JP2013118090A - Battery state monitoring device and battery state monitoring method - Google Patents

Battery state monitoring device and battery state monitoring method Download PDF

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JP2013118090A
JP2013118090A JP2011264701A JP2011264701A JP2013118090A JP 2013118090 A JP2013118090 A JP 2013118090A JP 2011264701 A JP2011264701 A JP 2011264701A JP 2011264701 A JP2011264701 A JP 2011264701A JP 2013118090 A JP2013118090 A JP 2013118090A
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secondary battery
negative electrode
charging
battery
potential
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Yosuke Suzuki
陽介 鈴木
Kenha Cho
剣波 張
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Nissan Motor Co Ltd
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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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    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • 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

PROBLEM TO BE SOLVED: To provide a battery state monitoring device that is capable of grasping a charged state of a secondary battery.SOLUTION: A battery state monitoring device includes: a secondary battery 1 obtained by sealing, inside an exterior member 16, a positive electrode plate 11 and a negative electrode plate 13, which are disposed with a separator 12 in-between, a reference electrode 17, and an electrolyte; and battery state monitoring means for monitoring a charged state of the secondary battery, wherein the reference electrode 17 is provided for the negative electrode plate 13 with an insulation member in-between and the battery state monitoring means monitors the charged state of the secondary battery 1 on the basis of a change amount per time of a measurement potential measured by the reference electrode 17 after charging of the secondary battery 1 is stopped.

Description

本発明は、電池状態監視装置及び電池状態の監視方法に関するものである。   The present invention relates to a battery state monitoring device and a battery state monitoring method.

電解液中でセパレータを介して積層される複数の電極と、前記複数の電極と電気的に絶縁され、前記電極の積層方向における当該電極の投影面内に配置され、発電要素の最上層で、片面に負極活物質層が形成された負極集電体の上部に配置される参照極と、を有する電気化学セルが知られている（特許文献１）。   A plurality of electrodes laminated via separators in the electrolyte, and electrically insulated from the plurality of electrodes, arranged in the projection plane of the electrodes in the lamination direction of the electrodes, An electrochemical cell having a reference electrode disposed on an upper part of a negative electrode current collector having a negative electrode active material layer formed on one side is known (Patent Document 1).

特開２０１０−７３５５８号公報JP 2010-73558 A

しかしながら、従来の参照極は、負極電極層の絶縁層側の電位を測定する構成であるため、負極電極層のセパレータ側の電位を正確に把握することができないという問題があった。例えばリチウムイオン電池では、負極電極層のセパレータ側が局所的に過充電状態となり、リチウム金属が析出するため、負極電極層のセパレータ側の電位を把握することが、二次電池の過充電状態を把握するためには不可欠である。   However, since the conventional reference electrode is configured to measure the potential on the insulating layer side of the negative electrode layer, there is a problem that the potential on the separator side of the negative electrode layer cannot be accurately grasped. For example, in a lithium ion battery, the separator side of the negative electrode layer is locally overcharged, and lithium metal is deposited. Therefore, grasping the potential on the separator side of the negative electrode layer can grasp the overcharge state of the secondary battery. It is essential to do.

本発明が解決しようとする課題は、二次電池の充電状態を把握することができる電池状態監視装置及び方法を提供する。   The problem to be solved by the present invention is to provide a battery state monitoring apparatus and method capable of grasping the state of charge of a secondary battery.

本発明は、参照極を、絶縁部材を介して負極板に設け、二次電池の充電停止後の、当該参照極による測定電位の時間あたりの変化量に基づいて、二次電池の充電状態を監視することによって上記課題を解決する。   The present invention provides a reference electrode on the negative electrode plate via an insulating member, and determines the state of charge of the secondary battery based on the amount of change in the measured potential per time by the reference electrode after the charge of the secondary battery is stopped. The above problem is solved by monitoring.

本発明によれば、参照極により負極電極層の集電体側の電位を経時的に測定することで、負極電極層のセパレータ側の電位を推定した上で、二次電池の充電状態が監視されるため、二次電池の充電状態を把握することができる。   According to the present invention, by measuring the potential on the current collector side of the negative electrode layer with the reference electrode over time, the charge state of the secondary battery is monitored after estimating the potential on the separator side of the negative electrode layer. Therefore, the state of charge of the secondary battery can be grasped.

本発明の実施形態に係る電池状態監視装置のブロック図である。It is a block diagram of the battery state monitoring apparatus which concerns on embodiment of this invention. 図１の参照極の測定電位の時間特性を示すグラフである。It is a graph which shows the time characteristic of the measurement electric potential of the reference pole of FIG. 図１の負極層におけるリチウムイオンの濃度分布及び負極電位の変化を説明するための模式図であり、（ａ）は充電中の状態を、（ｂ）は充電停止時の状態を、（ｃ）は（ｂ）の後の状態、（ｄ）は（ｃ）の後の状態を示す図である。It is a schematic diagram for demonstrating the density | concentration distribution of the lithium ion in the negative electrode layer of FIG. 1, and the change of negative electrode potential, (a) is the state in charge, (b) is the state at the time of charge stop, (c). (B) is a figure after (b), (d) is a figure which shows the state after (c). 図１の充電装置の制御手順を示すフローチャートである。It is a flowchart which shows the control procedure of the charging device of FIG. 本発明の変形例の電池状態監視装置における、充電装置の制御手順を示すフローチャートである。It is a flowchart which shows the control procedure of the charging device in the battery state monitoring apparatus of the modification of this invention.

以下、本発明の実施形態を図面に基づいて説明する。   Hereinafter, embodiments of the present invention will be described with reference to the drawings.

《第１実施形態》
図１は、本発明の実施形態に係る電池状態監視装置のブロック図を示す。なお、図１では、本発明の電池状態監視装置に含まれる二次電池を断面図で表す。本例の電池状態監視装置は、例えばリチウムイオン二次電池である非水電解質二次電池１と、電圧計２と、制御部３とを備えている。本例の二次電池１は、積層タイプの薄型二次電池であり、図１に示すように、３枚の正極板１１と、６枚のセパレータ１２と、３枚の負極板１３と、正極タブ１４と、負極タブ１５と、外装部材１６と、参照極１７と、参照極タブ１９と、特に図示しない電解液とから構成されている。 << First Embodiment >>
FIG. 1 shows a block diagram of a battery state monitoring apparatus according to an embodiment of the present invention. In addition, in FIG. 1, the secondary battery contained in the battery state monitoring apparatus of this invention is represented with sectional drawing. The battery state monitoring device of this example includes a non-aqueous electrolyte secondary battery 1 that is, for example, a lithium ion secondary battery, a voltmeter 2, and a control unit 3. The secondary battery 1 of this example is a laminated type thin secondary battery, and as shown in FIG. 1, three positive plates 11, six separators 12, three negative plates 13, and positive electrodes The tab 14, the negative electrode tab 15, the exterior member 16, the reference electrode 17, the reference electrode tab 19, and an electrolyte solution (not particularly shown) are configured.

このうちの正極板１１、セパレータ１２、負極板１３及び電解質が発電要素１８を構成し、また、正極板１１、負極板１３が電極板を構成する。   Among these, the positive electrode plate 11, the separator 12, the negative electrode plate 13, and the electrolyte constitute a power generation element 18, and the positive electrode plate 11 and the negative electrode plate 13 constitute an electrode plate.

発電要素１８を構成する正極板１１は、正極集電体１１ａと、正極集電体１１ａの一部の両主面にそれぞれ形成された正極層１１ｂ，１１ｃとを有する。正極板１１の正極層１１ｂ，１１ｃは、正極板１１、セパレータ１２及び負極板１３を積層して発電要素１８を構成する際に、正極板１１においてセパレータ１２に実質的に重なる部分に形成されている。複数の正極板１１のうち、発電要素１８の積層構造の最外層に配置される正極板１１は、正極集電体１１ａの一方の片主面に形成された正極層１１ｃを有し、正極集電体１１ａの他方の片主面には正極層１１ｂが形成されていない。   The positive electrode plate 11 constituting the power generation element 18 includes a positive electrode current collector 11a and positive electrode layers 11b and 11c formed on both main surfaces of a part of the positive electrode current collector 11a. The positive electrode layers 11 b and 11 c of the positive electrode plate 11 are formed in a portion of the positive electrode plate 11 that substantially overlaps the separator 12 when the positive electrode plate 11, the separator 12, and the negative electrode plate 13 are stacked to form the power generation element 18. Yes. Among the plurality of positive electrode plates 11, the positive electrode plate 11 disposed in the outermost layer of the stacked structure of the power generation elements 18 includes a positive electrode layer 11 c formed on one main surface of the positive electrode current collector 11 a. The positive electrode layer 11b is not formed on the other main surface of the electric body 11a.

正極板１１の正極集電体１１ａは、たとえばアルミニウム箔、アルミニウム合金箔、銅箔、又は、ニッケル箔等の電気化学的に安定した金属箔から構成されている。また、正極板１１の正極層１１ｂ，１１ｃは、たとえば、ニッケル酸リチウム（ＬｉＮｉＯ２）、マンガン酸リチウム（ＬｉＭｎＯ２）、又は、コバルト酸リチウム（ＬｉＣｏＯ２）等のリチウム複合酸化物や、カルコゲン（Ｓ、Ｓｅ、Ｔｅ）化物等の正極活物質と、カーボンブラック等の導電剤と、ポリ四フッ化エチレンの水性ディスパージョン等の接着剤と、溶剤とを混合したものを、正極集電体１１ａの一部の両主面に塗布し、乾燥及び圧延することにより形成されている。 The positive electrode current collector 11a of the positive electrode plate 11 is made of an electrochemically stable metal foil such as an aluminum foil, an aluminum alloy foil, a copper foil, or a nickel foil. Moreover, the positive electrode layers 11b and 11c of the positive electrode plate 11 are formed of, for example, lithium composite oxides such as lithium nickelate (LiNiO 2 ), lithium manganate (LiMnO 2 ), or lithium cobaltate (LiCoO 2 ), chalcogen ( A mixture of a positive electrode active material such as S, Se, Te), a conductive agent such as carbon black, an adhesive such as an aqueous dispersion of polytetrafluoroethylene, and a solvent is used as a positive electrode current collector 11a. It is formed by applying to both main surfaces of a part of, and drying and rolling.

発電要素１８を構成する負極板１３は、負極集電体１３ａと、当該負極集電体１３ａの一部の両主面にそれぞれ形成された負極層１３ｂ，１３ｃとを有する。なお、負極板１３の負極層１３ｂ，１３ｃは、正極板１１、セパレータ１２及び負極板１３を積層して発電要素１８を構成する際に、負極板１３においてセパレータ１２に実質的に重なる部分に形成されている。また、複数の負極板１３のうち、発電要素１８の積層構造の最外層に配置される負極板１３は、負極集電体１３ａの一方の片主面に形成された負極層１３ｂを有し、負極集電体１３ａの他方の片主面には負極層１３ｃが形成されていない。   The negative electrode plate 13 constituting the power generation element 18 includes a negative electrode current collector 13a and negative electrode layers 13b and 13c formed on both main surfaces of a part of the negative electrode current collector 13a. The negative electrode layers 13b and 13c of the negative electrode plate 13 are formed in a portion of the negative electrode plate 13 that substantially overlaps the separator 12 when the positive electrode plate 11, the separator 12, and the negative electrode plate 13 are stacked to form the power generation element 18. Has been. Further, among the plurality of negative electrode plates 13, the negative electrode plate 13 disposed in the outermost layer of the stacked structure of the power generation element 18 has a negative electrode layer 13b formed on one main surface of the negative electrode current collector 13a. The negative electrode layer 13c is not formed on the other main surface of the negative electrode current collector 13a.

負極板１３の負極集電体１３ａは、たとえばニッケル箔、銅箔、ステンレス箔、又は、鉄箔等の電気化学的に安定した金属箔から構成されている。また、負極板１３の負極層１３ｂ，１３ｃは、たとえば非晶質炭素、難黒鉛化炭素、易黒鉛化炭素、又は、黒鉛等のような、リチウムイオンを吸蔵及び放出する負極活物質に、スチレンブタジエンゴム樹脂粉末の水性ディスパージョンを混合し、乾燥させた後に粉砕することで、炭素粒子表面に炭化したスチレンブタジエンゴムを担持させたものを主材料とし、これにアクリル樹脂エマルジョン等の結着剤をさらに混合し、この混合物を負極集電体１３ａの一部の両主面に塗布し、乾燥及び圧延させることにより形成されている。   The negative electrode current collector 13a of the negative electrode plate 13 is made of an electrochemically stable metal foil, such as nickel foil, copper foil, stainless steel foil, or iron foil. Further, the negative electrode layers 13b and 13c of the negative electrode plate 13 are formed of styrene as a negative electrode active material that occludes and releases lithium ions, such as amorphous carbon, non-graphitizable carbon, graphitizable carbon, or graphite. An aqueous dispersion of butadiene rubber resin powder is mixed, dried and then pulverized, so that the main material is carbonized styrene butadiene rubber supported on the surface of the carbon particles, and a binder such as an acrylic resin emulsion. Are further mixed, and this mixture is applied to both main surfaces of part of the negative electrode current collector 13a, followed by drying and rolling.

特に、負極活物質として非晶質炭素や難黒鉛化炭素を用いると、充放電時における電位の平坦特性に乏しく放電量に伴って出力電圧も低下するので、通信機器や事務機器の電源には不向きであるが、電気自動車の電源として用いると急激な出力低下がないので有利である。   In particular, when amorphous carbon or non-graphitizable carbon is used as the negative electrode active material, the flatness of the potential during charge / discharge is poor and the output voltage decreases with the amount of discharge. Although unsuitable, it is advantageous when used as a power source for an electric vehicle because there is no sudden drop in output.

発電要素１８のセパレータ１２は、上述した正極板１１と負極板１３との短絡を防止すると同時に、電解液を保持する機能を備えている。このセパレータ１２は、たとえばポリエチレン（ＰＥ）やポリプロピレン（ＰＰ）等のポリオレフィン等から構成される微多孔性膜であり、過電流が流れると、その発熱によって層の空孔が閉塞され電流を遮断する機能をも有する。   The separator 12 of the power generation element 18 has a function of preventing the short-circuit between the positive electrode plate 11 and the negative electrode plate 13 and holding the electrolytic solution. The separator 12 is a microporous film made of polyolefin such as polyethylene (PE) or polypropylene (PP), for example. When an overcurrent flows, the pores of the layer are blocked by the heat generation and the current is cut off. It also has a function.

なお、本例に係るセパレータ１２は、ポリオレフィン等の単層膜にのみ限られず、ポリプロピレン膜をポリエチレン膜でサンドイッチした三層構造や、ポリオレフィン微多孔膜と有機不織布等を積層したものも用いることができる。このようにセパレータ１２を複層化することで、過電流の防止機能、電解質保持機能及びセパレータの形状維持（剛性向上）機能等の諸機能を付与することができる。   The separator 12 according to this example is not limited to a single-layer film such as polyolefin, but a three-layer structure in which a polypropylene film is sandwiched with a polyethylene film or a laminate of a polyolefin microporous film and an organic nonwoven fabric may be used. it can. Thus, by making the separator 12 into multiple layers, various functions such as an overcurrent prevention function, an electrolyte holding function, and a separator shape maintenance (stiffness improvement) function can be provided.

以上の発電要素１８は、セパレータ１２を介して正極板１１と負極板１３とが交互に積層されてなる。そして、３枚の正極板１１のうち、最外層の正極板１１は、正極集電体１１ａを介して、金属箔製の正極タブ１４に接続される。また、３枚の負極板１３のうち最外層の負極板１３は、負極集電体１３ａを介して、同様に金属箔製の負極タブ１５に接続されている。   The power generation element 18 is formed by alternately stacking the positive electrode plates 11 and the negative electrode plates 13 with the separators 12 interposed therebetween. Of the three positive electrode plates 11, the outermost positive electrode plate 11 is connected to the positive electrode tab 14 made of metal foil via the positive electrode current collector 11a. The outermost negative electrode plate 13 among the three negative electrode plates 13 is similarly connected to the negative electrode tab 15 made of metal foil via the negative electrode current collector 13a.

なお、発電要素１８の正極板１１、セパレータ１２、及び負極板１３は、上記の枚数に何ら限定されず、たとえば１枚の正極板１１、３枚のセパレータ１２、及び１枚の負極板１３でも発電要素１８を構成することができ、必要に応じて正極板１１、セパレータ１２及び負極板１３の枚数を選択して構成することができる。   In addition, the positive electrode plate 11, the separator 12, and the negative electrode plate 13 of the power generation element 18 are not limited to the above number, and for example, one positive plate 11, three separators 12, and one negative plate 13 are also included. The power generation element 18 can be configured, and the number of the positive electrode plate 11, the separator 12, and the negative electrode plate 13 can be selected and configured as necessary.

正極タブ１４も負極タブ１５も電気化学的に安定した金属材料であれば特に限定されないが、正極タブ１４としては、上述の正極集電体１１ａと同様に、たとえば厚さ０．２ｍｍ程度のアルミニウム箔、アルミニウム合金箔、銅箔、又はニッケル箔等を挙げることができる。また、負極タブ１５としては、上述の負極集電体１３ａと同様に、たとえば厚さ０．２ｍｍ程度のニッケル箔、銅箔、ステンレス箔、又は、鉄箔等を挙げることができる。   The positive electrode tab 14 and the negative electrode tab 15 are not particularly limited as long as they are electrochemically stable metal materials. As the positive electrode tab 14, for example, aluminum having a thickness of about 0.2 mm is used. A foil, an aluminum alloy foil, a copper foil, a nickel foil, or the like can be given. In addition, as the negative electrode tab 15, for example, a nickel foil, a copper foil, a stainless steel foil, or an iron foil having a thickness of about 0.2 mm can be used as in the negative electrode current collector 13 a described above.

参照極１７は、発電要素１８の積層構造のうち最外層に配置される負極板１３のさらに外側に、セパレータ１５を介して設けられている。参照極１７は、最外層に配置される負極板１３の負極集電体１３ａの両主面のうち、負極層１３ｂが形成された主面と反対側の主面側に、セパレータ１５を介して設けられている。参照極１７は、負極集電体１３ａの電位を測定するための電極である。参照極１７は、正確に電位を測定するよう、参照極１７の抵抗を低減させるために、好ましくは、負極集電体１３ａと同形状に形成されるとよい。参照極１７は、ニッケルなどの金属基板に、当該金属基板とは異なる金属である、リチウム、スズ、銀、白金、チタン酸リチウムなどの金属を表面電極としてコーティングすることで形成される。参照極１７はキャスト、電析などの方法で形成される。参照極１７には参照極タブ１９が接続され、参照極タブ１９は外部に導出されている。   The reference electrode 17 is provided on the outer side of the negative electrode plate 13 disposed in the outermost layer of the laminated structure of the power generation element 18 via the separator 15. The reference electrode 17 has a separator 15 on a main surface side opposite to the main surface on which the negative electrode layer 13b is formed, out of both main surfaces of the negative electrode current collector 13a of the negative electrode plate 13 disposed in the outermost layer. Is provided. The reference electrode 17 is an electrode for measuring the potential of the negative electrode current collector 13a. The reference electrode 17 is preferably formed in the same shape as the negative electrode current collector 13a in order to reduce the resistance of the reference electrode 17 so as to accurately measure the potential. The reference electrode 17 is formed by coating a metal substrate such as nickel as a surface electrode with a metal such as lithium, tin, silver, platinum, or lithium titanate, which is a metal different from the metal substrate. The reference electrode 17 is formed by a method such as casting or electrodeposition. A reference electrode tab 19 is connected to the reference electrode 17, and the reference electrode tab 19 is led out to the outside.

上述したセパレータ１２、参照極１７及び発電要素１８は、外装部材１６に収容されて封止されている。特に図示はしないが、本例の外装部材１６は、二次電池１の内側から外側に向かって、たとえばポリエチレン、変性ポリエチレン、ポリプロピレン、変性ポリプロピレン、又は、アイオノマー等の耐電解液性及び熱融着性に優れた樹脂フィルムから構成されている内側層と、たとえばアルミニウム等の金属箔から構成されている中間層と、たとえばポリアミド系樹脂又はポリエステル系樹脂等の電気絶縁性に優れた樹脂フィルムで構成されている外側層と、の三層構造とされている。   The separator 12, the reference electrode 17, and the power generation element 18 described above are housed and sealed in the exterior member 16. Although not illustrated in particular, the exterior member 16 of the present example is made from an inner side to an outer side of the secondary battery 1, for example, an electrolyte solution resistance such as polyethylene, modified polyethylene, polypropylene, modified polypropylene, or ionomer, and heat fusion. Consists of an inner layer composed of a resin film excellent in properties, an intermediate layer composed of a metal foil such as aluminum, and a resin film excellent in electrical insulation such as a polyamide resin or a polyester resin The outer layer is a three-layer structure.

したがって、外装部材１６は何れも、たとえばアルミニウム箔等金属箔の一方の面（薄型電池１の内側面）をポリエチレン、変性ポリエチレン、ポリプロピレン、変性ポリプロピレン、又はアイオノマー等の樹脂でラミネートし、他方の面（薄型電池１の外側面）をポリアミド系樹脂又はポリエステル系樹脂でラミネートした、樹脂−金属薄膜ラミネート材等の可撓性を有する材料で形成されている。   Accordingly, in each of the exterior members 16, for example, one surface of the metal foil such as an aluminum foil (inner surface of the thin battery 1) is laminated with a resin such as polyethylene, modified polyethylene, polypropylene, modified polypropylene, or ionomer, and the other surface. It is formed of a flexible material such as a resin-metal thin film laminate material obtained by laminating (an outer surface of the thin battery 1) with a polyamide resin or a polyester resin.

このように、外装部材１６が樹脂層に加えて金属層を具備することにより、外装部材自体の強度向上を図ることが可能となる。また、外装部材１６の内側層を、たとえばポリエチレン、変性ポリエチレン、ポリプロピレン、変性ポリプロピレン、又はアイオノマー等の樹脂で構成することにより、電極タブ１４、１５及び参照極タブ１９との良好な融着性を確保することが可能となる。   As described above, when the exterior member 16 includes the metal layer in addition to the resin layer, it is possible to improve the strength of the exterior member itself. Further, the inner layer of the exterior member 16 is made of, for example, a resin such as polyethylene, modified polyethylene, polypropylene, modified polypropylene, or ionomer, so that good fusion properties with the electrode tabs 14 and 15 and the reference electrode tab 19 can be obtained. It can be secured.

なお、図１に示すように、封止された外装部材１６の一方の端部から電極タブ１４、１５及び参照極タブ１９が導出されているが、タブの厚さ分だけ外装部材１６の融着部に隙間が生じるので、薄型電池１内部の封止性を維持するために、タブと外装部材１６とが接触する部分に、たとえばポリエチレンやポリプロピレン等から構成されたシールフィルムを介在させてもよい。   As shown in FIG. 1, the electrode tabs 14 and 15 and the reference electrode tab 19 are led out from one end of the sealed exterior member 16, but the exterior member 16 is melted by the thickness of the tab. Since a gap occurs in the attachment portion, a seal film made of, for example, polyethylene or polypropylene may be interposed in a portion where the tab and the exterior member 16 are in contact with each other in order to maintain the sealing performance inside the thin battery 1. Good.

外装部材１６によって、上述したセパレータ１４、参照極１７及び発電要素１８と、正極タブ１４の一部、負極タブ１５の一部及び参照極タブ１９の一部を包み込み、外装部材１６により形成される内部空間に、有機液体溶媒に過塩素酸リチウム、ホウフッ化リチウムや六フッ化リン酸リチウム等のリチウム塩を溶質とした液体電解質を注入しながら、外装部材１６により形成される空間を吸引して真空状態とした後に、外装部材１６の外周縁を熱プレスにより熱融着して封止する。   The exterior member 16 wraps the separator 14, the reference electrode 17, the power generation element 18, the part of the positive electrode tab 14, the part of the negative electrode tab 15, and the part of the reference electrode tab 19, and is formed by the exterior member 16. While injecting a liquid electrolyte having a lithium salt such as lithium perchlorate, lithium borofluoride or lithium hexafluorophosphate into an organic liquid solvent, the space formed by the exterior member 16 is sucked into the internal space. After the vacuum state, the outer peripheral edge of the exterior member 16 is heat-sealed by hot pressing and sealed.

有機液体溶媒として、プロピレンカーボネート（ＰＣ）、エチレンカーボネート（ＥＣ）、ジメチルカーボネート（ＤＭＣ）やメチルエチルカーボネート等のエステル系溶媒を挙げることができるが、本例の有機液体溶媒はこれに限定されることなく、エステル系溶媒に、γ−ブチロラクトン（γ−ＢＬ）、ジエトシキエタン（ＤＥＥ）等のエーテル系溶媒その他を混合、調合した有機液体溶媒を用いることもできる。   Examples of the organic liquid solvent include ester solvents such as propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), and methyl ethyl carbonate, but the organic liquid solvent in this example is limited to this. It is also possible to use an organic liquid solvent prepared by mixing and preparing an ether solvent such as γ-butyrolactone (γ-BL) or dietoxyethane (DEE) in the ester solvent.

電圧計２は、負極タブ１５及び参照極タブ１９に接続され負極の電位を測定する。充電装置３は、図示しない充電回路、充電制御部３１及び電池状態監視部３２等を有し、正極タブ１４、負極タブ１５及び電圧計２に接続されている。充電装置３は、図示しない電源からの電力を、充電制御部３１の制御に基づいて、充電回路で充電に適した電力に変換して正極タブ１４及び負極タブ１５の間に出力し、二次電池１を充電する。また充電装置３は、二次電池１の充電制御中に、電池状態監視部３２の制御に基づいて、電圧計２の測定電位を用いて、二次電池１の充電状態を監視している。   The voltmeter 2 is connected to the negative electrode tab 15 and the reference electrode tab 19 and measures the potential of the negative electrode. The charging device 3 includes a charging circuit (not shown), a charging control unit 31, a battery state monitoring unit 32, and the like, and is connected to the positive electrode tab 14, the negative electrode tab 15, and the voltmeter 2. The charging device 3 converts electric power from a power source (not shown) into electric power suitable for charging by the charging circuit based on the control of the charging control unit 31, and outputs the electric power between the positive electrode tab 14 and the negative electrode tab 15 to obtain the secondary power. The battery 1 is charged. In addition, the charging device 3 monitors the charging state of the secondary battery 1 using the measured potential of the voltmeter 2 based on the control of the battery state monitoring unit 32 during the charging control of the secondary battery 1.

次に、本例の電池状態監視装置の制御内容について説明する。まず充電制御について説明する。充電制御部３１は、電池状態監視部３２により監視された二次電池１の充電状態に応じて、二次電池１の充電電流を設定し、二次電池１を充電する。ユーザの操作などにより充電開始が指示されると、充電制御部３１は、予め設定されている充電電流で二次電池１の充電を開始する。   Next, the control content of the battery state monitoring apparatus of this example will be described. First, charge control will be described. The charging control unit 31 sets the charging current of the secondary battery 1 according to the charging state of the secondary battery 1 monitored by the battery state monitoring unit 32 and charges the secondary battery 1. When charging is instructed by a user operation or the like, the charging control unit 31 starts charging the secondary battery 1 with a preset charging current.

電池状態監視部３２は、充電中、二次電池１が過充電に達したか否かを判断しており、充電制御部３１は二次電池１が過充電に達したと判断された場合には、二次電池１への充電電流の出力を停止し、充電を終了させる。また、充電制御部３１は、充電制御中、所定の時間毎に充電を一時的に停止させ、電池状態監視部３２は充電停止中に二次電池１の充電状態を監視する。そして、充電停止中、電池状態監視部３２により、二次電池１が過充電の状態ではないと判定された場合には、充電制御部３１は充電を再開し、充電電流を再び二次電池１に出力する。一方、充電停止中、電池状態監視部３２により、二次電池１が過充電の状態であると判定された場合には、充電制御部３１は充電を終了させる。   The battery state monitoring unit 32 determines whether or not the secondary battery 1 has reached overcharge during charging, and the charge control unit 31 determines that the secondary battery 1 has reached overcharge. Stops the output of the charging current to the secondary battery 1 and ends the charging. Further, the charging control unit 31 temporarily stops charging at predetermined time intervals during charging control, and the battery state monitoring unit 32 monitors the charging state of the secondary battery 1 while charging is stopped. When the battery state monitoring unit 32 determines that the secondary battery 1 is not in an overcharged state while charging is stopped, the charge control unit 31 resumes charging and recharges the secondary battery 1 again. Output to. On the other hand, when the battery state monitoring unit 32 determines that the secondary battery 1 is in an overcharged state while charging is stopped, the charging control unit 31 ends the charging.

次に、電池状態の監視制御について説明する。電池状態監視部３２は、二次電池１の充電制御中、参照極１７により測定される測定電位を、電圧計２を介して、所定の周期で検出する。そして、電池状態監視部３２は、二次電池１の充電中、言い換えると、充電装置３から二次電池１に電流が流れている場合に、周期的に測定される測定電位に基づいて、二次電池１が過充電であるか否かを判定する。また、電池状態監視部３２は、充電制御中であり、一時的に充電を停止させている時に、言い換えると、充電装置３から二次電池１への充電電流を一時的に流していない時に、周期的に測定される測定電位に基づいて、二次電池１が過充電であるか否かを判定する。   Next, battery state monitoring control will be described. The battery state monitoring unit 32 detects the measurement potential measured by the reference electrode 17 at a predetermined cycle via the voltmeter 2 during charging control of the secondary battery 1. Then, the battery state monitoring unit 32 is configured to charge the secondary battery 1 based on the measured potential measured periodically while the secondary battery 1 is being charged, in other words, when a current flows from the charging device 3 to the secondary battery 1. It is determined whether or not the secondary battery 1 is overcharged. The battery state monitoring unit 32 is in charge control and temporarily stops charging, in other words, when the charging current from the charging device 3 to the secondary battery 1 is not temporarily flowing, It is determined whether or not the secondary battery 1 is overcharged based on periodically measured potentials.

ここで、二次電池１の充電状態を監視するために用いられる、参照極１７の測定電位について、説明する。図１に示すように、参照極１７は、セパレータ１２を介して、負極集電体１３ａに設けられているため、負極層１３ｂの集電体１３ａ側の電位を測定する。負極層１３ｂの電位は、負極集電体１３ａ側とセパレータ１２側とで異なっており、セパレータ１２側の電位の方が負極集電体１３ａ側の電位より低い。リチウムイオン電池である二次電池１において、二次電池１が過充電状態になると、負極層１３ｂのセパレータ側が負極集電体１３ａ側と比較して、局所的に過充電状態になり易い。そのため、二次電池１の充電状態を正確に把握するためには、負極層１３ｂのセパレータ側の電位を把握する必要がある。   Here, the measured potential of the reference electrode 17 used for monitoring the state of charge of the secondary battery 1 will be described. As shown in FIG. 1, since the reference electrode 17 is provided on the negative electrode current collector 13a via the separator 12, the potential on the current collector 13a side of the negative electrode layer 13b is measured. The potential of the negative electrode layer 13b is different between the negative electrode current collector 13a side and the separator 12 side, and the potential on the separator 12 side is lower than the potential on the negative electrode current collector 13a side. In the secondary battery 1 which is a lithium ion battery, when the secondary battery 1 is overcharged, the separator side of the negative electrode layer 13b is likely to be locally overcharged compared to the negative electrode current collector 13a side. Therefore, in order to accurately grasp the charged state of the secondary battery 1, it is necessary to grasp the potential on the separator side of the negative electrode layer 13b.

負極層１３ａのセパレータ側と、負極層１３ａの集電体１３ａ側との間には、負極層１３ｂの厚み方向の抵抗成分がある。そのため、電池状態監視部３２は、二次電池１の充電中に、二次電池１が過充電になったことを判定するための電位の閾値を、負極層１３ａのセパレータ側の電位に基づいて、予め設定する。例えば、負極層１３ａの厚さと負極層の厚さ方向の抵抗値を予め測定し、負極層１３ａを流れる充電電流が面方向で均一であるとすれば、負極層１３ａの厚さ方向の抵抗及び充電電流から、負極層１３ａの厚さ方向における電圧上昇分を把握することができる。すなわち、負極層１３ａのセパレータ側が過充電状態になった場合の、負極層１３ａのセパレータ側の電位に対して、負極層１３ａの厚さ方向の抵抗分、高くした電位を電位閾値として設定する。   There is a resistance component in the thickness direction of the negative electrode layer 13b between the separator side of the negative electrode layer 13a and the current collector 13a side of the negative electrode layer 13a. Therefore, the battery state monitoring unit 32 determines the potential threshold value for determining that the secondary battery 1 is overcharged while the secondary battery 1 is being charged based on the separator-side potential of the negative electrode layer 13a. , Set in advance. For example, if the thickness of the negative electrode layer 13a and the resistance value in the thickness direction of the negative electrode layer are measured in advance and the charging current flowing through the negative electrode layer 13a is uniform in the surface direction, the resistance in the thickness direction of the negative electrode layer 13a and From the charging current, the voltage increase in the thickness direction of the negative electrode layer 13a can be grasped. That is, a potential that is increased by the resistance in the thickness direction of the negative electrode layer 13a with respect to the potential on the separator side of the negative electrode layer 13a when the separator side of the negative electrode layer 13a is overcharged is set as the potential threshold value.

そして、電池状態監視部３２は、バッテリ１の充電中に、参照極１７の測定電位と、上記の電位閾値とを比較し、測定電位が電位閾値より低くなった場合に、二次電池１が過充電である、と判定する。これにより、本例は、負極層１３ａの負極集電体１３ａ側の測定電位から、負極層１３ａのセパレータ側の電位を推定した上で、二次電池１の充電状態を監視している。   Then, the battery state monitoring unit 32 compares the measured potential of the reference electrode 17 with the above-described potential threshold during charging of the battery 1, and when the measured potential becomes lower than the potential threshold, the secondary battery 1 It is determined that the battery is overcharged. Thus, in this example, the charged state of the secondary battery 1 is monitored after the potential on the separator side of the negative electrode layer 13a is estimated from the measured potential on the negative electrode current collector 13a side of the negative electrode layer 13a.

また、本例では、二次電池１の充電状態の監視の精度を高めるために、二次電池１の充電を一時的に中断させて、充電の停止後の、参照極１７の測定電位の変化速度から二次電池１の充電状態を監視する。   Further, in this example, in order to improve the accuracy of monitoring the charging state of the secondary battery 1, the charging of the secondary battery 1 is temporarily interrupted, and the change in the measured potential of the reference electrode 17 after the charging is stopped. The charging state of the secondary battery 1 is monitored from the speed.

ここで、充電停止後の測定電位の特性について、図２及び図３を用いて説明する。図２は充電停止後の測定電位の時間特性を示すグラフであり、図３は充電中及び充電停止後の、負極層１３ｂにおけるリチウムイオンの濃度分布及び負極電位の変化を説明するための模式図である。   Here, the characteristics of the measured potential after charging is stopped will be described with reference to FIGS. FIG. 2 is a graph showing the time characteristics of the measured potential after stopping charging, and FIG. 3 is a schematic diagram for explaining the change in lithium ion concentration distribution and the negative electrode potential in the negative electrode layer 13b during charging and after charging is stopped. It is.

図２に示すように、停止直後、オーム損による過電圧の影響がなくなることで、充電停止後の二次電池１の負極電位はわずかに上昇し、その後、緩やかに下降する。充電停止後の負極電位の下降は、負極層１３ａ、１３ｃの厚さ方向におけるリチウムイオン濃度が緩和されることによって起こる。   As shown in FIG. 2, immediately after the stop, the influence of the overvoltage due to the ohmic loss is eliminated, so that the negative electrode potential of the secondary battery 1 after the charge stop slightly rises and then gradually falls. The decrease in the negative electrode potential after the stop of charging occurs when the lithium ion concentration in the thickness direction of the negative electrode layers 13a and 13c is relaxed.

次に、リチウムイオンの濃度分布と負極電位の変化について、図３を用いて説明する。なお図３において、図３（ａ）は充電中の、リチウムイオン濃度及び負極電位を示しており、充電停止後の経時的な推移を、図３（ｂ）、図３（ｃ）及び図３（ｄ）の順番で示している。また、図３（ａ）〜（ｄ）は、最外層に配置されている負極板１３と、当該負極板の内側に配置されているセパレータ１１の断面図の一部を模式化して表している。さらに図３の縦軸は、負極電位及びリチウムイオンの濃度の大きさを示しており、図の白丸はリチウムイオン濃度を、黒丸は負極電位を示している。   Next, changes in the lithium ion concentration distribution and the negative electrode potential will be described with reference to FIG. In FIG. 3, FIG. 3 (a) shows the lithium ion concentration and the negative electrode potential during charging, and the changes over time after charging is stopped are shown in FIG. 3 (b), FIG. 3 (c) and FIG. It is shown in the order of (d). 3A to 3D schematically show a part of a cross-sectional view of the negative electrode plate 13 arranged in the outermost layer and the separator 11 arranged inside the negative electrode plate. . Further, the vertical axis in FIG. 3 indicates the magnitude of the negative electrode potential and the concentration of lithium ions, the white circle in the figure indicates the lithium ion concentration, and the black circle indicates the negative electrode potential.

図３（ａ）に示すように、充電中、リチウムイオンは、セパレータ１２を通り、負極層１３ｂのセパレータ側に偏って反応するため、負極層１３ｂのセパレータ１２側のリチウムイオン濃度は、集電体１３ａ側と比較して高くなり、負極層１３ｂのセパレータ１２側の負極電位は、集電体１３ａ側と比較して低くなる。かかる状態で、充電を停止させると、負極層１３ｂにおける電位分布を緩和するように、リチウムイオンが負極層１３ｂ内を移動するため、図３（ｂ）及び図３（ｃ）に示すように、経時的に、負極層１３ｂのセパレータ１２側のリチウムイオン濃度と集電体１３ａ側のリチウムイオン濃度との差が小さくなり、負極層１３ｂのセパレータ１２側の電位と集電体１３ａ側の電位との電位差が小さくなる。そして、最終的には、図３（ｄ）に示すように、負極層１３ｂのセパレータ１２側のリチウムイオン濃度と集電体１３ａ側のリチウムイオン濃度との差、及び、負極層１３ｂのセパレータ１２側の電位と集電体１３ａ側の電位との電位差がなくなり、電極層１３ｂにおけるリチウムイオン濃度分布及び電位分布が安定する。   As shown in FIG. 3 (a), during charging, lithium ions pass through the separator 12 and react in a biased manner toward the separator side of the negative electrode layer 13b. Therefore, the lithium ion concentration on the separator 12 side of the negative electrode layer 13b is The negative electrode potential on the separator 12 side of the negative electrode layer 13b is lower than that on the current collector 13a side. When charging is stopped in this state, since lithium ions move in the negative electrode layer 13b so as to relax the potential distribution in the negative electrode layer 13b, as shown in FIGS. 3 (b) and 3 (c), Over time, the difference between the lithium ion concentration on the separator 12 side of the negative electrode layer 13b and the lithium ion concentration on the current collector 13a side decreases, and the potential on the separator 12 side and the potential on the current collector 13a side of the negative electrode layer 13b The potential difference becomes smaller. Finally, as shown in FIG. 3D, the difference between the lithium ion concentration on the separator 12 side of the negative electrode layer 13b and the lithium ion concentration on the current collector 13a side, and the separator 12 on the negative electrode layer 13b. The potential difference between the potential on the side and the potential on the side of the current collector 13a disappears, and the lithium ion concentration distribution and potential distribution in the electrode layer 13b are stabilized.

すなわち、負極層１３ｂの集電体１３ａ側の電位に着目すると、当該電位は充停止後に低下していることが分かる。そして、上記の通り、参照極１７は、負極層１３ｂの集電体１３ａ側の電位を測定しているため、参照極１７の測定電位は、充電停止後、低下することになる。また、二次電池１の充電状態が過充電に近づくほど、負極層１３ｂのセパレータ１２側のリチウムイオン濃度は、集電体１３ａ側に対して、高くなるため、負極層１３ｂのセパレータ１２側の電位は低くなる。そして、二次電池１の充電状態が過充電になった状態で、充電を停止させると、負極層１３ｂのセパレータ側の電位は、より低い状態から安定化に向かうため、電位の変化の速度が、過充電でない状態における電位の変化の速度と比較して早くなる。すなわち、二次電池１の充電状態が過充電に近づくと、充電停止後における、参照極１７の測定電位の単位時間あたりの変化量が高くなる。   That is, when attention is paid to the potential of the negative electrode layer 13b on the side of the current collector 13a, it can be seen that the potential decreases after charging is stopped. As described above, since the reference electrode 17 measures the potential of the negative electrode layer 13b on the side of the current collector 13a, the measured potential of the reference electrode 17 decreases after the charging is stopped. Moreover, since the lithium ion concentration on the separator 12 side of the negative electrode layer 13b becomes higher than the current collector 13a side as the charged state of the secondary battery 1 approaches overcharge, the separator 12 side of the negative electrode layer 13b becomes closer to the separator 12 side. The potential is lowered. And when charging is stopped in a state where the charging state of the secondary battery 1 is overcharged, the potential on the separator side of the negative electrode layer 13b tends to stabilize from a lower state. This is faster than the speed of potential change in a state where there is no overcharge. That is, when the state of charge of the secondary battery 1 approaches overcharge, the amount of change per unit time of the measured potential of the reference electrode 17 after charging is increased.

本例では、電池状態監視部３２は、充電制御部３１により一時的に充電を停止させた後に、周期的に測定される参照極１７の測定電位から、測定周期毎に測定電位の変化量を演算し、測定電位の単位時間あたりの変化量を演算する。測定電位の単位時間あたりの変化量は、充電停止後に、低下する測定電位の低下速度に相当する。
単位時間あたりの測定電位の変化量（ｖ）は、測定周期間における測定電位の変化量をΔＶ、測定周期をΔｔとすると、以下の式（１）で演算される。

Figure 2013118090
In this example, the battery state monitoring unit 32, after temporarily stopping charging by the charging control unit 31, calculates the amount of change in the measured potential for each measurement cycle from the measured potential of the reference electrode 17 that is periodically measured. Calculate the amount of change in the measured potential per unit time. The amount of change in the measured potential per unit time corresponds to the decreasing rate of the measured potential that decreases after the charging is stopped.
The change amount (v) of the measurement potential per unit time is calculated by the following equation (1), where ΔV is the change amount of the measurement potential between the measurement periods and Δt is the measurement period.
Figure 2013118090

また、電池状態監視部３２には、二次電池１が過充電になったこと示す、測定電位の単位時間あたりの変化量の閾値が変化量閾値として予め設定されている。変化量閾値は、好ましくは１００μＶ／秒、より好ましくは２０μＶ／秒以上にするとよい。そして、電池状態監視部３２は、演算された、単位時間あたりの測定電位の変化量と、変化量閾値とを比較し、単位時間あたりの測定電位の変化量が当該変化量閾値より高くなった場合に、二次電池１が過充電である、と判定する。これにより、本例は、充電停止後の、負極層１３ａの負極集電体１３ａ側の測定電位の変化量から、負極層１３ａのセパレータ側の電位を推定した上で二次電池１の充電状態を監視している。   In the battery state monitoring unit 32, a threshold value of a change amount per unit time of the measured potential, which indicates that the secondary battery 1 is overcharged, is preset as a change amount threshold value. The change amount threshold is preferably 100 μV / second, more preferably 20 μV / second or more. Then, the battery state monitoring unit 32 compares the calculated change amount of the measured potential per unit time with the change amount threshold value, and the change amount of the measured potential per unit time is higher than the change amount threshold value. In this case, it is determined that the secondary battery 1 is overcharged. Accordingly, in this example, the charged state of the secondary battery 1 is estimated after estimating the potential on the separator side of the negative electrode layer 13a from the amount of change in the measured potential on the negative electrode current collector 13a side of the negative electrode layer 13a after charging is stopped. Is monitoring.

充電停止後の、参照極１７の測定電位の変化量に基づき二次電池の充電状態を監視する制御は、二次電池１の充電中に所定の周期で充電を中断させて行う制御である。そのため、二次電池１の充電中、参照極１７の測定電位が電位閾値より低い場合であっても、電池状態監視部３２は、二次電池の１の充電停止後の、測定電圧の単位時間あたりの変化量が閾値変化量より高くなった場合には、二次電池１は過充電であると、判定する。これにより、本例は、参照極１７の測定電位に基づき、負極層１３ｂのセパレータ１２側の電位を、複数の方法で推定し、二次電池１の充電状態を監視するため、二次電池１の充電状態の監視の精度を高めることができる。   The control for monitoring the charging state of the secondary battery based on the amount of change in the measured potential of the reference electrode 17 after the charging is stopped is a control performed by interrupting the charging at a predetermined cycle while the secondary battery 1 is being charged. Therefore, even when the measured potential of the reference electrode 17 is lower than the potential threshold during charging of the secondary battery 1, the battery state monitoring unit 32 can measure the unit time of the measured voltage after stopping the charging of the secondary battery 1. When the per-change amount is higher than the threshold change amount, it is determined that the secondary battery 1 is overcharged. Thereby, in this example, the potential on the separator 12 side of the negative electrode layer 13b is estimated by a plurality of methods based on the measured potential of the reference electrode 17, and the charge state of the secondary battery 1 is monitored. The accuracy of monitoring the state of charge can be improved.

次に、図４を用いて、本例の充電装置３における制御手順を説明する。図４は、充電装置３の制御手順を示すフローチャートである。ステップＳ１にて、充電制御部３１は、予め設定されている電流を充電電流に設定し、ステップＳ２にて、設定された充電電流で二次電池１を充電する。ステップＳ３にて、電池状態監視部３２は、電圧計の検出電圧から、参照極１７の測定電位を所定の周期で計測する。   Next, the control procedure in the charging device 3 of this example will be described with reference to FIG. FIG. 4 is a flowchart showing a control procedure of the charging device 3. In step S1, the charging control unit 31 sets a preset current to the charging current, and in step S2, charges the secondary battery 1 with the set charging current. In step S3, the battery state monitoring unit 32 measures the measurement potential of the reference electrode 17 at a predetermined cycle from the detection voltage of the voltmeter.

ステップＳ４にて、電池状態監視部３２は、計測された測定電位と、電位閾値とを比較する。測定電位が電位閾値より低い場合には、ステップＳ７に遷り、電池状態監視部３２は、二次電池１の充電状態が過充電である、と判定する（ステップＳ７）。一方、測定電位が電位閾値以上である場合には、ステップＳ５にて、充電制御部３１は所定の周期で、二次電池１の充電を停止させる。ステップＳ６にて、電池状態監視部３２は、ステップＳ３で測定した測定電位を用いて、充電停止後の、測定電位の単位時間あたりの変化量を演算し、変化量閾値と比較する。   In step S4, the battery state monitoring unit 32 compares the measured potential measured with the potential threshold value. When the measured potential is lower than the potential threshold, the process proceeds to step S7, and the battery state monitoring unit 32 determines that the charged state of the secondary battery 1 is overcharge (step S7). On the other hand, when the measured potential is equal to or higher than the potential threshold, in step S5, the charge control unit 31 stops the charging of the secondary battery 1 at a predetermined cycle. In step S6, the battery state monitoring unit 32 uses the measured potential measured in step S3 to calculate the amount of change per unit time of the measured potential after stopping charging, and compares it with a change amount threshold value.

測定電位の単位時間あたりの変化量が変化量閾値以下である場合には、電池状態監視部３２は、二次電池１の充電状態は過充電ではない、と判定し、ステップＳ２に戻り、充電を再開させる。一方、測定電位の単位時間あたりの変化量が変化量閾値より高い場合には、ステップＳ７に遷り、電池状態監視部３２は、二次電池１の充電状態が過充電である、と判定する（ステップＳ７）。   If the change amount of the measured potential per unit time is equal to or less than the change amount threshold value, the battery state monitoring unit 32 determines that the charge state of the secondary battery 1 is not overcharge, and returns to step S2 to charge. To resume. On the other hand, when the change amount of the measured potential per unit time is higher than the change amount threshold value, the process proceeds to step S7, and the battery state monitoring unit 32 determines that the charged state of the secondary battery 1 is overcharged. (Step S7).

そして、ステップＳ７の後、ステップＳ８にて、充電制御部３１は、二次電池１に流れる充電電流をゼロにして、二次電池１の充電を終了させ、本例の制御を終了させる。   Then, after step S7, in step S8, the charging control unit 31 sets the charging current flowing in the secondary battery 1 to zero, ends the charging of the secondary battery 1, and ends the control of this example.

上記のように、本例は、参照極１７を、セパレータ１２を介して負極板１３に設け、二次電池の充電停止後の、参照極１７で測定される測定電位の時間あたりの変化量に基づいて、二次電池の充電状態を監視する。これにより、参照極１７の測定電位を経時的に測定することで、負極板１３において、局所的に過充電になり易い部分の電位を推定することができ、二次電池１の充電状態を正確に把握することができる。   As described above, in this example, the reference electrode 17 is provided on the negative electrode plate 13 with the separator 12 interposed therebetween, and the amount of change per unit time of the measured potential measured at the reference electrode 17 after the secondary battery is stopped being charged. Based on this, the state of charge of the secondary battery is monitored. Thereby, by measuring the measurement potential of the reference electrode 17 with time, the potential of the portion that is likely to be overcharged locally in the negative electrode plate 13 can be estimated, and the state of charge of the secondary battery 1 can be accurately determined. Can grasp.

また本例は、参照極１７を、負極層１３ｂが形成された集電体１３ａの主面と反対の主面側に設け、負極層１３ｂの集電体１３ａ側の電位を測定する。これにより、参照極１７が、負極層１３ｂで過放電状態になり易いセパレータ１２側の電位とは異なる電位を測定する場合であっても、セパレータ１２側の電位が推定されるため、二次電池１の充電状態を正確に把握することができる。   In this example, the reference electrode 17 is provided on the main surface side opposite to the main surface of the current collector 13a on which the negative electrode layer 13b is formed, and the potential on the current collector 13a side of the negative electrode layer 13b is measured. Thereby, even when the reference electrode 17 measures a potential different from the potential on the separator 12 side, which is likely to be overdischarged in the negative electrode layer 13b, the potential on the separator 12 side is estimated. 1 state of charge can be accurately grasped.

また本例は、二次電位１の充電停止後に低下する測定電位から測定電位の時間あたりの変化量を演算し、時間あたりの変化量が変化量閾値より高い場合に、二次電池１が過充電であると判定する。これにより、充電停止後の、負極層１３ｂの電位分の経時的な変化に基づいて、負極層１３ｂのセパレータ１２側の電位が推定されるため、局所的に過充電になり易い部分の電位の推定精度を高めることができ、その結果として、二次電池１の充電状態を正確に把握することができ、充電時の金属の析出を抑制することができる。   Also, in this example, when the amount of change in the measured potential per time is calculated from the measured potential that decreases after the secondary potential 1 is stopped, and the amount of change per time is higher than the change amount threshold, the secondary battery 1 is excessive. It determines with charging. As a result, since the potential on the separator 12 side of the negative electrode layer 13b is estimated based on the change over time of the potential of the negative electrode layer 13b after the charging is stopped, the potential of the portion that is likely to be overcharged locally is estimated. The estimation accuracy can be increased, and as a result, the state of charge of the secondary battery 1 can be accurately grasped, and metal deposition during charging can be suppressed.

また本例は、測定電位が電位閾値より高い状態で二次電池１の充電を停止し、充電停止後に低下する測定電位から測定電位の時間あたりの変化量を演算し、時間あたりの変化量が変化量閾値より高い場合に、二次電池１が過充電であると判定する。これにより、充電中に推定される負極層１３ｂのセパレータ１２側の電位では、二次電池１が過充電の状態であることを検出できない場合でも、充電停止後の測定電位の変化量を用いることで、当該過充電の状態を検出することができるため、二次電池１の充電状態を正確に把握することができ、充電時の金属の析出を抑制することができる。また、本例は、参照極１７の測定電位に基づき、負極層１３ｂのセパレータ１２側の電位を、複数の方法で推定し、二次電池１の充電状態を監視するため、二次電池１の充電状態の監視の精度を高めることができる。   Further, in this example, the charging of the secondary battery 1 is stopped in a state where the measured potential is higher than the potential threshold, and the amount of change per hour of the measured potential is calculated from the measured potential that decreases after the stop of charging. When it is higher than the change amount threshold, it is determined that the secondary battery 1 is overcharged. Thereby, even if it cannot detect that the secondary battery 1 is in an overcharged state with the potential on the separator 12 side of the negative electrode layer 13b estimated during charging, the amount of change in the measured potential after stopping charging is used. Therefore, since the state of the overcharge can be detected, the state of charge of the secondary battery 1 can be accurately grasped, and metal deposition during charging can be suppressed. Further, in this example, since the potential on the separator 12 side of the negative electrode layer 13b is estimated by a plurality of methods based on the measured potential of the reference electrode 17, the charge state of the secondary battery 1 is monitored. The accuracy of monitoring the state of charge can be increased.

また本例は、変化量閾値を好ましくは２０μＶ／秒以上に設定する。また本例は、電位閾値を好ましくは０．５Ｖ以下に設定する。これにより、充電時のリチウム金属の析出を抑制することができる。   In this example, the change amount threshold is preferably set to 20 μV / second or more. In this example, the potential threshold is preferably set to 0.5 V or less. Thereby, precipitation of lithium metal at the time of charge can be suppressed.

また本例において、参照極１７は、金属基板と、当該金属基板の表面を前記金属基板と異なる金属で覆う電極とを有している。これにより、参照極１７を薄くすることができるため、電池の安全性を向上させることができる。   In this example, the reference electrode 17 has a metal substrate and an electrode that covers the surface of the metal substrate with a metal different from the metal substrate. Thereby, since the reference electrode 17 can be made thin, the safety | security of a battery can be improved.

なお、本例において、充電制御部３１は、充電電流を段階的に下げ、最も低い充電電流が設定されている時に、電池状態監視部３２により二次電池１が過充電であると判定された場合に、充電を終了させるよう制御してもよい。充電制御部３１には、予め多段階の充電電流値が設定されており、充電開始時には、最も高い充電電流を設定し、二次電池１が満充電に近づくにつれて、徐々に低い充電電流を設定する。以下、図５を用いて、本発明の変形例における、本例の充電装置３の制御手順を説明する。図５は、本発明の変形例に係る充電装置３の制御手順を示すフローチャートである。ステップＳ１からステップＳ７までの制御内容は、図４に示すステップＳ１からステップＳ７までの制御内容と同じであるため、説明を省略する。   In this example, the charging control unit 31 gradually decreases the charging current, and when the lowest charging current is set, the battery state monitoring unit 32 determines that the secondary battery 1 is overcharged. In some cases, the charging may be controlled to end. Multi-stage charging current values are set in the charging control unit 31 in advance. At the start of charging, the highest charging current is set, and gradually lower charging current is set as the secondary battery 1 approaches full charge. To do. Hereinafter, the control procedure of the charging device 3 of the present example in a modification of the present invention will be described with reference to FIG. FIG. 5 is a flowchart showing a control procedure of the charging apparatus 3 according to the modification of the present invention. The control content from step S1 to step S7 is the same as the control content from step S1 to step S7 shown in FIG.

ステップＳ７にて、電池状態監視部３２により二次電池１が過充電であると判定されと、ステップＳ１０１にて、充電制御部３１は、設定されている電流が最も低い充電電流であるか否かを判定する。設定されている充電電流が最低充電電流である場合には、ステップＳ１０２にて、充電制御部３１は、二次電池１に流れる充電電流をゼロにして、二次電池１の充電を終了させ、本例の制御を終了させる。一方、設定されている充電電流が最低充電電流ではない場合には、ステップＳ１０３にて、充電制御部３１は、設定されていた充電電流に対して１段階低い充電電流を再設定し、ステップＳ２に遷り、充電を再開する。   In step S7, when the battery state monitoring unit 32 determines that the secondary battery 1 is overcharged, in step S101, the charge control unit 31 determines whether or not the set current is the lowest charging current. Determine whether. When the set charging current is the minimum charging current, in step S102, the charging control unit 31 sets the charging current flowing through the secondary battery 1 to zero, and terminates the charging of the secondary battery 1, The control of this example is terminated. On the other hand, if the set charging current is not the minimum charging current, in step S103, the charging control unit 31 resets the charging current one step lower than the set charging current, and step S2 Resumed charging.

上記のように、本例は、電池状態監視部３２により二次電池１が過充電であると判定された場合には、充電電流を過充電と判定される前の充電電流より低くして、二次電池１を充電する。これにより、充電時の金属の析出を抑制することができる。   As described above, in the present example, when the battery state monitoring unit 32 determines that the secondary battery 1 is overcharged, the charge current is set lower than the charge current before the overcharge is determined, The secondary battery 1 is charged. Thereby, precipitation of the metal at the time of charge can be suppressed.

なお、本例において、参照極１７は、セパレータ１２を介して負極集電体１３ａに設けたが、参照極１７を絶縁部材で覆い負極集電体１３ａに設けてもよい。   In this example, the reference electrode 17 is provided on the negative electrode current collector 13a via the separator 12. However, the reference electrode 17 may be provided on the negative electrode current collector 13a by covering it with an insulating member.

上記の電池状態監視部３２が本発明の「電池状態監視手段」に相当し、セパレータ１２が「絶縁部材」に、負極層１３ｂ、１３ｃが「負極電極層」に、充電制御部３１が「充電制御手段」に相当する。   The battery state monitoring unit 32 corresponds to the “battery state monitoring unit” of the present invention, the separator 12 is the “insulating member”, the negative electrode layers 13 b and 13 c are the “negative electrode layer”, and the charge control unit 31 is “charging”. It corresponds to “control means”.

１…二次電池
１１…正極板
１１ａ…正極集電体
１１ｂ…正極層
１１ｃ…正極層
１２…セパレータ
１３…負極板
１３ａ…負極集電体
１３ｂ…負極層
１３ｃ…負極層
１４…正極タブ
１５…負極タブ
１６…外装部材
１７…参照極
１８…発電要素
１９…参照極タブ
２…電圧計
３…制御部
３１…充電制御部
３２…電池状態監視部 DESCRIPTION OF SYMBOLS 1 ... Secondary battery 11 ... Positive electrode plate 11a ... Positive electrode collector 11b ... Positive electrode layer 11c ... Positive electrode layer 12 ... Separator 13 ... Negative electrode plate 13a ... Negative electrode collector 13b ... Negative electrode layer 13c ... Negative electrode layer 14 ... Positive electrode tab 15 ... Negative electrode tab 16 ... exterior member 17 ... reference electrode 18 ... power generation element 19 ... reference electrode tab 2 ... voltmeter 3 ... control unit 31 ... charge control unit 32 ... battery state monitoring unit

Claims (9)

セパレータを介して設けられる正極板及び負極板と、参照極と、電解液とを外装部材の内部に封止する二次電池と、
前記二次電池の充電状態を監視する電池状態監視手段とを備え、
前記参照極は、
絶縁部材を介して、前記負極板に設けられ、
前記電池状態監視手段は、
前記二次電池の充電停止後の、前記参照極で測定される測定電位の時間あたりの変化量に基づいて、前記二次電池の充電状態を監視する
ことを特徴とする電池状態監視装置。 A secondary battery that seals a positive electrode plate and a negative electrode plate provided via a separator, a reference electrode, and an electrolyte solution inside the exterior member;
Battery state monitoring means for monitoring the state of charge of the secondary battery,
The reference electrode is
Provided on the negative electrode plate via an insulating member;
The battery state monitoring means includes
A battery state monitoring device that monitors the state of charge of the secondary battery based on the amount of change per hour of the measured potential measured at the reference electrode after the charge of the secondary battery is stopped. 前記負極の電極板は、
負極集電体及び前記負極集電体の主面に形成された負極電極層を有し、
前記参照極は、
前記負極電極層が形成された前記負極集電体の主面と反対の主面側に設けられ、
前記負極集電体側の前記負極電極層の電位を測定する
ことを特徴とする請求項１記載の電池状態監視装置。 The negative electrode plate is:
A negative electrode current collector and a negative electrode layer formed on a main surface of the negative electrode current collector;
The reference electrode is
Provided on the main surface side opposite to the main surface of the negative electrode current collector on which the negative electrode layer is formed;
The battery state monitoring device according to claim 1, wherein a potential of the negative electrode layer on the negative electrode current collector side is measured. 前記電池状態監視手段は、
前記二次電池の充電停止後に低下する前記測定電位から前記時間あたりの変化量を演算し、
前記時間あたりの変化量が前記二次電池の過充電を示す変化量閾値より高い場合に、前記二次電池が過充電であると判定する
ことを特徴とする請求項１又は２記載の電池状態監視装置。 The battery state monitoring means includes
Calculate the amount of change per time from the measured potential that decreases after the secondary battery stops charging,
3. The battery state according to claim 1, wherein when the amount of change per time is higher than a change amount threshold value indicating overcharge of the secondary battery, the secondary battery is determined to be overcharged. Monitoring device. 前記電池状態監視手段は、
充電中、前記測定電位が前記二次電池の過充電を示す電位閾値より低い場合に、前記二次電池が過充電であると判定し、
前記測定電位が前記電位閾値より高い状態で前記二次電池の充電を停止した後に低下する前記変化量が、前記二次電池の過充電を示す変化量閾値より高い場合に、前記二次電池が過充電であると判定する
ことを特徴とする請求項１又は２記載の電池状態監視装置。 The battery state monitoring means includes
During charging, when the measured potential is lower than a potential threshold indicating overcharge of the secondary battery, it is determined that the secondary battery is overcharged,
When the amount of change that decreases after stopping the charging of the secondary battery in a state where the measured potential is higher than the potential threshold is higher than a change amount threshold that indicates overcharging of the secondary battery, the secondary battery 3. The battery state monitoring apparatus according to claim 1, wherein it is determined that the battery is overcharged. 前記二次電池の充電を制御する充電制御手段をさらに備え、
前記充電制御手段は、
前記電池状態監視手段により前記二次電池が過充電であると判定された場合には、前記二次電池の充電電流を過充電と判定される前の充電電流より低くして、前記二次電池を充電する
ことを特徴とする請求項１〜４のいずれか一項に記載の電池状態監視装置。 Charging control means for controlling charging of the secondary battery,
The charge control means includes
When the secondary battery is determined to be overcharged by the battery state monitoring means, the secondary battery is made to have a charging current lower than that before the secondary battery is determined to be overcharged. The battery state monitoring device according to any one of claims 1 to 4, wherein the battery state monitoring device is charged. 前記変化量閾値は、２０μＶ／秒以上に設定されていること特徴とする請求項３又は４記載の電池状態監視装置。 The battery state monitoring device according to claim 3 or 4, wherein the change amount threshold is set to 20 µV / second or more. 前記電位閾値は０．５Ｖ以下に設定されていることを特徴とする請求項４記載の電池状態監視装置。 The battery state monitoring apparatus according to claim 4, wherein the potential threshold is set to 0.5 V or less. 前記参照極は、金属基板と、当該金属基板の表面を前記金属基板と異なる金属で覆う電極とを有している
ことを特徴とする請求項１〜７のいずれか一項に記載の電池状態監視装置。 The battery state according to claim 1, wherein the reference electrode includes a metal substrate and an electrode that covers a surface of the metal substrate with a metal different from the metal substrate. Monitoring device. セパレータを介して設けられる正極及び負極の電極板と、絶縁部材を介して前記負極板に設けられる参照極と、電解液とを外装部材の内部に封止する二次電池の充電状態の監視方法であって、
前記二次電池の充電を一時的に停止させる充電停止ステップと、
前記充電停止ステップによる前記二次電池の充電停止後に、前記参照極で測定される測定電位の時間あたりの変化量を演算し、前記変化量に基づいて前記二次電池の充電状態を監視するステップとを含む充電状態の監視方法。 A method for monitoring a charged state of a secondary battery in which a positive electrode and a negative electrode plate provided via a separator, a reference electrode provided on the negative electrode plate via an insulating member, and an electrolyte solution are sealed inside an exterior member. Because
A charge stopping step for temporarily stopping charging of the secondary battery;
After charging of the secondary battery is stopped by the charging stop step, calculating a change amount per time of the measured potential measured at the reference electrode, and monitoring a charging state of the secondary battery based on the change amount And a charging state monitoring method.
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JP2016143452A (en) * 2015-01-29 2016-08-08 日産自動車株式会社 Lithium ion secondary battery
WO2018141723A1 (en) 2017-02-06 2018-08-09 Lithium Energy and Power GmbH & Co. KG Energy storage system and charge method
JP2019050168A (en) * 2017-09-12 2019-03-28 日立化成株式会社 Secondary battery and power source system
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