JP2002352797A - Nonaqueous secondary battery - Google Patents

Nonaqueous secondary battery

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Publication number
JP2002352797A
JP2002352797A JP2001160766A JP2001160766A JP2002352797A JP 2002352797 A JP2002352797 A JP 2002352797A JP 2001160766 A JP2001160766 A JP 2001160766A JP 2001160766 A JP2001160766 A JP 2001160766A JP 2002352797 A JP2002352797 A JP 2002352797A
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JP
Japan
Prior art keywords
negative electrode
positive electrode
lithium
capacity
charge
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.)
Withdrawn
Application number
JP2001160766A
Other languages
Japanese (ja)
Inventor
Tokuji Ueda
上田　　篤司
Kiyonari Kimachi
聖也 木町
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Maxell Holdings Ltd
Original Assignee
Hitachi Maxell Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Hitachi Maxell Ltd filed Critical Hitachi Maxell Ltd
Priority to JP2001160766A priority Critical patent/JP2002352797A/en
Publication of JP2002352797A publication Critical patent/JP2002352797A/en
Withdrawn legal-status Critical Current

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    • 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

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous secondary cell that has high capacity and superior recycle characteristics. SOLUTION: This nonaqueous secondary battery is equipped with a negative electrode composed of at least a lithium-silicon alloy and carbon and a positive electrode composed of at least a metal oxide lithium compound, where the charging quantity of the negative electrode is controlled to be lower than the utilization percentage of the negative electrode calculated from the related formula: utilization percentage(%) of negative electrode = [4199×β/100×α/100+372×(1-α)/100]/[4199×α/100+372×(1-α)/100]×100, where α is percentage(%) of silicon content, 0<α<=70, and β is percentage(%) of silicon utilization, and 0<β<=45.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、高容量で、サイク
ル特性に優れた非水二次電池に関する。The present invention relates to a non-aqueous secondary battery having a high capacity and excellent cycle characteristics.

【０００２】[0002]

【従来の技術】近年、携帯電話や携帯情報端末などのポ
ータブル電子機器の低電圧化で、２．０Ｖ程度の作動電
圧を示し、且つ高容量の二次電池が必要とされるように
なってきた。このような観点から、リチウムイオン二次
電池が提案され、開発されている。開発当初は、負極材
料としてリチウム金属が用いられていた。しかしなが
ら、この金属リチウムを用いる電池は急速充放電特性に
劣り、サイクル寿命が短く、また充電時にリチウムのデ
ンドライト（樹枝状結晶）が生成して短絡等が発生しや
すく、安全上の問題もあった。以上のような問題点を解
決するために、現在は負極に炭素系及び黒鉛系の材料を
用いたリチウムイオン二次電池が商品化され、多用され
ている。2. Description of the Related Art In recent years, with the reduction in the voltage of portable electronic devices such as portable telephones and personal digital assistants, a secondary battery having an operating voltage of about 2.0 V and a high capacity has been required. Was. From such a viewpoint, a lithium ion secondary battery has been proposed and developed. Initially, lithium metal was used as the negative electrode material. However, batteries using this metallic lithium are inferior in rapid charge / discharge characteristics, have a short cycle life, and are liable to generate lithium dendrites (dendritic crystals) during charging, causing short-circuits and the like, and have a safety problem. . In order to solve the above problems, a lithium ion secondary battery using a carbon-based or graphite-based material for a negative electrode has been commercialized and widely used.

【０００３】このリチウムイオン二次電池のより一層の
高容量化を図るために、正極材料及び負極材料の研究が
続けられている。従来の正極材料としては、ＬｉＭｎ2
Ｏ4、ＬｉＣｏＯ2及びＬｉＮｉＯ2等が検討されてきた
が、調製が容易であるということ及び比較的安全性が高
いということからＬｉＣｏＯ2が多く用いられてきた。
しかし、最近では高容量化のため、ＬｉＮｉＯ2の改
良、またマンガンを含んだ新規材料の検討が盛んに行な
われている。[0003] In order to further increase the capacity of this lithium ion secondary battery, research on positive electrode materials and negative electrode materials has been continued. Conventional cathode materials include LiMn 2
O 4 , LiCoO 2, LiNiO 2 and the like have been studied, but LiCoO 2 has been frequently used because of its easy preparation and relatively high safety.
However, recently, in order to increase the capacity, improvement of LiNiO 2 and investigation of a new material containing manganese have been actively conducted.

【０００４】一方の負極材料に関しては、黒鉛の理論容
量３７２ｍＡｈ／ｇに比べ遥かに大きい理論容量を持つ
リチウム合金を用いることが試みられている。例えば、
リチウム錫合金、リチウム鉛合金、リチウムビスマス合
金、リチウムアルミニウム合金、リチウムケイ素合金、
リチウムアンチモン合金等である。これらの合金材料は
そのまま負極材料として用いることができるが、多くの
場合、合金可能な金属、半金属を負極材料として用いて
電池を組み立て、充電時にこれらの金属又は半金属と、
正極から放出されたリチウムとの間で電気化学的に合金
化を起こさせ、生成した合金を負極材料として用いる方
法が採られている。しかしながら、リチウム合金系材料
は充電に伴い、即ち合金中のリチウム量の増加によって
その体積が数倍にも膨張することから、サイクルを繰り
返すにつれて合金の微粉化が必然的に起こり、電池の安
全性やサイクル特性にとって大きな阻害要因となってい
る。従って、現状ではリチウム合金を負極材料とするリ
チウム二次電池は実用化されていない。With respect to the negative electrode material, attempts have been made to use a lithium alloy having a theoretical capacity much larger than the theoretical capacity of graphite of 372 mAh / g. For example,
Lithium tin alloy, lithium lead alloy, lithium bismuth alloy, lithium aluminum alloy, lithium silicon alloy,
Lithium antimony alloy and the like. These alloy materials can be used as a negative electrode material as they are, but in many cases, a battery is assembled using a metal or semimetal that can be alloyed as a negative electrode material, and these metals or semimetals are used during charging.
A method of electrochemically causing alloying with lithium released from the positive electrode and using the resulting alloy as a negative electrode material has been adopted. However, the lithium alloy-based material expands its volume several times as it is charged, that is, increases in the amount of lithium in the alloy. Therefore, as the cycle is repeated, the alloy is inevitably pulverized, and the safety of the battery increases. And cycle characteristics. Therefore, at present, a lithium secondary battery using a lithium alloy as a negative electrode material has not been put to practical use.

【０００５】[0005]

【発明が解決しようとする課題】近年、前記のリチウム
合金を負極材料とする場合の問題点を解決すべく、特開
２０００−２１５８８７号公報に記載のように、リチウ
ム合金を形成する金属、半金属を炭素で被覆することに
より、炭素層がリチウムと合金を形成する金属又は半金
属に対して膨張を抑制する拘束力を与えて電極の微粉化
や破壊を防いだ材料が提案されている。また、電極の重
要な構成要素であるバインダーを弾力性のあるものと組
み合わせることによって、材料の体積膨張による電極の
微粉化を抑制できることが報告されている。このような
検討によって、リチウム合金系負極材料のサイクル耐久
性は、ある特定の充電深度を超えないように規制できれ
ば向上できることが分かってきた。In recent years, in order to solve the problems in the case where the above-mentioned lithium alloy is used as the negative electrode material, as disclosed in Japanese Patent Application Laid-Open No. 2000-21587, a metal for forming the lithium alloy is used. A material has been proposed in which a metal is coated with carbon so that a carbon layer gives a binding force that suppresses expansion to a metal or metalloid that forms an alloy with lithium, thereby preventing pulverization or destruction of an electrode. In addition, it is reported that by combining a binder, which is an important component of the electrode, with an elastic one, it is possible to suppress pulverization of the electrode due to volume expansion of the material. From such studies, it has been found that the cycle durability of the lithium alloy-based negative electrode material can be improved if it can be regulated so as not to exceed a certain specific depth of charge.

【０００６】しかしながら、充電時に負極材料自体の体
積が数倍に膨張するという本質的な課題は残されたまま
であるために、サイクル数とともにインピーダンスが変
化し、一定の充電量であってもその終止電位（リチウム
金属基準）は変動する。それゆえ、終止電位で充電量を
制御した場合、設定値以上の充電量となりサイクル劣化
を招くという問題がある。However, since the essential problem that the volume of the negative electrode material itself expands several times at the time of charging remains, the impedance changes with the number of cycles, and even when the charging amount is constant, the end of the charging operation is stopped. The potential (based on lithium metal) varies. Therefore, when the charge amount is controlled by the final potential, the charge amount becomes equal to or more than the set value, and there is a problem that cycle deterioration is caused.

【０００７】そこで、本発明は、前記従来の問題を解決
するため、負極の充電量を所定量以下に制御することに
より、高容量で、サイクル特性に優れた非水二次電池を
提供することを目的とする。Accordingly, the present invention provides a non-aqueous secondary battery having a high capacity and excellent cycle characteristics by controlling the charge amount of a negative electrode to a predetermined amount or less in order to solve the conventional problem. With the goal.

【０００８】[0008]

【課題を解決するための手段】リチウム合金系負極材料
の体積膨張により電極が破壊されるという前記課題を解
決すべく鋭意検討を続けた結果、理論容量の９０％以上
の充電が可能な正極、又は充電末期でその電極電位が急
激に上昇するような挙動を持つような正極と、リチウム
合金系負極とを組み合わせることによって電池の充電を
終了させることで、リチウム合金系負極の充電量をほぼ
一定にできることから、リチウム合金系材料の体積膨張
を被覆した炭素層によって拘束できる範囲に抑え、サイ
クル耐久性を向上させることができることを見出した。As a result of intensive studies to solve the above-mentioned problem that the electrode is destroyed due to volume expansion of the lithium alloy-based negative electrode material, a positive electrode capable of being charged to 90% or more of the theoretical capacity has been obtained. Alternatively, the charge of the lithium alloy-based negative electrode is almost constant by terminating the charging of the battery by combining the positive electrode having such a behavior that the electrode potential rapidly rises at the end of charging and the lithium alloy-based negative electrode. Thus, it has been found that the volume expansion of the lithium alloy-based material can be suppressed to a range that can be restricted by the coated carbon layer, and the cycle durability can be improved.

【０００９】この黒鉛材料よりも高容量を示すリチウム
合金系負極材料は、リチウム合金を形成する金属又は半
金属の粒子を核として、その粒子核を炭素で被覆するこ
とにより、炭素材料で構成されるマトリックス内にその
金属又は半金属の粒子が存在する複合材料である。この
複合材料において炭素層は、その金属又は半金属のリチ
ウム合金形成時の体積膨張を抑制する強い拘束力を有す
る。その結果、５００ｍＡｈ／ｇ以上、１５００ｍＡｈ
／ｇ以下の充電容量を示し、その充電容量を規制させた
時にサイクル耐久性を示す負極材料である。これを図１
に基づき説明する。図１は、リチウム−ケイ素合金系負
極のサイクル特性を示した図である。図１において、Ａ
は充電終始電位をＬｉ金属基準で４０ｍＶと一定とした
場合のサイクル数と放電容量の関係を示す。また、同図
において、Ｂは充電量を１０００ｍＡｈ／ｇと一定とし
た場合のサイクル数と放電容量との関係を示す。図１か
ら負極の充電量を一定にすることで負極のサイクル特性
が向上することが分かる。A lithium alloy-based negative electrode material having a higher capacity than that of the graphite material is formed of a carbon material by coating particles of a metal or metalloid forming a lithium alloy as nuclei and coating the particle nuclei with carbon. A composite material in which the metal or metalloid particles are present in a matrix. In this composite material, the carbon layer has a strong binding force that suppresses the volume expansion of the metal or metalloid when forming the lithium alloy. As a result, 500 mAh / g or more and 1500 mAh
/ G is a negative electrode material having a charge capacity of not more than / g and exhibiting cycle durability when the charge capacity is regulated. Figure 1
It will be described based on. FIG. 1 is a diagram showing cycle characteristics of a lithium-silicon alloy-based negative electrode. In FIG. 1, A
Shows the relationship between the number of cycles and the discharge capacity when the potential at the end of charging is fixed at 40 mV based on Li metal. In the same figure, B shows the relationship between the number of cycles and the discharge capacity when the charge amount is constant at 1000 mAh / g. It can be seen from FIG. 1 that the cycle characteristics of the negative electrode are improved by keeping the charge amount of the negative electrode constant.

【００１０】前記のように負極の充電量を規制させるた
めには、正極は次のような条件を満たすものであること
が好ましい。その一つは、理論容量の９０％以上の充電
が可能な正極である。一般的に、正極は理論容量の１０
０％まで充電することはできない。これは、充電末期に
は正極材料中のリチウムイオン量が少なくなり、リチウ
ムイオンの拡散速度が低くなることから分極が上がり電
位が急激に上昇し、充電上限電位に達するためである。
しかし、理論容量の９０％以上の充電は可能であり、こ
のような特徴を示す正極と前記負極とを組み合わせるこ
とによって、正極の充電末期の電位上昇を契機として負
極の充電量を規制することができるという知見を得た。
スピネル型リチウムマンガン複合酸化物が本条件に当て
はまる正極材料の一つである。In order to regulate the charge amount of the negative electrode as described above, the positive electrode preferably satisfies the following conditions. One is a positive electrode capable of charging at least 90% of the theoretical capacity. Generally, the positive electrode has a theoretical capacity of 10
It cannot be charged to 0%. This is because, at the end of charging, the amount of lithium ions in the positive electrode material decreases, and the diffusion rate of lithium ions decreases, whereby polarization rises and the potential rises sharply to reach the charging upper limit potential.
However, it is possible to charge 90% or more of the theoretical capacity, and by combining the positive electrode and the negative electrode exhibiting such characteristics, it is possible to regulate the charge amount of the negative electrode in response to a potential rise at the end of charging of the positive electrode. I learned that I can do it.
Spinel-type lithium manganese composite oxide is one of the positive electrode materials that satisfies these conditions.

【００１１】他の一つには、充電末期においてその電極
電位が急激に上昇するような充電曲線を持つ正極であ
る。前記負極は充電時に体積膨張が起こって微粉化する
ためにインピーダンスがサイクル数とともに変化する傾
向にある。また、充電末期において正極の電位変動が少
ない場合に充電終止電位に基づき充電量を制御した場
合、過充電状態に陥る可能性が大きい。そこで、充電末
期で大きな電位変動が起こる正極と前記負極とを組み合
わせることによって、正極の充電末期で精度良く電池の
充電を終了させ、負極の充電量を一定にさせることがで
きるという知見を得た。ニッケル含有リチウムマンガン
複合酸化物が本条件に当てはまる正極材料の一つであ
る。Another one is a positive electrode having a charging curve such that its electrode potential sharply increases at the end of charging. The impedance of the negative electrode tends to change with the number of cycles because the volume of the negative electrode expands during charging and the powder is pulverized. In addition, when the amount of charge is controlled based on the charge termination potential when the potential change of the positive electrode is small at the end of charging, there is a high possibility that the battery will fall into an overcharged state. Thus, by combining the positive electrode and the negative electrode, in which a large potential change occurs at the end of charging, it has been found that the charging of the battery can be accurately terminated at the end of charging of the positive electrode, and the charge amount of the negative electrode can be kept constant. . Nickel-containing lithium manganese composite oxide is one of the positive electrode materials that meets this condition.

【００１２】上記の考えを、正極材料にＬｉＭｎ2Ｏ4及
びＬｉＣｏＯ2を用い、負極材料に充電量を規制する必
要がある典型的な炭素被覆ケイ素材料を用いて説明す
る。The above concept will be described using LiMn 2 O 4 and LiCoO 2 as the positive electrode material and a typical carbon-coated silicon material which needs to regulate the charge amount as the negative electrode material.

【００１３】負極材料は、リチウム−ケイ素合金材料と
炭素材料との混合系である。従って、負極では下記の２
つの異なる反応が共存する。 Ｓｉ ＋ ｘＬｉ → ＬｉxＳｉ 式（１） ６Ｃ ＋ ｙＬｉ → ＬｉyＣ6 式（２） ケイ素負極は、ｘ＝４.４（Ｌｉ4.4Ｓｉ）まで反応が進
むことが知られており、その理論容量は４１９９ｍＡｈ
／ｇである。また、炭素負極は、ｙ＝１（ＬｉＣ6）ま
で反応が進むことから、その理論容量は３７２ｍＡｈ／
ｇである。前記の混合負極の容量は、２つの容量の和と
なる。即ち、ケイ素がα％含まれた炭素との混合材料の
理論容量は、以下の式から計算される。 混合材料の理論容量（ｍＡｈ／ｇ）＝４１９９×α／１００＋３７２×（１−α ）／１００ 式（３） 例えば、前記２つの材料が１００％反応したとすると、
５０％ケイ素−５０％炭素混合負極の理論容量は、２２
８６ｍＡｈ／ｇと求まる。しかし、その反応はその終止
電位により、ケイ素のリチウム合金化反応とリチウムの
炭素への挿入反応の割合が決定される。その反応の可逆
性は、図１に示すように負極の充電深度に由来し、２０
００ｍＡｈ／ｇの充電ではサイクル耐久性は乏しい。ケ
イ素は、その大きな体積膨張率のため充放電を繰り返す
と粒子の崩壊が起こるため、そのサイクル耐久性は乏し
い。そこで、ケイ素の理論容量の利用率β≦４５％を利
用し、更に炭素をケイ素粒子に被覆することによって、
そのサイクル特性を維持できる。その時の混合材料の利
用率は、下記式で決定される。 混合材料の利用率γ（％）＝〔４１９９×β／１００×α／１００＋３７２×（ １−α）／１００〕／混合電極の理論容量×１００ 式（４） 例えば、そのサイクル特性を維持するためには、ケイ素
が５０％含有している場合、混合材料の利用率は５０％
以下に制御する必要がある。図２に示すように負極の利
用率は５０％以下、即ち１１４３ｍＡｈ／ｇ以下で充電
量を制御する必要がある。そのサイクル耐久性を保持さ
せるためには、負極の充電量を１０００ｍＡｈ／ｇに制
限しなければならない。しかしながら、その初期充電の
電位形状は図２に示すように１００ｍＡｈ／ｇを超えた
ところから、ほぼ一定の電位を示す。また、充電量規制
でサイクルさせた時、サイクル数とともにその充電終止
電位が変動する。従って、定電位充電した場合、その充
電量を一定に規制することは困難である。そこで、正極
で電池の充電量を規制するという手段に到達した。The negative electrode material is a mixture of a lithium-silicon alloy material and a carbon material. Therefore, in the negative electrode, the following 2
Two different reactions coexist. Si + xLi → Li x Si Formula (1) 6C + yLi → Li y C 6 Formula (2) It is known that the reaction of a silicon negative electrode progresses up to x = 4.4 (Li 4.4 Si). Capacity is 4199mAh
/ G. Further, since the reaction of the carbon anode proceeds to y = 1 (LiC 6 ), the theoretical capacity is 372 mAh /
g. The capacity of the mixed negative electrode is the sum of the two capacities. That is, the theoretical capacity of a mixed material with carbon containing α% silicon is calculated from the following equation. Theoretical capacity (mAh / g) of the mixed material = 4199 × α / 100 + 372 × (1-α) / 100 Formula (3) For example, if the two materials react by 100%,
The theoretical capacity of a 50% silicon-50% carbon mixed anode is 22
It is found to be 86 mAh / g. However, the final potential of the reaction determines the ratio of the lithium alloying reaction of silicon and the insertion reaction of lithium into carbon. The reversibility of the reaction is derived from the charge depth of the negative electrode as shown in FIG.
At a charge of 00 mAh / g, the cycle durability is poor. Silicon has poor cycle durability because of its large volume expansion coefficient, repeated charging and discharging causes the particles to collapse. Therefore, by utilizing the utilization ratio β ≦ 45% of the theoretical capacity of silicon, and further coating the silicon particles with carbon,
The cycle characteristics can be maintained. The utilization rate of the mixed material at that time is determined by the following equation. Utilization ratio γ (%) of mixed material = [4199 × β / 100 × α / 100 + 372 × (1-α) / 100] / theoretical capacity of mixed electrode × 100 Equation (4) For example, to maintain the cycle characteristics If the silicon content is 50%, the utilization of the mixed material is 50%
It is necessary to control the following. As shown in FIG. 2, it is necessary to control the charge amount at a utilization rate of the negative electrode of 50% or less, that is, 1143 mAh / g or less. In order to maintain the cycle durability, the charge amount of the negative electrode must be limited to 1000 mAh / g. However, the potential shape of the initial charge exceeds 100 mAh / g as shown in FIG. 2 and shows a substantially constant potential. In addition, when the battery is cycled in accordance with the charge amount regulation, the charge end potential varies with the number of cycles. Therefore, when charging at a constant potential, it is difficult to regulate the charge amount to a constant. Thus, a method has been reached in which the amount of charge of the battery is regulated by the positive electrode.

【００１４】正極で電池の充電量を規制させるために
は、（１）充電末期で正極材料中のリチウムの１００％
近くを利用することができること、又は（２）充電末期
で急激にその電極電位が上昇するという特徴を示す正極
であること、が必要である。In order to regulate the charge amount of the battery with the positive electrode, (1) 100% of lithium in the positive electrode material at the end of charging
It is necessary to be able to use a nearby area, or (2) to be a positive electrode exhibiting a feature that its electrode potential rises sharply at the end of charging.

【００１５】例えば、スピネル型リチウムマンガン複合
酸化物（ＬｉＭｎ2Ｏ4）材料からなる正極が、前記
（１）に該当する一つである。その正極材料の反応を詳
しく述べると、 ＬｉＭｎ2Ｏ4 → Ｌｉ+ ＋ ｅ- ＋ Ｍｎ2Ｏ4 式（５） で表され、その理論容量は１４８ｍＡｈ／ｇとなる。こ
こで、図２にＬｉＭｎ2Ｏ4からなる正極とＬｉ合金系負
極の充放電容量と電位との関係を示す。図２に示すよう
に、正極の電位曲線は充電末期で活性なリチウムイオン
が無くなるために、急激に電位が上昇するという特徴的
な形状を示す。実際には、サイクル特性を向上させたリ
チウム過剰組成のものが実用化されている。ここで、正
極材料と負極材料の質量比（Ｐ／Ｎ）は、図２の矢印で
示すように、下記の関係を満たす必要がある。 正極材料の初期充電量（例えば、１００ｍＡｈ／ｇ）× 正極材料の質量Ｐ（ｇ ）＝ 負極材料が安定にサイクル可能な充電量（例えば、１０００ｍＡｈ／ｇ） × 負極材料の質量Ｎ（ｇ） 式（６） 式（６）より、Ｐ／Ｎ＝１０となる。そこで、Ｐ／Ｎ値
を１０に設定した時、正極材料中のリチウム量を１００
％近く使用でき、且つ正極の電位が充電末期で急激に上
昇することによって、電池電圧も急激に上昇し、それを
契機として充電の終了を確実に行なうことができる。For example, a positive electrode made of a spinel-type lithium manganese composite oxide (LiMn 2 O 4 ) material corresponds to the above (1). The reaction of the positive electrode material is described in detail as follows: LiMn 2 O 4 → Li + + e − + Mn 2 O 4 Formula (5), and the theoretical capacity is 148 mAh / g. Here, FIG. 2 shows the relationship between the charge / discharge capacity and the potential of the positive electrode made of LiMn 2 O 4 and the Li alloy-based negative electrode. As shown in FIG. 2, the potential curve of the positive electrode has a characteristic shape in which the potential rapidly rises because active lithium ions disappear at the end of charging. Actually, a lithium-rich composition having improved cycle characteristics has been put to practical use. Here, the mass ratio (P / N) between the positive electrode material and the negative electrode material needs to satisfy the following relationship as shown by the arrow in FIG. Initial charge amount of positive electrode material (eg, 100 mAh / g) × mass of positive electrode material P (g) = charge amount (eg, 1000 mAh / g) at which negative electrode material can be stably cycled × mass N (g) of negative electrode material (6) From equation (6), P / N = 10. Therefore, when the P / N value is set to 10, the amount of lithium in the cathode material is reduced to 100.
%, And the potential of the positive electrode sharply increases at the end of charging, so that the battery voltage also sharply increases, and as a result, the charging can be surely terminated.

【００１６】また、ニッケル含有リチウムマンガン複合
酸化物（ＬｉＭｎ0.5Ｎｉ0.5Ｏ2）からなる正極は、前
記（２）に該当する一つである。この正極材料は、層構
造を有する複合酸化物であり、充電末期で急激に電位が
上昇する特性を有する。従って、この正極の電位上昇を
契機として充電の終了を確実に行なうことができる。The positive electrode made of nickel-containing lithium manganese composite oxide (LiMn 0.5 Ni 0.5 O 2 ) is one of the above-mentioned (2). This positive electrode material is a composite oxide having a layer structure, and has a characteristic that the potential rapidly increases at the end of charging. Accordingly, the termination of charging can be reliably performed with the potential rise of the positive electrode as a trigger.

【００１７】一方、現在実用化されているＬｉＣｏＯ2
を正極材料に用いた場合、その理論容量は、 ＬｉＣｏＯ2 → Ｌｉ+ ＋ ｅ- ＋ ＣｏＯ2 式（７） より、２７４ｍＡｈ／ｇとなる。実用的には、４．３Ｖ
まで充電した場合、充電量は１６０ｍＡｈ／ｇとなり、
約５８％の利用率となる。また、ＬｉＣｏＯ2材料の充
電曲線は充電終了末期でなだらかに電位上昇を示す特徴
を持つために、前記負極と組み合わせた場合、電池の充
電量を正極の充電量で確実に、効果的に規制することは
できない。On the other hand, LiCoO 2 currently in practical use
When using the positive electrode material, the theoretical capacity, LiCoO 2 → Li + + e - + CoO 2 equation from (7), and 274mAh / g. Practically, 4.3V
If the battery is charged up to 160 mAh / g,
The utilization rate is about 58%. In addition, since the charge curve of the LiCoO 2 material has a characteristic that the potential gradually rises at the end of charging, the charge amount of the battery is reliably and effectively regulated by the charge amount of the positive electrode when combined with the negative electrode. It is not possible.

【００１８】以上のように、本発明の非水二次電池は、
少なくともリチウム−ケイ素合金と炭素から構成される
負極、及び少なくとも金属酸化物リチウム化合物から構
成される正極を備え、前記負極の充電量を下記の関係式
から求められる負極の利用率以下に制御したことを特徴
とする。 負極の利用率（％）＝〔４１９９×β／１００×α／１
００＋３７２×（１−α）／１００〕／〔４１９９×α
／１００＋３７２×（１−α）／１００〕×１００ 但し、αはケイ素の含有率（％）であり、０＜α≦７
０、βはケイ素の利用率であり、０＜β≦４５である。As described above, the non-aqueous secondary battery of the present invention
A negative electrode composed of at least a lithium-silicon alloy and carbon, and a positive electrode composed of at least a metal oxide lithium compound, wherein the charge amount of the negative electrode is controlled to be equal to or less than the utilization rate of the negative electrode obtained from the following relational expression. It is characterized by. Negative electrode utilization rate (%) = [4199 × β / 100 × α / 1
00 + 372 × (1-α) / 100] / [4199 × α
/ 100 + 372 × (1-α) / 100] × 100 where α is the silicon content (%), and 0 <α ≦ 7.
0 and β are the utilization rates of silicon, and 0 <β ≦ 45.

【００１９】また、本発明の非水二次電池は、少なくと
も前記金属酸化物リチウム化合物から構成される正極に
おいて、充電容量の９０％の電位と、１００％の充電状
態の電位との差が５０ｍＶ以上であることが好ましい。Further, in the non-aqueous secondary battery of the present invention, the difference between the potential of 90% of the charged capacity and the potential of the charged state of 100% in the positive electrode composed of at least the lithium metal oxide compound is 50 mV. It is preferable that it is above.

【００２０】また、本発明の非水二次電池は、前記金属
酸化物リチウム化合物が、スピネル型リチウムマンガン
複合酸化物、又はニッケル含有リチウムマンガン複合酸
化物であることが好ましい。In the non-aqueous secondary battery according to the present invention, it is preferable that the lithium metal oxide compound is a spinel-type lithium manganese composite oxide or a nickel-containing lithium manganese composite oxide.

【００２１】[0021]

【発明の実施の形態】以下、本発明の実施の形態につい
て説明する。Embodiments of the present invention will be described below.

【００２２】本発明は、少なくともリチウム−ケイ素合
金と炭素から構成される負極、及び少なくとも金属酸化
物リチウム化合物から構成される正極を備え、前記負極
の充電量を下記の関係式から求められる負極の利用率以
下に制御したことを特徴とする非水二次電池である。 負極の利用率（％）＝〔４１９９×β／１００×α／１
００＋３７２×（１−α）／１００〕／〔４１９９×α
／１００＋３７２×（１−α）／１００〕×１００ 但し、αはケイ素の含有率（％）であり、０＜α≦７
０、βはケイ素の利用率であり、０＜β≦４５である。The present invention comprises a negative electrode composed of at least a lithium-silicon alloy and carbon, and a positive electrode composed of at least a lithium metal oxide compound, and the charge amount of the negative electrode is determined by the following equation. A non-aqueous secondary battery characterized by being controlled to a utilization rate or less. Negative electrode utilization rate (%) = [4199 × β / 100 × α / 1
00 + 372 × (1-α) / 100] / [4199 × α
/ 100 + 372 × (1-α) / 100] × 100 where α is the silicon content (%), and 0 <α ≦ 7.
0 and β are the utilization rates of silicon, and 0 <β ≦ 45.

【００２３】負極の充電量を上記関係から求めた負極の
利用率以下に制御することにより、負極のサイクル特性
を維持することができる。By controlling the charge amount of the negative electrode to be equal to or less than the utilization rate of the negative electrode obtained from the above relationship, the cycle characteristics of the negative electrode can be maintained.

【００２４】前記負極と組み合わせることができる正極
は、金属酸化物リチウム化合物から構成される正極であ
って、充電容量の９０％の電位と、１００％の充電状態
の電位との差が５０ｍＶ以上であることが好ましい。こ
れにより、正極の電位が充電末期で急激に上昇すること
によって、電池電圧も急激に上昇し、それを契機として
充電の終了を行なうことができるので、負極の充電量を
所定量以下に確実に制御することができる。The positive electrode that can be combined with the negative electrode is a positive electrode composed of a lithium metal oxide compound, and the difference between the potential of 90% of the charged capacity and the potential of the charged state of 100% is 50 mV or more. Preferably, there is. As a result, the potential of the positive electrode rises sharply at the end of charging, so that the battery voltage also rises sharply, which can be used to terminate charging. Can be controlled.

【００２５】このような特性を有する正極材料として
は、スピネル型リチウムマンガン複合酸化物であって、
一般式Ｌｉ［ＬｉxＭｅx'Ｍｎ2-x-x'］Ｏ4で表されるも
の、又は層構造を有するニッケル含有リチウムマンガン
複合酸化物であって、一般式Ｌｉ［Ｌｉx+x'Ｍｅy+y'Ｎ
ｉ2-x-yＭｎ2-x'-y'］Ｏ2（Ｍｅは、Ｔｉ、Ｃｒ、Ｆ
ｅ、Ｃｏ、Ｃｕ、Ｚｎ、Ａｌ及びＢからなる群から選択
される少なくとも１種、０≦ｘ≦０．５０、０≦ｘ’≦
０．５０、０≦ｙ≦０．１０、０≦ｙ’≦０．１０）で
表されるものが該当する。The cathode material having such characteristics is a spinel-type lithium manganese composite oxide,
A nickel-containing lithium manganese composite oxide represented by the general formula Li [Li x Me x ' Mn 2-x-x' ] O 4 or a nickel-containing lithium manganese composite oxide having a layer structure, wherein the general formula Li [Li x + x ′ Me y + y ' N
i 2-xy Mn 2-x'-y ' ] O 2 (Me is Ti, Cr, F
e, at least one selected from the group consisting of Co, Cu, Zn, Al and B, 0 ≦ x ≦ 0.50, 0 ≦ x ′ ≦
0.50, 0 ≦ y ≦ 0.10, 0 ≦ y ′ ≦ 0.10).

【００２６】正極用のバインダーには公知の材料、例え
ば、各種ピッチ、ポリテトラフルオロエチレン等が用い
られるが、中でもポリビニリデンフルオライド（ＰＶＤ
Ｆ）やエチレンプロピレンジエンポリマー（ＥＰＤＭ）
やカルボキシルセルロース（ＣＭＣ）が望ましい。更
に、負極には、上記バインダーとともに、負極材料の体
積膨張に適用した弾力性のあるゴム系添加剤、特にスチ
レンブタジエンゴム（ＳＢＲ）を含有させることも望ま
しい。As the binder for the positive electrode, known materials, for example, various pitches, polytetrafluoroethylene and the like are used. Among them, polyvinylidene fluoride (PVD) is used.
F) and ethylene propylene diene polymer (EPDM)
And carboxycellulose (CMC) are desirable. Further, the negative electrode preferably contains, together with the binder, a resilient rubber-based additive applied to the volume expansion of the negative electrode material, particularly styrene-butadiene rubber (SBR).

【００２７】本発明の非水二次電池における非水電解質
としては、有機溶媒に電解質を溶解させた有機溶媒系の
液状電解質、即ち電解液や、前記電解液をポリマー中に
ゲル化して保持させたポリマー電解質などを用いること
ができる。その電解液あるいはポリマー電解質に含まれ
る有機溶媒は特に限定されるものではないが、負荷特性
の点からは鎖状エステルを含んでいることが好ましい。
そのような鎖状エステルとしては、例えば、ジメチルカ
ーボネート（ＤＭＣ）、ジエチルカーボネート（ＤＥ
Ｃ）、エチルメチルカーボネート（ＥＭＣ）、酢酸エチ
ル（ＥＡ）、プロピオン酸メチル（ＭＰ）などの鎖状の
ＣＯＯ−結合を有する有機溶媒が挙げられる。これらの
鎖状エステルは、１種又は２種以上を混合して用いるこ
とができ、特に低温特性を改善するためには、これらの
鎖状エステルが全有機溶媒中の５０体積％以上を占める
ことが好ましく、特に鎖状エステルが全有機溶媒中の６
５体積％以上、とりわけ７５体積％以上を占めることが
好ましい。As the non-aqueous electrolyte in the non-aqueous secondary battery of the present invention, an organic solvent-based liquid electrolyte obtained by dissolving an electrolyte in an organic solvent, that is, an electrolyte, or the electrolyte is gelled and held in a polymer For example, a polymer electrolyte can be used. The organic solvent contained in the electrolytic solution or the polymer electrolyte is not particularly limited, but preferably contains a chain ester from the viewpoint of load characteristics.
Examples of such a chain ester include dimethyl carbonate (DMC) and diethyl carbonate (DE).
Organic solvents having a chain-like COO-bond such as C), ethyl methyl carbonate (EMC), ethyl acetate (EA), and methyl propionate (MP). These chain esters can be used alone or in combination of two or more. In order to improve low-temperature characteristics, in particular, these chain esters should account for 50% by volume or more of the total organic solvent. It is particularly preferable that the chain ester is 6% of the total organic solvent.
Preferably, it accounts for at least 5% by volume, especially at least 75% by volume.

【００２８】但し、有機溶媒としては、前記鎖状エステ
ルのみで構成するよりも、電池容量の向上を図るため
に、前記鎖状エステルに誘電率の高いエステル（誘電率
３０以上のエステル）を混合して用いることが好まし
い。前記誘電率の高いエステルとしては、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）、γ−ブチロラクトン（γ−Ｂ
Ｌ）、エチレングリコールサルファイト（ＥＧＳ）など
が挙げられ、特にエチレンカーボネート、プロピレンカ
ーボネートなどの環状構造のものが好ましい。そのよう
な誘電率の高いエステルは、放電容量の点から全有機溶
媒中の１０体積％以上、特に２０体積％以上含有させる
ことが好ましい。また、負荷特性との両立の点からは、
４０体積％以下が好ましく、２５体積％以下がより好ま
しい。However, as an organic solvent, an ester having a high dielectric constant (an ester having a dielectric constant of 30 or more) is mixed with the chain ester in order to improve the battery capacity as compared with the case of using only the chain ester. It is preferable to use them. Examples of the ester having a high dielectric constant include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), and γ-butyrolactone (γ-B
L), ethylene glycol sulphite (EGS) and the like, and particularly those having a cyclic structure such as ethylene carbonate and propylene carbonate are preferable. Such an ester having a high dielectric constant is preferably contained in an amount of 10% by volume or more, particularly 20% by volume or more in the total organic solvent from the viewpoint of discharge capacity. Also, from the point of compatibility with load characteristics,
It is preferably at most 40% by volume, more preferably at most 25% by volume.

【００２９】また、前記誘電率の高いエステル以外に併
用可能な溶媒としては、例えば、１，２−ジメトキシエ
タン（１，２−ＤＭＥ）、１，３−ジオキソラン（１，
３−ＤＯ）、テトラヒドロフラン（ＴＨＦ）、２−メチ
ル−テトラヒドロフラン（２−Ｍｅ−ＴＨＦ）、ジエチ
ルエーテル（ＤＥＥ）などが挙げられる。そのほか、ア
ミンイミド系有機溶媒や、含イオウ系又は含フッ素系の
有機溶媒なども用いることができる。Examples of the solvent which can be used together with the ester having a high dielectric constant include, for example, 1,2-dimethoxyethane (1,2-DME), 1,3-dioxolane (1,2).
3-DO), tetrahydrofuran (THF), 2-methyl-tetrahydrofuran (2-Me-THF), diethyl ether (DEE) and the like. In addition, an amine imide-based organic solvent, a sulfur-containing or fluorine-containing organic solvent, and the like can also be used.

【００３０】有機溶媒に溶解させる電解質としては、例
えば、ＬｉＣｌＯ4、ＬｉＰＦ6、ＬｉＢＦ4、ＬｉＡｓ
Ｆ6、ＬｉＳｂＦ6、ＬｉＣＦ3ＳＯ3、ＬｉＣ4Ｆ9Ｓ
Ｏ3、ＬｉＣＦ3ＣＯ2、Ｌｉ2Ｃ2Ｆ4（ＳＯ3）2、ＬｉＮ
（ＣＦ3ＳＯ2）2、ＬｉＣ（ＣＦ3ＳＯ2）3、ＬｉＣnＦ
2n+1ＳＯ3（ｎ≧２）などが単独で又は２種以上混合し
て用いられる。中でも、良好な充放電特性が得られるＬ
ｉＰＦ6やＬｉＣ4Ｆ9ＳＯ3などが好ましく用いられる。
電解液中における電解質の濃度は、特に限定されるもの
ではないが、０．３〜１．７ｍｏｌ／ｄｍ3、特に０．
４〜１．５ｍｏｌ／ｄｍ3程度が好ましい。Examples of the electrolyte dissolved in the organic solvent include LiClO 4 , LiPF 6 , LiBF 4 , and LiAs.
F 6 , LiSbF 6 , LiCF 3 SO 3 , LiC 4 F 9 S
O 3 , LiCF 3 CO 2 , Li 2 C 2 F 4 (SO 3 ) 2 , LiN
(CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , LiC n F
2n + 1 SO 3 (n ≧ 2) or the like is used alone or in combination of two or more. Among them, L which can obtain good charge / discharge characteristics
iPF 6 and LiC 4 F 9 SO 3 are preferably used.
The concentration of the electrolyte in the electrolytic solution is not particularly limited, but is 0.3 to 1.7 mol / dm 3 , especially 0.1 to 1.0 mol / dm 3 .
About 4 to 1.5 mol / dm 3 is preferable.

【００３１】セパレータとしては、強度が充分で且つ電
解液を多く保持できるものがよく、そのような観点か
ら、厚さが１０〜５０μｍで、開孔率が３０〜７０％の
ポリプロピレン製、ポリエチレン製、プロピレンとエチ
レンとの共重合体製等の微孔性フィルムや不織布などが
好ましく用いられる。As the separator, a separator having sufficient strength and capable of holding a large amount of electrolyte is preferred. From such a viewpoint, a separator made of polypropylene or polyethylene having a thickness of 10 to 50 μm and a porosity of 30 to 70% is used. , A microporous film made of a copolymer of propylene and ethylene, a nonwoven fabric, and the like are preferably used.

【００３２】[0032]

【実施例】以下、本発明を実施例により具体的に説明す
る。The present invention will be described below in more detail with reference to examples.

【００３３】（実施例１）リチウム合金系負極材料から
なる負極と、Ｌｉ1.05Ｍｎ1.95Ｏ4からなる正極とで構
成される非水二次電池を作製した。Example 1 A non-aqueous secondary battery comprising a negative electrode made of a lithium alloy-based negative electrode material and a positive electrode made of Li 1.05 Mn 1.95 O 4 was prepared.

【００３４】先ず、組成式Ｌｉ1.05Ｍｎ1.95Ｏ4の正極
材料の合成について説明する。この正極材料の合成のた
めに、原料に水酸化リチウムと電解二酸化マンガンの粉
末を用いた。これらの原料を所定量秤量し、エタノール
を溶媒として遊星型ボールミルで混合した。この混合粉
末を乾燥後、ペレット状に成形し、８５０℃で１２時
間、０.３ｃｍ3／分の流量で流した酸素気流中で焼成し
た。そして、このペレットを粉砕して前記正極材料を得
た。なお、以上の合成ではリチウム源として水酸化リチ
ウムを用いたが、炭酸リチウム、硝酸リチウム、酢酸リ
チウム等を用いてもよく、またマンガン源として電解二
酸化マンガンを用いたが、マンガナイト、化学合成二酸
化マンガン、炭酸マンガン等を用いても同様の正極材料
が得られる。この正極材料は立方晶スピネル型リチウム
マンガン複合酸化物である。First, the synthesis of the cathode material of the composition formula Li 1.05 Mn 1.95 O 4 will be described. For the synthesis of this positive electrode material, lithium hydroxide and electrolytic manganese dioxide powder were used as raw materials. These raw materials were weighed in predetermined amounts and mixed with a planetary ball mill using ethanol as a solvent. The mixed powder was dried, formed into pellets, and fired at 850 ° C. for 12 hours in an oxygen stream at a flow rate of 0.3 cm 3 / min. Then, the pellet was pulverized to obtain the positive electrode material. In the above synthesis, lithium hydroxide was used as a lithium source. However, lithium carbonate, lithium nitrate, lithium acetate, etc. may be used, and electrolytic manganese dioxide was used as a manganese source. A similar positive electrode material can be obtained by using manganese, manganese carbonate, or the like. This positive electrode material is a cubic spinel-type lithium manganese composite oxide.

【００３５】また、負極材料としては、ＳｉとＣがモル
比でＳｉ：Ｃ＝１．７：１の割合で混合されている炭素
被覆ケイ素材料を用いた。この負極材料の準備のため
に、平均粒径１μｍのケイ素粉末５００ｇを内容積１０
００ｃｍ3のステンレス容器に挿入し、攪拌しながら窒
素で内部をパージした。この容器内の温度を９５０℃に
昇温後、底部よりベンゼン蒸気を導入して化学蒸着処理
を１２０分間行ない、前記負極材料を得た。As a negative electrode material, a carbon-coated silicon material in which Si and C were mixed at a molar ratio of Si: C = 1.7: 1 was used. In order to prepare this negative electrode material, 500 g of silicon powder having an average particle size of 1 μm was added to an internal volume of
It was inserted into a 00 cm 3 stainless steel container, and the inside was purged with nitrogen while stirring. After the temperature in the container was raised to 950 ° C., benzene vapor was introduced from the bottom and a chemical vapor deposition treatment was performed for 120 minutes to obtain the negative electrode material.

【００３６】次に、電極の作製について説明する。正極
は、前記正極材料を８０質量％、導電材として黒鉛を１
５質量％、バインダーとしてＰＶＤＦを５質量％を混合
したものをアルミニウム箔上に厚さ７０〜１００μｍで
塗布し、Ａｒガス中で１００〜１２０℃で加熱処理した
ものを用いた。また、負極は、前記炭素被覆ケイ素材料
を９５質量％、バインダーとしてＰＶＤＦを５質量％を
混合したものを銅箔上に厚さ３０〜４０μｍで塗布し、
Ａｒガス中で１５０℃以上で加熱処理したものを用い
た。Next, the fabrication of the electrode will be described. The positive electrode was composed of 80% by mass of the positive electrode material and 1% of graphite as a conductive material.
A mixture of 5% by mass and 5% by mass of PVDF as a binder was applied on an aluminum foil to a thickness of 70 to 100 μm, and was subjected to heat treatment at 100 to 120 ° C. in Ar gas. The negative electrode was coated with a mixture of 95% by mass of the carbon-coated silicon material and 5% by mass of PVDF as a binder on a copper foil with a thickness of 30 to 40 μm.
Heat-treated at 150 ° C. or higher in Ar gas was used.

【００３７】前記正極と前記負極との間に配置したセパ
レータには、ポリプロピレン製の２５μｍ厚のものを用
いた。更に、電解液には、エチレンカーボネートとエチ
ルメチルカーボネートの１：２の混合溶液に１．２ｍｏ
ｌ／ｄｍ3のＬｉＰＦ6を溶解したものを用いた。As the separator disposed between the positive electrode and the negative electrode, a polypropylene separator having a thickness of 25 μm was used. Further, the electrolytic solution contained 1.2 mol of a 1: 2 mixed solution of ethylene carbonate and ethyl methyl carbonate.
A solution in which 1 / dm 3 of LiPF 6 was dissolved was used.

【００３８】前記正極は、４．３Ｖの充電末期では活物
質の質量当り１０５ｍＡｈ／ｇの初期充電容量を示す。
また、正極の電極密度は２．７ｇ／ｃｍ3であり、その
配合比率から計算して、電極厚みを１００μｍに調整し
て電極単位面積当り２２．７ｍＡｈ／ｃｍ2の初期充電
容量を示す正極を作製した。また、前記負極は１０００
ｍＡｈ／ｇの容量で充放電サイクルさせる限り、優れた
サイクル耐久性を示すことから、その電極密度１．２ｇ
／ｃｍ3とその配合比率から計算して、電極厚みを２０
μｍに調整し、電極単位面積当りの初期充電容量を正極
容量に等しくなるようにした。これにより、電池の初期
充電容量がその電極単位面積当り２２．７ｍＡｈ／ｃｍ
2になるように設計した。ここで、正極及び負極の体積
当りの放電理論容量（正極材料の体積当りの理論容量と
負極材料の体積当りの理論容量の和）は、１７０ｍＡｈ
／ｃｍ3である。The positive electrode has an initial charge capacity of 105 mAh / g per mass of the active material at the end of charge at 4.3 V.
The electrode density of the positive electrode was 2.7 g / cm 3 , and the electrode thickness was adjusted to 100 μm by calculating from the compounding ratio, and a positive electrode having an initial charge capacity of 22.7 mAh / cm 2 per unit area of the electrode was obtained. Produced. The negative electrode is 1000
As long as the charge / discharge cycle is performed at a capacity of mAh / g, excellent cycle durability is exhibited.
/ Cm 3 and its compounding ratio, the electrode thickness is 20
The initial charge capacity per unit area of the electrode was made equal to the positive electrode capacity. Thereby, the initial charge capacity of the battery is 22.7 mAh / cm per unit area of the electrode.
Designed to be 2 . Here, the theoretical discharge capacity per volume of the positive electrode and the negative electrode (sum of the theoretical capacity per volume of the positive electrode material and the theoretical capacity per volume of the negative electrode material) is 170 mAh.
/ Cm 3 .

【００３９】上記の構成材料を用いてモデルセルを作製
して特性評価を行なった。用いたモデルセルは三極式で
あり、その構成を図３に示す。即ち、正極１と負極２を
対抗させ、その間にセパレータ３をそれぞれ２枚配置し
た。そのセパレータ３の間にリチウム金属を挿入して補
助電極４として用いた。なお、５は正極集電体、６は負
極集電体、７は外枠である。A model cell was prepared using the above constituent materials, and the characteristics were evaluated. The model cell used was of a tripolar type, and its configuration is shown in FIG. That is, the positive electrode 1 and the negative electrode 2 were opposed to each other, and two separators 3 were arranged between them. A lithium metal was inserted between the separators 3 and used as an auxiliary electrode 4. In addition, 5 is a positive electrode current collector, 6 is a negative electrode current collector, and 7 is an outer frame.

【００４０】特性評価は、モデルセル全体をアルゴンを
充填したガラス製の容器に入れて次のように行なった。
充電終止電圧は４．２Ｖとし、０．５ｍＡ／ｃｍ2の一
定電流で充電させ、０．５ｍＡ／ｃｍ2の一定の電流で
３．０Ｖまで放電させることを１サイクルとして、充放
電を繰り返し行なった。The evaluation of the characteristics was performed as follows by placing the entire model cell in a glass container filled with argon.
The charge end voltage was set to 4.2 V, and charging and discharging were repeatedly performed, with charging and discharging at a constant current of 0.5 mA / cm 2 and discharging at a constant current of 0.5 mA / cm 2 to 3.0 V as one cycle. Was.

【００４１】（実施例２）前記実施例１と同じ負極材料
からなる負極と、ＬｉＮｉ0.5Ｍｎ1.5Ｏ4からなる正極
とで構成される非水二次電池を作製した。(Example 2) A non-aqueous secondary battery comprising a negative electrode made of the same negative electrode material as in Example 1 and a positive electrode made of LiNi 0.5 Mn 1.5 O 4 was prepared.

【００４２】組成式ＬｉＮｉ0.5Ｍｎ1.5Ｏ4の正極材料
の合成は次のように行なった。この正極材料の原料に水
酸化リチウム、電解二酸化マンガン、水酸化ニッケルの
粉末を用いた。これらの原料を所定量秤量し、エタノー
ルを溶媒として遊星型ボールミルで混合した。この混合
粉末を乾燥後、ペレット状に成形し、８５０℃で１２時
間、０．３ｃｍ3／分の流量で流した酸素気流中で焼成
した。そして、このペレットを粉砕して前記正極材料を
得た。この正極材料は立方晶スピネル型リチウムマンガ
ン複合酸化物である。The synthesis of the cathode material of the composition formula LiNi 0.5 Mn 1.5 O 4 was carried out as follows. Powders of lithium hydroxide, electrolytic manganese dioxide, and nickel hydroxide were used as raw materials for the positive electrode material. These raw materials were weighed in predetermined amounts and mixed with a planetary ball mill using ethanol as a solvent. After drying this mixed powder, it was formed into a pellet and fired at 850 ° C. for 12 hours in an oxygen stream at a flow rate of 0.3 cm 3 / min. Then, the pellet was pulverized to obtain the positive electrode material. This positive electrode material is a cubic spinel-type lithium manganese composite oxide.

【００４３】前記正極は、４．３Ｖの充電末期では１３
０ｍＡｈ／ｇの初期充電容量を示し、その電極密度が
２．７ｇ／ｃｍ3であることから、負極は実施例１と同
じ手法で作製し、電極厚みを正極１００μｍ、負極３０
μｍに調整した。また、その他の条件は実施例１と同様
とした。これにより、電池の初期充電容量はその電極単
位面積当り２８.０ｍＡｈ／ｃｍ2となる。ここで、正極
及び負極の体積当りの放電理論容量（正極材料の体積当
りの理論容量と負極材料の体積当りの理論容量の和）
は、１９５ｍＡｈ／ｃｍ3である。The positive electrode has a capacity of 13 at the end of the 4.3V charge.
Since the battery exhibited an initial charge capacity of 0 mAh / g and an electrode density of 2.7 g / cm 3 , a negative electrode was prepared in the same manner as in Example 1, and the thickness of the negative electrode was 100 μm, and the thickness of the negative electrode was 30 μm.
It was adjusted to μm. Other conditions were the same as in Example 1. Thereby, the initial charging capacity of the battery is 28.0 mAh / cm 2 per unit area of the electrode. Here, the theoretical discharge capacity per volume of the positive electrode and the negative electrode (sum of the theoretical capacity per volume of the positive electrode material and the theoretical capacity per volume of the negative electrode material)
Is 195 mAh / cm 3 .

【００４４】本実施例で用いた正極材料は、５Ｖ級Ｍｎ
材料として報告されているものであり、リチウム金属基
準で充電終止電位を５．０Ｖ以上としたとき、放電時に
４．６Ｖ以上の作動電位を示す。そこで、実施例１と同
じモデルセルを用いて、充電終止電圧を４．９Ｖ、充電
電流を０．５ｍＡ／ｃｍ2、放電終止電圧を３．０Ｖ、
放電電流を０．５ｍＡ／ｃｍ2に設定して充放電を行な
い、特性を評価した。The cathode material used in this example was a 5V class Mn.
It is reported as a material, and shows an operating potential of 4.6 V or more at the time of discharge when the charge end potential is 5.0 V or more based on lithium metal. Thus, using the same model cell as in Example 1, the charge end voltage was 4.9 V, the charge current was 0.5 mA / cm 2 , the discharge end voltage was 3.0 V,
Charging / discharging was performed with the discharge current set to 0.5 mA / cm 2 , and the characteristics were evaluated.

【００４５】（実施例３）前記実施例１と同じ負極材料
からなる負極と、ＬｉＮｉ0.5Ｍｎ0.5Ｏ2からなる正極
とで構成される非水二次電池を作製した。Example 3 A non-aqueous secondary battery comprising a negative electrode made of the same negative electrode material as in Example 1 and a positive electrode made of LiNi 0.5 Mn 0.5 O 2 was prepared.

【００４６】組成式ＬｉＮｉ0.5Ｍｎ0.5Ｏ2の正極材料
の合成は次のように行なった。Ｎｉ及びＭｎのイオンを
含む水溶液に、室温でＫＯＨ水溶液を加え、沈殿したも
のを２００℃で加熱してＮｉとＭｎの共沈化合物である
水酸化物（Ｎｉ0.5Ｍｎ0.5（ＯＨ）2）を合成した。こ
の水酸化物０．２ｍｏｌと、０．１９８ｍｏｌのＬｉＯ
Ｈ・Ｈ2Ｏとを秤量して混合し、その混合物をエタノー
ルで分散してスラリー状にした後、遊星型ボールミルで
４０分間混合し、室温で乾燥させた。次に、その混合物
をアルミナ製のるつぼに入れ、空気中で８００℃まで加
熱し、その温度で２時間保持することにより予備加熱を
行ない、更に１０００℃に昇温して１２時間焼成し、調
製した酸化物を乳鉢で粉砕して前記正極材料を得た。こ
の正極材料は層構造を有するニッケル含有リチウムマン
ガン複合酸化物である。The synthesis of the positive electrode material of the composition formula LiNi 0.5 Mn 0.5 O 2 was carried out as follows. A KOH aqueous solution is added to an aqueous solution containing ions of Ni and Mn at room temperature, and the precipitate is heated at 200 ° C. to form a hydroxide (Ni 0.5 Mn 0.5 (OH) 2 ) which is a coprecipitated compound of Ni and Mn. Synthesized. 0.2 mol of this hydroxide and 0.198 mol of LiO
It was weighed and mixed and H · H 2 O, after the slurry by dispersing the mixture with ethanol, and mixed for 40 minutes with a planetary ball mill, and dried at room temperature. Next, the mixture was placed in an alumina crucible, heated to 800 ° C. in air, and held at that temperature for 2 hours to perform preheating, and further heated to 1000 ° C. and calcined for 12 hours. The resulting oxide was pulverized in a mortar to obtain the positive electrode material. This positive electrode material is a nickel-containing lithium manganese composite oxide having a layer structure.

【００４７】前記正極は、４．３Ｖの充電末期では１８
０ｍＡｈ／ｇの初期充電容量を示し、その電極密度が
３．１ｇ／ｃｍ3であることから、負極は実施例１と同
じ手法で作製し、電極厚みを正極１００μｍ、負極５０
μｍに調整した。また、その他の条件は実施例１と同様
とした。これにより、電池の初期充電容量はその電極単
位面積当り４４.６ｍＡｈ／ｃｍ2となる。ここで、正極
及び負極の体積当りの放電理論容量（正極材料の体積当
りの理論容量と負極材料の体積当りの理論容量の和）
は、２６７ｍＡｈ／ｃｍ3である。また、特性評価は実
施例１と同じ条件で行なった。At the end of the 4.3 V charge, the positive electrode is 18
Since the battery exhibited an initial charge capacity of 0 mAh / g and an electrode density of 3.1 g / cm 3 , a negative electrode was prepared in the same manner as in Example 1, the electrode thickness was 100 μm, and the negative electrode was 50 μm.
It was adjusted to μm. Other conditions were the same as in Example 1. Thereby, the initial charge capacity of the battery is 44.6 mAh / cm 2 per unit area of the electrode. Here, the theoretical discharge capacity per volume of the positive electrode and the negative electrode (sum of the theoretical capacity per volume of the positive electrode material and the theoretical capacity per volume of the negative electrode material)
Is 267 mAh / cm 3 . Further, the characteristic evaluation was performed under the same conditions as in Example 1.

【００４８】（比較例１）人造黒鉛からなる負極と、Ｌ
ｉ1.05Ｍｎ1.95Ｏ4からなる正極とで構成される非水二
次電池を作製した。(Comparative Example 1) A negative electrode made of artificial graphite and L
A non-aqueous secondary battery composed of a positive electrode composed of i 1.05 Mn 1.95 O 4 was produced.

【００４９】正極は、実施例１と同じ手法で作製した。
また、負極は、前記人造黒鉛を９２質量％、炭素を４質
量％、バインダーとしてＰＶＤＦを４質量％を混合した
ものを銅箔上に厚さ７０〜１００μｍで塗布し、Ａｒガ
ス中で１５０℃以上で加熱処理したものを用いた。ここ
で、負極は、３４０ｍＡｈ／ｇの充電容量を示す。The positive electrode was manufactured in the same manner as in Example 1.
The negative electrode was prepared by applying a mixture of 92% by mass of the artificial graphite, 4% by mass of carbon, and 4% by mass of PVDF as a binder on a copper foil at a thickness of 70 to 100 μm, and the mixture was heated at 150 ° C. in Ar gas. The heat-treated one described above was used. Here, the negative electrode has a charge capacity of 340 mAh / g.

【００５０】前記正極は、４．３Ｖの充電末期では１０
５ｍＡｈ／ｇの初期充電容量を示し、その電極密度が
２．７ｇ／ｃｍ3であり、負極の電極密度は１．５ｇ／
ｃｍ3であることから、電極厚みを正極１００μｍ、負
極６０μｍに調整した。また、その他の条件は実施例１
と同様とした。これにより、電池の初期充電容量はその
電極単位面積当り２２.７ｍＡｈ／ｃｍ2となる。ここ
で、正極及び負極の体積当りの放電理論容量（正極材料
の体積当りの理論容量と負極材料の体積当りの理論容量
の和）は、１２０ｍＡｈ／ｃｍ3である。また、特性評
価は実施例１と同じ条件で行なった。The positive electrode has a potential of 10 at the end of the 4.3V charge.
It shows an initial charge capacity of 5 mAh / g, an electrode density of 2.7 g / cm 3 , and an electrode density of the negative electrode of 1.5 g / cm 3.
cm 3 , the electrode thickness was adjusted to 100 μm for the positive electrode and 60 μm for the negative electrode. Other conditions are the same as those in Example 1.
The same as above. Thereby, the initial charging capacity of the battery is 22.7 mAh / cm 2 per unit area of the electrode. Here, the theoretical discharge capacity per volume of the positive electrode and the negative electrode (sum of the theoretical capacity per volume of the positive electrode material and the theoretical capacity per volume of the negative electrode material) is 120 mAh / cm 3 . Further, the characteristic evaluation was performed under the same conditions as in Example 1.

【００５１】（比較例２）前記比較例１と同じ負極材料
からなる負極と、ＬｉＣｏＯ2からなる正極とで構成さ
れる非水二次電池を作製した。Comparative Example 2 A non-aqueous secondary battery comprising a negative electrode made of the same negative electrode material as in Comparative Example 1 and a positive electrode made of LiCoO 2 was manufactured.

【００５２】正極は、前記正極材料を８０質量％、炭素
を１５質量％、バインダーとしてＰＶＤＦを５質量％を
混合したものをアルミニウム箔上に厚さ７０〜１００μ
ｍで塗布し、Ａｒガス中で１００〜１２０℃で加熱処理
したものを用いた。また、負極は、比較例１と同じ手法
で作製した。The positive electrode was prepared by mixing 80% by mass of the positive electrode material, 15% by mass of carbon, and 5% by mass of PVDF as a binder on an aluminum foil to a thickness of 70 to 100 μm.
m and heated at 100 to 120 ° C. in Ar gas. The negative electrode was manufactured in the same manner as in Comparative Example 1.

【００５３】前記正極は、４．３Ｖの充電末期では１６
０ｍＡｈ／ｇの初期充電容量を示し、その電極密度が
３．２ｇ／ｃｍ3であり、負極の電極密度は１．５ｇ／
ｃｍ3であることから、電極厚みを正極１００μｍ、負
極１００μｍに調整した。また、その他の条件は実施例
１と同様とした。これにより、電池の初期充電容量はそ
の電極単位面積当り４１．０ｍＡｈ／ｃｍ2となる。こ
こで、正極及び負極の体積当りの放電理論容量（正極材
料の体積当りの理論容量と負極材料の体積当りの理論容
量の和）は、１７４ｍＡｈ／ｃｍ3である。また、特性
評価は実施例１と同じ条件で行なった。The positive electrode has a potential of 16 at the end of the 4.3V charge.
It shows an initial charge capacity of 0 mAh / g, an electrode density of 3.2 g / cm 3 , and an electrode density of the negative electrode of 1.5 g / cm 3.
cm 3 , the electrode thickness was adjusted to 100 μm for the positive electrode and 100 μm for the negative electrode. Other conditions were the same as in Example 1. Thus, the initial charge capacity of the battery is 41.0 mAh / cm 2 per unit area of the electrode. Here, the theoretical discharge capacity per volume of the positive electrode and the negative electrode (the sum of the theoretical capacity per volume of the positive electrode material and the theoretical capacity per volume of the negative electrode material) is 174 mAh / cm 3 . Further, the characteristic evaluation was performed under the same conditions as in Example 1.

【００５４】（比較例３）前記実施例１と同じ負極材料
からなる負極と、ＬｉＣｏＯ2からなる正極とで構成さ
れる非水二次電池を作製した。Comparative Example 3 A non-aqueous secondary battery comprising a negative electrode made of the same negative electrode material as in Example 1 and a positive electrode made of LiCoO 2 was produced.

【００５５】正極は、比較例２と同じ手法で作製した。
また、負極は、実施例１と同じ手法で作製した。The positive electrode was produced in the same manner as in Comparative Example 2.
The negative electrode was manufactured in the same manner as in Example 1.

【００５６】前記正極は、４．３Ｖの充電末期では１６
０ｍＡｈ／ｇの初期充電容量を示し、その電極密度が
３．２ｇ／ｃｍ3であり、負極の電極密度は１．２ｇ／
ｃｍ3であることから、電極厚みを正極１００μｍ、負
極４５μｍに調整した。また、その他の条件は実施例１
と同様とした。これにより、電池の初期充電容量はその
電極単位面積当り４１．０ｍＡｈ／ｃｍ2となる。ここ
で、正極及び負極の体積当りの放電理論容量（正極材料
の体積当りの理論容量と負極材料の体積当りの理論容量
の和）は、２５５ｍＡｈ／ｃｍ3である。また、特性評
価は実施例１と同じ条件で行なった。The positive electrode has a potential of 16 at the end of the 4.3V charge.
0 mAh / g initial charge capacity, the electrode density was 3.2 g / cm 3 , and the negative electrode density was 1.2 g / cm 3.
cm 3 , the electrode thickness was adjusted to 100 μm for the positive electrode and 45 μm for the negative electrode. Other conditions are the same as those in Example 1.
The same as above. Thus, the initial charge capacity of the battery is 41.0 mAh / cm 2 per unit area of the electrode. Here, the theoretical discharge capacity per volume of the positive electrode and the negative electrode (the sum of the theoretical capacity per volume of the positive electrode material and the theoretical capacity per volume of the negative electrode material) is 255 mAh / cm 3 . Further, the characteristic evaluation was performed under the same conditions as in Example 1.

【００５７】表１に前記実施例１〜３と比較例１〜３の
正極材料、負極材料、放電容量、負極の充電量、２０サ
イクル後の容量維持率を示す。Table 1 shows the positive electrode material, the negative electrode material, the discharge capacity, the charge amount of the negative electrode, and the capacity retention rate after 20 cycles in Examples 1 to 3 and Comparative Examples 1 to 3.

【００５８】[0058]

【表１】 [Table 1]

【００５９】また、図４に実施例１、３と比較例１、２
の放電曲線を示す。更に、図５に実施例１〜３と比較例
３のサイクル特性を示す。FIG. 4 shows Examples 1 and 3 and Comparative Examples 1 and 2.
2 shows a discharge curve of the sample. FIG. 5 shows the cycle characteristics of Examples 1 to 3 and Comparative Example 3.

【００６０】その電池容量は、実施例１と比較例１との
比較から、負極材料に炭素材料（人造黒鉛）の代わりに
炭素被覆ケイ素を使用することによって単位体積当りの
電池容量は４０％増加したことから、炭素被覆ケイ素材
料は電池の高容量化に効果的であることが分かる。ま
た、実施例１と実施例３との比較から、上記のように高
容量の負極材料である炭素被覆ケイ素を用いることに加
えて、更に高容量の正極材料を用いることによって電池
の高容量化を達成できることも分かる。更に、現在広く
用いられている正極材料であるＬｉＣｏＯ2を用いた場
合にも、比較例１と比較例３との比較から、４０％以上
の容量増加が期待できることが分かる。From the comparison between Example 1 and Comparative Example 1, the battery capacity was increased by 40% by using carbon-coated silicon instead of carbon material (artificial graphite) as the negative electrode material. This indicates that the carbon-coated silicon material is effective for increasing the capacity of the battery. In addition, from the comparison between Example 1 and Example 3, in addition to using carbon-coated silicon, which is a high-capacity negative electrode material, as described above, a higher capacity It can also be seen that can be achieved. Furthermore, even when LiCoO 2 , which is a positive electrode material widely used at present, is used, a comparison between Comparative Example 1 and Comparative Example 3 reveals that a capacity increase of 40% or more can be expected.

【００６１】しかし、比較例１と比較例３との比較か
ら、現在広く用いられている高容量の正極材料であるＬ
ｉＣｏＯ2を用いた場合にも、比較例３の電池のサイク
ル特性の劣化が激しく起こることが分かる。これは比較
例３の負極の充電量が理論容量の６０％を超えているた
めサイクル特性が低下し、且つ負極の充電終了時の電位
変動があるために正極材料が実質的にリチウム金属基準
で４．３Ｖを越えて充電されたためサイクル耐久性が低
下したものと考えられる。However, a comparison between Comparative Example 1 and Comparative Example 3 reveals that the high capacity cathode material L which is widely used at present is used.
It can be seen that even when iCoO 2 was used, the cycle characteristics of the battery of Comparative Example 3 were significantly deteriorated. This is because the charge capacity of the negative electrode of Comparative Example 3 exceeds 60% of the theoretical capacity, the cycle characteristics are reduced, and the potential change at the end of charging the negative electrode causes the positive electrode material to be substantially based on lithium metal. It is considered that the cycle durability was lowered because the battery was charged in excess of 4.3 V.

【００６２】これに対し、実施例１、実施例２のように
理論容量の９０％以上の充電が可能な正極材料を用いた
場合には、炭素被覆ケイ素材料を用いた場合でも良好な
サイクル特性を示すことが分かる。また、実施例３のよ
うに充電末期においてその電極電位が急激に上昇するＬ
ｉＮｉ0.5Ｍｎ0.5Ｏ2を正極材料として用いた場合に
も、実施例１、実施例２と同じように良好なサイクル特
性が得られることが分かる。これは実施例１〜３では負
極の充電量が理論容量の６０％以下であるため、比較例
３のようなサイクル特性の低下が起こらなかったものと
考えられる。On the other hand, when the positive electrode material which can be charged to 90% or more of the theoretical capacity is used as in Examples 1 and 2, good cycle characteristics are obtained even when the carbon-coated silicon material is used. It can be seen that Further, as in the third embodiment, L at which the electrode potential rapidly rises at the end of charging is L
It can be seen that good cycle characteristics can be obtained even when iNi 0.5 Mn 0.5 O 2 is used as the positive electrode material, as in Examples 1 and 2. This is presumably because in Examples 1 to 3, the charge amount of the negative electrode was 60% or less of the theoretical capacity, and thus the cycle characteristics did not decrease as in Comparative Example 3.

【００６３】次に、負極の充電量とサイクル特性との関
係を更に詳細に検討する。即ち、負極の充電量を理論容
量の３０％、４０％、５０％、６０％とした場合につい
て以下で検討した。Next, the relationship between the charge amount of the negative electrode and the cycle characteristics will be discussed in more detail. That is, the case where the charge amount of the negative electrode was set to 30%, 40%, 50%, and 60% of the theoretical capacity was examined below.

【００６４】上述の実施例及び比較例は、ケイ素５０％
と炭素５０％から構成される混合材料を用いていること
から、式（４）よりケイ素の利用率βは、 β／１００＝１．０８９（γ／１００）−０．０８９ 式（８） から求まる。負極の利用率γが５０％ならケイ素の利用
率βは５６．４％、γ＝５０％ならβ＝４５．６％、γ
＝４０％ならβ＝３４．７％、γ＝３０％ならβ＝２
３．８％である。The above-mentioned examples and comparative examples are based on the assumption that 50% silicon is used.
From the formula (4), the utilization factor β of silicon is β / 100 = 1.089 (γ / 100) −0.089 from the formula (8) I get it. If the utilization ratio γ of the negative electrode is 50%, the utilization ratio β of silicon is 56.4%, and if γ = 50%, β = 45.6%, γ
= 40%, β = 34.7%, γ = 30%, β = 2
3.8%.

【００６５】（実施例４）ＬｉＭｎ0.5Ｎｉ0.5Ｏ2から
なる正極と、Ｓｉを５０質量％含んだ炭素被覆ケイ素か
らなる負極とを組み合わせた。用いた正極は４．３Ｖの
充電末期では１７５ｍＡｈ／ｇの初期充電容量を示し、
一方の負極は２０００ｍＡｈ／ｇの初期充電容量を示
す。そこで、正極を初期充電容量の１００％まで充電す
るとして、その時の正極材料と負極材料との質量比を
３．４３〔＝（２０００×３０÷１００）÷１７
５）〕：１として作製することによって、負極の充電量
を理論容量の３０％とした非水二次電池を作製した。な
お、その他の作製条件は、実施例１に準じた。Example 4 A positive electrode made of LiMn 0.5 Ni 0.5 O 2 was combined with a negative electrode made of carbon-coated silicon containing 50% by mass of Si. The positive electrode used had an initial charge capacity of 175 mAh / g at the end of charge at 4.3 V,
One negative electrode has an initial charge capacity of 2000 mAh / g. Therefore, assuming that the positive electrode is charged to 100% of the initial charge capacity, the mass ratio between the positive electrode material and the negative electrode material at that time is 3.43 [= (2000 × 30 ÷ 100) ÷ 17
5)] to produce a non-aqueous secondary battery in which the charge amount of the negative electrode was 30% of the theoretical capacity. The other manufacturing conditions were the same as in Example 1.

【００６６】（実施例５）正極材料と負極材料の質量比
を４．５７：１とすることによって、負極の充電量を理
論容量の４０％としたこと以外は、実施例４と同様にし
て非水二次電池を作製した。Example 5 The procedure of Example 4 was repeated, except that the mass ratio of the positive electrode material to the negative electrode material was set to 4.57: 1 so that the charge amount of the negative electrode was set to 40% of the theoretical capacity. A non-aqueous secondary battery was manufactured.

【００６７】（実施例６）正極材料と負極材料の質量比
を５．７１：１とすることによって、負極の充電量を理
論容量の５０％としたこと以外は、実施例４と同様にし
て非水二次電池を作製した。Example 6 The procedure of Example 4 was repeated, except that the mass ratio of the positive electrode material to the negative electrode material was set to 5.71: 1 so that the charge amount of the negative electrode was set to 50% of the theoretical capacity. A non-aqueous secondary battery was manufactured.

【００６８】（比較例４）正極材料と負極材料の質量比
を６．８５：１とすることによって、負極の充電量を理
論容量の６０％としたこと以外は、実施例４と同様にし
て非水二次電池を作製した。Comparative Example 4 The same procedure as in Example 4 was carried out except that the mass ratio of the positive electrode material to the negative electrode material was 6.85: 1 so that the charge amount of the negative electrode was 60% of the theoretical capacity. A non-aqueous secondary battery was manufactured.

【００６９】上記実施例４〜６及び比較例４の非水二次
電池について、以下の条件でサイクル試験を行なった。The non-aqueous secondary batteries of Examples 4 to 6 and Comparative Example 4 were subjected to a cycle test under the following conditions.

【００７０】初期充電過程において、図２の下図に示す
ように負極の電位は充電開始とともにリチウム金属基準
で１００ｍＶのほぼ一定電位で進む。一方、正極は１７
５ｍＡｈ／ｇの充電時にリチウム金属基準で４．３Ｖに
到達する。そこで、実施例４〜６は正極の容量を１００
％利用（充電量１００％）するために、４．２Ｖの電池
電圧まで充電させた。In the initial charging process, as shown in the lower diagram of FIG. 2, the potential of the negative electrode advances at an almost constant potential of 100 mV on the basis of lithium metal at the start of charging. On the other hand, the positive electrode is 17
When charging at 5 mAh / g, the voltage reaches 4.3 V based on lithium metal. Therefore, in Examples 4 to 6, the capacity of the positive electrode was set to 100
The battery was charged to a battery voltage of 4.2 V in order to use 100% (amount of charge: 100%).

【００７１】負極の２サイクル目以降の充電曲線は初期
充電の形状と異なる。２サイクル目以降の充電曲線は、
充電容量が１４００ｍＡｈ／ｇ（充電量７０％）時に、
リチウム金属基準で１００ｍＶに到達するようになだら
かに電圧が降下していく。そのため、充電終止電圧によ
って負極の充電量（利用率）が決まる。例えば、負極の
充電量を理論容量の３０％にするためには充電終止電圧
は２５０ｍＶ、４０％なら２００ｍＶ、５０％なら１８
０ｍＶ、６０％なら１５０ｍＶ、７０％なら１２０ｍＶ
と負極に含まれるケイ素の量によって規定することがで
きる。The charge curves of the negative electrode after the second cycle are different from the shape of the initial charge. The charge curve after the second cycle is
When the charge capacity is 1400 mAh / g (charge amount 70%),
The voltage gradually drops so as to reach 100 mV based on lithium metal. Therefore, the charge amount (utilization rate) of the negative electrode is determined by the charge end voltage. For example, in order to make the charged amount of the negative electrode 30% of the theoretical capacity, the end-of-charge voltage is 250 mV, 200 mV for 40%, and 18 m for 50%.
0mV, 150mV for 60%, 120mV for 70%
And the amount of silicon contained in the negative electrode.

【００７２】即ち、２サイクル目以降の電池の充電終止
電圧は、負極の充電量が理論容量の３０％なら４．０５
Ｖ（実施例４）、４０％なら４．１０Ｖ（実施例５）、
５０％なら４．１２Ｖ（実施例６）、６０％なら４．１
５Ｖ（比較例４）となる。負極の充電量が理論容量の１
９％以上なら実容量は３８０ｍＡｈ／ｇ以上を示し、炭
素負極の理論容量３７２ｍＡｈ／ｇを越えた高容量負極
となる。That is, the charge end voltage of the battery after the second cycle is 4.05 if the charge amount of the negative electrode is 30% of the theoretical capacity.
V (Example 4), if it is 40%, 4.10 V (Example 5),
4.12 V for 50% (Example 6), 4.1 for 60%
5 V (Comparative Example 4). The charge amount of the negative electrode is 1 of the theoretical capacity.
If it is 9% or more, the actual capacity shows 380 mAh / g or more, and it becomes a high capacity negative electrode exceeding the theoretical capacity of 372 mAh / g of the carbon negative electrode.

【００７３】サイクル試験の結果を図６に示す。図６は
実施例４〜６と比較例４の容量維持率を示した図であ
る。負極の充電量を理論容量の５０％以下に抑えた実施
例４〜６は、３０サイクル後に８０％以上の容量維持率
を有するが、それを超えた６０％の充電量で充放電を繰
り返した比較例４の場合、負極のサイクル劣化が激しく
起こり、急激に容量が低下し、３０サイクル後の容量維
持率は５０％以下になった。FIG. 6 shows the results of the cycle test. FIG. 6 is a diagram showing the capacity retention ratios of Examples 4 to 6 and Comparative Example 4. In Examples 4 to 6 in which the charge amount of the negative electrode was suppressed to 50% or less of the theoretical capacity, the charge retention rate was 80% or more after 30 cycles, but charge / discharge was repeated at a charge amount of 60% which exceeded that. In the case of Comparative Example 4, the cycle deterioration of the negative electrode occurred violently, and the capacity rapidly decreased, and the capacity retention rate after 30 cycles became 50% or less.

【００７４】以上より、負極の充電量を下記の関係式か
ら求められる負極の利用率以下に制御することにより、
サイクル特性に優れた非水二次電池を提供できることが
分かる。 負極の利用率（％）＝〔４１９９×β／１００×α／１
００＋３７２×（１−α）／１００〕／〔４１９９×α
／１００＋３７２×（１−α）／１００〕×１００ 但し、αはケイ素の含有率（％）であり、０＜α≦７
０、βはケイ素の利用率であり、０＜β≦４５である。As described above, by controlling the charge amount of the negative electrode to be equal to or less than the utilization rate of the negative electrode obtained from the following relational expression,
It can be seen that a non-aqueous secondary battery having excellent cycle characteristics can be provided. Negative electrode utilization rate (%) = [4199 × β / 100 × α / 1
00 + 372 × (1-α) / 100] / [4199 × α
/ 100 + 372 × (1-α) / 100] × 100 where α is the silicon content (%), and 0 <α ≦ 7.
0 and β are the utilization rates of silicon, and 0 <β ≦ 45.

【００７５】[0075]

【発明の効果】以上のように、本発明は、少なくともリ
チウム−ケイ素合金と炭素から構成される負極、及び少
なくとも金属酸化物リチウム化合物から構成される正極
を備え、前記負極の充電量を下記の関係式から求められ
る負極の利用率以下に制御した非水二次電池とすること
により、高容量で、サイクル特性に優れた非水二次電池
を提供することができる。 負極の利用率（％）＝〔４１９９×β／１００×α／１
００＋３７２×（１−α）／１００〕／〔４１９９×α
／１００＋３７２×（１−α）／１００〕×１００ 但し、αはケイ素の含有率（％）であり、０＜α≦７
０、βはケイ素の利用率であり、０＜β≦４５である。As described above, the present invention comprises a negative electrode composed of at least a lithium-silicon alloy and carbon, and a positive electrode composed of at least a lithium metal oxide compound. By making the nonaqueous secondary battery controlled to be equal to or less than the utilization rate of the negative electrode obtained from the relational expression, a nonaqueous secondary battery having high capacity and excellent cycle characteristics can be provided. Negative electrode utilization rate (%) = [4199 × β / 100 × α / 1
00 + 372 × (1-α) / 100] / [4199 × α
/ 100 + 372 × (1-α) / 100] × 100 where α is the silicon content (%), and 0 <α ≦ 7.
0 and β are the utilization rates of silicon, and 0 <β ≦ 45.

【図面の簡単な説明】[Brief description of the drawings]

【図１】リチウム−ケイ素合金系負極のサイクル特性を
示した図である。FIG. 1 is a view showing cycle characteristics of a lithium-silicon alloy-based negative electrode.

【図２】ＬｉＭｎ2Ｏ4からなる正極とＬｉ合金系負極の
充放電容量と電位との関係を示した図である。FIG. 2 is a diagram showing the relationship between the charge / discharge capacity and the potential of a positive electrode made of LiMn 2 O 4 and a Li alloy-based negative electrode.

【図３】実施例で用いたモデルセルの構成図である。FIG. 3 is a configuration diagram of a model cell used in the embodiment.

【図４】実施例と比較例の放電曲線を示した図である。FIG. 4 is a diagram showing discharge curves of an example and a comparative example.

【図５】実施例と比較例のサイクル特性を示した図であ
る。FIG. 5 is a diagram showing cycle characteristics of an example and a comparative example.

【図６】実施例と比較例の容量維持率を示した図であ
る。FIG. 6 is a diagram showing a capacity retention ratio of an example and a comparative example.

【符号の説明】[Explanation of symbols]

１ 正極 ２ 負極 ３ セパレータ ４ 補助電極 ５ 正極集電体 ６ 負極集電体 ７ 外枠 Reference Signs List 1 positive electrode 2 negative electrode 3 separator 4 auxiliary electrode 5 positive electrode current collector 6 negative electrode current collector 7 outer frame

───────────────────────────────────────────────────── フロントページの続き Ｆターム(参考） 5H029 AJ03 AJ05 AK03 AL06 AL12 AM02 AM03 AM04 AM05 AM07 HJ01 HJ18 HJ19 5H050 AA07 AA08 BA15 CA08 CA09 CB07 CB12 FA17 FA19 GA10 HA01 HA18 HA19  ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H029 AJ03 AJ05 AK03 AL06 AL12 AM02 AM03 AM04 AM05 AM07 HJ01 HJ18 HJ19 5H050 AA07 AA08 BA15 CA08 CA09 CB07 CB12 FA17 FA19 GA10 HA01 HA18 HA19

Claims (3)

【特許請求の範囲】[Claims] 【請求項１】 少なくともリチウム−ケイ素合金と炭素
から構成される負極、及び少なくとも金属酸化物リチウ
ム化合物から構成される正極を備え、前記負極の充電量
を下記の関係式から求められる負極の利用率以下に制御
したことを特徴とする非水二次電池。 負極の利用率（％）＝〔４１９９×β／１００×α／１
００＋３７２×（１−α）／１００〕／〔４１９９×α
／１００＋３７２×（１−α）／１００〕×１００ 但し、αはケイ素の含有率（％）であり、０＜α≦７
０、βはケイ素の利用率であり、０＜β≦４５である。A negative electrode comprising at least a lithium-silicon alloy and carbon, and a positive electrode comprising at least a lithium metal oxide compound, wherein the charge of the negative electrode is determined by the following relational expression. A non-aqueous secondary battery controlled as follows. Negative electrode utilization rate (%) = [4199 × β / 100 × α / 1
00 + 372 × (1-α) / 100] / [4199 × α
/ 100 + 372 × (1-α) / 100] × 100 where α is the silicon content (%), and 0 <α ≦ 7.
0 and β are the utilization rates of silicon, and 0 <β ≦ 45. 【請求項２】 少なくとも前記金属酸化物リチウム化合
物から構成される正極において、充電容量の９０％の電
位と、１００％の充電状態の電位との差が５０ｍＶ以上
である請求項１に記載の非水二次電池。2. The non-electrolytic device according to claim 1, wherein a difference between a potential of 90% of a charged capacity and a potential of a charged state of 100% of the positive electrode composed of at least the lithium metal oxide compound is 50 mV or more. Water secondary battery. 【請求項３】 前記金属酸化物リチウム化合物が、スピ
ネル型リチウムマンガン複合酸化物、又はニッケル含有
リチウムマンガン複合酸化物である請求項２に記載の非
水二次電池。3. The non-aqueous secondary battery according to claim 2, wherein the lithium metal oxide compound is a spinel-type lithium-manganese composite oxide or a nickel-containing lithium-manganese composite oxide.
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