Formation method and device of positive electrode lithium supplement battery and positive electrode lithium supplement battery

Abstract

The invention provides a formation method and device of a positive pole lithium supplement battery and the positive pole lithium supplement battery, which can control a charging current as a first current, and perform constant-current charging on the positive pole lithium supplement battery until a solid electrolyte interface film is formed; controlling the charging current to increase, and carrying out constant-current charging until the voltage reaches a first voltage threshold value; controlling the charging current to be reduced, and carrying out constant-voltage and constant-current charging until the voltage reaches a second voltage threshold value; controlling the charging current to be continuously reduced, and carrying out constant-current charging in a negative-voltage environment until the voltage reaches a third voltage threshold value; and controlling the charging current to be continuously reduced, and carrying out constant-current charging in a negative-voltage environment until the voltage reaches a fourth voltage threshold value. According to the invention, battery polarization accumulation can be reduced, battery polarization is prevented from being too large, the lithium supplement agent is prevented from decomposing and generating gas too fast, battery interface deterioration is avoided, the capacity of the lithium supplement agent can be brought into full play, a good battery interface is kept, formation time is shortened, and the formation effect is relatively good.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and in particular to a formation method and device for a positive electrode lithium supplement battery and a positive electrode lithium supplement battery. Background Art

[0002] The market has higher and higher requirements for battery life, and it is very difficult to achieve this goal through material optimization and system optimization. Battery lithium replenishment has always been an important means for companies to solve the problem of battery cycle life. Battery lithium replenishment generally includes positive electrode lithium replenishment and negative electrode lithium replenishment. Negative electrode lithium replenishment technology has been in the research and development and trial stage because of its high requirements for the environment and process and its low compatibility with commercial production processes; positive electrode lithium replenishment only needs to add a small amount of lithium replenishment during the pulping stage of the positive electrode material, without changing the process and equipment of the previous stage, and the operation is simple and easy to implement.

[0003] At present, the commonly used positive electrode lithium supplements are generally: Li5FeO4, Li2NiO2, Li2O2, Li2C2O4, Li6CoO4, etc. With the deepening of research, lithium ferrite (Li5FeO4) has received more and more attention. First of all, the synthetic elements of lithium ferrite are widely available and inexpensive. The main reason limiting the price of lithium ferrite is the initial R&D cost and production cost of the product. With the market's acceptance, the price is also expected to drop significantly. Secondly, the amount of lithium supplemented by lithium ferrite is considerable, the mass proportion of lithium elements is high, and it has a low initial effect. Therefore, lithium ferrite may become the first choice for positive electrode lithium supplement materials.

[0004] However, in the application of lithium ferrite, there are some incompatibilities with the traditional non-positive lithium supplementation battery process. Take Li5FeO4 as an example. First, under high voltage, the battery gas production and electrolyte side reactions increase, affecting the battery capacity, rate, and cycle life; second, the lithium supplement is accompanied by gas production during the decomposition process, resulting in poor contact at the battery interface, purple spots, lithium precipitation, and reduced battery safety; third, the lithium supplement is incompletely decomposed, which may decompose oxygen during battery cycling or overcharging, causing battery performance deterioration.

[0005] Therefore, for positive lithium-supplemented batteries with lithium ferrite added, how to fully utilize the capacity of the lithium supplement, avoid gas production and deterioration of the interface, and shorten the formation time have become technical problems that need to be urgently solved by people in this field. Summary of the invention

[0006] In view of the above problems, the present invention provides a formation method and device for a positive electrode lithium supplement battery and a positive electrode lithium supplement battery that overcome the above problems or at least partially solve the above problems.

[0007] In a first aspect, a formation method of a positive lithium-supplemented battery comprises:

[0008] S1: Control the charging current to be the first current, and perform constant-current charging on the cathode lithium supplement battery with the first current until a solid electrolyte interface film is formed on the cathode lithium supplement battery;

[0009] S2: Control the charging current to increase to the second current, and perform constant-current charging on the cathode lithium supplement battery until the voltage of the cathode lithium supplement battery reaches the first voltage threshold;

[0010] S3: Control the charging current to decrease to the third current, and perform constant-voltage and constant-current charging on the cathode lithium supplement battery until the voltage of the cathode lithium supplement battery reaches the second voltage threshold, where the second voltage threshold is the first voltage plateau for the de-lithiation of the lithium supplement agent of the cathode lithium supplement battery;

[0011] S4: Control the charging current to decrease to the fourth current, and perform constant-current charging on the cathode lithium supplement battery in a negative pressure environment until the voltage of the cathode lithium supplement battery reaches the third voltage threshold, where the third voltage threshold is the second voltage plateau for the de-lithiation of the lithium supplement agent of the cathode lithium supplement battery;

[0012] S5: Control the charging current to decrease to the fifth current, and perform constant-current charging on the cathode lithium supplement battery in a negative pressure environment until the voltage of the cathode lithium supplement battery reaches the fourth voltage threshold, where the fourth voltage threshold is the upper limit value of the second voltage plateau for the de-lithiation of the lithium supplement agent of the cathode lithium supplement battery.

[0013] Optionally, in some alternative embodiments, S1 includes:

[0014] Control the charging current to be the first current, and perform constant-current charging on the cathode lithium supplement battery with the first current for a charging duration reaching a preset duration so that a solid electrolyte interface film is formed on the cathode lithium supplement battery, where the value range of the first current is from 0.05C to 0.1C, and the value range of the preset duration is from 5 minutes to 10 minutes.

[0015] Optionally, in some alternative embodiments, the value range of the second current is from 0.3C to 1.5C, and the value range of the first voltage threshold is from 3.40V to 3.50V.

[0016] Optionally, in some alternative embodiments, the value range of the third current is from 0.2C to 1C, the value range of the second voltage threshold is from 3.65V to 3.80V, and the cut-off current for restricting the constant-voltage and constant-current charging process is between 0.05C and 0.2C.

[0017] Optionally, in some alternative embodiments, the value range of the fourth current is from 0.05C to 0.2C, and the value range of the third voltage threshold is from 3.90V to 4.00V.

[0018] Optionally, in some alternative embodiments, the value range of the fifth current is from 0.02C to 0.1C, and the value range of the fourth voltage threshold is from 4.10V to 4.20 V.

[0019] Optionally, in some alternative embodiments, the absolute pressure of the negative pressure environment is between -50 kPa and -90 kPa;

[0020] The operating temperature range of S1 - S5 is: 20°C - 45°C.

[0021] Optionally, in some alternative embodiments, the lithium supplementation amount of the positive electrode lithium - supplemented battery is 0.5% - 4%, where the lithium supplementation amount = mass of the lithium supplementing agent ÷ mass of the main positive electrode material.

[0022] In a second aspect, a positive electrode lithium - supplemented battery is obtained by processing based on the formation method of the positive electrode lithium - supplemented battery according to any one of the above.

[0023] In a third aspect, a formation device for a positive electrode lithium - supplemented battery includes: a first charging unit, a second charging unit, a third charging unit, a fourth charging unit, and a fifth charging unit;

[0024] The first charging unit is configured to control the charging current as a first current and perform constant - current charging on the positive electrode lithium - supplemented battery with the first current until a solid electrolyte interface film is formed on the positive electrode lithium - supplemented battery;

[0025] The second charging unit is configured to control the charging current to increase to a second current and perform constant - current charging on the positive electrode lithium - supplemented battery until the voltage of the positive electrode lithium - supplemented battery reaches a first voltage threshold;

[0026] The third charging unit is configured to control the charging current to decrease to a third current and perform constant - voltage and constant - current charging on the positive electrode lithium - supplemented battery until the voltage of the positive electrode lithium - supplemented battery reaches a second voltage threshold, where the second voltage threshold is the first voltage platform for lithium de - intercalation of the lithium supplementing agent in the positive electrode lithium - supplemented battery;

[0027] The fourth charging unit is configured to control the charging current to decrease to a fourth current and perform constant - current charging on the positive electrode lithium - supplemented battery in a negative pressure environment until the voltage of the positive electrode lithium - supplemented battery reaches a third voltage threshold, where the third voltage threshold is the second voltage platform for lithium de - intercalation of the lithium supplementing agent in the positive electrode lithium - supplemented battery;

[0028] The fifth charging unit is configured to control the charging current to decrease to a fifth current and perform constant-current charging on the positive-lithium-supplemented battery in a negative-pressure environment until the voltage of the positive-lithium-supplemented battery reaches a fourth voltage threshold, where the fourth voltage threshold is the upper limit of the second voltage plateau at which the lithium supplement of the positive-lithium-supplemented battery is de-lithiated.

[0029] By means of the above technical solution, a formation method, a device, and a positive-lithium-supplemented battery provided by the present invention can control the charging current to be a first current and perform constant-current charging on the positive-lithium-supplemented battery with the first current until a solid electrolyte interface film is formed on the positive-lithium-supplemented battery; control the charging current to increase to a second current and perform constant-current charging on the positive-lithium-supplemented battery until the voltage of the positive-lithium-supplemented battery reaches a first voltage threshold; control the charging current to decrease to a third current and perform constant-voltage and constant-current charging on the positive-lithium-supplemented battery until the voltage of the positive-lithium-supplemented battery reaches a second voltage threshold, where the second voltage threshold is the first voltage plateau at which the lithium supplement of the positive-lithium-supplemented battery is de-lithiated; control the charging current to decrease to a fourth current and perform constant-current charging on the positive-lithium-supplemented battery in a negative-pressure environment until the voltage of the positive-lithium-supplemented battery reaches a third voltage threshold, where the third voltage threshold is the second voltage plateau at which the lithium supplement of the positive-lithium-supplemented battery is de-lithiated; control the charging current to decrease to a fifth current and perform constant-current charging on the positive-lithium-supplemented battery in a negative-pressure environment until the voltage of the positive-lithium-supplemented battery reaches a fourth voltage threshold, where the fourth voltage threshold is the upper limit of the second voltage plateau at which the lithium supplement of the positive-lithium-supplemented battery is de-lithiated. It can be seen from this that the present invention can perform segmented processing during the formation charging process, first rapidly exert the capacity of the main material with a relatively large voltage, and then gradually reduce the current, reduce the accumulation of battery polarization, prevent excessive battery polarization, prevent the lithium supplement from decomposing and generating gas too quickly, avoid the deterioration of the battery interface, enable the full utilization of the capacity of the lithium supplement, maintain a good battery interface, shorten the formation time, and have a better formation effect.

[0030] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly, it can be implemented according to the content of the specification. And in order to make the above and other objects, features, and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention are specifically described below. Brief Description of the Drawings

[0031] By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. And throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0032] Figure 1A flow chart of a formation method of a positive lithium-supplemented battery provided by the present invention is shown;

[0033] Figure 2 A structural schematic diagram of a formation device for a positive lithium-supplemented battery provided by the present invention is shown;

[0034] Figure 3 A structural schematic diagram of an electronic device provided by the present invention is shown. DETAILED DESCRIPTION

[0035] The market has higher and higher requirements for battery life, and it is very difficult to achieve this goal through material optimization and system optimization. Battery lithium replenishment has always been an important means for companies to solve the problem of battery cycle life. Battery lithium replenishment generally includes positive electrode lithium replenishment and negative electrode lithium replenishment. Negative electrode lithium replenishment technology has been in the research and development and trial stage because of its high requirements for the environment and process and its low compatibility with commercial production processes; positive electrode lithium replenishment only needs to add a small amount of lithium replenishment during the pulping stage of the positive electrode material, without changing the process and equipment of the previous stage, and the operation is simple and easy to implement.

[0036] At present, the commonly used positive electrode lithium supplements are generally: Li5FeO4, Li2NiO2, Li2O2, Li2C2O4, Li6CoO4, etc. With the deepening of research, lithium ferrite (Li5FeO4) has received more and more attention. First of all, the synthetic elements of lithium ferrite are widely available and inexpensive. The main reason limiting the price of lithium ferrite is the initial R&D cost and production cost of the product. With the market's acceptance, the price is also expected to drop significantly. Secondly, the amount of lithium supplemented by lithium ferrite is considerable, the mass proportion of lithium elements is high, and it has a low initial effect. Therefore, lithium ferrite may become the first choice for positive electrode lithium supplement materials.

[0037] However, in the application of lithium ferrite, there are some incompatibilities with the traditional non-positive lithium supplementation battery process. Take Li5FeO4 as an example. First, under high voltage, the battery gas production and electrolyte side reactions increase, affecting the battery capacity, rate, and cycle life; second, the lithium supplement is accompanied by gas production during the decomposition process, resulting in poor contact at the battery interface, purple spots, lithium precipitation, and reduced battery safety; third, the lithium supplement is incompletely decomposed, which may decompose oxygen during battery cycling or overcharging, causing battery performance deterioration.

[0038] That is, through the research of the inventors of this solution, it is found that the following problems exist in the formation process of the existing cathode lithium supplement lithium ferrite. First, the formation is carried out in two stages. That is, the first stage mainly focuses on the capacity utilization of the main material, and the second stage increases the voltage to decompose the lithium supplement agent. This method does not consider the problems of battery polarization and voltage hysteresis when the working window of the battery main material and the decomposition window of the lithium supplement agent overlap, which will cause insufficient decomposition of the lithium supplement agent and continue to decompose to produce oxygen during the subsequent cell cycling, resulting in deterioration of the cell performance. Second, adding a discharge process during the formation process, although reducing polarization, also increases the formation time of the battery. Too long formation time will affect the production scheduling cycle of mass production, increase equipment, etc., and increase the time and equipment costs of battery manufacturing. Finally, for the gas generation problem during the delithiation process of the lithium supplement agent, generally, the method of full negative pressure is adopted throughout the process, but it will also cause a large amount of electrolyte to be sucked away, and the liquid loss is very high.

[0039] Therefore, for the cathode lithium supplement battery with lithium ferrite added, how to fully utilize the capacity of the lithium supplement agent, avoid gas generation from deteriorating the interface, and shorten the formation time has become a technical problem that needs to be solved urgently by those skilled in the art.

[0040] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present invention can be more thoroughly understood and the scope of the present invention can be fully conveyed to those skilled in the art.

[0041] As Figure 1 shown, the present invention provides a formation method for a cathode lithium supplement battery, including: S100, S200, S300, S400, and S500;

[0042] S100. Control the charging current to be a first current, and perform constant current charging on the cathode lithium supplement battery with the first current until a solid electrolyte interface film is formed on the cathode lithium supplement battery;

[0043] Optionally, the first current can be a relatively small current. That is, the present invention first performs constant current charging on the cathode lithium supplement battery with a relatively small current so that a solid electrolyte interface film is formed on the cathode lithium supplement battery. It should be noted that: the present invention can be measured through experiments. Generally, for how long the cathode lithium supplement battery is charged with the first current, a solid electrolyte interface film can be formed on the cathode lithium supplement battery, and then this time range is recorded. Subsequently, during the actual formation process, the present invention can perform constant current charging on the cathode lithium supplement battery with the first current for this time range, and it can be defaulted that a solid electrolyte interface film has been formed without detecting whether the solid electrolyte interface film is generated, improving efficiency.

[0044] Optionally, during the first charge and discharge process of a lithium battery, a reaction occurs between the electrode material and the electrolyte at the solid-liquid interface, forming a passivation layer covering the surface of the electrode material. This passivation layer can effectively prevent further reaction between the electrolyte and the electrode material, thereby improving the cycle performance and safety of the battery. This passivation layer is the solid electrolyte interface film.

[0045] That is, in some alternative embodiments, the S100 includes: Step 1.1;

[0046] Step 1.1: Control the charging current to be a first current, and perform constant-current charging on the positive electrode supplementary lithium battery with the first current for a charging duration reaching a preset duration, so that the solid electrolyte interface film is formed on the positive electrode supplementary lithium battery. Among them, the value range of the first current is from 0.05C to 0.1C, and the value range of the preset duration is from 5 minutes to 10 minutes.

[0047] Optionally, as described above, the first current is a relatively small current. In the present invention, charging is first performed with a relatively small charging current to form a solid electrolyte interface film on the positive electrode supplementary lithium battery, which can ensure the integrity of the solid electrolyte interface film. The present invention does not limit this.

[0048] Optionally, the unit "C" of the current is common knowledge in the battery charge and discharge protocol. For example, for a 5Ah battery, the current when discharging from full charge to zero in 1 hour is 1C, and 1C = 5A; the current when discharging in 10 hours is 0.1C. The present invention does not describe this in detail.

[0049] Optionally, constant-current charging means that during the charging process, the charging current remains constant, and as time increases, the voltage of the positive electrode supplementary lithium battery is continuously rising.

[0050] S200: Control the charging current to increase to a second current, and perform constant-current charging on the positive electrode supplementary lithium battery until the voltage of the positive electrode supplementary lithium battery reaches a first voltage threshold;

[0051] For example, in some alternative embodiments, the value range of the second current is from 0.3C to 1.5C, and the value range of the first voltage threshold is from 3.40V to 3.50V.

[0052] Optionally, the present invention can control the charging current to increase from the first current to the second current, and then perform constant-current charging on the positive electrode supplementary lithium battery with the second current. It should be noted that: the second current is a relatively large current. Using a larger current to exert the capacity of the main material before reaching the first platform voltage of the lithium supplement agent can, to a certain extent, improve the efficiency of the present invention and shorten the formation time. The present invention does not limit this.

[0053] S300. Control the charging current to decrease to a third current, and perform constant voltage and constant current charging on the positive electrode lithium supplement battery until the voltage of the positive electrode lithium supplement battery reaches a second voltage threshold, where the second voltage threshold is the first voltage platform at which the lithium supplement agent of the positive electrode lithium supplement battery de-lithifies;

[0054] For example, in some optional embodiments, the value range of the third current is from 0.2C to 1C, the value range of the second voltage threshold is from 3.65V to 3.80V, and the cut-off current for limiting the constant voltage and constant current charging process is between 0.05C and 0.2C.

[0055] Optionally, the present invention can, on the basis of the second current, further reduce the charging current to a third current, and then perform constant voltage and constant current charging on the positive electrode lithium supplement battery with the third current. It should be noted that: constant voltage is a process in which the voltage remains unchanged and the current continuously decreases; if the cut-off current is not limited, theoretically the current will decrease infinitely, and then the charging time will be infinitely long, so a cut-off current needs to be set. That is, in the process of constant current and constant voltage where the current continuously decreases, there must be a cut-off current for constant voltage. That is, at the beginning of constant current and constant voltage, the current does not have true "constant current". After gradually decreasing from the third current to the cut-off current, true constant voltage and constant current charging is carried out with the cut-off current. The present invention does not limit this.

[0056] Optionally, because constant current and constant voltage can reduce the polarization of the battery, enabling the capacity to be exerted at a lower voltage (constant voltage); at the same time, it also limits the voltage from rising to the decomposition voltage of the lithium supplement agent, achieving the effect of platform segmentation. The present invention does not limit this.

[0057] S400. Control the charging current to decrease to a fourth current, and perform constant current charging on the positive electrode lithium supplement battery in a negative pressure environment until the voltage of the positive electrode lithium supplement battery reaches a third voltage threshold, where the third voltage threshold is the second voltage platform at which the lithium supplement agent of the positive electrode lithium supplement battery de-lithifies;

[0058] For example, in some optional embodiments, the value range of the fourth current is from 0.05C to 0.2C, and the value range of the third voltage threshold is from 3.90V to 4.00V.

[0059] Optionally, during the formation of a general battery, gas is generated. Soft packs require fixtures to restrain, and aluminum shells generally use a common negative pressure to enable the gas to be discharged in time to avoid the gas production affecting the interface of the battery cell. The present invention does not limit this.

[0060] Optionally, there are obviously two platforms in the discharging of the lithium supplement agent. For example, the first platform voltage of Li5FeO4 is about 3.5V; the second platform voltage of Li5FeO4 is about 4.0V. The present invention does not limit this.

[0061] S500, control the charging current to decrease to the fifth current, and perform constant-current charging on the positive electrode lithium supplement battery in a negative pressure environment until the voltage of the positive electrode lithium supplement battery reaches the fourth voltage threshold, where the fourth voltage threshold is the upper limit value of the second voltage platform for the de-lithiation of the lithium supplement agent of the positive electrode lithium supplement battery.

[0062] For example, in some optional embodiments, the value range of the fifth current is from 0.02C to 0.1C, and the value range of the fourth voltage threshold is from 4.10V to 4.20V.

[0063] Optionally, the upper limit value of the second platform voltage generally refers to 4.10V to 4.20V, because in this voltage range, it is already the upper limit of the voltage for the complete de-lithiation of the lithium supplement agent. The reason for setting this range is that the battery materials and temperature used make the kinetic performance of the battery different, but it is generally recognized that the lithium supplement agent is basically completely removed in this voltage range. Further increasing the voltage may cause damage to the original system (such as the lithium iron phosphate system + graphite system, 2.00V to 3.65V). The present invention does not limit this.

[0064] Optionally, in some optional embodiments, the absolute pressure of the negative pressure environment is between -50 kPa and -90 kPa;

[0065] The execution ambient temperature range of S1 to S5 is: 20°C - 45°C.

[0066] The above S100 to S300 can be carried out in an atmospheric pressure environment; S400 - S500 are carried out in a negative pressure environment; the above S100 - S500 can all be carried out at 20°C - 45°C, and the present invention does not limit this.

[0067] For further improvement, the positive electrode material of the battery cell in this embodiment is lithium iron phosphate, 2.2% of the lithium supplement agent LFO is added to the positive electrode, and the rated capacity is 57 Ah. The formation is carried out according to the following steps, table Compare each example and the comparative example:

[0068] Table 1

[0069] Step S1 S2 S3 S4 S5 Example 1 0.1C CC 7min 1C CC to 3.4V 0.3C CC CV to 3.75V, cut-off current 0.1C 0.1C CC to 3.95 V 0.05C CC to 4.20V Example 2 0.1C CC 7min 1.5C CC to 3.4V 0.5C CC CV to 3.75V cut-off current is 0.2C 0.1C CCto 3.95V 0.05C CC to 4.20V Example 3 0.05C CC 10min 0.3C CC to 3.4V 0.2C CC CV to 3.75V cut-off current is 0.05C 0.05C CC to3.95V 0.02C CC to4.20 Comparative Example 1 / 1C CC to3.4V 0.3C CC CV to 3.75V, cut-off current 0.1C 0.1C CC to 3.95 V 0.05C CC to 4.20V Comparative Example 2 0.1C CC 7min / 0.3C CC CV to 3.75V, cut-off current 0.1C 0.1C CC to 3.95 V 0.05C CC to 4.20V Comparative Example 3 0.1C CC 7min 1C CC to 3.75V / 0.1C CC to 3.95 V 0.05C CC to 4.20V Comparative Example 4 0.1C CC 7min 1C CC to 3.4V 0.3C CC CV to 3.75V cut-off current is 0.2C / 0.05C CC to4.20V Comparative Example 5 0.1C CC 7min 1C CC to 3.4V 0.3C CC CV to 3.75V cut-off current is 0.2C 0.1C CC to 4.20V

[0070] It should be noted that: CC refers to the constant current mode, and CV refers to the constant voltage mode.

[0071] After formation, the battery cells are tested as follows:

[0072] Formation duration: Statistically record the duration from the start to the end of the formation process;

[0073] Formation charging gram capacity: The calculation formula is the total formation capacity ÷ the mass of the active material (the weight of the main material + the weight of the lithium supplement agent) = the formation gram capacity;

[0074] Reverse capacity of the lithium supplement agent: The non-lithium-supplemented battery cells and the lithium-supplemented battery cells are subjected to the same process step to obtain the formation charging gram capacity. The calculation formula is: (H1 - H2 × α) × β = γ;

[0075] H1: Gram capacity of the lithium-supplemented battery cell;

[0076] H2: Gram capacity of the non-lithium-supplemented battery cell;

[0077] α: Mass ratio of the main material of the lithium-supplemented battery cell in the cathode sheet;

[0078] β: Mass ratio of the lithium supplement agent of the lithium-supplemented battery cell in the cathode sheet;

[0079] γ: Reverse capacity of the lithium supplement agent;

[0080] Cycle retention rate: At room temperature, cycle at a 1C rate for 1000 weeks, and calculate the capacity retention rate after cycling to 1000 weeks.

[0081] The results of relevant tests on the battery cells of each example and comparative example are shown in Table 2 below.

[0082] Table 2

[0083] Step Formation time min Formed gram capacity (mAh / g) Lithium supplement agent back-calculated capacity (mAh / g) Capacity retention rate after 1000 cycles % 60°C storage thermal thickness expansion rate % Example 1 184 174.38 694 95.36 1.42 Example 2 153 174.44 697 95.63 1.39 Example 3 285 174.60 704 95.65 1.40 Comparative Example 1 174 174.40 695 90.46 1.44 Comparative Example 2 318 174.35 693 95.67 1.46 Comparative Example 3 280 174.21 687 94.97 2.14 Comparative Example 4 378 174.06 720 90.65 3.85 Comparative Example 5 178 173.78 640 87.47 4.62

[0084] In Examples 1, 2, and 3, the lithium supplement agent reached more than 690 mAh / g, and after 1000 cycles, the capacity retention rates were basically the same and the interface was good.

[0085] Compared with Example 1, in Comparative Example 1, small-current formation charging was not added, resulting in poor integrity of the SEI in Comparative Example 1, and the 1000-cycle retention rate was significantly lower than that of Example 1.

[0086] Compared with Example 1, in Comparative Example 2, a larger current was not used in S2, and its formation time was longer than the overall formation time of Example 1, which would affect the production rhythm of the battery cells and increase the manufacturing cost of the battery cells.

[0087] Compared with Example 1, in Comparative Example 3, constant voltage charging at 3.75V was not added in the relief stage, which caused the large current charging in S2 to polarize the battery cells, resulting in a low capacity utilization of lithium iron phosphate. When the battery cells entered step S4, lithium iron phosphate did not release capacity at a low rate, resulting in the overall formation time of Comparative Example 3 being much longer than that of Example 1, a larger thickness expansion during storage at 60°C, and more gas generation in the comparative example battery cells than in the example.

[0088] Compared with Example 1, Comparative Example 4 uses a one-stage extremely small current to charge to 4.20V. The abnormal point is that the battery cell stays in the high voltage section for too long, which causes oxidation of part of the electrolyte, making the reverse capacity of the lithium supplement agent higher than the normal value, and also causing degradation of the battery cell system. Gas is produced during the cycle process, making the 1000-week cycle retention rate lower than Example 1, and the 60°C storage thickness is greater than that of the embodiment.

[0089] Compared with Example 1, Comparative Example 5 uses a one-stage larger current to charge to 4.20V, the polarization of the battery cell increases, and the gas production rate of the lithium supplement agent increases, which worsens the interface condition, and the capacity of the lithium supplement agent is not fully utilized. The undecomposed lithium supplement agent may continue to decompose and release oxygen during the subsequent use of the battery cell, and the battery cell stored at 60°C expands significantly, posing a major safety hazard.

[0090] In summary, the present invention splits the reaction stage of the lithium supplement agent and uses different currents to activate the lithium supplement agent once. For the first charge, the battery cell is charged with a small current to promote the formation of the SEI film.

[0091] In the second stage of charging, a larger current of 0.3C-1.5C is used to bring the main material capacity into full play before the first platform of lithium replenishment is reached; then, when the capacity of the first platform of lithium replenishment is brought into full play, a smaller current of 0.2C-1C is set to charge the battery cell and constant voltage charging is applied. Reducing current and constant voltage charging is to reduce battery polarization accumulation and give full play to the capacity of the first platform of lithium replenishment.

[0092] In the third stage of charging, the capacity of the second platform of the lithium supplement is utilized in stages to prevent excessive polarization of the battery, increase in voltage, and excessive decomposition and gas production of the lithium supplement, which will cause deterioration of the battery interface.

[0093] Finally, a small current is used to charge the battery to the upper limit voltage of the lithium supplement decomposition. The present invention controls the battery formation environment by applying a certain negative pressure exhaust only in the S400 and S500 stages where gas production is concentrated. This method reduces the negative pressure application time, reduces electrolyte loss, and reduces the production cost of the battery.

[0094] Although operations are depicted in a particular order, this should not be understood as requiring that the operations be performed in the particular order shown or in a sequential order.Multitasking and parallel processing may be advantageous under certain circumstances.

[0095] It should be understood that the various steps described in the method embodiments of the present invention may be performed in different orders and / or in parallel. In addition, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present invention is not limited in this respect.

[0096] like Figure 2As shown, the present invention provides a formation device for a cathode compensated lithium battery, comprising: a first charging unit 100, a second charging unit 200, a third charging unit 300, a fourth charging unit 400, and a fifth charging unit 500;

[0097] The first charging unit 100 is configured to control the charging current to be a first current and perform constant current charging on the cathode compensated lithium battery with the first current until a solid electrolyte interface film is formed on the cathode compensated lithium battery;

[0098] The second charging unit 200 is configured to control the charging current to increase to a second current and perform constant current charging on the cathode compensated lithium battery until the voltage of the cathode compensated lithium battery reaches a first voltage threshold;

[0099] The third charging unit 300 is configured to control the charging current to decrease to a third current and perform constant voltage and constant current charging on the cathode compensated lithium battery until the voltage of the cathode compensated lithium battery reaches a second voltage threshold, wherein the second voltage threshold is the first voltage platform for the de-lithiation of the lithium supplement agent of the cathode compensated lithium battery;

[0100] The fourth charging unit 400 is configured to control the charging current to decrease to a fourth current and perform constant current charging on the cathode compensated lithium battery in a negative pressure environment until the voltage of the cathode compensated lithium battery reaches a third voltage threshold, wherein the third voltage threshold is the second voltage platform for the de-lithiation of the lithium supplement agent of the cathode compensated lithium battery;

[0101] The fifth charging unit 500 is configured to control the charging current to decrease to a fifth current and perform constant current charging on the cathode compensated lithium battery in a negative pressure environment until the voltage of the cathode compensated lithium battery reaches a fourth voltage threshold, wherein the fourth voltage threshold is the upper limit value of the second voltage platform for the de-lithiation of the lithium supplement agent of the cathode compensated lithium battery.

[0102] Optionally, in some alternative embodiments, the first charging unit 100 includes: a first charging sub-unit;

[0103] The first charging sub-unit is configured to control the charging current to be a first current and perform constant current charging on the cathode compensated lithium battery with the first current for a charging duration reaching a preset duration so that a solid electrolyte interface film is formed on the cathode compensated lithium battery, wherein the value range of the first current is from 0.05C to 0.1C, and the value range of the preset duration is from 5 minutes to 10 minutes.

[0104] The processor contains cores, and the cores retrieve corresponding program units from the memory. One or more cores can be set. By adjusting the core parameters, the accumulation of battery polarization can be reduced, excessive battery polarization can be prevented, the decomposition and gas generation of the lithium supplement agent can be prevented from being too fast, the deterioration of the battery interface can be avoided, the capacity of the lithium supplement agent can be fully utilized, a good battery interface can be maintained, the formation time can be shortened, and the formation effect is better.

[0105] An embodiment of the present invention provides a computer-readable storage medium, on which a program is stored, and when the program is executed by a processor, the formation method of the positive electrode lithium supplement battery is implemented.

[0106] An embodiment of the present invention provides a processor, which is used to run a program. When the program runs, the formation method of the positive electrode lithium supplement battery is executed.

[0107] An embodiment of the present invention provides a positive electrode lithium supplement battery, which is obtained by processing based on the formation method of the positive electrode lithium supplement battery described in any one of the above.

[0108] As Figure 3 shown, an embodiment of the present invention provides an electronic device 700, which includes at least one processor 701, at least one memory 702 connected to the processor 701, and a bus 703; wherein, the processor 701 and the memory 702 complete communication with each other through the bus 703; the processor 701 is used to call program instructions in the memory 702 to execute the formation method of the positive electrode lithium supplement battery described above. The electronic device herein can be a server, a PC, a PAD, a mobile phone, etc.

[0109] The present invention also provides a computer program product, which is suitable for executing a program initialized with the following method steps when executed on an electronic device:

[0110] A formation method of a positive electrode lithium supplement battery includes:

[0111] S1: Control the charging current to be a first current, and perform constant current charging on the positive electrode lithium supplement battery with the first current until a solid electrolyte interface film is formed on the positive electrode lithium supplement battery;

[0112] S2: Control the charging current to increase to a second current, and perform constant current charging on the positive electrode lithium supplement battery until the voltage of the positive electrode lithium supplement battery reaches a first voltage threshold;

[0113] S3: Control the charging current to decrease to a third current, and perform constant voltage and constant current charging on the positive electrode lithium supplement battery until the voltage of the positive electrode lithium supplement battery reaches a second voltage threshold, where the second voltage threshold is the first voltage platform for the lithium supplement agent of the positive electrode lithium supplement battery to de-lithiate;

[0114] S4: Control the charging current to decrease to a fourth current, and perform constant-current charging on the positive electrode lithium supplement battery in a negative pressure environment until the voltage of the positive electrode lithium supplement battery reaches a third voltage threshold, where the third voltage threshold is the second voltage plateau at which the lithium supplement agent of the positive electrode lithium supplement battery de-lithiumizes;

[0115] S5: Control the charging current to decrease to a fifth current, and perform constant-current charging on the positive electrode lithium supplement battery in a negative pressure environment until the voltage of the positive electrode lithium supplement battery reaches a fourth voltage threshold, where the fourth voltage threshold is the upper limit value of the second voltage plateau at which the lithium supplement agent of the positive electrode lithium supplement battery de-lithiumizes.

[0116] Optionally, in some alternative embodiments, the S1 includes:

[0117] Control the charging current to be a first current, and perform constant-current charging on the positive electrode lithium supplement battery with the first current for a preset duration, so that a solid electrolyte interface film is formed on the positive electrode lithium supplement battery, where the value range of the first current is 0.05C to 0.1C, and the value range of the preset duration is 5 minutes to 10 minutes.

[0118] Optionally, in some alternative embodiments, the value range of the second current is 0.3C to 1.5C, and the value range of the first voltage threshold is 3.40V to 3.50V.

[0119] Optionally, in some alternative embodiments, the value range of the third current is 0.2C to 1C, the value range of the second voltage threshold is 3.65V to 3.80V, and the cut-off current for limiting the constant voltage and constant current charging process is between 0.05C and 0.2C.

[0120] Optionally, in some alternative embodiments, the value range of the fourth current is 0.05C to 0.2C, and the value range of the third voltage threshold is 3.90V to 4.00V.

[0121] Optionally, in some alternative embodiments, the value range of the fifth current is 0.02C to 0.1C, and the value range of the fourth voltage threshold is 4.10V to 4.20V.

[0122] Optionally, in some alternative embodiments, the absolute pressure of the negative pressure environment is between -50 kPa and -90 kPa;

[0123] The execution environment temperature range of the S1 - S5 is: 20°C - 45°C.

[0124] Optionally, in some alternative embodiments, the lithium supplementation amount of the positive electrode lithium supplementation battery is 0.5% - 4%, where the lithium supplementation amount = mass of the lithium supplementing agent ÷ mass of the main positive electrode material.

[0125] A positive electrode lithium supplementation battery obtained by processing the positive electrode lithium supplementation battery according to the formation method of the positive electrode lithium supplementation battery described in any one of claims 1 - 9.

[0126] A formation device for a positive electrode lithium supplementation battery, comprising: a first charging unit, a second charging unit, a third charging unit, a fourth charging unit, and a fifth charging unit;

[0127] The first charging unit is used to control the charging current to be a first current and perform constant - current charging on the positive electrode lithium supplementation battery with the first current until a solid electrolyte interface film is formed on the positive electrode lithium supplementation battery;

[0128] The second charging unit is used to control the charging current to increase to a second current and perform constant - current charging on the positive electrode lithium supplementation battery until the voltage of the positive electrode lithium supplementation battery reaches a first voltage threshold;

[0129] The third charging unit is used to control the charging current to decrease to a third current and perform constant - voltage and constant - current charging on the positive electrode lithium supplementation battery until the voltage of the positive electrode lithium supplementation battery reaches a second voltage threshold, where the second voltage threshold is the first voltage platform for lithium de - intercalation of the lithium supplementing agent in the positive electrode lithium supplementation battery;

[0130] The fourth charging unit is used to control the charging current to decrease to a fourth current and perform constant - current charging on the positive electrode lithium supplementation battery in a negative - pressure environment until the voltage of the positive electrode lithium supplementation battery reaches a third voltage threshold, where the third voltage threshold is the second voltage platform for lithium de - intercalation of the lithium supplementing agent in the positive electrode lithium supplementation battery;

[0131] The fifth charging unit is used to control the charging current to decrease to a fifth current and perform constant - current charging on the positive electrode lithium supplementation battery in a negative - pressure environment until the voltage of the positive electrode lithium supplementation battery reaches a fourth voltage threshold, where the fourth voltage threshold is the upper limit value of the second voltage platform for lithium de - intercalation of the lithium supplementing agent in the positive electrode lithium supplementation battery.

[0132] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses, electronic devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and combinations of flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to the processors of general-purpose computers, special-purpose computers, embedded processors, or other programmable devices to generate a machine, such that the instructions executed by the processors of the computer or other programmable devices produce means for implementing the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or in multiple blocks.

[0133] In a typical configuration, an electronic device includes one or more processors (CPUs), a memory, and a bus. The electronic device may also include an input / output interface, a network interface, etc.

[0134] The memory may include non-permanent memory in the form of computer-readable media, random access memory (RAM) and / or non-volatile memory such as read-only memory (ROM) or flash memory (flash RAM), and the memory includes at least one storage chip. The memory is an example of computer-readable media.

[0135] Computer-readable media includes permanent and non-permanent, removable and non-removable media that can store information by any method or technology. The information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette tapes, magnetic tape disk storage or other magnetic storage devices, or any other non-transmission media that can store information accessible by a computing device. As defined herein, computer-readable media does not include transitory media such as modulated data signals and carrier waves.

[0136] In the description of the present invention, it should be understood that if terms such as "upper", "lower", "front", "rear", "left" and "right" are used to indicate the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated position or element must have a specific orientation, be constructed and operate in a specific orientation. Therefore, it should not be construed as a limitation of the present invention.

[0137] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. It should also be noted that the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, commodity or device comprising a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent in such process, method, commodity or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the existence of another identical element in the process, method, commodity or device comprising the element.

[0138] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) containing computer-usable program code.

[0139] The above are only the embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the scope of the claims of the present invention.

Claims

1. A formation method for a positive lithium-supplemented battery, characterized in that: include: S1: controlling the charging current to be a first current, and performing constant current charging on the positive electrode lithium supplement battery with the first current until a solid electrolyte interface film is formed on the positive electrode lithium supplement battery; S2: Controlling the charging current to increase to a second current, and performing constant current charging on the positive lithium battery until the voltage of the positive lithium battery reaches a first voltage threshold; S3: controlling the charging current to decrease to a third current, and performing constant voltage and constant current charging on the positive lithium supplement battery until the voltage of the positive lithium supplement battery reaches a second voltage threshold, wherein the second voltage threshold is a first voltage platform for lithium supplement of the positive lithium supplement battery to be de-lithiated; S4: Controlling the charging current to decrease to a fourth current, and performing constant current charging on the positive lithium supplement battery in a negative pressure environment until the voltage of the positive lithium supplement battery reaches a third voltage threshold, wherein the third voltage threshold is a second voltage platform for lithium supplement of the positive lithium supplement battery to be de-lithiated; S5: Control the charging current to be reduced to a fifth current, and perform constant current charging on the positive lithium-supplementing battery in a negative pressure environment until the voltage of the positive lithium-supplementing battery reaches a fourth voltage threshold, wherein the fourth voltage threshold is the upper limit value of the second voltage platform of lithium depletion of the lithium-supplementing agent of the positive lithium-supplementing battery.

2. The method according to claim 1, characterized in that Said S1 comprises: The charging current is controlled to be a first current, and the positive electrode lithium battery is charged with a constant current with the first current. The charging time reaches a preset time so that the positive electrode lithium battery forms a solid electrolyte interface film, wherein the value range of the first current is 0.05C to 0.1C, and the value range of the preset time is 5 minutes to 10 minutes.

3. The method according to claim 1, characterized in that The second current has a value range of 0.3C to 1.5C, and the first voltage threshold has a value range of 3.40V to 3.50V.

4. The method according to claim 1, characterized in that: The value range of the third current is 0.2C to 1C, the value range of the second voltage threshold is 3.65V to 3.80V, and the cut-off current of the constant voltage and constant current charging process is limited to between 0.05C and 0.2C.

5. The method according to claim 1, characterized in that: The fourth current has a value range of 0.05C to 0.2C, and the third voltage threshold has a value range of 3.90V to 4.00V.

6. The method according to claim 1, characterized in that The fifth current has a value range of 0.02C to 0.1C, and the fourth voltage threshold has a value range of 4.10V to 4.20V.

7. The method according to claim 1, characterized in that The absolute pressure of the negative pressure environment is between -50 kPa and -90 kPa; The execution environment temperature range of S1 to S5 is: 20°C-45°C.

8. The method according to claim 1, characterized in that The amount of lithium supplement added to the positive electrode lithium supplement battery is 0.5%-4%, wherein the amount of lithium supplement added = the mass of the lithium supplement agent ÷ the mass of the positive electrode main material.

9. A positive lithium supplement battery, characterized in that: The positive electrode lithium-supplemented battery is obtained by processing according to the formation method of the positive electrode lithium-supplemented battery according to any one of claims 1 to 8.

10. A formation device for a positive lithium-supplemented battery, characterized in that: include: a first charging unit, a second charging unit, a third charging unit, a fourth charging unit and a fifth charging unit; The first charging unit is used to control the charging current to be a first current, and to perform constant current charging on the positive electrode lithium supplement battery with the first current until a solid electrolyte interface film is formed on the positive electrode lithium supplement battery; The second charging unit is used to control the charging current to increase to a second current, and to perform constant current charging on the positive lithium-supplemented battery until the voltage of the positive lithium-supplemented battery reaches a first voltage threshold; The third charging unit is used to control the charging current to be reduced to a third current, and to perform constant voltage and constant current charging on the positive lithium supplement battery until the voltage of the positive lithium supplement battery reaches a second voltage threshold, wherein the second voltage threshold is a first voltage platform for lithium supplement of the positive lithium supplement battery to be de-lithiated; The fourth charging unit is used to control the charging current to be reduced to a fourth current, and to perform constant current charging on the positive lithium supplement battery in a negative pressure environment until the voltage of the positive lithium supplement battery reaches a third voltage threshold, wherein the third voltage threshold is a second voltage platform for lithium supplement of the positive lithium supplement battery to be de-lithiated; The fifth charging unit is used to control the charging current to be reduced to a fifth current, and to perform constant current charging on the positive lithium-supplementing battery in a negative pressure environment until the voltage of the positive lithium-supplementing battery reaches a fourth voltage threshold, wherein the fourth voltage threshold is the upper limit value of the second voltage platform of lithium depletion of the lithium supplement agent of the positive lithium-supplementing battery.

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