JP2000353523A - Positive electrode active material for nonaqueous secondary battery, its manufacture, and nonaqueous secondary battery - Google Patents
Positive electrode active material for nonaqueous secondary battery, its manufacture, and nonaqueous secondary batteryInfo
- Publication number
- JP2000353523A JP2000353523A JP11162987A JP16298799A JP2000353523A JP 2000353523 A JP2000353523 A JP 2000353523A JP 11162987 A JP11162987 A JP 11162987A JP 16298799 A JP16298799 A JP 16298799A JP 2000353523 A JP2000353523 A JP 2000353523A
- Authority
- JP
- Japan
- Prior art keywords
- positive electrode
- active material
- secondary battery
- composite oxide
- electrode active
- 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.)
- Granted
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、サイクル寿命に優
れた、非水系２次電池用正極活物質、その製造方法及び
該正極活物質を備えた非水系２次電池に関する。The present invention relates to a positive electrode active material for a non-aqueous secondary battery having excellent cycle life, a method for producing the same, and a non-aqueous secondary battery provided with the positive electrode active material.
【０００２】[0002]
【従来技術】近年、軽量且つ高容量の電池として、リチ
ウムイオン２次電池をはじめとする非水電解質の２次電
池が注目されている。この２次電池は、リチウム、遷移
金属及び酸素を含む複合酸化物を正極活物質として使用
するため、充放電を繰り返すことにより、正極活物質の
結晶構造が急激に崩壊してしまい、サイクル寿命が低下
するという問題が指摘されている。また、この２次電池
の電解質としては、プロピレンカーボネート、ジメチル
カーボネート等の溶媒に、ＬｉＰＦ6等を溶解した非水
系電解質が使用されるため、この非水系電解質が高電位
の正極側において、活性な正極活物質表面と反応して分
解され、サイクル寿命が低下するという問題も指摘され
ている。そこで、このようなサイクル寿命を改善するた
めに種々の提案がなされている。例えば、特開平６−２
４３８７１号公報には、正極活物質としての複合酸化物
中の酸素の一部を、フッ素で置換することにより、充放
電時における正極活物質の結晶崩壊を抑制する技術が提
案されている。しかし、この技術では、複合酸化物の結
晶格子中にフッ素を導入することによって、複合酸化物
の結晶構造の崩壊によるサイクル寿命は改善されるもの
の、容量が低下するという問題が生じる。一方、特開平
８−２３６１１４号公報には、正極表面に特定の金属酸
化物皮膜を形成し、正極の表面活性を制御することによ
り非水系電解質の分解を抑制する技術が提案されてい
る。しかし、この技術では、正極表面に金属酸化物の皮
膜を形成するために、ＣＶＤやスパッタリング等を行な
う必要があり、工程が煩雑化すると共に、正極内部での
電解液の分解までは抑制できないという問題がある。2. Description of the Related Art In recent years, attention has been paid to non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries as lightweight and high-capacity batteries. Since this secondary battery uses a composite oxide containing lithium, a transition metal and oxygen as a positive electrode active material, the charge and discharge are repeated, whereby the crystal structure of the positive electrode active material is rapidly collapsed, and the cycle life is shortened. It has been pointed out that the problem is reduced. Further, as the electrolyte of the secondary battery, a non-aqueous electrolyte in which LiPF 6 or the like is dissolved in a solvent such as propylene carbonate or dimethyl carbonate is used. Therefore, the non-aqueous electrolyte is active on the high potential positive electrode side. It has also been pointed out that it is decomposed by reacting with the surface of the positive electrode active material and the cycle life is shortened. Therefore, various proposals have been made to improve such cycle life. For example, JP-A-6-2
Japanese Patent No. 43871 proposes a technique for suppressing crystal collapse of a positive electrode active material during charge and discharge by substituting a part of oxygen in a composite oxide as a positive electrode active material with fluorine. However, in this technique, by introducing fluorine into the crystal lattice of the composite oxide, although the cycle life due to the collapse of the crystal structure of the composite oxide is improved, there is a problem that the capacity is reduced. On the other hand, JP-A-8-236114 proposes a technique in which a specific metal oxide film is formed on the surface of a positive electrode and the surface activity of the positive electrode is controlled to suppress the decomposition of a non-aqueous electrolyte. However, in this technique, it is necessary to perform CVD, sputtering, or the like in order to form a metal oxide film on the positive electrode surface, which complicates the process and cannot suppress the decomposition of the electrolytic solution inside the positive electrode. There's a problem.
【０００３】[0003]
【発明が解決しようとする課題】従って、本発明の目的
は、電池容量の低下を抑制すると共に、正極表面の活性
を制御し、サイクル寿命を向上させることができる非水
系２次電池用正極活物質及びその製造方法を提供するこ
とにある。本発明の別の目的は、電池容量の低下を抑制
すると共に、サイクル寿命に優れた非水系２次電池を提
供することにある。SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a positive electrode active material for a non-aqueous secondary battery capable of suppressing a decrease in battery capacity, controlling the activity of the positive electrode surface, and improving cycle life. An object of the present invention is to provide a substance and a method for producing the same. Another object of the present invention is to provide a non-aqueous secondary battery excellent in cycle life while suppressing a decrease in battery capacity.
【０００４】[0004]
【課題を解決するための手段】本発明によれば、リチウ
ム、遷移金属及び酸素を含む複合酸化物からなる非水系
２次電池用の正極活物質であって、該複合酸化物が、更
に炭素及びフッ素を含むことを特徴とする非水系２次電
池用正極活物質が提供される。また本発明によれば、リ
チウム、遷移金属及び酸素を含む複合酸化物の原材料
と、フッ素を含む有機化合物とを混合する工程(Ａ)と、
工程(Ａ)で混合した混合物を、該フッ素を含む有機化合
物の分解温度以上で保持する工程(Ｂ)とを含むことを特
徴とする上記非水系２次電池用正極活物質の製造方法が
提供される。更に本発明によれば、上記正極活物質を含
む正極を備えた非水系２次電池が提供される。According to the present invention, there is provided a positive electrode active material for a non-aqueous secondary battery comprising a composite oxide containing lithium, a transition metal and oxygen, wherein the composite oxide further comprises carbon And a fluorine-containing positive electrode active material for a non-aqueous secondary battery. Further, according to the present invention, a step (A) of mixing a raw material of a composite oxide containing lithium, a transition metal and oxygen, and an organic compound containing fluorine,
And (B) maintaining the mixture mixed in the step (A) at a temperature equal to or higher than the decomposition temperature of the fluorine-containing organic compound. Is done. Further, according to the present invention, there is provided a non-aqueous secondary battery provided with a positive electrode containing the above-mentioned positive electrode active material.
【０００５】[0005]
【発明の実施の形態】以下、本発明を更に詳細に説明す
る。本発明の非水系２次電池用正極活物質(以下、本発
明の正極活物質と略すことがある)は、リチウム、遷移
金属及び酸素を含む複合酸化物が、更に炭素及びフッ素
を含むことを特徴とする。前記リチウム、遷移金属及び
酸素を含む複合酸化物としては、非水系２次電池の正極
に使用しうる組成であれば特に限定されない。遷移金属
としては、例えば、コバルト、マンガン、ニッケル、
鉄、バナジウム又はこれらの混合物等が挙げられる。特
に、コバルト、マンガン及びニッケルからなる群より選
択される１種又は２種以上であることが好ましい。本発
明において、炭素及びフッ素を導入するための上記複合
酸化物組成としては、例えば、ＬｉＣｏＯ2、ＬｉＮｉ
Ｏ2、ＬｉＭｎＯ2、ＬｉＭｎＯ2、ＬｉＭｎ2Ｏ4、Ｌｉ
ＦｅＯ2、ＬｉＶ3Ｏ8又はこれらの各サイトを他の元素
で一部置換した組成等が挙げられる。BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The positive electrode active material for a non-aqueous secondary battery of the present invention (hereinafter, may be abbreviated to the positive electrode active material of the present invention) is a composite oxide containing lithium, a transition metal, and oxygen, further containing carbon and fluorine. Features. The composite oxide containing lithium, transition metal and oxygen is not particularly limited as long as it has a composition that can be used for the positive electrode of a non-aqueous secondary battery. As the transition metal, for example, cobalt, manganese, nickel,
Examples include iron, vanadium, and mixtures thereof. In particular, one or more selected from the group consisting of cobalt, manganese and nickel is preferred. In the present invention, as the composite oxide composition for introducing carbon and fluorine, for example, LiCoO 2 , LiNi
O 2 , LiMnO 2 , LiMnO 2 , LiMn 2 O 4 , Li
Examples include FeO 2 , LiV 3 O 8, or a composition in which each of these sites is partially replaced with another element.
【０００６】本発明の正極活物質における複合酸化物に
おいて、必須成分として含むフッ素の量は、複合酸化物
全量に対して、１００ｐｐｍ以上、特に、３００ｐｐｍ
以上、更には１０００ｐｐｍ以上が好ましい。フッ素の
量が１００ｐｐｍ未満では、所望の効果が得られない恐
れがある。一方、必須成分として含む炭素の量は、複合
酸化物全量に対して、１０ｐｐｍ以上、特に、５０ｐｐ
ｍ以上、更には１００ｐｐｍ以上が好ましい。炭素の量
が１０ｐｐｍ未満では、所望の効果が得られない恐れが
あるので好ましくない。本発明の正極活物質における複
合酸化物において、必須成分として含むフッ素及び炭素
の合計量は、複合酸化物全量に対して、２０００〜５０
０００ｐｐｍ、特に、５０００〜２００００ｐｐｍが好
ましい。５００００ｐｐｍを超える場合には、活物質の
量が減少し、重量あたりの放電容量が低下する恐れがあ
るので好ましくない。[0006] In the composite oxide of the positive electrode active material of the present invention, the amount of fluorine contained as an essential component is 100 ppm or more, especially 300 ppm, based on the total amount of the composite oxide.
Above, more preferably 1000 ppm or more. If the amount of fluorine is less than 100 ppm, a desired effect may not be obtained. On the other hand, the amount of carbon contained as an essential component is 10 ppm or more, especially 50 pp, based on the total amount of the composite oxide.
m or more, more preferably 100 ppm or more. If the amount of carbon is less than 10 ppm, a desired effect may not be obtained. In the composite oxide in the positive electrode active material of the present invention, the total amount of fluorine and carbon contained as essential components is 2,000 to 50, based on the total amount of the composite oxide.
000 ppm, particularly preferably 5000 to 20000 ppm. If it exceeds 50,000 ppm, the amount of the active material is decreased, and the discharge capacity per weight is likely to be reduced, so that it is not preferable.
【０００７】本発明の正極物質は、上記複合酸化物に、
更に希土類金属のフッ化物及び／又は希土類元素の酸フ
ッ化物が導入されたものであっても良い。希土類金属の
フッ化物及び／又は希土類元素の酸フッ化物を導入する
ことにより、正極活物質表面の活性度を更に抑制し、サ
イクル寿命を向上させることができる。ここで、希土類
元素とは、イットリウム、スカンジウムを含むランタン
からルテチウムまでの元素を意味する。上記希土類金属
のフッ化物及び／又は希土類元素の酸フッ化物を導入す
る場合の量は、複合酸化物全量に対して、０．３〜１０
重量％が好ましい。０．３重量％未満では、所望の効果
が得られない恐れがあり、１０重量％を超える場合に
は、活物質の量が減少し、重量あたりの放電容量が低下
する恐れがあるので好ましくない。[0007] The cathode material of the present invention comprises
Further, a rare earth metal fluoride and / or a rare earth oxyfluoride may be introduced. By introducing the rare earth metal fluoride and / or the rare earth element oxyfluoride, the activity of the positive electrode active material surface can be further suppressed, and the cycle life can be improved. Here, the rare earth element means an element from lanthanum containing yttrium and scandium to lutetium. The amount of the rare earth metal fluoride and / or rare earth oxyfluoride introduced is preferably from 0.3 to 10 with respect to the total amount of the composite oxide.
% By weight is preferred. If the amount is less than 0.3% by weight, the desired effect may not be obtained. If the amount is more than 10% by weight, the amount of the active material may be reduced, and the discharge capacity per unit weight may be reduced. .
【０００８】本発明の正極活物質の製造方法は、上記所
望の効果が得られる組成が製造できれば特に限定されな
いが、簡易な方法としては、以下に示す本発明の製造方
法が好ましい。[0008] The method for producing the positive electrode active material of the present invention is not particularly limited as long as the composition which can obtain the above-mentioned desired effects can be produced. As a simple method, the following production method of the present invention is preferable.
【０００９】本発明の製造方法は、リチウム、遷移金属
及び酸素を含む複合酸化物の原材料と、フッ素を含む有
機化合物とを混合する工程(Ａ)と、工程(Ａ)で混合した
混合物を、該フッ素を含む有機化合物の分解温度以上で
保持する工程(Ｂ)とを含み、必要により、工程(Ａ)の
後、工程(Ｂ)の前に、工程(Ａ)で混合した混合物を、前
記フッ素を含む有機化合物の軟化点以上、分解温度未満
の温度で保持する工程(Ｃ)を更に含むことを特徴とす
る。In the production method of the present invention, a step (A) of mixing a raw material of a composite oxide containing lithium, a transition metal and oxygen, and an organic compound containing fluorine, and a mixture obtained in the step (A), And (B) maintaining the organic compound containing fluorine at a decomposition temperature or higher.If necessary, after the step (A) and before the step (B), the mixture obtained in the step (A) is mixed with the mixture. The method further comprises a step (C) of maintaining the organic compound containing fluorine at a temperature equal to or higher than the softening point and lower than the decomposition temperature.
【００１０】工程(Ａ)に用いるリチウム、遷移金属及び
酸素を含む複合酸化物の原材料としては、非水系２次電
池の正極に使用しうる組成であれば特に限定されない。
例えば、ＬｉＣｏＯ2、ＬｉＮｉＯ2、ＬｉＭｎＯ2、Ｌ
ｉＭｎＯ2、ＬｉＭｎ2Ｏ4、ＬｉＦｅＯ2、ＬｉＶ3Ｏ8又
はこれらの各サイトを他の元素で一部置換した組成の材
料等が挙げられる。これらの原材料は公知の方法で得る
ことができる。工程(Ａ)に用いるフッ素を含む有機化合
物としては、フッ素及び炭素を含み、金属を含まない有
機化合物であれば特に限定されないが、作業性等を考慮
した場合、常温で液体又は固体の有機化合物が好まし
い。例えば、フッ化デシル等のフッ化アルキル、フルオ
ル酢酸等の直鎖型有機化合物；フルオルベンゼン、フル
オルフェノール等の環状有機化合物；ポリテトラフルオ
ロエチレン(ＰＴＦＥ)、ポリフッ化ビニリデン(ＰＶＤ
Ｆ)等のフッ素含有樹脂等が挙げられ、特に、フルオル
酢酸又はフッ素含有樹脂が好ましい。フッ素含有樹脂の
分子量は特に限定されないが、重量平均分子量で５００
００〜１０００００００が好ましい。工程(Ａ)におい
て、リチウム、遷移金属及び酸素を含む複合酸化物の原
材料と、フッ素を含む有機化合物との混合割合は、複合
酸化物の原材料に対して、フッ素を含む有機化合物を、
フッ素換算で０．１〜１０重量％、特に、０．１〜５重
量％の範囲で混合することが好ましい。The raw material of the composite oxide containing lithium, transition metal and oxygen used in the step (A) is not particularly limited as long as the composition can be used for the positive electrode of a non-aqueous secondary battery.
For example, LiCoO 2 , LiNiO 2 , LiMnO 2 , L
Examples include iMnO 2 , LiMn 2 O 4 , LiFeO 2 , LiV 3 O 8, or a material having a composition in which each of these sites is partially substituted with another element. These raw materials can be obtained by a known method. The organic compound containing fluorine used in the step (A) is not particularly limited as long as it is an organic compound containing fluorine and carbon and containing no metal, but in consideration of workability and the like, a liquid or solid organic compound at room temperature is considered. Is preferred. For example, linear organic compounds such as alkyl fluorides such as decyl fluoride and fluoroacetic acid; cyclic organic compounds such as fluorobenzene and fluorophenol; polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVD)
And fluorine-containing resins such as F), and particularly preferred is fluoroacetic acid or a fluorine-containing resin. Although the molecular weight of the fluorine-containing resin is not particularly limited, the weight average molecular weight is 500
00 to 10000000 is preferred. In the step (A), the mixing ratio of the raw material of the composite oxide containing lithium, the transition metal and oxygen, and the organic compound containing fluorine is such that the raw material of the composite oxide contains the organic compound containing fluorine,
It is preferable to mix in a range of 0.1 to 10% by weight, particularly 0.1 to 5% by weight in terms of fluorine.
【００１１】工程(Ｂ)において、フッ素を含む有機化合
物の分解温度とは、フッ素を含む有機化合物を分解し得
る温度であれば良く、フッ素を含む有機化合物の種類に
応じて適宜選択することができる。保持時間は、含有さ
れるフッ素を含む有機化合物の分解が終了するのに必要
な時間以上であれば特に限定されない。但し、分解終了
後における必要以上の保持は、効率的ではない。In the step (B), the decomposition temperature of the fluorine-containing organic compound may be a temperature at which the fluorine-containing organic compound can be decomposed, and may be appropriately selected according to the type of the fluorine-containing organic compound. it can. The retention time is not particularly limited as long as it is equal to or longer than the time required for the decomposition of the organic compound containing fluorine to be contained. However, holding more than necessary after decomposition is not efficient.
【００１２】フッ素を含む有機化合物が常温で固体等の
場合には、工程(Ａ)における複合酸化物の原材料とフッ
素を含む有機化合物との混合を十分にするために、上記
工程(Ｃ)の実施が好ましい。工程(Ｃ)において、軟化点
とは、フッ素を含む有機化合物が軟化する温度である。
好ましくは融点以上、分解温度未満に保持することが好
ましい。この際の各保持時間は、工程(Ａ)における複合
酸化物の原材料とフッ素を含む有機化合物との混合が十
分となる時間であれば特に限定されない。When the fluorine-containing organic compound is a solid or the like at room temperature, in order to sufficiently mix the raw material of the composite oxide and the fluorine-containing organic compound in the step (A), the step (C) Implementation is preferred. In the step (C), the softening point is a temperature at which an organic compound containing fluorine softens.
Preferably, the temperature is maintained at a temperature equal to or higher than the melting point and lower than the decomposition temperature. The respective holding times at this time are not particularly limited as long as mixing of the raw material of the composite oxide and the organic compound containing fluorine in the step (A) is sufficient.
【００１３】更に、希土類元素のフッ化物及び／又は希
土類元素の酸フッ化物を導入した、本発明の正極活物質
を得るためには、工程(Ａ)において、希土類元素のフッ
化物及び／又は希土類元素の酸フッ化物を混合すること
により得ることができる。この際、希土類元素のフッ化
物及び／又は希土類元素の酸フッ化物の粒径は、他の材
料との接触面積を大きくし反応を円滑に行なうために、
平均粒径２０μｍ以下、特に、１０μｍ以下が好まし
い。更に、工程(Ｂ)の分解温度は、例えば、フッ素を含
む有機化合物の分解温度よりも希土類元素のフッ化物及
び／又は希土類元素の酸フッ化物の分解温度が高い場合
には、希土類元素のフッ化物及び／又は希土類元素の酸
フッ化物の分解温度以上に保持することが好ましい。Further, in order to obtain the positive electrode active material of the present invention into which the rare earth element fluoride and / or the rare earth element oxyfluoride is introduced, in the step (A), the rare earth element fluoride and / or the rare earth element It can be obtained by mixing elemental oxyfluorides. At this time, the particle size of the rare earth element fluoride and / or the rare earth element oxyfluoride is to increase the contact area with other materials and to smoothly carry out the reaction.
The average particle size is preferably 20 μm or less, particularly preferably 10 μm or less. Further, when the decomposition temperature of the rare earth element fluoride and / or the rare earth oxyfluoride is higher than the decomposition temperature of the organic compound containing fluorine, for example, the decomposition temperature of the rare earth element It is preferable that the temperature is maintained at a temperature equal to or higher than the decomposition temperature of the oxide and / or rare earth element oxyfluoride.
【００１４】本発明の製造方法では、上記工程(Ｂ)によ
り得られる分解物を冷却することにより所望の非水系２
次電池用正極活物質を得ることができる。この正極活物
質は、常法により粉砕して正極材料として用いることが
できる。この正極材料を用いて、例えば、通常の導電助
剤や結着剤を用いて集電体に固定することにより非水系
２次電池用の正極を得ることができる。In the production method of the present invention, the desired non-aqueous system 2 is cooled by cooling the decomposition product obtained in the step (B).
A positive electrode active material for a secondary battery can be obtained. This positive electrode active material can be pulverized by a conventional method and used as a positive electrode material. A positive electrode for a non-aqueous secondary battery can be obtained by fixing the positive electrode material to a current collector using, for example, a normal conductive assistant or a binder.
【００１５】本発明の非水系２次電池は、本発明の正極
活物質を含む正極を備えることを特徴とする。従って、
他の構成要件、例えば、陰極、電解液及びセパレータ等
は特に限定されず、非水系２次電池を構成し得る材料か
ら適宜選択することができ、通常の方法に従って、所望
の非水系２次電池を得ることができる。陰極は、例え
ば、金属リチウム、リチウム合金、若しくはコークス、
黒鉛等のリチウムイオンを吸蔵放出可能な材料から選択
することができる。電解液は、例えば、プロピレンカー
ボネート、エチレンカーボネート、ビニレンカーボネー
ト等の有機溶媒、若しくは該有機溶媒と、ジメチルカー
ボネート、ジエチルカーボネート、１，２−ジエトキシ
エタン、エトキシメトキシエタン等の低沸点溶媒との混
合溶媒に、ＬｉＰＦ6、ＬｉＣｌＯ4、ＬｉＣＦ3ＳＯ3等
の電解液溶質を溶解した溶液等が挙げられる。A non-aqueous secondary battery of the present invention is characterized by including a positive electrode containing the positive electrode active material of the present invention. Therefore,
Other constituent elements, for example, the cathode, the electrolytic solution, the separator, and the like are not particularly limited, and can be appropriately selected from materials that can constitute the non-aqueous secondary battery. Can be obtained. The cathode is, for example, metallic lithium, lithium alloy, or coke,
The material can be selected from materials capable of inserting and extracting lithium ions such as graphite. The electrolytic solution is, for example, an organic solvent such as propylene carbonate, ethylene carbonate, or vinylene carbonate, or a mixture of the organic solvent and a low boiling point solvent such as dimethyl carbonate, diethyl carbonate, 1,2-diethoxyethane, or ethoxymethoxyethane. Examples of the solvent include a solution in which an electrolyte solute such as LiPF 6 , LiClO 4 , and LiCF 3 SO 3 is dissolved.
【００１６】[0016]
【発明の効果】本発明の非水系２次電池用正極活物質
は、リチウム、遷移金属及び酸素を含む複合酸化物が、
更に炭素及びフッ素、また必要に応じて希土類元素のフ
ッ化物及び／又は希土類元素の酸フッ化物を含むので、
電池容量の低下を抑制すると共に、サイクル寿命を向上
させることができ、これを用いた非水系２次電池は、サ
イクル寿命に優れると共に、高電池容量が維持される。
また、本発明の製造方法では、このような正極活物質を
容易に得ることができる。The positive electrode active material for a non-aqueous secondary battery of the present invention comprises a composite oxide containing lithium, a transition metal and oxygen,
Furthermore, since it contains carbon and fluorine, and if necessary, a rare earth element fluoride and / or a rare earth element oxyfluoride,
A decrease in battery capacity can be suppressed and the cycle life can be improved. A non-aqueous secondary battery using the same has excellent cycle life and maintains high battery capacity.
Further, according to the production method of the present invention, such a positive electrode active material can be easily obtained.
【００１７】[0017]
【実施例】以下、本発明を実施例及び比較例により更に
詳細に説明するが、本発明はこれらに限定されるもので
はない。実施例１ (正極の作成)コバルト酸リチウムと、フッ素を含む有機
化合物としてのフルオル酢酸とを、重量比で９６：４の
割合で混合した。次いで、８００℃(フルオル酢酸の分
解温度以上)で５時間保持し、冷却して正極活物質とし
ての複合酸化物を得た。得られた複合酸化物中の炭素量
をホリバ製作所社製の炭素硫黄分析計(ＥＭＧＡ−５５
０ＦＡ)により、並びにフッ素量を日立製作所社製の吸
光光度計(Ｕ−２００１)を用いてそれぞれ測定した。結
果を表１に示す。次に、得られた複合酸化物をボールミ
ルで平均粒径５μｍになるまで粉砕した後、該粉砕物
と、導電助剤(電気化学工業社製のアセチレンブラック)
と、結着剤(アルドリッチ社製のポリフッ化ビニリデン)
とを重量比で、８０：１０：１０の割合で混合して正極
合剤を調製し、続いて、ステンレス鋼鈑を集電体として
円盤状の正極を作製した。 (負極の作製)リチウム圧延板を所定寸法に打ち抜いて円
盤状のリチウム金属板を得、ステンレス鋼鈑を集電体と
して負極を作製した。 (電解液の調製)エチレンカーボネートとジメチルカーボ
ネートとを容量比で１：１の割合で混合した溶液に、６
フッ化リン酸リチウムを１ｍｏｌ／リットルの割合で溶
解して電解液を調製した。 (電池評価)上記により得られた、正極、負極及び電解液
を用いて、常法によりリチウム２次電池を作製した。得
られた電池を、充放電電流密度が０．５ｍＡ／ｃｍ2に
なる条件で、充電上限電圧を４．１Ｖ、放電下限電圧を
２．７５Ｖとして充放電を繰り返し、作製した電池の繰
り返し充放電による容量維持率を、計測器センター社製
の電池サイクル寿命特性試験システムにより測定した。
結果を表１に示す。EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Example 1 ( Preparation of Positive Electrode) Lithium cobaltate and fluoroacetic acid as an organic compound containing fluorine were mixed at a weight ratio of 96: 4. Next, it was kept at 800 ° C. (not less than the decomposition temperature of fluoroacetic acid) for 5 hours and cooled to obtain a composite oxide as a positive electrode active material. The amount of carbon in the obtained composite oxide was measured using a carbon sulfur analyzer (EMGA-55) manufactured by Horiba, Ltd.
0FA), and the amount of fluorine was measured using a spectrophotometer (U-2001) manufactured by Hitachi, Ltd. Table 1 shows the results. Next, the obtained composite oxide was pulverized with a ball mill until the average particle size became 5 μm, and then the pulverized product and a conductive additive (acetylene black manufactured by Denki Kagaku Kogyo Co., Ltd.)
And a binder (polyvinylidene fluoride manufactured by Aldrich)
Were mixed at a weight ratio of 80:10:10 to prepare a positive electrode mixture, and subsequently, a disk-shaped positive electrode was prepared using a stainless steel plate as a current collector. (Preparation of Negative Electrode) A rolled lithium plate was punched into a predetermined size to obtain a disk-shaped lithium metal plate, and a negative electrode was prepared using a stainless steel plate as a current collector. (Preparation of electrolytic solution) A solution prepared by mixing ethylene carbonate and dimethyl carbonate at a volume ratio of 1: 1 was added
An electrolyte was prepared by dissolving lithium fluorophosphate at a rate of 1 mol / liter. (Evaluation of Battery) Using the positive electrode, the negative electrode, and the electrolytic solution obtained as described above, a lithium secondary battery was produced by a conventional method. The obtained battery was repeatedly charged and discharged at a charge upper limit voltage of 4.1 V and a discharge lower limit voltage of 2.75 V under the condition that the charge / discharge current density was 0.5 mA / cm 2 , and the prepared battery was repeatedly charged and discharged. Was measured by a battery cycle life characteristic test system manufactured by Keisoku Center.
Table 1 shows the results.
【００１８】実施例２ コバルト酸リチウムと、フッ素を含む有機化合物として
のポリフッ化ビニリデン(アルドリッチ社製、分子量５
３４０００)とを、重量比で９８：２の割合で混合し
た。次いで、２５０℃(ポリフッ化ビニリデンの軟化温
度は１７０℃)で２時間保持した後、８００℃(ポリフッ
化ビニリデンの分解温度は３６０℃)で５時間保持し、
冷却して正極活物質としての複合酸化物を得た。得られ
た複合酸化物中の炭素及びフッ素量を実施例１と同様に
測定した。結果を表１に示す。次いで、得られた複合酸
化物を用いて、実施例１と同様に、正極を作製し、実施
例１と同様に作製又は調製した陰極及び電解液を用いて
リチウム２次電池を作製した。得られた電池について、
実施例１と同様に容量維持率を測定した。結果を表１に
示す。 EXAMPLE 2 Lithium cobaltate and polyvinylidene fluoride as an organic compound containing fluorine (Aldrich, molecular weight 5
34000) and 98: 2 by weight. Next, after keeping at 250 ° C. (the softening temperature of polyvinylidene fluoride is 170 ° C.) for 2 hours, it is kept at 800 ° C. (the decomposition temperature of polyvinylidene fluoride is 360 ° C.) for 5 hours,
Upon cooling, a composite oxide as a positive electrode active material was obtained. The amounts of carbon and fluorine in the obtained composite oxide were measured in the same manner as in Example 1. Table 1 shows the results. Next, a positive electrode was produced using the obtained composite oxide in the same manner as in Example 1, and a lithium secondary battery was produced using the cathode and the electrolytic solution produced or prepared in the same manner as in Example 1. About the obtained battery,
The capacity retention was measured in the same manner as in Example 1. Table 1 shows the results.
【００１９】比較例１ フッ素含有有機化合物としてのフルオル酢酸を用いなか
った以外は、実施例１と同様に各材料及び電池を作製
し、各測定を行なった。結果を表１に示す。 Comparative Example 1 Materials and batteries were prepared in the same manner as in Example 1 except that fluoracetic acid was not used as the fluorine-containing organic compound, and each measurement was performed. Table 1 shows the results.
【００２０】比較例２ フッ素含有有機化合物としてのポリフッ化ビニリデンを
用いなかった以外は、実施例２と同様に各材料及び電池
を作製し、各測定を行なった。結果を表１に示す。 Comparative Example 2 Each material and battery were prepared in the same manner as in Example 2 except that polyvinylidene fluoride was not used as the fluorine-containing organic compound, and each measurement was performed. Table 1 shows the results.
【００２１】[0021]
【表１】 [Table 1]
フロントページの続き Ｆターム(参考） 5H003 AA04 BA01 BA03 BB05 BC01 BD01 BD04 5H014 AA01 AA06 BB01 BB06 EE05 EE07 EE10 HH01 HH08 5H029 AJ05 AK03 AL06 AL12 AM03 AM04 AM06 AM07 CJ02 CJ08 CJ28 DJ08 DJ16 EJ03 EJ04 HJ01 HJ14 Continued on front page F-term (reference)
Claims (8)
酸化物からなる非水系２次電池用の正極活物質であっ
て、該複合酸化物が、更に炭素及びフッ素を含むことを
特徴とする非水系２次電池用正極活物質。1. A positive electrode active material for a non-aqueous secondary battery comprising a composite oxide containing lithium, a transition metal and oxygen, wherein the composite oxide further contains carbon and fluorine. Positive active material for aqueous secondary batteries.
ッケルからなる群より選択される１種または２種以上を
含むことを特徴とする請求項１記載の非水系２次電池用
正極活物質。2. The positive electrode active material for a non-aqueous secondary battery according to claim 1, wherein the transition metal contains one or more selected from the group consisting of cobalt, manganese, and nickel.
上であることを特徴とする請求項１又は２記載の非水系
２次電池用正極活物質。3. The positive electrode active material for a non-aqueous secondary battery according to claim 1, wherein the amount of carbon in the composite oxide is 10 ppm or more.
び／又は希土類元素の酸フッ化物を更に含むことを特徴
とする請求項１〜３のいずれか１項記載の非水系２次電
池用正極活物質。4. The non-aqueous secondary battery according to claim 1, wherein the composite oxide further contains a rare earth element fluoride and / or a rare earth element oxyfluoride. Positive electrode active material.
元素の酸フッ化物量が、複合酸化物全体に対して０．３
〜１０重量％であることを特徴とする請求項４記載の非
水系２次電池用正極活物質。5. The amount of the rare earth element fluoride and / or the rare earth element oxyfluoride is 0.3 to the whole composite oxide.
The positive electrode active material for a non-aqueous secondary battery according to claim 4, wherein the content is 10 to 10% by weight.
酸化物の原材料と、フッ素を含む有機化合物とを混合す
る工程(Ａ)と、工程(Ａ)で混合した混合物を、該フッ素
を含む有機化合物の分解温度以上で保持する工程(Ｂ)と
を含むことを特徴とする請求項１記載の非水系２次電池
用正極活物質の製造方法。6. A step (A) of mixing a raw material of a composite oxide containing lithium, a transition metal and oxygen and an organic compound containing fluorine, and the mixture obtained in the step (A) is mixed with the organic compound containing fluorine. The method for producing a positive electrode active material for a non-aqueous secondary battery according to claim 1, further comprising a step (B) of maintaining the temperature at or above the decomposition temperature of the compound.
(Ａ)で混合した混合物を、前記フッ素を含む有機化合物
の軟化点以上、分解温度未満の温度で保持する工程(Ｃ)
を更に含むことを特徴とする請求項６記載の製造方法。7. The method according to claim 1, wherein after the step (A) and before the step (B),
Step (C) of maintaining the mixture mixed in (A) at a temperature equal to or higher than the softening point of the fluorine-containing organic compound and lower than the decomposition temperature.
The method according to claim 6, further comprising:
活物質を含む正極を備える非水系２次電池。8. A non-aqueous secondary battery comprising a positive electrode containing the positive electrode active material according to claim 1. Description:
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|---|---|---|---|---|
| US8889299B2 (en) | 2011-12-23 | 2014-11-18 | Samsung Sdi Co., Ltd. | Positive active material and method of preparing same and rechargeable lithium battery including same |
| JP2019186144A (en) * | 2018-04-16 | 2019-10-24 | トヨタ自動車株式会社 | Positive electrode active material, positive electrode, lithium ion secondary battery and method for manufacturing positive electrode active material |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10312523B2 (en) * | 2016-02-25 | 2019-06-04 | Tdk Corporation | Lithium ion secondary battery |
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1999
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8889299B2 (en) | 2011-12-23 | 2014-11-18 | Samsung Sdi Co., Ltd. | Positive active material and method of preparing same and rechargeable lithium battery including same |
| JP2019186144A (en) * | 2018-04-16 | 2019-10-24 | トヨタ自動車株式会社 | Positive electrode active material, positive electrode, lithium ion secondary battery and method for manufacturing positive electrode active material |
| CN110391403A (en) * | 2018-04-16 | 2019-10-29 | 丰田自动车株式会社 | The manufacturing method of positive electrode active materials, anode, lithium ion secondary battery and positive electrode active materials |
| JP7000239B2 (en) | 2018-04-16 | 2022-01-19 | トヨタ自動車株式会社 | Method for manufacturing positive electrode active material particles, positive electrode, lithium ion secondary battery, and positive electrode active material particles |
| US11296327B2 (en) * | 2018-04-16 | 2022-04-05 | Toyota Jidosha Kabushiki Kaisha | Positive electrode active material, positive electrode, lithium-ion secondary battery, and method of producing positive electrode active material |
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