A battery charging and discharging method

Abstract

The present invention discloses a battery charging and discharging method, comprising: performing a charge and discharge cycle on the battery at room temperature; performing a charge and discharge cycle on the battery at a high temperature; returning to the step of performing a charge and discharge cycle on the battery at room temperature to start the next temperature alternating cycle. The battery charging and discharging method provided by the present invention improves the battery charge and discharge cycle from a single temperature to alternating at two different temperatures, room temperature and high temperature, so that the formation of an excessively thick SEI layer can be avoided and the decomposition and gas generation of the electrolyte can be greatly reduced, thereby improving the battery cycle performance and having broad market application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion batteries, and in particular to a battery charging and discharging method. Background Art

[0002] Carbon-based materials, represented by graphite, are the main materials used in the negative electrode of lithium-ion batteries, which directly affect the electrochemical performance of lithium-ion batteries. As people's requirements for the energy density of lithium-ion batteries continue to increase, the application of silicon-based materials has received great attention and development.

[0003] Silicon is widely distributed in nature and is one of the most abundant elements in the earth's crust. The theoretical specific capacity of silicon is as high as 4200 mAh / g, which is more than 10 times the theoretical specific capacity of graphite (372 mAh / g), and can greatly improve the energy density of lithium-ion batteries.

[0004] However, the problem with silicon-based materials as negative electrode materials for lithium-ion batteries is that when charging and discharging at room temperature, the volume of silicon-based materials changes greatly during the process of lithium insertion and extraction, which causes the active material to pulverize and a new solid electrolyte layer (SEI) to be repeatedly generated. The SEI layer formed at this time is relatively thick, which consumes a large amount of active lithium, resulting in a decrease in the conductivity of the battery, deterioration of the kinetics, and ultimately a rapid decline in the battery's cycle performance. When charging and discharging at high temperatures, the battery's kinetics are better, and the SEI layer can be partially dissolved while being formed, so the SEI layer formed is relatively thin, but the high temperature exacerbates the decomposition of the electrolyte, resulting in an increase in gas production, which ultimately leads to a rapid decline in the battery's cycle performance.

[0005] Therefore, it is necessary to improve the existing technology.

[0006] The above information is presented as background information only to assist with understanding the present disclosure and no determination or admission is made as to whether any of the above may be used as prior art with respect to the present disclosure. Summary of the invention

[0007] The present invention provides a battery charging and discharging method to solve the problem in the prior art that the battery cycle performance rapidly decays when the battery is charged and discharged at a single temperature.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] In a first aspect, the present invention provides a battery charging and discharging method, the method comprising:

[0010] At room temperature, the battery is charged and discharged in cycles;

[0011] At an elevated temperature, subjecting the battery to a charge-discharge cycle;

[0012] Return to the step of performing a charge and discharge cycle on the battery at room temperature to start the next temperature alternation cycle.

[0013] Furthermore, in the battery charging and discharging method, the normal temperature is lower than the high temperature, and the difference between the high temperature and the normal temperature is higher than a set value.

[0014] Further, in the battery charging and discharging method, the normal temperature ranges from 18 to 30°C;

[0015] The high temperature range is 45-60°C;

[0016] The set point is 25°C.

[0017] Furthermore, in the battery charging and discharging method, the step of performing a charge and discharge cycle on the battery at room temperature is:

[0018] At room temperature, the battery is charged and discharged for M cycles, where M is a positive number;

[0019] The steps of charging and discharging the battery at a high temperature are as follows:

[0020] At a high temperature, the battery is charged and discharged for N cycles, where N is a positive number.

[0021] Furthermore, in the battery charging and discharging method, the M is greater than the N, and the M and the N satisfy a set relationship.

[0022] Further, in the battery charging and discharging method, the range of M is 20-300;

[0023] The range of N is 5-30;

[0024] The set relationship is M>5N.

[0025] Furthermore, in the battery charging and discharging method, the step of performing a charge and discharge cycle M times on the battery at room temperature, where M is a positive number, comprises:

[0026] At room temperature, charge the battery at a fixed charging rate and charge to the upper voltage limit;

[0027] Allow the battery to stand still, and then discharge the battery at a fixed discharge rate until the battery is discharged to a lower voltage limit;

[0028] Return to the step of charging the battery at a fixed charging rate at room temperature and charging to the voltage upper limit to start the next charge and discharge cycle until M cycles are completed, where M is a positive number.

[0029] Furthermore, in the battery charging and discharging method, the step of performing a charge and discharge cycle M times on the battery at room temperature, where M is a positive number, comprises:

[0030] At room temperature, the battery is step-charged at different charging rates until it reaches the upper voltage limit;

[0031] Allow the battery to stand still, and then discharge the battery at a fixed discharge rate until the battery is discharged to a lower voltage limit;

[0032] Return to the step of performing step-charging on the battery at different charging rates at room temperature until the voltage upper limit is charged, so as to start the next charge and discharge cycle, until the cycle is M, where M is a positive number.

[0033] Furthermore, in the battery charging and discharging method, the step of performing a charge and discharge cycle N times on the battery at a high temperature, where N is a positive number, comprises:

[0034] At high temperature, the battery is charged at a fixed charging rate and charged to the upper voltage limit;

[0035] Allow the battery to stand still, and then discharge the battery at a fixed discharge rate until the battery is discharged to a lower voltage limit;

[0036] Return to the step of charging the battery at a fixed charging rate at a high temperature and charging to an upper voltage limit to start the next charge and discharge cycle until the cycle is N, where N is a positive number.

[0037] Furthermore, in the battery charging and discharging method, the step of performing a charge and discharge cycle N times on the battery at a high temperature, where N is a positive number, comprises:

[0038] At high temperature, the battery is step-charged at different charging rates until it reaches the upper voltage limit;

[0039] Allow the battery to stand still, and then discharge the battery at a fixed discharge rate until the battery is discharged to a lower voltage limit;

[0040] Return to the step of performing step-charging on the battery at different charging rates at a high temperature until the voltage is charged to the upper limit, so as to start the next charge and discharge cycle, until the cycle is N, where N is a positive number.

[0041] In a second aspect, the present invention provides a battery module, comprising a battery body and a battery management unit connected to the battery body, wherein the battery management unit charges and discharges the battery body using the battery charging and discharging method described in the first aspect.

[0042] In a third aspect, the present invention provides a battery pack, comprising the battery module as described in the second aspect above.

[0043] In a fourth aspect, the present invention provides a power supply device, comprising the battery module as described in the second aspect or the battery pack as described in the third aspect.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The present invention provides a battery charging and discharging method, which improves the battery's cycle performance by improving the battery's charge and discharge cycle from being performed at a single temperature to being performed alternately at two different temperatures, normal temperature and high temperature, thereby avoiding the formation of an excessively thick SEI layer and significantly reducing the decomposition and gas generation of the electrolyte, and having broad market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0047] Figure 1 It is a flowchart of a battery charging and discharging method provided in Embodiment 1 of the present invention;

[0048] Figure 2 This is a cross-sectional electron microscope image of a lithium-ion battery containing a silicon-based negative electrode material when performing charge and discharge cycles at a room temperature of 25° C. during the comparative group 1 experiment in Example 1 of the present invention;

[0049] Figure 3 This is a cross-sectional electron microscope image of a lithium-ion battery containing a silicon-based negative electrode material during charge and discharge cycles at alternating temperatures of 25° C. and 60° C. during the experiment of Experiment Group 1 of Example 1 of the present invention. DETAILED DESCRIPTION

[0050] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] In the description of the present invention, it is to be understood that when a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a centrally disposed component. When a component is considered to be "disposed on" another component, it may be directly disposed on the other component or there may be a centrally disposed component.

[0052] In addition, terms such as "long", "short", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings and are only used to facilitate the description of the present invention. They do not indicate or imply that the device or component referred to must have this specific direction or operate with a specific direction structure, and should not be understood as a limitation of the present invention.

[0053] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods. Example

[0054] In view of the defects of the above-mentioned existing lithium-ion battery charging and discharging technology containing silicon-based negative electrode materials, the applicant, based on many years of rich practical experience and professional knowledge in the design and manufacture of such products, and in conjunction with the application of theory, actively conducts research and innovation in the hope of creating a technology that can solve the defects in the existing technology and make the lithium-ion battery charging and discharging technology containing silicon-based negative electrode materials more practical. After continuous research and design, and after repeated trial samples and improvements, the present invention with real practical value was finally created.

[0055] Please refer to Figure 1 , Figure 1 This is a flow chart of a battery charging and discharging method provided in Embodiment 1 of the present invention. The method is applicable to charging and discharging a lithium-ion battery containing a silicon-based negative electrode material. The method can be implemented by software and / or hardware, and specifically includes the following steps:

[0056] S100, performing charge and discharge cycles on the battery at room temperature.

[0057] It should be noted that the battery is a lithium-ion battery containing silicon-based negative electrode materials. Silicon-based materials include silicon-oxygen materials, metal-doped silicon-oxygen materials, nano-silicon composite carbon materials, etc.

[0058] The range of the normal temperature is 18-30° C., that is, in this embodiment, any temperature within the temperature range of 18-30° C. can be selected as the normal temperature, and then the battery is cycled in a charge-discharge-recharge-redischarge cycle at the selected temperature.

[0059] S200, performing charge and discharge cycles on the battery at a high temperature.

[0060] It should be noted that the high temperature ranges from 45 to 60°C, that is, in this embodiment, any temperature within the temperature range of 45 to 60°C can be selected as the high temperature, and then the battery is charged-discharged-recharged-redischarged at the selected temperature in the same manner as the battery at room temperature.

[0061] It should be added that although both the normal temperature and the high temperature can be indefinite values, there are conditions that need to be met when the normal temperature and the high temperature are taken. Specifically, the normal temperature needs to be lower than the high temperature, and the difference between the high temperature and the normal temperature is greater than the set value.

[0062] The set value can be set arbitrarily by technicians according to experience and actual application scenarios. This embodiment does not specifically limit it, but for example, the set value can be 25° C. That is, when the value of the normal temperature is 20° C., the value of the high temperature must be 45° C. or above.

[0063] S300, start the next temperature alternation cycle, and return to step S100.

[0064] It should be noted that the charge and discharge settings of the battery in this embodiment are performed alternately at two different temperatures, room temperature and high temperature, and it can be seen that this embodiment clearly states that the first charge and discharge of the battery needs to be performed at room temperature, and then the normal temperature-high temperature-normal temperature-high temperature cycle can be performed. This is because if the first charge and discharge of the battery is performed at a high temperature, the decay of the battery's cycle performance is much greater than the decay of the battery's cycle performance when the battery is first charged and discharged at room temperature, resulting in the inability to perform alternate charge and discharge cycles at different temperatures.

[0065] In this embodiment, the step S100 can be further refined into the following steps: at room temperature, the battery is charged and discharged for M cycles, where M is a positive number;

[0066] In this embodiment, the step S200 can be further refined into the following steps: performing a charge and discharge cycle N times on the battery at a high temperature, where N is a positive number.

[0067] Wherein, the M is greater than the N, and the M and the N satisfy a set relationship.

[0068] It should be noted that the range of M is 20-300, that is, in this embodiment, any number of cycles within the range of 20-300 can be selected as the number of normal temperature charge and discharge cycles, and then the battery can be charged-discharged-recharged-redischarged at normal temperature for the selected number of cycles.

[0069] Similarly, the range of N is 5-30, that is, in this embodiment, any number of cycles within the range of 5-30 can be selected as the high-temperature charge and discharge cycle number, and then the battery can be charged-discharged-recharged-redischarged at high temperature for the selected number of cycles.

[0070] It should be added that although both M and N can be indefinite values, there are conditions that need to be met when M and N take their respective values, that is, they need to satisfy a set relationship. Therefore, when the value of M is determined, the value of N is also determined accordingly. Conversely, when the value of N is determined, the value of M is also determined accordingly.

[0071] The set relationship can be arbitrarily set by technicians based on experience and actual application scenarios. This embodiment does not specifically limit this, but for example, the set relationship can be M>5N. That is, when the value of M is 30, the value of N must be less than 6.

[0072] As mentioned in the background technology, the conventional cycles of battery charging and discharging are all carried out at a single temperature, and whether it is cycled at room temperature, such as around 18-30°C, or at a higher temperature, such as 45-60°C, the battery cycle performance is not satisfactory. Therefore, in view of the different principles of cycle performance degradation of lithium-ion batteries containing silicon-based negative electrode materials at room temperature and high temperature, the applicant designed a temperature alternating battery charging and discharging method, that is, allowing the battery to be charged and discharged for a certain period of time at room temperature, then charged and discharged for a certain period of time at high temperature, and then charged and discharged for a certain period of time at room temperature, so that the cycle can avoid the formation of an excessively thick SEI layer and greatly reduce the decomposition and gas production of the electrolyte, thereby improving the battery cycle performance.

[0073] In this embodiment, there are many ways to implement the battery charging and discharging, such as constant rate charging or step charging. These two charging and discharging methods are introduced as examples below.

[0074] At room temperature:

[0075] In the first embodiment, the step of performing a charge and discharge cycle M times on the battery at room temperature, where M is a positive number, can be further refined to include the following steps:

[0076] At room temperature, charge the battery at a fixed charging rate and charge to the upper voltage limit;

[0077] Allow the battery to stand still, and then discharge the battery at a fixed discharge rate until the battery is discharged to a lower voltage limit;

[0078] Return to the step of charging the battery at a fixed charging rate at room temperature and charging to the voltage upper limit to start the next charge and discharge cycle until M cycles are completed, where M is a positive number.

[0079] In a second embodiment, the step of performing a charge and discharge cycle M times on the battery at room temperature, where M is a positive number, can be further refined to include the following steps:

[0080] At room temperature, the battery is step-charged at different charging rates until it reaches the upper voltage limit;

[0081] Allow the battery to stand still, and then discharge the battery at a fixed discharge rate until the battery is discharged to a lower voltage limit;

[0082] Return to the step of performing step-charging on the battery at different charging rates at room temperature until the voltage upper limit is charged, so as to start the next charge and discharge cycle, until the cycle is M, where M is a positive number.

[0083] It should be noted that a fixed discharge rate means that the battery is always charged at a certain charging rate, such as charging the battery at a charging rate of 1C, or charging the battery at a rate of 0.5C; different charging rates means charging the battery at multiple different charging rates at different times, such as first charging the battery at a charging rate of 1C, and then charging the battery at a rate of 0.5C.

[0084] Similarly, at high temperatures:

[0085] In the first embodiment, the step of performing N cycles of charge and discharge on the battery at a high temperature, where N is a positive number, can be further refined to include the following steps:

[0086] At high temperature, the battery is charged at a fixed charging rate and charged to the upper voltage limit;

[0087] Allow the battery to stand still, and then discharge the battery at a fixed discharge rate until the battery is discharged to a lower voltage limit;

[0088] Return to the step of charging the battery at a fixed charging rate at a high temperature and charging to an upper voltage limit to start the next charge and discharge cycle until the cycle is N, where N is a positive number.

[0089] In a second embodiment, the step of performing a charge and discharge cycle of N cycles on the battery at a high temperature, where N is a positive number, can be further refined to include the following steps:

[0090] At high temperature, the battery is step-charged at different charging rates until it reaches the upper voltage limit;

[0091] Allow the battery to stand still, and then discharge the battery at a fixed discharge rate until the battery is discharged to a lower voltage limit;

[0092] Return to the step of performing step-charging on the battery at different charging rates at a high temperature until the voltage is charged to the upper limit, so as to start the next charge and discharge cycle, until the cycle is N, where N is a positive number.

[0093] In order to verify the feasibility of the solution provided in this embodiment, this embodiment conducted a comparative experiment. Next, four experimental groups and three comparative groups are introduced respectively.

[0094] Experimental group 1: The positive electrode is 8-series high-nickel material, and the negative electrode is lithium-doped silicon-oxygen material;

[0095] Temperature alternating charge and discharge cycle test process:

[0096] 1) Stand for 30 minutes @ (25 ± 2) ℃;

[0097] 2) 1C constant current discharge to 2.8V;

[0098] 3) Let stand for 15 minutes;

[0099] 4) 0.5C constant current charging to 4.25V, constant voltage charging at 4.25V to cut-off current ≤ 0.05C;

[0100] 5) Let stand for 15 minutes;

[0101] 6) 1C constant current discharge to 2.8V;

[0102] 7) Repeat 3) to 6) for 100 cycles;

[0103] 8) Stand for 2 hours @ (60 ± 2) ℃ (to ensure the battery cell temperature can reach 60 ℃);

[0104] 9) 1C constant current charging to 4.2V, constant voltage charging at 4.2V to cut-off current ≤ 0.05C;

[0105] 10) Let stand for 15 minutes;

[0106] 11) 1C constant current discharge to 2.5V;

[0107] 12) Let stand for 15 minutes;

[0108] 14) Repeat 9) to 12) for 10 weeks;

[0109] 15) Stand for 2 hours @ (25 ± 2) ℃ (to ensure the battery cell temperature returns to 25 ℃);

[0110] 16) Cycle 3) to 15) alternately at 25℃ and 60℃ until the capacity decays to 80%.

[0111] Experimental group 2: The positive electrode is 8-series high-nickel material, and the negative electrode is lithium-doped silicon-oxygen material;

[0112] Charge and discharge process temperature alternating cycle test process:

[0113] 1) Stand for 30 minutes @ (20 ± 2) ℃;

[0114] 2) 1C constant current discharge to 2.8V;

[0115] 3) Let stand for 15 minutes;

[0116] 4) 0.5C constant current charging to 4.25V, constant voltage charging at 4.25V to cut-off current ≤ 0.05C;

[0117] 5) Let stand for 15 minutes;

[0118] 6) 1C constant current discharge to 2.8V;

[0119] 7) Cycle 3) to 6) 200 times;

[0120] 8) Stand for 2 hours @ (60 ± 2) ℃ (to ensure the battery cell temperature can reach 60 ℃);

[0121] 9) 1C constant current charging to 4.2V, constant voltage charging at 4.2V to cut-off current ≤ 0.05C;

[0122] 10) Let stand for 15 minutes;

[0123] 11) 1C constant current discharge to 2.5V;

[0124] 12) Let stand for 15 minutes;

[0125] 14) Cycle 9) to 12) for 15 weeks;

[0126] 15) Stand for 2 hours @ (20 ± 2) ℃ (to ensure the battery cell temperature returns to 20 ℃);

[0127] 16) Cycle 3) to 15) alternately at 20℃ and 60℃ until the capacity decays to 80%.

[0128] Experimental group 3: The positive electrode is 8-series high-nickel material, and the negative electrode is lithium-doped silicon-oxygen material;

[0129] Temperature alternating charge and discharge cycle test process:

[0130] 1) Stand for 30 minutes @ (28 ± 2) ℃;

[0131] 2) 1C constant current discharge to 2.8V;

[0132] 3) Let stand for 15 minutes;

[0133] 4) 0.5C constant current charging to 4.25V, constant voltage charging at 4.25V to cut-off current ≤ 0.05C;

[0134] 5) Let stand for 15 minutes;

[0135] 6) 1C constant current discharge to 2.8V;

[0136] 7) Cycle 3) to 6) for 150 cycles;

[0137] 8) Stand for 2 hours @ (55 ± 2) ℃ (to ensure the battery cell temperature can reach 55 ℃);

[0138] 9) 1C constant current charging to 4.2V, constant voltage charging at 4.2V to cut-off current ≤ 0.05C;

[0139] 10) Let stand for 15 minutes;

[0140] 11) 1C constant current discharge to 2.5V;

[0141] 12) Let stand for 15 minutes;

[0142] 14) Cycle 9) to 12) for 20 weeks;

[0143] 15) Stand for 2 hours @ (28 ± 2) ℃ (to ensure the battery cell temperature returns to 28 ℃);

[0144] 16) Cycle 3) to 15) alternately at 28℃ and 55℃ until the capacity decays to 80%.

[0145] Experimental group 4: The positive electrode is 8-series high-nickel material, and the negative electrode is lithium-doped silicon-oxygen material;

[0146] Charge and discharge process temperature alternating cycle test process:

[0147] 1) Stand for 30 minutes @ (18 ± 2) ℃;

[0148] 2) 1C constant current discharge to 2.8V;

[0149] 3) Let stand for 15 minutes;

[0150] 4) 0.5C constant current charging to 4.25V, constant voltage charging at 4.25V to cut-off current ≤ 0.05C;

[0151] 5) Let stand for 15 minutes;

[0152] 6) 1C constant current discharge to 2.8V;

[0153] 7) Cycle 3) to 6) for 80 weeks;

[0154] 8) Stand for 2 hours @ (50 ± 2) ℃ (to ensure the battery cell temperature can reach 50 ℃);

[0155] 9) 1C constant current charging to 4.2V, constant voltage charging at 4.2V to cut-off current ≤ 0.05C;

[0156] 10) Let stand for 15 minutes;

[0157] 11) 1C constant current discharge to 2.5V;

[0158] 12) Let stand for 15 minutes;

[0159] 14) Cycle 9) to 12) for 8 weeks;

[0160] 15) Stand for 2 hours @ (18 ± 2) ℃ (to ensure the battery cell temperature returns to 18 ℃);

[0161] 16) Cycle 3) to 15) alternately at 18℃ and 50℃ until the capacity decays to 80%.

[0162] Comparative group 1: The positive electrode is 8-series high-nickel material, and the negative electrode is lithium-doped silicon-oxygen material;

[0163] 1) Stand for 30 minutes @ (25 ± 2) ℃;

[0164] 2) 1C constant current discharge to 2.8V;

[0165] 3) Let stand for 15 minutes;

[0166] 4) 0.5C constant current charging to 4.25V, constant voltage charging at 4.25V to cut-off current ≤ 0.05C;

[0167] 5) Let stand for 15 minutes;

[0168] 6) 1C constant current discharge to 2.8V;

[0169] 7) Repeat steps 3) to 6) until the capacity decays to 80%.

[0170] Comparative group 2: The positive electrode is 8-series high-nickel material, and the negative electrode is lithium-doped silicon-oxygen material;

[0171] 1) Stand for 30 minutes @ (45 ± 2) ℃;

[0172] 2) 1C constant current discharge to 2.8V;

[0173] 3) Let stand for 15 minutes;

[0174] 4) 0.5C constant current charging to 4.25V, constant voltage charging at 4.25V to cut-off current ≤ 0.05C;

[0175] 5) Let stand for 15 minutes;

[0176] 6) 1C constant current discharge to 2.8V;

[0177] 7) Repeat steps 3) to 6) until the capacity decays to 80%.

[0178] Comparative group 3: The positive electrode is 8 series high nickel material, and the negative electrode is lithium-doped silicon oxide material;

[0179] 1) Stand for 30 minutes @ (60 ± 2) ℃;

[0180] 2) 1C constant current discharge to 2.8V;

[0181] 3) Let stand for 15 minutes;

[0182] 4) 0.5C constant current charging to 4.25V, constant voltage charging at 4.25V to cut-off current ≤ 0.05C;

[0183] 5) Let stand for 15 minutes;

[0184] 6) 1C constant current discharge to 2.8V;

[0185] 7) Repeat steps 3) to 6) until the capacity decays to 80%.

[0186] For specific experimental results, please refer to the following Tables 1 and 2:

[0187] Table 1:

[0188] Temperature A Temperature B M N Cycles until capacity decays to 80% Experimental Group 1 25℃ 60℃ 100 10 1513 Experimental Group 2 20℃ 60℃ 200 15 1420 Experimental Group 3 28℃ 55℃ 150 20 1519 Experimental Group 4 18℃ 50℃ 80 8 1530

[0189] Table 2:

[0190] temperature Cycles until capacity decays to 80% Comparison group 1 25℃ 1210 Comparison group 2 45℃ 980 Comparison group 3 60℃ 513

[0191] It can be seen from the above two tables that compared with the control group, the number of cycles in which the battery capacity in the experimental group decays to 80% is much greater than that in the control group, which proves that the temperature alternating battery charge and discharge cycle method can significantly improve the battery cycle performance.

[0192] The specific results of the comparative experiment can be found in Figure 2 and Figure 3 , Figure 2 The figure shows the cross-sectional electron micrograph of the lithium-ion battery containing silicon-based negative electrode materials when it is charged and discharged at room temperature of 25°C during the comparative group 1 experiment. Figure 2 It can be seen that the thickness of the SEI layer formed at this time is relatively large, about 1.0um; Figure 3 The figure shows the cross-sectional electron micrograph of the lithium-ion battery containing silicon-based negative electrode materials during the charge and discharge cycle at alternating temperatures of 25°C and 60°C during the experiment of Experiment Group 1. Figure 3 It can be seen that the thickness of the SEI layer formed at this time is relatively small, about 0.5um.

[0193] The present invention provides a battery charging and discharging method, which improves the battery's cycle performance by improving the battery's charge and discharge cycle from being performed at a single temperature to being performed alternately at two different temperatures, normal temperature and high temperature, thereby avoiding the formation of an excessively thick SEI layer and significantly reducing the decomposition and gas generation of the electrolyte, and having broad market application prospects. Example

[0194] An embodiment of the present invention provides a battery module, including a battery body and a battery management unit connected to the battery body, wherein the battery management unit charges and discharges the battery body using the battery charging and discharging method described in the first embodiment.

[0195] A battery module provided by the present invention improves the battery's charge and discharge cycle from being performed at a single temperature to being performed alternately at two different temperatures, normal temperature and high temperature, so that the formation of an excessively thick SEI layer can be avoided and the decomposition and gas production of the electrolyte can be greatly reduced, thereby improving the battery's cycle performance and having broad market application prospects. Example

[0196] An embodiment of the present invention provides a battery pack, comprising the battery module as described in the above-mentioned embodiment 2.

[0197] It should be noted that the battery should also include necessary component designs such as a casing and a bus. The specific function of these component designs is to ensure the normal operation of various functions of the battery pack. In view of the fact that these component designs have been implemented in many existing technologies and are not the focus of the design of this solution, they will not be elaborated in depth here.

[0198] A battery pack provided by the present invention improves the battery's cycle performance by improving the battery's charge and discharge cycle from being performed at a single temperature to being performed alternately at two different temperatures, normal temperature and high temperature, thereby avoiding the formation of an excessively thick SEI layer and significantly reducing the decomposition and gas production of the electrolyte, thereby improving the battery's cycle performance and having broad market application prospects. Example

[0199] An embodiment of the present invention provides a power supply device, comprising the battery module as described in the above-mentioned embodiment 2 or the battery pack as described in the above-mentioned embodiment 3.

[0200] The power supply device in this embodiment can be applied to electronic devices such as electronic devices, electric vehicles or power storage systems, but is not limited thereto. The electronic device can be, for example, various computers, mobile phones, display screens and other devices that use the power supply device as a driving power source. The electric vehicle can be, for example, an electric car, an electric tricycle, an electric bicycle, etc. that use the power supply device as a driving power source. The power storage system can be, for example, a power storage system that uses the power supply device as a power storage source.

[0201] In these electronic devices, the power supply device can be electrically connected to the electrical components to provide electrical energy to the electrical components. Since the power supply device provided in this application has excellent fast charging capability, it is beneficial for electronic devices to be used in application scenarios such as outdoor energy storage, short-term backup power, and mobile energy storage, thereby making the application scenarios of electronic devices more extensive.

[0202] The power supply device provided by the present invention improves the battery's cycle performance by improving the battery's charge and discharge cycle from being performed at a single temperature to being performed alternately at two different temperatures, normal temperature and high temperature, thereby avoiding the formation of an excessively thick SEI layer and significantly reducing the decomposition and gas generation of the electrolyte, thereby improving the battery's cycle performance and having broad market application prospects.

[0203] In summary, after reading this detailed disclosure, it will be apparent to those skilled in the art that the aforementioned detailed disclosure may be presented only by way of example and may not be restrictive. Although not explicitly stated herein, it will be appreciated by those skilled in the art that this application is intended to encompass various reasonable changes, improvements and modifications to the embodiments. These changes, improvements and modifications are intended to be proposed by this application and are within the spirit and scope of the exemplary embodiments of this application.

[0204] In addition, certain terms in this application have been used to describe embodiments of the present application. For example, "one embodiment", "embodiment" and / or "some embodiments" mean that a particular feature, structure or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. Therefore, it can be emphasized and should be understood that two or more references to "embodiment" or "one embodiment" or "alternative embodiment" in various parts of this specification do not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics may be appropriately combined in one or more embodiments of the present application.

[0205] It should be understood that in the foregoing description of the embodiments of the present application, in order to help understand a feature and for the purpose of simplifying the present application, the present application combines various features in a single embodiment, drawing or its description. However, this does not mean that the combination of these features is necessary. When reading the present application, it is entirely possible for a person skilled in the art to extract some of the features and understand them as separate embodiments. In other words, the embodiments in the present application can also be understood as the integration of multiple secondary embodiments. This is also true when the content of each secondary embodiment is less than all the features of a single aforementioned disclosed embodiment.

[0206] Each patent, patent application, patent application publication, and other materials, such as articles, books, specifications, publications, documents, articles, etc., cited herein may be incorporated herein by reference in its entirety for all purposes, except for any prosecution document history related thereto, any equivalent that may be inconsistent or conflicting with this document, or any equivalent prosecution document history that may have a limiting effect on the broadest scope of the claims now or later associated with this document. For example, if there is any inconsistency or conflict between the description, definition, and / or use of a term associated with any of the incorporated materials and the term, description, definition, and / or use associated with this document, the term in this document shall control.

[0207] Finally, it should be understood that the embodiments of the application disclosed herein are explanations of the principles of the embodiments of the present application. Other modified embodiments are also within the scope of the present application. Therefore, the embodiments disclosed in the present application are merely examples and not limitations. Those skilled in the art can adopt alternative configurations according to the embodiments in the present application to implement the application in the present application. Therefore, the embodiments of the present application are not limited to the embodiments accurately described in the application.

Claims

1. A battery charging and discharging method, characterized in that: The battery is a lithium-ion battery, and the method comprises: At room temperature, the battery is charged and discharged in cycles; At an elevated temperature, subjecting the battery to a charge-discharge cycle; Returning to the step of performing a charge and discharge cycle on the battery at room temperature to start the next temperature alternation cycle; The step of performing a charge-discharge cycle on the battery at room temperature is as follows: performing a charge-discharge cycle on the battery at room temperature for M cycles, where M is a positive number; The step of performing a charge-discharge cycle on the battery at a high temperature is: performing a charge-discharge cycle on the battery at a high temperature for N cycles, where N is a positive number; The M is greater than the N, and the M and the N satisfy a set relationship; The range of M is 20-300; the range of N is 5-30; and the setting relation is M>5N.

2. The battery charging and discharging method according to claim 1, characterized in that: The normal temperature is lower than the high temperature, and a difference between the high temperature and the normal temperature is greater than a set value.

3. The battery charging and discharging method according to claim 2, characterized in that: The normal temperature range is 18-30°C; The high temperature range is 45-60°C; The set point is 25°C.

4. The battery charging and discharging method according to claim 1, characterized in that: The step of performing a charge and discharge cycle M times on the battery at room temperature, where M is a positive number, comprises: At room temperature, charge the battery at a fixed charging rate and charge to the upper voltage limit; Allow the battery to stand still, and then discharge the battery at a fixed discharge rate until the battery is discharged to a lower voltage limit; Return to the step of charging the battery at a fixed charging rate at room temperature and charging to the voltage upper limit to start the next charge and discharge cycle until M cycles are completed, where M is a positive number.

5. The battery charging and discharging method according to claim 1, characterized in that: The step of performing a charge and discharge cycle M times on the battery at room temperature, where M is a positive number, comprises: At room temperature, the battery is step-charged at different charging rates until it reaches the upper voltage limit; Allow the battery to stand still, and then discharge the battery at a fixed discharge rate until the battery is discharged to a lower voltage limit; Return to the step of performing step-charging on the battery at different charging rates at room temperature until the voltage upper limit is charged, so as to start the next charge and discharge cycle, until the cycle is M, where M is a positive number.

6. The battery charging and discharging method according to claim 1, characterized in that: The step of performing a charge and discharge cycle of N cycles on the battery at a high temperature, where N is a positive number, comprises: At high temperature, the battery is charged at a fixed charging rate and charged to the upper voltage limit; Allow the battery to stand still, and then discharge the battery at a fixed discharge rate until the battery is discharged to a lower voltage limit; Return to the step of charging the battery at a fixed charging rate at a high temperature and charging to an upper voltage limit to start the next charge and discharge cycle until the cycle is N, where N is a positive number.

7. The battery charging and discharging method according to claim 1, characterized in that: The step of performing a charge and discharge cycle of N cycles on the battery at a high temperature, where N is a positive number, comprises: At high temperature, the battery is step-charged at different charging rates until it reaches the upper voltage limit; Allow the battery to stand still, and then discharge the battery at a fixed discharge rate until the battery is discharged to a lower voltage limit; Return to the step of performing step-charging on the battery at different charging rates at a high temperature until the voltage is charged to the upper limit, so as to start the next charge and discharge cycle, until the cycle is N, where N is a positive number.

8. A battery module, comprising a battery body and a battery management unit connected to the battery body, characterized in that: The battery management unit charges and discharges the battery body using a battery charging and discharging method as described in any one of claims 1-7.

9. A battery pack, characterized in that: Comprising the battery module as claimed in claim 8.

10. A power supply device, characterized in that: Comprising the battery module as claimed in claim 8 or the battery pack as claimed in claim 9.

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