CN114976449A

CN114976449A - Long-life battery module and application thereof

Info

Publication number: CN114976449A
Application number: CN202111215064.XA
Authority: CN
Inventors: 暴旭; 马华; 刘峰; 卫晓燕; 陈卓
Original assignee: Tianjin EV Energies Co Ltd
Current assignee: Tianjin EV Energies Co Ltd
Priority date: 2021-10-19
Filing date: 2021-10-19
Publication date: 2022-08-30
Anticipated expiration: 2041-10-19
Also published as: CN114976449B

Abstract

The invention provides a long-life battery module and application thereof, wherein the module comprises at least three electric cores which are connected in series and/or in parallel, and each electric core comprises an outer electric core and an inner electric core; the capacity of the outer-layer battery core is larger than that of the inner-layer battery core. The service life of the module is prolonged, the use cost of the module is reduced, extra capacity is added to the outer battery core of the module, and the service life of the inner battery core can be fully exerted.

Description

Long-life battery module and application thereof

Technical Field

The invention relates to the field of power batteries, in particular to a long-life battery module and application thereof.

Background

Electric automobile on the market provides the electric quantity by a battery system, comprises a plurality of modules through the mode of establishing ties in the electric core system, and a module comprises a lot of electric cores again. During operation of the vehicle, each cell will experience a capacity fade, and its fade rate determines the life of the module. Meanwhile, the attenuation of the battery cell is influenced by a plurality of environments. The decay life of the module is determined by the lowest capacity cell in the module, which is typically the "barrel effect". The condition that often takes place is that the decay rate of electric core is not the same in the module, and the electric core of some special position often will decay more fast than other electric cores, has caused other electric cores although not reaching the end of life, but the module life-span has already ended.

Various studies have been made by those skilled in the art in order to improve the life of the module.

CN211530140U discloses a battery module and a battery pack. The size through setting for thermal barrier portion diminishes from the tip of battery module to the middle part of battery module along the array direction of electric core unit gradually, guarantees the temperature uniformity of the electric core unit at different positions, reaches the purpose of samming to effective increase of service life. The purpose of prolonging the service life is achieved by ensuring that the temperatures of all the battery cells are the same, but the disclosed invention can not achieve good improvement effect on the shortening of the service life of the module caused by the capacity attenuation of the module by a method for controlling the temperatures.

CN109920969A discloses energy storage module battery, energy storage system and electric core monomer of long-life realizes annotating the liquid through setting up certain structure to improve the life-span of module, but the method with high costs, the later stage is annotated again and is annotated liquid and consume greatly, the troublesome poeration to be not fit for disposable module and use.

CN108777329A discloses a lithium battery grouping method, which greatly reduces the capacity difference between each string of single battery cells and between battery modules by capacity mathematical sequencing and grouping, improves the utilization rate of the battery cell grouping, reduces errors and costs, and simultaneously ensures the integrity of the battery module and the battery system, thereby improving the stability and the service life of the battery system. The battery module and the battery system are integrally unified by matching the capacity sequence, so that the stability and the service life of the battery system are improved. But the calculation method is complex and the sequencing is troublesome.

How to simply and effectively prolong the service life of the module is an important research direction in the field.

Disclosure of Invention

The invention aims to provide a long-life battery module, which is characterized in that the module is specially designed through the capacity of an electric core, so that the service life of the module is prolonged to the end, and an inner layer electric core and an outer layer electric core can be at the same attenuation level, thereby prolonging the service life of the module.

In order to achieve the purpose, the invention adopts the following technical scheme:

one of the objectives of the present invention is to provide a battery module, which includes at least three cells connected in series and/or in parallel, where the cells include an outer layer cell and an inner layer cell.

The capacity of the outer-layer battery cell is larger than that of the inner-layer battery cell.

In the invention, because the battery cell capacity in the module is matched according to the battery cells close to the capacity, but because the battery cells are positioned in different positions in the module, the service temperature and the use binding force of the battery cells are different, so that the attenuation rates of the battery cells at different positions are different. Generally, the decay rate of the outermost battery cell of the module is the fastest, and when the outermost battery cell reaches the end life, the module life is also ended, but the rest battery cells do not reach the end life yet, and can be used continuously, so that the middle battery cell is wasted undoubtedly. Therefore, the module is formed by connecting n electric cores in series and parallel, and when the service life of the module is up to the end, the inner layer electric core and the outer layer electric core can be in an attenuation level through the specific design of the electric core capacity, so that the service life of the module is relatively prolonged.

As a preferred embodiment of the present invention, the capacity of the outer cell — the capacity of the inner cell is m.

The calculation method of m comprises the following steps:

the average initial capacity of the inner-layer cell is A1, the initial capacity of the outer-layer cell is A2, the average residual capacity of the inner-layer cell after charge-discharge cycling is B1, the residual capacity of the outer-layer cell is B2, and m is (A2-B2) - (A1-B1).

As a preferable aspect of the present invention, a2 is an initial capacity of the cell having the largest capacity difference before and after charge and discharge cycles in the outer-layer cell.

Preferably, B2 is the residual capacity of the cell with the largest capacity difference before and after charge and discharge cycles in the outer-layer cell.

As a preferred technical solution of the present invention, the inner-layer battery cell is all battery cells except the outer-layer battery cell.

As a preferable technical solution of the present invention, the charging in the charge-discharge cycle is constant current and constant voltage charging.

Preferably, the discharge in the charge-discharge cycle is a constant current and constant voltage discharge.

In a preferred embodiment of the present invention, the charging current in the charge/discharge cycle is 0.05 to 100C, and the charging current may be 0.05C, 1C, 5C, 10C, 15C, 20C, 25C, 30C, 35C, 40C, 45C, 50C, 55C, 60C, 65C, 70C, 75C, 80C, 85C, 90C, 95C, or 100C, but is not limited to the above-mentioned values, and other values not listed in the above-mentioned value range are also applicable.

Preferably, the discharge current in the charge and discharge cycle is 0.05 to 100C, and the charge current may be 0.05C, 1C, 5C, 10C, 15C, 20C, 25C, 30C, 35C, 40C, 45C, 50C, 55C, 60C, 65C, 70C, 75C, 80C, 85C, 90C, 95C, or 100C, but is not limited to the values listed, and other values not listed in the range of values are also applicable.

In a preferred embodiment of the present invention, the charging voltage in the charge/discharge cycle is 2 to 500V, and the voltage may be 2C, 10C, 20C, 35C, 40C, 50C, 60C, 70C, 80C, 90C, 100C, 150C, 200C, 250C, 300C, 350C, 400C, 450C, or 500C, but is not limited to the above-mentioned values, and other values not listed in the above-mentioned range of values are also applicable.

Preferably, the discharge voltage in the charge and discharge cycle is 16.5-25.8V, wherein the voltage may be 16.5V, 17V, 17.5V, 18V, 18.5V, 19V, 19.5V, 20V, 20.5V, 21V, 21.5V, 22V, 22.5V, 23V, 23.5V, 24V, 24.5V, 25V, 25.5V or 25.8V, but is not limited to the recited values, and other values not recited in the range of values are also applicable.

In a preferred embodiment of the present invention, the cutoff condition of the charge/discharge cycle is that the capacity of the outer layer cell is attenuated by 80 to 85%, and the capacity may be 80%, 80.5%, 81%, 81.5%, 82%, 82.5%, 83%, 83.5%, 84%, 84.5%, 85%, or the like, but is not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable, and more preferably 80 to 82%.

As a preferred technical scheme of the present invention, the battery cell includes any one of a soft-package battery cell, a plastic-shell battery cell, or an aluminum-shell battery cell.

It is another object of the present invention to provide a use of the battery module according to the first aspect, wherein the module is applied to the field of power batteries.

The module is applied to lithium ion batteries, lead-acid batteries, sodium ion batteries, lithium sulfur batteries and the like, and relates to devices utilizing electrochemical energy storage.

Compared with the prior art, the invention has the following beneficial effects:

the invention provides a long-life battery module which is long in service life and low in use cost.

Drawings

Fig. 1 is a cross-sectional structural diagram corresponding to the module in embodiments 1-3 of the present invention.

FIG. 2 is a graph of capacity calibration corresponding to the data of Table 1 in example 1 of the present invention.

FIG. 3 is a graph of capacity calibration corresponding to the data in Table 2 in example 1 of the present invention.

FIG. 4 is a graph of capacity calibration corresponding to the data of Table 1 in example 2 of the present invention.

FIG. 5 is a graph of capacity scaling corresponding to the data in Table 2 in example 2 of the present invention.

FIG. 6 is a graph of capacity scaling corresponding to the data of Table 1 in example 3 of the present invention.

FIG. 7 is a graph of capacity scaling corresponding to the data in Table 2 in example 3 of the present invention.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

Example 1

The embodiment provides a preparation method of a battery module, which comprises the following steps:

(1) for a VDA model 355 module, the size is 355 × 151 × 108mm, the module is composed of 12 cells in 2 parallel 6 strings, the capacity of 1 cell is 50Ah, and the size is 306 × 103 × 11.4 mm. The sectional structure is shown in fig. 1.

(2) The module stopped the test when the capacity was 80% of the initial capacity when cycled to 1600 weeks (constant current charging 100A to 25.8V, rest 30 minutes, constant current discharging 100A to 16.5V). Then each battery core is detached to carry out capacity calibration independently. The capacity at different positions is shown in fig. 2. (A represents the initial capacity and B represents the capacity of the cell when the module decays to 80%).

(3) A battery cell is designed and manufactured, and the capacity value of the battery cell is 52.46 Ah. When assembling the module, a high-capacity battery cell (designed at 52.46Ah) was placed at the outermost positions #1 and #12, and a battery cell having the original designed at 50Ah was placed at the positions #2 to #10, and the module was assembled.

(4) The module stops the test when the capacity reaches 80% of the initial capacity by cycling to 2133 weeks (constant current charging 100A to 25.8V, rest 30 minutes, constant current discharging 100A to 16.5V). This module has compensated more decrement in the outside because the capacity abundance of its outside is more, make full use of the life-span of every electric core and prolonged the life of module. The capacity at different positions is shown in fig. 3. (A represents the initial capacity, B represents the capacity of the cell at which the module decays to 80%)

Example 2

(2) The module stopped the test when the capacity was 80% of the initial capacity by cycling to 2000 weeks (constant current charge 74A to 25.8V, rest 30 minutes, constant current discharge 74A to 16.5V). And then each battery core is detached to carry out capacity calibration independently.

(3) A battery cell is designed and manufactured, and the capacity value of the battery cell is 38.9 Ah. When assembling the module, a high-capacity cell (designed at 38.9Ah) was placed at the outermost positions #1 and #12, and a cell having the original designed at 50Ah was placed at the positions #2 to #10, so that the module was assembled.

(4) The module was stopped when the capacity was 80% of the initial capacity by cycling to 2400 weeks (constant current charge 74A to 25.8V, rest 30 minutes, constant current discharge 74A to 16.5V). This module has compensated more decrement in the outside because the capacity abundance of its outside is more, make full use of the life-span of every electric core and prolonged the life of module. The comparison results are shown in fig. 4 and 5.

Example 3

(1) for a VDA model 355 module, the size is 355 × 151 × 108mm, the module is composed of 12 cells in 2-to-6 strings, the capacity of 1 cell is 78Ah, and the size is 306 × 103 × 11.4 mm. The sectional structure is shown in fig. 1.

(2) The module stopped the test when the capacity was 80% of the initial capacity when cycled up to 1500 weeks (constant current charge 156A to 25.8V, rest 30 minutes, constant current discharge 156A to 16.5V). Then each battery core is detached to carry out capacity calibration independently.

(3) A battery cell is designed and manufactured, and the capacity value of the battery cell is 80.3 Ah. When assembling the module, a high-capacity cell (designed at 80.3Ah) was placed at the outermost positions #1 and #12, and a cell having an original designed at 50Ah was placed at the positions #2 to #10, so that the module was assembled.

(4) The module stops the test when the capacity is 80% of the initial capacity when cycling to 1800 weeks (constant current charging 156A to 25.8V, rest 30 minutes, constant current discharging 156A to 16.5V). This module has compensated more decrement in the outside because the capacity abundance of its outside is more, make full use of the life-span of every electric core and prolonged the life of module. The comparison results are shown in fig. 6 and 7.

The capacity calibration is performed on each cell in the step (2) of examples 1 to 3, the capacity at different positions is shown in table 1, the m value is calculated by using the formula m ═ from (a2-B2) - (a1-B1), and then the module in the step (3) is involved, and the capacity calibration is performed on each cell in the step (4), and the capacity at different positions is shown in table 2. Wherein, A represents the initial capacity, and B represents the capacity of the battery cell after the module attenuation.

TABLE 1

TABLE 2

Compared with the prior art, the service life of the module is prolonged, the use cost of the module is reduced, extra capacity is added to the battery cell on the outer layer of the module, and the service life of the battery cell on the inner layer can be fully played.

The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.

Claims

1. A battery module is characterized in that the module comprises at least three cells connected in series and/or in parallel, wherein each cell comprises an outer cell and an inner cell;

2. The battery module according to claim 1, wherein the capacity of the outer layer cell — the capacity of the inner layer cell is m;

the calculation method of m comprises the following steps:

3. The battery module according to claim 2, wherein the a2 is an initial capacity of a cell with a largest capacity difference before and after charge and discharge cycles in the outer cell;

4. The battery module according to any one of claims 1 to 3, wherein the inner cell is all cells except the outer cell.

5. The battery module according to any one of claims 2 to 4, wherein the charging in the charge-discharge cycle is constant-current constant-voltage charging;

6. The battery module according to any one of claims 2 to 5, wherein the charging current in the charge-discharge cycle is 0.05 to 100C;

preferably, the discharge current in the charge-discharge cycle is 0.05 to 100C.

7. The battery module according to any one of claims 2 to 6, wherein the charging voltage in the charge-discharge cycle is 2 to 500V;

preferably, the discharge voltage in the charge-discharge cycle is 16.5 to 25.8V.

8. The battery module according to any one of claims 2 to 7, wherein the cut-off condition of the charge-discharge cycle is that the capacity attenuation of the outer-layer cell is 80-85%, and more preferably 80-82%.

9. The battery module of any of claims 1-8, wherein the cell comprises any of a pouch cell, a plastic shell cell, or an aluminum shell cell.

10. Use of a battery module according to any of claims 1 to 9 in the field of power batteries.