CN114156589A

CN114156589A - Energy storage cell module

Info

Publication number: CN114156589A
Application number: CN202110947082.0A
Authority: CN
Inventors: S·森蒂尔纳森; A·班纳吉
Original assignee: TVS Motor Co Ltd
Current assignee: TVS Motor Co Ltd
Priority date: 2020-09-05
Filing date: 2021-08-18
Publication date: 2022-03-08
Anticipated expiration: 2041-08-18
Also published as: CN114156589B

Abstract

The invention relates to an energy storage cell module (100) comprising: a housing (101) having a plurality of walls, at least one end cap (102). The at least one end cap has a plurality of openings (111,112) wherein the connector (100a) is connected to the battery management system through opening a. A pressure relief valve assembly (113) is removably attached to opening B (112), ensuring venting of excess internal pressure generated inside the energy storage cell module.

Description

Energy storage cell module

Technical Field

The present subject matter relates to an energy storage cell module. More particularly, the present subject matter relates to pressure venting of energy storage cell modules.

Background

Generally, rechargeable energy storage units can be charged or discharged, unlike primary energy storage units that cannot be recharged. Generally, a low capacity energy storage unit in which only one energy storage unit is packaged in a bag shape can be used as a power source for various compact portable electronic devices (e.g., mobile phones, etc.). In the case of a high capacity energy storage unit, where multiple energy storage units are connected in series or parallel, the high capacity energy storage unit may be used to power a device (e.g., a mobile power source), a laptop computer, or to drive a motor (such as an electric scooter, a hybrid vehicle, etc.).

Energy storage units are proposed as clean, efficient and environmentally responsible power sources for power supply equipment, such as electric vehicles and various other applications. Typically, conventional energy storage cell modules include a plurality of energy storage cell cells arranged in a stacked configuration and which are also in electrical communication with an electrical device. Further, each energy storage cell includes a cathode terminal and an anode terminal, wherein the terminals are electrically connected in a combination of series and parallel configurations to maximize the voltage output and run time of the energy storage cell module. In some designs, an energy storage cell cover must be placed over the energy storage cell stack to isolate and protect the anode and cathode terminals of each cell.

Drawings

The detailed description is described with reference to the accompanying drawings. The same numbers are used throughout the drawings to reference features and components.

Fig. 1 is an assembly view of an energy storage cell module according to an embodiment of the present invention.

FIG. 1a is an assembled view of a case according to an embodiment of the present invention.

FIG. 1b is a perspective view of a front end cap according to an embodiment of the present invention.

Fig. 1c is a cross-sectional view of an energy storage cell module having a pressure relief valve according to an embodiment of the present invention.

Fig. 2 is an exploded view of a pressure relief valve according to an embodiment of the present invention.

Fig. 2a is a cross-sectional view of a pressure relief valve according to an embodiment of the present invention.

FIG. 2b is a perspective view of a pressure relief valve having internal and external threads according to an embodiment of the present invention.

FIG. 2c is an assembly view of a pressure relief valve having one or more perforations in accordance with an embodiment of the present invention.

Detailed Description

Recently, for environmental protection, reduction of carbon dioxide emissions is strongly demanded. Especially in the automotive industry, the desire to reduce carbon dioxide emissions by the introduction of electric or hybrid vehicles is constantly rising. As a result, the energy storage unit industry is continually expanding to meet the ever-increasing energy needs of the portable device, transportation, and communications markets.

Generally, energy storage units are classified into primary energy storage units, which are also referred to as disposable energy storage units and are mainly used until used up, and secondary energy storage units, in which the energy storage units are simply replaced by one or more energy storage units. Secondary energy storage units, commonly referred to as rechargeable energy storage units, can be repeatedly recharged and reused, and are therefore economical and environmentally friendly in the long term, as compared to primary energy storage units.

Although rechargeable energy storage units offer many advantages over primary energy storage units, they also have some disadvantages based on the chemistry of the energy storage unit used. The secondary battery has poor chemical stability compared to the primary battery. In addition, due to these relatively unstable chemistries, special handling of the secondary battery is often required during the manufacturing process.

The secondary energy storage unit is divided into two parts, i.e., a lithium ion energy storage unit and a lead-acid energy storage unit. Lead-acid energy storage units are the most common large capacity rechargeable energy storage units. Lead-acid energy storage units are made up of a number of individual batteries comprising multiple layers of lead alloy sheets immersed in an electrolyte solution, typically consisting of sulfuric acid and water. Pure lead (Pb) is too soft and cannot support itself, so small amounts of other metals are added to obtain mechanical strength and improve electrical performance. The most common additives are antimony (Sb), calcium (Ca), tin (Sn) and selenium (Se). When sulfuric acid comes into contact with the lead plate, a chemical reaction occurs and energy is generated. Lead-acid energy storage units work well at low temperatures and are superior to lithium ion energy storage units when operating at sub-zero conditions.

Lithium ion energy storage cells are typically configured as secondary energy storage cells (rechargeable energy storage cells) that operate primarily by virtue of lithium ions (Li +) moving between a positive electrode and a negative electrode. During charge and discharge, Li + intercalates and moves between the two electrodes; li + is separated from the positive electrode, and the electrolyte is inserted into the negative electrode, so that the negative electrode is in a lithium-rich state. During charging, lithium ion energy storage cells generally use lithium-containing materials as electrodes, which are representative of modern high-performance energy storage cells.

Furthermore, there are many variations of lithium ion energy storage units, and the most popular lithium ion energy storage units with the highest energy density use cobalt or nickel cobalt oxide anodes. These energy storage units also have disadvantages, such as they tend to produce their own internal oxygen supply when overheated. More specifically, oxygen is released from the oxide material of the anode at high temperatures, which occurs for many reasons, such as internal short circuits, overcharge, or any other reason. Since both oxygen and fuel are available inside the cell, a fire may be initiated within a single cell, thereby posing a safety risk.

In addition, secondary energy storage cells (e.g., lithium ion energy storage cells) tend to be more susceptible to thermal runaway than lead-acid energy storage cells. When the temperature within the module rises above a threshold temperature due to battery abnormalities or operation within the module, gas particles generated within the module may be caused to move faster. As the gas particles move faster, the number of collisions of gas particles within the module also increases. This can therefore result in excessive internal pressure within the module. If this excess internal pressure is not vented or released from the module in a timely manner, the safety risk of a potential explosion or fire caused by a thermal runaway of the system may be increased. The main causes of thermal runaway are internal short circuits of the battery, misuse of the battery, physical abuse, manufacturing defects, or exposure of the battery to excessive external temperatures.

Thermal runaway is a significant problem because the single event of thermal runaway can cause serious physical injury/damage, and in some cases, it can cause injury or loss of life to the human body. When an energy storage unit is in a thermal runaway condition, the energy storage unit typically emits a large amount of smoke, burning electrolyte, and a large amount of heat, causing surrounding components near the energy storage unit to burn out and be damaged. Furthermore, if the energy storage cell module has a stack of cells, a single thermal runaway event will immediately result in thermal runaway of the plurality of cells, and thus, extensive damage to the battery pack and its surrounding components may result. Furthermore, the flame generated by the thermal runaway condition, if the initial flame is not extinguished immediately, also increases the impact of property damage, whether the energy device is composed of single or multiple cells.

During a thermal runaway in a laptop or electric vehicle, the thermal runaway without anyone can damage not only the laptop, but at least the surrounding environment in the vicinity of the laptop, such as a home, office, automobile, etc. Furthermore, if the energy storage unit is carried on an airplane by a laptop computer to which it is mounted, the worst case scenario may occur, and smoke generated due to thermal runaway may lead to fatal forced landing or emergency landing in a more severe case. Similarly, thermal runaway of one or more energy storage units in an energy storage unit module of a hybrid or electric vehicle can not only damage the vehicle, but can also lead to accidents and damage to the environment surrounding the vehicle components. It is therefore evident from the above discussed paragraphs that venting excess internal pressure from a sealed enclosure is important to reduce the risk of thermal runaway in an energy storage cell module.

Generally, modules of sealed energy storage cells having ends made of plastic are commercially available or used commercially. In addition, internal abnormalities of the cells of the energy storage unit or operation of the cells at high temperatures may cause gas generation inside the module. The high temperature inside the module causes the gas particles inside the module to move, which causes the internal pressure inside the module to increase. As the internal pressure inside the module increases, the end of the module made of plastic melts, and thus the excessive internal pressure generated inside the module is discharged. This leads to another problem, as the user has to replace the complete module of the energy storage unit. This increases the overall cost of the energy storage cell module and is also cumbersome for the user. Therefore, in order to overcome this problem, it is necessary to provide a pressure relief valve in the energy storage cell module to release/vent excess internal pressure generated inside the energy storage cell module to avoid any type of safety hazard.

Furthermore, sealed energy storage modules configured to accommodate energy storage units are known in the art. When the energy storage unit module is abnormal due to thermal runaway and the like caused by thermal faults, mechanical faults, internal and external short circuits and the like, gas is generated in the sealing module, so that the internal pressure of the sealing module is increased. Thus, when the internal pressure exceeds the threshold pressure, a pressure relief valve located in the sealing module may open, thereby venting excess internal pressure out of the sealing module. However, this presents another problem, such as replacing the pressure relief valve, which results in replacement parts that are not cost effective and cumbersome for the user to replace the entire energy storage unit.

In the known art, in order to prevent thermal runaway, different types of mechanisms (i.e., energy storage unit management systems) are used to control the charging mechanism to avoid cooling systems such as high temperature, step charging, impulse charging, or adding heat sinks, which require additional manual intervention when BMS (energy storage unit management system) circuits or the like fail.

Therefore, it is challenging to design an efficient energy storage cell module without any significant changes in the design and manufacturing settings of the vehicle.

Accordingly, there is a need for an improved energy storage cell module that overcomes all of the above-referenced problems and others of the prior art.

The present invention provides a solution to the above-mentioned problems while meeting the requirements of minimal modification to the power supply equipment at low cost, ease of manufacture, etc.

In view of the above objects, the present invention relates to an energy storage cell module, and more particularly, to an improved configuration of an energy storage cell module, in which a one-way pressure relief valve assembly is detachably attached with the energy storage cell module to discharge excessive internal pressure generated inside the energy storage cell module due to a malfunction such as thermal runaway, thereby making it cost-effective, increasing the convenience of assembly, and also safe for a rider.

According to one aspect of the invention, an energy storage cell module includes a case, a front end cap, and a rear end cap. The end caps are removably attached to the housing of the module by various attachment means, such as fasteners. According to one aspect of the invention, the front end has a recess with an opening, such as opening a. The opening a accommodates a connector that connects the energy storage unit with the battery management system inside the module. A one-way pressure relief valve assembly (referred to herein as a pressure relief valve assembly) is disposed in opening B located on the front end cover of the module. The pressure relief valve assembly relieves high internal pressure generated inside the module, thereby ensuring user safety.

According to one aspect of the invention, a pressure relief valve assembly includes a relief bonnet, a relief valve nut, a relief valve resilient member (e.g., a resilient member), a relief valve housing, and a relief valve stem. The release valve stem is disposed within the release valve housing. The relief valve housing has a perforation at the lower end to direct excess internal pressure generated inside the module due to gas generated inside the module. Further, according to an aspect of the present invention, the relief valve elastic member is supported on the relief valve stem and the relief valve preload nut is fixed on the relief valve elastic member of the pressure relief valve assembly. The pressure relief valve assembly is closed or covered by a relief bonnet from an upper side of the pressure relief valve assembly. The relief bonnet also has one or more perforations to vent excess internal pressure that is directed by the relief valve housing inside the pressure relief valve. When the internal pressure inside the energy storage module rises due to an operation/abnormality inside the energy storage cell module, the lower end opening of the relief valve housing guides the excessive internal pressure inside the pressure relief valve assembly. This results in compression of the relief valve resilient member when the relief valve stem is displaced/lifted in an outward direction due to increased internal pressure in the module. This outward displacement of the relief valve stem creates a passage to direct excess internal pressure within the pressure relief valve assembly. Further, when the pressure level drops below the internal pressure threshold, the release valve resilient member helps the release valve stem to return to its original position within the pressure relief assembly. The relief valve nut is a pre-tightened nut that helps the relief valve elastomeric member of the pressure relief valve assembly operate at different internal pressure values generated within the module. This ensures that the pressure generated inside the module is released in time, thereby finally protecting the module from thermal runaway. The release valve resilient member tension in the release resilient member wall ensures support of the release valve stem and helps the release valve stem to maintain its original position.

According to an aspect of the invention, the relief valve housing has a neck band type structure with a plurality of flat profiles on both sides of the neck band. The relief valve housing is detachably attached to an opening B in the rear cover of the module, thereby protecting the opening B from dust, contamination, etc.

It is contemplated that the concepts of the present invention may be applied to any of two-wheel, three-wheel, four-wheel type vehicles and any other device that requires an energy storage unit module to operate.

Various other features of the present invention are described in detail below with reference to the accompanying drawings. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number. Reference is made to the drawings wherein like reference numerals will be used to refer to like or similar elements throughout the several views. Further, the present subject matter may be implemented on both terminals of a cylindrical battery.

Fig. 1 is an assembly diagram of an energy storage cell module (100). According to one embodiment of the invention, the energy storage cell module (100) includes a case (101), a front end cap (102), and a rear end cap (not shown). The energy storage cell module is made of metal. Furthermore, the cabinet (101) comprises a plurality of walls, such as a pair of side walls (103, 104), an upper wall (105) and a bottom wall (106), which also serve as a base plate to locate a plurality of energy storage cells inside the energy storage cell module (100) (as shown in fig. 1 a). Further, according to an embodiment of the present invention, the front cover (102) is detachably attached to the case (101) of the energy storage unit module (100) by various attachment means such as fasteners (100 a). The front end cap (102) has a plurality of openings (102a) (shown in fig. 1 b) that are complementary to a plurality of openings (107) (shown in fig. 1 a) on the case (101) of the energy storage cell module (100).

Further, according to an embodiment of the invention, the front end cap (102) has a plurality of cut-out portions (108a, 108b, and 108c), wherein the cut-out portions provide easy access to the fasteners in the energy storage cell module. Further, according to an embodiment of the invention, the front end cap (102) has a U-profile (109), the recess (110) of which includes an opening, opening a (111), for receiving a connector (100b) to connect the energy storage unit with a battery management system (not shown) within the module. Further, according to an embodiment of the present invention, the front end cover has an opening B (112) at the extreme end (as shown in fig. 1B) for configuring the pressure relief valve assembly (113) in the energy storage cell module (100). In another embodiment, the pressure relief valve assembly may be removably placed on any wall of the energy storage cell module. The pressure relief valve assembly (113) is removably attached to the opening B (112) of the front end cap by a different attachment means, for example, the pressure relief valve assembly (113) has a threaded portion (204d) (shown in fig. 1 c) that coincides with a counter-threaded portion in the opening B of the front end cap. Further, in another embodiment, the pressure relief valve assembly may be implemented in an energy storage cell module, wherein the end cap is made of plastic. This ensures that excess internal pressure is vented through the pressure relief valve assembly, thereby eliminating the need to replace the assembly.

FIG. 2 is an exploded view of a pressure relief valve assembly according to an embodiment of the present invention. The pressure relief valve assembly (113) comprises a relief valve cap (201), a relief valve nut (202), a relief valve elastic member (203); a release valve housing (204) and a release valve stem (205). A release valve stem (205) is disposed within the release valve housing (204). A wire mesh (not shown) is placed between the relief bonnet and the relief valve nut to protect the pressure relief valve assembly from dust particles. Furthermore, according to an embodiment of the invention, the release valve stem (205) has a funnel-shaped profile (205a) which seats on the lower end (204b) of the release valve housing (204) (as shown in fig. 2a) to avoid internal leakage of the pressure relief valve assembly (113), i.e. when the internal pressure is below the threshold pressure within the module, no atmospheric air is transmitted through the pressure relief stem valve to the energy storage cell module. The release valve housing (204) has a threaded portion (204d) on the lower end (204B) (as shown in fig. 2B) that is a reverse thread and is fastened with a threaded portion (not shown) that is present in the opening B of the front end cap (112). This ensures that the pressure relief valve is attached to the front end cap using a minimum number of parts. The relief valve housing (204) has an opening (208) at the lower end (as shown in fig. 2 c) to direct the increased internal pressure generated inside the tank due to the operation inside the tank.

Further, according to an embodiment of the invention, the relief valve nut (202) is screwed into a threaded portion (204c) (shown in FIG. 2 b) of the relief valve housing (204) on the upper end (204a) (shown in FIG. 2a) of the relief valve housing (204). The relief valve nut is a pre-tightened nut that helps the relief valve elastic member of the relief valve assembly operate at different internal pressure values generated within the energy storage unit module. For example, a pre-tightening nut is tightened with a wrench and supported on the relief valve resilient member to resist pressures up to 1bar in the tank. This means that the relief valve elastic member is compressed by the pretension nut to withstand the 1bar pressure built up in the module. When the pressure exceeds 1bar, the release valve stem is displaced/lifted in an outward direction together with the release valve elastic member by overcoming the pressing force of the elastic member. Thus, excess internal pressure is directed into the relief valve housing (204) and eventually vented through one or more perforations (206), respectively, present on the relief bonnet. Furthermore, when the internal pressure drops to a level of 1bar below the threshold pressure, the pressure relief valve elastic member (203) returns to its original position together with the relief valve stem (205), because no excess pressure is now generated, and therefore the force for displacing the relief valve stem (205) is not sufficient to move the relief valve stem (205) outwards together with the relief valve elastic member (203). Thus, the release valve stem (205) and the release valve elastic member (203) reach the original position in the pressure relief valve assembly (113). The elastic member tension in the elastic member ensures support of the release stem valve (205) and helps the release stem valve (205) maintain its position. Thus, the redundant pressure generated in the box body can be released in time, and the energy storage unit module is protected from thermal runaway.

Further, according to an embodiment of the present invention, since the outer diameter of the release valve stem is substantially equal to the inner diameter of the release valve elastic member, the release valve elastic member (203) is supported on the release valve stem (205) (as shown in fig. 2 a). The release valve stem is made of metal such as aluminum. The pressure relief valve assembly (113) is closed or covered by a relief bonnet (201) from the upper side of the pressure relief valve assembly. The relief bonnet (201) also has one or more perforations (206) (shown in fig. 2 c) to vent excess internal pressure that is directed through the relief valve housing (204) inside the pressure relief valve assembly (113). The lower end opening (208) of the relief valve housing (204) directs excess pressure inside the pressure relief valve assembly (113) when the internal pressure inside the energy storage cell module rises due to operation/anomalies inside the energy storage cell module. This results in further compression of the relief valve resilient member (203) as the relief valve stem (205) displaces/lifts in an outward direction due to increased internal pressure in the module. This outward displacement/lifting of the release valve stem (205) creates a channel to direct excess internal pressure inside the pressure relief valve assembly (113). Thus, the pressure generated inside the module is guided inside the relief valve assembly (113) through the lower end of the relief valve housing (204) and vented (venting internal pressure, as shown by the dashed arrows) through the passage formed in the relief valve nut (202) and one or more perforations/openings (206) present on the relief valve cap (201) (as shown in fig. 2 a). Further, the length (L) of the relief valve resilient member is greater than the length (L1) of the relief valve stem (205) (as shown in fig. 2), so the relief valve stem (205) does not create an obstruction in the passage formed in the pretension nut (202) and the relief valve cap (201) for venting excess internal pressure. The length L of the release valve elastic member (203) is within a predetermined range of 40-45 mm. Greater or less than the predetermined range may adversely affect the compression of the relief valve resilient member 203. The length L1 of the release valve stem (205) is in a predetermined range of 25-30 mm. A length longer than the predetermined length of the release valve stem (205) acts as an obstruction in the passage that vents the internal pressure generated. The length less than the predetermined length is insufficient to support the relief valve resilient member (203) to affect the operation of the pressure relief valve assembly. Additionally, when the pressure level drops below the internal pressure threshold, the resilient member (203) helps the release valve stem (205) to return to its original position within the pressure relief assembly 113. For example, when the internal pressure generated within the tank of the energy storage cell module exceeds 1bar, then the pressure relief valve (113) vents excess pressure from the one or more perforations present on the relief bonnet 206, as any excess pressure inside the module is detrimental to the operation of the energy storage cell and can also lead to thermal runaway, ultimately increasing the safety risk to the user.

Furthermore, according to an embodiment of the invention, the release valve housing (204) comprises a neck band type structure (207) with a plurality of flat profiles (207a, 207b) on both sides of the neck band (as shown in fig. 2 c). This ensures that tools are easily used when assembling the pressure relief valve assembly with the energy storage cell module.

The present invention helps to overcome these problems while ensuring the safety of the components surrounding the energy storage cell module.

Advantageously, embodiments of the present invention describe potential modifications in the assembly of energy storage cell modules that include a one-way pressure relief valve with a pre-tightened nut that relieves excess internal pressure generated inside the case of the energy storage cell module. The present invention facilitates simple and easy release of excess internal pressure accumulated in the energy storage cell module while effectively increasing accessibility and safety of surrounding components of the energy storage cell module.

Many other improvements and modifications (e.g., using different resilient means with stiffness) may be incorporated herein without departing from the scope of the invention.

List of reference numerals:

FIG. 1:

100: energy storage cell module

100 a: fastening piece

100 b: connector with a locking member

101: box body

113: pressure relief valve assembly

102: front end cover

FIG. 1a

103. 104: a pair of side walls

105: upper wall

107: opening of the container

106: bottom wall

FIG. 1b

108a, 108b, 108 c: multiple cut-out portions

111: opening A

102 a: a plurality of openings

110: groove

109: u-shaped profile

FIG. 2

201: release bonnet

202: release valve nut

203: relief valve resilient member

204: relief valve housing

205: release valve stem

FIG. 2a

204 a: upper end of relief valve housing

204 b: lower end of relief valve housing

205 a: funnel-shaped profile part

FIG. 2b

204 c: threaded portion on outer surface of relief valve housing

204 d: threaded portion of inner surface of relief valve housing

207: neck hoop type structure

207 a: flat profile portion

FIG. 2 c:

206: one or more perforations

Claims

1. An energy storage cell module (100) comprising:

a case (103) for placing a plurality of energy storage units therein;

at least one end cap (102) for covering the energy storage unit securely placed in the case (103);

the at least one end cap (102) has a plurality of openings: an opening A (111) and an opening B (112), wherein the opening B (112) comprises a pressure relief valve assembly (113); and

the pressure relief valve assembly (113) is removably attached to the at least one end cap (102) of the energy storage cell module (100).

2. The energy storage cell module (100) of claim 1, wherein the at least one end cap (102) comprises a U-profile (109), wherein a groove (110) of the U-profile (109) comprises the opening a (111).

3. The energy storage cell module (100) of claim 1, wherein the opening a (111) positions a connector (100b) to connect the energy storage cell with a battery management inside the energy storage module (100).

4. The energy storage cell module (100) of claim 1, wherein the pressure relief valve assembly (113) has a threaded portion (204d) that coincides with a reverse threaded portion in the opening B (112) of the at least one end cap (102).

5. The energy storage cell module (100) of claim 1, wherein the at least one end cap (112) is removably attached to the case (101) by fasteners (100 a).

6. A pressure relief valve assembly (113) for an energy storage cell module (100), the pressure relief bonnet assembly (113) comprising:

a release bonnet (201) for covering an upper side of the pressure relief valve assembly;

a relief valve housing (204), wherein the relief valve housing (205) is covered by the relief bonnet (201) from an upper side of the pressure relief valve assembly (113);

a release valve stem (205) disposed within the release valve housing (204);

a release valve elastic member (203) supported on the release valve stem (205);

a relief valve nut (202) compressing the relief valve resilient member within the relief valve housing (204);

when the internal pressure exceeds a threshold pressure within the energy storage cell module (100), the release valve stem (205) disposed within the release valve housing (204) is displaced in an outward direction with the compressed release valve resilient member (203) to form a passage for venting excess internal pressure (shown by the dashed arrow).

7. The pressure relief valve assembly (113) of claim 6, wherein the relief valve housing (204) has a lower end (204b), wherein the relief valve stem (205) has a funnel-shaped profile (205a), the funnel-shaped profile (205a) seating on the lower end (204b) of the relief valve housing (204) when the internal pressure is below the threshold pressure.

8. The pressure relief valve assembly (113) of claim 7, wherein the lower end (204b) of the relief valve housing (204) has an opening (208) through which the excess internal pressure is directed inside the pressure relief valve assembly (113) when the internal pressure exceeds a threshold pressure within the energy storage unit module (100) when a relief valve stem (205) of the pressure valve assembly (113) is displaced in an outward direction with a relief valve resilient member (203) of the pressure valve assembly (113).

9. The pressure relief valve assembly (113) of claim 6, wherein an outer diameter of the relief valve stem (205) is substantially equal to an inner diameter of the relief valve resilient member (203).

10. The pressure relief valve assembly (113) of claim 6 wherein said relief bonnet (201) has one or more perforations (206) to vent excess internal pressure from said energy storage cell module (100).

11. The pressure relief valve assembly (113) of claim 6 wherein a length L of said relief valve resilient member (203) is substantially greater than a length L1 of said relief valve stem (205).

12. The pressure relief valve assembly (113) as set forth in claim 11 wherein said length L is in a predetermined range of 40-45 mm.

13. The pressure relief valve assembly (113) as set forth in claim 12 wherein said length L1 is within a predetermined range of 25-30 mm.

14. The pressure relief valve assembly (113) of claim 6, wherein said relief valve housing (204) has an upper end (204a), wherein said upper end (204a) has a threaded portion (204c) inside said relief valve housing (204), and said relief valve nut (202) having a threaded portion is detachably connected with said threaded portion (204a) on said upper end (204a) present inside said relief valve housing (204).

15. The pressure relief valve assembly (113) of claim 6, wherein said relief valve housing (204) comprises a lower end (204B) having a threaded portion (204d), said threaded portion (204d) being counter-threaded and fastened with an opening B (112) present on at least one end cap (102) of said energy storage cell module (100).

16. The pressure relief valve assembly (113) of claim 5, wherein said relief valve housing comprises a neck band type structure (207) having a plurality of flat portions (207a, 207 b).

17. A method of venting excess internal pressure from an energy storage cell module through a pressure relief valve, comprising:

placing a relief valve assembly having a relief valve cap, a relief valve nut, a relief valve resilient member, a relief valve stem, and a relief valve housing in an energy storage cell module;

compressing a release valve elastic member with the release valve nut;

a release valve stem seated in the release valve housing when an internal pressure generated inside the energy storage cell module is below a threshold pressure;

when the internal pressure generated inside the energy storage cell module exceeds a threshold pressure, a release valve stem lifts in an outward direction together with the compressed release valve elastic member, causing the excess internal pressure to be discharged;

directing excess internal pressure in the relief valve housing of the pressure relief valve assembly; and

venting the excess internal pressure from the energy storage cell module through the relief valve nut and the relief bonnet of the pressure valve assembly.