JP2017034872A - Method for charging nonaqueous secondary battery, and charge control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for charging a nonaqueous secondary battery and a charge control device, which can improve a battery life.SOLUTION: A method for charging a nonaqueous secondary battery, having a net voltage of the nonaqueous secondary battery to be a target voltage, executes: a temperature determination step which determines whether or not the temperature of the nonaqueous secondary battery before charging is a predetermined value or higher; and an intermittent charging step which, when the temperature determination step determines the temperature of the nonaqueous secondary battery to be the predetermined value or higher, alternately repeats a charge-suspension unit which is composed of a charging step, which charges the nonaqueous secondary battery to the target voltage, and a suspension step which temporarily suspends the charging, or an overshoot charging step which charges the nonaqueous secondary battery to an excessive voltage exceeding the target voltage.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a charging method and a charging control device for a non-aqueous secondary battery.

  The charge control device that charges the non-aqueous secondary battery charges the non-aqueous secondary battery by supplying current to the non-aqueous secondary battery.

  The non-aqueous secondary battery includes an electrolytic solution in which an electrolyte is dissolved in an organic solvent. For this reason, when the nonaqueous secondary battery is charged at a high temperature when the temperature is high, there is a concern that a side reaction that causes decomposition of the electrolytic solution may occur in addition to a reversible reaction of a normal battery. In particular, for a secondary battery using a Si-based material as a negative electrode active material, the electrode is affected by hysteresis due to charging / discharging, so that the polarization becomes large. Decomposition of the electrolytic solution may cause deterioration of the surface of the electrolytic solution or the electrode material, displacement of the potentials of the positive electrode and the negative electrode, a decrease in life, and the like, and may reduce the charge / discharge cycle characteristics of the nonaqueous secondary battery.

  Thus, Patent Documents 1 to 8 propose a method of controlling the current according to the temperature when charging the non-aqueous secondary battery.

WO2014 / 104280 JP 2012-10593 A JP 2010-277839 A JP 2013-149609 A WO2012 / 081423 JP-A-8-205418 Japanese Patent Laid-Open No. 2-119539 JP 2012-16109 A

  The inventor of the present application eagerly searched for a new charging method and a charging control device different from the above-mentioned patent document in order to suppress the decomposition of the electrolyte during charging of the non-aqueous secondary battery and improve the battery life.

  This invention is made | formed in view of this situation, and makes it a subject to provide the charge method and charge control apparatus of a non-aqueous secondary battery which can aim at the improvement of battery life.

The charging method of the non-aqueous secondary battery of the present invention is a charging method of charging a non-aqueous secondary battery and setting the net voltage of the non-aqueous secondary battery as a target voltage,
A temperature determining step of determining whether or not the temperature of the non-aqueous secondary battery before charging is equal to or higher than a predetermined value;
When it is determined in the temperature determination step that the temperature of the non-aqueous secondary battery is equal to or higher than a predetermined value,
i) intermittent charge step of alternately repeating a charge-pause unit comprising a charge step of charging the non-aqueous secondary battery to the target voltage and a pause step of temporarily suspending the charge, or ii) the non-aqueous secondary battery And performing an overshoot charging step of charging to an excess voltage exceeding the target voltage.

The charging control device of the present invention includes a control unit that controls a current supplied to the non-aqueous secondary battery when charging the non-aqueous secondary battery and setting the net voltage of the non-aqueous secondary battery as a target voltage. Prepared,
The controller is
A temperature determination unit that determines whether the temperature of the non-aqueous secondary battery before charging is equal to or higher than a predetermined value;
An intermittent charging unit that alternately repeats a charge-pause unit consisting of a charge step of charging the non-aqueous secondary battery to the target voltage and a pause step of temporarily suspending the charge;
An overshoot charging unit for charging the non-aqueous secondary battery to an excess voltage exceeding the target voltage;
A selection unit that selects one of the intermittent charging unit and the overshoot charging unit when the temperature determination unit determines that the temperature of the non-aqueous secondary battery is equal to or higher than a predetermined value. Features.

  According to the said structure, when it is judged that the temperature of a non-aqueous secondary battery is more than predetermined value, the intermittent charge process or the overshoot charge process is performed. In the intermittent charging step, the charging depth of the positive electrode and the negative electrode is increased by performing a pause step after the charging step with a constant current. Thereby, decomposition | disassembly of the electrolyte solution by overvoltage can be suppressed, aiming at the polarization elimination in an electrode active material. In addition, the heat generated by charging during the pause in the pause process can be released to the outside, and the temperature of the battery can be prevented from increasing. In the overshoot charging process, the non-aqueous secondary battery is charged to an excess voltage exceeding the target voltage. When the non-aqueous secondary battery is exposed to an excess voltage higher than the target voltage, the battery reaction proceeds positively, and the net voltage of the non-aqueous secondary battery can be made the target voltage in a short time. It takes less time to expose the non-aqueous secondary battery under high temperature and high voltage, can suppress the decomposition of the electrolytic solution, and can suppress the decrease in the battery capacity due to the deterioration of the electrolytic solution.

  Since this invention has the said structure, the charging method and charge control apparatus of a non-aqueous secondary battery which can aim at the improvement of a battery life can be provided.

It is explanatory drawing of the charge control apparatus of embodiment of this invention. It is a flowchart which shows the charging method of this embodiment. It is a diagram which shows the voltage change accompanying the time passage at the time of charge of the test 1. FIG. It is a diagram which shows the voltage change accompanying the time passage at the time of charge of the test 2. FIG. It is a diagram which shows the voltage change accompanying the time passage at the time of charge of the test 3. FIG. It is a diagram which shows the voltage change accompanying the time passage at the time of charge of tests 1-5.

  A charging control device and a charging method for a non-aqueous secondary battery according to an embodiment of the present invention will be described.

  As shown in FIG. 1, the charging control device 1 of the present embodiment controls the current supplied to the non-aqueous secondary battery 5 when charging the non-aqueous secondary battery 5. The charging control device 1 is used to charge the nonaqueous secondary battery 5 mounted on the vehicle 50. The vehicle may be a vehicle that uses electric energy from a battery as a whole or a part of a power source. For example, an electric vehicle, a hybrid vehicle, a plug-in hybrid vehicle, a hybrid railway vehicle, an electric forklift, an electric wheelchair, and an electric assist. Bicycles and electric motorcycles are examples.

  The charge control device 1 is a device that charges the non-aqueous secondary battery 5 and sets the net voltage of the non-aqueous secondary battery 5 to the target voltage Vp. “Net voltage” refers to the voltage of the non-aqueous secondary battery when the influence of the internal resistance of the non-aqueous secondary battery 5 is minimized and the voltage is uniform across the entire electrode active material. The “target voltage Vp” may be the voltage of the non-aqueous secondary battery 5 when the charging rate is 100%, or a non-aqueous system with a charging rate lower than that (for example, 70%, 80%, 90%). The voltage of the secondary battery 5 may be used. The target voltage Vp may be set to a maximum voltage that can be used without causing performance deterioration of the nonaqueous secondary battery 5 or lower. In the present embodiment, the voltage 4.2V of the non-aqueous secondary battery 5 having a charging rate of 100% is set as the target voltage Vp. The minimum voltage of the non-aqueous secondary battery 5 was set to 3.0V.

  Each non-aqueous secondary battery 5 is a lithium ion secondary battery, and includes a negative electrode, a positive electrode, a separator, and a non-aqueous electrolyte solution. The negative electrode includes a current collector and an active material layer that covers the current collector surface and has a negative electrode active material. The positive electrode includes a current collector and an active material layer that covers the current collector surface and has a positive electrode active material.

  Examples of the positive electrode active material include lithium nickel cobalt manganese composite oxide, lithium manganese composite oxide having a spinel structure, lithium iron phosphate compound, and sulfur. Examples of the negative electrode active material include Si-based materials such as SiO, crystalline silicon and silicon materials, and carbon materials such as graphite.

As an embodiment of the silicon material, a layered silicon compound mainly composed of polysilane obtained by reacting CaSi ₂ and an acid to remove Ca is synthesized, and the layered silicon compound is heated at 300 ° C. or higher to release hydrogen. Mention may be made of the silicon material produced by the method. The silicon material has a structure in which a plurality of plate-like silicon bodies are laminated in the thickness direction. This structure can be confirmed by observation with a scanning electron microscope or the like. In consideration of using the silicon material as an active material of a lithium ion secondary battery, the plate-like silicon body has a thickness in the range of 10 nm to 100 nm for efficient insertion and desorption reaction of lithium ions. Those within the range are preferable, and those within the range of 20 nm to 50 nm are more preferable. The length of the plate-like silicon body in the major axis direction is preferably in the range of 0.1 μm to 50 μm. The plate-like silicon body preferably has a (length in the major axis direction) / (thickness) range of 2 to 1000.

  The silicon material preferably includes amorphous silicon and / or silicon crystallites. The size of the silicon crystallite is preferably in the range of 0.5 nm to 300 nm, more preferably in the range of 1 nm to 100 nm, still more preferably in the range of 1 nm to 50 nm, and particularly preferably in the range of 1 nm to 10 nm. The size of the silicon crystallite is calculated from the Scherrer equation using X-ray diffraction measurement (XRD measurement) on the silicon material and using the half-value width of the diffraction peak on the Si (111) surface of the obtained XRD chart. Is done.

  As a preferable particle size distribution of the silicon material when measured with a general laser diffraction particle size distribution measuring apparatus, it can be exemplified that the average particle diameter (D50) is in the range of 1 to 30 μm, and more preferably the average particle It can be exemplified that the diameter (D50) is in the range of 1 to 10 μm.

  The nonaqueous electrolytic solution contains a nonaqueous solvent and an electrolyte dissolved in the nonaqueous solvent.

  Examples of the non-aqueous solvent include cyclic esters, chain esters, and ethers. Examples of cyclic esters include ethylene carbonate, propylene carbonate, butylene carbonate, gamma butyrolactone, vinylene carbonate, 2-methyl-gamma butyrolactone, acetyl-gamma butyrolactone, and gamma valerolactone. Examples of the chain esters include dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dipropyl carbonate, methyl ethyl carbonate, propionic acid alkyl ester, malonic acid dialkyl ester, and acetic acid alkyl ester. Examples of ethers include tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-diethoxyethane, and 1,2-dibutoxyethane. As the non-aqueous solvent, a compound in which part or all of hydrogen in the chemical structure of the specific non-aqueous solvent is substituted with fluorine may be employed. Examples of the compound in which part or all of hydrogen in the chemical structure of the non-aqueous solvent is fluorine-substituted include, for example, fluoroethylene carbonate and difluoroethylene carbonate.

Moreover, as an electrolyte dissolved in the non-aqueous electrolyte, for example, a lithium salt such as LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ can be used.

As the non-aqueous electrolyte, for example, a lithium salt such as LiClO ₄ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO _{3 in} a solvent such as ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate is used in an amount of 0.5 mol / l to 1. A solution dissolved at a concentration of about 7 mol / l can be used.

  A separator is used as needed. The separator separates the positive electrode and the negative electrode and holds a non-aqueous electrolyte. The separator is a porous film made of polyolefin resin such as polyethylene (PE) or polypropylene (PP), polypropylene, polyethylene terephthalate (PET), methylcellulose. Examples thereof include a woven fabric or a non-woven fabric.

  As shown in FIG. 1, the charging control device 1 is provided between the supply power source 6 and the non-aqueous secondary battery 5, and controls the current supplied from the supply power source 6 to the non-aqueous secondary battery 5. . The supply power source 6 outputs electric power for charging the non-aqueous secondary battery 5, and may be, for example, an AC power source, or may be an AC power source converted into a DC power source for output. Good.

  The charging control device 1 includes a control unit 2 and an operation unit 3.

  The control unit 2 is mainly composed of a computer, and includes a temperature determination unit 21, a time determination unit 22, a current detection unit 23, a constant current constant voltage charging unit 24, an intermittent charging unit 25, and an overshoot charging unit. 26 and a selection unit 27.

  The vehicle 50 is provided with a temperature sensor 51 that measures the temperature Tx of the nonaqueous secondary battery 5. The temperature sensor 51 is, for example, a thermistor. The temperature determination unit 21 determines whether or not the temperature Tx of the nonaqueous secondary battery 5 is equal to or higher than a predetermined value To based on a battery temperature signal emitted from the temperature sensor 51 of the vehicle 50. The predetermined value To is, for example, a lower limit value of the temperature at which the electrolyte solution of the nonaqueous secondary battery 5 may be decomposed. The predetermined value To may be a specific temperature in the range of 35 to 55 ° C, and more preferably 40 to 50 ° C. In the present embodiment, the predetermined value To is 45 ° C.

  The time determination unit 22 determines whether or not the allowable charge time Ha that can be spent for charging the non-aqueous secondary battery 5 is equal to or longer than the reference charge time Ho. The reference charging time Ho is a time required to increase the net voltage of the nonaqueous secondary battery 5 to the target voltage Vp as will be described later.

  The allowable charging time Ha is arbitrarily set by an operator who operates the charging control device 1. For example, the time determination unit 22 is connected to a quick charge switch 32 provided in the operation unit 3. When the operator operates the quick charge switch 32, the time determination unit 22 determines that the charge allowable time Ha is less than the reference charge time Ho. When the quick charge switch 32 is not operated, the time determination unit 22 determines that the allowable charging time Ha is equal to or longer than the reference charging time Ho.

  The current detection unit 23 detects a current signal transmitted from a current measuring device 52 mounted on the vehicle 50. The current signal includes information on the voltage and current value of the nonaqueous secondary battery 5 measured by the current measuring device 52. The constant current / constant voltage charging unit 24, the intermittent charging unit 25, and the overshoot charging unit 26 of the control unit 2 calculate the current supplied to the non-aqueous secondary battery 5 based on the current signal transmitted from the current detection unit 23. Control.

  The constant current constant voltage charging unit 24 performs a constant current constant voltage charging step. In the constant current constant voltage charging step, the non-aqueous secondary battery 5 is charged with a constant current up to the target voltage Vp, and further charged so as to maintain the target voltage Vp after the non-aqueous secondary battery 5 reaches the target voltage Vp. .

  In the constant current constant voltage charging step, the nonaqueous secondary battery 5 is exposed to the target voltage Vp for a predetermined time after reaching the target voltage Vp. Immediately after the non-aqueous secondary battery 5 reaches the target voltage Vp, the charging depth is shallow for both the positive electrode and the negative electrode. That is, immediately after the non-aqueous secondary battery 5 reaches the target voltage Vp, the positive electrode active material releases Li ions exclusively from the surface, and the amount of internal Li ions released is small. Li ions are unevenly distributed on the surface of the negative electrode active material, and Li ions are not diffused into the negative electrode active material. The target voltage Vp is reached only between the surfaces of the positive electrode active material and the negative electrode active material, but the target voltage Vp is not reached between the positive electrode active material and the negative electrode active material. When a relatively large current flows through the non-aqueous secondary battery 5, the target voltage Vp immediately after reaching the target voltage Vp is greatly affected by the internal resistance of the battery.

  Therefore, in the present embodiment, after reaching the target voltage Vp, the current is gradually decreased so that the nonaqueous secondary battery 5 maintains the target voltage Vp, and charging is continued until the net voltage reaches the target voltage. To do. Thereby, not only between the surfaces of the electrode active materials of the positive electrode and the negative electrode but also the voltage between the electrode active materials of the positive electrode and the negative electrode can reach the target voltage Vp, and the influence of the internal resistance of the battery can be reduced. In the lost state, the net voltage of the battery, that is, the net voltage can reach the target voltage Vp.

  In the constant current constant voltage charging step, the positive electrode maintains a high potential while maintaining the target voltage Vp. For this reason, the electrolyte solution in the vicinity of the positive electrode is exposed to an oxidized state. However, since the temperature Tx of the nonaqueous secondary battery 5 is lower than the predetermined value To, the electrolytic solution is hardly decomposed. For this reason, when the temperature Tx of the non-aqueous secondary battery 5 is less than the predetermined value To, the electrolytic solution is not decomposed even if constant current constant voltage charging is performed with a relatively high current at a constant current and a constant voltage. It is difficult to occur and can exhibit excellent cycle characteristics. When the temperature Tx of the nonaqueous secondary battery 5 is less than the predetermined value To, constant current charging or constant voltage charging is performed instead of the constant current constant voltage charging performed in the constant current constant voltage charging step. It is also possible. Among constant current / constant voltage charge, constant current charge and constant voltage charge, constant current / constant voltage charge can be charged in a short time when charged with the same current value.

  In the constant current / constant voltage charging step, the target voltage Vp is maintained by charging the current value gradually after reaching the target voltage Vp, but the end current value is 0.3 C rate or less, and further 0.2 C rate or less. The target voltage Vp is preferably maintained until the rate becomes 0.15 C or less and 0.1 C or less. The 1C rate means a current value required to fully charge or discharge a battery in one hour at a constant current.

  The intermittent charging unit 25 performs an intermittent charging process. In the intermittent charging step, a charging-pause unit consisting of a charging step for charging the nonaqueous secondary battery 5 to the target voltage Vp and a pause step for temporarily suspending charging are alternately repeated. In general, when the target voltage Vp is continuously applied to the nonaqueous secondary battery 5 for a long time, the positive electrode maintains an oxidized state, and the decomposition of the electrolyte proceeds particularly in the vicinity of the positive electrode. Therefore, in the intermittent charging process, by performing a pause process after the charging process with a constant current, it is possible to suppress the decomposition of the electrolyte due to overvoltage while promoting the diffusion of Li into the positive electrode active material. Moreover, the heat | fever generate | occur | produced at the charge process can be discharge | released outside during a pause process, and the decomposition reaction of electrolyte solution can be suppressed.

  In the intermittent charging step, the charging current value in the charging-pause unit charging step may be smaller than the charging current value in the immediately preceding charging-pause unit charging step. Thereby, the charging depth can be increased as the later charging-pause unit, and the entire battery can be uniformly set to the target voltage Vp. In addition, voltage errors due to the internal resistance of the battery can be suppressed. Therefore, the net voltage of the battery can be brought close to the target voltage Vp.

  Immediately after the charging step, the positive electrode active material releases Li ions exclusively from the surface, and the amount of internal Li ions released is small. Li ions are unevenly distributed on the surface of the negative electrode active material, and Li ions are not diffused into the negative electrode active material. In particular, the Si-based negative electrode active material has large expansion and contraction due to charge and discharge, Li ions are unevenly distributed on the surface of the negative electrode active material, and the charge / discharge curve has a large hysteresis. Therefore, in the present embodiment, by performing a resting process after the charging process, it is possible to eliminate the hysteresis of the charge / discharge curve, diffuse Li to the entire negative electrode active material, and make the entire battery have a uniform voltage.

  In the pause process of the intermittent charging process, charging is paused by stopping the power supply while the charge control device 1 is connected to the non-aqueous secondary battery 5.

  In the charging-pause unit pause process of the intermittent charging process, it is preferable to pause the charging until the non-aqueous secondary battery 5 becomes less than the target voltage Vp. Thereby, the applied voltage spreads uniformly over the entire electrode active material, and the charging depth can be increased.

  In the intermittent charging process, the charging-pause unit is repeated until the net voltage of the non-aqueous secondary battery reaches the target voltage Vp. Furthermore, it is preferable that the repetition of the charge-pause unit is terminated when the voltage of the nonaqueous secondary battery 5 at the end of the pause process maintains a voltage close to the target voltage Vp. For example, in the intermittent charging process, the voltage of the non-aqueous secondary battery 5 at the end of the pause process, that is, the voltage detected by the current detector 23 is 90% or more of the target voltage Vp, further 95% or more, 97% or more, The charge-pause unit repetition may be terminated when 99% or more is maintained.

  In the present embodiment, the current value supplied to the nonaqueous secondary battery 5 in the first charging-pause unit charging process is set to a 1C rate. The current value in the charging step of each cycle of charging-pause unit was set to 1/3 of the current value in the charging step of the immediately preceding charging-pause step. The pause process in the charge-pause unit of each cycle was 1 hour.

  The overshoot charging unit 26 performs an overshoot charging process. In the overshoot charging step, the non-aqueous secondary battery 5 is charged to an excess voltage Vq that exceeds the target voltage Vp. The excess voltage Vq is higher than the target voltage Vp that is exposed to the non-aqueous secondary battery 5 in the intermittent charging step and the constant current constant voltage charging step. When charged to the excess voltage Vq, the charge rate of the non-aqueous secondary battery 5 may be a desired charge rate. When the non-aqueous secondary battery 5 is exposed to an excess voltage Vq higher than the target voltage Vp, immediately after reaching the excess voltage Vq, there is a difference between the voltage between the surface of the positive electrode active material and the negative electrode active material and the voltage between the inside. However, after a while after reaching the excess voltage Vq, Li ions move in the positive electrode active material and the negative electrode active material, and the entire positive electrode active material and negative electrode active material become the target voltage Vp. According to the overshoot charging process, the battery reaction proceeds positively, and the net voltage of the non-aqueous secondary battery can be set to the target voltage Vp in a short time. It takes less time to expose the non-aqueous secondary battery 5 under high temperature and high voltage, so that decomposition of the electrolytic solution can be suppressed, and a decrease in battery capacity due to deterioration of the electrolytic solution can be suppressed.

  In the overshoot charging step, the excess voltage Vq is preferably more than 100% and not more than 130% with respect to the target voltage Vp. In this case, charging can be performed in a short time while suppressing decomposition of the electrolytic solution. When the excess voltage Vq is excessively higher than the target voltage Vp, there is a possibility that the electrolytic solution is excessively decomposed or the positive electrode active material is damaged. The control unit 2 stops charging when the nonaqueous secondary battery 5 reaches the excess voltage Vq during charging.

  It is preferable that the current values during charging in the first charging-pause unit in the overshoot charging process, the intermittent charging process, and the constant current constant voltage charging process are constant and the same. Regardless of which process is selected, the battery can be charged with a current value suitable for the non-aqueous secondary battery 5.

  The current value at the time of charging in the overcharge charging step, the initial charging-pause unit in the intermittent charging step, and the constant current constant voltage charging step is preferably 0.2C rate or more and 3C rate or less, and further 0.5C rate The rate is preferably 2C or less and more preferably 0.7C or more and 1.5C or less. In this case, it is possible to charge to the excess voltage Vq in a short time while suppressing decomposition of the electrolytic solution. If the current value is too small, the time required for charging may be too long. When the current value is excessive, the electrolytic solution may be decomposed by a side reaction during charging.

  The time required for the overshoot charging process is shorter than the time required for the intermittent charging process. Further, the time required for the overshoot charging process is preferably shorter than the time required for the constant current constant voltage charging process.

  The selection unit 27 selects the constant current / constant voltage charging unit 24 when the temperature determination unit 21 determines that the temperature Tx of the nonaqueous secondary battery 5 is lower than the predetermined value To, and the nonaqueous secondary battery is selected. When it is determined that the temperature Tx of 5 is equal to or higher than the predetermined value To, the intermittent charging unit 25 or the overshoot charging unit 26 is selected. The selection unit 27 further selects the intermittent charging unit 25 when the time determination unit 22 determines that the allowable charging time Ha is equal to or longer than the reference charging time Ho, and the allowable charging time Ha is determined to be less than the reference charging time Ho. Overshoot charging unit 26 is selected.

  Each of the constant current and constant voltage charging unit 24, the intermittent charging unit 25, and the overshoot charging unit 26 includes a known power conversion circuit. When any one of the constant current constant voltage charging unit 24, the intermittent charging unit 25, and the overshoot charging unit 26 is selected by the selection unit 27, the current is adapted to the selected process by the power conversion circuit of each charging unit. Be controlled. The controlled current is supplied to the nonaqueous secondary battery 5 in the vehicle 50 through the power extraction unit 59.

  The operation unit 3 includes a start button 31 and a quick charge button 32. When the start button 31 is operated, charging of the charging control device 1 is started. When the start button 31 is operated and the quick charge button 32 is further operated, the overshoot charging process is selected when the temperature Tx of the non-aqueous secondary battery is equal to or higher than the predetermined value To.

  A charging method for charging the non-aqueous secondary battery 5 using the charging control device 1 will be described.

  When the charging control device 1 is connected to the electricity intake 51 of the vehicle 50 and the start button 31 is operated, charging by the charging control device 1 is started. Charging by the charging control device 1 is performed according to the flowchart shown in FIG.

  As shown in FIG. 2, in step S1, the control unit 2 confirms that the non-aqueous secondary battery 5 is stopped.

  In step S2, the temperature determination unit 21 determines whether or not the temperature Tx of the non-aqueous secondary battery 5 before charging is equal to or higher than a predetermined value To (temperature determination step). If the temperature Tx of the non-aqueous secondary battery 5 before charging is equal to or higher than a predetermined value To (45 ° C.) in step S2, the process proceeds to step S4. When the temperature Tx of the non-aqueous secondary battery 5 before charging is lower than a predetermined value To (45 ° C.), the selection unit 27 selects the constant current / constant voltage charging unit 24 in step S3.

  In step S3, the constant current constant voltage charging unit 24 performs a constant current constant voltage charging step. In the constant current constant voltage charging step, the non-aqueous secondary battery 5 is charged at a constant current of 1 C rate up to the target voltage Vp (4.2 V), and the target voltage Vp is reached after the non-aqueous secondary battery 5 reaches the target voltage Vp. The battery is further charged while gradually decreasing the current value so as to maintain the current.

  In step S4, the time determination unit 22 determines whether or not the allowable charging time Ha is equal to or longer than the reference charging time Ho. The reference charging time Ho is a time until the net voltage of the nonaqueous secondary battery is set to the target voltage Vp in the intermittent charging process. In order to determine the reference charging time Ho, the charging-pause unit that is paused for 1 hour after being charged to the target voltage Vp (4.2 V) at a constant current of 1 C rate is repeated, and the initial charging current value is set to 1 C rate. Is calculated as the time required to repeat the charging rate from 0% to 100% as 1/3 of the current value of the last charging-pause unit charging, and the calculated value is used as the reference charging time. Let it be Ho. In the present embodiment, the reference charging time Ho calculated under the above conditions of the intermittent charging process is 3 hours.

  In step S4, when the quick charge button 32 is not operated, the time determination unit 22 determines that the charge allowable time Ha is equal to or longer than the reference charge time Ho. In this case, the selection unit 27 selects the intermittent charging process in step S5. On the other hand, when the quick charge button 32 is operated, the time determination unit 22 determines that the allowable charging time Ha is less than the reference charging time Ho. In this case, the selection unit 27 selects the overshoot charging unit 26 in step S6.

  In step S5, the intermittent charging unit 25 performs an intermittent charging process. In the intermittent charging step, the control unit 2 alternately repeats a charging-pause unit including a charging step for charging the nonaqueous secondary battery 5 to the target voltage Vp and a pause step for temporarily stopping charging. The current value supplied to the non-aqueous secondary battery 5 in the first charging-pause unit charging step was set to 1C. The current value in the charging step of each cycle of charging-pause unit was set to 1/3 of the current value in the charging step of the immediately preceding charging-pause step. The pause process in the charge-pause unit of each cycle was 1 hour. The charge-pause unit is repeated until the net voltage of the non-aqueous secondary battery 5 reaches the target voltage Vp. Alternatively, in order to set the net voltage of the non-aqueous secondary battery 5 to the target voltage Vp, the charge-pause unit may be repeated until the non-aqueous secondary battery 5 reaches a desired charge rate, and preferably the charge rate is 100. Repeat until%. Or it is good to repeat a charge-pause unit until the voltage of the non-aqueous secondary battery 5 at the end of the pause process, that is, the voltage detected by the current detector 23 maintains 99% or more of the target voltage Vp. In the present embodiment, the charge-pause unit is repeated until the voltage of the nonaqueous secondary battery 5 at the end of the pause process maintains 99% or more of the target voltage Vp, and then the process ends.

  In step S6, the overshoot charging unit 26 performs an overshoot charging process. In the overshoot charging process, the overshoot charging unit 26 supplies a constant current of 1 C rate to the non-aqueous secondary battery 5. When a constant current continues to flow through the non-aqueous secondary battery 5, the non-aqueous secondary battery 5 reaches an excess voltage Vq (4.35V) that exceeds the target voltage Vp (4.2V). The excess voltage Vq of 4.35V is 104% when the target voltage Vp is 100%. When the voltage of the non-aqueous secondary battery 5 becomes the excess voltage Vq, the overshoot charging unit 26 stops supplying a constant current to the non-aqueous secondary battery 5 and ends the overshoot charging process. To do.

  Thus, the charging of the non-aqueous secondary battery is finished.

  In the present embodiment, when it is determined that the temperature Tx of the nonaqueous secondary battery 5 is equal to or higher than the predetermined value To, an intermittent charging process or an overshoot charging process is performed. In the intermittent charging process, the process of temporarily suspending charging after charging with a constant current increases the charging depth to eliminate the polarization in the positive electrode active material and the negative electrode active material, while decomposing the electrolyte due to overvoltage Can be suppressed. Further, in the pause process, the heat generated in the charging process can be released to the outside, and the decomposition of the electrolytic solution can be suppressed. In the overshoot charging process, the non-aqueous secondary battery 5 is charged to an excess voltage Vq that exceeds the target voltage Vp. When the nonaqueous secondary battery 5 is exposed to the excess voltage Vq higher than the target voltage Vp, the battery reaction proceeds positively, and the net voltage can be made the target voltage Vp in a short time. It takes only a short time to expose the non-aqueous secondary battery 5 under high temperature and high voltage, so that decomposition of the electrolytic solution can be suppressed, and a decrease in battery capacity due to deterioration of the electrolytic solution can be suppressed.

  In particular, a lithium ion secondary battery using a Si-based material as a negative electrode active material has hysteresis in the charge / discharge curve, and has a large polarization in the electrode active material. Therefore, when the temperature of the non-aqueous secondary battery is high, by performing the intermittent charging process or the overshoot charging process, it is possible to suppress the decomposition reaction of the electrolytic solution and extend the battery life.

  Further, an intermittent charging process is performed when the allowable charging time Ha is equal to or longer than the reference charging time Ho, and an overshoot charging process is performed when it is less than the reference charging time Ho. For this reason, when sufficient time can be spent in charging at a high temperature, by performing intermittent charging with a pause during charging, decomposition of the electrolyte is suppressed while eliminating polarization in the electrode active material be able to. When it is desired to charge in a short time, the reaction related to Li is actively advanced by charging to an excess voltage Vq exceeding the target voltage Vp in the overshoot charging process to increase the potential difference between the positive and negative electrodes. By reducing the time during which the secondary battery 5 is exposed to high temperature and high voltage, the capacity reduction can be relatively suppressed.

  On the other hand, when the temperature Tx of the nonaqueous secondary battery 5 is less than the predetermined value To, the temperature does not reach the temperature range where the electrolytic solution is decomposed. For this reason, in the constant current constant voltage charging step, after charging at a constant current up to the target voltage Vp, charging is performed until the net voltage reaches the target voltage Vp, thereby suppressing a decrease in battery life.

  Hereinafter, the nonaqueous secondary battery 5 was subjected to a cycle test employing various charging methods of Tests 1 to 5, and the capacity retention rate after the cycle test was measured.

(Non-aqueous secondary battery)
First, the configuration of a lithium ion secondary battery used for charging will be described. The positive electrode of the lithium ion secondary battery includes a positive electrode active material layer and a current collector covered with the positive electrode active material layer. The positive electrode active material layer may include a binder and a conductive additive as necessary.

The positive electrode active material layer has a positive electrode active material, a binder, and a conductive additive. The positive electrode active material is composed of a lithium-containing metal oxide having a layered rock salt structure represented by LiNi _0.5 Co _0.2 Mn _0.3 O ₂ and an olivine-type lithium phosphate composite oxide represented by LiFePO ₄ . The binder is made of polyvinylidene fluoride (PVDF). The conductive auxiliary agent is made of acetylene black (AB). The current collector is made of aluminum foil. When the positive electrode active material layer is 100 parts by mass, the mass ratio of the positive electrode active material, the binder, and the conductive additive is 94: 3: 3. The active material layer is coated on both sides of the aluminum foil so that the weight per side is 27.0 mg / cm ² , dried at 90 degrees 5 minutes, 120 degrees 5 minutes to volatilize n-methylpyrrolidone (NMP). Removed. Then, after pressing to a predetermined density, it was cut into a predetermined shape (40 mm × 80 mm rectangular shape) to form a positive electrode.

The negative electrode includes a negative electrode active material layer and a current collector covered with the negative electrode active material layer. The negative electrode active material layer is composed of 58 parts by mass of silicon material coated with carbon as a negative electrode active material, 24 parts by mass of natural graphite, 11 parts by mass of polyamide-imide resin as a binder, and 7 parts by mass of acetylene black as a conductive additive. Become. The current collector is a copper foil. The active material layer was coated on both sides of the copper foil so that the weight per side was 4.9 mg / cm ² , dried at 80 ° C. for 5 minutes, and NMP was volatilized and removed. Then, after pressing to a predetermined density, it was cut into a predetermined shape (44 mm × 84 mm rectangular shape) to form a negative electrode.

The non-aqueous electrolyte solution is obtained by dissolving a lithium salt in an organic solvent. A mixed solvent of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate (volume ratio 3: 3: 4) was used as the organic solvent, and LiPF ₆ was used as the lithium salt. The concentration of LiPF ₆ in the non-aqueous electrolyte was 1.0 mol / L.
A laminate type lithium ion secondary battery was produced as follows.

  A laminate type lithium ion secondary battery was manufactured using the two positive electrodes and three negative electrodes. Specifically, a rectangular sheet (48 mm × 88 mm, thickness 25 μm) made of a porous polyethylene film as a separator was sandwiched between the positive electrode and the negative electrode to form an electrode plate group. The electrode plate group was covered with a set of two laminated films, and the three sides were sealed, and then an electrolyte solution was injected into the bag-like laminated film.

  The capacity at 0.2 C of the lithium ion secondary battery was 500 mAh.

  About the lithium ion secondary battery, the cycle test was done on each conditions of the following tests 1-5, and the capacity | capacitance maintenance factor after a cycle test was measured.

(Test 1)
The lithium ion secondary battery was subjected to a constant current / constant voltage charging process in which constant voltage charging was performed with a constant current. The charging conditions were 25 ° C. and a constant current of 1 C rate and a constant voltage of 4.2 V. After the lithium ion secondary battery reached the target voltage Vp of 4.2V, the current value was decreased to further charge the battery so as to maintain the target voltage of 4.2V. The end current value was 0.1 C rate. The change of the voltage with the elapsed time of this constant current constant voltage charge is shown in FIG. 3 and FIG.

  Discharge was performed after charging. The discharge conditions were 25 ° C. and 1C rate.

  A cycle test in which the constant current and constant voltage charging step and the discharging step were repeated 200 times was performed.

(Test 2)
In Test 2, a cycle test was performed in the same manner as Test 1 except that an overshoot charging process was performed at 60 ° C. for the lithium ion secondary battery. In the overshoot charging process, charging was performed at 60 ° C. with a constant current of 1 C rate to 4.35 V, which is an excess voltage Vq. FIG. 4 and FIG. 6 show the change in voltage with the elapsed time of this overshoot charging process.

(Test 3)
In Test 3, a cycle test was conducted in the same manner as Test 1 except that the lithium ion secondary battery was intermittently charged at 60 ° C. In the intermittent charging step, the charging-pause unit was repeated 3 times at 60 ° C.

  In the intermittent charging process, the first charging-pause unit was charged to a target voltage of 4.2 V at a constant current of 1 C rate, and then paused for 1 hour.

  Subsequently, the second charging-pause unit was charged to a target voltage of 4.2 V at a constant current of 1/3 C rate, and then paused for 1 hour.

  The third charge-pause unit was charged to a target voltage of 4.2 V at a constant current of 1/9 C rate. Thereby, charge was complete | finished. The change of the voltage with the elapsed time of this intermittent charging process is shown in FIGS.

(Test 4)
In test 4, a cycle test was performed in the same manner as test 1 except that constant current charging to 4.2 V was performed at a constant current of 1/3 C rate during charging. FIG. 6 shows the change in voltage with the constant current charging time.

(Test 5)
Test 5 was a cycle test similar to Test 1 except that the temperature of the nonaqueous secondary battery during charging was 60 ° C. FIG. 6 shows the change in voltage with the elapsed time of constant current and constant voltage charging in Test 5.

(Capacity maintenance rate)
The capacity retention rates of the lithium non-aqueous secondary batteries in Tests 1 to 5 were measured, and the results are shown in Table 1. Table 1 shows the time required for charging in tests 1 to 5. The discharge capacity retention ratio is calculated as a percentage (100 × (discharge capacity after cycle test) / (initial discharge capacity)) obtained by dividing the discharge capacity after the cycle test by the initial discharge capacity.

As shown in Table 1, in tests 1 and 4 in which charging was performed at 25 ° C., the capacity retention rate was high. Tests 2 and 3 charged at 60 ° C. had a slightly lower capacity retention rate than Tests 1 and 4 charged at 25 ° C. In test 5, the capacity retention rate was significantly lower than in tests 2 and 3. Test 5 is different from Test 1 in temperature, but both perform constant current and constant voltage charging under the same conditions. However, Test 5 that was charged at 60 ° C. had a significantly lower capacity retention rate than Test 1 that was charged at 25 ° C. Tests 1 and 4 did not differ greatly in capacity retention rate, but test 1 was shorter than test 4 in terms of charging time. For Tests 2 and 3, the capacity retention rate was not significantly different, but the charge time was shorter in Test 2 than in Test 3.

  The shape of the lithium ion secondary battery is not particularly limited, and various shapes such as a cylindrical shape, a square shape, a coin shape, and a laminate shape can be employed.

  As mentioned above, although embodiment of the lithium ion secondary battery and its manufacturing method of this invention was described, this invention is not limited to the said embodiment. The present invention can be implemented in various forms without departing from the gist of the present invention, with modifications and improvements that can be made by those skilled in the art.

(1) The charging method of the non-aqueous secondary battery of the present embodiment is a charging method of charging the non-aqueous secondary battery and setting the net voltage of the non-aqueous secondary battery to the target voltage Vp,
A temperature determination step of determining whether or not the temperature of the non-aqueous secondary battery before charging is equal to or higher than a predetermined value To;
When it is determined in the temperature determination step that the temperature of the non-aqueous secondary battery is equal to or higher than the predetermined value To,
i) intermittent charging step of alternately repeating a charging-pause unit comprising a charging step of charging a non-aqueous secondary battery to a target voltage Vp and a pause step of temporarily suspending charging; or ii) targeting a non-aqueous secondary battery An overshoot charging step of charging to an excess voltage Vq exceeding the voltage Vp is performed.

  According to the above configuration, when it is determined that the temperature Tx of the non-aqueous secondary battery is equal to or higher than the predetermined value To, an intermittent charging process or an overshoot charging process is performed. In the intermittent charging process, by disposing a pause process after the charging process with a constant current, it is possible to suppress the decomposition of the electrolyte due to overvoltage while achieving polarization elimination in the electrode active material. In addition, the heat generated by charging during the pause in the pause process can be released to the outside, and the temperature of the battery can be prevented from increasing. In the overshoot charging process, the non-aqueous secondary battery is charged to an excess voltage Vq that exceeds the target voltage Vp. When the non-aqueous secondary battery is exposed to an excess voltage Vq higher than the target voltage Vp, the battery reaction proceeds positively, and the net voltage of the non-aqueous secondary battery can be made the target voltage in a short time. It takes less time to expose the non-aqueous secondary battery under high temperature and high voltage, can suppress the decomposition of the electrolytic solution, and can suppress the decrease in the battery capacity due to the deterioration of the electrolytic solution.

  (2) When it is determined in the temperature determination step that the temperature of the non-aqueous secondary battery is less than the predetermined value To, the non-aqueous secondary battery is charged with a constant current to the target voltage Vp. It is preferable to further include a constant current constant voltage charging step for further charging so as to maintain the target voltage Vp after reaching the target voltage Vp.

  According to the above configuration, when the temperature of the non-aqueous secondary battery is less than the predetermined value To, the temperature does not reach the temperature range where the electrolytic solution is decomposed. For this reason, in the constant current constant voltage charging step, charging is performed at a constant current up to the target voltage Vp, and then held at the constant voltage, and the net voltage of the nonaqueous secondary battery is set to the target voltage Vp. It is possible to suppress a decrease in life.

  (3) The intermittent charging process is selected when the allowable charging time Ha that can be spent for charging the non-aqueous secondary battery is equal to or longer than the reference charging time Ho, and overshoot charging when the allowable charging time Ha is less than the reference charging time Ho. It is preferable to further include a selection step for selecting a step.

  According to the above configuration, when sufficient time can be spent in charging at a high temperature, the electrolytic solution is decomposed while eliminating polarization in the electrode active material by performing intermittent charging with a pause during charging. Can be suppressed. When it is desired to charge in a short time, the reaction related to Li is actively advanced by charging to an excess voltage Vq exceeding the target voltage Vp in the overshoot charging process to increase the potential difference between the positive and negative electrodes. By reducing the time during which the secondary battery is exposed to a high temperature and high voltage, a decrease in capacity can be relatively suppressed.

  (4) It is preferable to further include a time determination step for determining whether or not the allowable charging time Ha is equal to or longer than the reference charging time Ho.

  According to the above configuration, it is possible to select whether or not the charging time can be selected according to the allowable charging time Ha.

  (5) In the intermittent charging step, the charging current value in the charging step in the charging-pause unit is preferably smaller than the charging current value in the charging step in the immediately preceding charging-pause unit. .

  According to the said structure, the voltage inside an electrode active material can be raised, a charging depth can be raised, and the whole battery can be made into the target voltage Vp uniformly. In addition, voltage errors due to the internal resistance of the battery can be suppressed. Thereby, the net voltage of the non-aqueous secondary battery can be brought close to the target voltage Vp.

  (6) It is preferable that the current values during charging in the first charging-pause unit in the intermittent charging process, the overshoot charging process, and the constant current constant voltage charging process are constant and the same.

  If the current value at the time of charging differs in each process, it is necessary to change the battery design for each current value. As in the above configuration, the first charge-pause unit in the intermittent charging process, the overshoot charging process, and the constant current constant voltage charging process in which the current values at the time of charging are constant and equal to each other. Even when it is performed, a current suitable for the battery can be supplied.

  (7) Charging in intermittent charging step-In the pause step of pause unit, it is preferable to pause charging until the non-aqueous secondary battery becomes less than the target voltage Vp.

  According to the said structure, the applied voltage spreads uniformly to the whole electrode active material, and can make the charging depth deep.

  (8) In the intermittent charging process, it is preferable to end the repetition of the charge-pause unit when the voltage of the nonaqueous secondary battery at the end of the pause process maintains 90% or more of the target voltage Vp.

  According to the said structure, the applied voltage spreads uniformly to the whole electrode active material, and can make the charging depth deep.

  (9) In the overshoot charging step, the excess voltage Vq is preferably more than 100% and not more than 130% with respect to the target voltage Vp.

  According to the said structure, it can charge in a short time, suppressing decomposition | disassembly of electrolyte solution.

(10) The charge control device 1 of the present invention controls the current supplied to the non-aqueous secondary battery when charging the non-aqueous secondary battery 5 and setting the net voltage of the non-aqueous secondary battery 5 as the target voltage. A control unit 2 for
The control unit 2
A temperature determination unit 21 that determines whether or not the temperature Tx of the non-aqueous secondary battery 5 before charging is equal to or higher than a predetermined value To;
An intermittent charging unit 25 that alternately repeats a charging-pause unit consisting of a charging step of charging the non-aqueous secondary battery 5 to the target voltage Vp and a pause step of temporarily suspending charging;
An overshoot charging unit 26 for charging the non-aqueous secondary battery 5 to an excess voltage Vq exceeding the target voltage Vp;
A selection unit 27 that selects one of the intermittent charging unit 25 and the overshoot charging unit 26 when the temperature determination unit 21 determines that the temperature Tx of the nonaqueous secondary battery 5 is equal to or higher than a predetermined value To; It is characterized by providing.

  According to the above configuration, when it is determined that the temperature Tx of the nonaqueous secondary battery 5 is equal to or higher than the predetermined value To, an intermittent charging process or an overshoot charging process is performed. In the intermittent charging process, a suspension process is inserted after the charging process at a constant current, thereby promoting the diffusion of Li ions into the electrode active material and depolarizing the battery. Can be suppressed. In addition, the heat generated by charging during the pause in the pause process can be released to the outside, and the temperature of the battery can be prevented from increasing. In the overshoot charging process, the non-aqueous secondary battery is charged to an excess voltage Vq that exceeds the target voltage Vp. When the non-aqueous secondary battery is exposed to an excess voltage Vq higher than the target voltage Vp, the battery reaction proceeds positively, and the net voltage of the non-aqueous secondary battery can be made the target voltage in a short time. It takes less time to expose the non-aqueous secondary battery under high temperature and high voltage, can suppress the decomposition of the electrolytic solution, and can suppress the decrease in the battery capacity due to the deterioration of the electrolytic solution.

(11) The control unit 2 charges the non-aqueous secondary battery with a constant current up to the target voltage Vp, and further charges the non-aqueous secondary battery to maintain the target voltage Vp after reaching the target voltage Vp. A constant voltage charging unit 24;
The selection unit 27 preferably selects the constant current / constant voltage charging step when the temperature determination unit 21 determines that the temperature Tx of the non-aqueous secondary battery is lower than the predetermined value To.

  According to the above configuration, when the temperature Tx of the non-aqueous secondary battery is lower than the predetermined value To, the non-aqueous secondary battery does not reach the temperature range where the electrolytic solution is decomposed. For this reason, in a constant current constant voltage charging process, it is possible to suppress a decrease in service life in a short time by charging at a constant current up to the target voltage Vp and holding at a constant voltage.

(12) The control unit 2 further includes a time determination unit 22 that determines whether the allowable charging time Ha is equal to or longer than a reference charging time Ho that can be spent for charging the non-aqueous secondary battery,
The selection unit 27 selects the intermittent charging unit 25 when the allowable charging time Ha is equal to or longer than the reference charging time Ho in the time determination unit, and selects the overshoot charging unit 26 when the allowable charging time Ha is less than the reference charging time Ho. It is preferable.

  According to the above configuration, when sufficient time can be spent in charging at high temperature, intermittent charging with a pause during charging is performed, so that decomposition of the electrolyte is suppressed while eliminating polarization in the electrode. can do. When it is desired to charge in a short time, the reaction related to Li is actively advanced by charging to an excess voltage Vq exceeding the target voltage Vp in the overshoot charging process to increase the potential difference between the positive and negative electrodes. By reducing the time during which the secondary battery is exposed to a high temperature and high voltage, a decrease in capacity can be relatively suppressed.

1: charge control device, 2: control unit, 21: temperature determination unit, 22: time determination unit, 23: current detection unit, 24: constant current constant voltage charging unit, 25: intermittent charging unit, 26: overshoot charging unit 27: Selection unit, 3: Operation unit, 31: Start button, 32: Quick charge button, 5: Non-aqueous secondary battery, 50: Electric vehicle, 51: Temperature sensor, 52: Current measuring device, 6: Power supply

Claims (12)

A charging method for charging a non-aqueous secondary battery and setting the net voltage of the non-aqueous secondary battery as a target voltage,
A temperature determining step of determining whether or not the temperature of the non-aqueous secondary battery before charging is equal to or higher than a predetermined value;
When it is determined in the temperature determination step that the temperature of the non-aqueous secondary battery is equal to or higher than a predetermined value,
i) intermittent charge step of alternately repeating a charge-pause unit comprising a charge step of charging the non-aqueous secondary battery to the target voltage and a pause step of temporarily suspending the charge, or ii) the non-aqueous secondary battery A non-aqueous secondary battery charging method comprising: performing an overshoot charging step of charging a battery to an excess voltage exceeding the target voltage.   When it is determined in the temperature determining step that the temperature of the non-aqueous secondary battery is lower than a predetermined value, the non-aqueous secondary battery is charged with a constant current to a target voltage, and the non-aqueous secondary battery is The method for charging a non-aqueous secondary battery according to claim 1, further comprising a constant-current constant-voltage charging step of further charging so as to maintain the target voltage after reaching the target voltage.   When the allowable charging time that can be spent for charging the non-aqueous secondary battery is equal to or longer than a reference charging time, the intermittent charging step is selected, and when the allowable charging time is less than the reference charging time, the overshoot charging step is performed. The method for charging a non-aqueous secondary battery according to claim 1, further comprising a selection step of selecting.   The method for charging a non-aqueous secondary battery according to claim 3, further comprising a time determination step of determining whether the allowable charging time is equal to or longer than the reference charging time.   In the intermittent charging step, the charging current value in the charging step in the charging-pause unit is made smaller than the charging current value in the charging step in the immediately preceding charging-pause unit. The charging method of the non-aqueous secondary battery in any one.   6. The current values at the time of charging in the first charging-pause unit in the intermittent charging process, the overshoot charging process, and the constant current constant voltage charging process are constant and the same as each other. A method for charging a non-aqueous secondary battery.   The non-aqueous secondary according to any one of claims 1 to 6, wherein in the pause step of the charge-pause unit of the intermittent charge step, the charge is paused until the non-aqueous secondary battery becomes less than the target voltage. How to charge the battery.   8. The repetition of the charge-pause unit is terminated when the voltage of the nonaqueous secondary battery at the end of the pause process maintains 90% or more of the target voltage in the intermittent charge process. A method for charging a non-aqueous secondary battery according to claim 1.   The method for charging a non-aqueous secondary battery according to claim 1, wherein, in the overshoot charging step, the excess voltage is greater than 100% and largely equal to or less than 130% with respect to the target voltage. In order to charge the non-aqueous secondary battery and set the net voltage of the non-aqueous secondary battery as a target voltage, a control unit is provided for controlling the current supplied to the non-aqueous secondary battery,
The controller is
A temperature determination unit that determines whether the temperature of the non-aqueous secondary battery before charging is equal to or higher than a predetermined value;
An intermittent charging unit that alternately repeats a charge-pause unit consisting of a charge step of charging the non-aqueous secondary battery to the target voltage and a pause step of temporarily suspending the charge;
An overshoot charging unit for charging the non-aqueous secondary battery to an excess voltage exceeding the target voltage;
A selection unit that selects one of the intermittent charging unit and the overshoot charging unit when the temperature determination unit determines that the temperature of the non-aqueous secondary battery is equal to or higher than a predetermined value. A charge control device. The control unit charges the non-aqueous secondary battery with a constant current up to a target voltage, and further charges the non-aqueous secondary battery so as to maintain the target voltage after the non-aqueous secondary battery reaches the target voltage. It further has a charging part,
The charging control device according to claim 10, wherein the selection unit selects the constant current constant voltage charging step when the temperature determination unit determines that the temperature of the non-aqueous secondary battery is lower than a predetermined value. . The control unit further includes a time determination unit that determines whether the allowable charging time is equal to or longer than a reference charging time that can be spent for charging the non-aqueous secondary battery,
The selection unit selects the intermittent charging unit when the allowable charging time is equal to or longer than the reference charging time in the time determination unit, and selects the overshoot charging unit when the allowable charging time is less than the reference charging time. The charge control device according to claim 10 or 11.

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