High-safety lithium ion battery and manufacturing method thereof

Abstract

The invention discloses a high-safety lithium ion battery which comprises a battery cell, a cathode composite copper pole piece and / or an anode composite aluminum pole piece are / is arranged in the battery cell besides a cathode piece and an anode piece which are arranged in a crossed and laminated manner, and any two adjacent types of the cathode piece, the anode piece, the anode composite copper pole piece and the anode composite aluminum pole piece are separated by a diaphragm. According to the high-safety lithium ion battery disclosed by the invention, the battery structure is improved, so that heat generated in the battery is reduced, the heat transfer rate in the battery is improved, and the heat in the battery is timely guided out, thereby reducing the probability of thermal runaway.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion battery manufacturing, and in particular to a high-safety lithium ion battery and a manufacturing method thereof. Background Art

[0002] Compared with other batteries, lithium-ion batteries have the characteristics of high energy density, high platform voltage, and long cycle life. With the improvement of the energy density of lithium-ion batteries, there are great hidden dangers in the safety performance of batteries. The phenomenon of battery charging, fire and explosion is also common. In particular, the higher the battery capacity and the larger the battery size, the greater the safety hazard. The most likely reason is that the battery is in use. In addition, it is very easy to cause the battery cell to short-circuit and generate heat in the case of heavy impact or needle puncture. The internal heat cannot be transferred and released in a timely and effective manner, which eventually leads to thermal runaway of the battery, causing fire and explosion. Summary of the invention

[0003] In view of the problems in the prior art, the present invention discloses a high-safety lithium-ion battery, which reduces the heat generation inside the battery and increases the heat transfer rate inside the battery by improving the battery structure, and timely conducts the heat inside the battery, thereby reducing the probability of thermal runaway.

[0004] The present invention is achieved through the following technical solutions:

[0005] A high-safety lithium-ion battery comprises a battery cell. In addition to cross-stacked positive and negative electrode sheets, the battery cell also comprises a negative composite copper electrode sheet and / or a positive composite aluminum electrode sheet. A diaphragm separates any two adjacent ones of the positive electrode sheet, the negative electrode sheet, the negative composite copper electrode sheet, and the positive composite aluminum electrode sheet.

[0006] There are two types of heat conduction in the battery: transverse conduction and longitudinal conduction. Transverse conduction is the electrode itself, and longitudinal conduction is the conduction between different layers of electrodes. In addition, the conduction of heat is related to thermal conductivity. The thermal conductivity of metal is greater than the thermal conductivity of the electrode. The present invention transfers the heat of the battery cell to the metal layer (i.e., aluminum layer and copper layer) on the composite metal electrode (i.e., negative composite copper electrode and positive composite aluminum electrode) through longitudinal conduction, so that the heat is conducted from the metal layer on the composite metal electrode to the positive electrode, negative electrode, negative composite copper electrode, and positive composite aluminum electrode through transverse conduction, and finally conducted through the electrode. Heavy impact and needle puncture can easily cause short circuit of the battery cell, and the main reason for heat generation is also short circuit heat generation. When the impedance is infinitely large or infinitely small, the battery generates little heat. The addition of composite metal electrode will increase the occurrence of these two possibilities (the metal-to-metal contact impedance of the composite metal electrode is extremely low, and the insulation layer of the composite metal electrode is in contact with other parts, and the impedance is extremely large), thereby reducing the heat generation of the battery.

[0007] As a further solution, the negative electrode composite copper pole piece and the positive electrode composite aluminum pole piece are located in the outermost layer and / or in the middle layer.

[0008] As a further solution, the negative composite copper pole piece and the positive composite aluminum pole piece are located in the outermost layer. The outermost layer is more likely to be in direct contact during the deformation of the battery cell, resulting in a short circuit and reducing the heat of the entire battery. Although the middle layer can also be in direct contact, its range cannot cover the entire battery cell, and the ability to prevent heat explosion is weaker than that of the outermost layer.

[0009] As a further solution, the area of ​​the negative electrode composite copper plate is 70%-100% of the area of ​​the positive electrode plate. This arrangement has the greatest effect on improving the safety performance of the battery.

[0010] As a further solution, the positive electrode plate includes a first aluminum tab region and a positive electrode material region. The first aluminum tab region is more conducive to heat dissipation and current conduction.

[0011] As a further solution, the positive composite aluminum pole piece includes a positive carrier insulating layer and aluminum layers arranged on both sides of the carrier insulating layer. The positive carrier insulating layer has a low density and a light weight. The addition of a composite metal pole piece can further improve the energy density of the battery relative to the metal pole piece. There are aluminum layers on both sides of the positive carrier insulating layer, which is conducive to receiving heat from both sides.

[0012] As a further solution, the material of the positive electrode carrier insulating layer is one of PP, PE, PET, PI or a mixture of two or more thereof. The positive electrode carrier insulating layer is an organic material, which is more flexible than pure aluminum foil and can achieve a thickness of less than 5 μm. Pure aluminum foil is difficult to process into a sheet with a thickness of less than 10 μm.

[0013] As a further solution, the thickness of the positive electrode carrier insulating layer is 2μm-4μm. To ensure the material strength, the positive electrode carrier insulating layer is designed to be within this thickness range; the thickness of the aluminum layer is 1μm-2μm. In this thickness range, good heat transfer can be achieved and it is convenient to prepare by coating to reduce the cost as much as possible. The overall thickness is controlled below 10μm. Too large thickness will affect the battery energy density.

[0014] As a further solution, the positive composite aluminum pole piece includes a second aluminum pole ear area and an aluminum body area. The size, position and material of the second aluminum pole ear area are the same as those of the first aluminum pole ear area to ensure that the positive composite aluminum pole piece and the positive pole piece can be welded together when the pole pieces are welded. The length of the aluminum body area is less than, equal to or greater than the length of the positive electrode material area, and the width of the aluminum body area is less than, equal to or greater than the width of the positive electrode material area.

[0015] As a further solution, the area of ​​the positive electrode composite aluminum plate is 80%-100% of the area of ​​the positive electrode plate. This arrangement has the greatest effect on improving the safety performance of the battery.

[0016] As a further solution, the negative electrode plate includes a first copper tab region and a negative electrode material region. The first copper tab region is more conducive to heat dissipation and current conduction.

[0017] As a further solution, the negative electrode composite copper pole piece includes a negative electrode carrier insulation layer and copper layers arranged on both sides of the carrier insulation layer. The negative electrode carrier insulation layer has a low density and a light weight. The addition of a composite metal pole piece can further improve the energy density of the battery relative to the metal pole piece. There are copper layers on both sides of the carrier insulation layer, which is conducive to receiving heat from both sides.

[0018] As a further solution, the negative electrode carrier insulating layer is made of any one of PP, PE, PET and PI. The negative electrode carrier insulating layer is an organic material, which is more flexible than pure copper foil and can achieve a thickness of less than 5 μm. Pure copper foil is difficult to process into a sheet with a thickness of less than 5 μm.

[0019] As a further solution, the thickness of the negative electrode carrier insulating layer is 2μm-4μm. To ensure the material strength, the positive electrode carrier insulating layer is designed to be within this thickness range. The thickness of the copper layer is 1μm-2μm. In this thickness range, good heat transfer can be achieved and it is convenient to prepare by coating to reduce the cost as much as possible. The overall thickness is controlled below 10μm. Too large thickness will affect the battery energy density.

[0020] As a further solution, the negative electrode composite copper pole sheet includes a second copper pole lug area and a copper body area. The second copper pole lug area is the same as the first copper pole lug area in size, position and material to ensure that the negative electrode composite copper pole sheet and the negative electrode pole sheet can be welded together when the pole sheets are welded. The length of the copper body area is less than, equal to or greater than the length of the negative electrode material area, and the width of the copper body area is less than, equal to or greater than the width of the negative electrode material area.

[0021] As a further solution, the diaphragm is selected from any one of a PP diaphragm, a PE diaphragm, and a PI diaphragm.

[0022] As a further solution, the number of the positive electrode plates is one less than the number of the negative electrode plates.

[0023] As a further solution, the number of the positive electrode composite aluminum pole pieces and the number of the negative electrode composite copper pole pieces are both at least one.

[0024] As a further solution, the number of the positive composite aluminum pole pieces does not exceed 20% of the number of the positive pole pieces, and the number of the negative composite copper pole pieces does not exceed 20% of the number of the negative pole pieces. The number of the positive composite aluminum pole pieces and the negative composite copper pole pieces cannot be too large, as too much will cause a large decrease in battery capacity.

[0025] As a further solution, it also includes an electrolyte and a shell, wherein the electrolyte and the shell are made of any existing technology.

[0026] The second aspect of the present invention is to provide a method for manufacturing the high-safety lithium-ion battery, the method comprising:

[0027] S1: Make battery cells;

[0028] S2: placing the battery cell in the shell, vacuum baking, and injecting electrolyte;

[0029] S3: Charge and activate, then seal to make a battery.

[0030] The third aspect of the present invention is to provide an electrochemical device having the high-safety lithium-ion battery.

[0031] As a further embodiment, the battery is a lithium battery, a sodium battery, a potassium battery, a zinc battery or a magnesium battery.

[0032] As a further solution, the electrochemical device can be used in terminal consumer products, and the terminal consumer products applied for include but are not limited to mobile phones, laptops, pen-type computers, mobile computers, e-book players, portable phones, portable fax machines, portable copiers, and portable printers.

[0033] As a further solution, the electrochemical device can be used for electrical equipment, which includes large electrical equipment and small electrical equipment, wherein small electrical equipment includes terminal consumer products, wearable electronic devices or movable electronic devices; large electrical equipment includes transportation electrical equipment. Transportation electrical equipment includes but is not limited to automobiles, motorcycles, power-assisted bicycles, buses, subways, high-speed railways, airplanes, and ships; wearable electronic devices or movable electronic devices include but are not limited to head-mounted stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, drones, motors, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, and lithium-ion capacitors.

[0034] The characteristics and beneficial effects of the present invention are:

[0035] (1) The present invention improves the battery structure by adding a positive composite aluminum electrode sheet and a negative composite copper electrode sheet. On the one hand, it improves the heat transfer rate inside the battery, transfers the heat of the battery cell to the composite metal electrode sheet through longitudinal conduction, and conducts the heat from the composite metal electrode sheet to the battery through lateral conduction. The heat inside the battery is promptly discharged, thereby reducing the probability of thermal runaway. On the other hand, the use of a positive composite aluminum electrode sheet and a negative composite copper electrode sheet increases the possibility of two possibilities, namely, infinite impedance and infinitesimal impedance, and reduces the heat generation inside the battery, thereby further reducing the probability of thermal runaway.

[0036] (2) The method for preparing a high-safety lithium-ion battery in the present invention is simple, efficient, low-cost, and conducive to large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 This is a picture of a battery cell of a high-safety lithium-ion battery described in the present invention.

[0039] Figure 2 This is a diagram of a positive electrode sheet of a high-safety lithium-ion battery described in the present invention.

[0040] Figure 3 This is a diagram of a positive composite aluminum electrode piece for a high-safety lithium-ion battery described in the present invention.

[0041] Figure 4 This is a diagram of a negative electrode sheet of a high-safety lithium-ion battery described in the present invention.

[0042] Figure 5 This is a diagram of a negative electrode composite copper electrode piece of a high-safety lithium-ion battery described in the present invention.

[0043] Reference numerals:

[0044] S, diaphragm; A, positive electrode composite aluminum electrode piece; B, negative electrode composite copper electrode piece; N, negative electrode piece; M, positive electrode piece; 1-1, first aluminum electrode tab area; 1-2, positive electrode material area; A-1, second aluminum electrode tab area; A-2, aluminum body area; 2-1, first copper electrode tab area; 2-2, negative electrode material area; B-1, second copper electrode tab area; B-2, copper body area. DETAILED DESCRIPTION

[0045] In order to facilitate the understanding of the present invention, the present invention will be described in more detail below, and embodiments of the present invention are given, but the scope of the present invention is not limited thereby.

[0046] like Figure 1-Figure 5 As shown, a high-safety lithium-ion battery described in the present invention is composed of a battery cell, an electrolyte, and a shell, wherein the battery cell is composed of a diaphragm S, a positive electrode plate M, a negative electrode plate N, a negative composite copper electrode plate B, and a positive composite aluminum electrode plate A.

[0047] In some embodiments, the positive electrode sheet M includes: one or more of lithium cobalt oxide, lithium manganese oxide, ternary, lithium iron phosphate, lithium-rich manganese, one or more of CNTs, SP, GF-2, graphene, PVDF, aluminum foil. Figure 2 As shown, all positive electrode plates M can be divided into two parts, namely the first aluminum pole lug area 1-1 and the positive electrode material area 1-2. The first aluminum pole lug area 1-1 is required for pole plate welding, and the positive electrode material area 1-2 is the main body of the battery capacity; wherein the first aluminum pole lug area 1-1 and the positive electrode material area 1-2 corners are all smooth transition areas without special burrs and sharp corners.

[0048] In some embodiments, the positive electrode composite aluminum electrode sheet A has a positive electrode carrier insulating layer in the middle and aluminum layers on both sides in cross section, wherein the thickness of the aluminum layer is 1 μm to 2 μm, the thickness of the positive electrode carrier insulating layer is 2 μm to 4 μm, and the positive electrode carrier insulating layer can be made of insulating materials such as PP, PE, PET and PI; Figure 3 As shown, the positive electrode composite aluminum pole piece A can be divided into two parts, namely the second aluminum pole lug area A-1 and the aluminum main body area A-2; the size, size and position of the second aluminum pole lug area A-1 should be the same as those of the positive electrode pole piece M to ensure that the positive electrode composite aluminum pole piece A and the positive electrode pole piece M can be welded together when the pole pieces are welded, and the material used for the second aluminum pole lug area A-1 should be the same as that of the positive electrode material area 1-2, and the length or width of the aluminum main body area A-2 can be less than the length or width of the positive electrode material area 1-2, or it can be greater than or equal to the length or width of the positive electrode material area 1-2.

[0049] In some embodiments, the negative electrode plate N includes one or more of graphite, hard carbon, SiO, one or more of CNtS, SP, GF-2, graphene, one or more of SBR, PAA, CMC, copper foil, and nickel tabs. Figure 4 As shown, the negative electrode plate N can be divided into two parts, namely the first copper pole ear area 2-1 and the negative electrode material area 2-2. The first copper pole ear area 2-1 is required for pole plate welding, and the negative electrode material area 2-2 is the main body of the battery capacity; wherein the first copper pole ear area 2-1 and the negative electrode material area 2-2 have smooth transition areas at the corners without special burrs and sharp corners.

[0050] In some embodiments, the negative electrode composite copper electrode sheet B has a negative electrode carrier insulating layer in the middle and copper layers on both sides in cross section, the copper layer has a thickness of 1 μm to 2 μm, the thickness of the negative electrode carrier insulating layer is 2 μm to 4 μm, and the negative electrode carrier insulating layer can be made of insulating materials such as PP, PE, PET and PI; Figure 4 As shown, the negative composite copper pole piece B can be divided into two parts, namely the second copper pole lug area B-1 and the copper body area B-2; the size, size and position of the second copper pole lug area B-1 must be the same as those of the first copper pole lug area 2-1 to ensure that the negative composite copper pole piece B and the negative pole piece N can be welded together when the pole pieces are welded, and the material used for the second copper pole lug area B-1 must be the same as that of the first copper pole lug area 2-1, and the length or width of the first copper pole lug area 2-1 can be less than the length or width of the negative electrode material area 2-2, or it can be greater than or equal to the length or width of the negative electrode material area 2-2.

[0051] In some embodiments, the separator S includes a PP separator S, a PE separator S, a PI separator S or a derivative thereof, such as a PP separator S plus ceramics, etc. Figure 1 As shown, the positive and negative electrode sheets are separated by a separator S and then wound to form a battery cell.

[0052] In some embodiments, the number of the positive electrode composite aluminum pole piece A and the negative electrode composite copper pole piece B is not limited.

[0053] The experimental parameters of Comparative Example 1 and Example 1 to Example 37 are designed as follows:

[0054] The battery cell model is 6060100; the battery height is 100mm, the width is 60mm, and the thickness is 6mm.

[0055] like Figure 1 As shown, there are n negative electrode plates (n=22), all of which have the same size and weight; there are n-1 positive electrode plates, all of which have the same size and weight.

[0056] The raw material composition and mass ratio of the positive electrode plate are: LCO: PVDF: Super P = 96:2:2;

[0057] The raw material composition and mass ratio of the negative electrode plate are: graphite: SBR: CMC: superP = 96.5:1.7:1.3:1.

[0058] The thickness of the positive electrode carrier insulating layer is 2 μm, and the thickness of the aluminum layer is 2 μm; the thickness of the negative electrode carrier insulating layer is 2 μm, and the thickness of the copper layer is 2 μm.

[0059] The position of the positive composite aluminum electrode is defined by the position of the two adjacent positive electrode plates. For example, if it is above m-1, it is defined as position 0; if it is between m-1 and m-2, it is defined as position 1; if it is below m-(n-1), it is defined as position n-1;

[0060] The position of the negative composite copper electrode is defined by the position of the two adjacent positive electrode pieces. For example, if it is above n-1, it is defined as position 0; if it is between n-1 and n-2, it is defined as position 1; if it is below mn, it is defined as position n;

[0061] Placing the positive composite aluminum electrode at position 0 and position n-1 can be considered to have the same effect;

[0062] Placing the negative copper electrode at position 0 and position n-1 can be considered to have the same effect;

[0063] Assume that the area of ​​the positive electrode material region of the positive electrode sheet is S1, the area of ​​the negative electrode material region of the negative electrode sheet is S2; the area of ​​the aluminum body region of the positive composite aluminum electrode sheet is S3; the area of ​​the copper body region of the negative composite copper electrode sheet is S4; the ratio of S3 to S1 is T1; the ratio of S4 to S2 is T2.

[0064] To make a battery cell, place the battery cell in a shell, vacuum bake it at 85°C for 24 hours, inject electrolyte (the electrolyte composition is DMC:EMC:EC:VC:FEC:LiPF6=30:25:35:1:3:6), activate it by charging (0.5C CC to4.0V), and then seal it to make the corresponding battery.

[0065] Table 1 Parameters of the embodiments of the present invention and the comparative examples

[0066]

[0067] Comparative Example 1, Experimental Performance Verification of Example 1-Example 37:

[0068] (1) Basic electrical properties

[0069] Capacity performance test: 1) 0.5C CC to 4.2V, CV to 0.05C; 2) 0.5C DC to 3.0V.

[0070] Internal resistance performance test: 1) Current I1 = 0.1C DC to 3S record cut-off voltage U1; 2) Current I2 = 1C DC to1S record start voltage U2; 3) Calculate using the following formula: internal resistance = (U1-U2) / (I2-I1).

[0071] Self-discharge performance test: 1) Test voltage U1 (mV); 2) After N hours at 25°C, test voltage U2 (mV); 3) Calculate using the following formula: Self-discharge = (U1-U2) / N.

[0072] Table 1 Basic electrical properties of the embodiments of the present invention and the comparative examples

[0073]

[0074]

[0075] It can be seen from Table 2 that the capacity of the battery decreases with the increase of the total thickness of the positive composite aluminum pole sheet and the negative composite copper pole sheet, and the internal resistance and self-discharge are comparable to those of Comparative Example 1. The use of positive composite aluminum pole sheets or negative composite copper pole sheets can improve the safety performance of the battery, but it will sacrifice the capacity of the battery. Therefore, the number of positive composite aluminum pole sheets or negative composite copper pole sheets should not be too large.

[0076] (2) Safety performance comparison experiment

[0077] Heavy object impact: Drop a 10Kg heavy hammer freely from a height of 1m to impact the battery cell fixed in the fixture (the largest surface of the battery cell should be perpendicular to the table surface).

[0078] Short circuit test: Connect the positive and negative electrodes of the battery cell with a wire with a resistance value less than 50mΩ, and end when the temperature drops to about 10℃ lower than the peak value.

[0079] Needle penetration test: Place the battery cell horizontally and use a steel nail with a diameter of about 3mm to penetrate the battery cell at a speed of 1m / min in the direction perpendicular to the battery cell surface at the center of the largest surface of the battery cell.

[0080]

[0081]

[0082]

[0083] It can be concluded from Table 3 that, by comparing Examples 1-3 with Examples 4-6, the pass rate of using the negative electrode composite copper pole piece alone is higher than that of using the positive electrode aluminum pole piece alone.

[0084] Comparing Examples 1-2 with Examples 5-6, when composite copper foil or composite aluminum foil pole pieces are used, the thickness of the pole pieces is irrelevant.

[0085] Compared with Examples 1-22, the more negative electrode composite copper pole pieces or positive electrode composite aluminum pole pieces there are, the better the safety performance is.

[0086] Comparing Examples 8-11 with Examples 12-13, and Examples 20-25 with Examples 26-28, the safety performance is better when the negative electrode composite copper pole piece and the positive electrode composite aluminum pole piece are used simultaneously than when they are used alone.

[0087] Comparing Example 7 with Example 8, and Example 9 with Example 10, the effect of placing the negative composite copper pole piece and the positive composite aluminum pole piece on the outer layers on both sides of the battery cell is better than placing them in the middle layer.

[0088] Compared with Examples 28-32, the surface area of ​​the positive composite aluminum electrode has an impact on the safety performance of the battery. The larger the surface area, the higher the pass rate.

[0089] Compared with Examples 32-37, the surface area of ​​the negative electrode composite copper electrode sheet has an impact on the safety performance of the battery. The larger the surface area, the higher the pass rate.

[0090] It should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-safety lithium-ion battery, characterized in that: The invention comprises a battery cell, in which, in addition to the cross-stacked positive electrode sheets and negative electrode sheets, a negative electrode composite copper electrode sheet and / or a positive electrode composite aluminum electrode sheet is also provided, and a diaphragm separates any two adjacent ones of the positive electrode sheets, the negative electrode sheets, the negative electrode composite copper electrode sheet and the positive electrode composite aluminum electrode sheet.

2. A high-safety lithium-ion battery according to claim 1, characterized in that: The negative electrode composite copper pole piece and the positive electrode composite aluminum pole piece are located in the outermost layer and / or in the middle layer; Further preferably, the negative electrode composite copper pole piece and the positive electrode composite aluminum pole piece are located in the outermost layer.

3. A high-safety lithium-ion battery according to claim 2, characterized in that: The area of ​​the negative electrode composite copper electrode sheet is 70%-100% of the area of ​​the positive electrode sheet; The positive electrode plate includes a first aluminum tab region and a positive electrode material region; The positive composite aluminum electrode sheet comprises a positive carrier insulating layer and aluminum layers arranged on both sides of the carrier insulating layer; The material of the positive electrode carrier insulating layer is any one of PP, PE, PET and PI.

4. A high-safety lithium-ion battery according to claim 3, characterized in that: The thickness of the positive electrode carrier insulating layer is 2 μm-4 μm, and the thickness of the aluminum layer is 1 μm-2 μm; The positive composite aluminum pole piece includes a second aluminum pole ear area and an aluminum body area. The size, position and material of the second aluminum pole ear area are the same as those of the first aluminum pole ear area. The length of the aluminum body area is less than, equal to or greater than the length of the positive electrode material area, and the width of the aluminum body area is less than, equal to or greater than the width of the positive electrode material area.

5. A high-safety lithium-ion battery according to claim 1, characterized in that: The area of ​​the positive composite aluminum electrode sheet is 80%-100% of the area of ​​the positive electrode sheet; The negative electrode plate comprises a first copper tab region and a negative electrode material region; The negative electrode composite copper electrode sheet comprises a negative electrode carrier insulating layer and copper layers arranged on both sides of the carrier insulating layer; The material of the negative electrode carrier insulating layer is any one of PP, PE, PET and PI.

6. A high-safety lithium-ion battery according to claim 5, characterized in that: The thickness of the negative electrode carrier insulating layer is 2 μm-4 μm, and the thickness of the copper layer is 1 μm-2 μm; The negative electrode composite copper pole piece includes a second copper pole lug area and a copper body area. The second copper pole lug area is the same as the first copper pole lug area in size, position and material. The length of the copper body area is less than, equal to or greater than the length of the negative electrode material area, and the width of the copper body area is less than, equal to or greater than the width of the negative electrode material area.

7. A high-safety lithium-ion battery according to claim 1, characterized in that: The diaphragm is selected from any one of a PP diaphragm, a PE diaphragm and a PI diaphragm.

8. A high-safety lithium-ion battery according to claim 1, characterized in that: The number of the positive electrode sheets is one less than the number of the negative electrode sheets; The number of the positive electrode composite aluminum pole pieces and the number of the negative electrode composite copper pole pieces are both at least one.

9. A high-safety lithium-ion battery according to claim 1, characterized in that: Also included is an electrolyte and a housing.

10. The method for manufacturing a high-safety lithium-ion battery according to any one of claims 1 to 9, characterized in that: The production method comprises: S1: Make battery cells; S2: placing the battery cell in the shell, vacuum baking, and injecting electrolyte; S3: Charge and activate, then seal to make a battery.

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