A method for preparing a laminated high-energy-density secondary battery cell

Abstract

The present invention relates to the technical field of new energy batteries, and specifically to a method for preparing a laminated high-energy-density secondary battery cell, including the following steps: S1, preparing two positive electrode slurries and three negative electrode slurries respectively, and stirring; S2, preparing two positive electrode slurries C1 and C2, and making three positive electrode sheets C1, C2 and C3 respectively; preparing three negative electrode slurries A1, A2 and A3, and making four negative electrode sheets A1, A2, A3, A12 and A23 respectively; S3, assembling the positive and negative electrode sheets and diaphragms according to a special method, and then wrapping Mylar sheets, welding, shelling, baking, and making dry batteries; S4, injecting, forming, and dividing the cells to obtain finished cells. The cell preparation method of the present invention does not require the modification of the existing process, and does not add additional equipment and devices, and can greatly improve the energy density and fast charging and discharging new energy, balance the life of the inner and outer ring sheets, extend the overall life of the cell, balance the temperature difference of the cell, and improve safety.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy batteries, and in particular to a method for preparing a laminated high-energy-density secondary battery cell. Background Art

[0002] At present, the never-ending demand for longer driving range in automobiles, commercial vehicles and heavy trucks, coupled with the companies' extreme control over costs, requires lithium-ion or sodium-ion batteries to achieve higher energy density and thicker electrode plates.

[0003] Lithium and sodium ion batteries are secondary batteries that can be repeatedly charged and discharged. They are composed of main components such as anode and cathode electrodes, isolation membranes, electrolytes, and mechanical parts. For large-volume square shell batteries, the larger the volume, the greater the uneven temperature distribution and current distribution inside the battery. The above differences will lead to increased polarization inside the battery, which will seriously affect the electrical performance and safety performance of the battery.

[0004] Based on this, a method for preparing a laminated high-energy-density secondary battery cell is now provided, which can eliminate the drawbacks of the existing device. Summary of the invention

[0005] In view of the above problems, a method for preparing a laminated high-energy-density secondary battery cell is provided to solve the problem that the larger the volume of the cell, the greater the unevenness of the temperature distribution and current distribution inside the cell.

[0006] In order to solve the problems of the prior art, the present invention provides a method for preparing a laminated high-energy-density secondary battery cell, comprising the following steps:

[0007] S1. Prepare two positive electrode slurries and three negative electrode slurries respectively, and stir them;

[0008] S2, two positive electrode slurries C1 and C2 were prepared, and three positive electrode sheets C1, C2 and C3 were made respectively; three negative electrode slurries A1, A2 and A3 were prepared, and five negative electrode sheets A1, A2, A3, A12 and A23 were made respectively;

[0009] S3, assembling the positive and negative electrode sheets and the separator according to a special method to form a dry cell;

[0010] S4, injecting liquid, forming, and dividing the capacity of the battery cell to obtain a finished battery cell.

[0011] Preferably, the manufacturing process of the positive electrode sheets C1, C2, and C3 in step S2 is as follows:

[0012] (1) Prepare and coat the positive electrode slurry C1, control the center value of the surface density at 450 g / m2, control the cold pressing density at 2.55 g / cm3, and then die-cut and slit to form the positive electrode sheet C1;

[0013] (2) Prepare the positive electrode slurry C1 for coating, control the center value of the surface density at 400g / m2, control the cold pressing density at 2.6g / cm3, and then die-cut and slit to form the positive electrode sheet C2;

[0014] (3) Apply positive electrode slurry C2, control the center value of surface density at 350g / m2, control the cold pressing density at 2.55g / cm3, and then die-cut and slit to form positive electrode sheet C3.

[0015] Preferably, the positive electrode sheet C1 coated on one side is a positive electrode sheet C10.

[0016] Preferably, the specific steps of processing the negative electrode sheets A1, A2 and A3 in step S2 are:

[0017] (1) Prepare and coat negative electrode slurry A1, control the center value of surface density at 223 g / m2, control the cold pressing density at 1.53 g / cm3, and then die-cut and slit to form negative electrode sheet A1;

[0018] (2) preparing the negative electrode slurry A2 for coating, controlling the center value of the surface density at 198 g / m2, and controlling the cold pressing density at 1.6 g / cm3, and then die-cutting and slitting to form the negative electrode sheet A2;

[0019] (3) Prepare to coat the negative electrode slurry A3, control the center value of the surface density at 174g / m2, and control the cold pressing density at 1.55g / cm3, and then die-cut and slit to form the negative electrode sheet A3.

[0020] Preferably, the specific steps of processing the negative electrode sheet A12 in step S2 are:

[0021] (1) One side is coated with negative electrode slurry A1, and the center value of the surface density is controlled at 223g / m2;

[0022] (2) The other side is coated with negative electrode slurry A2, the coating surface density is controlled at 198 g / m2, and the compaction is controlled so as not to exceed the smaller compaction, and then it is die-cut and strip-formed.

[0023] Preferably, the specific steps of processing the negative electrode sheet A23 in step S2 are:

[0024] (1) One side is coated with negative electrode slurry A2, and the center value of the surface density is controlled at 198g / m2;

[0025] (2) The other side is coated with negative electrode slurry A3, the coating surface density is controlled at 174 g / m2, and the compaction is controlled so as not to exceed the smaller compaction. Then, the negative electrode sheet A23 is produced through die-cutting and striping.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The battery cell preparation method of the present invention does not require modification of the existing process, nor does it require additional equipment. It can greatly improve energy density and fast charging and discharging capabilities, balance the life of inner and outer ring pole pieces, extend the overall life of the battery cell, balance the temperature difference of the battery cell, and improve safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The box line of Example 1 VS Comparative Example 1 of the method for preparing a laminated high-energy-density secondary battery cell Figure 1 .

[0029] Figure 2 The box line of Example 1 VS Comparative Example 1 of the method for preparing a laminated high-energy-density secondary battery cell Figure 2 .

[0030] Figure 3 It is an analysis diagram of a method for preparing a laminated high-energy-density secondary battery cell.

[0031] Figure 4 The present invention is a data chart of a method for preparing a laminated high-energy-density secondary battery cell. DETAILED DESCRIPTION

[0032] In order to further understand the features, technical means, specific objectives and functions of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0033] Example 1: 320Ah lithium iron phosphate aluminum shell battery cell (high energy density battery cell)

[0034] This embodiment provides a method for preparing a laminated high-energy-density secondary battery cell, the method comprising the following steps:

[0035] 1. Stirring: Prepare 2 kinds of positive electrode slurries and 3 kinds of negative electrode slurries respectively.

[0036] (1) The positive electrode slurry C1 is prepared as follows: 97.5% lithium iron phosphate powder, 1.0% conductive carbon black, and 1.5% polyvinylidene fluoride are stirred according to an existing mature stirring process to prepare slurry C1 for use.

[0037] (2) The preparation method of positive electrode slurry C2 is as follows: 96.5% lithium iron phosphate powder, 2.0% conductive carbon black, and 1.5% polyvinylidene fluoride are stirred according to an existing mature stirring process to prepare slurry C2 for use.

[0038] (3) The preparation method of negative electrode slurry A1 is as follows: 96.5% of small-particle graphite, 1.5% of conductive carbon black, and 2% of polyacrylic acid are stirred using an existing mature stirring process to prepare negative electrode slurry A1.

[0039] (4) The preparation method of negative electrode slurry A2 is as follows: 96.5% of large and small particle composite graphite, 1.5% of conductive carbon black, and 2% of polyacrylic acid are stirred using an existing mature stirring process to prepare negative electrode slurry A2.

[0040] (5) The preparation method of negative electrode slurry A3 is as follows: 96.0% small-particle graphite, 2% conductive carbon black, and 2% polyacrylic acid are stirred using an existing mature stirring process to prepare negative electrode slurry A3.

[0041] 2. Pole production:

[0042] (1) Positive electrode sheet C1: coating the positive electrode slurry C1, controlling the center value of the surface density at 450 g / m2, controlling the cold pressing density at 2.55 g / cm3, and then die-cutting and slitting to form the positive electrode sheet C1.

[0043] (2) Positive electrode sheet C2 is coated with positive electrode slurry C1, the center value of the surface density is controlled at 400g / m2, the cold pressing density is controlled at 2.6g / cm3, and then die-cut and strip-cut to form positive electrode sheet C2.

[0044] (3) Positive electrode sheet C3 is coated with positive electrode slurry C2, the center value of the surface density is controlled at 350g / m2, the cold pressing density is controlled at 2.55g / cm3, and then die-cut and strip-cut to form the positive electrode sheet C3.

[0045] (4) The positive electrode sheet C10 is a single-sided coated positive electrode sheet C1, mainly preventing the outermost layer on both sides of the battery cell.

[0046] (5) Negative electrode sheet A1: Apply negative electrode slurry A1, control the center value of surface density at 223g / m2, control the cold pressing density at 1.53g / cm3, and then die-cut and slit to form negative electrode sheet A1.

[0047] (6) Negative electrode sheet A2: coating negative electrode slurry A2, with the center value of surface density controlled at 198 g / m2, cold pressing density controlled at 1.6 g / cm3, and then die-cutting and striping to form negative electrode sheet A2.

[0048] (7) Negative electrode sheet A3: negative electrode slurry A3 is applied, the center value of the surface density is controlled at 174 g / m2, the cold pressing density is controlled at 1.55 g / cm3, and then the negative electrode sheet A3 is made by die cutting and striping.

[0049] (8) Negative electrode sheet A12: one side is coated with negative electrode slurry A1, and the center value of the surface density is controlled at 223 g / m2; the other side is coated with negative electrode slurry A2, and the coating surface density is controlled at 198 g / m2. The compaction is controlled so as not to exceed the smaller compaction value, and then the negative electrode sheet A12 is manufactured by die-cutting and stripping.

[0050] (9) Negative electrode sheet A23: one side is coated with negative electrode slurry A2, and the center value of the surface density is controlled at 198 g / m2; the other side is coated with negative electrode slurry A3, and the coating surface density is controlled at 174 g / m2. The compaction is controlled so as not to exceed the smaller compaction value, and then the negative electrode sheet A23 is manufactured by die-cutting and stripping.

[0051] 3. Assembly: Assemble the positive and negative electrodes and the diaphragm as follows Figure 1 Assemble, then wrap Mylar sheets, weld, put into shells, bake to make dry batteries.

[0052] 4. Activation: The battery cells are injected, formed, and divided to obtain finished battery cells; the average capacity and internal resistance are calculated, and two battery cells with performance indicators close to the center value are selected for 45-degree cycles (the decay of 25-degree cycles is too slow and not conducive to rapid data acquisition). The battery cells have significantly improved in capacity and cycle performance; see the specific data for details. Figure 2 and Figure 4 .

[0053] Comparative Example 1: 320Ah lithium iron phosphate aluminum shell battery cell (high energy density battery cell)

[0054] 1. Stirring:

[0055] (1) The positive electrode slurry preparation method is as follows: 97.5% lithium iron phosphate powder, 1.0% conductive carbon black, and 1.5% polyvinylidene fluoride are stirred according to an existing mature stirring process to prepare a positive electrode slurry for use.

[0056] (2) The preparation method of negative electrode slurry is as follows: 96.5% small-particle graphite, 1.5% conductive carbon black, and 2% polyacrylic acid are stirred using an existing mature stirring process to form a negative electrode slurry for use. 2. Pole sheet production: For positive electrode sheets, apply positive electrode slurry, control the center value of the surface density at 400g / m2, and control the cold pressing density at 2.6g / cm3, and then die-cut and slit to form positive electrode sheets. For negative electrode sheets, apply negative electrode slurry, control the center value of the surface density at 198g / m2, and control the cold pressing density at 1.6g / cm3, and then die-cut and slit to form negative electrode sheets.

[0057] 3. Assembly: Assemble the positive and negative electrode sheets in the order of isolation membrane + positive single-sided electrode sheet + (isolation membrane + negative electrode sheet + isolation membrane + positive electrode sheet + isolation membrane) * n + negative electrode sheet + isolation membrane + positive single-sided electrode sheet + isolation membrane; where n is designed according to the capacity of the battery cell; then wrap the Mylar sheet, weld, put into the shell, bake, and make a dry battery.

[0058] 4. Activation: Fill the battery cell with liquid, form it, and divide its capacity to obtain the finished battery cell; calculate the average capacity and internal resistance, and take 2 batteries with performance indicators close to the center value for 45-degree cycle. For specific data capacity, see Figure 1 , internal resistance Figure 2 , see the cycle Figure 3 .

[0059] In summary, this battery cell preparation method can improve energy density and fast charging and discharging capabilities, balance the life of inner and outer ring electrodes, extend the overall life of the battery cell, balance the temperature differences of the battery cell, and improve safety.

[0060] The above embodiments only express one or several implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a laminated high energy density secondary battery cell, characterized in that: The following steps are involved: S1. Prepare two positive electrode slurries and three negative electrode slurries respectively, and stir them; S2, two positive electrode slurries C1 and C2 were prepared, and three positive electrode sheets C1, C2 and C3 were made respectively; three negative electrode slurries A1, A2 and A3 were prepared, and five negative electrode sheets A1, A2, A3, A12 and A23 were made respectively; S3, assembling the positive and negative electrode sheets and the separator according to a special method to form a dry cell; S4, injecting liquid, forming, and dividing the capacity of the battery cell to obtain a finished battery cell.

2. A method for preparing a laminated high energy density secondary battery cell according to claim 1, characterized in that: The manufacturing process steps of the positive electrode sheets C1, C2, and C3 in step S2 are as follows: (1) Prepare and coat the positive electrode slurry C1, control the center value of the surface density at 450 g / m2, control the cold pressing density at 2.55 g / cm3, and then die-cut and slit to form the positive electrode sheet C1; (2) Prepare the positive electrode slurry C1 for coating, control the center value of the surface density at 400g / m2, control the cold pressing density at 2.6g / cm3, and then die-cut and slit to form the positive electrode sheet C2; (3) Apply positive electrode slurry C2, control the center value of surface density at 350g / m2, control the cold pressing density at 2.55g / cm3, and then die-cut and slit to form positive electrode sheet C3.

3. The method for preparing a laminated high energy density secondary battery cell according to claim 2, characterized in that: The positive electrode sheet C1 coated on one side is the positive electrode sheet C10.

4. The method for preparing a laminated high energy density secondary battery cell according to claim 1, characterized in that: The specific steps of processing the negative electrode sheets A1, A2 and A3 in step S2 are as follows: (1) Prepare and coat negative electrode slurry A1, control the center value of surface density at 223 g / m2, control the cold pressing density at 1.53 g / cm3, and then die-cut and slit to form negative electrode sheet A1; (2) preparing the negative electrode slurry A2 for coating, controlling the center value of the surface density at 198 g / m2, and controlling the cold pressing density at 1.6 g / cm3, and then die-cutting and slitting to form the negative electrode sheet A2; (3) Prepare the negative electrode slurry A3 for coating, control the center value of the surface density at 174g / m2, and control the cold pressing density at 1.55g / cm3, and then die-cut and slit to form the negative electrode sheet A3.

5. The method for preparing a laminated high energy density secondary battery cell according to claim 1, characterized in that: The specific steps of processing the negative electrode sheet A12 in step S2 are as follows: (1) One side is coated with negative electrode slurry A1, and the center value of the surface density is controlled at 223g / m2; (2) The other side is coated with negative electrode slurry A2, the coating surface density is controlled at 198 g / m2, and the compaction is controlled so as not to exceed the smaller compaction, and then it is die-cut and strip-formed.

6. The method for preparing a laminated high energy density secondary battery cell according to claim 1, characterized in that: The specific steps of processing the negative electrode plate A23 in step S2 are as follows: (1) One side is coated with negative electrode slurry A2, and the center value of the surface density is controlled at 198g / m2; (2) The other side is coated with negative electrode slurry A3, the coating surface density is controlled at 174 g / m2, and the compaction is controlled so as not to exceed the smaller compaction. Then, the negative electrode sheet A23 is produced through die-cutting and striping.

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