Claims:We Claim;
1. A battery case structure (100) comprising of:
A lid (103) is detachably attached to allow access to an interior of said battery case structure (100);
A battery module (205) includes a plurality of grooves (107) which holds one or more partition panels (108), where said partition panels (108) accommodate, stack of lithium ion battery (201) and stack of lead acid battery (203),
said battery case structure (100) includes a phase change material (204) which is detachably attached to said battery module (205) of said battery case structure (100); and
a fire extinguisher material (402) is detachably attached to said phase change material (204) and said battery module (205) of said battery case structure (100).
2. A battery case structure (100) comprising of:
a lid (103) is detachably attached to allow access to an interior of said battery case structure (100);
a battery management system (202) manages combination of said stack of lithium ion battery (201) and said stack of lead acid battery (203) and disposed in compartment between said stack of lithium ion battery and said lead acid battery (203), where said battery management system (202) provides energy to a powered unit in a ratio R.
3. The battery case structure (100) as claimed in claim 2, wherein said ratio R is the load duty on each of the batteries ranging from 0 to 100 %.
4. The battery case structure (100) as claimed in claim 1, wherein said battery case structure have four walls (105).
5. The battery case structure (100) as claimed in claim 2, wherein said four walls (105) includes a pair of side walls (105b, 105d), front wall (105a) and back wall (105c);
6. The battery case structure (100) as claim in claim 1, wherein said lid (103) includes one or more holes (102) to establish terminal connection of said battery module (205) with electrical connector in vehicle.
7. The battery case structure (100) as claimed in claim 1, wherein said wall (105c) includes one or more holders (106) to attach said battery case structure (100) with a vehicle.
8. The battery case structure (100) as claimed in claim 1, wherein said one or more walls (105b, 105d) includes one or more holes (102) to channelize flow of air outside said battery case structure (100).
9. The battery case structure (100) as claimed in claim 1, wherein said phase change material (204) includes two walls, inner wall (204a) and outer wall (204b).
10. The battery case structure (100) as claimed in claim 9, wherein said inner wall is having a predetermined thickness A ,
11. The battery case structure (100) as claimed in claim 10, wherein said thickness A is in predetermined range of 0.5mm-2mm.
12. The battery case structure (100) as claimed in claim 9, wherein said outer wall (204b) is having a predetermined thickness B,
13. The battery case structure (100) as claimed in claim 12, wherein said thickness B is in predetermined range of 2-5mm.
14. The battery case structure (100) as claimed in claim 9, wherein said thickness B of said outer wall (204b) is greater than said thickness A of said inner wall (204a) of said phase change material (204).
15. The battery case structure (100) as claimed in claim 1, wherein said phase change material (204) is configured with one or more vents (403) to release the heat absorbed by said phase change material (204).
16. The battery case structure (100) as claimed in claim 1, wherein said battery module (205) is configured with perforations (401), where said perforations (401) includes one or more opening (404) which is filled up with self-melting material.
17. The battery case structure (100) as claimed in claim 1, wherein said partition panels (108) divides said battery case structure (100) in one or more compartments, where one compartment accommodate stack of lithium ion battery (201), and another compartment accommodate stack of lead acid battery (203)
, Description:TECHNICAL FIELD
[0001] The present subject matter relates to a battery module for a powered device.
[0002] The present subject matter relates to the battery pack. More particularly, the present subject matter relates to the battery pack in which a plurality of unit cells is stacked.
BACKGROUND
[0003] Basically, the rechargeable batteries can be charged or discharged unlike the primary batteries which are not capable of getting recharged. Generally, the low capacity battery where only one battery cell is packaged into a pack shape may be used as the power source for the various compact and portable electronic devices like the mobile phones etc. In case of high capacity battery in which several numbers of batteries are connected in series or parallel, the high capacity battery may be used for powered devices e.g. power banks, laptops or driving motors such as electric scooters, hybrid vehicle etc.
[0004] A battery is proposed as a clean, efficient and environmentally responsible power source for powered devices like electric vehicles and various other applications. Generally, a conventional battery module includes a plurality of battery cells arranged in a stacked configuration and also same is in electrical communication with an electrical device. Further, each of the battery cells includes a cathode and anode terminals where the terminals are electrically connected in a combination of series & parallel configuration in order to maximize the voltage output & running time of the battery module. In certain designs, a battery cover has to be disposed over the stack of the battery cells to isolate and protect the anode and cathode terminals of each of the cells.
BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The detailed description is described with reference to the accompanying figures. The same numbers are used throughout the drawings to reference features and components.
[0006] Fig. 1 is an assembled view of battery case structure as per one embodiment of the present invention.
[0007] Fig. 1a is a back view of the battery case structure as per one embodiment of the present invention.
[0008] Fig. 1b is a sectional view of the battery case structure as per one embodiment of the present invention.
[0009] Fig. 2 is a sectional view of the battery case structure with the battery module and phase change material as per one embodiment of the present invention.
[00010] Fig. 3 is a graphical representation as per one embodiment of the present invention.
[00011] Fig. 4 is a sectional view of the battery case structure with the fire extinguisher material as per one embodiment of the present invention.
[00012] Fig. 4a is a sectional view of the perforation as per one embodiment of the present invention.
DETAILED DESCRIPTION
[00013] In present years, for environmental protection there has been a strong demand for the reduction of the amount of carbon dioxide emission. Especially, in automobile industry, expectations have been attracted to the reduction of carbon dioxide emission by introducing electric vehicle or a hybrid vehicle because of which the battery industry is continually expanding to meet the increasing energy needs of the portable equipment, transportation and communication markets.
[00014] Generally, batteries are classified into primary and secondary batteries, where the primary batteries are also referred as the disposable batteries and mostly intended to be used until exhausted after which the battery is simply replaced by one or more batteries. Secondary batteries, commonly referred as rechargeable batteries can be repeatedly recharged and reused, thus are economical in the long run, environmental as compared to disposable batteries.
[00015] While rechargeable batteries offer many advantages over primary batteries but also has some drawbacks which are based on the chemistry of the battery used, as these chemistries of the secondary cell is less stable as compared to the primary cell. Further, due to these relatively unstable chemistries, special handling of the secondary cell is often required during manufacture.
[00016] Further, a secondary battery is divided into two parts namely, lithium ion battery and lead acid battery. Further, lead acid batteries are the most common large capacity rechargeable batteries. The lead acid batteries are built with a number of individual cells containing layers of lead alloy plates immersed in an electrolyte solution, typically made up of sulphuric acid and water. Pure lead (Pb) is too soft and would not support itself, so small quantities of other metals are added to get the mechanical strength and improve electrical properties. The most common additives are antimony (Sb), calcium (Ca), tin (Sn) and selenium (Se). When the sulphuric acid comes into contact with the lead plate, a chemical reaction occurs and energy is produced. The lead acid battery works well at cold temperatures and is superior to lithium ion battery, when operating in sub-zero conditions
[00017] A lithium ion battery is typically configured as a secondary battery (rechargeable battery), which mainly depends on lithium ions (Li+) moving between a positive electrode and a negative electrode to work. During charging and discharging, Li+ is embedded and travels between two electrodes; Li+ is withdrawn from the positive electrode, and the electrolyte is embedded in the negative electrode, and the negative electrode is in a lithium-rich state. When charging, the lithium ion battery generally uses a material containing lithium as an electrode, which is representative of modern high-performance batteries.
[00018] Further, the Li ion batteries are produced in a number of variations; the most popular Li ion batteries, having the highest energy density, use a cobalt or nickel cobalt oxide anode. These batteries also have the disadvantage like when overheated, they have tend to create their own internal supply of oxygen. More particularly oxygen is released from the oxide material of the anode at high temperature, which occurs due to many reasons like internal short circuit, overcharging, or any other causes. Since both oxygen and fuel are both internally available to the cells, a fire can start within a single cell and can be difficult to extinguish with conventional methods potentially leading to safety risks.
[00019] Furthermore, in current electric vehicles, lead acid batteries and lithium-ion batteries are used to provide power to the vehicle. Tires of the vehicle are coupled with a direct current (DC) motor and lead acid batteries and lithium-ion batteries provide DC power to the DC motor of the vehicle.
[00020] In general, during starting a vehicle or a powered device, the DC motor requires a large current which is needed to generate sufficient torque to overcome the static friction during starting up of the vehicle. The lead acid batteries can provide current surge required at the starting of the vehicle and thereafter, once the vehicle has gained a predefined speed, the lithium-ion batteries take over and provide the power to the DC motor. However, the lithium-ion batteries are not able to effectively provide the large current during starting of the vehicle. Often high surge of current drawn during starting leads to harness damage or other undesirable effects for an ion based energy device. Thus, a vehicle may not have lithium-ion batteries alone for providing power to the vehicle and a lead acid battery may also be required to provide the starting power to the vehicle.
[00021] Moreover, the secondary battery such as lithium ion batteries tend to be more vulnerable to the thermal runaway than lead acid batteries and the main reason for occurrence of the thermal runaway is when the internal reaction rate increases to the point where the heat generation rate is more than the rate at which it is removed. Moreover, both the reaction rate and the exothermic reaction further increase with time . Consequentially, the calorific value generated in the energy device may be enough to cause combustion or explosion of the battery and materials in close vicinity to the battery. The main reasons for thermal runaway are shorting within the cell, improper use of the cell, physical abuse, manufacturing defects or exposing the cell to excessive external temperatures.
[00022] Thermal runaway is an important issue because a single event of thermal runaway can cause serious physical harm\damage and in some case, it can cause harm to the human body or loss of life. When a battery is in thermal runaway condition, the battery generally emits a large amount of a smoke, a jet of burning liquid electrolyte and significant heat, which results into the burning and destruction of the surrounding components nearby to the battery. Also, if the battery pack is having a stack of the cells, a single thermal runaway event will instantly cause thermal runaway of the multiple cells, hence, potentially causing extensive damage to the stack of the cells and its surrounding components. Further, the flame generated due to thermal runaway condition, also contributes in the increase of effect of property damage if the initial flame is not instantly extinguished, irrespective of the energy device consisting of single cell or the multiple cell.
[00023] Taking example of the thermal runaway in the laptop or electric vehicle. The thermal runaway in the laptop without any human attachment can cause not only damage to the laptop but also, at least some damage to the surrounding near to the laptop like as home, offices, cars etc.. Furthermore, worst situation can occur if the laptop battery is mounted on the board of aircraft, the resulting smoke due to thermal runaway can cause a fatal crash landing or emergency landing in more demanding situations. Similarly, taking the example of the electric vehicle, the thermal runaway of one or more batteries in the battery pack of a hybrid or electric vehicle not only damages the vehicle but also can cause accident and damage to the environments surrounding the components of the vehicles.
[00024] Further, in known art, the size and capacity of the lead acid batteries and the lithium-ion batteries, that can be used, are fixed. The size of compartments holding the lead acid batteries and the lithium-ion batteries are fixed and thus the size and capacity of the lead acid batteries and the lithium-ion batteries are restricted. Further, for generating a fixed voltage, a greater number of lead acid battery is required in comparison with the lithium ion battery. Further, individual use of the lithium ion battery increases the overall cost of the vehicle as the lithium ion battery is costly in addition to difficulty of effective cooling, disposal of heat, gas generated, difficulty in manufacturing as well as service. Thus, in known art, the lead acid battery and lithium ion battery are used separately and thus the greater combined effect from the combination of lead acid battery and lithium ion battery remains unutilized.
[00025] Further, in known art, to prevent thermal runaway, different types of mechanism are used namely, battery management system to control charge mechanism to ultimately avoid high temperatures, step charging, pulse charging or adding cooling systems like fins etc, which requires the additional manual intervention in case of failure like as failure in BMS (Battery Management System) circuit etc.
[00026] Hence, there exists a challenge of designing an efficient battery module without any major change in design and manufacturing set-up of the vehicle.
[00027] Therefore, there is a need to have an improved battery module which overcomes all of the above problems and other problems of known art.
[00028] The present invention provides a solution to the above problems while meeting the requirements of minimum modifications in a powered device e.g. an electric vehicle at low cost with ease of manufacturing etc.
[00029] With the above objectives in view, the present invention relates to the battery module and more particularly to an improved configuration of battery module where the lead acid battery and lithium ion battery is placed together and also, overcoming the thermal runaway, thereby, making it cost effective, increasing the ease of serviceability and also, safe for the riders.
[00030] As per one aspect of the present invention, the battery case structure comprises of the four walls, a base panel and a lid where the lid is detachably attached to allow an access to an interior of the box structure. The access to the interior of the box structure is for placing the lead acid batteries and lithium-ion batteries inside the box structure or for removing the lead acid batteries and lithium-ion batteries from the box structure. The box structure further comprises plurality of grooves that can hold a partition panel. The partition panels divide the interior of the box structure into one or more compartments. The size of the compartments can be changed by changing the position of the partition panel in the allocated grooves. Due the presence of plurality of the grooves in the interior of the box structure the partition panel can be secured at different positions on the interior of the box structure.
[00031] As per one aspect of the present invention, one or more compartments are formed due to partition panels where one compartment is to accommodate at least a battery, another compartment is to accommodate at least a lithium ion battery. Further, the box comprises a battery management system disposed in between the stack of lithium ion battery and lead acid battery, which manages the combination of at least one lead acid battery and at least one lithium ion battery to provide power to the device, more particularly provide power to the DC motor.
[00032] As per one aspect of the present invention, the battery module is further protected by the phase change material (PCM) which is disposed adjacent to the battery module. Further, as per one aspect of the present invention, when the temperature of the battery module exceeds the melting point of phase change material, the phase change material changes from solid state to liquid state and avoids sharp increase in the battery temperature thereby increasing life cycle & durability of the battery module. Further, as per one aspect of the present invention, when the temperature around the phase changes material decreases, the heat generated is released in the atmosphere through the vent provided in the phase change material and then the phase change material again returns to a solid state. Further as per one embodiment of the present invention, the phase change material has two walls namely inner wall and outer wall, where inner wall having a predetermined thickness “A’ , is separated with another wall i.e. outer wall of battery module. The inner wall of the phase change material is made up of plastic. More than or less than a predetermined thickness of the wall will impact efficient heat release of the phase change material which can adversely affect the releasing of heat from the phase changing module to the atmosphere.
[00033] Further, as per one embodiment of the present invention, the battery case structure additionally includes a fire extinguisher material, for example dry chemical powder. Further, as per one aspect of the present invention, the fire extinguisher material has portion which is connected to the perforations present in the battery module. The perforations are filled with a self-melting material like silicon etc. When the temperature of the battery module reaches predetermined limit e.g.100 OC to 120 OC, the self-melting material present in the slots of the perforations present in the battery module gets dissolved which further, leads the fire extinguisher material to come in contact with the battery module, thereby suppressing any fire from the battery module. Thus, any irreparable damage or fire hazard is avoided and the safety of the battery modules as well as its surrounding components is greatly enhanced. As per an aspect of this embodiment, The fire extinguisher is activated to suppress the fire when the phase change material and wall of the phase change material made up of plastic, is dissolved.
[00034] Further, as per another embodiment of the present invention, the thickness ’A’ of the phase change material wall is less than the outer thickness ‘B’ of the phase change material wall, so that the phase change material should exchange energy with the battery module and not with the atmosphere as the heat transfer between the battery module and phase change material is more as compared to the heat transfer between the phase change material and atmosphere..
[00035] Various other features of the 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. With reference to the accompanying drawings, wherein the same reference numerals will be used to identify the same or similar elements throughout the several views. Further, the present subject matter can be implemented on both the terminals of cylindrical cells.
[00036] Fig. 1 is the assembled view of the battery case structure (100). As per one embodiment of the present invention, the battery case structure (100) consist of the four walls (105) i.e. a pair of side walls (105b, 105d), front wall (105a) and back wall (105c), having base panel (not shown), a lid (103), where the base panel supports the four walls (105) of the battery case structure (100). Further, the battery case structure (100) also includes at least a pair of holders (106) (as shown in fig, 1a) fixed in an exterior of the battery case structure (100), to attach the battery case structure with the powered device e.g. a vehicle. At least a wall (105c) includes one or more holders (106) to attach said battery case structure (100) with a vehicle. Further, the battery case structure (100) includes one or more handles (101) to hold the battery case structure with hand, which ensures the ease of movement. Further, as per one embodiment of the present invention, the lid (103) of the battery case structure includes one or more small holes (102) for establishing the connections between the terminals of the battery module to the electrical wiring harness in the vehicle and also, if any pressure is build up in the battery module, this small holes act as the escape route to ensure that the pressure and heat generated are vented out. Further, the lid (103) is closed and locked by the locking mechanism (104) to ensure the rigid packing of the battery module and also, ensures the ease of accessibility.
[00037] Further, the battery case structure (100) is further divided into one or more compartments because of the one or more partition panels (108) for placing of the stack of lithium ion battery and the lead acid battery, which also improves the ease of accessibility of the battery module. Further, the one or more partition panels are attached with the battery case structure (100) through the grooves (107) (shown in Fig 1b)
[00038] Further, for example let us consider that to achieve the voltage above 50V, 40% of lead acid battery and 60 % of the lithium ion battery is required, reduction of weight of the combined battery module with respect to when the complete lead acid battery used to achieve is 48%. Further, the cost reduction of the battery module with respect to the complete lithium ion battery is 32%. Such flexible configuration ensures that the synergistic effect of the use of lithium ion battery and lead acid battery results in reduction of weight, cost, as well as enables maintaining required supply of starting energy or power to the motor etc. Additionally, the present configuration also ensures flexibility for an designer to preferentially balance the energy sources between the lead acid cell module vis-à-vis lithium ion cell module to overcome the contradictory hurdle of meeting both high energy supply during starting & / or low rpm condition as well as long range / time supply of power over a prolonged quasi-steady stage running condition of the motor or the powered device.
[00039] Fig. 2 is the assembled view of the battery module (205) in the battery case structure. As per one embodiment of the present invention, the battery module (205) is further divided into one or more compartments by the partition panels (108) (as shown in fig. 1b), where one compartment has one or more stack of lithium ion battery (201) and another compartment has one or more stack of lead acid battery (203). Further, a battery management system BMS (202) is disposed in compartment formed in between compartments of the stack of the lithium ion battery (201) and stack of lead acid battery (203). Further, as the lead acid battery and lithium ion battery have different nominal voltages, operating windows, charge-discharge currents and number of cycles, so the construction and operation of the battery management system is configured to optimize the usage & calibrated to meet the predetermined requirement of the powered device. Just for reference, taking example, the lead acid battery has the nominal voltage of 2V and lithium ion battery has the nominal voltage of 4V , further, to compensate one lithium ion cell of 4V nominal voltage, two lead acid cells of 2V each are required. Further, the battery management system protects the batteries from operating outside its safe operating area, thereby, the battery management system protects the battery from excess charging or discharging.
[00040] Further, the battery module manages the power requirements of the powered unit / device. Further, the battery module (205) along with the BMS may engage the lead acid battery (203) configured inside the compartment to provide energy to the powered unit during starting and may engage the lithium-ion battery (201) accommodated inside the compartment to provide the energy to the powered unit once the motor of the powered device has attained a predetermined speed. Further, as per another embodiment, the battery module (205) may engage the combination of the lead acid batteries (203) and the lithium-ion batteries (201) to provide energy to the powered unit in a ratio R wherein R is the load duty on each of the batteries ranging from 0 to 100 %. Further, the charging of at least one lead acid battery (203) and one lithium ion battery (201) is managed by the battery management system (202). The battery management system (202) present in the battery module, prevents the lead acid battery and lithium ion battery from being overcharged by preventing the flow of charging of current to the lead acid battery and the lithium ion battery once they are fully charged.
[00041] Further, as per one embodiment of the present invention, the battery module (205) is further covered by the layer of phase change material (204), where the phase change material (204) consists of the two walls namely, inner wall (204b) and outer wall (204a). The inner wall (204b) made up of plastic configured with predetermined thickness A , where the thickness A is in predetermined range of 0.5-2mm. Less than 0.5mm will adversely affect the strength of the inner wall of phase change material, as the strength will decrease if thickness is less than 0.5 mm whereas more than 2 mm adversely effects the thermal heat transfer effectiveness of the phase change material which additionally affects the heat absorbing properties of the phase change material. Further, when the temperature in the battery module (205) increases due to a potential thermal runway condition, heat energy so released is absorbed by the phase change material (204) leading to the phase change material (204) transforming from a solid to a liquid or semi-solid state while still being securely held in between the inner (204b) & the outer walls (204a). Further, the phase change material (204) releases the heat energy decreases and is released to the atmosphere through vent (403) (as shown in fig. 4) provided onthe outer wall (204a), thereby ensuring a predetermined or an ambient temperature in the battery module (205). The thickness B of outer wall of the phase change material is in predetermined range of 2 mm to 5 mm where the thickness B is equal or more than the thickness A , ensuring that the absorption of heat by the phase change material (204) from the battery module (204) is at higher rate, which increases the life cycle & durability of the battery unit.
[00042] Fig. 3 is the graphical representation of the charging and discharging of the battery module (205) with and without the phase change material. As per one embodiment of the present invention, during the charging of the battery, it is clear from the graphical representation G1that the peak charging temperature of the battery module with the phase change material (302) is lesser than the peak charging temperature of the battery module without phase change material (301), substantiating that the better operating temperature is advantageously lower with the phase change material. This, reduces the loss in capacity of the life cycle of battery module up to 50% with incorporation of a phase change material as compared with the loss in capacity of the life cycle of the battery module without phase change material. Further, as per one embodiment of the present invention, during the dis charging of the battery, it is clear from the graphical representation G2 , that the peak discharging temperature of the battery module with the phase change material (304) is lesser than the peak discharging temperature of the battery module without the phase change material (303). This signifies that the uses of phase change material significantly reduces the battery temperature which improves the life cycle as well as durability of the battery module.
[00043] Fig. 4 is the assembled view of the battery module with the fire extinguisher configured thereat. As per one embodiment of the present invention, perforations (401) are disposed in the inner wall (204b) of the phase change material (204). & a fire extinguisher material (402) is disposed around the external periphery of the PCM. The perforations (401) include the one or more openings (404) (as shown in fig. 4a) which is filled with the self-melting material like silicon. When the temperature increases abruptly, for example more than 100 degree, leading to changing the PCM from solid state to liquid state the self-melting material changes its state from solid to liquid state which makes the fire extinguisher material (402) to come in physical contact with the battery module (205), thereby suppressing the fire in the battery module (205) thereby ensuring safety of the energy unit. Further, as per one embodiment, the required quantity ratio by weight of the phase change material with the fire extinguisher is in predetermined ratio of 1:2.5 to enable safest results for various ratios R of the load duty between the lead acid module & the Lithium ion module.
[00044] The invention helps in overcoming the problem of increased weight, increased cost, releasing heat because of the thermal runaway, increasing the ease of accessibility of the cells of the battery module while ensuring the safety of the surrounding components of the battery module.
[00045] Advantageously, the embodiments of the present invention, describes the potential modifications in the assembly of the battery module which includes at least one lithium ion battery and lead acid battery with the phase change material and fire extinguisher material. Such configuration enables overcoming the limitations of the both the lead acid technology as well as the Lithium ion technology while combining the 2 technologies in an effective synergistic way & yet overcoming the new challenges that arise out of the amalgamation of both technologies. The present invention facilitates the simple and easy releasing of heat accumulated during the thermal runaway condition in the battery module which efficiently increasing the ease of accessibility and safety of the surrounding components of the battery module.
[00046] Many other improvements and modifications like using different elastic means having stiffness may be incorporated herein without deviating from the scope of the invention.
List of reference symbol:
Fig. 1:
100: Battery Case Structure
101: A pair of handle bar
102: Holes
103: Lid
104: Locking Mechanism
105 (105a, 105b, 105c,105d..): Four Walls
106: Holders
107: Grooves
108: partition panel
Fig. 2:
A: Thickness of inner wall of phase change material.
201: Stack of lithium ion battery
202: Battery Management System
203: Stack of Lead Acid Battery
204: Phase Change Material
204a: Outer wall of phase change material
204b: Inner wall of phase change material
B: Thickness of outer wall of phase change material
Fig. 3:
301: Charging without phase change material
302: Charging with phase change material
303: Discharging without phase change material
304: Discharging with phase change material.
Fig. 4:
401: Perforations
402: Fire extinguisher material
403: Vent
404: Slots