WO2003077348A1

WO2003077348A1 - A rechargeable lithium-ion power battery and manufacture method of the same

Info

Publication number: WO2003077348A1
Application number: PCT/CN2003/000170
Authority: WO
Inventors: Yongming Ju
Original assignee: Yongming Ju
Priority date: 2002-03-08
Filing date: 2003-03-07
Publication date: 2003-09-18
Also published as: AU2003221286A1; CN1320682C; CN1444303A

Abstract

A rechargeable lithium-ion power battery, each mono-cell is consisted of a cover plate, a negative pole, a safety valve, a positive pole, an electrolyte solution and a case. The positive pole is connected with the positiv- electrode, and the negative pole is connected with the negative electrode. Positive electrode substrate is selected from an aluminum foil with certain thickness, which is coated with positive active material on both sides. Negative electrode substrate is selected from copper foil with certain thickness, which is coated with negative active material on both sides. It is characterized in that an inner body of the battery is an electrode assembly which has plate-shaped structure which is composed of a positive electrode sheet, a negative electrode sheet and separator. Either the positive electrode sheet or the negative electrode sheet is shaped to a long expanded sheet with a big-leaf single tab or big-leaf multiple tabs which have different space , current flows to the poles by means of current-collecting clamp. The positive electrode has one or more electrode poles; the negative electrode has one or more electrode poles.

Description

Lithium-ion power battery capable of being repeatedly charged and discharged and manufacturing method thereof

The present invention relates to an environmentally friendly battery that can be repeatedly charged and discharged, and more particularly, the present invention relates to a lithium ion power battery that can be repeatedly charged and discharged and a method for manufacturing the same.

Background technique

Due to the requirements of environmental protection and energy saving, the world's demand for energy is more and more urgent. Therefore, it is an inevitable trend for social development and technological progress to seek efficient and clean power sources.

More than 4 studies have been involved in the field of power batteries. Currently common power batteries include lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and sodium-sulfur batteries. However, due to its low energy density, long charging time, and inability to meet the needs of high-power charging and discharging, it directly affects the practicability of these power batteries. In recent years, zinc air batteries, lithium ion batteries, and proton exchange membrane fuel cells have been considered as the best power batteries for power battery development. However, because it cannot meet the requirements of high-power charging and discharging, its practical problems have seriously hindered the practical application of power batteries.

Chinese patent application 001 01 356.4 discloses "a kind of chrome-fluoride lithium solid power battery that can be repeatedly charged and discharged". Although it is nominally a chrome-fluoride lithium solid power battery that can be repeatedly charged and discharged, its structure and composition are not fully disclosed in practice, so it has little practicality and application value, and it has not fundamentally solved high-power charging and discharging. The problem. The biggest problem of lithium-ion power batteries is the heat generated during the charging and discharging process, and the heat generated during the charging and discharging process has a great adverse effect on the lithium-ion power batteries.

Therefore, an object of the present invention is to provide a lithium ion power battery capable of being repeatedly charged and discharged, which can solve the problem of high power charging and discharging of the lithium ion power battery.

Summary of the Invention

The present invention provides a lithium-ion power battery that can be repeatedly charged and discharged. Each single battery consists of a cover plate, a negative pole, a safety valve, a positive pole, a current collector plywood, an inner body, an electrolyte, a cylindrical shape or a square shape. The outer casing is composed of the following features: The positive electrode and negative electrode groups, that is, the positive electrode sheet, the negative electrode sheet, and the separator together form an electrode assembly with a disc structure; the positive electrode post is connected to the positive electrode, and the negative electrode post is connected to the negative electrode. The poles are connected; the positive electrode is selected from a certain thickness of aluminum foil, and both sides are coated with a positive electrode active material; the negative electrode is selected from a copper foil of a certain thickness, and both sides are coated with a negative electrode active material having large leaf multipole ears and narrow rectangular pieces (also known as Shown into a piece), large leaf monopoles, large leaf multipoles are collectively called large leaf poles. Large-leaf poles can be either raised or hidden, and the current is exported to the pole through the current collector splint; the positive pole has one or several pole poles, the negative pole has one or several pole poles, The number can be equal or different, and the diameters of the poles can be equal or different.

The present invention adopts a structure with large leaf poles that can reduce the current density, which can avoid the extremely harmful heat generated in the lithium ion power battery to the greatest extent.

The invention also provides a safety valve for a lithium ion power battery that can be repeatedly charged and discharged. The compression spring is installed in the inner hole of the adjustment bolt, and the inner hole of the adjustment bolt is used to hold the compression spring and seal the steel ball. Stable, the compression spring can slide down vertically in the inner hole of the adjusting bolt, the sealing steel ball can slide down vertically in the inner hole of the adjusting bolt, and the outer diameter of the adjusting bolt is processed with a thread that matches the safety valve body The adjusting bolt is processed with several vertical exhaust grooves, and the lower part of the exhaust groove is provided with exhaust holes; the compression spring is pressed on the upper part of the steel ball, and the lower hole of the sealed steel ball is trapped on the cover injection port. The pressure relief hole at the bottom of the safety valve communicates with the injection hole on the cover.

The present invention also provides a lithium-ion power battery that can be repeatedly charged and discharged and a manufacturing method thereof, including the following steps: batching-→ coating (pulling)-→ slicing (if the tabs are directly cut, there is no Welding lugs)-→ rolling-→ making (welding) lugs-→ winding (including casing and sealing), filling-→ forming-→ dividing volume.

The invention has a uniquely designed current collecting (current collecting) terminal, that is, an inner body formed by winding positive and negative electrodes of a large leaf tab and a diaphragm at the same time, which is more sensitive to internal pressure, and thus more reliable, safe and secure. The current collecting plywood with better valve, current collecting performance and heat dissipation performance can solve the high-power repeated charging and discharging requirements of the lithium ion power battery, thereby realizing the wide application of the lithium ion power battery.

BRIEF DESCRIPTION OF THE DRAWINGS

The content of the present invention can be more easily understood with reference to the preferred embodiments in the accompanying drawings. In the drawings, the same reference numerals denote the same components, wherein: Figure 1A shows a cross-sectional view of a lithium-ion power battery using a cylindrical case;

FIG. 1B is a top view of a lithium-ion power battery with a cylindrical case;

Figure 1C shows the winding of the positive and negative pole pieces of a lithium-ion power battery with a cylindrical case;

FIG. 2A shows a top view of a lithium-ion power battery with a square case;

Figure 2B shows the winding method of the positive and negative plates of a lithium-ion power battery with a square case;

Figure 3 is a sectional view of a lithium-ion power battery with a square case; Figures 4A, 4 A-1, 4B, 4B-1, 4 C, 4 C-1 4D, and 4D-1 are large-leaf monopoles and large Schematic diagram of leaf multipole;

Figures 5 and 6 show the structure of a pressure spring type and a plate type safety valve, respectively.

detailed description

From the perspective of appearance, the basic structure of a lithium-ion power battery is shown in Figures 1A and 2A. Each unit battery consists of a cover plate 1, a negative pole 2, a safety valve 3, a positive pole 4, and an open case. 9. The inner body 7 is composed of: in the inner cavity of the lithium-ion power battery, there is a current collector plywood (also referred to as a pole piece plywood) 6, an electrolyte 8, a negative electrode piece 12, a positive electrode piece 1 3, and a separator 19. The outer casing 9, the cover plate 1, the negative pole 2, the safety valve 3, and the positive pole 4 constitute the outer body of the lithium-ion power battery; the positive and negative pole piece groups, the diaphragm, and the current collector plye constitute the inner body 7 of the lithium-ion power battery. The structure of a wound lithium-ion power battery is described in detail below.

Structure of wound lithium-ion power battery

The wound inner body 7 of a lithium-ion power battery is composed of a positive electrode, a negative electrode sheet, and a separator. The electrode assembly has a disc-shaped structure as shown in FIG. 1C or FIG. 2B. As shown in Figure 4 A, Figure 4 A-1 is a relatively narrow rectangular piece.

The positive electrode 1 3 is composed of an aluminum foil and a positive electrode active material. The aluminum foil is a thin metal foil, and both sides are coated with a positive electrode active material (either lithium cobaltate, lithium manganate or lithium nickelate, or nickel cobalt acid). Lithium). The surface of the aluminum foil is usually smooth, but the aluminum foil with a rougher surface has better adhesion for coating active materials. The suitable aluminum foil thickness ranges from 10 μm to 80 μm. When seeking 1 C ~ 2 C, exclude other influencing factors. The optimal thickness of aluminum foil is 15 μm ~ 2 5 μιη. When charging and discharging requirements are 2 C ~ 3 C or greater, exclude other influencing factors and use aluminum foil. The optimal thickness is 20 μm to 4 5 μm or more.

The negative electrode 1 2 is composed of a copper foil and a negative electrode active material. The copper foil is a thin metal foil, and both sides are uniformly coated with a collection of negative electrode active materials (either natural graphite, flake graphite, artificial graphite, or petroleum coke). Electric body. The surface of the copper foil is usually smooth, but the copper foil with a rougher surface has better adhesion for coating active materials. The suitable thickness of copper foil is 6 μ π ~ 50 μ ιη. When the charge and discharge requirements are 1 C ~ 2 C, other factors are excluded. The optimal thickness of copper foil is 8 μ ιη ~ 2 0 μ ιη; charge and discharge When 2 C ~ 3 C or more is required, other factors are excluded, and the optimal thickness of copper foil is 15 μm to 3 5 μm or more.

Neither the positive aluminum foil nor the negative copper foil should be too thick. The thickness of the metal foil (aluminum foil / copper foil) is not only related to the area of the current collector, but also to the capacitance of each single-piece pole piece. The thickness of the metal foil should be slightly thicker. Where possible, the metal foil should be as thin as possible, in order to obtain a larger electrode sheet area when applying the same amount of active material, thereby obtaining better electrical properties.

In order to reduce the weight and volume of the metal foil, as well as to increase the flexibility of the metal foil, in order to manufacture the lithium-ion power battery into a shape that can meet the needs of various forms, whether the metal foil used for the positive electrode or the negative electrode can also be separately Use wire mesh or flat mesh metal foil. The so-called flat mesh metal foil is formed by punching a number of fine small holes mechanically or chemically or by other methods on a thin aluminum or copper foil, and stretching it in the vertical and horizontal directions.

Active materials (excluding conductive agents, binders, and dispersants) of previous lithium-ion batteries accounted for about 90% of the total ingredients, and the remaining about 10% were conductive agents, binders, and dispersants. The amount of active material of the lithium ion power battery involved in the present invention is greatly increased, whether it is the positive electrode or the negative electrode, which is about 93% to 95% or even higher. The density of the positive electrode active material is 0.02 g to 0.06 g per square centimeter, and the optimal density of the positive electrode active material is 0.03 2 g to 0 · 0 4 2 g per square centimeter; Density per square centimeter is about 0. 0 1 g ~ 0. 0 3 g, the optimal density of the negative electrode active material per square centimeter is 0. 0 1 4 g ~ 0.

0 2 1 g.

The main characteristics of lithium-ion power batteries should be suitable for power applications, and they must meet the requirements of high-power charge and discharge. An important structure in the present invention is to use a large-area collector (current-collection) terminal, that is, a large leaf tab, which is more conducive to current conduction and heat dissipation, and can fully meet the requirements of high-power charge and discharge. In order to have the same name and reflect the characteristic image of the current collecting (collecting) terminal in the present invention as much as possible, the current collecting (collecting) terminal is called a large leaf tab. Those with only one pole tab on each pole piece are called large leaf monopoles, as shown in Figure 4A and Figure 4A-1, and those with several pole pieces on each pole piece are called large leaf multipole ears, as shown in Figure 4B, Fig. 4B-1; Fig. 4C, Fig. 4C-1; Fig. 4D, Fig. 4D-1.

When cutting the pole pieces, the positive and negative pole pieces should be cut into elongated pieces that conform to the process size and shape.

The size of the positive and negative electrode sheets varies due to their process requirements. Since the price of the active material of the positive electrode is much more expensive than that of the negative electrode, the length and width of the negative electrode sheet are slightly larger than those of the positive electrode when cutting. This method saves resources and gives full play to the material properties of the positive electrode, that is, the area of the positive electrode sheet is slightly smaller than that of the negative electrode sheet, and the area of the negative electrode sheet is slightly larger than that of the positive electrode sheet.

The positive electrode 1 3 and the negative electrode 1 2 are usually cut into monopole ears with large leaves (1 1 /

1 0) and scrape the slurry at the pole ears; the positive electrode 1 3 and the negative electrode 1. ,, ^

In addition to cutting, large leaf tabs can also be processed by roll cutting or shear stamping to form the pole pieces directly.

For the lithium-ion power battery with smaller capacity, the positive and negative electrodes usually have only one large leaf tab; for the lithium-ion power battery with larger capacity, there are several large leaf tabs. Therefore, when necessary, the positive and negative electrodes can also be made into large-leaf multipolar ears as shown in Figure B and Figure B-1. Thermal performance will also be better.

The width of the tabs of the large leaf tabs 1 1 for the positive electrode and the large leaf tabs 10 for the negative electrode should be as large as possible in cross-section, if possible, that is, the tabs should be as wide as possible and as wide as possible. Thick, the current collecting (collecting) path should be as short as possible, which is conducive to the extraction and heat dissipation of the current. Of course, the larger the width of the large leaf pole ears, the better it is for diversion and heat dissipation. However, if the large leaf tabs on the positive and negative electrodes are pulled out from the same direction, for example, as shown in Figures 4A and 4A-1, whether it is a large leaf monopole or a large leaf multipole, whether it is the last roll The maximum width of the large leaf tabs must be less than half (1/2) of the circumference of the stack where the large leaf tabs are located or formed.

The lugs of a larger-capacity power battery and the lugs of a smaller-capacity power battery obviously need to be wider to meet the requirements in terms of the performance of current conduction, heat dissipation, and high-rate charging and discharging.

Regardless of the cylindrical case or the square case, the pitch of the large-leaf multi-pole ears is different. Continue winding, and the pole ears on the pole pieces must be coincident at the same position in order to fit the current collector plate neatly. The distance between the large-leaf multipole ears is related to the diameter (perimeter) of the inner body 7 with a cylindrical shell, and to the circumference of the inner body 7 with a square shell. Because the inner body 7 of the wound lithium-ion power battery is wound, the perimeter of each roll is different. The perimeter of the inner roll is smaller than the perimeter of the outer roll. The pitch of the condyles is smaller than the pitch of the outer condyles.

In view of the foregoing reasons (the perimeter of each palate is different, the perimeter of the inner palate is smaller than the perimeter of the outer palate), therefore, the large-leaf multipole ear Leaf poles also vary in width. If a cylindrical shell is used, the width of the inner condyle is gradually smaller than the width of the outer condyle; if a square housing is used, the width of the inner condyle can be gradually smaller than the width of the outer condyle, or it can be the same width. .

In fact, the width of the inner condylar ear is very different from the width of the outer conical ear. Therefore, in most cases, the width of the inner condyle is equal to the width of the outer condyle. In other words, the width of the inner ear can be as wide as the width of the outer ear if the requirements are not very strict.

In general, the width of the large leaf tabs on the positive electrode 13 is the same as the width of the large leaf tabs on the negative electrode 12. Of course, the width of the respective large leaf tabs on the positive and negative electrodes can also be unequal under special requirements. For large-capacity lithium-ion power batteries, when fast high-power charging and discharging are required, the tab widths on the positive and negative electrodes should be equal. In the case of fast high-power charging without high-power discharge, the width of the large leaf tabs on the negative electrode 12 can be larger than the large leaf tabs on the positive electrode 1 3; Case, positive The width of the large leaf tab on 13 may be greater than the width of the large leaf tab on the negative electrode 12.

In general, the maximum height of the large leaf tab is usually not greater than its own (large leaf tab) width, preferably smaller than its width. Of course, the smaller the height of the lobe pole, the better. Although the position of the large leaf pole ears can be placed at will, in terms of current collecting performance, the large leaf monopole ears of the wound lithium ion power battery should be led out as far as possible from the middle of the pole piece. From the perspective of processing convenience, the large-leaf monopole ears of the wound lithium-ion power battery can be led out from the positions close to the two ends of the pole piece. That is to say, the large-leaf monopole can be drawn from the middle of the pole piece, or from the positions near the two ends of the pole piece.

The connection between the large lobe pole and the current collector can be a clear angle (that is, the connection is a right angle, an obtuse angle without an arc), or a smooth arc connection (that is, the connection has an R angle), as shown in Figure A. R in the connection of Figure A-1, not only has higher mechanical strength, but also helps to prevent the concentration of heat and cause the pole tabs to be melted or even the pole pieces to be destroyed.

Under normal circumstances, the positive and negative plates of lithium-ion power batteries use corresponding tabs, that is, when the positive electrode 1 3 uses large-leaf monopoles, and the negative electrode 12 usually uses large-leaf monopoles; the positive electrode 1 3 uses large-leaf multipoles. The ears and the negative poles 1 2 should also adopt large leaf multipole ears. In order to meet the needs of high-power charging and discharging, when the large-capacity lithium-ion power battery needs fast high-power charging and discharging, the tabs on the positive and negative electrodes should be equivalent and the number should be equal. In the case of fast high-power charging without high-power discharge, large-leaf multipole ears can be used for the negative electrode, and large-leaf monopoles can be used for the positive pole; in the case of high-power discharge without fast high-power charging, Large-leaf multipole ears can be used for the positive pole, and large-leaf monopole ears can be used for the negative pole.

The manufacturing methods of the tabs are directly cut heads 10, 11 or welded tabs. The so-called raised-ear type ears show that the ears are significantly higher than the part coated with the active material on the pole pieces, which has the advantage of being easy to scrape powder.

In addition to the raised-ear type ears, the ears shown in Figures 4D and 4D-1 are hidden-head style ears. The form of the hidden head is exactly the opposite of that of the raised head. Such Tibetan-headed large leaf pole ears 17 and 18 can more fully utilize the space of the inner cavity of the lithium ion power battery. In order to prevent the high-temperature fuse of the lithium ion power battery from melting and thinning the tabs, the tabs 1 5 and 1 6 can be made by welding as shown in Figures 4C and 4C-1. Welding of several metal pieces not only increases the mechanical strength, improves the conductivity, but also improves the heat dissipation performance. Therefore, it is best to use a welded large leaf tab for the large leaf tab. Welds 1 4 must be firm. The advantage of welding the lugs is that there is less burr on the cut pieces. The material of the tabs used for welding. The positive electrode is made of aluminum, and the negative electrode is made of nickel or copper.

The shape of the large leaf tabs can be square, rectangular, half-moon (circular), trapezoidal, or other shapes that facilitate flow and heat dissipation. The best tab shape is a trapezoid with R rounded corners at the connection.

For economic reasons, the negative electrode 12 is usually placed on the outer layer during winding. Of course, if necessary, the positive electrode 13 can also be placed on the outer layer.

The positive and negative electrode sheets must be stacked together and wound to make the inner body.

7. When the pole piece is folded inwardly, it may cause powder removal, so it should be considered to process the folding line on the pole piece inwardly folded. The active material at the fold line must be scraped off. Lithium-ion power batteries with cylindrical casings usually do not require folding lines for the positive and negative electrodes. Of course, folding lines can also be processed as needed. If a square shell is used, since the positive electrode 13 is relatively brittle and hard, the first bend has a large degree of deflection, which is easy to cause powder removal and even breakage. In order to prevent the positive electrode 13 from being powdered and broken, the folding line 20 should normally be processed at the first bend of the positive electrode sheet as shown in Fig. 4A, Fig. 4B, Fig. 4C, and Fig. 4D; Simultaneous processing of fold lines at two bends 2 0-

1. The center distance between the folding line 20 and the folding line 20-1 should meet the width of the square needle. Regardless of the width of the folding line 20 or the folding line 20-1, it should be larger than the thickness of the square curling needle.

The lithium-ion power battery with a cylindrical casing has a wound inner body 7 that is cylindrical and has a rectangular longitudinal section. The ratio of the diameter of the inner body to its height (aspect ratio), the ideal aspect ratio is 1: 2, that is, the diameter (height) is 1 and the width is

2 .

The lithium-ion power battery with a square casing has a rectangular inner body 7 after winding, and the ideal aspect ratio is 6. 2: 3. 8 or 6: 4.

The basic function of the separator is to separate the positive and negative electrodes, prevent the battery from short-circuiting, and adsorb and maintain the electrolyte. In addition to having good insulation properties, stable chemical and electrochemical properties, the separator must have a certain mechanical strength and a high electrical conductivity. Ratio, it is most suitable to use porous polyolefin materials. In view of the characteristics that lithium-ion power batteries must be charged and discharged with high power, higher safety performance is required.

The lithium-ion power battery involved in the present invention mainly uses a polyethylene separator with a thickness of 15 to 80 μm, which has a microporous structure and a low current cut-off temperature. The selection principle of the separator is as thin as possible, but when the area of the positive or negative electrode piece is less than or equal to 100 Ornm χ 500 mm and greater than or equal to 100 mm χ 50 mm, the charge and discharge requirements are 1 C ~ 2 C, Excluding other influencing factors, the optimal thickness of the separator is 25 μm to 40 μm; when charging and discharging requirements are 3C or greater, excluding other influencing factors, the optimal thickness of the separator is 4 Ομιη or more. When the battery internal temperature is higher than the limit value

(Whether it is caused by a short circuit or not). A separator with this feature will automatically close the pores, block the passage of lithium ions, and the battery will no longer react. Lithium-ion power battery The separator used can also be made of polypropylene.

The separator of the lithium ion power battery can also be directly coated with a slurry of a polyolefin-based material containing a reasonable amount of a pore-forming agent on the surface of the positive electrode sheet that has been rolled.

(You can also use the immersion method to immerse the rolled positive electrode sheet in the above slurry), and then place the positive electrode sheet in a specific solvent to extract the pore-forming agent to form a satisfactory separator integrated with the positive electrode sheet.

The separator 19 is generally made in a long shape, and the area of the separator is larger than the positive and negative electrodes no matter the length or width. Except for the ears, the separator 19 must completely shield the positive electrode 13 or negative electrode 1 2 from the periphery, and the edges must not be exposed. In case of short circuit.

The material of the lithium ion power battery pole is a metal material with excellent electrical and thermal conductivity. In addition to a certain strength, it must also have good heat dissipation performance. The pole can be cylindrical or sheet-shaped to facilitate faster heat dissipation by lithium ion power.

Under different requirements, the poles can be installed on any side surface of the lithium-ion power battery; according to different needs, the positive and negative poles can also be installed on different side surfaces of the lithium-ion power battery.

Generally, one positive pole and one negative pole of a lithium-ion power battery can meet the needs. In order to meet the needs of high-power charging and discharging, more poles of a larger-capacity lithium-ion power battery may be installed, for example, two positive poles and two negative poles may be installed at the same time. When several poles need to be installed, the number of positive and negative poles may be equal or different. In the case of fast high-power charging and discharging, the number of positive and negative poles should be equal; in the case of fast high-power charging without high-power discharge, the number of negative poles can be the same as that of the positive pole The number of poles is equal to or greater than the number of positive poles; in the case of high power discharge without fast high power charging, the number of positive poles may be equal to or greater than the number of negative poles.

The diameter of the pole can also be adjusted to meet the above needs. For example, in the case of fast high-power charging and discharging, the diameters of the positive and negative poles should be equal; in the case of fast high-power charging without high-power discharge, the negative pole The diameter of the pole can be equal to or larger than the diameter of the positive pole; in the case of high power discharge without fast high power charging, the diameter of the positive pole can be equal to or larger than the diameter of the negative pole The diameter of the pole.

Lithium-ion power batteries use multiple electrolytes to accommodate wider temperature changes. Multi-component electrolyte refers to a mixture of two or more solvents and lithium hexafluorophosphate. The lithium-ion power battery uses:

(1), LIPF 6 (lithium hexafluorophosphate) / EC (ethylene carbonate): DMC (dimethyl carbonate): DEC (diethyl carbonate), the solvent ratio is 0.9 5 to 1. 0 5: 0. 9 5 ~ 1. 0 5: 0.9 5 ~ 1. 0 5; or

(2), LIPF 6 / EC: EMC (ethyl methyl carbonate): DEC), the solvent ratio is 0.9 5 to 1. 0 5: 0.9 5 to 1. 0 5: 0.9 5- 1. 0 5; or

(3), L I P F 6 / E C: DM C: EM C, the solvent ratio is 0.9 5-1. 0 5: 0.9 5-1. 0 5: 0.9 5-1. 0 5; or

(4), LIPF 6 / EC: DMC: EMC: DEC, the solvent ratio is 0.9 5 to 1. 0 5: 0.9 5-1. 0 5: 0.9 5 to 1. 0 5: 0. 9 5 ~ 1. 0 5.

The lithium-ion power battery case according to the present invention is a part of a lithium-ion power battery, and is also called a battery case. In smaller batteries, the cell case is also one of the positive and negative electrodes. In this case, the cell case is also called the electrode case. Unless necessary by design, the cell case of high-power lithium-ion power batteries should be avoided as much as possible. Under normal circumstances, the cell shell of a high-power lithium-ion power battery cannot be an electrode shell, and the shell must be insulated from the pole. However, in special cases, the case can also become an electrode case.

The cell case of a wound lithium-ion power battery can be square (including rectangular) or cylindrical. The cylindrical shell consists of a flat surface above and below, and It consists of a cylindrical curved surface and a square shell composed of six planes. The battery cell and the cover plate are complementary. The battery case is square, the cover plate is square, the battery case is cylindrical, and the cover plate is circular.

Lithium-ion power battery cell shells have higher airtightness requirements and higher strength, usually metal shells with a certain rigidity, such as stainless steel cell shells. The cell shell of the lithium-ion power battery of the present invention can be either a metal shell, or made of polytetrafluoroethylene or polypropylene or other suitable plastics, and can be bonded or injection-molded. The safety performance is better than that of metal cells. shell.

In addition to the case of lithium-ion power batteries, in addition to rigid packaging (such as stainless steel casing), flexible packaging can also be used.

The upper or side of the shell of the lithium-ion power battery is designed and processed with plug-in ports that are convenient for series and parallel connection, so that the batteries can be connected in series or in parallel to form a battery pack.

If the heat generated by a lithium-ion power battery under working conditions cannot be dissipated in a timely manner, it will adversely affect the battery's safety and cycle life. Especially when a large number of batteries are arranged in parallel, the heat generated is greater, and the heat dissipation problem is more obvious. Therefore, a horizontal or vertical or crisscross air guide groove can be processed on the rectangular shell, which is beneficial to heat dissipation as soon as possible.

In order to dissipate heat as quickly as possible, heat sinks can be designed and processed on or inside the housing

(Thermal bridge) 9-1.

The cover of the lithium-ion power battery must match the battery case, and the airtightness is high. The cover of the lithium-ion power battery can also be made of PTFE or polypropylene or any other strong acid-resistant plastic with a certain strength and injection molding.

The safety valve 3 of the lithium-ion power battery is very important. It is a safety device provided to prevent other accidents such as overcharge and short circuit. It can instantly remove the pressure exceeding the design. The pressure relief hole at the bottom of the safety valve is also the injection port for the lithium-ion power battery.

There are two types of safety valves related to the present invention. One is a spring (compression spring type) as a reset mechanism, as shown in Figures 5-1, 5-2, 5-3, 5-4, 5-5. The anti-bow spring (pressing type) is used as the reset mechanism, as shown in Figures 6-6, 6-2, 6-3, 6-4, 6-5, 6-6. They are as follows:

The structure of the pressure spring safety valve is shown in Figures 5-1 and 5- 2. The compression spring (spring) 2 5 is installed in the inner hole of the adjustment bolt 2 3. The inner hole of the adjustment bolt is actually a retainer for the compression spring and the sealed steel ball 2 2. The compression spring can be vertically moved up and down in the inner hole of the adjustment bolt. The sliding steel ball can not swing laterally, and the sealing steel ball can also slide vertically in the inner hole of the adjusting bolt without swinging horizontally. The outer diameter of the adjustment bolt is processed with a thread matching the safety valve body 21, so the adjustment bolt is installed on the safety valve body, and the height can be adjusted at will through the key hole 27, which also serves as an exhaust. When the rotation adjusting bolt applies pressure to the compression spring, the sealing steel ball is fixed by the compression spring. The adjusting bolt is processed with a plurality of vertical exhaust grooves 2 4. Through the exhaust groove, the adjusting bolt can be rotated to rotate, and an exhaust hole 2 8 is opened at the lower part of the exhaust groove. The lowest layer is fluoro rubber 圏 26 or other corrosion-resistant rubber pads, which are pressed or attached to the liquid injection holes on the lid 1 of the lithium ion battery, and the sealed steel ball is trapped under fluoro rubber 圏 26 or other resistant materials. Corroded rubber pad. The pressure relief hole at the bottom of the safety valve communicates with the liquid injection hole on the cover plate 1, so the pressure relief hole is the liquid injection hole when the liquid is injected.

In addition, the fluorine rubber ring or other corrosion-resistant rubber pads must have some elasticity, so that when the steel ball is pressed against the fluorine rubber pad or other corrosion-resistant rubber pads, the fluorine rubber pads or other corrosion-resistant rubber pads deform The injection hole can be sealed. The compression spring is pressed against the upper part of the sealed steel ball with the inner inner part of the bottom part, and the lower part of the sealed steel ball is trapped on the fluorine rubber on the battery cover 圏 2 6 or other corrosion-resistant rubber pads to restrain the sealed steel ball from slipping. open. When the pressure inside the lithium-ion power battery is less than the set value, the sealed steel ball automatically closes the injection port due to the pressure of the compression spring to keep the inside of the battery isolated from the external environment. When the pressure inside the battery is greater than the set value, it will Automatically lift the sealed steel ball to release pressure, and the gas will be discharged from the pressure release hole 29 in an instant, and escape along the exhaust groove 2 4 along the exhaust hole 28. When the internal pressure is removed, the pressure of the compression spring is sufficient to compress the sealing steel ball again to seal the pressure relief hole.

The structure of the tablet safety valve is shown in Figure 6-1 and 6-2. The reverse bow spring piece 30 is installed at the lower part of the adjusting bolt 23, and the adjustment bolt is processed with a thread matching the safety valve body 21. Therefore, the adjustment bolt is installed on the safety valve body, and the bottom is pressed tightly on the reverse bow spring piece. Hole 8 adjusts the height of the bolt and adjusts the tension of the anti-bow spring. The safety valve body is processed with a rectangular exhaust groove 31, and the anti-bend spring is installed in the rectangular groove. It can not be rotated horizontally except it can spring up and down. The inner diameter of the lower part of the safety valve body is small, forming a cage, and the sealing steel ball 22 can be vertically moved down in the cage. The anti-bow spring is processed with a process assembly hole 33, which is crimped on the upper part of the steel ball to fix the sealed steel ball. The lower hole of the sealed steel ball is trapped on the fluoro rubber 圏 or other corrosion-resistant rubber pad on the cover injection port, which not only fixes the sealed steel ball, but also seals the battery. In addition, fluororubber or other corrosion-resistant rubber mats must have some elasticity, so that when the steel ball is pressed against the fluororubber or other corrosion-resistant rubber mats, the fluororubbers or other corrosion-resistant rubber mats will deform. The injection hole can be sealed. The compression spring is snapped on the upper part of the sealing steel ball with the inner 圏 at the bottom, and the lower part of the sealing steel ball is trapped on the fluoro rubber 圏 26 on the battery cover plate, restraining the sealing steel ball from sliding away. When the pressure inside the lithium-ion power battery is less than the set value, the sealed steel ball automatically closes the injection port due to the pressure of the compression spring to keep the inside of the battery isolated from the external environment. When the pressure inside the battery is greater than the set value, it will The pressure of the sealed steel ball is automatically lifted to release pressure, and the gas is instantly discharged from the pressure relief hole 29, and escapes from the exhaust hole 32 and the key hole 27 along the exhaust groove 31. When the internal pressure is removed, the pressure of the anti-bow spring is sufficient to compress the sealing steel ball again to seal the pressure relief hole.

The fluorine rubber ring 26 may be replaced by any other suitable rubber.

The anti-bow shrapnel can be designed and processed into a flat shape or a half-moon shaped anti-bow shrapnel as shown in Figure 6-1. The working principle of the flat anti-bow shrapnel is the same as that of the half-moon anti-bow shrapnel.

The pressure of the tablet-type safety valve can also be adjusted by the screws 3 4 shown in Figure 6-2.

In order to evacuate more quickly, the safety valve can also be designed with several vent holes 3 5 in the body.

The pressure relief hole 2 9 on the fluorine rubber 圏 2 6 and the liquid injection hole on the cover plate 1 are communication holes and also communicate with the pressure relief hole on the bottom of the safety gang, so they are not marked separately.

Regardless of the pressure spring type safety valve or the pressure plate type safety valve, the sealed steel ball 2 2 can be designed and processed into a ball 2 2-1 with horizontal transverse grooves, and the fluorine rubber 圏 2 6-1 is hung on the sealed steel ball. 2 2-1 in the horizontal slot. When the compression spring or reverse bow spring presses down the sealing steel ball 2 2-1, the fluorine rubber 圏 2 6-1 seals the injection hole. In order to prevent the sealed steel ball 2 2-1 from swinging, a fixed small handle 3 5 can also be processed thereon, and a compression spring or an anti-bow spring is sleeved on the fixed small handle. When the internal pressure is less than the allowable value, the compression spring or reverse bow spring presses the sealing steel ball 2 2-1 and the fluorine rubber 圏 2 6-1 tightly seals the injection hole. When the internal pressure is higher than the allowable value, the sealed steel ball 2 2-1 is lifted, and the fluoro rubber 圏 2 6-1 is lifted upwards at the same time, and the internal pressure is quickly released.

The sealing steel ball 2 2 can also be designed and processed into a sealing frustum 2 2-2. Compared with the steel ball 2 2 or 2 2-1, the lower part of the sealing frustum protrudes into the injection hole, so Bit more reliable. The sealing frustum can also be processed with a fixed small handle 3 6, and a compression spring or an inverse bow spring is sleeved on the fixed small handle. When the internal pressure is less than the allowable value, the compression spring or reverse bow spring presses the sealing frustum 2 2-2, and the pressure of the fluorine rubber 圏 26 in the sealing frustum deforms to tightly seal the injection hole. When the internal pressure is greater than the allowable value, lift the sealing cone 2 2-2 and quickly remove the internal pressure. The sealing frustum can also be designed and machined as 2 2-3, which has a horizontal horizontal groove, and the fluoro rubber 圏 2 6-1 is hooped in the horizontal horizontal groove on the sealing frustum 2 2-3. When the compression spring or reverse bow spring presses down the sealing cone 2 2-3, the fluorine rubber 圏 2 6-1 seals the injection hole. When the internal pressure is larger than the permissible value, when the sealing cone 2 2-3 is lifted up, the fluorine rubber 圏 2 6-1 is lifted upward at the same time, and the internal pressure is quickly released.

The sealing steel ball 2 2 or 2 2-1 or the sealing frustum 2 2-2, 2 2-3 can also be designed as a hollow sleeve, and the compression spring is inserted into a hollow sleeve with better guiding performance. in.

Generally, the safety valve and the pole should be installed on the same side surface of the lithium-ion battery case, but they can also be installed on different side surfaces as required.

According to different needs, safety valves and poles can be installed on any side surface of the lithium-ion power battery.

For safety, a large-capacity lithium-ion power battery may have several safety valves installed on the same side surface or on different side surfaces.

Proportion of active substance (slurry) and its preparation method

In the production process of lithium-ion batteries, the preparation (batching) process and coating process are extremely critical, and have the greatest impact on the electrical performance of lithium-ion power batteries.

Preparation of paddle materials. The medium for preparing the slurry includes NM P (N-methyl-2 -pyrrolidone) as the medium or water (deionized water, distilled water, purified water) as the medium; the preparation methods include wet method and dry method. In the description of the present invention, according to the medium, the NMP medium is described first, and then the water medium is described. In accordance with the preparation method, the wet method is first described (there are also wet methods: sequential preparation method and mixed preparation method), and then the dry method is described. (Positive). It is described below:

positive electrode. Use NM P as the medium. Materials required: PVDF (polyvinylidene fluoride) 2.5% ~ 3.5%, lithium cobaltate 93% ~ 95%, conductive agent graphite 1% ~ 2% (or acetylene black 0.5% ~ 1%), carbon black 2% ~ 3%. The amount of NMP is affected by the particle size and particle size of the foregoing substances, especially lithium cobaltate. Restriction on distribution, so it is about 30% ~ 100% of the total amount of all the aforementioned substances, that is, the solid-liquid ratio = 1 (active substance solid content): 0.3 ~ 1 (NM P); usually, the best的 solid-liquid ratio = 1: 0.3 5 to 0.7. PVDF, graphite (or acetylene black), and carbon black all need to be about 120. C Bake in an oven for about 2 to 3 hours.

Sequential preparation method. After adding PVDF to NMP and stirring for about 3 to 4 hours, add conductive agent graphite (or acetylene black), carbon black and stir for about 0.5 to 1 hour, and finally add lithium cobaltate and stir for about 2.5 to 4 hours to become viscous. Pasty.

Mixed formulation method. Add P V D F to NM P and stir for about 3 to 4 hours. Add conductive agent graphite (or acetylene black), carbon black, and lithium cobaltate and stir for about 2.5 to 4 hours to form a thick paste.

positive electrode. Use water as the medium. Required materials: CMC (sodium carboxymethyl cellulose) 0.6% ~ 0.9%, SBR (styrene-butadiene latex emulsion) actual solid content 2% ~ 4%, conductive agent graphite 1% ~ 2% or acetylene black 0.5% to 1%, carbon black 1.5% to 3%, lithium cobaltate 93% to 95%. The amount of water (deionized water, distilled water, purified water) is limited by the particle size and particle size distribution of the aforementioned substances, especially lithium cobaltate, so it is about 40% ~ 130% of the total amount of all the aforementioned substances. Liquid ratio = 1: 0. 4 ~ 1 · 3; Under normal circumstances, the best solid-liquid ratio = 1: 0.6 ~ 1. S B R can be replaced with P T F E (polytetrafluoroethylene).

Sequential preparation method. CMC is added to the water and stirred for about 3 to 4 hours, then SBR is added to it and stirred for about 0.5 to 1 hour, and then conductive agent graphite (or acetylene black) and carbon black are added and stirred for about 0.5 to 1 hour, and finally cobalt is added. The lithium acid is stirred for about 2.5 to 4 hours to form a thicker slurry. Sieve out agglomerates and other impurities.

Mixed formulation method. First add CMC to water and stir for 3 ~ 4 hours, then add SBR and stir for about 0.5 ~ 1 hour, and then add conductive agent graphite (or acetylene black), carbon black, lithium cobaltate and stir for about 2.5-4 It will become a thicker paste when it is small, and finally it will agglomerate and other impurities.

In view of the fact that lithium ion power batteries need to meet their high rate charge and discharge characteristics, the preparation of the positive electrode must be slightly larger than the conductive agent.

negative electrode. Use NMP as the medium. Materials required: Graphite 93% ~ 95% PVDF 5% ~ 7%, NMP is about 8% of the total amount of all the aforementioned substances 0% ~ 15 0% is the solid-liquid ratio-1: 0 ■ 8 ~ 1. 5; the optimal solid-liquid ratio = 1: 1 ~ 1.3. PVDF needs a temperature of about 120. B oven in C oven for 2 ~ 3 hours, graphite needs to be baked at 300 ° C ~ 500 ° C for 4 ~ 8 hours.

Sequential preparation method. Add P V D F to NM P and stir for about 3 to 4 hours. Then add the graphite that has been sifted through a 3 2 5 mesh screen and stir for about 3 to 4 hours to form a thick slurry.

negative electrode. Use water as the medium. Materials required: Graphite 93% ~ 95%, CMC 0.9% ~ 1.5%, SBR solid content 2% ~ 4%, water (deionized water, distilled water, purified water) is about the total of all the aforementioned substances The solid-liquid ratio of 80% ~ 160% of the amount = 1: 0.8 ~ 1.6; under normal circumstances, the best solid-liquid ratio = 1: 1 ~ 1.3. C M C needs to be 1 2 0. Baking at 2 ° C to 3 ° C, graphite needs to be baked at 300 ° C ~ 500 ° C for 4 ~ 8 hours. S B R can be replaced by P T F E.

Sequential preparation method. Add CMC to water and stir for about 3 to 4 hours, then add SBR to it and stir for about 0.5 to 1 hour. Finally, add graphite after baking and sieving through 300 mesh. Stir for about 3 to 4 hours to become viscous. Pasty.

Dry preparation. Dry preparation of the positive electrode with N M P as the medium. Materials required: Materials required: PVDF 2.5% to 3.5%, lithium cobaltate 93% to 95%, conductive agent graphite 1.5% to 2% (or acetylene black 0.8% to 1 .

2%), carbon black 2% ~ 3%. The amount of N M P is limited by the particle size and particle size distribution of the foregoing materials, especially lithium cobaltate, so it is about the total amount of all the foregoing materials.

30% ~ 100% means the solid-liquid ratio = 1 (solid content): 0.3 ~ 1 (N M P), under normal circumstances, the best solid-liquid ratio-1: 0.3. 5 ~ 0.7. P V D F, graphite (or acetylene black), and carbon black all need to be baked in an oven at about 120 ° C for 2 to 3 hours.

First put lithium cobaltate, conductive agent graphite (or acetylene black), carbon black into the mixer and stir for 3 hours; at the same time, stir PVDF and NMP for about 2 hours. After it is completely dissolved (slurry), it will be mixed The mixed powder after the machine is stirred is put into the clear slurry of PVDF and NM P after stirring, and then stirred for about 3 hours to form a thick slurry.

Dry preparation of the positive electrode with ice as the medium. Materials required: CMC 0.6% ~ 0.9%, SBR actual solid content 2% ~ 4%, conductive agent graphite 1 % To 2% or acetylene black O. 5% to 1%, carbon black 1.5% to 3%, lithium cobaltate 93% to 95%. The amount of water (deionized water, distilled water, purified water) is limited by the particle size and particle size distribution of the aforementioned substances, especially lithium cobaltate, so it is about 40% ~ 130% of the total amount of all the aforementioned substances. Liquid-to-liquid ratio = 1: 0.4-1.3; In general, the optimal solid-to-liquid ratio = 1: 0.6 ~ 1. SBR can be replaced with PTFE (polytetrafluoroethylene).

First put lithium cobaltate, conductive agent graphite (or acetylene black), carbon black into the mixer and stir for about 3 hours; at the same time, stir the CMC with water for about 3 hours. After it is completely dissolved, it will become a clear slurry. The mixed powder after being stirred by the machine is put into the clear slurry of the stirred CMC and water and stirred for about 3 hours to form a thick slurry. Finally, the agglomerates and other miscellaneous shields are sieved.

In the preparation of the positive electrode, it is necessary to pay attention to the selection of the conductive agent, and the particle size of the conductive agent must be equal to or smaller than the positive electrode material (lithium cobaltate, lithium manganate, lithium nickel cobaltate).

In order to ensure the quality of the prepared slurry, whether the water (deionized water, distilled water, purified water) or NMP is used as the medium during the preparation of the slurry, it must be based on the particle size, particle size distribution, and conductive agent of the positive electrode material. The amount is carefully calculated, and the medium is added once and cannot be added halfway. The same is true for the negative electrode, whether it is water (deionized water, distilled water, purified water) or NMP as the medium, it must be based on the anode material. And the amount of additives is finely calculated, and the medium should be filled in one time. Do not add it halfway. Otherwise, it is difficult to ensure the quality of the positive electrode slurry or the negative electrode slurry.

In addition to the lithium cobalt oxide, the active material used for the positive electrode of the lithium-ion power battery can also be lithium manganate, lithium nickelate, or lithium nickel cobaltate. The preparation method is basically the same as that of the foregoing lithium cobaltate preparation method.

The particle size of the lithium ion battery positive electrode material (lithium cobaltate, lithium manganate, lithium nickelate, or lithium nickel cobaltate) can be selected in the range of 2 μm to 12 μm, but the optimal particle size should be 5 μ m ~ 8 μ m; The particle size distribution of the cathode material must also be as narrow as possible. Taking 5 μm particle size as an example, too fine (less than 2 μm) or too thick (more than 12 μm) powder The total is usually not more than 40%.

Cathode material (lithium cobaltate, lithium manganate, lithium nickelate, or lithium nickel cobaltate) Preparation method of fine powder below 2 μm, coarser powder above 1 μm and 2 μm ~ 1 2 μ The preparation method in the range of m is the same except that the solid-liquid ratio is different. The solid-liquid ratio of fine powders below 2 μm should be increased by 20 from the original solid-liquid ratio. % ~ 50%, the solid-liquid ratio of coarser powders above 12 μm should be reduced by 10% ~ 30% based on the original solid-liquid ratio.

The anode material graphite is screened by 300 mesh vibration, and the remaining ones on the Internet are usually not suitable for use. The conductive agent involved in the present invention includes graphite, acetylene black, carbon black, etc .; except that graphite is used as a negative electrode material for high-temperature treatment (300 to 500 ° °), the rest is baked. The material can be placed in a vacuum box for vacuum treatment without the need for high temperature treatment.

Production method

The production process of the lithium-ion power battery is as follows: ingredients-→ coating-→ tableting-→ rolling-winding and assembling into the inner body (including casing and sealing)-→ filling-→ chemical conversion-→ volumetric.

Each process is described below.

The batching process has been described in detail above, and will not be repeated here.

Coating (also known as drawing pulp). There is no difference between the coating of the positive electrode and the coating of the negative electrode, so they are not described separately: The stirred positive electrode (or negative electrode) slurry is hook-coated on the metal foil current collector, pulled out by a roller knife into the oven and dried. After baking, it will become semi-finished current collector after baking. Care must be taken during coating to avoid scratches, exposed substrates, lightness and weight in the vertical and horizontal directions.

In the coating process, the temperature control is very important: the temperature of the preheating section should not be too high, usually the temperature is selected at 90 ° C or below, and the temperature of the intermediate temperature section is between 1 10 ° C ~ 1 3 0 ° Between C, ± 10 ° C, the temperature in the high-temperature section is 120. C ~ 1 4 0. Between C, ± 10. C. Under the aforementioned temperature conditions, the temperature of the negative electrode slurry can be slightly higher than the temperature of the positive electrode slurry by about 10 to 15 "C during coating and baking, and the temperature of the slurry using water as the medium can be higher than that of NMP as the medium. The temperature of the slurry is slightly higher than about 10 ~ 15 ° C.

After the prepared slurry is coated on the metal foil, both the positive electrode and the negative electrode must enter the drying tunnel of the coating machine (also known as the puller) from the preheating section, and must not be inverted. If the slurry (especially the negative electrode slurry) first enters the high-temperature section of the coater and bakes suddenly at high temperature, the surface is dried quickly, and it is easy to form a dry shell, which is slightly wrinkled, which will form cracked fine lines. The slurry under the dry shell is sugar-smeared and forms a liquid film invisible to the naked eye between the metal foil. The slurry is actually virtually attached to the surface of the metal foil, so it is easy to remove powder and even flakes ( (Ie, large pieces of active material fall off the metal foil), which seriously affects the electrical performance of lithium-ion power batteries. Current coating The cloth process is mostly coated on one side and then coated on the other side; however, it can also be coated on both sides simultaneously. The positive and negative electrode sheets to which the present invention is applied may be coated with active materials on both sides of the metal foil, or may be coated with active materials only on one side of the metal foil. The back surface (metallic surface without active material coating) can be attached to form a current collector with active materials on both sides. In this case, the thickness of the metal foil used for single-sided coating must be thinner than the thickness of the aforementioned metal foil, which is about 1/2 to 1/3 of the thickness of the aforementioned metal foil.

Line speed control in the coating process is also important. Under the above temperature conditions, the linear speed can be adjusted within the range of 800mm to 500 Omm per minute. The best linear speed is 1200mm ~ 3500mm per minute.

In addition to coating, which can be used to produce pole pieces of lithium-ion power batteries in the traditional drawing method, high-pressure spraying can also be used. Under a certain pressure of the dry protective gas, the slurry is sprayed evenly on the metal foil from the high-speed nozzle, which not only has better adhesion, but also significantly increases the production capacity.

Production. Making (welding) the lugs, if the lugs are cut directly, there is no process of making the welding lugs. Cutting the pole pieces can be done with a shears, a slitter or other equipment.

Roll. The role of rolling in the production process of lithium-ion power batteries cannot be ignored. Excessive line pressure not only causes pole pieces to deform, but also impedes the penetration of the electrolyte and affects the insertion and extraction of lithium ions. It will eventually affect the high-power charge and discharge performance of lithium ion power batteries. If the line pressure is too small, it will affect active materials. Adhesion to metal foil affects electrical performance. The more moderate line pressure of the positive electrode is about 100 ~ 180kg / C M, and the negative electrode is about 80 ~ 160kg / C M.

Under normal circumstances, the thickness of the positive electrode before rolling is about 170 μm to 270 μm, the thickness of the positive electrode after rolling is about 110 μm to 165 μm, and the thickness of the negative electrode is about 185 μm to 275 μ m, 110 μ π ~ 165 μ π after rolling. The optimal thickness of the positive electrode before rolling is 195 μm ~ 235 μ01, and the optimal thickness of the positive electrode after rolling is 135 μπι ~ 155 μm; the optimal thickness of the negative electrode before rolling is 220 μπι ~ 250 μ ιη, The optimal thickness after rolling is 135 μ m ~ 155 μ ηι.

Coiled. When assembling, a pair of positive and negative electrode groups must be neatly stacked (with a separator in the middle) and wound with a suitable and even tension on the winding pin. After winding, clamp the positive and negative electrodes separately Ears. There are two kinds of winding needles. The rolling pin of the inner body 7 of the shaped shell is a small cylindrical shaft as shown in FIG. 1A, and the rolling pin of the inner body of the square shell shown in FIG. 2A is a thin sheet with certain rigidity and elasticity.

Multiple pairs of positive and negative electrode groups can also be neatly stacked in parallel and wound at the same time. When winding, the positions of the positive and negative ears must be staggered. After winding into the inner body 7, the positive and negative ears can be neatly listed as the positive and negative poles shown in Figures 1A and 2A.

When winding, please also note that if there is a folding line on the positive electrode 13, the front end of the negative electrode 12 should be aligned with the center line of the folding line of the positive electrode 13 so that it cannot puncture the diaphragm 19.

After winding the inner body in the assembled state, excluding the thickness of the separator 19, the distance between the positive electrode and the negative electrode must not be greater than 25 μm (the maximum gap between the positive electrode and the negative electrode = the thickness of the separator + 2 5 μm).

When winding, the positive and negative electrodes must be staggered, and the distance between the positive electrode 1 3 and the first electrode of the negative electrode 12 must be reasonably calculated, so that the positive electrode tabs 11 on the wound inner body 7 happen to be neat and neat. The parallel arrangement is parallel to one end of the inner body, and the negative electrode tab 10 happens to be neatly arranged parallel to the other end of the inner body. The outermost layer of the inner body 7 may be either a negative electrode sheet or a positive electrode sheet.

There is usually only one inner body 7 in the outer shell of a wound lithium-ion battery. In order to meet the processing requirements, several inner bodies can be installed in parallel in a casing 9 of a wound lithium-ion power battery to form a large-capacity lithium-ion power battery.

It must be noted that the positive electrode pole 4 is connected to the positive electrode sheet 1 3, and the negative electrode pole 2 is connected to the negative electrode sheet 12.

In order to clamp the tabs, whether the integral current collecting splint or the split type current collecting plywood, the surface of the current collecting plywood in contact with the tabs is processed with raised spines. In general, the coverage of the current collector plywood should be larger than the large leaf tab. The method of clamping is also divided into perforated clamps and two-sided clamps. The integrated current collector ply is cut on a solid metal into several wire grooves that can be compressed and can be springed off. The pole ears are inserted into the wire grooves of the current collector ply A or D and fastened with metal bolts 5. The split-type current collecting plywood B or C is connected in series by a plurality of independent metal pieces through a series rod 2 Q, and the tabs are respectively clamped and fastened with metal bolts 5. The integrated current collector plywood can be perforated or double-sided. Similarly, the split current collector plywood can also be perforated or double-sided. From efficiency As far as the effect is concerned, the efficiency and effect of the perforated clip are better than the two-sided clip.

In order to prevent the bolts connecting the pole ears and poles from loosening, the bolts need to be fixed with curing glue.

Inject fluid. Before injection, the normal air in the inner cavity of the lithium ion power battery must be drawn out. Except for the moisture in the inner cavity, the inner cavity of the battery must be in a negative pressure state, and then an appropriate amount of electrolyte is injected from the safety valve port. The injection volume of a lithium-ion power battery must be calculated based on its capacity. If the injection volume is too large, it will easily leak and cause the drum shell. If the injection volume is too small, it will easily cause the deterioration of the positive and negative electrode active materials. The injection volume of lithium ion power battery is usually adjusted within the range of 0.1 5 Ah / g ~ 0.6 Ah / g; the optimal injection volume is 0.2 Ah / g ~ 0.3 5 Ah / g between. The environmental control of the injection is very important, so the injection must be completed in the operation box or other environment that can meet the requirements. Because the pressure relief hole of the safety valve communicates with the liquid injection hole on the cover plate, the injection liquid is usually injected from the pressure relief hole of the safety valve; the liquid injection hole can also be processed on the housing or the cover plate separately.

After the lithium-ion power battery is installed in the inner body and filled with liquid, a certain cavity should still be maintained. In order to reduce the volume or save the shell material, the internal cavity of the lithium-ion power battery must be intentionally filled with solid substances or electrolyte. Depending on the capacity of the lithium-ion power battery, the cavity is about 1% to 10% of the total volume of the internal cavity. The cavity can be filled with a protective gas.

Formation is the last key to battery production. The formation principle of high-power lithium-ion batteries must be low current and low voltage. High current must not be formed. Higher voltage formation is required to fully activate the active materials on the positive and negative current collector substrates. The formation process must be completed uninterrupted at one time, and it cannot be stopped or stopped at will. The formation curve should be smoothly connected, and the current should be controlled between 0. 0 1 C / 10 hours-→ 0. 2 C / 5 hours-— 0. 0 5 C / 5 hours-→ 0. 1 C / 4 hours-→ 0.2 C / 1 hour, after the constant current is full, it will be switched to constant pressure to continue charging, so as to ensure sufficient one time.

Divide. Put batteries with electrical performance indicators that meet the process requirements and batteries with electrical performance indicators that do not meet the process requirements, respectively.

The lithium ion power battery manufactured by this method can not only meet the requirements of high-power charge and discharge, but also avoid the problem of heat accumulation inside the power battery.

Claims

Rights request

1. A lithium-ion power battery that can be repeatedly charged and discharged. Each single battery is composed of a cover plate (1), a negative pole (2), a safety valve (3), and a positive pole.

(4), electrolyte (8), and casing (9), the positive pole (4) is connected to the positive pole (1 3), and the negative pole (2) is connected to the negative pole (1 2); the positive pole (1) 3) Select a certain thickness of aluminum foil and evenly coat the positive electrode active material on both sides, and the negative electrode (1 2) Select a certain thickness of copper foil and evenly coat the negative electrode active material on both sides; It is characterized by: the inner body (7) is A plurality of pairs of positive and negative electrode groups, that is, a positive electrode sheet (1 3), a negative electrode sheet (1 2), and a separator (1 9) together form an electrode assembly having a disc-like structure; Rectangular slice of leaf monopole or large leaf multipole and pass through current collector splint

(6) exporting the current to the poles; the positive pole has one or several pole poles, and the negative pole has one or several pole poles; the number of the positive pole poles and the negative pole poles can be equal or different, and the diameters of the pole poles can be equal or different; In addition to the shape of the pole, the shape of the pole can also be cylindrical, and it can be mounted on the same or different surface of the casing (9). The shape of the positive and negative electrodes can be made into other shapes besides the rectangular shape. sheet

(1 3) and the negative electrode sheet (1 2) must be stacked and spaced apart; the inner body (7) can be either the negative electrode sheet or the positive electrode on both sides of the outermost layer; the inner body (7) must be tightly wrapped with a separator or Clamped with polyethylene and polypropylene frames; positive pole tab (1

1) neatly arranged in parallel and connected to one end of the inner body (7), negative pole tab (1 0) neatly arranged and connected in parallel to the other end of the inner body; positive electrode (1 3) or negative electrode (1

2) A mesh metal foil may be selected separately; the active material of the positive electrode (1 3) may be lithium cobaltate, or lithium manganate, lithium nickelate, or lithium nickel cobaltate; the negative electrode (1

2) The active material can be either natural graphite, flake graphite, artificial graphite, or petroleum coke; the shell (9) can be either square or cylindrical; the shell (9) is usually filled with only one The main body (7), or a plurality of inner bodies may be installed in parallel in the casing to form a large-capacity power battery.

The lithium ion power battery capable of being repeatedly charged and discharged according to claim 1, characterized in that: the density of the positive electrode (1 3) active material is 0.02 g-0.06 g per square centimeter, preferably 0.032 g-0.042 g The density of the negative electrode (1 2) active material per square centimeter is about 0. Olg ~ 0.03g, preferably 0.014g ~ 0.021g _o

The lithium ion power battery capable of being repeatedly charged and discharged according to claim 1, characterized in that: the maximum width of the large leaf tabs must be less than half of the circumference of the stack where the tabs are located or formed; Shaped outer shell, the inner body (7) the width of the inner leaflet's large leaf tabs should be gradually smaller than the width of the outer palate poles or the same width; using a square shell, the inner leaflet's large leaf tabs can be gradually smaller than the outer The width of the 圏 pole ears can also be the same width; whether the cylindrical shell or the square shell is used, the spacing of the large leaf multipole ears is different; the large leaf monopole ears can be led out from the middle of the pole piece, or from two close to the pole piece. The end of the large leaf tab can be cut directly, the large leaf tab can be made separately and welded to the pole piece after the pole piece is rolled, it is best to use the large leaf tab; the shape of the large leaf tab can be It is square, rectangular, semi-circular, trapezoidal, or other shapes that are good for flow guidance and heat dissipation. The best shape is a trapezoid with an R angle. The connection between the root of the ear and the pole piece can be either a clear angle connection or Light Sliding arc connection; the positions of the large leaf tabs of the positive electrode (13) and negative electrode (12) must be staggered and wound. Neatly arranged in parallel to the other side of the inner body; the outermost layer of the inner body (7) can be either a negative electrode sheet or a positive electrode sheet.

The lithium ion power battery capable of being repeatedly charged and discharged according to claim 1, characterized in that: in general, the maximum height of the large leaf tab is not larger than its own width, and preferably smaller than its width.

The lithium ion power battery capable of being repeatedly charged and discharged according to claim 1, characterized in that: the integrated current collecting plate has a plurality of wire grooves which can be compressed and can be opened; the split type current collecting plate is formed by Several independent metal pieces are connected in series through a series rod (20); whether the integrated current collector plywood or the split current collector plywood, the current collector plywood should cover the tabs, and the surface in contact with the tabs has raised thorns .

The lithium ion power battery capable of being repeatedly charged and discharged according to claim 1, characterized in that: the separator (19) is made of a microporous structure with a low current cut-off temperature of 15 μm to 80 μm. The strip (19) is made of polyethylene or polypropylene material; the area of the separator (19) is larger than the positive and negative electrodes no matter the length or width. Except for the ears, the separator (19) must have the positive electrode (1 3) Or the negative electrode (1 2) is completely shielded around, and the edges must not be exposed to prevent short circuit. When the charge and discharge require 1 C ~ 2 C, the optimal thickness of the separator (1 9) is 2 Ομ ιη ~ 4 0 μm; When charge and discharge require 3 C or more, the optimal thickness of the separator is 40 μm or more.

7.—A safety valve for a lithium ion power battery that can be repeatedly charged and discharged, characterized in that: a compression spring (2 5) is installed in an inner hole of an adjustment bolt (2 3), and the inner hole of the adjustment bolt is used for holding Stability of compression springs, sealed steel balls (2 2), compression springs

(2 5) It can slide down vertically in the inner hole of the adjusting bolt to seal the steel ball (2

2) It can be slid up and down in the inner hole of the adjustment bolt. The outer diameter of the adjustment bolt is machined with threads that match the safety valve body (2 1); the adjustment bolt is machined with several vertical exhaust grooves (2 4) There are vent holes (2

8); the compression spring (2 5) is pressed on the upper part of the steel ball, and the lower hole of the sealed steel ball (2 2) is trapped on the fluorine rubber 圏 (2 6) on the injection port of the cover plate; The pressure hole communicates with the liquid injection hole on the cover plate (1); the pressure spring (25) can also be replaced by a reverse bow spring (30), and the reverse bow spring (30) is installed on the adjusting bolt (2)

3) The lower part of the adjusting bolt is processed with a thread matching the safety valve body (2 1), and the tension of the reverse bow spring is adjusted by turning the key hole (2 7); a rectangular exhaust groove (3 1), the anti-bow spring (3 0) can be bounced up and down in the exhaust slot and cannot be rotated horizontally; the sealed steel ball (2 2) can be vertically lowered in the holder of the safety valve body, and the anti-bow spring (3) 0) Process assembly holes (3 3) are machined on the top of the steel ball to seal the steel ball

The lower hole of (2 2) is trapped on the fluorine rubber 圏 (2 6) on the injection port of the cover plate; the pressure relief hole at the bottom of the safety valve communicates with the injection hole on the cover plate (1); the safety valve body ( 2 1) can be separately processed with exhaust holes (3 5); sealed steel balls can be processed into spheres with horizontal horizontal grooves (2 2-1), fluoro rubber 圏

(2 6-1) hoop tightly in the horizontal horizontal groove on the sealing steel ball (2 2-1); the sealing steel ball (2 2) can be processed into a sealing frustum (2 2-2); sealing frustum

(2 2-3) can process a horizontal horizontal groove, fluoro rubber 圏 (2 6-2) is hooped in the horizontal horizontal groove on the sealing pedestal (2 2-3); the safety valve can be installed in the housing (9 ) On any surface; a large-capacity lithium-ion power battery can install several safety valves on the same side surface or different side surfaces; usually, the safety valve (3) and the pole can be installed in the housing ( 9) can be installed on different surfaces on the same surface.

8. A method for manufacturing a lithium ion power battery that can be repeatedly charged and discharged, characterized in that it includes the following steps (1) Ingredients, including the following methods:

A. The sequential preparation method is used to prepare the positive electrode slurry with NM P as the medium. The required materials are: PVDF (polyvinylidene fluoride) 2 · 5% ~ 3 · 5%, lithium cobaltate 9 3%-95% 1, graphite conductive agent 1% ~ 2% or acetylene black 0.5% ~ 1%, carbon black 2% ~ 3%; the amount of NMP is limited by the particle size and particle size distribution of lithium cobaltate, usually solid-liquid Ratio = 1 (solid content): 0.3-1 (NM P); optimal solid-liquid ratio-1: 0.3 to 5; 0.7; PVDF, graphite (or acetylene black), and carbon black all need to be in Bake in an oven at about 120 ° C for about 2 to 3 hours; add PVDF to NMP and stir for about 3 to 4 hours, then add conductive agent graphite (or acetylene black), carbon black and stir for about 0.5 to 1 hour, and finally Add lithium cobaltate and stir for about 2.5 to 4 hours to form a thick paste;

A-2. The positive electrode slurry with water as the medium is prepared by the sequential preparation method. The required materials are: CMC 0 · 6% ~ 0 · 9%, SBR actual solid content 2% ~ 4%, conductive agent graphite 1% ~ 2% or 0.5% ~ 1% of acetylene black, 1.5% ~ 3% of carbon black, 93% ~ 95% of lithium cobaltate; the amount of water (deionized water, distilled water, purified water) is all 40% ~ 130% of the total amount of the aforementioned substances, that is, the solid-liquid ratio = 1: 0.4 to 1.3; under normal circumstances, the best solid-liquid ratio = 1: 0.6 to 1; SBR can be used 5 ~ 1 hour, add CMC to water and stir for about 3 to 4 hours, then add SBR to it and stir for about 0.5 to 1 hour, and then add conductive agent graphite (or acetylene black) and carbon black for about 0.5 to 1 hour, Finally, add lithium cobaltate and stir for about 2.5 to 4 hours to form a thicker slurry. Sieve out agglomerates and other impurities;

A-3. Dry preparation of positive electrode slurry with NM P as the medium, the required materials are: PVDF 2.5% ~ 3.5%, lithium cobaltate 93% ~ 95%, conductive agent graphite 1. 5% ~ 2% (or acetylene black 0.8% ~ 1.2%), carbon black 2% ~ 3%, the amount of NMP is limited by the particle size and particle size distribution of lithium cobaltate, which is the total amount of all the aforementioned substances 35% ~ 90% of the solid-liquid ratio = 1 (solid content): 0.3 ~ 1, the optimal solid-liquid ratio = 1: 0.3 5 ~ 0.7; PVDF, graphite (or acetylene black) ), Carbon black are required to be about 120. (: Baking in an oven for 2 to 3 hours; Put lithium cobaltate, conductive agent graphite (or acetylene black), carbon black into the mixer and stir for 3 hours; at the same time, stir PVDF and NMP for about 2 hours, wait for them to completely After dissolving (clearing), stir the mixer The mixed powder is put into the clear slurry of PVDF and NM P after stirring, and then stirred for about 3 hours to form a thick slurry;

A-4. Dry preparation of the positive electrode slurry with water as the medium, the required materials are: C M C 0.6 °. ~ 0.9%, S B R actual solid content 2% ~ 4%, conductive agent graphite 1% ~ 2% or acetylene black 0.5% ~ 1%, carbon black 1.

5% ~ 3%, lithium cobaltate '93% ~ 95%; the amount of water (deionized water, distilled water, purified water) is 40% ~ 130% of the total amount of all the aforementioned substances, that is, the solid-liquid ratio = 1: 0 · 4 ~ 1 · 3; Under normal circumstances, the best solid-liquid ratio-

1: 0.6-0.1; Put lithium cobaltate, conductive agent graphite (or acetylene black), carbon black into the mixer and stir for about 3 hours; at the same time, stir CMC with water for about 3 hours, wait for it After it is completely dissolved, it will become a clear slurry. That is, the mixed powder mixed by the mixer is put into the clear slurry of the stirred CMC and water and continued to be stirred for about 3 hours to form a thick slurry. Finally, aggregates and other impurities are removed;

B. Preparation of negative electrode slurry with NM P as the medium, the required materials are: graphite 93% ~ 95%, PVDF 5% ~ 7%, NMP is 80%-150% of the total amount of all the foregoing substances That is, the solid-liquid ratio-1: 0.8 ~ 1.

5; The best solid-liquid ratio = 1: 1 ~ 1 · 3; P V D F, need to be at about 1

2 0. B oven in C for 2 ~ 3 hours, graphite needs to be baked at 300 ° C ~ 500 ° C for 4 ~ 8 hours; the anode material is screened by 3 2 5 mesh vibration, and the remaining ones on the Internet are usually not suitable for use. ; Add PVDF to NM P and stir for about ³ to 4 hours, and then add the spare graphite that has been sifted through a 3 2 5 mesh screen to stir for about ³ to 4 hours.

3 to 4 hours into a thick paste;

B-1. To prepare the negative electrode slurry with water as the medium, the required materials are: graphite 93% ~ 95%, CMC 0.8% ~ 1.5%, SBR solid content 2% ~ 4%, water ( Deionized water, distilled water, purified water) is 80%-160% of the total amount of all the aforementioned substances, that is, the solid-liquid ratio-1: 0. 8 ~ 1. 6; the optimal solid-liquid ratio-1: 1 ~ 1.3; CMC should be baked at 120 ° C for 2 ~ 3 hours, graphite should be baked at 300 ° C ~ 500 ° (temperature baking 4 ~

8 hours; S B R can be replaced by P T F E; the anode material is screened by 300 mesh vibration, the leftovers on the Internet are generally not suitable for use; add C M C to water and stir for about

After 3 ~ 4 hours, add S B R (or P T F E) to it and stir for about 0.

5 to 1 hour. Finally, add graphite after baking and sieve through 3 2 5 mesh and stir for about 3 to 4 hours to form a thick paste; The particle size of the positive electrode material can be selected within the range of 2 μm to 12 μm. The optimal particle size should be 5 μm to 8 μm; the total particle size distribution of the positive electrode material is usually not more than 40 %; The solid-liquid ratio of fine powders below 2 μm should be increased by 20% to 50% based on the original solid-liquid ratio, and the solid-liquid ratio of coarser powders above 12 μm should be based on the original solid-liquid ratio 10% ~ 30%; In the preparation of the positive electrode, the particle size of the conductive material selected must be equal to or smaller than the particle size of the positive electrode material;

(2) Coating: Coat the stirred positive or negative electrode slurry onto the metal foil current collector, pull it out through a roller knife into the oven and bake, and it will become a semi-finished current collector after the baking is dried; The cloth must be careful not to have scratches, exposed substrates, lightness and weight in the vertical and horizontal directions; whether it is the positive or negative electrode, the prepared slurry must enter the coating machine from the preheating section after coating on the metal foil. The drying tunnel must not be inverted; the temperature of the preheating zone is usually 90 ° C or below, and the temperature of the medium temperature zone is 1 1 0. C ~ 1 3 0 ° C, ± 1 0 ° (:, the temperature of the high temperature section is 1

2 0 ° C ~ 1 4 0. Between C, ± 10 ° C; under the aforementioned temperature conditions, the temperature of the negative electrode slurry can be slightly higher than the temperature of the positive electrode slurry during coating and baking 10 ° C ~ 1

5. C, the temperature of the slurry with water as the medium can be slightly higher than that of the slurry with NM P as the medium by 10 ° C ~ 15 ° C. C; The linear speed of coating can be 800 mm ~

Adjust within the range of 5 0 0 0 mm; the best linear speed is 12 0 mm-3 5 0 0 mm per minute; the density of the active material of the coated positive electrode (1 3) is 0 per square centimeter. 0 2 ₈ ~ 0. 0 6 ₈ , the optimal density is 0 per square centimeter

0 3 2 g ~ 0. 0 4 2 g; The density of the active material of the negative electrode (1 2) after coating is about 0.0 1 g per square centimeter, and the optimal density is 0 per square centimeter. 0 1 4 g ~ 0. 0 2 1 g; both single-sided coating and simultaneous double-sided coating; single-sided coating of active materials, the back of the pole pieces of the same polarity must be attached to each other during assembly Active material current collector; The thickness of the metal foil used for single-sided coating must be thinner than the thickness of the aforementioned metal foil;

(3) Production: the positive electrode (1 3) is cut into a rectangular sheet with a large leaf monopole or a large leaf multipole and scrapes off the slurry at the pole (1 1); the negative electrode (1 2)

In addition to cutting, the method of making the tabs can be directly processed into rolled pole pieces by cutting or cutting; the large-leaf tabs can also be made separately and rolled on the positive and negative electrode pieces. After welding on the positive and negative plates; the maximum width of the large leaf tab is small At 1/2 of the perimeter, the maximum height of the large leaf tabs is not greater than its own width, preferably smaller than its width; when special needs are required, the minimum width of the large leaf tabs can be smaller than its height; a cylindrical shell is used, and the inner ridge The width of the large leaf tab is gradually smaller than the width of the outer palate. With a square shell, the width of the large leaf tab of the inner ring can be gradually smaller than the width of the outer palate and equal width. Generally, the positive The width of the large leaf tabs on the negative electrode sheet is the same width; but under special requirements, the width of the large leaf tabs on the positive and negative electrode sheet can also be unequal. In the case of fast high-power charging without high-power discharge, The width of the large leaf tab of the negative electrode can be larger than the width of the large leaf tab of the positive electrode. In the case of high power discharge without fast high power charging, the width of the large leaf tab of the positive electrode can be larger than that of the negative electrode Wide leaf monopole ears for the positive electrode and large leaf monopole ears for the negative electrode; large leaf multipole ears for the positive electrode and large leaf multipole ears for the negative electrode; In the case of rate discharge, large-leaf multipole ears can be used for the negative electrode, and large-leaf monopole ears can be used for the positive electrode. In the case of high-power discharge without fast high-power charging, large-leaf multipole ears can be used for the positive electrode. For the negative electrode, large-leaf monopoles can be used; for large-leaf multi-poles, the spacing of the poles can be different; the shape of the large-leaf poles can be designed and processed into square, rectangular, semi-circular, trapezoidal, or other conductive The shape of the flow and heat dissipation, the best shape of the tab is a trapezoidal tab with R rounded corners; the connection between the root of the large leaf tab and the pole piece can be a clear angle connection or a smooth arc connection; large Leaf pole ears can be processed into a raised head type (1 0/1 1) or a hidden head type (1 7/1 8);

The diaphragm (19) is made of a polyethylene or polypropylene material with a microporous structure and a low current cut-off temperature of 15 μm to 80 μm (19); a charge and discharge requirement of 1 C At ~ 2 C, the optimal thickness of the separator (19 or 19-1) is 20 μm to 40 μm; when the charge and discharge requirements are 3 C or greater, the optimal thickness of the separator is 4 Ο μ πι Or above; except for the ears, the diaphragm (1 9) must completely shield the positive electrode (1 3) or negative electrode (12) from the surroundings, and the edges must not be exposed to prevent short circuits; the immersed positive electrode ( 1 3) Immerse in a slurry of a polyolefin-based material containing a reasonable amount of a pore-forming agent, and then place the positive electrode (1 3) in a specific solvent to extract the pore-forming agent to form a separator integral with the positive electrode sheet; A slurry of a polyolefin-based material containing a reasonable amount of a pore former is directly coated on the surface of the positive electrode (1 3) that has been rolled, and the positive electrode (1 3) Put the pore-forming agent into a specific solvent to form a separator integrated with the positive electrode sheet (19);

(4) Rolling: In the rolling process, the linear pressure of the positive electrode is 100 to 18 kg / cm, and the linear pressure of the negative electrode is 80 to 160 kg / cm; the positive electrode (1 3) is rolling The thickness before rolling is about 170 μm to 27.0 μm, and the thickness after rolling is about 110 μm to 165 μm.The optimal thickness before rolling is 15 μm ~ 2 3 5 μ m, the optimal thickness after rolling is 1 3 5 μ m ~ 1 5 5 μ m; the thickness of the negative electrode (1 2) before rolling is about 1 8 5 μ m ~ 2 7 5 μ m, After rolling 1 1 0 μ ιη ~ 1 6 5 μ m, the optimal thickness of the negative electrode before rolling is 2 2 0 μ ιη ~ 2 5 0 μ ιη, and the optimal thickness after rolling is 1 3 5 μ m ~ 1 5 5 μ m;

(5) Winding: The rolling pin of the inner body of the cylindrical shell used for winding is a round shaft, and the rolling pin of the inner body of the rectangular shell used for winding is a thin sheet with certain rigidity and elasticity; when the pole piece is folded inward, Generally, the folding line should be processed at the inner fold on the pole piece and the active material at the folding line should be scraped off; if the folding line is processed on the positive electrode (1 3), the front end of the negative electrode (1 2) should be aligned with the folding of the positive electrode (1 3) The center line of the wire so that it cannot pierce the diaphragm (19); when winding, a pair of positive and negative electrode groups must be neatly stacked, and the middle lined with the diaphragm (19) is tightly wound into the inner body (7) It is also possible to stack multiple pairs of positive and negative electrodes in parallel neatly at the same time, and tightly wind them into an inner body; power batteries are usually only installed in one inner body (7); several inner bodies can also be installed in parallel to the casing (9 ), A large-capacity power battery is formed; when winding, the large leaf tabs on the positive and negative electrodes must be staggered, and the tabs can be neatly aligned with the positive and negative poles; the wound inner body with a cylindrical shell (7) The longitudinal section is moment The rolled inner body (7) with a square shell is rectangular, and the rolled inner body (7) excludes the thickness of the separator (1 9) and the gap between the positive electrode (1 3) and the negative electrode (1 2) Distance, not more than 2 5 μ m;

(6) Liquid injection: Before the liquid injection, the normal air in the inner cavity of the lithium ion power battery must be extracted, and then an appropriate amount of electrolyte is injected from the liquid injection hole in the safety valve (3); the liquid injection amount is usually 0.1. 5 Ah / g ~ 0.6 Ah / g adjustment; the optimal injection volume is 0.2 Ah / g ~ 0.3 5 Ah / g; using a multi-electrolyte that can adapt to wider temperature changes: LIPF 6 / EC: DMC: DEC, the solvent ratio is 0.9 5 to 1. 0 5: 0.9 5 to 1. 0 5: 0. 9 5-1. 0 5; or LIPF 6 / EC: EMC: DEC, the solvent ratio is 0.9 5 to 1. 0 5: 0.9 5 to 1. 0 5: 0.9 5 to 1. 0 5 ; Or 1 ^ 1?? 6 / £ 0;: 01 ^ (:: £ €, solvent ratio is 0.9 5-1. 0 5: 0.9 5-1. 0 5: 0.9 5-1 0 5; OR LIPF 6 / EC: DM C: EM C: DEC with a solvent ratio of 0.9 5 to 1. 0 5: 0.9 5-1. 0 5: 0.9 5-1. 0 5 : 0. 9 5-1 0 5;

(7) Formation: The formation principle must be low current and low voltage, and no large current can be formed. Higher voltage formation can fully activate the active materials on the positive and negative current collector substrates. The formation process must be completed uninterrupted at one time. Do not stop or stop arbitrarily in the middle, the formation curve should be smoothly connected, and the current should be controlled at 0. 0 1 C / 10 hours → → 0. 0 2 C / 5 hours → → 0. 0 5 C / 5 hours → → 0. 1 C / 4 hours → → 0.2 C / 1 hour, after the constant current is full, it will be converted to constant pressure to continue charging, so as to be sufficient at one time.

(8) Capacity division: Capacity division. Put batteries with electrical performance indicators that meet process requirements and batteries with electrical performance indicators that do not meet process requirements, respectively.