Gel lithium ion battery preparation method and gel lithium ion battery

Abstract

The invention discloses a preparation method of a gel lithium ion battery and the gel lithium ion battery, and the preparation method of the gel lithium ion battery comprises the following steps: injecting a first electrolyte into a battery cell to obtain the battery cell after injection; carrying out preliminary infiltration on the battery cell after liquid injection, and then carrying out formation to obtain a formed battery cell; the formed battery cell is weighed, and the liquid loss amount of the formation process is obtained; according to the liquid loss amount and the theoretical liquid injection amount of the formation process, a second electrolyte is injected into the formed battery cell to obtain a liquid-supplemented battery cell, and the second electrolyte is composed of a gel polymer matrix, an initiator, an organic solvent and a lithium salt; and infiltrating the battery cell after the liquid supplementation again, and gelatinizing the second electrolyte after the second electrolyte is infiltrated again. According to the invention, the initiator is introduced during subsequent fluid infusion, gel is formed in the heating process, and in the gel forming process, due to the fact that reducing gas in the battery is removed by components, gel forming is uniform, the thickness of a battery cell is controllable, the battery cell is not easy to swell, and the battery performance is better.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and more specifically to a preparation method of a gel lithium ion battery and a gel lithium ion battery. Background Art

[0002] Lithium-ion batteries have the advantages of high energy density, environmental friendliness, no memory effect, long cycle life, and low self-discharge. They are widely used in electronics, automobiles, aerospace, military and other fields. With the in-depth use of lithium-ion batteries in people's lives, their safety has also been increasingly valued. Most of the lithium-ion batteries currently used in commercial applications are liquid. Due to the hidden dangers of liquid leakage and flammability, a safer lithium-ion battery system is urgently needed to be developed. Gel lithium-ion batteries are favored by more and more companies because their internal electrolyte is in a colloidal state, has no fluidity, and does not have the risk of leakage, which reduces safety hazards. With the injection of electrolyte, the polymer gel is thermally polymerized at a certain temperature to form a gel battery. After gelation, lithium-ion batteries may have gas production problems during formation. After gelation, the surface of the pole piece is wrapped by the glue layer, making it difficult to completely eliminate the gas generated during formation, which will hinder the formation of a tight and uniform solid electrolyte membrane (SEI membrane), causing lithium precipitation, black spots and other problems, thereby affecting the battery capacity, cycle performance, rate performance and other battery performance. Therefore, it is a technical problem that needs to be solved in this field. Summary of the invention

[0003] In view of this, the present invention provides a method for preparing a gel lithium-ion battery, which is used to solve the problem of gas generation in the prior art after the lithium-ion battery is formed into a gel. After the gel, the surface of the electrode is wrapped by the gel layer, making it difficult to completely remove the gas generated in the formation, which will hinder the formation of a tight and uniform solid electrolyte membrane (SEI membrane), causing lithium precipitation, black spots and other problems.

[0004] In a first aspect, the present invention provides a method for preparing a gel lithium ion battery, comprising:

[0005] Injecting a first electrolyte into the battery cell to obtain an injected battery cell, wherein the first electrolyte comprises a gel polymer matrix, a lithium salt and an organic solvent;

[0006] Preliminarily wetting the battery cell after liquid injection, and then forming it to obtain a formed battery cell;

[0007] Weighing the formed battery cell to obtain the liquid loss during the formation process;

[0008] Injecting a second electrolyte into the formed battery cell according to the amount of liquid loss and the theoretical amount of liquid injection in the formation process to obtain a battery cell after liquid replenishment, wherein the second electrolyte comprises a gel polymer matrix, an initiator, an organic solvent and a lithium salt;

[0009] The battery cell after replenishment is soaked again, and the second electrolyte after soaking is made into gel.

[0010] Optionally, the step of re-wetting the battery cell after replenishment and forming the re-wetted second electrolyte into a gel comprises:

[0011] The re-wetted battery cell is heated in an oven to form a gel lithium-ion battery. The heating temperature ranges from 60°C to 90°C and the vacuum degree ranges from -85KPa to -90KPa.

[0012] Optionally, the added amount of the second electrolyte is not less than 10% of the theoretical injection amount.

[0013] Optionally, the amount of the second electrolyte added is 20±5% of the theoretical injection amount.

[0014] Optionally, the mass fraction of the gel polymer matrix in the second electrolyte is 5±0.2% of the theoretical injection volume, and the mass fraction of the initiator is 0.5±0.05% of the theoretical injection volume.

[0015] Optionally, the amount of liquid loss in the formation process is equal to the difference between the weight of the battery cell after initial infiltration and the weight of the battery cell after formation.

[0016] Optionally, the step of performing preliminary wetting and subsequent formation on the liquid-injected battery cell to obtain the formed battery cell comprises:

[0017] Charging at a constant current of 0.05C to 0.2C, the charging time range is 17min to 60min, the charging cut-off voltage is 3.5V to 3.8V, and the vacuum range is -30kpa to -70kpa;

[0018] The battery is charged at a constant current of 0.33C to 0.1C, the charging time range is 35min to 80min, and the charging cut-off voltage is 3V to 4.2V.

[0019] Optionally, before the first electrolyte is injected into the battery cell to obtain the injected battery cell, the method further comprises:

[0020] The battery cell is baked, and during the battery cell baking process, ventilation is performed once at a preset interval to obtain a baked battery cell.

[0021] Optionally, the theoretical liquid injection amount is obtained according to the rated capacity of the battery cell and the liquid injection coefficient.

[0022] In a second aspect, the present application provides a gel lithium ion battery, which is prepared using the above-mentioned gel lithium ion battery preparation method.

[0023] Compared with the prior art, the gel lithium ion battery preparation method and gel lithium ion battery provided by the present invention achieve at least the following beneficial effects:

[0024] The invention provides a preparation method of a gel lithium ion battery and a gel lithium ion battery. The preparation method of the gel lithium ion battery comprises: injecting a first electrolyte into a battery core to obtain a battery core after injection, wherein the first electrolyte consists of a gel polymer matrix, a lithium salt and an organic solvent; performing preliminary infiltration on the battery core after injection and then forming the battery core after injection to obtain a formed battery core; weighing the formed battery core to obtain a liquid loss amount in the forming process; injecting a second electrolyte into the formed battery core according to the liquid loss amount in the forming process and a theoretical liquid injection amount to obtain a battery core after liquid replenishment, wherein the second electrolyte consists of a gel polymer matrix, an initiator, an organic solvent and The invention discloses a method for preparing a lithium-ion battery having a plurality of electrolytes, wherein the battery cell is re-infiltrated with the second electrolyte and the initiator of the gel polymer matrix is ​​not added during the formation process, and the gel is not formed during the formation process, so that the problem that the battery gas is not easily extracted after the gel is formed can be avoided. The initiator is introduced during the subsequent re-infusion, and the gel is formed during the heating process. During the gel process, the reducing gas inside the battery has been excluded by the components, so the gel is uniform, the thickness of the battery cell is controllable, the battery cell is not easy to swell, and the battery performance is better. In the subsequent operation, the battery cell does not need to be separated from the first electrolyte for formation, so as to improve the preparation efficiency of the gel lithium-ion battery.

[0025] Of course, any product implementing the present invention does not necessarily need to achieve all of the technical effects described above at the same time.

[0026] Further features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0028] Figure 1 The present invention is a schematic diagram of the process of preparing a gel lithium-ion battery. DETAILED DESCRIPTION

[0029] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless otherwise specifically stated.

[0030] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0031] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0032] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0033] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0034] See also Figure 1 As shown, Figure 1 : is a schematic diagram of a process for preparing a gel lithium-ion battery provided by the present invention. This embodiment provides a method for preparing a gel lithium-ion battery, comprising the following steps:

[0035] Step 101: injecting a first electrolyte into a battery cell to obtain an injected battery cell, wherein the first electrolyte comprises a gel polymer matrix, a lithium salt and an organic solvent.

[0036] The gel polymer matrix in the above step 101 refers to the introduction of functional monomers on the basis of polyurethane resin. The functional monomers may be acrylic monomers, and the polyurethane resin may be unsaturated polyurethane.

[0037] The above-mentioned polyurethane resin is a polymer material made by the reaction of polyol and isocyanate, and has good elasticity, wear resistance and corrosion resistance. Functional monomers such as acrylic monomers are introduced on the basis of polyurethane resin. Acrylic monomers have active double bonds and can participate in polymerization reactions to form cross-linked structures, thereby enhancing the mechanical strength and heat resistance of the material.

[0038] By introducing acrylic monomers, more cross-linking points can be formed between the molecular chains of polyurethane resin, making the entire material more compact and stable. This cross-linking structure not only improves the mechanical properties of the material, but also improves its solvent resistance and aging resistance.

[0039] Optionally, the gel polymer matrix is ​​80% of the total added amount of the first electrolyte. The gel polymer matrix serves as the main part of the electrolyte. The structure of the gel polymer matrix can effectively reduce the leakage risk of the first electrolyte, thereby reducing the risk of fire or explosion of the gel lithium-ion battery, and can significantly improve the cycle life and stability of the battery. At the same time, it can accommodate more lithium salts, thereby improving the ionic conductivity of the first electrolyte, and then improving the energy density and power density of the gel lithium-ion battery.

[0040] The above-mentioned lithium salt includes one or more combinations of lithium hexafluorophosphate (LiPF6), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), wherein lithium hexafluorophosphate (LiPF6) has good ionic conductivity and electrochemical stability, and can form a stable SEI film on the surface of the electrode material, thereby improving the cycle performance of the battery. Lithium bis(fluorosulfonyl)imide (LiFSI) has a high electrochemical stability window and good thermal stability. It can maintain stable performance under high temperature conditions and is suitable for lithium batteries in high temperature environments. Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) has high electrical conductivity and good thermal stability. It can maintain stable performance over a wide temperature range and is suitable for lithium batteries under various temperature conditions.

[0041] The above-mentioned LiPF6 and LiTFSI can be added at a certain concentration. If the concentration ratio between the above-mentioned LiPF6 and LiFSI is too high, the gelation rate will be accelerated, which is not conducive to actual production; if the concentration ratio between the above-mentioned LiPF6 and LiFSI is too low, it may cause insufficient conductivity, affecting the charge and discharge performance of the gel lithium-ion battery. In this embodiment, the concentration ratio between LiPF6 and LiFSI ranges from 0.133 to 5, which can not only improve the conductivity and ion migration number, but also make the insertion and extraction of lithium ions smoother during the charge and discharge process, reduce the damage to the electrode structure, and extend the service life of the battery. It can also slow down the gelation rate, which is conducive to actual production and has better chemical stability. Specifically, the concentration ratio between LiPF6 and LiFSI can be 0.133, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5.

[0042] It should be noted that: the above-mentioned gel polymer matrix, lithium salt and organic solvent are mixed to form a liquid solution. If an initiator is added under conditions of high temperature or ultraviolet light irradiation to cause a chemical cross-linking reaction in the gel polymer matrix to form a gel-like three-dimensional network structure, in order to ensure that the SEI film generated by the chemical reaction is stable and dense and the degassing is thorough, therefore, in the present embodiment, no initiator is introduced into the first electrolyte to prevent the polymer matrix from gelling.

[0043] Optionally, the concentration range of the above-mentioned LiPF6 is 0.2M~1M, the concentration of LiPF6 can be 0.2M, 0.4M, 0.6M, 0.8M or 1M, the concentration range of LiTFSI is 0.2M~1.5M, the concentration of LiTFSI can be 0.2M, 0.5M, 0.8M, 1.1M, 1.2M or 1.5M.

[0044] The organic solvent includes one or more combinations of fluoroethylene carbonate (FEC), ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC).

[0045] The above-mentioned fluoroethylene carbonate (FEC) can improve the performance of the electrolyte, and increase the safety and cycle life of the battery; ethylene carbonate (EC) has a high dielectric constant and chemical stability, and can form dense decomposition products on the surface of graphite-like carbon materials, which is beneficial to the embedding and extraction of lithium ions.

[0046] Propylene carbonate (PC) can maintain high conductivity at low temperatures and helps to inhibit the decomposition of the electrolyte on the graphite electrode, forming a stable SEI film.

[0047] Dimethyl carbonate (DMC) has little odor, strong solubility, and a high conductivity improvement effect on lithium batteries; the mixed use of ethyl methyl carbonate EMC and other solvents can optimize the performance of the electrolyte and meet the different needs of lithium batteries.

[0048] When fluoroethylene carbonate (FEC), ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) are combined, they can be composed in a certain proportion according to actual conditions, and this embodiment does not make specific restrictions on this.

[0049] Optionally, EMC:DMC:PC:FEC=40:20:20:20. The above scheme has a high dielectric constant and low viscosity, which is conducive to the conduction and migration of lithium ions.

[0050] Step 103, preliminarily wetting the battery cell after the injection, and then forming it to obtain a formed battery cell;

[0051] Specifically, in order to ensure that the first electrolyte quickly infiltrates the interior of the battery cell, the battery cell after injection is evacuated, the vacuum value range is -85KPa to -90KPa, the pressure holding time is 5 minutes, and the number of cycles is 2 to 3 times.

[0052] The purpose of vacuuming the battery cell after injection is to reduce the resistance generated by the air during the injection process, which is conducive to the flow and infiltration of the first electrolyte, ensuring that the first electrolyte can fully and evenly infiltrate the positive and negative electrode materials and diaphragms of the gel lithium-ion battery; the above vacuum value can ensure that the air in the injector is fully removed, while avoiding damage to the injector caused by excessive decompression; the pressure holding time is set to 5 minutes, which is enough for the first electrolyte to fully infiltrate the positive and negative electrode materials and diaphragms of the gel lithium-ion battery in a vacuum environment, thereby improving the injection effect of the gel lithium-ion battery. Multiple cycles can further enhance the infiltration effect of the first electrolyte and ensure the stability and consistency of lithium-ion performance.

[0053] After the injection is completed, the battery cell is sealed with glue nails. The battery cell is placed at a temperature of 25°C for 48 hours to allow the injection liquid to fully penetrate the battery cell and ensure that the first electrolyte is evenly distributed in all parts of the battery cell, thereby restoring the normal use effect of the battery cell.

[0054] After the injection and suspension are completed, the injected battery cells are transferred to the dew point room; the injected battery cells are first clamped with a restraint clamp, and the suspended battery cells are placed on the cabinet for formation. Formation is a key step in the production of gel lithium-ion batteries. Its purpose is to form a stable solid electrolyte interface (SEI) film on the surface of the negative electrode through charging and discharging. The SEI film is crucial to the performance of the battery, which can prevent the first electrolyte from directly contacting the negative electrode material, reduce the self-discharge of the gel lithium-ion battery, and improve the safety performance of the gel lithium-ion battery.

[0055] The formation method is as follows:

[0056] Charge at a constant current of 0.05C to 0.2C, with a charging time range of 17min to 60min, a charging cut-off voltage of 3.5V to 3.8V, 2 to 3 cycles, and a vacuum range of -30kpa to -70kpa;

[0057] The battery is charged at a constant current of 0.33C to 0.1C, the charging time range is 35min to 80min, the charging cut-off voltage is 3V to 4.2V, and the cycle is 2 to 3 times. The vacuum degree range is -30kPa to -85kPa.

[0058] The specific process of the present embodiment is as follows in Table 1:

[0059] Table 1 Formation process

[0060] Step No. Step Type Current / A Time / min Voltage / v Temperature / ℃ Vacuum degree / kpa 1 Shelf 5 25 -85 2 Constant current charging 0.05C 60 3.5 25 -30 3 Shelf 1 25 -30 4 Constant current charging 0.1C 20 3.5 25 -50 5 Shelf 1 25 -50 6 Constant current charging 0.2C 17 3.8 25 -70 7 Shelf 1 25 -70 8 Constant current charging 0.33C 80 3.8 25 -85 9 Shelf 1 25 -85 10 Constant current charging 0.1C 75 4.2 25 -85 11 Shelf 1 25 -85 12 Constant current discharge 0.33C 35 3 25 -85 13 Shelf 5 25 -85

[0061] After the formation is completed, the formed battery cell is subjected to high-temperature aging. The inventors found that if the temperature of high-temperature aging is too high, the decomposition of the components in the first electrolyte will be aggravated, resulting in loss of electrode capacity, and even abnormal gas production and self-discharge of the formed battery cell will be aggravated; if the temperature of high-temperature aging is too low, although the SEI film formed may be more dense and stable, the reaction rate will slow down, the formation time will be extended, and it may be unfavorable for the aging effect, affecting the overall performance of the gel lithium-ion battery. In this embodiment, the temperature range of high-temperature aging is 42°C to 48°C to ensure that the formed battery cell can form a stable and good SEI film, while avoiding the occurrence of adverse phenomena such as abnormal gas production and aggravated self-discharge; the time of high-temperature aging can be 48h, so that the first electrolyte is fully infiltrated, and some active components in the positive and negative active materials are inactivated through certain reactions, so that the overall performance of the gel lithium-ion battery is more stable. Specifically, the temperature of high-temperature aging can be 42°C, 45°C or 48°C.

[0062] The temperature in the above Table 1 can be adjusted according to actual conditions.

[0063] Step 105, weighing the formed battery cell to obtain the liquid loss in the formation process;

[0064] Specifically, the amount of liquid loss in the formation process is equal to the difference between the weight of the battery cell after initial infiltration and the weight of the battery cell after formation, that is, the amount of liquid loss in the formation process can be obtained by subtracting the weight before formation from the weight after formation.

[0065] The weighing of the formed cell is carried out immediately after the formation process is completed to ensure the accuracy of the measurement results. By comparing the weight of the cell before and after formation, the liquid loss of the cell can be calculated, and then the quality and performance of the cell can be evaluated.

[0066] Step 107, injecting a second electrolyte into the formed battery cell according to the amount of liquid loss in the formation process and the theoretical amount of liquid injection to obtain a battery cell after liquid replenishment, wherein the second electrolyte comprises a gel polymer matrix, an initiator, an organic solvent and a lithium salt;

[0067] Specifically, during the formation process, the electrolyte inside the battery cell after injection may be consumed. Therefore, in order to ensure that the amount of electrolyte inside the battery cell after injection reaches the optimal state, it is necessary to replenish the electrolyte through secondary injection. Secondary injection also helps to adjust the electrolyte concentration and distribution inside the battery, thereby further optimizing the performance of the gel lithium-ion battery.

[0068] The amount of the second electrolyte is determined according to the amount of liquid loss in the formation process and the theoretical amount of liquid injection, which can ensure that after the liquid is replenished, the amount of the second electrolyte in the battery cell after formation is neither too much nor too little, thereby achieving the best performance state.

[0069] The amount of the second electrolyte added is not less than 10% of the theoretical injection amount, ensuring that the gel lithium-ion battery can obtain at least a certain amount of the second electrolyte to meet its basic electrochemical performance and safety requirements.

[0070] Optionally, the theoretical injection volume is obtained according to the rated capacity of the battery cell and the injection coefficient, specifically:

[0071] Theoretical injection volume = rated capacity of battery cell × injection coefficient. By setting the above injection coefficient reasonably, it can ensure that the second electrolyte is distributed more evenly in the battery cell, reducing the degradation of battery performance caused by insufficient or excessive electrolyte. It should be noted that the selection of the injection coefficient also takes into account the safety of the battery. The appropriate injection volume can ensure that the heat generated by the battery cell during the charging and discharging process is effectively dissipated, reducing the risk of thermal runaway of the gel lithium-ion battery. In this embodiment, the injection coefficient can be 1.9.

[0072] A specific example is as follows: for a 140Ah square shell battery cell with a group margin of 90% and a 9-series high-nickel silicon-carbon system, the filling coefficient is set to 1.9, and the theoretical filling amount should be 1.9×140=266g. According to the principle that the amount of the second electrolyte to be filled should not be less than 10% of the theoretical filling amount, no less than 26.6g of the second electrolyte should be added, and the shelf temperature range is 25℃~45℃, such as 25℃, 30℃, 35℃, 40℃ or 45℃.

[0073] Furthermore, the amount of the second electrolyte added is 20±5% of the theoretical injection amount, which means that the actual amount of the second electrolyte added should be within the range of 20% of the theoretical injection amount and fluctuate by 5%, that is, 15% to 25%, which not only ensures the stability of the battery performance, but also leaves a certain margin to adapt to fluctuations and differences in the production process. The amount of the second electrolyte added can be 15%, 18%, 21% or 25% of the theoretical injection amount.

[0074] The second electrolyte is composed of a gel polymer matrix, an initiator, an organic solvent and a lithium salt. The components of the gel polymer matrix in the second electrolyte are the same as those in the first electrolyte. For example, the gel polymer matrix also refers to the introduction of functional monomers on the basis of polyurethane resin. The functional monomers can be acrylic monomers, and the polyurethane resin can be unsaturated polyurethane. The components of the organic solvent in the second electrolyte are the same as those in the first electrolyte. The components of the lithium salt in the second electrolyte are the same as those in the first electrolyte.

[0075] The gel polymer matrix in the above-mentioned second electrolyte can be 20% of the total added amount of the second electrolyte, so as to reduce the amount of gel factor while ensuring that the gel electrolyte forms a stable polymer network structure, thereby reducing costs, and also helping to reduce the viscosity of the gel electrolyte, so that the penetration and distribution of the electrolyte in the battery are more uniform, thereby improving the electrochemical performance of the battery.

[0076] The above-mentioned initiator can be selected from azobisisobutyronitrile (AIBN), which will decompose rapidly when heated to a certain temperature, releasing nitrogen and forming free radicals. These free radicals can initiate polymerization reactions in gel lithium-ion battery materials, help form a stable gel structure, thereby improving the cycle stability and capacity retention rate of gel lithium-ion batteries, and can be dissolved in a variety of organic solvents, which provides convenience for its uniform dispersion in the preparation process of gel lithium-ion batteries, and can also adjust the molecular weight, distribution and cross-linking degree of the polymer. In gel lithium-ion batteries, this helps to optimize the electrolyte structure of gel lithium-ion batteries, improve the ion conduction efficiency, and thus improve the electrochemical performance of gel lithium-ion batteries.

[0077] Optionally, the mass fraction of the gel polymer matrix in the above-mentioned second electrolyte is 5±0.2% of the theoretical injection amount. By accurately controlling the mass fraction of the gel polymer matrix in the second electrolyte, not only the composition and structure of the electrolyte can be optimized, thereby improving the energy density, power density and cycle life of the gel lithium-ion battery, but also it helps to form a more stable and uniform electrolyte layer, which can effectively inhibit the occurrence of thermal runaway during the operation of the gel lithium-ion battery and improve the safety of the gel lithium-ion battery. At the same time, it can ensure that a protective gel layer can be quickly formed when needed, thereby improving the overall safety of the battery.

[0078] The mass fraction of the initiator is 0.5±0.05% of the theoretical injection volume. By precisely controlling the mass fraction of the initiator, not only can the reaction rate be effectively controlled during the secondary filling to avoid the gel lithium-ion battery performance being unstable or reduced due to an overly fast or slow reaction, but also the gel lithium-ion battery can be ensured to maintain a stable reaction rate during the charge and discharge process, thereby improving the safety of the battery, while improving the ion conductivity and electrochemical properties of the gel lithium-ion battery, so that the gel lithium-ion battery has a higher energy density, a longer cycle life and better charge and discharge performance.

[0079] The above-mentioned second electrolyte can be manually filled by mechanical tooling or by a fully automatic filling machine. To ensure that the electrolyte quickly infiltrates the battery cell, the battery cell is evacuated after filling, and the vacuum value is -85KPa to -90KPa. The pressure holding time is 5 minutes and the number of cycles is 2 to 3 times. After the filling is completed, it is packaged with glue nails to prevent leakage.

[0080] Step 109, re-infiltrating the battery cell after replenishment, and gelling the re-infiltrated second electrolyte. For example, the re-infiltrated battery cell is heated in an oven to form a gel lithium-ion battery. The heating temperature range is 60° C. to 90° C., and the vacuum range is -85 KPa to -90 KPa.

[0081] Specifically, the battery cell after rehydration is immersed at 25°C for 6 hours. After the immersion is completed, the gel lithium-ion battery is transferred to a dew point room, the gel lithium-ion battery is first clamped with a clamp, and the gel lithium-ion battery with the clamp is placed in an oven at a high temperature of 60°C to 90°C for 24 hours to allow the gel electrolyte to gel.

[0082] The inventor found that the reaction temperature of azobisisobutyronitrile (AIBN) is 60-120°C. If the reaction temperature of azobisisobutyronitrile (AIBN) is too high, it may cause rapid gelation, gas production cannot be exhausted, and battery swelling occurs. In this embodiment, the reaction temperature of azobisisobutyronitrile (AIBN) is 60°C to 90°C for high-temperature gelation aging, mainly considering that there may be high-temperature aging gas production during the gelation process, and the high temperature of 60°C to 90°C is close to the lower limit of the reaction temperature of azobisisobutyronitrile (AIBN), and the gelation reaction rate is slow. Since the decomposition rate of azobisisobutyronitrile (AIBN) in this temperature range is relatively low, the number of free radicals generated is limited, so the speed of the polymerization reaction will also be slowed down accordingly. This slower reaction rate helps the gas to be slowly discharged from the pole piece, reduces the internal pressure caused by rapid polymerization, and is beneficial to the safety and stability of the battery. For example, the temperature of high-temperature shelving for 24 hours can be 60°C, 65°C, 70°C, 75°C or 80°C. Preferably, the temperature range of the high-temperature storage for 24 hours may be 65° C. to 85° C.

[0083] In an optional embodiment, before injecting the first electrolyte into the battery cell to obtain the injected battery cell, the method further includes:

[0084] The battery cells are baked, and during the baking process, ventilation is performed once at a preset time interval to obtain baked battery cells.

[0085] Specifically, placing the assembled qualified battery cells in a vacuum oven for baking can remove moisture and volatile impurities inside the qualified battery cells, so as to improve the purity and performance stability of the gel lithium-ion battery.

[0086] During the baking process of the battery cells, the gas composition in the oven may change as the water evaporates and impurities are removed. Regular ventilation can introduce fresh air, maintain the stability and consistency of the baking environment, help to better remove moisture and impurities in the battery cells, and can also promptly discharge harmful or unnecessary gases to avoid their accumulation in the oven and adverse effects on the battery cells.

[0087] After baking, the moisture content of the positive and negative electrode plates needs to be measured in a dew point room to ensure that the moisture content of the positive and negative electrode plates is qualified. For example, the moisture content of the positive and negative electrode plates must be less than 300ppm (one part per million) before the first electrolyte can be injected into the battery cell.

[0088] Optionally, the preset time may be 3 hours, the baking temperature may be 95° C., and the baking time may be 48 hours.

[0089] It should be noted that: the present application is first formed and then gelled, that is, no initiator of the gel polymer matrix is ​​added during the formation process, no gel is formed during the formation process, the initiator is introduced during the subsequent fluid replenishment, and gel is formed during the subsequent heating process. During the gelling process, the reducing gas inside the battery has been excluded by the components, the gel is uniform, the thickness of the battery cell is controllable, it is not easy to swell, and the battery performance is better. Specifically, during the formation process, the electrolyte undergoes a reduction reaction at the negative electrode, including solid products formed on the surface of the negative electrode mainly including alkyl lithium carbonate (ROCO2Li), alkoxy lithium (ROLi), lithium carbonate (Li2CO3), LiF, Li2O, LiOH, etc., and these solid products form a SEI film. The gas products include hydrocarbon gases such as C2H4 and inorganic gases such as CO2 and H2. The reducing gas produced by the formation side reaction is fully eliminated by the step negative pressure. The step negative pressure mainly takes into account the large gas production and gas production rate before 3.5V. The gas production at 3.5V reaches more than 90% of the total gas volume. The smaller negative pressure value and the step increase can not only remove gas but also reduce the problem of increased fluid loss caused by excessive negative pressure. During the aging process after the battery is formed, the electrolyte will gradually decompose to form a solid electrolyte interface (SEI) film. The SEI film can protect the electrode surface and prevent further electrolyte decomposition, which will further produce gases similar to those in the formation process. Since no initiator is added during the formation and high-temperature aging process, the gel matrix will not polymerize to form macromolecular chains under the action of the initiator. The gas produced by the reduction reaction between the electrolyte and the negative electrode will have less resistance to pass through the gel electrolyte gap, which will not affect the removal of gas inside the battery in the shell, and avoid the situation where the battery gas is not easy to be extracted after gelation. The initiator is introduced during the subsequent rehydration, and gelation is formed during the high-temperature heating process. During the gelation process, since the reducing gas inside the battery has been eliminated by the components, the gelation uniformity is uniform and the battery performance is better.

[0090] Compared with the prior art, the gel lithium ion battery preparation method provided in this embodiment achieves at least the following beneficial effects:

[0091] The preparation method of the gel lithium ion battery provided in the present embodiment comprises: injecting a first electrolyte into a battery cell to obtain a battery cell after injection, wherein the first electrolyte consists of a gel polymer matrix, a lithium salt and an organic solvent; performing preliminary infiltration on the battery cell after injection and then forming the battery cell after injection to obtain a formed battery cell; weighing the formed battery cell to obtain the amount of liquid loss in the forming process; injecting a second electrolyte into the formed battery cell according to the amount of liquid loss in the forming process and the theoretical amount of liquid injection to obtain a battery cell after liquid replenishment, wherein the second electrolyte consists of a gel polymer matrix, an initiator, an organic solvent and a lithium salt; The battery cell is re-infiltrated, and the second electrolyte after re-infiltration is gelled. By adopting the above scheme, no initiator of the gel polymer matrix is ​​added during the formation process, and no gel is formed during the formation process, which can avoid the problem that the battery gas is difficult to be extracted after gelling. The initiator is introduced during the subsequent fluid replenishment, and gelling is formed during the heating process. During the gelling process, the reducing gas inside the battery has been excluded by the components, and the gelling is uniform, the thickness of the battery cell is controllable, it is not easy to swell, and the battery performance is better. In subsequent operations, the battery cell does not need to be separated from the first electrolyte for formation, so as to improve the preparation efficiency of the gel lithium-ion battery.

[0092] Based on the same inventive concept, the present invention also provides a gel lithium ion battery, which is prepared using the above gel lithium ion battery preparation method.

[0093] This embodiment:

[0094] Taking the 250Ah square shell battery Ni88-SiOX / C system as an example, the group margin is 90%. The shell size of the 250Ah square shell battery is 300mm long, 38.5mm thick, and 110mm wide. The positive electrode is LATP protected Ni88 single crystal, and the negative electrode is SiOX / C composite material. The first electrolyte is a mixture of dimethyl carbonate DMC, propylene carbonate PC, ethyl methyl carbonate EMC, vinyl carbonate EC, a flame retardant (such as triisopropylphenyl phosphate), and a film-forming agent (such as vinylene carbonate VC, fluoroethylene carbonate FEC, vinyl ethylene carbonate VEC, vinyl sulfate DTD, triphenyl phosphite TPPi and propenyl-1,3-sulfonate PST, etc.) in a certain proportion, for example, the organic solvent ratio EMC:DMC:PC:FEC=40:20:20:20, 1% VC+1% DTD+1% PST+0.5% TPPi, and the lithium salt is LiPF6 and LiTFSI added in a certain concentration range, such as the concentration ratio between LiPF6 and LiFSI ranges from 0.133 to 5. The gel polymer matrix is ​​a functional monomer introduced into the polyurethane resin, and the functional monomer is an acrylic monomer, such as tripropylene glycol diacrylate. The initiator in this embodiment can be azobisisobutyronitrile (AIBN). Due to the advantage of azobisisobutyronitrile as a more commonly used free radical initiator, its decomposition temperature (65°C to 85°C) is suitable for most reactions; the primary decomposition rate changes little with different organic solvents and is not easily attacked by free radicals, so the induced decomposition and transfer reactions can be ignored; it can be decomposed by light at a relatively low temperature.

[0095] This embodiment 1:

[0096] 1. After the positive and negative electrodes are tested for moisture, the injection coefficient is 2.24, and the theoretical injection volume is 2.24×250=560g. 420g of the first electrolyte is injected (75% of the theoretical injection volume, and the mass fraction of the gel polymer matrix is ​​4.8% of the theoretical injection volume);

[0097] 2. Evacuate the battery cell after injection to a vacuum value of -85KPa, maintain the pressure for 5 minutes, and cycle 2 to 3 times; after injection, seal it with glue nails. The storage temperature of the gel lithium-ion battery is 25°C and the storage time is 48 hours;

[0098] 3. The upper restraint tooling is formed. The forming process refers to Table 1 above;

[0099] 4. After the formation, age at 42℃ for 48h;

[0100] 5. After high-temperature aging, the amount of liquid lost in the formation process can be obtained by subtracting the weight before formation from the weight after formation. The amount of the second electrolyte added to the gel lithium-ion battery should be: 25% of the theoretical injection amount (calculated here as 25%, it should be 140g, the mass fraction of the gel polymer matrix is ​​4.8% of the theoretical injection amount, in addition, an initiator (such as a thermal initiator) should be introduced, the initiator can be azobisisobutyronitrile (AIBN), and the mass fraction of azobisisobutyronitrile (AIBN) is 0.45% of the theoretical injection amount), plus the calculated amount of liquid lost in the formation process. The 25% of the theoretical injection amount of the liquid replenishment here is determined based on the injection amount of one injection, and the sum of the two is 100% of the theoretical injection amount. It should be noted that the injection amount of one injection of the first electrolyte should not be less than 75%;

[0101] The second electrolyte is filled manually by mechanical tooling or by a fully automatic filling machine. To ensure that the second electrolyte quickly infiltrates the inside of the battery after formation, the battery after filling is evacuated to a vacuum value of -85KPa, the pressure holding time is 5min, and the number of cycles is 2 to 3 times; after filling, it is sealed with glue nails to prevent leakage. Then the battery after filling is immersed at 25℃ for 6h.

[0102] 6. After the soaking is completed, transfer the gel lithium-ion battery to the dew point room, clamp the gel lithium-ion battery with a clamp, and place the gel lithium-ion battery with the clamp in an oven, and place it at a high temperature of 60°C for 24 hours to allow the gel electrolyte to gel. The reaction temperature of azobisisobutyronitrile (AIBN) can be selected at 60°C for high-temperature gel aging.

[0103] 7. After the gelling is completed, the gel lithium-ion battery is taken out and sealed by welding. After the sealing is completed, the gel lithium-ion battery is divided into different capacities.

[0104] After the capacity division is offline, the battery cells after rehydration are randomly selected, and the thickness of the battery cells after rehydration and the battery cell parameters after rehydration are recorded as shown in the following table: the average is 38.50mm (5 points), and the average values ​​of the battery cell parameters capacity, internal resistance, k value and energy density after rehydration are 268.624Ah, 0.5069mΩ, 0.087mV / h and 314.89Wh / kg, as shown in Table 2.

[0105] Table 2 shows the thickness of the battery cell after rehydration and the parameters of the battery cell after rehydration in Example 1

[0106]

[0107] This embodiment 2:

[0108] 1. After the positive and negative electrodes are tested for moisture, the injection coefficient is 2.24, and the theoretical injection volume is 2.24×250=560g. One injection of the first electrolyte is 448g (80% of the theoretical injection volume, and the mass fraction of the gel polymer matrix is ​​5% of the theoretical injection volume);

[0109] 2. Evacuate the battery cell after injection to -80KPa, maintain the pressure for 5 minutes, and cycle 2 to 3 times; after injection, seal it with glue nails. The storage temperature of gel lithium-ion battery is 25℃, and the storage time is 48h;

[0110] 3. The upper restraint tooling is formed. The forming process refers to Table 1 above;

[0111] 4. After the formation, age at 45℃ for 48h;

[0112] 5. After high-temperature aging, the amount of liquid lost in the formation process can be obtained by subtracting the weight before formation from the weight after formation. The amount of the second electrolyte added to the gel lithium-ion battery should be: 20% of the theoretical injection volume (should be 112g, the mass fraction of the gel polymer matrix is ​​5% of the theoretical injection volume, and an initiator (such as a thermal initiator) should be introduced. The initiator can be azobisisobutyronitrile (AIBN), and the mass fraction of azobisisobutyronitrile (AIBN) is 0.5% of the theoretical injection volume), plus the calculated amount of liquid lost in the formation process. Here, 20% of the theoretical injection volume for liquid replenishment is determined based on the injection volume, and the sum of the two is 100% of the theoretical injection volume;

[0113] The second electrolyte is filled manually by mechanical tooling or by a fully automatic filling machine. To ensure that the second electrolyte quickly infiltrates the battery cell after formation, the battery cell after filling is evacuated to a vacuum value of -87.5KPa, the pressure holding time is 5 minutes, and the number of cycles is 2 to 3 times. After the filling is completed, it is sealed with glue nails to prevent leakage. Then the battery cell after filling is immersed at 25℃ for 6 hours.

[0114] 6. After the soaking is completed, transfer the gel lithium-ion battery to the dew point room, clamp the gel lithium-ion battery with a clamp, place the gel lithium-ion battery with the clamp in an oven, and leave it at a high temperature of 75°C for 24 hours to allow the gel electrolyte to gel. The reaction temperature of azobisisobutyronitrile (AIBN) can be selected at 75°C for high-temperature gel aging.

[0115] 7. After the gelling is completed, the gel lithium-ion battery is taken out and sealed by welding. After the sealing is completed, the gel lithium-ion battery is divided into different capacities.

[0116] After the capacity division is offline, the battery cells after rehydration are randomly selected, and the thickness of the battery cells after rehydration and the battery cell parameters after rehydration are recorded as shown in the following table: the average thickness is 38.50mm (5 points), and the average capacity, internal resistance, k value and energy density of the battery cells after rehydration are 270.524Ah, 0.50684mΩ, 0.0852mV / h and 315.4Wh / kg, as shown in Table 3.

[0117] Table 3 shows the thickness of the battery cell after rehydration and the parameters of the battery cell after rehydration in Example 2

[0118]

[0119] This embodiment 3:

[0120] 1. After the positive and negative electrodes are tested for moisture, the injection coefficient is 2.24, and the theoretical injection volume is 2.24×250=560g. 476g of the first electrolyte is injected (85% of the theoretical injection volume, and the mass fraction of the gel polymer matrix is ​​5.2% of the theoretical injection volume);

[0121] 2. Evacuate the battery cell after injection to -90KPa, maintain the pressure for 5 minutes, and cycle 2 to 3 times; after injection, seal it with glue nails. The storage temperature of gel lithium-ion battery is 25℃, and the storage time is 48h;

[0122] 3. The upper restraint tooling is formed. The forming process refers to Table 1 above;

[0123] 4. After the formation, high temperature aging at 48℃ for 48h;

[0124] 5. After high-temperature aging, the amount of liquid lost in the formation process can be obtained by subtracting the weight before formation from the weight after formation. The amount of the second electrolyte added to the gel lithium-ion battery should be: 15% of the theoretical injection volume (should be 112g, the mass fraction of the gel polymer matrix is ​​5.2% of the theoretical injection volume, and an initiator (such as a thermal initiator) should be introduced. The initiator can be azobisisobutyronitrile (AIBN), and the mass fraction of azobisisobutyronitrile (AIBN) is 0.55% of the theoretical injection volume), plus the calculated amount of liquid lost in the formation process. Here, 15% of the theoretical injection volume for liquid replenishment is determined based on the injection volume of one injection, and the sum of the two is 100% of the theoretical injection volume;

[0125] The second electrolyte is filled manually by mechanical tooling or by a fully automatic filling machine. To ensure that the second electrolyte quickly infiltrates the battery cell after formation, the battery cell after filling is evacuated to a vacuum value of -90KPa, the pressure holding time is 5 minutes, and the number of cycles is 2 to 3 times. After filling, it is sealed with glue nails to prevent leakage. Then the battery cell after filling is immersed at 25℃ for 6 hours;

[0126] 6. After the infiltration is completed, transfer the gel lithium-ion battery to the dew point room, first clamp the gel lithium-ion battery with a clamp, and place the gel lithium-ion battery with the clamp in an oven, and leave it at a high temperature of 90°C for 24 hours to allow the gel electrolyte to gel. The reaction temperature of azobisisobutyronitrile (AIBN) can be selected at 90°C for high-temperature gel aging;

[0127] 7. After the gelling is completed, the gel lithium-ion battery is taken out and sealed by welding. After the sealing is completed, the gel lithium-ion battery is divided into different capacities.

[0128] After the capacity division is offline, the battery cells after rehydration are randomly selected, and the thickness of the battery cells after rehydration and the battery cell parameters after rehydration are recorded as shown in the following table: the average thickness is 38.50mm (5 points), and the average capacity, internal resistance, k value and energy density of the battery cells after rehydration are 270.11Ah, 0.50674mΩ, 0.086mV / h and 315.46Wh / kg, as shown in Table 3.

[0129] Table 4 shows the thickness of the battery cell after rehydration and the parameters of the battery cell after rehydration in Example 3

[0130]

[0131] Comparative Example

[0132] Taking the 250Ah square shell battery Ni88-SiOX / C system as an example, the group margin is 90%, the battery shell size is 300mm long, 38.5mm thick, and 110mm wide. The positive electrode is LATP-protected Ni88 single crystal, and the negative electrode is SiOX / C compliant material. The electrolyte is DMC, PC, EMC, EC, flame retardant (such as triisopropylphenyl phosphate), and film-forming agent (such as VC, FEC, VEC, DTD, TPPi, PST, etc.) mixed in a certain proportion, such as the organic solvent ratio EMC: DMC: PC: FEC = 40: 20: 20: 20, 1% VC + 1% DTD + 1% PST + 0.5% TPPi; the lithium salt is LiPF6 and LiTFSI added in a certain concentration, such as LiPF6 is 0.2M~1M, and LiTFSI is 0.2M~1.5M. The gel is a polyurethane resin in which a functional monomer is introduced. The functional monomer is an acrylic monomer, such as tripropylene glycol diacrylate, and the initiator is azobisisobutyronitrile (AIBN).

[0133] Comparative Example 1:

[0134] 1. After the electrode moisture test is qualified, the injection coefficient is 2.24, and the theoretical injection volume is 2.24×250=560g. One injection of electrolyte is 448g (75% of the theoretical injection volume, the mass fraction of the gel polymer monomer is 4.8% of the theoretical injection volume, and initiator such as azobisisobutyronitrile (AIBN) is introduced, and the mass fraction of azobisisobutyronitrile (AIBN) is 0.45% of the theoretical injection volume);

[0135] 2. Evacuate the battery cell after injection to a vacuum value of -85KPa, maintain the pressure for 5 minutes, and cycle 2 to 3 times; after injection, seal with glue nails, and place the battery at a temperature of 25°C for 48 hours;

[0136] 3. The upper restraint tooling is formed. Please refer to Table 5 below for the formation system;

[0137] Table 5 shows the chemical process

[0138] Step No. Step Type Current / A Time / min Voltage / v Temperature / ℃ Vacuum degree / kpa 1 Shelf 5 25 -85 2 Constant current charging 0.05C 60 3.5 25 -85 3 Shelf 1 25 -85 4 Constant current charging 0.1C 20 3.5 25 -85 5 Shelf 1 25 -85 6 Constant current charging 0.2C 17 3.8 25 -85 7 Shelf 1 25 -85 8 Constant current charging 0.33C 80 3.8 25 -85 9 Shelf 1 25 -85 10 Constant current charging 0.1C 75 4.2 25 -85 11 Shelf 1 25 -85 12 Constant current discharge 0.33C 35 3 25 -85 13 Shelf 5 25 -85

[0139] 4. After the formation, age at 57℃ for 48h. During the aging process, under the action of the initiator, the gel polymer monomers accelerate polymerization to form ion channels;

[0140] 5. After aging, the amount of electrolyte added to the battery should be: 25% of the theoretical injection amount (should be 140g, the mass fraction of the gel polymer monomer is 4.8% of the theoretical injection amount);

[0141] 6. After the infiltration is completed, the sealing welding is carried out, and after the packaging is completed, the battery is transferred to the dew point room;

[0142] 7. Take out the battery and send it to the capacity dividing cabinet for capacity dividing.

[0143] The cell thickness and cell parameters after the capacity division is offline are shown in the following table. The average value is 38.71mm (5 points). The average values ​​of cell capacity, internal resistance, k value and energy density are 265.86Ah, 0.5165mΩ, 0.094mV / h and 310.624Wh / kg, respectively, as shown in Table 6.

[0144] Table 6 shows the cell thickness and cell parameters in Comparative Example 1

[0145]

[0146] Comparative Example 2

[0147] The differences from Comparative Example 1 are as follows:

[0148] One shot of injecting 448g of electrolyte (80% of the theoretical injection amount, the mass fraction of the gel polymer monomer is 5% of the theoretical injection amount, and an initiator such as azobisisobutyronitrile (AIBN) is introduced, and the mass fraction of the azobisisobutyronitrile (AIBN) is 0.5% of the theoretical injection amount);

[0149] After aging, the amount of electrolyte added to the battery should be: 20% of the theoretical injection volume (should be 112g, the mass fraction of the gel polymer monomer is 5% of the theoretical injection volume). The cell thickness and cell parameters after the capacity division are shown in the following table, with an average value of 38.76mm (5 points), and the average values ​​of cell capacity, internal resistance, k value, and energy density are 265.506Ah, 0.51774mΩ, 0.0956mV / h, and 310.1464Wh / kg, respectively, as shown in Table 7.

[0150] Table 7 shows the cell thickness and cell parameters in Comparative Example 2

[0151]

[0152] Comparative Example 3

[0153] The differences from Comparative Example 1 are as follows:

[0154] One shot of injecting electrolyte 476g (85% of the theoretical injection amount, the mass fraction of the gel polymer monomer is 5.2% of the theoretical injection amount, and an initiator such as azobisisobutyronitrile (AIBN) is introduced, and the mass fraction of the azobisisobutyronitrile (AIBN) is 0.55% of the theoretical injection amount);

[0155] After aging, the amount of electrolyte added to the battery should be: 15% of the theoretical injection volume (should be 84g, the mass fraction of the gel polymer monomer is 5.2% of the theoretical injection volume). The cell thickness and cell parameters after the capacity division are shown in the following table, with an average value of 38.7964mm (5 points), and the average values ​​of cell capacity, internal resistance, k value, and energy density are 265.814Ah, 0.51896mΩ, 0.098mV / h, and 310.222Wh / kg, respectively, as shown in Table 8.

[0156] Table 8 shows the cell thickness and cell parameters in Comparative Example 3

[0157]

[0158] In summary, the differences between the present embodiment and the comparative example are as follows: the cell thickness of the comparative example is higher than that of the present embodiment, because the initiator has been added to the cell before formation, the gel polymer monomer has been partially gelled during the formation process, and the gas generated during the formation and aging process cannot be fully discharged; and by comparison, the cell performance parameters (such as capacity, internal resistance, K value and energy density) of the comparative example are slightly lower than those of the present embodiment. The results show that the method of first formation and then gelling of the present invention can effectively solve the problem of excessive cell thickness and poor cell performance of gel lithium-ion batteries due to the inability to discharge gas during formation and high-temperature aging.

[0159] Although some specific embodiments of the present invention have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It will be appreciated by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A method for preparing a gel lithium-ion battery, characterized in that: include: Injecting a first electrolyte into the battery cell to obtain an injected battery cell, wherein the first electrolyte comprises a gel polymer matrix, a lithium salt and an organic solvent; Preliminarily wetting the battery cell after liquid injection, and then forming it to obtain a formed battery cell; Weighing the formed battery cell to obtain the liquid loss during the formation process; Injecting a second electrolyte into the formed battery cell according to the amount of liquid loss and the theoretical amount of liquid injection in the formation process to obtain a battery cell after liquid replenishment, wherein the second electrolyte comprises a gel polymer matrix, an initiator, an organic solvent and a lithium salt; The battery cell after replenishment is soaked again, and the second electrolyte after soaking is made into gel.

2. The method for preparing a gel lithium ion battery according to claim 1, characterized in that: The step of re-wetting the battery cell after replenishment and forming the re-wetted second electrolyte into a gel comprises: The re-wetted battery cell is heated in an oven to form a gel lithium-ion battery. The heating temperature ranges from 60°C to 90°C and the vacuum degree ranges from -85KPa to -90KPa.

3. The method for preparing a gel lithium-ion battery according to claim 1, characterized in that: The added amount of the second electrolyte is not less than 10% of the theoretical injection amount.

4. The method for preparing a gel lithium ion battery according to claim 3, characterized in that: The amount of the second electrolyte added is 20±5% of the theoretical injection amount.

5. The method for preparing a gel lithium ion battery according to claim 4, characterized in that: The mass fraction of the gel polymer matrix in the second electrolyte is 5±0.2% of the theoretical injection volume, and the mass fraction of the initiator is 0.5±0.05% of the theoretical injection volume.

6. The method for preparing a gel lithium-ion battery according to claim 1, characterized in that: The amount of liquid loss in the formation process is equal to the difference between the weight of the battery cell after initial infiltration and the weight of the battery cell after formation.

7. The method for preparing a gel lithium-ion battery according to claim 1, characterized in that: The battery cell after the liquid injection is initially wetted and then formed to obtain the formed battery cell comprises: Charging at a constant current of 0.05C to 0.2C, the charging time range is 17min to 60min, the charging cut-off voltage is 3.5V to 3.8V, and the vacuum range is -30kpa to -70kpa; The battery is charged at a constant current of 0.33C to 0.1C, the charging time range is 35min to 80min, and the charging cut-off voltage is 3V to 4.2V.

8. The method for preparing a gel lithium-ion battery according to claim 1, characterized in that: The first electrolyte is injected into the battery cell to obtain the injected battery cell, and the method further comprises: The battery cell is baked, and during the battery cell baking process, ventilation is performed once at a preset interval to obtain a baked battery cell.

9. The method for preparing a gel lithium-ion battery according to claim 1, characterized in that: The theoretical liquid injection amount is obtained according to the rated capacity of the battery cell and the liquid injection coefficient.

10. A gel lithium ion battery, characterized in that: The gel lithium ion battery is prepared by the preparation method of any one of claims 1 to 9.

Images