JP2017091804A - Method for analyzing lithium ion concentration distribution in lithium ion secondary battery electrode, and cell for evaluation - Google Patents
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本発明は、リチウムイオン二次電池の充放電中に生じる電極内のリチウムイオン濃度分布を分析する方法とその評価用セルに関する。 The present invention relates to a method for analyzing a lithium ion concentration distribution in an electrode generated during charging and discharging of a lithium ion secondary battery and a cell for evaluation thereof.
リチウムイオン二次電池を充放電する際には、電解質や電極材中に反応分布が生じることが知られている（非特許文献１参照）。この反応分布は、特に高速で充放電する場合に顕著となる。
反応分布が顕著である場合、電極内では局所的に過充電・過放電の状態となり、電池性能や安全性が低下する。そのため、充放電中に生じる電極内の反応分布を知ることができれば、電池性能劣化のメカニズムの解明等に繋がる新たな情報を取得できるようになる。
When charging and discharging a lithium ion secondary battery, it is known that a reaction distribution is generated in the electrolyte and the electrode material (see Non-Patent Document 1). This reaction distribution is particularly noticeable when charging and discharging at high speed.
When the reaction distribution is remarkable, the electrode is locally overcharged / overdischarged, and the battery performance and safety are lowered. Therefore, if the reaction distribution in the electrode that occurs during charging and discharging can be known, new information that leads to elucidation of the mechanism of battery performance deterioration and the like can be acquired.
しかしながら、電極中の活物質の種類にも依存するものの、多くの場合、充放電停止直後から電極中の反応分布が緩和する。そのため、充放電後に電池を解体して電極を取り出してから分析に供するのには、時間がかかりすぎて緩和してしまい、真の電極内の反応分布を観察することは困難である。 However, although depending on the type of active material in the electrode, in many cases, the reaction distribution in the electrode is relaxed immediately after charging and discharging are stopped. For this reason, it takes too much time to disassemble the battery after charging and discharging and take out the electrode for analysis, and it is difficult to observe the reaction distribution in the true electrode.
そこで、充放電中の電極内の反応分布を観察する方法として、ｉｎ−ｓｉｔｕ観察する方法（その場観察法）が報告されている（非特許文献２）。 Therefore, an in-situ observation method (in-situ observation method) has been reported as a method for observing the reaction distribution in the electrode during charge and discharge (Non-Patent Document 2).
しかしながら、その場観察法では、ＸＡＦＳ法による解析など、反応分布の分析に使用できる手法は限られている。また、リチウムイオン二次電池の充放電中に生じる電極中の反応分布は、放電後約数分で緩和して分布がほぼ無くなってしまうことから、通常行われる電池を解体してからの調査では、分布が無くなった状態となってしまい、充放電の最中に生じている分布を可視化することができない。 However, in-situ observation methods are limited in methods that can be used for analysis of reaction distribution, such as analysis by XAFS method. In addition, the reaction distribution in the electrode that occurs during charging and discharging of a lithium ion secondary battery relaxes in about a few minutes after the discharge and almost disappears. The distribution is lost, and the distribution generated during charging / discharging cannot be visualized.
そこで本発明者らは、充放電停止直後からの電極中の反応分布の緩和は、電極内のリチウムイオンの移動による濃度変化であると考え、充放電中に生じる電極内におけるリチウムイオン濃度分布を分析する新たな方法を提供することとした。
すなわち本発明の目的は、ＴＥＭ（透過型電子顕微鏡）、ＳＥＭ（走査型電子顕微鏡）、ＸＰＳ（Ｘ線光電子分光法）、ＸＲＤ（Ｘ線回折法）、ＩＣＰ−ＡＥＳ（高周波誘導結合プラズマ−発光分光分析法）、ＧＤ−ＯＥＳ（グロー放電発光分析法）等、多種多様な分析手法に適用可能な、リチウムイオン二次電池の電極内のリチウムイオン濃度分布を分析する方法を提供することである。
Therefore, the present inventors consider that the relaxation of the reaction distribution in the electrode immediately after stopping charging and discharging is a change in concentration due to the movement of lithium ions in the electrode, and the lithium ion concentration distribution in the electrode that occurs during charging and discharging is considered. We decided to provide a new way of analysis.
That is, the object of the present invention is to provide TEM (transmission electron microscope), SEM (scanning electron microscope), XPS (X-ray photoelectron spectroscopy), XRD (X-ray diffraction method), ICP-AES (high frequency inductively coupled plasma-luminescence). It is to provide a method for analyzing a lithium ion concentration distribution in an electrode of a lithium ion secondary battery, which can be applied to various analysis methods such as spectroscopic analysis method and GD-OES (glow discharge emission analysis method). .
本発明者らは、鋭意研究を重ねた結果、充電又は放電を停止してから１分以内に、リチウムイオンの移動に要する電解質のイオン伝導性を低下させることにより、リチウムイオン濃度分布の緩和を停止・抑制することにより、上記課題を解決できることを見出し、本発明を完成するに至った。 As a result of extensive research, the present inventors have reduced the ion ion conductivity of the electrolyte required for the movement of lithium ions within one minute after stopping charging or discharging, thereby reducing the lithium ion concentration distribution. The present inventors have found that the above-mentioned problems can be solved by stopping / suppressing and have completed the present invention.
すなわち、本発明は以下の［１］〜［６］に係るものである。
［１］ 電極及び電解質を含むリチウムイオン二次電池を充放電する工程と、
前記充放電する工程の任意の時点で充電又は放電を停止する工程と、
前記充電又は放電を停止してから１分以内に、前記電極におけるリチウムイオン濃度分布を保持する工程と、
前記電極におけるリチウムイオン濃度分布を保持した後の前記電極を取り出して分析に供する工程と、
を含む、リチウムイオン二次電池電極内のリチウムイオン濃度分布を分析する方法。
［２］ 前記リチウムイオン二次電池が単層ラミネートセルであり、
前記充放電する工程の前に露点−５０℃以下のドライ環境下で、前記単層ラミネートセルの外装を除去する工程と、前記外装を除去した単層ラミネートセルの正極、セパレータ及び負極の対を電解液に浸漬する工程と、を行い、
前記充放電する工程が、前記浸漬する工程で前記対が電解液に浸漬された状態で行われ、
前記電極におけるリチウムイオン濃度分布を保持する工程が、電極中の電解液を溶媒に置換することで行われる、前記［１］に記載のリチウムイオン二次電池電極内のリチウムイオン濃度分布を分析する方法。
［３］ 前記リチウムイオン二次電池が積層型構造又は巻回型構造のセルであり、
前記セルの外装には溶液のｉｎ−ｏｕｔ端子が設けられ、
前記電極におけるリチウムイオン濃度分布を保持する工程が、前記ｉｎ−ｏｕｔ端子を通じて電解液を溶媒に置換されることで行われる、前記［１］に記載のリチウムイオン二次電池電極内のリチウムイオン濃度分布を分析する方法。
［４］ 前記リチウムイオン二次電池が積層型構造又は巻回型構造のセルであり、
前記電極におけるリチウムイオン濃度分布を保持する工程が、前記セルを液体窒素に浸漬する工程、その後前記冷却状態を保ったまま前記セルを露点−５０℃以下のドライ環境下で解体する工程、及び、次いで露点−５０℃以下のドライ環境下で前記解体したセルを常温に戻すと同時に、少なくとも前記電極を溶媒に浸漬することにより電解液を溶媒に置換する工程を含む、前記［１］又は［３］に記載のリチウムイオン二次電池電極内のリチウムイオン濃度分布を分析する方法。
［５］ 前記リチウムイオン二次電池が全固体型のセルであり、
前記電極におけるリチウムイオン濃度分布を保持する工程が、前記セルを加熱して前記電解質をイオン伝導性が１０−４Ｓ・ｃｍ−１以下の相に変態させることで行われる、前記［１］に記載のリチウムイオン二次電池電極内のリチウムイオン濃度分布を分析する方法。
［６］ 前記リチウムイオン二次電池が全固体型のセルであり、
前記電極におけるリチウムイオン濃度分布を保持する工程が、前記セルに外力を加えることで前記電解質にクラックを生じさせ、前記電解質のイオン伝導性を１０−４Ｓ・ｃｍ−１以下にすることで行われる、前記［１］に記載のリチウムイオン二次電池電極内のリチウムイオン濃度分布を分析する方法。
That is, the present invention relates to the following [1] to [6].
[1] charging and discharging a lithium ion secondary battery including an electrode and an electrolyte;
A step of stopping charging or discharging at an arbitrary point in the step of charging and discharging;
Maintaining the lithium ion concentration distribution in the electrode within one minute after stopping the charging or discharging;
Removing the electrode after maintaining the lithium ion concentration distribution in the electrode and subjecting it to analysis;
A method for analyzing a lithium ion concentration distribution in a lithium ion secondary battery electrode.
[2] The lithium ion secondary battery is a single-layer laminate cell,
Before the step of charging and discharging, in a dry environment having a dew point of −50 ° C. or lower, the step of removing the outer layer of the single-layer laminated cell, and the pair of the positive electrode, separator, and negative electrode of the single-layer laminated cell from which the outer layer has been removed Performing a step of immersing in an electrolytic solution,
The step of charging and discharging is performed in a state in which the pair is immersed in an electrolytic solution in the step of immersing,
The step of maintaining the lithium ion concentration distribution in the electrode is performed by replacing the electrolytic solution in the electrode with a solvent, and analyzing the lithium ion concentration distribution in the lithium ion secondary battery electrode according to [1]. Method.
[3] The lithium ion secondary battery is a cell having a stacked structure or a wound structure,
An in-out terminal for the solution is provided on the exterior of the cell,
The lithium ion concentration in the lithium ion secondary battery electrode according to [1], wherein the step of maintaining the lithium ion concentration distribution in the electrode is performed by replacing the electrolyte solution with a solvent through the in-out terminal. How to analyze the distribution.
[4] The lithium ion secondary battery is a cell having a stacked structure or a wound structure,
The step of maintaining the lithium ion concentration distribution in the electrode is a step of immersing the cell in liquid nitrogen, and then disassembling the cell in a dry environment having a dew point of −50 ° C. or lower while maintaining the cooling state, and Next, at the same time that the disassembled cell is returned to room temperature in a dry environment having a dew point of −50 ° C. or lower, and at least the electrode is immersed in the solvent to replace the electrolytic solution with the solvent, [1] or [3 ]. The method for analyzing the lithium ion concentration distribution in the lithium ion secondary battery electrode according to claim 1.
[5] The lithium ion secondary battery is an all solid state cell,
In the above [1], the step of maintaining the lithium ion concentration distribution in the electrode is performed by heating the cell to transform the electrolyte into a phase having an ion conductivity of 10 −4 S · cm −1 or less. A method for analyzing a lithium ion concentration distribution in the lithium ion secondary battery electrode described.
[6] The lithium ion secondary battery is an all-solid-type cell,
The step of maintaining the lithium ion concentration distribution in the electrode is performed by applying an external force to the cell to cause cracks in the electrolyte and setting the ion conductivity of the electrolyte to 10 −4 S · cm −1 or less. The method for analyzing the lithium ion concentration distribution in the lithium ion secondary battery electrode according to [1].
本発明によれば、ＴＥＭ、ＳＥＭ、ＸＰＳ、ＸＲＤ、ＩＣＰ−ＡＥＳ、ＧＤ−ＯＥＳ等の非常に多種多様な分析手法が適用可能となり、劣化メカニズムの解明、および電池特性の改善に繋がる新たな情報を取得することが可能となる。 According to the present invention, a very wide variety of analysis methods such as TEM, SEM, XPS, XRD, ICP-AES, and GD-OES can be applied, and new information that leads to elucidation of deterioration mechanisms and improvement of battery characteristics. Can be obtained.
以下、本発明を詳細に説明するが、本発明は以下の実施形態に限定されるものではなく、本発明の要旨を逸脱しない範囲において、任意に変形して実施することができる。 Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following embodiments, and can be arbitrarily modified without departing from the gist of the present invention.
本発明に係るリチウムイオン二次電池電極内のリチウムイオン濃度分布を分析する方法は、下記工程（ｂ）〜（ｅ）を含むことを特徴とする。
（ｂ）電極及び電解質を含むリチウムイオン二次電池を充放電する工程、
（ｃ）前記充放電する工程の任意の時点で充電又は放電を停止する工程、
（ｄ）前記充電又は放電を停止してから１分以内に、前記電極におけるリチウムイオン濃度分布を保持する工程、
（ｅ）前記電極におけるリチウムイオン濃度分布を保持した後の前記電極を取り出して分析に供する工程。
上記工程（ｂ）の前に（ａ）前準備を行う工程、が設けられていてもよい。
The method for analyzing the lithium ion concentration distribution in the lithium ion secondary battery electrode according to the present invention includes the following steps (b) to (e).
(B) charging and discharging a lithium ion secondary battery including an electrode and an electrolyte;
(C) a step of stopping charging or discharging at an arbitrary point in the step of charging and discharging;
(D) maintaining the lithium ion concentration distribution in the electrode within 1 minute after stopping the charging or discharging;
(E) A step of taking out the electrode after maintaining the lithium ion concentration distribution in the electrode and subjecting it to analysis.
Before the step (b), (a) a step of performing pre-preparation may be provided.
本発明におけるリチウムイオン二次電池は一般的に用いられるものであれば特に制限されない。
例えば、正極には正極活物質、導電助剤、バインダー等を含むことができる。正極活物質にはリチウム金属酸化物が挙げられ、リチウム以外に含まれていてもよい金属としては、Ｎｉ、Ｍｎ、Ｃｏ、Ｆｅ、Ａｌ等が挙げられる。導電助剤やバインダーにも一般的に用いられるものを用いることができる。
The lithium ion secondary battery in the present invention is not particularly limited as long as it is generally used.
For example, the positive electrode can contain a positive electrode active material, a conductive additive, a binder, and the like. Examples of the positive electrode active material include lithium metal oxides, and examples of the metal that may be contained in addition to lithium include Ni, Mn, Co, Fe, and Al. Commonly used conductive assistants and binders can also be used.
負極には負極活物質、導電助剤、バインダー等を含むことができる。負極活物質にはグラファイト、ハードカーボン、スズ系材料、ケイ素系材料、チタン酸系材料、ゲルマニウム系材料等が挙げられる。導電助剤やバインダーにも一般的に用いられるものを用いることができる。 The negative electrode can contain a negative electrode active material, a conductive aid, a binder and the like. Examples of the negative electrode active material include graphite, hard carbon, tin-based material, silicon-based material, titanate-based material, and germanium-based material. Commonly used conductive assistants and binders can also be used.
電解質はリチウムイオン伝導性を有するものであればよく、非水系電解液、ポリマー電解質、イオン液体電解質、固体電解質等が挙げられる。
さらに、電解質の種類によっては、セパレータを用いることが好ましい。また、集電体やガスケット、電極タブ（電極リード、電極端子）、絶縁材等、適宜公知の物を使用することができる。
The electrolyte is not particularly limited as long as it has lithium ion conductivity, and examples thereof include non-aqueous electrolytes, polymer electrolytes, ionic liquid electrolytes, and solid electrolytes.
Furthermore, it is preferable to use a separator depending on the type of electrolyte. Moreover, a well-known thing can be used suitably, such as a collector, a gasket, an electrode tab (electrode lead, electrode terminal), and an insulating material.
リチウムイオン二次電池の構造は特に制限されず、例えば単層ラミネートセル、積層ラミネートセル等の積層型構造のセル、角型セルや１８６５０型セル等の巻回型構造のセル、全固体型のセル、コイン型セル等が挙げられる。 The structure of the lithium ion secondary battery is not particularly limited. For example, a single layer laminate cell, a laminate type cell such as a laminate cell, a winding type cell such as a square cell or 18650 type cell, an all-solid type cell. Examples thereof include a cell and a coin-type cell.
工程（ｂ）の充放電する工程において、充電レート、放電レート、充電終止電圧、放電終止電圧、充放電温度等の充放電試験条件は、用いる正極材料、負極材料、電解質等や、試験目的に合わせて任意に定めることができる。 In the step of charging and discharging in step (b), the charge / discharge test conditions such as the charge rate, discharge rate, end-of-charge voltage, end-of-discharge voltage, and charge / discharge temperature are used for the positive electrode material, negative electrode material, electrolyte, etc. used for the test purpose. It can be determined arbitrarily.
工程（ｄ）のリチウムイオン濃度分布を保持する工程においては、セル内の電解液をイオン伝導性の無い溶媒に置換したり、電解質のイオン伝導性を１０−４Ｓ・ｃｍ−１以下に低下させたりすることで行われる。電解質のイオン伝導性がゼロでない場合は、該リチウムイオン濃度分布は極めて緩やかに緩和してしまうことから、該緩和が進まないうちに電極の取り出しと分析（工程（ｅ））を行うことが必要となる。
例えば電解質のイオン伝導性が１０−４Ｓ・ｃｍ−１オーダーである場合には、工程（ｄ）から１２時間以内に工程（ｅ）を行うことが好ましい。
In the step of maintaining the lithium ion concentration distribution in step (d), the electrolytic solution in the cell is replaced with a solvent having no ion conductivity, or the ion conductivity of the electrolyte is reduced to 10 −4 S · cm −1 or less. It is done by letting. When the ionic conductivity of the electrolyte is not zero, the lithium ion concentration distribution relaxes very slowly. Therefore, it is necessary to take out and analyze the electrode (step (e)) before the relaxation proceeds. It becomes.
For example, when the ionic conductivity of the electrolyte is on the order of 10 −4 S · cm −1 , the step (e) is preferably performed within 12 hours from the step (d).
工程（ｅ）における分析は、ＴＥＭ、ＳＥＭ、ＸＰＳ、ＸＲＤ、ＩＣＰ−ＡＥＳ、ＧＤ−ＯＥＳ等、多種多様な分析手法が適用できる。 For the analysis in the step (e), various analysis methods such as TEM, SEM, XPS, XRD, ICP-AES, and GD-OES can be applied.
＜単層ラミネートセル＞
リチウムイオン二次電池が単層ラミネートセルの場合には、工程（ｂ）の前に前準備を行う工程（ａ）を含むことが好ましい。
工程（ａ）として、露点−５０℃以下のドライ環境下で、前記単層ラミネートセルの外装を除去する工程（ａ１−１）と、前記外装を除去した単層ラミネートセルの正極、セパレータ及び負極の対を電解液に浸漬する工程（ａ１−２）とを含む工程（ａ１）が好ましい。
<Single layer laminate cell>
In the case where the lithium ion secondary battery is a single layer laminate cell, it is preferable to include a step (a) for preparing before the step (b).
As a step (a), in a dry environment having a dew point of −50 ° C. or less, a step (a1-1) of removing the outer layer of the single-layer laminate cell, and a positive electrode, a separator, and a negative electrode of the single-layer laminate cell from which the outer layer has been removed The step (a1) including the step (a1-2) of immersing the pair in an electrolytic solution is preferable.
工程（ａ１）は、リチウムイオン二次電池を構成するリチウムが空気中の酸素と反応して変質しないために、露点−５０℃以下のドライ環境下で行うことが好ましい。露点−５０℃とは、水分量（容量）０．００３９％に相当する。露点は−６０℃以下がより好ましい。
また、リチウムは窒素とも反応することから、該ドライ環境はＡｒ雰囲気のグローブボックス内等で行うことが好ましい。以下、本明細書においてドライ環境とは、上記と同じ意味を表す。
The step (a1) is preferably performed in a dry environment having a dew point of −50 ° C. or lower so that lithium constituting the lithium ion secondary battery does not deteriorate due to reaction with oxygen in the air. A dew point of −50 ° C. corresponds to a water content (volume) of 0.0039%. The dew point is more preferably −60 ° C. or lower.
Since lithium also reacts with nitrogen, the dry environment is preferably performed in a glove box in an Ar atmosphere. Hereinafter, in this specification, the dry environment represents the same meaning as described above.
工程（ａ１−１）では露点−５０℃以下のドライ環境下で単層ラミネートセルの外装を除去するが、単層ラミネートセルが短絡しなければ、どのように除去してもよい。例えば、単層ラミネートセルの外装をハサミ等で切って開封し、除去してもよい。 In the step (a1-1), the exterior of the single-layer laminate cell is removed under a dry environment having a dew point of −50 ° C. or less. However, if the single-layer laminate cell is not short-circuited, it may be removed in any way. For example, the exterior of the single-layer laminate cell may be cut with scissors or the like, opened, and removed.
工程（ａ１−２）では露点−５０℃以下のドライ環境下で、外装を除去した単層ラミネートセルの正極、セパレータ及び負極の対を電解液に浸漬する。図１に示したように、電解液に浸漬する際、正極１、セパレータ２及び負極３の対をセラミック板６で挟み、拘束することが好ましい。これは、セラミック板の重みによって電解液４から前記対が浮くことを防止でき、さらには接触抵抗を低減することができるためである。 In the step (a1-2), in a dry environment having a dew point of −50 ° C. or lower, the pair of the positive electrode, separator, and negative electrode of the single-layer laminate cell from which the exterior has been removed is immersed in the electrolyte. As shown in FIG. 1, when immersed in an electrolytic solution, a pair of the positive electrode 1, the separator 2, and the negative electrode 3 is preferably sandwiched and restrained by a ceramic plate 6. This is because the pair can be prevented from floating from the electrolyte solution 4 due to the weight of the ceramic plate, and the contact resistance can be reduced.
工程（ａ１）の後、正極及び負極に繋がる各電極タブ５をそれぞれ充放電装置に接続し、続く充放電する工程（ｂ）を行う。 After the step (a1), each electrode tab 5 connected to the positive electrode and the negative electrode is connected to the charge / discharge device, and the subsequent charge / discharge step (b) is performed.
充放電する工程（ｂ）として、前記工程（ａ１−２）で前記対が電解液に浸漬された状態で行われる工程（ｂ１）が好ましい。この工程（ｂ１）も露点−５０℃以下のドライ環境下で行われることが好ましい。 As the step (b) of charging / discharging, the step (b1) performed in the state where the pair is immersed in the electrolytic solution in the step (a1-2) is preferable. This step (b1) is also preferably performed in a dry environment having a dew point of −50 ° C. or lower.
工程（ｂ１）の任意の時点で充電又は放電を停止する工程（ｃ）を経た後、前記充電又は放電を停止してから１分以内に、前記電極におけるリチウムイオン濃度分布を保持する（工程（ｄ））。単層ラミネートセルにおいては、工程（ｄ）として、電極中の電解液を、充電又は放電を停止してから１分以内に、溶媒に置換することで工程（ｄ１）が行われる。
工程（ｄ１）は電極のみを溶媒に浸漬してもよく、正極、セパレータ及び負極の対を溶媒に浸漬してもよく、図１における電解液４全体を溶媒に入れ替えてもよい。
電極中の電解液を置換する溶媒は、イオン伝導性が無いものが好ましく、ジメチルカーボネート（ＤＭＣ）、ジエチルカーボネート（ＤＥＣ）、エチルメチルカーボネート（ＥＭＣ）、ジメチルエーテル（ＤＭＥ）等が好ましく挙げられる。
After passing through the step (c) of stopping charging or discharging at an arbitrary time point in the step (b1), the lithium ion concentration distribution in the electrode is maintained within one minute after stopping the charging or discharging (step (step (b)) d)). In the single-layer laminate cell, as the step (d), the step (d1) is performed by replacing the electrolytic solution in the electrode with a solvent within 1 minute after stopping the charging or discharging.
In the step (d1), only the electrode may be immersed in the solvent, the pair of the positive electrode, the separator and the negative electrode may be immersed in the solvent, or the entire electrolyte solution 4 in FIG.
The solvent that replaces the electrolytic solution in the electrode is preferably one having no ionic conductivity, and preferred examples include dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and dimethyl ether (DME).
通常、充電又は放電を停止させた直後から、電極内におけるリチウムイオン濃度分布は緩和する。そこで、本発明においては、該電解液をイオン伝導性の低い溶媒に置換して溶液に含まれるリチウム塩(溶質)を溶媒にて希釈することにより、イオン伝導性を限りなくゼロに近付け、電極内のリチウムイオンを移動できなくする。これによりリチウムイオン濃度の緩和を抑制できるようになり、充放電中の電極内におけるリチウムイオン濃度分布を分析することができるようになる。 Usually, the lithium ion concentration distribution in the electrode is relaxed immediately after the charging or discharging is stopped. Therefore, in the present invention, by replacing the electrolytic solution with a solvent having low ion conductivity and diluting the lithium salt (solute) contained in the solution with the solvent, the ion conductivity is brought to zero as much as possible, and the electrode The lithium ion in the inside cannot be moved. Thereby, relaxation of the lithium ion concentration can be suppressed, and the lithium ion concentration distribution in the electrode during charging and discharging can be analyzed.
単層ラミネートセルにおいて、上記工程（ａ１）を経て工程（ｂ１）を行うことにより、工程（ｅ）において電極を取り出す際には既に外装がないことから、セルを解体する手間なく電極を直接取り出すことができる。 In the single-layer laminate cell, by performing the step (b1) through the step (a1), there is no exterior when the electrode is taken out in the step (e), so that the electrode is taken out directly without the trouble of disassembling the cell. be able to.
＜積層型構造、巻回型構造＞
リチウムイオン二次電池が積層型構造又は巻回型構造のセルの場合には、工程（ｂ）の前に前準備を行う工程（ａ２）を含むことが好ましい。
工程（ａ２）として、セルの外装に溶液のｉｎ−ｏｕｔ端子を設けることが好ましい。該ｉｎ−ｏｕｔ端子のｉｎ端子から所望の液体（溶媒）を流入し、セル内の電解液をｏｕｔ端子から排出することにより、電解液を該溶媒に置換することができる。
すなわち、前記工程（ａ２）を行うことにより、工程（ｄ）である電極におけるリチウムイオン濃度分布を保持する工程を、電解液を溶媒に置換する（工程（ｄ２））ことで行うことができるようになる。
<Laminated structure, wound structure>
In the case where the lithium ion secondary battery is a cell having a laminated structure or a wound structure, it is preferable to include a step (a2) of preparing before the step (b).
As the step (a2), it is preferable to provide an in-out terminal of the solution on the exterior of the cell. By flowing a desired liquid (solvent) from the in terminal of the in-out terminal and discharging the electrolytic solution in the cell from the out terminal, the electrolytic solution can be replaced with the solvent.
That is, by performing the step (a2), the step of maintaining the lithium ion concentration distribution in the electrode, which is the step (d), can be performed by replacing the electrolytic solution with a solvent (step (d2)). become.
ｉｎ−ｏｕｔ端子を設ける際は、元々溶液のｉｎ−ｏｕｔ端子が付いたセルを作製しても、セルにｉｎ−ｏｕｔ端子を後付けしてもよい。ｉｎ−ｏｕｔ端子を後付けする場合には、ドライ環境下で工程（ａ２）を行うことが好ましい。
ｉｎ端子からの溶媒の流入量やｏｕｔ端子からの排出量は特に限定されない。工程（ｄ２）において電解液を置換する溶媒は、イオン伝導性が無いものが好ましく、先の＜単層ラミネートセル＞における工程（ｄ１）と同様の溶媒を用いることができる。
When the in-out terminal is provided, a cell with an in-out terminal of the solution may be originally produced or the cell may be retrofitted with the in-out terminal. When the in-out terminal is retrofitted, the step (a2) is preferably performed in a dry environment.
The inflow amount of the solvent from the in terminal and the discharge amount from the out terminal are not particularly limited. The solvent that replaces the electrolytic solution in the step (d2) preferably has no ion conductivity, and the same solvent as in the step (d1) in the previous <single-layer laminate cell> can be used.
工程（ｅ）において電極を取り出す際、前記工程（ｄ２）でイオン伝導性を有する電解液は除去されており、電極におけるリチウムイオン濃度分布を保持できていることから、電極を取り出すためのセルの解体に長時間を要してもよい。 When the electrode is taken out in the step (e), the electrolyte solution having ion conductivity is removed in the step (d2), and the lithium ion concentration distribution in the electrode can be maintained. It may take a long time to dismantle.
また、積層型構造又は巻回型構造のセルにおいて、工程（ｄ）である電極におけるリチウムイオン濃度分布を保持する工程を、セルを液体窒素に浸漬する工程（ｄ３−１）、その後前記冷却状態を保ったまま前記セルを露点−５０℃以下のドライ環境下で解体する工程（ｄ３−２）及び次いで露点−５０℃以下のドライ環境下で前記解体したセルを常温に戻すと同時に、少なくとも前記電極を溶媒に浸漬することにより電解液を溶媒に置換する工程（ｄ３−３）を含む工程（ｄ３）とすることも好ましい。
該工程（ｄ３）は、上記工程（ａ２）及び工程（ｄ２）と共に行ってもよく、独立して行ってもよい。
Further, in a cell having a stacked structure or a wound structure, the step of maintaining the lithium ion concentration distribution in the electrode, which is the step (d), the step of immersing the cell in liquid nitrogen (d3-1), and then the cooling state The step (d3-2) of disassembling the cell in a dry environment having a dew point of −50 ° C. or lower while maintaining the temperature, and then returning the disassembled cell to a room temperature in a dry environment having a dew point of −50 ° C. or lower. It is also preferable to set it as the process (d3) including the process (d3-3) which replaces electrolyte solution with a solvent by immersing an electrode in a solvent.
The step (d3) may be performed together with the step (a2) and the step (d2), or may be performed independently.
工程（ｄ３−１）は、セル内の電解質のイオン伝導性を低下させるために行う。しかしセル内の電解質のイオン伝導性や冷却された電解質の温度を正確に測定するのは難しいため、セル全体を液体窒素に浸漬することで冷却すればよい。
電解液の種類によって低温時のイオン伝導性が大きく異なることから、セル全体の好ましい温度は一義に定義できない。例えば、電解液として１Ｍ ＬｉＰＦ６／ＥＣ：ＤＥＣ＝１：１（ｖｏｌ．）を用いる場合にはセルの温度を−２０℃以下とすると電解液が凝固するため好ましく、−５０℃以下とするとイオン伝導性がより低下するためにより好ましい。
セルの冷却は、液体窒素と同程度かそれ以上の冷却能があれば可能であり、液体窒素に代えて、例えば液体ヘリウム等を用いてもよい。
Step (d3-1) is performed in order to reduce the ionic conductivity of the electrolyte in the cell. However, since it is difficult to accurately measure the ionic conductivity of the electrolyte in the cell and the temperature of the cooled electrolyte, the entire cell may be cooled by being immersed in liquid nitrogen.
Since the ionic conductivity at a low temperature varies greatly depending on the type of the electrolytic solution, the preferable temperature of the entire cell cannot be defined uniquely. For example, when 1 M LiPF 6 / EC: DEC = 1: 1 (vol.) Is used as the electrolytic solution, the cell temperature is preferably −20 ° C. or lower because the electrolytic solution is solidified. It is more preferable because the conductivity is further lowered.
The cell can be cooled as long as it has a cooling capability equivalent to or higher than that of liquid nitrogen. Instead of liquid nitrogen, for example, liquid helium may be used.
工程（ｄ３−２）では、冷却状態を保ったままセルを解体する。ここで「冷却状態を保つ」とは、電解液のイオン伝導度が低い温度、又は電解液が凝固している状態を保ったまま、セルを解体することを意味する。セルの解体はセルのすべてが解体されていなくともよく、続く工程（ｄ３−３）で電極内の電解液を溶媒に置換（溶媒で希釈）できる程度に部分的に解体されていればよい。
その後工程（ｄ３−３）で、解体したセルを常温に戻すと同時に、前記解体したセルのうち、少なくとも前記電極を溶媒に浸漬することにより、電極内の電解液を溶媒に置換する。工程（ｄ３−３）において電解液を置換する溶媒は、イオン伝導性が無いものが好ましく、先の＜単層ラミネートセル＞における工程（ｄ１）と同様の溶媒を用いることができる。
In the step (d3-2), the cell is disassembled while keeping the cooling state. Here, “keep the cooling state” means that the cell is disassembled while maintaining the temperature at which the ionic conductivity of the electrolytic solution is low or the electrolytic solution is solidified. The cell may not be completely disassembled as long as it is partially disassembled to such an extent that the electrolytic solution in the electrode can be replaced with a solvent (diluted with a solvent) in the subsequent step (d3-3).
Thereafter, in step (d3-3), the disassembled cell is returned to room temperature, and at the same time, at least the electrode of the disassembled cell is immersed in a solvent to replace the electrolytic solution in the electrode with the solvent. The solvent that replaces the electrolytic solution in the step (d3-3) preferably has no ion conductivity, and the same solvent as in the step (d1) in the previous <single-layer laminate cell> can be used.
＜全固体型＞
リチウムイオン二次電池が全固体型のセルの場合、電解質も固体であることから、工程（ｄ）として、電解質を溶媒で置換することが難しい。そこで、工程（ｄ）である電極におけるリチウムイオン濃度分布を保持する工程を、セルを加熱して前記電解質をイオン伝導性が好ましくは１０−４Ｓ・ｃｍ−１以下の相に変態させる（工程（ｄ４））ことにより、リチウムイオン濃度分布を保持することが好ましい。なお、加熱はセルごと行われるので、加熱雰囲気は密閉雰囲気となる。また、加熱温度は電解質の種類によって適宜設定する。
<All solid type>
When the lithium ion secondary battery is an all-solid type cell, the electrolyte is also solid, so that it is difficult to replace the electrolyte with a solvent as the step (d). Therefore, in the step of maintaining the lithium ion concentration distribution in the electrode, which is step (d), the cell is heated to transform the electrolyte into a phase having an ion conductivity of preferably 10 −4 S · cm −1 or less (step) (D4)) Thus, it is preferable to maintain the lithium ion concentration distribution. In addition, since heating is performed for each cell, the heating atmosphere is a sealed atmosphere. The heating temperature is appropriately set depending on the type of electrolyte.
また、全固体型のセルにおいては、工程（ｄ）として、セルに外力を加えることで電解質にクラックを生じさせ、イオン伝導のパスを減少させ（工程（ｄ５））、リチウムイオン濃度分布を保持することも好ましい。
電解質が固体であることから、外力を加えてクラックが発生すると、その部分のイオン伝導のパスが失われる。具体的には、電解質のイオン伝導性が１０−４Ｓ・ｃｍ−１以下となるほどにイオン伝導のパスを減少させることが好ましい。
In the all-solid-state cell, as the step (d), an external force is applied to the cell to cause cracks in the electrolyte, reduce the ion conduction path (step (d5)), and maintain the lithium ion concentration distribution. It is also preferable to do.
Since the electrolyte is solid, when an external force is applied and a crack is generated, the ion conduction path in that portion is lost. Specifically, it is preferable to reduce the ion conduction path so that the ionic conductivity of the electrolyte is 10 −4 S · cm −1 or less.
セルに加える外力としては、ラミネートセルごと折り曲げたり、セルを圧潰する等の物理的力等が挙げられる。 Examples of the external force applied to the cell include a physical force such as bending the laminate cell or crushing the cell.
工程（ｄ４）及び工程（ｄ５）は、セルが破壊されない限り電解質がセルの密閉空間内に留まることから、必ずしもドライ環境下で行われる必要はないが、その後の工程（ｅ）における電極の取り出しやそれに伴うセルの解体、分析は露点−５０℃以下のドライ環境下で行う。 The step (d4) and the step (d5) do not necessarily have to be performed in a dry environment because the electrolyte remains in the sealed space of the cell unless the cell is destroyed. In addition, cell disassembly and analysis accompanying it are performed in a dry environment with a dew point of -50 ° C or lower.
以下に、実施例及び比較例を挙げて本発明をさらに具体的に説明するが、本発明は、これらの実施例に限定されるものではなく、その趣旨に適合し得る範囲で変更を加えて実施することも可能であり、それらはいずれも本発明の技術的範囲に包含される。
［単層ラミネートセルの作製］
活物質（ＬｉＮｉ１／３Ｍｎ１／３Ｃｏ１／３Ｏ２（ＮＭＣ））、導電助剤（アセチレンブラック）及びバインダー（ポリフッ化ビニリデン（ＰＶＤＦ））を重量比８６：７：７で混練し、溶媒としてＮＭＰ（Ｎ−メチル−２−ピロリドン）を用い、集電体である４５×４５ｍｍのＡｌ箔上に塗布、８０℃で１２時間真空乾燥させて正極を作製した。ロールプレスにて２．５ｇ／ｃｃの密度とした。
活物質（グラファイト）、導電助剤（アセチレンブラック）及びバインダー（ＰＶＤＦ）を重量比８６：７：７で混練し、溶媒としてＮＭＰを用い、集電体である５０×５０ｍｍのＣｕ箔上に塗布、８０℃で１２時間真空乾燥させて負極を作製した。ロールプレスにて１．３ｇ／ｃｃの密度とした。
電解液は１Ｍ ＬｉＰＦ６／ＥＣ：ＤＥＣ＝１：１（ｖｏｌ．）を用いた。
得られた電極、電解液及びポリエチレン製の多孔質セパレータを用いて露点−５０℃以下のドライベンチ中で単層ラミネートセルを作製した。
Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples, and modifications are made within a range that can be adapted to the gist thereof. It is also possible to carry out and they are all included in the technical scope of the present invention.
[Production of single-layer laminate cell]
An active material (LiNi 1/3 Mn 1/3 Co 1/3 O 2 (NMC)), a conductive assistant (acetylene black) and a binder (polyvinylidene fluoride (PVDF)) are kneaded at a weight ratio of 86: 7: 7. Then, using NMP (N-methyl-2-pyrrolidone) as a solvent, it was applied on a 45 × 45 mm Al foil as a current collector and vacuum-dried at 80 ° C. for 12 hours to produce a positive electrode. The density was 2.5 g / cc with a roll press.
An active material (graphite), a conductive additive (acetylene black) and a binder (PVDF) are kneaded in a weight ratio of 86: 7: 7, and NMP is used as a solvent, and applied onto a 50 × 50 mm Cu foil as a current collector. The negative electrode was prepared by vacuum drying at 80 ° C. for 12 hours. The density was 1.3 g / cc with a roll press.
As the electrolytic solution, 1M LiPF 6 / EC: DEC = 1: 1 (vol.) Was used.
A single-layer laminate cell was produced in a dry bench having a dew point of −50 ° C. or lower using the obtained electrode, electrolytic solution, and polyethylene porous separator.
[リチウムイオン濃度分布の分析］
得られた単層ラミネートセルを下記条件で３サイクル充放電するコンディショニングを行った後、ドライ環境下（露点−５０℃以下）で外装を解体した。負極、セパレータ、正極が接したまま短絡しないように取り出し、バット中の電解液（１Ｍ ＬｉＰＦ６／ＥＣ：ＤＥＣ＝１：１（ｖｏｌ．））に浸漬させ、さらに正極と負極の外側をそれぞれセラミック板で押さえつけることにより拘束した。
（条件）
上限電圧 ４．２Ｖ
下限電圧 ２．７Ｖ
充放電レート ０．２Ｃ
測定温度 ２５℃
休止時間 １０分
[Analysis of lithium ion concentration distribution]
The resulting single-layer laminate cell was conditioned for 3 cycles of charging and discharging under the following conditions, and then the exterior was disassembled in a dry environment (dew point -50 ° C. or lower). Take out the anode, separator, and cathode so that they are not short-circuited, immerse them in the electrolyte solution (1M LiPF 6 / EC: DEC = 1: 1 (vol.)) In the bat, and then attach the outside of the cathode and anode to the ceramic. Restrained by pressing with a plate.
(conditions)
Upper limit voltage 4.2V
Lower limit voltage 2.7V
Charge / discharge rate 0.2C
Measurement temperature 25 ℃
10 minutes downtime
次いで、１０Ｃの放電レートにて充電率（ＳＯＣ）７５％まで放電させた。なお、１Ｃとは定電流放電（定電流充電）において、１時間で放電（充電）が終了する電流値を表し、１０Ｃとは、１／１０時間（０．１時間）で放電（充電）が終了する電流値を表す。
放電停止直後、１分以内に正極を取り出し、溶媒（ＤＥＣ）に浸漬することにより、正極中の電解液を除去し、リチウムイオン濃度分布の保持を行った。
その後正極を取り出してグロー放電発光分析法（ＧＤ−ＯＥＳ、（株）堀場製作所製 ＧＤ−Ｐｒｏｆｉｌｅｒ２）を用い、正極中の深さ方向リチウムイオン濃度分布を測定した。結果を図２の「Ｂｅｆｏｒｅ」に示す。（実施例１）
Next, the battery was discharged to a charge rate (SOC) of 75% at a discharge rate of 10C. In addition, 1C represents a current value at which discharge (charging) is completed in 1 hour in constant current discharge (constant current charging), and 10C is discharged (charged) in 1/10 hour (0.1 hour). Indicates the current value to end.
Immediately after the discharge was stopped, the positive electrode was taken out within 1 minute and immersed in a solvent (DEC) to remove the electrolytic solution in the positive electrode and maintain the lithium ion concentration distribution.
Thereafter, the positive electrode was taken out, and the lithium ion concentration distribution in the depth direction in the positive electrode was measured using glow discharge emission spectrometry (GD-OES, GD-Profiler 2 manufactured by Horiba, Ltd.). The result is shown in “Before” in FIG. Example 1
その後、ＧＤ−ＯＥＳ測定に供した正極を再度１Ｍ ＬｉＰＦ６／ＥＣ：ＤＥＣ＝１：１（ｖｏｌ．）の電解液に１時間浸漬した。これは、放電停止直後、正極中の電解液を除去せず、リチウムイオン濃度分布の保持ができていない（電解液の除去に時間がかかった）場合の模擬試験である。
その後、正極を溶媒（ＤＥＣ）に浸漬することにより、正極中の電解液を除去し、実施例１と同様にグロー放電発光分析法による深さ方向リチウムイオン濃度分布を測定した。結果を図２の「Ａｆｔｅｒ」に示す。（比較例１）
Thereafter, the positive electrode subjected to the GD-OES measurement was again immersed in an electrolyte solution of 1M LiPF 6 / EC: DEC = 1: 1 (vol.) For 1 hour. This is a simulation test in the case where the electrolyte solution in the positive electrode is not removed immediately after the discharge is stopped and the lithium ion concentration distribution cannot be maintained (it takes time to remove the electrolyte solution).
Then, the electrolyte solution in the positive electrode was removed by immersing the positive electrode in a solvent (DEC), and the lithium ion concentration distribution in the depth direction by glow discharge emission spectrometry was measured in the same manner as in Example 1. The results are shown in “After” in FIG. (Comparative Example 1)
その結果、充放電停止直後に電極内部から電解液を除去しないと電極の深さ方向のリチウムイオン濃度分布に大きな差が見られないのに対し（比較例１ Ａｆｔｅｒ）、充放電停止直後に電極内の電解液を溶媒に置換することで除去することにより、電極の深さ方向リチウムイオン濃度分布に大きな差が見られる（実施例１ Ｂｅｆｏｒｅ）ことが分かった。
すなわち、充電又は放電を停止してから１分以内に電極内の電解液を除去することにより、電極内のリチウムイオン濃度分布を保持（リチウムイオン濃度分布の緩和を抑制）することにより、充放電時の電極内のリチウムイオン濃度分布状態を維持できていると判断できる。
一方で、電解液除去に時間がかかる従来の調査方法では濃度分布の緩和が起こり、ほとんど充放電時の状態が考察できない状態になっていることが確認された。
As a result, there is no significant difference in the lithium ion concentration distribution in the depth direction of the electrode unless the electrolytic solution is removed from the inside of the electrode immediately after the charge / discharge stop (Comparative Example 1 After). It was found that a large difference was observed in the lithium ion concentration distribution in the depth direction of the electrode by removing the electrolyte solution by substituting the electrolyte solution with a solvent (Example 1 Before).
That is, by removing the electrolyte in the electrode within 1 minute after stopping the charge or discharge, the charge / discharge is maintained by maintaining the lithium ion concentration distribution in the electrode (suppressing the relaxation of the lithium ion concentration distribution). It can be judged that the lithium ion concentration distribution state in the electrode at that time can be maintained.
On the other hand, it was confirmed that the conventional investigation method, which takes time to remove the electrolyte, relaxed the concentration distribution, and the state at the time of charging / discharging could hardly be considered.
１ 正極
２ セパレータ
３ 負極
４ 電解液
５ 電極タブ
６ セラミック板
DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Separator 3 Negative electrode 4 Electrolyte 5 Electrode tab 6 Ceramic board
Claims (6)
前記充放電する工程の任意の時点で充電又は放電を停止する工程と、
前記充電又は放電を停止してから１分以内に、前記電極におけるリチウムイオン濃度分布を保持する工程と、
前記電極におけるリチウムイオン濃度分布を保持した後の前記電極を取り出して分析に供する工程と、
を含む、リチウムイオン二次電池電極内のリチウムイオン濃度分布を分析する方法。 Charging and discharging a lithium ion secondary battery including an electrode and an electrolyte; and
A step of stopping charging or discharging at an arbitrary point in the step of charging and discharging;
Maintaining the lithium ion concentration distribution in the electrode within one minute after stopping the charging or discharging;
Removing the electrode after maintaining the lithium ion concentration distribution in the electrode and subjecting it to analysis;
A method for analyzing a lithium ion concentration distribution in a lithium ion secondary battery electrode.
前記充放電する工程の前に露点−５０℃以下のドライ環境下で、前記単層ラミネートセルの外装を除去する工程と、前記外装を除去した単層ラミネートセルの正極、セパレータ及び負極の対を電解液に浸漬する工程と、を行い、
前記充放電する工程が、前記浸漬する工程で前記対が電解液に浸漬された状態で行われ、
前記電極におけるリチウムイオン濃度分布を保持する工程が、電極中の電解液を溶媒に置換することで行われる、請求項１に記載のリチウムイオン二次電池電極内のリチウムイオン濃度分布を分析する方法。 The lithium ion secondary battery is a single layer laminate cell,
Before the step of charging and discharging, in a dry environment having a dew point of −50 ° C. or lower, the step of removing the outer layer of the single-layer laminated cell, and the pair of the positive electrode, separator, and negative electrode of the single-layer laminated cell from which the outer layer has been removed Performing a step of immersing in an electrolytic solution,
The step of charging and discharging is performed in a state in which the pair is immersed in an electrolytic solution in the step of immersing,
The method of analyzing the lithium ion concentration distribution in the lithium ion secondary battery electrode according to claim 1, wherein the step of maintaining the lithium ion concentration distribution in the electrode is performed by substituting the electrolytic solution in the electrode with a solvent. .
前記セルの外装には溶液のｉｎ−ｏｕｔ端子が設けられ、
前記電極におけるリチウムイオン濃度分布を保持する工程が、前記ｉｎ−ｏｕｔ端子を通じて電解液を溶媒に置換されることで行われる、請求項１に記載のリチウムイオン二次電池電極内のリチウムイオン濃度分布を分析する方法。 The lithium ion secondary battery is a cell having a laminated structure or a wound structure,
An in-out terminal for the solution is provided on the exterior of the cell,
The lithium ion concentration distribution in the lithium ion secondary battery electrode according to claim 1, wherein the step of maintaining the lithium ion concentration distribution in the electrode is performed by replacing the electrolytic solution with a solvent through the in-out terminal. How to analyze.
前記電極におけるリチウムイオン濃度分布を保持する工程が、前記セルを液体窒素に浸漬する工程、その後前記冷却状態を保ったまま前記セルを露点−５０℃以下のドライ環境下で解体する工程、及び、次いで露点−５０℃以下のドライ環境下で前記解体したセルを常温に戻すと同時に、少なくとも前記電極を溶媒に浸漬することにより電解液を溶媒に置換する工程を含む、請求項１又は３に記載のリチウムイオン二次電池電極内のリチウムイオン濃度分布を分析する方法。 The lithium ion secondary battery is a cell having a laminated structure or a wound structure,
The step of maintaining the lithium ion concentration distribution in the electrode is a step of immersing the cell in liquid nitrogen, and then disassembling the cell in a dry environment having a dew point of −50 ° C. or lower while maintaining the cooling state, and Next, at the same time as returning the disassembled cell to room temperature in a dry environment having a dew point of -50 ° C. or lower, the method includes substituting the electrolyte solution with a solvent by immersing at least the electrode in the solvent. Of analyzing a lithium ion concentration distribution in a lithium ion secondary battery electrode.
前記電極におけるリチウムイオン濃度分布を保持する工程が、前記セルを加熱して前記電解質をイオン伝導性が１０−４Ｓ・ｃｍ−１以下の相に変態させることで行われる、請求項１に記載のリチウムイオン二次電池電極内のリチウムイオン濃度分布を分析する方法。 The lithium ion secondary battery is an all-solid-type cell,
The step of maintaining the lithium ion concentration distribution in the electrode is performed by heating the cell to transform the electrolyte into a phase having an ion conductivity of 10 −4 S · cm −1 or less. Of analyzing a lithium ion concentration distribution in a lithium ion secondary battery electrode.
前記電極におけるリチウムイオン濃度分布を保持する工程が、前記セルに外力を加えることで前記電解質にクラックを生じさせ、前記電解質のイオン伝導性を１０−４Ｓ・ｃｍ−１以下にすることで行われる、請求項１に記載のリチウムイオン二次電池電極内のリチウムイオン濃度分布を分析する方法。 The lithium ion secondary battery is an all-solid-type cell,
The step of maintaining the lithium ion concentration distribution in the electrode is performed by applying an external force to the cell to cause cracks in the electrolyte and setting the ion conductivity of the electrolyte to 10 −4 S · cm −1 or less. The method of analyzing the lithium ion concentration distribution in the lithium ion secondary battery electrode according to claim 1.
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