Battery and electric equipment

Abstract

The invention belongs to the technical field of battery preparation, and particularly relates to a battery and electric equipment. The battery comprises a shell and a roll core arranged in the shell, a cylindrical body is arranged in the center of the roll core, the cylindrical body contains a flame retardant, the cylindrical body is provided with a first cylindrical section, a third cylindrical section and a second cylindrical section arranged between the first cylindrical section and the third cylindrical section in the length direction of the cylindrical body, and the second cylindrical section is arranged between the first cylindrical section and the third cylindrical section. The first column section, the second column section and the third column section contain the flame retardant; and the content of the flame retardant in the second column section is smaller than the content of the flame retardant in the first column section and the third column section. The content of the flame retardant in the middle of the columnar body is low, light weight and low cost are achieved, the content of the flame retardant at the two ends of the columnar body is high, flame retardance at the high-temperature tab is more targeted and efficient, the spare space in the roll core is fully utilized, the safety performance is improved, the electrochemical performance of the battery is improved, and the high energy density is kept.

Description

Technical Field

[0001] The invention belongs to the technical field of battery preparation, and in particular relates to a battery and electrical equipment. Background Art

[0002] The safety of traditional cylindrical batteries is still insufficient. Overheating, fire and even explosion may occur during use. In addition, the hollow space in the middle of the cylindrical battery is not fully utilized, resulting in space waste, which is not conducive to improving the overall performance and energy density of the battery. In addition, when the pole piece is rolled up, the poor rolling force leads to poor contact between the positive and negative pole pieces, which affects the battery's charge and discharge performance and cycle life, and reduces the battery's reliability and stability. Summary of the invention

[0003] Therefore, the main purpose of this application is to provide a battery and electrical equipment to solve the problems of insufficient safety of existing traditional cylindrical batteries and insufficient utilization of hollow space.

[0004] To this end, this application provides the following technical solutions.

[0005] The present application provides a battery, the battery comprising a shell, a winding core arranged in the shell, a columnar body arranged at the center of the winding core, the columnar body containing a flame retardant, along the length direction of the columnar body, the columnar body has a first column segment, a third column segment and a second column segment arranged between the first column segment and the third column segment, the first column segment, the second column segment and the third column segment containing the flame retardant;

[0006] The content of the flame retardant in the second column section is less than the content of the flame retardant in the first column section and the third column section.

[0007] Furthermore, the ratio of the lengths of the first column segment, the second column segment and the third column segment is (1-2):1:(1-2).

[0008] Furthermore, based on the total mass of the flame retardant in the column as 100%, the content of the flame retardant in the first column section is 35-50wt%; the content of the flame retardant in the second column section is 5-20wt%; and the content of the flame retardant in the third column section is 35-50wt%.

[0009] Further, the particle size Dv10 of the flame retardant particles is 5-10 μm, Dv50 is 10-50 μm, and Dv99 is 50-90 μm; and / or,

[0010] The flame retardant includes at least one of polyphosphazene, ammonium polyphosphate, phosphate, red phosphorus and organic phosphorus.

[0011] Furthermore, the ratio of the length of the column to the length of the winding core is (91-98):100.

[0012] Furthermore, the columnar body also includes a high molecular hot-melt material, and the first column segment, the second column segment and the third column segment contain the high molecular hot-melt material.

[0013] Furthermore, the polymer hot-melt material includes at least one of EVA (ethylene-vinyl acetate copolymer), POE (ethylene-butylene polymer), PEO (polyethylene oxide) and PCL (polycaprolactone).

[0014] Further, the shell is cylindrical; and / or the columnar body is a cylinder.

[0015] Furthermore, the bonding strength between the interior of the winding core and the columnar body is 12-30 N / cm.

[0016] The present application also provides an electrical device, comprising the above-mentioned battery.

[0017] The technical solution of this application has the following advantages:

[0018] The battery roll core of the present application is provided with a column at the center, the column contains a flame retardant, and along the length direction of the column, the flame retardant in the center of the column is lower than that at the two ends, the flame retardant content in the middle of the column is low, so as to achieve light weight and low cost, and the flame retardant content at the two ends of the column is high, which is more targeted and efficient for the higher temperature of the pole ear, can improve the overall performance and safety of the battery, and make full use of the free space inside the cylindrical battery, which is conducive to improving the overall performance of the battery and maintaining high energy density, as well as improving safety performance. When the battery temperature is too high, the flame retardant in the column absorbs heat, lowers the battery temperature, and the formed product adheres to the positive and negative pole ears to flame retardant; the heat dissipation in the inner circle of the roll core in the battery is slow and the temperature is high. When the battery temperature is too high, the column can cool down and flame retardant in the inner circle of the roll core in time; thereby reducing dangerous situations such as overheating and fire, and improving the safety performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 is a schematic structural diagram of a battery in Example 1 of the present invention;

[0021] Reference numerals:

[0022] 1- columnar body; 2- shell;

[0023] 11- first column section; 12- second column section; 13- third column section. DETAILED DESCRIPTION

[0024] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0025] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0026] As analyzed in the background technology, the safety of traditional cylindrical batteries is still insufficient, and they may overheat, catch fire, or even explode during use. In addition, the hollow space in the middle of the cylindrical battery is not fully utilized, resulting in space waste, which is not conducive to the overall performance and energy density of the battery. In addition, during the winding process, the poor winding force causes poor contact between the positive and negative electrode sheets, affecting battery performance.

[0027] In order to solve the above problems, the present application provides a battery, which includes a shell and a winding core arranged in the shell, a columnar body is arranged in the center of the winding core, and the columnar body contains a flame retardant. Along the length direction of the columnar body, the columnar body has a first column segment, a third column segment and a second column segment arranged between the first column segment and the third column segment, and the first column segment, the second column segment and the third column segment contain the flame retardant; the content of the flame retardant in the second column segment is less than the content of the flame retardant in the first column segment and the third column segment.

[0028] The battery core of the present application is provided with a columnar body at the center, which contains a flame retardant, and along the length direction of the columnar body, the flame retardant content in the center of the columnar body is lower than that at the two ends, and the flame retardant content in the middle of the columnar body is low, so as to achieve light weight and low cost, and the flame retardant content at the two ends of the columnar body is high, which is more targeted and efficient for the high-temperature pole ear, and can improve the overall performance and safety of the battery, and make full use of the empty space inside the cylindrical battery, which is conducive to improving the overall performance of the battery and maintaining high energy density, as well as improving safety performance. When the battery temperature is too high, the flame retardant in the columnar body absorbs heat, reduces the battery temperature, and the formed product adheres to the positive and negative pole ears to flame retardant; the heat dissipation at the inner circle of the core in the battery is slow and the temperature is high. When the battery temperature is too high, the columnar body can cool down and flame retardant in time at the inner circle of the core, thereby reducing dangerous situations such as overheating and fire, and improving the safety performance of the battery. The core described in the present application is obtained by stacking the positive pole piece, the diaphragm, and the negative pole piece in sequence and winding them; the battery includes a core, an electrolyte, a shell, etc.

[0029] In addition, the columnar body can also support the winding core, so that the winding core maintains a good winding force, improves the interface contact between the positive and negative pole pieces, and avoids the poor interface contact between the positive and negative pole pieces due to poor pole piece winding force, which affects the battery's charge and discharge performance and cycle life; at the same time, it can also improve the reliability and stability of the battery.

[0030] In some embodiments, the ratio of the lengths of the first column segment, the second column segment, and the third column segment is (1-2):1:(1-2). The second column segment of the present application is located in the middle of the hollow structure in the middle of the core, and the lengths of the first column segment and the third column segment are not less than the second column segment, so that the first column segment and the third column segment become the key column segments for the column to play a flame retardant role. Controlling the length of the second column segment can also appropriately reduce the amount of flame retardant in the length direction to achieve a low-cost, lightweight effect. The present application regulates the length ratio of the three column segments so that the column can achieve a low-cost, lightweight effect without affecting the flame retardant effect. It should be explained that the lengths of the first column segment and the third column segment can be the same or different.

[0031] In some embodiments, taking the total mass of the flame retardant in the column as 100%, the content of the flame retardant in the first column section is 35-50wt%; the content of the flame retardant in the second column section is 5-20wt%; the content of the flame retardant in the third column section is 35-50wt%. The flame retardant content of the first column section and the third column section of the present application is higher than that of the second column section, that is, the flame retardant content at both ends of the column is high, which can ensure that the first column section and the third column section play a major flame retardant role, and the flame retardant content of the second column section is low, and the amount of flame retardant can be appropriately reduced from the perspective of the column content, so as to achieve a low-cost and lightweight effect. It should be explained that the content of the flame retardant in the first column section and the third column section can be the same or different, and the types of flame retardants can be the same or different.

[0032] In some embodiments, the columnar body also includes a polymer hot-melt material, and the first column segment, the second column segment, and the third column segment contain the polymer hot-melt material. The polymer hot-melt material includes at least one of EVA (ethylene-vinyl acetate copolymer), POE (ethylene-butene polymer), PEO (polyethylene oxide), and PCL (polycaprolactone). The columnar body of the present application includes a polymer hot-melt material, which can wrap the flame retardant, protect the flame retardant from corrosion by the electrolyte, and prevent the flame retardant from entering the electrolyte and affecting the battery performance; on the other hand, it can make the bonding force between the columnar body and the inside of the winding core tighter, so that the columnar body plays a supporting role and the winding core maintains a good tightening force.

[0033] In some embodiments, the particle size Dv10 of the flame retardant particles is 5-10 μm, Dv50 is 10-50 μm, and Dv99 is 50-90 μm; and / or,

[0034] The flame retardant includes at least one of polyphosphazene, ammonium polyphosphate, phosphate, red phosphorus and organic phosphorus.

[0035] In order to protect the flame retardant from corrosion by the electrolyte and to make the column and the inside of the winding core tightly bonded, a polymer hot-melt material is generally added to the column. The particle size distribution of the flame retardant particles in the column of the present application is within the above range, so that after the polymer hot-melt material encapsulating the flame retardant is heated and melted, the large particles of flame retardant can be easily exposed and released to exert a flame retardant effect. Phosphate flame retardants can be but are not limited to at least one of zirconium phosphate, calcium phosphate and zinc phosphate; organophosphorus flame retardants can be but are not limited to at least one of guanidine phosphonate, phosphate ester and phosphite. When the core temperature is too high, these flame retardants can absorb heat and lower the battery temperature. The thermal decomposition products formed can adhere to the surface of the pole piece, play a good flame retardant role, and effectively improve the safety performance of the battery.

[0036] Considering the swelling phenomenon of polymer materials in the electrolyte, in some embodiments, the ratio of the length of the column to the length of the winding core is (91-98): 100. This can prevent the column from swelling in the electrolyte and becoming too long to support the tab, thereby affecting the current carrying capacity of the tab and the electrochemical performance of the battery.

[0037] In some embodiments of the battery, the first column section includes a polymer hot-melt material and a flame retardant in a mass ratio of (52.5-60): (40-47.5); the second column section includes a polymer hot-melt material and a flame retardant in a mass ratio of (60-95): (5-40); the third column section includes a polymer hot-melt material and a flame retardant in a mass ratio of (52.5-60): (40-47.5). The present application regulates the amount of polymer hot-melt material and flame retardant in the three column sections so that the flame retardant content in the second column section located in the middle section is lower than that in the first column section and the third column section. On the one hand, it ensures that the first column section and the third column section play a major flame retardant role, and on the other hand, the mass of the flame retardant is appropriately reduced to achieve a low-cost, lightweight effect. It should be explained that the type of flame retardant, the type of polymer hot-melt material, and the mass ratio of flame retardant to polymer hot-melt material in the first column section and the third column section may be the same or different.

[0038] In some embodiments, the shell is cylindrical; and / or the columnar body is a cylinder.

[0039] In some embodiments, the bonding strength between the interior of the core and the column is 12-30 N / cm. The bonding strength between the interior of the core and the column is tested by a method known in the art, such as "T" type 180° peeling.

[0040] In another embodiment of the present application, a method for preparing the above-mentioned battery is provided, comprising:

[0041] (1) After the polymer hot-melt material is melted, a flame retardant is added and the mixture is stirred evenly to prepare polymer hot-melt liquids corresponding to the first column segment, the second column segment and the third column segment respectively.

[0042] (2) After the core is wound, the polymer hot-melt liquid corresponding to the second column segment is injected into the middle of the hollow structure in the middle of the core, and then the polymer hot-melt liquid corresponding to the first column segment and the third column segment are simultaneously injected into both ends of the hollow structure in the middle of the core.

[0043] (3) Cooling and solidifying to form a column with three column sections; the column is bonded to the core and tightly connected internally. The column can also play a supporting role, maintaining a good winding force when the core is wound, so that the positive and negative pole pieces maintain good interface contact and dynamics, thereby improving the long cycle performance of the battery. The present invention uses a two-injection process to inject the polymer hot melt liquid into the hollow structure in the middle of the core, making the preparation process simpler and faster.

[0044] Example 1

[0045] This embodiment provides a battery having a structure as follows: Figure 1As shown, it includes a cylindrical shell 2, a winding core arranged in the shell, and the winding core includes a positive electrode sheet, a separator and a negative electrode sheet stacked and wound in sequence; a column 1 is arranged at the center of the winding core, and the column 1 is a cylinder, and the length ratio of the column 1 to the winding core is 95:100. The column 1 includes a first column segment 11, a second column segment 12 and a third column segment 13 with a length ratio of 1:1:1, and the second column segment 12 is arranged between the first column segment 11 and the third column segment 13. The bonding strength between the inside of the winding core and the column is 29N / cm.

[0046] Taking the total mass percentage of all flame retardants as 100%, the content of flame retardant in the first column section is 40.9%; the content of flame retardant in the second column section is 18.2%; and the content of flame retardant in the third column section is 40.9%.

[0047] The first column section includes EVA and polyphosphazene in a mass ratio of 6:4, and the particle size of the polyphosphazene particles is Dv10 of 9μm, Dv50 of 45μm, and Dv99 of 80μm; the second column section includes EVA and polyphosphazene in a mass ratio of 8:2, and the particle size of the polyphosphazene particles is Dv10 of 9μm, Dv50 of 45μm, and Dv99 of 80μm; the third column section includes EVA and polyphosphazene in a mass ratio of 6:4, and the particle size of the polyphosphazene particles is Dv10 of 9μm, Dv50 of 45μm, and Dv99 of 80μm.

[0048] The preparation method of the above battery comprises:

[0049] 1) The preparation method of the positive electrode sheet includes: dispersing the positive electrode active material (molecular formula: LiFePO4) and the conductive agent carbon nanotubes and the binder PVDF in a solvent NMP according to a mass ratio of 96:2:2 and mixing them evenly to obtain a positive electrode slurry. The positive electrode slurry is evenly coated on the positive electrode current collector aluminum foil, and the positive electrode sheet is obtained after baking, cold pressing and cutting.

[0050] 2) The preparation method of the negative electrode sheet includes: dispersing artificial graphite, conductive carbon black SP and binder SBR in a mass ratio of 94:3:3 in solvent deionized water and mixing them evenly to obtain a negative electrode slurry. The negative electrode slurry is evenly coated on the negative electrode current collector copper foil, and the negative electrode sheet is obtained after baking, cold pressing and cutting.

[0051] 3) The preparation method of the electrolyte includes: mixing ethylene carbonate (EC), diethyl carbonate (DEC) and dimethyl carbonate (DMC) in a mass ratio of 1:1:1 to obtain an organic solvent. Dissolving LiPF6 in the organic solvent and mixing to obtain an electrolyte. Based on the mass of the electrolyte, the mass percentage content of LiPF6 is 13%.

[0052] 4) The positive electrode sheet, PP / PE / PP composite isolation film and negative electrode sheet are stacked and wound in order to obtain a winding core. Then, 60 parts of EVA and 40 parts of polyphosphazene are weighed by weight, and polyphosphazene is added after heating the EVA to melt, and mixed evenly to obtain a polymer hot melt liquid, which is used as the raw material of the first column segment. The raw material of the third column segment is the same as that of the first column segment. 80 parts of EVA and 20 parts of polyphosphazene are weighed by weight, and polyphosphazene is added after heating the EVA to melt, and mixed evenly to obtain a polymer hot melt liquid, which is used as the raw material of the second column segment. First, the polymer hot melt liquid corresponding to the second column segment is injected into the middle position of the hollow structure in the middle of the winding core, and then the polymer hot melt liquids corresponding to the first column segment and the third column segment are simultaneously injected at both ends of the hollow structure in the middle of the winding core. After cooling and solidification, a columnar body having a first column segment, a second column segment and a third column segment is formed, and the columnar body is bonded to the winding core. The coil core is placed in a cylindrical aluminum shell for welding and baking, and the shell is sealed after adding the above-mentioned electrolyte to complete the preparation of the battery.

[0053] Example 2

[0054] This embodiment provides a battery, which differs from Embodiment 1 in that: in this embodiment, the length ratio of the first column segment, the second column segment and the third column segment is 1.5:1:1.5, the content of the flame retardant in the first column segment is 43wt%, the content of the flame retardant in the second column segment is 14wt%, and the content of the flame retardant in the third column segment is 43wt%.

[0055] Example 3

[0056] This embodiment provides a battery, which differs from Embodiment 1 in that: in this embodiment, the length ratio of the first column segment, the second column segment and the third column segment is 2:1:2, the content of the flame retardant in the first column segment is 44.4wt%, the content of the flame retardant in the second column segment is 11.2wt%, and the content of the flame retardant in the third column segment is 44.4wt%.

[0057] Example 4

[0058] This embodiment provides a battery, which is different from Embodiment 1 in that: in this embodiment, the length ratio of the first column segment, the second column segment and the third column segment is 1.5:1:2, the content of the flame retardant in the first column segment is 37.5wt%, the content of the flame retardant in the second column segment is 12.5wt%, and the content of the flame retardant in the third column segment is 50wt%.

[0059] Example 5

[0060] This embodiment provides a battery, which is different from Embodiment 1 in that: in this embodiment, the length ratio of the first column segment, the second column segment and the third column segment is 2:1:1.5, the content of the flame retardant in the first column segment is 50wt%, the content of the flame retardant in the second column segment is 12.5wt%, and the content of the flame retardant in the third column segment is 37.5wt%.

[0061] Example 6

[0062] This embodiment provides a battery, which is different from Embodiment 1 in that the length ratio of the column to the winding core in this embodiment is 91:100.

[0063] Example 7

[0064] This embodiment provides a battery, which is different from Embodiment 1 in that the length ratio of the column to the winding core in this embodiment is 98:100.

[0065] Example 8

[0066] This embodiment provides a battery, which is different from the embodiment 1 in that: the first column section includes EVA and polyphosphazene in a mass ratio of 53:47, the second column section includes EVA and polyphosphazene in a mass ratio of 94:6, and the third column section includes EVA and polyphosphazene in a mass ratio of 53:47. The content of the flame retardant in the first column section is 47wt%, the content of the flame retardant in the second column section is 6wt%, and the content of the flame retardant in the third column section is 47wt%.

[0067] Example 9

[0068] This embodiment provides a battery, which is different from the embodiment 1 in that: the first column section includes EVA and polyphosphazene in a mass ratio of 56:44, the second column section includes EVA and polyphosphazene in a mass ratio of 88:12, and the third column section includes EVA and polyphosphazene in a mass ratio of 56:44. The content of the flame retardant in the first column section is 44wt%, the content of the flame retardant in the second column section is 12wt%, and the content of the flame retardant in the third column section is 44wt%.

[0069] Example 10

[0070] This embodiment provides a battery, which is different from the embodiment 1 in that: the first column section includes EVA and polyphosphazene in a mass ratio of 53:47, the second column section includes EVA and polyphosphazene in a mass ratio of 90:10, and the third column section includes EVA and polyphosphazene in a mass ratio of 53:47. The content of the flame retardant in the first column section is 47wt%, the content of the flame retardant in the second column section is 10wt%, and the content of the flame retardant in the third column section is 43wt%.

[0071] Embodiment 11

[0072] This embodiment provides a battery, which is different from the embodiment 1 in that: the first column section includes EVA and polyphosphazene in a mass ratio of 58:42, the second column section includes EVA and polyphosphazene in a mass ratio of 87:13, and the third column section includes EVA and polyphosphazene in a mass ratio of 55:45. The content of the flame retardant in the first column section is 42wt%, the content of the flame retardant in the second column section is 13wt%, and the content of the flame retardant in the third column section is 45wt%.

[0073] Example 12

[0074] This embodiment provides a battery, which is different from the embodiment 1 in that the polymer hot-melt material in the first column section of this embodiment is PCL, which replaces EVA with the same mass. The bonding strength between the inside of the winding core and the columnar body is 23N / cm.

[0075] Embodiment 13

[0076] This embodiment provides a battery, which is different from the embodiment 12 in that the polymer hot-melt material in the third column section of this embodiment is PCL, which replaces EVA with equal mass. The bonding strength between the inside of the winding core and the columnar body is 12N / cm.

[0077] Embodiment 14

[0078] This embodiment provides a battery, which is different from the embodiment 1 in that the polymer hot melt material in the second column section of this embodiment is PEO, which replaces EVA with equal mass. The bonding strength between the inside of the winding core and the columnar body is 24N / cm.

[0079] Embodiment 15

[0080] This embodiment provides a battery, which is different from the embodiment 1 in that: the polymer hot-melt material in the first column section of this embodiment is PCL, which replaces EVA by the same mass; the polymer hot-melt material in the second column section is PEO, which replaces EVA by the same mass. The bonding strength between the inside of the winding core and the columnar body is 18N / cm.

[0081] Example 16

[0082] This embodiment provides a battery, which is different from Embodiment 1 in that the flame retardant in the first column section of this embodiment is calcium phosphate, which replaces polyphosphazene in equal mass.

[0083] Embodiment 17

[0084] This embodiment provides a battery, which differs from Embodiment 16 in that the flame retardant in the third column segment is calcium phosphate, which replaces polyphosphazene with an equal mass.

[0085] Embodiment 18

[0086] This embodiment provides a battery, which is different from Embodiment 1 in that the flame retardant in the second column section of this embodiment is zinc phosphate, which replaces polyphosphazene in equal mass.

[0087] Embodiment 19

[0088] This embodiment provides a battery, which is different from Embodiment 1 in that: the flame retardant in the first column section of this embodiment is calcium phosphate, which replaces polyphosphazene by equal mass; the flame retardant in the second column section of this embodiment is zinc phosphate, which replaces polyphosphazene by equal mass; the flame retardant in the third column section is ammonium polyphosphate, which replaces polyphosphazene by equal mass.

[0089] Embodiment 20

[0090] This embodiment provides a battery, which is different from Embodiment 1 in that the particle size Dv10 of the polyphosphazene particles in this embodiment is 5 μm, Dv50 is 10 μm, and Dv99 is 55 μm.

[0091] Embodiment 21

[0092] This embodiment provides a battery, which is different from Embodiment 1 in that the particle size Dv10 of the polyphosphazene particles in this embodiment is 7 μm, Dv50 is 30 μm, and Dv99 is 70 μm.

[0093] Embodiment 22

[0094] This embodiment provides a battery, which is different from Embodiment 1 in that the particle size Dv10 of the polyphosphazene particles in this embodiment is 10 μm, Dv50 is 50 μm, and Dv99 is 50 μm.

[0095] The parameters in each embodiment are shown in Table 1-2.

[0096] Table 1 Parameters of each embodiment

[0097]

[0098]

[0099] Table 2 Parameters of each embodiment

[0100]

[0101] Comparative Example 1

[0102] This comparative example provides a battery, which is different from Example 1 in that it does not contain a columnar body.

[0103] Comparative Example 2

[0104] This comparative example provides a battery, which is different from Example 1 in that the second column segment is the same as the first column segment, and the content of the flame retardant in the columnar body of this comparative example is uniform from the center to both ends.

[0105] Test Case

[0106] This test example provides performance tests of batteries in various embodiments and comparative examples, as follows:

[0107] The test method for flame retardancy is as follows: the fully charged battery is heated from 25°C to 180°C at a rate of 5°C / min, maintained for 30 minutes, and the battery status is recorded. Good means that the battery does not catch fire and the explosion-proof valve does not open; average means that the battery does not catch fire but the explosion-proof valve opens; poor means that the battery catches fire.

[0108] Needle puncture test method: Use a steel needle with a diameter of 3mm to pierce the center of the large surface of the fully charged battery at a 45° angle and a speed of 25mm / s, and observe for 1 hour. If the battery does not catch fire or explode, it passes the needle puncture test. If the battery catches fire or explodes, it fails the needle puncture test.

[0109] Mass energy density: At 25°C, charge and discharge the battery for one cycle (2.0-3.65V) at a current rate of 0.33C, record the discharge energy, and divide the discharge energy by the battery mass to get the mass energy density of the battery.

[0110] Capacity retention rate after 500 cycles: At 25°C, charge and discharge the battery cyclically at a current rate of 1C (2.0-3.65V), record the discharge capacity of the 1st and 500th cycles, and calculate the ratio of the 500th discharge capacity to the 1st discharge capacity, which is the capacity retention rate after 500 cycles.

[0111] Table 3 Performance test results of various embodiments and comparative examples

[0112]

[0113]

[0114] According to the above data, a column containing a flame retardant is arranged in the center of the battery core, and the flame retardant content in the center of the column is lower than that at both ends. This can balance the internal temperature of the core and is beneficial to achieving a flame retardant effect on the battery. At the same time, the presence of the column can enhance the winding force of the core, which is beneficial to stabilize the core structure, improve the battery cycle performance, and enable the battery to maintain a high energy density.

[0115] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention.

Claims

1. A battery, characterized in that: The battery comprises a shell, a winding core arranged in the shell, a columnar body is arranged at the center of the winding core, the columnar body contains a flame retardant, and along the length direction of the columnar body, the columnar body has a first column segment, a third column segment, and a second column segment arranged between the first column segment and the third column segment, and the first column segment, the second column segment, and the third column segment contain the flame retardant; The content of the flame retardant in the second column section is less than the content of the flame retardant in the first column section and the third column section.

2. The battery according to claim 1, characterized in that The ratio of the lengths of the first column segment, the second column segment and the third column segment is (1-2):1:(1-2).

3. The battery according to claim 1, characterized in that Taking the total mass of the flame retardant in the column as 100%, the content of the flame retardant in the first column section is 35-50wt%; the content of the flame retardant in the second column section is 5-20wt%; and the content of the flame retardant in the third column section is 35-50wt%.

4. The battery according to claim 1, characterized in that The particle size Dv10 of the flame retardant particles is 5-10 μm, Dv50 is 10-50 μm, and Dv99 is 50-90 μm; and / or, The flame retardant includes at least one of polyphosphazene, ammonium polyphosphate, phosphate, red phosphorus and organic phosphorus.

5. The battery according to claim 1, characterized in that The ratio of the length of the column to the length of the winding core is (91-98):

100.

6. The battery according to claim 1, characterized in that The columnar body further comprises a high molecular hot-melt material, and the first column segment, the second column segment and the third column segment contain the high molecular hot-melt material.

7. The battery according to claim 1, characterized in that The polymer hot-melt material includes at least one of EVA (ethylene-vinyl acetate copolymer), POE (ethylene-butylene polymer), PEO (polyethylene oxide) and PCL (polycaprolactone).

8. The battery according to claim 7, characterized in that The shell is cylindrical; and / or the columnar body is a cylinder.

9. The battery according to any one of claims 1 to 8, characterized in that: The bonding strength between the interior of the winding core and the columnar body is 12-30 N / cm.

10. An electrical device comprising the battery according to any one of claims 1 to 9.

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