Self-supporting gel electrolyte winding needle, preparation method thereof and application of self-supporting gel electrolyte winding needle in cylindrical lithium battery

Abstract

The invention provides a self-supporting gel electrolyte winding needle and a preparation method and application thereof in a cylindrical lithium battery, the self-supporting gel electrolyte winding needle comprises a winding needle body, the raw material of the winding needle body comprises a polymer matrix material or a combination of the polymer matrix material and a functional response material, and the winding needle body has a micro-nano pore structure. The polymer matrix material forms a gel structure after adsorbing the electrolyte, has winding support and electrolyte functions, and does not need to be taken out after winding, so that the production process is simplified; deformation in the circulation and storage process can be reduced, and the micro-nano hole structure of the winding needle can provide high liquid storage capacity. The introduced functional response material enables the gel structure to have concentration and temperature double responsiveness, when the concentration of the electrolyte in the battery cell is reduced or the temperature is increased, the gel network expands, and the stored electrolyte is automatically released; and when the concentration is increased or the temperature is reduced, the gel shrinks and adsorbs the electrolyte again, so that electrolyte self-regulation release without external control is realized in the charge-discharge cycle process.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a self-supporting gel electrolyte winding needle, its preparation method, and its application in cylindrical lithium batteries. Background Technology

[0002] With the rapid development of electronic devices, lithium-ion batteries, as a power source with high energy density and long cycle life, have been widely used in portable electronic devices, electric vehicles, and energy storage systems. Among various lithium battery structures, cylindrical lithium batteries have become one of the most widely used types of lithium batteries on the market due to their advantages such as stable structure, mature manufacturing process, and relatively low cost.

[0003] Traditional cylindrical lithium batteries typically employ a wound structure, where the positive electrode, negative electrode, and separator are wound into a cylindrical shape in a specific order and placed inside a metal casing. During the winding process, metal or plastic winding pins are usually used as supports to ensure the stability of the battery's internal structure.

[0004] However, traditional cylindrical lithium batteries have a series of problems during cycling and storage: First, changes in internal pressure can cause deformation of the battery casing, affecting the battery's appearance and safety performance; second, the electrolyte is gradually consumed after long-term cycling, leading to increased internal resistance and capacity decay; in addition, traditional rigid winding needles are prone to damaging the electrode sheets during winding and cannot provide additional support or electrolyte replenishment during battery use.

[0005] Therefore, there is an urgent need to develop a new type of winding needle structure that can not only ensure the smooth progress of the winding process, but also provide additional support and electrolyte replenishment during battery use, thereby improving the cycle performance and safety performance of the battery. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a self-supporting gel electrolyte winding needle to solve the problems of traditional rigid winding needles that easily damage the electrode during winding and cannot provide additional support during battery use; existing cylindrical lithium batteries suffer from deformation of the battery casing due to internal pressure changes during cycling and storage, affecting the battery's appearance and safety performance; and the electrolyte is gradually consumed after long-term cycling, leading to increased internal resistance and capacity decay. Furthermore, this invention will also provide a method for preparing the self-supporting gel electrolyte winding needle; in addition, this invention will also provide the application of the self-supporting gel electrolyte winding needle in cylindrical lithium batteries.

[0007] To achieve the above and other related objectives, the present invention provides the following technical solutions: In a first aspect, the present invention provides a self-supporting gel electrolyte winding needle, comprising a winding needle body, wherein the raw material constituting the winding needle body comprises a polymer matrix material, and the winding needle body has a micro-nanopore structure with a porosity of 30% to 60% and a pore size of 10 to 500 nm. The polymer matrix material forms a gel structure after adsorbing the electrolyte, which enables the winding needle body to maintain rigidity and structural stability after being wetted by the electrolyte.

[0008] Furthermore, the polymer matrix material is selected from at least one of polyvinyl alcohol (PVA), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polymethyl methacrylate (PMMA), poly(vinylidene fluoride-co-hexafluoropropylene) [P(VDF-HFP)] and its derivatives.

[0009] Furthermore, the polymer matrix material is a combination of PVDF and PMMA, with a mass ratio of PVDF to PMMA of 3:1 to 1:1.

[0010] Furthermore, the raw materials constituting the winding needle body also include functional responsive materials, which are selected from fluorinated ionic liquids, polyethylene glycol block copolymers, or block copolymers with polar end groups.

[0011] Functional responsive materials endow the winding needles with self-responsive adsorption-desorption properties based on electrolyte concentration gradients, enabling the winding needles to self-regulate electrolyte release according to changes in electrolyte concentration and temperature. Specifically, after adsorbing electrolyte, the winding needles form a multiphase gel network composed of a polymer matrix and the functional responsive material. When the electrolyte concentration inside the cell decreases or the temperature increases, the gel network expands, and the stored electrolyte is automatically released. When the concentration rises again or the temperature decreases, the gel contracts and re-adsorbs the electrolyte, thus achieving self-regulating electrolyte release without external control during charge-discharge cycles.

[0012] Furthermore, the wound needle body is a porous needle-like body prepared by phase separation or freeze-drying.

[0013] Furthermore, the pore size of the micro-nanopore structure in the winding needle body is preferably 50~200nm.

[0014] A second aspect of the present invention provides a method for preparing a self-supporting gel electrolyte winding needle, comprising the following steps: (1) Polymer solution preparation: The polymer matrix material or a combination of polymer matrix material and functional responsive material is dissolved in a solvent to form a polymer solution; (2) Molding: The polymer solution is injected into a needle-shaped mold, and a needle-shaped preform with a micro-nano porous structure is formed by phase separation or freeze drying. (3) Drying: Dry the needle-shaped preform at 40-80℃ for 12-24 hours to remove the solvent; (4) Electrolyte soaking: The dried needle blank is soaked in the electrolyte for 2 to 6 hours to allow it to fully absorb the electrolyte and form a gel structure, thereby obtaining the wound needle body.

[0015] Furthermore, in step (1), the solvent is N-methylpyrrolidone (NMP) or dimethylformamide (DMF).

[0016] Furthermore, in step (1), the concentration of the polymer matrix material in the polymer solution is 5% to 15 wt%; the concentration of the functional response material is 0.5% to 3 wt%.

[0017] Furthermore, the mass ratio of the polymer matrix material to the functional responsive material in the polymer solution is 1:0.1~0.3.

[0018] Furthermore, in step (4), the electrolyte is a solution containing LiPF6, and its solvent is selected from at least one of EC, DMC, DEC, and EMC.

[0019] A third aspect of the present invention provides a cylindrical lithium battery comprising the aforementioned self-supporting gel electrolyte winding needle, further comprising the battery casing, a positive electrode, a negative electrode, and a separator, wherein the positive and negative electrode and the separator are wound on the winding needle body, and the winding needle body is located at the center of the battery casing. During battery cycling or storage, the winding needle body can dynamically release the adsorbed electrolyte to compensate for electrolyte loss inside the battery, thereby maintaining battery structural stability and delaying internal resistance growth.

[0020] Furthermore, the ratio of the difference between the outer and inner diameters of the winding needle body to the inner diameter of the battery casing is 1:0.6~0.95; the ratio of the length of the winding needle body to the height inside the battery casing is 1:0.9~1.0.

[0021] Furthermore, the liquid absorption rate of the winding needle body is 20% to 60%. After 200 cycles, the capacity retention rate of the cylindrical lithium battery is ≥94%, and the battery diameter change rate is ≤0.7%; after 200 cycles, the internal resistance growth rate of the battery is 0.1 to 0.2 mΩ / cycle, and the cycle life exceeds 500 cycles.

[0022] As described above, the self-supporting gel electrolyte winding needle of the present invention, its preparation method, and its application in cylindrical lithium batteries have the following beneficial effects: 1. The gelled winding needle forms a stable support after being wetted by the electrolyte, effectively supporting the electrode roll and reducing deformation during cycling and storage. Actual measurements show that the battery diameter change rate is reduced from the traditional 2.5% to below 0.7%. The micro-nano porous structure of the winding needle provides high electrolyte storage capacity, dynamically releasing electrolyte during cycling to compensate for consumption, increasing the capacity retention rate from 85% to over 94% after 200 cycles. The winding needle combines winding support and electrolyte functions, eliminating the need for removal after winding, simplifying the production process and reducing equipment load.

[0023] 2. This winding needle can be used as a rigid winding needle in the winding process. After winding, it is left inside the cell and forms a gel structure with self-response regulation capability after absorbing electrolyte. This enables the battery to dynamically release and absorb electrolyte at different cycle stages, maintain the stability of ion transport channels, and significantly improve the cycle life, safety and dimensional stability of cylindrical batteries. Attached Figure Description

[0024] Figure 1 The image shown is a photograph of the cylindrical lithium battery prepared in Example 3 of the present invention; wherein: (a) is a photograph of the new battery, and (b) is a photograph after 500 cycles. Detailed Implementation

[0025] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0026] Example 1 This embodiment provides a self-supporting gel electrolyte wound needle, including a wound needle body. The wound needle body is composed of a polymer matrix material or a combination of a polymer matrix material and a functional responsive material. The wound needle body has a micro / nanoporous structure with a porosity of 30%–60% and a pore size of 10–500 nm. The polymer matrix material forms a gel structure after adsorbing the electrolyte, enabling the wound needle body to maintain rigidity and structural stability after being wetted by the electrolyte.

[0027] This embodiment also provides a method for preparing a self-supporting gel electrolyte wound needle, the method comprising the following steps: (1) Polymer solution preparation: A polymer solution is formed by dissolving the polymer matrix material or a combination of polymer matrix material and functional responsive material in a solvent. In this step, the polymer matrix material may be selected from at least one of polyvinyl alcohol (PVA), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polymethyl methacrylate (PMMA), poly(vinylidene fluoride-co-hexafluoropropylene) [P(VDF-HFP)] and its derivatives. Preferably, the polymer matrix material is a combination of PVDF and PMMA, with a mass ratio of PVDF to PMMA of 3:1 to 1:1. The functional responsive material may be selected from fluorinated ionic liquids, polyethylene glycol block copolymers, or block copolymers with polar end groups. The functional responsive material can impart self-responsive adsorption-desorption properties to the winding needle according to the electrolyte concentration gradient, enabling the winding needle to achieve self-regulating release of electrolyte according to changes in electrolyte concentration and temperature. The concentration of the polymer matrix material in the polymer solution is 5% to 15 wt%; the concentration of the functional responsive material is 0.5% to 3 wt%. The preferred mass ratio of polymer matrix material to functional responsive material is 1:0.1~0.3. The preferred solvent is N-methylpyrrolidone (NMP) or dimethylformamide (DMF).

[0028] (2) Molding: The polymer solution is injected into a needle-shaped mold, and a needle-shaped preform with a micro-nano porous structure is formed by phase separation or freeze drying. The needle-shaped preform prepared by this method has a micro-nano porous structure with a porosity of 30% to 60% and a pore size of 10 to 500 nm, preferably 50 to 200 nm.

[0029] (3) Drying: The needle-shaped preform is dried at 40-80℃ for 12-24 hours to remove the solvent. During the drying process, the micro- and nano-porous structure of the needle-shaped preform is preserved, providing sufficient space for subsequent absorption of electrolyte.

[0030] (4) Electrolyte soaking: The dried needle-shaped preform is soaked in the electrolyte for 2 to 6 hours to allow it to fully absorb the electrolyte and form a gel structure, thereby obtaining the wound needle body. The electrolyte is a solution containing LiPF6, and its solvent is selected from at least one of ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl ethyl carbonate (EMC).

[0031] The self-supporting gel electrolyte winding needle prepared by the above method maintains rigidity and structural stability after being immersed in electrolyte. When the winding needle contains a functional responsive material, it forms a multiphase gel network composed of a polymer matrix and the functional responsive material after adsorbing the electrolyte. When the electrolyte concentration inside the cell decreases or the temperature increases, the gel network expands, and the stored electrolyte is automatically released. When the concentration rises again or the temperature decreases, the gel shrinks and re-adsorbs the electrolyte, thus achieving self-regulating electrolyte release without external control during charge-discharge cycles.

[0032] The prepared winding needle can be applied to cylindrical lithium batteries, located at the center inside the battery casing, with the positive electrode, negative electrode, and separator wound around the needle body. During battery cycling or storage, the winding needle body can dynamically release the adsorbed electrolyte to compensate for electrolyte loss inside the battery, thereby maintaining battery structural stability and slowing down internal resistance growth. The electrolyte absorption rate of the winding needle body can reach 20%–60%. After 200 cycles, the capacity retention rate of cylindrical lithium batteries using this winding needle is ≥96%, and the battery diameter change rate is ≤0.8%; the internal resistance growth rate after 200 cycles is 0.1–0.2 mΩ / cycle, and the cycle life exceeds 500 cycles.

[0033] Example 2 This embodiment provides a self-supporting gel electrolyte winding needle, the preparation method of which includes the following steps: (1) Preparation of polymer solution: PMMA powder and PVDF powder in a mass ratio of 1:1 were dissolved in DMF solvent to form a polymer solution with a mass concentration of 8%.

[0034] (2) Molding: The polymer solution is injected into a needle-shaped mold with a diameter of 12 mm (corresponding to an inner diameter of 15 mm in the hollow part of the 21700 battery, with a diameter ratio of 80%) and a length of 70 mm (corresponding to a height of 70 mm in the 21700 battery, with a length ratio of 100%), and a needle-shaped preform with a micro-nanoporous structure is formed by freeze-drying (freezing at -40℃ for 12 hours and vacuum drying for 24 hours).

[0035] (3) Drying: The needle-shaped preform was dried at 50°C for 24 hours to remove the DMF solvent, resulting in a wound needle preform with a micro-nanoporous structure (pore size 100-300 nm, porosity 50%). During the drying process, the micro-nanoporous structure of the needle-shaped preform was preserved, providing sufficient space for subsequent electrolyte absorption.

[0036] (4) Electrolyte soaking: The electrolyte is 1.2M LiPF6 dissolved in EC+DEC+DMC (volume ratio 1:1:1). The dried needle-shaped preform is immersed in the electrolyte for 5 hours to allow it to fully absorb the electrolyte and form a gel structure, thereby obtaining the wound needle body.

[0037] This embodiment also provides a cylindrical lithium battery using the winding needle body, which is prepared as follows: the above-mentioned winding needle body is used to wind the electrode sheet (positive electrode: LiCoO2, negative electrode: graphite, separator: PE). After winding, it remains in the hollow interior of the battery casing. Subsequent processes such as encapsulation, liquid injection, and formation are completed to obtain a 21700 type cylindrical lithium battery.

[0038] The performance of this cylindrical lithium battery was tested, and the results are as follows: Capacity retention after 200 cycles: 94.9%; Battery diameter change rate after 200 cycles: 0.6%; After 200 cycles, the battery internal resistance increases at a rate of 0.18 mΩ / cycle, and the cycle life exceeds 500 cycles.

[0039] Example 3 This embodiment provides a self-supporting gel electrolyte winding needle, the preparation method of which includes the following steps: (1) Preparation of polymer solution: A polymer solution was formed by dissolving PMMA powder, PVDF powder and fluorinated ionic liquid (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, [EMIM][TFSI]) in DMF solvent at a mass ratio of 1:1:0.5. The concentration of the polymer matrix material in the polymer solution was 8 wt% and the concentration of the fluorinated ionic liquid was 2 wt%.

[0040] (2) Molding: The polymer solution is injected into a needle-shaped mold with a diameter of 12 mm (corresponding to an inner diameter of 15 mm in the hollow part of the 21700 battery, with a diameter ratio of 80%) and a length of 70 mm (corresponding to a height of 70 mm in the 21700 battery, with a length ratio of 100%), and a needle-shaped preform with a micro-nanoporous structure is formed by freeze-drying (freezing at -40℃ for 12 hours and vacuum drying for 24 hours).

[0041] (3) Drying: The needle-shaped preform was dried at 50°C for 24 hours to remove the DMF solvent, resulting in a wound needle preform with a micro-nanoporous structure (pore size 50-250 nm, porosity approximately 45%). During the drying process, the micro-nanoporous structure of the needle-shaped preform was preserved, providing sufficient space for subsequent electrolyte absorption.

[0042] (4) Electrolyte soaking: The electrolyte is 1.2M LiPF6 dissolved in EC+DEC+DMC (volume ratio 1:1:1). The dried needle-shaped preform is immersed in the electrolyte for 5 hours to allow it to fully absorb the electrolyte and form a gel structure, thereby obtaining the wound needle body.

[0043] This embodiment also provides a cylindrical lithium battery using the winding needle body, which is prepared as follows: the above-mentioned winding needle body is used to wind the electrode sheet (positive electrode: LiCoO2, negative electrode: graphite, separator: PE). After winding, it remains in the hollow interior of the battery casing. Subsequent processes such as encapsulation, liquid injection, and formation are completed to obtain a 21700 type cylindrical lithium battery.

[0044] The performance of this cylindrical lithium battery was tested, and the results are as follows: Capacity retention after 200 cycles: 96.4%; Battery diameter change rate after 200 cycles: 0.55%; After 200 cycles, the battery internal resistance increases at a rate of 0.16 mΩ / cycle, and the cycle life exceeds 500 cycles.

[0045] Among them, the comparison photos of lithium batteries before and after cycling are as follows: Figure 1 As shown; where: (a) is a photo of a new battery, and (b) is a photo after 500 cycles.

[0046] The self-supporting gel electrolyte winding needle prepared by the above method maintains rigidity and structural stability after being immersed in electrolyte. When the winding needle contains a functional responsive material, it forms a multiphase gel network composed of a polymer matrix and the functional responsive material after adsorbing the electrolyte. When the electrolyte concentration inside the cell decreases or the temperature increases, the gel network expands, and the stored electrolyte is automatically released. When the concentration rises again or the temperature decreases, the gel shrinks and re-adsorbs the electrolyte, thus achieving self-regulating electrolyte release without external control during charge-discharge cycles.

[0047] Example 4 This embodiment provides a self-supporting gel electrolyte winding needle, the preparation method of which includes the following steps: (1) Preparation of polymer solution: A polymer solution was formed by dissolving P(VDF-HFP) and PEG blocks (polyethylene glycol monomethyl ether) in DMF solvent at a mass ratio of 1:0.2. The concentration of the polymer matrix material in the polymer solution was 10 wt% and the concentration of polyethylene glycol monomethyl ether was 2 wt%.

[0048] (2) Molding: The polymer solution is injected into a needle-shaped mold with a diameter of 8 mm (corresponding to an inner diameter of 10 mm in the hollow part of the 18650 battery, with a diameter ratio of 80%) and a length of 65 mm (corresponding to a height of 65 mm in the 18650 battery, with a length ratio of 100%), and a needle-shaped preform with a micro-nanoporous structure is formed by freeze-drying (freezing at -40℃ for 12 hours and vacuum drying for 24 hours).

[0049] (3) Drying: The needle-shaped preform was dried at 50°C for 24 hours to remove the DMF solvent, resulting in a wound needle preform with a micro-nanoporous structure (pore size 100-250 nm, porosity 48%). During the drying process, the micro-nanoporous structure of the needle-shaped preform was preserved, providing sufficient space for subsequent electrolyte absorption.

[0050] (4) Electrolyte soaking: The electrolyte is 1.2M LiPF6 dissolved in EC+DEC+DMC (volume ratio 1:1:1). The dried needle-shaped preform is immersed in the electrolyte for 5 hours to allow it to fully absorb the electrolyte and form a gel structure, thereby obtaining the wound needle body.

[0051] This embodiment also provides a cylindrical lithium battery using the winding needle body, which is prepared as follows: the above-mentioned winding needle body is used to wind the electrode sheet (positive electrode: LiCoO2, negative electrode: graphite, separator: PE). After winding, it remains in the hollow interior of the battery casing. Subsequent processes such as encapsulation, liquid injection, and formation are completed to obtain an 18650 type cylindrical lithium battery.

[0052] The performance of this cylindrical lithium battery was tested, and the results are as follows: Capacity retention after 200 cycles: 96.3%; Battery diameter change rate after 200 cycles: 0.52%; After 200 cycles, the battery internal resistance increases at a rate of 0.15 mΩ / cycle, and the cycle life exceeds 500 cycles.

[0053] Example 5 This embodiment provides a self-supporting gel electrolyte winding needle, the preparation method of which includes the following steps: (1) Preparation of polymer solution: A polymer solution was formed by dissolving PVDF powder (molecular weight 500,000) and a block copolymer monomer with polar end groups (PEG-b-PMMA) in NMP solvent at a mass ratio of 1:0.2. The concentration of the polymer matrix material in the polymer solution was 10 wt% and the concentration of PEG-b-PMMA was 2 wt%.

[0054] (2) Molding: The polymer solution is injected into a needle-shaped mold with a diameter of 8 mm (corresponding to an inner diameter of 10 mm in the hollow part of the 18650 battery, with a diameter ratio of 80%) and a length of 65 mm (corresponding to a height of 65 mm in the 18650 battery, with a length ratio of 100%). A needle-shaped preform with a micro-nano porous structure is formed by phase separation (water bath temperature 25℃, solidification time 30 min).

[0055] (3) Drying: The needle-shaped preform was dried at 60°C for 18 hours to remove the NMP solvent, resulting in a wound needle preform with a micro-nanoporous structure (pore size 50-200 nm, porosity 45%). During the drying process, the micro-nanoporous structure of the needle-shaped preform was preserved, providing sufficient space for subsequent electrolyte absorption.

[0056] (4) Electrolyte soaking: The electrolyte is 1.2M LiPF6 dissolved in EC+DEC+DMC (volume ratio 1:1:1). The dried needle-shaped preform is immersed in the electrolyte for 4 hours to allow it to fully absorb the electrolyte and form a gel structure, thereby obtaining the wound needle body.

[0057] This embodiment also provides a cylindrical lithium battery using the winding needle body, which is prepared as follows: the above-mentioned winding needle body is used to wind the electrode sheet (positive electrode: LiCoO2, negative electrode: graphite, separator: PE). After winding, it remains in the hollow interior of the battery casing. Subsequent processes such as encapsulation, liquid injection, and formation are completed to obtain an 18650 type cylindrical lithium battery.

[0058] The performance of this cylindrical lithium battery was tested, and the results are as follows: Capacity retention after 200 cycles: 95.5%; Battery diameter change rate after 200 cycles: 0.6%; After 200 cycles, the battery internal resistance increases at a rate of 0.19 mΩ / cycle, and the cycle life exceeds 500 cycles.

[0059] In summary, the polymer matrix material of this invention forms a gel structure after adsorbing the electrolyte. The winding needle serves both as a winding support and an electrolyte, eliminating the need for removal after winding and simplifying the production process. It also reduces deformation during cycling and storage, and the micro-nano porous structure of the winding needle provides high electrolyte storage capacity. The introduced functional responsive material gives the gel structure dual concentration and temperature responsiveness. When the electrolyte concentration inside the cell decreases or the temperature increases, the gel network expands, and the stored electrolyte is automatically released. When the concentration rises again or the temperature decreases, the gel contracts and re-adsorbs the electrolyte, thus achieving self-regulating electrolyte release without external control during charge-discharge cycles. Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial applicability.

[0060] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A self-supporting gel electrolyte winding needle, comprising a winding needle body, characterized in that, The raw materials constituting the winding needle body include a polymer matrix material or a combination of a polymer matrix material and a functional responsive material. The winding needle body has a micro-nanopore structure with a porosity of 30% to 60% and a pore size of 10 to 500 nm. The polymer matrix material forms a gel structure after adsorbing the electrolyte.

2. The self-supporting gel electrolyte winding needle according to claim 1, characterized in that, The polymer matrix material is selected from at least one of PVA, PAN, PVDF, PMMA, P(VDF-HFP) and their derivatives.

3. The self-supporting gel electrolyte winding needle according to claim 1, characterized in that, The functional responsive material is selected from fluorinated ionic liquids, polyethylene glycol block copolymers, or block copolymers with polar end groups.

4. A method for preparing a self-supporting gel electrolyte winding needle as described in any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Dissolve the polymer matrix material or a combination of polymer matrix material and functional responsive material in a solvent to form a polymer solution; (2) The polymer solution is injected into a needle mold, and a needle-shaped preform with a micro-nano porous structure is formed by phase separation or freeze drying. (3) Dry the needle-shaped preform at 40-80°C for 12-24 hours to remove the solvent; (4) Immerse the dried needle-shaped blank in the electrolyte for 2 to 6 hours to allow it to fully absorb the electrolyte and form a gel structure, thereby obtaining the wound needle body.

5. The method for preparing the self-supporting gel electrolyte winding needle according to claim 4, characterized in that, In step (1), the solvent is NMP or DMF.

6. The method for preparing the self-supporting gel electrolyte winding needle according to claim 4, characterized in that, In step (1), the concentration of the polymer matrix material in the polymer solution is 5% to 15 wt%; the concentration of the functional response material is 0.5% to 3 wt%.

7. The method for preparing the self-supporting gel electrolyte winding needle according to claim 4, characterized in that, In step (4), the electrolyte is a solution containing LiPF6, and its solvent is selected from at least one of EC, DMC, DEC, and EMC.

8. A cylindrical lithium battery comprising a self-supporting gel electrolyte winding needle as described in any one of claims 1 to 3, characterized in that, It also includes the battery casing, positive electrode, negative electrode, and separator, wherein the positive and negative electrode and separator are wound on the winding needle body, and the winding needle body is located at the center inside the battery casing.

9. The cylindrical lithium battery according to claim 8, characterized in that, The ratio of the difference between the outer and inner diameters of the winding needle body to the inner diameter of the battery casing is 1:0.6~0.95; the ratio of the length of the winding needle body to the height inside the battery casing is 1:0.9~1.

0.

10. The cylindrical lithium battery according to claim 8, characterized in that, The cylindrical lithium battery retains ≥94% capacity after 200 cycles, and the battery diameter change rate is ≤0.7%; the internal resistance growth rate after 200 cycles is 0.1~0.2 mΩ / cycle, and the cycle life exceeds 500 cycles.

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