Electrolyte preparation method, electrolyte, ultra-high power lithium thionyl chloride battery and manufacturing method

Abstract

The invention relates to the technical field of batteries, and discloses an electrolyte preparation method, an electrolyte, an ultrahigh-power lithium thionyl chloride battery and a manufacturing method. The method comprises the following steps: adding solid anhydrous gallium chloride and anhydrous lithium chloride into a round-bottom flask in an argon protection environment, and heating to melt the anhydrous gallium chloride and the anhydrous lithium chloride into liquid; after the round-bottom flask is cooled, thionyl chloride is added into the round-bottom flask and stirred to be partially dissolved, then chlorosulfonic acid is added so that transparent floccules can appear in the solution in the round-bottom flask, a condensation reflux device is installed on the round-bottom flask, and the round-bottom flask is heated so that the transparent floccules in the solution can be completely dissolved. The method comprises the following steps: adding a metal elementary substance lithium sheet into a round-bottom flask in an environment with the relative humidity of less than 1%, installing a condensation reflux device, heating to remove impurities in a solution, cooling the round-bottom flask, enabling sulfur dioxide to sequentially pass through a concentrated sulfuric acid and calcium chloride scrubbing device, and then introducing the sulfur dioxide into the round-bottom flask to remove moisture in the solution so as to prepare the electrolyte.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to an electrolyte preparation method, an electrolyte, an ultra-high power lithium-ion battery, and a manufacturing method thereof. Background Technology

[0002] Lithium-thionyl chloride (LiTH) batteries are a type of lithium primary battery, currently the commercially available battery with the highest specific energy and widest operating temperature range. They can be broadly categorized into two types based on their structure: power-type and energy-type. Compared to lithium-ion batteries, even LiTH power-type batteries have a lower discharge rate. Taking the commonly seen D-type power LiTH battery as an example, when the discharge current gradually increases to 0.1C, the discharge load voltage and total discharge capacity decrease slowly, still meeting discharge requirements. However, when the discharge current increases from 0.1C to 0.2C, the discharge load voltage and total discharge capacity decrease rapidly. At 0.2C, the load voltage is almost below the cutoff voltage required by the device, rendering it unusable. This phenomenon is caused by the fact that during high-current discharge, the reaction products LiCl and S mainly concentrate at the pore openings of the porous carbon cathode, unable to enter the interior of the porous carbon cathode pores. This leads to premature passivation of the porous carbon cathode, a rapid drop in the discharge plateau, and low discharge capacity.

[0003] Therefore, there is an urgent need to design an electrolyte preparation method, an electrolyte, an ultra-high power lithium-ion battery, and a manufacturing method to solve the above technical problems. Summary of the Invention

[0004] One of the objectives of this invention is to provide an electrolyte preparation method. The electrolyte prepared by this method is less likely to passivate the battery cathode during high-current discharge, and can achieve higher capacity under high-power discharge conditions.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] An electrolyte preparation method is provided, comprising the following steps:

[0007] S1. In an argon-protected environment, add solid anhydrous gallium chloride and anhydrous lithium chloride to a round-bottom flask;

[0008] S2. In an argon-protected environment, heat the round-bottom flask to melt anhydrous gallium chloride and anhydrous lithium chloride into a liquid.

[0009] S3. In an argon-protected environment, after the round-bottom flask has cooled, add thionyl chloride to the round-bottom flask and stir to partially dissolve it. Then add chlorosulfonic acid to the round-bottom flask so that transparent flocculent matter appears in the solution in the round-bottom flask.

[0010] S4. In an argon-protected environment, install a reflux condenser on a round-bottom flask and heat the flask to completely dissolve the transparent flocculent material in the solution.

[0011] S5. In an environment with a relative humidity of less than 1%, add a metallic elemental lithium sheet into a round-bottom flask, install a reflux condenser on the round-bottom flask, and heat the round-bottom flask to remove impurities from the solution.

[0012] S6. In an environment with a relative humidity of less than 1%, after the round-bottom flask has cooled, sulfur dioxide is passed sequentially through a gas washing device containing concentrated sulfuric acid and calcium chloride, and then back into the round-bottom flask to remove water from the solution and prepare an electrolyte.

[0013] Optionally, in step S1, the number of moles of anhydrous lithium chloride added to the round-bottom flask is a, and the number of moles of anhydrous gallium chloride added to the round-bottom flask is b, where 1.02b≤a≤1.05b; the anhydrous lithium chloride is dried at 150℃-170℃ for more than 12 hours before being added to the round-bottom flask.

[0014] In step S3, thionyl chloride is added to the round-bottom flask to bring the concentration of anhydrous gallium chloride in the solution to 1.2 M / L-1.8 M / L; the amount of chlorosulfonic acid added to the round-bottom flask is 2 g / L-7 g / L.

[0015] In step S5, the amount of elemental lithium sheet added to the round-bottom flask is 1.2 g / L-5 g / L; the thickness of the elemental lithium sheet added to the round-bottom flask is 0.2 mm-0.5 mm.

[0016] In step S6, the amount of sulfur dioxide added to the round-bottom flask is 0.8 M / L-2.0 M / L.

[0017] Optionally, in step S2, the round-bottom flask is heated to 95°C-98°C and held at that temperature for 5 min-30 min;

[0018] In step S4, the round-bottom flask is heated to 50°C-60°C and kept at that temperature for 4-6 hours.

[0019] In step S5, the round-bottom flask is heated to 75°C-78°C and kept at that temperature for 6-12 hours.

[0020] Optionally, the anhydrous gallium chloride has a purity greater than 98% and a particle size of less than 1 mm;

[0021] Anhydrous lithium chloride has a purity greater than 98% and a particle size of less than 1 mm;

[0022] The purity of thionyl chloride is greater than 99.5%;

[0023] The concentration of chlorosulfonic acid is greater than 97%, and its density at 25°C is greater than or equal to 1.75.

[0024] The water content of sulfur dioxide is less than 600 ppm.

[0025] The second objective of this invention is to provide an electrolyte that does not easily passivate the battery cathode during high-current discharge, and can achieve higher capacity under high-power discharge conditions.

[0026] To achieve this objective, the present invention adopts the following technical solution:

[0027] An electrolyte is provided, which is prepared using the electrolyte preparation method described above.

[0028] The third objective of this invention is to propose an ultra-high power lithium-ion battery, in which the cathode is not easily passivated during high-current discharge, and higher capacity can be obtained under high-power discharge conditions.

[0029] To achieve this objective, the present invention adopts the following technical solution:

[0030] An ultra-high power lithium-ion battery is provided, comprising the electrolyte described above.

[0031] Optionally, the ultra-high power lithium-ion battery includes:

[0032] A core is formed by winding a positive electrode sheet and a negative electrode sheet. The positive electrode sheet includes a positive current collector network and positive current collector strips. Multiple positive current collector strips are spaced apart along the length of the positive current collector network. The first end of each positive current collector strip extends out of the positive current collector network in the width direction. Areas on the positive current collector network without a positive current collector strip are covered with a positive electrode film. The negative electrode sheet includes a negative current collector strip and two lithium strips. The negative current collector strip is located between the two lithium strips, and its first end extends out of the lithium strips in the width direction.

[0033] The outer casing includes a housing and a cover assembly. One end of the housing has an opening, and the cover assembly covers the opening. The cover assembly includes a cover plate and a negative electrode post that is insulated from and connected to the cover plate. The cover plate has an injection hole through which the electrolyte is injected into the housing. The core is located inside the housing through the opening. The first end of the positive current collector is sandwiched between the housing and the cover plate, and the first end of the negative current collector is connected to the negative electrode post. The area of ​​the core other than the positive and negative current collectors is insulated from and in contact with the outer casing.

[0034] Optionally, the positive current collector bars are spaced apart perpendicular to the length direction of the positive current collector network, with the first end of the positive current collector bar extending out of one side of the positive current collector network and the second end of the positive current collector bar flush with the other side of the positive current collector network.

[0035] Optionally, the length of the positive current collector is A, and the minimum distance between the positive current collector bars at both ends and the end of the positive current collector along the length direction of the positive current collector is C, where C > 0.15A; and / or,

[0036] The length of the positive electrode current collector is A, and the length of the lithium strip is B, where 0.96A ≥ B ≥ 0.90A.

[0037] The fourth objective of this invention is to propose a manufacturing method. The ultra-high power lithium-ion battery manufactured by this method has a cathode that is not easily passivated during high-current discharge, can achieve higher capacity under high-power discharge conditions, has less constraint on the high-power discharge energy of the battery due to the electronic impedance characteristics of the cathode current collector, and has more uniform electron gain, loss and conduction in all parts of the positive electrode.

[0038] To achieve this objective, the present invention adopts the following technical solution:

[0039] A manufacturing method is provided, comprising the following steps:

[0040] The positive electrode film is completely covered and bonded to the positive electrode current collector, and multiple spaced current collector strip setting areas are set along the length direction of the positive electrode current collector. The positive electrode film in multiple current collector strip setting areas is removed, and a positive electrode current collector is fixed in one current collector strip setting area to form a positive electrode sheet.

[0041] One side of an L-shaped negative electrode current collector is sandwiched between two lithium strips, and the other side extends out of the lithium strips to form a negative electrode sheet.

[0042] Align one end of the positive electrode sheet along its length with one end of the negative electrode sheet having the negative current collector strip extending out of the lithium strip, and wind the sheet around this end as the winding center to form a core.

[0043] The core is placed inside the housing, one end of the negative electrode current collector extends out of the lithium strip and is connected to the negative electrode post, the cover assembly is disposed at the opening of the housing, and one end of the positive electrode current collector extends out of the positive electrode current collector and is sandwiched between the cover plate and the housing;

[0044] The electrolyte is injected into the housing through the injection hole reserved on the cover plate, and then the injection hole is sealed.

[0045] The beneficial effects of the present invention include at least the following:

[0046] This invention provides a method for preparing an electrolyte, comprising the following steps: S1, adding solid anhydrous gallium chloride and anhydrous lithium chloride to a round-bottom flask under argon protection; S2, heating the round-bottom flask under argon protection to melt the anhydrous gallium chloride and anhydrous lithium chloride into a liquid; S3, under argon protection, after the round-bottom flask has cooled, adding thionyl chloride to the round-bottom flask, stirring to partially dissolve it, and then adding chlorosulfonic acid to the round-bottom flask to make transparent flocculent matter appear in the solution; S4, under argon protection... In an environment with relative humidity less than 1%, a reflux condenser is installed on a round-bottom flask, and the flask is heated to completely dissolve the transparent flocculent matter in the solution; S5, in an environment with relative humidity less than 1%, elemental lithium sheets are added to the round-bottom flask, and a reflux condenser is installed on the flask, and the flask is heated to remove impurities from the solution; S6, in an environment with relative humidity less than 1%, after the round-bottom flask has cooled, sulfur dioxide is passed sequentially through a gas washing device containing concentrated sulfuric acid and calcium chloride, and then passed back into the round-bottom flask to remove water from the solution, thus preparing the electrolyte. Unlike traditional lithium-ion battery electrolytes using aluminum tetrachlorochlorate as the electrolyte salt, the electrolyte provided by this invention, using lithium tetrachlorogallate as the electrolyte salt, is more suitable for high-power battery discharge. Aluminum and gallium are elements in the same group, and lithium tetrachlorogallate has a stronger Lewis acidity, resulting in higher conductivity and a higher discharge platform for its electrolyte. Meanwhile, lithium tetrachlorogallate has stronger activity and water absorption, and the electrolyte preparation process introduces a large number of impurities. The electrolyte preparation method provided by this invention can overcome these difficulties and obtain a lithium tetrachlorogallate electrolyte that meets the usage conditions. Using the electrolyte prepared by the method provided by this invention, the battery cathode is less likely to passivate during high-current discharge, and higher capacity can be obtained under high-power discharge conditions.

[0047] This invention provides an electrolyte manufactured using the above-described electrolyte manufacturing method. The electrolyte provided by this invention, using lithium tetrachlorogallate as the electrolyte salt, is more suitable for high-power battery discharge. Aluminum and gallium are elements in the same group, and lithium tetrachlorogallate has a stronger Lewis acidity, resulting in higher conductivity and a higher discharge platform for its electrolyte.

[0048] This invention provides an ultra-high power lithium-ion battery, comprising the electrolyte described above. Using the electrolyte provided by this invention, the battery cathode is less prone to passivation during high-current discharge, resulting in higher capacity under high-power discharge conditions.

[0049] This invention provides a manufacturing method for manufacturing the aforementioned ultra-high power lithium-ion battery. The manufacturing method includes the following steps: completely covering and bonding a positive electrode film to a positive electrode current collector, and setting multiple spaced current collector strip setting areas along the length direction of the positive electrode current collector; removing the positive electrode film from the multiple current collector strip setting areas, and fixing a positive electrode current collector strip corresponding to one current collector strip setting area to form a positive electrode sheet; clamping one side of an L-shaped negative electrode current collector strip between two lithium strips, with the other side partially extending out of the lithium strips to form a negative electrode sheet; aligning one end of the positive electrode sheet along its length with one end of the negative electrode sheet with the negative electrode current collector strip extending out of the lithium strip, and winding it around this end as a winding center to form a core; placing the core into a housing, connecting the end of the negative electrode current collector strip extending out of the lithium strip to the negative electrode post, setting a cover assembly at the opening of the housing, and clamping the end of the positive electrode current collector strip extending out of the positive electrode current collector between the cover plate and the housing; injecting electrolyte into the housing through a pre-reserved injection hole on the cover plate, and then sealing the injection hole. Batteries manufactured using this method are less prone to passivation of the cathode during high-current discharge, and can achieve higher capacity under high-power discharge conditions. The electronic impedance characteristics of the cathode current collector have less of a constraint on the battery's high-power discharge capacity, and the electron gain, loss, and conduction in all parts of the positive electrode are more uniform. Attached Figure Description

[0050] Figure 1 This is a flowchart of the electrolyte preparation method provided in the embodiments of the present invention;

[0051] Figure 2 This is a partial structural schematic diagram of the positive electrode sheet provided in an embodiment of the present invention;

[0052] Figure 3 This is a schematic diagram of the negative electrode sheet provided in an embodiment of the present invention;

[0053] Figure 4 This is a cross-sectional view of the ultra-high power lithium-ion battery provided in an embodiment of the present invention;

[0054] Figure 5 This is a comparison chart of the discharge capacity of the ultra-high power lithium-ion battery provided in the embodiments of the present invention and batteries of the prior art.

[0055] Figure Labels

[0056] 1. Positive electrode plate; 11. Positive electrode current collector; 12. Positive electrode current collector strip; 13. Positive electrode membrane;

[0057] 2. Negative electrode sheet; 21. Lithium strip; 22. Negative electrode current collector;

[0058] 3. Winding the diaphragm;

[0059] 4. Bottom diaphragm;

[0060] 5. Bottom insulating sheet;

[0061] 6. Apply insulating sheet;

[0062] 7. Cover assembly; 71. Cover plate; 72. Negative terminal post; 73. Sealing pin;

[0063] 8. Shell. Detailed Implementation

[0064] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. Furthermore, it should be noted that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings, not all of them.

[0065] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0066] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0067] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0068] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0069] like Figure 1As shown, this embodiment provides an electrolyte preparation method, including the following steps: S1, adding solid anhydrous gallium chloride and anhydrous lithium chloride to a round-bottom flask in an argon-protected environment; S2, heating the round-bottom flask in an argon-protected environment to melt the anhydrous gallium chloride and anhydrous lithium chloride into a liquid; S3, after the round-bottom flask cools in an argon-protected environment, adding thionyl chloride to the round-bottom flask, stirring to partially dissolve it, and then adding chlorosulfonic acid to the round-bottom flask to make transparent flocculent matter appear in the solution in the round-bottom flask; S4, heating the round-bottom flask in an argon-protected environment... In a protected environment, a reflux condenser is installed on the round-bottom flask, and the flask is heated to completely dissolve the transparent flocculent matter in the solution; S5, in an environment with a relative humidity of less than 1%, metallic lithium sheets are added to the round-bottom flask, a reflux condenser is installed on the round-bottom flask, and the flask is heated to remove impurities from the solution; S6, in an environment with a relative humidity of less than 1%, after the round-bottom flask has cooled, sulfur dioxide gas is passed sequentially through a gas washing device of concentrated sulfuric acid and calcium chloride, and then passed back into the round-bottom flask to remove water from the solution and prepare an electrolyte.

[0070] Unlike traditional lithium-ion battery electrolytes that use aluminum tetrachlorochlorate as the electrolyte salt, the electrolyte provided in this embodiment, using lithium tetrachlorogallate as the electrolyte salt, is more suitable for high-power battery discharge. Aluminum and gallium are elements in the same group, and lithium tetrachlorogallate has stronger Lewis acidity, resulting in higher electrolyte conductivity and a higher discharge plateau. However, lithium tetrachlorogallate is more active and hygroscopic, introducing a large number of impurities during the electrolyte preparation process. The electrolyte preparation method provided in this embodiment overcomes these difficulties, yielding a lithium tetrachlorogallate electrolyte that meets the usage requirements.

[0071] Optionally, in step S1, the number of moles of anhydrous lithium chloride added to the round-bottom flask is a, and the number of moles of anhydrous gallium chloride added to the round-bottom flask is b, where 1.02b≤a≤1.05b; the anhydrous lithium chloride is dried at 150℃-170℃ for more than 12 hours before being added to the round-bottom flask.

[0072] Preferably, the anhydrous gallium chloride has a purity greater than 98% and a particle size less than 1 mm; the anhydrous lithium chloride has a purity greater than 98% and a particle size less than 1 mm.

[0073] Optionally, in step S3, after stopping heating the round-bottom flask, it is cooled in an argon-protected environment, resulting in a gray solid. An appropriate amount of thionyl chloride is added to this solid, and the mixture is stirred until most of it dissolves. The amount of thionyl chloride added should ensure that the concentration of anhydrous gallium chloride in the solution reaches 1.2 M / L-1.8 M / L. A small amount of chlorosulfonic acid is then added to the solution to produce transparent flocculent matter; the amount of chlorosulfonic acid added is 2 g / L-7 g / L.

[0074] Preferably, the concentration of chlorosulfonic acid is greater than 97%, and the density at 25°C is greater than or equal to 1.75. The purity of thionyl chloride is greater than 99.5%.

[0075] Optionally, in step S5, the amount of elemental lithium sheet added to the round-bottom flask is 1.2 g / L-5 g / L; the thickness of the elemental lithium sheet added to the round-bottom flask is 0.2 mm-0.5 mm.

[0076] Optionally, in step S6, the amount of sulfur dioxide added to the round-bottom flask is 0.8 M / L to 2.0 M / L.

[0077] Preferably, the water content of sulfur dioxide is less than 600 ppm.

[0078] In addition, during step S2, while heating the round-bottom flask, the mixture of anhydrous gallium chloride and anhydrous lithium chloride solid particles inside the flask is simultaneously stirred. When the temperature rises to 78°C, liquid begins to appear inside the flask. After continuously heating to 95°C-98°C and holding at that temperature for 5-30 minutes, the solid particle mixture completely melts into a dark-colored liquid. Furthermore, the heating rate of the round-bottom flask should not be too fast; the heating rate must be less than 3°C / min, and stirring must be maintained during heating and holding.

[0079] In step S4, the round-bottom flask is heated to 50°C-60°C and held at that temperature for 4-6 hours. During the heating process, the outlet temperature of the condenser is set below 45°C.

[0080] In step S5, the round-bottom flask is heated to 75℃-78℃ and held at that temperature for 6h-12h. During the heating process, the outlet temperature of the condenser is set below 45℃.

[0081] In step S5, impurities in the solution react with lithium and are adsorbed onto the elemental lithium metal sheet. Alternatively, impurities generate gas and are released during heating. Thionyl chloride evaporates during heating, and by setting up a condensation reflux device, the thionyl chloride can be condensed and returned to the solution. The solution is filtered using glass fiber paper to separate the elemental lithium metal sheet and the impurities adsorbed on it from the solution.

[0082] This embodiment also provides an electrolyte. The raw materials for this electrolyte include anhydrous lithium chloride, anhydrous gallium chloride, thionyl chloride, chlorosulfonic acid, elemental lithium metal, and sulfur dioxide, and it is prepared using the electrolyte preparation method described above. Using the electrolyte prepared by the method provided in this embodiment, the battery cathode is less prone to passivation during high-current discharge, and higher capacity can be obtained under high-power discharge conditions.

[0083] This embodiment also provides an ultra-high power lithium-ion battery, including the electrolyte as described above.

[0084] like Figures 2 to 4 As shown, the ultra-high power lithium-ion battery includes a core and a casing. The core is formed by winding a positive electrode sheet 1 and a negative electrode sheet 2. The positive electrode sheet 1 includes a positive current collector 11 and positive current collector strips 12. Multiple positive current collector strips 12 are spaced apart along the length of the positive current collector 11. The first end of each positive current collector strip 12 extends out of the positive current collector 11 in the width direction. The area of ​​the positive current collector 11 without positive current collector strips 12 is covered by a positive electrode film 13. The negative electrode sheet 2 includes two lithium strips 21 and negative current collector strips 22. The negative current collector strips 22 are located between the two lithium strips 21, and the first end of the negative current collector strips 22 extends out of the lithium strips 21 in the width direction. The outer casing includes a housing 8 and a cover assembly 7. One end of the housing 8 has an opening, and the cover assembly 7 covers the opening. The cover assembly 7 includes a cover plate 71 and a negative electrode post 72 that is insulated from and connected to the cover plate 71. The cover plate 71 has an injection hole, through which electrolyte is injected into the housing 8. The core is located inside the housing 8 through this opening. The first end of the positive current collector 12 is sandwiched between the housing 8 and the cover plate 71, and the first end of the negative current collector 22 is connected to the negative electrode post 72. The area of ​​the core other than the positive current collector 12 and the negative current collector 22 is insulated from and in contact with the outer casing.

[0085] The ultra-high power lithium-ion battery also includes a bottom separator 4 and a bottom insulating sheet 5. The bottom insulating sheet 5 is located between the bottom separator 4 and the bottom of the casing 8. The core is located on the bottom separator 4. The bottom separator 4 and the bottom insulating sheet 5 are used to isolate the core and the casing 8 to prevent the negative electrode of the core from being electrically connected to the casing 8. The battery also includes an upper insulating sheet 6, which is located on the side of the cover plate 71 facing inward to prevent the central area of ​​the core from moving upward and contacting the cover plate 71 during battery use, thus preventing the negative electrode of the core from being electrically connected to the cover plate 71. In this embodiment, the positive current collector 12 is sandwiched between the cover plate 71 and the casing 8, and both are electrically connected to the positive electrode of the core. The positive electrode sheet 1 has multiple positive current collectors 12, which minimizes the limitation of the cathode current collector's electronic impedance characteristics on the high-power discharge energy of the battery. Except for the central negative electrode post 72, the entire battery casing is positive. Multiple positive current collectors 12 make the electron gain, loss and conduction of each part of the positive electrode more uniform.

[0086] Furthermore, due to the high-capacity design requirements of lithium-ion power batteries, the electrodes cannot be designed to be too long. This would increase the volume ratio of internal structural components (current collectors, wound separators, etc.) and reduce the volume ratio of reactive materials, ultimately reducing the overall design capacity and the ability to discharge at high currents. However, if it is clear that the battery will be used in a high-current scenario, the design can be optimized to increase the effective reaction area of ​​the battery and further increase the high-power discharge capability.

[0087] Optionally, the positive current collector bars 12 are spaced apart perpendicular to the length direction of the positive current collector grid 11, with the first end of each positive current collector bar 12 extending beyond one side of the positive current collector grid 11 and the second end of each positive current collector bar 12 flush with the other side of the positive current collector grid 11. The battery reaction at the cathode is concentrated near the positive current collector bars 12. By increasing the number of positive current collector bars 12 and the area covered by the positive current collector bars 12 on the positive current collector grid 11, the reaction path of electrons is shortened, thereby further reducing the electronic impedance characteristics recorded at the cathode.

[0088] Optionally, the length of the positive current collector 11 is A, and the minimum distance between the positive current collector strips 12 at both ends and the ends of the positive current collector 11 along the length direction of the positive current collector 11 is C, where C > 0.15A. A greater number of positive current collector strips 12 reduces the electronic impedance characteristics of the cathode current collector. However, limited by the manufacturing process, the number of positive current collector strips 12 can be determined based on the actual processing difficulty. The positive current collector strips 12 are evenly distributed in the middle of the positive electrode sheet 1, while the outermost and innermost positive current collector strips 12 of the core maintain a distance of at least 0.15 times the length of the positive electrode sheet 1 from both ends of the positive current collector 11.

[0089] Preferably, the positive electrode current collector 11 is a nickel perforated mesh. The positive electrode current collector strip 12 is a nickel strip with a thickness of 0.02-0.06 mm.

[0090] In this embodiment, the core is wound by wrapping the negative electrode 2 with the positive electrode sheet 1. That is, the separator 3, the positive electrode sheet 1, the separator 3, and the negative electrode sheet 2 are stacked in sequence, with the outermost part of the core being the positive electrode sheet 1 wrapped by the separator 3. The positive electrode sheet 1 at the center of the winding is aligned with the lithium strip 21. The length of the lithium strip 21 is less than the length of the positive electrode sheet 1. The length of the positive current collector 11 is A, and the length of the lithium strip 21 is B, where 0.96A ≥ B ≥ 0.90A.

[0091] This embodiment provides a manufacturing method for manufacturing the aforementioned ultra-high power lithium-ion battery, the manufacturing method comprising the following steps:

[0092] The positive electrode film 13 is completely covered and bonded to the positive electrode current collector 11, and multiple spaced current collector strip setting areas are set along the length direction of the positive electrode current collector 11. The positive electrode film 13 in multiple current collector strip setting areas is removed, and a positive electrode current collector 12 is fixed in one current collector strip setting area to form the positive electrode sheet 1.

[0093] One side of the L-shaped negative electrode current collector 22 is sandwiched between two lithium strips 21, and the other side extends out of the lithium strips 21 to form the negative electrode sheet 2.

[0094] Align one end of the positive electrode 1 along its length with one end of the negative electrode 2 with the negative current collector strip 22 extending from the lithium strip 21, and wind the electrode around this end as the winding center to form a core.

[0095] The core is placed inside the steel shell, the negative electrode current collector 22 extends out of the lithium strip 21 and is connected to the negative electrode post 72, the cover group 7 is placed on the opening of the shell 8, and the positive electrode current collector 12 extends out of the positive electrode current collector 11 and is sandwiched between the cover plate 71 and the shell 8.

[0096] Cut off the portion of the positive current collector 12 that is exposed in the outer casing, and weld the cover plate 71, the casing 8, and the positive current collector 12 sandwiched between them.

[0097] The electrolyte is injected into the housing 8 through the pre-reserved injection hole on the cover assembly 7, and then the injection hole is sealed with a sealing pin 73.

[0098] Among them, the L-shaped negative electrode current collector is a long strip of negative electrode current collector that is folded and spot-welded to form a right angle.

[0099] Following the method described above, the specific steps for manufacturing ultra-high power lithium-ion batteries are as follows:

[0100] 1. Anhydrous lithium chloride was dried in a vacuum drying oven at 160°C for 14 hours. Under argon protection, 88g of anhydrous gallium chloride and 22g of anhydrous lithium chloride were added to a round-bottom flask.

[0101] 2. Place the round-bottom flask into the heating mantle, mix the two solid particles evenly, and heat and stir in an argon-protected environment until the temperature rises to 78°C at a heating rate of 2°C / min. At this point, liquid appears in the round-bottom flask. Continue to heat to 96°C and hold for 10 minutes. At this point, the solid particle mixture will completely melt into a dark liquid.

[0102] 3. Stop heating, remove the round-bottom flask from the heating mantle, and cool it in an argon-protected environment to obtain a gray solid. Add 350 ml of thionyl chloride to it and stir to dissolve most of it. Then add 1.4 g of high-purity chlorosulfonic acid. Transparent flocculent matter will appear in the solution in the round-bottom flask.

[0103] 4. In an argon-protected environment, install a reflux condenser above the round-bottom flask, heat to 55°C, and continue for 4 hours until the transparent flocculent matter in the solution in the round-bottom flask is completely dissolved.

[0104] 5. In an environment with a relative humidity of less than 1%, add a 0.25 mm thick, 1.5 g thick elemental lithium sheet to a round-bottom flask. Install a reflux condenser above the round-bottom flask and heat it to 75°C for 10 hours to remove impurities from the solution.

[0105] 6. In an environment with a relative humidity of less than 1%, after the round-bottom flask has cooled, 32g of sulfur dioxide gas is passed through a gas washing device consisting of concentrated sulfuric acid and calcium chloride, and then introduced into the round-bottom flask to remove water from the solution and prepare an electrolyte.

[0106] 7. For example Figure 2 As shown, the prepared positive electrode film 13 is completely covered and bonded to the positive electrode current collector 11. The length of the positive electrode sheet 1 is 14cm. At appropriate positions (C=3cm, the distance between the three positive electrode current collectors 12 is 4cm), the positive electrode film 13 is removed by mechanical removal or laser powder removal, exposing the positive electrode current collector 11. The positive electrode current collectors 12 are then spot-welded to these positions, and the preparation of the positive electrode sheet 1 is completed.

[0107] 8. For example Figure 3 As shown, the negative electrode current collector 22 is spot-welded into a right angle. After the negative electrode current collector 22 is dried at high temperature, it is placed in an environment with a relative humidity of less than 1%. Two lithium strips 21 with a length of 13cm and the same width are taken, and the negative electrode current collector 22 is sandwiched in the middle. The lithium strips 21 are aligned and rolled and shaped by a roller press to form the negative electrode sheet 2.

[0108] 9. After the positive electrode 1 is dried at high temperature, place it in an environment with a relative humidity of less than 1%. Align one end of the positive electrode 1 with the end of the negative electrode 2 with the negative current collector 22 lead-out head, and use this end as the winding center to wind it.

[0109] 10. After forming the core, place it into the pre-prepared housing 8. The bottom insulating sheet 5 and the bottom diaphragm 4 are already placed at the bottom of the housing 8.

[0110] 11. Spot weld the negative current collector 22 onto the negative terminal post 72 of the pre-prepared cover assembly 7.

[0111] 12. Place all the leads of the positive current collector 12 outside the opening of the housing 8, press down the cover assembly 7, and clamp the positive current collector 12 between the cover assembly 7 and the opening of the housing 8.

[0112] 13. Cut off the part of the positive current collector 12 that is exposed in the outer shell, and weld the cover assembly 7, the shell 8 and the positive current collector 12 sandwiched between them.

[0113] 14. Inject the prepared electrolyte into the housing 8 through the pre-reserved injection hole on the cover plate 71, and seal the injection hole with the sealing nail 73.

[0114] The ultra-high power lithium-ion battery manufactured using the above method was compared with a traditional battery in terms of discharge performance. Figure 5 As shown in the figure, ultra-high power lithium-ion batteries can achieve higher capacity under high power discharge conditions.

[0115] The above embodiments merely illustrate the basic principles and characteristics of the present invention. The present invention is not limited to the above embodiments. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. An electrolyte preparation method, characterized in that, Includes the following steps: S1. In an argon-protected environment, add solid anhydrous gallium chloride and anhydrous lithium chloride to a round-bottom flask; S2. In an argon-protected environment, heat the round-bottom flask to melt anhydrous gallium chloride and anhydrous lithium chloride into a liquid. S3. In an argon-protected environment, after the round-bottom flask has cooled, add thionyl chloride to the round-bottom flask and stir to partially dissolve it. Then add chlorosulfonic acid to the round-bottom flask so that transparent flocculent matter appears in the solution in the round-bottom flask. S4. In an argon-protected environment, install a reflux condenser on a round-bottom flask and heat the flask to completely dissolve the transparent flocculent material in the solution. S5. In an environment with a relative humidity of less than 1%, add a metallic elemental lithium sheet into a round-bottom flask, install a reflux condenser on the round-bottom flask, and heat the round-bottom flask to remove impurities from the solution. S6. In an environment with a relative humidity of less than 1%, after the round-bottom flask has cooled, sulfur dioxide is passed sequentially through a gas washing device containing concentrated sulfuric acid and calcium chloride, and then back into the round-bottom flask to remove water from the solution and prepare an electrolyte.

2. The electrolyte preparation method according to claim 1, characterized in that, In step S1, the number of moles of anhydrous lithium chloride added to the round-bottom flask is a, and the number of moles of anhydrous gallium chloride added to the round-bottom flask is b, where 1.02b≤a≤1.05b; the anhydrous lithium chloride is dried at 150℃-170℃ for more than 12 hours before being added to the round-bottom flask. In step S3, thionyl chloride is added to the round-bottom flask to bring the concentration of anhydrous gallium chloride in the solution to 1.2 M / L-1.8 M / L; the amount of chlorosulfonic acid added to the round-bottom flask is 2 g / L-7 g / L. In step S5, the amount of elemental lithium sheet added to the round-bottom flask is 1.2 g / L-5 g / L; the thickness of the elemental lithium sheet added to the round-bottom flask is 0.2 mm-0.5 mm. In step S6, the amount of sulfur dioxide added to the round-bottom flask is 0.8 M / L-2.0 M / L.

3. The electrolyte preparation method according to claim 1, characterized in that, In step S2, the round-bottom flask is heated to 95℃-98℃ and held at that temperature for 5min-30min; In step S4, the round-bottom flask is heated to 50°C-60°C and kept at that temperature for 4-6 hours. In step S5, the round-bottom flask is heated to 75°C-78°C and kept at that temperature for 6-12 hours.

4. The electrolyte preparation method according to claim 1, characterized in that, Anhydrous gallium chloride has a purity greater than 98% and a particle size of less than 1 mm; Anhydrous lithium chloride has a purity greater than 98% and a particle size of less than 1 mm; The purity of thionyl chloride is greater than 99.5%; The concentration of chlorosulfonic acid is greater than 97%, and its density at 25°C is greater than or equal to 1.

75. The water content of sulfur dioxide is less than 600 ppm.

5. An electrolyte, characterized in that, It is prepared using the electrolyte preparation method according to any one of claims 1 to 4.

6. An ultra-high power lithium-ion battery, characterized in that, Includes the electrolyte as described in claim 5.

7. The ultra-high power lithium-ion battery according to claim 6, characterized in that, The ultra-high power lithium-ion battery includes: The core is formed by winding a positive electrode sheet (1) and a negative electrode sheet (2); the positive electrode sheet (1) includes a positive current collector mesh (11) and a positive current collector strip (12), there are multiple positive current collector strips (12), the multiple positive current collector strips (12) are spaced apart along the length direction of the positive current collector mesh (11), the first end of each positive current collector strip (12) extends out of the positive current collector mesh (11) in the width direction, and the area on the positive current collector mesh (11) where the positive current collector strip (12) is not provided is covered with a positive electrode film (13); the negative electrode sheet (2) includes a negative current collector strip (22) and two layers of lithium strip (21), the negative current collector strip (22) is located between the two layers of lithium strip (21), and the first end of the negative current collector strip (22) extends out of the lithium strip (21) in the width direction. The outer casing includes a housing (8) and a cover assembly (7). One end of the housing (8) has an opening, and the cover assembly (7) covers the opening. The cover assembly (7) includes a cover plate (71) and a negative electrode post (72) that is insulated from the cover plate (71). An injection hole is provided on the cover plate (71), and the electrolyte is injected into the housing (8) through the injection hole. The core is located inside the housing (8) through the opening. The first end of the positive current collector (12) is sandwiched between the housing (8) and the cover plate (71). The first end of the negative current collector (22) is connected to the negative electrode post (72). The area of ​​the core other than the positive current collector (12) and the negative current collector (22) is insulated from the outer casing.

8. The ultra-high power lithium-ion battery according to claim 7, characterized in that, The positive current collector strips (12) are spaced apart perpendicular to the length direction of the positive current collector network (11). The first end of the positive current collector strip (12) extends out of one side of the positive current collector network (11), and the second end of the positive current collector strip (12) is flush with the other side of the positive current collector network (11).

9. The ultra-high power lithium-ion battery according to claim 7, characterized in that, The length of the positive current collector (11) is A, and the minimum distance between the ends of the positive current collector strips (12) and the ends of the positive current collector (11) along the length direction of the positive current collector (11) is C, where C > 0.15A; and / or, The length of the positive current collector (11) is A, and the length of the lithium strip (21) is B, 0.96A≥B≥0.90A.

10. A manufacturing method, characterized in that, The manufacturing method for producing the ultra-high power lithium-ion battery according to any one of claims 6 to 9 includes the following steps: The positive electrode film (13) is completely covered and bonded to the positive electrode current collector (11), and multiple spaced current collector strip setting areas are set along the length direction of the positive electrode current collector (11). The positive electrode film (13) in multiple current collector strip setting areas is removed, and a positive electrode current collector strip (12) is fixed in one current collector strip setting area to form a positive electrode sheet (1). One side of the L-shaped negative electrode current collector (22) is sandwiched between two lithium strips (21), and the other side extends out of the lithium strips (21) to form a negative electrode sheet (2). Align one end of the positive electrode (1) along its length with one end of the negative electrode (2) having a negative current collector strip (22) extending out of the lithium strip (21), and wind it around this end as the winding center to form a core. The core is placed inside the housing (8), the negative electrode current collector (22) extends out of the lithium strip (21) and is connected to the negative electrode post (72), the cover group (7) is set at the opening of the housing (8), and the positive electrode current collector (12) extends out of the positive electrode current collector (11) and is sandwiched between the cover plate (71) and the housing (8); The electrolyte is injected into the housing (8) through the injection hole reserved on the cover plate (71), and then the injection hole is sealed.

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