JP2007273257A - Nonaqueous secondary battery and method of charging same - Google Patents
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Abstract
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本発明は、非水電解質二次電池及びそれに用いる非水電解質に関し、より詳しくは、高電位となるまで正極を充電して使用する非水電解質二次電池の過充電安全性及び高率放電特性を向上することに関する。 The present invention relates to a nonaqueous electrolyte secondary battery and a nonaqueous electrolyte used therefor, and more specifically, overcharge safety and high rate discharge characteristics of a nonaqueous electrolyte secondary battery used by charging a positive electrode until a high potential is reached. Related to improving.
今日、携帯電話、ノートパソコン、ＰＤＡ等の移動情報端末の高機能化・小型化および軽量化が急速に進展している。これらの端末の駆動電源として、高いエネルギー密度を有し、高容量であるリチウムイオン二次電池に代表される非水電解質二次電池が広く利用されている。近年、これらの機器の一層の高機能化に伴い、電池の更なる高容量化や、高率放電特性の向上の要望が高まっている。 Today, mobile information terminals such as mobile phones, notebook computers, PDAs, and the like are rapidly increasing in functionality, size, and weight. As a driving power source for these terminals, non-aqueous electrolyte secondary batteries represented by lithium ion secondary batteries having high energy density and high capacity are widely used. In recent years, with the further enhancement of functionality of these devices, there is an increasing demand for further increase in battery capacity and improvement of high rate discharge characteristics.
このため、正極を４．４〜５．１Ｖの高い電位となるまで充電して使用することにより、正極活物質の利用効率を高めて、高容量化を図る技術が提案されている。しかし、正極を高い電位となるまで充電して使用すると、正極活物質の安定性が低下し、且つ安全性が低下するとともに、高温保存時に正極と非水電解質とが反応することによりガスが発生し、電池が大きく膨れてしまうという問題がある。 For this reason, the technique which raises the utilization efficiency of a positive electrode active material and raises a capacity | capacitance by charging and using a positive electrode until it becomes a high potential of 4.4-5.1V is proposed. However, if the positive electrode is charged to a high potential and used, the stability of the positive electrode active material decreases and the safety decreases, and gas is generated due to the reaction between the positive electrode and the nonaqueous electrolyte during high temperature storage. However, there is a problem that the battery swells greatly.
ところで、過充電により電池が異常状態になることを防止するために、非水電解質にビフェニル（ＢＰ）やシクロヘキシルベンゼン（ＣＨＢ）等を添加する技術が提案されている。 By the way, in order to prevent the battery from becoming abnormal due to overcharge, a technique of adding biphenyl (BP), cyclohexylbenzene (CHB) or the like to the nonaqueous electrolyte has been proposed.
しかし、ＢＰやＣＨＢ等は、正極を高電位となるまで充電して使用する場合には、充放電サイクルによってこれらの化合物が分解して、電池に悪影響を及ぼす副反応をひき起こすという問題があった。 However, when BP, CHB, etc. are used with the positive electrode charged to a high potential, there is a problem that these compounds are decomposed by the charge / discharge cycle and cause side reactions that adversely affect the battery. It was.
ここで、非水電解質二次電池に関する技術として、下記特許文献１〜３が提案されている。 Here, the following patent documents 1 to 3 have been proposed as techniques relating to the non-aqueous electrolyte secondary battery.
特許文献１にかかる技術は、非水電解質に酢酸リチウムや安息香酸リチウム等を含有させる技術である。この技術によると、過充電時に発生したガスをこれらの化合物がトラップすることにより、安全性に優れた非水電解質二次電池が得られるとされる。 The technology according to Patent Document 1 is a technology in which a nonaqueous electrolyte contains lithium acetate, lithium benzoate, or the like. According to this technology, it is said that a nonaqueous electrolyte secondary battery excellent in safety can be obtained by trapping the gas generated during overcharge by these compounds.
特許文献２にかかる技術は、所定圧力よりも高い電池内圧となった場合に開放作動する弁機構を有する非水電解質二次電池の非水電解質に、酢酸リチウムや安息香酸リチウム等を含有させる技術である。この技術によると、電池温度上昇等による電池の著しい破壊を抑制できるとされる。 The technique according to Patent Document 2 is a technique in which lithium acetate, lithium benzoate, or the like is contained in a nonaqueous electrolyte of a nonaqueous electrolyte secondary battery having a valve mechanism that opens when a battery internal pressure higher than a predetermined pressure is reached. It is. According to this technique, it is said that the remarkable destruction of the battery due to the battery temperature rise or the like can be suppressed.
特許文献３にかかる技術は、非水電解質に酢酸ナトリウムや酢酸カリウム等を含有させる技術である。この技術によると高温保存特性に優れた非水電解質二次電池が得られるとされる。 The technique according to Patent Document 3 is a technique in which sodium acetate, potassium acetate, or the like is contained in a nonaqueous electrolyte. According to this technique, it is said that a nonaqueous electrolyte secondary battery having excellent high-temperature storage characteristics can be obtained.
しかしながら、上記各技術は、正極を高い電位となるまで充電して使用することについては考慮されていない。 However, the above-mentioned technologies do not take into account charging and using the positive electrode until it reaches a high potential.
本発明は、上記に鑑みなされたものであって、正極を高電位となるまで充電して使用した場合においても高率放電特性が高く、且つ過充電安全性に優れた非水電解質二次電池を提供することを目的とする。 The present invention has been made in view of the above, and is a non-aqueous electrolyte secondary battery that has high rate discharge characteristics and excellent overcharge safety even when the positive electrode is charged to a high potential and used. The purpose is to provide.
上記課題を解決するための第１の本発明は、正極活物質を有する正極と、負極活物質を有する負極と、非水溶媒と電解質塩とを有する非水電解質と、を備えた非水電解質二次電池において、前記正極の電位がリチウム基準で４．４〜５．１Ｖであり、前記非水電解質は更に、プロピレンカーボネートに飽和溶解させた液の電気伝導度が、２５℃において０．３ｍＳ×ｃｍ−１以下であるリチウム塩と、酸化分解電位がリチウム基準で前記正極の電位よりも０．３Ｖ以上高い化合物と、を有することを特徴とする。 A first aspect of the present invention for solving the above problem is a nonaqueous electrolyte comprising a positive electrode having a positive electrode active material, a negative electrode having a negative electrode active material, and a nonaqueous electrolyte having a nonaqueous solvent and an electrolyte salt. In the secondary battery, the positive electrode has a potential of 4.4 to 5.1 V with respect to lithium, and the nonaqueous electrolyte further has a conductivity of 0.3 mS at 25 ° C. at 25 ° C. It is characterized by having a lithium salt that is × cm −1 or less and a compound having an oxidative decomposition potential that is 0.3 V or more higher than the potential of the positive electrode on the basis of lithium.
通常、充放電を行うと、非水電解質内でリチウムイオンの濃度分布が不均一となるが、上記低電気伝導度のリチウム塩は、リチウムイオン濃度が低くなっている部分で乖離してリチウムイオンを生じさせ、リチウムイオンの濃度分布の不均一を緩衝させるように作用する。このため、正極全体が均一に充放電される。 Normally, when charge / discharge is performed, the concentration distribution of lithium ions in the non-aqueous electrolyte becomes non-uniform, but the lithium salt with low electrical conductivity is separated from the lithium ion concentration at the portion where the lithium ion concentration is low. And acts to buffer non-uniformity of the lithium ion concentration distribution. For this reason, the whole positive electrode is charged / discharged uniformly.
過充電時や高率放電時には、特にリチウムイオン濃度分布の不均一が生じやすいが、上記リチウム塩を含ませることにより、局所的な過充電や過放電が生じにくくなる。これにより、正極全体としての電位のムラを０．３Ｖ未満に抑制できる。また、高率放電時においてもスムースに放電反応が進行するので、高率放電特性を飛躍的に高めることができる During overcharge or high rate discharge, in particular, the lithium ion concentration distribution is likely to be non-uniform, but by including the lithium salt, local overcharge and overdischarge are less likely to occur. Thereby, the nonuniformity of the potential as the whole positive electrode can be suppressed to less than 0.3V. Also, since the discharge reaction proceeds smoothly even during high rate discharge, the high rate discharge characteristics can be dramatically improved.
上記構成では、さらに酸化分解電位がリチウム基準で正極の電位よりも０．３Ｖ以上高い化合物を備えている。この化合物は、上記リチウム塩と併用して正極電位のムラを低くすることにより、高電位となるまで充電して使用する充放電サイクルでは酸化分解することがない。この一方、過充電時には、正極とこの化合物とが反応して、電池が異常に至る前に速やかに電池を安全状態に移行させる。よって、電池に悪影響を及ぼすことなく過充電安全性が飛躍的に向上する。 In the above configuration, a compound having an oxidative decomposition potential higher by 0.3 V or more than the potential of the positive electrode with respect to lithium is provided. This compound is used in combination with the lithium salt to reduce the unevenness of the positive electrode potential, so that it is not oxidatively decomposed in a charge / discharge cycle that is charged and used until it becomes a high potential. On the other hand, at the time of overcharge, the positive electrode and this compound react to quickly shift the battery to a safe state before the battery becomes abnormal. Therefore, the overcharge safety is dramatically improved without adversely affecting the battery.
上記構成において、前記正極の電位がリチウム基準で４．４〜４．６Ｖであり、前記正極活物質が、少なくともジルコニウムとマグネシウムとが添加されたコバルト酸リチウムと、層状構造を有するリチウムニッケルマンガン複合酸化物とからなり、前記負極活物質が黒鉛からなる構成とすることができる。 In the above structure, the positive electrode has a potential of 4.4 to 4.6 V based on lithium, and the positive electrode active material includes lithium cobaltate to which at least zirconium and magnesium are added, and a lithium nickel manganese composite having a layered structure The negative electrode active material may be made of graphite, and the negative electrode active material may be made of graphite.
この構成によると、正極活物質としてジルコニウムとマグネシウムとが添加されたリチウムコバルト複合酸化物を有しており、この化合物はジルコニウムとマグネシウムとの添加によって高電位（リチウム基準で４．４〜４．６Ｖ）での安定性が高められている。さらに、正極活物質として、高電位での熱安定性に優れた層状構造を有するリチウムニッケルマンガン複合酸化物が配合されているため、高電位での熱安定性に優れる。よって、この活物質系は、高電位となるまで充電して使用するのに適している。 According to this configuration, the positive electrode active material has a lithium cobalt composite oxide to which zirconium and magnesium are added, and this compound has a high potential (4.4-4. The stability at 6V) is enhanced. Furthermore, since the lithium nickel manganese composite oxide having a layered structure excellent in thermal stability at high potential is blended as the positive electrode active material, the thermal stability at high potential is excellent. Therefore, this active material system is suitable for being charged until it reaches a high potential.
電池電圧は、正極の電位と負極の電位との差で示され、電池電圧を大きくすることにより、電池の容量を大きくすることができるが、負極活物質として電位の低い黒鉛（リチウム基準で約０．１Ｖ）を用いると、電池電圧が高く、正極活物質の利用効率の高い電池が得られる。 The battery voltage is indicated by the difference between the positive electrode potential and the negative electrode potential. By increasing the battery voltage, the battery capacity can be increased. When 0.1V) is used, a battery with high battery voltage and high utilization efficiency of the positive electrode active material can be obtained.
なお、この系の電池では、正極の電位を４．６Ｖよりも高くすると、上記正極活物質を用いても、正極活物質の安定性が低下するという問題がある。よって、正極の電位を上記範囲内に規制することが好ましい。 Note that in this type of battery, when the positive electrode potential is higher than 4.6 V, there is a problem that the stability of the positive electrode active material is lowered even when the positive electrode active material is used. Therefore, it is preferable to regulate the potential of the positive electrode within the above range.
また、ジルコニウムとマグネシウムとが添加されたリチウムコバルト複合酸化物には、アルミニウム等の異種元素がさらに添加されていてもよい。また、層状構造を有するリチウムニッケルマンガン複合酸化物には、結晶構造中にコバルトが含まれていてもよく、ジルコニウム、マグネシウム、アルミニウム等が添加されていてもよい。 In addition, a different element such as aluminum may be further added to the lithium cobalt composite oxide to which zirconium and magnesium are added. Further, the lithium nickel manganese composite oxide having a layered structure may contain cobalt in the crystal structure, and may contain zirconium, magnesium, aluminum, or the like.
上記のジルコニウムとマグネシウムとが添加されたリチウムコバルト複合酸化物は、ＬｉａＣｏ１−ｘ−ｙ−ｚＺｒｘＭｇｙＭｚＯ２（ＭはＡｌ，Ｔｉ，Ｓｎの少なくとも一種であり、０＜ａ≦１．１、ｘ＋ｙ＋ｚ＝１）で示されるものである。また、層状リチウムニッケルマンガン複合酸化物は、ＬｉｂＭｎｓＮｉｔＣｏｕＸｖＯ２（ＸはＺｒ，Ｍｇ，Ａｌ，Ｔｉ，Ｓｎの少なくとも一種、０≦＜ｂ≦１．１、ｓ＋ｔ＋ｕ＋ｖ＝１）で示されるものである。 Said zirconium and lithium cobalt composite oxide and is added magnesium, Li a Co 1-x- y-z Zr x Mg y M z O 2 (M is Al, Ti, at least one of Sn, 0 <A ≦ 1.1, x + y + z = 1). Further, the layered lithium-nickel-manganese composite oxide, Li b Mn s Ni t Co u X v O 2 (X is at least one Zr, Mg, Al, Ti, Sn, 0 ≦ <b ≦ 1.1, s + t + u + v = 1).
なお、本願発明の効果を十分に得るためには、ジルコニウムの添加量が、ＬｉａＣｏ１−ｘ−ｙ−ｚＺｒｘＭｇｙＭｚＯ２において、０．０００１≦ｘ＜０．０３であることが好ましい。また、本願発明の効果を十分に得るためには、マグネシウムの添加量は、０．０００１≦ｙ＜０．０３であることが好ましい。また、ジルコニウム、マグネシウム以外に、Ａｌ，Ｔｉ，Ｓｎが０．０００２≦ｚ＜０．０３の割合で添加されていてもよい。 In order to obtain the effect of the present invention sufficiently, the amount of zirconium added is 0.0001 ≦ x <0.03 in Li a Co 1-x-yz Zr x Mg y M z O 2 . Preferably there is. In order to sufficiently obtain the effects of the present invention, the amount of magnesium added is preferably 0.0001 ≦ y <0.03. In addition to zirconium and magnesium, Al, Ti, and Sn may be added in a ratio of 0.0002 ≦ z <0.03.
また、本願発明の効果を十分に得るためには、ニッケルの含有量が、ＬｉｂＭｎｓＮｉｔＣｏｕＸｖＯ２において、０＜ｔ≦０．５であることが好ましい。また、マンガン、コバルトの含有量が、０≦ｓ、０＜ｕ≦０．５であり、ｓ＋ｔ＋ｕ＝1であることが好ましい。また、化合物の熱安定性を高めるために、Ｚｒ，Ｍｇ，Ａｌ，Ｔｉ，Ｓｎ等の異種元素が０．０００１≦ｖ≦０．０３の割合で添加されていてもよい。この場合はｓ＋ｔ＋ｕ＋ｖ＝１であることが好ましい。 Further, in order to obtain the effect of the present invention sufficiently, the content of nickel in Li b Mn s Ni t Co u X v O 2, it is preferred that 0 <t ≦ 0.5. Further, the contents of manganese and cobalt are preferably 0 ≦ s, 0 <u ≦ 0.5, and preferably s + t + u = 1. Further, in order to increase the thermal stability of the compound, different elements such as Zr, Mg, Al, Ti and Sn may be added at a ratio of 0.0001 ≦ v ≦ 0.03. In this case, it is preferable that s + t + u + v = 1.
また、正極活物質中のリチウムコバルト複合酸化物の含有量が５１質量％より少ないと、電池容量、サイクル特性、保存特性が低下するおそれがあり、また、層状構造のリチウムニッケルマンガン複合酸化物の含有量が１０質量％未満であると、正極活物質の高電位での熱安定性の向上効果が十分に得られない。このため、好ましくはリチウムコバルト複合酸化物と、層状リチウムニッケルマンガン複合酸化物の質量比を、好ましくは５１：４９〜９０：１０とし、より好ましくは７０：３０〜８０：２０とする。 In addition, when the content of the lithium cobalt composite oxide in the positive electrode active material is less than 51% by mass, the battery capacity, cycle characteristics, and storage characteristics may be deteriorated. When the content is less than 10% by mass, the effect of improving the thermal stability of the positive electrode active material at a high potential cannot be sufficiently obtained. Therefore, the mass ratio of the lithium cobalt composite oxide and the layered lithium nickel manganese composite oxide is preferably 51:49 to 90:10, more preferably 70:30 to 80:20.
上記構成において、前記リチウム塩の含有量が、非水電解質１００質量部に対して０．０５〜２．０質量部であり、前記酸化分解電位がリチウム基準で前記正極の電位よりも０．３Ｖ以上高い化合物の含有量が、非水電解質１００質量部に対して０．５〜４．０質量部であるである構成とすることができる。 In the above configuration, the content of the lithium salt is 0.05 to 2.0 parts by mass with respect to 100 parts by mass of the nonaqueous electrolyte, and the oxidative decomposition potential is 0.3 V higher than the potential of the positive electrode on a lithium basis. It can be set as the structure whose content of a high compound is 0.5-4.0 mass parts with respect to 100 mass parts of nonaqueous electrolyte.
上記リチウム塩の含有量が０．０５質量部未満であると、十分な効果が得られない可能性がある。他方、２．０質量部とすると、リチウム塩による効果の上限に達し、更なる添加はコスト高を招く。また、この種のリチウム塩は、非水溶媒に対する溶解性が低いため、２．０質量部以上溶かすことは難しく、溶けきらなかったリチウム塩が電池に悪影響を及ぼす可能性もある。よって、リチウム塩の含有量は上記範囲内に規制することが好ましい。 If the content of the lithium salt is less than 0.05 parts by mass, a sufficient effect may not be obtained. On the other hand, when the amount is 2.0 parts by mass, the upper limit of the effect of the lithium salt is reached, and further addition causes high cost. In addition, since this type of lithium salt has low solubility in a non-aqueous solvent, it is difficult to dissolve 2.0 parts by mass or more, and the lithium salt that has not been completely dissolved may adversely affect the battery. Therefore, the lithium salt content is preferably regulated within the above range.
酸化分解電位がリチウム基準で前記正極の電位よりも０．３Ｖ以上高い化合物の含有量が０．５質量部未満であると、十分な効果が得られないおそれがあり、４．０質量部より多いと、この化合物が分解してガスが発生し電池の厚みを増大させる可能性がある。よって、酸化分解電位がリチウム基準で前記正極の電位よりも０．３Ｖ以上高い化合物の含有量は上記範囲内に規制することが好ましい。 If the content of the compound having an oxidative decomposition potential of 0.3 V or more higher than the positive electrode potential on the basis of lithium is less than 0.5 parts by mass, a sufficient effect may not be obtained, and from 4.0 parts by mass If the amount is too large, this compound may decompose and generate gas, which may increase the thickness of the battery. Therefore, the content of the compound having an oxidative decomposition potential of 0.3 V or more higher than the positive electrode potential on the basis of lithium is preferably regulated within the above range.
上記構成において、前記非水電解質は更に、ビニレンカーボネートを有する構成とすることができる。 In the above configuration, the non-aqueous electrolyte may further include vinylene carbonate.
ビニレンカーボネート（ＶＣ）は、負極と反応して安定な被膜を形成し、サイクル特性を向上させるように作用する。ここで、ＶＣの含有量が０．５質量％未満であると十分な効果が得られず、４．５質量部より多いと、ＶＣが分解して発生したガスにより電池を膨らしてしまう。よって、ＶＣの含有量は０．５〜４．５質量％であることが好ましい。 Vinylene carbonate (VC) reacts with the negative electrode to form a stable film and acts to improve cycle characteristics. Here, if the content of VC is less than 0.5% by mass, a sufficient effect cannot be obtained, and if it is more than 4.5 parts by mass, the battery is expanded by the gas generated by decomposition of VC. Therefore, the VC content is preferably 0.5 to 4.5% by mass.
上記酸化分解電位がリチウム基準で前記正極の電位よりも０．３Ｖ以上高い化合物としては、クロロトルエンやフルオロベンゼン等が好適に使用できる。 As the compound having an oxidation decomposition potential higher by 0.3 V or more than the potential of the positive electrode on the basis of lithium, chlorotoluene, fluorobenzene and the like can be suitably used.
上記課題を解決するための第２の本発明は、正極活物質を有する正極と、負極活物質を有する負極と、非水溶媒と電解質塩とを有する非水電解質と、を備えた非水電解質二次電池の充電方法において、前記非水電解質は更に、プロピレンカーボネートに飽和溶解させた液の電気伝導度が０．３ｍＳ×ｃｍ−１以下であるリチウム塩と、酸化分解電位がリチウム基準で前記正極の電位よりも０．３Ｖ以上高い化合物と、を有し、前記正極の電位がリチウム基準で４．４〜５．１Ｖとなるまで充電する工程を備えることを特徴とする。 A second aspect of the present invention for solving the above problems is a nonaqueous electrolyte comprising a positive electrode having a positive electrode active material, a negative electrode having a negative electrode active material, and a nonaqueous electrolyte having a nonaqueous solvent and an electrolyte salt. In the method for charging a secondary battery, the non-aqueous electrolyte further includes a lithium salt having a conductivity of 0.3 mS × cm −1 or less saturated in propylene carbonate, and an oxidative decomposition potential based on lithium. And a compound having a voltage higher by 0.3 V or more than the potential of the positive electrode, and charging until the potential of the positive electrode becomes 4.4 to 5.1 V on the basis of lithium.
以上説明したように、本発明によると、正極を高電位となるまで充電して使用した場合の安全性を飛躍的に向上でき、高率放電特性に優れた非水電解質二次電池を提供できる。 As described above, according to the present invention, the safety when the positive electrode is charged to a high potential and used can be dramatically improved, and a nonaqueous electrolyte secondary battery excellent in high rate discharge characteristics can be provided. .
本発明を実施するための最良の形態を、実施例を用いて詳細に説明する。なお、本発明は下記の形態に限定されるものではなく、その要旨を変更しない範囲において適宜変更して実施することが可能である。 The best mode for carrying out the present invention will be described in detail with reference to examples. In addition, this invention is not limited to the following form, In the range which does not change the summary, it can change suitably and can implement.
（実施例１）
〈正極の作製〉
コバルト（Ｃｏ）に対して０．２ｍｏｌ％のジルコニウム（Ｚｒ）と、コバルトに対して０．５ｍｏｌ％のマグネシウム（Ｍｇ）とを共沈させ、熱分解反応させて、ジルコニウム、マグネシウム含有四酸化三コバルトを得た。この四酸化三コバルトと炭酸リチウムとを混合し、空気雰囲気中で８５０℃で２４時間焼成し、その後乳鉢で平均粒径が１４μｍとなるまで粉砕して、ジルコニウム、マグネシウム含有リチウムコバルト複合酸化物（正極活物質Ａ）を得た。
Example 1
<Preparation of positive electrode>
Co-precipitation of 0.2 mol% of zirconium (Zr) with respect to cobalt (Co) and 0.5 mol% of magnesium (Mg) with respect to cobalt, followed by thermal decomposition reaction, gave zirconium and magnesium-containing trioxide. Cobalt was obtained. This tricobalt tetroxide and lithium carbonate are mixed, calcined in an air atmosphere at 850 ° C. for 24 hours, and then pulverized in a mortar until the average particle size becomes 14 μm. A positive electrode active material A) was obtained.
炭酸リチウムと、Ｎｉ０．３３Ｍｎ０．３３Ｃｏ０．３４（ＯＨ）２で示される共沈水酸化物とを混合し、空気雰囲気中で１０００℃で２０時間焼成し、その後乳鉢で平均粒径が５μｍとなるまで粉砕して、コバルト含有リチウムニッケルマンガン複合酸化物（正極活物質Ｂ）を得た。なお、この正極活物質Ｂの結晶構造をＸ線を用いて解析したところ、層状構造であることが確認された。 Lithium carbonate and a coprecipitated hydroxide represented by Ni 0.33 Mn 0.33 Co 0.34 (OH) 2 were mixed and fired at 1000 ° C. for 20 hours in an air atmosphere. To 5 μm, a cobalt-containing lithium nickel manganese composite oxide (positive electrode active material B) was obtained. In addition, when the crystal structure of this positive electrode active material B was analyzed using the X-ray | X_line, it was confirmed that it is a layered structure.
正極活物質Ａと正極活物質Ｂとを質量比７：３で混合した正極活物質９４質量部と、導電剤としての炭素粉末３質量部と、結着剤としてのポリフッ化ビニリデン（ＰＶｄＦ）３質量部と、Ｎ−メチルピロリドンとを混合して正極活物質スラリーとした。この正極活物質スラリーをアルミニウム製の正極集電体（厚み１５μｍ）の両面に塗布し、乾燥・圧延して正極を作製した。 94 parts by mass of a positive electrode active material obtained by mixing the positive electrode active material A and the positive electrode active material B at a mass ratio of 7: 3, 3 parts by mass of carbon powder as a conductive agent, and polyvinylidene fluoride (PVdF) 3 as a binder Mass parts and N-methylpyrrolidone were mixed to obtain a positive electrode active material slurry. This positive electrode active material slurry was applied on both sides of an aluminum positive electrode current collector (thickness 15 μm), dried and rolled to produce a positive electrode.
〔負極の作製〕
負極活物質としての黒鉛９５質量部と、結着剤としてのスチレンブタジエンゴム３質量部と、増粘剤としてのカルボキシメチルセルロース２質量部とを、水に分散させて、負極活物質スラリーを調製した。
(Production of negative electrode)
A negative electrode active material slurry was prepared by dispersing 95 parts by mass of graphite as a negative electrode active material, 3 parts by mass of styrene butadiene rubber as a binder, and 2 parts by mass of carboxymethyl cellulose as a thickener. .
次に、厚み８μｍの銅箔からなる負極芯体の両面に、この負極活物質スラリーを均一な厚さで塗布した。この極板を乾燥機内に通して水分を除去した。この後、ロールプレス機を用いて圧延して、負極を作製した。 Next, this negative electrode active material slurry was applied to both surfaces of a negative electrode core made of a copper foil having a thickness of 8 μm with a uniform thickness. The electrode plate was passed through a dryer to remove moisture. Then, it rolled using the roll press machine and produced the negative electrode.
〔電極体の作製〕
上記正極と負極とポリオレフィン系樹脂からなる微多孔膜のセパレータとを、巻き取り機により捲回し、絶縁性の巻き止めテープを取り付け、プレスして扁平電極体を完成させた。
(Production of electrode body)
The positive electrode, the negative electrode, and a microporous membrane separator made of a polyolefin resin were wound by a winder, and an insulating anti-winding tape was attached and pressed to complete a flat electrode body.
〔非水電解質の調製〕
エチレンカーボネートとメチルエチルカーボネートとジエチルカーボネートとを、体積比２０：５０：３０の割合（１気圧、２５℃における）で混合した非水溶媒に、電解質塩としてのＬｉＰＦ６（本発明の低電気伝導度リチウム塩ではない）を１．０Ｍ（モル／リットル）の割合で溶解した。これに、クロロトルエンを非水電解質１００質量部あたり２質量部、酢酸リチウムを非水電解質１００質量部あたり１質量部となるように添加して非水電解質を調製した。
(Preparation of non-aqueous electrolyte)
LiPF 6 as an electrolyte salt (low electrical conductivity of the present invention) was mixed with a non-aqueous solvent in which ethylene carbonate, methyl ethyl carbonate, and diethyl carbonate were mixed at a volume ratio of 20:50:30 (1 atm, at 25 ° C.). Not lithium salt) was dissolved at a rate of 1.0 M (mol / liter). A non-aqueous electrolyte was prepared by adding chlorotoluene to 2 parts by mass per 100 parts by mass of the non-aqueous electrolyte and lithium acetate to 1 part by mass per 100 parts by mass of the non-aqueous electrolyte.
〔電池の作製〕
上記扁平電極体と上記非水電解質とを、アルミニウム合金製の角形外装缶内に挿入し、外装缶の開口部に封口板を嵌め合わせレーザ溶接して、高さ４３ｍｍ、幅３４ｍｍ、厚み５．０ｍｍの、実施例１にかかるリチウムイオン二次電池を作製した。
[Production of battery]
4. The flat electrode body and the non-aqueous electrolyte are inserted into a rectangular outer can made of aluminum alloy, a sealing plate is fitted into the opening of the outer can, and laser welding is performed to obtain a height of 43 mm, a width of 34 mm, and a thickness of 5. A lithium ion secondary battery according to Example 1 having a thickness of 0 mm was produced.
（実施例２）
クロロトルエンを非水電解質１００質量部あたり２質量部、酢酸リチウムを非水電解質１００質量部あたり１質量部添加することに代えて、フルオロベンゼンを非水電解質１００質量部あたり２質量部、安息香酸リチウムを非水電解質１００質量部あたり１質量部以外は、上記実施例１と同様にして、実施例２にかかる非水電解質二次電池を作製した。
(Example 2)
Instead of adding 2 parts by mass of chlorotoluene per 100 parts by mass of non-aqueous electrolyte and 1 part by mass of lithium acetate per 100 parts by mass of non-aqueous electrolyte, 2 parts by mass of fluorobenzene and benzoic acid per 100 parts by mass of non-aqueous electrolyte A nonaqueous electrolyte secondary battery according to Example 2 was produced in the same manner as in Example 1 except that lithium was 1 part by mass per 100 parts by mass of the nonaqueous electrolyte.
（比較例１）
クロロトルエン及び酢酸リチウムをともに添加しなかったこと以外は、上記実施例１と同様にして、比較例１にかかる非水電解質二次電池を作製した。
(Comparative Example 1)
A nonaqueous electrolyte secondary battery according to Comparative Example 1 was produced in the same manner as in Example 1 except that neither chlorotoluene nor lithium acetate was added.
（比較例２）
酢酸リチウムを添加しなかったこと以外は、上記実施例１と同様にして、比較例２にかかる非水電解質二次電池を作製した。
(Comparative Example 2)
A nonaqueous electrolyte secondary battery according to Comparative Example 2 was produced in the same manner as in Example 1 except that lithium acetate was not added.
（比較例３）
酢酸リチウムに代えて、ＬｉＢＦ４を１質量部添加したこと以外は、上記実施例１と同様にして、比較例３にかかる非水電解質二次電池を作製した。
(Comparative Example 3)
A nonaqueous electrolyte secondary battery according to Comparative Example 3 was produced in the same manner as in Example 1 except that 1 part by mass of LiBF 4 was added instead of lithium acetate.
（比較例４）
クロロトルエンを添加しなかったこと以外は、上記実施例１と同様にして、比較例４にかかる非水電解質二次電池を作製した。
(Comparative Example 4)
A nonaqueous electrolyte secondary battery according to Comparative Example 4 was produced in the same manner as in Example 1 except that chlorotoluene was not added.
（比較例５）
クロロトルエンに代えて、シクロヘキシルベンゼンを添加したこと以外は、上記実施例１と同様にして、比較例５にかかる非水電解質二次電池を作製した。
(Comparative Example 5)
A nonaqueous electrolyte secondary battery according to Comparative Example 5 was produced in the same manner as in Example 1 except that cyclohexylbenzene was added instead of chlorotoluene.
《電気伝導度の測定》
２５℃において、プロピレンカーボネート（ＰＣ）に各種リチウム塩を飽和溶解させた液を、電解液を厚さ０．２ｍｍおよび面積１．７７ｃｍ２のステンレス板で挟んで電圧を印加し、その印加する正弦波交流電圧を記号法（複素表示）で表現したいわゆるコール・コール（Cole-Cole）プロットから電気伝導度を求めた。この結果を下記表１に示す。
<Measurement of electrical conductivity>
In 25 ° C., a solution prepared in propylene carbonate (PC) of various lithium salts is saturated dissolved, a voltage is applied across a stainless plate having a thickness of the electrolyte of 0.2mm and an area 1.77 cm 2, to the applied sinusoidal The electrical conductivity was obtained from a so-called Cole-Cole plot in which a wave AC voltage was expressed by a symbolic method (complex display). The results are shown in Table 1 below.
《酸化分解電位の測定》
２５℃において、エチレンカーボネート３０体積％とエチルメチルカーボネート７０体積％からなる混合溶媒に１ｍｏｌ／ＬのＬｉＰＦ６を溶解させた。次いで、この液１００ｇに、各種化合物を０．１質量％溶解させて、試験液となした。リチウム金属からなる対極と参照極と、白金からなる作用極とを、上記試験液に浸漬し、１ｍＶ／秒の電位走査を行った。このとき、０．１ｍＡ／ｃｍ２の酸化電流が流れた電位を酸化分解電位とした。
<Measurement of oxidation decomposition potential>
In 25 ° C., obtained by dissolving LiPF 6 of 1 mol / L in a mixed solvent composed of ethylene carbonate 30 vol% and 70 vol% ethyl methyl carbonate. Next, 0.1% by mass of various compounds was dissolved in 100 g of this solution to prepare a test solution. A counter electrode made of lithium metal, a reference electrode, and a working electrode made of platinum were immersed in the test solution, and a potential scan of 1 mV / second was performed. At this time, a potential at which an oxidation current of 0.1 mA / cm 2 flowed was defined as an oxidation decomposition potential.
《過充電試験》
２５℃において、８３０ｍＡの定電流で電圧が１２Ｖとなるまで充電し、電池の状態を観察した。ここで、非水電解質の漏液が確認されたものを×（不良）、異常なしのものを○（良好）と評価した。この結果を下記表３に示す。
<Overcharge test>
At 25 ° C., the battery was charged with a constant current of 830 mA until the voltage reached 12 V, and the state of the battery was observed. Here, the case where leakage of the nonaqueous electrolyte was confirmed was evaluated as x (defect), and the case without abnormality was evaluated as o (good). The results are shown in Table 3 below.
《高率放電試験》
２５℃において、１Ｉｔ（８３０ｍＡ）の定電流で電圧が４．４Ｖ（正極の電位がリチウム基準で４．５Ｖ）となるまで充電し、その後４．４Ｖの定電圧で電流が２０ｍＡとなるまで充電した。この電池を、１Ｉｔ（８３０ｍＡ）の定電流で電圧が３．０Ｖとなるまで放電した。この後上記条件で再度充電し、３Ｉｔ（２４９０ｍＡ）の定電流で電圧が３．０Ｖとなるまで放電した。高率放電特性を、以下の式により求め、０．８以上のものを○（良好）、０．８未満のものを×（不良）と評価した。この結果を下記表２に示す。
《High rate discharge test》
At 25 ° C, the battery is charged with a constant current of 1 It (830 mA) until the voltage reaches 4.4 V (the positive electrode potential is 4.5 V with respect to lithium), and then charged with a constant voltage of 4.4 V until the current reaches 20 mA. did. The battery was discharged at a constant current of 1 It (830 mA) until the voltage reached 3.0V. Thereafter, the battery was charged again under the above conditions, and discharged at a constant current of 3 It (2490 mA) until the voltage reached 3.0V. The high rate discharge characteristics were determined by the following formula, and those with 0.8 or more were evaluated as ◯ (good) and those with less than 0.8 were evaluated as x (defect). The results are shown in Table 2 below.
高率放電特性＝３Ｉｔ放電容量÷１Ｉｔ放電容量 High rate discharge characteristics = 3 It discharge capacity ÷ 1 It discharge capacity
上記表３から、低電気伝導度リチウム塩が添加されていない比較例１〜３では、高率放電特性試験の結果が×、過充電試験の結果が×であり、低電気伝導度リチウム塩及び高電位酸化分解化合物を添加した実施例１、２の高率放電特性試験の結果○、過充電試験の結果○よりも劣っていることがわかる。 From Table 3 above, in Comparative Examples 1 to 3 in which the low electrical conductivity lithium salt was not added, the result of the high rate discharge characteristic test was x, the result of the overcharge test was x, and the low electrical conductivity lithium salt and It turns out that it is inferior to the result (circle) of the high rate discharge characteristic test of Example 1, 2 which added the high potential oxidative decomposition compound, and the result (circle) of the overcharge test.
このことは、次のように考えられる。通常、充放電を行うと、非水電解質内でリチウムイオンの濃度分布が不均一となるが、上記低電気伝導度のリチウム塩は、リチウムイオン濃度が低くなっている部分で乖離してリチウムイオンを生じさせ、リチウムイオンの濃度分布の不均一を緩衝させるように作用する。このため、正極全体が均一に充放電される。 This is considered as follows. Normally, when charge / discharge is performed, the concentration distribution of lithium ions in the non-aqueous electrolyte becomes non-uniform, but the lithium salt with low electrical conductivity is separated from the lithium ion concentration at the portion where the lithium ion concentration is low. And acts to buffer non-uniformity of the lithium ion concentration distribution. For this reason, the whole positive electrode is charged / discharged uniformly.
過充電時や高率放電時には、特にリチウムイオン濃度分布の不均一が生じやすいが、上記リチウム塩を含ませることにより、局所的な過充電や過放電が生じにくくなる。よって、高率放電時においてもスムースに放電反応が進行するので、高率放電特性が飛躍的に高まる。また、正極内での電位のムラを０．３Ｖ未満に抑制できる。 During overcharge or high rate discharge, in particular, the lithium ion concentration distribution is likely to be non-uniform, but by including the lithium salt, local overcharge and overdischarge are less likely to occur. Therefore, since the discharge reaction proceeds smoothly even during high rate discharge, the high rate discharge characteristics are dramatically improved. Moreover, the unevenness of the potential in the positive electrode can be suppressed to less than 0.3V.
上記実施例１、２では、さらに酸化分解電位がリチウム基準で４．８Ｖ以上（正極の電位よりも０．３Ｖ以上高い）の化合物を備えている。この化合物は、上記リチウム塩と併用することにより、高電位となるまで充電して使用する充放電サイクルでは、酸化分解することがない。この一方、過充電時には、正極とこの化合物とが反応して、電池が異常に至る前に速やかに電池を安全状態に移行させる。よって、電池に悪影響を及ぼすことなく過充電安全性が飛躍的に向上する。 In Examples 1 and 2, a compound having an oxidative decomposition potential of 4.8 V or higher (0.3 V or higher than the positive electrode potential) based on lithium is provided. When this compound is used in combination with the above lithium salt, it is not oxidatively decomposed in a charge / discharge cycle in which it is charged until it reaches a high potential. On the other hand, at the time of overcharge, the positive electrode and this compound react to quickly shift the battery to a safe state before the battery becomes abnormal. Therefore, the overcharge safety is dramatically improved without adversely affecting the battery.
また、低電気伝導度リチウム塩を含み、高電位酸化分解化合物が添加されていない比較例４では、過充電試験の結果が×であり、低電気伝導度リチウム塩及び高電位酸化分解化合物を添加した実施例１、２の過充電試験の結果○よりも劣っていることがわかる。 Further, in Comparative Example 4 which contains a low electrical conductivity lithium salt and no high potential oxidative decomposition compound was added, the result of the overcharge test was x, and the low electrical conductivity lithium salt and the high potential oxidative decomposition compound were added. It turns out that it is inferior to (circle) result of the overcharge test of Example 1 and 2 which were done.
このことは、次のように考えられる。比較例４では、高電位酸化分解化合物を含んでいないため、過充電時による電池の異常状態を回避できず、電池を漏液に至らせる。 This is considered as follows. In Comparative Example 4, since the high potential oxidative decomposition compound is not included, the abnormal state of the battery due to overcharging cannot be avoided, and the battery is leaked.
また、低電気伝導度リチウム塩を含み、高電位酸化分解化合物に代えてシクロヘキシルベンゼンが添加された比較例５では、高率放電特性試験の結果が×であり、低電気伝導度リチウム塩及び高電位酸化分解化合物を添加した実施例１、２の過充電試験の結果○よりも劣っていることがわかる。 Further, in Comparative Example 5 containing a low electrical conductivity lithium salt and adding cyclohexylbenzene in place of the high potential oxidative decomposition compound, the result of the high rate discharge characteristic test was x, and the low electrical conductivity lithium salt and the high electrical conductivity lithium salt It turns out that it is inferior to the result (circle) of the overcharge test of Example 1, 2 which added the potential oxidative decomposition compound.
このことは、次のように考えられる。比較例５では、シクロヘキシルベンゼンの酸化分解電位が４．７Ｖであり、正極の電位との差が０．２Ｖと小さく、通常の充放電で局所的に過充電された部分で分解して電池に悪影響を及ぼす。このため、高率放電特性が低下する。 This is considered as follows. In Comparative Example 5, the oxidative decomposition potential of cyclohexylbenzene is 4.7 V, the difference from the positive electrode potential is as small as 0.2 V, and it is decomposed at a portion that is locally overcharged by normal charge / discharge and becomes a battery. Adversely affect. For this reason, a high rate discharge characteristic falls.
なお、正極活物質としては、上記実施例で用いたもの以外に、例えば異種元素を添加して高電位での安定性を高めたスピネル型マンガン酸リチウムを用いることができる。また、負極活物質には、リチウムを吸蔵・放出することが可能な炭素質材料、特に人造黒鉛や天然黒鉛等の黒鉛類が用いられる。 As the positive electrode active material, for example, spinel type lithium manganate which is improved in stability at a high potential by adding a different element can be used in addition to the materials used in the above examples. As the negative electrode active material, a carbonaceous material capable of inserting and extracting lithium, particularly graphite such as artificial graphite and natural graphite is used.
本発明においては、非水溶媒系電解質を構成する非水溶媒（有機溶媒）としては、カーボネート類、ラクトン類、エーテル類、エステル類などを使用することができ、これら溶媒の２種類以上を混合して用いることもできる。これらの中ではカーボネート類、ラクトン類、エーテル類、ケトン類、エステル類などが好ましく、カーボネート類がさらに好ましい。 In the present invention, carbonates, lactones, ethers, esters and the like can be used as the nonaqueous solvent (organic solvent) constituting the nonaqueous solvent electrolyte, and two or more of these solvents are mixed. It can also be used. Among these, carbonates, lactones, ethers, ketones, esters and the like are preferable, and carbonates are more preferable.
具体例としては、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、フルオロエチレンカーボネート、１，２−シクロヘキシルカーボネート、シクロペンタノン、スルホラン、３−メチルスルホラン、２，４−ジメチルスルホラン、３−メチル−１，３オキサゾリジン−２−オン、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、メチルプロピルカーボネート、メチルブチルカーボネート、エチルプロピルカーボネート、エチルブチルカーボネート、ジプロピルカーボネート、γ−ブチロラクトン、γ−バレロラクトン、１，２−ジメトキシエタン、テトラヒドロフラン、２−メチルテトラヒドロフラン、１，３−ジオキソラン、酢酸メチル、酢酸エチル、１，４−ジオキサンなどを挙げることができる。充放電効率を高める点から、エチレンカーボネート（ＥＣ）と、ジメチルカーボネート（ＤＭＣ）・メチルエチルカーボネート（ＭＥＣ）・ジエチルカーボネート（ＤＥＣ）等の鎖状カーボネート等との混合溶媒を用いることが好ましく、鎖状カーボネートとしてＭＥＣのような非対称鎖状カーボネートを用いることがより好ましい。また、鎖状カーボネートとして、ＤＭＣを用いるときは０体積％以上４０体積％以下、ＭＥＣを用いるときは３０体積％以上８０体積％以下、ＤＥＣを用いるときは２０体積％以上５０体積％以下とすることが好ましい。 Specific examples include ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate, 1,2-cyclohexyl carbonate, cyclopentanone, sulfolane, 3-methylsulfolane, 2,4-dimethylsulfolane, 3-methyl-1,3. Oxazolidin-2-one, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl butyl carbonate, ethyl propyl carbonate, ethyl butyl carbonate, dipropyl carbonate, γ-butyrolactone, γ-valerolactone, 1,2-dimethoxy Ethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, methyl acetate, ethyl acetate, 1,4-dioxane, etc. be able to. From the viewpoint of increasing charge / discharge efficiency, it is preferable to use a mixed solvent of ethylene carbonate (EC) and chain carbonates such as dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), and diethyl carbonate (DEC). It is more preferable to use an asymmetric linear carbonate such as MEC as the linear carbonate. Moreover, as a linear carbonate, when using DMC, it is 0 volume% or more and 40 volume% or less, when using MEC, it is 30 volume% or more and 80 volume% or less, and when using DEC, it is 20 volume% or more and 50 volume% or less. It is preferable.
なお、本発明における非水電解質の電解質塩としては、非水電解質二次電池において一般に電解質塩として用いられるリチウム塩を用いることができる。このようなリチウム塩としては、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＣＦ３ＳＯ３、ＬｉＮ（ＣＦ３ＳＯ２）２、ＬｉＮ（Ｃ２Ｆ５ＳＯ２）２、ＬｉＮ（ＣＦ３ＳＯ２）（Ｃ４Ｆ９ＳＯ２）、ＬｉＣ（ＣＦ３ＳＯ２）３、ＬｉＣ（Ｃ２Ｆ５ＳＯ２）３、ＬｉＡｓＦ６、ＬｉＣｌＯ４、Ｌｉ２Ｂ１０Ｃｌ１０、Ｌｉ２Ｂ１２Ｃｌ１２など及びそれらの混合物が例示される。ここで、高い充電電圧で充電する場合、通常正極の集電体として用いられるアルミニウムが溶解しやすくなるが、ＬｉＰＦ６の存在下では、ＬｉＰＦ６が分解することにより、アルミニウム表面に被膜が形成され、この被膜によってアルミニウムの溶解を抑制することができる。従って、リチウム塩としては、ＬｉＰＦ６を用いることが好ましい。前記非水溶媒に対する電解質塩の溶解量は、０．５〜２．０ｍｏｌ／Ｌとするのが好ましい。 In addition, as an electrolyte salt of the nonaqueous electrolyte in the present invention, a lithium salt generally used as an electrolyte salt in a nonaqueous electrolyte secondary battery can be used. Such lithium salts include LiPF 6 , LiBF 4 , LiCF 3 SO 3 , 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 ), LiC (CF 3 SO 2 ) 3 , LiC (C 2 F 5 SO 2 ) 3 , LiAsF 6 , LiClO 4 , Li 2 B 10 Cl 10 , Li 2 B 12 Cl 12 , and mixtures thereof Illustrated. Here, when charged with a high charging voltage, although aluminum is used as a current collector for normal positive electrode is easily dissolved in the presence of LiPF 6, by LiPF 6 decomposes, coating is formed on the aluminum surface The dissolution of aluminum can be suppressed by this coating. Therefore, it is preferable to use LiPF 6 as the lithium salt. The amount of electrolyte salt dissolved in the non-aqueous solvent is preferably 0.5 to 2.0 mol / L.
以上説明したように、本発明によると、正極を高電位となるまで充電して使用する電池の過充電安全性を大きく向上させることができ、且つ高率放電特性を飛躍的に向上できるので、産業上の意義は大きい。
As described above, according to the present invention, it is possible to greatly improve the overcharge safety of the battery used by charging the positive electrode until it becomes a high potential, and the high rate discharge characteristics can be dramatically improved. Industrial significance is great.
Claims (6)
前記正極の電位がリチウム基準で４．４〜５．１Ｖであり、
前記非水電解質は更に、プロピレンカーボネートに飽和溶解させた液の電気伝導度が、２５℃において０．３ｍＳ×ｃｍ−１以下であるリチウム塩と、
酸化分解電位がリチウム基準で前記正極の電位よりも０．３Ｖ以上高い化合物と、を有する、
ことを特徴とする非水電解質二次電池。
In a nonaqueous electrolyte secondary battery comprising a positive electrode having a positive electrode active material, a negative electrode having a negative electrode active material, and a nonaqueous electrolyte having a nonaqueous solvent and an electrolyte salt,
The positive electrode has a potential of 4.4 to 5.1 V based on lithium,
The non-aqueous electrolyte further includes a lithium salt having a conductivity of 0.3 mS × cm −1 or less at 25 ° C. in a liquid saturated with propylene carbonate,
A compound having an oxidative decomposition potential 0.3 V or more higher than the potential of the positive electrode on a lithium basis,
A non-aqueous electrolyte secondary battery.
前記正極の電位がリチウム基準で４．４〜４．６Ｖであり、
前記正極活物質が、少なくともジルコニウムとマグネシウムとが添加されたコバルト酸リチウムと、層状構造を有するリチウムニッケルマンガン複合酸化物とからなり、
前記負極活物質が黒鉛からなる、
ことを特徴とする非水電解質二次電池。 The nonaqueous electrolyte secondary battery according to claim 1,
The positive electrode has a potential of 4.4 to 4.6 V based on lithium,
The positive electrode active material is composed of lithium cobalt oxide to which at least zirconium and magnesium are added, and a lithium nickel manganese composite oxide having a layered structure,
The negative electrode active material is made of graphite;
A non-aqueous electrolyte secondary battery.
前記リチウム塩の含有量が、非水電解質１００質量部に対して０．０５〜２．０質量部であり、
前記酸化分解電位がリチウム基準で前記正極の電位よりも０．３Ｖ以上高い化合物の含有量が、非水電解質１００質量部に対して０．５〜４．０質量部である、
ことを特徴とする非水電解質二次電池。 The nonaqueous electrolyte secondary battery according to claim 1 or 2,
The content of the lithium salt is 0.05 to 2.0 parts by mass with respect to 100 parts by mass of the nonaqueous electrolyte,
The content of the compound having an oxidation decomposition potential of 0.3 V or more higher than the positive electrode potential on the basis of lithium is 0.5 to 4.0 parts by mass with respect to 100 parts by mass of the nonaqueous electrolyte.
A non-aqueous electrolyte secondary battery.
前記非水電解質は更に、ビニレンカーボネートを有する、
ことを特徴とする非水電解質二次電池。 The nonaqueous electrolyte secondary battery according to claim 1, 2, or 3,
The non-aqueous electrolyte further comprises vinylene carbonate;
A non-aqueous electrolyte secondary battery.
前記化合物は、クロロトルエン及びフルオロベンゼンの少なくとも一種である、
ことを特徴とする非水電解質二次電池。 The nonaqueous electrolyte secondary battery according to claim 1, 2, 3 or 4,
The compound is at least one of chlorotoluene and fluorobenzene.
A non-aqueous electrolyte secondary battery.
前記非水電解質は更に、プロピレンカーボネートに飽和溶解させた液の電気伝導度が、２５℃において０．３ｍＳ×ｃｍ−１以下であるリチウム塩と、
酸化分解電位がリチウム基準で前記正極の電位よりも０．３Ｖ以上高い化合物と、を有し、
前記正極の電位がリチウム基準で４．４〜５．１Ｖとなるまで充電する工程を備える、
ことを特徴とする非水電解質二次電池の充電方法。 In a method for charging a nonaqueous electrolyte secondary battery comprising a positive electrode having a positive electrode active material, a negative electrode having a negative electrode active material, and a nonaqueous electrolyte having a nonaqueous solvent and an electrolyte salt,
The non-aqueous electrolyte further includes a lithium salt having a conductivity of 0.3 mS × cm −1 or less at 25 ° C. in a liquid saturated with propylene carbonate,
A compound having an oxidative decomposition potential higher by 0.3 V or more than the potential of the positive electrode on a lithium basis,
A step of charging until the potential of the positive electrode is 4.4 to 5.1 V based on lithium;
A non-aqueous electrolyte secondary battery charging method.
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| JP2012174437A (en) * | 2011-02-21 | 2012-09-10 | Denso Corp | Charging apparatus and charging method for lithium secondary battery |
| JP2015198052A (en) * | 2014-04-02 | 2015-11-09 | 旭化成株式会社 | Using method of lithium ion secondary battery, and lithium ion secondary battery |
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