JP2020145064A - battery - Google Patents

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JP2020145064A
JP2020145064A JP2019040607A JP2019040607A JP2020145064A JP 2020145064 A JP2020145064 A JP 2020145064A JP 2019040607 A JP2019040607 A JP 2019040607A JP 2019040607 A JP2019040607 A JP 2019040607A JP 2020145064 A JP2020145064 A JP 2020145064A
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negative electrode
active material
electrode active
material layer
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JP2020145064A5 (en
JP7125235B2 (en
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克英 菊地
Katsuhide Kikuchi
克英 菊地
哲也 堀
Tetsuya Hori
哲也 堀
高橋　賢司
Kenji Takahashi
賢司 高橋
亮 金田
Akira Kaneda
亮 金田
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Toyota Motor Corp
Soken Inc
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Soken Inc
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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
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Abstract

To suppress high-rate deterioration in a battery containing a laminated electrode body.SOLUTION: A negative electrode active material layer 122 includes a first region R1 and a second region R2 in a plan view. The second region R2 is arranged along the peripheral edge of the negative electrode active material layer 122. The first region R1 is surrounded by the second region R2. The negative electrode active material contained in the second region R2 has a larger expansion/contraction rate during charging/discharging than that of the negative electrode active material contained in the first region R1.SELECTED DRAWING: Figure 3

Description

本開示は電池に関する。 The present disclosure relates to batteries.

特開２０１２−２３０８３７号公報（特許文献１）は、電池の外部から電極体を部分的に押圧することを開示している。 Japanese Unexamined Patent Publication No. 2012-23038 (Patent Document 1) discloses that the electrode body is partially pressed from the outside of the battery.

特開２０１２−２３０８３７号公報Japanese Unexamined Patent Publication No. 2012-230837

図１は従来の電池構造を示す第１断面概念図である。
容器９０は電極体５０および電解液６０を収納している。電極体５０は正極シート１０、セパレータシート３０および負極シート２０を含む。負極シート２０は負極活物質層２２を含む。負極活物質層２２は例えば負極集電体２１の表面に形成されている。 FIG. 1 is a conceptual diagram of a first cross section showing a conventional battery structure.
The container 90 houses the electrode body 50 and the electrolytic solution 60. The electrode body 50 includes a positive electrode sheet 10, a separator sheet 30, and a negative electrode sheet 20. The negative electrode sheet 20 includes a negative electrode active material layer 22. The negative electrode active material layer 22 is formed on the surface of the negative electrode current collector 21, for example.

電解液６０の一部は電極体５０に含浸されている。以下、電極体５０に含浸されている電解液が「含浸液」とも記される。電解液６０の残部は、電極体５０の外部に貯留している。以下、電極体５０の外部に貯留している電解液が「余剰液」とも記される。 A part of the electrolytic solution 60 is impregnated in the electrode body 50. Hereinafter, the electrolytic solution impregnated in the electrode body 50 is also referred to as “impregnated solution”. The rest of the electrolytic solution 60 is stored outside the electrode body 50. Hereinafter, the electrolytic solution stored outside the electrode body 50 is also referred to as “surplus liquid”.

図１には充電時の状態が示されている。充電時、負極活物質は膨張する。負極活物質の膨張により、電解液６０が負極活物質層２２から押し出され、電解液６０が電極体５０から排出されることがある。 FIG. 1 shows the state at the time of charging. During charging, the negative electrode active material expands. Due to the expansion of the negative electrode active material, the electrolytic solution 60 may be pushed out from the negative electrode active material layer 22, and the electrolytic solution 60 may be discharged from the electrode body 50.

なお図１、図２、図４および図５では、負極合材層２０，１２０内における電解液６０の移動を表す矢印が、便宜上セパレータシート３０、１３０内に描かれている。 In FIGS. 1, 2, 4, and 5, arrows indicating the movement of the electrolytic solution 60 in the negative electrode mixture layers 20 and 120 are drawn in the separator sheets 30 and 130 for convenience.

図２は従来の電池構造を示す第２断面概念図である。
図２には放電時の状態が示されている。放電時、負極活物質は収縮する。負極活物質の収縮により、余剰液が負極活物質層２２に吸入されることもある。 FIG. 2 is a second cross-sectional conceptual diagram showing a conventional battery structure.
FIG. 2 shows the state at the time of discharge. At the time of discharge, the negative electrode active material shrinks. Due to the shrinkage of the negative electrode active material, excess liquid may be sucked into the negative electrode active material layer 22.

含浸液および余剰液は、当初、略均一な濃度を有している。しかしハイレートで充放電が実施されると、含浸液の濃度に偏りが生じることがある。濃度に偏りが生じた含浸液が、電極体５０から排出されることにより、含浸液と余剰液との間に濃度差が生じると考えられる。さらにハイレートで充放電が繰り返されることにより、含浸液と余剰液との濃度差が徐々に大きくなると考えられる。電池１の内部抵抗は含浸液の濃度に依存する。含浸液の濃度が変化することにより、電池１の内部抵抗が増加すると考えられる。内部抵抗の増加により、使用可能な電池容量が減少すると考えられる。本明細書では、かかる劣化モードが「ハイレート劣化」と称される。 The impregnating liquid and the surplus liquid initially have a substantially uniform concentration. However, when charging and discharging are performed at a high rate, the concentration of the impregnating liquid may be biased. It is considered that a concentration difference occurs between the impregnating liquid and the surplus liquid when the impregnating liquid having a biased concentration is discharged from the electrode body 50. It is considered that the concentration difference between the impregnating liquid and the surplus liquid gradually increases as the charging and discharging are repeated at a high rate. The internal resistance of the battery 1 depends on the concentration of the impregnating liquid. It is considered that the internal resistance of the battery 1 increases as the concentration of the impregnating liquid changes. It is considered that the usable battery capacity decreases due to the increase in internal resistance. In the present specification, such a deterioration mode is referred to as "high rate deterioration".

特許文献１の電極体５０は捲回型である。捲回型の電極体５０では、電解液６０の排出方向が一方向であると考えてよい。すなわち電解液６０は捲回軸方向（図１のｘ軸方向）に沿って移動し、捲回軸方向の両端から排出されると考えられる。特許文献１では、電極体５０において捲回軸方向の両端が押圧されるように、電池１の外部にスペーサ８０が配置されている。これにより電解液６０の排出経路の出口部分が塞がれると考えられる。したがって電解液６０の排出が抑制され、ハイレート劣化が抑制されることが期待される。 The electrode body 50 of Patent Document 1 is a winding type. In the winding type electrode body 50, it may be considered that the discharge direction of the electrolytic solution 60 is one direction. That is, it is considered that the electrolytic solution 60 moves along the winding axis direction (x-axis direction in FIG. 1) and is discharged from both ends in the winding axis direction. In Patent Document 1, spacers 80 are arranged outside the battery 1 so that both ends of the electrode body 50 in the winding axis direction are pressed. It is considered that this blocks the outlet portion of the discharge path of the electrolytic solution 60. Therefore, it is expected that the discharge of the electrolytic solution 60 is suppressed and the high rate deterioration is suppressed.

しかし積層型の電極体５０では、電解液６０の排出方向が一方向ではない。電解液６０は、例えば図１のｚ軸方向の両端からも排出され得る。電解液６０の排出経路を塞ぐために、ｘｚ平面において、電極体１５０の全周が押圧されるようにスペーサ８０を配置することが考えられる。ただし電極体１５０の全周が押圧されるようにスペーサ８０を配置することにより、例えば電池１の冷却が阻害される等の不都合が想定される。 However, in the laminated electrode body 50, the discharge direction of the electrolytic solution 60 is not one direction. The electrolytic solution 60 can also be discharged from both ends in the z-axis direction of FIG. 1, for example. In order to block the discharge path of the electrolytic solution 60, it is conceivable to arrange the spacer 80 so that the entire circumference of the electrode body 150 is pressed in the xz plane. However, by arranging the spacer 80 so that the entire circumference of the electrode body 150 is pressed, inconveniences such as hindering the cooling of the battery 1 are assumed.

本開示の目的は、積層型の電極体を含む電池において、ハイレート劣化を抑制することである。 An object of the present disclosure is to suppress high-rate deterioration in a battery including a laminated electrode body.

以下、本開示の技術的構成および作用効果が説明される。ただし本開示の作用メカニズムは推定を含んでいる。作用メカニズムの正否により特許請求の範囲が限定されるべきではない。 Hereinafter, the technical configuration and the action and effect of the present disclosure will be described. However, the mechanism of action of the present disclosure includes estimation. The scope of claims should not be limited by the correctness of the mechanism of action.

〔１〕電池は容器、電極体および電解液を含む。容器は電極体および電解液を収納している。電解液の一部は電極体に含浸されている。電極体は積層型である。電極体は正極シート、セパレータシートおよび負極シートを含む。セパレータシートは正極シートと負極シートとの間に配置されている。負極シートは負極活物質層を含む。
平面視において、負極活物質層は第１領域および第２領域を含む。第２領域は負極活物質層の周縁に沿って配置されている。第１領域は第２領域に取り囲まれている。第２領域に含まれる負極活物質は、第１領域に含まれる負極活物質に比して、充放電時の膨張収縮率が大きい。 [1] The battery includes a container, an electrode body, and an electrolytic solution. The container contains the electrode body and the electrolytic solution. A part of the electrolytic solution is impregnated in the electrode body. The electrode body is a laminated type. The electrode body includes a positive electrode sheet, a separator sheet and a negative electrode sheet. The separator sheet is arranged between the positive electrode sheet and the negative electrode sheet. The negative electrode sheet includes a negative electrode active material layer.
In plan view, the negative electrode active material layer includes a first region and a second region. The second region is arranged along the periphery of the negative electrode active material layer. The first region is surrounded by the second region. The negative electrode active material contained in the second region has a larger expansion / contraction rate during charging / discharging than the negative electrode active material contained in the first region.

図３は本開示の負極活物質層を示す平面概念図である。
負極活物質層１２２は平面視において第１領域Ｒ１および第２領域Ｒ２を含む。第２領域Ｒ２は負極活物質層１２２の周縁に沿って配置されている。第１領域Ｒ１は第２領域Ｒ２に取り囲まれている。第２領域Ｒ２に含まれる負極活物質は、第１領域Ｒ１に含まれる負極活物質に比して、充放電時の膨張収縮率が大きい。 FIG. 3 is a plan conceptual diagram showing the negative electrode active material layer of the present disclosure.
The negative electrode active material layer 122 includes a first region R1 and a second region R2 in a plan view. The second region R2 is arranged along the peripheral edge of the negative electrode active material layer 122. The first region R1 is surrounded by the second region R2. The negative electrode active material contained in the second region R2 has a larger expansion / contraction rate during charging / discharging than the negative electrode active material contained in the first region R1.

本明細書の「平面視」は、負極活物質層１２２の法線方向（図３等のｙ軸方向）から、負極活物質層１２２を視ることを示す。 “Plan view” in the present specification indicates that the negative electrode active material layer 122 is viewed from the normal direction (y-axis direction in FIG. 3 and the like) of the negative electrode active material layer 122.

本明細書の「充放電時の膨張収縮率」は、ＳＯＣ（ｓｔａｔｅ ｏｆ ｃｈａｒｇｅ）が０％である時の体積に対する、ＳＯＣが１００％である時の体積の比を示す。 The “expansion / contraction rate at the time of charge / discharge” in the present specification indicates the ratio of the volume when the SOC (state of charge) is 0% to the volume when the SOC is 100%.

図４は本開示の電池構造を示す第１断面概念図である。
図４には充電時の状態が示されている。本開示の電池１００では、充電時、第２領域Ｒ２に含まれる負極活物質が、第１領域Ｒ１に含まれる負極活物質に比して大きく膨張すると考えられる。その結果、第２領域Ｒ２は、第１領域Ｒ１に比して密に詰まると考えられる。これにより第２領域Ｒ２の内部の空隙が減少し、含浸液の排出経路の出口部分が塞がれると考えられる。すなわち充電時、含浸液の排出が抑制されると考えられる。 FIG. 4 is a conceptual diagram of a first cross section showing the battery structure of the present disclosure.
FIG. 4 shows the state at the time of charging. In the battery 100 of the present disclosure, it is considered that the negative electrode active material contained in the second region R2 expands significantly as compared with the negative electrode active material contained in the first region R1 during charging. As a result, the second region R2 is considered to be more densely packed than the first region R1. It is considered that this reduces the voids inside the second region R2 and closes the outlet portion of the impregnating liquid discharge path. That is, it is considered that the discharge of the impregnating liquid is suppressed during charging.

図５は本開示の電池構造を示す第２断面概念図である。
図５には放電時の状態が示されている。放電時、第２領域Ｒ２に含まれる負極活物質が大きく収縮する。これにより第２領域Ｒ２に余剰液が吸入される。本開示の電池１では、充電時に含浸液の排出が抑制されているため、第１領域Ｒ１には含浸液が潤沢に残されていると考えられる。そのため余剰液は第１領域Ｒ１まで入り込み難いと考えられる。すなわち放電時、余剰液が負極活物質層１２２の中心に向かって移動することが抑制されると考えられる。 FIG. 5 is a second cross-sectional conceptual diagram showing the battery structure of the present disclosure.
FIG. 5 shows the state at the time of discharge. At the time of discharge, the negative electrode active material contained in the second region R2 contracts significantly. As a result, the excess liquid is sucked into the second region R2. In the battery 1 of the present disclosure, since the discharge of the impregnating liquid is suppressed during charging, it is considered that the impregnating liquid is abundantly left in the first region R1. Therefore, it is considered that the surplus liquid does not easily enter the first region R1. That is, it is considered that the excess liquid is suppressed from moving toward the center of the negative electrode active material layer 122 during discharge.

以上の作用により、本開示の電池１００では、電極体１５０の内外において電解液１６０の移動量が減少することが期待される。これにより含浸液の濃度変化が小さくなることが期待される。すなわちハイレート劣化が抑制されることが期待される。 Due to the above actions, in the battery 100 of the present disclosure, it is expected that the amount of movement of the electrolytic solution 160 inside and outside the electrode body 150 is reduced. This is expected to reduce the change in the concentration of the impregnating solution. That is, it is expected that high-rate deterioration is suppressed.

〔２〕第２領域に含まれる負極活物質が珪素材料を含んでおり、かつ第１領域に含まれる負極活物質が黒鉛材料を含んでいてもよい。 [2] The negative electrode active material contained in the second region may contain a silicon material, and the negative electrode active material contained in the first region may contain a graphite material.

珪素材料は黒鉛材料に比して充放電時の膨張収縮率が大きいと考えられる。 It is considered that the silicon material has a larger expansion / contraction rate during charging / discharging than the graphite material.

〔３〕第２領域における負極活物質の質量比率は、第１領域における負極活物質の質量比率よりも大きくてもよい。 [3] The mass ratio of the negative electrode active material in the second region may be larger than the mass ratio of the negative electrode active material in the first region.

これにより充電時、第２領域Ｒ２の内部の空隙が、第１領域Ｒ１の内部の空隙に比して、いっそう減少すると考えられる。その結果、電解液１６０の移動量が減少し、ハイレート劣化が抑制されることが期待される。 As a result, it is considered that the air gap inside the second region R2 is further reduced when charging as compared with the air gap inside the first region R1. As a result, it is expected that the amount of movement of the electrolytic solution 160 is reduced and high-rate deterioration is suppressed.

〔４〕第２領域に含まれる負極活物質は、第１領域に含まれる負極活物質に比して、熱膨張率が大きくてもよい。 [4] The negative electrode active material contained in the second region may have a larger coefficient of thermal expansion than the negative electrode active material contained in the first region.

ハイレートで充放電が実施されると、ジュール熱が発生すると考えられる。ジュール熱により、負極活物質層２２の温度が上昇すると考えられる。第２領域Ｒ２に含まれる負極活物質の熱膨張率が大きい場合、負極活物質の熱膨張により第２領域Ｒ２が密に詰まると考えられる。その結果、電解液１６０の移動量が減少し、ハイレート劣化が抑制されることが期待される。 When charging and discharging are performed at a high rate, Joule heat is considered to be generated. It is considered that the temperature of the negative electrode active material layer 22 rises due to Joule heat. When the coefficient of thermal expansion of the negative electrode active material contained in the second region R2 is large, it is considered that the second region R2 is densely clogged due to the thermal expansion of the negative electrode active material. As a result, it is expected that the amount of movement of the electrolytic solution 160 is reduced and high-rate deterioration is suppressed.

〔５〕第２領域は補助材を含んでいてもよい。補助材は、第１領域に含まれる負極活物質に比して、大きい熱膨張率を有していてもよい。 [5] The second region may include an auxiliary material. The auxiliary material may have a large coefficient of thermal expansion as compared with the negative electrode active material contained in the first region.

本明細書の「補助材」は、負極活物質として機能しない材料を示す。ハイレートで充放電が実施されると、補助材の熱膨張により、第２領域Ｒ２が密に詰まると考えられる。その結果、電解液１６０の移動量が減少し、ハイレート劣化が抑制されることが期待される。 As used herein, the term "auxiliary material" refers to a material that does not function as a negative electrode active material. When charging / discharging is performed at a high rate, it is considered that the second region R2 is densely clogged due to the thermal expansion of the auxiliary material. As a result, it is expected that the amount of movement of the electrolytic solution 160 is reduced and high-rate deterioration is suppressed.

〔６〕セパレータシートが以下の構成を含んでいてもよい。
平面視においてセパレータシートが第１領域および第２領域を含む。第２領域はセパレータシートの周縁に沿って配置されている。第１領域は第２領域に取り囲まれている。第２領域は第１領域に比して熱膨張率が大きい。 [6] The separator sheet may include the following configurations.
In plan view, the separator sheet includes a first region and a second region. The second region is arranged along the peripheral edge of the separator sheet. The first region is surrounded by the second region. The second region has a larger coefficient of thermal expansion than the first region.

セパレータシートの周縁に熱膨張率が大きい領域が形成されていることによっても、電解液１６０の移動量が減少することが期待される。 It is expected that the amount of movement of the electrolytic solution 160 will also decrease due to the formation of a region having a large coefficient of thermal expansion on the periphery of the separator sheet.

図１は従来の電池構造を示す第１断面概念図である。FIG. 1 is a conceptual diagram of a first cross section showing a conventional battery structure. 図２は従来の電池構造を示す第２断面概念図である。FIG. 2 is a second cross-sectional conceptual diagram showing a conventional battery structure. 図３は本開示の負極活物質層を示す平面概念図である。FIG. 3 is a plan conceptual diagram showing the negative electrode active material layer of the present disclosure. 図４は本開示の電池構造を示す第１断面概念図である。FIG. 4 is a conceptual diagram of a first cross section showing the battery structure of the present disclosure. 図５は本開示の電池構造を示す第２断面概念図である。FIG. 5 is a second cross-sectional conceptual diagram showing the battery structure of the present disclosure. 図６はサイクル特性を示すグラフである。FIG. 6 is a graph showing cycle characteristics.

以下、本開示の実施形態（本明細書では「本実施形態」と記される）が説明される。ただし以下の説明は特許請求の範囲を限定するものではない。 Hereinafter, embodiments of the present disclosure (referred to as “the present embodiment” in the present specification) will be described. However, the following description does not limit the scope of claims.

＜電池＞
図４および図５に示されるように、電池１００は容器１９０、電極体１５０および電解液１６０を含む。容器１９０は電極体１５０および電解液１６０を収納している。容器１９０は密閉されていてもよい。容器１９０は例えば金属製等であってもよい。容器１９０は例えばアルミラミネートフィルム製のパウチ等であってもよい。 <Battery>
As shown in FIGS. 4 and 5, the battery 100 includes a container 190, an electrode body 150 and an electrolytic solution 160. The container 190 houses the electrode body 150 and the electrolytic solution 160. The container 190 may be hermetically sealed. The container 190 may be made of metal, for example. The container 190 may be, for example, a pouch made of an aluminum laminated film or the like.

＜電解液＞
電解液１６０の一部は電極体１５０に含浸されている。すなわち電解液１６０の一部は含浸液であり、残部は余剰液である。電解液１６０は溶媒および支持塩を含む。ハイレートの充放電により、例えば図４のｘｚ平面において、支持塩の濃度に偏りが生じると考えられる。溶媒は例えばカーボネート系溶媒であってもよい。支持塩は例えばＬｉＰＦ6等であってもよい。 <Electrolytic solution>
A part of the electrolytic solution 160 is impregnated in the electrode body 150. That is, a part of the electrolytic solution 160 is an impregnating solution, and the rest is a surplus solution. The electrolytic solution 160 contains a solvent and a supporting salt. It is considered that the high-rate charge / discharge causes a bias in the concentration of the supporting salt, for example, in the xz plane of FIG. The solvent may be, for example, a carbonate solvent. The supporting salt may be, for example, LiPF 6 .

＜電極体＞
電極体１５０は積層型である。電極体１５０は、正極シート１１０と負極シート１２０とが交互にそれぞれ１枚以上積層されることにより形成されている。正極シート１１０と負極シート１２０との各間にはセパレータシート１３０がそれぞれ配置されている。すなわち電極体１５０は正極シート１１０、セパレータシート１３０および負極シート１２０を含む。 <Electrode body>
The electrode body 150 is a laminated type. The electrode body 150 is formed by alternately stacking one or more positive electrode sheets 110 and one or more negative electrode sheets 120. A separator sheet 130 is arranged between each of the positive electrode sheet 110 and the negative electrode sheet 120. That is, the electrode body 150 includes a positive electrode sheet 110, a separator sheet 130, and a negative electrode sheet 120.

＜負極シート＞
負極シート１２０は負極活物質層１２２を含む。負極シート１２０は実質的に負極活物質層１２２のみからなっていてもよい。負極シート１２０は負極集電体１２１をさらに含んでいてもよい。負極集電体１２１は例えば銅箔等であってもよい。負極活物質層１２２は例えば負極集電体１２１の表面に配置されていてもよい。負極活物質層１２２は負極集電体１２１の片面のみに配置されていてもよい。負極活物質層１２２は負極集電体１２１の表裏両面に配置されていてもよい。 <Negative electrode sheet>
The negative electrode sheet 120 includes a negative electrode active material layer 122. The negative electrode sheet 120 may substantially consist of only the negative electrode active material layer 122. The negative electrode sheet 120 may further include a negative electrode current collector 121. The negative electrode current collector 121 may be, for example, a copper foil or the like. The negative electrode active material layer 122 may be arranged on the surface of the negative electrode current collector 121, for example. The negative electrode active material layer 122 may be arranged on only one side of the negative electrode current collector 121. The negative electrode active material layer 122 may be arranged on both the front and back surfaces of the negative electrode current collector 121.

負極活物質層１２２は負極活物質を含む。負極活物質層１２２は実質的に負極活物質のみからなっていてもよい。負極活物質層１２２は例えば導電材、バインダ等をさらに含んでいてもよい。負極活物質層１２２は、例えば負極活物質、導電材およびバインダを含む負極ペーストが、負極集電体１２１の表面に塗着されることにより形成されていてもよい。 The negative electrode active material layer 122 contains a negative electrode active material. The negative electrode active material layer 122 may be substantially composed of only the negative electrode active material. The negative electrode active material layer 122 may further contain, for example, a conductive material, a binder, or the like. The negative electrode active material layer 122 may be formed by, for example, applying a negative electrode paste containing a negative electrode active material, a conductive material, and a binder to the surface of the negative electrode current collector 121.

図３に示されるように、平面視において負極活物質層１２２は例えば矩形状であってもよい。平面視において負極活物質層１２２は第１領域Ｒ１および第２領域Ｒ２を含む。第２領域Ｒ２は負極活物質層１２２の周縁に沿って配置されている。第１領域Ｒ１は第２領域Ｒ２に取り囲まれている。 As shown in FIG. 3, the negative electrode active material layer 122 may have a rectangular shape, for example, in a plan view. In plan view, the negative electrode active material layer 122 includes a first region R1 and a second region R2. The second region R2 is arranged along the peripheral edge of the negative electrode active material layer 122. The first region R1 is surrounded by the second region R2.

第１領域Ｒ１と第２領域Ｒ２とは例えば下記式：
０．５≦Ｓ１／（Ｓ１＋Ｓ２）≦０．９５
の関係を満たしていてもよい。 The first region R1 and the second region R2 are, for example, the following equations:
0.5 ≤ S1 / (S1 + S2) ≤ 0.95
The relationship may be satisfied.

上記式中「Ｓ１」は第１領域Ｒ１の面積を示し、「Ｓ２」は第２領域Ｒ２の面積を示す。上記式が満たされることにより、例えば電池容量とサイクル特性とのバランスが良いことが期待される。 In the above formula, "S1" indicates the area of the first region R1 and "S2" indicates the area of the second region R2. By satisfying the above formula, it is expected that, for example, the battery capacity and the cycle characteristics are well-balanced.

第２領域Ｒ２に含まれる負極活物質は、第１領域Ｒ１に含まれる負極活物質に比して、充放電時の膨張収縮率が大きい。そのため電極体１５０の内外において電解液１６０の移動量が減少し、ハイレート劣化が抑制されることが期待される。 The negative electrode active material contained in the second region R2 has a larger expansion / contraction rate during charging / discharging than the negative electrode active material contained in the first region R1. Therefore, it is expected that the amount of movement of the electrolytic solution 160 inside and outside the electrode body 150 is reduced, and high-rate deterioration is suppressed.

図６はサイクル特性を示すグラフである。
図６の充放電サイクルはハイレートで実施されている。試料Ｎｏ．１は本実施形態に従う電池である。試料Ｎｏ．２は従来の電池である。すなわち試料Ｎｏ．２では、負極活物質層１２２内に第１領域Ｒ１および第２領域Ｒ２が形成されていない。試料Ｎｏ．２では、負極活物質層１２２が全域にわたって均一な組成を有する。図６に示されるように、試料Ｎｏ．１は試料Ｎｏ．２に比して、電池容量の保持率が高い。試料Ｎｏ．１ではハイレート劣化が抑制されているためと考えられる。 FIG. 6 is a graph showing cycle characteristics.
The charge / discharge cycle of FIG. 6 is carried out at a high rate. Sample No. Reference numeral 1 denotes a battery according to the present embodiment. Sample No. Reference numeral 2 is a conventional battery. That is, the sample No. In No. 2, the first region R1 and the second region R2 are not formed in the negative electrode active material layer 122. Sample No. In No. 2, the negative electrode active material layer 122 has a uniform composition over the entire area. As shown in FIG. 6, the sample No. 1 is sample No. Compared to 2, the battery capacity retention rate is high. Sample No. It is considered that in No. 1, high rate deterioration is suppressed.

第２領域Ｒ２に含まれる負極活物質は、例えば珪素材料を含んでいてもよい。第２領域Ｒ２に含まれる負極活物質は、実質的に珪素材料のみからなっていてもよい。本実施形態の珪素材料は、例えば珪素、酸化珪素および珪素基合金からなる群より選択される少なくとも１種を含んでいてもよい。 The negative electrode active material contained in the second region R2 may include, for example, a silicon material. The negative electrode active material contained in the second region R2 may be substantially composed of only a silicon material. The silicon material of the present embodiment may contain at least one selected from the group consisting of, for example, silicon, silicon oxide and a silicon-based alloy.

第１領域Ｒ１に含まれる負極活物質は、例えば黒鉛材料を含んでいてもよい。第１領域Ｒ１に含まれる負極活物質は、実質的に黒鉛材料のみからなっていてもよい。本実施形態の黒鉛材料は、例えば黒鉛、易黒鉛化性炭素および難黒鉛化性炭素からなる群より選択される少なくとも１種を含んでいてもよい。 The negative electrode active material contained in the first region R1 may include, for example, a graphite material. The negative electrode active material contained in the first region R1 may be substantially composed of only a graphite material. The graphite material of the present embodiment may contain at least one selected from the group consisting of, for example, graphite, graphitizable carbon and non-graphitizable carbon.

第１領域Ｒ１および第２領域Ｒ２において負極活物質を除く残部は、例えば導電材、バインダ等であってもよい。導電材は特に限定されるべきではない。導電材は例えばカーボンブラック（例えばアセチレンブラック等）、カーボンナノチューブおよび炭素繊維からなる群より選択される少なくとも１種を含んでいてもよい。バインダも特に限定されるべきではない。バインダは例えばカルボキシメチルセルロース、スチレンブタジエンゴムおよびポリアクリル酸からなる群より選択される少なくとも１種を含んでいてもよい。 The balance of the first region R1 and the second region R2 excluding the negative electrode active material may be, for example, a conductive material, a binder, or the like. The conductive material should not be particularly limited. The conductive material may contain, for example, at least one selected from the group consisting of carbon black (for example, acetylene black, etc.), carbon nanotubes, and carbon fibers. Binders should not be particularly limited either. The binder may contain at least one selected from the group consisting of, for example, carboxymethyl cellulose, styrene butadiene rubber and polyacrylic acid.

第２領域Ｒ２に含まれる負極活物質は、第１領域Ｒ１に含まれる負極活物質に比して、熱膨張率が大きくてもよい。第２領域Ｒ２に含まれる負極活物質は、例えばリチウム金属等を含んでいてもよい。第１領域Ｒ１に含まれる負極活物質は、例えば黒鉛材料等を含んでいてもよい。 The negative electrode active material contained in the second region R2 may have a larger coefficient of thermal expansion than the negative electrode active material contained in the first region R1. The negative electrode active material contained in the second region R2 may contain, for example, a lithium metal or the like. The negative electrode active material contained in the first region R1 may include, for example, a graphite material or the like.

第２領域Ｒ２は補助材を含んでいてもよい。補助材は、第１領域Ｒ１に含まれる負極活物質に比して、大きい熱膨張率を有していてもよい。補助材としては、例えばイオン伝導性高分子材料、金属材料（銅粒子等）等が考えられる。 The second region R2 may include an auxiliary material. The auxiliary material may have a large coefficient of thermal expansion as compared with the negative electrode active material contained in the first region R1. As the auxiliary material, for example, an ion conductive polymer material, a metal material (copper particles, etc.) and the like can be considered.

＜正極シート＞
正極シート１１０は正極活物質層１１２を含む。正極シート１１０は実質的に正極活物質層１１２のみからなっていてもよい。正極シート１１０は正極集電体１１１をさらに含んでいてもよい。正極集電体１１１は例えばアルミニウム箔等であってもよい。正極活物質層１１２は例えば正極集電体１１１の表面に配置されていてもよい。正極活物質層１１２は正極集電体１１１の片面のみに配置されていてもよい。正極活物質層１１２は正極集電体１１１の表裏両面に配置されていてもよい。 <Positive sheet>
The positive electrode sheet 110 includes a positive electrode active material layer 112. The positive electrode sheet 110 may substantially consist of only the positive electrode active material layer 112. The positive electrode sheet 110 may further include a positive electrode current collector 111. The positive electrode current collector 111 may be, for example, an aluminum foil or the like. The positive electrode active material layer 112 may be arranged on the surface of the positive electrode current collector 111, for example. The positive electrode active material layer 112 may be arranged on only one side of the positive electrode current collector 111. The positive electrode active material layer 112 may be arranged on both the front and back surfaces of the positive electrode current collector 111.

平面視において正極活物質層１１２は、例えば矩形状であってもよい。正極活物質層１１２の面積は、負極活物質層１２２の面積よりも小さい。正極活物質層１１２は正極活物質を含む。正極活物質層１１２は例えば導電材、バインダ等をさらに含んでいてもよい。正極活物質層１１２は、例えば正極活物質、導電材およびバインダを含む正極ペーストが、正極集電体１１１の表面に塗着されることにより形成されていてもよい。 In a plan view, the positive electrode active material layer 112 may have a rectangular shape, for example. The area of the positive electrode active material layer 112 is smaller than the area of the negative electrode active material layer 122. The positive electrode active material layer 112 contains a positive electrode active material. The positive electrode active material layer 112 may further contain, for example, a conductive material, a binder, and the like. The positive electrode active material layer 112 may be formed by, for example, applying a positive electrode paste containing a positive electrode active material, a conductive material, and a binder to the surface of the positive electrode current collector 111.

正極活物質は特に限定されるべきではない。正極活物質は例えばニッケルコバルトマンガン酸リチウム、ニッケルコバルトアルミン酸リチウム等を含んでいてもよい。導電材も特に限定されるべきではない。導電材は例えばカーボンブラック等を含んでいてもよい。バインダも特に限定されるべきではない。バインダは例えばポリフッ化ビニリデン等を含んでいてもよい。 The positive electrode active material should not be particularly limited. The positive electrode active material may contain, for example, lithium nickel cobalt manganate, lithium nickel cobalt aluminate, and the like. The conductive material should not be particularly limited. The conductive material may contain, for example, carbon black or the like. Binders should not be particularly limited either. The binder may contain, for example, polyvinylidene fluoride or the like.

＜セパレータシート＞
セパレータシート１３０は正極シート１１０と負極シート１２０との間に配置されている。平面視においてセパレータシート１３０は、例えば矩形状であってもよい。セパレータシート１３０は電気絶縁性である。セパレータシート１３０は多孔質である。セパレータシート１３０の内部の空隙には含浸液が含まれている。 <Separator sheet>
The separator sheet 130 is arranged between the positive electrode sheet 110 and the negative electrode sheet 120. In a plan view, the separator sheet 130 may have a rectangular shape, for example. The separator sheet 130 is electrically insulating. The separator sheet 130 is porous. The void inside the separator sheet 130 contains an impregnating liquid.

セパレータシート１３０は弾性変形しやすいことが望ましい。第２領域Ｒ２の膨張に合わせて、セパレータシート１３０が弾性変形することにより、電極シートとセパレータシート１３０との界面にある含浸液が、電極体１５０から排出されることが効率的に抑制されると考えられる。さらにセパレータシート１３０内にある含浸液が、電極体１５０から排出されることも効率的に抑制されると考えられる。その結果、ハイレート劣化の抑制が期待される。弾性変形しやすい材料としては、例えば多孔質ポリエチレンシート、多孔質ポリプロピレンシート等が考えられる。 It is desirable that the separator sheet 130 is easily elastically deformed. The separator sheet 130 is elastically deformed in accordance with the expansion of the second region R2, so that the impregnating liquid at the interface between the electrode sheet and the separator sheet 130 is efficiently suppressed from being discharged from the electrode body 150. it is conceivable that. Further, it is considered that the impregnating liquid in the separator sheet 130 is efficiently suppressed from being discharged from the electrode body 150. As a result, suppression of high-rate deterioration is expected. As a material that is easily elastically deformed, for example, a porous polyethylene sheet, a porous polypropylene sheet, or the like can be considered.

セパレータシート１３０の周縁に熱膨張率が大きい領域が設けられていてもよい。すなわち平面視においてセパレータシート１３０が第１領域および第２領域を含む。第２領域はセパレータシート１３０の周縁に沿って配置されている。第１領域は第２領域に取り囲まれている。第２領域は第１領域に比して熱膨張率が大きい。該構成によっても、電解液１６０の移動量が減少することが期待される。すなわちハイレート劣化の抑制が期待される。例えば、セパレータシート１３０の周縁に高分子材料が塗布されることにより、第１領域および第２領域が形成され得る。 A region having a large coefficient of thermal expansion may be provided on the periphery of the separator sheet 130. That is, the separator sheet 130 includes the first region and the second region in a plan view. The second region is arranged along the peripheral edge of the separator sheet 130. The first region is surrounded by the second region. The second region has a larger coefficient of thermal expansion than the first region. It is expected that the amount of movement of the electrolytic solution 160 is also reduced by this configuration. That is, it is expected to suppress high rate deterioration. For example, a first region and a second region can be formed by applying a polymer material to the periphery of the separator sheet 130.

本実施形態はすべての点で例示であって制限的なものではない。特許請求の範囲の記載によって確定される技術的範囲は、特許請求の範囲と均等の意味および範囲内でのすべての変更を含む。 This embodiment is exemplary in all respects and is not restrictive. The technical scope defined by the description of the scope of claims includes all changes within the meaning and scope equivalent to the scope of claims.

１，１００ 電池、１０，１１０ 正極シート、１１，１１１ 正極集電体、１２，１１２ 正極活物質層、２０，１２０ 負極シート、２１，１２１ 負極集電体、２２，１２２ 負極活物質層、３０，１３０ セパレータシート、５０，１５０ 電極体、６０，１６０ 電解液、８０ スペーサ、９０，１９０ 容器、Ｒ１ 第１領域、Ｒ２ 第２領域。 1,100 battery, 10,110 positive electrode sheet, 11,111 positive electrode current collector, 12,112 positive electrode active material layer, 20,120 negative electrode sheet, 21,121 negative electrode current collector, 22,122 negative electrode active material layer, 30 , 130 Separator sheet, 50,150 Electrode body, 60,160 Electrolyte, 80 spacer, 90,190 container, R1 first region, R2 second region.

Claims (1)

容器、電極体および電解液を含み、
前記容器は前記電極体および前記電解液を収納しており、
前記電解液の一部は前記電極体に含浸されており、
前記電極体は積層型であり、
前記電極体は正極シート、セパレータシートおよび負極シートを含み、
前記セパレータシートは前記正極シートと前記負極シートとの間に配置されており、
前記負極シートは負極活物質層を含み、
平面視において、
前記負極活物質層は第１領域および第２領域を含み、
前記第２領域は前記負極活物質層の周縁に沿って配置されており、
前記第１領域は前記第２領域に取り囲まれており、
前記第２領域に含まれる負極活物質は、前記第１領域に含まれる負極活物質に比して、充放電時の膨張収縮率が大きい、
電池。 Contains container, electrode body and electrolyte
The container contains the electrode body and the electrolytic solution, and contains the electrode body and the electrolytic solution.
A part of the electrolytic solution is impregnated in the electrode body.
The electrode body is a laminated type and is
The electrode body includes a positive electrode sheet, a separator sheet and a negative electrode sheet.
The separator sheet is arranged between the positive electrode sheet and the negative electrode sheet.
The negative electrode sheet contains a negative electrode active material layer and contains a negative electrode active material layer.
In plan view
The negative electrode active material layer includes a first region and a second region.
The second region is arranged along the peripheral edge of the negative electrode active material layer.
The first region is surrounded by the second region.
The negative electrode active material contained in the second region has a larger expansion / contraction rate during charging / discharging than the negative electrode active material contained in the first region.
battery.
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