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JP2014049288A - Negative electrode for nonaqueous electrolyte secondary battery, manufacturing method therefor and nonaqueous electrolyte secondary battery - Google Patents

Negative electrode for nonaqueous electrolyte secondary battery, manufacturing method therefor and nonaqueous electrolyte secondary battery Download PDF

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JP2014049288A
JP2014049288A JP2012191236A JP2012191236A JP2014049288A JP 2014049288 A JP2014049288 A JP 2014049288A JP 2012191236 A JP2012191236 A JP 2012191236A JP 2012191236 A JP2012191236 A JP 2012191236A JP 2014049288 A JP2014049288 A JP 2014049288A
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negative electrode
graphite
dispersant
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Taisuke Yamamoto
泰右 山本
Shun Nomura
峻 野村
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Sanyo Electric Co Ltd
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Sanyo Electric Co Ltd
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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    • Y02E60/10Energy storage using batteries

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Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery in which cycle characteristics can be enhanced by minimizing degradation in collection performance of SiOeven in the end of discharge.SOLUTION: A nonaqueous electrolyte secondary battery comprises: a negative electrode mixture layer including a negative electrode active material containing SiO(0.8≤x≤1.2) and graphite, a dispersant, and a binder; and a negative electrode collector having the negative electrode mixture layer formed on at least one surface. Dispersant coverage factor Rof SiOshown in equation (1), and dispersant coverage factor Rof graphite shown in equation (2) satisfy a relation R>R. Dispersant coverage factor Rof SiO=(mass of dispersant covering SiO)/(mass of SiO)...(1), Dispersant coverage factor Rof graphite=(mass of dispersant covering graphite)/(mass of graphite)...(2).

Description

本発明は、非水電解質二次電池用負極、その製造方法及び非水電解質二次電池に関するものである。   The present invention relates to a negative electrode for a nonaqueous electrolyte secondary battery, a method for producing the same, and a nonaqueous electrolyte secondary battery.

近年、携帯電話、ノートパソコン、スマートフォン等の移動情報端末の小型・軽量化が急速に進展しており、その駆動電源としての電池にはさらなる高容量化が要求されている。充放電に伴い、リチウムイオンが正、負極間を移動することにより充放電を行う非水電解質二次電池は、高いエネルギー密度を有し、高容量であるので、上記のような移動情報端末の駆動電源として広く利用されている。
上記移動情報端末は、動画再生機能、ゲーム機能といった機能の充実に伴って、更に消費電力が高まる傾向にあり、その駆動電源である非水電解質二次電池には長時間再生や出力改善等を目的として、更なる高容量化や充放電性能の向上が強く望まれるところである。
In recent years, mobile information terminals such as mobile phones, notebook computers, and smart phones have been rapidly reduced in size and weight, and batteries as driving power sources are required to have higher capacities. A non-aqueous electrolyte secondary battery that performs charge / discharge by moving lithium ions between the positive and negative electrodes along with charge / discharge has a high energy density and a high capacity. Widely used as a drive power source.
The mobile information terminal has a tendency to further increase power consumption with enhancement of functions such as a video playback function and a game function, and the non-aqueous electrolyte secondary battery, which is a driving power source thereof, can be played back for a long time or improved in output. As an object, further increase in capacity and improvement in charge / discharge performance are strongly desired.

ここで、上記非水電解質二次電池では、正極活物質としてコバルト酸リチウムを用い、負極活物質として黒鉛を用いるのが一般的であるが、これらの材料では更なる高容量化は困難な状況である。このため、負極においては、黒鉛に比べ比容量が高いケイ素酸化物と、黒鉛とを混合した負極活物質を用いて、電池の高容量化を図る提案がされている(下記特許文献1)。   Here, in the non-aqueous electrolyte secondary battery, it is common to use lithium cobaltate as the positive electrode active material and graphite as the negative electrode active material, but it is difficult to further increase the capacity with these materials. It is. For this reason, in the negative electrode, a proposal has been made to increase the capacity of the battery by using a negative electrode active material obtained by mixing silicon oxide having a higher specific capacity than graphite and graphite (Patent Document 1 below).

特開2011−233245号JP2011-233245A

しかしながら、上記特許文献1に記載の提案の如く、ケイ素酸化物と黒鉛とを混合した場合、ケイ素酸化物は黒鉛に比べて、充電時には大きく膨張する一方、放電時には大きく収縮する。したがって、放電末期にはケイ素酸化物が孤立し易くなって、ケイ素酸化物の集電性が低下する結果、サイクル特性が低下するという課題を有していた。   However, when silicon oxide and graphite are mixed as proposed in the above-mentioned Patent Document 1, silicon oxide expands greatly during charging as compared with graphite, but greatly contracts during discharging. Accordingly, the silicon oxide is easily isolated at the end of discharge, and the current collection performance of the silicon oxide is reduced. As a result, the cycle characteristics are deteriorated.

本発明の非水電解質二次電池は、SiO(0.8≦x≦1.2)と黒鉛とを含む負極活物質、分散剤、及び結着剤を備えた負極合剤層と、少なくとも一方の面に上記負極合剤層が形成された負極集電体と、を有し、下記(1)式で示されるSiOの分散剤被覆率RSiOと、下記(2)式で示される黒鉛の分散剤被覆率Rとの関係が、RSiO>Rを満たす。
SiOの分散剤被覆率RSiO=[SiOを被覆する分散剤質量]/[SiO質量]・・・(1)
黒鉛の分散剤被覆率R=[黒鉛を被覆する分散剤質量]/[黒鉛質量]・・・(2)
The nonaqueous electrolyte secondary battery of the present invention includes a negative electrode active material containing SiO x (0.8 ≦ x ≦ 1.2) and graphite, a dispersant, and a negative electrode mixture layer including a binder, A negative electrode current collector having the negative electrode mixture layer formed on one surface thereof, and a SiO X dispersant coating ratio R SiO expressed by the following formula (1), and expressed by the following formula (2): The relation with the dispersant coating ratio R C of graphite satisfies R SiO > RC .
Dispersants coverage R SiO of SiO X = [dispersants mass covering the SiO X] / [SiO X mass] (1)
Graphite dispersant coverage R C = [dispersant mass covering graphite] / [graphite mass] (2)

本発明によれば、放電末期であってもSiOの集電性が低下するのを抑制することができるといった優れた効果を奏する。 According to the present invention, there is an excellent effect that it is possible to suppress a decrease in the current collecting property of SiO X even at the end of discharge.

この発明に係る非水電解質二次電池等について、以下に説明する。尚、この発明における非水電解質二次電池等は、下記の形態に示したものに限定されず、その要旨を変更しない範囲において適宜変更して実施できるものである。   The nonaqueous electrolyte secondary battery and the like according to the present invention will be described below. In addition, the nonaqueous electrolyte secondary battery in this invention is not limited to what was shown to the following form, In the range which does not change the summary, it can change suitably and can implement.

[正極の作製]
正極活物質としてのコバルト酸リチウムに、導電剤としてのアセチレンブラック(電気化学工業製HS100)と、結着剤としてのポリフッ化ビニリデン(PVdF)と、分散媒としてのN−メチル−2−ピロリドン(NMP)とを、正極活物質と導電剤と結着剤との質量比が95.0:2.5:2.5の割合になるように加えた後に混練して、正極スラリーを調製した。次に、この正極スラリーを、アルミニウム箔から成る正極集電体の両面に塗布、乾燥した後、圧延ローラにより圧延し、正極集電タブを取り付けることで、正極集電体の両面に正極合剤層が形成された正極を作製した。なお、正極合剤層の充填密度は3.60g/cmとした。
[Production of positive electrode]
Lithium cobaltate as a positive electrode active material, acetylene black (HS100 manufactured by Denki Kagaku Kogyo) as a conductive agent, polyvinylidene fluoride (PVdF) as a binder, and N-methyl-2-pyrrolidone (as a dispersion medium) NMP) was added so that the mass ratio of the positive electrode active material, the conductive agent and the binder was 95.0: 2.5: 2.5, and then kneaded to prepare a positive electrode slurry. Next, the positive electrode slurry is applied to both surfaces of a positive electrode current collector made of aluminum foil, dried, rolled by a rolling roller, and a positive electrode current collector tab is attached to the positive electrode current collector on both surfaces. A positive electrode having a layer formed thereon was produced. The filling density of the positive electrode mixture layer was 3.60 g / cm 3 .

[負極の作製]
先ず、負極活物質としてのSiO(X=0.93、平均粒子径5μm)の表面に、SiOに対する割合が10質量%となるように炭素をコーティングした。尚、コーティングはCVD法で行った。次に、該炭素がコーティングされたSiOと、分散剤としてのCMC(ダイセルファインケム株式会社製#1380、エーテル化度は1.0〜1.5)と、結着剤としてのSBRとを、SiOとCMCとSBRとの質量比が96:3:1となるように水溶液中で攪拌し、SiOスラリーを調製した。尚、攪拌は、プライミクス製T.K.ハイビスミックスを用いた。
[Production of negative electrode]
First, carbon was coated on the surface of SiO X (X = 0.93, average particle diameter of 5 μm) as the negative electrode active material so that the ratio to SiO X was 10% by mass. The coating was performed by the CVD method. Next, SiO X coated with the carbon, CMC as a dispersant (# 1380 manufactured by Daicel FineChem, Inc., etherification degree: 1.0 to 1.5), and SBR as a binder, The mixture was stirred in an aqueous solution so that the mass ratio of SiO X , CMC, and SBR was 96: 3: 1 to prepare a SiO X slurry. In addition, stirring is performed by T. K. Hibismix was used.

これと並行して、負極活物質としての黒鉛とCMCとSBRとが、質量比で98:1:1となるように、水溶液中で攪拌し、黒鉛スラリーを調製した。尚、攪拌は、プライミクス製T.K.ハイビスミックスを用いた。
次に、上記SiOと上記黒鉛との質量比が10:90になるように、上記SiOスラリーと上記時黒鉛スラリーとを混合して、負極スラリーを調製した。次いで、この負極スラリーを、銅箔から成る負極集電体の両面に塗布し、更に大気中105℃で乾燥した後、圧延し、負極集電タブを取り付けることで、負極集電体の両面に負極合剤層が形成された負極を作製した。なお、負極合剤層の充填密度は1.60g/ccとした。
In parallel with this, graphite as a negative electrode active material, CMC, and SBR were stirred in an aqueous solution so as to have a mass ratio of 98: 1: 1 to prepare a graphite slurry. In addition, stirring is performed by T. K. Hibismix was used.
Next, the SiO X slurry and the hourly graphite slurry were mixed so that the mass ratio of the SiO X and the graphite was 10:90 to prepare a negative electrode slurry. Next, this negative electrode slurry is applied to both surfaces of a negative electrode current collector made of copper foil, further dried in the atmosphere at 105 ° C., rolled, and attached to both surfaces of the negative electrode current collector by attaching negative electrode current collector tabs. A negative electrode on which a negative electrode mixture layer was formed was produced. The packing density of the negative electrode mixture layer was 1.60 g / cc.

ここで、下記(1)式に示したSiOの分散剤被覆率RSiOは0.03であり、下記(2)式に示した黒鉛の分散剤被覆率Rは0.01であり、下記(3)式に示し負極全体の分散剤比率R(SiO+C)は0.012であった。
SiOの分散剤被覆率RSiO=[SiOを被覆する分散剤質量]/[SiO質量]・・・(1)
黒鉛の分散剤被覆率R=[黒鉛を被覆する分散剤質量]/[黒鉛質量]・・・(2)
負極全体の分散剤比率R(SiO+C)=[SiOを被覆する分散剤質量+黒鉛を被覆する分散剤質量]/[SiO質量+黒鉛質量]・・・(3)
Here, the dispersion ratio R SiO of SiO X shown in the following formula (1) is 0.03, and the dispersion coverage RC of graphite shown in the following formula (2) is 0.01, The dispersing agent ratio R (SiO + C) shown in the following formula (3) was 0.012.
Dispersants coverage R SiO of SiO X = [dispersants mass covering the SiO X] / [SiO X mass] (1)
Graphite dispersant coverage R C = [dispersant mass covering graphite] / [graphite mass] (2)
Dispersant ratio R (SiO + C) of the whole negative electrode = [dispersant mass covering SiO X + dispersant mass covering graphite] / [SiO X mass + graphite mass] (3)

[非水電解液の調製]
エチレンカーボネート(EC)とジエチルカーボネート(DEC)とを、3:7の体積比で混合した混合溶媒に対し、六フッ化リン酸リチウム(LiPF)を1.0モル/リットルの濃度になるように溶解させて非水電解液を調製した。
[Preparation of non-aqueous electrolyte]
To a mixed solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) are mixed at a volume ratio of 3: 7, lithium hexafluorophosphate (LiPF 6 ) has a concentration of 1.0 mol / liter. To prepare a non-aqueous electrolyte.

[電池の作製]
上記正極及び負極を、ポリエチレン微多孔膜からなるセパレータを介して対向させた後、正極タブと負極タブとは共に各電極内における最外周部に位置するよう、これらを渦巻き状に捲回して電極体を作製した。次に、この電極体を電池外装体であるアルミニウムラミネート内に配置し、105℃で2時間真空乾燥した。最後に、上記非水電解液を電池外装体内に注液した後、電池外装体の開口部を封止することにより電池を作製した。当該非水電解質二次電池を4.40Vまで充電し、2.75Vまで放電したときの放電容量は800mAhであった。
[Production of battery]
After the positive electrode and the negative electrode are opposed to each other through a separator made of a polyethylene microporous film, the positive electrode tab and the negative electrode tab are wound in a spiral shape so that both the positive electrode tab and the negative electrode tab are located at the outermost periphery in each electrode. The body was made. Next, this electrode body was placed in an aluminum laminate as a battery outer package and vacuum dried at 105 ° C. for 2 hours. Finally, after pouring the non-aqueous electrolyte into the battery outer package, a battery was fabricated by sealing the opening of the battery outer package. When the nonaqueous electrolyte secondary battery was charged to 4.40 V and discharged to 2.75 V, the discharge capacity was 800 mAh.

(実施例1)
上記発明を実施するための形態と同様にして電池を作製した。
このようにして作製した電池を、以下、電池A1と称する。
Example 1
A battery was produced in the same manner as in the embodiment for carrying out the invention.
The battery thus produced is hereinafter referred to as battery A1.

(実施例2)
SiOスラリーを調製する際、SiOとCMCとSBRとの質量比を94:5:1とした以外は、実施例1と同様に電池を作製した。
尚、上記(1)式に示したSiOの分散剤被覆率RSiOは0.05であり、上記(2)式に示した黒鉛の分散剤被覆率Rは0.01であり、上記(3)式に示し負極全体の分散剤比率R(SiO+C)は0.014であった。
このようにして作製した電池を、以下、電池A2と称する。
(Example 2)
A battery was fabricated in the same manner as in Example 1 except that when preparing the SiO X slurry, the mass ratio of SiO X , CMC, and SBR was 94: 5: 1.
The dispersion ratio R SiO of SiO X shown in the above formula (1) is 0.05, and the dispersion coverage R C of graphite shown in the above formula (2) is 0.01. The dispersant ratio R (SiO + C) of the whole negative electrode shown in the formula (3) was 0.014.
The battery thus produced is hereinafter referred to as battery A2.

(実施例3)
SiOスラリーを調製する際、SiOとCMCとSBRとの質量比を89:10:1とした以外は、実施例1と同様に電池を作製した。
尚、上記(1)式に示したSiOの分散剤被覆率RSiOは0.1であり、上記(2)式に示した黒鉛の分散剤被覆率Rは0.01であり、上記(3)式に示し負極全体の分散剤比率R(SiO+C)は0.019であった。
このようにして作製した電池を、以下、電池A3と称する。
(Example 3)
A battery was fabricated in the same manner as in Example 1 except that when preparing the SiO X slurry, the mass ratio of SiO X , CMC, and SBR was 89: 10: 1.
The dispersion ratio R SiO of SiO X shown in the above formula (1) is 0.1, and the dispersion coverage R C of graphite shown in the above formula (2) is 0.01. The dispersant ratio R (SiO + C) of the whole negative electrode shown in the formula (3) was 0.019.
The battery thus produced is hereinafter referred to as battery A3.

(比較例1)
SiOスラリーを調製する際、SiOとCMCとSBRとの質量比を98:1:1とした以外は、実施例1と同様に電池を作製した。
尚、上記(1)式に示したSiOの分散剤被覆率RSiOは0.01であり、上記(2)式に示した黒鉛の分散剤被覆率Rは0.01であり、上記(3)式に示し負極全体の分散剤比率R(SiO+C)は0.01であった。
このようにして作製した電池を、以下、電池Z1と称する。
(Comparative Example 1)
A battery was fabricated in the same manner as in Example 1 except that when preparing the SiO X slurry, the mass ratio of SiO X , CMC, and SBR was 98: 1: 1.
The dispersion ratio R SiO of SiO X shown in the above formula (1) is 0.01, and the dispersion coverage RC of graphite shown in the above formula (2) is 0.01. The dispersing agent ratio R (SiO + C) of the whole negative electrode shown in the formula (3) was 0.01.
The battery thus produced is hereinafter referred to as battery Z1.

(比較例2)
SiOスラリーを調製する際、SiOとCMCとSBRとの質量比を98:1.4:1とし、黒鉛スラリーを調製する際、黒鉛とCMCとSBRとの質量比を98:1.4:1.4とした以外は、実施例1と同様に電池を作製した。
尚、上記(1)式に示したSiOの分散剤被覆率RSiOは0.014であり、上記(2)式に示した黒鉛の分散剤被覆率Rは0.014であり、上記(3)式に示し負極全体の分散剤比率R(SiO+C)は0.014であった。
このようにして作製した電池を、以下、電池Z2と称する。
(Comparative Example 2)
When preparing the SiO X slurry, the mass ratio of SiO X , CMC, and SBR is 98: 1.4: 1. When preparing the graphite slurry, the mass ratio of graphite, CMC, and SBR is 98: 1.4. : A battery was fabricated in the same manner as in Example 1 except that the ratio was 1.4.
The dispersion ratio R SiO of SiO X shown in the above formula (1) is 0.014, and the dispersion coverage RC of graphite shown in the above formula (2) is 0.014. The dispersant ratio R (SiO + C) of the whole negative electrode shown in the formula (3) was 0.014.
The battery thus produced is hereinafter referred to as battery Z2.

(実験)
上記電池A1〜A3、Z1、Z2を、下記に示す条件で充放電を行って、サイクル特性(30サイクル後の容量維持率)を調べたので、その結果を表1に示す。
(Experiment)
The batteries A1 to A3, Z1, and Z2 were charged and discharged under the conditions shown below, and the cycle characteristics (capacity maintenance ratio after 30 cycles) were examined. The results are shown in Table 1.

・充放電条件
1.0It(800mA)電流で電池電圧が4.4Vとなるまで定電流充電を行った後、4.4Vの定電圧で電流値が(1/20)It(40mA)となるまで充電を行った。10分間休止した後、1.0It(800mA)電流で電池電圧が2.75Vとなるまで定電流放電を行った。このような条件(温度は25℃)で、充放電を30サイクル行い、下記(4)式に示す30サイクル後の容量維持率を算出した。
30サイクル後の容量維持率(%)=[30サイクル目の放電容量/1サイクル目の放電容量]×100・・・(4)
-Charging / discharging conditions After charging with constant current until the battery voltage reaches 4.4 V at 1.0 It (800 mA) current, the current value becomes (1/20) It (40 mA) at a constant voltage of 4.4 V. The battery was charged until After resting for 10 minutes, constant current discharge was performed until the battery voltage became 2.75 V at a current of 1.0 It (800 mA). Under such conditions (temperature is 25 ° C.), charge and discharge were performed for 30 cycles, and the capacity retention rate after 30 cycles shown in the following formula (4) was calculated.
Capacity retention rate after 30 cycles (%) = [Discharge capacity at 30th cycle / Discharge capacity at 1st cycle] × 100 (4)

Figure 2014049288
Figure 2014049288

上記表1から明らかなように、RSiO>Rとなっている電池A1〜A3は、RSiO=Rとなっている電池Z1、Z2と比べて、容量維持率が高くなっていることがわかる。これは、充放電時における膨張、収縮が黒鉛より大きいSiOの表面に分散剤を集中して配置することで、収縮時にSiOが孤立するのを抑制できる。したがって、充放電サイクルを繰り返してもSiOの集電性の低下を抑えることができ、その結果、サイクル特性が向上する。尚、R(SiO+C)を同じくする電池A2と電池Z2とを比較した場合、RSiO>Rとなっている電池A2は、RSiO=Rとなっている電池Z2と比べて、容量維持率が高くなっている.したがって、本発明の効果は、単に、分散剤の比率を高めることによって達成できるものではないことがわかる。
上記RSiOは、0.01≦RSiO≦0.15であることが望ましく、上記Rは、0.005≦R≦0.02であることが望ましく、更に、R(SiO+C)は、0.008≦R(SiO+C)≦0.1であることが望ましい。RSiO、R、及びR(SiO+C)が小さ過ぎると、分散剤の添加効果が十分に発揮されない一方、RSiO、R、及びR(SiO+C)が大き過ぎると、負極活物質表面の分散剤の量が多くなり過ぎて、リチウムイオンの受入れ性が低下するからである。
As is clear from Table 1 above, the batteries A1 to A3 in which R SiO > RC have a higher capacity maintenance ratio than the batteries Z1 and Z2 in which R SiO = RC . I understand. This can suppress the isolation of SiO X during shrinkage by concentrating and arranging the dispersing agent on the surface of SiO X that is larger than graphite in expansion and contraction during charge and discharge. Therefore, even if the charge / discharge cycle is repeated, it is possible to suppress a decrease in the current collecting property of SiO X , and as a result, cycle characteristics are improved. In addition, when comparing the battery A2 and the battery Z2 having the same R (SiO + C) , the battery A2 in which R SiO > RC is maintained in capacity compared to the battery Z2 in which R SiO = RC. The rate is high. Therefore, it can be seen that the effect of the present invention cannot be achieved simply by increasing the ratio of the dispersant.
The R SiO is preferably 0.01 ≦ R SiO ≦ 0.15, the R C is preferably 0.005 ≦ R C ≦ 0.02, and R (SiO + C) is It is desirable that 0.008 ≦ R (SiO + C) ≦ 0.1. If R 2 SiO 3 , R C , and R 2 (SiO + C) are too small, the effect of adding the dispersing agent is not sufficiently exhibited. On the other hand, if R 2 SiO 3 , R C , and R 2 (SiO + C) are too large, the surface of the negative electrode active material is dispersed. This is because the amount of the agent becomes too large and the acceptability of lithium ions is lowered.

(その他の事項)
(1)負極合剤層中におけるSiOの割合は0.5質量%以上25質量%以下であることが好ましく、特に、1.0質量%以上20質量%以下であることが望ましい。SiOの含有量が少な過ぎる場合、負極容量の増大を図れなくなることがある一方、SiOの含有量が多過ぎる場合、負極内膨張が大きくなるため、負極合剤層の剥離、負極集電体の変形等が生じ、サイクル特性が低下することがある。また、SiOの粒径は1〜20μmであることが好ましい。
(Other matters)
(1) The ratio of SiO X in the negative electrode mixture layer is preferably 0.5% by mass or more and 25% by mass or less, and particularly preferably 1.0% by mass or more and 20% by mass or less. If the content of SiO X is too small, the negative electrode capacity may not be increased. On the other hand, if the content of SiO X is too large, the expansion in the negative electrode increases, so that the negative electrode mixture layer is peeled off and the negative electrode current collector is collected. The body may be deformed and the cycle characteristics may be deteriorated. Further, it is preferred that the particle size of the SiO X is 1 to 20 [mu] m.

(2)本発明に用いるリチウム遷移金属複合酸化物としては、上記コバルト酸リチウムの他、Ni−Co−Mnのリチウム複合酸化物、Ni−Mn−Alのリチウム複合酸化物、Ni−Co−Alのリチウム複合酸化物等のニッケル或いはマンガンを含むリチウム複合酸化物、燐酸鉄リチウムLiFePOに代表されるオリビン型燐酸リチウム等でも良い。また、それらを単独で用いても混合して用いても良い。 (2) The lithium transition metal composite oxide used in the present invention includes the above lithium cobaltate, Ni—Co—Mn lithium composite oxide, Ni—Mn—Al lithium composite oxide, Ni—Co—Al A lithium composite oxide containing nickel or manganese, such as lithium composite oxide, or an olivine type lithium phosphate represented by lithium iron phosphate LiFePO 4 may be used. Moreover, you may use them individually or in mixture.

(3)本発明に用いる非水電解液の溶媒には、非水電解質二次電池に従来から用いられてきた溶媒や添加剤を同時に用いることができる。例えば、エチレンカーボネート、プロピレンカーボネート、ブチレンカーボネート、ビニレンカーボネート等の環状カーボネートや、ジメチルカーボネート、メチルエチルカーボネート、ジエチルカーボネート等の鎖状カーボネートや、酢酸メチル、酢酸エチル、酢酸プロピル、プロピオン酸メチル、プロピオン酸エチル、γ−ブチロラクトン等のエステルを含む化合物や、プロパンスルトン等のスルホン基を含む化合物や、1,2−ジメトキシエタン、1,2−ジエトキシエタン、テトラヒドロフラン、1,2−ジオキサン、1,4−ジオキサン、2−メチルテトラヒドロフラン等のエーテルを含む化合物や、ブチロニトリル、バレロニトリル、n−ヘプタンニトリル、スクシノニトリル、グルタルニトリル、アジポニトリル、ピメロニトリル、1,2,3−プロパントリカルボニトリル、1,3,5−ペンタントリカルボニトリル等のニトリルを含む化合物や、ジメチルホルムアミド等のアミドを含む化合物等を用いることができる。特に、これらのHの一部がFにより置換されている溶媒が好ましく用いられる。また、これらを単独又は複数組み合わせて使用することができ、これらに少量のニトリルを含む化合物やエーテルを含む化合物が組み合わされた溶媒が好ましい。 (3) As the solvent of the non-aqueous electrolyte used in the present invention, solvents and additives conventionally used in non-aqueous electrolyte secondary batteries can be used at the same time. For example, cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, chain carbonates such as dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, propionic acid Compounds containing esters such as ethyl and γ-butyrolactone, compounds containing sulfone groups such as propane sultone, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 1,2-dioxane, 1,4 -Compounds containing ethers such as dioxane and 2-methyltetrahydrofuran, butyronitrile, valeronitrile, n-heptanenitrile, succinonitrile, glutaronitrile, adiponitrile, pimeronite Le, 1,2,3-propanetriol-carbonitrile, 1,3,5-pentanetricarboxylic carbonitrile compounds containing nitrile such as nitrile or can be used compounds comprising an amide such as dimethylformamide. In particular, a solvent in which a part of these H is substituted with F is preferably used. Moreover, these can be used individually or in combination of several, The solvent which combined these with the compound containing a small amount of nitriles and the compound containing ether is preferable.

更に、上記の非水電解液に用いる溶質としても、従来から非水電解質二次電池において一般に使用されている公知のリチウム塩を用いることができる。そして、このようなリチウム塩としては、P、B、F、O、S、N、Clの中の一種類以上の元素を含むリチウム塩を用いることができ、具体的には、LiPF、LiBF、LiCFSO、LiN(FSO、LiN(CFSO、LiN(CSO、LiN(CFSO)(CSO)、LiC(CSO、LiAsF、LiClO等のリチウム塩及びこれらの混合物を用いることができる。特に、非水電解質二次電池における高率充放電特性や耐久性を高めるためには、LiPFを用いることが好ましい。 Furthermore, as a solute used in the non-aqueous electrolyte, a known lithium salt that is conventionally used in a non-aqueous electrolyte secondary battery can be used. As such a lithium salt, a lithium salt containing one or more elements among P, B, F, O, S, N, and Cl can be used. Specifically, LiPF 6 , LiBF 4 , LiCF 3 SO 3 , LiN (FSO 2 ) 2 , LiN (CF 3 SO 2 ) 2 , LiN (C 2 F 5 SO 2 ) 2 , LiN (CF 3 SO 2 ) (C 4 F 9 SO 2 ), Lithium salts such as LiC (C 2 F 5 SO 2 ) 3 , LiAsF 6 , LiClO 4 and mixtures thereof can be used. In particular, LiPF 6 is preferably used in order to enhance the high rate charge / discharge characteristics and durability of the nonaqueous electrolyte secondary battery.

また、溶質としては、オキサラト錯体をアニオンとするリチウム塩を用いることもできる。このオキサラト錯体をアニオンとするリチウム塩としては、LiBOB〔リチウム−ビスオキサレートボレート〕の他、中心原子にC 2−が配位したアニオンを有するリチウム塩、例えば、Li[M(C](式中、Mは遷移金属,周期律表のIIIb族,IVb族,Vb族から選択される元素、Rはハロゲン、アルキル基、ハロゲン置換アルキル基から選択される基、xは正の整数、yは0又は正の整数である。)で表わされるものを用いることができる。具体的には、Li[B(C)F]、Li[P(C)F]、Li[P(C]等がある。但し、高温環境下においても負極の表面に安定な被膜を形成するためには、LiBOBを用いることが最も好ましい。
尚、上記溶質は、単独で用いるのみならず、2種以上を混合して用いても良い。また、溶質の濃度は特に限定されないが、電解液1リットル当り0.8〜1.7モルであることが望ましい。更に、大電電流での放電を必要とする用途では、上記溶質の濃度が電解液1リットル当たり1.0〜1.6モルであることが望ましい。
As the solute, a lithium salt having an oxalato complex as an anion can also be used. As a lithium salt having this oxalato complex as an anion, in addition to LiBOB [lithium-bisoxalate borate], a lithium salt having an anion in which C 2 O 4 2− is coordinated to the central atom, for example, Li [M (C 2 O 4 ) x R y ] (wherein M is a transition metal, an element selected from groups IIIb, IVb, and Vb of the periodic table, R is selected from a halogen, an alkyl group, and a halogen-substituted alkyl group) Group, x is a positive integer, and y is 0 or a positive integer). Specifically, there are Li [B (C 2 O 4 ) F 2 ], Li [P (C 2 O 4 ) F 4 ], Li [P (C 2 O 4 ) 2 F 2 ], and the like. However, it is most preferable to use LiBOB in order to form a stable film on the surface of the negative electrode even in a high temperature environment.
In addition, the said solute may be used not only independently but in mixture of 2 or more types. Further, the concentration of the solute is not particularly limited, but is preferably 0.8 to 1.7 mol per liter of the electrolytic solution. Furthermore, in applications that require discharge with a large electric current, the concentration of the solute is desirably 1.0 to 1.6 mol per liter of the electrolyte.

(4)本発明に用いるセパレータとしては、従来から用いられてきたセパレータを用いることができる。具体的には、ポリエチレンからなるセパレータのみならず、ポリエチレン層の表面にポリプロピレンからなる層が形成されたものや、ポリエチレンのセパレータの表面にアラミド系の樹脂等の樹脂が塗布されたものを用いても良い。 (4) As a separator used for this invention, the separator conventionally used can be used. Specifically, not only a separator made of polyethylene, but also a material in which a layer made of polypropylene is formed on the surface of a polyethylene layer, or a material in which a resin such as an aramid resin is applied to the surface of a polyethylene separator is used. Also good.

(5)正極とセパレータとの界面、又は、負極とセパレータとの界面には、従来から用いられてきた無機物のフィラーからなる層を形成することができる。フィラーとしても、従来から用いられてきたチタン、アルミニウム、ケイ素、マグネシウム等を単独もしくは複数用いた酸化物やリン酸化合物、またその表面が水酸化物等で処理されているものを用いることができる。
上記フィラー層の形成は、正極、負極、或いはセパレータに、フィラー含有スラリーを直接塗布して形成する方法や、フィラーで形成したシートを、正極、負極、或いはセパレータに貼り付ける方法等を用いることができる。
(5) At the interface between the positive electrode and the separator or at the interface between the negative electrode and the separator, a layer made of an inorganic filler that has been conventionally used can be formed. As the filler, it is possible to use oxides or phosphate compounds using titanium, aluminum, silicon, magnesium, etc., which have been used conventionally, or those whose surfaces are treated with hydroxide or the like. .
The filler layer can be formed by directly applying a filler-containing slurry to a positive electrode, a negative electrode, or a separator, or by attaching a sheet formed of a filler to the positive electrode, the negative electrode, or the separator. it can.

本発明は、例えば携帯電話、ノートパソコン、スマートフォン等の移動情報端末の駆動電源や、電気自動車、HEVや電動工具といった高出力向けの駆動電源や、蓄電関連の電源に展開が期待できる。   The present invention can be expected to be deployed in, for example, driving power sources for mobile information terminals such as mobile phones, notebook computers, and smartphones, high power driving power sources such as electric vehicles, HEVs, and power tools, and power sources related to power storage.

Claims (6)

SiO(0.8≦x≦1.2)と黒鉛とを含む負極活物質、分散剤、及び結着剤を備えた負極合剤層と、
少なくとも一方の面に上記負極合剤層が形成された負極集電体と、
を有し、
下記(1)式で示されるSiOの分散剤被覆率RSiOと、下記(2)式で示される黒鉛の分散剤被覆率Rとの関係が、RSiO>Rを満たす非水電解質二次電池用負極。
SiOの分散剤被覆率RSiO=[SiOを被覆する分散剤質量]/[SiO質量]・・・(1)
黒鉛の分散剤被覆率R=[黒鉛を被覆する分散剤質量]/[黒鉛質量]・・・(2)
A negative electrode mixture layer comprising a negative electrode active material comprising SiO X (0.8 ≦ x ≦ 1.2) and graphite, a dispersant, and a binder;
A negative electrode current collector in which the negative electrode mixture layer is formed on at least one surface;
Have
Non-aqueous electrolyte in which the relationship between the dispersion ratio R SiO of SiO X represented by the following formula (1) and the dispersion coverage R C of graphite represented by the following formula (2) satisfies R SiO > RC Negative electrode for secondary battery.
Dispersants coverage R SiO of SiO X = [dispersants mass covering the SiO X] / [SiO X mass] (1)
Graphite dispersant coverage R C = [dispersant mass covering graphite] / [graphite mass] (2)
上記SiOの分散剤被覆率RSiOが0.01≦RSiO≦0.15である、請求項1に記載の非水電解質二次電池用負極。 The negative electrode for a nonaqueous electrolyte secondary battery according to claim 1, wherein the SiO X dispersant coating ratio R SiO is 0.01 ≦ R SiO ≦ 0.15. 上記黒鉛の分散剤被覆率Rが0.005≦R≦0.02である、請求項1又は2に記載の非水電解質二次電池用負極。 The dispersant coverage R C of the graphite is 0.005 ≦ R C ≦ 0.02, the non-aqueous electrolyte secondary battery negative electrode according to claim 1 or 2. 下記(3)式で示す負極全体の分散剤比率R(SiO+C)が0.008≦R(SiO+C)≦0.1である、請求項1〜3の何れか1項に記載の非水電解質二次電池用負極。
負極全体の分散剤比率R(SiO+C)=[SiOを被覆する分散剤質量+黒鉛を被覆する分散剤質量]/[SiO質量+黒鉛質量]・・・(3)
The non-aqueous electrolyte 2 according to any one of claims 1 to 3, wherein a dispersion ratio R (SiO + C) of the whole negative electrode represented by the following formula (3) is 0.008 ≦ R (SiO + C) ≦ 0.1. Negative electrode for secondary battery.
Dispersant ratio R (SiO + C) of the whole negative electrode = [dispersant mass covering SiO X + dispersant mass covering graphite] / [SiO X mass + graphite mass] (3)
負極活物質であるSiO(0.8≦x≦1.2)、分散剤、及び結着剤を混合して、SiOスラリーを調製するステップと、
負極活物質である黒鉛、分散剤、及び結着剤を混合して、黒鉛スラリーを調製するステップと、
上記SiOスラリーと上記黒鉛スラリーとを混合して、負極スラリーを調製するステップと、
負極集電体の少なくとも一方の面に上記負極スラリーを塗布して、負極集電体の少なくとも一方の面に負極合剤層を形成するステップと、
を備え、
上記SiOスラリーにおけるSiOの質量に対する分散剤の質量の比率が、上記黒鉛スラリーにおける黒鉛の質量に対する分散剤の質量の比率よりも高くなっている非水電解質二次電池用負極の製造方法。
Mixing a negative electrode active material SiO X (0.8 ≦ x ≦ 1.2), a dispersant, and a binder to prepare a SiO X slurry;
Mixing a negative electrode active material graphite, a dispersant, and a binder to prepare a graphite slurry;
Mixing the SiO X slurry and the graphite slurry to prepare a negative electrode slurry;
Applying the negative electrode slurry to at least one surface of the negative electrode current collector to form a negative electrode mixture layer on at least one surface of the negative electrode current collector;
With
The manufacturing method of the negative electrode for nonaqueous electrolyte secondary batteries in which the ratio of the mass of the dispersant to the mass of SiO X in the SiO X slurry is higher than the ratio of the mass of the dispersant to the mass of graphite in the graphite slurry.
上記請求項1〜4の何れか1項に記載の負極と、
正極集電体の少なくとも一方の面に正極合剤層が形成された正極と、
上記正極と上記負極の間に配置されたセパレータと、
非水電解液と、
を備える非水電解質二次電池。
The negative electrode according to any one of claims 1 to 4, and
A positive electrode having a positive electrode mixture layer formed on at least one surface of the positive electrode current collector;
A separator disposed between the positive electrode and the negative electrode;
A non-aqueous electrolyte,
A non-aqueous electrolyte secondary battery.
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109037636A (en) * 2018-08-03 2018-12-18 深圳市斯诺实业发展有限公司 A kind of preparation method of SiO/ carbon graphite composite negative pole material
JP2019036416A (en) * 2017-08-10 2019-03-07 トヨタ自動車株式会社 Method of manufacturing non-aqueous electrolyte secondary battery
CN113097447A (en) * 2019-12-23 2021-07-09 松下电器产业株式会社 Negative electrode for nonaqueous electrolyte secondary battery and nonaqueous electrolyte secondary battery

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2019036416A (en) * 2017-08-10 2019-03-07 トヨタ自動車株式会社 Method of manufacturing non-aqueous electrolyte secondary battery
CN109037636A (en) * 2018-08-03 2018-12-18 深圳市斯诺实业发展有限公司 A kind of preparation method of SiO/ carbon graphite composite negative pole material
CN113097447A (en) * 2019-12-23 2021-07-09 松下电器产业株式会社 Negative electrode for nonaqueous electrolyte secondary battery and nonaqueous electrolyte secondary battery

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