JP3558523B2 - Charging method for non-aqueous secondary batteries - Google Patents
Charging method for non-aqueous secondary batteries Download PDFInfo
- Publication number
- JP3558523B2 JP3558523B2 JP19254098A JP19254098A JP3558523B2 JP 3558523 B2 JP3558523 B2 JP 3558523B2 JP 19254098 A JP19254098 A JP 19254098A JP 19254098 A JP19254098 A JP 19254098A JP 3558523 B2 JP3558523 B2 JP 3558523B2
- Authority
- JP
- Japan
- Prior art keywords
- charging
- specified
- value
- battery
- current value
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Classifications
-
- 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Landscapes
- Secondary Cells (AREA)
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、非水系二次電池の充電方法に関する。
【０００２】
【従来の技術】
近年、携帯電話やノートパソコンなどのコードレス機器の普及がめざましく、それとともに機器の電源となる二次電池の高容量化、高エネルギー密度化の要望がますます高まりつつある。
【０００３】
この二次電池として、高電圧で高エネルギー密度を有するリチウム二次電池のような非水系二次電池に対する期待が大きく、最近、リチウムと遷移金属との複合酸化物を正極活物質とし、リチウムを充放電できる炭素質材料を負極活物質として構成したリチウムイオン二次電池が実用化されている。
【０００４】
このような非水系二次電池を充電する方法としては、一般的に、電池電圧が設定値に達するまでは定電流で充電し、その後、定電圧充電に切り換えるという定電流定電圧充電方式が採用されている（特開平５−１１１１８４号公報、特開平６−３２５７９４号公報、特開平７−２４０２３５号公報）。また、満充電を検知する方法も数多く提案されている（特開平６−１８９４６６号公報、特開平７−１０５９８０号公報、特開平７−２３５３３２号公報）。
【０００５】
【発明が解決しようとする課題】
しかしながら、非水系二次電池では、電池電圧がある値以上になると電解質が
分解し、電池の容量が低下する。従来より採用されている定電流定電圧充電方法
でも、この電解液の分解が電池の容量劣化の一因となる。
【０００６】
本発明は以上に鑑み、優れたサイクル寿命特性を得ることが可能な非水系二次
電池の充電方法を提供することを目的とする。
【０００７】
【課題を解決するための手段】
上記課題を解決するため本発明の非水系二次電池の充電方法は、充放電可能な正極と、非水電解質と、充放電可能な負極とを具備する非水系二次電池を、規定電流値Ｉ1で定電流充電し、前記充電により前記二次電池の閉路電圧が規定値に到達した後、連続して前記電池の閉路電圧を前記規定電圧値に維持する定電流定電圧充電行程において、前記電池を規定電流値で定電流充電する際、まず第１規定電流値Ｉ1で充電し、このとき前記電池の閉路電圧Ｖ（Ｉ1）の時間に対する変化率ｄＶ（Ｉ1）を検出し、前記変化率ｄＶ（Ｉ1）が規定値以下の値になれば、前記第１規定電流値より大きい第２規定電流値Ｉ2で充電することを特徴とする。
【０００８】
また、充放電可能な正極と、非水電解質と、充放電可能な負極とを具備する非水系二次電池を、規定電流値Ｉ3で定電流充電し、前記充電により前記二次電池の閉路電圧が規定値に到達した後、連続して前記電池の閉路電圧を前記規定電圧値に維持する定電流定電圧充電行程において、前記電池を規定電流値で定電流充電する際、まず第３規定電流値Ｉ3で充電し、同時に前記電池のインピーダンスＺ（Ｉ3）を測定し、前記インピーダンス値Ｚ（Ｉ3）もしくは前記インピーダンス値の時間に対する変化率ｄＺ（Ｉ3）が規定値以下の値になれば、前記第３規定電流値Ｉ3より大きい第４規定電流値Ｉ4で前記電池を充電することを特徴とする。
【０００９】
また、充放電可能な正極と、非水電解質と、充放電可能な負極とを具備する非水系二次電池を、規定電流値Ｉ5で定電流充電し、前記充電により前記二次電池の閉路電圧が規定値に到達した後、連続して前記電池の閉路電圧を前記規定電圧値に維持する定電流定電圧充電行程において、前記電池を第５規定電流値Ｉ5で定電流充電する際、前記Ｉ5とは異なる第６規定電流値Ｉ6を規定時間間隔Ｔで規定時間通電し、前記第６規定電流値Ｉ6の通電回数がｎ回目の前記第６規定電流値Ｉ6の通電開始時から、第１規定時間ｔ1と第２規定時間ｔ2とが経過したときの、前記電池の閉路電圧をそれぞれＶ（ｔ1）T(n)およびＶ（ｔ2）T(n)とし、かつ、前記第６規定電流値Ｉ6の通電回数が（ｎ−１）回目の前記第６規定電流値Ｉ6の通電開始時から、第１規定時間ｔ1と第２規定時間ｔ2とが経過したときの、前記電池の閉路電圧をそれぞれＶ（ｔ1）T(n-1)およびＶ（ｔ2）T(n-1)とすると、｜Ｖ（ｔ1）T(n)−Ｖ（ｔ2）T(n)｜もしくは｜｛Ｖ（ｔ1）T(n)−Ｖ（ｔ2）T(n)｝−｛Ｖ（ｔ1）T(n-1)−Ｖ（ｔ2）T(n-1)｝｜が、規定値以下の値になれば前記第５規定電流値Ｉ5より大きな第７規定電流Ｉ7で定電流充電を行うことを特徴とする。
【００１０】
以上で用いる非水系二次電池は、リチウムと遷移金属との複合酸化物を正極活物質とし、リチウムを充放電できる炭素質材料を負極活物質として構成することが効果的である。
【００１１】
【発明の実施の形態】
従来の定電流定電圧充電方式では、満充電するためには、定電圧充電モードに入った後、４．２Ｖ程度の電圧でしばらく保持しなければならない。現行の非水系二次電池に用いられている電解質では、通常、分解電圧が４．２Ｖ以下であるため、この定電圧充電中に電解質の分解が起こり、これがサイクル劣化の要因の一つになると考えられている。したがって、電池電圧が電解質の分解電圧に達する前に充電を停止すれば、サイクル劣化の要因の一つを排除することができる。
【００１２】
また、上記のように電解質の分解を起こさないようにするのではなく、電解質の分解をより少なく抑えるようにしても、サイクル劣化を改善することが可能となる。定電流定電圧充電方式の場合、定電圧充電時間を短くする、あるいは定電圧充電を行わないようにすれば、電解質の分解を少なく抑えることができる。このように定電圧充電時間を短くする、あるいは定電圧充電を行わないようにするということは、すなわち定格容量に達する前に充電を停止することであるので、定格容量に達する前に充電を停止すればサイクル劣化を改善することができる。ここで、定格容量とは現行の充電方式で充電した場合の容量である。
【００１３】
定電流定電圧充電方式では、定電圧充電モードに入ると次第に充電電流が減少する。したがって、定電圧充電モードでは充電容量の増加率も時間とともに減少するので、充電容量の時間に対する変化率を検出し、その値によって充電を制御すれば、定格容量に達する前に充電を停止することができる。また、充電電流の時間に対する変化率を検出し、その変化率の絶対値によって充電を制御しても、定格容量に達する前に充電を停止することができる。単純に、タイマー制御を行っても定格容量に達する前に充電を停止することは可能である。その場合、タイマーを作動させるタイミングは定電流充電開始時、あるいは定電圧充電開始時のいずれでもかまわない。
【００１４】
リチウムイオン二次電池では定格容量に対する充電状態が非常に低い状態（定格容量に対して、ほぼ１０％以下の充電状態）では、電池の内部インピーダンスが大きい。例えば、複素インピーダンス測定を行うと、インピーダンスの実数成分−虚数成分図において、１０Ｈｚから０．１Ｈｚの低周波数領域に円弧が出現するが、定格容量に対して１０％以下の充電状態では前述の円弧が大きくなる。これは定格容量に対して１０％以下の充電状態では反応抵抗が大きくなることを示しており、そのような反応抵抗の大きい領域に対して大きな電流で充電しようとすると、電極活物質と電解液との界面で通常の充電反応以外の副反応が発生し、電池特性を損なう原因となると考えられる。したがって、反応抵抗の大きい領域では充電レートを小さくしておき、反応抵抗が小さくなった時に充電レートを大きくするようにすれば、サイクル特性を低下することなく、充電時間の短縮を図ることができる。
【００１５】
このとき、定電流充電中を開始すると同時に、一定時間毎にインピーダンス測定を行い、その測定から得られるインピーダンス値、あるいは前回の測定時のインピーダンス値との差が規定値以下になったときに充電レートを大きくすればよい。通常、インピーダンス測定では、測定周波数領域に現れた円弧のフィッティングを施し、実数軸との交点から抵抗値を求めるが、本発明では、１００ｍＨｚ程度の低周波数領域の１点での測定から得られるインピーダンス値を前述の抵抗値の代用としても支障はない。また、電池電圧の時間に対する変化率を検出し、その値が規定値以下になったときに充電レートを大きくしてもよい。
【００１６】
定電流充電を開始すると同時に、一定時間毎に異なる電流での短時間の充電あるいは短時間の休止を挿入し、その間の電圧挙動、すなわちＩＲドロップによる変化分を除いた電池電圧の変化量、あるいは前回の短時間の充電期間あるいは前回の休止期間における変化量との差を検出し、その値から充電レートを切り替えることも可能である。ＩＲドロップによる変化分を除いた電池電圧の挙動は前述の反応抵抗の影響を受けると思われるので、反応抵抗が大きければ、その電池電圧の変化量も大きくなる。したがって、その電池電圧の変化量あるいは前回の変化量との差が規定値以下になったときに充電レートを大きくすればよい。
【００１７】
以下に本発明の実施例について説明する。
（参考例１）
まず、以下のような方法で円筒型リチウムイオン二次電池を作製した。
【００１８】
正極活物質であるＬｉＣｏＯ2粉末１００重量部とアセチレンブラック３重量部、フッ素樹脂系結着剤７重量部とを混合して正極合剤とし、カルボキシメチルセルロース水溶液に懸濁させてペースト状にした。このペーストをアルミ箔に塗着し、乾燥後圧延したものを正極板とした。また、負極活物質である黒鉛粉末１００重量部とスチレン／ブタジエンゴム４重量部を混合したものを負極合剤とし、カルボキシメチルセルロース水溶液に懸濁させてペースト状にした。このペーストを銅箔に塗着し、乾燥後圧延したものを負極板とした。この正極板および負極板をポリプロピレン製多孔性フィルムであるセパレータを介して渦巻き状に巻回してＡサイズの電槽に挿入し、封口した。なお、電解液にはエチレンカーボネートとエチルメチルカーボネートの混合溶媒にＬｉＰＦ6を溶解したものを用いた。
【００１９】
このようにして作製した電池を、２０℃において、５００ｍＡで定電流充電し、電池電圧が４．２Ｖに達すれば定電圧充電に切り替え、合計２時間で充電を終了し、７２０ｍＡで３．０Ｖまで放電して、電池容量が７８０ｍＡｈであることを確認し、これを定格容量とした。
【００２０】
上記の電池を用いて、本発明の充電方法を用いた場合と従来の充電方法を用いた場合のサイクル寿命特性を比較した。上記の電解液を用いた場合、電解液の分解電圧は４．０Ｖから４．１Ｖ程度であると言われているので、本発明の充電方法を用いた実施例として、３６０ｍＡで定電流充電を行い、４．０Ｖでカットしたものをサンプル１とした。また、電解液の分解電圧には達しているが、その分解電圧以上の電圧で維持しない参考例として、５００ｍＡで定電流充電を行い、４．１Ｖでカットしたものをサンプル２、５００ｍＡで定電流充電を行い、４．２Ｖでカットしたものをサンプル３とした。これらに対して、従来の充電方法、すなわち５００ｍＡで定電流充電し、４．２Ｖに達すると定電圧充電に切り替え、合計２時間でカットしたものを比較例とした。
【００２１】
このような参考例および比較例の充放電サイクルを行い、その結果得られたサイクル寿命特性を図１に示した。なお、いずれの場合も放電は３．０Ｖまで行った。本実施例であるサンプル１〜３では定格容量に達する前に充電を停止しているので、比較例に比べてサイクル初期の電池容量は小さいが、充放電サイクルに伴う容量劣化は小さく、特に電解液の分解電圧に達する前に充電を停止したサンプル１では容量劣化は非常に小さかった。そして、充放電サイクルを繰り返すうちに容量が比較例を上回るようになった。
【００２２】
以上のように、本参考例では従来よりも優れたサイクル寿命特性が得られることがわかった。
【００２３】
（参考例２）
参考例１と同様に円筒型リチウムイオン二次電池を作製し、電池容量が７８０ｍＡｈであることを確認し、これを定格容量とした。
【００２４】
このような電池を用いて、本発明の充電方法を用いた場合と従来の充電方法を用いた場合のサイクル寿命特性を比較した。本発明の充電方法を用いた実施例として、５００ｍＡで定電流充電を行い、電池電圧が４．２Ｖに達すると定電圧充電に切り替え、充電容量の時間に対する変化率が０．０７ｍＡｈ／秒以下になったときに充電を停止したものをサンプル４とした。この場合、充電中に電流積算により充電容量を求め、１分ごとに充電容量の時間変化率を求めた。なお、定電流充電中は充電容量の時間変化率は一定で、０．１４ｍＡｈ／秒である。
【００２５】
また、５００ｍＡで定電流充電を行い、電池電圧が４．２Ｖに達すると定電圧充電に切り替え、定電圧充電モードに入った後の充電電流の時間に対する変化率の絶対値が０．３ｍＡ／秒以下になったときに充電を停止したものをサンプル５とした。この場合、充電中に充電電流を検出し、１分ごとに充電電流の時間変化率を算出した。もちろん定電流充電中は充電電流の時間変化率はゼロである。
【００２６】
さらに、５００ｍＡで定電流充電を開始すると同時にタイマーを作動させ、電池電圧が４．２Ｖに達すると定電圧充電に切り替え、８５分で充電を停止したものをサンプル６とした。
【００２７】
比較例は参考例１で用いたものと同じである。
このような実施例および比較例の充放電サイクルを行い、その結果得られたサイクル寿命特性を図２に示した。なお、いずれの場合も放電は３．０Ｖまで行った。本参考例であるサンプル４〜６では定格容量に達する前に充電を停止しているので、比較例に比べてサイクル初期の電池容量は小さいが、充放電サイクルに伴う容量劣化は小さくなった。そして、充放電サイクルを繰り返すうちに容量が比較例を上回るようになった。
【００２８】
以上のように、本参考例では従来よりも優れたサイクル寿命特性が得られることがわかった。
【００２９】
（実施例１）
参考例１と同様に円筒型リチウムイオン二次電池を作製し、電池容量が７８０ｍＡｈであることを確認し、これを定格容量とした。
【００３０】
このような電池を用いて、本発明の充電方法を用いた場合と従来の充電方法を用いた場合のサイクル寿命特性を比較した。本発明の充電方法を用いた実施例として、５００ｍＡで定電流充電を開始すると同時にタイマーを作動させ、電池電圧の時間に対する変化率が０．１５ｍＶ／秒以下になったときに充電電流を８００ｍＡに大きくし、電池電圧が４．２Ｖに達すると定電圧充電に切り替え、５８分で充電を停止したものをサンプル７とした。
【００３１】
また、５００ｍＡで定電流充電を開始すると同時にタイマーを作動させ、さらに、１０秒ごとに５００ミリ秒の休止を挿入し、その休止期間のＩＲドロップによる変化分を除いた電池電圧の変化量と前回の変化量との差が０．６ｍＶ以下になったときに充電電流を８００ｍＡに大きくし、電池電圧が４．２Ｖに達すると定電圧充電に切り替え、５８分で充電を停止したものをサンプル８とした。
【００３２】
比較例は参考例１で用いたものと同じである。
このような実施例および比較例の充放電サイクルを行い、その結果得られたサイクル寿命特性を図３に示した。なお、いずれの場合も放電は３．０Ｖまで行った。本実施例であるサンプル７および８では定格容量に達する前に充電を停止しているので、比較例に比べてサイクル初期の電池容量は小さいが、充放電サイクルに伴う容量劣化は小さくなった。そして、充放電サイクルを繰り返すうちに容量が比較例を上回るようになった。
【００３３】
また、サンプル７および８における電池容量は参考例２のサンプル６の電池容量とほぼ同じであるが、サンプル６では充電時間が８５分であるのに対して、サンプル７および８では充電時間が５８分に短縮できたこともわかった。
【００３４】
以上のように、本実施例では従来よりも優れたサイクル寿命特性が得られ、しかも充電時間の短縮を図ることも可能であることがわかった。
【００３５】
なお、５００ｍＡで定電流充電を開始すると同時に、一定時間毎に振幅１０ｍＡ、周波数１００ｍＨｚで交流インピーダンス測定を行い、得られるインピーダンス値と前回の測定時に得られたインピーダンス値との差が規定値以下になったときに充電電流を８００ｍＡに大きくする場合や、５００ｍＡで定電流充電を開始すると同時に、一定時間毎に８００ｍＡでの５００ミリ秒間の充電を挿入し、その充電期間のＩＲドロップによる変化分を除いた電池電圧の変化量と前回の８００ｍＡでの充電時の変化量との差が規定値以下になったときに充電電流を８００ｍＡに大きくする場合においても同様の結果が得られる。
【００３６】
【発明の効果】
上記実施例から明らかなように、本発明によれば、サイクル寿命特性に優れた非水系二次電池の充電方法が得られる。
【図面の簡単な説明】
【図１】本発明の第１の参考例および比較例で評価した電池のサイクル寿命特性を示した図
【図２】本発明の第２の参考例および比較例で評価した電池のサイクル寿命特性を示した図
【図３】本発明の実施例および比較例で評価した電池のサイクル寿命特性を示した図[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for charging a non-aqueous secondary battery.
[0002]
[Prior art]
2. Description of the Related Art In recent years, cordless devices such as mobile phones and notebook personal computers have been remarkably spread, and at the same time, demands for higher capacity and higher energy density of secondary batteries serving as power sources for the devices have been increasing.
[0003]
As this secondary battery, there is great expectation for non-aqueous secondary batteries such as a lithium secondary battery having a high voltage and a high energy density, and recently, a composite oxide of lithium and a transition metal has been used as a positive electrode active material, and lithium has been used. BACKGROUND ART A lithium ion secondary battery including a chargeable and dischargeable carbonaceous material as a negative electrode active material has been put to practical use.
[0004]
As a method of charging such a non-aqueous secondary battery, generally, a constant current / constant voltage charging method in which the battery is charged with a constant current until the battery voltage reaches a set value and then switched to a constant voltage charging is adopted. (JP-A-5-111184, JP-A-6-325794, and JP-A-7-240235). Also, many methods of detecting full charge have been proposed (Japanese Patent Application Laid-Open Nos. 6-189466, 7-105980, and 7-235332).
[0005]
[Problems to be solved by the invention]
However, in a non-aqueous secondary battery, when the battery voltage exceeds a certain value, the electrolyte is decomposed, and the capacity of the battery decreases. Even in the conventional constant-current and constant-voltage charging method, the decomposition of the electrolytic solution contributes to the deterioration of the capacity of the battery.
[0006]
In view of the above, an object of the present invention is to provide a method for charging a non-aqueous secondary battery capable of obtaining excellent cycle life characteristics.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the method for charging a non-aqueous secondary battery of the present invention includes a non-aqueous secondary battery including a chargeable / dischargeable positive electrode, a nonaqueous electrolyte, and a chargeable / dischargeable negative electrode. and constant-current charging at I 1, after the closed circuit voltage of the secondary battery by the charge reaches a prescribed value, in the constant current constant voltage charging step of continuously maintaining a closed circuit voltage of the battery to the specified voltage value, when constant current charging said battery at a specified current value, and charged first with a first specified current value I 1, this time to detect the rate of change dV (I 1) for the closed circuit voltage V (I 1) of time of the battery When the rate of change dV (I 1 ) is equal to or less than a specified value, the battery is charged with a second specified current value I 2 which is larger than the first specified current value.
[0008]
In addition, a non-aqueous secondary battery including a chargeable / dischargeable positive electrode, a nonaqueous electrolyte, and a chargeable / dischargeable negative electrode is charged at a constant current at a specified current value I 3 , and the charging causes the secondary battery to close. After the voltage reaches the specified value, in the constant current / constant voltage charging step for continuously maintaining the closed circuit voltage of the battery at the specified voltage value, when performing constant current charging of the battery at the specified current value, first the third specified was charged at a current value I 3, at the same time the measured impedance Z (I 3) of the battery, the impedance value Z (I 3) or the rate of change dZ (I 3) is a specified value or less of the value for the time of the impedance value if the, characterized in that charging the battery in the third specified current value I 3 is greater than the fourth prescribed current value I 4.
[0009]
Further, a rechargeable positive electrode, a nonaqueous electrolyte, the nonaqueous secondary battery comprising a chargeable and dischargeable negative electrode, a constant current charge at a specified current value I 5, closing of the secondary battery by the charge after the voltage reaches a prescribed value, in the constant current constant voltage charging step of continuously maintaining a closed circuit voltage of the battery to the prescribed voltage value, when the constant current charging the battery in the fifth prescribed current value I 5, the energizing specified time different from the sixth prescribed current value defining the I 6 time intervals T and I 5, the start of energization of the sixth prescribed current value the sixth prescribed current value I 6 energization number of n-th I 6 From time, when the first specified time t 1 and the second specified time t 2 have elapsed, the closing voltages of the battery are V (t 1 ) T (n) and V (t 2 ) T (n) , respectively. and, from the sixth prescribed number of times of energization of the electric current value I 6 is (n-1) th energization start of the sixth prescribed current value I 6, Of 1N time t 1 and when a second predetermined time t 2 has elapsed, the respective V (t 1) closed circuit voltage of the battery T (n-1) and V (t 2) T (n -1) and Then, | V (t 1) T (n) -V (t 2) T (n) | or | {V (t 1) T (n) -V (t 2) T (n)} - {V ( t 1 ) T (n-1) -V (t 2 ) T (n-1) ｝ | becomes a seventh specified current I 7 which is larger than the fifth specified current value I 5 if the value becomes equal to or less than a specified value. It is characterized by performing constant current charging.
[0010]
In the non-aqueous secondary battery used above, it is effective to configure a composite oxide of lithium and a transition metal as a positive electrode active material and a carbonaceous material capable of charging and discharging lithium as a negative electrode active material.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
In the conventional constant-current and constant-voltage charging method, in order to fully charge the battery, it is necessary to maintain the voltage at about 4.2 V for a while after entering the constant-voltage charging mode. Since the decomposition voltage of the electrolyte used in the current non-aqueous secondary battery is usually 4.2 V or less, decomposition of the electrolyte occurs during this constant voltage charging, and this is one of the factors of cycle deterioration. It is considered. Therefore, if charging is stopped before the battery voltage reaches the decomposition voltage of the electrolyte, one of the causes of cycle deterioration can be eliminated.
[0012]
In addition, even if the decomposition of the electrolyte is not reduced as described above, the decomposition of the electrolyte can be reduced even if the decomposition of the electrolyte is suppressed to a lower level. In the case of the constant current / constant voltage charging method, if the constant voltage charging time is shortened or the constant voltage charging is not performed, the decomposition of the electrolyte can be reduced. Shortening the constant voltage charging time or not performing constant voltage charging in this way means stopping charging before reaching the rated capacity, so stopping charging before reaching the rated capacity. Then, cycle deterioration can be improved. Here, the rated capacity is the capacity when charged by the current charging method.
[0013]
In the constant current / constant voltage charging method, the charging current gradually decreases when the constant voltage charging mode is entered. Therefore, in the constant voltage charging mode, the rate of increase of the charging capacity also decreases with time.If the rate of change of the charging capacity with respect to time is detected and charging is controlled based on the value, charging can be stopped before reaching the rated capacity. Can be. Further, even if the rate of change of the charging current with respect to time is detected and charging is controlled based on the absolute value of the rate of change, charging can be stopped before reaching the rated capacity. Simply, even if the timer control is performed, it is possible to stop charging before reaching the rated capacity. In that case, the timing for operating the timer may be either the start of constant current charging or the start of constant voltage charging.
[0014]
In a lithium ion secondary battery, when the state of charge with respect to the rated capacity is very low (about 10% or less of the state of charge with respect to the rated capacity), the internal impedance of the battery is large. For example, when a complex impedance measurement is performed, an arc appears in a low frequency range from 10 Hz to 0.1 Hz in the real component-imaginary component diagram of the impedance. Becomes larger. This indicates that the reaction resistance increases in a state of charge of 10% or less of the rated capacity, and if an attempt is made to charge a region having such a high reaction resistance with a large current, the electrode active material and the electrolyte It is considered that a side reaction other than the normal charging reaction occurs at the interface with the, and this causes deterioration of battery characteristics. Therefore, if the charging rate is reduced in a region where the reaction resistance is large, and the charging rate is increased when the reaction resistance is reduced, the charging time can be reduced without lowering the cycle characteristics. .
[0015]
At this time, at the same time that constant-current charging is started, impedance measurement is performed at regular time intervals, and charging is performed when the impedance value obtained from the measurement or the difference from the impedance value at the previous measurement is less than the specified value. You only need to increase the rate. Usually, in the impedance measurement, fitting of an arc appearing in a measurement frequency region is performed, and a resistance value is obtained from an intersection with a real axis. In the present invention, an impedance obtained from a measurement in one point in a low frequency region of about 100 mHz is obtained. There is no problem even if the value is used in place of the above-mentioned resistance value. Alternatively, the rate of change of the battery voltage with respect to time may be detected, and the charge rate may be increased when the value falls below a specified value.
[0016]
At the same time as starting the constant-current charging, a short-time charging with a different current or a short-time pause is inserted at regular time intervals, and the voltage behavior during that period, that is, the amount of change in the battery voltage excluding the change due to the IR drop, or It is also possible to detect the difference from the amount of change in the previous short charging period or the previous pause period, and switch the charging rate from that value. Since the behavior of the battery voltage excluding the change due to the IR drop is considered to be affected by the above-described reaction resistance, the larger the reaction resistance, the larger the amount of change in the battery voltage. Therefore, the charge rate may be increased when the change amount of the battery voltage or the difference from the previous change amount becomes equal to or less than the specified value.
[0017]
Hereinafter, examples of the present invention will be described.
( Reference Example 1)
First, a cylindrical lithium ion secondary battery was manufactured by the following method.
[0018]
100 parts by weight of LiCoO 2 powder, which is a positive electrode active material, 3 parts by weight of acetylene black, and 7 parts by weight of a fluororesin binder were mixed to form a positive electrode mixture, which was suspended in an aqueous solution of carboxymethyl cellulose to form a paste. This paste was applied to an aluminum foil, dried and rolled to obtain a positive electrode plate. A mixture of 100 parts by weight of graphite powder, which is a negative electrode active material, and 4 parts by weight of styrene / butadiene rubber was used as a negative electrode mixture, and suspended in an aqueous carboxymethyl cellulose solution to form a paste. This paste was applied to a copper foil, dried and rolled to obtain a negative electrode plate. The positive electrode plate and the negative electrode plate were spirally wound through a separator made of a porous film made of polypropylene, inserted into an A-size container, and sealed. The electrolyte used was a solution in which LiPF 6 was dissolved in a mixed solvent of ethylene carbonate and ethyl methyl carbonate.
[0019]
The battery thus prepared was charged at a constant current of 500 mA at 20 ° C., and switched to a constant voltage charge when the battery voltage reached 4.2 V. The charging was completed in a total of 2 hours, and reached a voltage of 3.0 mA at 720 mA. After discharging, it was confirmed that the battery capacity was 780 mAh, and this was defined as the rated capacity.
[0020]
Using the above batteries, the cycle life characteristics of the case using the charging method of the present invention and the case of using the conventional charging method were compared. When the above-mentioned electrolytic solution is used, the decomposition voltage of the electrolytic solution is said to be about 4.0 V to 4.1 V. Therefore, as an example using the charging method of the present invention, constant current charging at 360 mA is performed. Then, the sample cut at 4.0 V was used as Sample 1. Further, as a reference example which has reached the decomposition voltage of the electrolytic solution but is not maintained at a voltage equal to or higher than the decomposition voltage, a constant current charge at 500 mA and a cut at 4.1 V were taken as a sample at a constant current of 500 mA. The battery was charged and cut at 4.2 V to obtain Sample 3. On the other hand, the conventional charging method, that is, constant-current charging at 500 mA, switching to constant-voltage charging when the voltage reached 4.2 V, and cutting in a total of 2 hours was used as a comparative example.
[0021]
The charge / discharge cycle of the reference example and the comparative example was performed, and the cycle life characteristics obtained as a result are shown in FIG. In each case, the discharge was performed up to 3.0V. In Samples 1 to 3 of this embodiment, charging was stopped before reaching the rated capacity. Therefore, the battery capacity at the beginning of the cycle was smaller than that of the comparative example, but the capacity deterioration due to the charge / discharge cycle was small. In sample 1 in which charging was stopped before reaching the decomposition voltage of the liquid, the capacity deterioration was very small. And the capacity came to exceed the comparative example while repeating the charge / discharge cycle.
[0022]
As described above, in the present reference example, it was found that cycle life characteristics superior to those of the related art were obtained.
[0023]
( Reference Example 2)
A cylindrical lithium ion secondary battery was produced in the same manner as in Reference Example 1, and it was confirmed that the battery capacity was 780 mAh.
[0024]
Using such a battery, the cycle life characteristics when using the charging method of the present invention and when using the conventional charging method were compared. As an example using the charging method of the present invention, constant-current charging was performed at 500 mA, and when the battery voltage reached 4.2 V, switching to constant-voltage charging was performed, and the rate of change of the charging capacity with respect to time was reduced to 0.07 mAh / sec or less. When charging was stopped, Sample 4 was used. In this case, the charging capacity was obtained by current integration during charging, and the time change rate of the charging capacity was obtained every minute. During the constant current charging, the time change rate of the charging capacity is constant and is 0.14 mAh / sec.
[0025]
In addition, constant current charging is performed at 500 mA, and when the battery voltage reaches 4.2 V, switching to constant voltage charging is performed. The absolute value of the rate of change of the charging current with respect to time after entering the constant voltage charging mode is 0.3 mA / sec. The sample whose charging was stopped when the following conditions were reached was designated as Sample 5. In this case, the charging current was detected during charging, and the time change rate of the charging current was calculated every minute. Of course, during constant current charging, the time rate of change of the charging current is zero.
[0026]
Further, the constant current charging was started at 500 mA, and at the same time, the timer was operated. When the battery voltage reached 4.2 V, the charging was switched to the constant voltage charging.
[0027]
The comparative example is the same as that used in Reference Example 1.
The charge / discharge cycles of the examples and comparative examples were performed, and the cycle life characteristics obtained as a result are shown in FIG. In each case, the discharge was performed up to 3.0V. In Samples 4 to 6 of this reference example, the charging was stopped before reaching the rated capacity, so that the battery capacity at the beginning of the cycle was smaller than that of the comparative example, but the capacity deterioration due to the charge / discharge cycle was smaller. And the capacity came to exceed the comparative example while repeating the charge / discharge cycle.
[0028]
As described above, in the present reference example, it was found that cycle life characteristics superior to those of the related art were obtained.
[0029]
(Example 1 )
A cylindrical lithium ion secondary battery was produced in the same manner as in Reference Example 1, and it was confirmed that the battery capacity was 780 mAh.
[0030]
Using such a battery, the cycle life characteristics when using the charging method of the present invention and when using the conventional charging method were compared. As an example using the charging method of the present invention, the constant current charging is started at 500 mA, and at the same time, the timer is operated. When the rate of change of the battery voltage with respect to time becomes 0.15 mV / sec or less, the charging current is increased to 800 mA. When the battery voltage reached 4.2 V, the charging was switched to constant voltage charging, and charging was stopped in 58 minutes.
[0031]
At the same time, the constant current charging was started at 500 mA, the timer was started at the same time, and a pause of 500 milliseconds was inserted every 10 seconds. The charge current was increased to 800 mA when the difference from the change amount of the battery became 0.6 mV or less, and switched to constant voltage charging when the battery voltage reached 4.2 V, and charging was stopped in 58 minutes. And
[0032]
The comparative example is the same as that used in Reference Example 1.
The charge / discharge cycles of the examples and comparative examples were performed, and the resulting cycle life characteristics are shown in FIG. In each case, the discharge was performed up to 3.0V. Since charging was stopped before reaching the rated capacity in the samples 7 and 8 of the present example, the battery capacity at the beginning of the cycle was smaller than that of the comparative example, but the capacity deterioration due to the charge / discharge cycle was smaller. And the capacity came to exceed the comparative example while repeating the charge / discharge cycle.
[0033]
The battery capacities of Samples 7 and 8 are almost the same as the battery capacities of Sample 6 of Reference Example 2. However, while the charging time of Sample 6 is 85 minutes, the charging time of Samples 7 and 8 is 58%. It turned out that it could be reduced to minutes.
[0034]
As described above, in this example, it was found that cycle life characteristics superior to those of the related art were obtained, and that the charging time could be shortened.
[0035]
In addition, at the same time as starting the constant current charging at 500 mA, an AC impedance measurement is performed at a constant time at an amplitude of 10 mA and a frequency of 100 mHz, and the difference between the obtained impedance value and the impedance value obtained at the previous measurement is equal to or less than a specified value. When the charging current is increased to 800 mA at the time when the constant current charging is started at 500 mA, charging at 800 mA for 500 milliseconds is inserted at regular time intervals, and the change due to the IR drop during the charging period is calculated. Similar results can be obtained when the charging current is increased to 800 mA when the difference between the removed battery voltage variation and the variation during charging at the previous time of 800 mA is equal to or less than a specified value.
[0036]
【The invention's effect】
As is clear from the above examples, according to the present invention, a method for charging a non-aqueous secondary battery having excellent cycle life characteristics can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram showing cycle life characteristics of batteries evaluated in a first reference example and a comparative example of the present invention. FIG. 2 is a cycle life characteristic of batteries evaluated in a second reference example and a comparative example of the present invention. shows the cycle life characteristics of the battery were evaluated in real施例and comparative example of FIG. 3 shows the present invention showing the
Claims (4)
前記第６規定電流値Ｉ6の通電回数が（ｎ−１）回目の前記第６規定電流値Ｉ6の通電開始時から、第１規定時間ｔ1と第２規定時間ｔ2とが経過したときの、前記電池の閉路電圧をそれぞれＶ（ｔ1）T(n-1)およびＶ（ｔ2）T(n-1)とすると、｜Ｖ（ｔ1）T(n)−Ｖ（ｔ2）T(n)｜もしくは｜｛Ｖ（ｔ1）T(n)−Ｖ（ｔ2）T(n)｝−｛Ｖ（ｔ1）T(n-1)−Ｖ（ｔ2）T(n-1)｝｜が、規定値以下の値になれば前記第５規定電流値Ｉ5より大きな第７規定電流Ｉ7で定電流充電を行うことを特徴とする非水系二次電池の充電方法。A rechargeable positive electrode, a nonaqueous electrolyte, the nonaqueous secondary battery comprising a chargeable and dischargeable negative electrode, a constant current charge at a specified current value I 5, the closed circuit voltage of the secondary battery by the charge after reaching the prescribed value, the constant current constant voltage charging step of continuously maintaining a closed circuit voltage of the battery to the prescribed voltage value, when the constant current charging the battery in the fifth prescribed current value I 5, the I A sixth specified current value I 6 different from 5 is supplied at a specified time interval T for a specified time, and the number of times of application of the sixth specified current value I 6 is n times from the start of energization of the sixth specified current value I 6. When the first specified time t 1 and the second specified time t 2 have elapsed, the closed circuit voltages of the battery are V (t 1 ) T (n) and V (t 2 ) T (n) , respectively; and ,
From the energization start time of the sixth prescribed number of times of energization of the electric current value I 6 is (n-1) th of said sixth prescribed current value I 6, the first specified time t 1 and the t 2 a second specified time has elapsed At this time, when the closed circuit voltages of the batteries are V (t 1 ) T (n−1) and V (t 2 ) T (n−1) , respectively, | V (t 1 ) T (n) −V (t 2) T (n) | or | {V (t 1) T (n) -V (t 2) T (n)} - {V (t 1) T (n-1) -V (t 2) T (n-1)} | is a large seventh prescribed current I 7 than the fifth prescribed current value I 5 if the value of the specified value or less of the nonaqueous secondary battery, characterized by performing the constant current charging Charging method.
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19254098A JP3558523B2 (en) | 1998-07-08 | 1998-07-08 | Charging method for non-aqueous secondary batteries |
| US09/232,323 US6081097A (en) | 1998-01-19 | 1999-01-18 | Method for charging lithium secondary battery |
| EP99101016A EP0948075B1 (en) | 1998-01-19 | 1999-01-19 | Method for managing charge/discharge of secondary battery |
| CNB991012402A CN1193474C (en) | 1998-01-19 | 1999-01-19 | Method for managing charge/discharge of secondary battery |
| DE69912177T DE69912177T2 (en) | 1998-01-19 | 1999-01-19 | Method for regulating the charging / discharging of a secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19254098A JP3558523B2 (en) | 1998-07-08 | 1998-07-08 | Charging method for non-aqueous secondary batteries |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000030750A JP2000030750A (en) | 2000-01-28 |
| JP3558523B2 true JP3558523B2 (en) | 2004-08-25 |
Family
ID=16292984
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP19254098A Expired - Fee Related JP3558523B2 (en) | 1998-01-19 | 1998-07-08 | Charging method for non-aqueous secondary batteries |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3558523B2 (en) |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003132955A (en) | 2001-10-23 | 2003-05-09 | Nec Yonezawa Ltd | Charging and discharging method of nonaqueous electrolyte secondary battery |
| JP4583727B2 (en) * | 2002-05-30 | 2010-11-17 | パナソニック株式会社 | Non-aqueous electrolyte secondary battery charging method |
| US7674556B2 (en) | 2002-05-30 | 2010-03-09 | Panasonic Corporation | Non-aqueous electrolyte secondary battery and method for charging the same |
| US10297827B2 (en) | 2004-01-06 | 2019-05-21 | Sion Power Corporation | Electrochemical cell, components thereof, and methods of making and using same |
| US7358012B2 (en) | 2004-01-06 | 2008-04-15 | Sion Power Corporation | Electrolytes for lithium sulfur cells |
| US8828610B2 (en) | 2004-01-06 | 2014-09-09 | Sion Power Corporation | Electrolytes for lithium sulfur cells |
| US7646171B2 (en) * | 2004-01-06 | 2010-01-12 | Sion Power Corporation | Methods of charging lithium sulfur cells |
| KR20130105839A (en) | 2010-08-24 | 2013-09-26 | 바스프 에스이 | Electrolyte materials for use in electrochemical cells |
| JP5278467B2 (en) * | 2011-02-21 | 2013-09-04 | 株式会社デンソー | Lithium secondary battery charging device and charging method |
| US8735002B2 (en) | 2011-09-07 | 2014-05-27 | Sion Power Corporation | Lithium sulfur electrochemical cell including insoluble nitrogen-containing compound |
| KR101375158B1 (en) | 2011-11-17 | 2014-03-17 | 주식회사 샤인 | Electrode assembly, manufacturing the samem, and method of charging and discharging a battery |
| US9577289B2 (en) | 2012-12-17 | 2017-02-21 | Sion Power Corporation | Lithium-ion electrochemical cell, components thereof, and methods of making and using same |
| CN110611133B (en) * | 2019-09-20 | 2023-01-24 | 河南锂动电源有限公司 | Charging method of lithium ion battery management system |
| CN114362301A (en) * | 2021-12-27 | 2022-04-15 | 厦门芯阳科技股份有限公司 | Lithium battery charging voltage control method and device |
-
1998
- 1998-07-08 JP JP19254098A patent/JP3558523B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2000030750A (en) | 2000-01-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0948075B1 (en) | Method for managing charge/discharge of secondary battery | |
| DK2594006T3 (en) | METHOD AND DEVICE FOR CHARGING A BATTERY | |
| US20190222051A1 (en) | Methods and systems for recharging a battery | |
| JP5289558B2 (en) | Non-aqueous electrolyte secondary battery charging method and charging device | |
| JP3558523B2 (en) | Charging method for non-aqueous secondary batteries | |
| US8125185B2 (en) | Method for charging non-aqueous electrolyte secondary battery | |
| JP5305653B2 (en) | Method for charging a lithium ion storage battery having a negative electrode | |
| US7071653B2 (en) | Method for charging a non-aqueous electrolyte secondary battery and charger therefor | |
| JP2000106219A (en) | Method and device for charging secondary battery | |
| JP2003132955A (en) | Charging and discharging method of nonaqueous electrolyte secondary battery | |
| JPWO2011065009A1 (en) | Lithium ion secondary battery charging method and battery pack | |
| JPH11204148A (en) | Discharge capacity recovery method of nonaqueous electrolyte secondary battery and circuit therefor | |
| JP2012016109A (en) | Method and device of charging lithium ion battery | |
| JP5122899B2 (en) | Discharge control device | |
| JP3558515B2 (en) | Charging method for non-aqueous secondary batteries | |
| JPH07296854A (en) | Method and device for charging | |
| JP2002050407A (en) | Nonaqueous electrolyte secondary cell and control method of charge and discharge | |
| JP3558525B2 (en) | How to use non-aqueous secondary batteries | |
| JP2000195558A (en) | Charging/discharging control device for nonaqueous electrolyte secondary battery | |
| JP4618025B2 (en) | Battery pack and charge control method thereof | |
| JP2002199607A (en) | Charging method of secondary battery | |
| JP2001102093A (en) | Method for protecting secondary cell from being defective, and charger and electonic apparatus for performing the method | |
| JP2008186691A (en) | Usage and system of nonaqueous electrolyte battery | |
| JPH10321262A (en) | Method for charging non-aqueous secondary battery | |
| JP2003109671A (en) | Method of charging nonaqueous electrolyte secondary battery pack |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20040204 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20040217 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20040415 |
|
| RD02 | Notification of acceptance of power of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: A7422 Effective date: 20040415 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20040513 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20040518 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090528 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100528 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110528 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110528 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120528 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120528 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130528 Year of fee payment: 9 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130528 Year of fee payment: 9 |
|
| LAPS | Cancellation because of no payment of annual fees |