Method for determining liquid injection amount of laminated battery and method for calculating thickness of laminated battery

Abstract

The invention provides a method for determining the liquid injection amount of a laminated battery and a method for calculating the thickness of the laminated battery, and relates to the technical field of batteries. By adding the minimum solid-liquid layer gap matched with the solid-solid layer gap and the formation pressure, the liquid injection amount required for one time and the liquid injection amount required for the second time can be accurately calculated, so that on one hand, the electrolyte waste caused by excessive liquid injection amount can be greatly reduced; and on the other hand, the problem of insufficient electrode liquid amount required by formation caused by insufficient liquid injection amount can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a method for determining the liquid injection amount of a laminated battery and a method for calculating the thickness of a laminated battery. Background Art

[0002] With the development of technology, large cylindrical batteries are becoming increasingly popular in the energy storage market due to their high space utilization and high capacity. However, since the bare cells of laminated batteries have no constraints, the interlayer gap is difficult to control, resulting in insufficient accuracy in the battery's liquid injection volume, which brings difficulties to some battery manufacturing ends.

[0003] With current secondary injection technology, most battery designers lack a sound methodology for calculating primary and secondary injection volumes. In particular, the calculation of the primary injection volume often ignores the "solid-solid gap" in the winding core, resulting in inaccurate primary injection volume. Secondary injection volume calculations are often based on experience or experimental results, resulting in inaccurate secondary injection volumes.

[0004] In the current technology, the method of calculating the thickness of the battery cell usually ignores the change in the "solid-liquid" layer gap caused by the electrolyte infiltration between the electrode layers after the battery cell is filled with liquid, resulting in inaccurate calculation of the battery thickness.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The first object of the present invention is to provide a method for determining the liquid injection amount of a laminated battery to solve the above technical problems.

[0007] A second object of the present invention is to provide a method for calculating the thickness of a laminated battery.

[0008] In order to achieve the above objectives, the following technical solutions are adopted:

[0009] In a first aspect, the present invention provides a method for determining the liquid injection amount of a laminated battery, wherein the liquid injection amount includes a primary liquid injection amount and a secondary liquid injection amount;

[0010] The method for determining the amount of liquid injected once comprises the following steps:

[0011] a. Soak the dried positive and negative electrodes in the electrolyte. Measure the thickness of the positive electrode after soaking as Hc and the thickness of the negative electrode as Ha.

[0012] b. The target number of layers of the bare battery cell is vacuum-encapsulated with aluminum-plastic film, and the thickness of the battery cell after encapsulation is measured as H0, then H0 = n*Hc+(n+1)*Ha+2*(n+1)*Hs+Hτ1*n+2*Hv; where n is the number of positive electrode layers, n+1 is the number of negative electrode layers, 2*(n+1) is the number of separator layers, Hτ1 is the solid-solid layer gap within the basic unit, Hs is the separator thickness, and Hv is the thickness of the aluminum-plastic film; an adjacent separator layer, a negative electrode layer, a separator layer, and a positive electrode layer constitute a basic unit;

[0013] The one-time injection volume M1=(Vc+Va+Vs+Vτ1+Vo)*ρ*k1;

[0014] Vτ1=Hτ1*Lc*Wc*n;

[0015] Vτ2=Hτ2*Lc*Wc*n;

[0016] Vo=(Wa*La-Wc*Lc)*Hc*n;

[0017] Wherein, Vc is the pore of the positive electrode sheet, Va is the pore of the negative electrode sheet, Vs is the pore of the separator, Vτ1 is the solid-solid layer gap, Vτ2 is the solid-liquid layer gap, Vo is the gap of the negative electrode sheet beyond the positive electrode sheet, ρ is the electrolyte density, k1=1-1.05, Lc is the length of the positive electrode sheet, Wc is the width of the positive electrode sheet, Wa is the width of the negative electrode sheet, and La is the length of the negative electrode sheet;

[0018] The secondary injection amount M2 = (Hτ0-Hτ1)*Lc*Wc*n*ρ;

[0019] Where Hτ0 is the interlayer gap within the basic unit in the free state of the battery, and its value is 0.003mm-0.006mm.

[0020] As a further technical solution, in step a, the water content of the dried positive electrode sheet is below 400 ppm, and the water content of the dried negative electrode sheet is below 300 ppm.

[0021] As a further technical solution, in step a, the soaking time is 24-72 hours.

[0022] As a further technical solution, in step b, the vacuum degree of the vacuum packaging is 50-120 kPa, and the vacuuming time is 30-50 s.

[0023] As a further technical solution, the positive electrode sheet pore Vc = σc*Lc*Wc*(Hc-Dc)*n;

[0024] Wherein, σc is the porosity of the positive electrode sheet, and Dc is the thickness of the positive electrode current collector.

[0025] As a further technical solution, the negative electrode sheet pore Va=σa*La*Wa*(Ha-Da)*(n+1);

[0026] Where σa is the porosity of the negative electrode sheet and Da is the thickness of the negative electrode current collector.

[0027] As a further technical solution, the diaphragm pore Vs = σs*Ls*Ws*Hs*2*(n+1);

[0028] Where σs is the porosity of the membrane, Ls is the length of the membrane, Ws is the width of the membrane, and Hs is the thickness of the membrane.

[0029] In a second aspect, the present invention provides a method for calculating the thickness of a laminated battery, comprising the following steps:

[0030] a. Soak the dried positive and negative electrodes in the electrolyte. Measure the thickness of the positive electrode after soaking as Hc and the thickness of the negative electrode as Ha.

[0031] b. Inject the target number of stacked cells with an electrolyte injection volume of M0, then pressurize and form them. After fully charging the battery and discharging it to 0% SOC, measure the battery thickness as H1; M0 = K0 * C0, where C0 is the design capacity of the battery cell; K0 is a constant, K0 for lithium iron phosphate batteries is 4.8g / Ah, and K0 for lithium nickel cobalt manganese oxide batteries or lithium nickel cobalt aluminum oxide batteries is 3.5g / Ah; the solid-liquid layer gap within the basic unit is Hτ2 = (H1-H0) / n;

[0032] The battery thickness H is calculated by the following formula:

[0033] H=n*Hc+(n+1)*Ha+2*(n+1)*Hs+Hτ2*n+2*Hv;

[0034] Where n is the number of positive electrode layers, n+1 is the number of negative electrode layers, 2*(n+1) is the number of separator layers, Hc is the thickness of the positive electrode layer, Ha is the thickness of the negative electrode layer, Hs is the thickness of the separator, Hτ2 is the solid-liquid layer gap within the basic unit, and Hv is the thickness of the aluminum-plastic film.

[0035] As a further technical solution, in step b, the pressure of the pressurized formation is 0.08-0.1 MPa.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] In the present invention, by adding the calculation of the solid-solid layer gap and the minimum solid-liquid layer gap that matches the formation pressure, the required primary injection volume and the secondary injection volume can be accurately calculated. On the one hand, the waste of electrolyte caused by excessive injection volume can be greatly reduced. On the other hand, the problem of insufficient electrode liquid required for formation due to insufficient injection volume can be avoided. DETAILED DESCRIPTION

[0038] Below in conjunction with embodiment and example, embodiment of the present invention is described in detail, but those skilled in the art will appreciate that the following embodiment and example are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiment in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work premise all fall within the scope of protection of the present invention. Unspecified conditions are carried out according to the conditions of normal conditions or manufacturer's recommendations. Reagents used or instruments not specified by the manufacturer are conventional products that can be purchased commercially.

[0039] It should be noted that, in the present invention, the primary injection volume refers to the amount of electrolyte injected before the battery is formed; the secondary injection volume refers to the amount of electrolyte injected after the battery is formed.

[0040] In a first aspect, the present invention provides a method for determining the liquid injection amount of a laminated battery, wherein the liquid injection amount includes a primary liquid injection amount and a secondary liquid injection amount;

[0041] The method for determining the amount of liquid injected once comprises the following steps:

[0042] a. Soak the dried positive and negative electrodes in the electrolyte. Measure the thickness of the positive electrode after soaking as Hc and the thickness of the negative electrode as Ha.

[0043] b. The target number of layers of the bare battery cell is vacuum-encapsulated with aluminum-plastic film, and the thickness of the battery cell after encapsulation is measured as H0, then H0 = n*Hc+(n+1)*Ha+2*(n+1)*Hs+Hτ1*n+2*Hv; where n is the number of positive electrode layers, n+1 is the number of negative electrode layers, 2*(n+1) is the number of separator layers, Hτ1 is the solid-solid layer gap within the basic unit, Hs is the separator thickness, and Hv is the thickness of the aluminum-plastic film; an adjacent separator layer, a negative electrode layer, a separator layer, and a positive electrode layer constitute a basic unit;

[0044] The one-time injection volume M1=(Vc+Va+Vs+Vτ1+Vo)*ρ*k1;

[0045] Vτ1=Hτ1*Lc*Wc*n;

[0046] Vτ2=Hτ2*Lc*Wc*n;

[0047] Vo=(Wa*La-Wc*Lc)*Hc*n;

[0048] Wherein, Vc is the pore of the positive electrode sheet, Va is the pore of the negative electrode sheet, Vs is the pore of the separator, Vτ1 is the solid-solid layer gap, Vτ2 is the solid-liquid layer gap, Vo is the gap of the negative electrode sheet beyond the positive electrode sheet, ρ is the electrolyte density, k1=1-1.05, Lc is the length of the positive electrode sheet, Wc is the width of the positive electrode sheet, Wa is the width of the negative electrode sheet, and La is the length of the negative electrode sheet;

[0049] The secondary injection amount M2 = (Hτ0-Hτ1)*Lc*Wc*n*ρ;

[0050] Where Hτ0 is the interlayer gap within the basic unit in the free state of the battery, and its value is 0.003mm-0.006mm.

[0051] In the present invention, by adding the calculation of the solid-solid layer gap and the minimum solid-liquid layer gap that matches the formation pressure, the required primary injection volume and the secondary injection volume can be accurately calculated. On the one hand, the waste of electrolyte caused by excessive injection volume can be greatly reduced. On the other hand, the problem of insufficient electrode liquid required for formation due to insufficient injection volume can be avoided.

[0052] In some optional embodiments, in step a, the water content of the dried positive electrode sheet is below 400 ppm, and the water content of the dried negative electrode sheet is below 300 ppm.

[0053] In some optional embodiments, the drying step further includes placing the electrode sheet aside for 8 hours to 56 hours (for example, but not limited to 8 hours, 28 hours, or 56 hours) to allow the electrode sheet to release internal stress.

[0054] In some optional embodiments, in step a, the soaking time is 24-72 hours, for example, but not limited to 24 hours, 36 hours or 72 hours.

[0055] In some optional embodiments, in step b, the vacuum degree of the vacuum packaging is 50-120 kPa, for example, it can be, but not limited to 50 kPa, 80 kPa or 120 kPa, and the vacuuming time is 30-50 s, for example, it can be, but not limited to 30 s, 40 s or 50 s.

[0056] In some optional embodiments, the positive electrode sheet pore Vc=σc*Lc*Wc*(Hc-Dc)*n;

[0057] Wherein, σc is the porosity of the positive electrode sheet, and Dc is the thickness of the positive electrode current collector.

[0058] In some optional embodiments, the negative electrode sheet pore Va=σa*La*Wa*(Ha-Da)*(n+1);

[0059] Where σa is the porosity of the negative electrode sheet and Da is the thickness of the negative electrode current collector.

[0060] In some optional embodiments, the membrane pore Vs=σs*Ls*Ws*Hs*2*(n+1);

[0061] Where σs is the porosity of the membrane, Ls is the length of the membrane, Ws is the width of the membrane, and Hs is the thickness of the membrane.

[0062] In some optional embodiments, the injection volume further includes a secondary injection volume;

[0063] In a second aspect, the present invention provides a method for calculating the thickness of a laminated battery, comprising the following steps:

[0064] a. Soak the dried positive and negative electrodes in the electrolyte. Measure the thickness of the positive electrode after soaking as Hc and the thickness of the negative electrode as Ha.

[0065] b. Inject the target number of stacked cells with an electrolyte injection volume of M0, then pressurize and form them. After fully charging the battery and discharging it to 0% SOC, measure the battery thickness as H1; M0 = K0 * C0, where C0 is the design capacity of the battery cell; K0 is a constant, K0 for lithium iron phosphate batteries is 4.8g / Ah, and K0 for lithium nickel cobalt manganese oxide batteries or lithium nickel cobalt aluminum oxide batteries is 3.5g / Ah; the solid-liquid layer gap within the basic unit is Hτ2 = (H1-H0) / n;

[0066] The battery thickness H is calculated by the following formula:

[0067] H=n*Hc+(n+1)*Ha+2*(n+1)*Hs+Hτ2*n+2*Hv;

[0068] Where n is the number of positive electrode layers, n+1 is the number of negative electrode layers, 2*(n+1) is the number of separator layers, Hc is the thickness of the positive electrode layer, Ha is the thickness of the negative electrode layer, Hs is the thickness of the separator, Hτ2 is the solid-liquid layer gap within the basic unit, and Hv is the thickness of the aluminum-plastic film.

[0069] In some optional embodiments, in step b, the pressure of the pressurized formation is 0.08-0.1 MPa, for example, but not limited to 0.08 MPa, 0.09 MPa or 0.1 MPa.

[0070] The present invention is further described below by way of specific examples. However, it should be understood that these examples are merely provided for more detailed description and are not to be construed as limiting the present invention in any form.

[0071] The following laminated batteries are all lithium iron phosphate batteries. Except for the different technical parameters (the technical parameters are shown in Table 1), the preparation materials and methods are the same (the density of the electrolyte is 1.21g / cm^3).

[0072] Example 1

[0073] A method for determining the liquid injection amount of a laminated battery and a method for calculating the battery thickness include a method for determining the primary liquid injection amount of a laminated battery, a method for determining the secondary liquid injection amount, and a method for calculating the battery thickness.

[0074] 1. Method for determining the amount of liquid injected into a stacked primary battery:

[0075] 1) The rolled positive and negative electrode sheets are placed for a certain time T1, and then placed in an oven for a certain time of 4 hours until their moisture content meets P. The moisture content of the positive electrode sheet is Pc, and the moisture content of the negative electrode sheet is Pa, where Pc ≤ 400ppm and Pa ≤ 300ppm;

[0076] 2) Place the electrode from 1) in an electrolyte and seal it for 24 hours. Measure the thickness of the electrode after immersion. The thickness of the positive and negative electrodes are Hc and Ha, respectively.

[0077] 3) Calculate the porosity of the positive and negative electrode sheets using the electrode sheet thickness measured in 2) and the true density of each material in the electrode sheet formula. The porosity of the positive electrode sheet is recorded as σc, and the porosity of the negative electrode sheet is recorded as σa.

[0078] 4) Calculate the solid-solid interlayer gap: encapsulate the bare battery cells with the target number of stacked layers with aluminum-plastic film and evacuate them, where the vacuum degree is -50-120kPa and the vacuuming time (pressure holding time) is 30s. Test the battery cells after evacuation and the thickness of the encapsulated cells is H0, H0 = n*Hc+(n+1)*Ha+2*(n+1)*Hs+Hτ1*n+2*Hv; where n is the number of positive electrode layers, n+1 is the number of negative electrode layers, 2*(n+1) is the number of separator layers, Hτ1 is the solid-solid interlayer gap within the basic unit, Hs is the separator thickness, and Hv is the thickness of the aluminum-plastic film; one adjacent separator layer, one negative electrode layer, one separator layer, and one positive electrode layer constitute a basic unit;

[0079] 5) Calculate the solid-liquid interlayer gap: Fill the target battery with a certain amount of liquid, M0, and then perform a pressurized formation charge. Charge the battery to 0% SOC and test the battery thickness, H1. Here, M0 = k0 * C0, where C0 is the design capacity of the battery cell. K0 is a constant whose value depends on the main positive electrode material. K0 for lithium iron phosphate is 4.8g / Ah, and for lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminum oxide batteries, it is 3.5g / Ah. The solid-liquid interlayer gap within the basic cell is Hτ2 = (H1 - H0) / n. The pressure for pressurized formation is 0.08-0.1 MPa.

[0080] 6) Calculate the injection volume:

[0081] Porosity of positive electrode:

[0082] Vc=σc*Lc*Wc*(Hc-Dc)*n;

[0083] Wherein, σc is the porosity of the positive electrode sheet, and Dc is the thickness of the positive electrode current collector;

[0084] Negative electrode sheet pores:

[0085] Va=σa*La*Wa*(Ha-Da)*(n+1);

[0086] Where σa is the porosity of the negative electrode sheet, Da is the thickness of the negative electrode current collector;

[0087] Diaphragm pore: Vs = σs*Ls*Ws*Hs*2(n+1), Ls is the diaphragm length, Ws is the diaphragm width;

[0088] Layer gap:

[0089] Vτ1=Hτ1*Lc*Wc*n;

[0090] Vτ2=Hτ2*Lc*Wc*n;

[0091] Overhang gap:

[0092] Vo=(Wa*La-Wc*Lc)*Hc*n;

[0093] Where σs is the porosity of the diaphragm, Ls is the length of the diaphragm, Ws is the width of the diaphragm, and Hs is the thickness of the diaphragm;

[0094] The injection volume M1 = (Vc + Va + Vs + Vτ1 + Vo) * ρ * k1;

[0095] Vτ1=(Hτ1)*Lc*Wc*2n;

[0096] Vo=(Wa*La-Wc*Lc)*Hc*n;

[0097] Among them, Vc is the pore of the positive electrode sheet, Va is the pore of the negative electrode sheet, Vs is the pore of the diaphragm, Vτ1 is the solid-solid layer gap, Vτ2 is the solid-liquid layer gap, Vo is the gap in the area where the negative electrode sheet exceeds the positive electrode sheet, ρ is the electrolyte density, k1=1-1.05, Lc is the length of the positive electrode sheet, Wc is the width of the positive electrode sheet, Wa is the width of the negative electrode sheet, and La is the length of the negative electrode sheet.

[0098] 2. Method for determining the secondary injection volume:

[0099] M2=(Hτ0-Hτ1)*Lc*Wc*n*ρ;

[0100] Where Hτ0 is the interlayer gap within the basic unit in the free state of the battery, and its value is 0.003mm-0.006mm;

[0101] 3. Calculation method of battery thickness:

[0102] H=n*Hc+(n+1)*Ha+2*(n+1)*Hs+Hτ2*n+2*Hv;

[0103] In this embodiment, the basic parameters of the battery are measured as shown in Table 1, and the parameters calculated by the above formula are shown in Table 2.

[0104] Example 2

[0105] The difference from Example 1 is that the basic parameters of the battery are shown in Table 1, and the parameters calculated by the above formula are shown in Table 2.

[0106] Example 3

[0107] The difference from Example 1 is that the basic parameters of the battery are shown in Table 1, and the parameters calculated by the above formula are shown in Table 2.

[0108] Example 4

[0109] The difference from Example 1 is that the basic parameters of the battery are shown in Table 1, and the parameters calculated by the above formula are shown in Table 2.

[0110] Comparative Example 1

[0111] The difference from Example 1 is that the first injection volume and the second injection volume are different, wherein the first injection volume is 100g and the second injection volume is 0g.

[0112] Comparative Example 2

[0113] The difference from Example 21 is that the first injection volume and the second injection volume are different, wherein the first injection volume is 126g and the second injection volume is 0g.

[0114] Comparative Example 3

[0115] The difference from Example 3 is that the first injection volume and the second injection volume are different, wherein the first injection volume is 122g and the second injection volume is 10g.

[0116] Comparative Example 4

[0117] The difference from Example 1 is that the secondary liquid injection amount is different, wherein the secondary liquid injection amount is 0 g.

[0118] Comparative Example 5

[0119] The difference from Example 1 is that the secondary liquid injection volume is different, wherein the secondary liquid injection volume is 5g.

[0120] Table 1

[0121]

[0122] Table 2

[0123]

[0124] Test example

[0125] The thickness of the battery cells of Examples 1-4 after formation was measured, and the errors between the calculated values ​​and the measured values ​​were calculated. The results are shown in Table 3.

[0126] Table 3

[0127]

[0128] The battery cells of Examples 1-3 and Comparative Examples 1-5 were subjected to 0.5C / 0.5C charge-discharge cycles at 25°C. The results of 1000 and 3000 cycles are shown in Table 4.

[0129] Table 4

[0130]

[0131] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining the liquid injection amount of a laminated battery, characterized in that: The injection volume includes the primary injection volume and the secondary injection volume; The method for determining the amount of liquid injected once comprises the following steps: a. Soak the dried positive and negative electrodes in the electrolyte. Measure the thickness of the positive electrode after soaking as Hc and the thickness of the negative electrode as Ha. b. The target number of layers of the bare battery cell is vacuum-encapsulated with aluminum-plastic film, and the thickness of the battery cell after encapsulation is measured as H0, then H0 = n*Hc+(n+1)*Ha+2*(n+1)*Hs+Hτ1*n+2*Hv; where n is the number of positive electrode layers, n+1 is the number of negative electrode layers, 2*(n+1) is the number of separator layers, Hτ1 is the solid-solid layer gap within the basic unit, Hs is the separator thickness, and Hv is the thickness of the aluminum-plastic film; an adjacent separator layer, a negative electrode layer, a separator layer, and a positive electrode layer constitute a basic unit; The one-time injection volume M1=(Vc+Va+Vs+Vτ1+Vo)*ρ*k1; Vτ1=Hτ1*Lc*Wc*n; Vτ2=Hτ2*Lc*Wc*n; Vo=(Wa*La-Wc*Lc)*Hc*n; Wherein, Vc is the pore of the positive electrode sheet, Va is the pore of the negative electrode sheet, Vs is the pore of the separator, Vτ1 is the solid-solid layer gap, Vτ2 is the solid-liquid layer gap, Vo is the gap of the negative electrode sheet beyond the positive electrode sheet, ρ is the electrolyte density, k1=1-1.05, Lc is the length of the positive electrode sheet, Wc is the width of the positive electrode sheet, Wa is the width of the negative electrode sheet, and La is the length of the negative electrode sheet; The secondary injection amount M2 = (Hτ0-Hτ1)*Lc*Wc*n*ρ; Where Hτ0 is the interlayer gap within the basic unit in the free state of the battery, and its value is 0.003mm-0.006mm.

2. The method for determining the liquid injection amount of a laminated battery according to claim 1, characterized in that: In step a, the water content of the dried positive electrode sheet is below 400 ppm, and the water content of the dried negative electrode sheet is below 300 ppm.

3. The method for determining the liquid injection amount of a laminated battery according to claim 1, wherein: In step a, the soaking time is 24-72 hours.

4. The method for determining the liquid injection amount of a laminated battery according to claim 1, wherein: In step b, the vacuum degree of the vacuum packaging is 50-120 kPa, and the vacuuming time is 30-50 s.

5. The method for determining the liquid injection amount of a laminated battery according to claim 1, characterized in that: Pore ​​of positive electrode sheet Vc=σc*Lc*Wc*(Hc-Dc)*n; Wherein, σc is the porosity of the positive electrode sheet, and Dc is the thickness of the positive electrode current collector.

6. The method for determining the liquid injection amount of a laminated battery according to claim 1, characterized in that: Negative plate pore Va=σa*La*Wa*(Ha-Da)*(n+1); Where σa is the porosity of the negative electrode sheet and Da is the thickness of the negative electrode current collector.

7. The method for determining the liquid injection amount of a laminated battery according to claim 1, characterized in that: Diaphragm pore Vs = σs*Ls*Ws*Hs*2*(n+1); Where σs is the porosity of the membrane, Ls is the length of the membrane, Ws is the width of the membrane, and Hs is the thickness of the membrane.

8. A method for calculating battery thickness, characterized in that: The steps include: a. Soak the dried positive and negative electrodes in the electrolyte. Measure the thickness of the positive electrode after soaking as Hc and the thickness of the negative electrode as Ha. b. Inject the target number of stacked cells with an electrolyte injection volume of M0, then pressurize and form them. After fully charging the battery and discharging it to 0% SOC, measure the battery thickness as H1; M0 = K0 * C0, where C0 is the design capacity of the battery cell; K0 is a constant, K0 for lithium iron phosphate batteries is 4.8g / Ah, and K0 for lithium nickel cobalt manganese oxide batteries or lithium nickel cobalt aluminum oxide batteries is 3.5g / Ah; the solid-liquid layer gap within the basic unit is Hτ2 = (H1-H0) / n; The battery thickness H is calculated by the following formula: H=n*Hc+(n+1)*Ha+2*(n+1)*Hs+Hτ2*n+2*Hv; Where n is the number of positive electrode layers, n+1 is the number of negative electrode layers, 2*(n+1) is the number of separator layers, Hc is the thickness of the positive electrode layer, Ha is the thickness of the negative electrode layer, Hs is the thickness of the separator, Hτ2 is the solid-liquid layer gap within the basic unit, and Hv is the thickness of the aluminum-plastic film.

9. The calculation method according to claim 8, characterized in that: In step b, the pressure of the pressurized formation is 0.08-0.1 MPa.

Images