JP2014085323A - Secondary battery inspection method - Google Patents

Secondary battery inspection method Download PDF

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JP2014085323A
JP2014085323A JP2012237165A JP2012237165A JP2014085323A JP 2014085323 A JP2014085323 A JP 2014085323A JP 2012237165 A JP2012237165 A JP 2012237165A JP 2012237165 A JP2012237165 A JP 2012237165A JP 2014085323 A JP2014085323 A JP 2014085323A
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secondary battery
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JP5880972B2 (en
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Seigo Nakamura
成吾 中村
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Toyota Motor Corp
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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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    • Y02E60/10—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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    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery inspection method which reduces inspection time and cost required for an inspection process, while enabling highly accurate inspection.SOLUTION: In a secondary battery inspection method, a discharge process for discharging a secondary battery 1 from an initial voltage Vs to a discharge end voltage Ve with a discharge current I is performed only once, to perform capacity inspection and output inspection of the secondary battery 1. The output inspection includes the steps of: measuring a first voltage drop amount ΔV1 from the start of the discharge process to the lapse of a predetermined time; measuring a second voltage drop amount ΔV2 from the time when a voltage of the secondary battery 1 reaches a voltage V2 to the time when the predetermined time T2 elapses; calculating electric conductivity of the secondary battery 1 from the discharge current I, the first voltage drop amount ΔV1, and the second voltage drop amount ΔV2; and comparing the calculated electric conductivity with a preset threshold to determine whether an output of the secondary battery 1 having a correlation with the electric conductivity is proper or not.

Description

本発明は、二次電池の検査工程において、二次電池の検査時間を短縮することができる二次電池の検査方法に関する。   The present invention relates to a secondary battery inspection method capable of shortening a secondary battery inspection time in a secondary battery inspection process.

従来、リチウムイオン二次電池などの二次電池を製造して出荷する際には、前記二次電池の容量や出力などの初期特性を検査工程にて検査することが行われている。
前記検査工程において、例えば二次電池の容量および出力の検査を行う際には、まず、初期充電を行って二次電池を活性化させる活性化処理や高温エージング処理の後に、二次電池を規定電圧まで放電して容量を測定する。その後、二次電池の温度調整および電圧（ＳＯＣ）調整を行い、規定電流で任意時間放電してＩＶ抵抗を測定することにより、二次電池の出力を測定していた。 Conventionally, when a secondary battery such as a lithium ion secondary battery is manufactured and shipped, initial characteristics such as capacity and output of the secondary battery are inspected in an inspection process.
In the inspection step, for example, when inspecting the capacity and output of the secondary battery, first, the secondary battery is defined after the activation process and the high-temperature aging process for activating the secondary battery by performing initial charging. Discharge to voltage and measure capacity. Thereafter, the temperature and voltage (SOC) of the secondary battery were adjusted, and the output of the secondary battery was measured by discharging the battery at a specified current for an arbitrary time and measuring the IV resistance.

また、特許文献１に示す二次電池の製造工程においては、二次電池に対して高温エージング処理や活性化処理を行った後に、所定時間の放置処理（第１のバッファ処理）を経たうえで電池容量の検査が行われる。その後、更に所定時間の放置処理（第２のバッファ処理）を行ったうえで、開路電圧（ＯＣＶ）の測定を行うとともに、電流容量値に応じて二次電池を選別して、二次電池を出荷することが行われていた。   Moreover, in the manufacturing process of the secondary battery shown in Patent Document 1, after the high-temperature aging process and the activation process are performed on the secondary battery, after being left for a predetermined time (first buffer process). A battery capacity check is performed. Then, after performing a standing process (second buffer process) for a predetermined time, the open circuit voltage (OCV) is measured, and the secondary battery is selected according to the current capacity value. Shipping was done.

特開平１０−２８９７２９号公報Japanese Patent Laid-Open No. 10-289729

前述のように、二次電池の容量測定および出力測定を行う検査工程においては、容量を測定するために行う放電と、出力を測定するために行う放電とを別々に実施していたため、多くの検査時間を要することとなっていた。
また、特許文献１に記載の検査工程においては、電池容量の検査を行った後に、放置処理や開路電圧の測定を行っているので、容量測定後に二次電池のＳＯＣ調整や温度調整を行う必要があり、検査工程に多くの時間を要することとなっていた。 As described above, in the inspection process for measuring the capacity of the secondary battery and measuring the output, the discharge performed for measuring the capacity and the discharge performed for measuring the output were performed separately. Inspection time was required.
In addition, in the inspection process described in Patent Document 1, after the battery capacity is inspected, the standing treatment and the open circuit voltage are measured. Therefore, it is necessary to perform SOC adjustment and temperature adjustment of the secondary battery after the capacity measurement. Therefore, a lot of time is required for the inspection process.

そこで、本発明においては、検査時間を短縮して検査工程に要するコストを削減しつつ、高精度な検査を行うことができる、二次電池の検査方法を提供するものである。   Therefore, the present invention provides a secondary battery inspection method capable of performing high-accuracy inspection while shortening the inspection time and reducing the cost required for the inspection process.

上記課題を解決する二次電池の検査方法は、以下の特徴を有する。
即ち、請求項１記載の如く、初期充電を終えた二次電池を所定の初期電圧Ｖｓから放電終了電圧Ｖｅまで、所定の放電電流Ｉにて放電する放電工程を、一度だけ行うことによって、前記二次電池の容量検査と出力検査とを行う二次電池の検査方法であって、前記出力検査は、前記放電工程の開始時から一定時間経過後までの前記二次電池の第一の電圧降下量ΔＶ１を測定する工程と、前記二次電池の電圧が、前記第一の電圧降下量ΔＶ１を測定した電圧よりも低い電圧である任意の電圧Ｖ２に到達した時点から、一定時間Ｔ２経過した時点までの第二の電圧降下量ΔＶ２を測定する工程と、前記放電電流Ｉ、第一の電圧降下量ΔＶ１、および第二の電圧降下量ΔＶ２から、前記二次電池の導電率を算出する工程と、算出した前記導電率を予め設定した閾値と比較することにより、前記導電率と相関を有する前記二次電池の出力の良否を判定する工程とを備える。 A secondary battery inspection method that solves the above-described problems has the following characteristics.
That is, as described in claim 1, by performing the discharging step of discharging the secondary battery, which has been initially charged, from the predetermined initial voltage Vs to the discharge end voltage Ve with the predetermined discharge current I only once, A secondary battery inspection method for performing a secondary battery capacity inspection and an output inspection, wherein the output inspection includes a first voltage drop of the secondary battery from the start of the discharge process until a predetermined time has elapsed. A step of measuring the amount ΔV1, and a time when a certain time T2 has elapsed from when the voltage of the secondary battery reaches an arbitrary voltage V2, which is a voltage lower than the voltage at which the first voltage drop amount ΔV1 is measured. Measuring the second voltage drop amount ΔV2 until calculating the electrical conductivity of the secondary battery from the discharge current I, the first voltage drop amount ΔV1, and the second voltage drop amount ΔV2. Pre-set the calculated conductivity A step of determining whether the output of the secondary battery having a correlation with the conductivity is good or bad by comparing with the threshold value.

また、請求項２記載の如く、前記容量検査は、前記初期電圧Ｖｓと放電終了電圧Ｖｅとの範囲内にて、所定の検査開始電圧Ｖａから、前記検査開始電圧Ｖａよりも低い検査終了電圧Ｖｂまでの区間を、区間容量の検査区間として設定し、前記放電工程における電流値Ｉ、および前記検査開始電圧Ｖａから検査終了電圧Ｖｂとなるまでの放電時間Ｔａから電流積算量を算出して、前記二次電池の区間容量を測定する工程と、測定した前記区間容量を予め設定した閾値と比較することにより、前記区間容量と相関を有する前記二次電池の全容量の良否を判定する工程とを備える。   According to a second aspect of the present invention, the capacity test is performed within a range of the initial voltage Vs and the discharge end voltage Ve from a predetermined test start voltage Va to a test end voltage Vb lower than the test start voltage Va. The interval up to is set as the inspection interval of the interval capacity, and the current integration amount is calculated from the current value I in the discharge process and the discharge time Ta from the inspection start voltage Va to the inspection end voltage Vb, Measuring a section capacity of the secondary battery, and comparing the measured section capacity with a preset threshold value to determine pass / fail of the total capacity of the secondary battery having a correlation with the section capacity. Prepare.

また、請求項３記載の如く、前記出力検査は、前記二次電池における−３０℃〜２５℃の範囲の出力について行う。   According to a third aspect of the present invention, the output inspection is performed for an output in a range of −30 ° C. to 25 ° C. in the secondary battery.

本発明によれば、二次電池の検査方法において、検査時間を短縮して検査工程に要するコストを削減しつつ、高精度な検査を行うことが可能となる。   According to the present invention, in a secondary battery inspection method, it is possible to perform a highly accurate inspection while shortening the inspection time and reducing the cost required for the inspection process.

本発明係る二次電池の検査方法の対象となる二次電池を示す斜視図である。It is a perspective view which shows the secondary battery used as the object of the inspection method of the secondary battery which concerns on this invention. 二次電池の検査方法のフローを示す図である。It is a figure which shows the flow of the inspection method of a secondary battery. 二次電池の放電曲線を用いた二次電池の区間容量の求め方を示す図である。It is a figure which shows how to obtain | require the area capacity of a secondary battery using the discharge curve of a secondary battery. 二次電池の放電曲線を用いた二次電池の導電率の求め方を示す図である。It is a figure which shows how to obtain | require the electrical conductivity of a secondary battery using the discharge curve of a secondary battery. 二次電池の全容量の保証値と基準区間容量との関係を示す図である。It is a figure which shows the relationship between the guaranteed value of the full capacity of a secondary battery, and a reference | standard area capacity. 二次電池の出力の保証値と基準導電率との関係を示す図である。It is a figure which shows the relationship between the guarantee value of the output of a secondary battery, and reference | standard conductivity. 区間容量検査開始電圧を３．６４Ｖ、区間容量検査終了電圧を３．３９Ｖとしたときの、区間容量と全容量との相関性を示す図である。It is a figure which shows the correlation of a section capacity | capacitance and a total capacity | capacitance when a section capacity test start voltage is 3.64V and a section capacity test end voltage is 3.39V. 放電開始から０．１秒経過後の電圧降下量ΔＶ１と、電池電圧が３．５４Ｖに達してから２００秒経過後の電圧降下量ΔＶ２との積算電圧降下量から算出した導電率と−３０℃での出力との相関性を示す図である。The conductivity calculated from the integrated voltage drop amount of the voltage drop amount ΔV1 after 0.1 seconds from the start of discharge and the voltage drop amount ΔV2 after 200 seconds after the battery voltage reaches 3.54 V, and −30 ° C. It is a figure which shows the correlation with the output in. 電圧Ｖ２と経過時間Ｔ１とを種々変化させた場合の、二次電池の導電率と、−３０℃での二次電池の出力との相関係数を示す図である。It is a figure which shows the correlation coefficient of the electrical conductivity of a secondary battery when the voltage V2 and elapsed time T1 are variously changed, and the output of the secondary battery at -30 degreeC. 電圧Ｖ２と経過時間Ｔ１とを種々変化させた場合の、二次電池の導電率と、２５℃での二次電池の出力との相関係数を示す図である。It is a figure which shows the correlation coefficient of the electrical conductivity of a secondary battery when the voltage V2 and elapsed time T1 are variously changed, and the output of the secondary battery at 25 degreeC.

次に、本発明を実施するための形態を、添付の図面を用いて説明する。   Next, modes for carrying out the present invention will be described with reference to the accompanying drawings.

図１に示す、本実施形態に係る二次電池の検査方法の対象となる二次電池１は、例えばリチウムイオン二次電池に構成されており、一面（上面）が開口した有底角筒形状のケース本体２１と、平板状に形成されケース本体２１の開口部を閉塞する蓋体２２とで構成される電池ケース２に、電解液とともに電極体３を収容して構成されている。   A secondary battery 1 that is a target of the secondary battery inspection method according to the present embodiment shown in FIG. 1 is configured as a lithium ion secondary battery, for example, and has a bottomed rectangular tube shape with one surface (upper surface) opened. A battery case 2 including a case body 21 and a lid body 22 that is formed in a flat plate shape and closes an opening of the case body 21, and the electrode body 3 is accommodated together with the electrolytic solution.

電池ケース２は、一面（上面）が開口した直方体状の有底角筒形状に形成されるケース本体２１の開口部を、平板状の蓋体２２にて閉塞した角型ケースに構成されている。
蓋体２２の長手方向一端部（図１における左端部）には正極端子４ａが設けられ、蓋体２２の長手方向他端部（図１における右端部）には負極端子４ｂが設けられている。 The battery case 2 is configured as a rectangular case in which an opening of a case body 21 formed in a rectangular parallelepiped bottomed rectangular tube shape with one surface (upper surface) opened is closed with a flat lid body 22. .
A positive electrode terminal 4a is provided at one end in the longitudinal direction of the lid 22 (left end in FIG. 1), and a negative electrode terminal 4b is provided at the other longitudinal end of the lid 22 (right end in FIG. 1). .

電極体３は、正極、負極、およびセパレータを、正極と負極との間にセパレータが介在するように積層し、積層した正極、負極、およびセパレータを巻回して扁平させることにより構成されている。なお、二次電池１における正極の正極活物質としては、例えばＬｉ（Ｎｉ、Ｍｎ、Ｃｏ）Ｏ2系活物質などの三元系活物質を用いることができる。 The electrode body 3 is configured by laminating a positive electrode, a negative electrode, and a separator so that the separator is interposed between the positive electrode and the negative electrode, and winding and flattening the laminated positive electrode, negative electrode, and separator. In addition, as a positive electrode active material of the positive electrode in the secondary battery 1, for example, a ternary active material such as a Li (Ni, Mn, Co) O 2 active material can be used.

電池ケース２に電極体３および電解液を収容して二次電池１を構成する際には、まず電極体３の正極および負極に、それぞれ蓋体２２の正極端子４ａおよび負極端子４ｂを接続して、電極体３を蓋体２２に組み付けて、蓋体サブアッシーを形成する。
その後、電極体３および電解液をケース本体２１内に収容するとともに、ケース本体２１の開口部に蓋体２２を嵌合して、蓋体２２とケース本体２１とを溶接により密封することにより、二次電池１を構成する。 When the secondary battery 1 is configured by accommodating the electrode body 3 and the electrolyte in the battery case 2, first, the positive electrode terminal 4 a and the negative electrode terminal 4 b of the lid body 22 are respectively connected to the positive electrode and the negative electrode of the electrode body 3. Then, the electrode body 3 is assembled to the lid body 22 to form a lid body sub-assembly.
Thereafter, the electrode body 3 and the electrolytic solution are accommodated in the case main body 21, the lid body 22 is fitted into the opening of the case main body 21, and the lid body 22 and the case main body 21 are sealed by welding, A secondary battery 1 is configured.

このように構成される二次電池１は、製造時の検査工程において、その初期特性である容量および出力の検査が行われる。
二次電池１の容量および出力の検査は、図２に示すフローのように、初期充電を終えた二次電池１を１度だけ放電させることにより行われる。
検査工程における二次電池１の容量および出力の検査方法について、以下に具体的に説明する。 The secondary battery 1 configured in this manner is subjected to inspection of capacity and output, which are initial characteristics, in an inspection process at the time of manufacture.
The capacity and output of the secondary battery 1 are inspected by discharging the secondary battery 1 that has been initially charged only once, as in the flow shown in FIG.
A method for inspecting the capacity and output of the secondary battery 1 in the inspection process will be specifically described below.

図３、図４に示すように、容量および出力の検査を行う際には、まず、初期充電を終えた二次電池１を所定の初期電圧Ｖｓ（例えば、４．０Ｖ）から、放電終了電圧Ｖｅ（例えば、２．５Ｖ）まで、所定の電流値Ｉ（例えば、２．４Ｃ）にて放電を行う（Ｓ０１）。
この場合、二次電池１の放電開始電圧（初期電圧Ｖｓ）は、３．６Ｖ〜４．１Ｖに設定することが好ましく、さらには３．９５Ｖ〜４．１Ｖに設定することがより好ましい。また、放電電流は、１Ｃ〜１０Ｃに設定することが好ましく、さらには２Ｃ〜６Ｃに設定することがより好ましい。また、検査温度は、１０℃〜４０℃に設定することが好ましく、さらには２０℃〜３０℃に設定することがより好ましい。
なお、図３、図４には二次電池１の放電曲線を示しており、横軸は時間を示し、縦軸は放電時電池電圧を示している。 As shown in FIGS. 3 and 4, when the capacity and output are inspected, first, the secondary battery 1 that has been initially charged is discharged from a predetermined initial voltage Vs (for example, 4.0 V) to a discharge end voltage. Discharge is performed at a predetermined current value I (eg, 2.4 C) up to Ve (eg, 2.5 V) (S01).
In this case, the discharge start voltage (initial voltage Vs) of the secondary battery 1 is preferably set to 3.6V to 4.1V, and more preferably set to 3.95V to 4.1V. The discharge current is preferably set to 1C to 10C, more preferably 2C to 6C. Moreover, it is preferable to set inspection temperature to 10 to 40 degreeC, and it is more preferable to set to 20 to 30 degreeC.
3 and 4 show discharge curves of the secondary battery 1, the horizontal axis shows time, and the vertical axis shows the battery voltage during discharge.

次に、図３に示すように、区間容量の検査区間として、区間容量検査開始電圧Ｖａおよび区間容量検査終了電圧Ｖｂ（Ｖａ＞Ｖｂ）を、初期電圧Ｖｓから放電終了電圧Ｖｅの範囲内にて設定し、前記ステップＳ０１にて放電した際の放電電流値Ｉ、および二次電池１が区間容量検査開始電圧Ｖａの状態にある区間容量検査開始時刻ｔａから、区間容量検査終了電圧Ｖｂの状態にある区間容量検査終了時刻ｔｂまでの放電時間Ｔａを用いて、二次電池１の区間容量を算出する（Ｓ０２）。
具体的には、前記放電電流値Ｉと放電時間Ｔａとを用いて、区間容量検査開始電圧Ｖａから区間容量検査終了電圧Ｖｂまでの電圧区間における積算電流量（Ｉ×Ｔａ）を求めることにより二次電池１の区間容量を算出する。 Next, as shown in FIG. 3, as the section capacity check section, the section capacity test start voltage Va and the section capacity test end voltage Vb (Va> Vb) are within the range from the initial voltage Vs to the discharge end voltage Ve. The discharge current value I when discharged in step S01 and the section capacity test start time ta when the secondary battery 1 is in the section capacity test start voltage Va are changed to the section capacity test end voltage Vb. The section capacity of the secondary battery 1 is calculated using the discharge time Ta until a certain section capacity inspection end time tb (S02).
Specifically, by using the discharge current value I and the discharge time Ta, the integrated current amount (I × Ta) in the voltage section from the section capacity test start voltage Va to the section capacity test end voltage Vb is obtained. The section capacity of the secondary battery 1 is calculated.

また、図４に示すように、初期電圧Ｖｓから放電終了電圧Ｖｅの範囲内において、二次電池１の電圧が初期電圧Ｖｓにある放電開始時の時刻ｔ０から一定時間経過後の時刻ｔ１における二次電池１の電圧Ｖ１を測定し、初期電圧Ｖｓから電圧Ｖ１を減じることで、時刻ｔ０から時刻ｔ１までの第一の電圧降下量ΔＶ１を算出する。
同様に、初期電圧Ｖｓから放電終了電圧Ｖｅの範囲内において、二次電池１の電圧が、第一の電圧降下量ΔＶ１を測定した電圧（電圧Ｖ１）よりも低い電圧である所定の電圧Ｖ２に達した時刻ｔ２から、一定時間経過後の時刻ｔ３における二次電池１の電圧Ｖ３を測定し、電圧Ｖ２から電圧Ｖ３を減じることで、時刻ｔ２から時刻ｔ３までの（経過時間Ｔ１における）第二の電圧降下量ΔＶ２を算出する。 In addition, as shown in FIG. 4, within the range from the initial voltage Vs to the discharge end voltage Ve, the secondary battery 1 has a voltage at the initial voltage Vs. The voltage V1 of the secondary battery 1 is measured, and the first voltage drop amount ΔV1 from time t0 to time t1 is calculated by subtracting the voltage V1 from the initial voltage Vs.
Similarly, within the range from the initial voltage Vs to the discharge end voltage Ve, the voltage of the secondary battery 1 becomes a predetermined voltage V2 that is lower than the voltage (voltage V1) obtained by measuring the first voltage drop amount ΔV1. By measuring the voltage V3 of the secondary battery 1 at the time t3 after the lapse of a certain time from the reached time t2, and subtracting the voltage V3 from the voltage V2, the second (from the elapsed time T1) from the time t2 to the time t3. The voltage drop amount ΔV2 is calculated.

さらに、前記放電電流値Ｉを第一の電圧降下量ΔＶ１と第二の電圧降下量ΔＶ２との積算値にて除することにより、二次電池１の導電率（＝Ｉ／（ΔＶ１＋ΔＶ２））を算出する（Ｓ０２）。
なお、二次電池１の導電率とは、二次電池１における電流の流れ易さを表す指標となるものであり、抵抗の逆数にて表される。 Further, by dividing the discharge current value I by the integrated value of the first voltage drop amount ΔV1 and the second voltage drop amount ΔV2, the conductivity (= I / (ΔV1 + ΔV2)) of the secondary battery 1 is obtained. Calculate (S02).
In addition, the electrical conductivity of the secondary battery 1 serves as an index representing the ease of current flow in the secondary battery 1 and is represented by the reciprocal of the resistance.

そして、算出した前記区間容量と予め設定しておいた閾値となる基準区間容量とを比較するとともに、算出した導電率と予め設定しておいた閾値となる基準導電率とを比較する（Ｓ０３）。   Then, the calculated section capacity is compared with a reference section capacity serving as a preset threshold value, and the calculated conductivity is compared with a reference conductivity serving as a preset threshold value (S03). .

ここで、図５に示すように、二次電池１の前記区間容量は、二次電池１の全容量（ＳＯＣ１００％から０％まで放電させた場合に測定される容量）と相関を有するものであり、二次電池１において保証する全容量（全容量の保証値）に対応する区間容量を基準区間容量として設定している。
従って、ステップＳ０２にて算出した区間容量と基準区間容量とをステップＳ０３にて比較した際に、区間容量が基準区間容量以上であれば、当該二次電池１の全容量が必要性能を満たしているとして、検査合格と判定することが可能となる。 Here, as shown in FIG. 5, the section capacity of the secondary battery 1 has a correlation with the total capacity of the secondary battery 1 (capacity measured when discharging from SOC 100% to 0%). Yes, the section capacity corresponding to the total capacity (guaranteed value of the total capacity) guaranteed in the secondary battery 1 is set as the reference section capacity.
Therefore, when the section capacity calculated in step S02 and the reference section capacity are compared in step S03, if the section capacity is equal to or greater than the reference section capacity, the total capacity of the secondary battery 1 satisfies the required performance. As a result, it is possible to determine that the inspection has passed.

また、図６に示すように、二次電池１の前記導電率は、二次電池１の出力と相関を有するものであり、二次電池１において保証する出力に対応する導電率を基準導電率として設定している。
従って、ステップＳ０２にて算出した導電率と基準導電率とをステップＳ０３にて比較した際に、導電率Ｖが基準導電率以上であれば、当該二次電池１の出力が必要性能を満たしているとして、検査合格と判定することが可能となる。 Further, as shown in FIG. 6, the conductivity of the secondary battery 1 has a correlation with the output of the secondary battery 1, and the conductivity corresponding to the output guaranteed in the secondary battery 1 is set as the reference conductivity. It is set as.
Therefore, when the conductivity calculated in step S02 and the reference conductivity are compared in step S03, if the conductivity V is equal to or higher than the reference conductivity, the output of the secondary battery 1 satisfies the required performance. As a result, it is possible to determine that the inspection has passed.

ステップＳ０３における前記区間容量と基準区間容量との比較、および前記導電率と基準導電率との比較の結果、前記区間容量が基準区間容量以上であるとともに、前記導電率が基準導電率以上であって、区間容量と導電率との両者が基準値を達成していると判断した場合には（Ｓ０４）、当該二次電池１は全容量および出力の両方が必要性能を満たしており、良品（出荷可能）であると判定する（Ｓ０５）。
一方、ステップＳ０３における前記比較の結果、少なくとも前記区間容量が基準区間容量よりも少ないか、または前記導電率が基準導電率よりも小さくて、区間容量および導電率の少なくとも何れか一方が基準値を達成していないと判断した場合には（Ｓ０４）、当該二次電池１は少なくとも全容量または出力の何れかが必要性能を満たしていないと判断し、不良品（出荷不可）であると判定する（Ｓ０６）。 As a result of the comparison between the section capacity and the reference section capacity in Step S03 and the comparison between the conductivity and the reference conductivity, the section capacity is equal to or greater than the reference section capacity, and the conductivity is equal to or greater than the reference conductivity. When it is determined that both the section capacity and the conductivity have achieved the reference values (S04), the secondary battery 1 satisfies both the necessary capacity and the output, and the non-defective product ( (S05).
On the other hand, as a result of the comparison in step S03, at least the section capacitance is smaller than the reference section capacity, or the conductivity is smaller than the reference conductivity, and at least one of the section capacitance and the conductivity has a reference value. If it is determined that it has not been achieved (S04), it is determined that at least either the full capacity or the output does not satisfy the required performance, and the secondary battery 1 is determined to be defective (unshipable). (S06).

このように、本実施形態の二次電池１の検査方法においては、二次電池１を１度だけ放電させて、全容量および出力の検査を同時に行うようにしている。また、出力検査は、二次電池１のＩＶ抵抗を測定することなく、容量測定に用いられる放電結果（放電曲線）を用いて導電率を算出することにより行っている。
これにより、二次電池１の検査時間を短縮して、検査工程に要するコストを削減することが可能となっている。 As described above, in the inspection method for the secondary battery 1 of the present embodiment, the secondary battery 1 is discharged only once, and the total capacity and the output are inspected at the same time. Further, the output inspection is performed by calculating the conductivity using the discharge result (discharge curve) used for the capacity measurement without measuring the IV resistance of the secondary battery 1.
Thereby, the inspection time of the secondary battery 1 can be shortened, and the cost required for the inspection process can be reduced.

前述のように、二次電池１について算出する区間容量は、二次電池１の全容量と相関を有しているが、その相関度合いは、区間容量を算出する際に設定される区間容量検査開始電圧Ｖａおよび区間容量検査終了電圧Ｖｂの値により変化する。
従って、区間容量検査開始電圧Ｖａおよび区間容量検査終了電圧Ｖｂの値は、算出する区間容量と二次電池１の全容量との相関係数が高くなる値に設定することにより、区間容量を用いて行う容量検査の検査精度を高めることができる。 As described above, the section capacity calculated for the secondary battery 1 has a correlation with the total capacity of the secondary battery 1, but the degree of correlation is the section capacity test set when calculating the section capacity. It changes depending on the values of the start voltage Va and the interval capacity test end voltage Vb.
Therefore, the values of the section capacity inspection start voltage Va and the section capacity inspection end voltage Vb are set to values that increase the correlation coefficient between the section capacity to be calculated and the total capacity of the secondary battery 1, thereby using the section capacity. Therefore, it is possible to improve the inspection accuracy of the capacity inspection.

なお、算出する区間容量と二次電池１の全容量との相関係数を求める際には、良品であることが既知であるモデル二次電池について求めた区間容量および全容量のデータを用いて相関係数を算出する。   When obtaining the correlation coefficient between the calculated section capacity and the total capacity of the secondary battery 1, the section capacity and the total capacity data obtained for the model secondary battery that is known to be non-defective are used. A correlation coefficient is calculated.

図７には、二次電池１の区間容量と全容量との相関係数が高くなるように、区間容量検査開始電圧Ｖａおよび区間容量検査終了電圧Ｖｂを設定した場合の、二次電池１の区間容量と全容量との相関性を示している。
図７によれば、区間容量検査開始電圧Ｖａを３．４６Ｖに設定するとともに、区間容量検査終了電圧Ｖｂを３．３９Ｖに設定することで、区間容量と全容量との相関係数として０．９８１といった高い値が得られている。 FIG. 7 shows the secondary battery 1 when the section capacity inspection start voltage Va and the section capacity inspection end voltage Vb are set so that the correlation coefficient between the section capacity and the total capacity of the secondary battery 1 is high. The correlation between the interval capacity and the total capacity is shown.
According to FIG. 7, by setting the section capacity inspection start voltage Va to 3.46V and setting the section capacity inspection end voltage Vb to 3.39V, the correlation coefficient between the section capacity and the total capacity is set to 0. A high value such as 981 is obtained.

また、前述のように、二次電池１について測定した第一の電圧変化量ΔＶ１および第二の電圧降下量ΔＶ２を用いて算出される導電率は、二次電池１の出力と相関を有しているが、その相関度合いは、第二の電圧降下量ΔＶ２を算出する際の所定の電圧Ｖ２、および所定の電圧Ｖ２に達した時刻ｔ２から時刻ｔ３までの経過時間Ｔ１の値により変化する。   Further, as described above, the conductivity calculated using the first voltage change amount ΔV1 and the second voltage drop amount ΔV2 measured for the secondary battery 1 has a correlation with the output of the secondary battery 1. However, the degree of correlation varies depending on the predetermined voltage V2 when calculating the second voltage drop amount ΔV2 and the value of the elapsed time T1 from time t2 to time t3 when the predetermined voltage V2 is reached.

従って、第二の電圧降下量ΔＶ２を算出する際には、例えば良品であることが既知であるモデル二次電池の出力と導電率との相関係数を、種々の所定の電圧Ｖ２および経過時間Ｔ１の場合について予め算出しておき、これらを用いて、所定の電圧Ｖ２および経過時間Ｔ１の値を、前記モデル二次電池の出力と導電率との相関係数が高くなる値に設定するようにしている。
これにより、算出した導電率を用いて二次電池１の出力検査を高精度に行うことが可能となる。 Therefore, when calculating the second voltage drop amount ΔV2, for example, the correlation coefficient between the output and conductivity of a model secondary battery that is known to be a non-defective product is calculated using various predetermined voltages V2 and elapsed time. The case of T1 is calculated in advance, and the values of the predetermined voltage V2 and the elapsed time T1 are set to values that increase the correlation coefficient between the output of the model secondary battery and the conductivity. I have to.
Thereby, it becomes possible to perform the output test of the secondary battery 1 with high accuracy using the calculated conductivity.

図８には、二次電池１の−３０℃での出力と導電率との相関係数が高くなるように、所定の電圧Ｖ２および経過時間Ｔ１の値を設定した場合の、二次電池１の出力と導電率との相関性を示している。
図８によれば、所定の電圧Ｖ２を３．５４Ｖに設定するとともに、経過時間Ｔ１を２００秒に設定することで、−３０℃での出力と導電率との相関係数として０．９１６といった高い値が得られている。なお、図８においては、放電開始直後の電圧降下量ΔＶ１として、放電開始から０．１秒経過後の電圧降下量を用いている。 FIG. 8 shows the secondary battery 1 when the values of the predetermined voltage V2 and the elapsed time T1 are set so that the correlation coefficient between the output of the secondary battery 1 at −30 ° C. and the conductivity is high. The correlation between the output and the conductivity is shown.
According to FIG. 8, by setting the predetermined voltage V2 to 3.54V and setting the elapsed time T1 to 200 seconds, the correlation coefficient between the output at −30 ° C. and the conductivity is 0.916. A high value is obtained. In FIG. 8, the voltage drop amount after 0.1 second has elapsed from the start of discharge is used as the voltage drop amount ΔV1 immediately after the start of discharge.

ここで、二次電池１における電気的な抵抗成分としては、主に直流抵抗成分、反応抵抗成分、および拡散抵抗成分の３つの抵抗成分がある。
直流抵抗成分は、正極および負極の集電体の抵抗や、正極および負極における活物質と集電体との間や活物質間で電荷が伝達される際の抵抗である。
反応抵抗成分は、Ｌｉイオンの正極および負極への入り易さ、即ち電解液と正極および負極における活物質界面での電荷の移動抵抗のことである。
拡散抵抗成分は、Ｌｉイオンの正極および負極における活物質内への拡散のし易さ、即ちＬｉイオンの前記活物質内への拡散に起因する抵抗である。 Here, the electrical resistance component in the secondary battery 1 mainly includes three resistance components, that is, a DC resistance component, a reaction resistance component, and a diffusion resistance component.
The direct current resistance component is the resistance of the current collector of the positive electrode and the negative electrode, or the resistance when charge is transferred between the active material and the current collector or between the active materials in the positive electrode and the negative electrode.
The reaction resistance component is the ease with which Li ions can enter the positive electrode and the negative electrode, that is, the charge transfer resistance at the interface between the electrolyte and the active material in the positive electrode and the negative electrode.
The diffusion resistance component is the resistance resulting from the ease of diffusion of Li ions into the active material in the positive and negative electrodes, that is, the diffusion of Li ions into the active material.

図４に示す放電曲線においては、放電開始直後（放電開始時の時刻ｔ０から一定時間経過後の時刻ｔ１までの時間）の第一の電圧降下量ΔＶ１に、前記直流抵抗成分が反映されている。また、放電開始直後以降において、二次電池１の電圧が所定の電圧Ｖ２に達した時刻ｔ２から一定時間経過後の時刻ｔ３となるまでの間の第二の電圧降下量ΔＶ２に、前記反応抵抗成分および拡散抵抗成分が反映されている。
これは、二次電池１の直流抵抗成分が、電圧変化に対して応答が早い抵抗成分であり、放電曲線における放電開始直後の第一の電圧降下量ΔＶ１を測定する部分にのみ含まれることとなるためである。 In the discharge curve shown in FIG. 4, the direct current resistance component is reflected in the first voltage drop amount ΔV1 immediately after the start of discharge (the time from the time t0 at the start of discharge to the time t1 after a certain time has elapsed). . Further, immediately after the start of discharge, the reaction resistance is reduced to the second voltage drop amount ΔV2 from the time t2 when the voltage of the secondary battery 1 reaches the predetermined voltage V2 to the time t3 after a certain time has elapsed. The component and the diffusion resistance component are reflected.
This is because the DC resistance component of the secondary battery 1 is a resistance component having a quick response to a voltage change, and is included only in a portion for measuring the first voltage drop ΔV1 immediately after the start of discharge in the discharge curve. It is to become.

そして、本実施形態における出力検査では、直流抵抗成分が反映された放電開始直後の第一の電圧降下量ΔＶ１と、反応抵抗成分および拡散抵抗成分が反映された放電開始直後以降のタイミングにおける第二の電圧降下量ΔＶ２とを用いて、二次電池１の導電率を算出することにより出力検査を行っているので、出力検査を高精度に行うことが可能となっている。
即ち、放電開始直後の第一の電圧降下量ΔＶ１により二次電池１の直流抵抗成分を推定するとともに、放電開始直後以降の第二の電圧降下量ΔＶ２により二次電池１の反応抵抗成分および拡散抵抗成分を推定することで、第一の電圧降下量ΔＶ１および第二の電圧降下量ΔＶ２を用いて算出した二次電池１の導電率と出力との相関性を高めることができ、高精度な出力検査を行うことが可能となっている。 In the output inspection in the present embodiment, the first voltage drop amount ΔV1 immediately after the start of discharge reflecting the direct current resistance component, and the second time at the timing immediately after the start of discharge reflecting the reaction resistance component and the diffusion resistance component. Since the output inspection is performed by calculating the electrical conductivity of the secondary battery 1 using the voltage drop amount ΔV2 of the above, it is possible to perform the output inspection with high accuracy.
That is, the DC resistance component of the secondary battery 1 is estimated from the first voltage drop amount ΔV1 immediately after the start of discharge, and the reaction resistance component and diffusion of the secondary battery 1 are estimated from the second voltage drop amount ΔV2 immediately after the start of discharge. By estimating the resistance component, the correlation between the electrical conductivity of the secondary battery 1 calculated using the first voltage drop amount ΔV1 and the second voltage drop amount ΔV2 and the output can be increased, and high accuracy is achieved. It is possible to perform output inspection.

一方、初期充電を終えた二次電池を１度だけ放電させることにより、容量と出力との測定を同時に行って、二次電池１の検査の検査時間を短縮させる場合、初期電圧Ｖｓから放電終了電圧Ｖｅの範囲内において、二次電池１が任意の電圧に達してから所定時間が経過した時点までの電圧降下量ΔＶを算出し、算出した電圧降下量ΔＶと相関を有する二次電池１の出力の良否を判定することが考えられる。   On the other hand, when the secondary battery that has been initially charged is discharged only once, the capacity and the output are measured simultaneously to shorten the inspection time of the secondary battery 1, and the discharge ends from the initial voltage Vs. Within the range of the voltage Ve, a voltage drop amount ΔV is calculated from when the secondary battery 1 reaches an arbitrary voltage until a predetermined time has elapsed, and the secondary battery 1 having a correlation with the calculated voltage drop amount ΔV is calculated. It can be considered to determine whether the output is good or bad.

しかし、例えば前記電圧降下量ΔＶを算出する区間を、放電開始直後以降の区間に設定した場合は、二次電池１の反応抵抗成分および拡散抵抗成分のみが考慮され、二次電池１の直流抵抗成分が考慮されない出力検査を行うこととなるため、直流抵抗成分が反映された第一の電圧降下量ΔＶ１と、反応抵抗成分および拡散抵抗成分が反映された第二の電圧降下量ΔＶ２とを用いた本実施形態における出力検査の場合に比べて、二次電池１の導電率と出力との相関性が低くなり、出力検査の精度が低下することになる。   However, for example, when the section for calculating the voltage drop amount ΔV is set to a section immediately after the start of discharge, only the reaction resistance component and the diffusion resistance component of the secondary battery 1 are considered, and the DC resistance of the secondary battery 1 is considered. Since the output inspection is performed without considering the component, the first voltage drop amount ΔV1 reflecting the DC resistance component and the second voltage drop amount ΔV2 reflecting the reaction resistance component and the diffusion resistance component are used. Compared with the case of the output inspection in the present embodiment, the correlation between the conductivity and the output of the secondary battery 1 is lowered, and the accuracy of the output inspection is lowered.

また、前記電圧降下量ΔＶを算出する区間を、放電開始時から、放電開始直後以降の時点までの区間に設定した場合は、直流抵抗成分が反映された電圧降下量と反応抵抗成分および拡散抵抗成分が反映された電圧降下量とを連続して測定した出力検査を行うこととなるが、二次電池１の放電開始電圧（初期電圧Ｖｓ）やＳＯＣが揃っていないため、二次電池１の残存容量の差が電圧降下量に影響することから、直流抵抗成分が反映された第一の電圧降下量ΔＶ１と、反応抵抗成分および拡散抵抗成分が反映された第二の電圧降下量ΔＶ２とを別々に測定して行った本実施形態における出力検査の場合に比べて、二次電池１の導電率と出力との相関性が低くなり、出力検査の精度が低下することになる。   Further, when the section for calculating the voltage drop amount ΔV is set to a section from the start of discharge to the time immediately after the start of discharge, the voltage drop amount, reaction resistance component and diffusion resistance reflecting the direct current resistance component Although the output inspection in which the voltage drop amount reflecting the component is continuously measured is performed, since the discharge start voltage (initial voltage Vs) and SOC of the secondary battery 1 are not uniform, Since the difference in the remaining capacity affects the voltage drop amount, the first voltage drop amount ΔV1 reflecting the DC resistance component and the second voltage drop amount ΔV2 reflecting the reaction resistance component and the diffusion resistance component are obtained. Compared with the case of the output inspection in the present embodiment performed separately, the correlation between the conductivity of the secondary battery 1 and the output is lowered, and the accuracy of the output inspection is lowered.

このように、本実施形態における二次電池１の検査方法では、直流抵抗成分が反映された第一の電圧降下量ΔＶ１と、反応抵抗成分および拡散抵抗成分が反映された第二の電圧降下量ΔＶ２とを用いて二次電池１の導電率を算出することにより、二次電池１の導電率と出力との相関性を高めて、二次電池１の出力検査を高精度に行うようにしている。   Thus, in the inspection method for the secondary battery 1 in the present embodiment, the first voltage drop amount ΔV1 reflecting the DC resistance component and the second voltage drop amount reflecting the reaction resistance component and the diffusion resistance component. By calculating the electrical conductivity of the secondary battery 1 using ΔV2, the correlation between the electrical conductivity and the output of the secondary battery 1 is increased, and the output test of the secondary battery 1 is performed with high accuracy. Yes.

次に、本実施形態における検査方法により、二次電池１の検査を実施した場合に、高い精度で検査ができているかを検証した結果について説明する。   Next, the result of verifying whether or not the inspection can be performed with high accuracy when the inspection of the secondary battery 1 is performed by the inspection method in the present embodiment will be described.

まず、本実施形態の検査方法による検査を実施した二次電池１としては、電極長を変更することにより設計容量を０〜２．５％の範囲で４水準に変化させたサンプルを２８個用いた。
検査実施例として、これらの各サンプルを、２０℃の環境下で、４．０Ｖから２．５Ｖまで２．４Ｃにて一度だけ放電させた。 First, as the secondary battery 1 subjected to the inspection by the inspection method of the present embodiment, 28 samples whose design capacity is changed to 4 levels in the range of 0 to 2.5% by changing the electrode length are used. It was.
As a test example, each of these samples was discharged only once at 2.4 C from 4.0 V to 2.5 V in a 20 ° C. environment.

＜容量検査について＞
前述の検査実施例とは別に、各サンプルを、４．１Ｖ（ＳＯＣ１００％）から３．０Ｖ（ＳＯＣ０％）までＣＶ放電を行って、各サンプルの全容量を測定した。
また、各サンプルについて、区間容量検査開始電圧Ｖａを３．６４Ｖに設定し、区間容量検査終了電圧Ｖｂを３．４Ｖに設定して、前記検査実施例での放電データより、区間容量検査開始電圧Ｖａから区間容量検査終了電圧Ｖｂまでの区間容量を算出した。
そして、各サンプルについて、測定した全容量と算出した区間容量とを比較し、両者の相関性の確認を行った。 <About capacity inspection>
Separately from the test example described above, each sample was subjected to CV discharge from 4.1 V (SOC 100%) to 3.0 V (SOC 0%), and the total capacity of each sample was measured.
For each sample, the section capacity test start voltage Va is set to 3.64 V, the section capacity test end voltage Vb is set to 3.4 V, and the section capacity test start voltage is determined from the discharge data in the test example. The section capacity from Va to the section capacity inspection end voltage Vb was calculated.
And about each sample, the measured total capacity | capacitance was compared with the calculated area capacity | capacitance, and both correlation was confirmed.

この確認の結果、測定した全容量と算出した区間容量との相関係数は０．９８と高い値を示したことから、両者間には高い相関性があることがわかった。
従って、例えば、区間容量検査開始電圧Ｖａを３．６４Ｖに設定し、区間容量検査終了電圧Ｖｂを３．４Ｖに設定して区間容量を算出することにより、高精度な容量検査を実施することが可能となる。 As a result of this confirmation, the correlation coefficient between the measured total capacity and the calculated section capacity showed a high value of 0.98, indicating that there is a high correlation between the two.
Therefore, for example, by setting the section capacity test start voltage Va to 3.64 V and the section capacity test end voltage Vb to 3.4 V, and calculating the section capacity, it is possible to perform a highly accurate capacity test. It becomes possible.

＜出力検査について＞
前述の検査実施例とは別に、各サンプルについて、二次電池１の−３０℃および２５℃での出力を測定した。 <About output inspection>
Separately from the above-described inspection example, the output of the secondary battery 1 at −30 ° C. and 25 ° C. was measured for each sample.

次に、各サンプルについて、算出した導電率と、測定した出力のうちの−３０℃での出力とを比較し、両者の相関性の確認を行った。
この場合、二次電池１の導電率を算出する際に用いる第一の電圧降下量ΔＶ１は、放電開始時の時刻ｔ０から一定時間経過後の時刻ｔ１までの時間を０．１秒に設定して求めた。 Next, for each sample, the calculated conductivity was compared with the output at −30 ° C. of the measured output, and the correlation between the two was confirmed.
In this case, the first voltage drop amount ΔV1 used when calculating the conductivity of the secondary battery 1 is set to 0.1 second from the time t0 at the start of discharge to the time t1 after a predetermined time has elapsed. Asked.

図９には、電圧Ｖ２と経過時間Ｔ１とを種々変化させた場合の、二次電池１の導電率と、−３０℃での二次電池１の出力との相関係数を示している。
具体的には、二次電池１の導電率と−３０℃での二次電池１の出力との相関係数の経過時間Ｔ１による変化を、電圧Ｖ２を３．８２Ｖ、３，７４Ｖ、３．６６Ｖ、３．６２Ｖ、３．５８Ｖ、３．５４Ｖ、３．５０Ｖ、および３．４６Ｖとした場合のそれぞれについて示している。
また、放電開始時（ｔ０）から放電開始直後以降の時点までの所定の経過時間Ｔまでの電圧降下量ΔＶを用いて二次電池１の導電率（＝Ｉ／ΔＶ）を算出した場合（これは、第一の電圧降下量ΔＶ１および第二の電圧降下量ΔＶ２を連続して測定した場合に相当する）の、二次電池１の導電率と−３０℃での二次電池１の出力との相関係数の経過時間Ｔによる変化を、比較例（ｒｅｆ）として示している。 FIG. 9 shows a correlation coefficient between the conductivity of the secondary battery 1 and the output of the secondary battery 1 at −30 ° C. when the voltage V2 and the elapsed time T1 are variously changed.
Specifically, the change of the correlation coefficient between the electrical conductivity of the secondary battery 1 and the output of the secondary battery 1 at −30 ° C. according to the elapsed time T1, the voltage V2 is 3.82V, 3,74V, Each of 66V, 3.62V, 3.58V, 3.54V, 3.50V, and 3.46V is shown.
Further, when the electrical conductivity (= I / ΔV) of the secondary battery 1 is calculated using the voltage drop amount ΔV from the start of discharge (t0) to a predetermined elapsed time T from the time immediately after the start of discharge to the time immediately after the start of discharge (this) Is equivalent to the case where the first voltage drop amount ΔV1 and the second voltage drop amount ΔV2 are continuously measured), the conductivity of the secondary battery 1 and the output of the secondary battery 1 at −30 ° C. A change of the correlation coefficient due to the elapsed time T is shown as a comparative example (ref).

図９によれば、電圧Ｖ２が３．５４Ｖで経過時間Ｔ１が２００秒付近（図９において丸印で囲んだ部分）である場合に、二次電池１の導電率と出力との相関係数が最も高くなっている。
従って、二次電池１の−３０℃での出力を検査する際には、電圧Ｖ２および経過時間Ｔ１をＶ２＝３．５４Ｖ、Ｔ１＝２００秒付近に設定したうえで第二の電圧降下量ΔＶ２を測定して導電率を算出することで、高い検査精度での出力検査を行い得ることがわかる。 According to FIG. 9, when the voltage V2 is 3.54V and the elapsed time T1 is around 200 seconds (the part circled in FIG. 9), the correlation coefficient between the conductivity and the output of the secondary battery 1 Is the highest.
Therefore, when inspecting the output of the secondary battery 1 at −30 ° C., the voltage V2 and the elapsed time T1 are set to V2 = 3.54 V and T1 = 200 seconds, and then the second voltage drop amount ΔV2 is set. It is understood that an output inspection with high inspection accuracy can be performed by measuring the electrical conductivity and calculating the conductivity.

つまり、電圧Ｖ２および経過時間Ｔ１をＶ２＝３．５４Ｖ、Ｔ１＝２００秒付近に設定したうえで第二の電圧降下量ΔＶ２を測定して導電率を算出し、算出した導電率を用いて二次電池１の出力検査を行うことで、検査精度を向上させることができる。
また、この条件に設定した場合の二次電池１の導電率と出力との相関係数は、比較例（ｒｅｆ）の相関係数に比べて高くなっており、第一の電圧降下量ΔＶ１および第二の電圧降下量ΔＶ２を別々に測定した場合の方が、第一の電圧降下量ΔＶ１および第二の電圧降下量ΔＶ２を連続して測定した場合に比べて、出力検査の精度を向上できることがわかる。 That is, after setting the voltage V2 and the elapsed time T1 to V2 = 3.54 V and T1 = 200 seconds, the second voltage drop amount ΔV2 is measured to calculate the conductivity, and the calculated conductivity is used to calculate the second conductivity. By performing the output inspection of the secondary battery 1, the inspection accuracy can be improved.
Further, the correlation coefficient between the conductivity and the output of the secondary battery 1 when this condition is set is higher than the correlation coefficient of the comparative example (ref), and the first voltage drop amount ΔV1 and When the second voltage drop amount ΔV2 is measured separately, the accuracy of the output inspection can be improved as compared with the case where the first voltage drop amount ΔV1 and the second voltage drop amount ΔV2 are continuously measured. I understand.

次に、各サンプルについて、算出した導電率と、測定した出力のうちの２５℃での出力とを比較し、両者の相関性の確認を行った。
この場合、二次電池１の導電率を算出する際に用いる第一の電圧降下量ΔＶ１は、放電開始時の時刻ｔ０から一定時間経過後の時刻ｔ１までの時間を０．１秒に設定して求めた。 Next, for each sample, the calculated conductivity was compared with the output at 25 ° C. of the measured output, and the correlation between the two was confirmed.
In this case, the first voltage drop amount ΔV1 used when calculating the conductivity of the secondary battery 1 is set to 0.1 second from the time t0 at the start of discharge to the time t1 after a predetermined time has elapsed. Asked.

図１０には、電圧Ｖ２と経過時間Ｔ１とを種々変化させた場合の、二次電池１の導電率と、２５℃での二次電池１の出力との相関係数を示している。
具体的には、二次電池１の導電率と２５℃での二次電池１の出力との相関係数の経過時間Ｔ１による変化を、電圧Ｖ２を３．８２Ｖ、３，７４Ｖ、３．６６Ｖ、３．６２Ｖ、３．５８Ｖ、３．５４Ｖ、３．５０Ｖ、および３．４６Ｖとした場合のそれぞれについて示している。
また、放電開始時（ｔ０）から放電開始直後以降の時点までの所定の経過時間Ｔまでの電圧降下量ΔＶを用いて二次電池１の導電率（＝Ｉ／ΔＶ）を算出した場合（これは、第一の電圧降下量ΔＶ１および第二の電圧降下量ΔＶ２を連続して測定した場合に相当する）の、二次電池１の導電率と２５℃での二次電池１の出力との相関係数の経過時間Ｔによる変化を、比較例（ｒｅｆ）として示している。 FIG. 10 shows a correlation coefficient between the conductivity of the secondary battery 1 and the output of the secondary battery 1 at 25 ° C. when the voltage V2 and the elapsed time T1 are variously changed.
Specifically, the change of the correlation coefficient between the electrical conductivity of the secondary battery 1 and the output of the secondary battery 1 at 25 ° C. by the elapsed time T1, the voltage V2 is 3.82V, 3,74V, 3.66V. It has shown about each when it is set as 3.62V, 3.58V, 3.54V, 3.50V, and 3.46V.
Further, when the electrical conductivity (= I / ΔV) of the secondary battery 1 is calculated using the voltage drop amount ΔV from the start of discharge (t0) to a predetermined elapsed time T from the time immediately after the start of discharge to the time immediately after the start of discharge (this) Is equivalent to the case where the first voltage drop amount ΔV1 and the second voltage drop amount ΔV2 are continuously measured), and the conductivity of the secondary battery 1 and the output of the secondary battery 1 at 25 ° C. A change of the correlation coefficient due to the elapsed time T is shown as a comparative example (ref).

図１０によれば、電圧Ｖ２が３．６６Ｖで経過時間Ｔ１が７３０秒付近（図１０において丸印で囲んだ部分）である場合に、二次電池１の導電率と出力との相関係数が最も高くなっている。
従って、二次電池１の２５℃での出力を検査する際には、電圧Ｖ２および経過時間Ｔ１をＶ２＝３．６６Ｖ、Ｔ１＝７３０秒付近に設定したうえで第二の電圧降下量ΔＶ２を測定して導電率を算出することで、高い検査精度での出力検査を行い得ることがわかる。 According to FIG. 10, when the voltage V2 is 3.66V and the elapsed time T1 is around 730 seconds (the part circled in FIG. 10), the correlation coefficient between the conductivity and the output of the secondary battery 1 is obtained. Is the highest.
Therefore, when inspecting the output of the secondary battery 1 at 25 ° C., the voltage V2 and the elapsed time T1 are set to V2 = 3.66V and T1 = 730 seconds, and then the second voltage drop ΔV2 is set. It can be seen that an output inspection with high inspection accuracy can be performed by measuring and calculating the conductivity.

つまり、電圧Ｖ２および経過時間Ｔ１をＶ２＝３．６６Ｖ、Ｔ１＝７３０秒付近に設定したうえで第二の電圧降下量ΔＶ２を測定して導電率を算出し、算出した導電率を用いて二次電池１の出力検査を行うことで、検査精度を向上させることができる。
また、この条件に設定した場合の二次電池１の導電率と出力との相関係数は、比較例（ｒｅｆ）の相関係数に比べて高くなっており、第一の電圧降下量ΔＶ１および第二の電圧降下量ΔＶ２を別々に測定した場合の方が、第一の電圧降下量ΔＶ１および第二の電圧降下量ΔＶ２を連続して測定した場合に比べて、出力検査の精度を向上できることがわかる。 That is, after setting the voltage V2 and the elapsed time T1 to V2 = 3.66V and T1 = 730 seconds, the second voltage drop amount ΔV2 is measured to calculate the conductivity, and the calculated conductivity is used to calculate the second conductivity. By performing the output inspection of the secondary battery 1, the inspection accuracy can be improved.
Further, the correlation coefficient between the conductivity and the output of the secondary battery 1 when this condition is set is higher than the correlation coefficient of the comparative example (ref), and the first voltage drop amount ΔV1 and When the second voltage drop amount ΔV2 is measured separately, the accuracy of the output inspection can be improved as compared with the case where the first voltage drop amount ΔV1 and the second voltage drop amount ΔV2 are continuously measured. I understand.

なお、二次電池１においては、低温になるほど反応抵抗成分が大きくなるため、第一の電圧降下量ΔＶ１および第二の電圧降下量ΔＶ２を別々に測定した場合の導電率と出力との相関係数の、第一の電圧降下量ΔＶ１および第二の電圧降下量ΔＶ２を連続して測定した場合の導電率と出力との相関係数に対する向上度合いは、低温になるほど大きくなっている。
また、第一の電圧降下量ΔＶ１および第二の電圧降下量ΔＶ２を連続して測定した場合は、二次電池１の放電開始電圧（初期電圧Ｖｓ）やＳＯＣが揃っていないと、二次電池１の残存容量の差が電圧降下量に影響することから、第一の電圧降下量ΔＶ１および第二の電圧降下量ΔＶ２を別々に測定して導電率を算出することが好ましい。 In the secondary battery 1, since the reaction resistance component increases as the temperature decreases, the phase relationship between the conductivity and the output when the first voltage drop amount ΔV1 and the second voltage drop amount ΔV2 are measured separately. When the first voltage drop amount ΔV1 and the second voltage drop amount ΔV2 are continuously measured, the degree of improvement in the correlation coefficient between the conductivity and the output increases as the temperature decreases.
Further, when the first voltage drop amount ΔV1 and the second voltage drop amount ΔV2 are continuously measured, if the discharge start voltage (initial voltage Vs) and SOC of the secondary battery 1 are not complete, the secondary battery Since the difference in the remaining capacity of 1 affects the voltage drop amount, it is preferable to calculate the conductivity by separately measuring the first voltage drop amount ΔV1 and the second voltage drop amount ΔV2.

このように、二次電池１を一度だけ放電して、その放電データにおける二次電池１の区間容量および導電率を用いて、二次電池１の容量および出力を検査した場合でも、容量および出力の両方において、高い精度で検査可能であることが確認できた。   Thus, even when the secondary battery 1 is discharged only once and the capacity and output of the secondary battery 1 are inspected using the section capacity and conductivity of the secondary battery 1 in the discharge data, the capacity and output In both cases, it was confirmed that inspection was possible with high accuracy.

また、二次電池１の−３０℃および２５℃といった各温度での出力を測定して、各温度における二次電池１の出力検査を行うことで、初期充電を終えた二次電池を１度だけ放電させることにより、広範囲の温度での二次電池１の出力を保証することが可能となる。
なお、本実施形態では、−３０℃および２５℃での出力について出力検査を行ったが、他の温度での出力検査を行うことも可能である。 Further, by measuring the output of the secondary battery 1 at each temperature such as −30 ° C. and 25 ° C. and performing the output inspection of the secondary battery 1 at each temperature, the secondary battery that has finished initial charging is once By discharging only, it becomes possible to guarantee the output of the secondary battery 1 in a wide range of temperatures.
In the present embodiment, the output inspection is performed for outputs at −30 ° C. and 25 ° C., but it is also possible to perform the output inspection at other temperatures.

１ 二次電池
２ 電池ケース
３ 電極体３
Ｔ２ 一定時間（経過時間）
Ｖｓ 初期電圧
Ｖｅ 放電終了電圧
Ｖａ 区間容量検査開始電圧
Ｖｂ 区間容量検査終了電圧
Ｖ２ 電圧
ΔＶ 電圧変化量 1 Secondary Battery 2 Battery Case 3 Electrode Body 3
T2 fixed time (elapsed time)
Vs initial voltage Ve discharge end voltage Va interval capacity inspection start voltage Vb interval capacity inspection end voltage V2 voltage ΔV voltage change amount

Claims (3)

初期充電を終えた二次電池を所定の初期電圧Ｖｓから放電終了電圧Ｖｅまで、所定の放電電流Ｉにて放電する放電工程を、一度だけ行うことによって、前記二次電池の容量検査と出力検査とを行う二次電池の検査方法であって、
前記出力検査は、
前記放電工程の開始時から一定時間経過後までの前記二次電池の第一の電圧降下量ΔＶ１を測定する工程と、
前記二次電池の電圧が、前記第一の電圧降下量ΔＶ１を測定した電圧よりも低い電圧である任意の電圧Ｖ２に到達した時点から、一定時間Ｔ２経過した時点までの第二の電圧降下量ΔＶ２を測定する工程と、
前記放電電流Ｉ、第一の電圧降下量ΔＶ１、および第二の電圧降下量ΔＶ２から、前記二次電池の導電率を算出する工程と、
算出した前記導電率を予め設定した閾値と比較することにより、前記導電率と相関を有する前記二次電池の出力の良否を判定する工程とを備える、
ことを特徴とする二次電池の検査方法。 By performing the discharge process of discharging the secondary battery that has been initially charged from the predetermined initial voltage Vs to the discharge end voltage Ve at a predetermined discharge current I only once, the capacity inspection and output inspection of the secondary battery are performed. A method for inspecting a secondary battery,
The output inspection is
Measuring a first voltage drop amount ΔV1 of the secondary battery from the start of the discharge step to after a lapse of a fixed time;
The second voltage drop amount from the time when the voltage of the secondary battery reaches an arbitrary voltage V2 which is a voltage lower than the voltage obtained by measuring the first voltage drop amount ΔV1 to the time when a certain time T2 has elapsed. Measuring ΔV2;
Calculating the conductivity of the secondary battery from the discharge current I, the first voltage drop amount ΔV1, and the second voltage drop amount ΔV2,
Comparing the calculated conductivity with a preset threshold value to determine whether the output of the secondary battery having a correlation with the conductivity is good or bad.
A method for inspecting a secondary battery. 前記容量検査は、
前記初期電圧Ｖｓと放電終了電圧Ｖｅとの範囲内にて、所定の検査開始電圧Ｖａから、前記検査開始電圧Ｖａよりも低い検査終了電圧Ｖｂまでの区間を、区間容量の検査区間として設定し、前記放電工程における電流値Ｉ、および前記検査開始電圧Ｖａから検査終了電圧Ｖｂとなるまでの放電時間Ｔａから電流積算量を算出して、前記二次電池の区間容量を測定する工程と、
測定した前記区間容量を予め設定した閾値と比較することにより、前記区間容量と相関を有する前記二次電池の全容量の良否を判定する工程とを備える、
ことを特徴とする請求項１に記載の二次電池の検査方法。 The capacity check is
Within a range between the initial voltage Vs and the discharge end voltage Ve, a section from a predetermined test start voltage Va to a test end voltage Vb lower than the test start voltage Va is set as a section capacity test section. Calculating a current integrated amount from a current value I in the discharging step and a discharge time Ta from the inspection start voltage Va to the inspection end voltage Vb, and measuring a section capacity of the secondary battery;
Comparing the measured section capacity with a preset threshold value, and determining whether or not the total capacity of the secondary battery has a correlation with the section capacity.
The method for inspecting a secondary battery according to claim 1. 前記出力検査は、前記二次電池における−３０℃〜２５℃の範囲の出力について行う、
ことを特徴とする請求項１または請求項２に記載の二次電池の検査方法。 The output inspection is performed for an output in a range of −30 ° C. to 25 ° C. in the secondary battery.
The method for inspecting a secondary battery according to claim 1 or 2, characterized in that:
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