Battery with automatic electrolyte supplementing function and preparation method thereof
By setting up an accommodating chamber of an explosion-proof valve inside the lithium-ion battery, the automatic replenishment of the electrolyte is solved, and the problem of too little or too much electrolyte is improved, and the circulation performance of the battery is improved.
Patent Information
- Application Number
- CN202510411911.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-02
- Publication Date
- 2025-07-18
AI Technical Summary
During the circulation process of existing lithium-ion batteries, too little electrolyte leads to accelerated circulation attenuation, while too much electrolyte causes problems such as more side reactions and gas production, which are difficult to effectively solve.
A storage chamber with an explosion-proof valve is set inside the battery. The electrolyte in the storage chamber flows into the electrode through the explosion-proof valve under the extrusion pressure generated by the expansion of the electrode sheet, so as to automatically replenish the electrolyte and avoid the problem of too little or too much electrolyte.
It effectively avoids the acceleration of circulating attenuation caused by too little electrolyte during the later cycle of lithium-ion batteries, and at the same time avoids side reactions and gas production problems caused by too much electrolyte, and improves the circulating performance of the battery.
Smart Images
Figure CN120341394A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of secondary batteries, and in particular to a battery with an automatic electrolyte replenishment function and a preparation method thereof. Background Art
[0002] With the rapid development of science and technology, lithium-ion batteries have become an indispensable part of our daily lives. They are widely used in many fields such as mobile phones, laptops, electric vehicles, etc. Lithium-ion batteries are mainly composed of four parts: positive electrode, negative electrode, separator and electrolyte. The electrolyte plays the role of conducting ions in the battery, allowing lithium ions to move freely between the positive and negative electrodes, thereby realizing the battery's charge and discharge process. The amount of electrolyte used directly affects the battery's capacity, energy density, internal resistance and other key performance parameters.
[0003] The electrolyte composition includes lithium salt, solvent and additives, wherein the lithium salt is used to provide active Li + Solvents are used to dissolve lithium salts. There are many types of additives, including film-forming additives, overcharge additives, flame retardant additives, etc., which usually have certain functional effects. In order to ensure the capacity of the active material, the electrolyte must completely infiltrate the diaphragm and electrode to form Li + Conductive path, if the amount of electrolyte is too little, it will inevitably lead to insufficient infiltration of some active particles, increased interface impedance, deterioration of capacity and cycle life, etc. However, the electrolyte should not be too much, otherwise it will cause excessive gas production, interface problems, and increased side reactions will lead to low initial efficiency of the whole battery. Excess electrolyte may also cause unnecessary chemical reactions with other battery materials, affecting the stability and safety of the battery.
[0004] Therefore, how to avoid too little electrolyte in the later cycle of lithium-ion batteries and too much electrolyte in the early cycle is a technical problem that needs to be solved urgently in this field. Summary of the invention
[0005] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a battery with an automatic electrolyte replenishment function and a preparation method thereof. The present invention provides a containing chamber with an explosion-proof valve inside the battery. In the later stage of the battery cycle, the extrusion force generated by the expansion of the pole piece breaks the explosion-proof valve, and the electrolyte in the containing chamber flows out of the containing chamber and is replenished to the pole piece, thereby avoiding the accelerated cycle attenuation caused by too little electrolyte in the later cycle of the lithium-ion battery, and also avoiding the problems of more side reactions and more gas production caused by too much electrolyte in the early cycle.
[0006] In order to achieve the above object, the present invention adopts the following technical solutions:
[0007] In a first aspect, the present invention provides a battery with an automatic electrolyte replenishment function, and the battery includes:
[0008] A square shell, the square shell (1) is provided with an inner cavity, the square shell (1) includes two relatively arranged large surfaces (11), and a receiving cavity (2) for storing electrolyte is provided at the position of the R corner on the inner wall of the large surface (11), and the receiving cavity (2) has a cavity opening;
[0009] An explosion-proof valve (3), the explosion-proof valve (3) is arranged on the receiving cavity (2) and closes the cavity opening, and the explosion-proof valve (3) ruptures when subjected to a bursting pressure so that the electrolyte in the receiving cavity (2) flows into the inner cavity through the cavity opening.
[0010] In the present invention, a receiving cavity with an explosion-proof valve is arranged inside the battery. When the battery is in the later stage of cycling, the extrusion pressure generated by the expansion of the electrode sheet breaks the explosion-proof valve, and the electrolyte in the receiving cavity flows out of the receiving cavity and is replenished into the electrode sheet, avoiding the acceleration of cycle attenuation caused by too little electrolyte during the later cycling process of the lithium-ion battery, and at the same time avoiding problems such as more side reactions and more gas generation caused by too much electrolyte during the early cycling process.
[0011] Further, the battery further includes:
[0012] A bare battery cell, and the bare battery cell is arranged inside the inner cavity of the square shell (1).
[0013] Further, the square shell (1) is a square aluminum shell;
[0014] And / or, the replenishment amount of the electrolyte is 10 - 100 g;
[0015] And / or, the electrolyte includes a lithium salt, a solvent, and an additive.
[0016] Further, the shell of the receiving cavity (2) is an aluminum-plastic shell;
[0017] And / or, the number of the receiving cavities (2) is multiple;
[0018] And / or, the width L of the receiving cavity (2) is 10 - 100 mm, the height h is 5 - 100 mm, and the thickness d is 0.01 - 4 mm.
[0019] Further, the cavity opening is arranged on the side surface or the bottom surface of the receiving cavity (2).
[0020] Further, the bare battery cell includes a positive electrode sheet, a negative electrode sheet, and a separator, the separator is located between the positive electrode sheet and the negative electrode sheet, and the bare battery cell is a structure formed by winding the positive electrode sheet, the negative electrode sheet, and the separator.
[0021] Furthermore, the active material of the positive electrode sheet includes at least one of lithium iron phosphate, ternary material, lithium cobaltate, and lithium nickelate;
[0022] and / or, the active material of the negative electrode sheet includes graphite.
[0023] Furthermore, the size of the explosion-proof valve (3) is (0.01 - 100) mm * (0.01 - 100) mm.
[0024] Furthermore, the bursting pressure of the explosion-proof valve (3) is 1 - 300 MPa.
[0025] In a second aspect, the present invention provides a method for preparing a battery with an automatic electrolyte replenishment function as described in the first aspect, and the preparation method includes the following steps:
[0026] S1. Obtain the relationship curve between the discharge capacity retention rate and the number of cycles of the sample battery, and the relationship curve between the swelling force at the R corner and the number of cycles;
[0027] S2. Based on the relationship curve between the discharge capacity retention rate and the number of cycles, determine the timing of electrolyte replenishment, the composition of the electrolyte, and the replenishment amount;
[0028] S3. Determine the size of the accommodation cavity (2) according to the replenishment amount of the electrolyte;
[0029] S4. According to the relationship curve between the swelling force at the R corner and the number of cycles and the timing of electrolyte replenishment, determine the bursting pressure, and based on the bursting pressure and the preset size of the explosion-proof valve (3), determine the bursting pressure of the explosion-proof valve (3);
[0030] S5. Based on the size of the accommodation cavity (2), set an accommodation cavity (2) for storing electrolyte at the position of the R corner on the inner wall of the large surface (11) of the square shell (1); based on the bursting pressure and the preset size of the explosion-proof valve (3), set an explosion-proof valve (3) on the accommodation cavity (2); inject the electrolyte into the accommodation cavity (2) according to the composition and replenishment amount of the electrolyte;
[0031] S6. Place the bare battery cell in the inner cavity of the square shell (1), assemble, inject liquid, and after encapsulation, obtain the battery with an automatic electrolyte replenishment function through formation.
[0032] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:
[0033] The present invention provides a containment chamber with an explosion-proof valve inside the battery. During the later stage of the battery cycle, when the extrusion force generated by the expansion of the electrode sheet breaks the explosion-proof valve, the electrolyte in the containment chamber flows out and replenishes the electrode sheet, thus avoiding the accelerated cycle attenuation caused by insufficient electrolyte during the later cycle of the lithium-ion battery, and also avoiding problems such as excessive side reactions and gas generation caused by excessive electrolyte during the earlier cycle. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0035] Figure 1 Structural schematic diagram of the battery with the function of automatically replenishing electrolyte provided by the present invention;
[0036] Figure 2 Another structural schematic diagram of the battery with the function of automatically replenishing electrolyte provided by the present invention;
[0037] Figure 3 Relationship curve of expansion force - number of cycles at the R corner of the lithium-ion battery provided in Comparative Example 1 of the present invention;
[0038] Figure 4 Relationship curve of discharge capacity retention rate - number of cycles of the lithium-ion battery provided in Comparative Example 1 of the present invention;
[0039] Figure 5 Relationship curve of discharge capacity retention rate - number of cycles of the lithium-ion battery provided in Example 1 of the present invention.
[0040] Reference numerals: 1 - rectangular housing; 11 - large surface; 2 - containment chamber; 3 - explosion-proof valve. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0041] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in combination with the embodiments of the present invention. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention. The process parameters not specified in the following embodiments are usually in accordance with conventional conditions.
[0042] In the ranges disclosed in the present invention, the endpoints and any values of the ranges are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present invention.
[0043] In a first aspect, the present invention provides a battery with an automatic electrolyte replenishment function, as Figure 1 and Figure 2 shown. The battery includes:
[0044] A square shell 1, the square shell 1 is provided with an inner cavity, the square shell 1 includes two relatively arranged large faces 11, and a receiving cavity 2 for storing electrolyte is provided at the position of the R corner on the inner wall of the large face 11. The receiving cavity 2 has a cavity opening;
[0045] An explosion-proof valve 3, the explosion-proof valve 3 is arranged on the receiving cavity 2 and closes the cavity opening. The explosion-proof valve 3 ruptures when subjected to a bursting pressure so that the electrolyte in the receiving cavity 2 flows into the inner cavity through the cavity opening.
[0046] In the present invention, a receiving cavity with an explosion-proof valve is arranged inside the battery. When the battery is in the later stage of cycling, the extrusion force generated by the expansion of the electrode plate breaks the explosion-proof valve, and the electrolyte in the receiving cavity flows out from the aluminum-plastic film and is replenished into the electrode plate, avoiding the accelerated cycle attenuation caused by too little electrolyte during the later cycling process of lithium-ion batteries, and also avoiding problems such as more side reactions and more gas generation caused by too much electrolyte during the early cycling process.
[0047] The expansion force of the square shell battery at the R corner is the largest. By arranging the receiving cavity for storing electrolyte at the R corner, the liquid replenishment mechanism can be better triggered, and the situation where the electrolyte cannot be replenished due to insufficient expansion force will not occur.
[0048] A lithium-ion battery is an electro-thermal-mechanical coupling system, and there will be an expansion problem during actual use. On the one hand, the SEI film is formed during the formation process, generating gas, increasing the air pressure inside the battery, and as the cycle progresses, the thickness of the SEI film increases, resulting in the expansion of the battery cell; on the other hand, during charging and discharging, Li +Insertion and extraction between the positive and negative electrode materials will cause structural phase changes, resulting in the generation of swelling phenomena. As the cycling progresses, the electrolyte is continuously consumed and the swelling force of the core package also increases. When the electrolyte is exhausted, the interface of the electrode sheet will deteriorate, leading to an accelerated increase in the swelling force of the core package and an accelerated decline in the cycling performance of the battery. In a wound square-shell lithium battery, the swelling force increases the most at the location where the R corner is close to the large surface. Therefore, a receiving cavity with an explosion-proof valve can be provided at each position where the four R corners are close to the large surface, and a certain amount of electrolyte can be added to the receiving cavity. When the electrolyte is exhausted and the swelling force of the core package increases to the explosion-proof pressure of the explosion-proof valve in the receiving cavity at the R corner, the explosion-proof valve in the receiving cavity will rupture, and the electrolyte in the cavity will also be extruded, automatically replenishing the electrolyte for the battery and improving the cycling performance of the battery.
[0049] In the above battery with the function of automatically replenishing electrolyte, as an optional implementation manner, the battery further includes:
[0050] A bare battery cell, and the bare battery cell is arranged in the inner cavity of the square shell.
[0051] In the above battery with the function of automatically replenishing electrolyte, as an optional implementation manner, the square shell 1 is a square aluminum shell.
[0052] In the above battery with the function of automatically replenishing electrolyte, as an optional implementation manner, the replenishment amount of the electrolyte is 10 - 100 g, for example, it can be 10 g, 20 g, 40 g, 60 g, 80 g or 100 g.
[0053] In the above battery with the function of automatically replenishing electrolyte, as an optional implementation manner, the electrolyte includes a lithium salt, a solvent and an additive.
[0054] In the above battery with the function of automatically replenishing electrolyte, as an optional implementation manner, the lithium salt includes at least one of LiPF6, LiClO4, LiBF4, LiAsF6, LiFSI.
[0055] In the above battery with the function of automatically replenishing electrolyte, as an optional implementation manner, the concentration of the lithium salt in the electrolyte is 0.5 - 5 mol / L, for example, it can be 0.5 mol / L, 1 mol / L, 3 mol / L or 5 mol / L. The concentration of the lithium salt = the amount of substance of the lithium salt / the volume of the solvent.
[0056] In the above battery with the function of automatically supplementing electrolyte, as an alternative embodiment, the solvent includes at least one of cyclic carbonates, chain carbonates, and ethers. Specifically, the solvent includes at least two of ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, and butyl butyrate.
[0057] In the above battery with the function of automatically supplementing electrolyte, as an alternative embodiment, the additive includes a film-forming additive. The film-forming additive includes at least one of VC (vinylene carbonate) and FEC (fluoroethylene carbonate). The volume percentage of the additive in the solvent is 0.1-10% (volume ratio), and for example, it can be 0.1%, 1%, 3%, 5%, 7%, or 10%.
[0058] In the above battery with the function of automatically supplementing electrolyte, as an alternative embodiment, the shell of the accommodating cavity 2 is an aluminum-plastic shell.
[0059] In the above battery with the function of automatically supplementing electrolyte, as an alternative embodiment, the number of the accommodating cavities 2 is multiple.
[0060] In the above battery with the function of automatically supplementing electrolyte, as an alternative embodiment, the width L of the accommodating cavity 2 is 10-100 mm (for example, it can be 10 mm, 30 mm, 50 mm, 70 mm, 90 mm, or 100 mm), the height h is 5-100 mm (for example, it can be 5 mm, 10 mm, 30 mm, 50 mm, 70 mm, or 100 mm), and the thickness d is 0.01-4 mm (for example, it can be 0.01 mm, 0.1 mm, 0.2 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, or 4 mm).
[0061] In the above battery with the function of automatically supplementing electrolyte, as an alternative embodiment, the chamber opening is arranged on the side surface or the bottom surface of the accommodating cavity 2.
[0062] In the above battery with the function of automatically supplementing electrolyte, as an alternative embodiment, the bare battery cell includes a positive electrode sheet, a negative electrode sheet, and a separator. The separator is located between the positive electrode sheet and the negative electrode sheet. The bare battery cell is a structure formed by winding the positive electrode sheet, the negative electrode sheet, and the separator.
[0063] In the above battery with the function of automatically supplementing electrolyte, as an alternative embodiment, the active material of the positive electrode sheet includes at least one of lithium iron phosphate, ternary materials, lithium cobaltate, and lithium nickelate.
[0064] In the above battery with the function of automatically replenishing electrolyte, as an alternative embodiment, the active material of the negative electrode plate includes graphite.
[0065] In the above battery with the function of automatically replenishing electrolyte, as an alternative embodiment, the size of the explosion-proof valve 3 is (0.01 - 100) mm * (0.01 - 100) mm.
[0066] In the above battery with the function of automatically replenishing electrolyte, as an alternative embodiment, the bursting pressure of the explosion-proof valve 3 is 1 - 300 MPa, for example, it can be 5 MPa, 10 MPa, 20 MPa, 50 MPa, 100 MPa, 200 MPa or 300 MPa.
[0067] In a second aspect, the present invention provides a method for preparing a battery with the function of automatically replenishing electrolyte as described in the first aspect, and the preparation method includes the following steps:
[0068] S1. Obtain the relationship curve between the discharge capacity retention rate and the number of cycles of the sample battery, and the relationship curve between the swelling force at the R corner and the number of cycles;
[0069] S2. Based on the relationship curve between the discharge capacity retention rate and the number of cycles, determine the timing of replenishing the electrolyte, the composition and the replenishment amount of the electrolyte;
[0070] S3. Determine the size of the accommodation cavity 2 according to the replenishment amount of the electrolyte;
[0071] S4. According to the relationship curve between the swelling force at the R corner and the number of cycles and the timing of replenishing the electrolyte, determine the bursting pressure, and based on the bursting pressure and the preset size of the explosion-proof valve 3, determine the bursting pressure of the explosion-proof valve 3;
[0072] S5. Based on the size of the accommodation cavity 2, set the accommodation cavity 2 for storing electrolyte at the position of the R corner on the inner wall of the large surface 11 of the square shell 1; based on the bursting pressure and the preset size of the explosion-proof valve 3, set the explosion-proof valve 3 on the accommodation cavity 2; inject the electrolyte into the accommodation cavity 2 according to the composition and the replenishment amount of the electrolyte;
[0073] S6. Place the bare battery core in the inner cavity of the square shell 1, assemble, inject liquid, and after completing the encapsulation, obtain the battery with the function of automatically replenishing electrolyte through formation.
[0074] Specifically, in step S2, calculate the composition and amount of the electrolyte to be replenished according to the cycling requirements and experience.
[0075] Based on the bursting pressure, the diaphragm material of the explosion-proof valve can be selected, so that the explosion-proof valve can burst at a specific bursting pressure.
[0076] The present invention can calculate the blasting pressure through the expansion force, and can control the timing of liquid replenishment by controlling the blasting pressure of the explosion-proof valve, so as to replenish the liquid more efficiently.
[0077] The present invention will be further described in detail below with specific examples and comparative examples.
[0078] In the following examples and comparative examples:
[0079] The active material of the negative electrode sheet is artificial graphite.
[0080] The active material of the positive electrode sheet is lithium iron phosphate.
[0081] Comparative Example 1
[0082] The lithium-ion battery provided in this comparative example is a conventional 207Ah square aluminum shell lithium iron phosphate battery. The components of the electrolyte in this lithium iron phosphate battery are: 1M LiPF6, the solvent is EC:DMC = 1:1 (volume ratio), and the film-forming additive is 5% VC (vinyl carbonate, the volume percentage of vinyl carbonate in the solvent is 5%). The relationship curve between the discharge capacity retention rate and the number of cycles obtained by constant current charge and discharge cycling of this square aluminum shell lithium iron phosphate battery at 25°C with a 1C current between 3.65 - 2.5V is as Figure 4 shown, and the relationship curve between the expansion force at the R corner and the number of cycles is as Figure 3 shown.
[0083] Example 1
[0084] The purpose of this example is to provide a battery with an automatic electrolyte replenishment function and its preparation method to avoid the problem of too little electrolyte in the same type of lithium-ion battery provided in Comparative Example 1 during the later cycling process.
[0085] This example provides a preparation method of a battery with an automatic electrolyte replenishment function. The preparation method includes the following steps:
[0086] S1. The relationship curve between the discharge capacity retention rate and the number of cycles of the lithium-ion battery provided in Comparative Example 1 is as Figure 4 shown, and the relationship curve between the expansion force at the R corner and the number of cycles is as Figure 3 shown.
[0087] S2. The goal of this embodiment is to make the capacity retention rate of the same type of lithium-ion battery provided in Comparative Example 1 at 25°C with 1C / 1C cycling for 1500 cycles be above 80%. According to experience, approximately 20 g of electrolyte needs to be added. The composition of the replenished electrolyte is determined as follows: the lithium salt is 1M LiPF6, the solvent is EC:DMC = 1:1 (volume ratio), and the film-forming additive is 5% VC (vinyl carbonate, and the volume percentage of vinyl carbonate in the solvent is 5%). According to Figure 4 it can be seen that the battery capacity starts to decay rapidly from 600 cycles, and the liquid replenishment time is set at 600 cycles of cycling.
[0088] S3. The density of the electrolyte is 1.2 g / cm 3 , and the volume of the electrolyte to be replenished is approximately 16 cm 3 ; Four accommodation cavities are set, and the volume of each accommodation cavity is approximately 4 cm 3 , and the size of the accommodation cavity is width L * height h * thickness d = 10 mm * 100 mm * 4 mm.
[0089] S4. According to Figure 4 it can be seen that the battery capacity starts to decay rapidly from 600 cycles, and the liquid replenishment time is set at 600 cycles of cycling. According to Figure 3 , at this time, the expansion force (bursting pressure) is 1100 Kgf. The entire side surface of the accommodation cavity is set as an explosion-proof valve, and the break area (size) of the explosion-proof valve is 100 mm * 4 mm = 400 mm 2 , and the bursting pressure of each explosion-proof valve is 1100 * 9.80665 / 400 * 10^-6 / 1000000 Mpa = 26.97 Mpa.
[0090] S5. Based on the size and number of the accommodation cavities, accommodation cavities with a size of width L * height h * thickness d = 10 mm * 100 mm * 4 mm for storing electrolyte are set at the positions of the 4 R corners on the inner wall of the large surface of the square shell; based on the bursting pressure and size of the explosion-proof valve, explosion-proof valves with a bursting pressure of 26.97 Mpa are set on each accommodation cavity; based on the composition and replenishment amount of the electrolyte, 4 cm 3 of electrolyte is injected into each accommodation cavity;
[0091] S6. The bare battery cell is placed in the inner cavity of the square shell, assembled, and filled with liquid (the composition and dosage of the electrolyte are the same as those in Comparative Example 1). After encapsulation, a lithium-ion battery is obtained through formation.
[0092] The battery with the function of automatically replenishing electrolyte prepared in this embodiment includes:
[0093] Square aluminum shell housing, the square aluminum shell housing is provided with an inner cavity, the square aluminum shell housing includes two relatively arranged large faces, and at the position of the R corner on the inner wall of the large face, there is a receiving cavity for storing electrolyte. The receiving cavity has a cavity opening, the shell of the receiving cavity is an aluminum-plastic shell, the number of the receiving cavities is 4, the width L of the receiving cavity is 10 mm, the height h is 100 mm, and the thickness d is 4 mm. The cavity opening is arranged on the entire side surface of the receiving cavity;
[0094] Naked battery cell, the naked battery cell is arranged in the inner cavity of the square housing. The naked battery cell includes a positive electrode sheet, a negative electrode sheet and a separator. The separator is located between the positive electrode sheet and the negative electrode sheet. The naked battery cell is a structure formed by winding the positive electrode sheet, the negative electrode sheet and the separator;
[0095] Explosion-proof valve, the explosion-proof valve is arranged on the receiving cavity and closes the cavity opening. The explosion-proof valve ruptures when it receives an expansion force (burst pressure) of 1100 Kgf so that the electrolyte in the receiving cavity flows into the inner cavity through the cavity opening. The size of the explosion-proof valve is 100 mm * 4 mm.
[0096] For the lithium-ion battery provided in this embodiment, at 25 °C, a constant current charge and discharge cycle test is carried out at a current of 1C between 3.65 - 2.5V, and the results are as Figure 5 shown.
[0097] From Figure 4 and Figure 5 it can be seen that before liquid replenishment (Comparative Example 1), the capacity retention rate reaches 80% after 1100 cycles. After automatic liquid replenishment (Example 1), the capacity retention rate reaches 80% after more than 1600 cycles. The lithium-ion battery provided in this embodiment significantly improves the cycle performance and avoids the accelerated cycle decay caused by too little electrolyte during the later cycle of the lithium-ion battery.
[0098] Example 2
[0099] The battery with the function of automatically replenishing electrolyte provided in this embodiment is basically the same as that in Example 1, except that the cavity opening is arranged on the bottom surface of the receiving cavity, the explosion-proof valve is arranged on the receiving cavity and closes the cavity opening, the size of the explosion-proof valve is 10 mm * 4 mm, and the bursting pressure of the explosion-proof valve is 269.7 MPa.
[0100] For the lithium-ion battery provided in this embodiment, at 25 °C, a constant current charge and discharge cycle test is carried out at a current of 1C between 3.65 - 2.5V. After automatic liquid replenishment, the capacity retention rate reaches 80% after more than 1600 cycles.
[0101] Comparative Example 2
[0102] The lithium-ion battery provided in this comparative example is basically the same as that in Comparative Example 1, except that the amount of electrolyte in the lithium-ion battery is the sum of the liquid injection amount in Example 1 and the amount of electrolyte in the accommodation chamber.
[0103] The lithium-ion battery provided in this comparative example was subjected to a constant current charge-discharge cycle test at 25°C with a current of 1C between 3.65V and 2.5V. Since the lithium-ion battery provided in this comparative example has more electrolyte, it will cause excessive gas generation, resulting in interface problems, and an increase in side reactions leading to faster cycle decay in the early stage of the lithium-ion battery. At the 400th cycle, the capacity retention rate was 92.5%, while the lithium-ion battery provided in Example 1 had a capacity retention rate of 95.6% at the 400th cycle.
[0104] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A battery with an automatic electrolyte replenishment function, characterized in that, The battery includes: A square shell (1), the square shell (1) is provided with an inner cavity, the square shell (1) includes two relatively arranged large faces (11), and a receiving cavity (2) for storing electrolyte is provided at the position of the R corner on the inner wall of the large face (11), and the receiving cavity (2) has a cavity opening; An explosion-proof valve (3), the explosion-proof valve (3) is arranged on the receiving cavity (2) and closes the cavity opening, and the explosion-proof valve (3) ruptures when subjected to a bursting pressure so that the electrolyte in the receiving cavity (2) flows into the inner cavity through the cavity opening.
2. The battery with the function of automatically replenishing electrolyte according to claim 1, characterized in that, The battery further includes: A bare battery cell, and the bare battery cell is arranged in the inner cavity of the square shell (1).
3. The battery with the function of automatically replenishing electrolyte according to claim 1, characterized in that The square shell (1) is a square aluminum shell; And / or, the supplementary amount of the electrolyte is 10-100 g; And / or, the electrolyte includes a lithium salt, a solvent and an additive.
4. The battery with an automatic electrolyte replenishment function according to claim 1, characterized in that, The shell of the receiving cavity (2) is an aluminum-plastic shell; And / or, the number of the receiving cavities (2) is multiple; And / or, the width L of the receiving cavity (2) is 10-100 mm, the height h is 5-100 mm, and the thickness d is 0.01-4 mm.
5. The battery with the function of automatically replenishing electrolyte according to claim 1, characterized in that, The cavity opening is arranged on the side surface or the bottom surface of the receiving cavity (2).
6. The battery with the function of automatically replenishing electrolyte according to claim 2, wherein, The bare battery cell includes a positive electrode sheet, a negative electrode sheet and a separator, the separator is located between the positive electrode sheet and the negative electrode sheet, and the bare battery cell is a structure formed by winding the positive electrode sheet, the negative electrode sheet and the separator.
7. The battery with the function of automatically replenishing electrolyte according to claim 6, characterized in that, The active material of the positive electrode sheet includes at least one of lithium iron phosphate, ternary material, lithium cobaltate, and lithium nickelate; And / or, the active material of the negative electrode sheet includes graphite.
8. The battery with the function of automatically supplementing electrolyte according to claim 1, characterized in that, The size of the explosion-proof valve (3) is (0.01-100) mm * (0.01-100) mm.
9. The battery with the function of automatically replenishing electrolyte according to claim 1, wherein, The bursting pressure of the explosion-proof valve (3) is 1-300 MPa.
10. A method for preparing a battery with an automatic electrolyte replenishment function as described in any one of claims 1-9, characterized in that, The preparation method includes the following steps: S1. Obtain the relationship curve between the discharge capacity retention rate and the number of cycles of the sample battery and the relationship curve between the swelling force at the R corner and the number of cycles; S2. Based on the relationship curve between the discharge capacity retention rate and the number of cycles, determine the timing of supplementing the electrolyte, the composition and the supplementary amount of the electrolyte; S3. Determine the size of the receiving cavity (2) according to the supplementary amount of the electrolyte; S4. Determine the bursting pressure according to the relationship curve between the swelling force at the R corner and the number of cycles and the timing of supplementing the electrolyte, and determine the bursting pressure of the explosion-proof valve (3) based on the bursting pressure and the preset size of the explosion-proof valve (3); S5. Based on the size of the receiving cavity (2), arrange a receiving cavity (2) for storing electrolyte at the position of the R corner on the inner wall of the large face (11) of the square shell (1); arrange an explosion-proof valve (3) on the receiving cavity (2) based on the bursting pressure and the preset size of the explosion-proof valve (3); inject the electrolyte into the receiving cavity (2) based on the composition and the supplementary amount of the electrolyte; S6. Place the bare battery cell in the inner cavity of the square shell (1), assemble, inject liquid, and after encapsulation, obtain the battery with the function of automatically supplementing electrolyte through formation.