JP2017059343A - Evaluation method of member for lithium ion secondary battery - Google Patents

Evaluation method of member for lithium ion secondary battery Download PDF

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JP2017059343A
JP2017059343A JP2015181688A JP2015181688A JP2017059343A JP 2017059343 A JP2017059343 A JP 2017059343A JP 2015181688 A JP2015181688 A JP 2015181688A JP 2015181688 A JP2015181688 A JP 2015181688A JP 2017059343 A JP2017059343 A JP 2017059343A
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battery
lithium ion
separator
laminate
electrode
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誉子 笠井
Takako Kasai
誉子 笠井
加藤 真
Makoto Kato
真 加藤
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三菱製紙株式会社
Mitsubishi Paper Mills Ltd
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    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50Manufacturing or production processes characterised by the final manufactured product

Abstract

PROBLEM TO BE SOLVED: To provide a method for evaluating a member for a lithium ion secondary battery, by which the safety of lithium ion secondary battery's member can be evaluated in simply and conveniently without performing complicated works including the assembly of a lithium ion secondary battery, and the application of a mechanical stimulation.SOLUTION: A method for evaluating a member for a lithium ion secondary battery is arranged to include the steps of: applying a voltage from an external power source across electrodes of a laminate including the electrodes and a separator; and piercing a conductor through the electrodes, thereby causing a short circuit therebetween. In the method, a lithium ion secondary battery is used as the external power source.SELECTED DRAWING: Figure 1

Description

本発明は、リチウムイオン二次電池用部材の評価方法に関する。   The present invention relates to a method for evaluating a member for a lithium ion secondary battery.
近年、リチウムイオン二次電池(以下、単に「電池」と記す場合がある)の高容量化にともない、安全性が重大な問題になる傾向にある。リチウムイオン二次電池の安全性評価方法としては、強制内部短絡、釘刺試験、圧壊試験等が行われているが、これらの評価には一定の容量以上の電池を組む必要があり、試験できる環境も限られているため、作業が煩雑であり、1回の試験にかかるコストも大きいといった問題があった。   In recent years, with the increase in capacity of lithium ion secondary batteries (hereinafter sometimes simply referred to as “batteries”), safety tends to become a serious problem. As a safety evaluation method for lithium ion secondary batteries, forced internal short circuit, nail penetration test, crushing test, etc. are performed, but it is necessary to build a battery with a certain capacity or more for these evaluations, and it can be tested Since the environment is limited, there is a problem that the work is complicated and the cost for one test is high.
リチウムイオン二次電池用部材の安全性を評価する際、簡便な評価方法として部材自体の熱安定性を評価する方法がある。例えばセパレータでは、規定温度(例えば、120℃)における熱収縮率を測定し、代替指標とする方法(例えば、特許文献1参照)が行われている。また、電極では、充電後の活物質を取り出して、示差熱分析装置を用いて発熱開始温度を測定して評価する方法が行われている(例えば、特許文献2参照)。しかし、これらの方法では、熱のみに焦点が当てられており、短絡時の電池内部で起こる変動のうち一つの要因を評価しているに過ぎず、実際の電池の安全性を必ずしも反映しない問題があった。また、セパレータの耐熱性評価方法として、セパレータを弾性電極で挟み、短絡用の異物を入れて定電圧を印加する方法があるが(例えば、特許文献3参照)、実際の電池を用いて行った試験の結果との相関が、必ずしも十分でなかった。   When evaluating the safety of a member for a lithium ion secondary battery, there is a method for evaluating the thermal stability of the member itself as a simple evaluation method. For example, in a separator, a method of measuring a heat shrinkage rate at a specified temperature (for example, 120 ° C.) and using it as an alternative index (for example, see Patent Document 1) is performed. For the electrode, a method of taking out the active material after charging and measuring and evaluating the heat generation start temperature using a differential thermal analyzer is performed (for example, see Patent Document 2). However, these methods focus only on heat and only evaluate one factor of the fluctuations that occur inside the battery at the time of a short circuit, and do not necessarily reflect the actual battery safety. was there. In addition, as a method for evaluating the heat resistance of the separator, there is a method in which the separator is sandwiched between elastic electrodes, a foreign material for short-circuiting is applied, and a constant voltage is applied (for example, refer to Patent Document 3). Correlation with test results was not always sufficient.
特開2011−190307号公報JP 2011-190307 A 特開2008−123815号公報JP 2008-123815 A 特開2013−190220号公報JP2013-190220A
本発明は、上記事情を鑑みたものであって、リチウムイオン二次電池用部材の評価方法において、リチウムイオン二次電池を組み立て、機械的刺激を与えるといった煩雑な作業を行わなくても、リチウムイオン二次電池部材の安全性を簡便に評価することができるリチウムイオン二次電池用部材の評価方法を提供することにある。   The present invention has been made in view of the above circumstances, and in the method for evaluating a member for a lithium ion secondary battery, the lithium ion secondary battery can be assembled without performing complicated operations such as providing a mechanical stimulus. It is providing the evaluation method of the member for lithium ion secondary batteries which can evaluate the safety | security of an ion secondary battery member simply.
上記課題を解決するために鋭意研究した結果、
(1)電極とセパレータの積層体の電極間に外部電源から電圧を印加し電極間に導体を貫通して短絡させるリチウムイオン二次電池部材の評価方法であって、外部電源としてリチウムイオン二次電池を使用することを特徴とするリチウムイオン二次電池部材の評価方法、
(2)電極とセパレータを含む積層体が、リチウムイオン二次電池用の正極、負極、セパレータ及び電解液溶媒からなる(1)記載のリチウムイオン二次電池部材の評価方法、
を見出した。
As a result of earnest research to solve the above problems,
(1) A method for evaluating a lithium ion secondary battery member in which a voltage is applied from an external power source between electrodes of a laminate of an electrode and a separator and a conductor is passed between the electrodes and short-circuited. A method of evaluating a lithium ion secondary battery member, characterized by using a battery;
(2) The method for evaluating a lithium ion secondary battery member according to (1), wherein the laminate including the electrode and the separator comprises a positive electrode, a negative electrode, a separator, and an electrolyte solvent for a lithium ion secondary battery,
I found.
本発明のリチウムイオン二次電池用部材の評価方法を用いることで、リチウムイオン二次電池の短絡直後に起こる事象を実際のリチウムイオン二次電池を短絡させたときに近い状況で簡便に再現することができる。   By using the method for evaluating a member for a lithium ion secondary battery of the present invention, an event that occurs immediately after a short circuit of a lithium ion secondary battery can be easily reproduced in a situation close to when the actual lithium ion secondary battery is shorted. be able to.
本発明のリチウムイオン二次電池用部材の評価方法の一例を示す概略図である。It is the schematic which shows an example of the evaluation method of the member for lithium ion secondary batteries of this invention.
本発明は、電極とセパレータを含む積層体の電極間に外部電源から電圧を印加し電極間に導体を貫通して短絡させるリチウムイオン二次電池部材の評価方法(以下、「評価方法」と記す場合がある)であって、外部電源としてリチウムイオン二次電池を使用することを特徴とする。この特徴によって、リチウムイオン二次電池の短絡直後に起こる事象を、従来の技術よりも、実際のリチウムイオン二次電池を短絡させたときの状況に近い状況で簡便に再現することができるという有利な効果が得られる。すなわち、リチウムイオン二次電池以外の電源、例えば定電圧電源を外部電源として使用する従来の技術では、定電流又は定電圧を印加していたのに対し、リチウムイオン二次電池を外部電源として用いる本発明では、実際のリチウムイオン二次電池を短絡させたときに近い電圧、電流の変動の下で、短絡に起因する各種事象が進行するため、実際のリチウムイオン二次電池を短絡させたときの状況に近い状況を再現することができる。   The present invention relates to a method for evaluating a lithium ion secondary battery member (hereinafter referred to as “evaluation method”) in which a voltage is applied from an external power source between electrodes of a laminate including an electrode and a separator and a conductor is short-circuited between the electrodes. And a lithium ion secondary battery is used as an external power source. Due to this feature, an event that occurs immediately after a short circuit of a lithium ion secondary battery can be easily reproduced in a situation closer to the situation when an actual lithium ion secondary battery is shorted than the conventional technique. Effects can be obtained. That is, in a conventional technique using a power source other than a lithium ion secondary battery, for example, a constant voltage power source as an external power source, a constant current or a constant voltage is applied, whereas a lithium ion secondary battery is used as an external power source. In the present invention, since various events due to the short circuit proceed under fluctuations in voltage and current close to when the actual lithium ion secondary battery is short-circuited, when the actual lithium-ion secondary battery is short-circuited The situation close to the situation can be reproduced.
本発明における検討によれば、リチウムイオン二次電池に短絡が発生した場合に、当該電池が熱暴走に至るか否かは、短絡後0.5秒以内に短絡部で発生する熱量に大きく依存し、当該熱量は、短絡部にかかる電圧と短絡部を通じて流れる電流の積を、時間で積分することで求めることができる。熱量を計算しない場合でも、短絡部を通じて流れる電流が大きい程、また当該電流の継続時間が長い程、当該電池が熱暴走に至る可能性が高くなる傾向があり、この傾向に基づく半定量的な比較を行うだけでも十分に有用な情報を得ることができる。   According to the study in the present invention, when a short circuit occurs in a lithium ion secondary battery, whether or not the battery reaches thermal runaway largely depends on the amount of heat generated in the short circuit part within 0.5 seconds after the short circuit. And the said heat quantity can be calculated | required by integrating the product of the voltage applied to a short circuit part, and the electric current which flows through a short circuit part by time. Even when the amount of heat is not calculated, the larger the current flowing through the short-circuited part and the longer the duration of the current, the higher the possibility that the battery will run out of heat. Sufficiently useful information can be obtained simply by making a comparison.
本発明により、リチウムイオン二次電池部材(以下、「部材」と略記する場合がある)を評価するには、評価の対象とする部材と、比較の対象とする部材について本発明を実施し、短絡後0.5秒以内に短絡部で発生する熱量を前記の方法で求めて比較するか、又は簡易な方法として、短絡部を通じて流れる電流及び電流の継続時間を比較すれば良い。   In order to evaluate a lithium ion secondary battery member (hereinafter sometimes abbreviated as “member”) according to the present invention, the present invention is carried out on a member to be evaluated and a member to be compared. The amount of heat generated in the short circuit portion within 0.5 seconds after the short circuit is obtained and compared by the above method, or as a simple method, the current flowing through the short circuit portion and the duration of the current may be compared.
本発明においてリチウムイオン二次電池部材とは、リチウムイオン二次電池に用いられる正極、負極、セパレータ、又はこれらを構成する材料である。   In the present invention, the lithium ion secondary battery member is a positive electrode, a negative electrode, a separator, or a material constituting these used in a lithium ion secondary battery.
本発明により電極又は電極の材料を評価する場合、本発明の電極としては評価の対象となる正極又は負極を用いる。電極は、活物質をバインダーや導電助剤と共に金属箔上に塗工したものであり、電位の高い方を正極、低い方を負極とする。正極活物質としては、コバルト酸リチウム、マンガン酸リチウム、ニッケル酸リチウム、チタン酸リチウム、リチウムニッケルマンガン酸化物、リン酸鉄リチウムが用いられる。リン酸鉄リチウムは、更に、マンガン、クロム、コバルト、銅、ニッケル、バナジウム、モリブデン、チタン、亜鉛、アルミニウム、ガリウム、マグネシウム、ホウ素、ニオブから選ばれる1種以上の(半)金属との複合物でも良い。負極活物質としては、黒鉛やコークスなどの炭素材料、金属リチウム、アルミニウム、シリカ、スズ、ニッケル、鉛から選ばれる1種以上の金属とリチウムとの合金、SiO、SnO、Fe、WO、Nb、Li4/3Ti5/3等の金属酸化物、Li0.4CoNなどの窒化物が用いられる。バインダーとしては、例えば、ポリフッ化ビニリデン(PVdF)及びその誘導体、エチレン−アクリレート共重合物、フッ素系樹脂、スチレンブタジエンゴム(SBR)系樹脂、カルボキシメチルセルロース、ヒドロキシエチルセルロース、ポリビニルアルコールなどが挙げられる。導電助剤としては、カーボンブラック、アセチレンブラック、ケッチェンブラック、炭素繊維、導電性金属酸化物などが挙げられる。 When evaluating an electrode or an electrode material according to the present invention, a positive electrode or a negative electrode to be evaluated is used as the electrode of the present invention. The electrode is obtained by coating an active material on a metal foil together with a binder and a conductive auxiliary agent, with the higher potential as the positive electrode and the lower potential as the negative electrode. As the positive electrode active material, lithium cobaltate, lithium manganate, lithium nickelate, lithium titanate, lithium nickel manganese oxide, or lithium iron phosphate is used. The lithium iron phosphate is further a composite with one or more (semi) metals selected from manganese, chromium, cobalt, copper, nickel, vanadium, molybdenum, titanium, zinc, aluminum, gallium, magnesium, boron, and niobium. But it ’s okay. Examples of the negative electrode active material include carbon materials such as graphite and coke, alloys of one or more metals selected from lithium, aluminum, silica, tin, nickel, lead, and lithium, SiO, SnO, Fe 2 O 3 , WO 2 , metal oxides such as Nb 2 O 5 and Li 4/3 Ti 5/3 O 4 , and nitrides such as Li 0.4 CoN are used. Examples of the binder include polyvinylidene fluoride (PVdF) and derivatives thereof, ethylene-acrylate copolymer, fluorine resin, styrene butadiene rubber (SBR) resin, carboxymethyl cellulose, hydroxyethyl cellulose, and polyvinyl alcohol. Examples of the conductive assistant include carbon black, acetylene black, ketjen black, carbon fiber, and conductive metal oxide.
本発明の評価方法により、電極及び電極の材料以外の部材を評価する場合、電極としては前記の電極の他、金属箔を用いることもできる。   When the member other than the electrode and the electrode material is evaluated by the evaluation method of the present invention, a metal foil can be used as the electrode in addition to the electrode.
本発明において、評価の対象となるセパレータには、不織布、紙、微多孔フィルムなどが挙げられる。また、不織布、紙、微多孔フィルムを基材とし、無機粒子、有機粒子、有機ポリマー、無機ポリマー等の層を付与したセパレータや、無機粒子、有機粒子、有機ポリマー、無機ポリマー等の層を電極に直接形成させて電極とセパレータを複合化させた複合体を評価することもできる。   In the present invention, examples of the separator to be evaluated include nonwoven fabric, paper, and microporous film. In addition, separators with layers of inorganic particles, organic particles, organic polymers, inorganic polymers, etc., and layers of inorganic particles, organic particles, organic polymers, inorganic polymers, etc., as electrodes based on nonwoven fabric, paper, and microporous films It is also possible to evaluate a composite in which the electrode and the separator are combined and formed directly on the substrate.
本発明において、外部電源として使用するリチウムイオン二次電池は、評価の対象となる材料を適用しようとしている電池に類似した特性の電池であることが好ましい。容量としては、1500mAh以上のものが好ましい。短絡電流が流れた際、外部電源として使用しているリチウムイオン二次電池が大電流放電による発熱で熱暴走を起こす可能性があるため、外部短絡試験又は釘刺試験に合格した電池を使用することが好ましい。   In the present invention, the lithium ion secondary battery used as the external power source is preferably a battery having characteristics similar to those of the battery to which the material to be evaluated is applied. The capacity is preferably 1500 mAh or more. When a short-circuit current flows, a lithium ion secondary battery used as an external power supply may cause thermal runaway due to heat generated by a large current discharge. Use a battery that has passed the external short-circuit test or nail penetration test. It is preferable.
本発明において、電極間に貫通させる導体には、鉄、ステンレス、アルミ、銅などの金属からなる針、釘、刃などが挙げられる。導体の大きさや形状に特に制限はなく、電極間を貫通し短絡させることができれば良い。   In the present invention, examples of the conductor penetrating between the electrodes include needles, nails and blades made of metal such as iron, stainless steel, aluminum, and copper. There is no restriction | limiting in particular in the magnitude | size and shape of a conductor, What is necessary is just to be able to penetrate between electrodes and to make it short-circuit.
本発明において、積層体は、リチウムイオン二次電池用の正極、負極、セパレータ及び電解液溶媒からなることが好ましい。本発明において、積層体が電解液溶媒を含むことで、より実際の電池内で起こる事象に近い事象を再現できるためである。本発明において、電解液溶媒とは、リチウムイオン二次電池用電解液に用いられる溶媒であって、電解質を含まない。本発明において、積層体に電解液、すなわちヘキサフルオロリン酸リチウム等の電解質を加えた電解液溶媒を用いた場合、電池反応に起因する電流が流れ、電池反応に起因する電流と短絡に起因する電流との区別は困難であるため、事象の解析が困難になる。電解液溶媒としては、プロピレンカーボネート、エチレンカーボネート、ジメチルカーボネート、ジエチルカーボネート、ジメトキシエタン、ジメトキシメタン、ガンマブチロラクトン、エチルアセテート、エチルプロピオネート等が例示される。また、これらの混合溶媒を使用することもできる。   In this invention, it is preferable that a laminated body consists of a positive electrode for lithium ion secondary batteries, a negative electrode, a separator, and electrolyte solution solvent. This is because, in the present invention, an event closer to an event occurring in an actual battery can be reproduced by including an electrolyte solvent in the laminate. In the present invention, the electrolytic solution solvent is a solvent used for an electrolytic solution for a lithium ion secondary battery, and does not include an electrolyte. In the present invention, when an electrolyte, that is, an electrolyte solvent in which an electrolyte such as lithium hexafluorophosphate is added to the laminate, a current resulting from the battery reaction flows, resulting from a short circuit due to a current resulting from the battery reaction. Since it is difficult to distinguish from current, it is difficult to analyze events. Examples of the electrolyte solution solvent include propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, dimethoxyethane, dimethoxymethane, gamma butyrolactone, ethyl acetate, and ethyl propionate. Moreover, these mixed solvents can also be used.
図1は、本発明のリチウムイオン二次電池用部材の評価方法の一例を示す概略図である。本発明の評価方法は、外部電源として用いるリチウムイオン二次電池1と、これらをつなぎ、電圧の印加を制御するスイッチ2と、電極とセパレータを含む積層体3と、積層体3の電極間を短絡させる導体4、積層体3における短絡電流を測定するための電流計5、積層体の電極間電圧を測定する電圧計6からなる。積層体の電極と導体との間の電圧を測定する場合、電圧計をこれらにつないでも良い。積層体3は、正極3−1、セパレータ3−2、負極3−3を重ね合わせてなる。   FIG. 1 is a schematic view showing an example of a method for evaluating a member for a lithium ion secondary battery of the present invention. The evaluation method of the present invention includes a lithium ion secondary battery 1 used as an external power source, a switch 2 that connects these and controls voltage application, a laminate 3 that includes an electrode and a separator, and a gap between the electrodes of the laminate 3. It comprises a conductor 4 to be short-circuited, an ammeter 5 for measuring a short-circuit current in the laminate 3, and a voltmeter 6 for measuring a voltage between electrodes of the laminate. When measuring the voltage between the electrode of a laminated body and a conductor, you may connect a voltmeter to these. The laminate 3 is formed by stacking a positive electrode 3-1, a separator 3-2, and a negative electrode 3-3.
本発明の評価方法において、外部電源と積層体をつなぎ、電圧の印加を制御するスイッチ2は、外部電源として用いるリチウムイオン二次電池の短絡電流に耐えられる電流容量を持ったスイッチであることが好ましい。例えば、定格電流200A以上のナイフスイッチを用いることができる。また、ナイフスイッチ等の機械的スイッチに代え、MOSFET等の半導体スイッチを用いることもできる。また、これらの接続に使用する電線も、外部電源として用いるリチウムイオン二次電池の短絡電流に耐えられる瞬時許容電流を持った電線であることが好ましい。例えば、導体断面積が8mm以上の架橋ポリエチレン被覆電線を用いることができる。各部品の接続部はできるだけ接触抵抗を生じさせないように接続する必要がある。例えば、圧着端子を使用してネジ留めする等の方法で接続される。 In the evaluation method of the present invention, the switch 2 that connects the external power source and the laminate and controls the voltage application is a switch having a current capacity that can withstand the short-circuit current of the lithium ion secondary battery used as the external power source. preferable. For example, a knife switch having a rated current of 200 A or more can be used. Moreover, it can replace with mechanical switches, such as a knife switch, and can also use semiconductor switches, such as MOSFET. Moreover, it is preferable that the electric wire used for these connections is also an electric wire having an instantaneous allowable current that can withstand a short-circuit current of a lithium ion secondary battery used as an external power source. For example, a cross-linked polyethylene-coated electric wire having a conductor cross-sectional area of 8 mm 2 or more can be used. It is necessary to connect the connection portions of the respective components so as not to cause contact resistance as much as possible. For example, it connects by the method of screwing using a crimp terminal.
本発明を実施する場合、短絡電流による火花の発生や部材が燃焼することによるガスの発生が考えられるため、特に積層体に電解液溶媒を含ませる場合には、局所排気装置を備えた環境下で、耐火服等を着用して行うことが好ましい。   When carrying out the present invention, it is conceivable that sparks are generated due to short-circuit currents and gas is generated due to combustion of members. Therefore, particularly when an electrolyte solvent is included in the laminate, the environment is provided with a local exhaust device. Therefore, it is preferable to carry out by wearing fireproof clothing.
以下、実施例により本発明を更に詳しく説明するが、本発明は実施例に限定されるものではない。   EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to an Example.
<本発明による安全性評価>
実施例1
マンガン酸リチウム系正極3−1、被評価セパレータ3−2、人造黒鉛系負極3−3を順に積層し、これに電解液溶媒としてジエチルカーボネートを浸漬させて、リチウムイオン二次電池用の正極、負極、セパレータ及び電解液溶媒からなる積層体3を作製した。電極とセパレータの密着性を上げるため、積層体3を2枚のベークライト板で挟んで固定した。ベークライト板の中央には導体4を通すための穴を空けている。外部電源として公称容量10Ahのラミネート型リチウムイオン二次電池を用い、積層体3と外部電源1を定格電流200Aのカバースイッチ2で接続した。積層体3の電極間を貫通させる導体4として、直径3.4mmのステンレス製の釘を用い、電極間に電圧を印加したときの積層体の短絡電流と、積層体と電極との間における電圧を測定した。電圧を印加してから0.5秒間の積層体の短絡電流と積層体と電極との間における電圧から、短絡によって生じた熱量Jを、被評価セパレータ3−2の種類別に算出した。熱量Jが小さいものほど、リチウムイオン二次電池用部材としての安全性が高い。
<Safety evaluation according to the present invention>
Example 1
A lithium manganate-based positive electrode 3-1, an evaluated separator 3-2, an artificial graphite-based negative electrode 3-3 are laminated in this order, and diethyl carbonate is immersed therein as an electrolyte solvent, whereby a positive electrode for a lithium ion secondary battery, A laminate 3 made of a negative electrode, a separator, and an electrolyte solvent was produced. In order to improve the adhesion between the electrode and the separator, the laminate 3 was sandwiched and fixed between two bakelite plates. A hole is formed in the center of the bakelite plate for the conductor 4 to pass through. A laminated lithium ion secondary battery having a nominal capacity of 10 Ah was used as an external power source, and the laminate 3 and the external power source 1 were connected by a cover switch 2 having a rated current of 200 A. A stainless steel nail having a diameter of 3.4 mm is used as the conductor 4 penetrating between the electrodes of the laminate 3, and the short-circuit current of the laminate when a voltage is applied between the electrodes and the voltage between the laminate and the electrode Was measured. From the short-circuit current of the laminate for 0.5 seconds after the voltage was applied and the voltage between the laminate and the electrode, the amount of heat J generated by the short-circuit was calculated for each type of separator 3-2 to be evaluated. The smaller the amount of heat J, the higher the safety as a member for a lithium ion secondary battery.
実施例2
実施例1において、電解液溶媒を浸漬させずに、リチウムイオン二次電池用の正極、負極及びセパレータからなる積層体3を用いた以外は、同様の方法で評価を行った。
Example 2
In Example 1, it evaluated by the same method except having used the laminated body 3 which consists of a positive electrode for a lithium ion secondary battery, a negative electrode, and a separator, without immersing electrolyte solution solvent.
比較例
実施例1において、外部電源として直流電圧電源を使用し、積層体に4V定電圧を印加した以外は、同様の方法で評価を行った。
Comparative Example Evaluation was performed in the same manner as in Example 1, except that a DC voltage power source was used as the external power source and a 4 V constant voltage was applied to the laminate.
<実際の電池での釘刺試験による安全性評価>
ニッケル、コバルト、マンガンの三元系正極、グラファイト系負極、ヘキサフルオロリン酸リチウムのジエチルカーボネート:エチレンカーボネート混合溶媒(3:7v/v)電解液(1M)を用いた公称容量3Ahのラミネート型リチウムイオン二次電池を作製し、4.2Vで充電した。この電池の中央付近に直径4.5mmの釘を刺し、その後のセルの挙動を観察した。
<Safety evaluation by nail penetration test with actual battery>
Laminated lithium with a nominal capacity of 3 Ah using nickel, cobalt, manganese ternary positive electrode, graphite negative electrode, lithium hexafluorophosphate diethyl carbonate: ethylene carbonate mixed solvent (3: 7 v / v) electrolyte (1 M) An ion secondary battery was prepared and charged at 4.2V. A nail having a diameter of 4.5 mm was inserted near the center of the battery, and the behavior of the subsequent cell was observed.
各実施例及び比較例による各種被評価セパレータにおける安全性評価結果を、表1に比較して示す。被評価セパレータとしては、ポリオレフィン樹脂多孔膜、表面にアラミド塗工層を設けたポリオレフィン樹脂多孔膜、表面に無機粒子層を設けたポリオレフィン樹脂多孔膜、無機粒子層を設けた不織布を使用した。   Table 1 shows the safety evaluation results of various separators to be evaluated according to the examples and comparative examples. As the separator to be evaluated, a polyolefin resin porous film, a polyolefin resin porous film provided with an aramid coating layer on the surface, a polyolefin resin porous film provided with an inorganic particle layer on the surface, and a nonwoven fabric provided with an inorganic particle layer were used.
釘刺試験による安全性評価と本発明による安全性評価は良好な相関を示しており、釘刺試験で発火や発煙を起こした電池に使用していたセパレータは、本発明による評価では、電圧を印加してから0.5秒の間に生じた熱量が高くなっていた。特に実施例1では、積層体が正極、負極、セパレータ及び電解液溶媒からなるため、積層体の密着性が上がり、短絡電流が流れることによる導体の振動によるノイズが少なくなること、短絡電流自体が大きくなることから、被評価セパレータごとの差がより明確になっていた。   The safety evaluation by the nail penetration test and the safety evaluation by the present invention show a good correlation, and the separator used for the battery that ignited or smoked by the nail penetration test was evaluated with the voltage in the evaluation according to the present invention. The amount of heat generated in 0.5 seconds after application was high. Particularly in Example 1, since the laminate is composed of the positive electrode, the negative electrode, the separator, and the electrolyte solvent, the adhesion of the laminate is improved, noise due to the vibration of the conductor due to the flow of the short-circuit current is reduced, and the short-circuit current itself is reduced. Since it became large, the difference for every to-be-evaluated separator became clearer.
一方、比較例では、外部電源としてリチウムイオン二次電池ではなく、直流電圧電源を使用したため、定電圧での評価となり、短絡によって生じる電圧降下を反映していないこと、電源自体の電圧の立ち上がりがリチウムイオン二次電池を外部電源としたときに比べて遅いことから、被評価セパレータごとの差が表れにくく、リチウムイオン二次電池用部材の安全性評価としては不充分だった。具体的には、比較例において、表面に無機粒子層を設けたポリオレフィン樹脂多孔膜であるセパレータと、無機粒子層を設けた不織布であるセパレータとを比較した場合、後者の方における発熱量がやや大きかったものの、釘刺し試験においては、前者の方における事象がより激烈であった。   On the other hand, in the comparative example, a DC voltage power supply was used as an external power supply instead of a lithium ion secondary battery, so the evaluation was performed at a constant voltage, and the voltage drop caused by a short circuit was not reflected, and the voltage rise of the power supply itself was not Since it is slower than when a lithium ion secondary battery is used as an external power source, a difference for each separator to be evaluated hardly appears, which is insufficient for safety evaluation of a member for a lithium ion secondary battery. Specifically, in a comparative example, when a separator that is a polyolefin resin porous membrane having an inorganic particle layer provided on the surface thereof and a separator that is a nonwoven fabric provided with an inorganic particle layer are compared, the calorific value in the latter is somewhat higher. Although large, the events in the former were more intense in the nail penetration test.
本発明は、リチウムイオン二次電池用部材の研究開発時の安全性の評価に用いることができる。   The present invention can be used for safety evaluation during research and development of members for lithium ion secondary batteries.
1 外部電源として用いるリチウムイオン二次電池
2 スイッチ
3 電極とセパレータを含む積層体
3−1 正極
3−2 セパレータ
3−3 負極
4 導体
5 電流計
6 電圧計
DESCRIPTION OF SYMBOLS 1 Lithium ion secondary battery used as external power supply 2 Switch 3 Laminate body including electrode and separator 3-1 Positive electrode 3-2 Separator 3-3 Negative electrode 4 Conductor 5 Ammeter 6 Voltmeter

Claims (2)

  1. 電極とセパレータを含む積層体の電極間に外部電源から電圧を印加し電極間に導体を貫通して短絡させるリチウムイオン二次電池部材の評価方法であって、外部電源としてリチウムイオン二次電池を使用することを特徴とするリチウムイオン二次電池部材の評価方法。   An evaluation method of a lithium ion secondary battery member in which a voltage is applied from an external power source between electrodes of a laminate including an electrode and a separator and a conductor is passed between the electrodes to short-circuit the lithium ion secondary battery as an external power source. The evaluation method of the lithium ion secondary battery member characterized by using.
  2. 電極とセパレータを含む積層体が、リチウムイオン二次電池用の正極、負極、セパレータ及び電解液溶媒からなる請求項1記載のリチウムイオン二次電池部材の評価方法。   The method for evaluating a lithium ion secondary battery member according to claim 1, wherein the laminate including the electrode and the separator comprises a positive electrode, a negative electrode, a separator, and an electrolyte solvent for the lithium ion secondary battery.
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CN107742754A (en) * 2017-09-26 2018-02-27 深圳市曼晶创业投资咨询企业(有限合伙) A kind of state evaluating method of lithium titanate electrokinetic cell system
CN109959875A (en) * 2017-12-26 2019-07-02 丰田自动车株式会社 Evaluation method, the manufacturing method of appraisal tool and electric energy storage device of electric energy storage device
CN110148336A (en) * 2019-03-27 2019-08-20 北京航空航天大学 A kind of lithium ion battery charging process failure simulation method and device
WO2020189034A1 (en) * 2019-03-19 2020-09-24 株式会社Gsユアサ Simulation method, simulation device, and computer program

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107742754A (en) * 2017-09-26 2018-02-27 深圳市曼晶创业投资咨询企业(有限合伙) A kind of state evaluating method of lithium titanate electrokinetic cell system
CN109959875A (en) * 2017-12-26 2019-07-02 丰田自动车株式会社 Evaluation method, the manufacturing method of appraisal tool and electric energy storage device of electric energy storage device
CN109959875B (en) * 2017-12-26 2021-07-06 丰田自动车株式会社 Evaluation method and evaluation tool for power storage device, and method for manufacturing power storage device
WO2020189034A1 (en) * 2019-03-19 2020-09-24 株式会社Gsユアサ Simulation method, simulation device, and computer program
CN110148336A (en) * 2019-03-27 2019-08-20 北京航空航天大学 A kind of lithium ion battery charging process failure simulation method and device

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