Charging method and related equipment

Abstract

The invention discloses a charging method and related equipment, and belongs to the technical field of batteries. Based on different lithium embedding amounts of the first active material and the second active material in different charge state stages of the mixed negative electrode battery, the contribution proportions of the first active material and the second active material in the battery in different charge state stages are decomposed, so that reasonable charging rates are distributed to different charge state intervals; meanwhile, compared with a second active material, the first active material is easier to lose due to high-rate charging, so that the rate of a charge state interval of leading lithium insertion of the first active material is reduced; and the multiplying power of the charge state interval of the second active material leading intercalation lithium and the multiplying power of the charge state interval of the first active material and the second active material coacting intercalation lithium are increased, so that the cycle expansion of the battery can be reduced and the cycle capacity retention ratio of the battery can be improved on the premise of not influencing the charging speed, and the cycle life of the battery is further prolonged.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a charging method, a battery, an electronic device, a computer program product, and a storage medium. Background Art

[0002] In recent years, lithium-ion batteries using silicon and graphite as negative electrode active materials have been initially applied in the market. Due to the low conductivity of silicon and the alloying lithium insertion and extraction mechanism, the problems of volume expansion and capacity attenuation during the cycle are still major challenges.

[0003] Currently, mainstream battery products in the consumer and power battery sectors mostly utilize high-rate, high-voltage step charging to achieve fast charging of lithium batteries. Compared to graphite, silicon active material particles face a more severe problem of uneven lithium intercalation concentration distribution when charging at high charge rates. This leads to stress concentration at the reaction interface of the silicon active material particles, causing particle damage and repeated side reaction consumption. Ultimately, this increases the consumption of active lithium and silicon materials, leading to rapid capacity decay and expansion growth of lithium batteries. As the silicon content of negative electrode active materials continues to increase, the life degradation problem caused by this charging system will become more prominent.

[0004] Therefore, it is urgent to develop a more reasonable charging strategy that can protect and improve the recycling of silicon materials, reduce the expansion growth rate and capacity attenuation rate, and achieve better cycle performance while achieving fast charging. Summary of the Invention

[0005] The purpose of this application is to provide a charging method, a battery, an electronic device, a computer program product and a storage medium, so as to improve the problem of insufficient cycle life in the related technologies of high-rate charging of silicon and graphite batteries.

[0006] To achieve the above objectives, the present application provides a charging method, comprising:

[0007] A battery is provided, wherein the negative electrode active material of the battery comprises a first active material and a second active material, wherein the gram capacity of the first active material is greater than the gram capacity of the second active material;

[0008] Before charging the battery, obtaining the real-time state of charge of the battery;

[0009] Comparing the real-time state of charge with a state of charge interval set in the battery; the state of charge interval is determined based on the lithium insertion contribution ratio of the first active material and the second active material in different state of charge stages, the state of charge interval includes a first interval in which the first active material predominantly inserts lithium, a second interval and a third interval in which the second active material predominantly inserts lithium, and a fourth interval in which the first active material and the second active material jointly insert lithium; the fourth interval includes at least one CC stage and / or at least one CV stage;

[0010] When the real-time state of charge is within the first interval, charging is performed using a first charging rate; the first charging rate is less than a fourth charging rate used in the fourth interval adjacent to the first interval;

[0011] When the real-time state of charge is in the second interval, charging is performed using a second charging rate; the second charging rate is greater than the fourth charging rate used in the fourth interval adjacent to the second interval;

[0012] When the real-time state of charge is within the third interval, charging is performed using a third charging rate; the third charging rate used at the lower threshold point of the third interval is greater than the fourth charging rate used at the upper threshold point of the fourth interval adjacent to the third interval; the third charging rate used at the upper threshold point of the third interval is greater than the fourth charging rate used at the lower threshold point of the fourth interval adjacent to the third interval;

[0013] When the real-time state of charge is in the fourth interval, charging is performed using the fourth charging rate.

[0014] Optionally, the charging method further includes:

[0015] Acquiring the real-time aging status of the battery during the aging process;

[0016] During the aging process, when the real-time aging state is less than the aging state threshold, the upper and lower limit thresholds of the state of charge interval are corrected to the upper and lower limit thresholds of the state of charge interval corresponding to the real-time first active material proportion in the current aging state;

[0017] At least one aging state threshold is set in the battery.

[0018] Optionally, the real-time aging status is the real-time first active material proportion; and obtaining the real-time aging status of the battery during the aging process includes:

[0019] obtaining a first capacity increment curve of a fresh battery and a second capacity increment curve of the battery during the aging process;

[0020] The real-time loss capacity of the first active material of the battery during the aging process is calculated according to a first relationship; the first relationship is:

[0021] Q′=L1-L2;

[0022] Wherein, Q′ represents the real-time loss capacity of the first active material; L1 represents the distance from the fourth peak or the fifth peak in the first capacity increment curve to the end point of the first capacity increment curve along the x-axis direction of the first capacity increment curve; L2 represents the distance from the fourth peak or the fifth peak in the first capacity increment curve to the end point of the second capacity increment curve along the x-axis direction of the second capacity increment curve; the real-time first active material proportion of the battery during the aging process is calculated according to the second relationship; the second relationship is:

[0023] Y=Q′ / L1;

[0024] Wherein, Y represents the proportion of the real-time first active material.

[0025] Optionally, the first charge rate is a constant value within the first interval, or the first charge rate varies with the state of charge in a continuous straight line, a curve, or a step-like manner;

[0026] And / or, the second charge rate is a constant value within the second interval, or the second charge rate changes with the state of charge in a continuous straight line, a curve, and / or a step-like manner;

[0027] And / or, the third charge rate in the third interval is a constant value, or the third charge rate changes with the state of charge in a continuous straight line, a curve, and / or a step-like manner;

[0028] And / or, the fourth charge rate in the fourth interval is a constant value, or the fourth charge rate changes with the state of charge in a continuous straight line, and / or curve, and / or step-like manner.

[0029] Optionally, the first active material is silicon, and the second active material is graphite;

[0030] The fourth interval includes a first sub-interval, a second sub-interval and a third sub-interval;

[0031] The first sub-interval is located between the first interval and the second interval; the first charging rate is less than the fourth charging rate used in the first sub-interval;

[0032] The second sub-interval is located between the second interval and the third interval; the second charging rate is greater than the fourth charging rate used in the first sub-interval and greater than the fourth charging rate used in the second sub-interval; the third charging rate used at the lower limit threshold point of the third interval is greater than the fourth charging rate used at the upper limit threshold point of the second sub-interval;

[0033] The third interval is located between the second sub-interval and the third sub-interval; the third charging rate used at the upper threshold point of the third interval is greater than the fourth charging rate used at the lower threshold point of the third sub-interval.

[0034] Optionally, the state of charge interval is determined according to the lithium insertion contribution ratio of the first active material and the second active material at different state of charge stages, including:

[0035] Determining, according to a calculation formula for state-of-charge interval threshold value values, upper and lower threshold values ​​of the first interval where the first active material predominantly inserts lithium, and upper and lower threshold values ​​of the second interval and the third interval where the second active material predominantly inserts lithium;

[0036] The calculation formula of the state of charge interval threshold value includes:

[0037] x0=A11×c+B11×d;

[0038] x1=A12×c+B12×d;

[0039] Wherein, x0 represents the lower limit threshold point of the first interval; A11 represents the lithium insertion coefficient of the first active material at x0, and A11 is 0; B11 represents the lithium insertion coefficient of the second active material at x0, and B11 is 0; c represents the capacity ratio of the first active material; d represents the capacity ratio of the second active material;

[0040] x1 represents the upper threshold value of the first interval; A12 represents the lithium insertion coefficient of the first active material at x1, A12 is 0.4-0.5, including both ends; B12 represents the lithium insertion coefficient of the second active material at x1, B12 is 0;

[0041] x2=A21×c+B21×d;

[0042] x3=A22×c+B22×d;

[0043] Wherein, x2 represents the lower threshold value of the second interval; A21 represents the lithium insertion coefficient of the first active material at x2, and A21 is 0.58-0.68, inclusive; B21 represents the lithium insertion coefficient of the second active material at x2, and B21 is 0.18-0.28, inclusive;

[0044] x3 represents the upper threshold value of the second interval; A22 represents the lithium insertion coefficient of the first active material at x3, A22 is 0.65-0.75, and includes the values ​​at both ends; B22 represents the lithium insertion coefficient of the second active material at x3, B12 is 0.46-0.56, and includes the values ​​at both ends;

[0045] x4=A31×c+B31×d;

[0046] x5=A32×c+B32×d;

[0047] Wherein, x4 represents the lower threshold value of the third interval; A31 represents the lithium insertion coefficient of the first active material at x4, and A31 is 0.7-0.8, inclusive; B31 represents the lithium insertion coefficient of the second active material at x4, and B31 is 0.47-0.57, inclusive;

[0048] x5 represents the upper threshold point of the second interval; A32 represents the lithium insertion coefficient of the first active material at x5, A32 is 0.77-0.87, and includes the values ​​at both ends; B32 represents the lithium insertion coefficient of the second active material at x5, B32 is 0.8-0.9, and includes the values ​​at both ends.

[0049] To achieve the above-mentioned purpose, the present application also provides a battery, which is charged using the charging method as described above. The battery includes a negative electrode, the negative electrode includes a negative electrode active layer, the negative electrode active layer includes a silicon-based material, and the silicon content of the silicon-based material in the negative electrode active layer is 2%-20%.

[0050] To achieve the above objectives, the present application also provides an electronic device, comprising: a memory and a processor;

[0051] The memory is connected to the processor and is used to store programs;

[0052] The processor is configured to implement the steps of any of the above-described charging methods by running the program stored in the memory.

[0053] To achieve the above objectives, the present application also provides a computer program product, including: computer program instructions, which, when executed by a processor, enable the processor to perform the steps of any of the charging methods described above.

[0054] To achieve the above objectives, the present application also provides a storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the charging method as described in any one of the above items are implemented.

[0055] Obviously, the present application provides a charging method, based on the different lithium insertion amounts of the first active material and the second active material in different charge state stages of the hybrid negative electrode battery, by decomposing the contribution ratios of the first active material and the second active material in the battery at different charge state stages, thereby allocating a reasonable charging rate to the charge state interval where the first active material and the second active material predominantly insert lithium, and the charge state interval where the second active material and the first active material jointly insert lithium. At the same time, considering that the first active material is more easily lost than the second active material when charged at a high rate, the rate of the charge state interval where the first active material predominantly inserts lithium is reduced, and the rate of the charge state interval where the second active material predominantly inserts lithium and the rate of the charge state interval where the first active material and the second active material jointly insert lithium are increased. This can achieve the reduction of battery cycle expansion, the improvement of battery cycle capacity retention rate, and thus the improvement of battery cycle life without affecting the charging speed. The present application also provides a battery, an electronic device, a computer program product, and a storage medium, which have the above-mentioned beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without any creative work.

[0057] Figure 1 A flowchart of a charging method provided in an embodiment of the present application;

[0058] Figure 2 This is an example graph of a lithium battery charging anode potential versus state of charge curve provided in an embodiment of the present application;

[0059] Figure 3 This is an example graph of a curve showing the change in charge state of silicon and graphite components in a lithium battery as a function of the charge state of the lithium battery provided in an embodiment of the present application;

[0060] Figure 4 This is an example graph of a curve showing the change in the state of charge of silicon and graphite components in a lithium battery according to an embodiment of the present application as a function of the first-order derivative of the state of charge of the lithium battery;

[0061] Figure 5 A schematic diagram of a capacity increment curve of a fresh battery and an aged battery provided in an embodiment of the present application;

[0062] Figure 6 This is an example graph of a curve showing the change of the state of charge of components in a lithium battery with different silicon contents along with the first-order derivative of the state of charge of the lithium battery provided in an embodiment of the present application;

[0063] Figure 7 A schematic diagram of charging rate selection for a charging method provided in an embodiment of the present application;

[0064] Figure 8 A graph showing the cyclic expansion variation trend of a lithium battery according to a charging method provided in an embodiment of the present application;

[0065] Figure 9 A graph showing a trend in the capacity change of a lithium battery cycle according to a charging method provided in an embodiment of the present application;

[0066] Figure 10 A hardware structure block diagram of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0067] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0068] At present, in order to increase the charging speed when lithium batteries are put into use, high-rate charging is usually adopted in the medium and low charge stages during the charging process. For lithium batteries with silicon and graphite negative electrodes, indiscriminate high-rate charging will inevitably lead to excessive active material loss and redundant by-products when silicon particles are embedded with lithium, thereby causing unnecessary capacity loss and expansion growth.

[0069] Therefore, the present application provides a charging method, a battery, an electronic device, a computer program product and a storage medium. Based on the different amounts of lithium intercalation of the first active material and the second active material in different charge state stages of the hybrid negative electrode battery, by decomposing the contribution ratios of the first active material and the second active material in the battery at different charge state stages, a reasonable charging rate is allocated to the charge state interval in which the first active material and the second active material dominate lithium intercalation and the charge state interval in which the second active material and the first active material jointly intercalate lithium. At the same time, considering that the first active material is more easily lost than the second active material when charged at a high rate, the rate in the charge state interval in which the first active material dominates lithium intercalation is reduced, and the rate in the charge state interval in which the second active material dominates lithium intercalation and the rate in the charge state interval in which the first active material and the second active material jointly intercalate lithium are increased. This can reduce battery cycle expansion and improve battery cycle capacity retention without affecting the charging speed, thereby improving battery cycle life.

[0070] Please refer to Figure 1 , Figure 1 A flowchart of a charging method provided in an embodiment of the present application may include:

[0071] S0: A battery is provided, wherein the negative electrode active material of the battery includes a first active material and a second active material, and the gram capacity of the first active material is greater than the gram capacity of the second active material.

[0072] Optionally, the battery in this embodiment may be, but is not limited to, a lithium-ion battery, and may also be a sodium-ion battery, a potassium-ion battery, or the like. The first active material may be silicon, and the second active material may be graphite. The first active material and the second active material may also be other negative electrode active materials having different lithium insertion amounts.

[0073] S1: Before charging the battery, obtain the real-time state of charge of the battery.

[0074] S2: Compare the real-time state of charge with the state of charge range set in the battery; the state of charge range is determined based on the proportion of lithium insertion contribution of the first active material and the second active material in different state of charge stages, and the state of charge range includes a first range in which the first active material dominates lithium insertion, a second range and a third range in which the second active material dominates lithium insertion, and a fourth range in which the first active material and the second active material jointly insert lithium; the fourth range includes at least one CC stage and / or at least one CV stage.

[0075] In this embodiment, the state of charge interval set in the battery can be the state of charge interval of the initial battery (i.e., a fresh battery), where a fresh battery refers to a battery in a new, unopened terminal, which is in an unpowered or just-powered state. The terminal can be a mobile phone, laptop, etc.

[0076] In this embodiment, the fourth interval may include a conventional CC stage, and / or a step CC stage, and / or a CV stage, and / or a CCCV alternating stage, wherein the conventional CC stage refers to charging with a constant current throughout the entire process until the battery voltage reaches a set threshold, and a constant charging rate is used in this stage; the step CC stage refers to charging with different constant currents in stages, and a constant charging rate is used in each stage and decreases step by step; the CV stage refers to constant voltage and exponential current decay, and the charging rate continues to decrease in this stage.

[0077] S21: When the real-time state of charge is in a first interval, charging is performed using a first charging rate; the first charging rate is smaller than a fourth charging rate used in a fourth interval adjacent to the first interval.

[0078] S22: When the real-time state of charge is in the second interval, charging is performed using a second charging rate; the second charging rate is greater than a fourth charging rate used in a fourth interval adjacent to the second interval.

[0079] S23: When the real-time state of charge is in the third interval, charging is performed using the third charging rate; the third charging rate used at the lower threshold point of the third interval is greater than the fourth charging rate used at the upper threshold point of the fourth interval adjacent to the third interval; the third charging rate used at the upper threshold point of the third interval is greater than the fourth charging rate used at the lower threshold point of the fourth interval adjacent to the third interval.

[0080] S24: When the real-time state of charge is in the fourth interval, charging is performed using a fourth charging rate.

[0081] This embodiment does not limit the specific number, arrangement, and charge rate relationship of each state of charge interval, which can be determined according to the specific types of the first active material and the second active material. For example, when the first active material is silicon and the second active material is graphite, it can be:

[0082] The fourth interval includes the first sub-interval, the second sub-interval and the third sub-interval;

[0083] The first sub-interval is between the first interval and the second interval; the first charging rate is less than the fourth charging rate used in the first sub-interval;

[0084] The second subinterval is between the second and third intervals; the second charge rate is greater than the fourth charge rate used in the first subinterval and greater than the fourth charge rate used in the second subinterval; the third charge rate used at the lower threshold point of the third interval is greater than the fourth charge rate used at the upper threshold point of the second subinterval;

[0085] The third interval is between the second sub-interval and the third sub-interval; the third charging rate used at the upper threshold point of the third interval is greater than the fourth charging rate used at the lower threshold point of the third sub-interval.

[0086] It should be noted that in this embodiment, the second sub-interval, the third sub-interval, and the third sub-interval are high state-of-charge intervals. The charge rate in this high state-of-charge interval decreases continuously in steps as the state of charge increases. This is done, on the one hand, to account for polarization issues to avoid triggering the cutoff voltage; on the other hand, to avoid lithium plating. Furthermore, in this embodiment, the fourth charge rate in the second sub-interval can be initially constant and then decrease continuously in steps as the state of charge increases; and the fourth charge rate in the third sub-interval can be initially constant and then decrease continuously in steps as the state of charge increases.

[0087] Furthermore, when the fourth charging rate used in the first sub-interval, the second sub-interval and the third sub-interval in this embodiment can be a conventional system rate under the same state of charge interval (that is, the charging rate used in the conventional charging method), accordingly, the first charging rate in the first interval can be a charging rate smaller than the conventional system rate under the same state of charge interval; the second charging rate in the second interval and the third charging rate in the third interval can be charging rates greater than the conventional system rate under the same state of charge interval.

[0088] It should be noted that when the first charging rate, and / or the second charging rate, and / or the third charging rate are used at a high charging rate in this embodiment, direct charging, multi-step constant current and constant voltage charging, multi-step constant current and constant voltage overvoltage charging, and any other high-rate charging method can be used for charging.

[0089] In a possible implementation, the specific method of determining the state of charge range in step S2 of the above embodiment may include:

[0090] Obtaining a first change curve; the first change curve includes curves of change of the charging anode potential of the first component battery, the second component battery, and the battery with the state of charge; the negative electrode active material of the first component battery includes a first active material; the negative electrode active material of the second component battery includes a second active material;

[0091] According to the first change curve, a second change curve is obtained; the second change curve includes the change curves of the charge state of the first component battery and the second component battery respectively as the charge state of the battery changes;

[0092] The second variation curve is derived to obtain a third variation curve; the third variation curve includes variation curves of the first derivatives of the state of charge of the first component battery and the second component battery respectively along with the state of charge of the battery;

[0093] The upper and lower threshold values ​​of the first interval in which the first active material predominantly inserts lithium are determined based on the width of the characteristic peak in the curve of the first derivative of the state of charge of the first component battery versus the state of charge of the battery; the upper and lower threshold values ​​of the second and third intervals in which the second active material predominantly inserts lithium are determined based on the width of the characteristic peak in the curve of the first derivative of the state of charge of the second component battery versus the state of charge of the battery; the interval other than the first, second and third intervals is the fourth interval in which the first active material and the second active material jointly insert lithium.

[0094] It should be noted that the upper and lower threshold points of the lithium insertion state of charge interval dominated by each active material in batteries with different active material contents are different, and the upper and lower threshold points of the lithium insertion state of charge interval dominated by each active material in batteries with different active material contents can be obtained by the above method.

[0095] The following examples further illustrate this embodiment:

[0096] Please refer to Figure 2 , Figure 2 This is an example graph of a lithium battery charging anode potential versus SOC curve provided in an embodiment of the present application. Figure 2 In the figure, the vertical axis represents the anode potential of the lithium battery when it is charging, and the horizontal axis represents the SOC (State of Charge, hereinafter referred to as SOC). The three curves shown in the example represent the anode potential variation curves of a pure graphite lithium battery, a pure silicon lithium battery, and a m% silicon + (1-m%) graphite lithium battery as a function of SOC. It should be noted that pure graphite or pure silicon means that the negative electrode active material of the lithium battery contains only graphite or silicon, and m% silicon + (1-m%) graphite means that the negative electrode active material of the lithium battery is composed of silicon and (1-m%) graphite accounting for m%. The value of m ranges from [0, 100]. The specific application value is not limited and can be determined according to the actual design situation. In this embodiment, the value of m is 4 as an example. It should be further noted that the three curves all use the same anode potential range to calibrate the capacity of 0-100% SOC. Furthermore, considering that over-delithiation of the anode will cause damage to the material structure, the anode potential in actual lithium battery applications can be selected in the range of 0.8V~0.01V. The specific application situation is not specifically limited in this embodiment.

[0097] like Figure 2 As shown in the figure, during the charging process, as the anode potential changes, the SOC values ​​of pure silicon lithium battery, pure graphite lithium battery and m% silicon + (1-m%) graphite lithium battery are different (that is, the degree of lithium insertion is different). Under the same anode potential Vx, the corresponding SOC values ​​X on the three curves can be obtained respectively. 石墨 、X 硅 、X 石墨 / 硅Therefore, these three curves can be used to calculate the SOC of pure silicon lithium battery, pure graphite lithium battery and m% silicon + (1-m%) graphite lithium battery at any anode potential. Furthermore, the corresponding SOC of the graphite and silicon components in the m% silicon + (1-m%) graphite lithium battery at different SOCs can be obtained.

[0098] Please refer to Figure 3 , Figure 3 The example graph of the change curve of the state of charge of silicon and graphite components in a lithium battery according to the embodiment of the present application can be based on Figure 2 The curve is calculated. Figure 3 In the figure, the vertical axis is the SOC of each component in the lithium battery, and the horizontal axis is the SOC of the lithium battery. The three curves shown are the change curves of the SOC of m% silicon + (1-m%) graphite lithium battery, pure silicon lithium battery and pure graphite lithium battery with the SOC of m% silicon + (1-m%) graphite lithium battery.

[0099] like Figure 3 As shown, the steeper the slope of the curve in the SOC range of the lithium battery on the horizontal axis, the more capacity the negative electrode active material component contributes to in the SOC range of the lithium battery (that is, the greater the contribution ratio). Specifically, when the SOC range of the lithium battery is [0%, 10%], the slope of the graphite component curve is very small, while the slope of the silicon component curve is very large, indicating that the capacity of the lithium battery in this SOC range is basically contributed by the lithium intercalation of the silicon component (that is, silicon dominates the lithium intercalation); when the SOC range of the lithium battery is [20%, 50%] and [55%, 65%], the slope of the graphite component curve is much greater than the slope of the silicon component curve, indicating that the capacity of the lithium battery in this SOC range is almost contributed by the lithium intercalation of the graphite component (that is, graphite dominates the lithium intercalation); in other SOC ranges, the slope of the graphite component curve and the slope of the silicon component curve are slightly different, indicating that the capacity of the lithium battery in this SOC range is contributed by both the lithium intercalation of the graphite component and the lithium intercalation of the silicon component (that is, graphite and silicon work together to intercalate lithium).

[0100] Please refer to Figure 4 , Figure 4 This is an example of a curve showing the change of the state of charge of silicon and graphite components in a lithium battery with the first-order derivative of the state of charge of the lithium battery provided in an embodiment of the present application. Figure 3 Obtained by curve derivation. Figure 4 In the figure, the vertical axis is the first-order derivative of the SOC of each component in the lithium battery, and the horizontal axis is the SOC of the lithium battery, which can more clearly distinguish the SOC range of silicon and graphite-dominated lithium insertion.

[0101] like Figure 4As shown in the figure, as the SOC of the lithium battery increases, the first-order derivatives of the SOC of the silicon and graphite components show different characteristic peaks; among them, the appearance of the characteristic peak represents the change of the component SOC, the higher the characteristic peak intensity, the faster the SOC change, and the characteristic peak width corresponds to the SOC range of the lithium battery when the component SOC changes. Specifically:

[0102] In stage 1 (i.e., the first interval mentioned above), a strong characteristic peak appears in the silicon component curve, indicating that the silicon SOC changes dramatically, and no characteristic peak appears in the graphite component curve, indicating that the graphite SOC does not change significantly. Therefore, it can be seen that the change in the lithium battery SOC in stage 1 is caused by the change in the silicon SOC, that is, the capacity of the lithium battery in this stage is dominated by silicon-intercalated lithium. Correspondingly, the maximum lithium battery SOC value in this stage is the upper limit threshold point of the lithium battery SOC in the silicon-dominated lithium-intercalated interval. During the lithium battery charging process, when the lithium battery SOC is in this stage, charging at a smaller rate than the conventional system rate can alleviate the lithium concentration difference in the particles, slow down the expansion, prevent material damage caused by stress concentration and excessive consumption during SEI (Solid Electrolyte Interphase) repair, thereby improving cycle expansion and reducing capacity loss;

[0103] In stage 2 and stage 3 (i.e., the second and third intervals mentioned above), a strong characteristic peak appears in the graphite component curve, indicating that the graphite SOC changes dramatically, and the characteristic peak of the silicon component curve is extremely weak, indicating that the silicon SOC has no obvious change. Therefore, it can be seen that the capacity of the lithium battery in stage 2 and stage 3 is dominated by graphite lithium insertion. Correspondingly, the upper and lower limit lithium battery SOC values ​​in this stage are the upper and lower limit threshold points of the lithium battery charge state in the graphite-dominated lithium insertion interval. During the lithium battery charging process, when the lithium battery SOC is in this stage, charging at a higher rate than the conventional rate can compensate for the time extension caused by the low rate charging in the silicon-dominated lithium insertion stage, and the total time of the balanced charging is equivalent to the total time of charging at the conventional rate.

[0104] The interval between stage 1 and stage 2, the interval between stage 2 and stage 3, and the interval greater than stage 3 are respectively the third interval, the fourth interval, and the fifth interval of the third interval.

[0105] In a possible implementation, the specific method of determining the state of charge range in step S2 of the above embodiment may include:

[0106] Determine, according to a calculation formula for the state of charge interval threshold value, the upper and lower threshold values ​​of a first interval where the first active material predominantly inserts lithium, and the upper and lower threshold values ​​of a second interval and a third interval where the second active material predominantly inserts lithium;

[0107] The calculation formula for the state of charge interval threshold value includes:

[0108] x0=A11×c+B11×d;

[0109] x1=A12×c+B12×d;

[0110] Wherein, x0 represents the lower threshold value of the first interval; A11 represents the lithium insertion coefficient of the first active material at x0, and A11 is 0; B11 represents the lithium insertion coefficient of the second active material at x0, and B11 is 0; c represents the capacity ratio of the first active material; d represents the capacity ratio of the second active material;

[0111] x1 represents the upper threshold value of the first interval; A12 represents the lithium insertion coefficient of the first active material at x1, and A12 is 0.4-0.5 (preferably 0.43-0.47), inclusive; B12 represents the lithium insertion coefficient of the second active material at x1, and B12 is 0;

[0112] x2=A21×c+B21×d;

[0113] x3=A22×c+B22×d;

[0114] Wherein, x2 represents the lower threshold point of the second interval; A21 represents the lithium insertion coefficient of the first active material at x2, and A21 is 0.58-0.68 (preferably in the range of 0.61-0.65), including both ends; B21 represents the lithium insertion coefficient of the second active material at x2, and B21 is 0.18-0.28 (preferably in the range of 0.21-0.25), including both ends;

[0115] x3 represents the upper threshold value of the second interval; A22 represents the lithium insertion coefficient of the first active material at x3, A22 is 0.65-0.75 (preferably in the range of 0.68-0.72), including both ends; B22 represents the lithium insertion coefficient of the second active material at x3, B12 is 0.46-0.56 (preferably in the range of 0.49-0.53), including both ends;

[0116] x4=A31×c+B31×d;

[0117] x5=A32×c+B32×d;

[0118] Wherein, x4 represents the lower threshold value of the third interval; A31 represents the lithium insertion coefficient of the first active material at x4, and A31 is 0.7-0.8 (preferably in the range of 0.73-0.77), inclusive; B31 represents the lithium insertion coefficient of the second active material at x4, and B31 is 0.47-0.57 (preferably in the range of 0.50-0.54), inclusive;

[0119] x5 represents the upper threshold point of the second interval; A32 represents the lithium insertion coefficient of the first active material at x5, A32 is 0.77-0.87 (preferably in the range of 0.80-0.84), and includes the values ​​at both ends; B32 represents the lithium insertion coefficient of the second active material at x5, B32 is 0.8-0.9 (preferably in the range of 0.83-0.87), and includes the values ​​at both ends.

[0120] It should be noted that the lithium insertion coefficient represents the ratio of lithium insertion, which is a fixed value determined based on the thermodynamics of the battery; the calculation formula for the capacity ratio of the first active material is:

[0121] c=m%×a / [m%×a+(1-m%)×b];

[0122] Wherein, c represents the capacity ratio of the first active material; m% represents the content of the first active material; 1-m% represents the content of the second active material; a represents the gram capacity of the first active material; b represents the gram capacity of the second active material;

[0123] The calculation formula for the capacity ratio of the first active material is:

[0124] d=(1-m%)×b / [m%×a+(1-m%)×b];

[0125] Wherein, d represents the capacity ratio of the second active material.

[0126] It should be noted that the lithium insertion coefficients of the upper and lower threshold points of the lithium insertion state of charge range dominated by each active material in batteries with different active material contents are constants determined based on the thermodynamics of the battery. The upper and lower threshold points of the lithium insertion state of charge range dominated by each active material in batteries with different active material contents can be obtained by substituting the content and gram capacity of each active material into the above formula.

[0127] The following examples further illustrate this embodiment:

[0128] In this embodiment, the upper and lower thresholds of the SOC interval of silicon-dominated lithium intercalation and graphite-dominated lithium intercalation in lithium batteries with different initial silicon contents can be calculated according to the following formula:

[0129] SOC interval threshold value = Σ(capacity ratio of each active material × lithium insertion coefficient of each active material at the SOC interval threshold point);

[0130] First, define the following variables:

[0131] The lithium insertion coefficient refers to the lithium insertion ratio of the silicon and graphite components at the upper and lower SOC threshold points of stages 1, 2, and 3 (the lithium insertion ratio of each component when fully charged is defined as 100%). This ratio is a constant determined by the thermodynamics of the lithium battery and is essentially only related to the anode potential of the lithium battery and does not change with changes in silicon content.

[0132] The component capacity ratio refers to the ratio of the capacity of silicon and graphite components to the total capacity in a lithium battery with a fixed silicon content; this ratio changes with the silicon content.

[0133] When the silicon content is m%, the silicon gram capacity is a, and the graphite gram capacity is b, then:

[0134] Total gram capacity: m%×a+(1-m%)×b;

[0135] Silicon capacity ratio: c = m% × a / [m% × a + (1-m%) × b];

[0136] Graphite capacity ratio: d = (1-m%) × b / [m% × a + (1-m%) × b];

[0137] For stage 1: graphite lithium insertion coefficient: 0, that is, the lithium insertion coefficient of graphite in stage 1 is 0; silicon lithium insertion coefficient: [0, 0.45], that is, the lithium insertion coefficient of silicon at the lower threshold point of stage 1 is 0, and the lithium insertion coefficient of silicon at the upper threshold point of stage 1 is 0.45; it can be obtained:

[0138] Stage 1 SOC interval lower threshold point: x0=0;

[0139] Stage 1 SOC interval upper threshold point: x1=0.45×c+0×d;

[0140] For stage 2: graphite lithium insertion coefficient: [0.23, 0.51], that is, the lithium insertion coefficient of graphite at the lower threshold point of stage 2 is 0.23, and the lithium insertion coefficient of graphite at the upper threshold point of stage 2 is 0.51; silicon lithium insertion coefficient: [0.63, 0.70], that is, the lithium insertion coefficient of silicon at the lower threshold point of stage 2 is 0.63, and the lithium insertion coefficient of silicon at the upper threshold point of stage 2 is 0.70; it can be obtained:

[0141] Stage 2 SOC interval lower threshold point: x2=0.63×c+0.23×d;

[0142] Stage 2 SOC interval upper threshold point: x3=0.70×c+0.51×d;

[0143] For stage 3: graphite lithium insertion coefficient: [0.52, 0.85], that is, the lithium insertion coefficient of graphite at the lower threshold point of stage 3 is 0.52, and the lithium insertion coefficient of graphite at the upper threshold point of stage 3 is 0.851; silicon lithium insertion coefficient: [0.75, 0.82], that is, the lithium insertion coefficient of silicon at the lower threshold point of stage 3 is 0.75, and the lithium insertion coefficient of silicon at the upper threshold point of stage 3 is 0.82; it can be obtained:

[0144] Stage 3 SOC interval lower threshold point: x4=0.75×c+0.52×d;

[0145] Stage 3 SOC interval upper threshold point: x5=0.82×c+0.85×d.

[0146] Charging the initial lithium battery: when the real-time SOC is in the range of [0, x1], a smaller charging rate lower than the conventional rate can be used; when the real-time SOC is in the range of [x2, x3] or [x4, x5], a larger charging rate higher than the conventional rate can be used; when the real-time SOC is in an SOC range outside the above three ranges, the conventional rate can be used for charging.

[0147] It should be noted that for lithium batteries with different silicon contents, the upper and lower thresholds of each SOC range are different and need to be adjusted according to the formula. For batteries with different negative electrode active materials, the lithium insertion coefficients of each component in the negative electrode active material at the SOC range threshold points are also different and need to be adjusted according to actual conditions.

[0148] In a possible implementation, the charging method of the above embodiment may further include:

[0149] Obtain the real-time aging status of the battery during the aging process;

[0150] During the aging process, when the real-time aging state is less than the aging state threshold, the upper and lower limit threshold points of the state of charge interval are corrected to the upper and lower limit threshold points of the state of charge interval corresponding to the real-time first active material proportion in the current aging state; at least one aging state threshold is set in the battery.

[0151] It should be noted that, in this embodiment, the upper and lower limit thresholds of the state of charge interval corresponding to the real-time first active material proportion under the current aging state can be determined according to the method of determining the state of charge interval in the above embodiment.

[0152] It should be noted that the aging process in this embodiment refers to all normal battery usage processes, including charging, discharging, and storage, starting from the time the battery is freshly used. This embodiment does not limit the specific number of aging status thresholds; multiple different aging status thresholds (such as first active material percentage thresholds under different aging conditions) can be set during the aging process and regularly adjusted.

[0153] It should be noted that different aging states refer to the process states in which the voltage-state of charge curve gradually shifts due to the gradual consumption of the active materials in the negative electrode during battery use. Taking lithium batteries with silicon and graphite negative electrodes as an example, this curve shift stems from the difference between the rapid consumption of silicon and the slow consumption of graphite during the cycle. During the aging process of lithium batteries, the proportion of silicon in the overall active material of the negative electrode continues to decline, resulting in a gradual shift in the charge range dominated by silicon and graphite. Therefore, during the aging process, the upper and lower threshold points of the state of charge range need to be continuously corrected to maintain a good match between the various charging stages and the charge rate during the aging process.

[0154] This embodiment does not limit the triggering conditions for iteratively correcting the upper and lower thresholds of the initially preset state of charge range. For example, the aging state threshold may include any one of a battery cycle count threshold, a first active material percentage threshold, or a battery state of health (SOH) threshold. Correspondingly, the real-time aging state may include any one of a real-time battery cycle count, a real-time first active material percentage, or a real-time battery health state. This embodiment does not limit the specific method for obtaining the real-time aging state. The corresponding acquisition method can be selected based on the specific type of real-time aging state. For example, when the real-time aging state is the real-time first active material percentage, the following two methods can be used:

[0155] (1) Obtaining a first capacity increment curve of a fresh battery and a second capacity increment curve of a battery during aging;

[0156] The real-time loss capacity of the first active material of the battery during the aging process is calculated according to the first relationship; the first relationship is:

[0157] Q′=L1-L2;

[0158] Wherein, Q′ represents the real-time loss capacity of the first active material; L1 represents the distance from the fourth peak or the fifth peak in the first capacity increment curve to the end point of the first capacity increment curve along the x-axis direction of the first capacity increment curve; L2 represents the distance from the fourth peak or the fifth peak in the first capacity increment curve to the end point of the second capacity increment curve along the x-axis direction of the second capacity increment curve; the real-time first active material proportion of the battery during the aging process is calculated according to the second relationship; the second relationship is:

[0159] Y=Q′ / L1;

[0160] Wherein, Y represents the real-time proportion of the first active material.

[0161] It should be noted that the prerequisite for decomposing the real-time loss capacity of the first active material according to the capacity increment curve in this embodiment is that there is no obvious loss of positive electrode active material in the battery, otherwise it will interfere with the decomposition result and lead to inaccurate silicon loss.

[0162] Please refer to Figure 5 , Figure 5 A schematic diagram of the capacity increment curve of a fresh battery and an aged battery provided in an embodiment of the present application. Figure 5 The horizontal axis is capacity (Q), and the vertical axis is dV (voltage) / dQ. Figure 5 Both the fresh and aged batteries in the figure use lithium cobalt oxide / lithium iron phosphate systems, so the distance from the fourth peak in the first capacity increment curve to the end point of the first capacity increment curve along the x-axis direction of the first capacity increment curve is recorded as L1. For ternary system batteries, the distance from the fifth peak in the first capacity increment curve to the end point of the first capacity increment curve along the x-axis direction of the first capacity increment curve is recorded as L1.

[0163] (2) From the relationship table between the number of cycles and the proportion of the first active material, find the real-time proportion of the first active material corresponding to the real-time number of cycles.

[0164] The following examples further illustrate this embodiment:

[0165] Please refer to Figure 6 , Figure 6 This is an example graph of a curve showing the change of the state of charge of components in a lithium battery with different silicon contents as a function of the first-order derivative of the state of charge of the lithium battery provided in an embodiment of the present application. Figure 6 In the figure, the upper vertical axis is the first-order derivative of the silicon SOC in the lithium battery, and the lower vertical axis is the first-order derivative of the graphite SOC in the lithium battery. The origins of the upper and lower vertical axes are both 0%; the horizontal axis is the lithium battery SOC, and high silicon and low silicon represent two lithium batteries with different silicon content.

[0166] like Figure 6 As shown in the figure, when the silicon content in the lithium battery changes from high to low, the corresponding characteristic peaks of each component shift toward the low SOC of the lithium battery. Correspondingly, the SOC range of the lithium battery dominated by each component also shifts toward the low SOC. On the other hand, due to the difference in the lithium insertion mechanism between silicon and graphite, the loss rate of silicon active material is faster than that of graphite. With aging, the real-time available active material ratio of silicon in the mixed negative electrode gradually decreases. For example, in the initial state of a lithium battery with a fixed ratio (cycle number is 0), the real-time silicon ratio is 10%, and the real-time silicon-dominated lithium insertion SOC range is [0,16%]. When the lithium battery cycle number reaches 400, due to the faster silicon attenuation, the real-time silicon ratio becomes 7%, and the real-time silicon-dominated lithium insertion SOC range is [0,10%]. Based on this, during the aging process, it is necessary to readjust the upper and lower thresholds of the initial preset silicon- and graphite-dominated lithium insertion SOC range according to the change in the real-time silicon ratio caused by silicon loss.

[0167] The following is a specific example of using the number of cycles as a trigger condition: taking a certain type of 5% silicon battery cycled at a voltage of 3V-4.53V and a temperature of 25°C as an example, the silicon loss capacity, real-time silicon proportion (i.e. silicon content), and the upper and lower thresholds of the silicon / graphite-dominated lithium insertion SOC range at each cycle number node are shown in Table 1.

[0168] Table 1 Changes in parameters when the number of cycles is used as a trigger condition

[0169]

[0170] In a possible implementation, the first charge rate in the first interval of the above embodiment may be a constant value, or the first charge rate may vary with the state of charge in a continuous straight line, and / or curve, and / or step-like manner;

[0171] And / or, the second charge rate in the second interval may be a constant value, or the second charge rate may vary with the state of charge in a continuous straight line, a curve, or a step-like manner;

[0172] And / or, the third charge rate is a constant value within the third interval, or the third charge rate varies with the state of charge in a continuous straight line, a curve, or a step-like manner;

[0173] And / or, the fourth charge rate is a constant value in the fourth interval, or the fourth charge rate changes with the state of charge in a continuous straight line, a curve, and / or a step-like manner.

[0174] Among them, the fourth charging rate can be a conventional charging rate.

[0175] The following examples further illustrate this embodiment:

[0176] Please refer to Figure 7 , Figure 7 A schematic diagram of charging rate selection for a charging method provided in an embodiment of the present application. Figure 7 In the figure, the upper vertical axis is the charge rate, the lower vertical axis is the first-order derivative of the SOC of each component in the lithium battery, and the horizontal axis is the SOC of the lithium battery. Among them, the conditions for formulating conventional charging systems are generally based on the balance between charging time and lithium precipitation window, without taking into account factors such as polarization and material damage. Specifically, Figure 7 The conventional system shown uses high-rate charging in the medium and low SOC range, which will aggravate the uneven distribution of lithium when silicon particles are embedded with lithium, leading to stress concentration, aggravated material damage, destroyed exposed new active interfaces, aggravated active lithium consumption and SEI thickening, thereby worsening the capacity loss and expansion growth of lithium batteries.

[0177] Based on this, Figure 7As an example of an improved strategy, this embodiment proposes dividing the SOC intervals based on silicon and graphite dominating lithium insertion into different stages. In SOC stage 1 where silicon dominates lithium insertion, a charging rate smaller than the conventional rate is selected to improve the uniformity of silicon lithium insertion, thereby avoiding the above situation. On the other hand, due to the good kinetics of graphite, in SOC stages 2 and 3 where graphite dominates lithium insertion, a rate larger than the conventional rate is selected within the kinetic and temperature rise window to achieve faster charging, which can offset the extended time of small current charging in the silicon-dominated lithium insertion stage.

[0178] It should be noted that the specific selected charging rate is designed to balance the extension time of the SOC interval using a smaller rate than the conventional system and the shortening time of the SOC interval using a larger rate than the conventional system, under the premise of meeting the dynamics, temperature window, charging time requirements of the actual lithium battery design. This embodiment does not impose specific restrictions.

[0179] Apart from Figure 7 As shown, within each divided charging stage, the charging rate can be a smooth constant value, or the charging rate can change continuously, such as a continuous straight line; or a continuous rising straight line; or a step-like rising curve, or a continuous rising curve; in addition, it can also be a continuous falling straight line; or a step-like falling curve, or a continuous falling curve.

[0180] In a possible implementation, the SOC interval for reducing or increasing the rate in the above embodiment may be all or part of the divided SOC interval, for example:

[0181] When the real-time state of charge is equal to any state of charge in the first interval, charging can be performed at the first charging rate; or when the real-time state of charge is equal to any state of charge in part of the first interval, charging can be performed at the first charging rate;

[0182] and / or, when the real-time state of charge is equal to any state of charge in the second interval, charging may be performed at the second charge rate, or when the real-time state of charge is equal to any state of charge in part of the second interval, charging may be performed at the second charge rate;

[0183] And / or, when the real-time state of charge is equal to any state of charge in the third interval, charging can be performed using the third charge rate, or when the real-time state of charge is equal to any state of charge in part of the third interval, charging can be performed using the third charge rate.

[0184] The following examples further illustrate this embodiment:

[0185] The silicon-dominated lithium intercalation SOC range is [0, x1], and the SOC range where the charging rate can be selected to be reduced can be [0, y1], then 0 < y1 ≤ x1. The graphite-dominated lithium intercalation SOC range is [x2, x3], and the SOC range where the charging rate can be selected to be increased is [y2, y3], then x2 ≤ y2 < y3 ≤ x3;

[0186] Exemplarily, taking a certain model battery with 5% silicon in the initial state as an example, any segment or all of the SOC range [0, 9.3%] can be selected to charge at a lower rate, and any segment or all of the SOC ranges [31.2%, 54.9%] and [56.7%, 84.4%] can be selected to charge at a higher rate.

[0187] The beneficial effects that can be produced by the above embodiments will be described below in conjunction with specific examples.

[0188] The batteries used in the following comparative examples and embodiments are all certain LCO-10%Si system batteries, with a rated capacity of 5950 mAh and a charging range of 3.0V - 4.58V;

[0189] Among them, a group of such batteries is used as a comparative example, and this comparative example uses a conventional charging regime. Two groups of such batteries are used as Embodiment 1 and Embodiment 2 respectively. Among them, Embodiment 1 uses Improved Regime 1 for charging, and Embodiment 2 uses Improved Regime 2 for charging. The charging methods of different groups of batteries are shown in Table 2.

[0190] Table 2 Charging Methods of Different Groups of Batteries

[0191]

[0192] After charging is completed, obtain the lithium battery cycle expansion change trend graph and the lithium battery cycle expansion change trend graph.

[0193] Please refer to Figure 8 , Figure 8 which is the lithium battery cycle expansion change trend graph of a charging method provided by an embodiment of the present application. Figure 8 In, the horizontal axis is the cycle number of the battery cell (i.e., the charge and discharge times of the battery cell), and the vertical axis is the cycle expansion rate. The conventional regime (solid line) refers to the change situation of the expansion rate of the lithium battery with the increase of the cycle number under the conventional high-rate charging regime; Improved Regimes 1 and 2 (dotted line, short dashed line) refer to the change situation of the expansion rate of the lithium battery with the increase of the cycle number after adjusting the charging rate to be reduced according to the silicon-dominated lithium intercalation SOC range. Among them, the charging rates of the silicon-dominated lithium intercalation SOC range are: Improved Regime 2 < Improved Regime 1 < Conventional Regime.

[0194] As Figure 8As shown in the figure, the three curves show that the cycle expansion rate of the battery cell gradually increases with the number of cycles. The difference is that under the same number of cycles, the cycle expansion rate of the lithium battery is lower when a lower charge rate is used in the silicon-dominated lithium intercalation SOC range. For example, at a cycle number of 600, the cycle expansion rate at the conventional system charge rate (maximum rate) is about 15.4%; the cycle expansion rate at the improved system 1 charge rate (intermediate rate) is about 12.6%; and the cycle expansion rate at the improved system 2 charge rate (minimum rate) is about 13.1%. It can be seen that by reducing the charge rate of the lithium battery in the silicon-dominated lithium intercalation SOC range, the rate of increase in the cycle expansion rate can be slowed, thereby achieving the purpose of extending the cycle life of the battery cell.

[0195] Please refer to Figure 9 , Figure 9 A graph showing the changing trend of the lithium battery cycle capacity according to a charging method provided in an embodiment of the present application. Figure 9 In the graph, the horizontal axis represents the number of cycles (i.e., the number of times the cell is charged and discharged), and the vertical axis represents the cycle capacity retention rate. The conventional system (solid line) shows how the capacity retention rate of a lithium battery changes with the number of cycles under the conventional high-rate charging system. Improved Systems 1 and 2 (dotted and dashed lines) show how the capacity retention rate changes with the number of cycles after the rate is adjusted to reduce the silicon-dominated lithium intercalation SOC range. Specifically, the charge rate in the silicon-dominated lithium intercalation SOC range is: Improved System 2 < Improved System 1 < Conventional System.

[0196] like Figure 9 As shown in the figure, the three curves show that as the number of cycles of the battery cell increases, the cycle capacity retention rate of the battery cell gradually decreases. The difference is that under the same number of cycles, when a lower charging rate is used in the silicon-dominated lithium intercalation SOC range, the cycle capacity retention rate of the lithium battery is higher. For example, when the number of cycles is 600, the cycle capacity retention rate under the conventional system charging rate (maximum rate) is about 78.9%; the cycle capacity retention rate under the improved system 1 charging rate (intermediate rate) is about 80.5%; and the cycle capacity retention rate under the improved system 2 charging rate (minimum rate) is about 80.2%. It can be seen that by reducing the charging rate of the lithium battery in the silicon-dominated lithium intercalation SOC range, the rate of decrease in the cycle capacity retention rate can be slowed down, thereby achieving the purpose of extending the cycle life of the battery cell.

[0197] The following introduces a battery, electronic device, computer program product, and storage medium provided in an embodiment of the present application. The battery, electronic device, computer program product, and storage medium described below can be referenced in correspondence with the charging method described above.

[0198] Based on the above embodiments, the present application also provides a battery, which is charged using the charging method as described above. The battery includes a negative electrode, the negative electrode includes a negative electrode active layer, the negative electrode active layer includes a silicon-based material, and the silicon content of the silicon-based material in the negative electrode active layer is 2%-20%.

[0199] It should be noted that the silicon testing method in this embodiment is as follows: the mass content of silicon in the negative electrode active layer can be tested by conventional methods in the art. For example, after discharging the battery to 0% SOC, the negative electrode is disassembled and removed, soaked in dimethyl carbonate (DMC) solvent for 12 hours, then rinsed with DMC solvent to remove lithium salts attached to the negative electrode. After drying, the negative electrode is high-temperature treated at 400°C for 2 hours in an inert atmosphere (for example, in a tube furnace under nitrogen or argon atmosphere). The negative electrode active layer can be peeled off from the negative electrode current collector and the negative electrode active layer is collected as a test sample. Using a thermogravimetric analyzer (for example, a TGA550 thermogravimetric analyzer), the test sample is 5 mg to 15 mg. The temperature is increased from room temperature (25°C) to 900°C at a rate of 10°C / min in air or oxygen atmosphere, and then maintained at 900°C for 40 minutes to allow non-silicon components in the negative electrode active layer to volatilize and silicon to be fully oxidized to silicon dioxide. The remaining substance is the ash of the negative electrode active layer. The mass content of silicon in the negative electrode active layer can be calculated based on the mass of the ash. The calculation formula is as follows: mass content of silicon in the negative electrode active layer = 7×mass of ash / (15×mass of test sample).

[0200] Please refer to Figure 10 , Figure 10 This is a hardware structure block diagram of an electronic device provided in an embodiment of the present application. Based on the above embodiment, the present application also provides an electronic device, including: a memory 1001 and a processor 1002;

[0201] The memory 1001 is connected to the processor 1002 and is used to store programs;

[0202] The processor 1002 is configured to implement the steps of the above-mentioned charging method by running the program stored in the memory 1001 .

[0203] In this embodiment, the electronic device may further include: a communication interface 1003, an input device 1004, an output device 1005 and a bus 1006;

[0204] The processor 1002, the memory 1001, the communication interface 1003, the input device 1004 and the output device 1005 are interconnected via a bus 1006.

[0205] Bus 1006 may include a pathway for transferring information between various components of the computer system.

[0206] Processor 1002 may be a general-purpose processor, such as a general-purpose central processing unit (CPU), a microprocessor, or the like. It may also be an application-specific integrated circuit (ASIC), or one or more integrated circuits used to control the execution of the program of the present application. It may also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), an off-the-shelf field programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic device, or discrete hardware component.

[0207] The processor 1002 may include a main processor, and may also include a baseband chip, a modem, etc.

[0208] Memory 1001 stores a program for executing the technical solution of the present application, and may also store an operating system and other key services. Specifically, the program may include program code, which includes computer operating instructions. More specifically, memory 1001 may include read-only memory (ROM), other types of static storage devices capable of storing static information and instructions, random access memory (RAM), other types of dynamic storage devices capable of storing information and instructions, disk storage, flash memory, and the like.

[0209] The input device 1004 may include a device for receiving data and information input by a user, such as a keyboard, a mouse, a camera, a scanner, a light pen, a voice input device, a touch screen, a pedometer, or a gravity sensor.

[0210] Output device 1004 may include a device that allows information to be output to a user, such as a display screen, a printer, a speaker, etc.

[0211] The communication interface 1003 may include any transceiver-like device to communicate with other devices or communication networks, such as Ethernet, Radio Access Network (RAN), Wireless Local Area Network (WLAN), etc. The processor 1002 executes the program stored in the memory 1001 and calls other devices to implement the various steps of the lithium battery charging method provided in the above embodiments of the present application.

[0212] Based on the above embodiments, the present application further provides a computer program product, including: computer program instructions, which, when executed by a processor, enable the processor to perform the steps of the above-mentioned charging method.

[0213] The computer program product described above in this embodiment can be written in any combination of one or more programming languages ​​to form program code for executing the operations of the embodiments of the present application. The programming languages ​​may include object-oriented programming languages ​​such as Java, C++, etc., as well as conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user computing device, partially on the user computing device, as a standalone software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0214] Based on the above embodiments, the present application further provides a storage medium, characterized in that: a computer program is stored on the storage medium, and when the computer program is executed by a processor, the steps of the charging method as described above are implemented.

[0215] Specific examples are used herein to illustrate the principles and implementation methods of the present application, and the various embodiments are in a progressive relationship. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other. For the relevant equipment disclosed in the embodiments, please refer to the corresponding method part description. The description of the above embodiments is only used to help understand the method of the present application and its core idea. For ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

[0216] It should also be noted that, in this specification, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

Claims

1. A charging method, characterized in that: include: A battery is provided, wherein the negative electrode active material of the battery comprises a first active material and a second active material, wherein the gram capacity of the first active material is greater than the gram capacity of the second active material; Before charging the battery, obtaining the real-time state of charge of the battery; comparing the real-time state of charge with a state of charge range set in the battery; The state of charge interval is determined according to the lithium insertion contribution ratio of the first active material and the second active material at different state of charge stages, and the state of charge interval includes a first interval in which the first active material predominantly inserts lithium, a second interval and a third interval in which the second active material predominantly inserts lithium, and a fourth interval in which the first active material and the second active material jointly insert lithium; the fourth interval includes at least one CC stage and / or at least one CV stage; When the real-time state of charge is within the first interval, charging is performed using a first charging rate; the first charging rate is less than a fourth charging rate used in the fourth interval adjacent to the first interval; When the real-time state of charge is in the second interval, charging is performed using a second charging rate; the second charging rate is greater than the fourth charging rate used in the fourth interval adjacent to the second interval; When the real-time state of charge is within the third interval, charging is performed using a third charging rate; the third charging rate used at the lower threshold point of the third interval is greater than the fourth charging rate used at the upper threshold point of the fourth interval adjacent to the third interval; the third charging rate used at the upper threshold point of the third interval is greater than the fourth charging rate used at the lower threshold point of the fourth interval adjacent to the third interval; When the real-time state of charge is in the fourth interval, charging is performed using the fourth charging rate.

2. The charging method according to claim 1, wherein: Also includes: Acquiring the real-time aging status of the battery during the aging process; During the aging process, when the real-time aging state is less than the aging state threshold, the upper and lower limit thresholds of the state of charge interval are corrected to the upper and lower limit thresholds of the state of charge interval corresponding to the real-time first active material proportion in the current aging state; At least one aging state threshold is set in the battery.

3. The charging method according to claim 2, wherein: The real-time aging state is the real-time first active material proportion; The obtaining of the real-time aging status of the battery during the aging process includes: obtaining a first capacity increment curve of a fresh battery and a second capacity increment curve of the battery during the aging process; The real-time loss capacity of the first active material of the battery during the aging process is calculated according to a first relationship; the first relationship is: Q′=L1-L2; Wherein, Q′ represents the real-time loss capacity of the first active material; L1 represents the distance from the fourth peak or the fifth peak in the first capacity increment curve to the end point of the first capacity increment curve along the x-axis direction of the first capacity increment curve; L2 represents the distance from the fourth peak or the fifth peak in the first capacity increment curve to the end point of the second capacity increment curve along the x-axis direction of the second capacity increment curve; the real-time first active material proportion of the battery during the aging process is calculated according to the second relationship; the second relationship is: Y=Q′ / L1; Wherein, Y represents the proportion of the real-time first active material.

4. The charging method according to claim 1, wherein: The first charge rate is a constant value within the first interval, or the first charge rate varies with the state of charge in a continuous straight line, a curve, or a step-like manner; And / or, the second charge rate is a constant value within the second interval, or the second charge rate changes with the state of charge in a continuous straight line, a curve, and / or a step-like manner; And / or, the third charge rate in the third interval is a constant value, or the third charge rate changes with the state of charge in a continuous straight line, a curve, and / or a step-like manner; And / or, the fourth charge rate in the fourth interval is a constant value, or the fourth charge rate changes with the state of charge in a continuous straight line, and / or curve, and / or step-like manner.

5. The charging method according to claim 1, wherein: The first active material is silicon, and the second active material is graphite; The fourth interval includes a first sub-interval, a second sub-interval and a third sub-interval; The first sub-interval is located between the first interval and the second interval; the first charging rate is less than the fourth charging rate used in the first sub-interval; The second sub-interval is located between the second interval and the third interval; the second charging rate is greater than the fourth charging rate used in the first sub-interval and greater than the fourth charging rate used in the second sub-interval; the third charging rate used at the lower limit threshold point of the third interval is greater than the fourth charging rate used at the upper limit threshold point of the second sub-interval; The third interval is located between the second sub-interval and the third sub-interval; the third charging rate used at the upper threshold point of the third interval is greater than the fourth charging rate used at the lower threshold point of the third sub-interval.

6. The charging method according to any one of claims 1 to 5, characterized in that: The state of charge interval is determined according to the lithium insertion contribution ratio of the first active material and the second active material at different state of charge stages, including: Determining, according to a calculation formula for state-of-charge interval threshold value values, upper and lower threshold values ​​of the first interval where the first active material predominantly inserts lithium, and upper and lower threshold values ​​of the second interval and the third interval where the second active material predominantly inserts lithium; The calculation formula of the state of charge interval threshold value includes: x0=A11×c+B11×d; x1=A12×c+B12×d; Wherein, x0 represents the lower limit threshold point of the first interval; A11 represents the lithium insertion coefficient of the first active material at x0, and A11 is 0; B11 represents the lithium insertion coefficient of the second active material at x0, and B11 is 0; c represents the capacity ratio of the first active material; d represents the capacity ratio of the second active material; x1 represents the upper threshold value of the first interval; A12 represents the lithium insertion coefficient of the first active material at x1, A12 is 0.4-0.5, including both ends; B12 represents the lithium insertion coefficient of the second active material at x1, B12 is 0; x2=A21×c+B21×d; x3=A22×c+B22×d; Wherein, x2 represents the lower threshold value of the second interval; A21 represents the lithium insertion coefficient of the first active material at x2, and A21 is 0.58-0.68, inclusive; B21 represents the lithium insertion coefficient of the second active material at x2, and B21 is 0.18-0.28, inclusive; x3 represents the upper threshold value of the second interval; A22 represents the lithium insertion coefficient of the first active material at x3, A22 is 0.65-0.75, and includes the values ​​at both ends; B22 represents the lithium insertion coefficient of the second active material at x3, B12 is 0.46-0.56, and includes the values ​​at both ends; x4=A31×c+B31×d; x5=A32×c+B32×d; Wherein, x4 represents the lower threshold value of the third interval; A31 represents the lithium insertion coefficient of the first active material at x4, and A31 is 0.7-0.8, inclusive; B31 represents the lithium insertion coefficient of the second active material at x4, and B31 is 0.47-0.57, inclusive; x5 represents the upper threshold point of the second interval; A32 represents the lithium insertion coefficient of the first active material at x5, A32 is 0.77-0.87, and includes the values ​​at both ends; B32 represents the lithium insertion coefficient of the second active material at x5, B32 is 0.8-0.9, and includes the values ​​at both ends.

7. A battery, characterized in that: The battery is charged using the charging method according to any one of claims 1 to 6, wherein the battery includes a negative electrode, the negative electrode includes a negative electrode active layer, the negative electrode active layer includes a silicon-based material, and the silicon-based material in the negative electrode active layer has a silicon content of 2%-20%.

8. An electronic device, characterized in that: include: memory and processor; The memory is connected to the processor and is used to store programs; The processor is configured to implement the steps of the charging method according to any one of claims 1 to 6 by running the program stored in the memory.

9. A computer program product, characterized in that include: Computer program instructions, when the computer program instructions are executed by a processor, enable the processor to perform the steps of the charging method according to any one of claims 1 to 6.

10. A storage medium, characterized in that: The storage medium stores a computer program, and when the computer program is executed by the processor, the steps of the charging method according to any one of claims 1 to 6 are implemented.

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