JP4034940B2 - Lithium secondary battery using non-aqueous electrolyte - Google Patents

Lithium secondary battery using non-aqueous electrolyte Download PDF

Info

Publication number
JP4034940B2
JP4034940B2 JP2001051689A JP2001051689A JP4034940B2 JP 4034940 B2 JP4034940 B2 JP 4034940B2 JP 2001051689 A JP2001051689 A JP 2001051689A JP 2001051689 A JP2001051689 A JP 2001051689A JP 4034940 B2 JP4034940 B2 JP 4034940B2
Authority
JP
Japan
Prior art keywords
positive electrode
lithium
secondary battery
electrolyte
lithium secondary
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
Application number
JP2001051689A
Other languages
Japanese (ja)
Other versions
JP2002260728A (en
Inventor
和宏 立花
辰夫 仁科
孝志 遠藤
幸裕 佐藤
徹 藤原
智統 鈴木
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Japan Science and Technology Agency
National Institute of Japan Science and Technology Agency
Original Assignee
Japan Science and Technology Agency
National Institute of Japan Science and Technology Agency
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Japan Science and Technology Agency, National Institute of Japan Science and Technology Agency filed Critical Japan Science and Technology Agency
Priority to JP2001051689A priority Critical patent/JP4034940B2/en
Publication of JP2002260728A publication Critical patent/JP2002260728A/en
Application granted granted Critical
Publication of JP4034940B2 publication Critical patent/JP4034940B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

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

Landscapes

  • Cell Electrode Carriers And Collectors (AREA)
  • Secondary Cells (AREA)

Description

【０００１】
【産業上の利用分野】
本発明は、正極集電体表面の不動態皮膜を安定化し、耐久性に優れたリチウム二次電池に関する。
【０００２】
【従来技術及び問題点】
リチウム二次電池は、電気容量が大きく、充放電の可逆性に優れ、過充電時にも安定である長所を活用し、広範な分野で電力源に使用されている。
通常のリチウム二次電池では、リチウムイオンを含む遷移金属との複合酸化物（活性物質）及び炭素等（導電助剤）を有機バインダーでアルミニウム箔（集電体）上に固着させた正極と、リチウムイオンの脱挿入可能な炭素材料粉末等を有機ポリマーのバインダで銅箔（集電体）上に固着させた負極が使用される。有機電解液を含浸させたセパレータを介在させて正極及び負極を捲回することにより、高エネルギー密度で高サイクル特性を示す二次電池が得られる。
【０００３】
リチウム二次電池の普及に伴って、リチウム二次電池の長寿命化が種々検討されている。構造安定性をもつ活性物質の開発や化学的に安定な電解液の開発によってリチウム二次電池の長寿命化が図られているが、何れも電池各部材の長寿命化に留まり、電池デバイス内における部材間の相互作用を十分に検討したものではない。
【０００４】
【課題を解決するための手段】
本発明は、このような問題を解消すべく案出されたものであり、正極集電体に使用される金属又は合金の表面に保護作用の強い不動態皮膜を形成することによって、電池容量の劣化が抑制されたリチウム二次電池を提供することを目的とする。
【０００５】
本発明のリチウム二次電池は、その目的を達成するため、リチウム複合酸化物を正極活性物質、フッ素を含むアニオンのリチウム塩を主電解質、不動態皮膜が形成される金属を正極集電体とするリチウム二次電池において、副電解質に含酸素リチウム塩又は水分が添加されていることを特徴とする。
【０００６】
副電解質に添加される含酸素リチウム塩には、塩素酸リチウム，ヨウ素酸リチウム，炭酸リチウム，ケイ酸リチウム，水酸化リチウムから選ばれた１種又は２種以上が使用される。正極集電体には、表面が不動態皮膜で覆われるアルミニウム，タンタル，チタン，ハフニウム，ジルコニウム，亜鉛，タングステン，ビスマス，アンチモンから選ばれた金属又は合金やステンレス鋼が使用される。
【０００７】
【実施の形態】
リチウム二次電池は、たとえば図１に示すように、セパレータ１を挟んで正極２及び負極３を捲回して電池缶４に収容し、セパレータ１に注入した電解液に接触させている。電池ケース４の底部には負極端子５が組み込まれ、正極２はスペーサ６を介して正極端子７に接続される。電池ケース４は、パッキン８を用いてキャップ９を装着することにより封止される。
【０００８】
正極２は、アルミニウム，タンタル，チタン，ハフニウム，ジルコニウム，亜鉛，タングステン，ビスマス，アンチモンから選ばれたバルブメタル又はステンレス鋼が集電体素材として使用される。バルブメタル及びステンレス鋼は、雰囲気中の酸素と反応し、保護作用のある不動態皮膜を表面に生成する。
正極活性物質を含む正極合剤を素材に塗布し、乾燥させることによって正極集電体が作製される。
【０００９】
正極活性物質には、ＬｉＭｎＯ2，ＬｉＭｎ2Ｏ4，ＬｉＮｉＯ2，ＬｉＣｏＯ2，ＬｉＶＯ2，ＬｉＶ2Ｏ4，ＬｉＣｒＯ2，ＬｉＦｅＯ2，ＬｉＴｉＯ2，ＬｉＳｃＯ2，ＬｉＹＯ2等のリチウム複合酸化物が使用される。リチウム複合酸化物は、Ｎａ，Ｋ，Ｒｂ，Ｃｓ、Ｆｒ等のアルカリ金属、Ｂｅ，Ｍｇ，Ｃａ，Ｓｒ，Ｂａ，Ｒａ等のアルカリ土類金属、Ａｌ，Ｚｎ，Ｇａ，Ｆｅ，Ｃｄ，Ｉｎ，Ｓｂ，Ｈｇ，Ｔｉ，Ｐｂ，Ｂｉ，Ｐｏ等の典型金属の化合物又は塩を含むことができる。なかでも、ＬｉＭｎＯ2中のＭｎは、地殻中元素比が高く、低価格で環境にも優しいことから次世代リチウム二次電池の活性物質として注目されている。
【００１０】
主電解質には、ＬｉＢＦ4，ＬｉＰＦ6，ＬｉＡｓＦ，ＬｉＳｂＦ6，ＬｉＣＦ3ＳＯ3，Ｌｉ(ＣＦ3ＳＯ2)2Ｎ，Ｌｉ(ＣＦ3ＳＯ2)3Ｃ等、フッ素アニオンを含むリチウム塩が使用される。なかでも、ＬｉＢＦ4は、ＬｉＰＦ6と同様に不動態皮膜を安定化させる作用が最も強く、ＬｉＰＦ6よりも安価で、熱力学的な安定性もＬｉＰＦ6より優れ、更に副電解質の添加に対してＬｉＰＦ6よりも安定であることから、好適な主電解質として使用される。
【００１１】
このリチウム二次電池において、水分が含まれないほど電池性能が良くなるものと従来から考えられてきた。本発明者等は、電池性能に及ぼす水分の影響を実際に調査・研究したところ、所定量の水分を添加すると従来の定説とは逆に電池性能が向上することを見出した。
【００１２】
水分が電池性能を向上させる理由は明らかではないものの、フッ化物系の皮膜が酸化物系になることに起因するものと推察される。すなわち、水分添加によって正極集電体表面に生成している不動態皮膜が安定化し、分解過電圧が増大し、電解質の分解等、電池内部の副反応が抑制され、実施例にもみられるように電池の可逆性が向上する。因みに、充放電を１０サイクル程度繰り返した場合に電池容量の低下が９５％程度に留まる。電池性能の向上効果は、本発明者等の実験結果から、ＬｉＰＦ6を電解質に用いた場合に３００〜４００ｐｐｍの水分濃度で、ＬｉＢＦ4を電解質に用いた場合に３００〜９００ｐｐｍの水分濃度で顕著であった。
【００１３】
電池性能の向上は、添加された水分が酸素供与物質として正極集電体に作用し、正極集電体表面にある不動態皮膜が緻密安定化した結果と推定される。そこで、水分添加に代えて硝酸リチウム，塩素酸リチウム，ヨウ素酸リチウム，炭酸リチウム，ケイ酸リチウム，水酸化リチウムから選ばれた１種又は２種以上の含酸素リチウム塩を主電解質に添加したところ、この場合も同様に電池性能の向上がみられた。
【００１４】
正極集電体表面に生成する不動態皮膜は、フッ素を含むアニオンのリチウム塩を主電解質とすることによっても緻密で強固な皮膜となる。すなわち、フッ素を含む有機電解質中で高電場に曝されるため、保護作用の強い強固で緻密な不動態皮膜が生成する。この不動態皮膜は，電池性能を劣化させる原因である正極集電体の腐食や電解質の分解と密接な関係があり、環境遮断機能を強化することによって電池のサイクル特性が向上する。
【００１５】
［参考例１］ＬｉＭｎ2Ｏ4を正極活性物質に用い、正極活性物質３０ｍｇにアセチレンブラック（導電助剤）を十分混合した後、ポリビニリデンフルオライド（ＰＶＤＦ）及びN-メチルピロリドン（ＮＭＰ）を一滴加えてメノウ乳鉢上で混練し、ラバー状の正極合剤を用意した。正極集電体は、純度９９．９９％のアルミニウム箔を直径８ｍｍに打ち抜き、純度９９．９９９％，径０．５ｍｍのアルミニウムワイヤをスポット溶接することにより作製した。正極集電体に正極合剤を塗布し、治具を用いて１トン／ｃｍ2×１分でハンドプレスした後、真空雰囲気で１８０℃×４時間の乾燥処理を施すことにより試料電極を作製した。
【００１６】
試料電極１１を対極１２，参照極１３と共にトールビーカ１４に収納し、三極セル（図２）を組み立てた。対極１２，参照極１３には、リチウム箔を使用した。プロピレンカーボネート（ＰＣ）：1,2-ジメトキシエタン（ＤＭＥ）＝１：１（体積比）の混合溶媒に１Ｍ六フッ化燐酸リチウム（ＬｉＰＦ6）又は１Ｍ四フッ化ホウ酸リチウム（ＬｉＢＦ4）を加えた電解質１５をトールビーカ１４に注入し、Ａｒガスを封入した。各電極１１〜１３はＳＵＳ３０４ステンレス鋼線１６で外部に引き出され、絶縁性のキャップ１７を装着した後、絶縁シート１８で密閉封止した。
【００１７】
２５±０．５℃に保持したインキュベータに三極セルを配置し、+３．５〜４．４Ｖ vs. Ｌｉ/Ｌｉ+の電位範囲において定電流（０．４ｍＡ／ｃｍ2＝０．０９Ｃレート）で充放電試験した。試験結果を電解質１５の水分濃度で整理したところ、表１の結果が得られた。
【００１８】
電解質１５の水分濃度は、カールフィッシャー水分計を用いて測定した。意図的に水分を電化しなかった電解質（水分無添加の電解質）では、電解質原料に起因する水分が濃度８５．３ｐｐｍで含まれていた。他方、原料混練時に水分を添加した電解質（水分添加の電解質）では、水分濃度が４１４．７ｐｐｍであった。
【００１９】
表１の試験結果にみられるように、水分添加の電解質では、１サイクル目の理論容量１４８ｍＡ・ｈ／ｇに対して１２５．７ｍＡ・ｈ／ｇまで充電できた。また、１サイクル目に対する８サイクル目の容量劣化率は、６．２％であった。これに対し、水分無添加の電解質では、１サイクル目に１１８．２ｍＡ・ｈ／ｇまで充電できたが、１サイクル目に対する８サイクル目の容量劣化率は３２．８％と大幅に低下していた。
【００２０】
この対比から明らかなように、ＬｉＢＦ4／ＰＣ＋ＤＭＥ又はＬｉＰＦ6／ＰＣ＋ＤＭＥの電解質に水分を添加すると、１サイクル目の充電容量こそ若干劣ることもあるが、サイクル特性の大幅な向上が確認された。
充放電が繰り返された三極セルから試料電極１１を取り出し、試料電極１１の表面をＸＰＳ分析したところ、不動態皮膜の酸素濃度が高くなっていた。酸素濃度の増加は、過電圧の大きく安定した皮膜がアルミニウム箔表面に形成していることを意味し、不動態皮膜の安定化によって容量劣化率の低下が抑えられたことが窺われる。
【００２１】

Figure 0004034940
【００２２】
［実施例１］純度９９．９９％，厚み０．１ｍｍのアルミニウム箔をアルカリ脱脂し、ＬｉＭｎ2Ｏ4（活性物質）及びアセチレンブラック（導電助剤）を塗布して試料電極１１を作製した。１Ｍ ＬｉＢＦ4／ＰＣ＋ＤＭＥ（５０：５０）及び１ＭＬｉＰＦ6／ＰＣ＋ＤＭＥ（５０：５０）にＬｉＮＯ3（酸素供与物質）を０ｐｐｍ，３００ｐｐｍ，６００ｐｐｍ添加した電解質１５を用意した。試料電極１１をＰｔ電極（対極２），Ａｇ参照極３（+３．０Ｖ vs. Ｌｉ／Ｌｉ+）と共にトールビーカ１４に収容し、Ａｒ置換グローブボックス内で実施例１と同様に三極セルを組み立てた。
【００２３】
作製した三極セルを充放電試験し電池性能を評価した。電解質１５中で試料電極１１を５Ｖ vs. Ａｇの定電位に保持したとき、不動態皮膜の漏れ電流は図３に示すように経時変化した。すなわち、ＬｉＮＯ3無添加の場合に比較して、ＬｉＮＯ3を３００ｐｐｍ添加した場合に約３０％，６００ｐｐｍ添加した場合に約６０％と正極集電体の漏れ電流が大幅に低下した。
【００２４】
漏れ電流が少なかったＬｉＮＯ3６００ｐｐｍ添加の三極セルから試料電極１１を取り出し、試料電極１１の表面をＸＰＳ分析したところ、不動態皮膜の酸素濃度が増加していた。酸素濃度の増加は、ＬｉＮＯ3が酸素供与物質として働き，不動態皮膜を強化したことを意味し、その結果が漏れ電流の現象に現れている。
また、充放電サイクルごとに放電容量を測定したところ、図４にみられるように電解液中のＬｉＮＯ3濃度増加に従って放電容量が増加し、しかもサイクルごとの容量減少が抑えられた。
【００２５】
ＬｉＮＯ3に代えて他の含酸素リチウム塩を使用した場合でも、同様に正極集電体表面の不動態皮膜が強化され、サイクル特性の低下が抑制された。材料組成，アルミニウム箔の表面処理（熱処理），正極合剤の水分，電解液の水分やＬｉＮＯ3濃度等、他の要因によって不動態皮膜の絶縁性を向上させた場合でも、同様に電池のサイクル特性向上が観察された。
【００２６】
【発明の効果】
以上に説明したように、本発明のリチウム二次電池では、正極集電体の表面に過電圧の高い安定な不動態皮膜が形成されるように、水分や含酸素リチウム塩等の酸素供与物質を副電解質に添加している。不動態皮膜が強化されているため，充放電を繰り返してもサイクル特性の低下が少なく、耐久性に優れた二次電池として使用される。
【図面の簡単な説明】
【図１】 本発明に従ったリチウム二次電池の構成図
【図２】 本発明実施例で作製した三極セル
【図３】 副電解質に添加したＬｉＮＯ3の濃度が正極集電体の漏れ電流に及ぼす影響を示したグラフ
【図４】 副電解質に添加したＬｉＮＯ3の濃度が三極セルのサイクル特性に及ぼす影響を示したグラフ
【符号の説明】
１：セパレータ ２：正極 ３：負極 ４：電池ケース ５：負極端子
７：正極端子[0001]
[Industrial application fields]
The present invention relates to a lithium secondary battery that stabilizes a passive film on the surface of a positive electrode current collector and has excellent durability.
[0002]
[Prior art and problems]
Lithium secondary batteries are used as power sources in a wide range of fields, taking advantage of their large electric capacity, excellent reversibility of charge and discharge, and stability during overcharge.
In a normal lithium secondary battery, a positive electrode in which a composite oxide (active substance) with a transition metal containing lithium ions and carbon or the like (conductive aid) are fixed on an aluminum foil (current collector) with an organic binder, A negative electrode is used in which a carbon material powder or the like from which lithium ions can be removed is fixed on a copper foil (current collector) with an organic polymer binder. By winding a positive electrode and a negative electrode with a separator impregnated with an organic electrolyte interposed, a secondary battery having high energy density and high cycle characteristics can be obtained.
[0003]
With the widespread use of lithium secondary batteries, various attempts have been made to extend the life of lithium secondary batteries. The development of active materials with structural stability and the development of chemically stable electrolytes have extended the life of lithium secondary batteries. The interaction between members is not fully examined.
[0004]
[Means for Solving the Problems]
The present invention has been devised to solve such a problem, and by forming a passive film having a strong protective action on the surface of a metal or alloy used for the positive electrode current collector, the battery capacity can be improved. An object of the present invention is to provide a lithium secondary battery in which deterioration is suppressed.
[0005]
In order to achieve the object, the lithium secondary battery of the present invention uses a lithium composite oxide as a positive electrode active material, a lithium salt of an anion containing fluorine as a main electrolyte, and a metal on which a passive film is formed as a positive electrode current collector. The lithium secondary battery is characterized in that an oxygen-containing lithium salt or moisture is added to the sub-electrolyte.
[0006]
As the oxygen-containing lithium salt added to the subelectrolyte, one or more selected from lithium chlorate, lithium iodate, lithium carbonate, lithium silicate, and lithium hydroxide are used. As the positive electrode current collector, a metal or alloy selected from aluminum, tantalum, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony whose surface is covered with a passive film or stainless steel is used.
[0007]
Embodiment
In the lithium secondary battery, for example, as shown in FIG. 1, the positive electrode 2 and the negative electrode 3 are wound around the separator 1, accommodated in the battery can 4, and brought into contact with the electrolyte injected into the separator 1. A negative electrode terminal 5 is incorporated in the bottom of the battery case 4, and the positive electrode 2 is connected to the positive electrode terminal 7 through a spacer 6. The battery case 4 is sealed by attaching a cap 9 using a packing 8.
[0008]
For the positive electrode 2, valve metal or stainless steel selected from aluminum, tantalum, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony is used as a current collector material. Valve metal and stainless steel react with oxygen in the atmosphere to produce a protective passive film on the surface.
A positive electrode current collector is prepared by applying a positive electrode mixture containing a positive electrode active material to a material and drying it.
[0009]
For the positive electrode active material, LiMnO 2, LiMn 2 O 4 , LiNiO 2, LiCoO 2, LiVO 2, LiV 2 O 4, LiCrO 2, LiFeO 2, LiTiO 2, LiScO 2, LiYO lithium composite oxide such as 2 using Is done. Lithium composite oxides include alkali metals such as Na, K, Rb, Cs, and Fr, alkaline earth metals such as Be, Mg, Ca, Sr, Ba, and Ra, Al, Zn, Ga, Fe, Cd, In, A compound or salt of a typical metal such as Sb, Hg, Ti, Pb, Bi, or Po can be included. Among them, Mn in LiMnO 2 is attracting attention as an active material for next-generation lithium secondary batteries because it has a high element ratio in the crust, is low in price and is friendly to the environment.
[0010]
Lithium salts containing fluorine anions such as LiBF 4 , LiPF 6 , LiAsF, LiSbF 6 , LiCF 3 SO 3 , Li (CF 3 SO 2 ) 2 N, Li (CF 3 SO 2 ) 3 C are used for the main electrolyte. Is done. Among them, LiBF 4 are most strongly acts to stabilize the same manner passivation film and LiPF 6, cheaper than LiPF 6, thermodynamic stability better than LiPF 6, to further addition of secondary electrolytes It is more stable than LiPF 6 and is therefore used as a suitable main electrolyte.
[0011]
In this lithium secondary battery, it has been conventionally considered that the battery performance is improved so as not to contain moisture. The present inventors actually investigated and studied the influence of moisture on the battery performance, and found that the addition of a predetermined amount of moisture improved the battery performance, contrary to the conventional theory.
[0012]
Although the reason why moisture improves battery performance is not clear, it is presumed to be caused by the fact that the fluoride-based film becomes oxide-based. That is, the passive film formed on the surface of the positive electrode current collector by the addition of moisture is stabilized, the decomposition overvoltage is increased, and side reactions such as the decomposition of the electrolyte are suppressed. The reversibility of is improved. Incidentally, when charging and discharging are repeated for about 10 cycles, the decrease in battery capacity remains at about 95%. From the experimental results of the present inventors, the battery performance improvement effect is remarkable at a water concentration of 300 to 400 ppm when LiPF 6 is used as an electrolyte, and at a water concentration of 300 to 900 ppm when LiBF 4 is used as an electrolyte. Met.
[0013]
The improvement in battery performance is presumed to be the result of the added moisture acting on the positive electrode current collector as an oxygen donor and the passive film on the positive electrode current collector surface being densely stabilized. Therefore, instead of adding water, one or more oxygen-containing lithium salts selected from lithium nitrate, lithium chlorate, lithium iodate, lithium carbonate, lithium silicate, and lithium hydroxide are added to the main electrolyte. In this case, the battery performance was improved as well.
[0014]
The passive film formed on the surface of the positive electrode current collector is a dense and strong film even when a main electrolyte is a lithium salt of an anion containing fluorine. That is, since it is exposed to a high electric field in an organic electrolyte containing fluorine, a strong and dense passive film having a strong protective action is generated. This passive film has a close relationship with the corrosion of the positive electrode current collector and the decomposition of the electrolyte, which are causes of deterioration of the battery performance, and the cycle characteristics of the battery are improved by enhancing the environmental barrier function.
[0015]
[ Reference Example 1] LiMn 2 O 4 was used as a positive electrode active material, 30 mg of the positive electrode active material was sufficiently mixed with acetylene black (conducting aid), and then polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP) were added. One drop was added and kneaded on an agate mortar to prepare a rubber-like positive electrode mixture. The positive electrode current collector was produced by punching an aluminum foil having a purity of 99.99% to a diameter of 8 mm and spot welding an aluminum wire having a purity of 99.999% and a diameter of 0.5 mm. A positive electrode mixture is applied to the positive electrode current collector, hand pressed with a jig at 1 ton / cm 2 × 1 minute, and then subjected to a drying process at 180 ° C. for 4 hours in a vacuum atmosphere to produce a sample electrode. did.
[0016]
The sample electrode 11 was accommodated in the tall beaker 14 together with the counter electrode 12 and the reference electrode 13 to assemble a triode cell (FIG. 2). Lithium foil was used for the counter electrode 12 and the reference electrode 13. 1M lithium hexafluorophosphate (LiPF 6 ) or 1M lithium tetrafluoroborate (LiBF 4 ) was added to a mixed solvent of propylene carbonate (PC): 1,2-dimethoxyethane (DME) = 1: 1 (volume ratio). The added electrolyte 15 was injected into the tall beaker 14 and sealed with Ar gas. Each of the electrodes 11 to 13 was drawn to the outside with a SUS304 stainless steel wire 16, attached with an insulating cap 17, and hermetically sealed with an insulating sheet 18.
[0017]
A triode cell was placed in an incubator maintained at 25 ± 0.5 ° C., and a constant current (0.4 mA / cm 2 = 0.09 C rate) in a potential range of +3.5 to 4.4 V vs. Li / Li +. ). When the test results were arranged according to the moisture concentration of the electrolyte 15, the results shown in Table 1 were obtained.
[0018]
The water concentration of the electrolyte 15 was measured using a Karl Fischer moisture meter. In an electrolyte that did not intentionally electrify water (electrolyte without addition of moisture), moisture resulting from the electrolyte raw material was contained at a concentration of 85.3 ppm. On the other hand, the moisture concentration of the electrolyte added with moisture during the raw material kneading (moisture-added electrolyte) was 414.7 ppm.
[0019]
As can be seen from the test results in Table 1, the electrolyte added with water could be charged up to 125.7 mA · h / g with respect to the theoretical capacity of 148 mA · h / g in the first cycle. Further, the capacity deterioration rate of the eighth cycle with respect to the first cycle was 6.2%. On the other hand, the electrolyte with no moisture added could charge up to 118.2 mA · h / g in the first cycle, but the capacity deterioration rate in the eighth cycle relative to the first cycle was greatly reduced to 32.8%. It was.
[0020]
As is apparent from this comparison, when water was added to the LiBF 4 / PC + DME or LiPF 6 / PC + DME electrolyte, the charge capacity at the first cycle was slightly inferior, but a significant improvement in cycle characteristics was confirmed.
When the sample electrode 11 was taken out from the triode cell in which charge and discharge were repeated and the surface of the sample electrode 11 was analyzed by XPS, the oxygen concentration of the passive film was high. The increase in the oxygen concentration means that a stable film with a large overvoltage is formed on the surface of the aluminum foil, and it is indicated that the decrease in the capacity deterioration rate was suppressed by stabilizing the passive film.
[0021]
Figure 0004034940
[0022]
[Example 1 ] An aluminum foil having a purity of 99.99% and a thickness of 0.1 mm was alkali degreased, and LiMn 2 O 4 (active substance) and acetylene black (conductive aid) were applied to prepare a sample electrode 11. An electrolyte 15 was prepared by adding LiNO 3 (oxygen-donating substance) at 0 ppm, 300 ppm, and 600 ppm to 1M LiBF 4 / PC + DME (50:50) and 1M LiPF 6 / PC + DME (50:50). The sample electrode 11 is accommodated in a tall beaker 14 together with a Pt electrode (counter electrode 2) and an Ag reference electrode 3 (+3.0 V vs. Li / Li + ), and a triode cell is placed in an Ar-substituted glove box in the same manner as in Example 1. Assembled.
[0023]
The produced triode cell was subjected to a charge / discharge test to evaluate the battery performance. When the sample electrode 11 was held at a constant potential of 5 V vs. Ag in the electrolyte 15, the leakage current of the passive film changed with time as shown in FIG. That is, compared with the case where LiNO 3 was not added, the leakage current of the positive electrode current collector was significantly reduced to about 30% when LiNO 3 was added and about 60% when 600 ppm was added.
[0024]
When the sample electrode 11 was taken out from the triode cell added with 600 ppm of LiNO 3 with little leakage current and the surface of the sample electrode 11 was analyzed by XPS, the oxygen concentration of the passive film was increased. An increase in oxygen concentration means that LiNO 3 acts as an oxygen donor and strengthens the passive film, and the result appears in the phenomenon of leakage current.
When the discharge capacity was measured for each charge / discharge cycle, the discharge capacity increased as the LiNO 3 concentration in the electrolyte increased as shown in FIG. 4, and the capacity decrease for each cycle was suppressed.
[0025]
Even when another oxygen-containing lithium salt was used instead of LiNO 3 , the passive film on the surface of the positive electrode current collector was similarly strengthened, and the deterioration of the cycle characteristics was suppressed. Even when the insulating properties of the passive film are improved by other factors such as material composition, aluminum foil surface treatment (heat treatment), positive electrode mixture water, electrolyte water and LiNO 3 concentration, the cycle of the battery is the same. Improved properties were observed.
[0026]
【The invention's effect】
As described above, in the lithium secondary battery of the present invention, an oxygen-donating substance such as water or an oxygen-containing lithium salt is used so that a stable passive film having a high overvoltage is formed on the surface of the positive electrode current collector. It is added to the secondary electrolyte. Since the passive film is reinforced, it can be used as a secondary battery having excellent durability with little deterioration in cycle characteristics even after repeated charge and discharge.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a lithium secondary battery according to the present invention. FIG. 2 is a triode cell fabricated in an embodiment of the present invention. FIG. 3 is a concentration of LiNO 3 added to a subelectrolyte. Graph showing the effect on the current [Fig. 4] Graph showing the effect of the LiNO 3 concentration added to the sub-electrolyte on the cycle characteristics of the triode cell [Explanation of symbols]
1: Separator 2: Positive electrode 3: Negative electrode 4: Battery case 5: Negative electrode terminal 7: Positive electrode terminal

Claims (4)

リチウム複合酸化物を正極活性物質、フッ素を含むアニオンのリチウム塩を主電解質、不動態皮膜が形成される金属を正極集電体とするリチウム二次電池において、副電解質に酸素供与物質として硝酸リチウムが添加されていることを特徴とする非水電解液を用いたリチウム二次電池。In a lithium secondary battery using a lithium composite oxide as a positive electrode active substance, a lithium salt of an anion containing fluorine as a main electrolyte, and a metal on which a passive film is formed as a positive electrode current collector, lithium nitrate as an oxygen donor substance as a sub-electrolyte A lithium secondary battery using a non-aqueous electrolyte, characterized in that is added. 正極集電体がアルミニウム，タンタル，チタン，ハフニウム，ジルコニウム，亜鉛，タングステン，ビスマス，アンチモンから選ばれた金属又は合金、或いはステンレス鋼である請求項１記載のリチウム二次電池。2. The lithium secondary battery according to claim 1, wherein the positive electrode current collector is a metal or alloy selected from aluminum, tantalum, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony, or stainless steel. 正極集電体がアルミニウムである請求項１記載のリチウム二次電池。The lithium secondary battery according to claim 1, wherein the positive electrode current collector is aluminum. フッ素を含むアニオンのリチウム塩がＬｉＢＦ4，ＬｉＰＦ6，ＬｉＡｓＦ，ＬｉＳｂＦ6，ＬｉＣＦ3ＳＯ3，Ｌｉ(ＣＦ3ＳＯ2)2Ｎ，Ｌｉ(ＣＦ3ＳＯ2)3Ｃから選ばれた１種又は２種以上である請求項１記載のリチウム二次電池。The lithium salt of an anion containing fluorine is selected from LiBF 4 , LiPF 6 , LiAsF, LiSbF 6 , LiCF 3 SO 3 , Li (CF 3 SO 2 ) 2 N, Li (CF 3 SO 2 ) 3 C or The lithium secondary battery according to claim 1, wherein there are two or more kinds.
JP2001051689A 2001-02-27 2001-02-27 Lithium secondary battery using non-aqueous electrolyte Expired - Fee Related JP4034940B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2001051689A JP4034940B2 (en) 2001-02-27 2001-02-27 Lithium secondary battery using non-aqueous electrolyte

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2001051689A JP4034940B2 (en) 2001-02-27 2001-02-27 Lithium secondary battery using non-aqueous electrolyte

Publications (2)

Publication Number Publication Date
JP2002260728A JP2002260728A (en) 2002-09-13
JP4034940B2 true JP4034940B2 (en) 2008-01-16

Family

ID=18912430

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2001051689A Expired - Fee Related JP4034940B2 (en) 2001-02-27 2001-02-27 Lithium secondary battery using non-aqueous electrolyte

Country Status (1)

Country Link
JP (1) JP4034940B2 (en)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4728598B2 (en) * 2003-06-16 2011-07-20 株式会社豊田中央研究所 Lithium ion secondary battery
KR101094115B1 (en) * 2003-12-15 2011-12-15 미쓰비시 쥬시 가부시끼가이샤 Nonaqueous electrolyte secondary battery
JP5099964B2 (en) * 2003-12-25 2012-12-19 セイコーインスツル株式会社 Electrochemical cell and method for producing the same
JP4529683B2 (en) * 2004-12-28 2010-08-25 Ｔｄｋ株式会社 Electrochemical devices
JP4753655B2 (en) * 2005-08-03 2011-08-24 三洋電機株式会社 Lithium secondary battery
CN102498590A (en) 2009-08-19 2012-06-13 三菱化学株式会社 Separator for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery
KR20140073301A (en) * 2012-12-06 2014-06-16 삼성정밀화학 주식회사 Electrolyte for lithium secondary baterries
JP6848330B2 (en) * 2016-10-21 2021-03-24 株式会社Ｇｓユアサ Non-aqueous electrolyte power storage element
CN109216705A (en) * 2018-09-17 2019-01-15 苏州清陶新能源科技有限公司 A kind of solid state battery conductive composite coating aluminium foil and its preparation process

Also Published As

Publication number Publication date
JP2002260728A (en) 2002-09-13

Similar Documents

Publication Publication Date Title
JP4022889B2 (en) Electrolyte and battery
JP4231411B2 (en) Electrode active material for lithium secondary battery, method for producing the same, and lithium secondary battery including the same
JP4625744B2 (en) Nonaqueous electrolyte battery and battery pack
US20060099495A1 (en) Cathode and battery
JP4938919B2 (en) Secondary battery
JP2002203553A (en) Positive-electrode active material and non-aqueous electrolyte secondary battery
CN101355146A (en) Negative electrode, battery, and method for producing them
JP2000011996A (en) Nonaqueous electrolyte secondary battery
JP2002025611A (en) Nonaqueous electrolyte secondary battery
JP3287376B2 (en) Lithium secondary battery and method of manufacturing the same
JP4034940B2 (en) Lithium secondary battery using non-aqueous electrolyte
JP2005166290A (en) Electrolyte and battery using it
WO2013035527A1 (en) Nonaqueous electrolyte secondary battery
JP2002170566A (en) Lithium secondary cell
JPH03108261A (en) Nonaqueous solvent secondary battery
JPH1154120A (en) Lithium ion secondary battery
JP2007335175A (en) Method of manufacturing coating composition for electrode mixture layer of nonaqueous electrolyte battery, electrode for nonaqueous electrolyte battery, and nonaqueous electrolyte battery
JP2006024407A (en) Organic electrolyte battery
JP2007115507A (en) Anode activator and aqueous lithium secondary cell
JP2005071617A (en) Nonaqueous electrolyte secondary battery and its manufacturing method
JP2006216450A (en) Battery
JP3447187B2 (en) Non-aqueous electrolyte battery and method for manufacturing the same
JPH0462764A (en) Nonaqueous electrolyte cell
WO2021039178A1 (en) Non-aqueous electrolyte secondary battery
JP2003168478A (en) Lithium ion non-aqueous electrolyte secondary battery

Legal Events

Date Code Title Description
A711 Notification of change in applicant

Free format text: JAPANESE INTERMEDIATE CODE: A712

Effective date: 20031031

RD03 Notification of appointment of power of attorney

Free format text: JAPANESE INTERMEDIATE CODE: A7423

Effective date: 20040129

A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20040507

RD02 Notification of acceptance of power of attorney

Free format text: JAPANESE INTERMEDIATE CODE: A7422

Effective date: 20040507

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20061219

RD02 Notification of acceptance of power of attorney

Free format text: JAPANESE INTERMEDIATE CODE: A7422

Effective date: 20070307

RD04 Notification of resignation of power of attorney

Free format text: JAPANESE INTERMEDIATE CODE: A7424

Effective date: 20070309

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20070626

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20070824

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20071023

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20071026

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20101102

Year of fee payment: 3

R150 Certificate of patent or registration of utility model

Free format text: JAPANESE INTERMEDIATE CODE: R150

LAPS Cancellation because of no payment of annual fees