JP4954791B2 - Voltage prediction method for power storage devices - Google Patents
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Description
本発明は、簡便で予測精度が高く、かつ、実用的であり、蓄電デバイスの充放電制御、残存容量予測等に用いることが可能な蓄電デバイスの電圧予測方法に関する。 The present invention relates to a voltage prediction method for an electricity storage device that is simple, has high prediction accuracy, is practical, and can be used for charge / discharge control of an electricity storage device, prediction of remaining capacity, and the like.
近年、最先端蓄電デバイスであるリチウムイオン電池、キャパシタのハイブリッド電気自動車に代表される大電流負荷用途蓄電システムに向けた開発が加速している。この開発において蓄電デバイスの出力特性向上、信頼性向上、安全性に関する検討に加え、蓄電デバイスの容量、内部抵抗等を監視し、蓄電デバイスの充放電制御、残存容量予測等を実施することも重要な課題として検討されている。蓄電デバイスの監視システムにおいて、蓄電デバイスの状態予測に関しては、例えば、ノート型パソコン等の残存容量（使用可能時間）予測、充電時間完了予測等があるが、数十分以上の比較的遅い充放電に関する予測であり、事前に取得された容量−電圧カーブ、充放電容量の積算データに基づき予測されている。一方、大電流負荷用途等においては、大電流負荷における蓄電デバイスの内部抵抗に起因する電圧変化（放電時：電圧降下、充電時：電圧上昇）を含めた電池電圧の予測が重要となる。すなわち、例えば、残存容量がある場合においても、蓄電デバイスの電池電圧が規定電圧以下あるいは以上になる場合、システムが要求する出力が得られなくなる、システムの効率が低下する、過放電、過充電による寿命低下等の問題が発生する場合がある。従って、特に、大電流負荷用途蓄電システムにおいて、今後起こるべき充電、あるいは、放電に対して、その電池電圧を簡便かつ精度良く予測する方法が求められている。
この電圧予測に関して重要となるのが、電流負荷時における蓄電デバイスの電圧変化を引き起こす内部抵抗の予測方法である。蓄電デバイスの内部抵抗検知方法においては、例えば、特許文献1に記載されている交流でインピーダンスを測定する方法、特許文献２に記載されているパルス電流を印加したときの電圧降下から内部抵抗を算出する方法、特許文献３に記載されている充電電流を中断したときの電圧降下から内部抵抗を算出する方法が知られている。特許文献４に記載されているように模擬負荷を印加し、すなわち、蓄電デバイスに直接電圧を印加し、実際にその電圧降下からバッテリーをチェックする方法も開示されている。また、非特許文献1には蓄電デバイスの直流内部抵抗評価法として電流休止法が提案され、その評価具体例が記載されている。この電流休止法とは、直流内部抵抗評価を電流休止時の電圧降下（充電時）、電圧上昇（放電時）挙動から求め、その1秒までの時間変化を直流内部抵抗のオーム成分、1秒以降の電圧変化を直流内部抵抗の平衡成分として解析する方法である。しかしながら、時間ｔ後の蓄電デバイスの電圧予測への適用に関しては何ら記載されていない。
What is important regarding this voltage prediction is a method of predicting internal resistance that causes a voltage change of the electricity storage device at the time of current load. In the method for detecting the internal resistance of an electricity storage device, for example, the method of measuring impedance with an alternating current described in Patent Document 1, and the internal resistance is calculated from the voltage drop when a pulse current described in Patent Document 2 is applied. And a method of calculating the internal resistance from the voltage drop when the charging current described in Patent Document 3 is interrupted. As described in Patent Document 4, a method is also disclosed in which a simulated load is applied, that is, a voltage is directly applied to an electricity storage device, and a battery is actually checked from the voltage drop. Non-Patent Document 1 proposes a current pause method as a DC internal resistance evaluation method for an electricity storage device, and describes an example of the evaluation. With this current pause method, DC internal resistance is evaluated from the voltage drop (during charging) and voltage rise (during discharge) behavior during current pause, and the time change up to 1 second is the ohmic component of the DC internal resistance, 1 second. This is a method of analyzing the subsequent voltage change as an equilibrium component of the DC internal resistance. However, there is no description regarding application to the voltage prediction of the electricity storage device after time t.
蓄電システム、特に、大電流負荷用途蓄電システムにおいて、充電、あるいは、放電に対して時間ｔ後の電池電圧を予測するためには、充電電流印加時、放電電流印加時における内部抵抗による電圧降下を考慮する必要がある。非特許文献１によれば、直流内部抵抗は時間とともに大きく変化し、特に、大電流負荷用途における秒オーダーの充放電において直流内部抵抗の時間依存性は大きく、また、この直流内部抵抗の時間変化は蓄電デバイスの種類、放電深度により異なることが示されている。従って、例えば、特許文献１〜３に記載されている方法で得られる内部抵抗データでは、精度良く時間ｔ後の電池電圧を予測することが難しい。また、直接電圧を印加する方法では、たとえ、直流内部抵抗の時間のファクターを考慮したとしても、充放電にともなうＯＣＶ変化等が電圧情報に含まれることから、精度良く時間ｔ後の電池電圧を予測するには煩雑な手順を含む必要がある。 In a power storage system, in particular, a large current load power storage system, in order to predict a battery voltage after time t with respect to charging or discharging, a voltage drop due to internal resistance at the time of charging current application or discharge current application It is necessary to consider. According to Non-Patent Document 1, the DC internal resistance changes greatly with time. In particular, the time dependency of the DC internal resistance is large in charge and discharge on the order of seconds in a large current load application. Are different depending on the type of storage device and the depth of discharge. Therefore, for example, with the internal resistance data obtained by the methods described in Patent Documents 1 to 3, it is difficult to accurately predict the battery voltage after time t. In addition, in the method of directly applying a voltage, even if the time factor of the DC internal resistance is taken into account, the voltage information includes the OCV change associated with charging / discharging, so the battery voltage after time t can be accurately calculated. Prediction requires complicated procedures.
本発明者は、上記の様な従来技術の問題点に留意しつつ、研究を進めた結果、電流休止から時間ｔ後の電圧変化ΔＶｔより算出される電流休止法に基づく直流内部抵抗Ｒｔを用いることにより、蓄電デバイスの時間ｔ後の蓄電デバイスの電圧Ｖ（ｔ）を簡便で精度良く予測する方法を見出し本発明に至った。 The present inventor has used the DC internal resistance Rt based on the current pause method calculated from the voltage change ΔVt after a time t from the current pause as a result of research while paying attention to the problems of the prior art as described above. Thus, a method for predicting the voltage V (t) of the electricity storage device after time t of the electricity storage device simply and accurately has been found and the present invention has been achieved.
請求項１に記載の蓄電デバイスの電圧予測方法は、蓄電デバイスの充電あるいは放電が 開始されてから時間ｔ後の放電深度Ｑ（ｔ）における開路電圧Ｖ０（ｔ）、印加電流Ｉ（ｔ）（ここでＩ（ｔ）は、放電時には正の値、充電時には負の値をとる）とした時、その時の蓄電デバイスの電圧Ｖ（ｔ）を、予め測定された電流休止から時間ｔ後の電圧変化ΔＶｔより算出される電流休止法に基づく直流内部抵抗Ｒｔを用い、Ｖ（ｔ）＝Ｖ０（ｔ）−Ｉ（ｔ）×Ｒｔより算出することを特徴とする。The voltage predicting method for the electricity storage device according to claim 1 is the open circuit voltage V 0 (t) and the applied current I (t) at the depth of discharge Q (t) after time t from the start of charging or discharging of the electricity storage device. (Here, I (t) takes a positive value at the time of discharging and a negative value at the time of charging), and the voltage V (t) of the electric storage device at that time is a time t after the current pause measured in advance. A direct current internal resistance Rt based on the current pause method calculated from the voltage change ΔVt is used, and V (t) = V 0 (t) −I (t) × Rt.
請求項２に記載の蓄電デバイスの電圧予測方法は、前記印加電流Ｉ（ｔ）が１０Ｃ以上の電流であることを特徴とする。 The method for predicting the voltage of the electricity storage device according to claim 2 is characterized in that the applied current I (t) is a current of 10 C or more.
請求項３に記載の蓄電デバイスの電圧予測方法は、前記放電深度Ｑ（ｔ）が０％を超え７０％以下であることを特徴とする。 The voltage predicting method for an electricity storage device according to claim 3 is characterized in that the depth of discharge Q (t) is more than 0% and 70% or less.
請求項４に記載の蓄電デバイスの電圧予測方法は、前記時間ｔが６０秒以下であることを特徴とする。 The voltage predicting method for an electricity storage device according to claim 4 is characterized in that the time t is 60 seconds or less.
上記請求項１〜４の構成によれば、蓄電デバイスの時間ｔ後の蓄電デバイスの電圧Ｖ（ｔ）を電流休止法に基づく直流内部抵抗Ｒｔを用いることにより簡便で精度良く予測することが可能となる。 According to the configuration of the first to fourth aspects, the voltage V (t) of the power storage device after time t of the power storage device can be easily and accurately predicted by using the DC internal resistance Rt based on the current pause method. It becomes.
本発明の蓄電デバイスの電圧予測方法は、電流休止時における蓄電デバイスの時間に対する電圧変化から求める電流休止法に基づく直流内部抵抗Ｒｔを用いることにより、簡便で予測精度が高く、かつ、実用的に、今後起こる充電、あるいは、放電に対して時間ｔ後の電池電圧を予測可能であるという効果を奏する。 The method for predicting the voltage of the electricity storage device of the present invention is simple, high in prediction accuracy, and practically by using the DC internal resistance Rt based on the current pause method obtained from the voltage change with respect to the time of the electricity storage device during the current pause. The battery voltage after time t can be predicted with respect to charging or discharging that will occur in the future.
本発明の一実施形態について、説明すれば以下の通りである。
本発明の蓄電デバイスの電圧予測方法は、蓄電デバイスの充電あるいは放電が開始され てから時間ｔ後の放電深度Ｑ（ｔ）における開路電圧Ｖ０（ｔ）、印加電流Ｉ（ｔ）（ここでＩ（ｔ）は、放電時には正の値、充電時には負の値をとる）とした時、その時の蓄電デバイスの電圧Ｖ（ｔ）を、予め測定された電流休止から時間ｔ後の電圧変化ΔＶｔより算出される電流休止法に基づく直流内部抵抗Ｒｔを用い、Ｖ（ｔ）＝Ｖ０（ｔ）−Ｉ（ｔ）×Ｒｔより算出することを特徴とする。まず、本発明の電圧予測では基本データとして放電深度に対する開路電圧を用いる。開路電圧のデータは予め取得される、あるいは、取得されたデータから算出されるものであり、放電深度との関数として表される。開路電圧のデータは一定電流で放電あるいは充電しながら、適時電流を休止し、充分な休止後の電圧を測定するが、実用的には予測したい印加電流に対し充分に低い電流で充放電を実施し、その時の充放電電圧を開路電圧として近似することも可能である。ここで温度、劣化レベル等の放電深度と開路電圧の関係に影響を与える因子に関し、開路電圧の補正条件も予め設定することも可能である。更に、蓄電デバイス使用時に、予め取得した上記データを蓄電デバイスの経年劣化状況等に応じ補正することにより、高い精度で予測データを得ることが可能となる。蓄電デバイスの使用においては、常時電流が印加されていることはなく、開路電圧を測定するに充分な休止時間があることが一般的である。本発明では開路電圧を基本データとして使用することにより、上記蓄電デバイスの開路電圧の経年変化も容易に補正することが可能となり、結果として精度の高い電圧予測が可能となる。An embodiment of the present invention will be described as follows.
The method for predicting the voltage of an electricity storage device according to the present invention includes an open circuit voltage V 0 (t) and an applied current I (t) at a discharge depth Q (t) after a time t from when charging or discharging of the electricity storage device starts. I (t) takes a positive value at the time of discharging and a negative value at the time of charging), and the voltage V (t) of the power storage device at that time is a voltage change ΔVt after a time t from the current pause measured in advance. Using the DC internal resistance Rt based on the current pause method calculated from the above, V (t) = V 0 (t) −I (t) × Rt. First, in the voltage prediction of the present invention, an open circuit voltage with respect to the depth of discharge is used as basic data. The open circuit voltage data is acquired in advance or calculated from the acquired data, and is expressed as a function of the depth of discharge. The open circuit voltage data is measured by measuring the voltage after a sufficient pause while discharging or charging at a constant current, but in practice, charging and discharging is performed at a sufficiently low current relative to the applied current that is to be predicted. The charge / discharge voltage at that time can be approximated as an open circuit voltage. Here, with respect to factors that affect the relationship between the discharge depth such as temperature and deterioration level and the open circuit voltage, it is also possible to preset the open circuit voltage correction conditions. Furthermore, when the power storage device is used, it is possible to obtain prediction data with high accuracy by correcting the data acquired in advance according to the aging deterioration state of the power storage device. In the use of an electricity storage device, current is not always applied, and it is general that there is sufficient downtime to measure the open circuit voltage. In the present invention, by using the open circuit voltage as basic data, it is possible to easily correct the secular change of the open circuit voltage of the power storage device, and as a result, it is possible to predict the voltage with high accuracy.
蓄電デバイスの充電あるいは放電が開始されてから時間ｔ後の電圧Ｖ（ｔ）を予測する方法につき説明する。まず、蓄電デバイスの充電あるいは放電が開始されてから時間ｔ後の放電深度Ｑ（ｔ）を設定する。Ｑ（ｔ）は、予測する蓄電デバイスの放電深度、すなわち、時間ｔ＝０における放電深度Ｑ（０）と、予測する時間ｔ内における放電容量、あるいは、充電容量から算出することができる。この予測方法を蓄電システムに実際応用する場合、放電深度は電流積算等の方法により監視する。予測精度を高めるためには、放電深度を、充電末（放電深度０％）での補正、上記放電深度と開路電圧の関係による補正等の手法により補正することも可能である。また、時間ｔ＝０が休止状態であるときは、すなわち、実際の開路電圧を測定することが可能である場合は、上記放電深度と開路電圧の関係から放電深度Ｑ（０）を求めることも可能である。A method for predicting the voltage V (t) after time t from the start of charging or discharging of the electricity storage device will be described. First, the discharge depth Q (t) after the time t from the start of charging or discharging of the electricity storage device is set. Q (t) can be calculated from the predicted discharge depth of the electricity storage device, that is, the discharge depth Q (0) at time t = 0, and the discharge capacity or charge capacity within the predicted time t. When this prediction method is actually applied to a power storage system, the discharge depth is monitored by a method such as current integration. In order to increase the prediction accuracy, the depth of discharge can be corrected by a technique such as correction at the end of charging (
本発明では蓄電デバイスの時間ｔ後の蓄電デバイスの電圧Ｖ（ｔ）をＶ（ｔ）＝Ｖ０（ｔ）−Ｉ（ｔ）×Ｒｔより算出する。Ｖ０（ｔ）は時間ｔ後の蓄電デバイスの開路電圧であり、時間ｔ後の蓄電デバイスの放電深度Ｑ（ｔ）から、上述の予め取得された、あるいは、蓄電デバイス使用時に補正された放電深度と開路電圧の関係より求められる。Ｉ（ｔ）は、予測する時間ｔ後、蓄電デバイスに印加される電流（印加電流）であり、予測する時間ｔ内において印加電流Ｉ（ｔ）が一定である場合、Ｑ（ｔ）＝Ｑ（０）＋〔Ｉ（ｔ）×ｔ／容量×１００％〕の関係がある。Ｉ（ｔ）は、放電時には正の値、充電時には負の値をとる。Ｒｔは蓄電デバイスの時間ｔ後の電流休止法に基づく直流内部抵抗であり、時間tにより変化する値である。In the present invention, the voltage V (t) of the electricity storage device after time t of the electricity storage device is calculated from V (t) = V 0 (t) −I (t) × Rt. V 0 (t) is the open circuit voltage of the electricity storage device after time t, and the discharge obtained previously from the discharge depth Q (t) of the electricity storage device after time t or corrected when the electricity storage device is used. It is obtained from the relationship between depth and open circuit voltage. I (t) is a current (applied current) applied to the electricity storage device after the predicted time t. When the applied current I (t) is constant within the predicted time t, Q (t) = Q (0) + [I (t) × t / capacity × 100%]. I (t) takes a positive value during discharging and takes a negative value during charging. Rt is a direct current internal resistance based on the current pause method after time t of the electricity storage device, and is a value that changes with time t.
本発明の予測方法の特徴は、蓄電デバイスに印加される種々の電流印加における実際の直流内部抵抗の時間変化を、予め測定された電流休止から時間ｔ後の電圧変化ΔＶｔより算出される非特許文献１に記載の電流休止法に基づく直流内部抵抗Ｒｔと等しいとすることにある。図１に蓄電デバイスの電流休止時の電圧変化を例示する。電流休止から時間ｔ後の電圧変化ΔＶｔより算出される電流休止法に基づく直流内部抵抗Ｒｔは、非特許文献１に記載のように、電流休止時直前の電流Ｉｒと電流休止時直前の電圧と電流休止から時間ｔ後の電圧との差ΔＶｔから、Ｒｔ＝ΔＶｔ／Ｉｒで求めることができる。電流休止法に基づく直流内部抵抗Ｒｔは予め測定する必要がある。この時、電流休止時直前の電流Ｉrは特に限定されることはなく、１０Ｃ、１００Ｃと高いレートに対する予測に対しても、０．５Ｃ〜５Ｃに相当するＩrが印加された後の電流休止時電圧変化ΔＶｔから算出されるＲｔを用いることができ、簡便でかつ汎用性が高い。予測に使用する電流休止法に基づく直流内部抵抗Ｒｔは、予測する放電深度の近傍での測定された電流休止時の電圧変化値から算出することが好ましく、例えば、放電深度７０％の電圧を予測する場合、放電深度１０％での電流休止時の電圧変化値から算出される電流休止法に基づく直流内部抵抗Ｒｔを用いることは、蓄電デバイスの種類にもよるが、予測精度の観点から避けたほうが好ましい場合が多い。どの程度近傍の値が必要とされるかについては蓄電デバイスの種類、予測する電流値により異なることから適宜決定する必要があるが、例えば、電気二重層キャパシタでは放電深度５０％の電圧までは、放電深度１０％での電流休止時の電圧変化値から算出される電流休止法に基づく直流内部抵抗Ｒｔを用いて予測可能である。また、充電側の予測には、充電時の電流休止法に基づく直流内部抵抗Ｒｔを、放電側の予測には、放電時の電流休止法に基づく直流内部抵抗Ｒｔを用いることが好ましく、例えば、非特許文献１に記載されているように、電気二重層キャパシタにおいては電流休止法に基づく直流内部抵抗Ｒｔが充電、放電の履歴に依存する場合、この点に特に注意する必要がある。 A feature of the prediction method of the present invention is that non-patents are calculated from a change in voltage ΔVt after a time t from a current pause measured in advance, with respect to the actual change in DC internal resistance over time when various currents are applied to the electricity storage device. It is to be equal to the DC internal resistance Rt based on the current pause method described in Document 1. FIG. 1 exemplifies a voltage change at the time of current suspension of the electricity storage device. As described in Non-Patent Document 1, the DC internal resistance Rt based on the current change method calculated from the voltage change ΔVt after time t from the current stop is the current Ir immediately before the current stop and the voltage immediately before the current stop. Rt = ΔVt / Ir can be obtained from the difference ΔVt from the voltage after time t from the current pause. The DC internal resistance Rt based on the current pause method needs to be measured in advance. At this time, the current Ir immediately before the current stop is not particularly limited, and the current stop after the Ir corresponding to 0.5C to 5C is applied to the prediction for a high rate of 10C and 100C. Rt calculated from the voltage change ΔVt can be used, which is simple and highly versatile. The DC internal resistance Rt based on the current pause method used for prediction is preferably calculated from the voltage change value at the time of current pause measured in the vicinity of the predicted discharge depth. For example, a voltage at a discharge depth of 70% is predicted. In this case, the use of the DC internal resistance Rt based on the current pause method calculated from the voltage change value at the time of current pause at a discharge depth of 10% was avoided from the viewpoint of prediction accuracy although it depends on the type of power storage device. This is often preferred. It is necessary to appropriately determine how close the value is required because it differs depending on the type of storage device and the current value to be predicted. For example, in an electric double layer capacitor, the voltage up to a discharge depth of 50% It can be predicted using the DC internal resistance Rt based on the current pause method calculated from the voltage change value during the current pause at a discharge depth of 10%. Moreover, it is preferable to use the DC internal resistance Rt based on the current pause method during charging for prediction on the charge side, and to use the DC internal resistance Rt based on the current pause method during discharge on the discharge side, for example, As described in Non-Patent Document 1, in an electric double layer capacitor, it is necessary to pay particular attention to this point when the DC internal resistance Rt based on the current pause method depends on the history of charging and discharging.
この予測方法を蓄電システムに実際応用する場合、電流休止から時間ｔ後の電圧変化ΔＶｔを電流休止法により予め測定し、上述の方法による電流休止法に基づく直流内部抵抗Ｒｔを算出することが必要となる。ΔＶｔの測定は蓄電デバイスの使用前に予め取得する、あるいは、使用中に取得する等それが予測前に測定されておれば良く、温度、劣化レベル等の電流休止法に基づく直流内部抵抗Ｒｔに影響を与える因子に関し補正すること、あるいは、使用中の電流休止時の電圧変化から直接補正することが好ましい。また、予測直前に電流休止法による電圧変化ΔＶｔを測定する操作を蓄電デバイスに対し行うことも、蓄電デバイスの使用条件が許すのであれば好ましい。 When this prediction method is actually applied to a power storage system, it is necessary to measure in advance the voltage change ΔVt after time t from the current pause by the current pause method and to calculate the DC internal resistance Rt based on the current pause method by the above method. It becomes. The measurement of ΔVt may be acquired in advance before use of the electricity storage device, or may be acquired before use, such as being acquired during use, and may be measured in accordance with the DC internal resistance Rt based on the current pause method such as temperature and deterioration level. It is preferable to correct with respect to the influencing factors, or to correct directly from the voltage change at the time of current pause during use. It is also preferable to perform an operation on the electricity storage device to measure the voltage change ΔVt by the current pause method immediately before the prediction if the usage conditions of the electricity storage device allow.
本発明の予測方法において、予測する印加電流Ｉ（ｔ）は、特に限定されるものではないが、１０Ｃ以上の電流である場合、本発明の適用効果は大きく、５０Ｃ以上の電流であることが更に適している。また、時間ｔについても、特に限定されるものではないが、６０秒以下であることが本発明の適用効果は大きい。本発明では電流休止法により測定可能となる直流内部抵抗Ｒｔの時間変化を考慮し予測することからその精度が向上する。従って、電流休止法に基づく直流内部抵抗Ｒｔの影響を受けやすい大電流印加時、電流休止法に基づく直流内部抵抗Ｒｔの時間変化が大きい電流印加から短時間内の予測に対し、特に、本発明の予測方法による精度向上効果が大きい。 In the prediction method of the present invention, the applied current I (t) to be predicted is not particularly limited, but when the current is 10 C or more, the application effect of the present invention is large, and the current is 50 C or more. More suitable. Also, the time t is not particularly limited, but the application effect of the present invention is great when it is 60 seconds or less. In the present invention, the accuracy is improved because the prediction is made in consideration of the time change of the DC internal resistance Rt that can be measured by the current pause method. Therefore, when applying a large current that is susceptible to the influence of the DC internal resistance Rt based on the current pause method, the present invention is particularly suitable for prediction within a short time from the current application in which the time change of the DC internal resistance Rt based on the current pause method is large. The accuracy improvement effect by this prediction method is great.
本発明の予測方法において、放電深度Ｑ（ｔ）は、特に限定されるものではないが、０％を超え７０％以下であることが好ましい。これは蓄電デバイスの種類にもよるが、非特許文献１にも記載されているように、例えば、リチウムイオン電池は深い放電深度（電圧が低い領域）において、放電深度増加にともなう直流内部抵抗変化が大きく、これが原因として本発明の予測方法による精度向上効果が得られにくいことがある。 In the prediction method of the present invention, the discharge depth Q (t) is not particularly limited, but is preferably more than 0% and 70% or less. Although this depends on the type of power storage device, as described in Non-Patent Document 1, for example, a lithium ion battery has a change in DC internal resistance with an increase in discharge depth at a deep discharge depth (a region where the voltage is low). As a result, the accuracy improvement effect by the prediction method of the present invention may be difficult to obtain.
本発明の電圧予測方法は、リチウムイオン電池、電気二重層キャパシタ、新型リチウム系蓄電デバイス、Ｎｉ水素電池等の蓄電デバイスに適用可能であるが、特に、ＨＥＶ用蓄電デバイス等の高出力時の電圧予測にその効果が大きい。 The voltage prediction method of the present invention can be applied to power storage devices such as lithium ion batteries, electric double layer capacitors, new lithium-based power storage devices, and Ni-hydrogen batteries. The effect is great for prediction.
以下に実施例を示し、本発明の特徴とするところをさらに明確化するが、本発明は実施例により何ら限定されるものではない。 EXAMPLES Examples will be shown below to further clarify the features of the present invention, but the present invention is not limited to the examples.
（１）比表面積１９５０ｍ２／ｇを有する市販活性炭７７．５重量部、導電材ケッチェンブラック５．８重量部、ＰＶｄＦ（ポリフッ化ビニリデン）１４．２重量部、ＰＶＰ（ポリビニルピロリドン）２．５重量部をＮＭＰ（Ｎ−メチルピロリドン）３５５重量部と混合し、合材スラリーを得た。黒鉛系導電性塗料を予め塗布した厚さ３０μｍのアルミ箔に合材スラリーを片面に塗布し、乾燥した後、プレス加工して、電極層の厚み９１μｍ、電極層密度０．６８ｇ／ｃｍ３の活性炭電極を得た。 (1) 77.5 parts by weight of commercially available activated carbon having a specific surface area of 1950 m 2 / g, 5.8 parts by weight of conductive material ketjen black, 14.2 parts by weight of PVdF (polyvinylidene fluoride), 2.5 PVP (polyvinylpyrrolidone) Part by weight was mixed with 355 parts by weight of NMP (N-methylpyrrolidone) to obtain a composite slurry. A composite slurry was applied to one side of an aluminum foil having a thickness of 30 μm previously coated with a graphite-based conductive paint, dried, and then pressed to form an electrode layer having a thickness of 91 μm and an electrode layer density of 0.68 g / cm 3 . An activated carbon electrode was obtained.
（２）上記、活性炭電極を正極及び負極とし、電気二重層キャパシタを作製した。電極面積は２．８ｃｍ２とし、セパレータにセルロース系不織布、電解液としてプロピレンカーボネートに１.５ｍｏｌ／ｌの濃度にトリエチルメチルアンモニウム（ＴＥＭＡ）ＢＦ４を溶解した溶液を使用した。 (2) The above-mentioned activated carbon electrode was used as a positive electrode and a negative electrode to produce an electric double layer capacitor. The electrode area was 2.8 cm 2 , a cellulose-based non-woven fabric was used as the separator, and a solution obtained by dissolving triethylmethylammonium (TEMA) BF 4 in propylene carbonate at a concentration of 1.5 mol / l as the electrolytic solution was used.
（３）作製したキャパシタを０．６６ｍＡの定電流で２．５Ｖまで充電した後、０．６６ｍＡの電流で０．０Ｖまで放電した。放電カーブを図２に示す。この時の容量は０．６６ｍＡｈであり、この値を放電深度１００％とした。次に非特許文献１に記載されている電流休止法にて全充電過程、全放電過程の電流休止法に基づく直流内部抵抗を測定した。すなわち、１．９８ｍＡの電流を１分５０秒印加し、１０秒休止する操作によりキャパシタの電圧が２．５Ｖになるまで充電後、同様の操作でキャパシタの電圧が０．０Ｖになるまで放電した。１．９８ｍＡの電流を１分５０秒印加した場合、その容量は放電深度変化約１０％に相当する。このようにして得られる各放電深度における電流休止法に基づく直流内部抵抗（休止１０秒後の値）と０．６６ｍＡの定電流充放電結果から開路電圧を計算し、放電深度と開路電圧との関係を得た。 (3) The manufactured capacitor was charged to 2.5 V with a constant current of 0.66 mA, and then discharged to 0.0 V with a current of 0.66 mA. A discharge curve is shown in FIG. The capacity at this time was 0.66 mAh, and this value was defined as a discharge depth of 100%. Next, the direct current internal resistance based on the current pause method of the whole charge process and the whole discharge process was measured by the current pause method described in Non-Patent Document 1. That is, a current of 1.98 mA was applied for 1 minute 50 seconds, and after charging for 10 seconds, the capacitor voltage was charged until it reached 2.5 V, and then the same operation was performed until the capacitor voltage reached 0.0 V. . When a current of 1.98 mA is applied for 1 minute 50 seconds, the capacity corresponds to a change in discharge depth of about 10%. The open circuit voltage is calculated from the DC internal resistance (value after 10 seconds of rest) and the constant current charge / discharge result of 0.66 mA based on the current rest method at each depth of discharge thus obtained. Got a relationship.
（４）このキャパシタの１００Ｃ（６６ｍＡ）で放電した場合の電圧予測及び３００Ｃ（１９８ｍＡ）で放電した場合の時間ｔ後の電圧予測を実施した。（３）で測定した電流休止法に基づく直流内部抵抗の放電時第１回目の休止（放電第一休止点）における時間ｔとΔＶｔ及びΔＶｔと印加電流Ｉｒ＝１．９８ｍＡから計算した直流内部抵抗Ｒｔの結果を表１に示す。表１においては１００ｍｓｅｃ間隔で測定されたデータの一部を説明のため記載している。
（５）放電深度０％から１００Ｃ（６６ｍＡ）で時間ｔ（秒）間放電した場合の放電容量は（６６ｍＡ×ｔ／３６００）ｍＡｈ、放電深度は（６６ｍＡ×ｔ／３６００）／０．６６ｍＡｈ×１００％となる。（３）で得られた放電深度と開路電圧の関係から時間ｔ（秒）後の開路電圧Ｖ０（ｔ）が求まり、Ｖ（ｔ）＝Ｖ０（ｔ）−Ｉ（ｔ）×Ｒｔの関係からＶ（ｔ）を求めた。ここでＩ（ｔ）は６６ｍＡである。同様にして放電深度０％から３００Ｃ（１９８ｍＡ）で時間ｔ（秒）間放電した場合についても表１の電流休止法に基づく直流内部抵抗Ｒｔ、Ｉ（ｔ）＝１９８ｍＡの値を用いて電圧予測を実施した。３００Ｃ（１９８ｍＡ）で時間ｔ（秒）間放電した場合の放電容量は（１９８ｍＡ×ｔ／３６００）ｍＡｈ、放電深度は（１９８ｍＡ×ｔ／３６００）／０．６６ｍＡｈ×１００％となる。結果を図３に示す。また、実際このキャパシタを１００Ｃ（６６ｍＡ）で放電した場合の実測電圧及び３００Ｃ（１９８ｍＡ）で放電した場合の実測電圧を図３に合わせて示す。予測データと実測データがほぼ一致し、精度良く電圧予測できている。 (5) The discharge capacity is (66 mA × t / 3600) mAh and the discharge depth is (66 mA × t / 3600) /0.66 mAh × when discharged for a time t (seconds) from 0% discharge depth to 100 C (66 mA). 100%. The open circuit voltage V 0 (t) after time t (seconds) is obtained from the relationship between the discharge depth and the open circuit voltage obtained in (3), and V (t) = V 0 (t) −I (t) × Rt V (t) was obtained from the relationship. Here, I (t) is 66 mA. Similarly, when the discharge depth is 0% to 300C (198 mA) for a time t (second), the voltage is predicted using the values of DC internal resistance Rt, I (t) = 198 mA based on the current pause method shown in Table 1. Carried out. When discharging at 300 C (198 mA) for time t (seconds), the discharge capacity is (198 mA × t / 3600) mAh, and the discharge depth is (198 mA × t / 3600) /0.66 mAh × 100%. The results are shown in FIG. Also, FIG. 3 shows the measured voltage when this capacitor is actually discharged at 100 C (66 mA) and the measured voltage when discharged at 300 C (198 mA). The predicted data and the measured data are almost the same, and the voltage can be predicted accurately.
本発明の電圧予測法は、例えば、携帯機器用電源、電気自動車、ハイブリッド電気自動車、燃料電池電気自動車等に用いられる蓄電デバイスにおいて、時間ｔ後の電圧Ｖ（ｔ）を電流休止法に基づく直流内部抵抗を用いることにより、簡便で精度良く予測することが可能となる。特に、高出力蓄電デバイスに適用することにより、大電流負荷時におけるシステムの効率低下、過放電、過充電による寿命低下等の課題を解決することができる。 The voltage prediction method according to the present invention is a direct current based on the current pause method, for example, using a voltage V (t) after time t in an electricity storage device used for a power source for portable devices, an electric vehicle, a hybrid electric vehicle, a fuel cell electric vehicle, and the like. By using the internal resistance, it is possible to predict easily and accurately. In particular, when applied to a high-output power storage device, it is possible to solve problems such as a decrease in system efficiency at the time of a large current load, overdischarge, and a decrease in life due to overcharge.
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| JP2000294228A (en) * | 1999-04-06 | 2000-10-20 | Mitsubishi Heavy Ind Ltd | Lithium secondary battery |
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| JP4215152B2 (en) * | 2001-08-13 | 2009-01-28 | 日立マクセル株式会社 | Battery capacity detection method |
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| JP2006153819A (en) * | 2004-12-01 | 2006-06-15 | Canon Inc | Device and method for checking battery |
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