Battery pack

Abstract

The subject matter described herein relates to a battery pack (100) comprising a battery module (102) and an outer housing (101). The battery module (102) comprises a battery cell support (103), a plurality of battery cells (301) and a plurality of cell terminal connectors. And the flame-retardant sheet (201) is placed above the plurality of battery cell terminal connectors. And the flame-retardant sheet (201) is placed in the outer shell (101). Each battery cell (202) of the plurality of battery cells (301) is covered with a conduit, and a fire extinguishing agent is disposed within the conduit (202).

Description

Technical Field

[0001] The subject matter described herein generally relates to a battery pack for a vehicle. More specifically, the present disclosure relates to thermal management of the battery pack. Background Art

[0002] Typically, lithium-ion battery packs are used as a power source for electric and hybrid vehicles. The battery pack consists of multiple cylindrical cells that are interconnected in series and parallel arrangements to meet current, voltage, and capacity requirements. The charging and discharging of the cells are monitored and controlled by a battery management system (BMS). This series and parallel interconnection of multiple cells can create various problems. Due to high current charging and discharging, there may be situations where excessive heat is generated, causing component melting and imbalance between cells, leading to battery pack fires. Since lithium is a highly reactive component, the nature of lithium ions is relatively unstable, which poses a challenge to safety and requires specialized handling and operating requirements.

[0003] Generally speaking, battery devices generate a lot of heat during operation, so the battery temperature will increase significantly. Eventually, the temperature will increase to a value where the battery pack goes into thermal runaway. A good battery pack design should be able to prevent thermal runaway. Depending on other requirements such as space, current, voltage, weight, cost, etc., the design can be applied to pouch cells or prismatic cells.

[0004] Conventionally, a thermal pad is used to ensure thermal management of the battery. A thermal pad is a heat dissipation pad used to control the heat generated by the battery. It is generally located between the battery module and the heat sink outside the battery pack, and it transfers the heat generated inside to the outside. For the thermal pad, a dedicated substrate is provided separately for heat dissipation and insulation. The thermal pad is disadvantageous for cylindrical cells because it cannot provide proper contact between the cells. Further, the thermal pad requires different layer thicknesses in different spaces. Therefore, the maintainability and assembly of the battery pack are troublesome. And, the maximum temperature resistance of the thermal pad is low.

[0005] The role of the battery thermal management system (BTMS) is to ensure that the operating temperature of the battery pack is within the normal safety range. Phase change materials (PCM) can be used to absorb heat, and the temperature of the battery pack can be kept within the normal operating range for a long time without the use of any external power. In the event of overheating, due to the high thermal conductivity of the phase change material (PCM) and the presence of cooling devices such as radiators and heat pipes in the BTMS, the temperature of the battery pack can quickly return to the normal operating range, thereby effectively reducing the occurrence of thermal runaway (TR) or fire accidents. However, due to the disadvantages of overcooling, low thermal conductivity and chemical instability, pure PCM cannot fully meet all application requirements at present. Summary of the invention

[0006] In the present invention, a battery pack includes a battery module, a battery cell assembly as a component of the battery module, and a plurality of battery cells. The plurality of battery cells are disposed in a battery cell holder. The plurality of cell terminal connectors are configured to electrically assemble the plurality of battery cells. The outer shell is configured to protect the battery module from external damage. The flame retardant sheet is placed between the plurality of cell terminal connectors and the outer shell. Each of the plurality of battery cells is covered with a conduit, and a fire extinguishing agent is disposed in the conduit.

[0007] Many battery cells generate heat during operation. Thanks to the flame retardant sheet and fire extinguishing agent, damage caused by the increase in temperature and heat in the battery pack is prevented, thereby improving the safety and driving range of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The present subject matter is described in detail with reference to the accompanying drawings. Throughout the drawings, the same reference numerals are used to refer to the same features and components.

[0009] Figure 1 An exploded view of a conventional battery pack according to the prior art is shown.

[0010] Figure 2 The internal cell arrangement of a battery pack and the placement of a flame retardant sheet according to an embodiment of the present disclosure are shown.

[0011] Figure 3 A single battery cell with conduits and their arrangement according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0012] The automotive industry has a growing demand for electrochemical power cells such as lithium-ion batteries due to the emergence of electric vehicles and grid storage systems. Further, multi-cell applications such as electric bicycles, uninterrupted power battery systems, and lead-acid battery replacement batteries are increasing. Therefore, in order to achieve widespread commercial adoption of electric vehicles, high energy and power density with low manufacturing costs and high safety are necessary.

[0013] The present invention relates to thermal management in such battery power systems. The term "battery" herein is intended to include various forms of electrochemical power generation, which have in common that chemical energy is stored in a confined space in the form of one or more chemical reactants that react with each other or with external reactants in an electrochemical reaction to produce electricity when desired.

[0014] The various uses of battery power sources are well established. For example, it is well known and common to package multiple battery cells together in a parallel or series configuration to form a battery module or battery pack for use as a power source for personal electronic devices such as cell phones, laptop computers, portable cameras, etc. In addition, the desirable properties or characteristics of battery power sources (including, for example, the rechargeability of certain battery power sources) make such battery power sources a potential power source for vehicle (i.e., electric vehicle (EV)) propulsion. More recently, the concept and application of battery power sources have been expanded to include "fuel cells" or "fuel cell batteries", in which the fuel cell reaction is used to generate electricity, similar to conventional rechargeable batteries, but one of the reactants (the fuel) must be replenished from time to time.

[0015] In various such applications, it is common to package multiple cells together in a preselected configuration (e.g., in parallel or in series) to form a battery module. Multiple such battery modules can then be combined or combined to form various battery packs such as are known in the art. During operation and discharge, such cells, battery modules or battery packs often produce or generate a large amount of heat, which can significantly affect the performance resulting therefrom. Thus, in order to maintain the desired or optimal performance of such cells or the resulting battery modules or battery packs, it is generally important to maintain the temperature of such cells, battery modules or battery packs within a fairly narrow specified range.

[0016] In practice, temperature variations between individual cells may be caused by one or more of a variety of factors, including, for example, changes in ambient temperature, unequal impedance distribution between cells, and differences in heat transfer efficiency between cells.

[0017] Differences in heat transfer efficiency between cells are typically primarily attributable to the cell pack configuration. For example, cell elements at the center of the cell pack configuration may tend to accumulate heat, while those at the periphery of the cell pack configuration generally tend to cool more easily or more freely due to heat transfer to the surrounding environment. Further, such variations in heat transfer efficiency may result in further differences in impedance, which may, for example, help to amplify capacity differences between cells. Such capacity imbalances may cause or result in overcharging or overdischarging of some cells, which in turn may result in premature failure of the cell pack or its specific cell elements. In particular, such failures may manifest as thermal runaway or accelerated capacity decay.

[0018] Thermal management systems based on the use of active cooling (e.g., based on forced circulation of air, liquid or other selected cooling medium, etc.) have been proposed for use in conjunction with such battery power systems. However, the incorporation and use of such active cooling mechanisms may introduce a degree of complexity in the design and operation of the power source, such as may hinder or prevent the more widespread use of such power sources.

[0019] Further, the required or desired size of a battery power source generally depends on its specific application. Thus, certain contemplated or envisioned applications for such power sources (such as powering electric vehicles), for example, may require the use of a power source that is or has a significantly larger physical size than commonly or available power sources. Those skilled in the art will recognize that as the size of such battery cells, battery modules, or battery packs increases, thermal management in the power system becomes more critical or important.

[0020] Typically, lithium-ion battery construction consists of an outer metal housing and a plastic cell holder in which the cells are placed. A battery pack generally consists of multiple cells. Multiple battery cells are placed on the cell holder. Depending on the power requirements of the vehicle, the number of battery cells in a battery pack can be increased or decreased.

[0021] Lithium-ion battery packs are equipped with battery management systems to prevent failures caused internally by the battery and ensure that the cells connected in series and parallel operate within the desired current, voltage and temperature ranges. Unfortunately, however, the BMS does not protect the lithium-ion cells, which may experience thermal runaway, causing fire and explosion. Moreover, if a single cell in the series-parallel arrangement of multiple cells experiences a failure, this may cause cascading failures of other cells. Conventional battery construction is not equipped to be immune to these failures.

[0022] Thermal management of lithium-ion battery packs is important to avoid thermal runaway. Increased temperatures inside the battery pack can cause safety issues and shorten the battery pack's service life. To ensure effective thermal management of lithium-ion battery packs, a fire-retardant sheet is provided inside the battery pack.

[0023] In the present invention, a battery pack includes a battery module, a battery cell assembly as a component of the battery module, and a plurality of battery cells. The plurality of battery cells are disposed in a battery cell holder. The plurality of cell terminal connectors are configured to electrically assemble the plurality of battery cells. The outer shell is configured to protect the battery module from external damage. The flame retardant sheet is placed between the plurality of cell terminal connectors and the outer shell. Each of the plurality of battery cells is covered with a conduit, and a fire extinguishing agent is disposed in the conduit.

[0024] Many battery cells generate heat during operation. Thanks to the flame retardant sheet and fire extinguishing agent, damage caused by the increase in temperature and heat in the battery pack is prevented, thereby improving the safety and driving range of the vehicle.

[0025] According to an aspect of the present invention, a flame retardant sheet is placed over a positive terminal of each of a plurality of battery cells.

[0026] According to an aspect of the present invention, a flame retardant sheet is placed over a negative terminal of each of a plurality of battery cells.

[0027] According to another aspect of the present invention, the fire extinguishing agent is one of a clean fire extinguishing agent or a powder based extinguishing agent.

[0028] According to yet another aspect of the present invention, the thickness of the flame retardant sheet is in the range of 1 mm to 10 mm.

[0029] According to another aspect of the present invention, the flame-retardant sheet is composed of one of silicon oxide, calcium oxide and aluminum oxide.

[0030] According to yet another aspect of the present invention, the conduit is a tubular structure helically wound around each of the plurality of battery cells.

[0031] According to another aspect of the present invention, the diameter of the tubular structure is in the range of 1 mm to 5 mm, and the tubular structure is made of a polymer.

[0032] The present invention prevents the battery pack from being damaged by overheating and temperature generated by thermal runaway. Further, the flame retardant sheet is composed of a composite material incorporating several high temperature resistant silicate materials. And, the design protects adjacent battery cells from the spread of fire between the cells by means of a conduit spirally wound around each battery cell in a plurality of battery cells. The conduit is composed of a rubber or polymer material that melts at high temperatures. The conduit sprays a fire extinguishing agent to prevent the flame from spreading to adjacent battery cells. The battery pack disclosed in the present invention has improved performance due to the increase in the operating temperature range, and further, the durability of the battery pack is also improved. Further, the battery pack disclosed in the present invention is easy to assemble and manufacture. And, the present invention also provides a solution for thermal management and fire extinguishing. Further, the flame retardant sheet and the fire extinguishing agent together prevent thermal runaway.

[0033] The summary given above explains the essential features of the present invention and does not limit the scope of the present invention.The nature and further characteristics of the subject matter will become more apparent from the following description made with reference to the accompanying drawings.

[0034] Exemplary embodiments of the features of the retrofittable components of the battery pack and their construction according to the present subject matter will be described below with reference to the accompanying drawings. Various aspects of the various embodiments of the present subject matter will be clearly discernible through the following description set forth below. Rather, the following description provides a practical illustration of an exemplary embodiment of the present subject matter. Moreover, it should be understood that the wording and terminology used herein are for descriptive purposes only and should not be considered limiting.

[0035] The present subject matter together with all attendant embodiments and further advantages thereof will be described in more detail in the following paragraphs with reference to the accompanying drawings.

[0036] Figure 1A conventional battery pack 100 is shown. Generally, the battery pack 100 includes a top cover 101, a bottom cover 104, an aluminum outer shell 103. The battery pack 100 includes a battery module 102 and the aluminum outer shell 103. The battery module 102 includes a plurality of battery cells, an interconnector, an interconnector damper, and a plastic cell support.

[0037] Figure 2 The internal cell arrangement of a battery pack and the placement of a flame retardant sheet according to the prior art are shown. The flame retardant sheet 201 is placed at the top and bottom of the battery cell holder. More specifically, the flame retardant sheet 201 is placed above a plurality of cell terminal connectors. Further, the flame retardant sheet 201 is placed inside the outer shell 103. A plurality of battery cells 301 are disposed in the battery cell holder. A plurality of cell terminal connectors are configured to electrically assemble a plurality of battery cells 301. The outer shell 103 is configured to protect the battery module from external damage. Each of the plurality of battery cells 301 is covered with a conduit, and a fire extinguishing agent is disposed within the conduit.

[0038] The plurality of battery cells 301 generate heat during operation. Due to the flame retardant sheet 201 and the fire extinguishing agent, damage caused by the increase of temperature and heat in the battery pack is prevented, thereby improving the safety and driving range of the vehicle.

[0039] Figure 3 A single battery cell with a conduit and its arrangement according to the prior art is shown. The conduit 202 covers each of the plurality of battery cells 301. The conduit 202 is a tubular structure spirally wound around each of the plurality of battery cells 301. The conduit 202 is designed so that it prevents fires from spreading between adjacent battery cells. The conduit 202 is made of a rubber or polymer material that melts at high temperatures. After the outer covering of the conduit 202 melts, a fire extinguishing agent is sprayed, which prevents the flames from spreading to adjacent battery cells.

[0040] The fire extinguishing agent inside the conduit helps prevent the fire from starting in a local area of ​​the battery cell and spreading. This prevents the fire from spreading to adjacent battery cells and causing catastrophic failure of the battery module. Further, the flame retardant sheet prevents the fire from spreading to the outside of the battery module. Because the claimed steps discussed above implement the following solutions to existing problems in conventional technology, the claimed steps are not routine, conventional, or well known in the art.

[0041] In light of the above disclosure, many modifications and variations of the subject matter are possible. Therefore, within the scope of the claims of the subject matter, the present disclosure may be practiced otherwise than as specifically described.

[0042] Reference numerals list

[0043] 100-Battery Pack

[0044] 101-Top cover

[0045] 102-Battery Module

[0046] 103-Outer shell

[0047] 104-Bottom cover

[0048] 201-Flame retardant sheet

[0049] 202-Catheter

[0050] 301-Battery cell.

Claims

1. A battery pack (100), comprising: A battery module (102), the battery module comprising: Battery cell holder (103), A plurality of battery cells (301), wherein the plurality of battery cells (301) are arranged in the battery cell holder (103), a plurality of battery cell terminal connectors, the plurality of battery cell terminal connectors being configured to be electrically connected to the plurality of battery cells (301), an outer shell (103), the outer shell (103) being configured to protect the battery module (102) from external damage, in, The flame retardant sheet (201) is placed above the plurality of battery terminal connectors, and the flame retardant sheet (201) is placed inside the outer shell (103). Each of the plurality of battery cells (301) is annularly covered with a conduit (202), and a fire extinguishing agent is disposed within the conduit (202).

2. The battery pack (100) according to claim 1, wherein: The flame retardant sheet (201) is placed above the positive terminal of each battery cell in the plurality of battery cells (301).

3. The battery pack (100) according to claim 1, wherein: The flame retardant sheet (201) is placed above the negative terminal of each battery cell in the plurality of battery cells (301).

4. The battery pack (100) according to claim 1, wherein: The fire extinguishing agent is one of a clean fire extinguishing agent or a powder-based fire extinguishing agent.

5. The battery pack (100) according to claim 1, wherein: The thickness of the flame retardant sheet (201) is in the range of 1 mm to 10 mm.

6. The battery pack (100) according to claim 1, wherein: The flame retardant sheet (201) is made of one of silicon oxide, calcium oxide and aluminum oxide.

7. The battery pack (100) according to claim 1, wherein: The conduit (202) is a tubular structure spirally wound around each of the plurality of battery cells (301).

8. The battery pack (100) according to claim 6, wherein: The diameter of the tubular structure is in the range of 1 mm to 5 mm, and the tubular structure is made of a polymer.

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