JPH10334916A - Negative electrode for lithium secondary battery and its manufacture - Google Patents
Negative electrode for lithium secondary battery and its manufactureInfo
- Publication number
- JPH10334916A JPH10334916A JP9144301A JP14430197A JPH10334916A JP H10334916 A JPH10334916 A JP H10334916A JP 9144301 A JP9144301 A JP 9144301A JP 14430197 A JP14430197 A JP 14430197A JP H10334916 A JPH10334916 A JP H10334916A
- Authority
- JP
- Japan
- Prior art keywords
- graphite
- negative electrode
- lithium secondary
- secondary battery
- carbon
- 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.)
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Links
Classifications
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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
Landscapes
- Battery Electrode And Active Subsutance (AREA)
- Carbon And Carbon Compounds (AREA)
- Secondary Cells (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は活物質を炭素質材料
から構成したリチウム二次電池用負極及びその製造方法
に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negative electrode for a lithium secondary battery in which an active material is composed of a carbonaceous material, and a method of manufacturing the same.
【０００２】[0002]
【従来の技術】この種のリチウム二次電池は、負極の炭
素質材料にリチウムイオンが出入りして充放電がなされ
るため、安全性が高いという利点があり、近年、多くの
種類のものが開発されている。負極の炭素質材料として
は充放電容量の面からグラファイトが最も好ましいとさ
れているが、これはプロピレンカーボネート（ＰＣ）を
主体とする電解液に対して反応性があるため、低温特性
が悪いエチレンカーボネート（ＥＣ）等を使用せざるを
得ず、この点の改良が待たれていた。2. Description of the Related Art Lithium secondary batteries of this type have the advantage of high safety because lithium ions enter and leave the carbonaceous material of the negative electrode and are charged and discharged. Is being developed. As the carbonaceous material of the negative electrode, graphite is considered to be most preferable from the viewpoint of charge / discharge capacity. However, since it is reactive with an electrolytic solution mainly composed of propylene carbonate (PC), ethylene has poor low-temperature characteristics. There has been no choice but to use carbonate (EC), and improvement in this respect has been awaited.
【０００３】グラファイトのＰＣに対する反応性を抑制
する技術としては、例えば特開平５−１２１０６６号公
報に記載された発明が公知である。これは、グラファイ
ト粒子を石油ピッチ等と混合した後に焼成することによ
り、グラファイト粒子の表面に無定型炭素の被覆を形成
するものである。このような無定形炭素被覆のグラファ
イトを活物質として使用した負極では、ＰＣとの反応性
が抑えられて低温特性に優れたリチウム二次電池を構成
することができる。As a technique for suppressing the reactivity of graphite with respect to PC, for example, the invention described in Japanese Patent Application Laid-Open No. 5-110666 is known. In this method, graphite particles are mixed with petroleum pitch or the like and then fired to form a coating of amorphous carbon on the surfaces of the graphite particles. In the negative electrode using such an amorphous carbon-coated graphite as an active material, a lithium secondary battery excellent in low-temperature characteristics by suppressing reactivity with PC can be constituted.
【０００４】[0004]
【発明が解決しようとする課題】しかしながら、上述の
炭素質材料を使用した負極では、電池として構成したと
きの高温保存特性が悪いという問題があった。すなわ
ち、電池を高温度に保存した場合に、電池容量が著しく
低下してしまうのである。これは、次のような原因によ
ると推定される。However, the negative electrode using the above-mentioned carbonaceous material has a problem that the high-temperature storage characteristics when configured as a battery are poor. That is, when the battery is stored at a high temperature, the battery capacity is significantly reduced. This is presumed to be due to the following reasons.
【０００５】すなわち、従来の方法で製造した負極の活
物質では、グラファイトと無定形炭素或いは低結晶性炭
素からなる皮膜との界面においてグラファイト層と皮膜
層との間で十分な化学結合が持たれておらず、グラファ
イトのエッジ面の炭素原子が不飽和結合の状態で多く残
留している。従って、この残留不飽和結合炭素が、高温
度になると電解液中のリチウムイオンと反応して充放電
に寄与するリチウムイオン量を減らしてしまうのであ
る。That is, in the negative electrode active material manufactured by the conventional method, a sufficient chemical bond is provided between the graphite layer and the coating layer at the interface between the graphite and the coating made of amorphous carbon or low-crystalline carbon. However, many carbon atoms on the edge surface of graphite remain in an unsaturated bond state. Therefore, when the temperature of the residual unsaturated bond carbon becomes high, it reacts with lithium ions in the electrolytic solution to reduce the amount of lithium ions contributing to charge and discharge.
【０００６】しかも、従来製法では、グラファイトを覆
う皮膜の厚さが相当に厚くなってしまうため、充放電容
量の少ない皮膜成分が不必要に増えて活物質のエネルギ
ー密度を低下させてしまうという問題もあった。In addition, in the conventional production method, the thickness of the coating covering the graphite becomes considerably large, so that a coating component having a small charge / discharge capacity is unnecessarily increased and the energy density of the active material is reduced. There was also.
【０００７】かかる事情にあるから、無定形炭素や低結
晶性炭素などによる耐ＰＣ性皮膜を形成するためには、
エッジ面の不飽和炭素のほとんどと化学的に結合し、し
かも、できるだけ薄い皮膜を形成することが望ましい。
しかし、グラファイト粒子の表面にいわは物理的なコー
ティングによって低結晶性炭素の被覆を形成するという
特開平５−１２１０６６号公報に記載された従来の製造
方法では、低結晶性炭素の膜厚を十分に薄くすることは
困難である。また、本発明者らは、グラファイトを高温
の不活性雰囲気において炭化水素を導入し、炭化水素の
熱分解によってグラファイト表面に低結晶性炭素の皮膜
を成長させることも試みたが、これでは薄い膜厚の被覆
を形成できるものの、電解液との反応性の抑制が十分に
行われないという問題が生ずるものであった。Under these circumstances, in order to form a PC-resistant film of amorphous carbon, low-crystalline carbon, or the like,
It is desirable to form a film which is chemically bonded to most of the unsaturated carbon on the edge surface and is as thin as possible.
However, according to the conventional manufacturing method described in Japanese Patent Application Laid-Open No. 5-121066, in which the surface of graphite particles is coated with low-crystalline carbon by physical coating, the film thickness of low-crystalline carbon is not sufficiently increased. It is difficult to make it thin. The present inventors have also tried to introduce a hydrocarbon into graphite in a high-temperature inert atmosphere and grow a low-crystalline carbon film on the graphite surface by pyrolysis of the hydrocarbon. Although a thick coating can be formed, there is a problem that the reactivity with the electrolytic solution is not sufficiently suppressed.
【０００８】本発明は上記事情に鑑みてなされたもの
で、その目的は、低温性能及び高温保存特性を改良で
き、しかも、容量増大も可能にできるリチウム二次電池
用負極及びその製造方法を提供することを目的とする。The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a negative electrode for a lithium secondary battery capable of improving low-temperature performance and high-temperature storage characteristics and increasing capacity, and a method of manufacturing the same. The purpose is to do.
【０００９】[0009]
【課題を解決するための手段及びその作用・効果】請求
項１の発明は、負極の活物質の製造に際し、グラファイ
トを非酸化雰囲気で加熱して表面の酸素を取り除く活性
化処理を行い、その後、高温不活性雰囲気下で有機物を
導入して活性化グラファイトの表面に低結晶性炭素又は
炭素化合物の薄膜を形成するところに特徴を有する。上
記発明において、グラファイトを非酸化雰囲気で高温度
に加熱すると、表面に結合している酸素がＣＯ又はＣＯ
2 の形で除去され、活性化された炭素原子が露出する。
その加熱温度については、グラファイト表面の汚れ状態
や生産性等を考慮して種々設定することができるが、８
００℃〜１２００℃程度とすることが好ましい。Means for Solving the Problems and Action / Effect The invention according to claim 1 provides an activation treatment for removing graphite from the surface by heating graphite in a non-oxidizing atmosphere when producing an active material for a negative electrode. It is characterized in that a thin film of low-crystalline carbon or a carbon compound is formed on the surface of activated graphite by introducing an organic substance under a high-temperature inert atmosphere. In the above invention, when graphite is heated to a high temperature in a non-oxidizing atmosphere, oxygen bonded to the surface becomes CO or CO.
Removed in the form of 2, exposing the activated carbon atoms.
The heating temperature can be variously set in consideration of the stain state of the graphite surface, productivity, and the like.
The temperature is preferably set to about 00C to 1200C.
【００１０】この後、高温不活性雰囲気下で例えば炭化
水素等の有機物を導入すると、その有機物の熱分解によ
り生成した炭素がグラファイト粒子の表面に析出して低
結晶性炭素又は炭素化合物の薄膜が形成される。この場
合の加熱温度及び加熱時間も生産性等を考慮して設定す
ることができるが、６００℃〜１２００℃程度で３０分
から９０分程度が好ましく、有機物は例えば窒素ガス等
の不活性ガスと共に炉内に導入することが好ましい。Thereafter, when an organic substance such as a hydrocarbon is introduced in a high-temperature inert atmosphere, carbon generated by thermal decomposition of the organic substance is deposited on the surface of the graphite particles to form a thin film of low-crystalline carbon or a carbon compound. It is formed. In this case, the heating temperature and the heating time can be set in consideration of productivity and the like. However, the heating temperature and the heating time are preferably from about 600 ° C. to 1200 ° C. for about 30 minutes to 90 minutes. It is preferred to be introduced into the inside.
【００１１】このようにして低結晶性炭素又は炭素化合
物により被覆されたグラファイトを活物質とし、例えば
これにバインダを添加して集電体に塗布して乾燥させる
ことによりリチウム二次電池の負極を構成することがで
きる。この負極によれば、グラファイトの表面が低結晶
性炭素又は炭素化合物の薄膜により覆われており、グラ
ファイト部分にまでＰＣ電解液が侵入できないため、Ｐ
Ｃの反応を抑えることができる。また、グラファイト表
面の炭素をいったん活性化してから有機物の熱分解によ
って低結晶性炭素又は炭素化合物をグラファイト表面に
結合させるから、化学結合が強固で均一な皮膜を形成す
ることができ、さらにグラファイト表面の未結合の炭素
原子（不対電子を有する炭素原子）の数を大幅に減らし
てグラファイトと低結晶性炭素又は炭素化合物との間の
Ｃ−Ｃ結合を増大させることができる。このことは、低
結晶性炭素又は炭素化合物の被覆の膜厚を薄くしても電
解液との反応性を十分に抑えることができることを意味
し、充放電容量が少ない部分の膜厚が薄い分、活物質の
エネルギー密度を高めて充放電容量を増大させることが
できる。しかも、この方法で製造された低結晶性炭素又
は炭素化合物の薄膜で覆ったグラファイトでは、上述の
ようにグラファイト層と低結晶性炭素層又は炭素化合物
との間の結合度が高まるから、サイクル特性も大きく向
上する。The graphite coated with the low-crystalline carbon or carbon compound is used as an active material. For example, a binder is added to the active material and the resultant is coated on a current collector and dried to form a negative electrode of a lithium secondary battery. Can be configured. According to this negative electrode, the surface of graphite is covered with a thin film of low-crystalline carbon or a carbon compound, and the PC electrolyte cannot penetrate into the graphite portion.
The reaction of C can be suppressed. In addition, since the carbon on the graphite surface is activated once, and the low-crystalline carbon or carbon compound is bonded to the graphite surface by thermal decomposition of an organic substance, a uniform chemical film with a strong chemical bond can be formed. Can greatly reduce the number of unbonded carbon atoms (carbon atoms with unpaired electrons) to increase the CC bond between graphite and the low crystalline carbon or carbon compound. This means that the reactivity with the electrolytic solution can be sufficiently suppressed even when the thickness of the coating of the low-crystalline carbon or carbon compound is reduced, and the portion having a small charge / discharge capacity has a small thickness. In addition, the charge / discharge capacity can be increased by increasing the energy density of the active material. In addition, the graphite covered with a thin film of low-crystalline carbon or carbon compound produced by this method has a high degree of bonding between the graphite layer and the low-crystalline carbon layer or carbon compound as described above, and therefore has a cycle characteristic. Is also greatly improved.
【００１２】請求項２の発明は、上記発明の活性化処理
に先だってグラファイト表面を酸又はアルカリ液により
洗浄する清浄化処理を行うところに特徴を有する。この
清浄化処理を行うと、グラファイト表面に付着・吸着或
いは結合している不純物が除去されるから、活性化処理
がより効率的に行われて一層の好結果が得られる。な
お、洗浄液としては、硝酸や硫酸等の強酸が最も好まし
い。The invention of claim 2 is characterized in that prior to the activation treatment of the above invention, a cleaning treatment for cleaning the graphite surface with an acid or an alkali solution is performed. By performing this cleaning treatment, impurities adhering, adsorbing, or bonding to the graphite surface are removed, so that the activation treatment is performed more efficiently, and more favorable results are obtained. Note that a strong acid such as nitric acid or sulfuric acid is most preferable as the cleaning liquid.
【００１３】ところで、本発明者らの研究によれば、低
結晶性炭素被覆を構成する炭素原子の一部を窒素原子で
置換した炭素化合物であるＣxＮの皮膜とすると、化学
的により安定となって高温保存特性が改善されることが
発見された。According to the study of the present inventors, when a CxN film, which is a carbon compound in which a part of carbon atoms constituting a low-crystalline carbon coating is substituted with nitrogen atoms, becomes chemically more stable. It was found that the high temperature storage characteristics were improved.
【００１４】このＣxＮの皮膜は、上述した請求項１又
は２の発明において、有機物として窒素を含有する有機
物を使用すると効率的に形成することができ（請求項３
の発明）、特にアセトニトリル蒸気を窒素ガスと共に導
入することが最も好ましい。なお、グラファイト粒子の
表面に形成されたＣxＮの皮膜は、ＸＰＳ分析（Ｘ線光
電子分光法）によって確認することができる。ＸＰＳ分
析によっては表面がＣxＯ，ＣyＮＯzという成分として
分析されるが、測定深度を深めて行くとＯ，Ｎの相対量
が減少してゆくから、ＣxＮの表面皮膜が形成されてい
ることが明らかである。This CxN film can be efficiently formed by using an organic substance containing nitrogen as the organic substance in the above-mentioned invention of claim 1 or 2 (claim 3).
Invention), particularly, acetonitrile vapor is most preferably introduced together with nitrogen gas. The CxN film formed on the surface of the graphite particles can be confirmed by XPS analysis (X-ray photoelectron spectroscopy). According to the XPS analysis, the surface is analyzed as components of CxO and CyNOz. However, as the measurement depth is increased, the relative amounts of O and N decrease, and it is clear that a CxN surface film is formed. is there.
【００１５】[0015]
【実施例】以下、本発明のいくつかの実施例を比較例と
ともに説明する。ここで、グラファイト粒子は平均粒径
７μｍの天然黒鉛を使用している。EXAMPLES Some examples of the present invention will be described below along with comparative examples. Here, the graphite particles use natural graphite having an average particle size of 7 μm.
【００１６】［実施例１］まず、グラファイト粒子を９
４％硝酸によって洗浄してその表面の不純物を除去する
とともに、表面を酸化させた（清浄化処理）。次に、そ
のグラファイトを非酸化雰囲気で加熱して表面の酸素を
取り除く活性化処理を行った。これは高温還元炉又は高
温真空炉にグラファイトを収容して９５０℃に加熱する
ことにより行い、これにてグラファイト表面の酸素原子
がＣＯ又はＣＯ2 の形で取り除かれて活性な炭素原子が
表面に露出する。Example 1 First, graphite particles were mixed with 9
The surface was washed with 4% nitric acid to remove impurities on the surface, and the surface was oxidized (cleaning treatment). Next, the graphite was heated in a non-oxidizing atmosphere to perform an activation treatment for removing oxygen on the surface. This is done by placing graphite in a high-temperature reduction furnace or high-temperature vacuum furnace and heating it to 950 ° C, whereby oxygen atoms on the graphite surface are removed in the form of CO or CO2 and active carbon atoms are exposed on the surface. I do.
【００１７】次に、その活性化グラファイトを外気に触
れさせることなく窒素雰囲気炉に導入して９５０℃に加
熱しておき、ここにアセトニトリル蒸気を窒素ガスとと
もに導入した。このときアセトニトリルの分圧は０．９
×１０4 Ｐａで、全圧は１×１０5 Ｐａであり、処理時
間は３０分から１時間３０分であった。これにより、活
性化グラファイトの表面にＣxＮの皮膜が形成された。Next, the activated graphite was introduced into a nitrogen atmosphere furnace without being exposed to the outside air, heated to 950 ° C., and acetonitrile vapor was introduced together with nitrogen gas. At this time, the partial pressure of acetonitrile was 0.9.
The pressure was × 10 4 Pa, the total pressure was 1 × 10 5 Pa, and the processing time was 30 minutes to 1 hour 30 minutes. As a result, a CxN film was formed on the surface of the activated graphite.
【００１８】このグラファイト粒子の９２重量部に対し
て、Ｎ−メチルピロリドンを溶媒とした１０重量％濃度
のポリ弗化ビニリデン溶液をポリ弗化ビニリデンが８重
量部となるように加えて攪拌し、これを負極ペーストと
した。この負極ペーストを厚さ３０μｍの銅箔に厚みが
１００μｍとなるように塗布した後、１００℃で２時間
真空乾燥した。これを２cm角に切り出して多孔度が２５
％となるようにプレスして試験極とした。相手極には金
属リチウム板を用い、これらを例えばポリエチレン製の
微孔膜セパレータを挟んで周知の電池構造とし、ここに
プロピレンカーボネート（ＰＣ）とエチレンカーボネー
ト（ＥＣ）との体積比１：１の混合物に１モルＬi ＰＦ
6を混合した電解液を注液してリチウム二次電池を構成
した。To 92 parts by weight of the graphite particles, a 10% by weight polyvinylidene fluoride solution using N-methylpyrrolidone as a solvent was added so that the polyvinylidene fluoride became 8 parts by weight, followed by stirring. This was used as a negative electrode paste. This negative electrode paste was applied to a copper foil having a thickness of 30 μm so as to have a thickness of 100 μm, and then vacuum dried at 100 ° C. for 2 hours. This is cut into 2 cm squares and has a porosity of 25.
% To obtain a test electrode. A lithium metal plate is used as a counter electrode, and these have a well-known battery structure with a microporous membrane separator made of, for example, polyethylene, in which propylene carbonate (PC) and ethylene carbonate (EC) have a volume ratio of 1: 1. 1 mol Li PF in the mixture
The lithium secondary battery was constructed by injecting the electrolyte mixed with 6.
【００１９】［実施例２］上述のアセトニトリル蒸気に
代えて炭化水素（ベンゼン又はフェノール）を使用した
ところが相違し、その他は同一条件である。Example 2 A hydrocarbon (benzene or phenol) was used in place of the acetonitrile vapor, and the other conditions were the same.
【００２０】［比較例］キノリン１５重量部に３重量部
のバインダーピッチを溶解させ、実施例１，２と同一の
グラファイト粒子を１重量部浸漬し、次いでキノリンを
蒸発させた後に、窒素ガス中で４００℃で焼成した。こ
のようにして製造したグラファイトを使用したところが
相違し、その他は実施例１と同一条件である。Comparative Example 3 parts by weight of binder pitch were dissolved in 15 parts by weight of quinoline, 1 part by weight of the same graphite particles as in Examples 1 and 2 were immersed, and then quinoline was evaporated. At 400.degree. The difference was that the graphite thus produced was used, and the other conditions were the same as in Example 1.
【００２１】［高温保存特性の評価］上記３種のリチウ
ム二次電池を０．２ｍＡ／cm2 の定電流で負極電位が金
属リチウム正極に対して０Ｖになるまで充電した後に、
４５℃で３０日間放置した。その後、室温で０．２ｍＡ
／cm2 の放電電流によって放電させて測定した場合の残
存容量と、初期容量との比率（容量保持率％）を計算し
た。測定結果は、次の表１のようであり、特にＣxＮ皮
膜を形成した実施例１が格段に優れた高温保存性を示し
た。[Evaluation of High-Temperature Storage Characteristics] The above three lithium secondary batteries were charged at a constant current of 0.2 mA / cm 2 until the negative electrode potential became 0 V with respect to the metallic lithium positive electrode.
It was left at 45 ° C. for 30 days. Then, 0.2 mA at room temperature
The ratio (capacity retention%) between the remaining capacity and the initial capacity measured by discharging with a discharge current of / cm @ 2 was calculated. The measurement results are as shown in Table 1 below. In particular, Example 1 in which the CxN film was formed showed remarkably excellent high-temperature storage property.
【００２２】[0022]
【表１】 ちなみに、上述の実施例１及び実施例２において製造し
たＣxＮ及び低結晶性炭素被覆のグラファイトのＸＰＳ
分析結果を次表に示す。実施例１では、測定深度を深め
て行くと（照射角度が大きいほど表面から深い部分の組
成を表す）、Ｏ，Ｎの相対量が減少してゆき、ＣxＮの
表面皮膜が形成されていることが判る。[Table 1] By the way, XPS of CxN and graphite of low crystalline carbon coating produced in Example 1 and Example 2 described above.
The analysis results are shown in the following table. In Example 1, as the measurement depth was increased (the larger the irradiation angle, the deeper the composition from the surface), the relative amounts of O and N gradually decreased, and a CxN surface film was formed. I understand.
【００２３】[0023]
【表２】 [Table 2]
─────────────────────────────────────────────────────
────────────────────────────────────────────────── ───
【手続補正書】[Procedure amendment]
【提出日】平成９年７月２日[Submission date] July 2, 1997
【手続補正１】[Procedure amendment 1]
【補正対象書類名】明細書[Document name to be amended] Statement
【補正対象項目名】００１７[Correction target item name] 0017
【補正方法】変更[Correction method] Change
【補正内容】[Correction contents]
【００１７】次に、その活性化グラファイトを外気に触
れさせることなく窒素雰囲気炉に導入して９５０℃に加
熱しておき、ここにアセトニトリル蒸気を窒素ガスとと
もに導入した。このときアセトニトリルの分圧は０．９
×１０4Ｐａで、全圧は１×１０5Ｐａであり、処理時間
は３０分から１時間３０分であった。これにより、活性
化グラファイトの表面にＣxＮの皮膜が形成された。Next, the activated graphite was introduced into a nitrogen atmosphere furnace without being exposed to the outside air, heated to 950 ° C., and acetonitrile vapor was introduced together with nitrogen gas. At this time, the partial pressure of acetonitrile was 0.9.
× 10 4 Pa, the total pressure was 1 × 10 5 Pa, and the treatment time was 30 minutes to 1 hour 30 minutes. As a result, a CxN film was formed on the surface of the activated graphite.
【手続補正２】[Procedure amendment 2]
【補正対象書類名】明細書[Document name to be amended] Statement
【補正対象項目名】００１８[Correction target item name] 0018
【補正方法】変更[Correction method] Change
【補正内容】[Correction contents]
【００１８】このグラファイト粒子の９２重量部に対し
て、Ｎ−メチルピロリドンを溶媒とした１０重量％濃度
のポリ弗化ビニリデン溶液をポリ弗化ビニリデンが８重
量部となるように加えて攪拌し、これを負極ペーストと
した。この負極ペーストを厚さ３０μｍの銅箔に厚みが
１００μｍとなるように塗布した後、１００℃で２時間
真空乾燥した。これを２cm角に切り出して多孔度が２５
％となるようにプレスして試験極とした。相手極には金
属リチウム板を用い、これらを例えばポリエチレン製の
微孔膜セパレータを挟んで周知の電池構造とし、ここに
プロピレンカーボネート（ＰＣ）とエチレンカーボネー
ト（ＥＣ）との体積比１：１の混合物に１モルＬi ＰＦ
6を混合した電解液を注液してリチウム二次電池を構成
した。To 92 parts by weight of the graphite particles, a 10% by weight polyvinylidene fluoride solution using N-methylpyrrolidone as a solvent was added so that the polyvinylidene fluoride became 8 parts by weight, followed by stirring. This was used as a negative electrode paste. This negative electrode paste was applied to a copper foil having a thickness of 30 μm so as to have a thickness of 100 μm, and then vacuum dried at 100 ° C. for 2 hours. This is cut into 2 cm squares and has a porosity of 25.
% To obtain a test electrode. A lithium metal plate is used as a counter electrode, and these have a well-known battery structure with a microporous membrane separator made of, for example, polyethylene, in which propylene carbonate (PC) and ethylene carbonate (EC) have a volume ratio of 1: 1. 1 mol Li PF in the mixture
The lithium secondary battery was constructed by injecting the electrolyte mixed with 6 .
───────────────────────────────────────────────────── フロントページの続き (72)発明者 岡本 朋仁 京都市南区吉祥院西ノ庄猪之馬場町１番地 日本電池株式会社内 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tomohito Okamoto 1 Nishinosho Ino Babacho, Kichijoin, Minami-ku, Kyoto Inside Nippon Battery Co., Ltd.
Claims (5)
使用されるリチウム二次電池用負極の製造方法であっ
て、 負極の活物質は、グラファイトを非酸化雰囲気で加熱し
て表面の酸素を取り除く活性化処理を行い、その後、高
温の不活性雰囲気下で有機物を導入して活性化グラファ
イトの表面に炭素又は炭素化合物を結合させることによ
り炭素又は炭素化合物からなる薄膜を形成することを特
徴とするリチウム二次電池用負極の製造方法。1. A method of manufacturing a negative electrode for a lithium secondary battery used together with a non-aqueous electrolyte of a lithium secondary battery, wherein an active material of the negative electrode is heated to graphite in a non-oxidizing atmosphere to remove oxygen from the surface. Performing an activation treatment, and thereafter, forming a thin film made of carbon or carbon compound by introducing organic matter under a high temperature inert atmosphere and bonding carbon or carbon compound to the surface of activated graphite. A method for producing a negative electrode for a lithium secondary battery.
表面を酸又はアルカリ液により洗浄する清浄化処理を行
うことを特徴とする請求項１記載のリチウム二次電池用
負極の製造方法。2. The method for producing a negative electrode for a lithium secondary battery according to claim 1, wherein a cleaning treatment for cleaning the graphite surface with an acid or an alkali solution is performed prior to the activation treatment.
ることを特徴とする請求項１又は２に記載のリチウム二
次電池用負極の製造方法。3. The method for producing a negative electrode for a lithium secondary battery according to claim 1, wherein the organic substance is an organic substance containing nitrogen.
これを窒素ガスと共に導入することを特徴とする請求項
３に記載のリチウム二次電池用負極の製造方法。4. The organic substance is acetonitrile,
4. The method for producing a negative electrode for a lithium secondary battery according to claim 3, wherein the method is introduced together with nitrogen gas.
使用されるものであって、負極の活物質が、グラファイ
トの表面にＣxＮの被覆が形成されたものであることを
特徴とするリチウム二次電池用負極。5. A lithium secondary battery used together with a non-aqueous electrolyte of a lithium secondary battery, wherein the active material of the negative electrode is a graphite having a CxN coating formed on a surface thereof. Negative electrode for battery.
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|---|---|---|---|
| JP14430197A JP3807691B2 (en) | 1997-06-02 | 1997-06-02 | Negative electrode for lithium secondary battery and method for producing the same |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14430197A JP3807691B2 (en) | 1997-06-02 | 1997-06-02 | Negative electrode for lithium secondary battery and method for producing the same |
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| Publication Number | Publication Date |
|---|---|
| JPH10334916A true JPH10334916A (en) | 1998-12-18 |
| JP3807691B2 JP3807691B2 (en) | 2006-08-09 |
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ID=15358898
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|---|---|---|---|
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|---|---|---|---|---|
| JP2009117334A (en) * | 2007-10-17 | 2009-05-28 | Hitachi Chem Co Ltd | Carbon-covered graphite anode material for lithium-ion secondary battery, its manufacturing method, and anode for lithium-ion secondary battery and lithium-ion secondary battery using the anode |
| KR20190062400A (en) | 2016-10-13 | 2019-06-05 | 내셔날 인스티튜트 오브 어드밴스드 인더스트리얼 사이언스 앤드 테크놀로지 | Lithium ion secondary battery and electric appliance using the same |
| CN116081615A (en) * | 2021-11-08 | 2023-05-09 | 湖南中科星城石墨有限公司 | Artificial graphite negative electrode material, preparation method and application |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009117334A (en) * | 2007-10-17 | 2009-05-28 | Hitachi Chem Co Ltd | Carbon-covered graphite anode material for lithium-ion secondary battery, its manufacturing method, and anode for lithium-ion secondary battery and lithium-ion secondary battery using the anode |
| KR20190062400A (en) | 2016-10-13 | 2019-06-05 | 내셔날 인스티튜트 오브 어드밴스드 인더스트리얼 사이언스 앤드 테크놀로지 | Lithium ion secondary battery and electric appliance using the same |
| US11289706B2 (en) | 2016-10-13 | 2022-03-29 | National Institute Of Advanced Industrial Science And Technology | Lithium ion secondary battery and electric device using same |
| CN116081615A (en) * | 2021-11-08 | 2023-05-09 | 湖南中科星城石墨有限公司 | Artificial graphite negative electrode material, preparation method and application |
| WO2023078159A1 (en) * | 2021-11-08 | 2023-05-11 | 湖南中科星城石墨有限公司 | Artificial graphite negative electrode material, preparation method, and use |
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| Publication number | Publication date |
|---|---|
| JP3807691B2 (en) | 2006-08-09 |
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