteristics can be obtained. If the amount of the binder added is too large, the resistance of the obtained electrode becomes large, so that the internal resistance of the battery becomes large and the battery characteristics may be deteriorated. Further, if the amount of the binder added is too small, the bonding between the particles of the negative electrode material and the current collector may be insufficient. The amount of the binder added varies depending on the type of binder used, but for example, a PVDF-based binder is preferably 1 to 30 parts, more preferably 5 to 20 parts with respect to 100 parts of the complex. The current collector is not particularly limited as long as it is made of a conductive material, and for example, a metal material such as iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, or platinum can be used. One of these may be used alone, or two or more of them may be used in combination at any ratio.

前記電極の対極(正極)は例えば、電極活物質と結着剤と導電材とを混合し、適当な溶剤を加えてペースト状の電極合剤としたものを集電体の表面に塗布・乾燥し、必要に応じて圧縮して形成することで得ることができる。前記電極活物質としては、金属Li、層状酸化物系(LiMOと表されるもので、Mは金属:例えばLiCoO、LiNiO、LiMnO、またはLiNixCoyMozO(ここでx、y、zは組成比を表わす))、オリビン系(LiMPOで表され、Mは金属:例えばLiFePOなど)、スピネル系(LiMで表され、Mは金属:例えばLiMnなど)の複合金属カルコゲン化合物が好ましく、これらのカルコゲン化合物を必要に応じて混合して使用してもよい。これらの正極材料を適当なバインダーと電極に導電性を付与するための炭素材料とともに成形して、導電性の集電材上に層形成することにより正極が形成される。 For the counter electrode (positive electrode) of the electrode, for example, a paste-like electrode mixture prepared by mixing an electrode active material, a binder, and a conductive material and adding an appropriate solvent is applied and dried on the surface of the current collector. It can be obtained by compressing and forming as needed. The electrode active material includes a metal Li, a layered oxide system (represented as LiMO 2, and M is a metal: for example, LiCoO 2 , LiNiO 2 , LiMnO 2 , or LiNixCoyMozO 2 (where x, y, z are x, y, z). (Representing composition ratio)), olivine type (represented by LiMPO 4 , M is a metal: for example LiFePO 4 ), spinel type (represented by LiM 2 O 4 , M is a metal: for example LiMn 2 O 4 ) Metallic chalcogen compounds are preferable, and these chalcogen compounds may be mixed and used as necessary. A positive electrode is formed by molding these positive electrode materials together with an appropriate binder and a carbon material for imparting conductivity to the electrodes and forming a layer on the conductive current collector.

前記非水電解質二次電池の電解液としては、一般に非水溶媒に電解質を溶解することにより形成される。非水溶媒としては、例えばプロピレンカーボネート、エチレンカーボネート、ジメチルカーボネート、ジエチルカーボネート、ジメトキシエタン、ジエトキシエタン、γ−ブチルラクトン、テトラヒドロフラン、2−メチルテトラヒドロフラン、スルホラン、または1,3−ジオキソラン等の有機溶媒を、一種または二種以上を組み合わせて用いることができる。また、電解質としては、LiClO¬4、LiPF、LiBF、LiCFSO、LiAsF、LiCl、LiBr、LiB(C、またはLiN(SOCF等が用いられる。 The electrolytic solution of the non-aqueous electrolyte secondary battery is generally formed by dissolving an electrolyte in a non-aqueous solvent. Examples of the non-aqueous solvent include organic solvents such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, dimethoxyethane, diethoxyethane, γ-butyl lactone, tetrahydrofuran, 2-methyltetrahydrofuran, sulfolane, and 1,3-dioxolane. Can be used alone or in combination of two or more. Further, as the electrolyte, LiClO ¬ 4 , LiPF 6 , LiBF 4 , LiCF 3 SO 3 , LiAsF 6 , LiCl, LiBr, LiB (C 6 H 5 ) 4 , LiN (SO 3 CF 3 ) 2, or the like is used. ..

前記非水電解質二次電池は、正極と負極との間にセパレータを備えていても良い。セパレータとしては、二次電池に通常用いられる不織布、その他の多孔質材料からなる透過性または透液性のセパレータを用いることができる。あるいはセパレータの代わりに、もしくはセパレータと一緒に、電解液を含浸させたポリマーゲルからなる固体電解質を用いることもできる。 The non-aqueous electrolyte secondary battery may include a separator between the positive electrode and the negative electrode. As the separator, a permeable or liquid-permeable separator made of a non-woven fabric or other porous material usually used for a secondary battery can be used. Alternatively, instead of the separator, or together with the separator, a solid electrolyte composed of a polymer gel impregnated with an electrolytic solution can be used.

本発明で得られる負極活物質を用いた非水電解質二次電池は、十分な充放電容量を示し、種々の用途への適用が期待される。 The non-aqueous electrolyte secondary battery using the negative electrode active material obtained in the present invention exhibits a sufficient charge / discharge capacity, and is expected to be applied to various applications.

以下、実施例によって本発明を具体的に説明するが、これらは本発明の範囲を限定するものではない。なお、以下に負極活物質の各測定方法を記載するが、実施例を含めて、本明細書中に記載する各測定結果は、以下の方法により求めた値に基づくものである。 Hereinafter, the present invention will be specifically described with reference to Examples, but these do not limit the scope of the present invention. In addition, although each measurement method of a negative electrode active material is described below, each measurement result described in this specification including an Example is based on the value obtained by the following method.

(充放電試験)
各実施例および比較例で得られたコインセルについて、充放電試験装置(東洋システム株式会社製、「TOSCAT」)を用いて、初回充電前に直流抵抗値を測定後、充放電試験を行った。リチウムのドーピングは、活物質質量に対し0.26mAで行い、リチウム電位に対して5mVになるまでドーピングした。このときの初回の容量(mAh/g)を充電容量とした。次いで、活物質質量に対し0.26mAで行い、リチウム電位に対して3.0Vになるまで脱ドーピングを行い、このとき放電した容量を、芳香族環構造および前記芳香族環構造の環を構成する原子に結合した2以上のCOOM基を有する化合物の質量あたりに換算した値を初期セル容量(mAh/g)として評価した。また、初回放電曲線で得られる平坦電位域(テレフタル酸ジリチウムでは0.95−1.05V vs.Li/Li)の範囲で発現した容量を初期平坦領域容量とし、さらにこの初期平坦領域容量をテレフタル酸ジリチウムの理論容量301mAh/gで除し化合物の利用効率(%)とした。
(Charge / discharge test)
The coin cells obtained in each Example and Comparative Example were subjected to a charge / discharge test after measuring the DC resistance value before the first charge using a charge / discharge test device (manufactured by Toyo System Co., Ltd., “TOSCAT”). Lithium was doped at 0.26 mA with respect to the mass of the active material and doped to 5 mV with respect to the lithium potential. The initial capacity (mAh / g) at this time was defined as the charging capacity. Next, it was carried out at 0.26 mA with respect to the mass of the active material, dedoping was carried out until it became 3.0 V with respect to the lithium potential, and the discharged capacitance at this time constitutes an aromatic ring structure and a ring of the aromatic ring structure. The value converted per mass of the compound having two or more COOM groups bonded to the atom to be used was evaluated as the initial cell volume (mAh / g). Further, the capacity expressed in the flat potential region (0.95-1.05 V vs. Li / Li + for dilithium terephthalate) obtained by the initial discharge curve is defined as the initial flat region capacity, and the initial flat region capacity is further used. Dilithium terephthalate was divided by the theoretical volume of 301 mAh / g to obtain the compound utilization efficiency (%).

(実施例1)
三口フラスコにテレフタル酸とイオン交換水を入れ、マグネチックスターラーで撹拌し、イオン交換水中にテレフタル酸を分散させた後、水酸化リチウム一水和物をイオン交換水に溶解した水溶液を、テレフタル酸分散液に添加し、還流下、80℃で撹拌した。テレフタル酸8.8gに対して、水酸化リチウム一水和物を4.2g、イオン交換水は300mLとした。その後、内容液をなすフラスコに移し、ロータリーエバポレーターを用いてイオン交換水を留去した。析出した粉末をスクリュー管に入れ、19Paまで減圧し、60℃で乾燥を行い、テレフタル酸ジリチウムを得た。
得たテレフタル酸ジリチウムをイオン交換水に溶解し、15質量%テレフタル酸ジリチウム水溶液を調製した。15質量%テレフタル酸ジリチウム水溶液をアセチレンブラック(デンカ社製、製品名「デンカブラック Li−100」)と混合して(混合物中の固形分濃度20質量%)5分間80℃で乾燥する、という操作をテレフタル酸ジリチウムとアセチレンブラックの質量比が2:1となるまで6回にわけて繰り返し、負極活物質(1)を得た。
負極の作製は、負極活物質(A)を90重量部、PVDF(ポリフッ化ビニリデン)10重量部を混合し、NMP(N−メチルピロリドン)を加えて、ボールミルを使用して固形分濃度を20質量%としたスラリーを得た。得られたスラリーを、厚さ18μmの銅箔上に塗布し、乾燥させた後、プレスして、厚さ70μmの電極を得た。上記で得た電極を径14mmに打ち抜き負極とし、径15mmに打ち抜いた金属リチウム箔を正極とした。電解質としては、溶媒として、エチレンカーボネート(EC)とエチルメチルカーボネート(EMC)とジメチルカーボネート(DMC)の混合溶媒(体積比 EC/EMC/DMC=1/1/1)を用い、この溶媒に、LiClOを1mol/L溶解して用いた。セパレータにはポリプロピレン膜を使用した。アルゴン雰囲気下のグローブボックス内でコインセルを作製した。このコインセルについて、上述の方法に従って、充放電試験を行った。結果について表1に示す。
(Example 1)
Put terephthalic acid and ion-exchanged water in a three-necked flask, stir with a magnetic stirrer, disperse terephthalic acid in ion-exchanged water, and then add an aqueous solution of lithium hydroxide monohydrate in ion-exchanged water. It was added to the dispersion and stirred at 80 ° C. under reflux. With respect to 8.8 g of terephthalic acid, 4.2 g of lithium hydroxide monohydrate and 300 mL of ion-exchanged water were used. Then, it was transferred to a flask forming a content liquid, and ion-exchanged water was distilled off using a rotary evaporator. The precipitated powder was placed in a screw tube, the pressure was reduced to 19 Pa, and the mixture was dried at 60 ° C. to obtain dilithium terephthalate.
The obtained dilithium terephthalate was dissolved in ion-exchanged water to prepare a 15% by mass dilithium terephthalate aqueous solution. An operation of mixing a 15% by mass dilithium terephthalate aqueous solution with acetylene black (manufactured by Denka, product name "Denka Black Li-100") (solid content concentration in the mixture is 20% by mass) and drying at 80 ° C. for 5 minutes. Was repeated 6 times until the mass ratio of dilithium terephthalate to acetylene black was 2: 1 to obtain the negative electrode active material (1).
To prepare the negative electrode, 90 parts by weight of the negative electrode active material (A) and 10 parts by weight of PVDF (polyvinylidene fluoride) are mixed, NMP (N-methylpyrrolidone) is added, and the solid content concentration is 20 by using a ball mill. A slurry having a mass% was obtained. The obtained slurry was applied onto a copper foil having a thickness of 18 μm, dried, and then pressed to obtain an electrode having a thickness of 70 μm. The electrode obtained above was used as a negative electrode punched to a diameter of 14 mm, and a metallic lithium foil punched to a diameter of 15 mm was used as a positive electrode. As the electrolyte, a mixed solvent (volume ratio EC / EMC / DMC = 1/1/1) of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) was used as a solvent, and this solvent was used. LiClO 4 was dissolved in 1 mol / L and used. A polypropylene film was used for the separator. A coin cell was prepared in a glove box under an argon atmosphere. This coin cell was subjected to a charge / discharge test according to the above method. The results are shown in Table 1.

(実施例2)
実施例1の負極活物質(A)に400℃、3時間の熱処理を施し、負極活物質(B)を得た。負極活物質(A)を負極活物質(B)に置き換えて電極を作製した以外は実施例1と同様にして評価を行った。結果を表1に示す。
(Example 2)
The negative electrode active material (A) of Example 1 was heat-treated at 400 ° C. for 3 hours to obtain a negative electrode active material (B). The evaluation was carried out in the same manner as in Example 1 except that the negative electrode active material (A) was replaced with the negative electrode active material (B) to prepare an electrode. The results are shown in Table 1.

(実施例3)
実施例1において、テレフタル酸に代えてフマル酸8.1gを使用した以外は、実施例1と同様に負極活物質(負極活物質(C)と称する)を作製し、評価を行った。なお、フタル酸ジリチウムの理論容量は387mAh/gとして利用効率を計算した。結果を表1に示す。
(Example 3)
A negative electrode active material (referred to as a negative electrode active material (C)) was prepared and evaluated in the same manner as in Example 1 except that 8.1 g of fumaric acid was used instead of terephthalic acid in Example 1. The theoretical capacity of dilithium phthalate was 387 mAh / g, and the utilization efficiency was calculated. The results are shown in Table 1.

(実施例4)
実施例3において、フマル酸に代えてマレイン酸を使用した以外は、実施例3負極活物質と同様に負極活物質(負極活物質(D)と称する)を作製し、評価を行った。なお、マレイン酸ジリチウムの理論容量は387mAh/gとして利用効率を計算した。結果を表1に示す。
(Example 4)
A negative electrode active material (referred to as a negative electrode active material (D)) was prepared and evaluated in the same manner as in Example 3 negative electrode active material except that maleic acid was used instead of fumaric acid in Example 3. The theoretical capacity of dilithium maleate was 387 mAh / g, and the utilization efficiency was calculated. The results are shown in Table 1.

(実施例5)
実施例4において、炭素材に水溶液を逐次添加せず、一括添加した以外は、実施例4と同様に負極活物質(負極活物質(E)と称する)を作製し、評価を行った。結果を表1に示す。
(Example 5)
In Example 4, a negative electrode active material (referred to as a negative electrode active material (E)) was prepared and evaluated in the same manner as in Example 4, except that the aqueous solution was not sequentially added to the carbon material but was added all at once. The results are shown in Table 1.

(比較例1)
実施例1で得たテレフタル酸ジリチウムを60重量部、アセチレンブラックを30重量部、PVDF(ポリフッ化ビニリデン)を10重量部を混合し、NMP(N−メチルピロリドン)を加えて遊星ボールミルを使用して固形分濃度20%としたスラリー状の電極合剤を得た。得られた電極合剤を厚さ18μmの銅箔上に塗布し、乾燥させた後、プレスして、厚さ70μmの電極を得た以外は実施例1と同様にして評価を行った。結果について表1に示す。
(Comparative Example 1)
60 parts by weight of dilithium terephthalate obtained in Example 1, 30 parts by weight of acetylene black, and 10 parts by weight of PVDF (polyvinylidene fluoride) were mixed, NMP (N-methylpyrrolidone) was added, and a planetary ball mill was used. A slurry-like electrode mixture having a solid content concentration of 20% was obtained. The obtained electrode mixture was applied onto a copper foil having a thickness of 18 μm, dried, and then pressed to obtain an electrode having a thickness of 70 μm, and the evaluation was carried out in the same manner as in Example 1. The results are shown in Table 1.

(比較例2)
実施例1で得たテレフタル酸ジリチウムと、炭素材料としてアセチレンブラックを、重量比2:1になるようにメノウボールの入ったメノウ製粉砕容器に入れ、周波数15Hzで30分間ミキサーミルで処理をして、負極活物質(F)を得た。評価は実施例1と同様に行った。結果を表1に示す。
(Comparative Example 2)
Dilithium terephthalate obtained in Example 1 and acetylene black as a carbon material were placed in an agate crushing container containing agate balls so as to have a weight ratio of 2: 1 and treated with a mixer mill at a frequency of 15 Hz for 30 minutes. The negative electrode active material (F) was obtained. The evaluation was carried out in the same manner as in Example 1. The results are shown in Table 1.

Figure 2020184473
Figure 2020184473

表1より、比較例1および2に比べ、本発明の方法で得られた実施例1〜5の負極活物質A〜Fを用いて作製したコインセルでは、高い初期平坦領域容量、初期セル容量、利用効率を示した。 From Table 1, as compared with Comparative Examples 1 and 2, in the coin cell produced by using the negative electrode active materials A to F of Examples 1 to 5 obtained by the method of the present invention, the initial flat region capacity and the initial cell capacity were higher. The utilization efficiency was shown.

Claims (4)

(1)水溶性を示す共役多価カルボン酸塩構造を有する化合物を含む水溶液を炭素材料と混合して混合物を得る工程、および
(2)前記混合物中の水を留去する工程を含む、非水系二次電池用負極活物質の製造方法。
Non-compounding, including (1) a step of mixing an aqueous solution containing a compound having a conjugated polyvalent carboxylic acid salt structure showing water solubility with a carbon material to obtain a mixture, and (2) a step of distilling off water in the mixture. A method for producing a negative electrode active material for an aqueous secondary battery.
前記化合物のカルボン酸塩を構成する金属がアルカリ金属元素である、請求項1記載の非水系二次電池用負極活物質の製造方法。 The method for producing a negative electrode active material for a non-aqueous secondary battery according to claim 1, wherein the metal constituting the carboxylate of the compound is an alkali metal element. 前記化合物の炭素数が4〜14である、請求項1または2に記載の製造方法。 The production method according to claim 1 or 2, wherein the compound has 4 to 14 carbon atoms. 前記化合物の構造は、次式(I)〜(III)で表される化合物から選択される少なくとも一つである、請求項1〜3のいずれかに記載の製造方法。
Figure 2020184473
(I)
(式中、mは1~2の整数を表し、Mは金属元素を表し、RおよびRはそれぞれ独立して置換基として水酸基、ハロゲンおよびカルボキシル基からなる群から選ばれる少なくとも一つを有してもよい炭素数1から2のアルキル基、水素、カルボキシル基または塩化されたカルボキシル基のいずれかを表す。)
Figure 2020184473
(II)
(式中、nは1~2の整数を表し、Mは金属元素を表し、R、R、RおよびRはそれぞれ独立して置換基として水酸基、ハロゲンおよびカルボキシル基からなる群から選ばれる少なくとも一つを有してもよい炭素数1から2のアルキル基、水素、カルボキシル基または塩化されたカルボキシル基のいずれかを表す。)
Figure 2020184473
(III)
(式中、Mは金属元素を表し、R、R、R、R10、R11およびR12はそれぞれ独立して置換基として水酸基、ハロゲンおよびカルボキシル基からなる群から選ばれる少なくとも一つを有してもよい炭素数1から2のアルキル基、水素、カルボキシル基または塩化されたカルボキシル基のいずれかを表す。)


The production method according to any one of claims 1 to 3, wherein the structure of the compound is at least one selected from the compounds represented by the following formulas (I) to (III).
Figure 2020184473
(I)
(In the formula, m represents an integer of 1 to 2, M represents a metal element, and R 1 and R 2 each independently have at least one selected from the group consisting of a hydroxyl group, a halogen, and a carboxyl group as substituents. It represents either an alkyl group having 1 to 2 carbon atoms, hydrogen, a carboxyl group, or a chloride carboxyl group.)
Figure 2020184473
(II)
(In the formula, n represents an integer of 1 to 2, M represents a metal element, and R 3 , R 4 , R 5 and R 6 are independently substituted groups consisting of a hydroxyl group, a halogen and a carboxyl group. It represents either an alkyl group having 1 to 2 carbon atoms, a hydrogen, a carboxyl group, or a chloride carboxyl group which may have at least one selected.)
Figure 2020184473
(III)
(In the formula, M represents a metal element, and R 7 , R 8 , R 9 , R 10 , R 11 and R 12 are at least one independently selected from the group consisting of hydroxyl groups, halogens and carboxyl groups as substituents. It represents either an alkyl group having 1 to 2 carbon atoms, hydrogen, a carboxyl group, or a chloride carboxyl group which may have one.)


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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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