JP5016276B2 - Negative electrode for non-aqueous electrolyte secondary battery, method for producing the same, and non-aqueous electrolyte secondary battery - Google Patents
Negative electrode for non-aqueous electrolyte secondary battery, method for producing the same, and non-aqueous electrolyte secondary battery Download PDFInfo
- Publication number
- JP5016276B2 JP5016276B2 JP2006230809A JP2006230809A JP5016276B2 JP 5016276 B2 JP5016276 B2 JP 5016276B2 JP 2006230809 A JP2006230809 A JP 2006230809A JP 2006230809 A JP2006230809 A JP 2006230809A JP 5016276 B2 JP5016276 B2 JP 5016276B2
- Authority
- JP
- Japan
- Prior art keywords
- negative electrode
- secondary battery
- electrolyte secondary
- active material
- binder
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Description
本発明は非水電解質二次電池に関するものであり、さらに詳しくは、非水電解質二次電池の負極の改良に関するものである。 The present invention relates to a non-aqueous electrolyte secondary battery, and more particularly to improvement of a negative electrode of a non-aqueous electrolyte secondary battery.
非水電解質電池は、小型かつ軽量で、高エネルギー密度を有し、各種電子機器の主電源やメモリーバックアップ用電源に用いられている。近年、携帯型の電子機器等の著しい発展に伴い、機器のさらなる小型化、高性能化、メンテナンスフリー化が進む中で、非水電解質電池のさらなる高エネルギー密度化が強く要望されている。
電池特性は、正極活物質および負極活物質の特性に大きく依存するため、正極活物質および負極活物質に関する検討が多く行われている。
Nonaqueous electrolyte batteries are small and light, have high energy density, and are used as main power sources for various electronic devices and power sources for memory backup. In recent years, with the remarkable development of portable electronic devices and the like, as devices are further reduced in size, performance, and maintenance-free, there is a strong demand for higher energy density of nonaqueous electrolyte batteries.
Since battery characteristics largely depend on the characteristics of the positive electrode active material and the negative electrode active material, many studies on the positive electrode active material and the negative electrode active material have been conducted.
例えば、ＳｉはＬｉと金属間化合物を生成して、Ｌｉを可逆的に吸蔵・放出することができる。このＳｉを負極活物質に用いた場合、Ｓｉの理論容量は約４２００ｍＡｈ／ｇであり、従来用いられていた炭素材料の理論容量約３７０ｍＡｈ／ｇと比較して極めて大きい。このため、電池の小型化および高容量化を目的として、Ｓｉを負極活物質に用いた数多くの改良検討が行われている。 For example, Si can generate Li and an intermetallic compound, and can absorb and release Li reversibly. When this Si is used for the negative electrode active material, the theoretical capacity of Si is about 4200 mAh / g, which is extremely large compared to the theoretical capacity of about 370 mAh / g of the conventionally used carbon material. For this reason, many improvement studies using Si as a negative electrode active material have been conducted for the purpose of reducing the size and increasing the capacity of the battery.
しかし、Ｓｉ粒子はＬｉの吸蔵・放出にともなう体積変化により割れを生じ微粉化しやすい。このため、Ｓｉを含む負極活物質は高容量を有するが、充放電サイクルに伴う容量低下が大きく、サイクル寿命が短くなるという不利な面を有する。
これに対しては、例えば、特許文献１では、Ｓｉを主体するＡ相と、遷移金属のケイ化物を含むＢ相からなり、Ａ相およびＢ相の少なくとも一方が、アモルファス状態および低結晶状態の少なくとも一方の状態である負極活物質を用いることが提案されている。これにより、Ｌｉの吸収・放出に伴う体積変化が低減され、サイクル寿命が向上する。
However, Si particles are easily cracked due to changes in volume accompanying the insertion and release of Li. For this reason, although the negative electrode active material containing Si has a high capacity, it has a disadvantage in that the capacity reduction accompanying the charge / discharge cycle is large and the cycle life is shortened.
On the other hand, for example, in Patent Document 1, it consists of an A phase mainly composed of Si and a B phase containing a silicide of a transition metal, and at least one of the A phase and the B phase is in an amorphous state or a low crystalline state. It has been proposed to use a negative electrode active material in at least one state. Thereby, the volume change accompanying absorption and discharge | release of Li is reduced, and cycle life improves.
ところで、正極および負極は、充放電反応に寄与する活物質、導電材、およびバインダーなどを含む合剤からなる。導電材は、活物質粒子間の電子伝導性の向上のために用いられる。バインダーは、活物質粒子や導電材などの合剤中の電極材料の接着、および合剤と集電体との接着のために用いられる。
バインダーには、ポリ四フッ化エチレン（ＰＴＦＥ）やポリフッ化ビニリデン（ＰＶＤＦ）などのフッ素系樹脂が用いられる。このフッ素系樹脂は非水電解質に対し安定であり、活物質や導電材との結着性に優れている。
By the way, a positive electrode and a negative electrode consist of a mixture containing the active material, conductive material, binder, etc. which contribute to charging / discharging reaction. The conductive material is used to improve electronic conductivity between the active material particles. The binder is used for adhesion of the electrode material in the mixture such as active material particles and conductive material, and adhesion between the mixture and the current collector.
As the binder, a fluorine-based resin such as polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF) is used. This fluororesin is stable with respect to non-aqueous electrolytes and has excellent binding properties with active materials and conductive materials.
しかし、ＳｉやＳｎなどを活物質に用いる場合、充放電時のＬｉの吸蔵・放出に伴う上記活物質の体積変化が大きいため、上記フッ素系樹脂をバインダーに用いても、合剤の接着状態を良好に維持することが難しい。また、合剤と集電体との接着性が低下しやすい。よって、充放電に伴い合剤の集電性が低下し、活物質の利用率が低下して、充放電サイクルに伴う劣化が非常に大きくなる。
また、バインダーにポリイミドを用いると、合剤中の電極材料の結着性、および合剤と集電体との結着性が向上し、充放電時の体積変化の大きい活物質を用いた場合でも、合剤が集電体から脱離することがなく、良好な充放電サイクル特性が得られることが知られている。
However, when Si, Sn or the like is used as an active material, the volume of the active material changes greatly due to insertion and extraction of Li during charge / discharge, so even if the fluorine resin is used as a binder, Is difficult to maintain well. Moreover, the adhesiveness between the mixture and the current collector tends to be lowered. Therefore, the current collecting property of the mixture decreases with charge / discharge, the utilization factor of the active material decreases, and deterioration due to the charge / discharge cycle becomes very large.
In addition, when polyimide is used as the binder, the binding property of the electrode material in the mixture and the binding property between the mixture and the current collector are improved, and an active material having a large volume change during charge / discharge is used. However, it is known that the charge / discharge cycle characteristics can be obtained without the mixture being detached from the current collector.
例えば、特許文献２では、サイクル特性の向上を目的として、以下のように提案されている。二次電池用負極において、ケイ素およびケイ素合金の少なくとも一方からなる活物質を含む合剤層中、または合剤層と金属箔集電体との間にバインダーとしてポリイミドを含む導電性中間層を配する。金属箔集電体上に導電性中間層を配置した状態で非酸化雰囲気下にて焼結する。導電性中間層が、充放電反応に伴う負極活物質の膨張収縮により、合剤層が集電体から剥離するのを抑制し、この中間層が合剤層と集電体との間の密着性を高める。 For example, Patent Document 2 proposes the following for the purpose of improving cycle characteristics. In the negative electrode for a secondary battery, a conductive intermediate layer containing polyimide as a binder is disposed in a mixture layer containing an active material composed of at least one of silicon and a silicon alloy, or between the mixture layer and the metal foil current collector. To do. Sintering is performed in a non-oxidizing atmosphere with the conductive intermediate layer disposed on the metal foil current collector. The conductive intermediate layer suppresses separation of the mixture layer from the current collector due to the expansion and contraction of the negative electrode active material accompanying the charge / discharge reaction, and this intermediate layer adheres between the mixture layer and the current collector. Increase sex.
ところで、モバイル機器の製造に関して、プリント基板上に電子部品を取り付ける方法としては、電子部品を高密度に且つ一括してハンダ付け可能なリフローハンダ付けが多く採用されている。
リフローハンダ付けは、以下のような方法である。プリント基板上のハンダ付けを行う部分にハンダクリーム等を塗布する。その後、ハンダ付け部分が２００〜２６０℃となるように設定された高温雰囲気の炉内に、電子部品を搭載したプリント基板を通過させる。このとき、ハンダが溶融しハンダ付けされる。
By the way, regarding the manufacture of mobile devices, as a method of attaching electronic components on a printed circuit board, reflow soldering capable of soldering electronic components at a high density and in a lump is often employed.
The reflow soldering is performed as follows. A solder cream or the like is applied to the part to be soldered on the printed circuit board. Thereafter, the printed circuit board on which electronic components are mounted is passed through a furnace in a high-temperature atmosphere set so that the soldered portion becomes 200 to 260 ° C. At this time, the solder is melted and soldered.
このため、メモリーバックアップ用途としてプリント基板上に非水電解質二次電池を設置し、上記のようなリフローハンダ付けを採用する場合、この電池自身にも耐熱性が要求される。これに対しては、電解液、セパレータ、ガスケットなどの電池構成部材に耐熱性を有する材料を採用することが検討されている。 For this reason, when a non-aqueous electrolyte secondary battery is installed on a printed circuit board as a memory backup application and the above reflow soldering is adopted, the battery itself is also required to have heat resistance. In response to this, it has been studied to employ heat-resistant materials for battery constituent members such as an electrolytic solution, a separator, and a gasket.
耐熱性に優れた非水電解質二次電池用のバインダーとしては、例えば、ポリイミド（融点：約５００℃）が挙げられる。ポリイミドは、熱安定性が極めて高く他の有機高分子材料と比較して優れた耐熱性を有する。
しかし、非水電解質二次電池における負極のバインダーにポリイミドを使用すると、電池の低温特性が低下しやすい。
As a binder for a non-aqueous electrolyte secondary battery excellent in heat resistance, for example, polyimide (melting point: about 500 ° C.) can be mentioned. Polyimide has extremely high thermal stability and excellent heat resistance compared to other organic polymer materials.
However, when polyimide is used as a negative electrode binder in a non-aqueous electrolyte secondary battery, the low temperature characteristics of the battery are likely to deteriorate.
また、特許文献３では、以下のように提案されている。非水電解液電池において、負極活物質に炭素材料を用いる。バインダーとしてのポリイミド樹脂と、結着助材としてのアクリル酸ポリマー、メタクリル酸ポリマー、ウレタンポリマーを混合し、その後結着助材を熱処理により分解除去する。これによりサイクル特性が向上する。
しかし、熱処理により結着助材が分解除去され、ポリイミドのみがバインダーとして機能するため、上記のように低温特性が低下する。
Patent Document 3 proposes the following. In the nonaqueous electrolyte battery, a carbon material is used as the negative electrode active material. A polyimide resin as a binder and an acrylic acid polymer, methacrylic acid polymer and urethane polymer as a binder aid are mixed, and then the binder aid is decomposed and removed by heat treatment. This improves the cycle characteristics.
However, since the binding aid is decomposed and removed by heat treatment, and only polyimide functions as a binder, the low-temperature characteristics are reduced as described above.
さらに、特許文献４では、イミド化が終了した状態で有機溶媒へ溶解性を示すポリイミドおよびフッ素系ポリマーの混合物を電極合剤のバインダーに用いることが提案されている。これにより、電極合剤の熱処理によるイミド化が必要でなくなり生産性が向上する。 Furthermore, Patent Document 4 proposes that a mixture of polyimide and fluorine-based polymer, which is soluble in an organic solvent in a state where imidization is completed, is used as a binder of an electrode mixture. Thereby, imidation by the heat processing of an electrode mixture becomes unnecessary, and productivity improves.
しかし、有機溶媒に対して溶解性を示す上記バインダーは、非水電解質二次電池における有機電解質中に溶出するため、バインダーとしての機能を維持することが困難であり、サイクル特性や保存特性が低下する。また、高温で熱処理しないため、イミド化による脱水縮合の際に発生する水が残り、これが正極活物質に悪影響を与える場合がある。
本発明の目的は、活物質がＳｉを含む場合でも結着性に優れ、かつバインダーにポリイミドを用いた場合でも電子伝導性に優れた負極およびその製造方法を提供することである。また、本発明の目的は、上記負極を用いて、優れた充放電サイクル特性、低温特性、および耐熱性を有する高エネルギー密度の非水電解質電池を提供することである。 An object of the present invention is to provide a negative electrode excellent in binding property even when the active material contains Si and excellent in electronic conductivity even when polyimide is used as a binder, and a method for producing the same. Another object of the present invention is to provide a high energy density non-aqueous electrolyte battery having excellent charge / discharge cycle characteristics, low temperature characteristics, and heat resistance using the negative electrode.
本発明は、Ｓｉを含有する活物質、バインダー、および導電材を含み、前記バインダーが、ポリアミド酸およびポリアクリル酸を含む混合物を１５０〜３００℃で加熱することにより得られ、前記加熱により、前記ポリアミド酸は、イミド化されており、前記導電材が、炭素材料である非水電解質二次電池用負極に関する。
また、本発明は、上記の負極と、正極と、前記正極と前記負極との間に配されるセパレータと、非水電解質とを具備する非水電解質二次電池に関する。
The present invention includes an active material containing Si, a binder, and a conductive material, and the binder is obtained by heating a mixture containing polyamic acid and polyacrylic acid at 150 to 300 ° C. The polyamic acid is imidized, and the conductive material relates to a negative electrode for a nonaqueous electrolyte secondary battery, which is a carbon material.
The present invention also relates to a nonaqueous electrolyte secondary battery comprising the above negative electrode, a positive electrode, a separator disposed between the positive electrode and the negative electrode, and a nonaqueous electrolyte.
さらに、本発明は、Ｓｉを含む活物質と、ポリアミド酸およびポリアクリル酸を含むバインダー原料溶液と、導電材として炭素材料とを混合した後、加熱・乾燥して負極合剤を得る工程（１）と、前記負極合剤を加圧成形してペレットを得た後、前記ペレットを１５０〜３００℃で加熱して前記ポリアミド酸をイミド化させてポリイミドを得、バインダーとしてポリイミドおよびポリアクリル酸を含む負極を得る工程（２）を含む、負極の作製方法に関する。 Furthermore, the present invention includes a step of obtaining a negative electrode mixture by mixing an active material containing Si, a binder raw material solution containing polyamic acid and polyacrylic acid, and a carbon material as a conductive material, followed by heating and drying (1) ) And the negative electrode mixture are pressure-molded to obtain pellets, and then the pellets are heated at 150 to 300 ° C. to imidize the polyamic acid to obtain polyimide, and polyimide and polyacrylic acid are used as binders. The present invention relates to a method for manufacturing a negative electrode, including a step (2) of obtaining a negative electrode including the negative electrode.
本発明によれば、Ｓｉを含有する負極活物質にポリアクリル酸が優先的に結合し、ポリイミドが負極活物質を強く被覆することを抑制できるため、優れた結着性および耐熱性とともに、優れた電子伝導性が得られる。また、本発明によれば、上記負極を用いることにより、充放電サイクル特性、低温特性、および耐熱性に優れた高エネルギー密度の非水電解質二次電池が得られる。 According to the present invention, polyacrylic acid is preferentially bonded to the Si-containing negative electrode active material, and it is possible to prevent polyimide from strongly covering the negative electrode active material. Electronic conductivity can be obtained. Further, according to the present invention, by using the negative electrode, a high energy density non-aqueous electrolyte secondary battery excellent in charge / discharge cycle characteristics, low temperature characteristics, and heat resistance can be obtained.
本発明は、Ｓｉを含む負極活物質、バインダー、および導電材を含み、バインダーがポリイミドおよびポリアクリル酸であり、導電材が炭素材料である非水電解質二次電池用負極に関する。 The present invention relates to a negative electrode for a non-aqueous electrolyte secondary battery including a negative electrode active material containing Si, a binder, and a conductive material, wherein the binder is polyimide and polyacrylic acid, and the conductive material is a carbon material.
従来、バインダーにポリイミドを単独で用いる場合、ポリイミドは耐熱性とともに結着性に優れるため、電池のサイクル特性が向上するが、電池の低温特性が低下する。これは、Ｓｉを含む負極活物質粒子がポリイミドで広く被覆されることにより、負極活物質粒子と導電材である炭素材料との接触が妨げられ、負極の電子伝導性が低下するためであると推測される。 Conventionally, when polyimide is used alone as a binder, since polyimide has excellent heat resistance and binding properties, the cycle characteristics of the battery are improved, but the low temperature characteristics of the battery are lowered. This is because when the negative electrode active material particles containing Si are widely covered with polyimide, the contact between the negative electrode active material particles and the carbon material as the conductive material is hindered, and the electronic conductivity of the negative electrode is reduced. Guessed.
また、バインダーにポリアクリル酸を単独で用いる場合、ポリアクリル酸はポリイミドと比べて結着性が弱く、また耐熱性が低いため、ポリイミドの場合のように電池の低温特性は低下しないが、電池のサイクル特性および耐熱性が低下する。 In addition, when polyacrylic acid is used alone as the binder, polyacrylic acid has a lower binding property than polyimide and has low heat resistance, so the low temperature characteristics of the battery do not deteriorate as in the case of polyimide. Cycle characteristics and heat resistance are reduced.
これに対して、本発明のように、負極のバインダーにポリイミドおよびポリアクリル酸の混合物を用いると、Ｓｉを含む負極活物質粒子にポリアクリル酸が優先的に結合し、負極活物質粒子がポリイミドで被覆され難くなる。これにより、負極の電子伝導性が改善され、バインダーとしてポリイミドを単独で用いた場合に生じる電池の低温特性の低下を抑制することができる。また、バインダーにポリイミドおよびポリアクリル酸の両方を用いた場合、ポリイミドは結着性に優れているため、バインダーにポリイミドを単独で用いた場合と同等のサイクル特性が得られる。 On the other hand, when a mixture of polyimide and polyacrylic acid is used as a negative electrode binder as in the present invention, polyacrylic acid is preferentially bonded to negative electrode active material particles containing Si, and the negative electrode active material particles are polyimide. It becomes difficult to be covered with. Thereby, the electronic conductivity of a negative electrode is improved and the fall of the low temperature characteristic of the battery which arises when a polyimide is used alone as a binder can be suppressed. In addition, when both polyimide and polyacrylic acid are used for the binder, since the polyimide is excellent in binding properties, cycle characteristics equivalent to those when the polyimide is used alone for the binder can be obtained.
このように、上記負極を用いることにより、充放電サイクル特性、低温特性、および耐熱性に優れた高エネルギー密度の非水電解質二次電池が得られる。
負極中のポリアクリル酸含有量は負極活物質１００重量部あたり０．５〜３０重量部であるのが好ましい。
負極中のポリイミド含有量は負極活物質１００重量部あたり６．５〜４０重量部であるのが好ましい。
負極中に含まれるポリアクリル酸とポリイミドの重量比は、５〜９０：９〜９５であるのが好ましい。
Thus, by using the negative electrode, a high energy density non-aqueous electrolyte secondary battery excellent in charge / discharge cycle characteristics, low temperature characteristics, and heat resistance can be obtained.
The polyacrylic acid content in the negative electrode is preferably 0.5 to 30 parts by weight per 100 parts by weight of the negative electrode active material.
The polyimide content in the negative electrode is preferably 6.5 to 40 parts by weight per 100 parts by weight of the negative electrode active material.
The weight ratio of polyacrylic acid and polyimide contained in the negative electrode is preferably 5 to 90: 9 to 95.
リチウムと合金化可能なＳｉを含む負極活物質は、例えば、ケイ素単体、ケイ素酸化物、ケイ素合金などが挙げられる。ケイ素酸化物には、例えばＳｉＯx（０＜ｘ＜２、好ましくは０．１≦ｘ≦１）を用いることができる。ケイ素合金には、例えばＳｉと遷移金属Ｍとを含む合金（Ｍ−Ｓｉ合金）を用いることができる。例えば、Ｎｉ−Ｓｉ合金、Ｔｉ−Ｓｉ合金などを用いることが好ましい。また、Ｓｉを含む負極活物質は、単結晶、多結晶、非晶質のいずれでもよい。 Examples of the negative electrode active material containing Si that can be alloyed with lithium include silicon simple substance, silicon oxide, and silicon alloy. As the silicon oxide, for example, SiO x (0 <x <2, preferably 0.1 ≦ x ≦ 1) can be used. As the silicon alloy, for example, an alloy containing Si and a transition metal M (M-Si alloy) can be used. For example, it is preferable to use a Ni—Si alloy, a Ti—Si alloy, or the like. Further, the negative electrode active material containing Si may be any of single crystal, polycrystal, and amorphous.
負極活物質が、主にＳｉを含む第一の相（Ａ相）、および遷移金属のケイ化物を含む第二の相（Ｂ相）とからなり、第一の相および第二の相の少なくとも一方が、非晶質状態および低結晶状態の少なくとも一方の状態であるのが好ましい。高容量、かつサイクル寿命に優れた非水電解質二次電池が得られる。また、Ｂ相は遷移金属とケイ化物を含む相であることが好ましい。 The negative electrode active material mainly comprises a first phase containing Si (A phase) and a second phase containing a transition metal silicide (B phase), and at least one of the first phase and the second phase One is preferably in at least one of an amorphous state and a low crystalline state. A nonaqueous electrolyte secondary battery having a high capacity and excellent cycle life can be obtained. The B phase is preferably a phase containing a transition metal and a silicide.
Ａ相は、Ｌｉの吸蔵放出に寄与する相、すなわち電気化学的にＬｉと反応可能な相である。Ａ相の重量または体積あたりのＬｉ吸蔵放出量が多い点で、Ａ相はＳｉの単相であるのが好ましい。ただし、Ｓｉは電子伝導性に乏しいために、Ａ相の電子伝導性を改善するために、Ａ相中にリン、ホウ素、または遷移金属などの元素を添加してもよい。
ケイ化物を含むＢ相はＡ相との親和性が高く、特に充電時に体積膨張した場合でも結晶界面での割れが生じにくい。Ｂ相はＳｉを主体とするＡ相に比べて電子伝導性が高くかつ硬度も高い。そのため、活物質がＢ相を含むことにより、Ａ相における低い電子伝導性が改善され、かつ膨張時の応力が緩和されて活物質粒子の割れが抑制される。
The A phase is a phase that contributes to the occlusion and release of Li, that is, a phase that can electrochemically react with Li. The A phase is preferably a single Si phase in that the amount of Li occlusion / release per unit weight or volume of the A phase is large. However, since Si has poor electronic conductivity, elements such as phosphorus, boron, or transition metals may be added to the A phase in order to improve the electronic conductivity of the A phase.
The B phase containing silicide has a high affinity with the A phase, and cracking at the crystal interface is unlikely to occur even when the volume of the B phase expands during charging. The B phase has higher electron conductivity and higher hardness than the A phase mainly composed of Si. Therefore, when the active material contains the B phase, low electronic conductivity in the A phase is improved, and stress during expansion is relaxed, and cracking of the active material particles is suppressed.
Ｂ相は複数の相で構成されてもよい。例えば、Ｂ相は、ＭＳｉ2およびＭＳｉ（Ｍは遷移金属）のように、遷移金属Ｍとケイ素との組成比が異なる２相からなる。また、例えば、上記２相と、異なる遷移金属Ｍとのケイ化物の相と、を含む３相以上の相から構成されてもよい。遷移金属Ｍは、Ｔｉ、Ｚｒ、Ｎｉ、Ｃｕ、Ｆｅ、およびＭｏからなる群より選ばれる少なくとも１種が好ましい。上記遷移金属Ｍのケイ化物は、高い電子伝導度を有し、かつ高い強度を有する。これらの中でも、遷移金属ＭはＴｉがより好ましい。Ｂ相はＴｉＳｉ2を含むことが好ましい。 The B phase may be composed of a plurality of phases. For example, the B phase is composed of two phases having different composition ratios of the transition metal M and silicon, such as MSi 2 and MSi (M is a transition metal). Further, for example, it may be composed of three or more phases including the above two phases and a silicide phase of different transition metal M. The transition metal M is preferably at least one selected from the group consisting of Ti, Zr, Ni, Cu, Fe, and Mo. The transition metal M silicide has high electronic conductivity and high strength. Among these, the transition metal M is more preferably Ti. B phase preferably contains TiSi 2.
Ｓｉを含む負極活物質粒子が遷移金属を含むと、負極活物質粒子表面に存在する遷移金属は酸化され、負極活物質粒子表面に遷移金属の酸化物が形成される。遷移金属酸化物の表面には水酸基（−ＯＨ基）が存在するため、負極活物質とポリアクリル酸の結合が強くなり、ポリアクリル酸が優先して負極活物質と結合するため、バインダーにポリイミドを用いた場合でも電池の低温特性が低下しない。 When the negative electrode active material particle containing Si contains a transition metal, the transition metal present on the surface of the negative electrode active material particle is oxidized, and an oxide of the transition metal is formed on the surface of the negative electrode active material particle. Since there is a hydroxyl group (—OH group) on the surface of the transition metal oxide, the bond between the negative electrode active material and polyacrylic acid becomes stronger, and polyacrylic acid preferentially binds to the negative electrode active material. Even when is used, the low temperature characteristics of the battery do not deteriorate.
負極中の炭素材料には、例えば、黒鉛やカーボンブラックが用いられる。負極中の炭素材料の含有量は、特に限定されないが、負極活物質１００重量部あたり１．０〜５０重量部が好ましく、特に負極活物質１００重量部あたり１．０〜４０重量部がより好ましい。
本発明の負極の作製方法は、Ｓｉを含む活物質と、ポリアミド酸およびポリアクリル酸を含むバインダー原料溶液と、導電材として炭素材料とを混合した後、加熱・乾燥して負極合剤を得る工程（１）と、前記負極合剤を加圧成形してペレットを得た後、前記ペレットを加熱して、ポリアミド酸をイミド化させてポリイミドを得、バインダーとしてポリイミドおよびポリアクリル酸を含む負極を得る工程（２）と、を含む。
For example, graphite or carbon black is used as the carbon material in the negative electrode. The content of the carbon material in the negative electrode is not particularly limited, but is preferably 1.0 to 50 parts by weight per 100 parts by weight of the negative electrode active material, and more preferably 1.0 to 40 parts by weight per 100 parts by weight of the negative electrode active material. .
In the method for producing a negative electrode of the present invention, an active material containing Si, a binder raw material solution containing polyamic acid and polyacrylic acid, and a carbon material as a conductive material are mixed, and then heated and dried to obtain a negative electrode mixture. After the step (1) and the negative electrode mixture are pressure-molded to obtain pellets, the pellets are heated to imidize polyamic acid to obtain polyimide, and the negative electrode containing polyimide and polyacrylic acid as a binder (2).
バインダー原料溶液には、例えば、ポリアミド酸およびポリアクリル酸を含むＮ−メチル−２−ピロリドン（ＮＭＰ）溶液が用いられる。バインダー原料溶液において、ポリアミド酸の代わりにポリイミドを直接用いてもよいが、ポリイミドはＮＭＰ等の溶媒に溶けにくく、負極合剤中に均一に分散しにくい。これに対して上記バインダー原料溶液では、ポリイミドの前駆体であるポリアミド酸がＮＭＰ等の溶媒に溶解しやすい。このため、ポリアミド酸を負極合剤中に均一に分散させることができ、このポリアミド酸をイミド化させることにより、負極中にポリイミドを均一に分散させることができる。工程（１）では、例えば、負極合剤を真空下において６０℃で１２時間加熱・乾燥させる。工程（１）の加熱温度は、後述するイミド化反応を起こすための加熱温度よりも十分低いため、工程（１）ではイミド化反応は起こらない。 As the binder raw material solution, for example, an N-methyl-2-pyrrolidone (NMP) solution containing polyamic acid and polyacrylic acid is used. In the binder raw material solution, polyimide may be used directly instead of polyamic acid. However, polyimide is hardly dissolved in a solvent such as NMP and is not easily dispersed uniformly in the negative electrode mixture. On the other hand, in the binder raw material solution, polyamic acid which is a polyimide precursor is easily dissolved in a solvent such as NMP. For this reason, a polyamic acid can be uniformly disperse | distributed in a negative electrode mixture, and a polyimide can be disperse | distributed uniformly in a negative electrode by imidating this polyamic acid. In step (1), for example, the negative electrode mixture is heated and dried at 60 ° C. for 12 hours under vacuum. Since the heating temperature in the step (1) is sufficiently lower than the heating temperature for causing the imidation reaction described later, the imidization reaction does not occur in the step (1).
工程（２）の加熱処理により、ポリアミド酸がイミド化（脱水重合）してポリイミドが得られる。このポリイミドおよびポリアクリル酸が負極のバインダーとして機能する。熱処理としては、熱風、赤外線、遠赤外線、電子線を単独またはこれらを複数組み合わせて用いられる。 By the heat treatment in the step (2), the polyamic acid is imidized (dehydration polymerization) to obtain a polyimide. This polyimide and polyacrylic acid function as a binder for the negative electrode. As the heat treatment, hot air, infrared rays, far infrared rays, and electron beams are used alone or in combination.
ペレットの加熱温度は２００〜３００℃が好ましく、より好ましくは２００〜２５０℃である。ペレットを２００〜３００℃で加熱処理した場合、ポリアミド酸のイミド化が十分進行し、かつポリアクリル酸を分解させずに、負極作製時に添加した量のポリアクリル酸を負極内に残存させることができる。工程（２）におけるイミド化反応は２００℃以上で進行しやすい。また、加熱温度が３００℃を超えるとポリアクリル酸は分解しやすくなり、負極中のポリアクリル酸の残存量が少なくなると、Ｓｉを含む負極活物質にポリアクリル酸が優先的に結合し、負極活物質表面のポリイミドによる被覆を抑制する効果が小さくなり、負極の電子伝導性が低下し、電池の低温特性向上の効果が十分に得られない。イミド化による脱水重合により水分が発生するが、ペレットを２００〜３００℃で加熱しているため水分は除去される。このため、電池システム内部に水分が入り込むことはない。 The heating temperature of the pellet is preferably 200 to 300 ° C, more preferably 200 to 250 ° C. When the pellet is heat-treated at 200 to 300 ° C., the imidization of the polyamic acid proceeds sufficiently and the amount of polyacrylic acid added during the preparation of the negative electrode can be left in the negative electrode without decomposing the polyacrylic acid. it can. The imidization reaction in the step (2) tends to proceed at 200 ° C. or higher. In addition, when the heating temperature exceeds 300 ° C., polyacrylic acid is easily decomposed, and when the remaining amount of polyacrylic acid in the negative electrode decreases, polyacrylic acid is preferentially bonded to the negative electrode active material containing Si, and the negative electrode The effect of suppressing the coating of the active material surface with polyimide is reduced, the electron conductivity of the negative electrode is lowered, and the effect of improving the low temperature characteristics of the battery cannot be sufficiently obtained. Although moisture is generated by dehydration polymerization by imidization, the moisture is removed because the pellets are heated at 200 to 300 ° C. For this reason, moisture does not enter the battery system.
ポリアミド酸のイミド化率が８０％以上であることが好ましい。ポリアミド酸のイミド化反応が８０％未満であると、ポリイミドがバインダーとして十分機能しないため、サイクル特性が低下しやすい。ポリアミド酸のイミド化率は、例えば、工程（２）のペレットの加熱温度や加熱時間を調整することにより制御することができる。イミド化率は、赤外分光法（ＩＲ）を用いて求めることができる。 The imidation ratio of the polyamic acid is preferably 80% or more. When the imidization reaction of the polyamic acid is less than 80%, the polyimide does not function sufficiently as a binder, so that the cycle characteristics are likely to deteriorate. The imidation ratio of the polyamic acid can be controlled, for example, by adjusting the heating temperature and heating time of the pellet in the step (2). The imidization rate can be determined using infrared spectroscopy (IR).
負極合剤中のバインダーの含有量は、電池特性の観点から、負極活物質粒子同士の結着性が十分に維持される最小量が適切である。このような観点から、負極合剤中のポリアミド酸およびポリアクリル酸の含有量の合計は、負極活物質１００重量部あたり０．５〜３０重量部が好ましい。負極合剤中のポリアミド酸およびポリアクリル酸の含有量の合計が負極活物質１００重量部あたり０．５重量部未満であると、バインダーとしての効果が不十分となる。一方、負極合剤中のポリアミド酸とポリアクリル酸の含有量の合計が負極活物質１００重量部あたり３０．０重量部を超えると、バインダー量が過剰となり相対的に活物質量が減少するため、電池容量が低下する。 The minimum content with which the binding property between the negative electrode active material particles is sufficiently maintained is appropriate as the content of the binder in the negative electrode mixture from the viewpoint of battery characteristics. From such a viewpoint, the total content of polyamic acid and polyacrylic acid in the negative electrode mixture is preferably 0.5 to 30 parts by weight per 100 parts by weight of the negative electrode active material. When the total content of polyamic acid and polyacrylic acid in the negative electrode mixture is less than 0.5 parts by weight per 100 parts by weight of the negative electrode active material, the effect as a binder becomes insufficient. On the other hand, if the total content of polyamic acid and polyacrylic acid in the negative electrode mixture exceeds 30.0 parts by weight per 100 parts by weight of the negative electrode active material, the amount of binder becomes excessive and the amount of active material is relatively reduced. , Battery capacity decreases.
優れたサイクル特性および低温特性が得られる点で、負極合剤中のポリアミド酸含有量が、ポリアミド酸とポリアクリル酸の合計１００重量部あたり１０〜９５重量部であるのが好ましい。負極合剤中のポリアミド酸含有量が、ポリアミド酸とポリアクリル酸の合計１００重量部あたり１０．０重量部未満であると、得られるポリイミドの量が少なくなり、サイクル特性が低下する。負極合剤中のポリアクリル酸含有量がポリアミド酸およびポリアクリル酸の合計１００重量部あたり９５重量部を超えると、負極活物質と優先的に結合可能なポリアクリル酸量が不足し、ポリイミドが負極活物質を強固に覆うため電池の低温特性が低下しやすい。 In view of obtaining excellent cycle characteristics and low temperature characteristics, the polyamic acid content in the negative electrode mixture is preferably 10 to 95 parts by weight per 100 parts by weight of the total of polyamic acid and polyacrylic acid. When the polyamic acid content in the negative electrode mixture is less than 10.0 parts by weight per 100 parts by weight of the total of polyamic acid and polyacrylic acid, the amount of polyimide obtained is reduced, and the cycle characteristics are deteriorated. If the polyacrylic acid content in the negative electrode mixture exceeds 95 parts by weight per 100 parts by weight of the total of polyamic acid and polyacrylic acid, the amount of polyacrylic acid that can be preferentially bonded to the negative electrode active material is insufficient, Since the negative electrode active material is firmly covered, the low-temperature characteristics of the battery are likely to deteriorate.
本発明の非水電解質二次電池は、上記負極と、正極と、正極と負極との間に配されるセパレータと、非水電解質とを具備する。上記の負極を用いることにより、充放電サイクル特性、低温特性、および耐熱性に優れた高エネルギー密度の非水電解質二次電池が得られる。非水電解質二次電池の形状や大きさは特に限定されない。本発明の負極は、円筒型、角型など、種々の形状の非水電解質二次電池に適用できる。また、本発明の非水電解質二次電池では、上記のようにバインダーにフッ素を含む材料を用いないため、バインダーの熱分解により生成したフッ化水素が負極活物質と反応して電池が劣化することがない。 The nonaqueous electrolyte secondary battery of the present invention includes the above negative electrode, a positive electrode, a separator disposed between the positive electrode and the negative electrode, and a nonaqueous electrolyte. By using the negative electrode, a high energy density non-aqueous electrolyte secondary battery excellent in charge / discharge cycle characteristics, low temperature characteristics, and heat resistance can be obtained. The shape and size of the nonaqueous electrolyte secondary battery are not particularly limited. The negative electrode of the present invention can be applied to non-aqueous electrolyte secondary batteries having various shapes such as a cylindrical shape and a rectangular shape. Further, in the nonaqueous electrolyte secondary battery of the present invention, as described above, since a material containing fluorine is not used in the binder, hydrogen fluoride generated by thermal decomposition of the binder reacts with the negative electrode active material and the battery deteriorates. There is nothing.
正極は、例えば、正極活物質、バインダー、および導電材を含む正極合剤からなる。
正極活物質には、リチウムイオンの吸蔵・放出が可能なリチウム含有または非含有の化合物が用いられる。例えば、ＬｉxＣｏＯ2、ＬｉxＮｉＯ2、ＬｉxＭｎＯ2、ＬｉxＭｎ1+yＯ4、ＬｉxＣｏyＮｉ1-yＯ2、ＬｉxＣｏyＭ1-yＯz、ＬｉxＮｉ1-yＭyＯz、ＬｉxＭｎ2Ｏ4、ＬｉxＭｎ2-yＭyＯ4（Ｍ＝Ｎａ、Ｍｇ、Ｓｃ、Ｙ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｚｎ、Ａｌ、Ｃｒ、Ｐｂ、Ｓｂ、Ｂのうち少なくとも一種である）が挙げられる。上記において、ｘは０〜１．２、ｙは０〜０．９、ｚは２．０〜２．３である。また、上記ｘ値は、充放電により変化する。また、遷移金属カルコゲン化物、バナジウム酸化物およびそのリチウム化合物、ニオブ酸化物およびそのリチウム化合物、有機導電性物質を用いた共役系ポリマー、シェブレル相化合物等が用いられる。上記化合物を単独で用いてもよく、２種以上を組み合わせて用いてもよい。
A positive electrode consists of a positive electrode mixture containing a positive electrode active material, a binder, and a electrically conductive material, for example.
As the positive electrode active material, a lithium-containing or non-containing compound capable of inserting and extracting lithium ions is used. For example, Li x CoO 2, Li x NiO 2, Li x MnO 2, Li x Mn 1 + y O 4, Li x Co y Ni 1-y O 2, Li x Co y M 1-y O z, Li x Ni 1-y M y O z , Li x Mn 2 O 4, Li x Mn 2-y M y O 4 (M = Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al , Cr, Pb, Sb, and B). In the above, x is 0 to 1.2, y is 0 to 0.9, and z is 2.0 to 2.3. The x value changes due to charge / discharge. Further, transition metal chalcogenides, vanadium oxides and lithium compounds thereof, niobium oxides and lithium compounds thereof, conjugated polymers using organic conductive substances, chevrel phase compounds, and the like are used. The said compound may be used independently and may be used in combination of 2 or more type.
正極のバインダおよび導電材は、非水電解質二次電池で使用可能なものであればよく、特に限定されない。
セパレータには、例えば、優れたイオン透過性を有する微多孔性フィルムが用いられる。例えば、ガラス繊維シート、不織布、織布などが用いられる。
The binder and the conductive material of the positive electrode are not particularly limited as long as they can be used in the nonaqueous electrolyte secondary battery.
For the separator, for example, a microporous film having excellent ion permeability is used. For example, a glass fiber sheet, a nonwoven fabric, a woven fabric, etc. are used.
また、耐有機溶剤性と疎水性の観点から、セパレータの材料としては、ポリプロピレン、ポリエチレン、ポリフェニレンスルフイド、ポリエチレンテレフタレート、ポリアミド、ポリイミドなどが用いられる。これらを単独で用いてもよく、２種以上組み合わせて用いてもよい。また、通常は安価なポリプロピレンが用いられるが、電池に耐リフロー性を付与する場合には、この中でも熱変形温度が２３０℃以上のポリプロピレンスルフィド、ポリエチレンテレフタレート、ポリアミド、ポリイミドなどを用いることが好ましい。
セパレータの厚みは、例えば１０〜３００μｍである。また、セパレータの空孔率は、電子やイオンの透過性、セパレータの素材などに応じて適宜決めればよいが、一般的に３０〜８０％であることが望ましい。
Also, from the viewpoint of organic solvent resistance and hydrophobicity, polypropylene, polyethylene, polyphenylene sulfide, polyethylene terephthalate, polyamide, polyimide, and the like are used as the separator material. These may be used alone or in combination of two or more. In general, inexpensive polypropylene is used. However, in order to impart reflow resistance to the battery, it is preferable to use polypropylene sulfide, polyethylene terephthalate, polyamide, polyimide, or the like having a heat distortion temperature of 230 ° C. or higher.
The thickness of the separator is, for example, 10 to 300 μm. Further, the porosity of the separator may be appropriately determined according to the permeability of electrons and ions, the material of the separator, and the like, but generally 30 to 80% is desirable.
非水電解質には、例えば、リチウム塩を溶解させた非水溶媒が用いられる。
非水溶媒には、例えば、エチレンカーボネート（ＥＣ）、プロピレンカーボネート（ＰＣ）、ブチレンカーボネート（ＢＣ）、ビニレンカーボネート（ＶＣ）などの環状カーボネート類、ジメチルカーボネート（ＤＭＣ）、ジエチルカーボネート（ＤＥＣ）、エチルメチルカーボネート（ＥＭＣ）、ジプロピルカーボネート（ＤＰＣ）などの鎖状カーボネート類、ギ酸メチル、酢酸メチル、プロピオン酸メチル、プロピオン酸エチルなどの脂肪族カルボン酸エステル類、γ−ブチロラクトン等のγ−ラクトン類、１，２−ジメトキシエタン（ＤＭＥ）、１，２−ジエトキシエタン（ＤＥＥ）、エトキシメトキシエタン（ＥＭＥ）等の鎖状エーテル類、テトラヒドロフラン、２−メチルテトラヒドロフラン等の環状エーテル類、ジメチルスルホキシド、１，３−ジオキソラン、ホルムアミド、アセトアミド、ジメチルホルムアミド、ジオキソラン、アセトニトリル、プロピルニトリル、ニトロメタン、エチルモノグライム、リン酸トリエステル、トリメトキシメタン、ジオキソラン誘導体、スルホラン、メチルスルホラン、１，３−ジメチル−２−イミダゾリジノン、３−メチル−２−オキサゾリジノン、プロピレンカーボネート誘導体、テトラヒドロフラン誘導体、エチルエーテル、１，３−プロパンサルトン、アニソール、ジメチルスルホキシド、Ｎ−メチルピロリドン、ブチルジグライム、メチルテトラグライムなどの非プロトン性有機溶媒が挙げられ、これらを単独で用いてもよく、２種以上を組み合わせて用いてもよい。
For the nonaqueous electrolyte, for example, a nonaqueous solvent in which a lithium salt is dissolved is used.
Nonaqueous solvents include, for example, cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and vinylene carbonate (VC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl Chain carbonates such as methyl carbonate (EMC) and dipropyl carbonate (DPC), aliphatic carboxylic acid esters such as methyl formate, methyl acetate, methyl propionate and ethyl propionate, and γ-lactones such as γ-butyrolactone Chain ethers such as 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE) and ethoxymethoxyethane (EME), cyclic ethers such as tetrahydrofuran and 2-methyltetrahydrofuran, dimethylsulfoxide Sid, 1,3-dioxolane, formamide, acetamide, dimethylformamide, dioxolane, acetonitrile, propylnitrile, nitromethane, ethyl monoglyme, phosphoric acid triester, trimethoxymethane, dioxolane derivative, sulfolane, methylsulfolane, 1,3-dimethyl -2-imidazolidinone, 3-methyl-2-oxazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ethyl ether, 1,3-propane sultone, anisole, dimethyl sulfoxide, N-methylpyrrolidone, butyl diglyme, methyl tetraglyme Aprotic organic solvents such as these may be used, and these may be used alone or in combination of two or more.
また、上記のなかでも、耐リフロー性の観点から、常圧での沸点が２００℃以上のエチレンカーボネート、プロピレンカーボネート、スルホラン、ブチルジグライム、メチルテトラグライム、γ―ブチロラクトンを用いるのが好ましい。 Among these, from the viewpoint of reflow resistance, it is preferable to use ethylene carbonate, propylene carbonate, sulfolane, butyl diglyme, methyl tetraglyme, or γ-butyrolactone having a boiling point of 200 ° C. or higher at normal pressure.
上記リチウム塩には、例えばＬｉＣｌＯ4、ＬｉＢＦ4、ＬｉＰＦ6、ＬｉＡｌＣｌ4、ＬｉＳｂＦ6、ＬｉＳＣＮ、ＬｉＣＦ3ＳＯ3、ＬｉＣＦ3ＣＯ2、Ｌｉ（ＣＦ3ＳＯ2）2、ＬｉＡｓＦ6、ＬｉＢ10Ｃｌ10、低級脂肪族カルボン酸リチウム、ＬｉＣｌ、ＬｉＢｒ、ＬｉＩ、クロロボランリチウム、四フェニルホウ酸リチウム、ＬｉＮ（ＣＦ3ＳＯ2）2、ＬｉＮ（Ｃ2Ｆ5ＳＯ2）2等が挙げられ、これらを単独で用いてもよく２種以上を組み合わせて用いてもよい。また、ゲルなどの固体電解質を用いてもよい。非水電解質中のリチウム塩の濃度は、特に限定されないが、０．２〜２．０ｍｏｌ／Ｌが好ましく、特に、０．５〜１．５ｍｏｌ／Ｌがより好ましい。 Examples of the lithium salt include LiClO 4 , LiBF 4 , LiPF 6 , LiAlCl 4 , LiSbF 6 , LiSCN, LiCF 3 SO 3 , LiCF 3 CO 2 , Li (CF 3 SO 2 ) 2 , LiAsF 6 , LiB 10 Cl 10. , Lower aliphatic lithium carboxylate, LiCl, LiBr, LiI, lithium chloroborane, lithium tetraphenylborate, LiN (CF 3 SO 2 ) 2 , LiN (C 2 F 5 SO 2 ) 2 and the like. Or may be used in combination of two or more. Further, a solid electrolyte such as a gel may be used. The concentration of the lithium salt in the nonaqueous electrolyte is not particularly limited, but is preferably 0.2 to 2.0 mol / L, and more preferably 0.5 to 1.5 mol / L.
以下に、本発明を実施例に基づいて具体的に説明するが、本発明は以下の実施例に限定されるものではない。
《実施例１》
（１）負極活物質の作製
負極活物質粒子中のＡ相であるＳｉ相の割合が３０重量％となるように、Ｔｉ粉末（高純度化学（株）製、純度９９．９９％、粒径２０μｍ未満）およびＳｉ粉末（関東化学（株）製、純度９９．９９９％、粒径２０μｍ未満）を重量比３２．２：６７．８の割合で混合した。
EXAMPLES The present invention will be specifically described below based on examples, but the present invention is not limited to the following examples.
Example 1
(1) Production of negative electrode active material Ti powder (manufactured by High-Purity Chemical Co., Ltd., purity 99.99%, particle size so that the proportion of the Si phase as the A phase in the negative electrode active material particles is 30% by weight. Less than 20 μm) and Si powder (manufactured by Kanto Chemical Co., Inc., purity 99.999%, particle size less than 20 μm) were mixed at a weight ratio of 32.2: 67.8.
そして、混合粉を振動ミル容器に投入し、さらにステンレス製ボール（直径２ｃｍ）を、ミル容器の容量の７０体積％を占めるように投入した。容器内部を真空に引いた後、容器内が１気圧になるまで容器内部をＡｒ（日本酸素（株）製、純度９９．９９９％）で置換した。その後、６０Ｈｚの振動を加えながら６０時間メカニカルアロイングを行い、Ｔｉ―Ｓｉ合金を得た。
得られたＴｉ−Ｓｉ合金粉末についてＸ線回折測定を行った結果、合金粒子内にＳｉ単相およびＴｉＳｉ2相とが存在することが確かめられた。また、この合金材料を透過電子顕微鏡（ＴＥＭ）で観察した結果、非晶質または１０ｎｍ程度の結晶を有するＳｉ相と、１５〜２０ｎｍ程度の結晶を有するＴｉＳｉ2相の存在が確認された。
Then, the mixed powder was put into a vibration mill container, and further a stainless ball (diameter 2 cm) was added so as to occupy 70% by volume of the capacity of the mill container. After evacuating the inside of the container, the inside of the container was replaced with Ar (Nihon Oxygen Co., Ltd., purity 99.999%) until the inside of the container reached 1 atm. Thereafter, mechanical alloying was performed for 60 hours while applying a vibration of 60 Hz to obtain a Ti—Si alloy.
As a result of X-ray diffraction measurement of the obtained Ti—Si alloy powder, it was confirmed that Si single phase and TiSi 2 phase existed in the alloy particles. Further, as a result of observing this alloy material with a transmission electron microscope (TEM), it was confirmed that an Si phase having an amorphous or about 10 nm crystal and a TiSi 2 phase having about 15 to 20 nm crystal were present.
（２）バインダー原料溶液の作製
ポリイミドの前駆体であるポリアミド酸溶液（宇部興産（株）製、Ｕ−ワニスＡ、２０重量％ＮＭＰ（Ｎ−メチル−２−ピロリドン）溶液）に、ポリアクリル酸粉末（日本純薬（株）製、ジュリマーＡＣ−１０ＬＨＰ）を１０重量％溶かしてバインダー原料溶液を得た。
(2) Preparation of binder raw material solution Polyacrylic acid was added to polyamic acid solution (Ube Industries, U-Varnish A, 20 wt% NMP (N-methyl-2-pyrrolidone) solution), which is a polyimide precursor. 10% by weight of powder (manufactured by Nippon Pure Chemical Co., Ltd., Jurimer AC-10LHP) was dissolved to obtain a binder raw material solution.
（３）負極の作製
次に、上記で得られた負極活物質およびバインダー原料溶液、ならびに導電材として黒鉛粉末（日本黒鉛（株）製、ＳＰ−５０３０）を混合した。この混合物を真空下において６０℃で１２時間乾燥させて負極合剤を得た。この時、負極合剤中のＴｉ−Ｓｉ合金、黒鉛粉末、ポリアミド酸、およびポリアクリル酸の重量比は、１００：２０：５：５であった。
(3) Production of negative electrode Next, the negative electrode active material and the binder raw material solution obtained above, and graphite powder (SP-5030, manufactured by Nippon Graphite Co., Ltd.) were mixed as a conductive material. This mixture was dried under vacuum at 60 ° C. for 12 hours to obtain a negative electrode mixture. At this time, the weight ratio of the Ti—Si alloy, graphite powder, polyamic acid, and polyacrylic acid in the negative electrode mixture was 100: 20: 5: 5.
その後、負極合剤を加圧成形し、直径４．０ｍｍおよび厚さ０．３ｍｍの円板状負極ペレットを得た。この負極ペレットを２５０℃で１２時間加熱してペレット内部に存在するポリアミド酸をイミド化させて負極を得た。このとき、イミド化率は９８％であった。なお、イミド化率は、赤外分光法（ＩＲ）を用いて求めた。また、赤外分光法（ＩＲ）により、加熱した後も、負極作製時に添加した量のポリアクリル酸が負極中に残存していることが確かめられた。 Thereafter, the negative electrode mixture was pressure-molded to obtain a disc-shaped negative electrode pellet having a diameter of 4.0 mm and a thickness of 0.3 mm. This negative electrode pellet was heated at 250 ° C. for 12 hours to imidize the polyamic acid present inside the pellet to obtain a negative electrode. At this time, the imidation ratio was 98%. In addition, the imidation ratio was calculated | required using the infrared spectroscopy (IR). In addition, it was confirmed by infrared spectroscopy (IR) that the amount of polyacrylic acid added during the preparation of the negative electrode remained in the negative electrode even after heating.
（４）正極の作製
二酸化マンガンと水酸化リチウムをモル比２：１の割合で混合した後、空気中４００℃で１２時間焼成してマンガン酸リチウムを得た。正極活物質として上記で得られたマンガン酸リチウム粉末８８重量部と、導電材であるカーボンブラック６重量部と、バインダーであるフッ素樹脂を６重量部含む量の水性ディスパージョンとを混合した。この混合物を真空下において６０℃で１２時間乾燥させて正極合剤を得た。この正極合剤を加圧成形し、直径４．０ｍｍおよび厚さ１．１ｍｍの円板状正極ペレットを得た。この正極ペレットを２５０℃で１２時間加熱して正極を得た。
(4) Production of positive electrode Manganese dioxide and lithium hydroxide were mixed at a molar ratio of 2: 1 and then fired at 400 ° C. for 12 hours in air to obtain lithium manganate. 88 parts by weight of the lithium manganate powder obtained above as a positive electrode active material, 6 parts by weight of carbon black as a conductive material, and an aqueous dispersion containing 6 parts by weight of a fluororesin as a binder were mixed. This mixture was dried under vacuum at 60 ° C. for 12 hours to obtain a positive electrode mixture. This positive electrode mixture was pressure-molded to obtain a disc-shaped positive electrode pellet having a diameter of 4.0 mm and a thickness of 1.1 mm. This positive electrode pellet was heated at 250 ° C. for 12 hours to obtain a positive electrode.
（５）コイン型電池の作製
以下の手順で図１に示すコイン型電池を作製した。図１は、本発明のコイン型電池の縦断面図である。
まず、ステンレス鋼製の正極缶１１の内面に上記で得られた正極１２を配置し、正極１２上に多孔質ポリエチレンシートからなるセパレータ１３を配置した。次に電解液を正極缶１１内に注液した。電解液にはリチウム塩としてＬｉＮ（ＣＦ3ＳＯ2）2を１モル／Ｌ含む有機溶媒を用いた。有機溶媒には、ＰＣ、ＥＣ、およびＤＭＥの混合溶媒（体積比ＰＣ：ＥＣ：ＤＭＥ＝１：１：１）を用いた。
(5) Production of coin-type battery The coin-type battery shown in FIG. 1 was produced by the following procedure. FIG. 1 is a longitudinal sectional view of a coin-type battery of the present invention.
First, the
正極缶１１内のセパレータ１３上に、上記で得られた負極１４を配置した。ステンレス鋼製の負極缶１６の周縁部にポリプロピレン製のガスケット１５を装着したものを正極缶１１の開口部に配置した。正極缶１１の開口端部をガスケット１５を介して負極缶１６の周縁部にかしめて、正極缶１１の開口部を封口した。このとき、正極缶１１および負極缶１６と、ガスケット１５との密着箇所にピッチを塗布した。このようにして、直径６．８ｍｍおよび厚さ２．１ｍｍのコイン型電池を作製した。
なお、上記の負極１４は、電解液の存在下で負極活物質にリチウムを吸蔵させて電気化学的に負極活物質をリチウム合金化した状態で使用した。
On the
In addition, said
本実施例では、ガスケット材料にポリプロピレンを用いたが、これ以外にも、電解液に対する安定性および耐熱性の点から、ポリフェニレンスルフィド、ポリエーテルケトン、ポリアミド、ポリイミド、液晶ポリマーなどが用いられる。また、これらを単独で用いてもよく、２種以上を組み合わせて用いてもよい。また、上記ポリマーに無機繊維等のフィラーを添加してもよい。また、通常は安価なポリプロピレンが用いられるが、電池に耐リフロー性を付与する場合、熱変形温度が２３０℃以上であるポリフェニレンスルフィド、ポリエーテルケトン、ポリイミド、液晶ポリマーを用いることが好ましい。 In this embodiment, polypropylene was used as the gasket material. In addition, polyphenylene sulfide, polyether ketone, polyamide, polyimide, liquid crystal polymer, and the like are used from the viewpoints of stability to the electrolytic solution and heat resistance. Moreover, these may be used independently and may be used in combination of 2 or more type. Moreover, you may add fillers, such as an inorganic fiber, to the said polymer. In general, inexpensive polypropylene is used, but in order to impart reflow resistance to the battery, it is preferable to use polyphenylene sulfide, polyether ketone, polyimide, or liquid crystal polymer having a heat distortion temperature of 230 ° C. or higher.
本実施例では、電池の気密性を向上させるために、ガスケットの正極缶および負極缶との密着部分にシール材としてピッチを塗布したが、これ以外に、シール材に、アスファルトピッチ、ブチルゴム、フッ素系オイルなどを用いてもよい。シール材が透明の場合は着色して、塗布の有無を明確にすることが好ましい。また、ガスケットにシール材を塗布する代わりに、正極缶および負極缶のガスケットとの密着部分に予めシール材を塗布してもよい。 In this example, in order to improve the hermeticity of the battery, a pitch was applied as a sealing material to the close contact portion of the gasket with the positive electrode can and the negative electrode can, but in addition to this, asphalt pitch, butyl rubber, fluorine System oil or the like may be used. When the sealing material is transparent, it is preferable to color it to clarify the presence or absence of application. Further, instead of applying the sealing material to the gasket, the sealing material may be applied in advance to the contact portion between the positive electrode can and the negative electrode can.
《比較例１》
実施例１のバインダー原料溶液の代わりに、ポリアミド酸溶液（宇部興産（株）製、Ｕ−ワニスＡ、２０重量％ＮＭＰ溶液）を用い、負極合剤中のＴｉ−Ｓｉ合金、黒鉛、およびポリアミド酸の重量比を１００：２０：１０とした。これ以外は、実施例１と同様の方法によりコイン型電池を作製した。
<< Comparative Example 1 >>
Instead of the binder raw material solution of Example 1, a polyamic acid solution (Ube Industries, U-Varnish A, 20 wt% NMP solution) was used, and the Ti—Si alloy, graphite, and polyamide in the negative electrode mixture The weight ratio of the acid was 100: 20: 10. Except for this, a coin-type battery was produced in the same manner as in Example 1.
《比較例２》
実施例１のバインダー原料溶液の代わりに、ポリアクリル酸粉末（日本純薬（株）製、ジュリマーＡＣ−１０ＬＨＰ）を１０重量％溶かしたＮＭＰ溶液を用い、負極合剤中のＴｉ−Ｓｉ合金、黒鉛、およびポリアクリル酸の重量比を１００：２０：１０とした。これ以外は、実施例１と同様の方法によりコイン型電池を作製した。
<< Comparative Example 2 >>
Instead of the binder raw material solution of Example 1, an NMP solution in which 10% by weight of polyacrylic acid powder (manufactured by Nippon Pure Chemical Co., Ltd., Jurimer AC-10LHP) was used, a Ti—Si alloy in the negative electrode mixture, The weight ratio of graphite and polyacrylic acid was 100: 20: 10. Except for this, a coin-type battery was produced in the same manner as in Example 1.
《比較例３》
負極活物質としてＴｉ−Ｓｉ合金の代わりに黒鉛（日本黒鉛（株）製、ＳＰ−５０３０）を用い、導電材を用いずに、黒鉛と、ポリアミド酸と、ポリアクリル酸とを１００：５：５の割合で含む負極合剤を用いた以外は、実施例１と同様の方法によりコイン型電池を作製した。
<< Comparative Example 3 >>
As the negative electrode active material, graphite (SP-5030, manufactured by Nippon Graphite Co., Ltd.) was used instead of the Ti—Si alloy, and graphite, polyamic acid, and polyacrylic acid were used 100: 5: A coin-type battery was produced in the same manner as in Example 1 except that the negative electrode mixture contained at a ratio of 5 was used.
上記の実施例１および比較例１〜３の電池について以下の評価を行った。
（６）電池の充放電試験
上記で得られたコイン型電池の充放電サイクル試験を２０℃に設定した恒温槽中で以下のように行った。
電池電圧２．０〜３．３Ｖの範囲内において、０．０２ＣＡの定電流で充放電を５０サイクル行った。そして、２サイクル目の放電容量（以下、初期容量とする）に対する５０サイクル目の放電容量の割合をサイクル容量維持率とした。このサイクル容量維持率が１００に近いほどサイクル特性が優れていることを示す。
The batteries of Example 1 and Comparative Examples 1 to 3 were evaluated as follows.
(6) Battery charge / discharge test The charge / discharge cycle test of the coin-type battery obtained above was performed as follows in a thermostatic bath set at 20 ° C.
In the range of battery voltage 2.0-3.3V, charging / discharging was performed 50 cycles with the constant current of 0.02CA. The ratio of the discharge capacity at the 50th cycle to the discharge capacity at the second cycle (hereinafter referred to as initial capacity) was defined as the cycle capacity maintenance rate. The closer the cycle capacity retention rate is to 100, the better the cycle characteristics.
また、電池の低温特性として、−２０℃の恒温槽中で上記充放電サイクル試験を行った。２０℃における初期容量に対する−２０℃における初期容量の割合を求めて低温容量維持率とした。この低温容量維持率が１００に近いほど低温特性が優れていることを示す。 Moreover, the said charge / discharge cycle test was done in the -20 degreeC thermostat as a low temperature characteristic of a battery. The ratio of the initial capacity at −20 ° C. to the initial capacity at 20 ° C. was determined and used as the low temperature capacity retention rate. The closer this low temperature capacity retention rate is to 100, the better the low temperature characteristics.
（７）負極の耐熱性試験
各電池を充電した後、電池を分解してリチウムが吸蔵状態の負極を取り出し、この負極について示差走査熱量測定装置（理学電気（株）製 Thermo Plus DSC8230）を用いて熱分析測定（ＤＳＣ測定）を行った。なお、ＤＳＣ測定は、取り出した負極約５ｍｇをステンレス鋼製の試料容器（耐圧：５０気圧）に入れ、静止空気雰囲気中で昇温速度１０℃／分で室温から４００℃まで加熱した。
このとき、負極に帰属する発熱ピークが現れる温度を発熱ピーク温度とした。なお、このピーク温度が高いほど、耐熱性に優れていることを示す。
その評価結果を表１に示す。
(7) Heat resistance test of negative electrode After each battery is charged, the battery is disassembled and the negative electrode in which lithium is occluded is taken out. Using this negative electrode, a differential scanning calorimeter (Thermo Electric DSC8230 manufactured by Rigaku Corporation) is used. Thermal analysis measurement (DSC measurement) was performed. In the DSC measurement, about 5 mg of the taken-out negative electrode was placed in a stainless steel sample container (withstand pressure: 50 atm) and heated from room temperature to 400 ° C. at a temperature rising rate of 10 ° C./min in a still air atmosphere.
At this time, the temperature at which the exothermic peak attributed to the negative electrode appears was defined as the exothermic peak temperature. In addition, it shows that it is excellent in heat resistance, so that this peak temperature is high.
The evaluation results are shown in Table 1.
負極用バインダーにポリイミドおよびポリアクリル酸の混合物を用いた実施例１の電池では、負極バインダーにポリイミドを単独で用いた比較例１の電池に比べて、低温特性が大幅に改善された。これは、ポリアクリル酸が負極活物質と優先的に結合することによりポリイミドが負極活物質と強く結合して低温特性が低下することを抑制したためと考えられる。また、サイクル特性はポリイミドを単独で用いた比較例１と同等レベルまで向上した。 In the battery of Example 1 using a mixture of polyimide and polyacrylic acid as the negative electrode binder, the low temperature characteristics were significantly improved as compared with the battery of Comparative Example 1 using polyimide alone as the negative electrode binder. This is considered to be because polyacrylic acid preferentially bonds to the negative electrode active material, thereby suppressing the polyimide from strongly bonding to the negative electrode active material and lowering the low temperature characteristics. Further, the cycle characteristics were improved to the same level as in Comparative Example 1 in which polyimide was used alone.
負極活物質にＴｉ−Ｓｉ合金を用いた実施例１の電池では、負極活物質に黒鉛を用いた比較例３の電池に比べて、初期容量が増大した。また、実施例１の電池に用いられた負極は、比較例３の電池に用いられた負極に比べて優れた耐熱性を示した。これは、Ｔｉ−Ｓｉ合金にリチウムが挿入した場合に比べ、黒鉛にリチウムが挿入した場合のほうが反応性が大きいためと考えられる。Ｔｉ−Ｓｉ合金を負極活物質に用いる場合、導電材である黒鉛よりも優先的にＴｉ−Ｓｉ合金にリチウムが挿入・脱離をする。このように、黒鉛にリチウムが挿入脱離することがなく、Ｔｉ−Ｓｉ合金のみが活物質として電池反応に関与する。従って、黒鉛よりもＴｉ−Ｓｉ合金を負極活物質に用いたほうが負極の耐熱性は優れていると考えられる。 In the battery of Example 1 using the Ti—Si alloy as the negative electrode active material, the initial capacity increased compared to the battery of Comparative Example 3 using graphite as the negative electrode active material. Moreover, the negative electrode used for the battery of Example 1 showed superior heat resistance as compared with the negative electrode used for the battery of Comparative Example 3. This is thought to be because the reactivity is greater when lithium is inserted into the graphite than when lithium is inserted into the Ti—Si alloy. When a Ti—Si alloy is used as the negative electrode active material, lithium is inserted into and desorbed from the Ti—Si alloy preferentially over graphite as a conductive material. Thus, lithium does not insert into and desorb from graphite, and only the Ti—Si alloy is involved in the battery reaction as an active material. Therefore, it is considered that the heat resistance of the negative electrode is better when a Ti—Si alloy is used as the negative electrode active material than graphite.
表１より、バインダーの種類やバインダーの配合比により負極の熱分解に帰属する発熱ピークが現れる温度（表１中の発熱ピーク温度）が異なり、ポリイミドを含むバインダーを用いた場合、耐熱性に優れた負極が得られることがわかった。
以上のことから、負極において、活物質にＴｉ−Ｓｉ合金、バインダーにポリイミドおよびポリアクリル酸、ならびに導電材に炭素材料を用いることにより、低温特性、充放電サイクル特性、および耐熱性に優れた高容量の非水電解質二次電池が得られることがわかった。
From Table 1, the temperature (exothermic peak temperature in Table 1) at which the exothermic peak attributed to the thermal decomposition of the negative electrode varies depending on the type of binder and the blending ratio of the binder, and when using a binder containing polyimide, it has excellent heat resistance. It was found that a negative electrode was obtained.
From the above, in the negative electrode, by using a Ti—Si alloy as the active material, polyimide and polyacrylic acid as the binder, and a carbon material as the conductive material, it has excellent low temperature characteristics, charge / discharge cycle characteristics, and heat resistance. It was found that a non-aqueous electrolyte secondary battery with a capacity was obtained.
《実施例２〜４および参考例１》
本実施例および参考例では、負極バインダーにポリイミドおよびポリアクリル酸を用いる場合において、ポリイミドの前駆体であるポリアミド酸を含有する負極ペレットの加熱温度について検討した。
負極ペレットの加熱温度を表２に示す温度に変えた以外は、実施例１と同様の方法によりコイン型電池を作製し、評価した。その評価結果を実施例１の電池の結果とともに表２に示す。
<< Examples 2 to 4 and Reference Example 1 >>
In this example and reference example , when polyimide and polyacrylic acid were used for the negative electrode binder, the heating temperature of the negative electrode pellet containing polyamic acid which is a precursor of polyimide was examined.
A coin-type battery was produced and evaluated in the same manner as in Example 1 except that the heating temperature of the negative electrode pellet was changed to the temperature shown in Table 2. The evaluation results are shown in Table 2 together with the results of the battery of Example 1.
負極ペレットの加熱温度が１５０℃である実施例２の負極はイミド化率が低く、ポリアミド酸の大部分はポリイミドに変化していないため、この負極を用いた電池では、サイクル特性が低下した。
実施例１〜４の電池では、負極作製時に添加した量のポリアクリル酸がほぼ残存しており、優れた低温特性が得られた。
Since the negative electrode of Example 2 in which the heating temperature of the negative electrode pellet was 150 ° C. had a low imidization rate and most of the polyamic acid was not changed to polyimide, the cycle characteristics were deteriorated in the battery using this negative electrode.
In the batteries of Examples 1 to 4, the amount of polyacrylic acid added during the production of the negative electrode remained almost, and excellent low-temperature characteristics were obtained.
一方、参考例１の電池では、低温容量維持率が低下した。これは、熱処理温度が４００℃の参考例１の負極では、ポリアクリル酸の大部分が分解して、負極がポリアクリル酸を含むことによる低温特性の向上効果が小さくなったためと考えられる。なお、加熱後の負極中のポリアクリル酸量は赤外分光法（ＩＲ）により調べた。
特に、実施例１、３および４では、低温特性、サイクル特性、および耐熱性に優れた高容量の非水電解質二次電池が得られたことから、ポリアミド酸のイミド化率は８０％以上であり、負極ペレットの加熱温度は２００〜３００℃であるのが好ましい。
On the other hand, in the battery of Reference Example 1 , the low-temperature capacity maintenance rate decreased. This is presumably because, in the negative electrode of Reference Example 1 having a heat treatment temperature of 400 ° C., most of the polyacrylic acid was decomposed, and the effect of improving the low-temperature characteristics due to the negative electrode containing polyacrylic acid was reduced. The amount of polyacrylic acid in the negative electrode after heating was examined by infrared spectroscopy (IR).
In particular, in Examples 1, 3 and 4, since a high capacity non-aqueous electrolyte secondary battery excellent in low temperature characteristics, cycle characteristics and heat resistance was obtained, the imidization ratio of the polyamic acid was 80% or more. Yes, the heating temperature of the negative electrode pellet is preferably 200 to 300 ° C.
《実施例６〜１０》
本実施例では、バインダーにポリイミドおよびポリアクリル酸を用いた負極の作製時における負極合剤中のバインダー原料（ポリアミド酸およびポリアクリル酸）の含有量について検討した。
バインダー原料におけるポリアミド酸とポリアクリル酸の配合比は変えずに、負極合剤中の負極活物質１００重量部あたりのバインダー原料の含有量を、表３に示す量に種々に変えた以外は、実施例１と同様の条件でコイン型電池を作製し、評価した。
その評価結果を実施例１の評価結果とともに表３に示す。
<< Examples 6 to 10 >>
In this embodiment, the examined content of the binder material in the negative electrode mixture during preparation of the anode using the polyimide and polyacrylic acid binder (polyamide acids and poly A acrylic acid).
The content ratio of the binder raw material per 100 parts by weight of the negative electrode active material in the negative electrode mixture was variously changed to the amount shown in Table 3 without changing the blending ratio of the polyamic acid and the polyacrylic acid in the binder raw material. A coin-type battery was produced and evaluated under the same conditions as in Example 1.
The evaluation results are shown in Table 3 together with the evaluation results of Example 1.
負極合剤中のバインダー原料の含有量が負極活物質１００重量部あたり０．２重量部である実施例６の電池では、サイクル特性が低下した。これは、負極中のバインダー量が少なく、バインダーによる効果が小さくなったためと考えられる。
一方、負極合剤中のバインダー原料の含有量が負極活物質１００重量部あたり４０重量部である実施例１０の電池では、初期容量が低下した。これは、得られた負極中のバインダー量が過剰となり、相対的に負極活物質量が減少したためと考えられる。
実施例１および７〜９では、サイクル特性に優れた高容量の非水電解質二次電池が得られたことから、負極合剤中のバインダー原料の含有量は負極活物質１００重量部あたり０．５〜３０重量部が好ましい。
In the battery of Example 6 in which the content of the binder raw material in the negative electrode mixture was 0.2 parts by weight per 100 parts by weight of the negative electrode active material, the cycle characteristics deteriorated. This is presumably because the amount of binder in the negative electrode was small and the effect of the binder was reduced.
On the other hand, in the battery of Example 10 in which the content of the binder raw material in the negative electrode mixture was 40 parts by weight per 100 parts by weight of the negative electrode active material, the initial capacity was lowered. This is presumably because the amount of the binder in the obtained negative electrode was excessive and the amount of the negative electrode active material was relatively reduced.
In Examples 1 and 7 to 9, a high-capacity non-aqueous electrolyte secondary battery having excellent cycle characteristics was obtained. Therefore, the content of the binder raw material in the negative electrode mixture was 0.00 by weight per 100 parts by weight of the negative electrode active material. 5 to 30 parts by weight is preferred.
《実施例１１〜１４および比較例４》
負極作製時において、負極合剤中のバインダー原料の含有量は変えずに、負極合剤中におけるポリアミド酸のバインダー原料（ポリアミド酸およびポリアクリル酸）１００重量部あたりの含有量を表４に示す値に種々に変えた。これ以外は、実施例１と同様の方法によりコイン型電池を作製し、評価した。その評価結果を実施例１の結果とともに表４に示す。
<< Examples 11 to 14 and Comparative Example 4 >>
Table 4 shows the content per 100 parts by weight of the binder material (polyamic acid and polyacrylic acid) of the polyamic acid in the negative electrode mixture without changing the content of the binder raw material in the negative electrode mixture at the time of preparing the negative electrode. The value was changed variously. Except for this, a coin-type battery was prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4 together with the results of Example 1.
バインダー原料中のポリアクリル酸含有量がバインダー原料の合計１００重量部あたり５．０重量部の実施例１１の電池では、サイクル特性および低温特性が低下した。これは、ポリイミドの前駆体であるポリアミド酸の含有量が少なく、ポリイミドの効果が小さくなったためと考えられる。 In the battery of Example 11 in which the polyacrylic acid content in the binder raw material was 5.0 parts by weight per 100 parts by weight of the binder raw material, the cycle characteristics and the low temperature characteristics were deteriorated. This is presumably because the content of polyamic acid, which is a polyimide precursor, is small, and the effect of polyimide is reduced.
一方、バインダー原料中のポリアミド酸含有量がバインダー原料１００重量部あたり１００重量部である比較例４の電池では、低温特性が大幅に低下した。これは、Ｔｉ−Ｓｉ合金にポリイミドよりも優先的に結合するポリアクリル酸量が存在せず、ポリイミドがＴｉ−Ｓｉ合金と強く結合したためと考えられる。
実施例１および１２〜１４では、低温特性およびサイクル特性に優れた非水電解質二次電池が得られたことから、負極合剤中のポリアミド酸含有量はバインダー原料１００重量部あたり１０〜９５重量部が好ましい。
On the other hand, in the battery of Comparative Example 4 in which the polyamic acid content in the binder raw material was 100 parts by weight per 100 parts by weight of the binder raw material, the low-temperature characteristics were significantly lowered. This is presumably because there was no polyacrylic acid amount preferentially bonded to the Ti—Si alloy over the polyimide, and the polyimide was strongly bonded to the Ti—Si alloy.
In Examples 1 and 12 to 14, a non-aqueous electrolyte secondary battery excellent in low temperature characteristics and cycle characteristics was obtained. Therefore, the polyamic acid content in the negative electrode mixture was 10 to 95 weights per 100 parts by weight of the binder raw material. Part is preferred.
《実施例１５〜２２》
負極活物質粒子中のＡ相であるＳｉ相の割合が３０重量％となるように、遷移金属Ｍ（Ｍは、Ｚｒ、Ｎｉ、Ｃｕ、Ｆｅ、Ｍｏ、Ｃｏ、またはＭｎ）の粉末（高純度化学（株）製、純度９９．９９％、粒径２０μｍ未満）およびＳｉ粉末（関東化学（株）製、純度９９．９９９％、粒径２０μｍ未満）を混合した。遷移金属ＭとＳｉとの混合重量比は、それぞれＺｒ：Ｓｉ＝４３．３：５６．７、Ｎｉ：Ｓｉ＝３５．８：６４．２、Ｃｕ：Ｓｉ＝３７．２：６２．８、Ｆｅ：Ｓｉ＝３４．９：６５．１、Ｍｏ：Ｓｉ＝４４．２：５５．８、Ｃｏ：Ｓｉ＝３５．８：６４．２、Ｍｎ：Ｓｉ＝３４．６：６５．４とした。
<< Examples 15 to 22 >>
Powder (high purity) of transition metal M (M is Zr, Ni, Cu, Fe, Mo, Co, or Mn) so that the proportion of the Si phase that is the A phase in the negative electrode active material particles is 30% by weight. Chemical Co., Ltd., purity 99.99%, particle size less than 20 μm) and Si powder (Kanto Chemical Co., Ltd., purity 99.999%, particle size less than 20 μm) were mixed. The mixing weight ratio of the transition metal M and Si is Zr: Si = 43.3: 56.7, Ni: Si = 35.8: 64.2, Cu: Si = 37.2: 62.8, Fe, respectively. : Si = 34.9: 65.1, Mo: Si = 44.2: 55.8, Co: Si = 35.8: 64.2, and Mn: Si = 34.6: 65.4.
そして、混合粉を振動ミル容器に投入し、さらにステンレス製ボール（直径２ｃｍ）を、ミル容器の容量の７０体積％を占めるように投入した。容器内部を真空に引いた後、容器内が１気圧になるまで容器内部をＡｒ（日本酸素（株）製、純度９９．９９９％）で置換した。その後、６０Ｈｚの振動を加えながら６０時間メカニカルアロイングを行い、Ｍ―Ｓｉ合金を得た。
得られたＭ−Ｓｉ合金粉末についてＸ線回折測定を行った結果、合金粒子内にＳｉ単相およびＭＳｉ2相とが存在することが確かめられた。また、この合金材料を透過電子顕微鏡（ＴＥＭ）で観察した結果、非晶質または１０ｎｍ程度の結晶を有するＳｉ相と、１５〜２０ｎｍ程度の結晶を有するＭＳｉ2相の存在が確認された。
Then, the mixed powder was put into a vibration mill container, and further a stainless ball (diameter 2 cm) was added so as to occupy 70% by volume of the capacity of the mill container. After evacuating the inside of the container, the inside of the container was replaced with Ar (Nihon Oxygen Co., Ltd., purity 99.999%) until the inside of the container reached 1 atm. Thereafter, mechanical alloying was performed for 60 hours while applying 60 Hz vibration to obtain an M-Si alloy.
As a result of X-ray diffraction measurement of the obtained M-Si alloy powder, it was confirmed that Si single phase and MSi 2 phase exist in the alloy particles. Further, as a result of observing this alloy material with a transmission electron microscope (TEM), it was confirmed that an amorphous or Si phase having a crystal of about 10 nm and an MSi 2 phase having a crystal of about 15 to 20 nm were present.
そして、Ｔｉ−Ｓｉ合金粉末の代わりに、Ｍ−Ｓｉ合金粉末または上記Ｓｉ粉末を用いた以外は実施例１と同様の方法により負極合剤を得た。このとき、負極合剤中におけるＭ−Ｓｉ合金粉末または上記のＳｉ粉末、黒鉛粉末、ポリアミド酸、およびポリアクリル酸の重量比は、１００：２０：５．０：５．０とした。
上記以外は、実施例１と同様の方法によりコイン型電池を作製し、評価した。その評価結果を実施例１の結果とともに表５に示す。
A negative electrode mixture was obtained in the same manner as in Example 1 except that M-Si alloy powder or the Si powder was used instead of Ti-Si alloy powder. At this time, the weight ratio of the M-Si alloy powder or the above-mentioned Si powder, graphite powder, polyamic acid, and polyacrylic acid in the negative electrode mixture was 100: 20: 5.0: 5.0.
Except for the above, a coin-type battery was produced and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 5 together with the results of Example 1.
実施例１および１５〜２１の電池では、いずれも優れた低温特性が得られた。負極活物質表面には遷移金属の酸化物が形成される。この遷移金属酸化物の表面には水酸基（−ＯＨ基）が存在するため、カルボキシル基（−ＣＯＯＨ基）を有するポリアクリル酸とは水素結合を形成する。これにより、ポリアクリル酸がポリイミドより優先的にＭ−Ｓｉ合金と結合することができる。
また、負極活物質に遷移金属を含むＳｉ合金を用いた実施例１および１５〜２１の電池では、Ｓｉ単体を用いた実施例２２の電池に比べて、優れたサイクル特性および低温特性が得られた。
In the batteries of Example 1 and 15 to 21, excellent low temperature characteristics were obtained. A transition metal oxide is formed on the surface of the negative electrode active material. Since a hydroxyl group (—OH group) exists on the surface of the transition metal oxide, a hydrogen bond is formed with polyacrylic acid having a carboxyl group (—COOH group). Thereby, polyacrylic acid can couple | bond with an M-Si alloy preferentially rather than a polyimide.
In addition, in the batteries of Examples 1 and 15 to 21 using the Si alloy containing a transition metal as the negative electrode active material, excellent cycle characteristics and low temperature characteristics were obtained as compared with the battery of Example 22 using Si alone. It was.
上記の結果をもたらす原因は、次のように推定される。負極活物質がＳｉを含む場合のサイクル劣化の主要因は、充放電に伴う負極の集電性の低下である。すなわち、リチウムを吸蔵・放出する際に発生する活物質粒子の膨張・収縮によって、活物質粒子と集電体との間および活物質粒子間の接点が減少し、負極の電子伝導ネットワークが破壊されることにより、負極の抵抗が増大する。しかし、上記Ｓｉ合金を用いた場合では、Ｓｉ単体の場合と比べて、このような負極の集電性の低下が抑制されると考えられる。 The cause of the above result is estimated as follows. The main factor of cycle deterioration when the negative electrode active material contains Si is a decrease in the current collecting property of the negative electrode accompanying charge / discharge. In other words, the expansion / contraction of the active material particles generated when lithium is inserted / extracted reduces the contact between the active material particles and the current collector and between the active material particles, thereby destroying the electron conduction network of the negative electrode. As a result, the resistance of the negative electrode increases. However, in the case of using the Si alloy, it is considered that such a decrease in the current collecting property of the negative electrode is suppressed as compared with the case of using Si alone.
本発明の非水電解質二次電池は、高容量を有し、かつサイクル特性および低温特性に優れているため、携帯電話やデジタルカメラ等の各種電子機器の主電源およびメモリーバックアップ用電源として好適に用いられる。 The non-aqueous electrolyte secondary battery of the present invention has a high capacity and is excellent in cycle characteristics and low-temperature characteristics. Therefore, the non-aqueous electrolyte secondary battery is suitably used as a main power source and a memory backup power source for various electronic devices such as mobile phones and digital cameras. Used.
１１ 正極缶
１２ 正極
１３ セパレータ
１４ 負極
１５ ガスケット
１６ 負極缶
11 Positive electrode can 12
Claims (12)
前記バインダーは、ポリアミド酸およびポリアクリル酸を含む混合物を１５０〜３００℃で加熱することにより得られ、前記加熱により、前記ポリアミド酸は、イミド化されており、
前記導電材は、炭素材料である非水電解質二次電池用負極。 Including an active material containing Si, a binder, and a conductive material;
The binder is obtained by heating a mixture containing polyamic acid and polyacrylic acid at 150 to 300 ° C., by the heating, the polyamic acid, Ri Contact is imidized,
The conductive material is a negative electrode for a non-aqueous electrolyte secondary battery, which is a carbon material.
前記第一の相および前記第二の相の少なくとも一方は、非晶質状態および低結晶状態の少なくとも一方の状態である請求項１記載の非水電解質二次電池用負極。 The negative electrode active material comprises a first phase containing Si and a second phase containing a transition metal silicide,
2. The negative electrode for a nonaqueous electrolyte secondary battery according to claim 1, wherein at least one of the first phase and the second phase is at least one of an amorphous state and a low crystalline state.
前記負極合剤を加圧成形してペレットを得た後、前記ペレットを１５０〜３００℃で加熱して前記ポリアミド酸をイミド化させてポリイミドを得、バインダーとしてポリイミドおよびポリアクリル酸を含む負極を得る工程（２）と、を含む非水電解質二次電池用負極の作製方法。 (1) a step of obtaining a negative electrode mixture by heating and drying after mixing an active material containing Si, a binder raw material solution containing polyamic acid and polyacrylic acid, and a carbon material as a conductive material;
After the negative electrode mixture is pressure-molded to obtain a pellet, the pellet is heated at 150 to 300 ° C. to imidize the polyamic acid to obtain a polyimide, and a negative electrode containing polyimide and polyacrylic acid as a binder. A method for producing a negative electrode for a non-aqueous electrolyte secondary battery, comprising the step (2).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2006230809A JP5016276B2 (en) | 2005-08-29 | 2006-08-28 | Negative electrode for non-aqueous electrolyte secondary battery, method for producing the same, and non-aqueous electrolyte secondary battery |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2005247115 | 2005-08-29 | ||
| JP2005247115 | 2005-08-29 | ||
| JP2006230809A JP5016276B2 (en) | 2005-08-29 | 2006-08-28 | Negative electrode for non-aqueous electrolyte secondary battery, method for producing the same, and non-aqueous electrolyte secondary battery |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2007095670A JP2007095670A (en) | 2007-04-12 |
| JP5016276B2 true JP5016276B2 (en) | 2012-09-05 |
Family
ID=37981080
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2006230809A Active JP5016276B2 (en) | 2005-08-29 | 2006-08-28 | Negative electrode for non-aqueous electrolyte secondary battery, method for producing the same, and non-aqueous electrolyte secondary battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP5016276B2 (en) |
Families Citing this family (32)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5104025B2 (en) * | 2007-05-18 | 2012-12-19 | パナソニック株式会社 | Non-aqueous electrolyte battery |
| CN102007627B (en) | 2008-04-18 | 2014-04-09 | 株式会社丰田自动织机 | Negative electrode for lithium ion secondary battery, and method for production thereof |
| JP2010129363A (en) * | 2008-11-27 | 2010-06-10 | Jfe Chemical Corp | Negative electrode material for lithium ion secondary battery, negative electrode for lithium ion secondary battery, and lithium ion secondary battery |
| CN101740747B (en) * | 2008-11-27 | 2012-09-05 | 比亚迪股份有限公司 | Silicon cathode and lithium ion battery comprising same |
| JP2010218849A (en) * | 2009-03-16 | 2010-09-30 | Furukawa Electric Co Ltd:The | Anode for lithium-ion secondary battery, lithium-ion secondary battery using it, collector used for anode of lithium-ion secondary battery, and manufacturing method of anode for lithium-ion secondary battery |
| GB2470190B (en) * | 2009-05-11 | 2011-07-13 | Nexeon Ltd | A binder for lithium ion rechargeable battery cells |
| JP5431829B2 (en) * | 2009-08-17 | 2014-03-05 | 株式会社豊田自動織機 | Negative electrode for non-aqueous secondary battery and non-aqueous secondary battery |
| JP5748193B2 (en) | 2009-09-29 | 2015-07-15 | Ｎｅｃエナジーデバイス株式会社 | Secondary battery |
| JP5704633B2 (en) | 2009-09-29 | 2015-04-22 | Ｎｅｃエナジーデバイス株式会社 | Secondary battery |
| WO2011118387A1 (en) | 2010-03-26 | 2011-09-29 | Ｎｅｃエナジーデバイス株式会社 | Non-aqueous electrolyte secondary battery |
| US8999562B2 (en) | 2010-09-02 | 2015-04-07 | Nec Corporation | Secondary battery and secondary battery electrolytic solution for use in secondary battery |
| KR101532847B1 (en) | 2010-09-02 | 2015-06-30 | 닛본 덴끼 가부시끼가이샤 | Secondary battery and secondary battery electrolyte used therein |
| US9299985B2 (en) | 2010-10-14 | 2016-03-29 | Nec Corporation | Secondary battery and electrolyte solution for secondary battery to be used in same |
| JP5659994B2 (en) * | 2011-10-05 | 2015-01-28 | トヨタ自動車株式会社 | Negative electrode active material, lithium secondary battery, and method for producing negative electrode active material |
| US9680272B2 (en) * | 2012-02-17 | 2017-06-13 | Semiconductor Energy Laboratory Co., Ltd. | Method for forming negative electrode and method for manufacturing lithium secondary battery |
| JP5099394B1 (en) * | 2012-05-31 | 2012-12-19 | Ｊｓｒ株式会社 | Binder composition for electrode of power storage device |
| US20140004412A1 (en) * | 2012-06-29 | 2014-01-02 | Semiconductor Energy Laboratory Co., Ltd. | Secondary battery |
| JP6097643B2 (en) * | 2012-08-21 | 2017-03-15 | 積水化学工業株式会社 | Negative electrode material for lithium ion secondary battery, negative electrode for lithium ion secondary battery, and lithium ion secondary battery |
| JP2014103052A (en) * | 2012-11-22 | 2014-06-05 | Furukawa Electric Co Ltd:The | Negative electrode for nonaqueous electrolyte secondary battery and nonaqueous electrolyte secondary battery using the same and manufacturing method therefor |
| JP6286829B2 (en) * | 2013-01-28 | 2018-03-07 | 日本電気株式会社 | Lithium ion secondary battery |
| JP2015118871A (en) * | 2013-12-19 | 2015-06-25 | 凸版印刷株式会社 | Negative electrode for nonaqueous electrolyte secondary batteries, and nonaqueous electrolyte secondary battery |
| EP3121876B1 (en) | 2014-04-22 | 2020-11-11 | Toppan Printing Co., Ltd. | Electrode for non-aqueous electrolyte secondary battery, and non-aqueous electrolyte secondary battery |
| US11404694B2 (en) | 2015-09-17 | 2022-08-02 | Nec Corporation | Resin composition |
| JP6642081B2 (en) * | 2015-10-15 | 2020-02-05 | 株式会社豊田自動織機 | Polymer compound, binder for negative electrode, intermediate composition, negative electrode, power storage device, slurry for negative electrode, method for producing polymer compound, and method for producing negative electrode |
| JP6718784B2 (en) * | 2016-09-30 | 2020-07-08 | ビークルエナジージャパン株式会社 | Lithium ion secondary battery |
| WO2018211610A1 (en) * | 2017-05-17 | 2018-11-22 | 国立研究開発法人産業技術総合研究所 | Method for manufacturing negative electrode slurry for non-aqueous electrolyte secondary battery, and negative electrode slurry for non-aqueous electrolyte secondary battery |
| JP7140125B2 (en) * | 2017-08-24 | 2022-09-21 | 日本電気株式会社 | Negative electrode for lithium ion secondary battery and lithium ion secondary battery including the same |
| CN109423237B (en) | 2017-08-24 | 2021-08-27 | 三星电子株式会社 | Binder, electrode and lithium battery including the same, and method of preparing the binder |
| TWI818019B (en) * | 2018-05-17 | 2023-10-11 | 日商日本碍子股份有限公司 | Coin-type lithium secondary batteries and IoT devices |
| WO2019225717A1 (en) | 2018-05-24 | 2019-11-28 | 宇部興産株式会社 | Electrode binder resin composition, electrode mix paste, and electrode |
| JP7223544B2 (en) * | 2018-10-12 | 2023-02-16 | 日産自動車株式会社 | Negative electrode for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery using the same |
| JP6648854B2 (en) * | 2019-06-06 | 2020-02-14 | 宇部興産株式会社 | Binder resin composition for electrode, electrode mixture paste, and electrode |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3475001B2 (en) * | 1996-03-29 | 2003-12-08 | 三洋電機株式会社 | Manufacturing method of non-aqueous electrolyte battery |
| JP3703667B2 (en) * | 1998-12-24 | 2005-10-05 | 株式会社エスアイアイ・マイクロパーツ | Nonaqueous electrolyte secondary battery |
| JP4245933B2 (en) * | 2003-02-13 | 2009-04-02 | セイコーインスツル株式会社 | Non-aqueous electrolyte secondary battery for reflow soldering |
-
2006
- 2006-08-28 JP JP2006230809A patent/JP5016276B2/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| JP2007095670A (en) | 2007-04-12 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP5016276B2 (en) | Negative electrode for non-aqueous electrolyte secondary battery, method for producing the same, and non-aqueous electrolyte secondary battery | |
| US20070048609A1 (en) | Negative electrode for non-aqueous electrolyte secondary battery, producing method therefor, and non-aqueous electrolyte secondary battery | |
| US8808920B2 (en) | Positive electrode active material, positive electrode, nonaqueous electrolyte cell, and method of preparing positive electrode active material | |
| JP5030414B2 (en) | Nonaqueous electrolyte secondary battery | |
| JP5100024B2 (en) | Cathode active material for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery using the same | |
| JP2006210208A (en) | Nonaqueous electrolyte secondary battery | |
| JP5079291B2 (en) | Nonaqueous electrolyte secondary battery | |
| WO2012014998A1 (en) | Lithium secondary battery | |
| JP2004319105A (en) | Positive active material and nonaqueous electrolyte secondary battery using it | |
| JP2005235628A (en) | Positive electrode for lithium secondary batteries, and lithium secondary battery | |
| WO2018092359A1 (en) | Positive electrode active material for batteries, and battery | |
| JP2015053152A (en) | Nonaqueous electrolytic secondary battery | |
| JP2019178025A (en) | Lithium composite metal compound, positive electrode active material for lithium secondary battery, positive electrode for lithium secondary battery, lithium secondary battery, and method for producing lithium composite metal compound | |
| EP1439591B1 (en) | Lithium ion secondary battery | |
| KR20200041974A (en) | A positive electrode active material for a non-aqueous electrolyte secondary battery and a method for manufacturing the same, and a non-aqueous electrolyte secondary battery using the positive electrode active material | |
| JP2006244991A (en) | Non-aqueous secondary battery | |
| US9893356B2 (en) | Cathode active material for nonaqueous electrolyte secondary battery, nonaqueous electrolyte secondary battery, and method of producing cathode active material for nonaqueous electrolyte secondary battery | |
| CN107546365B (en) | Negative electrode material for nonaqueous electrolyte secondary battery and method for producing same | |
| JP4482953B2 (en) | Anode for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery using the same | |
| JP5546009B2 (en) | Cathode active material for lithium battery, method for producing the same, and lithium battery using the same | |
| JP3755506B2 (en) | Anode material for secondary battery and secondary battery using the same | |
| JP4441935B2 (en) | Negative electrode for non-aqueous electrolyte secondary battery and battery using the same | |
| WO2017047022A1 (en) | Positive electrode active material and battery | |
| JP2005317447A (en) | Battery | |
| JP2006156021A (en) | Nonaqueous electrolyte secondary battery |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20090723 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20120208 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20120216 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20120413 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20120510 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20120608 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20150615 Year of fee payment: 3 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 5016276 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 Free format text: JAPANESE INTERMEDIATE CODE: R150 |