JP3274993B2 - Cathode materials for lithium secondary batteries - Google Patents
Cathode materials for lithium secondary batteriesInfo
- Publication number
- JP3274993B2 JP3274993B2 JP22698398A JP22698398A JP3274993B2 JP 3274993 B2 JP3274993 B2 JP 3274993B2 JP 22698398 A JP22698398 A JP 22698398A JP 22698398 A JP22698398 A JP 22698398A JP 3274993 B2 JP3274993 B2 JP 3274993B2
- Authority
- JP
- Japan
- Prior art keywords
- lithium
- positive electrode
- electrode material
- lithium secondary
- battery
- 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.)
- Expired - Fee Related
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
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
正極材料に関し、詳しくは電解液との反応性を抑制し、
マンガンの溶出量を抑制し、高温保存性、高温サイクル
特性等の電池の高温特性を向上させたリチウム二次電池
用正極材料に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive electrode material for a lithium secondary battery, and more particularly, to a method for suppressing the reactivity with an electrolytic solution.
The present invention relates to a positive electrode material for a lithium secondary battery in which the amount of manganese eluted is suppressed and the high-temperature characteristics of the battery such as high-temperature storage properties and high-temperature cycle characteristics are improved.
【０００２】[0002]
【従来の技術及び発明が解決しようとする課題】近年の
パソコンや電話等のポータブル化、コードレス化の急速
な進歩によりそれらの駆動用電源としての二次電池の需
要が高まっている。その中でもリチウム二次電池は最も
小型かつ高エネルギー密度を持つため特に期待されてい
る。上記の要望を満たすリチウム二次電池の正極材料と
してはコバルト酸リチウム（ＬｉＣｏＯ2 ）、ニッケル
酸リチウム（ＬｉＮｉＯ2 ）、マンガン酸リチウム（Ｌ
ｉＭｎ2 Ｏ4 ）等がある。これらの複合酸化物はリチウ
ムに対し４Ｖ以上の電位を有していることから、高エネ
ルギー密度を有する電池となり得る。2. Description of the Related Art With the rapid progress of portable and cordless personal computers and telephones in recent years, the demand for secondary batteries as power sources for driving them has been increasing. Among them, lithium secondary batteries are particularly expected because they have the smallest size and high energy density. As the positive electrode material of the lithium secondary battery satisfying the above demands, lithium cobalt oxide (LiCoO 2 ), lithium nickelate (LiNiO 2 ), lithium manganate (L
iMn 2 O 4 ). Since these composite oxides have a potential of 4 V or more with respect to lithium, they can be batteries having a high energy density.
【０００３】上記の複合酸化物のうちＬｉＣｏＯ2 、Ｌ
ｉＮｉＯ2 は、理論容量が２８０ｍＡｈ／ｇ程度である
のに対し、ＬｉＭｎ2 Ｏ4 は１４８ｍＡｈ／ｇと小さい
が、原料となるマンガン酸化物が豊富で安価であること
や、ＬｉＮｉＯ2 のような充電時の熱的不安定性が無い
ことから、ＥＶ用途等に適していると考えられている。[0003] Among the above composite oxides, LiCoO 2 , L
INiO 2, compared to a theoretical capacity of about 280 mAh / g, but LiMn 2 O 4 is as small as 148 mAh / g, and that manganese oxide as a raw material is abundant and inexpensive, charging such as LiNiO 2 Since there is no thermal instability at the time, it is considered to be suitable for EV use and the like.
【０００４】しかしながら、このマンガン酸リチウム
（ＬｉＭｎ2 Ｏ4 ）は、高温においてマンガンが溶出す
るため、高温保存性、高温サイクル特性等の高温での電
池特性に劣るという問題がある。このことが、マンガン
酸リチウムをリチウム二次電池の正極材料として実用化
するための大きな問題となっている。However, since lithium manganate (LiMn 2 O 4 ) elutes manganese at a high temperature, there is a problem that the battery characteristics at a high temperature such as a high temperature storage property and a high temperature cycle characteristic are inferior. This is a major problem for putting lithium manganate into practical use as a positive electrode material of a lithium secondary battery.
【０００５】このことは、高温でマンガンが有機電解液
中に溶出し、溶出したマンガンが負極やセパレーターに
析出して電池反応を阻害するためといわれている。その
ために、マンガン酸リチウムからのマンガンの溶出を抑
制することが、高温保存性、高温サイクル特性を向上す
るために必要であった。It is said that this is because manganese elutes into the organic electrolyte at a high temperature, and the eluted manganese deposits on the negative electrode and the separator to inhibit the battery reaction. Therefore, it is necessary to suppress the elution of manganese from lithium manganate in order to improve high-temperature storage stability and high-temperature cycle characteristics.
【０００６】このために、無機化合物によってマンガン
酸リチウムの表面を被覆することが報告されている。こ
れは、水溶液反応によりマンガン酸リチウム上にニッケ
ル又はコバルトの水酸化物又は酸化物を析出してマンガ
ン酸リチウムを被覆する方法である。しかし、この方法
では製造工程が複雑になるばかりでなく、水溶液中で処
理することによるマンガン酸リチウムのダメージが懸念
される。[0006] For this purpose, it has been reported that the surface of lithium manganate is coated with an inorganic compound. This is a method of coating a lithium manganate by depositing a nickel or cobalt hydroxide or oxide on the lithium manganate by an aqueous solution reaction. However, this method not only complicates the manufacturing process, but also may cause damage to lithium manganate due to treatment in an aqueous solution.
【０００７】従って、本発明の目的は、充電時のマンガ
ン溶出量を抑制し、高温保存性、高温サイクル特性等の
高温での電池特性を向上させたリチウム二次電池用正極
材料を提供することにある。Accordingly, an object of the present invention is to provide a positive electrode material for a lithium secondary battery in which the amount of manganese eluted during charging is suppressed and battery characteristics at high temperatures such as high-temperature storage properties and high-temperature cycle characteristics are improved. It is in.
【０００８】[0008]
【０００９】本発明者らは、マンガン酸リチウムの表面
に、特定の有機化合物を化学的又は物理的に被覆するこ
とにより、上記目的を達成し得ることを知見した。The present inventors have found that the above object can be achieved by chemically or physically coating a specific organic compound on the surface of lithium manganate.
【００１０】本発明は、上記知見に基づきなされたもの
で、カルボキシル基を有する有機化合物でマンガン酸リ
チウムの表面を化学的又は物理的に被覆したことを特徴
とするリチウム二次電池用正極材料を提供するものであ
る。[0010] The present invention has been made based on the above findings, and provides a positive electrode material for a lithium secondary battery, wherein the surface of lithium manganate is chemically or physically coated with an organic compound having a carboxyl group. To provide.
【００１１】[0011]
【発明の実施の形態】以下、本発明を詳細に説明する。
本発明のリチウム二次電池用正極材料は、カルボキシル
基を有する有機化合物でマンガン酸リチウム（ＬｉＭｎ
2 Ｏ4)の表面を化学的又は物理的に被覆するものであ
る。BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The positive electrode material for lithium secondary battery of the present invention, the carboxyl
Lithium manganate organic compound having a group (LiMn
2 O 4 ) is chemically or physically coated.
【００１２】このマンガン酸リチウムの製造に用いられ
るリチウム原料としては、炭酸リチウム（Ｌｉ2 Ｃ
Ｏ3 ）、硝酸リチウム（ＬｉＮＯ3 ）、水酸化リチウム
（ＬｉＯＨ）等が挙げられる。また、マンガン原料とし
ては、二酸化マンガン（ＭｎＯ2）、三酸化二マンガン
（Ｍｎ2 Ｏ3 ）、オキシ水酸化マンガン（ＭｎＯＯＨ）
等が使用できる。マンガン原料としてはＭｎＯ2 が特に
好適に使用できる。その理由としては、ＭｎＯ2 はリチ
ウムの一次電池用正極材料として利用されており、リチ
ウムを構造内に取り込みやすいことや、特に電解ＭｎＯ
2 ではタップ密度を大きくしやすいことが挙げられる。
なお、マンガン原料として二酸化マンガンを用いた場合
に、リチウム原料として水酸化リチウムを用いると、ロ
ータリーキルン焼成の場合には、炉心管への付着が激し
く実用上問題があり、また、こうして得られたマンガン
酸リチウムをリチウム二次電池の正極材料に使用する
と、電池性能が低下するので好ましくない。これらのリ
チウム及びマンガン原料の中で、二酸化マンガンと炭酸
リチウムの組み合わせが最も好ましい。As a lithium raw material used for producing this lithium manganate, lithium carbonate (Li 2 C
O 3 ), lithium nitrate (LiNO 3 ), lithium hydroxide (LiOH) and the like. Manganese raw materials include manganese dioxide (MnO 2 ), dimanganese trioxide (Mn 2 O 3 ), manganese oxyhydroxide (MnOOH)
Etc. can be used. MnO 2 can be particularly preferably used as a manganese raw material. The reason is that MnO 2 is used as a positive electrode material for a lithium primary battery, and it is easy to incorporate lithium into the structure.
In 2 , the tap density can be easily increased.
When manganese dioxide is used as the manganese raw material and lithium hydroxide is used as the lithium raw material, in the case of rotary kiln firing, there is a serious problem in practical use due to severe adhesion to the furnace core tube. It is not preferable to use lithium oxide as a positive electrode material of a lithium secondary battery because battery performance is reduced. Among these lithium and manganese raw materials, a combination of manganese dioxide and lithium carbonate is most preferred.
【００１３】これらリチウム及びマンガン原料は、より
大きな反応断面積を得るために、原料混合前あるいは後
に粉砕することも好ましい。秤量、混合された原料はそ
のままでもあるいは造粒して使用してもよい。造粒方法
は、湿式でも乾式でも良く、押し出し造粒、転動造粒、
流動造粒、混合造粒、噴霧乾燥造粒、加圧成形造粒ある
いはロール等を用いたフレーク造粒でも良い。These lithium and manganese raw materials are preferably ground before or after mixing the raw materials in order to obtain a larger reaction cross section. The weighed and mixed raw materials may be used as they are or may be granulated. Granulation method may be wet or dry, extruding granulation, rolling granulation,
Fluid granulation, mixed granulation, spray drying granulation, pressure molding granulation, or flake granulation using a roll or the like may be used.
【００１４】このようにして得られた原料は、焼成炉内
に投入され、６００〜１０００℃で焼成することによっ
て、マンガン酸リチウムが得られる。単一相のマンガン
酸リチウムを得るには６００℃程度の焼成温度でも十分
であるが、焼成温度が低いと粒成長が進まないので７５
０℃以上の焼成温度、好ましくは８５０℃以上の焼成温
度が必要となる。ここで用いられる焼成炉としては、ロ
ータリーキルンあるいは静置炉等が例示される。焼成時
間は１時間以上、好ましくは５〜２０時間である。この
マンガン酸リチウムの中でもスピネル型マンガン酸リチ
ウムが４Ｖ級の電位を有することから特に好ましく用い
られる。The raw material thus obtained is put into a firing furnace and fired at 600 to 1000 ° C. to obtain lithium manganate. A sintering temperature of about 600 ° C. is sufficient to obtain a single-phase lithium manganate, but if the sintering temperature is low, the grain growth does not proceed.
A firing temperature of 0 ° C. or higher, preferably a firing temperature of 850 ° C. or higher is required. Examples of the firing furnace used here include a rotary kiln and a stationary furnace. The firing time is 1 hour or more, preferably 5 to 20 hours. Among these lithium manganates, spinel type lithium manganate is particularly preferably used because it has a potential of 4V class.
【００１５】また、カルボキシル基を有する有機化合物
としては、具体的にはマロン酸、こはく酸、グルタル
酸、アジピン酸等の有機酸が挙げられる。これらの中で
もとりわけマロン酸が好ましく用いられる。[0015] As the organic compound having a carboxyl group, the concrete malonic acid, succinic acid, glutaric acid, and organic acids such as adipic acid. Among these
Based Riwake malonate is preferably used.
【００１６】このカルボキシル基を有する有機化合物の
被覆量は、上記マンガン酸リチウムに対して、好ましく
は０．０１〜１．０重量％、さらに好ましくは０．０５
〜０．５重量％である。有機化合物の被覆量が０．０１
重量％未満では高温保存性が低下し、また２．０重量％
を超えると初期容量が低下する。The coating amount of the organic compound having a carboxyl group is preferably 0.01 to 1.0% by weight, more preferably 0.05 to 1.0% by weight based on the above-mentioned lithium manganate.
~ 0.5% by weight. Organic compound coverage of 0.01
If the content is less than 20% by weight, the high-temperature preservability is reduced, and 2.0% by weight.
If it exceeds, the initial capacity decreases.
【００１７】次に、本発明のリチウム二次電池用正極材
料の製造方法について説明する。本発明では、このマン
ガン酸リチウムとカルボキシル基を有する有機化合物を
混合し、例えば室温〜４００℃、好ましくは８０〜２０
０℃で熱処理してリチウム二次電池用正極材料とする。
熱処理温度が４００℃超では高温保存性に劣る。また、
熱処理時間は３０分〜２４時間が適当である。Next, a method for producing the positive electrode material for a lithium secondary battery of the present invention will be described. In the present invention, this lithium manganate and an organic compound having a carboxyl group are mixed, and for example, room temperature to 400 ° C., preferably 80 to 20 ° C.
Heat treated at 0 ° C. to obtain a positive electrode material for a lithium secondary battery.
When the heat treatment temperature is higher than 400 ° C., the high-temperature preservability is poor. Also,
The heat treatment time is suitably from 30 minutes to 24 hours.
【００１８】本発明のリチウム二次電池は、上記正極材
料とアセチレンブラック等の導電材とテフロンバインダ
ー等の結着剤とを混合して正極合剤とし、また、負極に
はリチウム又はカーボン等のリチウムを吸蔵、脱蔵でき
る材料が用いられ、非水系電解質としては、六フッ化リ
ンリチウム（ＬｉＰＦ6 ）等のリチウム塩をエチレンカ
ーボネート−ジメチルカーボネート等の混合溶媒に溶解
したものが用いられるが、特に限定されるものではな
い。The lithium secondary battery of the present invention comprises a mixture of the above-mentioned positive electrode material, a conductive material such as acetylene black and a binder such as a Teflon binder to form a positive electrode mixture. A material capable of absorbing and desorbing lithium is used. As the non-aqueous electrolyte, a material obtained by dissolving a lithium salt such as lithium hexafluorophosphate (LiPF 6 ) in a mixed solvent such as ethylene carbonate-dimethyl carbonate is used. There is no particular limitation.
【００１９】本発明のリチウム二次電池は、充電状態で
のマンガンの溶出を抑制することができるので、高温保
存性、高温サイクル特性等の高温での電池特性を向上さ
せることができる。The lithium secondary battery of the present invention can suppress the elution of manganese in the charged state, so that the battery characteristics at high temperatures such as high-temperature storage characteristics and high-temperature cycle characteristics can be improved.
【００２０】[0020]
【実施例】以下、実施例等に基づき本発明を具体的に説
明する。EXAMPLES Hereinafter, the present invention will be specifically described based on examples and the like.
【００２１】〔実施例１〕二酸化マンガン１ｋｇに炭酸
リチウム２３０ｇを加えて混合し、箱型炉中８００℃で
２０時間焼成してマンガン酸リチウムを得た。このよう
にして得られたマンガン酸リチウム１００ｇとエタノー
ルを溶解させたマロン酸０．５ｇを混合し、１２０℃で
１０時間加熱して正極材料を得た。得られた正極材料９
０重量部、導電剤としてアセチレンブラック３重量部及
び結着剤としてテフロン７重量部を混合して正極合剤を
作製した。Example 1 1 kg of manganese dioxide was added with 230 g of lithium carbonate, mixed, and fired in a box furnace at 800 ° C. for 20 hours to obtain lithium manganate. 100 g of the lithium manganate thus obtained and 0.5 g of malonic acid in which ethanol was dissolved were mixed and heated at 120 ° C. for 10 hours to obtain a positive electrode material. The obtained cathode material 9
0 parts by weight, 3 parts by weight of acetylene black as a conductive agent, and 7 parts by weight of Teflon as a binder were mixed to prepare a positive electrode mixture.
【００２２】このようにして得られた正極合剤を用いて
２０１６型コイン電池を作製した。負極には金属リチウ
ムを、電解液には１モルＬｉＰＦ6 ／エチレンカーボネ
ート−ジメチルカーボネート（１：１）混合溶媒を用い
た。A 2016 type coin battery was manufactured using the positive electrode mixture thus obtained. Metal lithium was used for the negative electrode, and a 1 mol LiPF 6 / ethylene carbonate-dimethyl carbonate (1: 1) mixed solvent was used for the electrolytic solution.
【００２３】このようにして得られた電池について、２
５℃で電流密度０．５ｍＡ／ｃｍ2として、電圧４．３
Ｖから３．０Ｖの範囲で５サイクル充放電試験を行なっ
た。その後、この電池を５０℃の環境下で同条件で５０
サイクル充放電し、１サイクル目の放電容量を１００と
した時の、５０サイクル目の放電容量を容量維持率とし
て確認した。５０℃での初期放電容量と５０サイクル後
の容量維持率の測定結果を表１に示す。With respect to the battery thus obtained, 2
At a current density of 0.5 mA / cm 2 at 5 ° C., a voltage of 4.3
A 5-cycle charge / discharge test was performed in the range of V to 3.0 V. Then, the battery was stored under the same conditions at 50 ° C. for 50 hours.
When the charge / discharge cycle was performed and the discharge capacity at the first cycle was set to 100, the discharge capacity at the 50th cycle was confirmed as the capacity retention ratio. Table 1 shows the measurement results of the initial discharge capacity at 50 ° C. and the capacity retention after 50 cycles.
【００２４】〔実施例２〕マンガン酸リチウムと混合す
る有機化合物をこはく酸０．５ｇとし、加熱温度を１５
０℃とした以外は、実施例１と同様に正極材料の合成、
電池の作製を行い評価した。５０℃での初期放電容量と
５０サイクル後の容量維持率の測定結果を表１に示す。Example 2 The organic compound mixed with lithium manganate was 0.5 g of succinic acid, and the heating temperature was 15
Except for 0 ° C., the synthesis of the positive electrode material was performed in the same manner as in Example 1,
A battery was prepared and evaluated. Table 1 shows the measurement results of the initial discharge capacity at 50 ° C. and the capacity retention after 50 cycles.
【００２５】〔実施例３〕マンガン酸リチウムと混合す
る有機化合物をグルタル酸０．５ｇとし、加熱温度を１
００℃とした以外は、実施例１と同様に正極材料の合
成、電池の作製を行い評価した。５０℃での初期放電容
量と５０サイクル後の容量維持率の測定結果を表１に示
す。Example 3 The organic compound to be mixed with lithium manganate was 0.5 g of glutaric acid, and the heating temperature was 1
A positive electrode material was synthesized and a battery was fabricated and evaluated in the same manner as in Example 1 except that the temperature was changed to 00 ° C. Table 1 shows the measurement results of the initial discharge capacity at 50 ° C. and the capacity retention after 50 cycles.
【００２６】〔実施例４〕マンガン酸リチウムと混合す
る有機化合物をアジピン酸０．５ｇとし、加熱温度を１
５０℃とした以外は、実施例１と同様に正極材料の合
成、電池の作製を行い評価した。５０℃での初期放電容
量と５０サイクル後の容量維持率の測定結果を表１に示
す。Example 4 The organic compound to be mixed with lithium manganate was 0.5 g of adipic acid, and the heating temperature was 1
Except that the temperature was changed to 50 ° C., the synthesis of a positive electrode material and the production of a battery were performed and evaluated in the same manner as in Example 1. Table 1 shows the measurement results of the initial discharge capacity at 50 ° C. and the capacity retention after 50 cycles.
【００２７】〔実施例５〕マンガン酸リチウムと混合す
る有機化合物をマロン酸０．０１ｇとした以外は、実施
例１と同様に正極材料の合成、電池の作製を行い評価し
た。５０℃での初期放電容量と５０サイクル後の容量維
持率の測定結果を表１に示す。Example 5 A positive electrode material was synthesized and a battery was prepared and evaluated in the same manner as in Example 1, except that the organic compound mixed with lithium manganate was changed to 0.01 g of malonic acid. Table 1 shows the measurement results of the initial discharge capacity at 50 ° C. and the capacity retention after 50 cycles.
【００２８】〔実施例６〕マンガン酸リチウムと混合す
る有機化合物をマロン酸１．０ｇとした以外は、実施例
１と同様に正極材料の合成、電池の作製を行い評価し
た。５０℃での初期放電容量と５０サイクル後の容量維
持率の測定結果を表１に示す。Example 6 A positive electrode material was synthesized and a battery was prepared and evaluated in the same manner as in Example 1 except that the organic compound mixed with lithium manganate was changed to 1.0 g of malonic acid. Table 1 shows the measurement results of the initial discharge capacity at 50 ° C. and the capacity retention after 50 cycles.
【００２９】〔実施例７〕マンガン酸リチウムと混合す
る有機物をマロン酸０．００１ｇとした以外は、実施例
１と同様に正極材料の合成、電池の作製を行い評価し
た。５０℃での初期放電容量と５０サイクル後の容量維
持率の測定結果を表１に示す。Example 7 A positive electrode material was synthesized and a battery was prepared and evaluated in the same manner as in Example 1 except that the amount of the organic substance mixed with lithium manganate was changed to 0.001 g of malonic acid. Table 1 shows the measurement results of the initial discharge capacity at 50 ° C. and the capacity retention after 50 cycles.
【００３０】〔実施例８〕マンガン酸リチウムと混合す
る有機化合物をマロン酸２．０ｇとした以外は、実施例
１と同様に正極材料の合成、電池の作製を行い評価し
た。５０℃での初期放電容量と５０サイクル後の容量維
持率の測定結果を表１に示す。Example 8 A positive electrode material was synthesized and a battery was prepared and evaluated in the same manner as in Example 1, except that the organic compound mixed with lithium manganate was changed to 2.0 g of malonic acid. Table 1 shows the measurement results of the initial discharge capacity at 50 ° C. and the capacity retention after 50 cycles.
【００３１】〔比較例１〕マンガン酸リチウムに有機化
合物を混合しなかった以外は、実施例１と同様に正極材
料の合成、電池の作製を行い評価した。５０℃での初期
放電容量と５０サイクル後の容量維持率の測定結果を表
１に示す。Comparative Example 1 A positive electrode material was synthesized and a battery was prepared and evaluated in the same manner as in Example 1 except that no organic compound was mixed with lithium manganate. Table 1 shows the measurement results of the initial discharge capacity at 50 ° C. and the capacity retention after 50 cycles.
【００３２】[0032]
【表１】 [Table 1]
【００３３】表１に示されるように、実施例１〜８は、
初期放電容量及び高温保存後容量維持率に優れている。
特に、各有機化合物を一定範囲で被覆した実施例１〜６
は、比較例１に比較して、初期放電容量を同等に維持し
つつ、高温保存後容量維持率を大幅に向上させることが
できる。As shown in Table 1, Examples 1 to 8
Excellent initial discharge capacity and capacity retention after high temperature storage.
In particular, Examples 1 to 6 in which each organic compound was coated in a certain range.
Can significantly improve the capacity retention rate after high-temperature storage, while maintaining the initial discharge capacity equal to that of Comparative Example 1.
【００３４】図１にマロン酸のＴＧ−ＤＴＡ曲線、図２
に実施例１のＴＧ−ＤＴＡ曲線をそれぞれ示す。マロン
酸には５００℃までに発熱ピークは見られないが（図
１）、実施例１は３００℃付近に重量減少を伴う発熱ピ
ークが見られる（図２）。これは、マロン酸のカルボキ
シル基がマンガン酸リチウム中のマンガンと何らかの結
合をしていることを示しており、昇温によりこの結合が
切れ、被覆した有機化合物が燃焼するときに発熱が起こ
る。従って、本実施例では被覆した有機化合物とマンガ
ン酸リチウムが化学結合しているが、単なる物理的な被
覆だけでもマンガンの溶出は抑制できる。FIG. 1 shows a TG-DTA curve of malonic acid, and FIG.
2 shows TG-DTA curves of Example 1. Malonic acid has no exothermic peak up to 500 ° C. (FIG. 1), but in Example 1, an exothermic peak accompanied by weight loss is observed at around 300 ° C. (FIG. 2). This indicates that the carboxyl group of malonic acid has some kind of bond with manganese in lithium manganate, and this bond is broken by raising the temperature, and heat is generated when the coated organic compound burns. Therefore, in the present embodiment, the coated organic compound and lithium manganate are chemically bonded, but leaching of manganese can be suppressed by merely physical coating.
【００３５】[0035]
【発明の効果】以上説明したように、本発明のリチウム
二次電池用正極材料は、充電時のマンガン溶出量を抑制
し、高温保存性、高温サイクル特性等の高温での電池特
性を向上させることができる。As described above, the positive electrode material for a lithium secondary battery of the present invention suppresses the amount of manganese eluted during charging and improves battery characteristics at high temperatures such as high-temperature preservability and high-temperature cycle characteristics. be able to.
【図１】図１は、マロン酸のＴＧ−ＤＴＡ曲線を示すグ
ラフ。FIG. 1 is a graph showing a TG-DTA curve of malonic acid.
【図２】図２は、実施例１のＴＧ−ＤＴＡ曲線を示すグ
ラフ。FIG. 2 is a graph showing a TG-DTA curve of Example 1.
フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) H01M 4/58 H01M 4/02 H01M 10/40 Continuation of the front page (58) Field surveyed (Int.Cl. 7 , DB name) H01M 4/58 H01M 4/02 H01M 10/40
Claims (3)
ンガン酸リチウムの表面を被覆したことを特徴とするリ
チウム二次電池用正極材料。1. A positive electrode material for a lithium secondary battery, wherein the surface of lithium manganate is coated with an organic compound having a carboxyl group .
チウムに対して０．０１〜１．０重量％であることを特
徴とする請求項１に記載のリチウム二次電池用正極材
料。2. The positive electrode material for a lithium secondary battery according to claim 1, wherein the coating amount of the organic compound is 0.01 to 1.0% by weight based on lithium manganate.
用いたリチウム二次電池。Wherein the first aspect or a lithium secondary battery using the cathode material according to 2.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22698398A JP3274993B2 (en) | 1998-08-11 | 1998-08-11 | Cathode materials for lithium secondary batteries |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22698398A JP3274993B2 (en) | 1998-08-11 | 1998-08-11 | Cathode materials for lithium secondary batteries |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000058055A JP2000058055A (en) | 2000-02-25 |
| JP3274993B2 true JP3274993B2 (en) | 2002-04-15 |
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ID=16853677
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002101869A1 (en) * | 2001-06-07 | 2002-12-19 | Mitsubishi Chemical Corporation | Lithium secondary cell |
| CN1324731C (en) * | 2003-07-15 | 2007-07-04 | 新乡无氧铜材总厂 | Preparation technology of lithium manganese oxide positive electrode material for lithium ion battery |
| CA2749696C (en) | 2009-01-20 | 2018-06-05 | Toda Kogyo Corporation | Positive electrode active material for secondary batteries and process for producing thereof |
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| JPH11224664A (en) * | 1998-02-06 | 1999-08-17 | Nikki Chemcal Co Ltd | Lithium-ion secondary battery having high moisture resistance and high safety |
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