Electrochemical lithium insertion and formation method of lithium ion capacitor

Abstract

The present invention relates to the technical field of lithium ion capacitors, and in particular to an electrochemical lithium insertion and formation method for lithium ion capacitors. The technical key point is to solve the problems of a large number of cycles and a long high-temperature aging time required for the existing lithium insertion and formation processes of lithium ion capacitors by means of pressurization and high temperature, thereby improving production efficiency and facilitating industrial production. At the same time, potential defects inside the product are exposed in a relatively short time, which is conducive to detection and screening, thereby ensuring product consistency.

Description

Technical Field

[0001] The invention relates to a lithium ion capacitor, and in particular to an electrochemical lithium insertion and formation method of a lithium ion capacitor. Background Art

[0002] Lithium-ion capacitor (LIC for short) is a new type of supercapacitor invented by combining lithium-ion batteries, supercapacitors and graphene, and is a type of hybrid capacitor. It has the advantages of high energy density and power density, long cycle life, fast charge and discharge speed, low self-discharge, and stable electrical performance. It has broad application prospects in wind power generation, rail transportation, energy recovery of new energy vehicles, and reserve power sources. Electrochemical lithium insertion is a key process in the manufacture of lithium-ion capacitors, which directly affects the product's cycle performance, self-discharge characteristics, service life, rate discharge and other electrochemical characteristics. However, the following problems exist in the existing lithium-ion capacitor field: the number of cycles required for lithium insertion and formation processes is large, the high-temperature aging time is long, the product consistency is poor, and industrial production cannot be achieved. Summary of the invention

[0003] The purpose of the present invention is to provide an electrochemical lithium insertion and formation method for lithium ion capacitors, which solves the problems of a large number of cycles and a long high-temperature aging time required for the existing lithium insertion and formation processes of lithium ion capacitors by means of pressurization and high temperature, improves production efficiency, and is conducive to industrial production. At the same time, potential defects inside the product are exposed in a relatively short time, which is conducive to detection and screening, thereby ensuring product consistency.

[0004] The technical solution of the present invention is:

[0005] A method for electrochemical lithium insertion and formation of a lithium ion capacitor, the technical key points of which are as follows:

[0006] The first stage, high temperature lithium insertion:

[0007] The lithium-ion capacitor is placed in a high temperature environment with a temperature of T1, so that the electrolyte fully infiltrates the electrode, and the metal lithium begins to embed into the graphite material of the negative electrode. The potential change during the lithium embedding process is monitored in real time. When the remaining amount of metal lithium is less than 40%, the storage is terminated. At this time, the total high temperature storage time is t 1 During this period, increasing pressures of P1, P2, and P3 are applied in sequence every 24 hours, and a boost pressure of P4 is applied for the remaining time; pressures P1 and P2 compress the lithium-ion capacitor and shorten the distance between the positive and negative electrodes, accelerating the penetration and reaction of the electrolyte in the electrodes, and pressures P3 and P4 promote gas discharge, and secondary sealing is performed after exhaust;

[0008] The second stage, formation:

[0009] At room temperature, first use a constant current I 1 Charge to rated voltage U R , constant voltage charging time is t 2 , and finally the constant current I 1 Discharge to the minimum operating voltage U min , the standing time is t 3 , repeat the above steps 3 to 5 times;

[0010] Stage 3, Aging:

[0011] Before aging, prepare with constant current I 1 Charge to maximum operating voltage U R , then constant voltage charging time t 4 After that, use constant current I 2 Discharge to voltage U 1 , and then placed in a high temperature environment at temperature T2 for a storage time of t 5 During storage in a high temperature environment for 24 to 48 hours, pressure P2 is applied, and increasing pressure P3 is applied for the remaining time. At this time, lithium insertion is 98% complete.

[0012] In the above-mentioned electrochemical lithium insertion and formation method of lithium ion capacitor, in the first stage, the temperature T1 is 40-50°C and the storage time t 1 It is 96 to 120 hours.

[0013] In the above-mentioned electrochemical lithium insertion and formation method of the lithium ion capacitor, in the first stage, the pressure P1 is 0.1-0.3 MPa, the pressure P2 is 0.3-0.5 MPa, the pressure P3 is 0.8-1.2 MPa, and the pressure P4 is 1.2-1.5 MPa.

[0014] In the above-mentioned electrochemical lithium insertion and formation method of lithium ion capacitor, in the second stage, the constant current I 1 0.2~0.5C, rated voltage U R 3.8~4.0V, constant voltage charging time t 2 2 to 5 hours, minimum working voltage U min 2.0~2.2V, standstill time t 3 1 to 10 minutes.

[0015] In the above-mentioned electrochemical lithium insertion and formation method of lithium ion capacitor, in the third stage, the constant voltage charging time t 4 For 20 to 25 hours, the constant current I 2 1~4C, voltage U 1 is 3.5~3.7V, temperature T2 is 40~45℃, storage time t 5 It is 96 to 192 hours.

[0016] The beneficial effects of the present invention are:

[0017] 1. The first stage of the present invention uses high temperature to reduce the viscosity of the electrolyte, improve the conductivity of the electrolyte, and accelerate the infiltration of the electrolyte and the embedding of LI ions by pressurizing, that is, shortening the gap between the electrode and the electrolyte, so that the electrolyte can more evenly and fully infiltrate the electrode. By continuously increasing the pressure, the internal bubbles can be discharged, which helps to reduce the pressure inside the capacitor, reduce the risk of bulging, leakage and other problems in the capacitor, and improve the quality and reliability of the capacitor. At the same time, the discharge of internal bubbles reduces the internal resistance, which means that more energy can be effectively released, thereby improving the discharge capacity and cycle life of the product.

[0018] 2. In the second stage, the lithium-ion capacitor is formed by controlling the formation current, optimizing the electrochemical reaction on the electrode surface, causing the electrode material and the electrolyte to react at the solid-liquid interface to form a uniform and stable dielectric layer covering the surface of the electrode material, reducing electrode polarization and improving the charge and discharge efficiency of the capacitor.

[0019] 3. In the third stage, during the high temperature and high pressure aging process, uniform pressure is applied to expose potential defects inside the product in a relatively short period of time, such as voltage changes, thickness changes, internal resistance changes, etc. These are comprehensive indicators of safety and electrochemical performance, to remind staff of problems such as uneven distribution of electrode materials and tiny short circuit points in the product, which lead to a significant decline in capacitor performance. Staff can quickly detect and screen out unqualified products to ensure product consistency.

[0020] In summary, the present invention solves the problems of a large number of cycles and a long high-temperature aging time required for the existing lithium ion capacitor lithium insertion and formation processes by means of pressurization and high temperature, thereby significantly improving production efficiency and facilitating industrial production. DETAILED DESCRIPTION

[0021] The present invention is described in detail below with reference to specific embodiments.

[0022] The method for manufacturing a lithium ion capacitor of the present invention comprises the following steps:

[0023] First, the activated carbon is mixed with adhesives, etc., made into a slurry, and then coated on aluminum foil, and then dried to complete the production of the positive electrode; the negative electrode uses graphite, which is also a single carbon substance, mixed with adhesives, made into a slurry, and then coated on copper foil, and then dried to complete the production; secondly, the positive electrode, negative electrode and diaphragm paper are used to make a battery cell, which is completed after water removal, pre-embedded lithium in the negative electrode, and injection and sealing. Finally, electrochemical lithium insertion and formation are carried out. This process is that the metal lithium is embedded in the negative electrode graphite, and the negative electrode potential is low, thereby generating a potential difference.

[0024] Among them, the electrochemical lithium insertion and formation method specifically includes the following stages:

[0025] The first stage is high-temperature lithium insertion. The product is placed in a 40-50°C oven for 96-120 hours, and pressure is applied in sequence: 0.1-0.3 Mpa, 0.3-0.5 Mpa, 0.8-1.2 Mpa every 24 hours, and 1.2-1.5 Mpa for the remaining time. During this process, the potential change during the lithium insertion process is monitored in real time, and then the second seal is performed after exhaust. When the remaining amount of metal lithium is less than 40%, the storage ends.

[0026] The second stage is formed at room temperature. The parameters are as follows: first charge at a constant current of 0.2-0.5C to a rated voltage of 3.8-4.0V, charge at a constant voltage for 2-5 hours, and finally discharge at a constant current of 0.2-0.5C to a minimum operating voltage of 2.0-2.2V, let stand for 1-10 minutes, and repeat the above steps 3-5 times.

[0027] The third stage is aging.

[0028] First, charge at a constant current of 0.2-0.5C to a rated voltage of 3.8-4.0V, charge at a constant voltage for 20-25h, then discharge at a constant current of 1-4C to a voltage of 3.5-3.7V, and place at a high temperature of 40-45℃ for 96-192 hours. When stored at a high temperature for 24-48 hours, the pressure applied is 0.3-0.5Mpa, and the pressure applied for the remaining time is 0.8-1.2Mpa. Example 1

[0029] Make a 270mAh lithium-ion capacitor with a designed ESR of 4.3mΩ.

[0030] S1: Place the injected lithium ion capacitor in a high temperature oven at 40℃, and apply pressures of 0.1Mpa, 0.3Mpa, 0.8Mpa, and 1.2Mpa every 24 hours. After 120 hours of high temperature storage, the terminal voltage of the product is 2.70~2.73V, and the storage is ended.

[0031] S2: At room temperature, use the Enzhi capacity tester to perform formation. Set the parameters as follows: first charge at a constant current of 0.3C (0.09A) to a rated voltage of 3.8V, constant voltage charging time of 3 hours, and finally discharge at a constant current of 0.3C (0.09A) to a minimum operating voltage of 2.2V, stand for 5 minutes, and repeat the above steps 5 times.

[0032] S3: First charge at a constant current of 0.3C (0.09A) to a rated voltage of 3.8V, charge at a constant voltage for 22h, then discharge at a constant current of 3C (0.9A) to a voltage of 3.5V, place at a high temperature of 45°C for 48 hours, apply a pressure of 0.3Mpa, and then apply a pressure of 0.8Mpa for 48 hours (a total of 96 hours under high temperature conditions).

[0033] The initial capacity and capacity after cycling of capacitor samples No. 1 to No. 5 manufactured according to the above steps are tested, and the data are shown in the following table:

[0034]

[0035] It can be seen from Table 1-1 that the average initial internal resistance of the product prepared in Example 1 is 4.18m, which is 97.21% of the designed ESR; the average initial capacity is 296.7mAh, which is 109.9% of the designed capacity; the average internal resistance change multiple after 20,000 cycles is 1.21, the average capacity after the cycle is 285.9mAh, and the average capacity retention rate is 96.36%. Example 2

[0036] Make a 270mAh lithium-ion capacitor with a designed ESR of 4.3mΩ.

[0037] S1: Place the injected lithium-ion capacitor in a high temperature environment of 50°C. Apply pressures of 0.2 Mpa, 0.4 Mpa, 1.0 Mpa, and 1.4 Mpa in sequence every 24 hours. After 108 hours of high temperature storage, the terminal voltage of the product is 2.82-2.85V.

[0038] S2: Under normal temperature, the capacitor is formed using the Enzhi capacitance tester. The parameters are set as follows: first, charge to the rated voltage of 3.8V at a constant current of 0.3C (0.09A), the constant voltage charging time is 3 hours, and finally discharge to the minimum working voltage of 2.1V at a constant current of 0.3C (0.09A), the standing time is 5 minutes, and the above steps are repeated 3 times.

[0039] S3: First charge at a constant current of 0.3C (0.09A) to a rated voltage of 3.8V, charge at a constant voltage for 22h, then discharge at a constant current of 3C (0.9A) to a voltage of 3.5V, place at a high temperature of 45°C for 48 hours, apply a pressure of 0.4Mpa, and then apply a pressure of 1.0Mpa for 48 hours (a total of 96 hours under high temperature conditions).

[0040] The initial capacity and capacity after cycling of capacitor samples No. 1 to No. 5 manufactured according to the above steps are tested, and the data are shown in the following table:

[0041]

[0042] As can be seen from Table 1-2, the average initial internal resistance of the product prepared in Example 2 is 4.17mΩ, which is 96.98% of the designed ESR; the average initial capacity is 296.1mAh, which is 109.7% of the designed capacity. After 20,000 cycles, the average internal resistance change factor is 1.22, the average capacity after the cycle is 286.72mAh, and the average capacity retention rate is 96.84%. Example 3

[0043] Make a 270mAh lithium-ion capacitor with a designed ESR of 4.3mΩ.

[0044] S1: Place the injected lithium-ion capacitor in a high temperature environment of 45°C. Apply 0.3Mpa, 0.5Mpa, 1.2Mpa, and 1.5Mpa in sequence every 24 hours. After 96 hours of high temperature storage, the terminal voltage of the product is 2.75-2.78V.

[0045] S2: At room temperature, the capacitor was formed using the Enzhi capacitance tester. The parameters were set as follows: first, charge at a constant current of 0.3C (0.09A) to a rated voltage of 3.8V, charge at a constant voltage for 3 hours, and finally discharge at a constant current of 0.3C (0.09A) to a minimum operating voltage of 2.2V, let stand for 5 minutes, and repeat the above steps 3 times.

[0046] S3: First charge at a constant current of 0.3C (0.09A) to a rated voltage of 3.8V, maintain constant voltage for 22 hours, then discharge at a constant current of 3C (0.9A) to a voltage of 3.5V, place at a high temperature of 45°C for 48 hours, apply a pressure of 0.5Mpa, and then apply a pressure of 1.2Mpa for 48 hours (a total of 96 hours under high temperature conditions).

[0047] The initial capacity and capacity after cycling of capacitor samples No. 1 to No. 5 manufactured according to the above steps are tested, and the data are shown in the following table:

[0048]

[0049] As can be seen from Tables 1-3, the average initial internal resistance of the product obtained in Example 3 is 4.05mΩ, which is 94.19% of the designed ESR; the average initial capacity is 296.5mAh, which is 109.8% of the designed capacity. After 20,000 cycles, the average internal resistance change multiple is 1.19, the average capacity after the cycle is 288.1mAh, and the average capacity retention rate is 97.18%. Example 4

[0050] Make a 270mAh lithium-ion capacitor with a designed ESR of 4.3mΩ.

[0051] S1: Same as Example 3.

[0052] S2: At room temperature, the capacitor was formed using the Enzhi capacitance tester. The parameters were set as follows: first, charge to a rated voltage of 3.8V at a constant current of 0.2C (0.06A), charge at a constant voltage for 5 hours, and finally discharge to a minimum operating voltage of 2.2V at a constant current of 0.2C (0.06A), let stand for 1 minute, and repeat the above steps 4 times.

[0053] S3: First charge at a constant current of 0.2C (0.06A) to a rated voltage of 3.8V, charge at a constant voltage for 20h, then discharge at a constant current of 1C (0.3A) to a voltage of 3.7V, place at a high temperature of 40°C for 48 hours, apply a pressure of 0.5Mpa, and then apply a pressure of 1.2Mpa for 48 hours (a total of 96 hours under high temperature conditions).

[0054] The initial capacity and capacity after cycling of capacitor samples No. 1 to No. 5 manufactured according to the above steps are tested, and the data are shown in the following table:

[0055]

[0056] As can be seen from Tables 1-4, the average initial internal resistance of the product prepared in Example 4 is 4.13mΩ, which is 96.05% of the designed ESR; the average initial capacity is 295.2mAh, which is 109.3% of the designed capacity. After 20,000 cycles, the average internal resistance change factor is 1.22, the average capacity after the cycle is 283.6mAh, and the average capacity retention rate is 96.08%. Example 5

[0057] Make a 270mAh lithium-ion capacitor with a designed ESR of 4.3mΩ.

[0058] S1: Same as Example 3.

[0059] S2: At room temperature, the capacitor was formed using the Enzhi capacitance tester. The parameters were set as follows: first, charge to a rated voltage of 3.8V at a constant current of 0.5C (0.15A), charge at a constant voltage for 2 hours, and finally discharge to a minimum operating voltage of 2.0V at a constant current of 0.5C (0.15A), let stand for 10 minutes, and repeat the above steps 3 times.

[0060] S3: First charge at a constant current of 0.5C (0.15A) to a rated voltage of 3.8V, charge at a constant voltage for 25h, then discharge at a constant current of 4C (1.2A) to a voltage of 3.5V, place at a high temperature of 45°C for 48 hours with a pressure of 0.5Mpa, then place at a pressure of 1.2 Mpa for 96 hours (a total of 144 hours under high temperature conditions).

[0061] The initial capacity and capacity after cycling of capacitor samples No. 1 to No. 5 manufactured according to the above steps are tested, and the data are shown in the following table:

[0062]

[0063] As can be seen from Tables 1-5, the average initial internal resistance of the product prepared in Example 5 is 4.26 mΩ, which is 99.1% of the designed ESR; the average capacity is 293.9 mAh, which is 108.9% of the designed capacity. After 20,000 cycles, the average internal resistance change factor is 1.22, the average capacity after the cycle is 282.3 mAh, and the average capacity retention rate is 96.07%. Example 6

[0064] Make a 600mAh lithium-ion capacitor with a designed ESR of 2.2mΩ.

[0065] S1, S2: Same as Example 3.

[0066] S3: First charge at a constant current of 0.3C (0.18A) to the rated voltage of 3.8V, charge at a constant voltage for 22h, then discharge at a constant current of 3C (0.9A) to 3.5V, place at a high temperature of 45℃ for 48 hours with a pressure of 0.5Mpa, then place at a pressure of 1.2Mpa for 144 hours (a total of 192 hours under high temperature conditions).

[0067] The initial capacity and capacity after cycling of capacitor samples No. 1 to No. 5 manufactured according to the above steps are tested, and the data are shown in the following table:

[0068]

[0069] As can be seen from Table 1-6, the average initial internal resistance of the product prepared in Example 6 is 2.10mΩ, which is 95.45% of the designed ESR; the average initial capacity is 623.5mAh, which is 103.9% of the designed capacity. After 20,000 cycles, the average internal resistance change factor is 1.19, the average capacity after the cycle is 610.5mAh, and the average capacity retention rate is 97.92%. Example 7

[0070] Make a 850mAh lithium-ion capacitor with a designed ESR of 1.5mΩ.

[0071] S1: Same as Example 3.

[0072] S2: At room temperature, the capacitor was formed using the Enzhi capacitance tester. The parameters were set as follows: first, charge to a rated voltage of 3.9V at a constant current of 0.4C (0.34A), charge at a constant voltage for 2 hours, and finally discharge to a minimum operating voltage of 2.2V at a constant current of 0.4C (0.34A), let stand for 10 minutes, and repeat the above steps 3 times.

[0073] S3: First charge at a constant current of 0.4C (0.34A) to a rated voltage of 3.9V, charge at a constant voltage for 20h, then discharge at a constant current of 3C (2.55A) to 3.6V, place at a high temperature of 43°C for 48 hours with a pressure of 0.5Mpa, then place at a pressure of 1.2Mpa for 96 hours (a total of 144 hours under high temperature conditions).

[0074] The initial capacity and capacity after cycling of capacitor samples No. 1 to No. 5 manufactured according to the above steps are tested, and the data are shown in the following table:

[0075]

[0076] As can be seen from Table 1-7, the average initial internal resistance of the product prepared in Example 7 is 1.43mΩ, which is 95.07% of the designed ESR; the average initial capacity is 934.24mAh, which is 109.9% of the designed capacity. After 20,000 cycles, the average internal resistance change factor is 1.16, the average capacity after the cycle is 905.94mAh, and the average capacity retention rate is 96.97%. Example 8

[0077] Make a 850mAh lithium-ion capacitor with a designed ESR of 1.5mΩ.

[0078] S1: Same as Example 3.

[0079] S2: At room temperature, the capacitor was formed using an Enzhi capacitance tester. The parameters were set as follows: first, charge at a constant current of 0.5C (0.425A) to a rated voltage of 4.0V, charge at a constant voltage for 2 hours, and finally discharge at a constant current of 0.5C (0.425A) to a minimum operating voltage of 2.2V, let stand for 10 minutes, and repeat the above steps 3 times.

[0080] S3: First charge at a constant current of 0.5C (0.425A) to a rated voltage of 4.0V, charge at a constant voltage for 20h, then discharge at a constant current of 2.5C (2.125A) to 3.5V, place at a high temperature of 40°C for 48 hours with a pressure of 0.5Mpa, then place at a pressure of 1.2Mpa for 96 hours (a total of 144 hours under high temperature conditions).

[0081] The initial capacity and capacity after cycling of capacitor samples No. 1 to No. 5 manufactured according to the above steps are tested, and the data are shown in the following table:

[0082]

[0083] As can be seen from Tables 1-8, the average initial internal resistance of the product prepared in Example 8 is 1.43mΩ, which is 95.07% of the designed ESR; the average initial capacity is 931.62mAh, which is 109.6% of the designed capacity. After 20,000 cycles, the average internal resistance change factor is 1.13, the average capacity after the cycle is 892.4mAh, and the average capacity retention rate is 95.79%.

[0084] Comparative Example 1

[0085] Make a 270mAh lithium-ion capacitor with a designed ESR of 4.3mΩ.

[0086] Except that no pressure is applied during high temperature storage, everything else is the same as Example 3.

[0087] The initial capacity and capacity after cycling of capacitor samples No. 1 to No. 5 manufactured according to the above steps are tested, and the data are shown in the following table:

[0088]

[0089] As can be seen from Table 1-9, the average initial internal resistance of the product prepared in Comparative Example 1 is 5.56mΩ, which is 129.3% of the designed ESR; the average initial capacity is 258.8mAh, which is 95.87% of the designed capacity. After 20,000 cycles, the average internal resistance change factor is 2.89, the average capacity after the cycle is 251.98mAh, and the average capacity retention rate is 87.24%.

[0090] Comparative Example 2

[0091] Make a 270mAh lithium-ion capacitor with a designed ESR of 4.3mΩ.

[0092] Except that the pressure applied at high temperature is 2.0 MPa, everything else is the same as Example 3.

[0093] The initial capacity and capacity after cycling of capacitor samples No. 1 to No. 5 manufactured according to the above steps are tested, and the data are shown in the following table:

[0094]

[0095] As can be seen from Table 1-10, the average initial internal resistance of the product prepared in Comparative Example 2 is 4.39mΩ, which is 102.1% of the designed ESR; the average initial capacity is 255.3mAh, which is 94.54% of the designed capacity. After 20,000 cycles, the average internal resistance change factor is 1.12, the average capacity after the cycle is 218.02mAh, and the average capacity retention rate is 85.42%.

[0096] Comparative Example 3

[0097] Make a 600mAh lithium-ion capacitor with a designed ESR of 2.2mΩ.

[0098] S1: Same as Example 3.

[0099] S2: At room temperature, the capacitor is formed using the Enzhi capacitance tester. The parameters are set as follows: first charge at a constant current of 1C (0.3A) to a rated voltage of 3.8V, the constant voltage charging time is 3 hours, and finally discharge at a constant current of 1C to a minimum operating voltage of 2.2V, let it stand for 5 minutes, and repeat the above steps 3 times.

[0100] S3: First charge at a constant current of 1C (0.3A) to a rated voltage of 3.8V, charge at a constant voltage for 22h, then discharge at a constant current of 5C (1.5A) to a voltage of 3.5V, place at a high temperature of 45°C for 48 hours, apply a pressure of 0.5Mpa, and then apply a pressure of 1.2Mpa for 48 hours (a total of 96 hours under high temperature conditions).

[0101] The initial capacity and capacity after cycle of the manufactured capacitor were tested, and the data are shown in the following table:

[0102]

[0103] As can be seen from Table 1-11, the average initial internal resistance of the product prepared in Comparative Example 3 is 3.29mΩ, which is 149.55% of the designed ESR; the average initial capacity is 561.4mAh, which is 93.57% of the designed capacity. After 20,000 cycles, the average internal resistance change factor is 1.42, the average capacity after the cycle is 485.76mAh, and the average capacity retention rate is 86.52%.

[0104] By comparing Examples 1-8 with Comparative Examples 1-3, it is shown that the electrochemical lithium insertion and formation method of the lithium ion capacitor of the present invention effectively improves the basic performance and cycle life of the product by high temperature and pressure, and can achieve large-scale production.

[0105] The embodiments of the present invention are described in detail above, but the contents described are only preferred embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A method for electrochemical lithium insertion and formation of a lithium ion capacitor, characterized in that: It includes the following three stages: The first stage, high temperature lithium insertion: The lithium ion capacitor is stored in a high temperature environment with a temperature of T1, so that the electrolyte fully infiltrates the pole piece, and the metal lithium begins to be embedded in the graphite material of the negative electrode. The potential change during the lithium embedding process is monitored in real time. When the remaining amount of metal lithium is less than 40%, the storage is terminated. At this time, the total high temperature storage time is t1, during which increasing pressures of P1, P2, and P3 are applied in sequence every 24 hours, and the boost pressure P4 is applied for the remaining time; pressures P1 and P2 compress the lithium ion capacitor and shorten the distance between the positive electrode and the negative electrode, accelerate the penetration and reaction of the electrolyte in the electrode, and pressures P3 and P4 promote gas discharge, and then perform secondary sealing after exhaust; pressure P1 is 0.1-0.3Mpa, pressure P2 is 0.3-0.5Mpa, pressure P3 is 0.8-1.2Mpa, and pressure P4 is 1.2-1.5Mpa; The second stage, formation: At room temperature, first charge with constant current I1 to rated voltage U R , constant voltage charging time is t2, and finally discharges to the minimum working voltage U with constant current I1 min , let stand for t3, repeat the above steps 3 to 5 times; The constant current I1 is 0.2~0.5C, the rated voltage U R The constant voltage charging time t2 is 2 to 5 hours, and the minimum working voltage U min is 2.0~2.2V, and the standing time t3 is 1~10 minutes; Stage 3, Aging: Before aging, charge with constant current I1 to the maximum working voltage U R , and then after constant voltage charging time t4, discharge with constant current I2 to voltage U1, and then store in a high temperature environment with temperature T2 for time t5. During the storage in the high temperature environment for 24 to 48 hours, pressure P2 is applied, and increasing pressure P3 is applied for the remaining time. At this time, lithium insertion is completed by 98%; The constant voltage charging time t4 is 20 to 25 hours, the constant current I2 is 1 to 4C, the voltage U1 is 3.5 to 3.7V, the temperature T2 is 40 to 45°C, and the storage time t5 is 96 to 192 hours.

2. The electrochemical lithium insertion and formation method of a lithium ion capacitor according to claim 1, characterized in that: In the first stage, the temperature T1 is 40 to 50° C. and the storage time t1 is 96 to 120 hours.

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