High safety lamination type lithium ion cell structure, battery and preparation method thereof

Abstract

The application discloses a high-safety lamination type lithium ion cell structure and a battery thereof. The battery comprises a cell, an electrolyte and a shell. The cell comprises positive and negative electrode sheets alternately stacked and separated by a diaphragm. The positive and / or negative electrode sheets have an epitaxial empty foil arranged on the same side. At least one layer of the positive and / or negative electrode sheets is a base layer in a sawtooth partition design. The epitaxial empty foil of other non-base layers corresponds to the sawtooth of at least one partition of the base layer in the stacking direction and is welded to the sawtooth. The cell structure is partitioned and welded, thereby reducing the thickness of the lamination type lithium battery welding joint, improving the welding effect, the internal space utilization rate of the cell and the energy density of the battery, and reducing the safety problems caused by the over-thick battery head welding joint piercing the battery shell.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to a high-safety stacked lithium-ion cell structure, its battery, and its preparation method. Background Technology

[0002] Technology changes lives. The diversification of electronic product applications is altering our lifestyles, making life more convenient while placing higher demands on battery life. Lithium batteries are mainly classified into two types based on their core manufacturing method: wound and stacked. Due to their structural advantages, stacked batteries have a 2% to 5% higher energy density than wound batteries. Furthermore, the stacking process offers better rate performance and more diverse shapes, making stacked batteries more widely applicable. However, in existing stacked battery structures, the internal electrodes and external tabs are mainly welded at the battery head. After welding, the weld joint needs to be bent before being placed inside the battery casing. The space left inside the casing for the weld joint causes a certain loss of energy density. Additionally, because the separator is layered at the battery head, there is a possibility of misalignment between the upper and lower layers. The separator's function is to isolate the positive and negative electrodes, limiting the current increase under overcharging or temperature rise conditions to prevent short circuits and explosions. Moreover, the thickness of the welded joints, especially in thick batteries, can also pose certain safety hazards.

[0003] Chinese patent CN108461811B discloses an electrode and cell for a wound lithium-ion battery. This patent improves battery power performance by doubling the number of tabs and increases energy density by coating the entire surface of the electrode body with electrode material. Patent CN112117496A discloses a method for manufacturing a stacked cell, a stacked cell, and a lithium battery. This patent aligns all positive electrode empty foil areas with the ends furthest from the center of the positive electrode to form positive tabs; it also stacks and welds all negative electrode empty foil areas, aligning the ends furthest from the center of the negative electrode to form negative tabs, simplifying the cell manufacturing process and improving battery quality. While these patented solutions structurally improve the energy density and production quality of lithium batteries, the thickness of the welded joints connecting the electrode to the external tabs within the cell is not reduced. The internal space utilization of the cell can still be improved, but the safety issues caused by excessively thick welded joints are not addressed. Summary of the Invention

[0004] This invention addresses the problems in existing technologies by disclosing a high-safety stacked lithium-ion cell structure, its battery, and its fabrication method. The aim is to improve the internal space utilization of the stacked lithium battery, thereby increasing its energy density. By partitioning and welding the cell structure, the internal space utilization is increased, and the safety issues caused by excessively thick weld joints between all positive or negative electrodes and the outer tabs at the battery head, which could lead to the battery being punctured by the outer casing, are avoided.

[0005] This invention is achieved through the following technical solution:

[0006] A high-safety stacked lithium-ion cell structure includes alternating stacked positive and negative electrode sheets separated by a separator. The positive and / or negative electrode sheets have epitaxial open foils disposed on the same side. At least one of the positive and / or negative electrode sheets is a base layer. The base layer is designed with a serrated partition. Other non-base layer epitaxial open foils correspond to the serrations of at least one partition on the base layer in the stacking direction and are welded to the serrations.

[0007] The above-described design of the present invention enables the outer epitaxial foil of the non-base layer of the positive electrode and / or negative electrode to be welded to the serrations on the base layer of the positive electrode and / or negative electrode in a partitioned manner, forming multiple welding connection points based on the number of partitions. This avoids the situation where all the positive or negative electrode pieces are concentrated at one welding connection position at the battery head, which could lead to the battery being punctured by the outer casing due to excessive thickness at a single welding connection position, thus causing safety issues. The partitioned welding connection of the cell structure reduces the number of layers at each welding position of the positive and negative electrode pieces, reduces the outward extension length of the serrations at the welding point, thereby reducing the distance between the cell and the casing, preventing bending at the welding joint, increasing the utilization rate of the internal space of the cell, and improving the energy density of the stacked lithium battery.

[0008] As a further preferred embodiment, the length of the epitaxial foil of the non-base layer increases with the increase of its interlayer spacing from the base layer, so that the epitaxial foil of the non-base layer has the same length after folding and welding.

[0009] As a further preferred embodiment, the positive electrode and the negative electrode each have a positive electrode base layer and a negative electrode base layer, respectively.

[0010] As a further preferred embodiment, the positive electrode base layer and the negative electrode base layer are located on the outermost or innermost positive electrode and negative electrode, respectively, which facilitates the connection of external electrode tabs and improves the welding effect.

[0011] As a further preferred embodiment, the number of serrations in the base layer partition is set to at least two, that is, at least two partitions.

[0012] As a further preferred embodiment, the serrations of each partition on the base layer have the same length; the serrations of each partition also preferably have the same spacing, and the spacing between the serrations of each partition on the base layer is greater than 0.

[0013] As a further preferred embodiment, the epitaxial foils of the non-base layer welded to the serrations of each partition on the base layer are all located on sequentially adjacent positive and negative electrode sheets; even further, the epitaxial foils of the non-base layer welded to the serrations of adjacent partitions on the base layer are also all located on sequentially adjacent positive and negative electrode sheets. This sequential adjacent arrangement facilitates the welding operation.

[0014] As a further preferred option, the number of non-base layer epitaxial empty foil layers that are welded to the serrations of each partition of the base layer is ≤8 layers. Reducing the number of non-base layer epitaxial empty foil layers that are welded to the serrations of each partition can reduce the thickness of the weld joint and improve the safety of lithium batteries at high temperatures.

[0015] The cell structure separator is a PP separator or a PE separator.

[0016] The present invention also provides a battery comprising the above-described cell structure, wherein the battery further comprises an electrolyte and a casing, the cell is installed in the casing, and the electrolyte is injected into the cell.

[0017] The present invention also provides a method for preparing the above-mentioned high-safety stacked lithium battery. The method involves stacking each layer of positive electrode sheet and negative electrode sheet using a separator, such that the epitaxial foils of the positive electrode sheet and negative electrode sheet are located on both sides of the cell. Then, the epitaxial foils on the non-base layer of the positive electrode sheet and the corresponding serrations on the base layer of the negative electrode sheet are welded together. The battery is then obtained through a liquid injection process, a chemical process, and a sealing process.

[0018] As a further preferred option, the electrolyte injection process is carried out in an environment with a dew point below -55°C; the chemical processing process is carried out in an environment with a dew point below -10°C.

[0019] Compared with existing technologies, the characteristics and beneficial effects of this cell structure and its battery are as follows:

[0020] 1. The cell structure is partitioned and welded. The positive and negative electrode sheets each have a base layer with a serrated partition design, which is welded to the corresponding non-base layer positive and negative electrode sheet outer foil. After the non-base layer stacked outer foil is welded to the serrated partition of the base layer, the base layer positive and negative electrode sheets are welded to the external positive and negative electrode tabs of the battery. The serrated weld joints of each partition after welding have the same length, which reduces the thickness of the welding joint at the head of the stacked lithium battery and eliminates the bending structure at the welding joint at the battery head. This not only improves the welding effect, the internal space utilization of the stacked lithium battery cell and the energy density of the stacked lithium battery, but also reduces the safety problems caused by the excessive thickness of the welding joint at the battery head piercing the battery shell. 2. The welding parameters of the epitaxial foil layers of the non-base layer positive and negative electrode sheets are optimized. The serrated welding connection of the non-base layer epitaxial foil layers of each base layer positive and negative electrode sheet is ≤8 layers, which can reduce the thickness of the welding joint and improve the safety of lithium batteries at high temperatures. Attached Figure Description

[0021] To more clearly illustrate the cell structure in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the cell structure.

[0022] Figure 1 This is a schematic diagram of the basic layer structure of the lithium-ion positive electrode sheet provided in an embodiment of the present invention.

[0023] Figure 2 This is a schematic diagram of the basic layer structure of the lithium-ion negative electrode sheet provided in an embodiment of the present invention.

[0024] Figure 3 This is a three-dimensional structural diagram of the battery cell before welding, provided in an embodiment of the present invention.

[0025] Figure 4 This is a three-dimensional structural diagram of the battery cell after welding, provided in an embodiment of the present invention.

[0026] Figure 5 This is a schematic diagram of an existing unpartitioned, stacked lithium-ion battery cell structure.

[0027] Figure 6 A schematic diagram of a stacked lithium battery cell structure is provided for an embodiment of the present invention.

[0028] The above figures include the following reference numerals:

[0029] X-1 - First serration of the positive electrode base layer; X-2 - Second serration of the positive electrode base layer; Xm - Mth serration of the positive electrode base layer; Xn - Nth serration of the positive electrode base layer; X-0 - Coating of the positive electrode base layer; 1-2 - Second epitaxial empty foil of the non-base layer of the positive electrode; 1-m - Mth epitaxial empty foil of the non-base layer of the positive electrode; 1-n - Nth epitaxial empty foil of the non-base layer of the positive electrode; Y-1 - First serration of the negative electrode base layer; Y -2-Second serration of the negative electrode base layer; Ym-mth serration of the negative electrode base layer; Yn-nth serration of the negative electrode base layer; 2-2-Second epitaxial empty foil of the non-base layer of the negative electrode; 2-m-mth epitaxial empty foil of the non-base layer of the negative electrode; 2-n-nth epitaxial empty foil of the non-base layer of the negative electrode; Y-0-Coating of the negative electrode base layer; 1-Positive electrode; 2-Negative electrode; 3-Separator; d1-Cell length; d2-Battery casing length. Detailed Implementation

[0030] To facilitate understanding of the battery cell structure of the present invention, a more comprehensive description of the battery cell structure of the present invention will be provided below, preferred embodiments of the present invention will be given, and the technical solution of the present invention will be further illustrated in conjunction with the accompanying drawings.

[0031] An example diagram of a high-safety stacked lithium-ion battery cell structure of the present invention is shown below. Figure 4 As shown, it includes alternately stacked positive electrode plates 1 and negative electrode plates 2, separated by a separator 3. The positive electrode plate 1 has a current collector in its center. Figure 3 , 4 The current collector 1 has a positive electrode coating on both sides. The portion of the current collector without the positive electrode coating extends outwards as an epitaxial foil. All epitaxial foils of the positive electrode 1 in the cell structure extend outwards to the same side of the cell. The positive electrode coating material includes a positive electrode active material, a positive electrode conductive agent, and a positive electrode binder. The positive electrode active material includes one or more of lithium cobalt oxide, lithium manganese oxide, ternary lithium, lithium iron phosphate, and lithium-rich manganese. The positive electrode conductive agent includes one or more of CNTs, SP, GF-2, and graphene. The positive electrode binder includes PVDF. The negative electrode 2 has a current collector in the center, with a negative electrode coating on both sides. The portion of the current collector without the negative electrode coating extends outwards as an epitaxial foil. All epitaxial foils of the negative electrode 2 in the cell structure also extend outwards to the same side of the cell, and the direction of extension is opposite to that of the epitaxial foil of the positive electrode 1. The negative electrode coating materials include negative electrode active materials, negative electrode conductive agents, and negative electrode binder materials. The negative electrode active materials include one or more of graphite, hard carbon, and SiO; the negative electrode conductive agents include one or more of CNtS, SP, GF-2, and graphene; and the negative electrode binder materials include one or more of SBR, pAA, and CMC.

[0032] The positive electrode 1 includes a base layer, and the others are non-base layers. The base layer is typically positioned as either the outermost or innermost positive electrode layer. An exemplary structure of the base layer is shown below. Figure 1 As shown, it includes a positive electrode base layer, which has n serrated sections, including: the first serration X-1, the second serration X-2, ..., the m-th serration Xm, ..., the n-th serration Xn. The number of serrations in each section of the positive electrode base layer is ≥2, the serration lengths in each section are equal, and the spacing between the serrations in each section is greater than 0. The non-base layer of the positive electrode is as follows... Figure 3 As shown, the non-base layer of the positive electrode sheet has n-1 layers of epitaxial empty foil, including: the second layer of epitaxial empty foil 1-2... the mth layer of epitaxial empty foil 1-m... the nth layer of epitaxial empty foil 1-n. The lengths of the different layers of epitaxial empty foil increase sequentially in the stacking direction away from the base layer, such as... Figure 3 As shown, the length relationship of the epitaxial empty foil on the non-base layer of the positive electrode is: nth layer epitaxial empty foil 1-n>mth layer epitaxial empty foil 1-m>...>2nd layer epitaxial empty foil 1-2 of the non-base layer of the positive electrode.

[0033] The negative electrode 2 includes a base layer, and the others are non-base layers. The base layer is typically positioned as either the outermost or innermost negative electrode layer. An exemplary structure of the base layer is shown below. Figure 2 As shown, it includes a negative electrode base layer, which has n serrated sections, including: the first serration Y-1, the second serration Y-2, ..., the m-th serration Ym, ..., the n-th serration Yn. The number of serrations in each section of the negative electrode base layer is ≥2, the serration lengths in each section are equal, and the spacing between the serrations in each section is greater than 0. The non-base layer of the negative electrode is as follows... Figure 3 As shown, the non-base layer of the negative electrode sheet has n-1 layers of epitaxial empty foil, including: the second layer of epitaxial empty foil 2-2... the m-th layer of epitaxial empty foil 2-m... the n-th layer of epitaxial empty foil 2-n. The lengths of the different layers of epitaxial empty foil increase sequentially in the stacking direction away from the base layer, such as... Figure 3 As shown, the length relationship of the epitaxial empty foil on the non-base layer of the negative electrode sheet is: nth layer epitaxial empty foil 2-n>mth layer epitaxial empty foil 2-m>...>2nd layer epitaxial empty foil 2-2 of the non-base layer of the negative electrode sheet.

[0034] PP or PE diaphragms are used to stack between each layer of positive and negative electrode plates.

[0035] To further verify the technical effectiveness of the high-safety stacked lithium-ion cell structure of the present invention, a series of specific experiments are presented below as implementation examples.

[0036] I. Preparation method:

[0037] The example uses a stacked lithium battery with battery model number 476875PL, which includes battery cells ( Figure 4 The components include the electrolyte and the casing. For brevity, this invention only describes in detail one welding method for a high-safety stacked lithium-ion cell structure. The correct preparation method includes the following steps:

[0038] Setting: The positive electrode of the battery cell structure has K layers of positive electrode sheets, and only 1 layer of positive electrode sheet base layer. The second serration X-2 to the (n-1)th serration Xn-1 of the positive electrode sheet base layer are defined, and the second epitaxial empty foil 1-2 to the (n-1)th epitaxial empty foil 1-n-1 of the positive electrode sheet non-base layer are defined. The average number of epitaxial empty foil layers welded to the serrations of the partition is defined as int((k-1) / (n-1)), where int function represents rounding.

[0039] Setting: The negative electrode of the battery cell structure has K layers of negative electrode sheets, and only 1 layer of negative electrode sheet base layer. The second sawtooth of the negative electrode sheet base layer is set to Y-2 to the (n-1)th sawtooth of the negative electrode sheet base layer, and the second epitaxial empty foil layer 2-2 to the (n-1)th epitaxial empty foil layer 2-n-1 of the negative electrode sheet non-base layer is set. The average number of epitaxial empty foil layers welded to the sawtooth of the partition is = int((k-1) / (n-1)), where int function means rounding.

[0040] Defined as follows: The difference between the cell length d1 and the casing length d2 is the gap A, where gap A = d2 - d1, unit: mm. The preferred length difference for the gap is 4-6 mm. The top seal length of the casing is 3 mm. The battery energy density E = battery 0.2C (discharge capacity × discharge plateau voltage / cell volume).

[0041] Step 1: Stack each layer of positive electrode 1 and negative electrode 2 using PP or PE separators, with the outer epitaxial foil of the positive electrode and the outer epitaxial foil of the negative electrode located on both sides of the cell.

[0042] Step 2: At the positive electrode of the battery cell, weld the stacked positive electrode sheet non-base layer 2nd epitaxial empty foil 1-2... positive electrode sheet non-base layer mth epitaxial empty foil 1-m... positive electrode sheet non-base layer nth epitaxial empty foil 1-n to the corresponding positive electrode sheet base layer 2nd serration X-2... positive electrode sheet base layer mth serration Xm... positive electrode sheet base layer nth serration Xn. The length relationship of the positive electrode sheet non-base layer epitaxial empty foil is: positive electrode sheet non-base layer nth epitaxial empty foil 1-n> positive electrode sheet non-base layer mth epitaxial empty foil 1-m>...> positive electrode sheet non-base layer 2nd epitaxial empty foil 1-2. The number of serrations in each section of the positive electrode sheet base layer is ≥2, the spacing between the serrations in each section is greater than 0, and the length of the serrations in each section is equal.

[0043] Step 3: At the negative electrode of the battery cell, weld the stacked negative electrode sheet non-base layer 2-2... negative electrode sheet non-base layer m-m... negative electrode sheet non-base layer n-n epitaxial empty foil to the corresponding negative electrode sheet base layer second sawtooth Y-2... negative electrode sheet base layer m-m... negative electrode sheet base layer n-n sawtooth Yn. The length relationship of the negative electrode sheet non-base layer epitaxial empty foil is: negative electrode sheet non-base layer n-n epitaxial empty foil 2-n> negative electrode sheet non-base layer m-m epitaxial empty foil 2-m>...> negative electrode sheet non-base layer 2-2 epitaxial empty foil 2-2. The number of sawtooths in the negative electrode sheet base layer partition is ≥2, the spacing between the sawtooths in the partition is greater than 0, and the sawtooth lengths in the partition are equal.

[0044] Step 4: The battery cells are sequentially subjected to the electrolyte injection process under the following conditions: the battery cells are placed in an environment with a dew point below -55°C.

[0045] Step 5: Chemical process, specific conditions are as follows: The battery cells are placed in an environment with a dew point below -10°C.

[0046] Step 6: Sealing process.

[0047] In addition, battery capacity tests were conducted on the experimental group under the following conditions: (1) read the discharge capacity at 0.2C; (2) let stand for 5 minutes; (3) discharge from 0.5C CC to 4.35V, and from CV to 0.05C; (4) let stand for 5 minutes; (5) discharge from 0.2C DC to 3.0V; (6) end the test. The test results are shown in Tables 1, 2 and 3.

[0048] In addition, a 130℃ hot box test was conducted on the experimental group. The specific test conditions were as follows: (1) The battery was placed in a forced-air oven and heated at a rate of 5℃ / min. When the temperature of the oven reached the range of 130℃±2℃, the timer was started and heating was stopped after the battery had been placed inside for 60 minutes; (2) When the temperature of the oven dropped below 50℃, the oven was checked to confirm the condition of the battery; (3) As long as the battery did not catch fire or explode, we considered the test to be passed and the test was completed. The test results are shown in Tables 1, 2 and 3.

[0049] II. Analysis of Verification Results

[0050] A comparative experiment of stacked lithium batteries was conducted, with control groups 1-6 and experimental groups 1-6. Experimental groups 1-6 adopted the partitioned welding method of the positive and negative electrode epitaxial foils of the present invention, which is based on the serrations of the partitions on the base layers of the positive and negative electrode sheets. Control groups 1-6 adopted the general welding method in the prior art without partitions, that is, all the epitaxial foils of the positive electrode sheets that are not in the base layer are welded to the serrations of the partitions of the positive electrode sheet base layer through a single solder joint, and all the epitaxial foils of the negative electrode sheets that are not in the base layer are welded to the serrations of the partitions of the negative electrode sheet base layer through a single solder joint.

[0051] Setting: The cell structure has a total of 23 positive electrode layers (K1) and 24 negative electrode layers (K2). Short-circuit rate, capacity, energy density, and thermal shock pass rate were tested on existing lithium-ion batteries with different gaps (A) and experimental lithium-ion batteries. The experimental results are shown in Table 1 below.

[0052] Table 1

[0053]

[0054]

[0055] As shown in Table 1, as the gap A between the cell length d1 and the casing length d2 increases, when the gap A in the control group is 6.5mm to 7.0mm, the short-circuit rate of the batteries in the control group is below 10%. In contrast, the short-circuit rate of the experimental group batteries can be controlled to below 10% when the gap A is 4.5mm to 7.0mm. This demonstrates that partitioned welding significantly lowers the lower limit of gap A control. After layered welding of the cell structure, excessively thick weld joints and bending at the weld joints are avoided. The thermal shock rate and short-circuit rate of the lithium batteries in the six experimental groups are all better than those in the control group, and the internal space utilization of the battery cell is increased. Based on the above, to further optimize capacity and energy density, the gap A can be optimized and controlled at 5.0mm-6.0mm, increasing the battery energy density from 668Wh / L to 685Wh / L.

[0056] Comparative experiments were conducted on stacked lithium-ion batteries, with experimental groups 7, 8, and 9 set up. The total number of positive electrode layers K1 = 23 and the total number of negative electrode layers K2 = 24 were set. The short-circuit rate, capacity, energy density, and thermal shock pass rate of the lithium-ion batteries in the experimental group with a gap A = 5mm were tested. The experimental results are shown in Table 2 below.

[0057] Table 2

[0058]

[0059] As shown in Table 2, the fewer the number of epitaxial foil layers welded to the 2nd to (n-1)th serrations, the lower the thermal shock rate of the lithium battery. When the number of epitaxial foil layers welded is too high (as in experimental group 7), the weld joint becomes too thick, making it unsuitable for folding after welding. Therefore, we need to further optimize the number of epitaxial foil layers welded to the serrations of each zone to further improve the high-temperature performance of the battery. When the number of serrations in a zone is 4, we further designed the following experiment.

[0060] A comparative experiment of stacked lithium-ion batteries was conducted, with experimental groups 10, 11...26 and 27. The following settings were established: the number of serrations in the base layer of the positive electrode was 4; the total number of positive electrode layers K1 in experimental group 10 was 22, and the total number of positive electrode layers K1 in the other experimental groups decreased by one layer successively; the total number of negative electrode layers K2 in experimental group 10 was 23, and the total number of negative electrode layers K2 in the other experimental groups decreased by one layer successively. The process short-circuit rate, capacity, energy density, and thermal shock pass rate of the lithium-ion batteries in the experimental group with a gap A = 5mm were tested. The experimental results are shown in Table 3 below.

[0061] Table 3

[0062]

[0063] As verified by Table 3, when the gap A = 5mm, the number of serrations in the positive electrode base layer and negative electrode base layer partitions = 4, the number of positive electrode layers decreases from 10 to 2, and the average number of positive electrode layers welded to the serrations of the partitions = int((k-1) / (n-1)). The number of negative electrode layers decreases from 11 to 2, and the average number of negative electrode layers welded to the serrations of the partitions = int((k-1) / (n-1)). The results show that when the number of welded layers int((k-1-a) / (n-2)) > 8, the thermal shock pass rate is low, all less than 90%. It can be seen that when the number of adjacent epitaxial foil layers of non-base layers welded to the serrations of each partition of the base layer is ≤ 8, this scheme can improve the energy density and safety performance of the battery.

[0064] 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 within the protection scope of the present invention.

Claims

1. A high-safety stacked lithium-ion cell structure, characterized in that, It includes alternating stacked positive and negative electrode sheets separated by a diaphragm, the positive and / or negative electrode sheets having epitaxial foils disposed on the same side; The positive electrode and the negative electrode each have a positive electrode base layer and a negative electrode base layer, respectively. The positive electrode base layer and the negative electrode base layer are located on the outermost or innermost positive electrode and negative electrode, respectively. The length of the epitaxial empty foil of the non-base layer increases with the increase of the interlayer spacing of its distance from the base layer. The base layer has a serrated partition design. Other non-base layer epitaxial empty foils correspond to the serrations of at least one partition on the base layer in the stacking direction and are welded to the serrations. The number of serrations in the base layer partition is set to at least two, and the number of epitaxial empty foil layers of the non-base layer corresponding to the serrations in each partition of the base layer is ≤8.

2. The high-safety stacked lithium-ion cell structure according to claim 1, characterized in that, The epitaxial foils of the non-base layer welded to the serrations of each partition on the base layer are all located on the adjacent positive and negative electrode plates; the epitaxial foils of the non-base layer welded to the serrations of adjacent partitions on the base layer are also located on the adjacent positive and negative electrode plates.

3. The high-safety stacked lithium-ion cell structure according to claim 1, characterized in that, The serrations of each partition on the base layer have the same length; the serrations of each partition are further preferably spaced at the same distance, and the distance between the serrations of each partition on the base layer is greater than 0.

4. The high-safety stacked lithium-ion cell structure according to claim 1, characterized in that, The positive electrode coating on the positive electrode sheet comprises a positive electrode active material, a positive electrode conductive agent, and a positive electrode binder. The positive electrode active material includes one or more of lithium cobalt oxide, lithium manganese oxide, ternary lithium, lithium iron phosphate, and lithium-rich manganese oxide. The positive electrode conductive agent includes one or more of CNTs, SP, GF-2, and graphene. The positive electrode binder includes PVDF. The negative electrode coating on the negative electrode sheet comprises a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder. The negative electrode active material includes one or more of graphite, hard carbon, and SiO. The negative electrode conductive agent includes one or more of CNtS, SP, GF-2, and graphene. The negative electrode binder includes one or more of SBR, pAA, and CMC. The separator is a PP separator or a PE separator.

5. A battery comprising the high-safety stacked lithium-ion cell structure as described in any one of claims 1-4.

6. The method for preparing the battery according to claim 5, characterized in that, Includes the following steps: S1: Stack each layer of positive and negative electrode sheets using a separator, with the non-base layer epitaxial foil of the positive electrode sheet and the non-base layer epitaxial foil of the negative electrode sheet located on both sides of the cell; S2: Partition welding the positive and negative electrode structures of the cell, respectively connecting the epitaxial foil on the non-base layer of the positive and negative electrode sheets with the corresponding serrated welds on the base layer; S3: Perform liquid injection, chemical processing, and sealing processes on the cell obtained in S2 to obtain the battery.

7. A method for preparing a high-safety stacked lithium battery according to claim 6, characterized in that, the positive electrode structure of the cell is prepared by: stacking the second layer of epitaxial empty foil (1-2) of the non-base layer of the positive electrode sheet (1-m) of the non-base layer of the positive electrode sheet (1-m) of the positive electrode sheet (1-n) of the non-base layer of the positive electrode sheet (1-n) of the positive electrode sheet (1-n) of the positive electrode sheet (1-n) of the non-base layer of the positive electrode sheet (1-n) of the positive electrode sheet (1-m) of the corresponding second serration (X-2) of the base layer of the positive electrode sheet (X-2) ... The nth serration (Xn) of the base layer of the negative electrode sheet is welded together; the negative electrode structure of the battery cell is prepared by welding together the second epitaxial empty foil (2-2) of the non-base layer of the stacked negative electrode sheet, the mth epitaxial empty foil (2-m) of the non-base layer of the negative electrode sheet, the nth epitaxial empty foil (2-n) of the non-base layer of the negative electrode sheet, and the corresponding second serration (Y-2) of the base layer of the negative electrode sheet, the mth serration (Ym) of the base layer of the negative electrode sheet, and the nth serration (Yn) of the base layer of the negative electrode sheet.

8. The method for preparing a high-safety stacked lithium battery according to claim 6, characterized in that, in the liquid injection process, the battery cell is placed in an environment with a dew point below -55°C; and in the chemical processing process, the battery cell is placed in an environment with a dew point below -10°C.

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