阅读说明：本技术 电池包、方法和车辆 (Battery pack, method and vehicle ) 是由 王林峰 方杰 曾士哲 周泽润 罗文娟 何冲 王贤鹏 韩琳 于 2021-01-08 设计创作，主要内容包括：本发明提供了电池包、方法和车辆。所述电池包具有电芯组(100),其中,所述电芯组(100)包括磷酸铁锂电芯(A)和三元锂离子电芯(B),其中,所述磷酸铁锂电芯(A)和所述三元锂离子电芯(B)彼此串联设置。(The invention provides a battery pack, a method and a vehicle. The battery pack is provided with a battery pack (100), wherein the battery pack (100) comprises a lithium iron phosphate battery cell (A) and a ternary lithium ion battery cell (B), and the lithium iron phosphate battery cell (A) and the ternary lithium ion battery cell (B) are connected in series with each other.)

1. The utility model provides a battery pack, battery pack has electric core group (100), its characterized in that, electric core group (100) includes lithium iron phosphate core (A) and ternary lithium ion battery cell (B), wherein, lithium iron phosphate core (A) with ternary lithium ion battery cell (B) establish ties each other and sets up.

2. The battery pack according to claim 1, wherein the lithium iron phosphate cells (A) and the ternary lithium ion cells (B) are arranged in a one-to-one alternating arrangement with each other.

3. The battery pack according to claim 1, wherein two lithium iron phosphate cells (a) and one ternary lithium ion cell (B) are arranged in series.

4. The battery pack according to claim 1, wherein the electric core pack (100) has only one ternary lithium ion cell (B).

5. The battery pack according to claim 1, wherein the lithium iron phosphate cells (a) and the ternary lithium ion cells (B) are arranged in a row with respect to each other.

6. A method for measuring the state of charge of a battery pack, wherein the battery pack is according to any one of claims 1 to 5, the method comprising:

carrying out ampere-hour integral calculation when the battery pack is charged and discharged; and/or

Correcting the state of charge calculation with the open circuit voltage of the ternary lithium ion cell (B) with the battery pack at a state of charge of 5% to 95% during resting of the battery pack; and/or

Correcting the state of charge calculation with the open circuit voltages of the lithium iron phosphate cell (a) and the ternary lithium ion cell (B) when the battery pack is at a state of charge of 0% to 5% or 95% to 100% while it is at rest.

7. The method of claim 6, wherein the calculation of the ampere-hour integral is performed using a resistive shunt.

8. A vehicle, characterized in that the vehicle has a battery pack according to any one of claims 1 to 5.

Technical Field

The invention belongs to the technical field of new energy automobiles, and particularly relates to a battery pack, a method and a vehicle. In particular, the invention relates to a high-performance battery design scheme formed by combining battery cells of different chemical systems and a method for improving the measurement accuracy of the state of charge of a lithium iron phosphate battery pack.

Background

In order to improve the energy density of the battery pack and increase the endurance mileage and power output of the electric automobile, the ternary lithium ion battery becomes a main technical route of the industry and becomes the first choice of most new energy automobiles in a quite long period of time. However, with the large-scale use of ternary lithium ion batteries, many battery safety accidents occur in the market. Due to the inherent characteristics of ternary lithium ion batteries, their safety risks cannot be fundamentally addressed in a short period of time. The lithium iron phosphate battery has been paid attention again due to its outstanding high safety and low cost, and has become the focus of research.

However, lithium iron phosphate has the inherent characteristic that an SOC-OCV (state of charge-open circuit voltage) curve is very gentle, and SOC correction can be performed relatively accurately only when the battery is fully charged or discharged. In actual use, the SOC calculation accuracy is poor particularly at low temperature, and the cruising range is greatly affected.

In the case of using the lithium iron phosphate battery pack, due to inaccurate SOC calculation, charging time estimation is inaccurate or charging is impossible, the deviation of the mileage during discharging is large, and users need to perform full charging and full discharging periodically to improve SOC calculation accuracy, which causes great complaints to the users.

And the OCV of the ternary lithium ion battery cell is accurately identified at different temperatures and different SOC intervals, and the standing waiting time can be greatly shortened through calibration.

CN111490304A provides a battery equalization enabling method, device, storage medium and battery pack. Judging whether a balancing instruction is received or not; if the balancing instruction is judged not to be received, judging whether the cell type of the single battery comprises a lithium iron phosphate cell; if the battery cell type is judged to comprise the lithium iron phosphate battery cell, judging whether the measured change value of the state of charge of the battery cell is smaller than a specified threshold value; if the change value of the state of charge is smaller than the specified threshold value, judging whether the obtained residual equilibrium capacity of the single battery is larger than the set calibration capacity; and if the residual equilibrium capacity is judged to be larger than the calibration capacity, carrying out equilibrium enabling on the single battery. In the embodiment of the document, when the change value of the state of charge of the battery cell of the lithium iron phosphate battery cell is smaller than a specified threshold and the remaining equalization capacity is larger than a calibrated capacity, equalization enabling is performed on the battery cell, so that the starting frequency of equalization enabling of the battery is improved, and the equalization effect of the battery is improved.

Disclosure of Invention

An object of an aspect of the present invention is to provide a battery pack having high safety and low cost. Another aspect of the present invention is directed to achieving high accuracy SOC calculations.

Furthermore, the present invention is also directed to solve or alleviate other technical problems of the prior art.

The present invention solves the above problems by providing a battery pack, a method and a vehicle, and particularly, according to an aspect of the present invention, there is provided:

the utility model provides a battery package, the battery package has electric core group, wherein, electric core group includes lithium iron phosphate core and ternary lithium ion battery cell, wherein, lithium iron phosphate core with ternary lithium ion battery cell establishes ties each other and sets up.

Alternatively, according to an embodiment of the present invention, the lithium iron phosphate cells and the ternary lithium ion cells are arranged in a one-to-one alternating manner.

Optionally, according to an embodiment of the present invention, two lithium iron phosphate cells and one ternary lithium ion cell are arranged in series as a group.

Alternatively, according to an embodiment of the present invention, the electric core group has only one ternary lithium ion battery cell.

Alternatively, according to an embodiment of the present invention, the lithium iron phosphate cells and the ternary lithium ion cells are arranged in a row with each other.

According to another aspect of the present invention, there is provided a method for measuring a state of charge of a battery pack, wherein the battery pack is any one of the battery packs described above, the method comprising:

carrying out ampere-hour integral calculation when the battery pack is charged and discharged; and/or

Correcting the calculation of the state of charge with the open circuit voltage of the ternary lithium ion battery cell when the battery pack is in a state of charge of 5% to 95% during the battery pack standing; and/or

Correcting the state of charge calculation using the open circuit voltages of the lithium iron phosphate cell and the ternary lithium ion cell when the battery pack is in a state of charge of 0% to 5% or 95% to 100% while the battery pack is at rest.

Optionally, according to an embodiment of the invention, the calculation of the ampere-hour integral is performed using a resistive shunt.

According to still another aspect of the present invention, there is provided a vehicle having any one of the battery packs described above.

Benefits of the battery pack, method and vehicle provided include: on the basis of realizing high safety, high-precision SOC is obtained, charging time and endurance mileage are accurately calculated, and complaints of users are reduced; the balance of energy density and cost of the battery pack is realized, and the battery pack is suitable for different vehicle types and choices.

Drawings

The above and other features of the present invention will become apparent with reference to the accompanying drawings, in which,

fig. 1 shows a schematic diagram of open circuit voltage-state of charge curves for a ternary cell and a lithium iron phosphate cell; and

fig. 2 to 4 are schematic diagrams respectively illustrating the cell layout of the cell group of the battery pack according to the invention.

Detailed Description

It is easily understood that according to the technical solution of the present invention, a person skilled in the art can propose various alternative structures and implementation ways without changing the spirit of the present invention. Therefore, the following detailed description and the accompanying drawings are merely illustrative of the technical aspects of the present invention, and should not be construed as all of the present invention or as limitations or limitations on the technical aspects of the present invention.

The terms of orientation of up, down, left, right, front, back, top, bottom, and the like referred to or may be referred to in this specification are defined relative to the configuration shown in the drawings, and are relative terms, and thus may be changed correspondingly according to the position and the use state of the device. Therefore, these and other directional terms should not be construed as limiting terms. Furthermore, the terms "first," "second," "third," and the like are used for descriptive and descriptive purposes only and not for purposes of indication or implication as to the relative importance of the respective components.

Referring to fig. 1, a schematic diagram of open circuit voltage-state of charge curves for a ternary cell and a lithium iron phosphate cell is shown.

It should be understood that the ternary battery cell is also called a ternary lithium ion battery cell, where ternary refers to nickel salt, cobalt salt, and manganese salt as raw materials, for example, nickel cobalt lithium manganate or nickel cobalt lithium aluminate is used as a positive electrode material, which has the characteristic of high safety. The lithium iron phosphate core has the advantages of high working voltage, large energy density, long cycle life, good safety performance, small self-discharge rate and no memory effect.

The Open Circuit Voltage (OCV) is a voltage in an open circuit state, that is, at the time of disconnection; the state of charge (SOC) is a ratio of the remaining capacity to the capacity in the fully charged state, and indicates that the discharge is complete when it is 0 and indicates that the fully charged state is 1.

It can be seen from the figure that the slope of the curve of the ternary battery cell is large, the calibration is convenient, and the performance is good, the curve of the lithium iron phosphate battery cell is generally smooth, and the slope is large near the two ends, and the lithium iron phosphate battery cell has the characteristics of low cost, good safety and difficulty in thermal runaway.

Based on the curve characteristics of the two battery cells and the corresponding characteristics of the battery cells, the application provides a combination scheme of the ternary battery cell and the lithium iron phosphate battery cell.

Referring to fig. 2 to 4, they respectively show schematic diagrams of the cell layout of the cell pack 100 of a battery pack according to the present invention.

The battery pack is provided with a battery pack 100, wherein the battery pack 100 comprises a lithium iron phosphate battery cell A and a ternary lithium ion battery cell B, and the lithium iron phosphate battery cell A and the ternary lithium ion battery cell B are connected in series with each other.

It should be understood that the series arrangement does not limit the specific positioning of the lithium iron phosphate cell a and the ternary lithium ion cell B, but only specifies the connection manner.

Through the introduction of the open-circuit voltage-state-of-charge curve and the characteristics of the lithium iron phosphate cell and the ternary lithium ion cell, it can be seen that the cost of the whole cell pack and the whole battery pack is reduced through the lithium iron phosphate cell, and the safety of the battery pack is improved due to the characteristic that the lithium iron phosphate cell is not easily subjected to thermal runaway, for example, under the condition that the ternary cell is subjected to thermal runaway, the lithium iron phosphate cell can serve as a barrier to maintain the safety of the whole cell pack. Meanwhile, the use of the ternary battery cell ensures that the battery cell group and the battery pack have good performance. In addition, the measurement accuracy of the state of charge of the battery pack can be improved by utilizing different curve characteristics of the ternary battery cell and the lithium iron phosphate battery cell. Furthermore, the battery pack may be a power battery pack.

With regard to the specific serial arrangement of the lithium iron phosphate cell a and the ternary lithium ion cell B, it is exemplary that the lithium iron phosphate cell a and the ternary lithium ion cell B are arranged one by one alternately with each other (as shown in fig. 2), for example, in the form of a + B + a + B. Through the alternative appearance of lithium iron phosphate core and ternary electric core, guaranteed that ternary electric core can not arouse next door second electric core's thermal runaway (this has utilized the difficult thermal runaway's of lithium iron phosphate core characteristics) when thermal runaway to prevent the thermal diffusion of battery package, and realized energy density and power output on the at utmost. Of course, the form of B + a + B + a is also possible and falls within the scope of protection of the present application.

It is also exemplary to arrange two lithium iron phosphate cells a and one ternary lithium ion cell B in series, for example in the form of a + B + a + B (as shown in fig. 3). The two lithium iron phosphate cells and the ternary cell appear alternately, so that the cost can be reduced, and meanwhile, the battery pack still has better performance and is still beneficial to improving the measurement accuracy of the state of charge of the battery pack. Of course, the arrangement positions of a and B in the groups are not limited, for example, the arrangement of each group B + a + A, A + B + a is possible, and each group is not necessarily exactly the same, i.e., a mixed form of a + B + a may be adopted. In addition, the grouping of two ternary lithium ion cells B with one lithium iron phosphate cell a is also optional.

The skilled person can also design the layout of the whole battery pack 100 in the manner of grouping other numbers of lithium iron phosphate batteries a and ternary lithium ion batteries B according to practical situations.

As another example, the electric core assembly 100 has only one ternary lithium ion electric core B. The ternary lithium ion battery cell B may be disposed at an end position of the battery cell pack 100 (as shown in fig. 4), or may be disposed at other positions of the battery cell pack 100. That is to say, in every module, adopt a ternary electricity core to carry out the SOC of this module and calculate to under the prerequisite that obtains better performance and be convenient for SOC calibration, reduce cost to the utmost.

Fig. 2 to 4 also have in common that the lithium iron phosphate cells a and the ternary lithium ion cells B are arranged in a row with respect to each other. The advantages of the row layout include the convenience of electrical connection (particularly series connection) of the individual cells of the cell pack 100 and the ability to save space in the lateral direction.

In addition, the lithium iron phosphate cells a and the ternary lithium ion cells B may be equidistantly spaced apart from each other and/or have the same size and shape (e.g., rectangular) so as to standardize the manufacture and assembly of the entire battery pack.

According to the practical situation (such as the space shape of a vehicle for accommodating a battery pack), the layout, the size, the shape and the distance between the lithium iron phosphate battery cell A and the ternary lithium ion battery cell B can be flexibly changed, and the serial connection design can still be realized through wiring.

According to another aspect of the invention, the invention relates to a method for measuring the state of charge of a battery pack, wherein the battery pack is any one of the battery packs described above, the method comprising:

carrying out ampere-hour integral calculation when the battery pack is charged and discharged; and/or

Correcting the calculation of the state of charge with the open circuit voltage of the ternary lithium ion battery cell B when the battery pack is in a state of charge of 5% to 95% during the battery pack standing; and/or

The calculation of the state of charge is corrected using the open circuit voltages of the lithium iron phosphate cell a and the ternary lithium ion cell B when the battery pack is at a state of charge (i.e., the first end of the state of charge) of 0% to 5% or 95% to 100% while the battery pack is at rest.

It should be noted that the above description is not related to the sequence or the steps, but only different application scenarios, that is, the corresponding method is executed according to different application scenarios (conditions).

Through the introduction of the open-circuit voltage-state-of-charge curves and the characteristics of the lithium iron phosphate cell and the ternary lithium ion cell, it can be seen that the method realizes the high-precision SOC calculation of the battery pack by combining the characteristics of the larger curve slope of the ternary lithium ion cell and the larger slope of the lithium iron phosphate cell near the end of the curve. While maintaining the characteristics of a battery pack having high safety and low cost.

Regarding the manner of calculating the ampere-hour integral, it is exemplified that the ampere-hour integral is calculated using a high-precision resistive shunt. Thereby saving costs.

It should be understood that the battery pack of the present invention may be mounted on various vehicles, including pure electric vehicles or hybrid vehicles of cars, vans, coaches, etc. Therefore, the subject matter of the present invention is also intended to protect various vehicles equipped with the battery pack of the present invention.

In summary, the invention is based on the combined design of the cells of two different chemical systems, namely ternary and lithium iron phosphate, so that the battery pack can realize high-precision SOC calculation on the premise of meeting high safety and low cost: by adopting the battery pack formed by combining the ternary lithium iron phosphate battery cells and the lithium iron phosphate battery cells, the high-precision SOC can be obtained on the basis of realizing high safety, the charging time and the endurance mileage can be accurately calculated, the phenomena that the battery pack is easy to overcharge or cannot be fully charged during charging and the battery pack is easy to overdischarge or the endurance mileage is greatly reduced during discharging are prevented, and the complaints of users are reduced; through different forms of ternary and lithium iron phosphate core group scheme, can realize the balance of battery package energy density and cost, be applicable to different motorcycle types and selection.

It should be understood that all of the above preferred embodiments are exemplary and not restrictive, and that various modifications and changes in the specific embodiments described above, which would occur to persons skilled in the art upon consideration of the above teachings, are intended to be within the scope of the invention.