CN116093251A - Lithium ion battery, design method of porosity of pole piece of lithium ion battery and application of lithium ion battery - Google Patents
Lithium ion battery, design method of porosity of pole piece of lithium ion battery and application of lithium ion battery Download PDFInfo
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- H01M4/00—Electrodes
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Abstract
The application relates to the technical field of lithium ion batteries, and discloses a lithium ion battery, a design method of porosity of a pole piece of the lithium ion battery and application of the lithium ion battery. The design method of the porosity of the lithium ion battery pole piece comprises the following steps: according to the formula: (sigma) 1 ‑σ 2 )*k 1 ＝σ 4 ‑σ 3 Design sigma 1 、σ 2 、σ 3 Sigma (sigma) 4 Value of, wherein the coefficient k 1 1 to 1.1; sigma (sigma) 1 Porosity of positive plate in 0% SOC state, sigma 2 Porosity of positive plate in 100% SOC state, sigma 3 Porosity of the negative plate in 0% SOC state, sigma 4 The porosity of the negative plate is 100% in SOC state. The design method of the lithium ion battery comprises the design method of the porosity. The design method can be applied to the manufacture of lithium ion batteriesIs a kind of medium. The porosity of the lithium ion battery meets the formula, and the battery has the characteristic of long cycle life because the porosity of the lithium ion battery meets the formula.
Description
Technical Field
The application relates to the technical field of lithium ion batteries, in particular to a design method of porosity of a lithium ion battery and a pole piece thereof and application of the design method.
Background
Along with the progress of science and technology and the improvement of consumer demands for living matters, people have increasingly high demands for long-cycle batteries. The electrolyte is the 'blood' of the battery, and is an important bridge for communicating the anode and the cathode to transmit lithium ions. In the lithium ion battery operation, electrolyte needs to infiltrate into the positive and negative plates and the diaphragm to conduct a channel between the positive and negative plates, thereby providing a passage for the intercalation and deintercalation of lithium ions.
In the process of charging and discharging the lithium ion battery, the positive and negative electrode materials shrink in volume and expand due to the intercalation-deintercalation of lithium ions of the positive and negative electrode plates, so that the battery has a breathing effect in the process of charging and discharging, and the porosity of the positive and negative electrode plates in the process of charging and discharging is changed, so that the positive and negative electrode plates in the battery show huff-puff phenomenon to electrolyte in the process of charging and discharging, if the positive and negative electrode plates are unreasonably designed in the process of huff-puff electrolyte, the huff-puff mismatch of the electrode plates can occur, the electrolytic distribution in the battery is uneven in the process of recycling the battery, and the impedance distribution in the electrode plates is uneven, so that the lithium precipitation is caused by uneven impedance distribution in the later period of the battery cycle, and the service life of the battery is deteriorated.
In the current design of lithium ion batteries, the total addition amount is calculated through the pores and the free amount of the positive and negative plates and the separator, and the problem that the battery shows throughput phenomenon on electrolyte in the charging and discharging process cannot be solved by the design.
In view of this, the present application is specifically proposed.
Disclosure of Invention
It is an object of the present application to provide a method for designing porosity of lithium ion batteries and pole pieces thereof, and applications thereof, to ameliorate at least one of the problems mentioned in the background.
The application is realized in such a way that:
in a first aspect, the present invention provides a method for designing the porosity of a lithium ion battery pole piece, comprising: according to the formula: (sigma) 1 -σ 2 )*k 1 ＝σ 4 -σ 3 Design sigma 1 、σ 2 、σ 3 Sigma (sigma) 4 Value of, wherein the coefficient k 1 1 to 1.1; sigma (sigma) 1 Porosity of positive plate in 0% SOC state, sigma 2 Porosity of positive plate in 100% SOC state, sigma 3 Porosity of the negative plate in 0% SOC state, sigma 4 The porosity of the negative plate is 100% in SOC state.
In an alternative embodiment, the method comprises:
(1) Taking two groups of batteries of the same system, and respectively adjusting to 0% and 100% SOC states;
(2) Disassembling two groups of batteries of the same system, and respectively measuring the thicknesses of positive and negative plates in 0% and 100% SOC states;
(3) Calculating the corresponding porosity according to the thicknesses of the positive and negative plates in the 0% and 100% SOC states measured in the step (2);
(4) Calculating the rebound rate of the positive and negative plates according to the thicknesses of the positive and negative plates in the 0% and 100% SOC states measured in the step (2), wherein the rebound rate is calculated according to the following formula:
S＝(d 1 -d 0 )/d 0 wherein d is 1 The thickness of the pole piece in the SOC state is 100 percent, d 0 The thickness of the pole piece is 0% of that of the SOC state;
(5) Checking whether the measured porosity satisfies the formula (sigma 1 -σ 2 )*k 1 ＝σ 4 -σ 3 ；
If not, changing d by adjusting the compaction density of the positive and negative plates 0 And calculating d by using the rebound rate calculated in the step (4) 1 Value according to d 0 And d 1 The value can be calculated to obtain sigma 1 、σ 2 、σ 3 Sigma (sigma) 4 The value is adjusted until the compaction density of the positive and negative plates is adjusted to ensure that the porosity of the positive and negative plates meets (sigma 1 -σ 2 )*k 1 ＝σ 4 -σ 3 。
In an alternative embodiment, the two sets of cells of the same system are two sets of cells after capacity division.
In a second aspect, the present invention provides a method for designing a lithium ion battery, including a method for designing a porosity of a lithium ion battery pole piece and a method for determining an electrolyte amount of the lithium ion battery according to the foregoing embodiments;
the method for determining the electrolyte amount of the lithium ion battery comprises the following steps:
according to the formula: m is M 1 ＝ρ 1 *(V 1 *σ 2 +V 2 *σ 4 *k 1 +V 3 *σ 5 )+Q 1 *k 2 Calculating to obtain electrolyte amount M 1 Wherein σ is 5 For diaphragm porosity, V 1 Is the volume of the positive plate dressing, V 2 Volume of dressing of negative electrode sheet, V 3 For the diaphragm volume ρ 1 To electrolyte density, Q 1 Designing capacity, k for battery 2 The value of the free electrode liquid quantity coefficient is 0.05-0.3 g/Ah.
In a third aspect, the present invention provides the use of a method as described in the previous embodiments in the manufacture of a lithium ion battery.
In an alternative embodiment, the positive electrode material of the lithium ion battery is selected from at least one of lithium cobaltate, ternary positive electrode material and lithium iron phosphate.
In an alternative embodiment, the negative electrode material of the lithium ion battery is selected from at least one of graphite, a silicon-based negative electrode material, and lithium titanate.
In alternative embodiments, the lithium ion battery is a pouch battery, prismatic battery, or cylindrical battery.
In a fourth aspect, the present invention provides a lithium ion battery, where the positive and negative electrode sheets of the lithium ion battery satisfy the formula: (sigma) 1 -σ 2 )*k 1 ＝σ 4 -σ 3 Wherein the coefficient k 1 1 to 1.1; sigma (sigma) 1 Porosity of positive plate in 0% SOC state, sigma 2 Porosity of positive plate in 100% SOC state, sigma 3 Porosity of the negative plate in 0% SOC state, sigma 4 The porosity of the negative plate is 100% in SOC state.
In an alternative embodiment, the amount of electrolyte of the lithium ion battery satisfies the formula: m is M 1 ＝ρ 1 *(V 1 *σ 2 +V 2 *σ 4 *k 1 +V 3 *σ 5 )+Q 1 *k 2 Wherein M is 1 For the electrolyte volume, sigma 5 For diaphragm porosity, V 1 Is the volume of the positive plate dressing, V 2 Volume of dressing of negative electrode sheet, V 3 For the diaphragm volume ρ 1 To electrolyte density, Q 1 Designing capacity, k for battery 2 The value of the free electrode liquid quantity coefficient is 0.05-0.3 g/Ah.
In an alternative embodiment, at least one of the following features (1) to (3) is further included:
(1) The positive electrode material of the lithium ion battery is at least one of lithium cobaltate, ternary positive electrode material and lithium iron phosphate;
(2) The negative electrode material of the lithium ion battery is at least one selected from graphite, silicon-based negative electrode material and lithium titanate;
(3) The lithium ion battery is a soft package battery, a square battery or a cylindrical battery.
The application has the following beneficial effects:
according to the method, through the optimal design of the pores of the positive and negative plates, when the porosity of the positive and negative plates meets the requirements of the formula, the electrolyte which is swallowed and spitted by the positive plate due to shrinkage-expansion can be basically and completely sucked back into the negative plate in the charge-discharge process, and likewise, the electrolyte which is swallowed and spitted by the negative plate due to shrinkage-expansion can be basically and completely sucked back into the positive plate, so that the redistributing probability of the electrolyte in the recycling process of the battery is reduced, and the design purpose of prolonging the recycling service life of the battery is further achieved.
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In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a graph of positive and negative plate porosity matches.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
The following specifically describes a design method of porosity of a lithium ion battery and a pole piece thereof and application thereof.
The design method for the porosity of the lithium ion battery pole piece provided by the embodiment of the application comprises the following steps:
according to the formula: (sigma) 1 -σ 2 )*k 1 ＝σ 4 -σ 3 Design sigma 1 、σ 2 、σ 3 Sigma (sigma) 4 Value of, wherein the coefficient k 1 1 to 1.1; sigma (sigma) 1 Porosity of positive plate in 0% SOC state, sigma 2 Porosity of positive plate in 100% SOC state, sigma 3 Porosity of the negative plate in 0% SOC state, sigma 4 The porosity of the negative plate is 100% in SOC state.
As shown in fig. 1, when the porosity of the positive and negative plates meets the requirement of the formula, the positive and negative plates can enable electrolyte which is swallowed and spitted by the positive plate due to shrinkage-expansion to be basically and completely sucked back into the negative plate in the charge-discharge process, and similarly, the electrolyte which is swallowed and spitted by the negative plate due to shrinkage-expansion can be basically and completely sucked back into the positive plate, so that the redistributing probability of the electrolyte in the recycling process of the battery is reduced, and the design purpose of prolonging the recycling service life of the battery is further achieved.
Compared with the prior art, in the prior art, the injection amount of the battery is controlled by controlling and calculating the amounts of the positive electrode plate, the negative electrode plate and the free electrolyte, the influence of the matching degree of the electrolyte amounts in the positive electrode plate and the negative electrode plate on the cycle performance of the battery is not noticed, if the porosities of the positive electrode plate and the negative electrode plate are not matched, the change of the porosities of the electrode plate is caused by the expansion and the contraction of the electrode plate in the cycle process, finally, the electrolyte in the battery is required to be redistributed in each charge and discharge, thus the difficult absorption of the electrode plate or the region with poor wettability is caused, black spots and lithium precipitation are caused at the battery interface, and finally, the battery is invalid.
Further, to ensure that the designed porosity can meet the above formula, the method specifically includes:
(1) Taking two groups of batteries of the same system, and respectively adjusting to 0% and 100% SOC states;
(2) Disassembling two groups of batteries of the same system, and respectively measuring the thicknesses of positive and negative plates in 0% and 100% SOC states;
(3) Calculating the corresponding porosity according to the thicknesses of the positive and negative plates in the 0% and 100% SOC states measured in the step (2);
the porosity is calculated by the following steps: porosity = [ thickness of pole piece per unit area of pole piece- (weight of pole piece dressing per unit area of pole piece dressing true density) ]/thickness of pole piece per unit area of pole piece.
(4) Calculating the rebound rate of the positive and negative plates according to the thicknesses of the positive and negative plates in the 0% and 100% SOC states measured in the step (2), wherein the rebound rate is calculated according to the following formula:
S＝(d 1 -d 0 )/d 0 wherein d is 1 The thickness of the pole piece in the SOC state is 100 percent, d 0 The thickness of the pole piece is 0% of that of the SOC state;
(5) Checking whether the measured porosity satisfies the formula (sigma 1 -σ 2 )*k 1 ＝σ 4 -σ 3 ；
If not, changing d by adjusting the compaction density of the positive and negative plates 0 And calculating d by using the rebound rate calculated in the step (4) 1 Value according to d 0 And d 1 The value can be calculated to obtain sigma 1 、σ 2 、σ 3 Sigma (sigma) 4 Value (d of known positive electrode sheet 0 And d 1 The value can be calculated to obtain sigma 1 、σ 2 A value; d of known negative electrode sheet 0 And d 1 The value can be calculatedObtaining sigma 3 、σ 4 Value) until the positive and negative electrode sheet compaction density is adjusted to satisfy the porosity (sigma) 1 -σ 2 )*k 1 ＝σ 4 -σ 3 。
Preferably, in order to avoid individual differences and ensure the accuracy of the measured results, the two groups of batteries of the same system are two groups of batteries after capacity division.
The positive and negative electrode plate matched porosity is obtained by adjusting the density of the positive and negative electrode, so that the electrolyte in the positive and negative electrode plates is matched, the phenomenon that the electrolyte in the battery is redistributed and sucked back in the process of cyclic charge and discharge is avoided, and the cyclic failure caused by poor infiltration effect is avoided. In the application, the purpose of designing and obtaining the lithium ion battery is achieved by reasonably optimizing the electrolyte quantity in the positive and negative plates.
The design method of the lithium ion battery provided by the embodiment of the application comprises the design method of the porosity of the lithium ion battery pole piece and the determination method of the electrolyte amount of the lithium ion battery;
the method for determining the electrolyte amount of the lithium ion battery comprises the following steps:
according to the formula: m is M 1 ＝ρ 1 *(V 1 *σ 2 +V 2 *σ 4 *k 1 +V 3 *σ 5 )+Q 1 *k 2 Calculating to obtain electrolyte amount M 1 Wherein σ is 5 For diaphragm porosity, V 1 Is the volume of the positive plate dressing, V 2 Volume of dressing of negative electrode sheet, V 3 For the diaphragm volume ρ 1 To electrolyte density, Q 1 Designing capacity, k for battery 2 The value of the free electrode liquid quantity coefficient is 0.05-0.3 g/Ah.
In the design process of the electrolyte injection amount of the lithium ion battery, whether the electrolyte is redistributed and sucked back due to expansion and shrinkage of the electrode plates in the charging and discharging process is considered, the porosity of the electrode plates is taken as an influence factor to be brought into the design range, and the pores of the positive electrode plates and the negative electrode plates are optimized, so that the electrolyte which is swallowed and spitted by the positive electrode plates due to shrinkage-expansion is completely sucked back into the negative electrode plates in the charging and discharging process, and the electrolyte which is swallowed and spitted by the negative electrode plates due to shrinkage-expansion is completely sucked back into the positive electrode plates, so that the lithium ion battery with the electrolyte redistributed back in the recycling process is reduced.
The embodiment of the application also provides an application of the design method of the lithium ion battery in manufacturing the lithium ion battery.
When the design method is applied to the manufacture of the lithium ion battery, the lithium ion battery with long cycle life can be manufactured.
Further, the positive electrode material of the lithium ion battery is selected from at least one of lithium cobaltate, ternary positive electrode material and lithium iron phosphate.
Further, the negative electrode material of the lithium ion battery is selected from at least one of graphite, a silicon-based negative electrode material and lithium titanate.
Further, the lithium ion battery is a soft package battery, a square battery or a cylindrical battery.
The positive and negative electrode plates of the lithium ion battery provided by the embodiment of the application satisfy the formula: (sigma) 1 -σ 2 )*k 1 ＝σ 4 -σ 3 Wherein the coefficient k 1 1 to 1.1; sigma (sigma) 1 Porosity of positive plate in 0% SOC state, sigma 2 Porosity of positive plate in 100% SOC state, sigma 3 Porosity of the negative plate in 0% SOC state, sigma 4 The porosity of the negative plate is 100% in SOC state.
The porosity of the positive plate and the negative plate of the lithium ion battery meets the formula, so that electrolyte which is swallowed and spitted by the positive plate due to shrinkage-expansion can be basically and completely sucked into the negative plate in the charging and discharging process, and likewise, electrolyte which is swallowed and spitted by the negative plate due to shrinkage-expansion can be basically and completely sucked into the positive plate, so that the electrolyte re-distribution probability of the battery in the recycling process is lower, and the recycling service life of the battery is longer.
Further, the amount of electrolyte of the lithium ion battery satisfies the formula: m is M 1 ＝ρ 1 *(V 1 *σ 2 +V 2 *σ 4 *k 1 +V 3 *σ 5 )+Q 1 *k 2 Wherein M is 1 For the electrolyte volume, sigma 5 For diaphragm porosity, V 1 Is the volume of the positive plate dressing, V 2 Volume of dressing of negative electrode sheet, V 3 For the diaphragm volume ρ 1 To electrolyte density, Q 1 Designing capacity, k for battery 2 The value of the free electrode liquid quantity coefficient is 0.05-0.3 g/Ah.
Through the porosity and the liquid injection amount of the electrode slice of reasonable design, when the liquid injection amount meets the formula, the electrolyte redistributing probability of the battery in the recycling process is lower, and the recycling service life of the battery is longer.
Further, the positive electrode material of the circulating lithium ion battery is at least one selected from lithium cobaltate, ternary positive electrode material and lithium iron phosphate; the negative electrode material of the lithium ion battery is at least one selected from graphite, silicon-based negative electrode material and lithium titanate; the lithium ion battery is a soft package battery, a square battery or a cylindrical battery.
The features and capabilities of the present application are described in further detail below in connection with the examples.
Examples
Taking two groups of batteries with model capacity of 8Ah after capacity division, and respectively adjusting to 0% and 100% SOC states;
disassembling the two groups of batteries, and respectively measuring the thicknesses of the positive electrode plate and the negative electrode plate in 0% SOC state and 100% SOC state to obtain the thicknesses of the positive electrode plate and the negative electrode plate in the 0% SOC state and the 100% SOC state respectively as 151 μm and 144 μm and 120 μm and 134 μm respectively; calculated, corresponding porosity sigma 1 、σ 2 、σ 3 Sigma (sigma) 4 The values are 33.6%, 29.4%, 36.3% and 41.4%, respectively, and the rebound rates of the positive and negative plates are 4.6% and 11.4%, respectively.
The porosity of the positive and negative plates is calculated to be unsatisfied with the formula (sigma) 1 -σ 2 )*k 1 ＝σ 4 -σ 3 ；
The positive and negative electrode plates are changed by adjusting the compaction density of the positive and negative electrode platesD of (2) 0 The values of (a) are 137.5 μm and 133.4 μm, respectively, and d of the positive and negative electrode sheets is calculated by using the above-mentioned rebound rate 1 The values are 4.5% and 11.5%, respectively, according to d above 0 And d 1 Calculating the value to obtain sigma 1 、σ 2 、σ 3 Sigma (sigma) 4 Values of 26.6%, 21.9%, 42.9% and 47.5%, respectively, satisfy (σ) 1 -σ 2 )*k 1 ＝σ 4 -σ 3 At this time k 1 The value was 1.02.
The true density was selected to be 1.20g/cm 3 According to formula M 1 ＝ρ 1 *(V 1 *σ 2 +V 2 *σ 4 *k 1 +V 3 *σ 5 )+Q 1 *k 2 Calculating to obtain electrolyte amount M 1 26.8g, wherein the separator porosity sigma 5 45% of positive electrode dressing volume V 1 25.6cm 3 Volume of negative electrode sheet dressing V 2 24.3cm 3 Diaphragm volume V 3 Electrolyte density ρ of 8.7 1 1.20g/cm 3 The cell design capacity 8.2Ah is the free electrode liquid quantity coefficient k 2 The value is 0.15g/Ah.
According to the porosity and the liquid injection amount of the battery, a new lithium ion battery is manufactured, the cycle life of the lithium ion battery is tested under the 1C cycle condition in the environment of 25+/-3 ℃, and the test result is that the capacity retention rate is 85% after 4000 cycles.
Comparative example 1
This comparative example is substantially identical to the examples, except that: the compaction density of the positive and negative electrode plates is not adjusted on the basis of the embodiment, sigma 1 、σ 2 、σ 3 Sigma (sigma) 4 The value is the porosity value, k, calculated after the battery is disassembled 1 The value was 1.22, and the remaining design method was exactly the same as in the example.
The porosity and the liquid injection amount designed according to the comparative example are manufactured to obtain a new lithium ion battery, and the cycle life of the lithium ion battery is tested under the 1C cycle condition in the environment of 25+/-3 ℃, and the test result is that the capacity retention rate is 80% in 3400 cycles.
Comparative example 2
This comparative example is substantially identical to the examples, except that: adjusting the compaction density of the positive and negative electrode plates to obtain sigma after adjustment 1 、σ 2 、σ 3 Sigma (sigma) 4 The values were 44.2%, 35.7%, 49.0% and 60.8%, respectively, and k was calculated 1 The value was 1.17, and the remaining design method was exactly the same as in the examples.
The porosity and the liquid injection amount designed according to the comparative example were manufactured to obtain a new lithium ion battery, and the cycle life of the lithium ion battery was tested under a 1C cycle condition in an environment of 25±3 ℃, and the test result was a cycle 3900 week capacity retention rate of 80%.
The cycle efficiency test results of the batteries prepared in the comparative examples and the two comparative examples show that the cycle efficiency of the batteries prepared in the examples is significantly better than that of the two comparative examples, which indicates that the porosity of the positive and negative electrode sheets is designed under the conditions required in the application, and the designed lithium ion battery has good cycle efficiency and long cycle life.
In summary, according to the design method for the porosity of the lithium ion battery and the pole piece thereof provided by the application, through optimally designing the porosity of the positive pole piece and the negative pole piece, when the porosity of the positive pole piece meets the requirements of the formula, the electrolyte swallowed and spitted by the positive pole piece due to shrinkage-expansion can be basically and completely sucked back into the negative pole piece in the charging and discharging process, and likewise, the electrolyte swallowed and spitted by the negative pole piece due to shrinkage-expansion can be basically and completely sucked back into the positive pole piece, so that the redistribution probability of the electrolyte in the recycling process of the battery is reduced, and the design purpose of prolonging the recycling service life of the battery is further achieved.
The lithium ion battery obtained through the design has a longer cycle service life due to lower redistribution probability of electrolyte in the charge and discharge processes.
The lithium ion battery provided by the application, because the porosities of the positive electrode plate and the negative electrode plate are specially designed, the electrolyte amounts in the positive electrode plate and the negative electrode plate are matched, the electrolyte in the battery can not be redistributed and sucked back in the circulating charge and discharge process, and the circulating failure caused by poor infiltration effect can be effectively avoided. Therefore, the lithium ion battery provided by the application has the characteristic of long cycle life.
The foregoing description is only of the preferred embodiments of the present application and is not intended to limit the same, but rather, various modifications and variations may be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.
Claims (10)
1. The design method of the porosity of the lithium ion battery pole piece is characterized by comprising the following steps:
according to the formula: (sigma) 1 -σ 2 )*k 1 ＝σ 4 -σ 3 Design sigma 1 、σ 2 、σ 3 Sigma (sigma) 4 Value of, wherein the coefficient k 1 1 to 1.1; sigma (sigma) 1 Porosity of positive plate in 0% SOC state, sigma 2 Porosity of positive plate in 100% SOC state, sigma 3 Porosity of the negative plate in 0% SOC state, sigma 4 The porosity of the negative plate is 100% in SOC state.
2. The method according to claim 1, characterized in that it comprises:
(1) Taking two groups of batteries of the same system, and respectively adjusting to 0% and 100% SOC states;
(2) Disassembling two groups of batteries of the same system, and respectively measuring the thicknesses of positive and negative plates in 0% and 100% SOC states;
(3) Calculating the corresponding porosity according to the thicknesses of the positive and negative plates in the 0% and 100% SOC states measured in the step (2);
(4) Calculating the rebound rate of the positive and negative plates according to the thicknesses of the positive and negative plates in the 0% and 100% SOC states measured in the step (2), wherein the rebound rate is calculated according to the following formula:
S＝(d 1 -d 0 )/d 0 wherein d is 1 The thickness of the pole piece in the SOC state is 100 percent, d 0 The thickness of the pole piece is 0% of that of the SOC state;
(5) Checking whether the measured porosity satisfies the formula (sigma 1 -σ 2 )*k 1 ＝σ 4 -σ 3 ；
If not, changing d by adjusting the compaction density of the positive and negative plates 0 And calculating d by using the rebound rate calculated in the step (4) 1 Value according to d 0 And d 1 The value can be calculated to obtain sigma 1 、σ 2 、σ 3 Sigma (sigma) 4 The value is adjusted until the compaction density of the positive and negative plates is adjusted to ensure that the porosity of the positive and negative plates meets (sigma 1 -σ 2 )*k 1 ＝σ 4 -σ 3 ；
Preferably, the two groups of batteries of the same system are two groups of batteries after capacity division.
3. The design method of the lithium ion battery is characterized by comprising the design method of the porosity of the lithium ion battery pole piece and the determination method of the electrolyte amount of the lithium ion battery according to claim 1 or 2;
the method for determining the electrolyte amount of the lithium ion battery comprises the following steps:
according to the formula: m is M 1 ＝ρ 1 *(V 1 *σ 2 +V 2 *σ 4 *k 1 +V 3 *σ 5 )+Q 1 *k 2 Calculating to obtain electrolyte amount M 1 Wherein σ is 5 For diaphragm porosity, V 1 Is the volume of the positive plate dressing, V 2 Volume of dressing of negative electrode sheet, V 3 For the diaphragm volume ρ 1 To electrolyte density, Q 1 The capacity is designed for the battery, k2 is the free electrode liquid quantity coefficient, and the value is 0.05-0.3 g/Ah.
4. Use of the method of claim 3 in the manufacture of a lithium ion battery.
5. The use according to claim 4, wherein the positive electrode material of the lithium ion battery is selected from at least one of lithium cobaltate, ternary positive electrode material and lithium iron phosphate.
6. The use according to claim 4, wherein the negative electrode material of the lithium ion battery is selected from at least one of graphite, silicon-based negative electrode material and lithium titanate.
7. The use according to claim 4, wherein the lithium ion battery is a pouch battery, a prismatic battery or a cylindrical battery.
8. The lithium ion battery is characterized in that positive and negative plates of the lithium ion battery meet the formula: (sigma) 1 -σ 2 )*k 1 ＝σ 4 -σ 3 Wherein the coefficient k 1 1 to 1.1; sigma (sigma) 1 Porosity of positive plate in 0% SOC state, sigma 2 Porosity of positive plate in 100% SOC state, sigma 3 Porosity of the negative plate in 0% SOC state, sigma 4 The porosity of the negative plate is 100% in SOC state.
9. The lithium ion battery of claim 8, wherein the amount of electrolyte of the lithium ion battery satisfies the formula: m is M 1 ＝ρ 1 *(V 1 *σ 2 +V 2 *σ 4 *k 1 +V 3 *σ 5 )+Q 1 *k 2 Wherein M is 1 For the electrolyte volume, sigma 5 For diaphragm porosity, V 1 Is the volume of the positive plate dressing, V 2 Volume of dressing of negative electrode sheet, V 3 For the diaphragm volume ρ 1 To electrolyte density, Q 1 Designing capacity, k for battery 2 The value of the free electrode liquid quantity coefficient is 0.05-0.3 g/Ah.
10. The lithium-ion battery of claim 8, further comprising at least one of the following features (1) - (3):
(1) The positive electrode material of the lithium ion battery is at least one of lithium cobaltate, ternary positive electrode material and lithium iron phosphate;
(2) The negative electrode material of the lithium ion battery is at least one selected from graphite, silicon-based negative electrode material and lithium titanate;
(3) The lithium ion battery is a soft package battery, a square battery or a cylindrical battery.
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| CN117633934A (en) * | 2023-11-24 | 2024-03-01 | 四川新能源汽车创新中心有限公司 | High-voltage-resistant all-solid-state battery and pole piece form design method thereof |
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| CN117633934A (en) * | 2023-11-24 | 2024-03-01 | 四川新能源汽车创新中心有限公司 | High-voltage-resistant all-solid-state battery and pole piece form design method thereof |
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