JP2001283847A - Manufacturing method of positive active material and positive active material as well as lithium secondary battery using same - Google Patents
Manufacturing method of positive active material and positive active material as well as lithium secondary battery using sameInfo
- Publication number
- JP2001283847A JP2001283847A JP2000090928A JP2000090928A JP2001283847A JP 2001283847 A JP2001283847 A JP 2001283847A JP 2000090928 A JP2000090928 A JP 2000090928A JP 2000090928 A JP2000090928 A JP 2000090928A JP 2001283847 A JP2001283847 A JP 2001283847A
- Authority
- JP
- Japan
- Prior art keywords
- active material
- electrode active
- positive electrode
- heat treatment
- lithium
- 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.)
- Pending
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、リチウム二次電池
に使用可能な正極活物質の製造方法とそれにより得られ
た正極活物質、並びにリチウム二次電池に関するもので
ある。The present invention relates to a method for producing a positive electrode active material usable for a lithium secondary battery, a positive electrode active material obtained by the method, and a lithium secondary battery.
【０００２】[0002]
【従来の技術】リチウム二次電池の利用分野は、携帯電
気・電子機器の電源であり、より長時間、充電操作無く
連続使用できること、また、機器寿命に匹敵する期間、
繰り返し充放電可能であることが、リチウム二次電池に
求められている。これらの特性は、電池を構成する部材
中で、正極活物質が支配的に担っている。現在、市販さ
れるリチウム二次電池には、正極活物質として主にリチ
ウム―コバルト酸化物が用いられてきた。2. Description of the Related Art Lithium secondary batteries are used in the field of power supplies for portable electric and electronic devices, and can be used continuously for a longer time without charging operation.
A rechargeable lithium battery is required to be capable of being repeatedly charged and discharged. These characteristics are dominated by the positive electrode active material in the members constituting the battery. At present, lithium-cobalt oxide is mainly used as a positive electrode active material in commercially available lithium secondary batteries.
【０００３】リチウム二次電池の動作は、充電過程に、
正極活物質を構成するリチウムイオンが電解液を介し
て、負極活物質に移動し電力を化学的エネルギーとして
蓄え、放電過程ではその逆反応により電力を発生するも
のである。正極活物質としてリチウム―コバルト酸化
物、負極活物質に炭素系素材を用いる場合、両電極中で
起きるリチウムイオンの脱挿入過程は、固相内拡散を伴
う可逆的な電気化学反応である。製造時、リチウム−コ
バルト酸化物中のコバルトは化学的に３価の状態にある
が、充電により電子を引き出すことで複酸化物中の一部
のコバルトは４価を取り、リチウムが結晶外に拡散移動
する。この反応において、結晶構造中のコバルト―酸素
の骨格に配位数を変える大きな変化を伴わないことが特
徴的である。また、リチウム―コバルト酸化物中のコバ
ルトイオンの酸化還元電位が高いことは、二次電池のエ
ネルギー密度を押し上げる要因である。これにより、正
極活物質にリチウム―コバルト酸化物、負極活物質に炭
素系素材の組み合わせで生ずる４Ｖに近い発生電圧も、
従来リチウム二次電池の大きな特徴である。[0003] The operation of a lithium secondary battery involves a charging process.
Lithium ions constituting the positive electrode active material move to the negative electrode active material via the electrolytic solution and store electric power as chemical energy, and generate electric power by a reverse reaction in a discharging process. When a lithium-cobalt oxide is used as the positive electrode active material and a carbon-based material is used as the negative electrode active material, the process of removing and inserting lithium ions in both electrodes is a reversible electrochemical reaction accompanied by diffusion in a solid phase. At the time of manufacture, cobalt in the lithium-cobalt oxide is chemically in a trivalent state, but by extracting electrons by charging, part of the cobalt in the double oxide takes tetravalent, and lithium moves out of the crystal. Diffusion moves. In this reaction, it is characteristic that the cobalt-oxygen skeleton in the crystal structure is not accompanied by a large change in coordination number. The high oxidation-reduction potential of cobalt ions in the lithium-cobalt oxide is a factor that increases the energy density of the secondary battery. Thereby, the generated voltage close to 4 V generated by the combination of the lithium-cobalt oxide for the positive electrode active material and the carbon-based material for the negative electrode active material is
This is a major feature of conventional lithium secondary batteries.
【０００４】化学式ＬｉＣｏＯ2で表されるリチウム―
コバルト酸化物は上記のように有効な材料ではあるが、
コバルトは稀少かつ高価な資源であり、正極活物質が電
池価格に占める割合は高く、用途拡大に繋がる低価格化
が妨げられている。特に電気自動車、電力貯蔵などの大
型用途では、廉価な活物質の提供が強く望まれている。
これに応える物質として、コバルトほどに電気化学的活
性でかつ、廉価な遷移金属を主成分とするリチウム―マ
ンガン酸化物が注目されている。Lithium represented by the chemical formula LiCoO 2
Although cobalt oxide is an effective material as described above,
Cobalt is a scarce and expensive resource, and the ratio of the positive electrode active material to the battery price is high, which hinders cost reduction leading to expanded use. In particular, for large-sized applications such as electric vehicles and electric power storage, it is strongly desired to provide an inexpensive active material.
As a material corresponding to this, attention has been paid to lithium-manganese oxides which are electrochemically active as much as cobalt and are mainly composed of inexpensive transition metals.
【０００５】[0005]
【発明が解決しようとする課題】正極活物質として有望
視されるリチウム―マンガン酸化物は、化学式ＬｉＭｎ
Ｏ2とＬｉＭｎ2Ｏ4の２種である。ＬｉＭｎＯ2は一般に
層状構造の結晶型であり、ＬｉＭｎ2Ｏ4の結晶型はスピ
ネル構造である。しかし、層状構造のＬｉＭｎＯ2はイ
オン交換による合成手法が知られているが、工業規模の
製造には適さず、目的である廉価な生産と供給は困難で
ある。The lithium-manganese oxide which is promising as a positive electrode active material has a chemical formula of LiMn.
O 2 and LiMn 2 O 4 . LiMnO 2 generally has a layered structure crystal type, and LiMn 2 O 4 has a spinel structure. However, although a synthesis method by ion exchange is known for LiMnO 2 having a layered structure, it is not suitable for production on an industrial scale, and it is difficult to produce and supply the intended inexpensive.
【０００６】また、ＬｉＭｎ2Ｏ4を５０℃以上の高温度
域で使用すると、物質粒子からＭｎ分の溶出を伴い、電
気化学的特性が著しく劣化する。大型電池では運転に伴
う発熱で、中心部の温度が５０℃を越える可能性があ
る。最近、組成を化学量論比よりＬｉ過剰領域にするこ
とで、高温劣化を低減できることが報告されたが、その
改善にともない充放電容量は約１００ｍＡｈ／ｇと大き
く減少する。Further, when LiMn 2 O 4 is used in a high temperature range of 50 ° C. or higher, Mn content is eluted from the material particles, and the electrochemical characteristics are significantly deteriorated. For large batteries, the heat generated during operation may cause the temperature at the center to exceed 50 ° C. Recently, it has been reported that high-temperature deterioration can be reduced by setting the composition in the Li excess region rather than the stoichiometric ratio. However, with the improvement, the charge / discharge capacity is greatly reduced to about 100 mAh / g.
【０００７】また、リチウム―マンガン酸化物をイオン
結晶としてとらえた場合、Ｍｎの３価イオンがヤーン＝
テラー効果により、結晶中に存在するＭｎＯ6の配位多
面体が正八面体から大きく歪んで、Ｍｎの３価イオンの
含有が多い場合に、ＭｎＯ6の配位多面体を結晶単位と
して構成される層状構造やスピネル構造を不安定化する
こと、またその不安定性を緩和するため、欠陥を多く含
んだ結晶となっていると予測される。これら不安定な結
晶と結晶欠陥が、ＬｉＭｎＯ2の合成困難さ、ＬｉＭｎ2
Ｏ4における低価数Ｍｎ状態の利用困難さや高温劣化に
結びついていると考えられる。Further, when lithium-manganese oxide is taken as an ionic crystal, the trivalent ion of Mn is represented by yarn =
Due to the Teller effect, the coordination polyhedron of MnO 6 present in the crystal is greatly distorted from the octahedron, and when the content of trivalent ions of Mn is large, a layered structure composed of the coordination polyhedron of MnO 6 as a crystal unit In order to destabilize the spinel structure and the spinel structure, and to alleviate the instability, it is expected that the crystal has many defects. These unstable crystals and crystal defects are difficult to synthesize LiMnO 2 , LiMn 2
It is considered that this is linked to the difficulty in using the low-valent Mn state in O 4 and deterioration at high temperatures.
【０００８】つまり、大気中で熱処理したＬｉＭｎ2Ｏ4
について化学分析により実験的に求めたＭｎの平均価数
は約３．６３であり、化学量論比から求められる理想値
３．５からずれている。この結果から、Ｌｉが占める結
晶格子点の約２６％、またはＭｎが占める結晶格子点の
約７％程度が空格子点であると予想でき、ＬｉＭｎ2Ｏ4
の結晶は金属欠乏型の点欠陥を格子点の１割程度含んで
いると考えられる。つまり、ＬｉＭｎ2Ｏ4における、Ｍ
ｎを幾つかの遷移金属元素により置換し、その置換効果
を化学的分析と電気化学的評価により繰り返し調べ、高
温劣化は結晶に含有される欠陥に起因すると推察した。That is, LiMn 2 O 4 heat-treated in the air
The average valency of Mn experimentally determined by chemical analysis is about 3.63, which deviates from the ideal value 3.5 determined from the stoichiometric ratio. From this result, it can be expected that about 26% of the crystal lattice points occupied by Li or about 7% of the crystal lattice points occupied by Mn are vacancies, and LiMn 2 O 4
Is considered to contain about 10% of lattice points of metal-deficient point defects. That is, in LiMn 2 O 4 , M
n was substituted by some transition metal elements, and the substitution effect was repeatedly examined by chemical analysis and electrochemical evaluation, and it was presumed that high-temperature deterioration was caused by defects contained in the crystal.
【０００９】例えば、化学式Ｌｉ（Ｍｎ1-yＭｇy）2Ｏ4
（０．０１≦ｙ＜０．１）により表せる活物質では、ヤ
ーン＝テラー・イオンである３価のＭｎをＭｇのイオン
で置換した分、結晶格子の歪みが緩和され、点欠陥を減
少できると考えられ、実験的には高温劣化の減少が見ら
れた。つまり、ｙ＝０．１の場合、実験的に求めたＭｎ
の平均価数はＭｇを２価として約３．７０であり、Ｍｇ
とＭｎを区別しないで求めた平均価数は３．５３とな
り、無添加に比べて空格子点の減少が推定される。しか
し、置換にともない初回充電容量が減少した。これは、
電気化学的酸化還元の反応に関与する３価のＭｎ量が減
少したことに起因するものである。For example, the chemical formula Li (Mn 1-y Mg y ) 2 O 4
In the active material represented by (0.01 ≦ y <0.1), the distortion of the crystal lattice is reduced and the point defects can be reduced by replacing the trivalent Mn, which is the yarn-Teller ion, with the Mg ion. It was considered experimentally that a decrease in high-temperature deterioration was observed. That is, when y = 0.1, Mn obtained experimentally
Is about 3.70 when Mg is divalent.
The average valence obtained without distinguishing between Mn and Mn is 3.53, and it is estimated that the number of vacancies is reduced as compared with the case of no addition. However, the initial charge capacity decreased with the replacement. this is,
This is due to a decrease in the amount of trivalent Mn involved in the electrochemical redox reaction.
【００１０】また、上記欠陥が減少した理想的なＬｉＭ
ｎ2Ｏ4であっても、理論容量が約１４５ｍＡｈ／ｇであ
り、現行のリチウムイオン２次電池の構成でＬｉＣｏＯ
2（約１５０ｍＡｈ／ｇ）を代替えして、電池のエネル
ギー体積密度を同程度に確保することは理論容量を使い
切ることにほぼ等しく難しい。さらに、負極にカーボン
系材料を使用する電池構成の場合、カーボン材料固有の
不可逆容量の存在が電池設計上の条件として考慮する必
要がある。つまり、初回充電時の標準的なカーボン負極
の容量は約３５０ｍＡｈ／ｇであるが、初回放電時と二
回以降の充放電容量は約１割低下する。この不可逆容量
を加味すると、Ｍｎ系スピネル酸化物正極材を使用する
電池の容量はさらに低下して、「高エネルギー密度」と
いうリチウム２次電池の産業上の優位性が著しく阻害さ
れるという課題もある。In addition, an ideal LiM having reduced defects
Even with n 2 O 4 , the theoretical capacity is about 145 mAh / g, and LiCoO 2
2 (approximately 150 mAh / g) and assuring the same energy volume density of the battery is almost as difficult as using up the theoretical capacity. Further, in the case of a battery configuration using a carbon-based material for the negative electrode, it is necessary to consider the existence of the irreversible capacity inherent to the carbon material as a condition in battery design. That is, the standard capacity of the carbon negative electrode at the time of the first charge is about 350 mAh / g, but the charge / discharge capacity at the time of the first discharge and the charge and discharge after the second time is reduced by about 10%. Taking this irreversible capacity into account, the capacity of the battery using the Mn-based spinel oxide cathode material is further reduced, and the problem that the industrial advantage of the lithium secondary battery of “high energy density” is significantly impaired is also raised. is there.
【００１１】本発明はかかる課題を解消するためになさ
れたもので、高温劣化が防止されるとともに、正極の初
回充電時の不可逆容量を増加させ、カーボン負極の不可
逆容量を補償可能な正極活物質の製造方法と正極活物質
を得ることを目的とする。また、高温劣化が少なく、高
容量なリチウム二次電池を得ることを目的とする。SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and a positive electrode active material capable of preventing high-temperature deterioration, increasing the irreversible capacity of the positive electrode during the first charge, and compensating for the irreversible capacity of the carbon negative electrode. It is intended to obtain a positive electrode active material and a method for producing the same. It is another object of the present invention to obtain a high-capacity lithium secondary battery that has little degradation at high temperatures.
【００１２】[0012]
【課題を解決するための手段】本発明に係る第１の正極
活物質の製造方法は、Ｌｉの無機塩と、Ｍｎの無機塩
と、Ｍｇの無機塩とを混合した混合物を得る工程、上記
混合物を酸化性雰囲気中、６００〜９００℃の温度範囲
で熱処理する第１の熱処理工程、並びに第１の熱処理
後、還元性雰囲気中、６００〜９００℃の温度範囲で熱
処理する第２の熱処理工程を施す方法である。The first method for producing a positive electrode active material according to the present invention comprises a step of obtaining a mixture of an inorganic salt of Li, an inorganic salt of Mn and an inorganic salt of Mg. A first heat treatment step in which the mixture is heat-treated in an oxidizing atmosphere at a temperature in the range of 600 to 900 ° C., and a second heat treatment step in which the mixture is heat-treated in a reducing atmosphere at a temperature in the range of 600 to 900 ° C. It is a method of applying.
【００１３】本発明に係る第２の正極活物質の製造方法
は、Ｌｉイオンと、Ｍｎイオンと、Ｍｇイオンとを、各
々ｘ：１−ｙ：ｙ（０．８≦ｘ≦１．１５、０．０１≦
ｙ≦０．１）の比で含有するとともに、Ｌｉ、Ｍｎおよ
びＭｇと錯体を形成する錯化剤を含有した溶液を得る工
程、上記溶液の溶媒を除去して前駆体を得る工程、並び
に上記前駆体を還元性雰囲気中または不活性雰囲気中、
６００〜９００℃の温度範囲で熱処理する工程を施す方
法である。In a second method for producing a positive electrode active material according to the present invention, Li ion, Mn ion, and Mg ion are each converted into x: 1-y: y (0.8 ≦ x ≦ 1.15, 0.01 ≦
a solution containing a complexing agent which forms a complex with Li, Mn and Mg, a step of obtaining a precursor by removing the solvent of the solution, The precursor in a reducing atmosphere or an inert atmosphere,
In this method, a heat treatment is performed in a temperature range of 600 to 900C.
【００１４】本発明に係る第３の正極活物質の製造方法
は、上記第２の正極活物質の製造方法において、前駆体
が、Ｌｉのカルボン酸塩、Ｍｎのカルボン酸塩およびＭ
ｇのカルボン酸塩、またはＬｉ、ＭｎおよびＭｇの複合
カルボン酸塩の方法である。According to a third method for producing a positive electrode active material according to the present invention, in the above-mentioned second method for producing a positive electrode active material, the precursor is a carboxylate of Li, a carboxylate of Mn and M
g, or a complex carboxylate of Li, Mn and Mg.
【００１５】本発明に係る第１の正極活物質は上記第１
ないし第３のいずれかの製造方法により得られ、下記組
成式（１） Ｌｉx（Ｍｎ1-yＭｇy）2Ｏz ・・（１） （但し、０．８≦ｘ≦１．１５、０．０１≦ｙ≦０．
１、４≦ｚ≦４．２）で表され、スピネル構造をとるも
のである。The first positive electrode active material according to the present invention is the first positive electrode active material.
To (1) Li x (Mn 1-y Mg y ) 2 O z. (1) (provided that 0.8 ≦ x ≦ 1.15, 0.01 ≦ y ≦ 0.
1, 4 ≦ z ≦ 4.2) and has a spinel structure.
【００１６】本発明に係る第２の正極活物質は、ＬｉＭ
ｎ2Ｏ4粒子の表面部に上記第１の正極活物質を含有する
層を備えたものである。The second positive electrode active material according to the present invention is LiM
The n 2 O 4 particles are provided with a layer containing the first positive electrode active material on the surface thereof.
【００１７】本発明に係る第１のリチウムイオン二次電
池は、正極活物質層と、負極活物質層と、上記正極およ
び負極活物質層の間にリチウムイオンを含む非水電解質
を保持したセパレータとを備えたリチウムイオン二次電
池において、上記正極活物質層が上記第１または第２の
正極活物質を有するものである。A first lithium ion secondary battery according to the present invention is a separator having a positive electrode active material layer, a negative electrode active material layer, and a nonaqueous electrolyte containing lithium ions between the positive electrode and the negative electrode active material layer. Wherein the positive electrode active material layer has the first or second positive electrode active material.
【００１８】[0018]
【発明の実施の形態】実施の形態１．本発明の第１の実
施の形態の正極活物質の製造方法は、Ｌｉの無機塩と、
Ｍｎの無機塩と、Ｍｇの無機塩とを混合した混合物を得
る工程、上記混合物を酸化性雰囲気中、６００〜９００
℃の温度範囲で熱処理する第１の熱処理工程、並びに第
１の熱処理工程後、還元性雰囲気中で、６００〜９００
℃の温度範囲で熱処理する第２の熱処理工程を施す方法
である。なお、上記第１、第２熱処理工程の熱処理温度
は６００℃未満では反応が起こらず、９００℃を超える
と分解がおこり、７５０〜８５０℃が好ましい。本実施
の形態は、特に上記第１の熱処理を酸化性雰囲気中で行
いその後、上記第２の熱処理を還元雰囲気中で行うこと
により下記本発明の正極活物質を得ることができるとい
うものである。還元性雰囲気としてはＣＯ、Ｈ2雰囲気
または酸素ゲッターとしてのスポンジチタンが用いられ
る。DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 The method for producing a positive electrode active material according to the first embodiment of the present invention comprises the steps of:
A step of obtaining a mixture of an inorganic salt of Mn and an inorganic salt of Mg, and mixing the mixture in an oxidizing atmosphere at 600 to 900;
A first heat treatment step of performing heat treatment in a temperature range of 600 ° C., and after the first heat treatment step, in a reducing atmosphere, at 600 to 900 ° C.
This is a method of performing a second heat treatment step of performing heat treatment in a temperature range of ° C. When the heat treatment temperature in the first and second heat treatment steps is less than 600 ° C., no reaction occurs, and when the heat treatment temperature exceeds 900 ° C., decomposition occurs, and 750 to 850 ° C. is preferable. In the present embodiment, in particular, the following positive electrode active material of the present invention can be obtained by performing the first heat treatment in an oxidizing atmosphere and then performing the second heat treatment in a reducing atmosphere. . As the reducing atmosphere, a CO, H 2 atmosphere or sponge titanium as an oxygen getter is used.
【００１９】実施の形態２．本発明の第２の実施の形態
の正極活物質の製造方法は、Ｌｉイオンと、Ｍｎイオン
と、Ｍｇイオンとを、各々ｘ：１−ｙ：ｙ（０．８≦ｘ
≦１．１５、０．０１≦ｙ≦０．１）の比で含有すると
ともに、Ｌｉ、ＭｎおよびＭｇと錯体を形成する錯化剤
を含有した溶液を得る工程、上記溶液の溶媒を除去して
前駆体を得る工程、並びに上記前駆体を還元性雰囲気中
または不活性雰囲気中で、６００〜９００℃の温度範囲
で熱処理する工程を施す方法である。不活性雰囲気とし
ては、Ｎ2またはＡｒガス雰囲気が用いられる。Embodiment 2 In the method for manufacturing a positive electrode active material according to the second embodiment of the present invention, Li ion, Mn ion, and Mg ion are each converted into x: 1−y: y (0.8 ≦ x
≦ 1.15, 0.01 ≦ y ≦ 0.1) and obtaining a solution containing a complexing agent which forms a complex with Li, Mn and Mg, and removing the solvent of the solution. A step of obtaining a precursor by heating, and a step of subjecting the precursor to a heat treatment in a reducing atmosphere or an inert atmosphere at a temperature in the range of 600 to 900 ° C. As the inert atmosphere, an N 2 or Ar gas atmosphere is used.
【００２０】また、上記前駆体がリチウムのカルボン酸
塩、Ｍｎのカルボン酸塩およびＭｇのカルボン酸塩の混
合物またはＬｉ、ＭｎおよびＭｇの複カルボン酸塩であ
ると、極めて均質性に富み、また水分や溶媒などの不純
物成分が内部に残留していないので、反応が均一かつ速
やかに起こる。If the precursor is a mixture of lithium carboxylate, Mn carboxylate and Mg carboxylate, or a double carboxylate of Li, Mn and Mg, the precursor is extremely homogeneous. Since no impurity components such as water and solvent remain inside, the reaction occurs uniformly and promptly.
【００２１】実施の形態３．本発明の第３の実施の形態
の正極活物質は上記第１または第２の実施の形態の正極
活物質の製造方法により得られたもので、下記組成式
（１） Ｌｉx（Ｍｎ1-yＭｇy）2Ｏz ・・（１） （但し、０．８≦ｘ≦１．１５、０．０１≦ｙ≦０．
１、４≦ｚ≦４．２）で示され、スピネル構造をとるも
のである。式中、ｚが４未満または４．２を越えるとス
ピネル構造をとらず、ｘが０．８未満ではマグネシア等
の未反応相が生じ、１．１５を越えると２種以上の異な
る組成のスピネル結晶相からなる混合相を生じ、ｙが
０．０１未満ではＭｇ添加による効果が小さく、０．１
を越えるとマグネシア等の未反応相が生じ、組成式
（１）で示される組成物の含有率が低下し、工業上の利
用価値が低下する。Embodiment 3 The cathode active material according to the third embodiment of the present invention is obtained by the method for producing the cathode active material according to the first or second embodiment, and has the following composition formula (1): Li x (Mn 1− ) y Mg y ) 2 O z (1) (provided that 0.8 ≦ x ≦ 1.15, 0.01 ≦ y ≦ 0.
1, 4 ≦ z ≦ 4.2) and has a spinel structure. In the formula, when z is less than 4 or more than 4.2, a spinel structure is not formed, and when x is less than 0.8, an unreacted phase such as magnesia is generated. A mixed phase consisting of a crystal phase is produced. When y is less than 0.01, the effect of adding Mg is small, and
If the ratio exceeds m, an unreacted phase such as magnesia is generated, the content of the composition represented by the composition formula (1) decreases, and the industrial utility value decreases.
【００２２】ＬｉＭｎ2Ｏ4は、スピネル構造をとる酸化
物である。結晶構造中でＬｉは結晶学的なシンボル８ａ
に対応する位置を、Ｍｎは結晶学的なシンボル１６ｄに
対応する位置をそれぞれ示す。上記組成式（１）ではＬ
ｉとＭｇが８ａと１６ｄ位置に分布し、熱処理中の雰囲
気により、分布状況が変化する。つまり、Ｍｇが１６ｄ
位置を優先的に占有し、（ ）内を８ａ位置、[ ]内を
１６ｄ位置として原子の位置を明示した式（２） （Ｌｉ）[Ｍｎ1- α - βＭｇαＬｉβ]2Ｏ4 ・・（２） と表現できる状態、またはＭｇが８ａ位置を優先的に占
有し、下記原子の位置を明示した式（３） （Ｌｉ1-2 αＭｇ2 α）[Ｍｎ1- α - βＬｉα + β]2Ｏ4 ・・（３） と表現できる状態となり、結晶構造解析と化学分析およ
び充放電測定の結果から、初回充電時の不可逆容量は式
（３）の状態で生じることがわかった。なお、上記式
（２）、（３）中、αとβは組成式（１）中のｘ、ｙと
下式 α＝３ｙ／（２＋ｘ）、β＝｛３ｘ／（２＋ｘ）−１｝／２ の関係にあり、ｘが１．０程度ではαはｙにほぼ等し
く、βはｘ−１にほぼ等しい。LiMn 2 O 4 is an oxide having a spinel structure. Li is a crystallographic symbol 8a in the crystal structure.
And Mn indicates a position corresponding to the crystallographic symbol 16d. In the above composition formula (1), L
i and Mg are distributed at the 8a and 16d positions, and the distribution changes depending on the atmosphere during the heat treatment. That is, Mg is 16d
Position is preferentially occupied, () in the 8a position, [] was clearly the position of the atoms as 16d located in equation (2) (Li) [Mn 1- α - β Mg α Li β] 2 O 4 Formula (3) (Li 1-2 α Mg 2 α ) [Mn 1 -α - β] in which Mg can be preferentially occupied at position 8a and the position of the following atom is specified. Li α + β ] 2 O 4 ··· (3). From the results of the crystal structure analysis, chemical analysis, and charge / discharge measurement, the irreversible capacity at the time of the first charge may occur in the state of the formula (3). all right. In the above formulas (2) and (3), α and β are x and y in the composition formula (1) and the following formula α = 3y / (2 + x), β = {3x / (2 + x) −1} / 2 where α is approximately equal to y and β is approximately equal to x−1 when x is about 1.0.
【００２３】単元素の無機塩を使用する場合、１回の熱
処理では式（３）の単一相を生成することができないの
で、上記第１の実施の形態の製造方法に示すように、第
１、第２熱処理を行なうことにより組成式（１）で示さ
れ、かつ式（３）の原子位置を有する正極活物質を得る
ことができる。また、第２の実施の形態の製造方法によ
っても、組成式（１）で示され、かつ式（３）の原子位
置を有する正極活物質を得ることができる。When a single element inorganic salt is used, a single heat treatment cannot produce a single phase of the formula (3), and as shown in the manufacturing method of the first embodiment, By performing the first and second heat treatments, a positive electrode active material represented by the composition formula (1) and having the atomic position of the formula (3) can be obtained. Further, also according to the manufacturing method of the second embodiment, a positive electrode active material represented by the composition formula (1) and having the atomic position of the formula (3) can be obtained.
【００２４】上記正極活物質の充放電容量特性を調べた
結果、初回充電で３Ｖ程度の電圧における比較的大きな
不可逆容量分の存在が見出され、かつ高温劣化も減少し
た。高温劣化の抑制度と２回以降の容量値および不可逆
容量分の大きさは、おおむね、ｘとｙが大きいほど、高
温劣化の抑制効果と不可逆容量は大きいが、２回以降の
充放電容量値はＬｉＭｎ2Ｏ4より小さくなる。また、ｙ
がゼロの時、即ちＬｉＭｎ2Ｏ4では不可逆容量が小さ
い。As a result of examining the charge / discharge capacity characteristics of the positive electrode active material, the existence of a relatively large irreversible capacity at a voltage of about 3 V in the initial charge was found, and deterioration at high temperatures was also reduced. The degree of suppression of high-temperature deterioration, and the magnitude of the capacity value and the irreversible capacity after the second time are generally larger as x and y are larger, but the effect of suppressing the high-temperature deterioration and the irreversible capacity are larger, but the charge and discharge capacity values after the second time Is smaller than LiMn 2 O 4 . Also, y
Is zero, that is, LiMn 2 O 4 has a small irreversible capacity.
【００２５】即ち、本実施の形態の正極活物質は、上記
組成式（１）で示される複合酸化物を、上記条件で第２
の熱処理を施すことにより、初回充電容量が大きい状態
を生成して、カーボン負極の不可逆容量を補償し、電池
の実容量低下を抑制することができる。That is, the positive electrode active material of the present embodiment is obtained by converting the composite oxide represented by the composition formula (1) into the second
By performing the heat treatment, a state in which the initial charge capacity is large is generated, the irreversible capacity of the carbon negative electrode is compensated, and a decrease in the actual capacity of the battery can be suppressed.
【００２６】実施の形態４．一般に高温劣化に伴いＬｉ
Ｍｎ2Ｏ4の粒子表面からＭｎが溶出することが報告され
ている。高温劣化は上記のように粉末の結晶欠陥の減少
によって回避できるので、ＬｉＭｎ2Ｏ4の粒子表面に、
上記実施の形態の高温劣化が防止された正極活物質をコ
ーティングすることによっても、溶出量を減少すること
ができる。さらに、安価なＬｉＭｎ2Ｏ4を用いることが
でき、正規のスピネル構造を有するＬｉＭｎ2Ｏ4の初回
充電量を保持したままで、高温劣化を防止することがで
きる。Embodiment 4 In general, Li
It has been reported that Mn elutes from the surface of Mn 2 O 4 particles. Since high-temperature deterioration can be avoided by reducing the crystal defects of the powder as described above, the surface of the LiMn 2 O 4 particles
The elution amount can also be reduced by coating the positive electrode active material in which the high-temperature deterioration of the above embodiment is prevented. Furthermore, inexpensive LiMn 2 O 4 can be used, and high-temperature deterioration can be prevented while maintaining the initial charge amount of LiMn 2 O 4 having a regular spinel structure.
【００２７】実施の形態５．図１は、一般的なリチウム
イオン二次電池の構成図であり、図において、１は正極
活物質層、２は正極集電体、３は正極ケース、４は絶縁
材からなるガスケット、５はリチウムイオンを含む非水
電解液を保持したセパレータ、６は負極活物質層、７は
負極集電体、８は負極ケースで、正極活物質層１と、負
極活物質層６との間にリチウムイオンを含む非水電解質
を保持したセパレータ５を備えたもので、本発明の実施
の形態のリチウムイオン二次電池用正極は、正極活物質
層１に上記実施の形態の正極活物質を含有したものであ
る。正極材料の初回充放電の不可逆容量分が負極材料の
初回充放電の不可逆容量分を補償することができるの
で、極力２回以降の充放電容量値の減少を極力抑えるこ
とができ、負極にカーボン材料を用いた場合に生じる負
極に起因する初回充電時の不可逆容量を補償できるため
に、通常のＭｎ系スピネル酸化物正極材を使用した電池
とくらべて高エネルギー密度の電池は設計し製造でき
る。特にこの正極活物質の原材料のコストがＬｉＣｏＯ
2に比べて安いため、廉価な大型のリチウム２次電池を
市場に提供し、用途拡大をはかれ、また高温劣化を抑制
することができるので、特性が安定する。Embodiment 5 FIG. FIG. 1 is a configuration diagram of a general lithium ion secondary battery, in which 1 is a positive electrode active material layer, 2 is a positive electrode current collector, 3 is a positive electrode case, 4 is a gasket made of an insulating material, and 5 is A separator holding a non-aqueous electrolyte containing lithium ions, 6 is a negative electrode active material layer, 7 is a negative electrode current collector, 8 is a negative electrode case, and lithium is disposed between the positive electrode active material layer 1 and the negative electrode active material layer 6. The positive electrode for a lithium ion secondary battery according to the embodiment of the present invention includes the separator 5 holding a nonaqueous electrolyte containing ions, and the positive electrode active material layer 1 includes the positive electrode active material according to the above embodiment. Things. Since the irreversible capacity of the first charge / discharge of the positive electrode material can compensate for the irreversible capacity of the first charge / discharge of the negative electrode material, the decrease in the charge / discharge capacity after two times can be suppressed as much as possible. Since the irreversible capacity at the time of the first charge caused by the negative electrode caused by using the material can be compensated, a battery having a higher energy density can be designed and manufactured as compared with a battery using an ordinary Mn-based spinel oxide cathode material. In particular, the cost of the raw material of this positive electrode active material is LiCoO
Since it is cheaper than 2 , it can provide inexpensive large-sized lithium secondary batteries to the market, expand applications, and suppress high-temperature deterioration, so that the characteristics are stable.
【００２８】[0028]
【実施例】実施例１〜６、比較例１〜６．出発原料とし
て、炭酸リチウム、二酸化マンガン、並びに炭酸マグネ
シウムもしくは酸化物を用いて、上記各金属イオンが表
１に示す組成比になるように秤取り、メノウ乳鉢中で混
合した。EXAMPLES Examples 1 to 6, Comparative Examples 1 to 6. Using lithium carbonate, manganese dioxide, and magnesium carbonate or oxide as starting materials, each of the above metal ions was weighed so as to have a composition ratio shown in Table 1, and mixed in an agate mortar.
【００２９】[0029]
【表１】 [Table 1]
【００３０】混合物は大気中８００℃で５時間程度保持
の後、室温まで炉冷し反応物をメノウ乳鉢中で粉砕し
た。この粉末の一部はこのまま（比較例４〜６）、また
一部は還元性の３％水素―アルゴンベースガス中で８０
０℃で５時間焼成し室温まで冷却した後粉砕した。The mixture was kept at 800 ° C. in the atmosphere for about 5 hours, cooled in a furnace to room temperature, and pulverized in an agate mortar. A part of this powder was left as it was (Comparative Examples 4 to 6), and a part was powdered in a reducing 3% hydrogen-argon base gas.
The mixture was calcined at 0 ° C. for 5 hours, cooled to room temperature, and then pulverized.
【００３１】上記粉末を、正極活物質としての性能を評
価するために、ガラス容器を用いた評価用のリチウム２
次電池を以下の手順で作製した。まず、評価粉末に約３
重量％のフッ素樹脂系バインダーを混合し、よく練り合
わせ、数ミリグラム程度の少量を約１０φのニッケルメ
ッシュ上に擦り込み、加圧処理して正極板とした。負極
には同形のニッケルメッシュにリチウム金属薄を圧着し
たものを用いた。また、参照極は負極と同じ処理を施し
た小径のニッケルメッシュを用いた。次に、これらの極
板にニッケル線でリードを取って、ガラス容器内部に設
置した。容器内部は電極のメッシュ面が、完全に浸るよ
う電解液で満たした。用いた電解液は、ジメトキシエタ
ンとジエチレンカーボネートの１：１混合溶媒にＬｉＰ
Ｆ6を約１モル／リットルの濃度で溶解させた物であ
る。なお、負極と参照極の準備と電池の組立は、アルゴ
ン置換したグローブボックス内で行った。In order to evaluate the performance of the above-mentioned powder as a positive electrode active material, lithium 2 for evaluation using a glass container was used.
A secondary battery was manufactured in the following procedure. First, about 3
By weight, a fluororesin-based binder was mixed and well kneaded, and a small amount of about several milligrams was rubbed on a nickel mesh of about 10φ, and pressure-treated to prepare a positive electrode plate. The negative electrode used was a nickel mesh having the same shape and a lithium metal thin film pressed thereon. The reference electrode used was a small-diameter nickel mesh treated in the same manner as the negative electrode. Next, a lead was taken from these electrode plates with a nickel wire, and placed inside the glass container. The inside of the container was filled with an electrolyte so that the mesh surface of the electrode was completely immersed. The electrolyte used was LiP in a 1: 1 mixed solvent of dimethoxyethane and diethylene carbonate.
The F 6 is obtained by dissolving at a concentration of about 1 mole / liter. The preparation of the negative electrode and the reference electrode and the assembly of the battery were performed in a glove box replaced with argon.
【００３２】充放電レートは約Ｃ／１０（約１０時間か
けて充電もしくは放電させる条件）として、参照極と正
極の間の電圧が３．０Ｖから４．３Ｖの電圧範囲で、定
電流による充放電を繰り返し評価した。なお、評価は室
温下とホットプレートで加熱し摂氏６０度下で行った。
表にそれらの測定結果をまとめて示す。また、全試料の
結晶構造を粉末Ｘ線回折法により評価した。The charge / discharge rate is about C / 10 (conditions for charging or discharging over about 10 hours), and the voltage between the reference electrode and the positive electrode is in the voltage range of 3.0 V to 4.3 V, and the charging and discharging at a constant current is performed. The discharge was repeatedly evaluated. The evaluation was performed at room temperature and at a temperature of 60 ° C. by heating with a hot plate.
The table summarizes the measurement results. Further, the crystal structures of all the samples were evaluated by the powder X-ray diffraction method.
【００３３】表１中、比較例１、２、３、６は組成が本
発明の請求範囲外にある。また、表中の焼成条件に「大
気＋３％水素」と記してあるものは、一度大気中で焼成
した（第１の熱処理）後、３％水素中で還元処理した
（第２の熱処理）試料である。また、「大気」と記すも
のは、上記第１の熱処理だけのものである。表中の初回
不可逆容量の意味は、初回充電容量と初回放電容量の差
を示し、二回目以降の充放電に伴う差に比べて大きい。In Table 1, Comparative Examples 1, 2, 3, and 6 have compositions outside the scope of the present invention. In the table, the firing conditions indicated as “air + 3% hydrogen” are samples fired once in the air (first heat treatment) and then reduced in 3% hydrogen (second heat treatment). It is. In addition, what is described as “atmosphere” is only the first heat treatment. The meaning of the first irreversible capacity in the table indicates the difference between the first charge capacity and the first discharge capacity, and is larger than the difference accompanying the second and subsequent charge and discharge.
【００３４】表にまとめた結果から、組成が請求範囲内
にある試料では、室温と６０℃での初回および２０回目
の放電容量に大きな差は見られず、高温劣化が改善され
ている。また、初回不可逆容量も明確に観察できた。お
おむね、ｘが大きいほど充放電容量は小さくなり、ｙが
大きいほど、不可逆容量も大きく、不可逆容量の大きさ
は、約１０から２０ｍＡｈ／ｇ程度である。From the results summarized in the table, in the samples whose compositions are within the claimed range, there is no significant difference between the first and 20th discharge capacities at room temperature and 60 ° C., and the high-temperature deterioration is improved. In addition, the first irreversible capacity was clearly observed. In general, the larger x is, the smaller the charge / discharge capacity is, and the larger y is, the larger the irreversible capacity is, and the magnitude of the irreversible capacity is about 10 to 20 mAh / g.
【００３５】一方、比較例ではｘが大きい値の場合（比
較例１）には、高温劣化の抑制効果は見られるが、初回
不可逆容量は小さい。比較例３（ｘ＝１．０）では初回
容量は他に比べて大きいが、高温での劣化も激しい。ま
た、組成が請求範囲にあっても、３％水素中での還元処
理を施さない場合（比較例４〜６）は不可逆容量は小さ
い。また、粉末Ｘ線回折法の結果、表中のいずれの試料
もスピネル構造を有することがわかった。On the other hand, in the comparative example, when x is a large value (Comparative Example 1), the effect of suppressing high-temperature deterioration is seen, but the initial irreversible capacity is small. In Comparative Example 3 (x = 1.0), the initial capacity is larger than the others, but the deterioration at high temperatures is severe. In addition, even if the composition falls within the claimed range, the irreversible capacity is small when the reduction treatment in 3% hydrogen is not performed (Comparative Examples 4 to 6). Further, as a result of the powder X-ray diffraction method, all the samples in the table were found to have a spinel structure.
【００３６】実施例７、８、比較例７．出発原料とし
て、炭酸リチウム、二酸化マンガン、炭酸マグネシウム
を用い、上記各金属イオンが表１に示す組成比になるよ
うに秤取り、メノウ乳鉢中で混合した。Examples 7 and 8, Comparative Example 7. Lithium carbonate, manganese dioxide, and magnesium carbonate were used as starting materials, and the respective metal ions were weighed so as to have a composition ratio shown in Table 1, and mixed in an agate mortar.
【００３７】混合物は大気中８００℃に５時間程度保持
の後、室温まで炉冷し、反応物をメノウ乳鉢中で粉砕し
た。一部はこのまま（比較例７）、一部は圧粉成形して
白金箔に包み、るつぼ中に収めた後、適当量の塊状スポ
ンジチタンを詰めた。次にるつぼは、アルゴン気流中８
００℃に１０時間程度保持の後、室温まで炉冷し、白金
箔に包んだ反応物を粉砕した（実施例７、８）。次に、
上記粉末の正極活物質としての性能を上記実施例と同様
な手法で評価し、表１に示す。The mixture was kept at 800 ° C. in the atmosphere for about 5 hours, cooled in a furnace to room temperature, and crushed in an agate mortar. A part was left as it was (Comparative Example 7), a part was compacted, wrapped in platinum foil, placed in a crucible, and then packed with an appropriate amount of titanium sponge. Next, the crucible is placed in a stream of argon 8
After holding at 00 ° C. for about 10 hours, the reaction mixture was cooled in a furnace to room temperature, and the reaction product wrapped in platinum foil was pulverized (Examples 7 and 8). next,
The performance of the above powder as a positive electrode active material was evaluated by the same method as in the above examples, and is shown in Table 1.
【００３８】表中の焼成条件の「大気＋チタン」の記述
は、一度大気中焼成した（第１の熱処理）後、スポンジ
チタンとともにアルゴン気流中で焼成した（第２の熱処
理）ことを意味する。また、「大気」の記述は、第１の
熱処理だけを施したもので（比較例７）ある。The description of “air + titanium” in the firing conditions in the table means that once firing was performed in the air (first heat treatment), and then firing in an argon stream together with titanium sponge (second heat treatment). . The description of “atmosphere” is obtained by performing only the first heat treatment (Comparative Example 7).
【００３９】図２は室温下で測定した充放電曲線で、本
発明の実施例７または比較例７の正極活物質と、リチウ
ム負極を用いたリチウムイオン二次電池の充放電曲線を
比較して示す特性図である。図中、１ｊは初回充電曲
線、１ｈは初回放電曲線、２ｈは２回目放電曲線であ
る。図から、実施例７には不可逆容量が明確に現れてい
るが、同じ組成の比較例７には不可逆容量が見られな
い。また、実施例７、８の各種データーは実施例３、４
と同等である。FIG. 2 is a charge / discharge curve measured at room temperature, comparing the charge / discharge curves of the positive electrode active material of Example 7 or Comparative Example 7 of the present invention and a lithium ion secondary battery using a lithium negative electrode. FIG. In the figure, 1j is an initial charge curve, 1h is an initial discharge curve, and 2h is a second discharge curve. From the figure, the irreversible capacity clearly appears in Example 7, but no irreversible capacity is observed in Comparative Example 7 having the same composition. Further, various data of Examples 7 and 8 are described in Examples 3 and 4.
Is equivalent to
【００４０】実施例９．硝酸リチウム、硝酸マンガン、
硝酸マグネシウム、無水クエン酸をモル比で１．０５：
０．９５：０．０５：１．０の割合で溶解した水溶液に
した。各金属元素の含有量は実施例３に等しい。この水
溶液をフラスコ中で湯煎しながら減圧乾燥して水飴状の
含水物を得た。減圧乾燥の段階で溶液は脱硝され、得ら
れたものはクエン酸塩の水和物であり、クエン酸のキレ
ート反応により分子レベルの均一混合が行われたと思わ
れる。水飴状の混合物は大気中３００℃で２時間、仮焼
して前駆体とした。前駆体はアルゴン気流中、７５０℃
で５時間、熱処理して試料粉末を得た。この粉末の正極
活物質としての性能を上記実施例と同様な手法で評価し
表１に結果を示す。Embodiment 9 FIG. Lithium nitrate, manganese nitrate,
Magnesium nitrate and citric anhydride in a molar ratio of 1.05:
The resulting solution was dissolved in a ratio of 0.95: 0.05: 1.0. The content of each metal element is the same as in Example 3. This aqueous solution was dried under reduced pressure while being boiled in a flask to obtain a syrupy hydrate. The solution was denitrated in the stage of drying under reduced pressure, and the obtained product was a hydrate of citrate, and it is considered that a uniform mixing at a molecular level was performed by a chelate reaction of citric acid. The syrupy mixture was calcined in air at 300 ° C. for 2 hours to obtain a precursor. The precursor is 750 ° C in an argon stream.
For 5 hours to obtain a sample powder. The performance of this powder as a positive electrode active material was evaluated in the same manner as in the above example, and the results are shown in Table 1.
【００４１】表１に示す実施例９の各種データーが実施
例３と同等であることから、本実施例のようなキレート
反応を用いる合成プロセスによれば、還元性雰囲気中ま
たは不活性雰囲気中（本実施例）、１回の熱処理で所期
活物質を得ることができる。Since the various data of Example 9 shown in Table 1 are equivalent to those of Example 3, according to the synthesis process using the chelate reaction as in this example, in a reducing atmosphere or an inert atmosphere ( (Embodiment) The desired active material can be obtained by one heat treatment.
【００４２】実施例１０．硝酸リチウム、硝酸マンガ
ン、硝酸マグネシウム、無水クエン酸を実施例３の組成
比で水溶液にした。また、あらかじめＬｉＭｎ2Ｏ4の粉
末を準備しておき、造粒装置で上記水溶液を霧状に吹き
込みながら造粒し、赤外線またはレーザーにより瞬時に
加熱および冷却した。この時の加熱は４００℃程の温度
が電気化学的特性上最適である。Embodiment 10 FIG. Lithium nitrate, manganese nitrate, magnesium nitrate, and citric anhydride were made into an aqueous solution at the composition ratio of Example 3. In addition, LiMn 2 O 4 powder was prepared in advance, granulated while blowing the above aqueous solution into a mist with a granulator, and heated and cooled instantaneously by infrared rays or laser. The heating at this time is optimal at a temperature of about 400 ° C. in terms of electrochemical characteristics.
【００４３】得られた粉末は管状炉中に移し、大気中７
５０℃で５時間焼成した後、真空排気して３％水素―ア
ルゴンガスを５００ｍｌ／分程度の流量で流しながら熱
処理した。熱処理温度は約７５０℃で、１時間とした。
冷却過程はできる限り速やかに行った。得られた熱処理
生成物は黒褐色の塊状であり、軽く粉砕処理を行い粉末
状にした。この粉末に対しＸ線回折を行った結果、Ｌｉ
Ｍｎ2Ｏ4の他に格子定数の異なるスピネル型に対応する
弱い回折線があった。粉末を走査型電子顕微鏡で観察し
た結果、数ミクロンの粉体粒子表面が、約０．１ミクロ
ンの厚みの異相で覆われていた。異相について微小領域
の組成分析を行った結果、Ｍｇがほぼ溶液の仕込み組成
で含有していた。The obtained powder was transferred into a tube furnace, and then dried in air.
After calcination at 50 ° C. for 5 hours, heat treatment was performed while evacuating and flowing a 3% hydrogen-argon gas at a flow rate of about 500 ml / min. The heat treatment temperature was about 750 ° C. for one hour.
The cooling process took place as soon as possible. The resulting heat-treated product was a black-brown mass and was lightly pulverized into a powder. X-ray diffraction of this powder showed that Li
In addition to Mn 2 O 4 , there were weak diffraction lines corresponding to spinel types having different lattice constants. Observation of the powder with a scanning electron microscope revealed that the surface of the powder particles of several microns was covered with a heterogeneous phase having a thickness of about 0.1 μm. As a result of analyzing the composition of the minute region with respect to the different phase, it was found that Mg was substantially contained in the charged composition of the solution.
【００４４】この粉末の正極活物質としての性能を実施
例１と同様な電気化学的手法で評価し、結果を表１に示
す。表１から本実施例の正極活物質は、初回容量が約１
３０ｍＡｈ／ｇと高く、しかも、高温劣化が少ないもの
であるとわかる。The performance of this powder as a positive electrode active material was evaluated by the same electrochemical method as in Example 1, and the results are shown in Table 1. Table 1 shows that the positive electrode active material of this example has an initial capacity of about 1
It can be seen that it is as high as 30 mAh / g and has little deterioration at high temperatures.
【００４５】実施例１１．図３は、実施例７または比較
例７の正極活物質とカーボン負極を用いたリチウムイオ
ン二次電池の充放電曲線を比較して示す特性図である。
図から、不可逆容量の小さい比較例７の正極活物質を用
いた場合は、カーボン負極の不可逆容量により、リチウ
ム負極を用いた場合（図２）に比較して２回目の容量値
が小さくなる。一方、実施例７の正極活物質を用いたも
のでは負極の違いによる容量値の差が小さいことが、図
２と図３の比較によりわかる。これは、実施例７の場
合、正極の不可逆容量により、カーボン負極の不可逆容
量が補償された結果であると考えられ、二次電池に充放
電を繰り返した場合の特性の変化が小さく安定である。Embodiment 11 FIG. FIG. 3 is a characteristic diagram showing a comparison between charge and discharge curves of a lithium ion secondary battery using the positive electrode active material of Example 7 or Comparative Example 7 and a carbon negative electrode.
From the figure, when the positive electrode active material of Comparative Example 7 having a small irreversible capacity is used, the second-time capacity value is smaller than that in the case where a lithium negative electrode is used (FIG. 2) due to the irreversible capacity of the carbon negative electrode. On the other hand, it can be seen from a comparison between FIG. 2 and FIG. 3 that in the case of using the positive electrode active material of Example 7, the difference in capacitance value due to the difference in the negative electrode was small. This is considered to be a result of the case where the irreversible capacity of the carbon negative electrode was compensated for by the irreversible capacity of the positive electrode in the case of Example 7, and the change in characteristics when the secondary battery was repeatedly charged and discharged was small and stable. .
【００４６】[0046]
【発明の効果】本発明の第１の正極活物質の製造方法
は、Ｌｉの無機塩と、Ｍｎの無機塩と、Ｍｇの無機塩と
を混合した混合物を得る工程、上記混合物を酸化性雰囲
気中、６００〜９００℃の温度範囲で熱処理する第１の
熱処理工程、並びに第１の熱処理後、還元性雰囲気中、
６００〜９００℃の温度範囲で熱処理する第２の熱処理
工程を施す方法で、高温劣化が抑制され、初回充電時に
不可逆容量を有する正極活物質を得るという効果があ
る。According to the first method for producing a positive electrode active material of the present invention, there is provided a step of obtaining a mixture of an inorganic salt of Li, an inorganic salt of Mn, and an inorganic salt of Mg. And a first heat treatment step of performing a heat treatment in a temperature range of 600 to 900 ° C., and after the first heat treatment, in a reducing atmosphere,
The method of performing the second heat treatment step of performing heat treatment in a temperature range of 600 to 900 ° C. has an effect of suppressing high-temperature deterioration and obtaining a positive electrode active material having an irreversible capacity at the time of first charging.
【００４７】本発明の第２の正極活物質の製造方法は、
Ｌｉイオンと、Ｍｎイオンと、Ｍｇイオンとを、各々
ｘ：１−ｙ：ｙ（０．８≦ｘ≦１．１５、０．０１≦ｙ
≦０．１）の比で含有するとともに、Ｌｉ、Ｍｎおよび
Ｍｇと錯体を形成する錯化剤を含有した溶液を得る工
程、上記溶液の溶媒を除去して前駆体を得る工程、並び
に上記前駆体を還元性雰囲気中または不活性雰囲気中、
６００〜９００℃の温度範囲で熱処理する工程を施す方
法で、高温劣化が抑制され、初回充電時に不可逆容量を
有する正極活物質を得るという効果がある。The second method for producing a positive electrode active material of the present invention comprises:
Li ion, Mn ion, and Mg ion are respectively converted into x: 1-y: y (0.8 ≦ x ≦ 1.15, 0.01 ≦ y
≦ 0.1) to obtain a solution containing a complexing agent that forms a complex with Li, Mn and Mg, a step of removing a solvent of the solution to obtain a precursor, and a step of In a reducing or inert atmosphere,
A method of performing a heat treatment in a temperature range of 600 to 900 ° C. has an effect of suppressing high-temperature deterioration and obtaining a positive electrode active material having an irreversible capacity at the time of initial charging.
【００４８】本発明の第３の正極活物質の製造方法は、
上記第２の正極活物質の製造方法において、前駆体が、
Ｌｉのカルボン酸塩、Ｍｎのカルボン酸塩およびＭｇの
カルボン酸塩、またはＬｉ、ＭｎおよびＭｇの複合カル
ボン酸塩の方法で、反応が均一かつ速やかに起こるとい
う効果がある。The third method for producing a positive electrode active material of the present invention comprises:
In the second method for producing a positive electrode active material, the precursor is
The method of using a carboxylate of Li, a carboxylate of Mn and a carboxylate of Mg, or a complex carboxylate of Li, Mn and Mg has an effect that the reaction occurs uniformly and promptly.
【００４９】本発明の第１の正極活物質は、上記第１な
いし第３のいずれかの正極活物質の製造方法により得ら
れ、下記組成式（１） Ｌｉx（Ｍｎ1-yＭｇy）2Ｏz ・・（１） （但し、０．８≦ｘ≦１．１５、０．０１≦ｙ≦０．
１、４≦ｚ≦４．２）で表され、スピネル構造をとるも
ので、高温劣化が抑制され、初回充電時に不可逆容量を
有するという効果がある。The first positive electrode active material of the present invention is obtained by any one of the first to third methods for producing a positive electrode active material, and has the following composition formula (1): Li x (Mn 1-y Mg y ) 2 O z (1) (provided that 0.8 ≦ x ≦ 1.15, 0.01 ≦ y ≦ 0.
1, 4 ≦ z ≦ 4.2), which has a spinel structure, has an effect of suppressing high-temperature deterioration and having an irreversible capacity at the time of initial charging.
【００５０】本発明の第２の正極活物質は、ＬｉＭｎ2
Ｏ4粒子の表面部に上記第１の正極活物質を含有する層
を備えたもので、高温劣化が抑制され、かつ容量の減少
が押さえられた正極活物を製造できるという効果があ
る。The second positive electrode active material of the present invention is LiMn 2
Since a layer containing the first positive electrode active material is provided on the surface portion of the O 4 particles, there is an effect that a high-temperature active material in which deterioration at high temperatures is suppressed and a decrease in capacity is suppressed can be produced.
【００５１】本発明の第１のリチウムイオン二次電池
は、正極活物質層と、負極活物質層と、上記正極および
負極活物質層の間にリチウムイオンを含む非水電解質を
保持したセパレータとを備えたリチウムイオン二次電池
において、上記正極活物質層が上記第１または第２の正
極活物質を有するもので、コストが安く、負極に起因す
る初回充電時の不可逆容量を補償でき高エネルギー密度
となるという効果がある。The first lithium ion secondary battery of the present invention comprises a positive electrode active material layer, a negative electrode active material layer, and a separator holding a non-aqueous electrolyte containing lithium ions between the positive electrode and the negative electrode active material layer. In the lithium ion secondary battery provided with the above, the positive electrode active material layer has the first or second positive electrode active material, the cost is low, and the irreversible capacity at the time of the first charge caused by the negative electrode can be compensated. This has the effect of increasing the density.
【図１】 一般的なコイン電池の構成図である。FIG. 1 is a configuration diagram of a general coin battery.
【図２】 本発明の実施例７または比較例７の正極活物
質と、リチウム負極を用いたリチウムイオン二次電池の
充放電曲線を比較して示す特性図である。FIG. 2 is a characteristic diagram showing a comparison between charge and discharge curves of a positive electrode active material of Example 7 or Comparative Example 7 of the present invention and a lithium ion secondary battery using a lithium negative electrode.
【図３】 本発明の実施例７または比較例７の正極活物
質と、カーボン負極を用いたリチウムイオン二次電池の
充放電曲線を比較して示す特性図である。FIG. 3 is a characteristic diagram showing a comparison between charge and discharge curves of a positive electrode active material of Example 7 or Comparative Example 7 of the present invention and a lithium ion secondary battery using a carbon negative electrode.
１ 正極活物質層、２ 正極集電体、３ 正極ケース、
５ リチウムイオンを含む非水電解液を保持したセパレ
ータ、６ 負極活物質層、７ 負極集電体、８負極ケー
ス。1 positive electrode active material layer, 2 positive electrode current collector, 3 positive electrode case,
5 Separator holding a non-aqueous electrolyte containing lithium ions, 6 Negative electrode active material layer, 7 Negative current collector, 8 Negative case.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 宮下 章志 東京都千代田区丸の内二丁目２番３号 三 菱電機株式会社内 Ｆターム(参考） 4G048 AA04 AA05 AB02 AB05 AC06 AE05 AE08 5H029 AJ03 AJ14 AK03 AL06 AM03 AM04 AM05 AM07 BJ03 BJ16 CJ02 CJ28 DJ12 DJ16 DJ17 HJ02 HJ14 5H050 AA08 AA19 BA17 CA09 CB07 FA12 FA18 FA19 GA02 GA12 GA26 GA27 HA02 HA14 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Miyashita 2-3-2 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) in Mitsubishi Electric Corporation 4G048 AA04 AA05 AB02 AB05 AC06 AE05 AE08 5H029 AJ03 AJ14 AK03 AL06 AM03 AM04 AM05 AM07 BJ03 BJ16 CJ02 CJ28 DJ12 DJ16 DJ17 HJ02 HJ14 5H050 AA08 AA19 BA17 CA09 CB07 FA12 FA18 FA19 GA02 GA12 GA26 GA27 HA02 HA14
Claims (6)
の無機塩とを混合した混合物を得る工程、上記混合物を
酸化性雰囲気中、６００〜９００℃の温度範囲で熱処理
する第１の熱処理工程、並びに第１の熱処理後、還元性
雰囲気中、６００〜９００℃の温度範囲で熱処理する第
２の熱処理工程を施す正極活物質の製造方法。1. An inorganic salt of Li, an inorganic salt of Mn, Mg
Obtaining a mixture obtained by mixing the above-mentioned mixture with an inorganic salt, a first heat treatment step of heat-treating the mixture in an oxidizing atmosphere at a temperature in the range of 600 to 900 ° C., and after the first heat treatment, in a reducing atmosphere. A method for producing a positive electrode active material, wherein a second heat treatment step of performing heat treatment in a temperature range of 900 ° C. is performed.
ンとを、各々ｘ：１−ｙ：ｙ（０．８≦ｘ≦１．１５、
０．０１≦ｙ≦０．１）の比で含有するとともに、Ｌ
ｉ、ＭｎおよびＭｇと錯体を形成する錯化剤を含有した
溶液を得る工程、上記溶液の溶媒を除去して前駆体を得
る工程、並びに上記前駆体を還元性雰囲気中または不活
性雰囲気中、６００〜９００℃の温度範囲で熱処理する
工程を施す正極活物質の製造方法。2. The method according to claim 1, wherein the Li ion, the Mn ion, and the Mg ion are respectively x: 1−y: y (0.8 ≦ x ≦ 1.15,
0.01 ≦ y ≦ 0.1).
i, a step of obtaining a solution containing a complexing agent that forms a complex with Mn and Mg, a step of removing a solvent of the solution to obtain a precursor, and a step of reducing the precursor in a reducing atmosphere or an inert atmosphere; A method for producing a positive electrode active material, wherein a heat treatment is performed in a temperature range of 600 to 900 ° C.
カルボン酸塩およびＭｇのカルボン酸塩、またはＬｉ、
ＭｎおよびＭｇの複合カルボン酸塩であることを特徴と
する請求項２に記載の正極活物質の製造方法。3. The precursor is a carboxylate of Li, a carboxylate of Mn and a carboxylate of Mg, or Li,
The method for producing a positive electrode active material according to claim 2, wherein the method is a complex carboxylate of Mn and Mg.
載の製造方法により得られ、下記組成式（１） Ｌｉx（Ｍｎ1-yＭｇy）2Ｏz ・・（１） （但し、０．８≦ｘ≦１．１５、０．０１≦ｙ≦０．
１、４≦ｚ≦４．２）で表され、スピネル構造をとる正
極活物質。4. A composition obtained by the production method according to claim 1 and having the following composition formula (1): Li x (Mn 1 -y Mg y ) 2 O z .. (1) , 0.8 ≦ x ≦ 1.15, 0.01 ≦ y ≦ 0.
1, 4 ≦ z ≦ 4.2), and a positive electrode active material having a spinel structure.
記載の正極活物質を含有する層を備えた正極活物質。5. A positive electrode active material comprising a layer containing the positive electrode active material according to claim 4 on the surface of LiMn 2 O 4 particles.
正極および負極活物質層の間にリチウムイオンを含む非
水電解質を保持したセパレータとを備えたリチウムイオ
ン二次電池において、上記正極活物質層が請求項４また
は請求項５に記載の正極活物質を有することを特徴とす
るリチウムイオン二次電池。6. A lithium ion secondary battery comprising a positive electrode active material layer, a negative electrode active material layer, and a separator holding a nonaqueous electrolyte containing lithium ions between the positive electrode and the negative electrode active material layer. A lithium ion secondary battery, wherein the positive electrode active material layer has the positive electrode active material according to claim 4.
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002226213A (en) * | 2001-01-25 | 2002-08-14 | Nippon Chem Ind Co Ltd | Lithium manganese complex oxide powder, its production method, cathode active material for lithium secondary cell, and lithium secondary cell |
| JP2005231914A (en) * | 2004-02-17 | 2005-09-02 | Nippon Chem Ind Co Ltd | Method for manufacturing lithium manganate |
| WO2005096416A1 (en) * | 2004-04-02 | 2005-10-13 | Seimi Chemical Co., Ltd. | Process for producing lithium-containing composite oxide for positive electrode of lithium secondary battery |
| JPWO2005112152A1 (en) * | 2004-05-14 | 2008-03-27 | Ａｇｃセイミケミカル株式会社 | Method for producing lithium-containing composite oxide for positive electrode of lithium secondary battery |
| JP2008198553A (en) * | 2007-02-15 | 2008-08-28 | National Institute Of Advanced Industrial & Technology | Active material for lithium cell, its manufacturing method, and lithium cell using the active material |
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| JP2002226213A (en) * | 2001-01-25 | 2002-08-14 | Nippon Chem Ind Co Ltd | Lithium manganese complex oxide powder, its production method, cathode active material for lithium secondary cell, and lithium secondary cell |
| JP2005231914A (en) * | 2004-02-17 | 2005-09-02 | Nippon Chem Ind Co Ltd | Method for manufacturing lithium manganate |
| WO2005096416A1 (en) * | 2004-04-02 | 2005-10-13 | Seimi Chemical Co., Ltd. | Process for producing lithium-containing composite oxide for positive electrode of lithium secondary battery |
| JP4833058B2 (en) * | 2004-04-02 | 2011-12-07 | Ａｇｃセイミケミカル株式会社 | Method for producing lithium-containing composite oxide for positive electrode of lithium secondary battery |
| US8101143B2 (en) | 2004-04-02 | 2012-01-24 | Seimi Chemical Co., Ltd. | Process for producing lithium-containing composite oxide for positive electrode for lithium secondary battery |
| JPWO2005112152A1 (en) * | 2004-05-14 | 2008-03-27 | Ａｇｃセイミケミカル株式会社 | Method for producing lithium-containing composite oxide for positive electrode of lithium secondary battery |
| JP4666653B2 (en) * | 2004-05-14 | 2011-04-06 | Ａｇｃセイミケミカル株式会社 | Method for producing lithium-containing composite oxide for positive electrode of lithium secondary battery |
| JP2008198553A (en) * | 2007-02-15 | 2008-08-28 | National Institute Of Advanced Industrial & Technology | Active material for lithium cell, its manufacturing method, and lithium cell using the active material |
| JP2011501699A (en) * | 2007-10-01 | 2011-01-13 | ジョンソン、マッセイ、パブリック、リミテッド、カンパニー | Improvements to produce shape memory alloy tubes by drawing |
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| WO2010038424A1 (en) * | 2008-10-01 | 2010-04-08 | 戸田工業株式会社 | Lithium manganate powder for nonaqueous electrolyte secondary battery, method for producing same, and nonaqueous electrolyte secondary battery |
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