JP3913438B2 - Lithium secondary battery - Google Patents
Lithium secondary battery Download PDFInfo
- Publication number
- JP3913438B2 JP3913438B2 JP2000100406A JP2000100406A JP3913438B2 JP 3913438 B2 JP3913438 B2 JP 3913438B2 JP 2000100406 A JP2000100406 A JP 2000100406A JP 2000100406 A JP2000100406 A JP 2000100406A JP 3913438 B2 JP3913438 B2 JP 3913438B2
- Authority
- JP
- Japan
- Prior art keywords
- active material
- material layer
- negative electrode
- thin film
- 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】
【発明の属する技術分野】
本発明は、リチウム二次電池に関するものである。
【０００２】
【従来の技術】
リチウム金属を負極として用いたリチウム二次電池は、そのエネルギー密度が大きいことから、次世代の二次電池として注目されている。しかしながら、リチウム金属を負極に用いるため、充放電に伴ってリチウム金属の溶解析出が生じ、デンドライトの生成や電極の変形が生じる。このため、サイクル性能が劣悪であり、実用化に耐え得るものはできていない。このような問題を解決し得るものとして、Ｌｉと合金化する金属を用いたＬｉ合金負極や、黒鉛などの炭素材料を用いた炭素負極が提案されており、炭素負極を用いたものは一部実用化されている。
【０００３】
しかしながら、炭素負極はその理論容量が３７２ｍＡｈ／ｇと低いため、金属リチウムを負極に用いた場合に比べて、大幅にエネルギー密度が低下するという欠点がある。また、Ｌｉ合金負極を用いた場合には、充放電に伴い体積の膨張と収縮が繰り返されるため、充放電サイクルが進むにつれて活物質粒子が微粉化し、サイクル性能が悪くなるという欠点があった。
【０００４】
一方、リチウム二次電池を用いる応用機器においては、より一層のエネルギー密度の向上が要求されており、黒鉛負極を用いたリチウム二次電池と同等以上のサイクル性能と、より一層の高エネルギー密度を有するリチウム二次電池が要望されている。
【０００５】
そこで、黒鉛に比べて非常に大きな容量を有するケイ素粉末を、黒鉛粉末と混合した負極が提案されている。これは、ケイ素粉末の有する大きな容量と、黒鉛の優れたサイクル性能を兼ね備えることを目的とするものである。
【０００６】
【発明が解決しようとする課題】
しかしながら、ケイ素粉末は、上述のようにリチウムとの合金化によりリチウムを吸蔵及び放出する活物質であるので、黒鉛粉末と混合して用いた場合にも、充放電サイクルに伴い微粉化が進行し、集電体から活物質が剥離するため、電極全体のサイクル性能は劣ったものとなり、実用性を有するものではなかった。
【０００７】
本発明の目的は、充放電時の膨張収縮による集電体からの活物質の剥離を防止することができ、優れたサイクル特性を得ることができるリチウム二次電池を提供することにある。
【０００８】
【課題を解決するための手段】
本発明の二次電池は、Ｌｉと合金化しない材料からなる集電体の上に、炭素からなる第１の活物質層を設け、該第１の活物質層の上に、ラマン分光分析において、結晶領域に対応する５２０ｃｍ -1 近傍のピークと、非晶質領域に対応する４８０ｃｍ -1 近傍のピークの両方が実質的に検出される微結晶Ｓｉ薄膜、または結晶領域に対応する５２０ｃｍ -1 近傍のピークは実質的に検出されず、非晶質領域に対応する４８０ｃｍ -1 のピークが実質的に検出される非晶質Ｓｉ薄膜からなる第２の活物質層を設けた電極を用いることを特徴としている。
【０００９】
本発明の上記電極においては、上記第２活物質層の上に、さらに第１の活物質層が設けられていてもよい。すなわち、集電体の上に、第１の活物質層／第２の活物質層／第１の活物質層の３層構造の活物質層が設けられていてもよい。さらに、本発明の上記電極においては、上記第２活物質層の上に、第１の活物質層及び第２の活物質層がこの順序で交互に繰り返し積層されていてもよい。すなわち、集電体の上に、第１の活物質層／第２の活物質層／第１の活物質層／第２の活物質層のように第１の活物質層と第２の活物質層からなる繰り返しの積層構造が形成されていてもよい。
【００１０】
本発明の第２の活物質層に用いる活物質は、微結晶Ｓｉ薄膜または非晶質Ｓｉ薄膜である。Ｓｉは、高い容量を有しており、Ｌｉ4.4Ｓｉの組成までＬｉを吸蔵することが可能である。
【００１１】
また、第２の活物質層は、気相から堆積させた薄膜であることが好ましい。これらの薄膜は、ＣＶＤ法、スパッタリング法、及び蒸着法などの気相からの薄膜形成法により形成することができる。
【００１２】
微結晶Ｓｉ薄膜は、ラマン分光分析において、結晶領域に対応する５２０ｃｍ-1近傍のピークと、非晶質領域に対応する４８０ｃｍ-1近傍のピークの両方が実質的に検出されるＳｉ薄膜である。また、非晶質Ｓｉ薄膜は、ラマン分光分析において、結晶領域に対応する５２０ｃｍ-1近傍のピークは実質的に検出されず、非晶質領域に対応する４８０ｃｍ-1のピークが実質的に検出されるＳｉ薄膜である。
【００１３】
本発明において第１の活物質層に用いる炭素材料は、リチウム二次電池において負極として用いることができる炭素材料であれば特に限定されるものではなく、例えば、天然黒鉛、人造黒鉛、カーボンブラック、活性炭、カーボンファイバー、コークス、有機前駆体を不活性雰囲気中で熱処理して合成した炭素、あるいはダイヤモンドライクカーボン（ＤＬＣ）などが挙げられる。黒鉛としては、層間距離ｄが３．３７Å以下、積層方向の結晶子寸法Ｌｃが３００Å以上の黒鉛が好ましく用いられる。
【００１４】
本発明における集電体は、Ｌｉと合金化しない材料であって、高い導電性を有するものであれば特に限定されないが、銅箔等の金属箔が好ましく用いられる。
本発明によれば、炭素からなる第１の活物質層の上に、Ｌｉと合金化する金属または半導体からなる第２の活物質層が設けられる。第２の活物質層は、Ｌｉを吸蔵・放出することにより膨張収縮するが、その下地層である第１の活物質層も、同様にＬｉの吸蔵・放出により膨張収縮するので、第２の活物質層の剥離を防止することができ、サイクル性能を高めることができる。
【００１５】
本発明において、さらに好ましくは、第２の活物質層の充放電時における膨張収縮率と、第１の活物質層の充放電時おける膨張収縮率とがほぼ同じになるように調整される。例えば、第１の活物質層及び第２の活物質層のそれぞれの厚みを調整することにより、このような調整が可能である。
【００１６】
本発明において、上記電極は、負極として用いてもよいし、正極として用いてもよいが、一般には負極として用いられる。
この場合の正極としては、特に制限されるものではないが、従来からリチウム二次電池の正極として用いられているものを用いることができる。このような正極活物質としては、ＬｉＣｏＯ2 、ＬｉＮｉＯ2 、ＬｉＭｎ2Ｏ4 、ＬｉＭｎＯ2 、ＬｉＣｏ0.5Ｎｉ0.5Ｏ2 、ＬｉＮｉ0.7Ｃｏ0.2Ｍｎ0.1Ｏ2 などのリチウム含有遷移金属酸化物や、ＭｎＯ2 などのリチウムを含有していない金属酸化物が例示される。また、この他にも、リチウムを電気化学的に挿入・脱離する物質であれば、制限なく用いることができる。
【００１７】
本発明の二次電池に用いる電解質の溶媒は、特に限定されるものではないが、エチレンカーボネート、プロピレンカーボネート、ブチレンカーボネートなどの環状カーボネートと、ジメチルカーボネート、メチルエチルカーボネート、ジエチルカーボネートなどの鎖状カーボネートとの混合溶媒が例示される。また、前記環状カーボネートと１，２−ジメトキシエタン、１，２−ジエトキシエタンなどのエーテル系溶媒との混合溶媒も例示される。また、電解質の溶質としては、ＬｉＰＦ6 、ＬｉＢＦ4 、ＬｉＣＦ3ＳＯ3 、ＬｉＮ（ＣＦ3ＳＯ2)2 、ＬｉＮ（Ｃ2Ｆ5ＳＯ2)2 、ＬｉＮ（ＣＦ3ＳＯ2)(Ｃ4Ｆ9ＳＯ2)、ＬｉＣ（ＣＦ3ＳＯ2)3 、ＬｉＣ（Ｃ2Ｆ5ＳＯ2)3 など及びそれらの混合物が例示される。さらに電解質として、ポリエチレンオキシド、ポリアクリロニトリルなどのポリマー電解質に電解液を含浸したゲル状ポリマー電解質や、ＬｉＩ、Ｌｉ3Ｎなどの無機固体電解質が例示される。本発明の二次電池の電解質は、イオン導電性を発現させる溶媒としてのＬｉ化合物とこれを溶解・保持する溶媒が電池の充電時や放電時あるいは保存時の電圧で分解しない限り、制約なく用いることができる。
【００１８】
【発明の実施の形態】
以下、本発明を実施例に基づいてさらに詳細に説明するが、本発明は以下の実施例に何ら限定されるものではなく、その要旨を変更しない範囲において適宜変更して実施することが可能なものである。
【００１９】
（本発明電池Ａの作製）
〔負極第１活物質層の作製〕
負極の第１の活物質層の活物質として黒鉛（ｄ＜３．３７Å、Ｌｃ＞３００Å）を用い、結着剤としてフッ素樹脂（ＰＶｄＦ）を用いて第１の活物質層を作製した。フッ素樹脂の濃度が黒鉛＋フッ素樹脂の全体の５重量％となるように、フッ素樹脂を溶解したＮ−メチルピロリドン溶液に黒鉛を添加し、３０分間らいかい機でらいかいしてスラリーを作製した。このスラリーをドクターブレード法により、電解銅箔の上に塗布、乾燥して第１の活物質層とした。第１の活物質層の厚みは６０μｍであった。
【００２０】
〔負極第２活物質層の作製〕
原料ガスとしてＳｉＨ4ガスを用い、キャリアガスとしてＨ2ガスを用い、プラズマＣＶＤ法により、上記第１の活物質層の上に、第２の活物質層としてシリコン薄膜を形成し、負極を作製した。薄膜形成条件は、原料ガス流量：１０ｓｃｃｍ、キャリアガス流量：２００ｓｃｃｍ、基板温度：１８０℃、反応圧力：４０Ｐａ、高周波電力５５５Ｗとした。形成されたシリコン薄膜の膜厚は２μｍであり、ラマン分光分析により微結晶シリコン薄膜であることを確認した。
【００２１】
第１の活物質層中の黒鉛と第２の活物質層であるシリコン薄膜との重量比は、８４：４．６であった。
なお、上記の実施例では、ＣＶＤ法によりシリコン薄膜を形成しているが、スパッタリング法及び蒸着法などの他の薄膜形成法で形成してもよい。
【００２２】
〔正極の作製〕
正極活物質としてＬｉＣｏＯ2 を用い、結着剤としてフッ素樹脂（ＰＶｄＦ）を用いて正極を作製した。具体的には、ＬｉＣｏＯ2粉末１００ｇを、フッ素樹脂が５重量％となるように溶解したＮ−メチルピロリドン溶液に混合し、３０分間らいかい機でらいかいしてスラリーを作製した。このスラリーをドクターブレード法によって、厚み２０μｍのアルミニウム箔上に塗布し、乾燥して正極を得た。
【００２３】
〔電池の作製〕
上記負極と上記正極を、ポリプロピレン製セパレータを介して積層した後、巻き取ることによって、電極群を作製した。この電極群を電池缶に挿入した後、電解液を注入し、封口して電池を作製した。なお、電解液としては、エチレンカーボネートとジエチルカーボネートとの等体積混合溶媒に、ＬｉＰＦ6 を１モル／リットル溶解したものを用いた。
【００２４】
（本発明電池Ｂの作製）
〔下層の負極第１活物質層の作製〕
第１の活物質層の厚みを３０μｍとする以外は、上記本発明電池Ａにおける負極第１活物質層と同様にして、下層の負極第１活物質層を作製した。
【００２５】
〔負極第２活物質層の作製〕
上記本発明電池Ａにおける負極第２活物質層と同様にして、上記の下層の負極第１活物質層の上にシリコン薄膜を形成した。シリコン薄膜の膜厚は２μｍとした。
【００２６】
〔上層の負極第１活物質層の作製〕
上記シリコン薄膜の上に、下層の負極第１活物質層と同様にして、上層の負極第１活物質層を作製した。
【００２７】
以上のようにして、集電体である電解銅箔の上に、第１の活物質層／第２の活物質層／第１の活物質層の３層を積層し、負極を得た。
上層及び下層の第１の活物質層中の合計の黒鉛と、第２の活物質層であるシリコン薄膜との重量比は、８４：４．６であった。
【００２８】
〔正極の作製〕
上記本発明電池Ａと同様にして正極を作製した。
〔電池の作製〕
上記負極及び上記正極を用い、上記本発明電池Ａと同様にして電池を作製した。
【００２９】
（比較電池の作製）
黒鉛粉末とケイ素粉末を重量比８４：４．６となるように混合し、結着剤として上記と同様のフッ素樹脂を用いてスラリー化した後、電解銅箔上に塗布して負極を作製した。この負極を用いる以外は上記本発明電池と同様にして、比較電池を作製した。
【００３０】
（充放電サイクル試験）
本発明電池Ａ及びＢ並びに比較電池について、充放電サイクル試験を行った。充電は電池電圧４．２Ｖまでとし、放電は電池電圧２．７５Ｖまでとし、充放電電流は１００ｍＡとして、充放電を行い、１サイクル目、２サイクル目、５サイクル目、及び１０サイクル目の放電容量及び充放電効率を測定した。測定結果を表１に示す。
【００３１】
【表１】
表１に示すように、本発明電池Ａ及びＢは、比較電池に比べ、高い放電容量及び充放電効率を示している。
１０サイクル後に各電池を分解したところ、本発明電池Ａ及びＢの負極活物質は、集電体である銅箔から剥離している部分が認められず、負極活物質自体はその形状を保っていた。一方、比較電池においては、ほとんどの負極活物質が集電体から剥離、ケイ素粉末と思われる銀白色の微粉が電解液中に分散していることが確認された。
【００３３】
【発明の効果】
本発明によれば、充放電時の膨張収縮による集電体からの活物質の剥離を防止することができ、良好なサイクル特性を得ることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to lithium secondary batteries.
[0002]
[Prior art]
A lithium secondary battery using lithium metal as a negative electrode has attracted attention as a next-generation secondary battery because of its high energy density. However, since lithium metal is used for the negative electrode, lithium metal dissolves and precipitates with charge and discharge, and dendrites are generated and the electrode is deformed. For this reason, cycle performance is inferior, and what can endure practical use has not been made. As a solution to such a problem, a Li alloy negative electrode using a metal alloying with Li and a carbon negative electrode using a carbon material such as graphite have been proposed. It has been put into practical use.
[0003]
However, since the theoretical capacity of the carbon negative electrode is as low as 372 mAh / g, there is a drawback that the energy density is greatly reduced as compared with the case where metallic lithium is used for the negative electrode. Further, when a Li alloy negative electrode is used, volume expansion and contraction are repeated with charge / discharge, so that the active material particles are pulverized as the charge / discharge cycle progresses, resulting in poor cycle performance.
[0004]
On the other hand, in application equipment using a lithium secondary battery, further improvement in energy density is required, and cycle performance equal to or higher than that of a lithium secondary battery using a graphite negative electrode and higher energy density are required. There is a need for a lithium secondary battery.
[0005]
Therefore, a negative electrode in which silicon powder having a very large capacity compared with graphite is mixed with graphite powder has been proposed. The purpose of this is to combine the large capacity of silicon powder with the excellent cycle performance of graphite.
[0006]
[Problems to be solved by the invention]
However, since silicon powder is an active material that absorbs and releases lithium by alloying with lithium as described above, even when mixed with graphite powder, pulverization proceeds with charge / discharge cycles. Since the active material was peeled from the current collector, the cycle performance of the entire electrode was inferior and was not practical.
[0007]
An object of the present invention is to provide a lithium secondary battery that can prevent the active material from peeling from the current collector due to expansion and contraction during charge and discharge, and can obtain excellent cycle characteristics.
[0008]
[Means for Solving the Problems]
In the secondary battery of the present invention, a first active material layer made of carbon is provided on a current collector made of a material that is not alloyed with Li, and a Raman spectroscopic analysis is performed on the first active material layer . A microcrystalline Si thin film in which both a peak near 520 cm −1 corresponding to the crystalline region and a peak near 480 cm −1 corresponding to the amorphous region are substantially detected, or 520 cm −1 corresponding to the crystalline region Use an electrode provided with a second active material layer made of an amorphous Si thin film in which a peak in the vicinity is not substantially detected and a peak at 480 cm −1 corresponding to an amorphous region is substantially detected. It is characterized by.
[0009]
In the electrode of the present invention, a first active material layer may be further provided on the second active material layer. That is, an active material layer having a three-layer structure of first active material layer / second active material layer / first active material layer may be provided on the current collector. Furthermore, in the electrode of the present invention, the first active material layer and the second active material layer may be alternately and repeatedly laminated in this order on the second active material layer. That is, on the current collector, the first active material layer and the second active material layer are formed as follows: first active material layer / second active material layer / first active material layer / second active material layer. A repetitive laminated structure composed of material layers may be formed.
[0010]
The active material used for the second active material layer of the present invention is a microcrystalline Si thin film or an amorphous Si thin film. S i has a have high capacity, Ru can der to occlude Li to composition of Li 4.4 S i.
[0011]
The second active material layer is preferably a thin film deposited from the gas phase. These thin films can be formed by a thin film forming method from a gas phase such as a CVD method, a sputtering method, and a vapor deposition method.
[0012]
The microcrystalline Si thin film is a Si thin film in which both a peak near 520 cm −1 corresponding to a crystalline region and a peak near 480 cm −1 corresponding to an amorphous region are substantially detected in Raman spectroscopic analysis. . In addition, in the amorphous Si thin film, the peak near 520 cm −1 corresponding to the crystalline region is not substantially detected in Raman spectroscopic analysis, and the peak at 480 cm −1 corresponding to the amorphous region is substantially detected. Si thin film .
[0013]
The carbon material used for the first active material layer in the present invention is not particularly limited as long as it is a carbon material that can be used as a negative electrode in a lithium secondary battery. For example, natural graphite, artificial graphite, carbon black, Examples thereof include activated carbon, carbon fiber, coke, carbon synthesized by heat treatment of an organic precursor in an inert atmosphere, diamond-like carbon (DLC), and the like. As the graphite, graphite having an interlayer distance d of 3.37 mm or less and a crystallite size Lc in the stacking direction of 300 mm or more is preferably used.
[0014]
The current collector in the present invention is not particularly limited as long as it is a material that is not alloyed with Li and has high conductivity, but a metal foil such as a copper foil is preferably used.
According to the present invention, the second active material layer made of a metal or semiconductor alloyed with Li is provided on the first active material layer made of carbon. The second active material layer expands and contracts by occluding / releasing Li, but the first active material layer, which is the underlying layer, similarly expands and contracts by occluding / releasing Li. Peeling of the active material layer can be prevented and cycle performance can be improved.
[0015]
In the present invention, more preferably, the expansion / contraction rate during charging / discharging of the second active material layer and the expansion / contraction rate during charging / discharging of the first active material layer are adjusted to be substantially the same. For example, such adjustment is possible by adjusting the thicknesses of the first active material layer and the second active material layer.
[0016]
In the present invention, the electrode may be used as a negative electrode or a positive electrode, but is generally used as a negative electrode.
Although it does not restrict | limit especially as a positive electrode in this case, The thing conventionally used as a positive electrode of a lithium secondary battery can be used. Examples of such positive electrode active materials include lithium-containing transition metal oxides such as LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , LiMnO 2 , LiCo 0.5 Ni 0.5 O 2 , LiNi 0.7 Co 0.2 Mn 0.1 O 2 , and MnO 2. Examples thereof include metal oxides not containing lithium. In addition, any substance that electrochemically inserts and desorbs lithium can be used without limitation.
[0017]
The electrolyte solvent used in the secondary battery of the present invention is not particularly limited, but cyclic carbonates such as ethylene carbonate, propylene carbonate, and butylene carbonate, and chain carbonates such as dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate. And a mixed solvent. Further, mixed solvents of the cyclic carbonate and ether solvents such as 1,2-dimethoxyethane and 1,2-diethoxyethane are also exemplified. As electrolyte solutes, LiPF 6 , LiBF 4 , LiCF 3 SO 3 , LiN (CF 3 SO 2 ) 2 , LiN (C 2 F 5 SO 2 ) 2 , LiN (CF 3 SO 2 ) (C 4 F 9 SO 2 ), LiC (CF 3 SO 2 ) 3 , LiC (C 2 F 5 SO 2 ) 3 and the like and mixtures thereof. Further, examples of the electrolyte include gel polymer electrolytes in which a polymer electrolyte such as polyethylene oxide and polyacrylonitrile is impregnated with an electrolytic solution, and inorganic solid electrolytes such as LiI and Li 3 N. The electrolyte of the secondary battery of the present invention can be used without restriction unless the Li compound as a solvent that develops ionic conductivity and the solvent that dissolves and retains it are decomposed by the voltage at the time of charging, discharging, or storage of the battery. be able to.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail based on examples. However, the present invention is not limited to the following examples, and can be implemented with appropriate modifications within a range not changing the gist thereof. Is.
[0019]
(Production of Invention Battery A)
[Preparation of negative electrode first active material layer]
A first active material layer was manufactured using graphite (d <3.37Å, Lc> 300Å) as an active material of the first active material layer of the negative electrode and using a fluororesin (PVdF) as a binder. Graphite was added to the N-methylpyrrolidone solution in which the fluororesin was dissolved so that the concentration of the fluororesin would be 5% by weight of the total of the graphite + fluororesin, and the slurry was prepared with a milling machine for 30 minutes. . This slurry was applied onto an electrolytic copper foil by a doctor blade method and dried to form a first active material layer. The thickness of the first active material layer was 60 μm.
[0020]
[Preparation of negative electrode second active material layer]
A SiH 4 gas is used as a source gas, an H 2 gas is used as a carrier gas, a silicon thin film is formed as a second active material layer on the first active material layer by plasma CVD, and a negative electrode is produced. did. The thin film formation conditions were as follows: source gas flow rate: 10 sccm, carrier gas flow rate: 200 sccm, substrate temperature: 180 ° C., reaction pressure: 40 Pa, and high-frequency power 555 W. The formed silicon thin film had a thickness of 2 μm and was confirmed to be a microcrystalline silicon thin film by Raman spectroscopic analysis.
[0021]
The weight ratio of graphite in the first active material layer to the silicon thin film as the second active material layer was 84: 4.6.
In the above embodiment, the silicon thin film is formed by the CVD method, but may be formed by other thin film forming methods such as a sputtering method and a vapor deposition method .
[0022]
[Production of positive electrode]
A positive electrode was produced using LiCoO 2 as a positive electrode active material and a fluororesin (PVdF) as a binder. Specifically, 100 g of LiCoO 2 powder was mixed with an N-methylpyrrolidone solution in which the fluororesin was dissolved at 5% by weight, and the mixture was broken with a cracking machine for 30 minutes to prepare a slurry. This slurry was applied onto an aluminum foil having a thickness of 20 μm by a doctor blade method and dried to obtain a positive electrode.
[0023]
[Production of battery]
After laminating | stacking the said negative electrode and the said positive electrode through the separators made from a polypropylene, the electrode group was produced by winding up. After this electrode group was inserted into the battery can, an electrolytic solution was injected and sealed to prepare a battery. As the electrolytic solution, an equal volume mixed solvent of ethylene carbonate and diethyl carbonate was used as the LiPF 6 was dissolved 1 mol / liter.
[0024]
(Preparation of the battery B of the present invention)
[Preparation of Lower Layer First Negative Active Material Layer]
A lower negative electrode first active material layer was produced in the same manner as the negative electrode first active material layer in the battery A of the present invention except that the thickness of the first active material layer was 30 μm.
[0025]
[Preparation of negative electrode second active material layer]
In the same manner as the negative electrode second active material layer in the present invention battery A, a silicon thin film was formed on the lower negative electrode first active material layer. The film thickness of the silicon thin film was 2 μm.
[0026]
[Preparation of Upper Negative Electrode First Active Material Layer]
An upper negative electrode first active material layer was formed on the silicon thin film in the same manner as the lower negative electrode first active material layer.
[0027]
As described above, three layers of the first active material layer / second active material layer / first active material layer were laminated on the electrolytic copper foil as the current collector to obtain a negative electrode.
The weight ratio of the total graphite in the upper and lower first active material layers to the silicon thin film as the second active material layer was 84: 4.6.
[0028]
[Production of positive electrode]
A positive electrode was produced in the same manner as the battery A of the present invention.
[Production of battery]
Using the negative electrode and the positive electrode, a battery was produced in the same manner as the battery A of the present invention.
[0029]
(Production of comparative battery)
Graphite powder and silicon powder were mixed at a weight ratio of 84: 4.6 and slurried using the same fluororesin as above as a binder, and then applied onto an electrolytic copper foil to produce a negative electrode. . A comparative battery was produced in the same manner as the battery of the present invention except that this negative electrode was used.
[0030]
(Charge / discharge cycle test)
A charge / discharge cycle test was performed on the batteries A and B of the present invention and the comparative battery. Charging is performed up to a battery voltage of 4.2 V, discharging is performed up to a battery voltage of 2.75 V, charging / discharging current is set to 100 mA, and discharging is performed in the first cycle, the second cycle, the fifth cycle, and the tenth cycle. Capacity and charge / discharge efficiency were measured. The measurement results are shown in Table 1.
[0031]
[Table 1]
As shown in Table 1, the batteries A and B of the present invention exhibit higher discharge capacity and charge / discharge efficiency than the comparative batteries.
When each battery was disassembled after 10 cycles, the negative electrode active materials of the batteries A and B of the present invention were not found to be separated from the copper foil as the current collector, and the negative electrode active material itself maintained its shape. It was. On the other hand, in the comparative battery, most of the negative electrode active material was peeled off from the current collector, and it was confirmed that silver-white fine powder that seems to be silicon powder was dispersed in the electrolytic solution.
[0033]
【The invention's effect】
According to the present invention, peeling of the active material from the current collector due to expansion and contraction during charge / discharge can be prevented, and good cycle characteristics can be obtained.
Claims (2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000100406A JP3913438B2 (en) | 2000-04-03 | 2000-04-03 | Lithium secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000100406A JP3913438B2 (en) | 2000-04-03 | 2000-04-03 | Lithium secondary battery |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2001283833A JP2001283833A (en) | 2001-10-12 |
| JP3913438B2 true JP3913438B2 (en) | 2007-05-09 |
Family
ID=18614619
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2000100406A Expired - Fee Related JP3913438B2 (en) | 2000-04-03 | 2000-04-03 | Lithium secondary battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3913438B2 (en) |
Families Citing this family (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3520921B2 (en) * | 2001-03-27 | 2004-04-19 | 日本電気株式会社 | Negative electrode for secondary battery and secondary battery using the same |
| US6844113B2 (en) | 2001-04-13 | 2005-01-18 | Sanyo Electric Co., Ltd. | Electrode for lithium secondary battery and method for producing the same |
| JP4415241B2 (en) * | 2001-07-31 | 2010-02-17 | 日本電気株式会社 | Negative electrode for secondary battery, secondary battery using the same, and method for producing negative electrode |
| JP4517560B2 (en) * | 2001-12-28 | 2010-08-04 | 日本電気株式会社 | Lithium ion secondary battery and method of using lithium secondary battery |
| JP4701579B2 (en) * | 2002-01-23 | 2011-06-15 | 日本電気株式会社 | Negative electrode for secondary battery |
| JP4944341B2 (en) * | 2002-02-26 | 2012-05-30 | 日本電気株式会社 | Method for producing negative electrode for lithium ion secondary battery |
| JP4400019B2 (en) * | 2002-04-10 | 2010-01-20 | 日本電気株式会社 | Non-aqueous electrolyte battery and method for producing the same |
| JP4196398B2 (en) * | 2002-08-26 | 2008-12-17 | 日本電気株式会社 | Non-aqueous electrolyte secondary battery |
| JP4623940B2 (en) * | 2003-06-02 | 2011-02-02 | 日本電気株式会社 | Negative electrode material and secondary battery using the same |
| JP3746499B2 (en) | 2003-08-22 | 2006-02-15 | 三星エスディアイ株式会社 | Negative electrode active material for lithium secondary battery, method for producing the same, and lithium secondary battery |
| JP2005293960A (en) * | 2004-03-31 | 2005-10-20 | Jfe Chemical Corp | Anode for lithium ion secondary battery, and lithium ion secondary battery |
| JP4775621B2 (en) * | 2004-09-06 | 2011-09-21 | 株式会社Ｇｓユアサ | Nonaqueous electrolyte secondary battery |
| JP5481904B2 (en) * | 2009-03-30 | 2014-04-23 | 日産自動車株式会社 | Negative electrode for lithium ion secondary battery and lithium ion secondary battery using the same |
| JP5285033B2 (en) * | 2010-08-06 | 2013-09-11 | 日本電気株式会社 | Negative electrode material and secondary battery using the same |
| JP5676173B2 (en) * | 2010-08-09 | 2015-02-25 | 日本電気株式会社 | Method for producing negative electrode for secondary battery |
| JP2010251339A (en) * | 2010-08-11 | 2010-11-04 | Nec Corp | Secondary battery, and negative electrode for the same |
| JP2012146398A (en) * | 2011-01-07 | 2012-08-02 | Hitachi Ltd | Lithium secondary battery |
| WO2013062335A1 (en) * | 2011-10-25 | 2013-05-02 | 주식회사 엘지화학 | Cathode for secondary battery and secondary battery having same |
| JP2015069712A (en) * | 2013-09-26 | 2015-04-13 | 凸版印刷株式会社 | Negative electrode for nonaqueous electrolyte secondary battery, method for manufacturing the same, and nonaqueous electrolyte secondary battery |
| CN111213262B (en) * | 2017-12-01 | 2023-08-22 | 株式会社Lg新能源 | Negative electrode and secondary battery comprising same |
-
2000
- 2000-04-03 JP JP2000100406A patent/JP3913438B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2001283833A (en) | 2001-10-12 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP3913439B2 (en) | Lithium secondary battery | |
| JP3913438B2 (en) | Lithium secondary battery | |
| JP4201509B2 (en) | Electrode for lithium secondary battery and lithium secondary battery | |
| US7556881B2 (en) | Lithium secondary battery | |
| WO2015111710A1 (en) | Non-aqueous secondary battery | |
| JP4212458B2 (en) | Lithium secondary battery | |
| WO2015041167A1 (en) | Non-aqueous secondary battery | |
| JP3670938B2 (en) | Lithium secondary battery | |
| WO2014117421A1 (en) | Non-aqueous electrolyte for lithium ion batteries and corresponding lithium ion battery thereof | |
| WO2023070769A1 (en) | Positive electrode, preparation method therefor, and lithium ion secondary battery | |
| JP2002231224A (en) | Lithium secondary battery electrode, its manufacturing method, and lithium secondary battery | |
| JP2005235397A (en) | Electrode for lithium battery, lithium battery using it, and lithium secondary battery | |
| JP4412885B2 (en) | Lithium secondary battery | |
| JP5863631B2 (en) | Method for producing non-aqueous electrolyte secondary battery | |
| US11962007B2 (en) | Lithium-ion secondary battery, battery module, battery pack, and powered device | |
| JP4318405B2 (en) | Lithium secondary battery | |
| WO2006103829A1 (en) | Nonaqueous electrolyte secondary battery | |
| JP4104476B2 (en) | Method of using lithium secondary battery and lithium secondary battery | |
| JP6946536B1 (en) | Lithium secondary battery | |
| JP4212439B2 (en) | How to use lithium secondary battery | |
| CN115039256A (en) | Positive electrode, method for producing same, and lithium ion secondary battery | |
| JP5846031B2 (en) | Lithium ion secondary battery and non-aqueous electrolyte | |
| JPH07105977A (en) | Non-aqueous electrolyte secondary battery | |
| JP4841125B2 (en) | Method for manufacturing lithium secondary battery | |
| US20230268555A1 (en) | Prevention of gassing in si dominant lithium-ion batteries |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20040421 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20050518 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20050705 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20050823 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20050927 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20051031 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20051124 |
|
| 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: 20070116 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20070131 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110209 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110209 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120209 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120209 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130209 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130209 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140209 Year of fee payment: 7 |
|
| LAPS | Cancellation because of no payment of annual fees |