CONTROL METHOD OF LITHIUM SECONDARY BATTERY AND BATTERY CONTROL DEVICE

To provide a control method of a lithium secondary battery timely detecting a state of a battery cell in a charging cycle, and a battery control device.SOLUTION: A control method of a lithium secondary battery includes steps S10-S18 of charging a lithium secondary battery cell in a single charging cycle, and a step S20 of detecting a state of the lithium secondary battery cell. A charging step includes steps S10-S12YES of charging the lithium secondary battery cell up to predetermined voltage Va at constant current (CC), and steps S16-S18YES of charging the lithium secondary battery cell at constant voltage (CV) until it becomes equal to or less than a predetermined cutoff current value while keeping the voltage Va after it reaches the voltage Va and gradually reducing charging current. A cell state detection step includes a step of estimating a time required for CV charging according to a predetermined equation, and a step of detecting a state of the lithium secondary battery cell based on a difference between an estimation value obtained by estimation and an actual value of the time required for the CV charging.SELECTED DRAWING: Figure 5 【課題】充電サイクルにおいて電池セルの状態を適時に検出するリチウム二次電池の制御方法及び電池制御装置を提供する。【解決手段】リチウム二次電池の制御方法は、１回の充電サイクルにおいて、リチウム二次電池セルを充電するステップＳ１０～Ｓ１８と、リチウム二次電池セルの状態を検出するステップＳ２０と、を含む。充電するステップは、リチウム二次電池セルを所定の電圧Ｖａまで定電流（ＣＣ）充電するステップＳ１０～Ｓ１２ＹＥＳと、電圧Ｖａに達した後に、電圧Ｖａを維持しつつ充電電流を漸次減少させながら所定のカットオフ電流値以下になるまで定電圧（ＣＶ）充電を行うステップＳ１６～Ｓ１８ＹＥＳと、を含む。セル状態検出ステップは、ＣＶ充電に要する時間を所定の式に従って推定する工程と、推定により得られた推定値と、ＣＶ充電に要した時間の実測値との差分に基づいて、リチウム二次電池セルの状態を検出する工程と、を含む。【選択図】図５