A charging method, a charge-discharge method, and a charging system for a lithium-ion battery

Abstract

The application provides a charging method, a charging and discharging method and a charging system of a lithium ion battery. By regulating and controlling the cyclic charging capacity, the long cycle capacity of the battery is prolonged without attenuation or the attenuation is delayed, the cycle capacity retention rate of the lithium ion battery is obviously improved, the technical problem of the low cycle capacity retention rate of the lithium ion battery in the prior art is solved, and in addition, the discharging capacity of the lithium ion battery can be regulated and controlled by regulating and controlling the charging parameters (such as the charging voltage during constant current charging and the charging current during constant voltage charging) in the charging system.

Description

Technical Field

[0001] This application relates to the field of charging technology, specifically to a charging method, a charging and discharging method, and a charging system for a lithium-ion battery. Background Technology

[0002] With the development of battery technology, lithium-ion batteries have gained widespread use due to their large capacity, long battery life, light weight, low price, and high safety, and are currently commonly used in mobile terminals such as mobile phones and tablets. As the application scope of lithium-ion batteries continues to expand, the requirements for their application conditions are becoming increasingly stringent.

[0003] Improving capacity retention in the later stages of the cycle has become an urgent problem to be solved.

[0004] To address the aforementioned issues, lithium battery researchers have undertaken extensive work on modifying battery active materials, current collector thickness, and optimizing electrolyte composition, resulting in improved high and low temperature performance. However, the potential for further improvements in cycle life through chemical systems or processes remains relatively limited. Therefore, lithium battery researchers have focused on improving the cycle life of lithium-ion batteries by employing cyclic charging regimes. This typically involves reducing the voltage (current) during cycling to decrease the degree of side reactions occurring in the battery, thereby extending its lifespan. Voltage reduction methods include single voltage reductions and multiple voltage reductions. However, voltage reduction often leads to a significant decrease in cycle capacity retention. Summary of the Invention

[0005] In view of this, this application provides a charging method, a charging and discharging method, and a charging system for a lithium-ion battery. By adjusting the cycle charging capacity, the goal of extending the battery's long-cycle capacity without degradation or delaying degradation can be achieved, which can significantly improve the cycle capacity retention rate of the lithium-ion battery and solve the technical problem of low cycle capacity retention rate of lithium-ion batteries in the prior art.

[0006] As a first aspect of this application, this application provides a method for charging a lithium-ion battery, comprising:

[0007] S1: Charge the lithium-ion battery to the calibrated charging voltage using a first preset charging regime to determine the calibrated charge cycle capacity C0 of the lithium-ion battery; and

[0008] S2: The lithium-ion battery is charged to its first preset charging cycle capacity using a second preset charging regime until charging stops, thereby determining the first preset charging cycle capacity C of the lithium-ion battery. i ,

[0009] Wherein, the first preset charging cycle capacity is equal to α*C0, where α is 50% to 110%;

[0010] Where i is an integer greater than or equal to 1.

[0011] In one embodiment of this application, S2 includes:

[0012] S22: Charge the lithium-ion battery with a first preset current constant current to the first preset voltage for the (i+1)th time, then charge it with a constant voltage until the first preset charging cycle capacity is reached, at which point charging is stopped; thus determining the (i+1)th charging cycle capacity C of the lithium-ion battery. i+1 .

[0013] In one embodiment of this application, S1 includes:

[0014] The lithium-ion battery is charged to a third preset voltage using a first preset charging regime to determine the rated charging cycle capacity C0 of the lithium-ion battery.

[0015] Wherein, the calibrated charging voltage is the rated charging voltage of the lithium-ion battery, and the third preset voltage is less than the rated charging voltage of the lithium-ion battery.

[0016] In one embodiment of this application, the charging cut-off current at the charging cut-off point is less than or equal to 0.02C, or the charging cut-off current at the charging cut-off point is less than or equal to a preset cut-off current, wherein the preset cut-off current is the cut-off current at which the lithium-ion battery is charged to β times its standard charge cycle capacity under standard charging conditions, where β is 100%-110%; and / or

[0017] The charging cutoff voltage at which charging is cut off is less than or equal to the first preset voltage.

[0018] In one embodiment of this application, the first preset voltage is greater than the rated charging voltage of the lithium-ion battery.

[0019] In one embodiment of this application, the first preset voltage is equal to the rated charging voltage of the lithium-ion battery.

[0020] In one embodiment of this application, S22 includes:

[0021] S225: The lithium-ion battery is charged for the (i+1)th time to its rated charging voltage using a first preset constant current charging method, then charged to the first preset charging cycle capacity using a constant voltage method until charging is stopped, and then charged a second time to a third preset cycle capacity, wherein the difference between the third preset cycle capacity and the calibrated charging cycle capacity C0 is greater than 0; thus determining the (i+1)th charging cycle capacity C of the lithium-ion battery. i+1 .

[0022] In one embodiment of this application, the calibrated charging voltage is less than or equal to the rated charging voltage of the lithium-ion battery.

[0023] In one embodiment of this application, before S22, S2 further includes:

[0024] S210: Charge the lithium-ion battery to the first preset voltage using a constant current charging method with a first preset current, and then charge the lithium-ion battery with a constant voltage method; to determine the first charge cycle capacity C1 and the first discharge cycle capacity D1 of the lithium-ion battery.

[0025] S211: Charge the lithium-ion battery to a first preset voltage using a constant current charging method with a first preset current, and then charge the lithium-ion battery using a constant voltage method; to determine the i-th charge cycle capacity C of the lithium-ion battery. i ;

[0026] S212: Determine C i Whether it is less than γ times the calibrated charging cycle capacity C0, where γ is 80% to 100%;

[0027] When C i When the value is less than γ times the calibrated charging cycle capacity C0, the lithium-ion battery is charged for the (i+1)th time to the first preset voltage using a first preset constant current charging method, and then charged to the first preset charging cycle capacity using a constant voltage method until charging is stopped; thus, the (i+1)th charging cycle capacity C of the lithium-ion battery is determined. i+1 .

[0028] In one embodiment of this application, when C i When the value is greater than or equal to γ ​​times the calibrated charging cycle capacity C0, the lithium-ion battery is charged to the first preset voltage using a first preset constant current charging method, and then charged to the first preset voltage using a constant voltage method; thus determining the (i+1)th charging cycle capacity C of the lithium-ion battery. i+1 .

[0029] In one embodiment of this application, S2 includes:

[0030] S26: The lithium-ion battery is charged to its rated charging voltage using a constant current with a second preset current, and then charged to its first charging cycle capacity using a constant voltage until the charging is cut off; thus determining the first charging cycle capacity C1 of the lithium-ion battery; wherein the charging cut-off current for the first cycle charging is α*I0, where I0 is the charging cut-off current in the first preset charging system;

[0031] S27: Charge the lithium-ion battery with a second preset constant current to the rated charging voltage of the lithium-ion battery for the (i+1)th time, and then charge the lithium-ion battery with a constant voltage until the charging is stopped when the first preset charging cycle capacity is reached; thereby determining the (i+1)th charging cycle capacity C of the lithium-ion battery. i+1 The charging cutoff current for the (i+1)th charging cycle is I. f Among them, I f =θ f *I0; where f is the quotient of (i+1) and 100, rounded down and then incremented by 1;

[0032] Where, θ f+1 Greater than θ f .

[0033] In one embodiment of this application, S2 includes:

[0034] S28: The lithium-ion battery is charged to the second preset voltage using a constant current charging method with a third preset current, and then charged to the first preset charging cycle capacity using a constant voltage method until the charging is stopped; thereby determining the first charging cycle capacity C1 of the lithium-ion battery; wherein, the second preset voltage of the first cycle charging is α*V0, where V0 is the rated charging voltage of the lithium-ion battery;

[0035] S29: The lithium-ion battery is charged to the second preset voltage using a constant current charging method with a third preset current for the (i+1)th time, and then charged to the first preset charging cycle capacity using a constant voltage method until charging is stopped; thus determining the (i+1)th charging cycle capacity C of the lithium-ion battery. i+1 The second preset voltage for the (i+1)th charging cycle is V. f V f =η f *V0, where f is the quotient of (i+1) and 100, rounded down and then incremented by 1;

[0036] Where, η f+1 Greater than η f .

[0037] In one embodiment of this application, α is 80% to 100%.

[0038] As a second aspect of this application, this application also provides a method for charging and discharging a lithium-ion battery, comprising:

[0039] S4: Charge the lithium-ion battery for the jth time using the charging method described above.

[0040] S5: Discharge the lithium-ion battery for the jth time using a first preset discharge regime until the first preset discharge cycle capacity is reached, then discharge is stopped, to determine the charging cycle capacity C of the lithium-ion battery for the jth charge-discharge cycle. j and discharge cycle capacity D j ;

[0041] Where j is an integer greater than or equal to 1.

[0042] In one embodiment of this application, before S4, the charging and discharging method further includes:

[0043] The lithium-ion battery is charged to the calibrated charging voltage under a calibrated charging regime and discharged under a calibrated discharging regime to determine the calibrated charging cycle capacity C0 and the calibrated discharging cycle capacity D0 of the lithium-ion battery.

[0044] Wherein, the first preset discharge cycle capacity is equal to ε*D0, where ε is 50% to 110%.

[0045] In one embodiment of this application, S5 includes:

[0046] S51: The lithium-ion battery is discharged for the (j+1)th time at a first preset discharge current until the first preset discharge cycle capacity is reached, and then the discharge is stopped to determine the (j+1)th discharge cycle capacity D of the lithium-ion battery. i+1 .

[0047] In one embodiment of this application, before S51, S5 further includes:

[0048] S510: Discharge the lithium-ion battery to the rated discharge voltage for the first time using the second preset discharge current to determine the first discharge cycle capacity D1 of the lithium-ion battery;

[0049] S512: Discharge the lithium-ion battery to the rated discharge voltage using a second preset discharge current for the j-th time, to determine the j-th discharge cycle capacity D of the lithium-ion battery. j ;

[0050] S513: Determine D j Whether it is less than μ times the calibrated discharge cycle capacity D0, where μ is 50% to 110%;

[0051] When D j When the discharge cycle capacity is less than μ times the calibrated discharge cycle capacity D0, the lithium-ion battery is discharged for the (j+1)th time with a first preset discharge current until the discharge stops at the first preset discharge cycle capacity, thereby determining the (j+1)th discharge cycle capacity D of the lithium-ion battery. j+1 .

[0052] In one embodiment of this application, S5 includes:

[0053] S53: Discharge the lithium-ion battery for the first time with a first preset discharge current until the discharge is cut off when the first preset discharge cycle capacity is reached; to determine the first discharge cycle capacity D1 of the lithium-ion battery; wherein, the discharge cut-off voltage of the first cycle discharge is ε*V0, where V0 is the discharge cut-off voltage during the discharge under the calibrated discharge regime.

[0054] S54: Discharge the lithium-ion battery for the (j+1)th time with a second preset current until the first preset discharge cycle capacity is reached, at which point the discharge is stopped; thus, the (j+1)th discharge cycle capacity D of the lithium-ion battery is determined. j+1 The discharge cutoff voltage for the (j+1)th cycle discharge is V. f Among them, V f =w f *V0; where f is the quotient of (j+1) and 100, rounded down and then incremented by 1;

[0055] Among them, w f+1 Greater than w f .

[0056] As a third aspect of this application, this application also provides a charging system for a lithium-ion battery, comprising:

[0057] A charging device for cyclically charging the lithium-ion battery according to a charging regime; and

[0058] A controller, which is communicatively connected to the charging device, is used to execute the lithium-ion battery charging method described above.

[0059] This application provides a charging method, a charging and discharging method, and a charging system for a lithium-ion battery. By adjusting the cycle charging capacity, the goal of extending the battery's long-cycle capacity without degradation or delaying degradation can be achieved, which can significantly improve the cycle capacity retention rate of the lithium-ion battery and solve the technical problem of low cycle capacity retention rate of lithium-ion batteries in the prior art. In addition, the discharge capacity of the lithium-ion battery can also be adjusted by regulating the charging parameters in the charging regime (such as the charging voltage during constant current charging and the charging current during constant voltage charging). Attached Figure Description

[0060] The above and other objects, features, and advantages of this application will become more apparent from the more detailed description of the embodiments thereof in conjunction with the accompanying drawings. The drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the embodiments of this application to explain the application and do not constitute a limitation thereof. In the drawings, the same reference numerals generally represent the same components or steps.

[0061] Figure 1 The diagram shown is a schematic flowchart of a lithium-ion battery charging method provided in an embodiment of this application.

[0062] Figure 2 The diagram shown is a schematic flowchart of a lithium-ion battery charging method provided in another embodiment of this application.

[0063] Figure 3 The diagram shown is a schematic flowchart of a lithium-ion battery charging method provided in another embodiment of this application.

[0064] Figure 4 The diagram shown is a schematic flowchart of a lithium-ion battery charging method provided in another embodiment of this application.

[0065] Figure 5 The diagram shown is a schematic flowchart of a lithium-ion battery charging method provided in another embodiment of this application.

[0066] Figure 6 The diagram shown is a schematic flowchart of a lithium-ion battery charging method provided in another embodiment of this application.

[0067] Figure 7 The diagram shown is a schematic flowchart of a lithium-ion battery charging method provided in another embodiment of this application.

[0068] Figure 8 The diagram shown is a schematic flowchart of a lithium-ion battery charging method provided in another embodiment of this application.

[0069] Figure 9 The diagram shown is a schematic flowchart of a lithium-ion battery charging method provided in another embodiment of this application.

[0070] Figure 10 The diagram shown is a schematic diagram of the working principle of an electronic device provided in an embodiment of this application. Detailed Implementation

[0071] In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. All directional indications (such as up, down, left, right, front, back, top, bottom, etc.) in the embodiments of this application are only used to explain the relative positional relationships and movement of the components in a specific posture (as shown in the figures). If the specific posture changes, the directional indication will also change accordingly. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0072] Furthermore, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0073] The technical methods described below, with reference to the accompanying drawings of the embodiments of this application, will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0074] Exemplary methods

[0075] As a first aspect of this application, this application provides a method for charging a lithium-ion battery. Figure 1 The diagram shown is a schematic flowchart of a lithium-ion battery charging method according to an embodiment of this application. Figure 1 As shown, the charging method for this lithium-ion battery includes the following steps:

[0076] S1: Charge the lithium-ion battery to the calibrated charging voltage using the first preset charging regime to determine the calibrated charging cycle capacity C0 of the lithium-ion battery.

[0077] Specifically, the calibrated charging voltage is less than or equal to the rated charging voltage of the lithium-ion battery. For example, the calibrated charging voltage is the rated charging voltage of the lithium-ion battery, 4.48V. Another example is a calibrated charging voltage less than the rated charging voltage of the lithium-ion battery, such as 4.4V.

[0078] The rated charging voltage, also known as the maximum charging voltage, can be 4.48V, 4.40V, 4.45V, or 4.50V.

[0079] Specifically, the first preset charging system is a suitable charging system, which can be constant current charging at a preset current to the rated charging voltage of the lithium-ion battery (e.g., the rated charging voltage is 4.48V), and then constant voltage charging at the rated charging voltage of the lithium-ion battery to the cutoff current (e.g., the cutoff current is 0.02C) to cut off.

[0080] The preset current can be determined according to the characteristics of the lithium-ion battery and user needs, such as 0.5C in the standard charging regime.

[0081] For example, the first preset charging regime is: constant current charging at 0.5C to 4.48V, and then constant voltage charging at 4.48V until the current cuts off at 0.02C. That is, the first preset charging regime is: 0.5CCC to 4.48V, CV to 0.02C. Step S1 is to calibrate the charging cycle capacity during the cyclic charging process of the lithium-ion battery, that is, to determine the calibrated charging cycle capacity C0 of the lithium-ion battery; when cyclically charging the lithium-ion battery, the charging cycle capacity of each cycle is adjusted based on the calibrated charging cycle capacity C0.

[0082] S2: The lithium-ion battery is charged to its first preset charging cycle capacity using the second preset charging regime, and charging is stopped when the battery reaches the first preset charging cycle capacity. The first charging cycle capacity C of the lithium-ion battery is then determined. i ,

[0083] Wherein, the first preset charging cycle capacity is equal to α*C0, where α is 50% to 110%; where i is an integer greater than or equal to 1.

[0084] Specifically, such as Figure 1 As shown, when i equals 1, the first cycle of charging of the lithium-ion battery is performed. After the first cycle of charging is completed, i is incremented by 1, and then the second cycle of charging is performed. This process continues. After the i-th cycle of charging the lithium-ion battery, i is incremented by 1, and the lithium-ion battery is charged for the (i+1)-th cycle.

[0085] Specifically, in step S2, during the cyclic charging process of the lithium-ion battery, the charging capacity for each charging cycle is a first preset charging cycle capacity, which is equal to α times the calibrated charging cycle capacity C0. That is, in the i-th charging cycle, the first preset charging cycle capacity is equal to α times the calibrated charging cycle capacity C0, where α is 50% to 110%. In other words, during the cyclic charging process of the lithium-ion battery, the charging cycle capacity for each charging cycle is adjusted based on the calibrated charging cycle capacity C0 obtained in step S1, thereby achieving the adjustment of the charging capacity during the cyclic charging.

[0086] Optionally, α can be 80%–100%.

[0087] In one embodiment of this application, the specific method for determining α is as follows:

[0088] Step S70: Charge the lithium-ion battery using a known standard charging regime with constant current and constant voltage until the voltage V is reached. u Discharge to voltage V using a known standard current. L Thus, the standard initial charge and discharge capacities of the battery, C1 and D1, are obtained;

[0089] Specifically, the known standard charging system can be any standard charging system known in the prior art. For example, the standard charging system can be the standard charging system specified in GB / T18287-2000: charge the lithium-ion battery with a constant current of 0.5C to the charging cutoff voltage (4.2V), then charge the lithium-ion battery with a constant voltage to the charging cutoff current (0.02C); and discharge the lithium-ion battery with a discharge current of 0.2C to the discharge cutoff voltage (3.0V).

[0090] Step S71: Perform a conventional charge-discharge cycle on the lithium-ion battery, i.e., repeat the charge-discharge cycle N times as described in step 70 (where N is a positive integer, and N can be determined as needed), to obtain the charge-discharge capacity C of the Nth charge-discharge cycle. N D N .

[0091] Specifically, the charge / discharge capacity C of the Nth charge / discharge cycle is obtained using step S71. N D N See Table 1 below for details, which shows the charge / discharge capacity C corresponding to the base scheme in Table 1. N D N .

[0092] Step S72: Perform the Mth charge on the lithium-ion battery using a suitable charging regime. When the Mth charge cycle capacity of the lithium-ion battery is C... MCharging is stopped when the value equals X*C1. The lithium-ion battery is then discharged for the Mth time using a suitable discharge regime to determine the Mth charge cycle capacity C of the lithium-ion battery. M and the capacity D of the Mth discharge cycle M ;

[0093] Step S72 involves determining the charge cycle capacity as X*C during each charge-discharge cycle. 1， In other words, the charging cycle capacity is adjusted based on C1 during each charge-discharge cycle.

[0094] Specifically, a suitable charging regime controls the charging capacity by controlling the charging voltage, current carrying capacity (CV), temperature, and resistance. A suitable discharging regime could be: 0.5C CC to 4.48V, CV to 0.02C.

[0095] A suitable discharge regime is achieved by controlling the discharge capacity through measures such as discharge voltage, discharge current, temperature, and resistance. For example, a suitable discharge regime could be 0.2C to 3.0V.

[0096] Specifically, the lithium-ion battery is cycled using step S72 (where X = 20%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 100%, 105%, and 110%) under different X conditions, with a charging regime of 0.5C CC to 4.48V and CV to 0.02C. M and the capacity D of the Mth discharge cycle M Among them, the capacity C of the Mth charging cycle M See Table 1 below for details.

[0097] Table 1

[0098] Base scheme 100.00％ 98.46％ 97.67％ 94.92％ 93.33％ X＝20％ 20.01％ 20.03％ 20.04％ 20.01％ 19.99％ X＝40％ 40.04％ 40.07％ 40.02％ 40.09％ 40.02％ X＝50％ 50.06％ 50.04％ 50.05％ 50.01％ 50.03％ X＝60％ 60.01％ 59.99％ 59.98％ 60.03％ 60.01％ X＝70％ 70.02％ 70.04％ 70.01％ 70.05％ 69.99％ X＝80％ 80.01％ 80.08％ 80.05％ 79.98％ 80.01％ X＝90％ 90.00％ 90.03％ 90.01％ 90.03％ 90.00％ X＝95％ 95.08％ 95.10％ 95.11％ 95.04％ 95.01％ X＝100％ 100.00％ 100.01％ 100.05％ 100.03％ 99.98％ X＝105％ 105.11％ 104.03％ 103.12％ 102.04％ 101.01％ X＝110％ 110.01％ 107.24％ 105.12％ 102.34％ 98.04％

[0099] As can be seen from Table 1, the charge / discharge capacity C obtained by performing cyclic charge / discharge using step S71 (conventional charge / discharge cycle) is... N Therefore, we can obtain: △C=(100.00%-93.33%) / 600=0.0111%.

[0100] The charge / discharge capacity C obtained by performing cyclic charging and discharging using step S72 (adjusting the charging capacity) is... MWe can see that when X = 50% to 110%, ΔC is less than 0.0117%. For example, when X = 80, C100 = 80.08%C1, C200 = 80.05, then ΔC = 0.003%, which is much less than 0.0111%.

[0101] In other words, the charge / discharge capacity C obtained by cyclic charging and discharging using step S72 (adjusting the charging capacity to make the charging cycle capacity X*C1, where X = 50% to 110%) is... M Reducing the rate of degradation can improve the cycle capacity retention of lithium-ion batteries, thereby extending their service life.

[0102] Table 1 also shows that when X = 80% to 100%, ΔC is smaller. Therefore, the charge / discharge capacity C obtained by cyclic charging and discharging using step S72 (adjusting the charging capacity to make the charging cycle capacity X*C1, X = 80% to 100%) is the optimal value. M A significant reduction in degradation can substantially improve the cycle capacity retention of lithium-ion batteries, thereby extending their lifespan. Furthermore, the discharge capacity of lithium-ion batteries can be controlled by adjusting charging parameters in the charging process (e.g., charging voltage during constant current charging and charging current during constant voltage charging).

[0103] In one embodiment of this application, S2 (the lithium-ion battery is charged for the i-th time using a second preset charging regime, when the lithium-ion cycle capacity C of the i-th charge is...) i Charging stops when the capacity equals the first preset charging cycle capacity, thus determining the capacity C of the lithium-ion battery in the i-th charging cycle. i One way to regulate the cycle charging capacity of a lithium-ion battery during cyclic charging is by using constant-capacity charging.

[0104] like Figure 2 As shown, step S2 specifically includes the following steps:

[0105] S22: Charge the lithium-ion battery with a first preset current constant current to the first preset voltage for the (i+1)th time, then charge it with the first preset voltage constant voltage until the first preset charging cycle capacity (first preset charging cycle capacity = α*C0, where α is 50%~110%), at which point charging is stopped; thus determining the (i+1)th charging cycle capacity C of the lithium-ion battery. i+1 ;

[0106] In other words, the second preset charging regime in this embodiment is:

[0107] The lithium-ion battery is charged to the first preset voltage for the (i+1)th time using a constant current charging with the first preset current, and then charged to the first preset voltage using a constant voltage until the charging is cut off when the first preset charging cycle capacity (the first preset charging cycle capacity α*C0, where α is 50% to 110%).

[0108] Specifically, in step S22, the first preset current can be 0.5C.

[0109] Specifically, in step S22, the charging cut-off current is less than or equal to 0.02C when charging is cut off, or the charging cut-off current is less than or equal to a preset cut-off current. The preset cut-off current is the cut-off current when the lithium-ion battery is charged to β times the standard charging cycle capacity of the lithium-ion battery under the standard charging regime, where β is 100%-110%.

[0110] The charging cutoff voltage at the charging cutoff point is less than or equal to the first preset voltage.

[0111] Optionally, when using constant-capacity regulation to regulate the first preset charging cycle capacity of a lithium-ion battery during cyclic charging, the following regulation methods can be adopted:

[0112] ① Fixed volume + increased volume

[0113] like Figure 3 As shown, S22 specifically includes the following steps:

[0114] Step S221: Charge the lithium-ion battery for the (i+1)th time using a first preset current constant current charging method until it reaches a first preset voltage (the first preset voltage is greater than the rated charging voltage of the lithium-ion battery, for example, 4.53V). Then charge the lithium-ion battery for the first preset voltage constant voltage until it reaches a first preset charging cycle capacity (first preset charging cycle capacity = α*C0, where α is 50%~110%), at which point charging is stopped. The charging cycle capacity C of the lithium-ion battery for the (i+1)th time is then determined. i+1 ;

[0115] The first preset voltage is greater than the rated charging voltage of the lithium-ion battery. For example, when the rated charging voltage of the lithium-ion battery is 4.48V, the first preset voltage is greater than 4.48V. For example, the first preset voltage can be 4.53V.

[0116] That is to say, step S221 is to charge the lithium-ion battery for the (i+1)th time with a first preset current constant current in step S22 until it is greater than the rated charging voltage of the lithium-ion battery, and then charge the lithium-ion battery with a first preset voltage constant voltage until the first preset charging cycle capacity (first preset charging cycle capacity = α*C0, where α is 50%~110%), at which point charging is cut off.

[0117] Since the calibrated charging voltage in step S1 is less than or equal to the rated charging voltage of the lithium-ion battery, for example, the calibrated charging voltage is equal to 4.48V or 4.4V.

[0118] The first preset voltage in S221 is greater than the rated charging voltage of the lithium-ion battery, thus increasing the capacity of the lithium-ion battery. This allows the charging cycle capacity to be adjusted regardless of the number of charging cycles (i+1). For example, the charging cycle capacity can still be adjusted when the number of charging cycles (i+1) is 2000. That is, no matter how high the number of charging cycles (i+1) is, the charging cycle capacity C of the (i+1)th charging cycle can be adjusted. i+1 =α*C0.

[0119] ②Constant volume

[0120] like Figure 4 As shown, S22 specifically includes the following steps:

[0121] Step S222: Charge the lithium-ion battery for the (i+1)th time using a first preset constant current charging to the rated charging voltage of the lithium-ion battery (e.g., 4.48V), and then charge the lithium-ion battery for the first preset charging cycle capacity (first preset charging cycle capacity α*C0, where α is 50%~110%) at a constant voltage charging to cut off charging; thus determining the (i+1)th charging cycle capacity C of the lithium-ion battery. i+1 ;

[0122] The first preset voltage is equal to the rated charging voltage of the lithium-ion battery. For example, when the rated charging voltage of the lithium-ion battery is 4.48V, the first preset voltage is greater than 4.48V. For example, the first preset voltage can be 4.53V.

[0123] In other words, step S222 involves charging the lithium-ion battery for the (i+1)th time to the rated charging voltage of the lithium-ion battery using a first preset current constant current charging method, and then charging the lithium-ion battery at the rated charging voltage constant voltage until the first preset charging cycle capacity (first preset charging cycle capacity = α*C0, where α is 50%~110%) is reached and charging is stopped.

[0124] Step S222 is the first preset voltage in step S22, which is equal to the rated charging voltage of the lithium-ion battery.

[0125] ③ Fixed volume + increased volume

[0126] like Figure 5 As shown, S22 specifically includes the following steps:

[0127] Step S225: Charge the lithium-ion battery for the (i+1)th time using a first preset constant current charging to the rated charging voltage (e.g., 4.48V). Then charge the lithium-ion battery for the (i+1)th time using the rated constant voltage to the calibrated charging voltage (i.e., the first preset charging cycle capacity = 100*C0), at which point charging is stopped. Then charge the lithium-ion battery for the second time to the third preset cycle capacity. The difference between the third preset cycle capacity and the calibrated charging cycle capacity C0 is greater than 0. Determine the (i+1)th charging cycle capacity C of the lithium-ion battery. i+1 ;

[0128] Step S225 is the first preset voltage in step S22 that is equal to the rated charging voltage of the lithium-ion battery.

[0129] Optionally, the difference between the third preset cycle capacity and the calibrated charging cycle capacity C0 is 1mAh.

[0130] Specifically, during the second charging, the lithium-ion battery can be charged at a constant current with a second preset current.

[0131] Optionally, the second preset current is 0.1C.

[0132] Specifically, during the second charge, the lithium-ion battery can be recharged at a preset constant voltage.

[0133] In other words, after the lithium-ion battery is charged at a constant voltage to 4.48V, it is then charged at a constant current to the calibrated charging voltage (i.e., the first preset charging cycle capacity = 100*C0), at which point charging is stopped. A second charge is then performed to increase the charging capacity of the lithium-ion battery, thus improving its capacity. This allows the charging cycle capacity to be adjusted regardless of the number of charging cycles (i+1). For example, the charging cycle capacity can still be adjusted even when the number of charging cycles (i+1) is 2000. That is, regardless of the number of charging cycles (i+1), the charging cycle capacity C in the (i+1)th charging cycle can be adjusted. i+1 =α*C0.

[0134] Optional, such as Figure 6 As shown, S1 specifically includes the following steps:

[0135] S11: Charge the lithium-ion battery to a third preset voltage using a first preset charging regime; and discharge the lithium-ion battery using a second preset discharging regime to determine the calibrated charging cycle capacity C0 and the calibrated discharging cycle capacity D0 of the lithium-ion battery.

[0136] The calibrated charging voltage is the rated charging voltage of the lithium-ion battery, and the third preset voltage is lower than the rated charging voltage of the lithium-ion battery. For example, when the rated charging voltage of the lithium-ion battery is 4.48V, the third preset voltage is less than 4.48V; for example, the third preset voltage could be 4.4V.

[0137] Specifically, the first preset current can be 0.5C.

[0138] Step S11 can adjust the initial calibrated charging cycle capacity C0 of the lithium-ion battery, which means that the basis for adjusting the first charging cycle capacity during the lithium-ion battery's cyclic charging process, i.e., the initial SOC state of charge, can be adjusted.

[0139] Optional, such as Figure 7 As shown, before step S22, step S2 further includes the following steps:

[0140] S210: Charge the lithium-ion battery to the first preset voltage using a constant current charging method with a first preset current, and then charge the lithium-ion battery to the first preset voltage using a constant voltage method; to determine the first charge cycle capacity C1 of the lithium-ion battery.

[0141] S211: Charge the lithium-ion battery to a first preset voltage using a constant current charging method with a first preset current, and then charge the lithium-ion battery to a calibrated charging voltage using a constant voltage method with the first preset voltage (e.g., 4.48V; or less than 4.48V, e.g., 4.4V) to determine the i-th charge cycle capacity C of the lithium-ion battery. i ;

[0142] S212: Determine C i Is it less than γ times the rated charging cycle capacity C0, where γ is 80% to 100%?

[0143] When the judgment result in step S212 is yes, that is, when C i When the value is less than γ times the rated charging cycle capacity C0, the lithium-ion battery is charged for the (i+1)th time to the first preset voltage using a first preset constant current charging method, and then charged to the first preset charging cycle capacity using the first preset voltage constant voltage until charging is stopped; thus, the (i+1)th charging cycle capacity C of the lithium-ion battery is determined. i+1 .

[0144] That is, when the lithium-ion battery is charged in the normal way, if the charging cycle capacity decays significantly after the i-th charging cycle, the first preset charging cycle capacity of the lithium-ion battery is adjusted by using constant capacity charging during the (i+1)-th charging cycle to reduce the decay of the charging cycle capacity.

[0145] When the judgment result in step S212 is negative, that is, when C i When the value is greater than or equal to γ ​​times the rated charging cycle capacity C0, step S214 is executed: i is incremented by 1, i.e., i = i + 1; then step S211 is executed repeatedly with i = i + 1, i.e., the lithium-ion battery is charged to the first preset voltage using a constant current charging with the first preset current, and then the lithium-ion battery is charged to the first preset voltage using a constant voltage, so as to determine the (i + 1)th charging cycle capacity C of the lithium-ion battery. i+1 .

[0146] That is, when a lithium-ion battery is charged using conventional charging, if the capacity decay after the i-th charging cycle is small, the lithium-ion battery will still be charged using conventional charging in the (i+1)-th charging cycle.

[0147] In another embodiment of this application, in one embodiment of this application, S2 (the lithium-ion battery is charged for the i-th time using a second preset charging regime, when the lithium-ion cycle capacity C of the i-th charge is...) i Charging stops when the capacity equals the first preset charging cycle capacity, thus determining the capacity C of the lithium-ion battery in the i-th charging cycle. i One way to regulate the cycle charging capacity of lithium-ion batteries during cyclic charging is through constant voltage variable current charging.

[0148] like Figure 8 As shown, step S2 specifically includes the following steps:

[0149] S26: The lithium-ion battery is charged to its rated charging voltage using a constant current charging method with a second preset current, and then charged to its rated charging voltage until the charging is cut off when the first preset charging cycle capacity is reached; thereby determining the first charging cycle capacity C1 of the lithium-ion battery; wherein, the charging cut-off current I1 of the first cycle charging is α*I0, where I0 is the charging cut-off current in the first preset charging system;

[0150] Specifically, as mentioned above, the first preset charging cycle capacity is equal to α*C0, where α is 50% to 110%.

[0151] Specifically, when α is 95%, I1 = 95% * I0.

[0152] S27: Charge the lithium-ion battery for the (i+1)th time to the rated charging voltage of the lithium-ion battery using a second preset constant current charging method, and then charge the lithium-ion battery again to the first preset charging cycle capacity at the rated charging voltage of the lithium-ion battery, at which point charging is stopped; thus determining the (i+1)th charging cycle capacity C of the lithium-ion battery. i+1 ;

[0153] The charging cutoff current for the (i+1)th charging cycle is I. f Among them, I f =θ f *I0;

[0154] f is the quotient of (i+1) and 100, rounded down and then incremented by 1. For example, when i+1 equals 99, 99 / 100 is less than 1, so f is 1. For example, when i+1 equals 185, 185 / 100 equals 1.85, rounded down to 1, so f is 2. That is to say, when i+1 = 1 - 100, the charging cutoff current for each charging cycle is I1 = θ1 * I0; when i+1 = 101 - 200, the charging cutoff current for each charging cycle is I2 = θ2 * I0.

[0155] Specifically, θ increases as f increases, that is, θ f+1 Greater than θ f ;

[0156] When α is 95%, when i+1 = 1-100, that is, during the 1st-100th charging cycle, the charging cutoff current I1 = 95% * I0; that is, the initial value of θ is α.

[0157] When i+1 = 101-200, that is, during the 101st-200th charging cycle, θ2 in the charging cutoff current I2 is greater than 95%. For example, the charging cutoff current during the 101st-200th charging cycle can be 96%, i.e., I2 = 96% * I0. In other words, when cyclically charging a lithium-ion battery, the first preset charging cycle capacity for each charging cycle is controlled by changing the charging cutoff current during each charging cycle, thus controlling the charging cycle capacity for each charging cycle.

[0158] In another embodiment of this application, in one embodiment of this application, S2 (the lithium-ion battery is charged for the i-th time using a second preset charging regime, when the lithium-ion cycle capacity C of the i-th charge is...) i Charging stops when the capacity equals the first preset charging cycle capacity, thus determining the capacity C of the lithium-ion battery in the i-th charging cycle. i One way to regulate the cycle charging capacity of a lithium-ion battery during cyclic charging is by using a constant current-variable voltage charging method.

[0159] like Figure 9 As shown, step S2 specifically includes the following steps:

[0160] S28: Charge the lithium-ion battery to the second preset voltage using a constant current charging method with a third preset current, and then charge the lithium-ion battery to the first preset charging cycle capacity using a constant voltage method with the second preset voltage until the charging is stopped; thereby determining the first charging cycle capacity C1 of the lithium-ion battery; wherein, the second preset voltage of the first cycle charging is α*V0, where V0 is the rated charging voltage of the lithium-ion battery.

[0161] Specifically, as mentioned above, the first preset charging cycle capacity is equal to α*C0, where α is 50% to 110%.

[0162] Specifically, when α is 95%, V1 = 95% * V0.

[0163] S29: Charge the lithium-ion battery with a constant current of the third preset current for the (i+1)th time to the second preset voltage, and then charge the lithium-ion battery with the second preset voltage until the charging is stopped when the first preset charging cycle capacity is reached; thus determining the (i+1)th charging cycle capacity C of the lithium-ion battery. i+1 The second preset voltage for the (i+1)th charging cycle is V. f V f =η f *V0, and η f It increases as f increases, i.e., η f+1 Greater than η f ;

[0164] For example:

[0165] For example, when i+1 equals 1-100, (1-100) / 100 is less than 1, so f is 1. That is to say, when i+1 = 1-100, the second preset voltage V1 for each cycle of charging is η1*V0; similarly, when i+1 = 101-200, the second preset voltage V2 for each cycle of charging is η2*V0; η2 is greater than η1.

[0166] Specifically, when α is 95%, when i+1 = 1-100, that is, during the 1st to 100th charging cycles, the second preset voltage V1 for each cycle is η1*V0 = 95%*V0; that is, the initial value of η is α. When i+1 = 101-200, that is, during the 101st to 200th charging cycles, the second preset voltage V1 is η2*V0 = 96%*V0. That is, η2 is 96%.

[0167] That is, when the lithium-ion battery is cycle-charged, the first preset charging cycle capacity is adjusted by changing the second preset voltage during each charging cycle, thus adjusting the charging cycle capacity during each charging cycle.

[0168] Exemplary charging and discharging methods

[0169] As a second aspect of this application, this application also provides a method for charging and discharging a lithium-ion battery, comprising the following steps:

[0170] S4: Charge the lithium-ion battery for the jth time using the charging method described above.

[0171] S5: Discharge the lithium-ion battery for the jth time using a first preset discharge regime until the first preset discharge cycle capacity is reached, then discharge is stopped, to determine the charging cycle capacity C of the lithium-ion battery for the jth charge-discharge cycle. j and discharge cycle capacity D j ;

[0172] Where j is an integer greater than or equal to 1.

[0173] The first preset discharge regime can be a conventional discharge regime, and in this case, the first preset discharge cycle capacity can be the discharge cycle capacity obtained under the conventional discharge regime.

[0174] Specifically, prior to S4, the charging and discharging methods for lithium-ion batteries also included the following steps:

[0175] S40: Charge the lithium-ion battery to the calibrated charging voltage using a calibrated charging regime, and discharge it using a calibrated discharging regime to determine the calibrated charging cycle capacity C0 and the calibrated discharging cycle capacity D0 of the lithium-ion battery.

[0176] Wherein, the first preset discharge cycle capacity is equal to ε*D0, where ε is 50% to 110%, or optionally, ε is 80% to 100%.

[0177] Specifically, ε is determined in the same way as α was determined above, and will not be repeated here.

[0178] Specifically, the calibrated discharge regime is a suitable discharge regime that discharges to the calibrated discharge voltage with a constant discharge current. The constant discharge current can be a standard discharge current (e.g., 0.2C) or a larger one (e.g., 0.2C), such as 0.7C or 0.5C.

[0179] Step S40 is to calibrate the charge-discharge cycle capacity of the lithium-ion battery during the cyclic charge-discharge process, that is, to determine the calibrated charge cycle capacity C0 and the calibrated discharge cycle capacity D0 of the lithium-ion battery; when the lithium-ion battery is cyclically charged and discharged, the discharge cycle capacity of each charge-discharge cycle is adjusted based on the calibrated discharge cycle capacity D0.

[0180] In one embodiment of this application, S5 (discharge is stopped when the lithium-ion battery is discharged for the jth time to the first preset discharge cycle capacity under a first preset discharge regime, so as to determine the charging cycle capacity C of the lithium-ion battery for the jth charge-discharge cycle) j and discharge cycle capacity D j )include:

[0181] S51: The lithium-ion battery is discharged for the (j+1)th time at a first preset discharge current until the first preset discharge cycle capacity is reached, and then the discharge is stopped to determine the (j+1)th discharge cycle capacity D of the lithium-ion battery. i+1 .

[0182] Wherein, the first preset discharge cycle capacity = ε * D0, where ε is 50% to 110%; and the discharge cycle capacity D of the lithium-ion battery in the (j+1)th cycle is determined. j+1 ;

[0183] In other words, the first preset discharge regime in this embodiment is:

[0184] The lithium-ion battery is discharged for the (i+1)th time with a first preset discharge current until the first preset discharge cycle capacity (first preset discharge cycle capacity ε*D0, where ε is 50%~110%) is reached, at which point the discharge is cut off.

[0185] Specifically, in step S51, the first preset discharge current can be 0.5C or 0.7C.

[0186] In one embodiment of this application, before S51, S5 further includes:

[0187] S510: Discharge the lithium-ion battery to the rated discharge voltage for the first time using the second preset discharge current to determine the first discharge cycle capacity D1 of the lithium-ion battery;

[0188] S512: Discharge the lithium-ion battery to the rated discharge voltage using a second preset discharge current for the j-th time, to determine the j-th discharge cycle capacity D of the lithium-ion battery. j ;

[0189] S513: Determine D j Whether it is less than μ times the calibrated discharge cycle capacity D0, where μ is 50% to 110%;

[0190] When D j When the discharge cycle capacity is less than μ times the calibrated discharge cycle capacity D0, the lithium-ion battery is discharged for the (j+1)th time with a first preset discharge current until the discharge stops at the first preset discharge cycle capacity, thereby determining the (j+1)th discharge cycle capacity D of the lithium-ion battery. j+1(i.e., step S51).

[0191] That is, when the lithium-ion battery is discharged according to the normal discharge method, if the discharge cycle capacity decays significantly after the j-th discharge cycle, the discharge method described in step S51 is started during the (j+1)-th discharge cycle. In other words, the first preset discharge cycle capacity in the lithium-ion battery cycle discharge is adjusted to reduce the decay of the discharge cycle capacity.

[0192] When the judgment result in step S513 is negative, that is, when D j When the value is greater than or equal to γ ​​times the rated discharge cycle capacity D0, step S514 is executed: j is incremented by 1, i.e., j = j + 1; then step S512 is executed repeatedly with j = j + 1, i.e., the lithium-ion battery is discharged to the rated discharge voltage for the jth time with the second preset discharge current, so as to determine the jth discharge cycle capacity D of the lithium-ion battery. j .

[0193] That is, when the lithium-ion battery is discharged in a conventional discharge manner, if the discharge cycle capacity decay is small after the j-th discharge cycle, the lithium-ion battery will still be discharged in a conventional discharge manner in the j+1-th discharge cycle.

[0194] In one embodiment of this application, S5 (discharge is stopped when the lithium-ion battery is discharged for the jth time to the first preset discharge cycle capacity under a first preset discharge regime, so as to determine the charging cycle capacity C of the lithium-ion battery for the jth charge-discharge cycle) j and discharge cycle capacity D j )include:

[0195] S53: Discharge the lithium-ion battery for the first time with a first preset discharge current until the discharge is cut off when the first preset discharge cycle capacity is reached; to determine the first discharge cycle capacity D1 of the lithium-ion battery; wherein, the discharge cut-off voltage of the first cycle discharge is ε*V0, where V0 is the discharge cut-off voltage during the discharge under the calibrated discharge regime.

[0196] Specifically, as mentioned above, the first preset discharge cycle capacity is equal to ε*C0, where ε is 50% to 110%.

[0197] S54: Discharge the lithium-ion battery for the (j+1)th time with a second preset current until the first preset discharge cycle capacity is reached, at which point the discharge is stopped; thus, the (j+1)th discharge cycle capacity D of the lithium-ion battery is determined. j+1 The discharge cutoff voltage for the (j+1)th cycle discharge is V. f Among them, V f =w f*V0; where f is the quotient of (j+1) and 100, rounded down and then incremented by 1;

[0198] Among them, w f+1 Greater than w f .

[0199] Specifically, when ε is 95%, V1 = 95% * V0.

[0200] f is the quotient of (i+1) and 100, rounded down and then incremented by 1. For example, when i+1 equals 99, 99 / 100 is less than 1, so f is 1. For example, when i+1 equals 185, 185 / 100 equals 1.85, rounded down to 1, so f is 2. That is to say, when i+1 = 1 - 100, the discharge cutoff voltage for each cycle is V1 = w1 * V0; when i+1 = 101 - 200, the discharge cutoff voltage for each cycle is V2 = w2 * V0.

[0201] Specifically, w f w increases as f increases. f+1 Greater than w f ;

[0202] When α is 95%, when i+1 = 1-100, that is, during the 1st-100th discharge cycle, the discharge cutoff voltage V1 = 95% * V0; that is, the initial value of w is ε.

[0203] When i+1 = 101-200, that is, during the 101st-200th discharge cycle, w2 in the discharge cutoff voltage V2 is greater than 95%. For example, the discharge cutoff voltage V2 during the 101st-200th discharge cycle can be 96% V0, i.e., V2 = 96% * V0. In other words, when cyclically discharging a lithium-ion battery, the first preset discharge cycle capacity for each discharge cycle is controlled by changing the discharge cutoff voltage during each discharge cycle, thus controlling the discharge cycle capacity for each discharge cycle.

[0204] The following specific embodiments further illustrate the charging and discharging methods for a lithium-ion battery provided in this application.

[0205] Example 1

[0206] Example 1: The rated charging voltage of the lithium-ion battery is 4.48V, the first preset voltage is 4.48V, and α is 95%; the control method is constant capacity.

[0207] Place the battery in an environment of 12–45°C.

[0208] Step1:0.5C CC to 4.48V, CV to 0.02C / 0.2C to 3.0V→Cap0

[0209] The charging method is: 0.5C CC to 4.48V, CV to 0.02C; the discharging method is 0.2C to 3.0V. In each of the following charging steps, the description before the slash refers to the charging method, and the description after the slash refers to the discharging method.

[0210] Step 2: Charge to the specified voltage limit of 4.48V using the specified charging method, CV to 0.02C / 0.7C to 3.0V → Cap1

[0211] Step 3: Charge according to the specified method until the voltage reaches the upper limit of 4.48V. The charge will stop when the capacity equals Cap1 * 0.952, with a maximum cutoff of 4.48V - 0.02C / 0.7C to 3.0V. Repeat this cycle n times.

[0212] Step 4: Every 100T: 0.5C to the upper limit of voltage 4.48V. When the capacitance = Cap0 * 0.952, it will be cut off. The maximum cutoff is 4.48V - 0.02C / 0.2C to 3.0V.

[0213] Specifically, the charging methods in Step 1 and Step 2 are the specific steps of step S1 (which calibrates the charging cycle capacity and discharging cycle capacity during the cyclic charging process of the lithium-ion battery) as described above.

[0214] In Step 1, Cap0 is the basis for adjusting the discharge cycle capacity for each 100T (e.g., the 100th, 200th, 300th, etc.) charging cycle. In Step 2, Cap1 is the basis for adjusting the discharge cycle capacity for each (non-100T) charging cycle.

[0215] The Cap0 determined in Step 1 is used as the basis for adjusting the discharge cycle capacity for every 100T (e.g., the 100th, 200th, 300th, etc.) charging cycles. This serves as test data to verify the decrease in discharge cycle capacity when using a high discharge current (e.g., 0.7C in Step 3) and the discharge cycle capacity D when using a low discharge current (e.g., 0.2C in Step 4). i The difference in degradation is negligible. In other words, when the charging cycle capacity is adjusted during the cyclic charging of a lithium-ion battery, whether the discharge is carried out at a constant high current or a constant low current, the effect on the degradation of the discharge cycle capacity is negligible.

[0216] Step 3 and the charging method in Step 3 are the specific steps of step S2 described above.

[0217] Example 2:

[0218] Implementation Case 2: The rated charging voltage of the lithium-ion battery is 4.48V, the first preset voltage is 4.53V, and α is 95%; the control method is: constant capacity + increase capacity.

[0219] Place the battery in an environment of 12–45°C.

[0220] Step1:0.5C CC to 4.48V, CV to 0.02C / 0.2C to 3.0V→Cap0

[0221] Step 2: Charge to the upper voltage limit of 4.48V using the specified charging method, CV to 0.02C / 0.7C to 3.0V → Cap1.

[0222] Step 3: Charge to the upper voltage limit of 4.53V using the specified charging method. When the capacity = Cap1 * 0.952, the maximum cutoff is 4.53V - xxC / 0.7C to 3.0V. Repeat this cycle n times.

[0223] Among them, the cutoff current xxC is the cutoff current with a capacity of 102%-110% of the standard capacity.

[0224] Step 4: Every 100T: 0.5C to the upper voltage limit of 4.53V. When the capacitance = Cap0 * 0.952, the cutoff value is 4.53V - xx C / 0.2C to 3.0V.

[0225] Implementation Case 3:

[0226] Example 3: The rated charging voltage of the lithium-ion battery is 4.48V, the first preset voltage is 4.48V, and α is 95%; the control method is constant capacity.

[0227] Place the battery in an environment of 12–45°C.

[0228] Step1:0.5C CC to 4.4V, CV to 0.02C / 0.2C to 3.0V→Cap0

[0229] Since 4.4 is less than 4.48, Cap0 is less than 95% of the nominal capacity cycle.

[0230] Step 2: Charge to the specified voltage limit of 4.4V using the specified charging method, CV to 0.02C / 0.7C to 3.0V → Cap1

[0231] Step 3: Charge according to the specified method until the voltage reaches the upper limit of 4.48V. The charge will stop when the capacity equals Cap1 * 0.952, with a maximum cutoff of 4.48V - 0.02C / 0.7C to 3.0V. Repeat this cycle n times.

[0232] Step 4: Every 100T: 0.5C to the upper limit of voltage 4.48V. When the capacitance = Cap0 * 0.952, it will be cut off. The maximum cutoff is 4.48V - 0.02C / 0.2C to 3.0V.

[0233] Example 4

[0234] Example 4: The rated charging voltage of the lithium-ion battery is 4.48V, the first preset voltage is 4.53V, and α is 98%; the control method is constant capacity.

[0235] Place the battery in an environment of 12–45°C.

[0236] Step1:0.5C CC to 4.48V, CV to 0.02C / 0.2C to 3.0V→Cap0

[0237] Step 2: Charge to the specified voltage limit of 4.48V using the specified charging method, CV to 0.02C / 0.7C to 3.0V → Cap1

[0238] Step 3: Charge to the upper voltage limit of 4.53V using the specified charging method. When the capacity = Cap1 * 0.982, the maximum cutoff is 4.53V - xxC / 0.7C to 3.0V. Repeat this cycle n times.

[0239] Step 4: Every 100T: 0.5C to the upper voltage limit of 4.53V, cut off when capacitance = Cap0 * 0.982, maximum cutoff is 4.53V - xxC / 0.2C to 3.0V.

[0240] Among them, the cutoff current xxC is the cutoff current with a capacity of 102%-110% of the standard capacity.

[0241] Example 5

[0242] Implementation Case 5: The rated charging voltage of the lithium-ion battery is 4.48V, the first preset voltage is 4.53V, and α is 100%; the control method is: constant capacity + increase capacity.

[0243] Place the battery in an environment of 12–45°C.

[0244] Step1:0.5C CC to 4.48V, CV to 0.02C / 0.2C to 3.0V→Cap0

[0245] Step 2: Charge to the specified voltage limit of 4.48V using the specified charging method, CV to 0.02C / 0.7C to 3.0V → Cap1

[0246] Step 3: Charge to the upper voltage limit of 4.53V using the specified charging method. When the capacity = Cap1 * 1.002, the maximum cutoff is 4.53V - xxC / 0.7C to 3.0V. Repeat this cycle n times.

[0247] Step 4: Every 100T: 0.5C to the upper voltage limit of 4.53V. When the capacitance = Cap0 * 1.002, it will be cut off. The maximum cutoff is 4.53V - xx C / 0.2C to 3.0V.

[0248] Among them, the cutoff current xxC is the cutoff current with a capacity of 102%-110% of the standard capacity.

[0249] Example 6

[0250] Implementation Case 6: The rated charging voltage of the lithium-ion battery is 4.48V, the first preset voltage is 4.53V, and α is 95%; the control method is: mid-stage cycle constant capacity + capacity increase.

[0251] Place the battery in an environment of 12–45°C.

[0252] Step1:0.5C CC to 4.48V, CV to 0.02C / 0.2C to 3.0V→Cap0

[0253] Step 2: Charge to the specified voltage limit of 4.48V using the specified charging method, CV to 0.02C / 0.7C to 3.0V → Cap1

[0254] Step 3: Charge according to the specified method until the voltage reaches the upper limit of 4.53V, CV to xxC / 0.7C to 3.0V, cycle n times → Capn

[0255] Step 4: Every 100T: 0.5C to the upper voltage limit of 4.53V, CV to xxC / 0.2C to 3.0V

[0256] Step 5: If Capn < Cap1 * 0.95, proceed to Step 6; if Capn ≥ Cap1 * 0.95, proceed to Step 3 and Step 4.

[0257] Step 6: Charge to the upper voltage limit of 4.53V using the specified charging method. When the capacity = Cap1 * 0.952, the maximum cutoff is 4.53V - xxC / 0.7C to 3.0V.

[0258] Step 7: Every 100T: 0.5C to the upper voltage limit of 4.53V, when the capacitance = Cap0 * 0.952 cuts off, the highest cutoff is 4.53V - xxC / 0.2C to 3.0V;

[0259] Among them, the cutoff current xxC is the cutoff current with a capacity of 102%-110% of the standard capacity.

[0260] Example 7

[0261] Implementation Case 7: The rated charging voltage of the lithium-ion battery is 4.48V, the first preset voltage is 4.48V, α is 95%, and w is 0.05; the control method is: variable current constant capacity.

[0262] Place the battery in an environment of 12–45°C.

[0263] Step1:0.5C CC to 4.48V, CV to 0.02C / 0.2C to 3.0V→Cap0

[0264] Step 2: Charge according to the specified method until the voltage reaches the upper limit of 4.48V, CV to I-0.95 / 0.7C to 3.0V.

[0265] Step 3: For every additional 100T, change CV to I-0.95, then to I-0.955, I-0.96, ..., I-1.00 / 0.2C to 3.0V.

[0266] Implementation Case 8

[0267] Example 8: The rated charging voltage of the lithium-ion battery is 4.48V, the first preset voltage is 4.48V, α is 95%, and k is 0.05; the control method is: variable voltage constant capacity.

[0268] Place the battery in an environment of 12–45°C.

[0269] Step1:0.5C CC to 4.48V, CV to 0.02C / 0.2C to 3.0V→Cap0

[0270] Step 2: Charge at 0.1C until the voltage V-0.95 / 0.7C reaches 3.0V;

[0271] Step 3: For every additional 100T: V-0.95, change to V-0.955, V-0.96, ..., V-1.00 / 0.7C to 3.0V.

[0272] Example 9

[0273] Implementation Case 9: The rated charging voltage of the lithium-ion battery is 4.48V, the first preset voltage is 4.48V, and α is 100%; the control method is: accelerator capacity.

[0274] Place the battery in an environment of 12–45°C.

[0275] Step1:0.5C CC to 4.48V, CV to 0.02C / 0.2C to 3.0V→Cap0

[0276] Step 2: Charge to the upper voltage limit of 4.48V using the specified charging method, CV to 0.02C / 0.7C to 3.0V → Cap1;

[0277] Step 3: Charge to the upper voltage limit of 4.48V using the specified charging method, and charge an additional 1mAh at 0.1C when it is time to stop.

[0278] Example 10

[0279] Example 10: α is 95%, discharge method: variable cutoff voltage discharge.

[0280] Place the battery in an environment of 12–45°C.

[0281] Step1:0.5C CC to 4.48V, CV to 0.02C / 0.2C to 3.0V→Cap0

[0282] That is, the charging cycle is: 0.5C CC to 4.48V, CV to 0.02C; the discharging cycle is: 0.2C to 3.0V.

[0283] In each of the following steps, the descriptions before the slash refer to the charging method, and the descriptions after the slash refer to the discharging method.

[0284] Specifically, the discharge method in Step 1 is the specific step described above for calibrating the discharge cycle capacity during the cyclic discharge process of a lithium-ion battery.

[0285] Step 2: Charge using the specified charging method: 0.7C to V-0.95

[0286] The battery is discharged at a current of 0.7C until the cutoff voltage is 95%V0 (i.e., 3.0V); the resulting discharge capacity is 95%Cap0 (i.e., D0).

[0287] Step 3: For every additional 100T thereafter, the discharge cutoff voltage is changed to: 0.96% V0, ..., 98% V0, ..., 105%.

[0288] Example 11:

[0289] Implementation Case 11: α is 98%,

[0290] Place the battery in an environment of 12–45°C.

[0291] Step1:0.5C CC to 4.48V, CV to 0.02C / 0.2C to 3.0V→Cap0

[0292] Step 2: Charge according to the specified charging method to the upper voltage limit of 4.48V, CV to 0.02C / 0.7C to 3.0V → Cap1

[0293] Step 3: Charge according to the specified charging method to the upper voltage limit of 4.48V, CV to 0.02C / 0.7C to Cap1*0.982, repeat n times.

[0294] That is, the adjustment basis for the discharge cycle capacity of each non-100T (e.g., the 34th, 105th, and 408th charging cycle) is Cap1 obtained in Step 2.

[0295] Step 4: Every 100T: 0.5C to the upper voltage limit of 4.48V, CV to 0.02C / 0.2C to Cap0*0.982;

[0296] That is, the adjustment basis for the discharge cycle capacity of every 100T (e.g., the 100th, 200th, 300th, etc.) discharge cycle is Cap0 obtained in Step 1.

[0297] Specifically, the discharge methods in Step 1 and Step 2 are the specific steps described above for calibrating the discharge cycle capacity during the cyclic discharge process of a lithium-ion battery.

[0298] In Step 1, Cap0 is the basis for adjusting the discharge cycle capacity for every 100T (e.g., the 100th, 200th, 300th, etc.) discharge cycle. In Step 2, Cap1 is the basis for adjusting the discharge cycle capacity for each (non-100T) discharge cycle.

[0299] The Cap0 determined in Step 1 is used as the basis for adjusting the discharge cycle capacity for every 100T (e.g., the 100th, 200th, 300th, etc.) discharge cycles. This serves as test data to verify the attenuation of the discharge cycle capacity when using a high current (e.g., 0.7C in Step 3) and the discharge cycle capacity D when using a low current (e.g., 0.2C in Step 4). i The difference in degradation is negligible. In other words, when the discharge cycle capacity is adjusted during the cyclic discharge of a lithium-ion battery, whether the discharge is carried out at a constant high current or a constant low current, the effect on the degradation of the discharge cycle capacity is negligible.

[0300] Example 12:

[0301] Implementation Case 12: α is 80%.

[0302] Place the battery in an environment of 12–45°C.

[0303] Step1:0.5C CC to 4.48V, CV to 0.02C / 0.2C to 3.0V→Cap0

[0304] Step 2: Charge according to the specified charging method to the upper voltage limit of 4.48V, CV to 0.02C / 0.7C to 3.0V → Cap1

[0305] Step 3: Charge to the upper voltage limit of 4.48V using the specified charging method, then CV to 0.02C / 0.7C to Cap1*0.802, repeat n times.

[0306] That is, the adjustment basis for the discharge cycle capacity of each non-100T (e.g., the 34th, 105th, and 408th discharge cycle) is Cap1 obtained in Step 2.

[0307] Step 4: Every 100T: 0.5C to the upper voltage limit of 4.48V, CV to 0.02C / 0.2C to Cap0*0.802;

[0308] That is, the adjustment basis for the discharge cycle capacity of every 100T (e.g., the 100th, 200th, 300th, etc.) discharge cycle is Cap0 obtained in Step 1.

[0309] Example 13:

[0310] Example 13: α is 95%,

[0311] Place the battery in an environment of 12–45°C.

[0312] Step1:0.5C CC to 4.48V, CV to 0.02C / 0.2C to 3.0V→Cap0

[0313] Step 2: Charge according to the specified charging method to the upper voltage limit of 4.48V, CV to 0.02C / 0.7C to 3.0V → Cap1

[0314] Step 3: Charge according to the specified charging method to the upper voltage limit of 4.48V, CV to 0.02C / 0.7C to 3.0V, cycle n times → Capn

[0315] Step 4: Every 100T, increase the voltage by 0.5C to the upper limit of 4.48V, then increase the voltage CV to 0.02C / 0.2C to 3.0V.

[0316] Step 5: When Capn < Cap1 * 0.95, proceed to Step 6.

[0317] When Capn ≥ Cap1 * 0.95, proceed to Step 3;

[0318] Step 6: Charge to 4.53V using the specified charging method, then CV to xxC / 0.7C to Cap1*0.952, repeat n times.

[0319] Step 7: Every 100T: Charge to 4.53V using the specified charging method, CV to xxC / 0.2C to Cap0*0.952;

[0320] When the discharge begins, it is discharged in a normal discharge mode. When the discharge capacity is less than Cap1*0.95, step S2 is used to adjust the discharge capacity in order to reduce the decay of the discharge capacity.

[0321] Among them, the cutoff current xxC is the cutoff current with a capacity of 102%-110% of the standard capacity.

[0322] Example 14:

[0323] Implementation Case 14: α is 100%.

[0324] Place the battery in an environment of 12–45°C.

[0325] Step1:0.5C CC to 4.48V, CV to 0.02C / 0.2C to 3.0V→Cap0

[0326] Step 2: Charge according to the specified charging method to the upper voltage limit of 4.48V, CV to 0.02C / 0.7C to 3.0V → Cap1

[0327] Step 3: Charge to 4.53V using the specified charging method, then CV to xxC / 0.7C to Cap 1*100%, repeat n times.

[0328] That is, the adjustment basis for the discharge cycle capacity of each non-100T (e.g., the 34th, 105th, and 408th discharge cycle) is Cap1 obtained in Step 2.

[0329] Step 4: Every 100T: 0.5C to the upper voltage limit of 4.53V, CV to xxC / 0.2C to Cap0*100%;

[0330] That is, the adjustment basis for the discharge cycle capacity of every 100T (e.g., the 100th, 200th, 300th, etc.) discharge cycle is Cap0 obtained in Step 1.

[0331] Among them, the cutoff current xxC is the cutoff current with a capacity of 102%-110% of the standard capacity.

[0332] Example 15:

[0333] Example 15: α is 90%,

[0334] Place the battery in an environment of 12–45°C.

[0335] Step1:0.5C CC to 4.4V, CV to 0.02C / 0.2C to 3.0V→Cap0

[0336] Step 2: Charge according to the specified charging method to the upper voltage limit of 4.4V, CV to 0.02C / 0.7C to 3.0V → Cap1

[0337] Step 3: Charge according to the specified charging method to the upper voltage limit of 4.4V, CV to 0.02C / 0.7C to 3.0V, cycle n times → Capn

[0338] Step 4: Every 100T: 0.5C to the upper voltage limit of 4.48V, CV to 0.02C / 0.2C to 3.0V

[0339] Step 5: When Capn < Cap1 * 0.95, proceed to Step 6.

[0340] When Capn ≥ Cap1 * 0.95, proceed to Step 3;

[0341] Step 6: Charge to 4.48V using the specified charging method, then CV to 0.02C / 0.7C to Cap1*0.902, repeat n times.

[0342] Step 7: Every 100T: 0.5C to the upper voltage limit of 4.48V, CV to 0.02C / 0.2C to Cap0*0.902;

[0343] At the start of discharge, a conventional discharge method is used. When the discharge capacity is less than Cap1*0.95, step S2 is used to adjust the discharge capacity to 90% to reduce the decay of the discharge capacity after multiple cycles. That is, after multiple conventional cycles, when S2 is used to adjust the discharge capacity, the discharge capacity can be controlled at 90%.

[0344] Comparative Example

[0345] The lithium-ion battery was subjected to charge-discharge cycle testing using conventional charge-discharge cycle methods.

[0346] The i-th charge cycle capacity Cap was obtained by cyclic charging and discharging of lithium-ion batteries using Examples 1-15 and the comparative examples. i (D i See Table 2 below for details.

[0347] Table 2

[0348]

[0349]

[0350] From Table 2, we can obtain:

[0351] The comparison yields:

[0352] △C≈△D=△Cap=(97.67%-94.92%) / 200=0.0137%.

[0353] The discharge capacity Cap obtained by performing cyclic charging and discharging using Examples 1-15 of this paper is... i (D iFrom this, we can obtain the following: In Example 1 (α = 95%), ΔC ≈ ΔD = ΔCap = (95.08% - 95.01%) / 600 = 0.0001%, which is much less than 0.0137%. Compared to the initial (first) discharge cycle charge capacity, the cycle charge capacity decay after i cycles is very small (even negligible). Therefore, when charging a lithium-ion battery, if charging is stopped when the cycle charge capacity reaches 95% C0 during each cycle, the cycle charge capacity can be controlled to maintain at 95%.

[0354] In other words, the charge / discharge capacity C obtained by cyclic charging and discharging using the charging method provided in this application is... i A significant reduction in degradation can substantially improve the cycle capacity retention of lithium-ion batteries, thereby extending their lifespan. Furthermore, the charging capacity of lithium-ion batteries can also be controlled by adjusting charging parameters in the charging process (e.g., charging voltage during constant current charging and charging current during constant voltage charging).

[0355] Exemplary System

[0356] As a third aspect of this application, this application also provides a charging system for a lithium-ion battery, comprising:

[0357] A charging device for cyclically charging lithium-ion batteries according to a charging regime; and

[0358] The controller is communicatively connected to the charging device and is used to execute the lithium-ion battery charging method described above.

[0359] Specifically, the controller can be an electronic device.

[0360] Below, for reference Figure 10 This describes an electronic device according to embodiments of the present application. Figure 10 The diagram shown is a structural schematic of an electronic device provided in an embodiment of this application.

[0361] like Figure 10 As shown, the electronic device 600 includes one or more processors 601 and memory 602.

[0362] The processor 601 may be a central processing unit (CPU) or other form of processing unit with data processing and / or information execution capabilities, and may control other components in the electronic device 600 to perform desired functions.

[0363] The memory 601 may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, random access memory (RAM) and / or cache memory. The non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. One or more computer program information may be stored on the computer-readable storage medium, and the processor 601 may run the program information to implement the lithium-ion battery charging method or other desired functions described in the various embodiments of this application above.

[0364] In one example, the electronic device 600 may also include an input device 603 and an output device 604, which are interconnected via a bus system and / or other forms of connection mechanism (not shown).

[0365] The input device 603 may include, for example, a keyboard, a mouse, etc.

[0366] The output device 604 can output various information to the outside. The output device 604 may include, for example, a display, a communication network, and remote output devices connected thereto.

[0367] Of course, for the sake of simplicity, Figure 10 Only some of the components of the electronic device 600 relevant to this application are shown in this illustration; components such as buses, input / output interfaces, etc., are omitted. In addition, the electronic device 600 may include any other suitable components depending on the specific application.

[0368] In addition to the methods and devices described above, embodiments of this application may also be computer program products, which include computer program information that, when run by a processor, causes the processor to perform the steps in the lithium-ion battery charging methods according to various embodiments of this application as described in this specification.

[0369] The computer program product can be written in any combination of one or more programming languages ​​to perform the operations of the embodiments of this application. The programming languages ​​include object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computing device, partially on the user's computing device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0370] Furthermore, embodiments of this application may also be computer-readable storage media storing computer program information thereon, which, when run by a processor, causes the processor to perform the steps in the charging methods for lithium-ion batteries according to various embodiments of this application.

[0371] The computer-readable storage medium may be any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may, for example, include, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or devices, or any combination thereof. More specific examples of readable storage media (a non-exhaustive list) include: electrical connections having one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0372] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0373] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0374] It should also be noted that in the apparatus, equipment, and methods of this application, the components or steps can be disassembled and / or recombined. Such disassembly and / or recombination should be considered as equivalent to the present application.

[0375] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be carried out within the widest scope consistent with the principles and novel features of the invention herein.

[0376] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Any modifications or equivalent substitutions made within the spirit and principles of the present application shall be included within the protection scope of the present application.

Claims

1. A method for charging a lithium-ion battery, characterized in that, include: S1: Charge the lithium-ion battery to the calibrated charging voltage using a first preset charging regime to determine the calibrated charging cycle capacity C0 of the lithium-ion battery. as well as S2: The lithium-ion battery is charged to its first preset charging cycle capacity using a second preset charging regime until charging stops, thereby determining the first preset charging cycle capacity C of the lithium-ion battery. i , Wherein, the first preset charging cycle capacity is equal to α C0, where α is 50%~110%; Where i is an integer greater than or equal to 1; Before the charging is stopped when the lithium-ion battery is charged to the first preset charging cycle capacity using the second preset charging regime, S2 further includes: S210: Charge the lithium-ion battery to the first preset voltage using a constant current charging method with a first preset current, and then charge the lithium-ion battery with a constant voltage method; to determine the first charge cycle capacity C1 and the first discharge cycle capacity D1 of the lithium-ion battery. S211: Charge the lithium-ion battery to a first preset voltage using a constant current charging method with a first preset current, and then charge the lithium-ion battery using a constant voltage method; to determine the i-th charge cycle capacity C of the lithium-ion battery. i ; S212: Determine C i Whether it is less than γ times the calibrated charging cycle capacity C0, where γ is 80%~100%; When C i When the value is less than γ times the calibrated charging cycle capacity C0, the lithium-ion battery is charged for the (i+1)th time to the first preset voltage using a first preset constant current charging method, and then charged to the first preset charging cycle capacity using a constant voltage method until charging is stopped; thus, the (i+1)th charging cycle capacity C of the lithium-ion battery is determined. i+1 .

2. The charging method according to claim 1, characterized in that, S2 include: S22: Charge the lithium-ion battery to the first preset voltage for the (i+1)th time using a first preset current constant current charging, and then charge the lithium-ion battery to the first preset charging cycle capacity using a constant voltage until charging is stopped. To determine the capacity C of the lithium-ion battery in the (i+1)th charging cycle. i+1 .

3. The charging method according to claim 2, characterized in that, S1 includes: The lithium-ion battery is charged to a third preset voltage using a first preset charging regime to determine the rated charging cycle capacity C0 of the lithium-ion battery. Wherein, the calibrated charging voltage is the rated charging voltage of the lithium-ion battery, and the third preset voltage is less than the rated charging voltage of the lithium-ion battery.

4. The charging method according to claim 2, characterized in that, The charging cut-off current is less than or equal to 0.02C, or the charging cut-off current is less than or equal to a preset cut-off current, wherein the preset cut-off current is the cut-off current when the lithium-ion battery is charged to β times its standard charge cycle capacity under standard charging conditions, where β is 100%-110%; and / or The charging cutoff voltage at which charging is cut off is less than or equal to the first preset voltage.

5. The charging method according to claim 2, characterized in that, The first preset voltage is greater than the rated charging voltage of the lithium-ion battery.

6. The charging method according to claim 2, characterized in that, The first preset voltage is equal to the rated charging voltage of the lithium-ion battery.

7. The charging method according to claim 6, characterized in that, S22 includes: S225: The lithium-ion battery is charged for the (i+1)th time to its rated charging voltage using a first preset constant current charging method, then charged to the first preset charging cycle capacity using a constant voltage method until charging is stopped, and then charged a second time to a third preset cycle capacity, wherein the difference between the third preset cycle capacity and the calibrated charging cycle capacity C0 is greater than 0; thus determining the (i+1)th charging cycle capacity C of the lithium-ion battery. i+1 .

8. The charging method according to claim 1, characterized in that, The calibrated charging voltage is less than or equal to the rated charging voltage of the lithium-ion battery.

9. The charging method according to claim 1, characterized in that, When C i When the value is greater than or equal to γ ​​times the calibrated charging cycle capacity C0, the lithium-ion battery is charged to the first preset voltage using a first preset constant current charging method, and then charged to the first preset voltage using a constant voltage method; thus determining the (i+1)th charging cycle capacity C of the lithium-ion battery. i+1 .

10. The charging method according to claim 1, characterized in that, S2 includes: S26: The lithium-ion battery is charged for the first time to the rated charging voltage of the lithium-ion battery using a constant current charging with a second preset current, and then the lithium-ion battery is charged to the first preset charging cycle capacity using a constant voltage charging, and the charging is stopped. To determine the first charge cycle capacity C1 of the lithium-ion battery; wherein, the charging cutoff current for the first charge cycle is α. I0, where I0 is the charging cutoff current in the first preset charging system; S27: Charge the lithium-ion battery with a second preset constant current to the rated charging voltage of the lithium-ion battery for the (i+1)th time, and then charge the lithium-ion battery with a constant voltage until the charging is stopped when the first preset charging cycle capacity is reached; thereby determining the (i+1)th charging cycle capacity C of the lithium-ion battery. i+1 The charging cutoff current for the (i+1)th charging cycle is I. f Among them, I f =θ f I0; where f is the quotient of (i+1) and 100, rounded down and then incremented by 1; Where, θ f+1 Greater than θ f .

11. The charging method according to claim 1, characterized in that, S2 include: S28: The lithium-ion battery is charged to the second preset voltage for the first time using a constant current charging with a third preset current, and then the lithium-ion battery is charged to the first preset charging cycle capacity using a constant voltage charging with a constant voltage charging, at which point the charging is stopped. To determine the first charge cycle capacity C1 of the lithium-ion battery; wherein, the second preset voltage for the first charge cycle is α. V0, where V0 is the rated charging voltage of the lithium-ion battery; S29: Charge the lithium-ion battery with a third preset current constant current to the second preset voltage for the (i+1)th time, then charge it with a constant voltage until the first preset charging cycle capacity is reached, at which point charging is stopped; thus determining the (i+1)th charging cycle capacity C of the lithium-ion battery. i+1 The second preset voltage for the (i+1)th charging cycle is V. f V f =η f V0, where f is the quotient of (i+1) and 100, rounded down and then incremented by 1; Where, η f+1 Greater than η f .

12. The charging method according to claim 1, characterized in that, Where α is 80%~100%.

13. A method for charging and discharging a lithium-ion battery, characterized in that, include: S4: The lithium-ion battery is charged for the jth time using the charging method according to any one of claims 1-12; S5: Discharge the lithium-ion battery for the jth time using a first preset discharge regime until the first preset discharge cycle capacity is reached, then discharge is stopped, to determine the charging cycle capacity C of the lithium-ion battery for the jth charge-discharge cycle. j and discharge cycle capacity D j ; Where j is an integer greater than or equal to 1.

14. The charging and discharging method according to claim 13, characterized in that: Prior to S4, the charging and discharging method further includes: The lithium-ion battery is charged to a calibrated charging voltage using a calibrated charging regime and discharged using a calibrated discharging regime to determine the calibrated charging cycle capacity C0 and the calibrated discharging cycle capacity D0 of the lithium-ion battery. Wherein, the first preset discharge cycle capacity is equal to ε D0, where ε is 50%~110%.

15. The charging and discharging method according to claim 14, characterized in that, S5 include: S51: Discharge the lithium-ion battery for the (j+1)th time to the first preset discharge cycle capacity using a first preset discharge current, and then cut off the discharge to determine the (j+1)th discharge cycle capacity D of the lithium-ion battery. i+1 .

16. The charging and discharging method according to claim 15, characterized in that, Prior to S51, S5 also included: S510: Discharge the lithium-ion battery to the rated discharge voltage for the first time using the second preset discharge current to determine the first discharge cycle capacity D1 of the lithium-ion battery; S512: Discharge the lithium-ion battery to the rated discharge voltage using a second preset discharge current for the j-th time, to determine the j-th discharge cycle capacity D of the lithium-ion battery. j ; S513: Determine D j Whether it is less than μ times the calibrated discharge cycle capacity D0, where μ is 50%~110%; When D j When the discharge cycle capacity is less than μ times the calibrated discharge cycle capacity D0, the lithium-ion battery is discharged for the (j+1)th time with a first preset discharge current until the discharge stops at the first preset discharge cycle capacity, thereby determining the (j+1)th discharge cycle capacity D of the lithium-ion battery. j+1 .

17. The charging and discharging method according to claim 14, characterized in that, S5 include: S53: The lithium-ion battery is discharged for the first time at a first preset discharge current until the first preset discharge cycle capacity is reached, at which point the discharge is cut off; thus, the first discharge cycle capacity D1 of the lithium-ion battery is determined; wherein, the discharge cutoff voltage of the first cycle discharge is ε. V0, where V0 is the discharge cutoff voltage during the discharge under the calibrated discharge regime; S54: Discharge the lithium-ion battery for the (j+1)th time with a second preset current until the first preset discharge cycle capacity is reached, then discharge is stopped; thus determining the (j+1)th discharge cycle capacity D of the lithium-ion battery. j+1 The discharge cutoff voltage for the (j+1)th cycle discharge is V. f Among them, V f =w f V0; where f is the quotient of (j+1) and 100, rounded down and then incremented by 1; Among them, w f+1 Greater than w f .

18. A charging system for a lithium-ion battery, characterized in that, include: A charging device for cyclically charging the lithium-ion battery according to a charging regime; as well as A controller, which is communicatively connected to the charging device, is used to execute the charging method for the lithium-ion battery according to any one of claims 1-12.

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