阅读说明：本技术 电池的设计方法 (Design method of battery ) 是由 旷理政 刘贵军 谭祖宪 康健强 赵人艺 于 2020-05-08 设计创作，主要内容包括：本发明实施例公开了一种电池的设计方法,包括：将参照电池的正极极片、负极极片的厚度作为原始值,等比例地乘以厚度变化比例系数；依据等体积的原则,确定新的极片的面积；根据新的极片的面积、新的正极极片的厚度和预设的活性物质的载入量,确新的电池容量；根据新的正极极片的厚度和新的负极极片的厚度、新的极片的面积和新的电池容量,确定电池模型；根据电池模型,仿真电池的电性能,以确定各种倍率下的比能量密度；根据电池模型,仿真电池的热性能,热性能包括不同放电倍率下不同散热条件下,电池的最高温升和最大温差；改变厚度变化比例系数,重复上述步骤；选择其中一个厚度变化比例系数作为待设计电池对应的厚度变化比例系数。(The embodiment of the invention discloses a design method of a battery, which comprises the following steps: taking the thicknesses of the positive pole piece and the negative pole piece of the reference battery as original values, and multiplying the original values by a thickness change proportion coefficient in an equal proportion manner; determining the area of a new pole piece according to the equal volume principle; determining the new battery capacity according to the area of the new pole piece, the thickness of the new positive pole piece and the preset loading amount of the active substance; determining a battery model according to the thickness of the new positive pole piece, the thickness of the new negative pole piece, the area of the new pole piece and the new battery capacity; simulating the electrical performance of the battery according to the battery model to determine the specific energy density under various multiplying powers; according to the battery model, simulating the thermal performance of the battery, wherein the thermal performance comprises the highest temperature rise and the maximum temperature difference of the battery under different heat dissipation conditions under different discharge rates; changing the thickness change proportion coefficient, and repeating the steps; and selecting one of the thickness change proportionality coefficients as the thickness change proportionality coefficient corresponding to the battery to be designed.)

1. A method of designing a battery, comprising:

s1, obtaining parameters of a reference battery, wherein the parameters of the reference battery comprise the thicknesses of the positive pole piece and the negative pole piece;

s2, taking the thicknesses of the positive pole piece and the negative pole piece of the reference battery as original values, and multiplying the original values by a thickness change proportion coefficient in an equal proportion manner to obtain the thickness of a new positive pole piece and the thickness of a new negative pole piece;

s3, determining the area of the new pole piece according to the principle of equal volume, the thickness of the new positive pole piece and the thickness of the new negative pole piece;

s4, determining the new battery capacity according to the area of the new pole piece, the thickness of the new positive pole piece and the preset loading amount of the active substance;

s5, determining a battery model according to the thickness of the new positive pole piece, the thickness of the new negative pole piece, the area of the new pole piece and the new battery capacity;

s6, simulating the electrical performance of the battery according to the battery model to determine the specific energy density under various multiplying powers, wherein the electrical performance comprises charge and discharge curves under different multiplying powers;

s7, simulating the thermal performance of the battery according to the battery model, wherein the thermal performance comprises the highest temperature rise and the maximum temperature difference of the battery under different discharge rates and different heat dissipation conditions;

s8, changing the thickness change proportion coefficient, and repeating S2-S7;

s9: according to the new battery capacity corresponding to each thickness change proportionality coefficient, the specific energy density under various multiplying powers, the highest temperature rise and the maximum temperature difference of the battery and the preset parameters of the battery to be designed, one of the thickness change proportionality coefficients is selected as the thickness change proportionality coefficient corresponding to the battery to be designed so as to determine the thicknesses of the positive pole piece and the negative pole piece of the battery to be designed, wherein the parameters of the battery to be designed comprise: rated capacity, specific energy, maximum temperature rise under preset heat dissipation conditions and maximum temperature difference.

2. The method of claim 1, wherein the thickness variation scaling factor is in a range of 0.2 to 5.

3. The method of claim 1, wherein the determining the area of the new pole piece according to the equal volume principle, the thickness of the new positive pole piece and the thickness of the new negative pole piece comprises:

when the thickness of pole piece changes, the area of pole piece changes along with it, and the width of pole piece is unchangeable, and the length of pole piece changes, and the total volume of pole piece is:

V＝BL(Ma+a+s+c+Mc)；

where B is the width of the electrode sheet, L is the length of the electrode sheet, Ma is the thickness of the negative electrode current collector, Mc is the thickness of the positive electrode current collector, a is the thickness of the negative electrode, c is the thickness of the positive electrode, s is the thickness of the separator, and when the positive and negative electrode thicknesses are X times the original values, i.e., ' a + ' c ═ X (a + c), L ' ═ L (Ma + a + s + c + Mc)/(Ma + Xa + s + Xc + Mc).

4. The method of claim 1, wherein the reference battery is a lithium battery and the new battery capacity Q is a capacity of the lithium battery_capacityDetermined by the following equation:

Q_capacity＝FA_{e s c}C_s,max△x；

wherein A is_eThe electrode area is BL, F is the faraday constant,_sis active substance volume fraction, C_s,maxThe maximum intercalation lithium ion concentration of the electrode, c the thickness of the positive electrode, and △ x the variation range of the lithium ion concentration.

5. The method of claim 1, wherein after S1 and before S2, the method further comprises:

and establishing an electrochemical thermal coupling model of the reference battery, and determining a charging curve and a discharging curve of the reference battery and a highest temperature change curve and a lowest temperature change curve of the reference battery in the charging and discharging processes based on simulation.

Technical Field

The invention relates to the field of batteries, in particular to a design method of a battery.

Background

The performance of the battery includes electrical and thermal properties and internal structure of the battery. The battery structure comprises a macroscopic structure such as the shape, the geometric size, the arrangement mode of a pole piece and the like, and also comprises a microscopic structure such as the thickness of the pole piece, the particle size of an active material, the configuration proportion of various materials and the like. Designing a qualified battery is a very tedious and difficult task, and even on the premise that the macrostructure is determined, a large number of comparisons and orthogonal experiments are needed to determine the microstructure. The experimental method is time-consuming and labor-consuming, and wastes a large amount of resources.

The thickness of the battery pole piece has a significant effect on the performance of the battery. Generally, the thicker the battery pole piece, the larger the capacity, but the high-rate charging and discharging performance is deteriorated, meanwhile, the internal resistance of the battery is also increased, the heat emitted under the same working condition is increased, and the thermal performance is deteriorated, and vice versa. Therefore, the design of the thickness of the pole piece is a pair of contradictions, and the choice needs to be made according to the actual use condition. In practice, the thickness of the battery is usually determined by the experience of engineers or experimentally.

Disclosure of Invention

In view of the above technical problems, embodiments of the present invention provide a method for designing a battery.

The embodiment of the invention provides a design method of a battery, which comprises the following steps:

s1, obtaining parameters of a reference battery, wherein the parameters of the reference battery comprise the thicknesses of the positive pole piece and the negative pole piece;

s2, taking the thicknesses of the positive pole piece and the negative pole piece of the reference battery as original values, and multiplying the original values by a thickness change proportion coefficient in an equal proportion manner to obtain the thickness of a new positive pole piece and the thickness of a new negative pole piece;

s3, determining the area of the new pole piece according to the principle of equal volume, the thickness of the new positive pole piece and the thickness of the new negative pole piece;

s4, determining the new battery capacity according to the area of the new pole piece, the thickness of the new positive pole piece and the preset loading amount of the active substance;

s5, determining a battery model according to the thickness of the new positive pole piece, the thickness of the new negative pole piece, the area of the new pole piece and the new battery capacity;

s6, simulating the electrical performance of the battery according to the battery model to determine the specific energy density under various multiplying powers, wherein the electrical performance comprises charge and discharge curves under different multiplying powers;

s7, simulating the thermal performance of the battery according to the battery model, wherein the thermal performance comprises the highest temperature rise and the maximum temperature difference of the battery under different discharge rates and different heat dissipation conditions;

s8, changing the thickness change proportion coefficient, and repeating S2-S7;

s9: according to the new battery capacity corresponding to each thickness change proportionality coefficient, the specific energy density under various multiplying powers, the highest temperature rise and the maximum temperature difference of the battery and the preset parameters of the battery to be designed, one of the thickness change proportionality coefficients is selected as the thickness change proportionality coefficient corresponding to the battery to be designed so as to determine the thicknesses of the positive pole piece and the negative pole piece of the battery to be designed, wherein the parameters of the battery to be designed comprise: rated capacity, specific energy, maximum temperature rise under preset heat dissipation conditions and maximum temperature difference.

Optionally, the thickness variation proportionality coefficient is in a range of 0.2-5.

Optionally, the determining the area of the new pole piece according to the principle of equal volume, the thickness of the new positive pole piece and the thickness of the new negative pole piece includes:

when the thickness of pole piece changes, the area of pole piece changes along with it, and the width of pole piece is unchangeable, and the length of pole piece changes, and the total volume of pole piece is:

V＝BL(Ma+a+s+c+Mc)；

where B is the width of the electrode sheet, L is the length of the electrode sheet, Ma is the thickness of the negative electrode current collector, Mc is the thickness of the positive electrode current collector, a is the thickness of the negative electrode, c is the thickness of the positive electrode, s is the thickness of the separator, and when the positive and negative electrode thicknesses are X times the original values, i.e., ' a + ' c ═ X (a + c), L ' ═ L (Ma + a + s + c + Mc)/(Ma + Xa + s + Xc + Mc).

Optionally, the reference battery is a lithium battery, and the new battery capacity Q is_capacityDetermined by the following equation:

Q_capacity＝FA_{e s c}C_s,max△x；

wherein A is_eThe electrode area is BL, F is the faraday constant,_sis active substance volume fraction, C_s,maxThe maximum intercalation lithium ion concentration of the electrode, c the thickness of the positive electrode, and △ x the variation range of the lithium ion concentration.

Optionally, after S1, before S2, the method further comprises:

and establishing an electrochemical thermal coupling model of the reference battery, and determining a charging curve and a discharging curve of the reference battery and a highest temperature change curve and a lowest temperature change curve of the reference battery in the charging and discharging processes based on simulation.

In the technical scheme provided by the embodiment of the invention, the method for designing the battery by selecting the thickness is adopted, namely, the simulation technology is adopted to simulate the electric and thermal properties of the battery with different pole piece thicknesses, and the proper thickness is selected according to the actual requirement.

Drawings

Fig. 1 is a schematic method flow diagram of a battery design method according to an embodiment of the invention;

FIG. 2 is a graph of battery rated capacity versus relative thickness in an embodiment of the present invention;

FIG. 3 is a graph of discharge curves of a battery 1C with different anode and cathode thicknesses according to an embodiment of the present invention;

FIG. 4 is a graph of the discharge curve of a battery 3C with different anode and cathode thicknesses according to an embodiment of the present invention;

fig. 5 shows a temperature distribution at the end of discharge of the 1.5 battery 3C (h 10Wm-2K-1) according to an embodiment of the present invention;

FIG. 6 is a graph of specific energy to 1C discharge versus relative thickness in an embodiment of the present invention;

FIG. 7 is a graph showing the relationship between the maximum temperature rise and the relative thickness for different heat transfer coefficients in an embodiment of the present invention;

FIG. 8 is a graph showing the relationship between the maximum temperature difference and the relative thickness for different heat transfer coefficients according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the following embodiments may be combined without conflict.

The design method of the battery provided by the embodiment of the invention can be suitable for the design of the lithium battery, but is not limited to the lithium battery, and can also be suitable for the design of other types of batteries.

In addition, the embodiment of the invention requires that other microscopic and macroscopic parameters of the battery are fixed, and the microscopic parameters comprise: the composition and proportion of various materials, the properties of the materials, the particle size of solid materials and the like, and macroscopic parameters comprise: the appearance and the geometric dimension of the battery, the winding or stacking mode of the pole pieces, the size and the appearance of the pole lugs, the connection mode of the pole lugs and the pole columns and the like.

Referring to fig. 1, a method for designing a battery according to an embodiment of the present invention may include the following steps:

s1, acquiring parameters of a reference battery, wherein the parameters of the reference battery comprise the thicknesses of the positive pole piece and the negative pole piece;

illustratively, the reference cell is a widely and largely used cell, such as a cylindrical 18650 cell.

Further, the parameters of the reference battery may further include: capacity, charge and discharge curves at different rates, open circuit voltage, etc.

S2, taking the thicknesses of the positive pole piece and the negative pole piece of the reference battery as original values, and multiplying the original values by a thickness change proportion coefficient in an equal proportion to obtain the thickness of a new positive pole piece and the thickness of a new negative pole piece;

optionally, the thickness variation proportionality coefficient (hereinafter, may be abbreviated as X, and may also be referred to as magnification) has a value range of 0.2-5; it should be understood that the value range of X may be set to other values.

The thickness of the positive and negative electrodes of the battery is actually changed by changing the size of X, and for example, when X is 2, the thickness of the positive and negative electrodes is 2 times the original value.

S3, determining the area of a new pole piece according to the principle of equal volume, the thickness of the new positive pole piece and the thickness of the new negative pole piece;

optionally, determining the area of the new pole piece according to the principle of equal volume, the thickness of the new positive pole piece and the thickness of the new negative pole piece includes:

when the thickness of pole piece changes, the area of pole piece changes along with it, and the width of pole piece is unchangeable, and the length of pole piece changes, and the total volume of pole piece is:

V＝BL(Ma+a+s+c+Mc) (1)；

in the formula (1), B is a width of the electrode sheet, L is a length of the electrode sheet, Ma is a thickness of the negative electrode current collector, Mc is a thickness of the positive electrode current collector, a is a thickness of the negative electrode, c is a thickness of the positive electrode, s is a thickness of the separator, and when the positive and negative electrode thicknesses are X times of the original values, i.e., ' a + ' c ═ X (a + c), and L ' ═ L (Ma + a + s + c + Mc)/(Ma + Xa + s + Xc + Mc).

S4, determining the new battery capacity according to the area of the new pole piece, the thickness of the new positive pole piece and the preset loading amount of the active substance;

alternatively, the reference battery is a lithium battery, and the new battery capacity Q_capacityDetermined by the following equation:

Q_capacity＝FA_{e s c}C_s,max△x (2)；

in the formula (2), A_eThe electrode area is BL, F is the faraday constant,_sis active substance volume fraction, C_s,maxMaximum intercalation of lithium ions for the electrodeUnder the condition that the thicknesses of the diaphragm and the current collector are not changed, the volume of the battery is ensured to be unchanged, the thickness of the pole piece is increased, and meanwhile, the area of the pole piece and the capacity of the lithium ion battery are correspondingly changed.

S5, determining a battery model according to the thickness of the new positive pole piece, the thickness of the new negative pole piece, the area of the new pole piece and the new battery capacity;

s6, simulating the electrical performance of the battery according to the battery model to determine the specific energy density under various multiplying powers, wherein the electrical performance comprises charge and discharge curves under different multiplying powers;

s7, simulating the thermal performance of the battery according to the battery model, wherein the thermal performance comprises the highest temperature rise and the maximum temperature difference of the battery under different heat dissipation conditions under different discharge rates;

the heat dissipation conditions are embodied by heat dissipation coefficients, and different heat dissipation coefficients correspond to different heat dissipation conditions.

S8, changing the thickness change proportion coefficient, and repeating S2-S7;

s9: according to the new battery capacity corresponding to each thickness change proportionality coefficient, the specific energy density under various multiplying powers, the highest temperature rise and the maximum temperature difference of the battery and the preset parameters of the battery to be designed, one of the thickness change proportionality coefficients is selected as the thickness change proportionality coefficient corresponding to the battery to be designed so as to determine the thicknesses of the positive pole piece and the negative pole piece of the battery to be designed, and the parameters of the battery to be designed comprise: rated capacity, specific energy, maximum temperature rise under preset heat dissipation conditions and maximum temperature difference.

Optionally, after S1, before S2, the method further comprises: and establishing an electrochemical thermal coupling model of the reference battery, and determining a charging curve and a discharging curve of the reference battery and a highest temperature change curve and a lowest temperature change curve of the reference battery in the charging and discharging processes based on simulation.

In the embodiment of the invention, the same simulation software, such as COMSOL or the like, is adopted for simulation.

Illustratively, according to application requirements, a 18650 type ternary lithium ion battery needs to be used, and the following performances are provided for a single batteryIndexes are as follows: rated capacity is more than or equal to 2Ah, specific energy of 1C discharge is more than or equal to 180wh/Kg, and heat exchange coefficient h is approximately equal to 50Wm^-2K^-1) The maximum temperature rise is less than or equal to 8K and the maximum temperature difference is less than or equal to 2K when the 3C discharge is finished. Parameters of the battery to be designed: rated capacity of 1.78Ah, specific energy of 1C discharge of 156.4wh/Kg, positive and negative thickness of 36.55 μm and 40 μm, respectively, and electrode area of 1020.41cm². On the premise of not changing other process parameters, the novel battery is designed by changing the thicknesses of the positive electrode and the negative electrode so as to meet the required performance indexes, and the method specifically comprises the following steps:

1) and taking the thicknesses of the anode and the cathode of the reference battery as original values, multiplying the original values by X in an equal proportion, wherein the value of X is 0.75, 1, 1.5, 2, 2.5, 3 and 3.5.

2) The battery capacity and other parameters after the thickness was changed were calculated according to the formula (2), and the results are shown in table 1, and the relationship between the relative thicknesses of the positive and negative electrodes and the capacity is shown in fig. 2.

TABLE 1 relationship between the positive and negative thickness and the change of the capacity and electrode area

X	Negative pole (mum)	Positive electrode (mum)	Area Ae (cm) of the pole piece2)	Capacity (Ah)
					0.75	30	27.42	1202.21	1.57
1	40	36.55	1020.41	1.78
					1.5	60	54.83	783.45	2.05
2	80	73.10	635.81	2.22
					2.5	100	91.38	534.99	2.33
3	120	109.65	461.77	2.41
					3.5	140	127.93	348.56	2.48

3) The battery parameters to be changed include: the positive and negative electrode thicknesses, electrode areas, and capacities were updated in a 18650 li-ion electrochemical-electric coupling model in COMSOL software, and 1C and 3C discharge curves were simulated as shown in fig. 3 and 4 (in fig. 3, the curves from top to bottom are open-circuit voltage, X ═ 0.75, X ═ 1, X ═ 1.5, X ═ 2, X ═ 2.5, X ═ 3, and X ═ 3.5, respectively; in fig. 4, X ═ 0.75, X ═ 1, X ═ 1.5, X ═ 2, X ═ 2.5, X ═ 3, X ═ 3.5, and open-circuit voltage, respectively), and the temperature curves of 3C discharge under different heat transfer coefficients, as shown in fig. 5.

4) The specific energy at 1C discharge was calculated from the 1C discharge curve, and its relationship with the relative thickness is shown in fig. 6.

5) And according to the temperature curve, respectively taking the maximum temperature rise and the maximum temperature difference, and the relationship graphs of the maximum temperature rise and the maximum temperature difference and the relative thickness are shown in figures 7 and 8.

6) From the conclusions of fig. 2, 5, 7, 8, in combination with the target requirements, it can be concluded that when X ═ 1.5 can satisfy the requirements, i.e. the positive and negative electrode thicknesses of the battery to be designed are respectively: 54.83 μm and 60 μm.

The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.