Lithium thionyl chloride battery, preparation method of positive electrode piece and preparation method of lithium thionyl chloride battery

Abstract

The invention belongs to the technical field of batteries, and discloses a lithium thionyl chloride battery, a preparation method of a positive electrode piece and a preparation method of the lithium thionyl chloride battery. The lithium thionyl chloride battery comprises a shell, a negative electrode piece and a positive electrode piece, wherein the shell is in a flat cylindrical shape, one side of the shell is provided with a positive pole and a negative pole, the positive pole and the negative pole are arranged in an insulating manner, and the shell is provided with a containing cavity; the cathode piece is the same as the shell in shape, and the cathode piece is flatly laid and electrically connected to the bottom wall of the accommodating cavity; the negative pole piece is electrically connected with the negative pole post; the positive pole piece is the same as the shell in shape, the positive pole piece is insulated and covers the negative pole piece, the positive pole piece and the cavity wall of the containing cavity are insulated, and the positive pole piece is electrically connected with the positive pole column. According to the lithium thionyl chloride battery, the mounting height of the lithium thionyl chloride battery can be reduced, the mounting space and other accessories are reduced, the space utilization rate is improved, and meanwhile, the energy density of the lithium thionyl chloride battery is also improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a lithium-ion battery, a method for preparing a positive electrode, and a method for preparing a lithium-ion battery. Background Art

[0002] Lithium-ion battery is a type of lithium primary battery. It is the type with the highest specific energy and the widest operating temperature range among the current commercial battery products. At present, lithium-ion batteries can be roughly divided into two categories according to their structures, namely power type and energy type. Energy type batteries adopt a carbon package structure and are mainly used in scenarios with low power and long service life. Power type batteries adopt a winding structure and are mainly used in scenarios that require continuous high power pulses.

[0003] In the prior art, both power-type and energy-type lithium-ion batteries are generally cylindrical batteries with relatively fixed sizes. When using, customers often need to install the lithium-ion battery horizontally, and design and process a specific battery compartment on the circuit board. At the same time, they also need to process leads or pins to fix the lithium-ion battery and connect it to the circuit board; however, such a setting will increase the height of the entire circuit board and the number of components, reducing the utilization of space. At the same time, since the positive electrode carbon in the energy-type battery is completely wrapped by the diaphragm, and the carbon positive electrode of the power-type battery is supported by a collector, the positive electrode strength requirements of these two batteries are not high, and the density inside the positive electrode is relatively small, which increases the area occupied by the positive electrode, and the connection force between the internal parts of the positive electrode is not strong, resulting in low space utilization of the positive electrode, the problem of partial detachment, and the reduction of the energy density of the lithium-ion battery.

[0004] Therefore, a new type of lithium-ion battery is urgently needed to solve the above technical problems. Summary of the invention

[0005] One object of the present invention is to provide a lithium-ion battery that can reduce its own installation height, reduce installation space and other accessories, improve space utilization, and also improve its own energy density.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] Lithium-ion batteries, including:

[0008] The shell is in a flat cylindrical shape, a positive pole and a negative pole are arranged on one side of the shell, the positive pole and the negative pole are insulated, and the shell has a receiving cavity;

[0009] A negative electrode member, the negative electrode member and the shell have the same shape, the negative electrode member is laid flat and electrically connected to the bottom wall of the accommodating cavity; the negative electrode member is electrically connected to the negative electrode post;

[0010] A positive electrode component, the positive electrode component and the shell have the same shape, the positive electrode component is insulated and covers the negative electrode component, and the positive electrode component is insulated from the cavity wall of the accommodating cavity, and the positive electrode component is electrically connected to the positive electrode column.

[0011] Optionally, it further comprises a diaphragm, the diaphragm having a bowl-shaped separation groove, the diaphragm is covered and arranged on the negative electrode component, and the positive electrode component is arranged in the separation groove.

[0012] Optionally, the lithium-substrate battery further comprises a negative electrode current collecting net, which is arranged on the bottom wall of the accommodating cavity, and is used to electrically connect the negative electrode member to the bottom wall of the accommodating cavity.

[0013] Optionally, the lithium-substrate battery further includes a positive electrode current collector, the positive electrode current collector covers and is electrically connected to the positive electrode member, and the positive electrode current collector is electrically connected to the positive electrode column.

[0014] Optionally, a connecting hole is provided in the middle of the positive electrode current collector, one end of the positive electrode pole insulation seal extending into the accommodating cavity passes through the connecting hole and abuts against the positive electrode piece, and the hole wall of the connecting hole abuts against the positive electrode pole.

[0015] Optionally, the above-mentioned shell includes a shell and a cover group, the above-mentioned cover group is sealed and connected to the above-mentioned shell, and is enclosed with the above-mentioned shell to form the above-mentioned accommodating cavity, the above-mentioned negative electrode column and the above-mentioned positive electrode column are both arranged on the above-mentioned cover group, and the above-mentioned cover group is provided with an insulating part on the side facing the above-mentioned accommodating cavity.

[0016] The beneficial effects of the lithium-ion battery provided by the present invention are as follows: by making the positive electrode into a flat cylindrical shape, and stacking and insulating with the negative electrode of the same flat cylindrical shape, the compaction density and space utilization of the positive electrode are improved, the problem of partial detachment of the positive electrode is avoided, and the energy density of the lithium-ion battery is improved. In addition, the lithium-ion battery is in a flat cylindrical shape as a whole, so that the overall height of the lithium-ion battery is reduced, so that when the lithium-ion battery is installed, its height does not exceed the height of other structures on the circuit board, thereby improving the space utilization; at the same time, the positive pole and the negative pole are both arranged on the same side of the shell, and when the lithium-ion battery is installed on the circuit board, the positive pole and the negative pole can be directly inserted into the positive connection end and the negative connection end of the circuit board, without the need to set up an additional battery compartment for fixing, and without the need to set up additional leads for electrical connection, thereby reducing the number of components and space occupancy.

[0017] Another object of the present invention is to provide a method for preparing a positive electrode member, which can produce a positive electrode member with high compaction density and avoid partial falling of the positive electrode material during reuse.

[0018] To achieve this object, the present invention adopts the following technical solutions:

[0019] A method for preparing a positive electrode component is used to prepare the positive electrode component of the above-mentioned lithium-ion battery. The method for preparing the positive electrode component comprises the following steps:

[0020] S1. Mixing preparation: Mixing dry powder and adding wet powder in sequence according to a preset ratio until the mixture is uniform, and then drying and forming to obtain positive electrode powder;

[0021] S2, roller pressing: spreading the wet positive electrode powder in a molding die, and rolling it step by step until it is formed into a positive electrode sheet of a preset thickness and then dried;

[0022] S3, post-processing: cutting and shaping the above-mentioned positive electrode sheet to obtain a positive electrode component.

[0023] Optionally, in step S1, after the positive electrode powder is evenly mixed, the positive electrode powder is sequentially dried at low temperature and at high temperature.

[0024] Optionally, after step S1, the method further includes: taking out the positive electrode powder after high-temperature drying and soaking it in an isopropanol solution for a preset time to obtain the wet positive electrode powder.

[0025] The beneficial effects of the preparation method of the positive electrode provided by the present invention are as follows: the positive electrode can be prepared by sequentially performing dry powder mixing, wet powder mixing, low temperature drying, high temperature drying, infiltration, roll forming, drying, shaping, and stamping, and the positive electrode is formed by powder and rolled to improve its compaction density and volume utilization, avoid partial falling of the powder in the positive electrode, and at the same time improve the energy density of the lithium-ion battery.

[0026] Another object of the present invention is to provide a method for preparing a lithium-ion battery, which can produce a lithium-ion battery with high space utilization and high energy density.

[0027] To achieve this object, the present invention adopts the following technical solutions:

[0028] The preparation method of a lithium-ion battery comprises the following steps:

[0029] S100, preparation work: preparing a positive electrode member by the above-mentioned method for preparing a positive electrode member, and preparing a negative electrode member, a separator, a shell with a negative electrode current collecting net at the bottom, and a cover assembly with a positive electrode current collecting member integrated therein;

[0030] S200, stacking installation: placing the negative electrode component, the separator, and the positive electrode component in the accommodating cavity of the shell in sequence, and pressing the negative electrode component and the negative electrode current collecting net tightly together;

[0031] S300, closing the cover: pressing the positive electrode current collector in the cover assembly onto the positive electrode member, and sealingly pressing the cover assembly onto the housing;

[0032] S400, liquid injection and sealing: injecting electrolyte into the shell through the liquid injection hole of the cover assembly, and sealing the liquid injection hole with a sealing pin.

[0033] The preparation method of the lithium-ion battery in this embodiment is different from that of the other two types of lithium-ion batteries. It eliminates the need for other structural supports for the positive electrode powder, improves the compaction density and volume utilization of the positive electrode component, and thus improves the energy density of the lithium-ion battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a cross-sectional view of a lithium-subcell provided in a specific embodiment of the present invention;

[0035] Figure 2 It is a working flow chart of a method for preparing a positive electrode member provided in a specific embodiment of the present invention;

[0036] Figure 3 The present invention provides a flowchart of a method for preparing a lithium-ion battery according to a specific embodiment of the present invention;

[0037] Figure 4 It is a comparison table of the actual discharge capacity and voltage of Example 1 of the present invention and the comparative example.

[0038] In the figure:

[0039] 10. Shell; 11. Shell; 12. Cover assembly; 121. Cover plate; 1211. Liquid injection hole; 122. Positive pole; 123. Negative pole; 124. Sealing nail; 125. Insulating seal; 126. Insulating member;

[0040] 20. Negative electrode; 30. Positive electrode;

[0041] 40. diaphragm; 41. isolation groove;

[0042] 50. Negative electrode current collecting network;

[0043] 60. Positive electrode current collector; 61. Connecting hole. DETAILED DESCRIPTION

[0044] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0045] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0047] In the description of this embodiment, the terms "upper", "lower", "left", "right", etc., and the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of description and simplified operation, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0048] Please refer to Figure 1 , this embodiment provides a lithium-ion battery, which includes a shell 10, a negative electrode 20 and a positive electrode 30. The shell 10 is in a flat cylindrical shape, and a positive electrode column 122 and a negative electrode column 123 are provided on one side of the shell 10. The positive electrode column 122 and the negative electrode column 123 are insulated, and the shell 10 has a receiving cavity; the negative electrode 20 is in the same shape as the shell 10, and the negative electrode 20 is laid flat and electrically connected to the bottom wall of the receiving cavity; the negative electrode 20 is electrically connected to the negative electrode column 123; the positive electrode 30 is in the same shape as the shell 10, and the positive electrode 30 is insulated and covered on the negative electrode 20, and the positive electrode 30 is insulated from the cavity wall of the receiving cavity, and the positive electrode 30 is electrically connected to the positive electrode column 122.

[0049] The lithium-ion battery in this embodiment makes the positive electrode 30 into a flat cylindrical shape, and is stacked and insulated with the negative electrode 20 which is also a flat cylindrical shape, thereby improving the compaction density and space utilization of the positive electrode 30, avoiding the problem of partial detachment of the positive electrode 30, and improving the energy density of the lithium-ion battery. In addition, the lithium-ion battery is in a flat cylindrical shape as a whole, so that the overall height of the lithium-ion battery is reduced, so that when the lithium-ion battery is installed, its height does not exceed the height of other structures on the circuit board, thereby improving the space utilization; at the same time, the positive electrode column 122 and the negative electrode column 123 are both arranged on the same side of the shell 10. When the lithium-ion battery is installed on the circuit board, the positive electrode column 122 and the negative electrode column 123 can be directly inserted into the positive connection end and the negative connection end of the circuit board, without the need to set up an additional battery compartment for fixing, and without the need to set up additional leads for electrical connection, thereby reducing the number of components and space occupancy.

[0050] In some embodiments, the positive electrode 30 is formed by mixing, drying, and rolling powders of acetylene black, Ketjen black, polytetrafluoroethylene, purified water, isopropyl alcohol, etc. Of course, in other embodiments, the positive electrode 30 can also be prepared by other powders, which are not specifically limited here.

[0051] Optionally, the thickness of the positive electrode member 30 is 1 mm-3 mm, and the diameter is 20 mm-40 mm, which can meet the size of the lithium-ion battery required in practice.

[0052] In some embodiments, the negative electrode member 20 is a lithium sheet, which can achieve the negative electrode performance of the lithium-ion battery.

[0053] Optionally, the thickness of the negative electrode member 20 is 0.8 mm-2.5 mm, and the diameter is 21 mm-41 mm, which can meet the size of the lithium-ion battery required in practice.

[0054] In some embodiments, the lithium-ion battery further includes a separator 40, the separator 40 having a bowl-shaped separation groove 41, the separator 40 is disposed to cover the negative electrode member 20, and the positive electrode member 30 is disposed in the separation groove 41. The positive electrode member 30 is directly covered by the bowl-shaped separator 40, which can not only achieve insulation between the positive electrode member 30 and the negative electrode member 20, but also achieve insulation between the positive electrode member 30 and the cavity wall of the accommodating cavity.

[0055] Optionally, the material of the diaphragm 40 is glass fiber material, which can achieve the insulation performance of the diaphragm 40.

[0056] Optionally, the thickness of the diaphragm 40 is 0.2±0.01 mm, and the cutting diameter is 25 mm-48 mm, which can meet the size of the lithium-ion battery required in practice.

[0057] In some embodiments, a negative electrode current collecting net 50 is disposed on the bottom wall of the accommodating cavity, and the negative electrode current collecting net 50 is used to electrically connect the negative electrode member 20 to the bottom wall of the accommodating cavity, so that the housing 10 is electrically connected to the negative electrode member 20 .

[0058] Optionally, the negative electrode post 123 is directly protruded from the outer shell 10 , and such an arrangement can realize electrical connection between the negative electrode post 123 and the negative electrode member 20 .

[0059] Optionally, the negative electrode current collecting mesh 50 is a nickel mesh, which can achieve the function of conductive connection between the negative electrode member 20 and the outer shell 10 .

[0060] Optionally, the positive electrode column 122 is insulated from the housing 10, thereby achieving insulation between the positive electrode column 122 and the negative electrode column 123, thereby improving the safety of the lithium-ion battery. Specifically, in order to achieve electrical connection between the positive electrode column 122 and the positive electrode member 30, the positive electrode column 122 is insulated and sealed through the housing 10 and electrically connected to the positive electrode member 30.

[0061] Optionally, the diameter of the positive pole 122 is selected to be 0.8mm-2mm, and the length of the positive pole 122 extending into the positive electrode member 30 is ensured to just press against the positive electrode member 30 and exceed 0.2mm-0.5mm, so that the positive pole 122 and the positive electrode member 30 are stably connected.

[0062] Specifically, an insulating seal 125 is provided between the positive electrode column 122 and the housing 10 to achieve insulation between the two. Optionally, the insulating seal 125 is a glass seal, which has good insulating sealing performance and is widely used. Of course, in other embodiments, other insulating seals 125 can also be used to perform insulation sealing between the positive electrode column 122 and the housing 10.

[0063] In some embodiments, the lithium-substrate battery further includes a positive current collector 60 , which covers and is electrically connected to the positive electrode member 30 , and is electrically connected to the positive electrode column 122 . The positive electrode member 30 and the positive electrode column 122 can be electrically connected through the positive current collector 60 .

[0064] Specifically, a connecting hole 61 is provided in the middle of the positive current collector 60, and one end of the positive pole 122 that is insulated and sealed and extends into the accommodating cavity passes through the connecting hole 61 and abuts against the positive pole 30. The hole wall of the connecting hole 61 abuts against the positive pole 122, so that the positive pole 122 can not only be directly electrically connected to the positive pole 30, but also be electrically connected to the positive pole 30 through the positive current collector 60, so that the positive pole 30 and the positive pole 122 are evenly connected, improving the current capacity. In addition, the setting of the connecting hole 61 also facilitates the flow of the electrolyte.

[0065] Optionally, the positive electrode current collector 60 is made of stainless steel or nickel, which can satisfy the function of conductive connection between the positive electrode member 30 and the positive electrode column 122 .

[0066] Optionally, the positive electrode current collector 60 has a common thickness of 0.1 mm-0.2 mm and a diameter that is 1 mm-4 mm smaller than the diameter of the positive electrode member 30 , which can satisfy the conductive connection function of the positive electrode current collector 60 .

[0067] In some embodiments, the height of the accommodating cavity of the housing 10 is greater than the sum of the thickness of the positive electrode member 30, the thickness of the separator 40 and the thickness of the negative electrode member 20, so as to provide the lithium-ion battery with a certain expansion space, thereby improving the safety of the lithium-ion battery.

[0068] In some embodiments, the housing 10 includes a sealed shell 11 and a cover assembly 12 , wherein the cover assembly 12 is sealed to the shell 11 and encloses the shell 11 to form a receiving cavity, and the negative electrode column 123 and the positive electrode column 122 are both disposed in the cover assembly 12 .

[0069] Optionally, the housing 10 is made of stainless steel, which is a common choice for lithium-ion battery housings 10, is easy to conduct electricity, and has high strength. Of course, in other embodiments, the housing 10 may also be made of other materials, which are not specifically limited here.

[0070] Optionally, the wall thickness of the shell 11 is usually selected as 0.3mm-0.35mm, the inner diameter of the shell 11 is usually selected as 22mm-42mm, and the height of the shell 11 is usually selected as 3mm-8mm, which can meet the installation dimensions of the lithium-ion battery required by conventional requirements.

[0071] Specifically, the cover group 12 includes a cover plate 121, a positive electrode column 122, a negative electrode column 123 and an insulating seal 125. The negative electrode column 123 is protruded from the cover plate 121, the positive electrode column 122 is passed through the cover plate 121, and an insulating seal 125 is arranged between the positive electrode column 122 and the cover plate 121, so that the positive electrode column 122 and the cover plate 121 are insulated and sealed.

[0072] Optionally, the diameter of the cover plate 121 is 0.02 mm-0.06 mm larger than the inner diameter of the shell 11 , so that the cover plate 121 and the inner wall of the shell 11 are interference fit to achieve a sealed connection between the two.

[0073] In some embodiments, an insulating member 126 is provided on the side of the cover plate 121 facing the accommodating cavity to insulate the cover plate 121 from other structures in the internal accommodating cavity to avoid safety problems caused by short circuits.

[0074] Specifically, the diameter of the insulating member 126 is smaller than the inner diameter of the housing 10, so that no interference occurs while ensuring insulation. Optionally, the difference between the inner diameter of the housing 10 and the diameter of the insulating member 126 is 1 mm-2 mm.

[0075] Optionally, since the insulating member 126 is disposed on the side of the cover plate 121 facing the accommodating cavity, the insulating member 126 is provided with a through hole to penetrate the positive electrode column 122 .

[0076] Optionally, the insulating member 126 is made of mica, which has good insulation properties.

[0077] Optionally, the insulating member 126 is provided with small holes to facilitate the flow of electrolyte.

[0078] In some embodiments, the cover plate 121 is further provided with a liquid injection hole 1211 for injecting electrolyte of the lithium-ion battery.

[0079] Optionally, the injection hole 1211 is sealed and connected to the sealing nail 124, so that after the injection is completed, the sealing nail 124 seals the injection hole 1211, thereby ensuring the sealing of the lithium-ion battery.

[0080] This embodiment further provides a method for preparing a positive electrode member, which is used to prepare the positive electrode member 30 of the lithium-ion battery described in any of the above schemes, so as to improve the compaction density of the positive electrode member 30 and thus improve the volume utilization rate of the positive electrode member 30.

[0081] Please refer to Figure 2 Specifically, the preparation method of the positive electrode member includes the following steps:

[0082] Step S1, mixing preparation: mixing dry powder and adding wet powder in sequence according to a preset ratio until the mixture is uniform, and then drying and forming to obtain positive electrode powder.

[0083] Optionally, in step S1, the positive electrode dry powder and the corresponding weight percentages are: 75%-84% acetylene black, 1%-2% Ketjen black and 15%-25% polytetrafluoroethylene, and the positive electrode wet powder includes: 85%-95% pure water and 5%-15% isopropanol.

[0084] Among them, the weight percentage of polytetrafluoroethylene is the weight percentage of the positive electrode powder after molding. If 5 / 3 times of polytetrafluoroethylene emulsion is required to be added during mixing preparation, the above-mentioned proportion of polytetrafluoroethylene can be present in the positive electrode powder.

[0085] Optionally, in step S1, when mixing the positive electrode dry powder, acetylene black and ketjen black are added in a preset ratio and mixed by a mixing and stirring machine for 20 minutes to 40 minutes to obtain a uniformly mixed positive electrode dry powder. Exemplarily, the mixing and stirring time can be 20 minutes, 30 minutes or 40 minutes.

[0086] Optionally, in step S1, when adding and mixing the positive electrode wet powder, a primary mixing and a secondary mixing are required.

[0087] Specifically, the mixing of the materials once includes the following steps: 35%-45% of pure water and 5%-15% of isopropanol are stirred for about 1 minute to make them evenly mixed to obtain the first part of wet material; then the first part of wet material is added to the mixed dry powder material, and mixed for 5 minutes to 10 minutes during mixing and stirring, so that the dry powder and the wet powder are evenly mixed. Exemplarily, the mixing and stirring time can be 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes or 10 minutes.

[0088] Specifically, the secondary feeding and mixing includes the following steps: mixing and stirring the remaining 50% of the pure water and the polytetrafluoroethylene emulsion for 1 minute to make them uniformly mixed to obtain the second part of wet material; then adding the second part of wet material to the mixed material after the hesitant feeding and mixing and stirring for 5 minutes to 10 minutes to achieve complete mixing of the dry powder material and the wet powder material. Exemplarily, the mixing and stirring time can be 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes or 10 minutes.

[0089] In some embodiments, in step S1, after the positive electrode powder is evenly mixed, the positive electrode powder is sequentially dried at low temperature and high temperature, and can be formed into a uniform positive electrode powder by drying at low temperature and high temperature once.

[0090] Specifically, low-temperature drying of the positive electrode powder includes the following steps: spreading the evenly mixed positive electrode powder on a baking mesh surface with a laying height of less than 3 cm, and drying at a temperature of 55° C.-65° C. for 10 h-16 h to completely dry it.

[0091] Exemplarily, the laying height can be 1 cm, 2 cm or 3 cm; the drying temperature can be 55° C., 60° C. or 65° C.; and the drying time can be 10 h, 11 h, 12 h, 13 h, 14 h, 15 h or 16 h.

[0092] Specifically, high-temperature drying of the positive electrode powder includes the following steps: spreading the low-temperature dried positive electrode powder on a baking mesh surface with a laying height of less than 3 cm, heating it at a temperature of 190°C-210°C for 30min-60min to complete high-temperature drying.

[0093] Exemplarily, the laying height may be 1 cm, 2 cm or 3 cm; the drying temperature may be 190° C., 200° C. or 210° C.; and the drying time may be 30 min, 40 min, 50 min or 60 min.

[0094] Through a one-time drying at low temperature and high temperature, the excess material in the powder can be dried, leaving only the material required for the positive electrode to be formed into the positive electrode material.

[0095] Optionally, the low-temperature drying device and the high-temperature drying device can be the same or two. The low-temperature drying device and the high-temperature drying device can be any one of a drying box, a drying channel, etc., and only need to achieve low-temperature drying and / or high-temperature drying, which is not specifically limited here.

[0096] In some embodiments, after step S1, the process further includes: taking out the high-temperature dried positive electrode powder and soaking it in an isopropanol solution for a preset time to obtain a wet positive electrode powder. This is done to prepare for the forming of the positive electrode sheet in the subsequent step S2.

[0097] Specifically, the preset time is 20 minutes to 40 minutes, and the positive electrode powder can be wetted. Optionally, during the soaking process, the soaking temperature is controlled between 15° C. and 25° C. to achieve better soaking.

[0098] For example, the preset time may be 20 min, 30 min or 40 min. The soaking temperature may be 15°C, 20°C or 25°C.

[0099] Step S1 is followed by step S2, roller forming: the wet positive electrode powder is spread in a forming mold, and roller-pressed step by step until it is formed into a positive electrode sheet of a preset thickness and dried to form; by roller pressing step by step, the thickness of the positive electrode powder is gradually reduced until it reaches the preset thickness, and then it can be dried to form.

[0100] Specifically, the number of step-by-step rolling is 3-4 times. This arrangement allows the positive electrode sheet to be roll-formed, resulting in a higher compaction density of the positive electrode powder and avoiding the problem of damage caused by multiple rolling.

[0101] Exemplarily, the number of rolling is 3 or 4 times.

[0102] Optionally, the preset thickness of the positive electrode sheet is 1 mm-3 mm, that is, 1 mm, 2 mm or 3 mm, which can meet the preset thickness of the positive electrode member 30 of the lithium-ion battery in general demand.

[0103] Optionally, the shape of the forming mold can be set according to actual needs, or it can be directly formed into a square structure and then cut. In this embodiment, the shape of the forming mold is rectangular, so that it can be formed, and then the edge material with poor forming effect around it is cut to obtain a uniformly formed positive electrode member 30.

[0104] In some embodiments, the drying and molding of the positive electrode sheet includes the following steps: drying the positive electrode sheet at a temperature of 45°C-55°C, performing a flat pressing and shaping after drying for 2h-4h to a thickness of 1-3mm, and then continuing to dry for 10h-16h until the positive electrode sheet is completely dried, thereby achieving the molding of the positive electrode sheet.

[0105] Exemplarily, the drying temperature may be 45° C., 50° C. or 55° C.; the drying time may be 2 h, 3 h or 4 h; and the continuous drying time may be 10 h, 11 h, 12 h, 13 h, 14 h, 15 h or 16 h.

[0106] The step S2 also includes S3, post-processing: cutting and shaping the positive electrode sheet to obtain the positive electrode member 30.

[0107] Since the positive electrode sheet is first formed into a square structure and then cut, specifically, the positive electrode sheet cutting and forming method includes stamping and machining, so as to form the positive electrode member 30 of a preset size.

[0108] Optionally, the preset size is that the diameter of the positive electrode member 30 meets 20 mm-40 mm, that is, the size of the lithium-ion battery that meets conventional requirements. Exemplarily, the diameter of the positive electrode member 30 is 20 mm, 30 mm or 40 mm.

[0109] The preparation method of the positive electrode member in the present embodiment can prepare the positive electrode member 30 by sequentially performing dry powder mixing, wet powder mixing, low temperature drying, high temperature drying, infiltration, roller forming, drying, shaping, and stamping. The positive electrode member 30 is formed by powder and rolled to improve its compaction density and volume utilization, avoid partial falling of the powder in the positive electrode member 30, and improve the energy density of the lithium-ion battery.

[0110] This embodiment also provides a method for preparing a lithium-ion battery, which is used to prepare the lithium-ion battery described in any of the above solutions.

[0111] Please refer to Figure 2 and Figure 3 Specifically, the preparation method of the lithium-ion battery comprises the following steps:

[0112] Step S100, preparation work: prepare the positive electrode member 30 by the preparation method of the positive electrode member described in any of the above schemes, and prepare the negative electrode member 20, the separator 40, the shell 11 with a negative electrode current collecting net 50 at the bottom and the cover group 12 integrated with the positive electrode current collecting member 60; that is, the preparation of each structure in the above-mentioned lithium-ion battery is completed, and the assembly materials of the lithium-ion battery can be completed.

[0113] Specifically, the housing 11 and the negative electrode current collecting net 50 are assembled by spot welding the center of the negative electrode current collecting net 50 to the bottom of the housing 11 .

[0114] Specifically, the assembly method between the cap assembly 12 and the positive current collector 60 is: the connecting hole 61 in the positive current collector 60 is penetrated into the positive electrode column 122 and the two are spot welded to form.

[0115] Step S100 is followed by step S200, stacking installation: placing the negative electrode component 20, the separator 40, and the positive electrode component 30 in the accommodating cavity of the shell 11 in sequence, and pressing the negative electrode component 20 and the negative electrode current collecting net 50 together; thus, the positive and negative electrodes in the battery can be assembled.

[0116] Specifically, the negative electrode component 20 is placed on the negative electrode current collecting net 50 and flattened so that the negative electrode component 20 and the inner wall of the shell 11, as well as the negative electrode component 20 and the negative electrode current collecting net 50 are tightly arranged; then the diaphragm 40 is placed, and the positive electrode component 30 is placed in the diaphragm 40 to complete the assembly of the positive and negative electrodes.

[0117] After step S200 , the process further includes step S300 , closing the cover: pressing the positive electrode current collector 60 in the cover assembly 12 onto the positive electrode member 30 , and sealingly pressing the cover assembly 12 onto the housing 11 , thereby completing the assembly of the housing 11 .

[0118] Optionally, the cover assembly 12 and the housing 11 are pressed together and then fixed and sealed by welding.

[0119] After step S300, step S400 is also included, liquid injection and sealing: electrolyte is injected into the shell 11 through the liquid injection hole 1211 of the cover assembly 12, and the liquid injection hole 1211 is sealed by the sealing nail 124, so that the preparation of the lithium-ion battery is completed.

[0120] Optionally, the sealing pin 124 and the injection hole 1211 are fixed and sealed by welding.

[0121] The preparation method of the lithium-ion battery in this embodiment is different from the preparation of the other two types of lithium-ion batteries. It eliminates the need for other structural supports for the positive electrode powder, improves the compaction density and volume utilization of the positive electrode member 30, and thus improves the energy density of the lithium-ion battery.

[0122] The advantages of the lithium-ion battery in this embodiment are described in detail below through specific embodiments.

[0123] Example 1: ER34L65, which has a diameter of 34 mm and a height of 65 mm, and a volume of about 6.1 cm 3 , the battery has a rated capacity of 2500mAh lithium-ion battery. Specifically, in step S1, the weight ratio of the positive electrode dry powder is 8kg of acetylene black and 0.15kg of Ketjen black; the mixing and stirring time of the positive electrode dry powder is 30min; the weight ratio of the positive electrode wet powder for the first feeding is 18kg of pure water and 4kg of isopropanol; the first mixing time of the positive electrode wet powder is 1min, and the first feeding and stirring time of the positive electrode wet powder is 5min; the weight ratio of the positive electrode wet powder for the second feeding is 18kg of pure water and 3.08kg of 60% solid content polytetrafluoroethylene emulsion; the second mixing time of the positive electrode wet powder is 1min, and the second feeding and stirring time of the positive electrode wet powder is 5min; the low-temperature drying temperature of the positive electrode powder is 60℃, and the low-temperature drying time is 12h; the high-temperature drying temperature of the positive electrode powder is 200℃, and the high-temperature drying time is 30min; the preset soaking time of the positive electrode powder is 30min, and the soaking temperature is 20℃. In step S2, the preset thickness of the positive electrode sheet is 2 mm; the drying temperature of the positive electrode sheet is 50°C, the drying time is 3 hours, and the continuous drying time is 12 hours.

[0124] Specifically, the diameter of the positive electrode member 30 is 30 mm and the thickness is 2 mm. The battery shell 10 is made of stainless steel, with a wall thickness of 0.3 mm, an inner diameter of 32.5 mm and a height of 6.5 mm. The negative electrode current collector 50 is a nickel mesh with a thickness of 0.05 mm and a diameter of 31 mm. The thickness of the negative electrode member 20 is 0.15 mm and the diameter is 32 mm. The diaphragm 40 is made of glass fiber material with a thickness of 0.2 mm and a cutting diameter of 38 mm. The diameter of the cover plate 121 is 32.54 mm. The diameter of the positive pole 122 is 2 mm, and the lower end penetrates into the positive pole member 30 by 1.75 mm. The positive current collector 60 is made of nickel material, with a thickness of 0.15 mm and a diameter slightly smaller than the positive pole member 30 by 28 mm. The positive current collector 60 is 0.2 mm away from the lower end of the positive pole member 122. The insulating member 126 is made of mica, and its diameter is slightly smaller than the inner diameter of the shell 10 by 31 mm.

[0125] Comparative Example 1: ER14505, which has a diameter of 14 mm, a height of 50.5 mm, and a volume of about 7.6 cm 3 , the battery is a lithium-ion battery with a rated capacity of 2500mAh.

[0126] Please refer to Figure 4 , which gives the comparison values ​​of the actual discharge capacity and platform voltage in Example 1 and Comparative Example 1. It can be concluded that the actual discharge capacity and discharge platform voltage of the lithium-ion battery in Example 1 are higher than those in the comparative example.

[0127] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A lithium-ion battery, characterized in that: include: A shell (10), the shell (10) is in a flat cylindrical shape, a positive pole (122) and a negative pole (123) are provided on one side of the shell (10), the positive pole (122) and the negative pole (123) are insulated, and the shell (10) has a receiving cavity; A negative electrode member (20), the negative electrode member (20) having the same shape as the housing (10), the negative electrode member (20) being laid flat and electrically connected to the bottom wall of the accommodating cavity; the negative electrode member (20) being electrically connected to the negative electrode column (123); A positive electrode member (30), the positive electrode member (30) having the same shape as the housing (10), the positive electrode member (30) being insulated and covering the negative electrode member (20), the positive electrode member (30) being insulated from the cavity wall of the accommodating cavity, and the positive electrode member (30) being electrically connected to the positive electrode column (122).

2. The lithium-ion battery according to claim 1, characterized in that: It also includes a diaphragm (40), the diaphragm (40) having a bowl-shaped separation groove (41), the diaphragm (40) covering the negative electrode member (20), and the positive electrode member (30) being arranged in the separation groove (41).

3. The lithium-ion battery according to claim 1, characterized in that: The lithium-ion battery further comprises a negative electrode current collecting net (50), wherein the negative electrode current collecting net (50) is arranged on the bottom wall of the accommodating cavity, and the negative electrode current collecting net (50) is used to electrically connect the negative electrode member (20) to the bottom wall of the accommodating cavity.

4. The lithium-ion battery according to claim 1, characterized in that: The lithium sub-battery further comprises a positive electrode current collector (60), the positive electrode current collector (60) covers and is electrically connected to the positive electrode member (30), and the positive electrode current collector (60) is electrically connected to the positive electrode column (122).

5. The lithium-ion battery according to claim 4, characterized in that: A connecting hole (61) is provided in the middle of the positive electrode current collector (60); one end of the positive electrode column (122) that is insulated and sealed and extends into the accommodating cavity passes through the connecting hole (61) and abuts against the positive electrode component (30); and the hole wall of the connecting hole (61) is abutted and connected with the positive electrode column (122).

6. The lithium-substrate battery according to any one of claims 1 to 5, characterized in that: The housing (10) comprises a shell (11) and a cover group (12); the cover group (12) is sealedly connected to the shell (11) and encloses the shell (11) to form the accommodating cavity; the negative electrode column (123) and the positive electrode column (122) are both arranged on the cover group (12); and an insulating member (126) is provided on a side of the cover group (12) facing the accommodating cavity.

7. A method for preparing a positive electrode, characterized in that: A method for preparing a positive electrode member (30) for a lithium-ion battery according to any one of claims 1 to 6, wherein the method comprises the following steps: S1. Mixing preparation: Mixing dry powder and adding wet powder in sequence according to a preset ratio until the mixture is uniform, and then drying and forming to obtain positive electrode powder; S2, roller forming: spreading the wet positive electrode powder in a forming mold, and rolling it step by step until it is formed into a positive electrode sheet of a preset thickness and then dried to form; S3, post-processing: cutting and shaping the positive electrode sheet to obtain a positive electrode member (30).

8. The method for preparing a positive electrode according to claim 7, characterized in that: In step S1, after the positive electrode powder is evenly mixed, the positive electrode powder is sequentially dried at low temperature and at high temperature.

9. The method for preparing a positive electrode member according to claim 7, characterized in that: After step S1, the method further includes: taking out the positive electrode powder after high-temperature drying and soaking it in an isopropanol solution for a preset time to obtain the wet positive electrode powder.

10. A method for preparing a lithium-ion battery, characterized in that: The preparation method of the lithium-ion battery comprises the following steps: S100, preparation work: preparing a positive electrode member (30) by the method for preparing a positive electrode member according to any one of claims 7 to 9, and preparing a negative electrode member (20), a separator (40), a shell (11) with a negative electrode current collecting net (50) at the bottom, and a cover assembly (12) with a positive electrode current collecting member (60) integrated therein; S200, stacking installation: placing the negative electrode component (20), the separator (40), and the positive electrode component (30) in the accommodating cavity of the shell (11) in sequence, and pressing the negative electrode component (20) and the negative electrode current collecting net (50) together; S300, closing the cover: pressing the positive electrode current collector (60) in the cover assembly (12) onto the positive electrode member (30), and sealingly pressing the cover assembly (12) onto the housing (11); S400, liquid injection and sealing: injecting electrolyte into the housing (11) through the liquid injection hole (1211) of the cover assembly (12), and sealing the liquid injection hole (1211) with a sealing pin (124).

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