JP2002170563A - Manganese system positive electrode material having excellent cycle property and lithium secondary battery using the same - Google Patents
Manganese system positive electrode material having excellent cycle property and lithium secondary battery using the sameInfo
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- JP2002170563A JP2002170563A JP2000364153A JP2000364153A JP2002170563A JP 2002170563 A JP2002170563 A JP 2002170563A JP 2000364153 A JP2000364153 A JP 2000364153A JP 2000364153 A JP2000364153 A JP 2000364153A JP 2002170563 A JP2002170563 A JP 2002170563A
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- Prior art keywords
- positive electrode
- lithium secondary
- secondary battery
- electrode material
- cycle characteristics
- Prior art date
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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
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- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
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
用正極材料、特にサイクル特性に優れたＭｎ系正極材料
及び同正極材料を用いたリチウム二次電池に関する。The present invention relates to a positive electrode material for a lithium secondary battery, and more particularly to a Mn-based positive electrode material having excellent cycle characteristics and a lithium secondary battery using the same.
【０００２】[0002]
【従来の技術】リチウム二次電池は従来の二次電池に比
べ高いエネルギー密度を有するので、携帯電話、携帯用
ビデオカメラ、ノート型パソコンなどの電子機器用電池
として普及しているが、将来的には電気自動車や一般家
庭の分散配置型電源としての利用が期待されており、さ
らに高容量、高能率の電池を得るための研究開発が盛ん
に行われている。2. Description of the Related Art Lithium secondary batteries have a higher energy density than conventional secondary batteries, and thus have become widespread as batteries for electronic devices such as mobile phones, portable video cameras, and notebook personal computers. Is expected to be used as a distributed power source for electric vehicles and ordinary households, and research and development for obtaining a high-capacity, high-efficiency battery is being actively conducted.
【０００３】現在、市販されているリチウム二次電池用
正極活物質には、ＬｉＣｏＯ２が用いられているが、熱
的安定性が悪いため安全性に問題があり、またコバルト
自体の地球資源の採掘可能な埋蔵量が少なく、高価であ
るという欠点を持っている。これに替わるものとして、
豊富な資源を持ち経済性に優れているリチウム・ニッケ
ル複合酸化物の研究が行われている。しかし、このリチ
ウム・ニッケル複合酸化物はＬｉＮｉＯ２の合成の際に
酸素気流が必要であるという工程の難しさがあり、また
Ｎｉの一部が本来Ｌｉの入るべきサイトに混入するなど
の結晶の乱れがあって十分なサイクル特性が得られない
という欠点があるので殆ど実用化に至っていないのが現
状である。At present, LiCoO 2 is used as a commercially available positive electrode active material for lithium secondary batteries, but has a problem in safety due to poor thermal stability. It has the drawback that the reserves that can be mined are small and expensive. As an alternative,
Research is being conducted on lithium-nickel composite oxides that have abundant resources and are economical. However, this lithium-nickel composite oxide has a difficulty in the step of requiring an oxygen gas stream when synthesizing LiNiO 2 , and has a problem in that a part of Ni is mixed in a site where Li should originally enter. At present, it has hardly been put to practical use because there is a defect that sufficient cycle characteristics cannot be obtained due to disturbance.
【０００４】このようなことから、コバルトやニッケル
に比べさらに価格が安く、埋蔵されている量も豊富であ
るＬｉｘＭｎ２Ｏ４スピネル化合物が注目され、近年研
究が盛んに行われている。そして上記のような電気自動
車等の用途にも対応できるものと期待されている。この
リチウム・マンガン複合酸化物であるスピネルＬｉｘＭ
ｎ２Ｏ４はＬｉが８ａ四面体サイトに、Ｍｎは１６ｄ八
面体サイトにある。酸素の配置は立方細密充填構造であ
り、基本の骨格はλ-ＭｎＯ２である。リチウムイオン
は可逆的に四面体サイトを占めるのでＬｉｘＭｎ２Ｏ４
を正極材とするリチウム二次電池においては基本骨格の
構造破壊は殆ど起こらない。充放電に伴なって結晶格子
の膨張・収縮が起こるのみである。このため充放電が安
定しているという特徴を有している。[0004] For these reasons, attention has been paid to Li x Mn 2 O 4 spinel compounds, which are cheaper than cobalt and nickel and have a large amount of reserves, and have been actively studied in recent years. It is expected that it can be used for electric vehicles and the like as described above. This lithium / manganese composite oxide, spinel Li x M
In n 2 O 4 , Li is on the 8a tetrahedral site and Mn is on the 16d octahedral site. The arrangement of oxygen is a cubic close-packed structure, and the basic skeleton is λ-MnO 2 . Since lithium ions reversibly occupy tetrahedral sites, Li x Mn 2 O 4
In a lithium secondary battery using as a positive electrode material, structural destruction of the basic skeleton hardly occurs. Only expansion and contraction of the crystal lattice occur with charge and discharge. For this reason, it has the feature that charge and discharge are stable.
【０００５】ところが、ＬｉｘＭｎ２Ｏ４スピネル化合
物はこのように熱的安定性が高いけれども、これを正極
活物質として使用した二次電池はサイクル特性が悪く、
実用上の大きな支障となっている。従来、この欠点を改
良しようとして活物質の均一性を高めたり、他の物質の
ドーピングなどの方法を用いてサイクル特性改善の図ら
れているがいまだ十分なものとは言えない。例えば、Ｌ
ｉｘＭｎ２Ｏ４スピネル化合物のＭｎ塩のＭｎサイトを
Ｚｎ、Ｔｉ、Ｚｒ等で一部置換する提案がなされた。し
かし、これによって得たものは、Ｍｎ酸化数が大きく変
動し、初期容量が著しく低下するという問題があった。
このようなことから、ＬｉｘＭｎ２Ｏ４スピネル化合物
は、さらに改良がなければ実用に供することができなか
った。[0005] However, although the Li x Mn 2 O 4 spinel compound has high thermal stability as described above, a secondary battery using this as a positive electrode active material has poor cycle characteristics.
This is a major obstacle in practical use. Conventionally, attempts have been made to improve the uniformity of the active material to improve this drawback, or to improve the cycle characteristics by using a method such as doping with another material, but it cannot be said that it is still sufficient. For example, L
i x Mn 2 O 4 Mn sites of Zn in the Mn salt of spinel compounds, Ti, is proposed to partially replaced with Zr, etc. have been made. However, those obtained by this method had a problem that the Mn oxidation number fluctuated greatly and the initial capacity was significantly reduced.
For these reasons, the Li x Mn 2 O 4 spinel compound could not be put to practical use without further improvement.
【０００６】従来、ＬｉＭｎ２Ｏ４スピネル化合物のサ
イクル特性を改善する方法として、ＬｉＭｎ２Ｏ４粉の
表面にＡｇを被覆する技術の提案がなされている（「Ｌ
ｉＭｎ２Ｏ４粉の表面処理の充放電特性への影響Ｉ．Ａ
ｇ被覆」Electrochemistry 67,No.4(1999) p.359-363
）。しかし、この技術報告書によるとＬｉＭｎ２Ｏ４
粒子へのＡｇ被覆により、３０°Ｃでは充放電サイクル
特性は良好であったが、６０°Ｃではサイクル特性数の
増加とともに放電容量が低下し、５０サイクル目の容量
は初期容量の７０％に低下し、必ずしも良好な結果が得
られていない。しかも、６０°ＣではＬｉＭｎ２Ｏ４粉
からのマンガンイオンの溶出があり、それをＡｇ被覆で
は防止できないと報告されており、ＬｉＭｎ２Ｏ４粉の
表面にＡｇを被覆することでは、サイクル特性の改善は
困難なことが分かっている。Conventionally, as a method for improving the cycle characteristics of a LiMn 2 O 4 spinel compound, a technique of coating Ag on the surface of LiMn 2 O 4 powder has been proposed (see “L.
Effect of surface treatment of iMn 2 O 4 powder on charge and discharge characteristics A
g coating '' Electrochemistry 67, No. 4 (1999) p.359-363
). However, according to this technical report, LiMn 2 O 4
Due to the Ag coating on the particles, the charge / discharge cycle characteristics were good at 30 ° C, but at 60 ° C, the discharge capacity decreased as the number of cycle characteristics increased, and the capacity at the 50th cycle was reduced to 70% of the initial capacity. And good results have not always been obtained. Moreover, there is dissolution of manganese ions from the 60 ° C in LiMn 2 O 4 powder, it has been reported that it can not prevent the Ag coating is to coat the Ag on the surface of LiMn 2 O 4 powder, the cycle characteristics Improvements have proven difficult.
【０００７】また、ＬｉＭｎ２Ｏ４スピネル化合物の高
温サイクル特性を改善する方法として、ポリアニリン高
分子化合物でＬｉＭｎ２Ｏ４粒を被覆して電解液との直
接的接触を防止し、マンガン溶解に起因する充放電容量
の低下を抑制する方法が提案されている（「ポリアニリ
ン被覆スピネルＬｉＭｎ２Ｏ４の充放電挙動」Electroc
hemistry 68,No.7(2000) p.587-590）。しかし、この方
法はサイクル数が少ない場合に効果があること報告がな
されているが、サイクル数が増大する場合の効果は十分
に確認されていない。しかも、ポリアニリン自体の充放
電挙動が電解液に強く依存するため、電解液の種類によ
っては十分な効果が得られず、汎用性のある安定したサ
イクル特性改善効果のある材料とは必ずしも言えない問
題がある。この外、ＬｉＭｎ２Ｏ４粒子にＬｉ２Ｍｎ２
Ｏ４層を形成するか又はＬｉ２Ｍｎ２Ｏ４との複合体と
して、高電位における充放電時にマンガンの溶出を防止
し、サイクル特性を向上させようとするもの（特開平１
０−１９９５２８）あるいはスピネルマンガン正極活物
質粒子お表面のマンガンの一部をＳｃ、Ｔｉ、Ｖ、Ｃ
ｒ、Ｆｅ、希土類の遷移金属で置換して表面層を形成し
サイクル特性を向上させようとするもの（特開２０００
−３０７０９）が提案されている。しかし、表面被覆層
形成の作業工程が複雑になり、また安定した十分なサイ
クル特性を向上させることができないという問題があ
る。As a method of improving the high-temperature cycle characteristics of the LiMn 2 O 4 spinel compound, a method of coating LiMn 2 O 4 particles with a polyaniline polymer compound to prevent direct contact with the electrolyte and dissolving the manganese is caused. (“Charging and discharging behavior of polyaniline-coated spinel LiMn 2 O 4 ” Electroc) has been proposed.
hemistry 68, No. 7 (2000) p.587-590). However, although it has been reported that this method is effective when the number of cycles is small, the effect when the number of cycles is increased has not been sufficiently confirmed. In addition, since the charge / discharge behavior of polyaniline itself strongly depends on the electrolytic solution, sufficient effects cannot be obtained depending on the type of the electrolytic solution, and it is not necessarily a versatile material having a stable cycle characteristic improving effect. There is. In addition, LiMn 2 O 4 particles have Li 2 Mn 2
A method of forming an O 4 layer or as a composite with Li 2 Mn 2 O 4 to prevent manganese from eluting during charge and discharge at a high potential and to improve cycle characteristics (Japanese Patent Laid-Open No.
0-199528) or a part of manganese on the surface of the spinel manganese positive electrode active material particles is Sc, Ti, V, C
A method for improving cycle characteristics by forming a surface layer by substituting with a transition metal of r, Fe, or rare earth (Japanese Patent Laid-Open No. 2000-2000)
-30709) has been proposed. However, there is a problem that the operation process of forming the surface coating layer becomes complicated, and stable and sufficient cycle characteristics cannot be improved.
【０００８】[0008]
【発明が解決しようとする課題】本発明は、リチウム二
次電池用正極材料としてＬｉ１＋ｘ（Ｍｎ２-ｘ）Ｏ４
（０≦ｘ≦０．２０）の化学式で表されるスピネル化合
物を使用し、初期容量を良好に維持するとともに、高温
での劣化を抑制し、高充電率を維持する良好な充電サイ
クル特性を有するＭｎ系正極材料及び同正極材料を用い
たリチウム二次電池を確立することである。SUMMARY OF THE INVENTION The present invention provides Li 1 + x (Mn 2-x ) O 4 as a cathode material for a lithium secondary battery.
Using a spinel compound represented by the chemical formula of (0 ≦ x ≦ 0.20), a good charge cycle characteristic of maintaining a good initial capacity, suppressing deterioration at a high temperature, and maintaining a high charge rate. An object of the present invention is to establish a Mn-based positive electrode material and a lithium secondary battery using the same.
【０００９】[0009]
【課題を解決するための手段】本発明は、この知見に基
づき、 １．Ｌｉ１＋ｘ（Ｍｎ２-ｘ）Ｏ４（０≦ｘ≦０．２
０）の化学式で表される粒状のリチウム二次電池用正極
活物質材料であって、その表面がＬｉＮｉｘＣｏ１ -ｘ
Ｏ２（０＜ｘ＜１．０）でコーティングされていること
を特徴とするサイクル特性に優れたＭｎ系正極材料 ２．Ｌｉ１＋ｘ（Ｍｎ２-ｘ）Ｏ４（０≦ｘ≦０．２
０）の化学式で表される粒状のリチウム二次電池用正極
活物質材料であって、その表面がＬｉＮｉｘＣｏ１ -ｘ
Ｏ２（０．７＜ｘ＜０．９）でコーティングされている
ことを特徴とするサイクル特性に優れたＭｎ系正極材料 ３．正極活物質材料の平均粒径が５〜２０μｍ、タップ
密度が２．０ｇ／ｃｃ以上であることを特徴とする上記
１又は２記載のサイクル特性に優れたＭｎ系正極材料 ４．コーティングされるＬｉＮｉｘＣｏ１-ｘＯ２の平
均粒径が１μｍ以下であることを特徴とする上記１〜３
のそれぞれに記載のサイクル特性に優れたＭｎ系正極材
料 ５．ＬｉＮｉｘＣｏ１-ｘＯ２のコーティング層の厚さ
が０．５μｍ以下であることを特徴とする上記１〜４の
それぞれに記載のサイクル特性に優れたＭｎ系正極材料 ６．ＬｉＮｉｘＣｏ１-ｘＯ２粉粒に圧縮と剪断力を与
えて母粒子である正極活物質材料にコーティングされた
ものであることを特徴とする上記１〜５のそれぞれに記
載のサイクル特性に優れたＭｎ系正極材料 ７．上記１〜６のそれぞれに記載のＭｎ系正極材料を用
いたリチウム二次電池を提供する。The present invention has been made based on this finding. Li 1 + x (Mn 2-x ) O 4 (0 ≦ x ≦ 0.2
0) A particulate positive electrode active material for a lithium secondary battery represented by the chemical formula 0), the surface of which is LiNi x Co 1 -x
1. Mn-based positive electrode material excellent in cycle characteristics characterized by being coated with O 2 (0 <x <1.0) Li 1 + x (Mn 2-x ) O 4 (0 ≦ x ≦ 0.2
0) A particulate positive electrode active material for a lithium secondary battery represented by the chemical formula 0), the surface of which is LiNi x Co 1 -x
2. Mn-based positive electrode material excellent in cycle characteristics characterized by being coated with O 2 (0.7 <x <0.9) 3. The Mn-based positive electrode material having excellent cycle characteristics as described in 1 or 2, wherein the positive electrode active material has an average particle diameter of 5 to 20 μm and a tap density of 2.0 g / cc or more. Wherein the average particle size of LiNi x Co 1-x O 2 to be coated is 1 μm or less.
4. Mn-based positive electrode materials excellent in cycle characteristics described in each of 5. 5. The Mn-based positive electrode material having excellent cycle characteristics as described in any one of 1 to 4 above, wherein the thickness of the coating layer of LiNi x Co 1-x O 2 is 0.5 μm or less. LiNi x Co 1-x O 2 powder is compressed and sheared to give a positive electrode active material which is a base particle by applying a compressive and shearing force. 6. Excellent Mn-based positive electrode material A lithium secondary battery using the Mn-based positive electrode material described in any of 1 to 6 above is provided.
【００１０】[0010]
【発明の実施の形態】現在、リチウム二次電池に用いら
れるＬｉ１＋ｘ（Ｍｎ２-ｘ）Ｏ４スピネル化合物は実
験室レベルの特殊なケースを除き、実用的なレベルでは
粉末状のリチウム塩（炭酸塩）とマンガン塩（酸化物）
を混合して熱処理する固相反応法が用いられている。固
相反応法はリチウム塩（炭酸塩）中のリチウムとマンガ
ン塩（酸化物）中のマンガンの相互拡散を主反応として
進む。この場合、相互に均一拡散するのが理想である
が、リチウム塩（炭酸塩）は熱的に不安定で分解しやす
く、実際にはマンガン塩（酸化物）中にリチウムが拡散
する形で反応が進む。DETAILED DESCRIPTION OF THE INVENTION At present, Li 1 + x (Mn 2 -x ) O 4 spinel compounds used in lithium secondary batteries are powdery lithium salts at practical levels except for special cases at the laboratory level. Carbonate) and manganese salt (oxide)
Are mixed and heat-treated. The solid-state reaction method proceeds mainly by mutual diffusion of lithium in a lithium salt (carbonate) and manganese in a manganese salt (oxide). In this case, it is ideal that they diffuse uniformly, but the lithium salt (carbonate) is thermally unstable and easily decomposed, and actually reacts in such a way that lithium diffuses into the manganese salt (oxide). Advances.
【００１１】スピネル化合物の平均粒径は二酸化マンガ
ンの粒径に依存するが、本発明の平均粒径は５ミクロン
以上、２０ミクロン以下の大きさに調整され、またタッ
プ密度が２．０ｇ／ｃｃ以上であるのが望ましい。平均
粒径５μｍ未満では電解液へのＭｎ溶解の進行が速く効
果が期待できない。また、平均粒径２０μｍを超えると
相対的に粗粒が増え、塗布性や電池特性に問題を生じ
る。さらに、タップ密度が２．０ｇ／ｃｃ未満では、電
池作製時のプレス時に粒の破壊を生じ電池特性に悪影響
を与える。これらのスピネル化合物の出発原料として
は、市販の化学合成二酸化マンガンを用いても良いし、
微粒炭酸マンガンを酸化して作製しても良い（特願平１
１−０８５１０６、特願２０００−０４３５８８参
照）。これらの出発原料とリチウム塩（炭酸塩）を混合
し、不活性雰囲気中、大気中又は酸化雰囲気中で６５０
〜９００°Ｃの間で電気炉等の加熱装置を用いて熱処理
することによって得られる。Although the average particle size of the spinel compound depends on the particle size of manganese dioxide, the average particle size of the present invention is adjusted to a size of 5 μm to 20 μm and the tap density is 2.0 g / cc. It is desirable that this is the case. If the average particle size is less than 5 μm, the dissolution of Mn in the electrolytic solution proceeds so rapidly that no effect can be expected. On the other hand, if the average particle size exceeds 20 μm, coarse particles relatively increase, which causes problems in applicability and battery characteristics. Further, when the tap density is less than 2.0 g / cc, particles are broken at the time of pressing at the time of producing a battery, which adversely affects battery characteristics. As a starting material of these spinel compounds, commercially available chemically synthesized manganese dioxide may be used,
It may be produced by oxidizing fine manganese carbonate.
1-085106, Japanese Patent Application No. 2000-043588). These starting materials are mixed with a lithium salt (carbonate) and mixed in an inert atmosphere, air or an oxidizing atmosphere.
It is obtained by performing heat treatment using a heating device such as an electric furnace at a temperature of up to 900 ° C.
【００１２】上記のように、Ｍｎ系正極材における問題
点の一つとして高温での劣化が大きいことが挙げられる
が、その要因として電解液と水分の反応で生成するＨＦ
がＭｎ系正極材に作用して劣化することが挙げられる。
近年Ｎｉ−Ｃｏ系正極材料がＨＦに対して劣化防止の効
果があることが見出されている。そのてめ、Ｍｎ系正極
材とＮｉ−Ｃｏ系正極材料とを混合した混合正極材料の
提案がなされている。しかし、これによってもサイクル
劣化が大きくなり実用的ではない結果が得られている。
このため、本発明はＬｉ１＋ｘ（Ｍｎ２-ｘ）Ｏ４（０
≦ｘ≦０．２０）の化学式で表される粒状のリチウム二
次電池用正極活物質材料に、ＬｉＮｉｘＣｏ１ -ｘＯ２
（０＜ｘ＜１．０）、好ましくはＬｉＮｉｘＣｏ１-ｘ
Ｏ２（０．７＜ｘ＜０．９）をコーティングし、高温時
におけるマンガン系正極材料とＨＦとの反応を抑制し、
サイクル劣化を防止するものである。なお、ＬｉＮｉｘ
Ｃｏ１-ｘＯ２に種々の元素をドーピングした材料につ
いても同様の効果が得られる。As described above, one of the problems with the Mn-based cathode material is that deterioration at a high temperature is large. One of the causes is that HF generated by the reaction between the electrolyte and water.
Acts on the Mn-based positive electrode material and deteriorates.
In recent years, it has been found that a Ni—Co-based positive electrode material has an effect of preventing deterioration of HF. In addition, a mixed cathode material in which a Mn-based cathode material and a Ni—Co-based cathode material are mixed has been proposed. However, this also results in increased cycle deterioration and results in impractical results.
For this reason, the present invention provides Li 1 + x (Mn 2-x ) O 4 (0
≦ x ≦ 0.20) LiNi x Co 1 -xO 2 is used as a granular positive electrode active material for a lithium secondary battery represented by the chemical formula:
(0 <x <1.0), preferably LiNi x Co 1-x
O 2 (0.7 <x <0.9) is coated to suppress the reaction between the manganese-based positive electrode material and HF at a high temperature,
This is to prevent cycle deterioration. Note that LiNi x
Similar effects can be obtained for materials obtained by doping Co 1-x O 2 with various elements.
【００１３】コーティングするＬｉＮｉｘＣｏ１-ｘＯ
２は平均粒径が１μｍ以下であることが望ましい。平均
粒径が１μｍを超えるとコーティング自体が困難とな
り、コーティングの効果が得られない。また、ＬｉＮｉ
ｘＣｏ１-ｘＯ２のコーティング層の厚さは０．５μｍ
以下であることが望ましい。コーティング層の厚さが
０．５μｍを超えると充放電時のＬｉの移動に悪影響を
与える。好適な範囲は０．０１〜０．２μｍである。こ
れらのＬｉＮｉｘＣｏ１-ｘＯ２コーティングは、Ｌｉ
ＮｉｘＣｏ１-ｘＯ２の粉粒に圧縮と剪断力を与えて母
粒子であるＬｉ１＋ｘ（Ｍｎ２-ｘ）Ｏ４の正極活物質
材料にコーティングすることが望ましい。これによっ
て、ＬｉＮｉｘＣｏ１-ｘＯ２を母粒子である正極活物
質材料を破壊せずに該正極活物質材料に均一に被覆する
ことができる。以上のＬｉＮｉｘＣｏ１-ｘＯ２コーテ
ィング層を形成することによって、初期容量を低下させ
ずに、自己放電の低減、高サイクル特性のリチウム二次
電池用正極材料を得ることが可能になった。LiNi x Co 1-x O to be coated
2 preferably has an average particle size of 1 μm or less. If the average particle size exceeds 1 μm, the coating itself becomes difficult, and the effect of the coating cannot be obtained. Also, LiNi
x Co 1-x O 2 coating layer thickness is 0.5 μm
It is desirable that: If the thickness of the coating layer exceeds 0.5 μm, the movement of Li during charge and discharge is adversely affected. A preferred range is from 0.01 to 0.2 μm. These LiNi x Co 1-x O 2 coatings provide Li
It is desirable to apply compression and shearing force to the Ni x Co 1-x O 2 powder to coat the powder on the positive electrode active material of Li 1 + x (Mn 2-x ) O 4 as the base particle. Thereby, the LiNi x Co 1-x O 2 can be uniformly coated on the positive electrode active material without destroying the positive electrode active material which is the base particle. By forming the above-mentioned LiNi x Co 1-x O 2 coating layer, it became possible to obtain a positive electrode material for a lithium secondary battery having reduced self-discharge and high cycle characteristics without lowering the initial capacity. .
【００１４】[0014]
【実施例】以下、実施例に基づいて説明する。本実施例
は好適な１例にすぎず、本発明はこれらの実施例に限定
されるものではない。したがって、本発明の技術思想の
範囲で種々の変形や他の実施例及び態様を含むものであ
る。本発明の実施に当たって、図１に示すコイン型セル
を用いて電池特性の評価を行った。このコイン型セルは
正極活物質を導電性カーボン及び結着剤としてのポリフ
ッ化ビニリデンとｎ-メチルピロリドンを混合し、ドク
ターブレード法でＳＵＳ板４上に成膜したものを正極８
とした。これにセパレータ７及び負極６としての金属リ
チウム板及び電解液５としてＥＣ／ＤＭＣ溶液を用いて
ＳＵＳ製の上下蓋１、３及びテフロン（登録商標）製の
シールガスケット２にて封入したものを使用した。この
セルにより電池性能として、５５°Ｃでのサイクル試験
をＣ／２充電、１Ｃ放電で１００サイクルまで行った。Embodiments will be described below with reference to embodiments. This embodiment is merely a preferred example, and the present invention is not limited to these embodiments. Therefore, various modifications and other embodiments and aspects are included within the technical idea of the present invention. In carrying out the present invention, battery characteristics were evaluated using the coin-shaped cell shown in FIG. This coin-type cell was prepared by mixing a positive electrode active material with conductive carbon, polyvinylidene fluoride as a binder and n-methylpyrrolidone, and forming a film on a SUS plate 4 by a doctor blade method.
And A separator and a metal lithium plate as the negative electrode 6 and an EC / DMC solution as the electrolyte 5 which are sealed with upper and lower lids 1 and 3 made of SUS and a seal gasket 2 made of Teflon (registered trademark) are used. did. As a battery performance of this cell, a cycle test at 55 ° C. was performed up to 100 cycles of C / 2 charge and 1C discharge.
【００１５】微細粒炭酸マンガンを酸化処理した酸化マ
ンガンを出発原料として、炭酸リチウムと混合し、大気
中７５０°Ｃで熱処理して、スピネル構造のマンガン酸
リチウムをリチウム二次電池用正極材料として得た。こ
の時の平均粒径は出発原料に依存するが、本発明の範囲
内である平均粒径１０μｍに調整した。この正極材料を
母材として、これに平均粒径が０．５μｍのＬｉＮｉｘ
Ｃｏ１-ｘＯ２を０．１μｍの厚さでコーティングし
た。なお、コーティング材は平均粒径５μｍのＬｉＮｉ
ｘＣｏ１-ｘＯ２をボールミルで湿式粉砕し乾燥して準
備した。Using manganese oxide obtained by oxidizing fine manganese carbonate as a starting material, it is mixed with lithium carbonate and heat-treated at 750 ° C. in the air to obtain lithium manganate having a spinel structure as a positive electrode material for a lithium secondary battery. Was. The average particle size at this time depends on the starting material, but was adjusted to an average particle size of 10 μm within the range of the present invention. Using this positive electrode material as a base material, LiNi x having an average particle size of 0.5 μm
Co 1-x O 2 was coated at a thickness of 0.1 μm. The coating material is LiNi having an average particle size of 5 μm.
x Co 1-x O 2 was prepared by wet grinding with a ball mill and drying.
【００１６】[0016]
【表１】 [Table 1]
【００１７】表１に示すように母材のサイクル特性は、
初期放電容量は１１５．２ｍＡｈ／ｇであり、５０サイ
クルまではほぼ一定の比率で低下するが、６０サイクル
目で急激な低下を示す。この低下傾向はさらにサイクル
を増加させると顕著であり、８０サイクルで９８．０ｍ
Ａｈ／ｇ、９０サイクルで８８．１ｍＡｈ／ｇとなっ
た。これに対して、実施例のコーティングした材料のサ
イクル特性は、初期放電容量１０９．４ｍＡｈ／ｇであ
り、５０サイクルまでは母材同様一定の比率で低下す
る。それ以降も低下傾向は同様であるが、８０サイクル
目では９９．２ｍＡｈ／ｇと母材の放電容量を逆転す
る。実施例のサイクル特性は１００サイクル以降も同様
の低下傾向で推移し、２００サイクルを超えても急激な
低下は見られなかった。As shown in Table 1, the cycle characteristics of the base material are as follows:
The initial discharge capacity is 115.2 mAh / g, and decreases at a substantially constant rate until 50 cycles, but shows a sharp decrease at the 60th cycle. This decreasing tendency is remarkable when the cycle is further increased, and 98.0 m in 80 cycles.
Ah / g, 88.1 mAh / g in 90 cycles. On the other hand, the cycle characteristics of the coated material of the example are an initial discharge capacity of 109.4 mAh / g, and decrease at a constant rate like the base material up to 50 cycles. Thereafter, the decrease tendency is the same, but the discharge capacity of the base material is reversed to 99.2 mAh / g at the 80th cycle. The cycle characteristics of the example remained in a similar decreasing tendency even after 100 cycles, and no sharp decrease was observed even after 200 cycles.
【００１８】サイクル劣化率（ｍＡｈ／ｇ／サイクル）
を以下の式で計算し、表２にまとめた。 サイクル劣化率＝（Ｎ回目の放電容量−Ｍ回目の放電容
量／（Ｍ−Ｎ）×１００）Cycle deterioration rate (mAh / g / cycle)
Was calculated by the following equation and summarized in Table 2. Cycle deterioration rate = (Nth discharge capacity−Mth discharge capacity / (M−N) × 100)
【００１９】[0019]
【表２】 [Table 2]
【００２０】表２に示したとおり、母材のサイクルの低
下傾向は５０サイクルを境に急激に悪化したのに対し
て、実施例では５０サイクル以降も同様の低下率で安定
したサイクル劣化率となった。このように本発明のＬｉ
ＮｉｘＣｏ１-ｘＯ２をコーティングしたリチウム二次
電池用正極材料のサイクル特性の向上が著しいことが分
かる。As shown in Table 2, the decrease tendency of the cycle of the base material rapidly deteriorated after 50 cycles, whereas in the embodiment, the cycle deterioration rate was stable at the same rate after 50 cycles. became. Thus, the Li of the present invention
It can be seen that the cycle characteristics of the positive electrode material for a lithium secondary battery coated with Ni x Co 1-x O 2 are remarkably improved.
【００２１】[0021]
【発明の効果】リチウム二次電池用正極材料としてＬｉ
１＋ｘ（Ｍｎ２-ｘ）Ｏ４（０≦ｘ≦０．２０）の化学
式で表されるスピネル化合物を使用し、初期容量を良好
に維持するとともに、高充電率を維持する良好な充電サ
イクル特性を有するＭｎ系正極材料及び同正極材料を用
いたリチウム二次電池を得ることができるという優れた
効果を有する。As described above, Li is used as a positive electrode material for a lithium secondary battery.
1 + x (Mn 2-x ) using O 4 (0 ≦ x ≦ 0.20 ) spinel compound represented by the chemical formula, while maintaining good initial capacity, good charge cycle characteristic of maintaining a high charging rate And a lithium secondary battery using the same Mn-based positive electrode material and the positive electrode material.
【図１】電池特性評価用コイン型セルの断面模式図であ
る。FIG. 1 is a schematic cross-sectional view of a coin-type cell for evaluating battery characteristics.
１ 上蓋 ２ シールガスケット ３ 下蓋 ４ ＳＵＳ板 ５ 電解液 ６ 負極 ７ セパレータ ８ 正極 DESCRIPTION OF SYMBOLS 1 Upper lid 2 Seal gasket 3 Lower lid 4 SUS plate 5 Electrolyte 6 Negative electrode 7 Separator 8 Positive electrode
───────────────────────────────────────────────────── フロントページの続き Ｆターム(参考） 5H029 AJ05 AK03 AK19 AL12 AM03 AM05 AM07 BJ03 CJ05 CJ22 DJ16 HJ02 HJ04 HJ05 HJ08 5H050 AA07 BA17 CA08 CA09 CA29 FA17 FA18 GA07 GA22 HA02 HA04 HA05 HA08 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H029 AJ05 AK03 AK19 AL12 AM03 AM05 AM07 BJ03 CJ05 CJ22 DJ16 HJ02 HJ04 HJ05 HJ08 5H050 AA07 BA17 CA08 CA09 CA29 FA17 FA18 GA07 GA22 HA02 HA04 HA05 HA08
Claims (7)
≦０．２０）の化学式で表される粒状のリチウム二次電
池用正極活物質材料であって、その表面がＬｉＮｉｘＣ
ｏ１-ｘＯ２（０＜ｘ＜１．０）でコーティングされて
いることを特徴とするサイクル特性に優れたＭｎ系正極
材料。1. Li 1 + x (Mn 2-x ) O 4 (0 ≦ x
≦ 0.20) a positive electrode active material for lithium secondary battery of particulate represented by the chemical formula, its surface LiNi x C
A Mn-based positive electrode material excellent in cycle characteristics characterized by being coated with o 1-x O 2 (0 <x <1.0).
≦０．２０）の化学式で表される粒状のリチウム二次電
池用正極活物質材料であって、その表面がＬｉＮｉｘＣ
ｏ１-ｘＯ２（０．７＜ｘ＜０．９）でコーティングさ
れていることを特徴とするサイクル特性に優れたＭｎ系
正極材料。2. Li 1 + x (Mn 2-x ) O 4 (0 ≦ x
≦ 0.20) a positive electrode active material for lithium secondary battery of particulate represented by the chemical formula, its surface LiNi x C
A Mn-based positive electrode material excellent in cycle characteristics characterized by being coated with o 1-x O 2 (0.7 <x <0.9).
ｍ、タップ密度が２．０ｇ／ｃｃ以上であることを特徴
とする請求項１又は２記載のサイクル特性に優れたＭｎ
系正極材料。3. The positive electrode active material has an average particle size of 5 to 20 μm.
3. Mn having excellent cycle characteristics according to claim 1 or 2, wherein the tap density is 2.0 g / cc or more.
System cathode material.
１-ｘＯ２の平均粒径が１μｍ以下であることを特徴と
する請求項１〜３のそれぞれに記載のサイクル特性に優
れたＭｎ系正極材料。4. LiNi x Co to be coated
Mn-based positive electrode material having excellent cycle characteristics according to each of claims 1 to 3 having an average particle size of 1-x O 2 is equal to or is 1μm or less.
グ層の厚さが０．５μｍ以下であることを特徴とする請
求項１〜４のそれぞれに記載のサイクル特性に優れたＭ
ｎ系正極材料。5. The M according to claim 1, wherein the thickness of the coating layer of LiNi x Co 1-x O 2 is 0.5 μm or less.
n-based positive electrode material.
剪断力を与えて母粒子である正極活物質材料にコーティ
ングされたものであることを特徴とする請求項１〜５の
それぞれに記載のサイクル特性に優れたＭｎ系正極材
料。6. The method according to claim 1, wherein the LiNi x Co 1-x O 2 powder is applied to the positive electrode active material as mother particles by applying compression and shearing force. 4. A Mn-based positive electrode material excellent in cycle characteristics described in 1.
正極材料を用いたリチウム二次電池。7. A lithium secondary battery using the Mn-based positive electrode material according to claim 1.
Priority Applications (1)
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|---|---|---|---|
| JP2000364153A JP2002170563A (en) | 2000-11-30 | 2000-11-30 | Manganese system positive electrode material having excellent cycle property and lithium secondary battery using the same |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000364153A JP2002170563A (en) | 2000-11-30 | 2000-11-30 | Manganese system positive electrode material having excellent cycle property and lithium secondary battery using the same |
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|---|---|
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ID=18835145
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| JP2006012433A (en) * | 2004-06-22 | 2006-01-12 | Nichia Chem Ind Ltd | Positive electrode active material for nonaqueous electrolyte secondary battery and nonaqueous electrolyte secondary battery |
| JP2006503789A (en) * | 2002-10-31 | 2006-02-02 | エルジー・ケム・リミテッド | Lithium transition metal oxide with gradient in composition of metal components |
| WO2010029745A1 (en) * | 2008-09-10 | 2010-03-18 | 戸田工業株式会社 | Li-Ni COMPOSITE OXIDE PARTICLE POWDER FOR NON-AQUEOUS ELECTROLYTE SECONDARY BATTERY AND METHOD FOR PRODUCTION THEREOF, AND NON-AQUEOUS ELECTROLYTE SECONDARY BATTERY |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006503789A (en) * | 2002-10-31 | 2006-02-02 | エルジー・ケム・リミテッド | Lithium transition metal oxide with gradient in composition of metal components |
| US7695649B2 (en) | 2002-10-31 | 2010-04-13 | Lg Chem, Ltd. | Lithium transition metal oxide with gradient of metal composition |
| JP2006012433A (en) * | 2004-06-22 | 2006-01-12 | Nichia Chem Ind Ltd | Positive electrode active material for nonaqueous electrolyte secondary battery and nonaqueous electrolyte secondary battery |
| WO2010029745A1 (en) * | 2008-09-10 | 2010-03-18 | 戸田工業株式会社 | Li-Ni COMPOSITE OXIDE PARTICLE POWDER FOR NON-AQUEOUS ELECTROLYTE SECONDARY BATTERY AND METHOD FOR PRODUCTION THEREOF, AND NON-AQUEOUS ELECTROLYTE SECONDARY BATTERY |
| JP2010092848A (en) * | 2008-09-10 | 2010-04-22 | Toda Kogyo Corp | Li-Ni COMPOSITE OXIDE PARTICLE POWDER FOR NONAQUEOUS ELECTROLYTE SECONDARY BATTERY, ITS MANUFACTURING METHOD, AND NONAQUEOUS ELECTROLYTE SECONDARY BATTERY |
| JP2012094483A (en) * | 2011-05-11 | 2012-05-17 | Dainippon Printing Co Ltd | Positive electrode plate for nonaqueous electrolyte secondary battery, nonaqueous electrolyte secondary battery, method of manufacturing positive electrode plate for nonaqueous electrolyte secondary battery, and battery pack |
| CN102709525A (en) * | 2012-05-24 | 2012-10-03 | 奇瑞汽车股份有限公司 | Metal oxide coated lithium nickel manganese oxide material, preparation method of metal oxide coated lithium nickel manganese oxide material and lithium ion battery |
| JP2022139191A (en) * | 2021-03-11 | 2022-09-26 | プライムプラネットエナジー＆ソリューションズ株式会社 | Positive electrode active material and lithium ion secondary battery including the positive electrode active material |
| JP7275180B2 (en) | 2021-03-11 | 2023-05-17 | プライムプラネットエナジー＆ソリューションズ株式会社 | Positive electrode active material and lithium ion secondary battery comprising the positive electrode active material |
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