JP2015046219A - Negative electrode for lithium ion secondary batteries, and lithium ion secondary battery using the same - Google Patents
Negative electrode for lithium ion secondary batteries, and lithium ion secondary battery using the same Download PDFInfo
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
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Abstract
Description
本発明は、リチウムイオン二次電池用負極及び該リチウムイオン二次電池用負極を用いたリチウムイオン二次電池に関する。 The present invention relates to a negative electrode for a lithium ion secondary battery and a lithium ion secondary battery using the negative electrode for a lithium ion secondary battery.
リチウムイオン二次電池は、携帯用電子機器や通信機器などの駆動電源として利用が広がっている。一般に、リチウムイオン二次電池では、負極板にリチウムの吸蔵・放出が可能な炭素材料を用い、正極板にＬｉＣｏＯ２などの遷移金属とリチウムの複合酸化物を活物質として用いており、これによって高出力、高容量の二次電池を実現している。 Lithium ion secondary batteries are widely used as drive power sources for portable electronic devices and communication devices. Generally, in a lithium ion secondary battery, a carbon material capable of occluding and releasing lithium is used for the negative electrode plate, and a composite oxide of lithium and a transition metal such as LiCoO 2 is used as the active material for the positive electrode plate. A high-power, high-capacity secondary battery is realized.
近年、電子機器および通信機器の多機能化に伴って、さらなる高出力、高容量化が望まれている。しかしながら出力特性及び入力特性が十分でないといった問題があり、特許文献１〜特許文献３では負極にリチウムを吸蔵・放出可能な炭素質材料とリチウムを吸蔵・放出可能な酸化物とを含むことで、入・出力特性に優れたリチウムイオン二次電池を提供することを目的としている。 In recent years, with higher functionality of electronic devices and communication devices, higher output and higher capacity are desired. However, there is a problem that output characteristics and input characteristics are not sufficient, and in Patent Documents 1 to 3, the negative electrode includes a carbonaceous material capable of occluding and releasing lithium and an oxide capable of occluding and releasing lithium, The object is to provide a lithium ion secondary battery with excellent input / output characteristics.
ところが、リチウムを吸蔵・放出可能な酸化物は、導電性が低いため、電池の内部抵抗が増加し、電池の高出力特性を低下させる要因となる。また、電池の作動電圧の設定範囲次第では活物質として機能しないため、電池の高容量化を阻害させる要因ともなり、高入出力、高容量化を図ることができない。 However, since the oxide capable of inserting and extracting lithium has low conductivity, the internal resistance of the battery is increased, which causes a decrease in the high output characteristics of the battery. Moreover, since it does not function as an active material depending on the setting range of the operating voltage of the battery, it becomes a factor that hinders the increase in capacity of the battery, and high input / output and high capacity cannot be achieved.
負極活物質層としてリチウムを吸蔵・放出可能な炭素質材料とリチウムを吸蔵・放出可能な酸化物とを含み、高い入出力特性に優れた高容量リチウムイオン二次電池を提供することを目的としながら、リチウムを吸蔵・放出可能な酸化物は、導電性が低いため、電池の内部抵抗が増加し、電池の高出力特性を低下させる要因となる。また、リチウムを吸蔵・放出可能な酸化物は、電池の作動電圧の設定範囲次第では活物質として機能しないため、電池の高容量化を阻害させる要因ともなり、高入出力、高容量化を図ることができない。 An object of the present invention is to provide a high-capacity lithium ion secondary battery that includes a carbonaceous material capable of occluding and releasing lithium as an anode active material layer and an oxide capable of occluding and releasing lithium, and having excellent input / output characteristics. However, since the oxide capable of inserting and extracting lithium has low conductivity, the internal resistance of the battery is increased and the high output characteristic of the battery is deteriorated. In addition, an oxide capable of inserting and extracting lithium does not function as an active material depending on the setting range of the operating voltage of the battery. Therefore, it becomes a factor that hinders the increase in the capacity of the battery, so that high input / output and high capacity are achieved. I can't.
本発明は、かかる課題に鑑みなされたもので、その主な目的は、電池の高出力、高容量特性に優れたリチウムイオン二次電池用負極を提供することにある。 This invention is made | formed in view of this subject, The main objective is to provide the negative electrode for lithium ion secondary batteries excellent in the high output of a battery, and a high capacity | capacitance characteristic.
本発明に係るリチウムイオン二次電池用負極は、集電体と、集電体の上に形成された活物質を含む層からなり、活物質は、炭素材料とリチウムイオンを吸蔵・放出可能な金属酸化物とからなり、金属酸化物の平均粒径は、炭素材料の平均粒径の１／１０以下であり、炭素材料の表面の少なくとも一部が金属酸化物で被覆されており、金属酸化物の炭素材料に対する被覆率が３０％〜７０％であることを特徴とする。 A negative electrode for a lithium ion secondary battery according to the present invention comprises a current collector and a layer containing an active material formed on the current collector, and the active material can occlude and release a carbon material and lithium ions. The metal oxide has an average particle size that is 1/10 or less of the average particle size of the carbon material, and at least a part of the surface of the carbon material is coated with the metal oxide. It is characterized in that the covering ratio of the product to the carbon material is 30% to 70%.
本発明は、電池出力をより向上させると共にサイクル特性をより高めることができるリチウム二次電池及びその使用方法を提供することができる。 INDUSTRIAL APPLICABILITY The present invention can provide a lithium secondary battery that can further improve battery output and further improve cycle characteristics, and a method for using the lithium secondary battery.
本発明を説明する前に、本発明を想到するに至った経緯をまず説明する。 Before explaining the present invention, the background to the idea of the present invention will be described first.
上述したように、チタン酸リチウムは、炭素材料に比べて導電性が低く容量も小さい。一方、チタン酸リチウム中のリチウムイオンの拡散速度は、炭素材料中のリチウムイオンの拡散速度よりも大きいという特性がある。 As described above, lithium titanate has a lower conductivity and a smaller capacity than a carbon material. On the other hand, the diffusion rate of lithium ions in lithium titanate is higher than the diffusion rate of lithium ions in the carbon material.
従って、炭素材料からなる活物質に、チタン酸リチウムを被覆した構造の負極は、リチウムイオン二次電池を高出力化したときに、より効率よくリチウムを負極活物質層全体に供給することができるため、炭素材料を含む活物質層上に、リチウムが析出するのを抑制する効果が期待できる。これにより、高出力化を図ったリチウムイオン二次電池において、リチウム析出に伴う内部短絡等の発生を効果的に防止することが可能となる。 Therefore, a negative electrode having a structure in which an active material made of a carbon material is coated with lithium titanate can supply lithium to the entire negative electrode active material layer more efficiently when the output of the lithium ion secondary battery is increased. Therefore, an effect of suppressing the precipitation of lithium on the active material layer containing the carbon material can be expected. This makes it possible to effectively prevent the occurrence of an internal short circuit or the like due to lithium deposition in a lithium ion secondary battery with high output.
一方、チタン酸リチウムは、炭素材料に比べて、導電性が低く、容量も小さいため、炭素材料を含む活物質層の容量低下を抑えるためには、チタン酸リチウムによる被覆量をできるだけ薄く形成する必要がある。 On the other hand, lithium titanate has a lower conductivity and a smaller capacity than carbon materials. Therefore, in order to suppress a decrease in capacity of an active material layer containing a carbon material, a coating amount with lithium titanate is formed as thin as possible. There is a need.
しかしながら、被覆層を薄膜化した場合、炭素材料からなる活物質層のみが近接し、チタン酸リチウムによる道筋が途切れてしまうとリチウムの活物質層全体への供給が遅延し、リチウムが析出するおそれがあり、特に、電池を高出力化した場合、安全性の低下や、サイクル特性の低下を招くおそれがある。 However, when the coating layer is thinned, if only the active material layer made of the carbon material is in close proximity and the route of lithium titanate is interrupted, the supply of lithium to the entire active material layer may be delayed and lithium may be deposited. In particular, when the output of the battery is increased, there is a possibility that the safety and the cycle characteristics may be deteriorated.
そこで本発明者等は、チタン酸リチウムを含む負極構造において、被覆層の最適化を検討していたところ、チタン酸リチウムが炭素材料とのマトリックスを形成するためには、活物質層を構成する炭素材料の粒径と、チタン酸リチウムの粒径との関係を考慮しなければならないことを見出し、本発明を想到するに至った。 Therefore, the present inventors have studied optimization of the coating layer in the negative electrode structure containing lithium titanate, and in order for lithium titanate to form a matrix with a carbon material, an active material layer is formed. It has been found that the relationship between the particle size of the carbon material and the particle size of lithium titanate must be taken into consideration, and the present invention has been conceived.
本発明に係るリチウムイオン二次電池用負極は、集電体と、集電体の上に形成された活物質を含む層からなり、活物質は、炭素材料とリチウムイオンを吸蔵・放出可能な金属酸化物とからなり、金属酸化物の平均粒径は、炭素材料の平均粒径の１／１０以下であり、炭素材料の表面の少なくとも一部が金属酸化物で被覆されており、金属酸化物の炭素材料に対する被覆率が３０％〜７０％であることを特徴とし、被被覆材である炭素材料粒子径に対して十分に小さい粒子径の金属酸化物で被覆することにより、被覆材である金属酸化物の量を少なくすることが出来る。金属酸化物は電池の作動電圧の設定範囲次第では活物
質として機能しないため、その量を少なくすることで電池容量を低下させることなく電池出力を向上させるとともに、サイクル特性を高めることができる。
A negative electrode for a lithium ion secondary battery according to the present invention comprises a current collector and a layer containing an active material formed on the current collector, and the active material can occlude and release a carbon material and lithium ions. The metal oxide has an average particle size that is 1/10 or less of the average particle size of the carbon material, and at least a part of the surface of the carbon material is coated with the metal oxide. The covering ratio of the carbon material to the material is 30% to 70%, and the covering material is coated with a metal oxide having a particle diameter sufficiently smaller than the particle diameter of the carbon material to be coated. The amount of a certain metal oxide can be reduced. Since the metal oxide does not function as an active material depending on the setting range of the operating voltage of the battery, the battery output can be improved and the cycle characteristics can be improved without decreasing the battery capacity by reducing the amount of the metal oxide.
また、金属酸化物がチタン酸リチウムであると、リチウムを吸蔵・放出可能なので好ましい。 Further, it is preferable that the metal oxide is lithium titanate because lithium can be occluded / released.
また、金属酸化物の平均粒径が１μｍ以上であると、電解液との反応による副生ガスの発生を抑制するので好ましい。 Further, it is preferable that the average particle diameter of the metal oxide is 1 μm or more because generation of by-product gas due to reaction with the electrolytic solution is suppressed.
また、金属酸化物が活物質中に１０ｗｔ％以上、３０ｗｔ％以下含まれると、炭素材料を均一に被覆することができ、かつ電池容量を低下させることがないので好ましい。 Further, it is preferable that the metal oxide is contained in the active material in an amount of 10 wt% or more and 30 wt% or less because the carbon material can be uniformly coated and the battery capacity is not reduced.
さらに、炭素材料が黒鉛であると、リチウムを吸蔵・放出可能なので好ましい。 Further, it is preferable that the carbon material is graphite because lithium can be occluded / released.
以下、本発明の実施形態を図面に基づいて詳細に説明する。なお、本発明は、以下の実施形態に限定されるものではない。また、本発明の効果を奏する範囲を逸脱しない範囲で、適宜変更は可能である。さらに、他の実施形態との組み合わせも可能である。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the following embodiment. Moreover, it can change suitably in the range which does not deviate from the range which has the effect of this invention. Furthermore, combinations with other embodiments are possible.
図１は、本発明の一実施形態におけるリチウムイオン二次電池用負極の構成を示した断面図である。 FIG. 1 is a cross-sectional view illustrating a configuration of a negative electrode for a lithium ion secondary battery according to an embodiment of the present invention.
図１に示すように、負極２は、集電体１０と、集電体１０の上に形成された活物質を含む活物質層１１を備えている。 As shown in FIG. 1, the negative electrode 2 includes a current collector 10 and an active material layer 11 including an active material formed on the current collector 10.
ここで、活物質層１１に含まれる活物質は炭素材料からなり、例えば、黒鉛、カーボンブラック、アセチレンブラック、炭素繊維等が挙げられる。また、保護層１２に含まれる金属酸化物は、例えば、チタン酸リチウムの他、酸化モリブデン等が挙げられる。 Here, the active material contained in the active material layer 11 is made of a carbon material, and examples thereof include graphite, carbon black, acetylene black, and carbon fiber. Examples of the metal oxide included in the protective layer 12 include molybdenum oxide in addition to lithium titanate.
なお、活物質層１１には、所定量の導電剤及び結着剤が含まれていてもよい。導電剤としては、黒鉛等の炭素材料が挙げられる。結着剤としては、ポリフッ化ビニリデン（ＰＶＤＦ）、フッ素系ゴム、スチレンブタジエンゴム（ＳＢＲ）、ニトリルブタジエンゴム（ＮＢＲ）、アクリルゴム（ＡＣＭ）等が挙げられる。 The active material layer 11 may contain a predetermined amount of a conductive agent and a binder. Examples of the conductive agent include carbon materials such as graphite. Examples of the binder include polyvinylidene fluoride (PVDF), fluorine-based rubber, styrene butadiene rubber (SBR), nitrile butadiene rubber (NBR), acrylic rubber (ACM), and the like.
また、集電体１０は、例えば、銅箔または銅合金箔を用いることができる。 Moreover, the collector 10 can use copper foil or copper alloy foil, for example.
図２は、本実施形態における負極を用いたリチウムイオン二次電池の構成を示した断面図である。 FIG. 2 is a cross-sectional view showing a configuration of a lithium ion secondary battery using the negative electrode in the present embodiment.
図２に示すように、正極１と負極２とがセパレータ３を介して捲回された電極群４が、非水電解液（不図示）とともに、電池ケース７に収容されている。正極１は、正極リード５を介して正極端子を兼ねる封口体８に接合され、負極２は、負極リード６を介して負極端子を兼ねる電池ケース７の底部に接合されている。そして、電池ケース７の開口部は、ガスケット９を介して、封口体８で封口されている。 As shown in FIG. 2, an electrode group 4 in which a positive electrode 1 and a negative electrode 2 are wound through a separator 3 is housed in a battery case 7 together with a non-aqueous electrolyte (not shown). The positive electrode 1 is joined to a sealing body 8 that also serves as a positive electrode terminal via a positive electrode lead 5, and the negative electrode 2 is joined to the bottom of a battery case 7 that also serves as a negative electrode terminal via a negative electrode lead 6. The opening of the battery case 7 is sealed with a sealing body 8 via a gasket 9.
本実施形態において、負極２以外のリチウムイオン二次電池１００を構成する他の構成要素については、特に制限はなく、通常使用される部材等を用いることができる。 In this embodiment, there are no particular limitations on the other components constituting the lithium ion secondary battery 100 other than the negative electrode 2, and members that are normally used can be used.
次に、図３、図４および図５を参照しながら、金属酸化物の、炭素材料への被覆率との関係を説明する。 Next, the relationship between the coverage of the metal oxide on the carbon material will be described with reference to FIGS. 3, 4, and 5.
ここで、「平均粒径」とは、粒子の粒度分布において、累積体積が５０％となる粒径（Ｄ５０）を意味する。なお、粒子の粒度分布は、例えば、レーザー回折式の粒度分布測定装置によって測定することができる。 Here, the “average particle size” means a particle size (D50) at which the cumulative volume is 50% in the particle size distribution of the particles. The particle size distribution of the particles can be measured by, for example, a laser diffraction type particle size distribution measuring apparatus.
図３、図４および図５は、活物質層を構成する炭素材料の配列と、金属酸化物の配列を模式的に示した断面図である。なお、炭素材料と金属酸化物の粒子は、平均粒径の大きさを用いて表示している。 3, 4 and 5 are cross-sectional views schematically showing the arrangement of carbon materials and the arrangement of metal oxides constituting the active material layer. In addition, the particle | grains of a carbon material and a metal oxide are displayed using the magnitude | size of an average particle diameter.
図３に示すように、平均粒径Ｄ２の炭素材料２１には平均粒径Ｄ１の金属酸化物２０が、その表面を埋めるように配列して、被覆層が形成される。 As shown in FIG. 3, the average particle diameter D 2 of an average particle diameter D 1 of the metal oxide 20 in the carbon material 21, it is arranged so as to fill the surface coating layer is formed.
ここで、被覆層５０％とすると、炭素材料２１の表面に、金属酸化物２０がその断面の投影面積として、半分の被覆層が形成されることを想定した場合であり、図３に示すように、隣接する炭素材料２１の各々に金属酸化物２０が５０％の被覆層を形成しておれば、炭素材料２１上に、金属酸化物２０が連続して形成することができる。 Here, assuming that the covering layer is 50%, it is assumed that a half covering layer is formed on the surface of the carbon material 21 as the projected area of the cross section of the metal oxide 20, as shown in FIG. In addition, if a 50% coating layer of the metal oxide 20 is formed on each of the adjacent carbon materials 21, the metal oxide 20 can be continuously formed on the carbon material 21.
しかし、図４に示すように、金属酸化物２０の炭素材料２１への被覆率が３０％以下に小さくなれば、隣接する炭素材料２１上の、金属酸化物２０が欠損する可能性が高く、活物質層１１内でのリチウムの移動が抑制される。 However, as shown in FIG. 4, if the coverage of the metal oxide 20 on the carbon material 21 is reduced to 30% or less, the metal oxide 20 on the adjacent carbon material 21 is highly likely to be lost, The movement of lithium in the active material layer 11 is suppressed.
同様に、図５に示すように、金属酸化物２０の炭素材料２１への被覆率が７０％以下に大きくなれば、隣接する炭素材料２１上の、金属酸化物２０が過剰に重なり合うために、炭素材料２１間の抵抗層となる。 Similarly, as shown in FIG. 5, if the coverage of the metal oxide 20 on the carbon material 21 is increased to 70% or less, the metal oxide 20 on the adjacent carbon material 21 is excessively overlapped. It becomes a resistance layer between the carbon materials 21.
以上の考察から、炭素材料を含む活物質層１１において、金属酸化物を含む負極２の構造において、金属酸化物２０の炭素材料２１に対する被覆率と、その被覆率に関与する金属酸化物２０の平均粒径Ｄ１と、活物質層１１を構成する炭素材料２１の平均粒径Ｄ２を考慮しなければならない。 From the above consideration, in the active material layer 11 including the carbon material, in the structure of the negative electrode 2 including the metal oxide, the coverage of the metal oxide 20 with respect to the carbon material 21 and the metal oxide 20 involved in the coverage are as follows. the average particle diameter D 1, must be considered an average particle diameter D 2 of the carbon material 21 which constitutes the active material layer 11.
そこで、このような定性的な示唆に基づき、図１に示したような負極２を実際に作製し、上記の各パラメータとの関係を定量的に評価した。 Therefore, based on such qualitative suggestions, the negative electrode 2 as shown in FIG. 1 was actually produced, and the relationship with each of the above parameters was quantitatively evaluated.
表１は、その結果を示した表である。ここで、金属酸化物２０は、チタン酸リチウム（ＬｉｘＴｉｙＯｚ：ＬＴＯ）を使用し、炭素材料２１は、黒鉛を使用した。なお、リチウムイオン二次電池の正極活物質は、ニッケル酸リチウムを使用した。 Table 1 shows the results. Here, the metal oxide 20 used lithium titanate (LixTiyOz: LTO), and the carbon material 21 used graphite. Note that lithium nickelate was used as the positive electrode active material of the lithium ion secondary battery.
表１に示した電池１〜６では、黒鉛の平均粒径Ｄ２を２１〜１７μｍ、ＬＴＯの平均粒径Ｄ１を１〜２μｍ、金属酸化物の炭素材料に対する被覆率を３０〜７０％の範囲内で作製した負極をそれぞれ使用した。 In the batteries 1 to 6 shown in Table 1, the average particle diameter D2 of graphite is 21 to 17 [mu] m, the average particle diameter D1 of LTO is 1 to 2 [ mu] m, and the coverage of the metal oxide on the carbon material is 30 to 70%. Each negative electrode produced within the range was used.
表１の被覆率は、負極２の断面を電子顕微鏡写真で撮影し、炭素材料と金属酸化物の粒子径と被覆されている個数から計算で求めたものである。 The coverage shown in Table 1 was obtained by calculating from the particle diameters of the carbon material and the metal oxide and the number of the coated materials by taking a cross-section of the negative electrode 2 with an electron micrograph.
表１に示すように、電池１〜６に用いた負極では、ＬＴＯの平均粒径Ｄ１は黒鉛の平均粒径Ｄ２の１／１０以下であり、被覆率を３０〜７０％にするには、ＬＴＯの比率は１０〜３０ｗｔ％となり、高い容量とサイクル特性を両立することができた。 As shown in Table 1, the negative electrode used in the battery 1-6, the average particle diameter D 1 of the LTO is less than 1/10 of the average particle diameter D 2 of graphite, to the coverage in the 30% to 70% The ratio of LTO was 10-30 wt%, and both high capacity and cycle characteristics could be achieved.
電池７では、ＬＴＯの平均粒径Ｄ１を、黒鉛の平均粒径Ｄ２の１／２０以下にしたため、ＬＴＯの比率は２０〜３０％にすることで電池容量は高い容量を維持したが、被覆率が１００％以上まで増加したために隣接する炭素材料の抵抗層となり、サイクル特性が劣化した。 In the battery 7, the average particle diameter D 1 of the LTO, for you 1/20 of the average particle diameter D 2 of the graphite, the battery capacity by a ratio of LTO is that 20 to 30 percent has been maintaining a high capacity, Since the coverage increased to 100% or more, it became a resistance layer of an adjacent carbon material, and the cycle characteristics deteriorated.
電池９でも同様に被覆率が１００％以上まで増加したために、サイクル特性が劣化した。 Similarly, in the battery 9, since the coverage increased to 100% or more, the cycle characteristics deteriorated.
電池８では、ＬＴＯ比率を１０％以下、被覆率を２０％以下に低減したために、容量低下は見られなかったものの、ＬＴＯによるマトリックスの効果が発揮されず、サイクル特性が劣化した、またこの電池を分解して観察したところ、負極表面へのリチウム析出が観察された。 In Battery 8, since the LTO ratio was reduced to 10% or less and the coverage was reduced to 20% or less, the capacity was not reduced, but the matrix effect by LTO was not exhibited, and the cycle characteristics were deteriorated. When lithium was decomposed and observed, lithium deposition on the negative electrode surface was observed.
電池１０では、ＬＴＯの平均粒径Ｄ１を、黒鉛の平均粒径Ｄ２の１／４にしたため、ＬＴＯの被覆率を５０％にするには比率が５０％必要となり容量が低下した。 In the battery 10, the average particle diameter D 1 of the LTO, because of the 1/4 of the average particle diameter D 2 of the graphite, the coverage of LTO To 50% ratio is decreased capacity required 50%.
この結果から、ＬＴＯの平均粒径Ｄ１を、黒鉛の平均粒径Ｄ２の１／１０以下に、被覆率を３０〜７０％にすることによって、活物質層１１での金属酸化物２０が炭素材料２１を欠損することも過剰な抵抗層を作ることもなく効果的なマトリックスを構成して、ＬＴＯが活物質として機能し、かつ、リチウムイオンの拡散速度が大きいことから、電池の高出力、高容量化も同時に図ることができる。これにより、電池の高出力、高容量特性を低下させることのないリチウムイオン二次電池を実現することができる。 From this result, the average particle diameter D 1 of the LTO, 1/10 in the following average particle diameter D 2 of the graphite, by the coverage to 30% to 70%, the metal oxide 20 in the active material layer 11 is Since the LTO functions as an active material without losing the carbon material 21 or forming an excessive resistance layer, and the lithium ion diffusion rate is high, the high output of the battery The capacity can be increased at the same time. Thereby, it is possible to realize a lithium ion secondary battery that does not degrade the high output and high capacity characteristics of the battery.
なお、電解液との副反応によるガス発生抑制の観点から、ＬＴＯの平均粒径は１μｍ以上が好ましい。 From the viewpoint of suppressing gas generation due to side reaction with the electrolytic solution, the average particle size of LTO is preferably 1 μm or more.
ところで、図３に示した模式図では、金属酸化物２０及び炭素材料２１を、平均粒径（Ｄ５０）の大きさを用いて表示したが、実際には、それぞれの粒径は、一定の粒度分布をもって分散している。もし、粒度分布が広がっていると、粒子径の大きな金属酸化物２０が存在することにより、被覆率が低下するおそれがある。同様に、粒子径の大きな炭素材料２１が存在することにより、被覆率が低下するおそれがあるため、ＬＴＯの９０％積算粒子径（Ｄ９０）が、４μｍ以下であることが好ましく、被覆率の低下のない、電池特性の高い電池を得ることができる。同じく、黒鉛の９０％積算粒子径（Ｄ９０）が、４０μｍ以下であれば、被覆率の低下のない、電池特性の高い電池を得ることができる。 By the way, in the schematic diagram shown in FIG. 3, the metal oxide 20 and the carbon material 21 are displayed using the average particle size (D50), but in actuality, each particle size is a constant particle size. Distributed with distribution. If the particle size distribution is wide, the metal oxide 20 having a large particle size is present, which may reduce the coverage. Similarly, since the coverage may be reduced due to the presence of the carbon material 21 having a large particle size, the 90% cumulative particle size (D90) of LTO is preferably 4 μm or less, and the coverage is reduced. A battery having high battery characteristics can be obtained. Similarly, when the 90% cumulative particle diameter (D90) of graphite is 40 μm or less, a battery having high battery characteristics without a reduction in coverage can be obtained.
本実施形態における負極２は、通常用いる方法、例えば、ダイコート法、あるいはグラビアコート法等により、集電体１０上に、活物質層１１を塗布、乾燥して製造することができる。 The negative electrode 2 in this embodiment can be manufactured by applying and drying the active material layer 11 on the current collector 10 by a commonly used method such as a die coating method or a gravure coating method.
以上、本発明を好適な実施形態により説明してきたが、こうした記述は限定事項ではなく、もちろん、種々の改変が可能である。例えば、上記実施形態においては、負極２は、集電体１０の片面に活物質層１１及び保護層１２を形成したが、集電体１０の両面に形成してもよい。 As mentioned above, although this invention was demonstrated by suitable embodiment, such description is not a limitation matter and of course various modifications are possible. For example, although the active material layer 11 and the protective layer 12 are formed on one surface of the current collector 10 in the above embodiment, the negative electrode 2 may be formed on both surfaces of the current collector 10.
本発明は、自動車、電動バイク又は電動遊具等の駆動用電源として有用である。 The present invention is useful as a power source for driving automobiles, electric motorcycles, electric playground equipment and the like.
１ 正極
２ 負極
３ セパレータ
４ 電極群
５ 正極リード
６ 負極リード
７ 電池ケース
８ 封口体
９ ガスケット
１０ 集電体
１１ 活物質層（第１の層）
１２ 保護層（第２の層）
２０ 金属酸化物（ＬＴＯ）
２１ 炭素材料（黒鉛）
１００ リチウムイオン二次電池
DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Separator 4 Electrode group 5 Positive electrode lead 6 Negative electrode lead 7 Battery case 8 Sealing body 9 Gasket 10 Current collector 11 Active material layer (1st layer)
12 Protective layer (second layer)
20 Metal oxide (LTO)
21 Carbon material (graphite)
100 Lithium ion secondary battery
Claims (6)
前記活物質は、炭素材料と金属酸化物とからなり、
前記金属酸化物の平均粒径は、前記炭素材料の平均粒径の１／１０以下であり、
前記炭素材料の表面の少なくとも一部が前記金属酸化物で被覆されており、
前記金属酸化物の前記炭素材料に対する被覆率が３０％以上、７０％以下であるリチウムイオン二次電池用負極。 A negative electrode for a lithium ion secondary battery comprising a current collector and a layer containing an active material formed on the current collector,
The active material comprises a carbon material and a metal oxide,
The average particle diameter of the metal oxide is 1/10 or less of the average particle diameter of the carbon material,
At least part of the surface of the carbon material is coated with the metal oxide;
A negative electrode for a lithium ion secondary battery, wherein a coverage of the metal oxide with respect to the carbon material is 30% or more and 70% or less.
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| PCT/JP2012/008015 WO2013099138A1 (en) | 2011-12-28 | 2012-12-14 | Negative electrode for lithium ion secondary battery and lithium ion secondary battery having negative electrode for lithium ion secondary battery |
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| JP2018185931A (en) * | 2017-04-25 | 2018-11-22 | トヨタ自動車株式会社 | Negative electrode active material particles for lithium ion secondary battery and manufacturing method thereof |
| US20190081348A1 (en) * | 2017-09-11 | 2019-03-14 | Toyota Jidosha Kabushiki Kaisha | Negative electrode, lithium ion secondary battery, method of manufacturing negative electrode, and method of manufacturing lithium ion secondary battery |
| JP2020047387A (en) * | 2018-09-14 | 2020-03-26 | トヨタ自動車株式会社 | Negative electrode for lithium ion secondary battery |
| WO2021095719A1 (en) * | 2019-11-11 | 2021-05-20 | 昭和電工株式会社 | Composite material, manufacturing method therefor, negative electrode material for lithium ion secondary battery, and the like |
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| CN110635106A (en) * | 2019-10-23 | 2019-12-31 | 珠海格力电器股份有限公司 | Pole piece, lithium ion battery and manufacturing method of pole piece |
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| JP2004063394A (en) * | 2002-07-31 | 2004-02-26 | Sanyo Electric Co Ltd | Nonaqueous electrolyte battery |
| WO2009002053A2 (en) * | 2007-06-22 | 2008-12-31 | Lg Chem, Ltd. | Anode material of excellent conductivity and high power secondary battery employed with the same |
| JP2011090876A (en) * | 2009-10-22 | 2011-05-06 | Toyota Motor Corp | Lithium secondary battery and method of manufacturing the same |
| JP5073105B2 (en) * | 2010-06-30 | 2012-11-14 | パナソニック株式会社 | Negative electrode for non-aqueous electrolyte secondary battery, method for producing the same, and non-aqueous electrolyte secondary battery |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2018185931A (en) * | 2017-04-25 | 2018-11-22 | トヨタ自動車株式会社 | Negative electrode active material particles for lithium ion secondary battery and manufacturing method thereof |
| US10938025B2 (en) | 2017-04-25 | 2021-03-02 | Toyota Jidosha Kabushiki Kaisha | Negative electrode active material particles for lithium ion secondary battery and method of producing the same |
| US20190081348A1 (en) * | 2017-09-11 | 2019-03-14 | Toyota Jidosha Kabushiki Kaisha | Negative electrode, lithium ion secondary battery, method of manufacturing negative electrode, and method of manufacturing lithium ion secondary battery |
| US10818962B2 (en) * | 2017-09-11 | 2020-10-27 | Toyota Jidosha Kabushiki Kaisha | Negative electrode, lithium ion secondary battery, method of manufacturing negative electrode, and method of manufacturing lithium ion secondary battery |
| JP2020047387A (en) * | 2018-09-14 | 2020-03-26 | トヨタ自動車株式会社 | Negative electrode for lithium ion secondary battery |
| WO2021095719A1 (en) * | 2019-11-11 | 2021-05-20 | 昭和電工株式会社 | Composite material, manufacturing method therefor, negative electrode material for lithium ion secondary battery, and the like |
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