DESC:TECHNICAL FIELD
The present disclosure relates generally to battery technology and more specifically, to a Zinc Bromine Static Battery (ZBSB) apparatus, a bilayer current collector for the ZBSB apparatus and a method of preparation of the bilayer current collector for the ZBSB apparatus.
BACKGROUND
Typically, a battery apparatus includes a current collector that acts as a conductive pathway for a flow of electrons between electrochemical reactions occurring in an electrode of the battery apparatus and an external circuit. The current collector facilitates a transfer of electrical charges generated during chemical reactions within the battery apparatus. The current collector is generally manufactured from materials exhibiting high electrical conductivity, resistance to corrosion induced by an electrolyte of the battery apparatus, and resilience against the electrochemical reactions (i.e., redox reactions) to avoid rapid consumption. in such cases, the battery apparatus may be a zinc-bromine battery (ZBB) apparatus due to their potential long life, deep discharge characteristics and potential low manufacturing cost.
Conventionally, the current collectors of the ZBB apparatus are composed of metallic materials such as copper or aluminium and form a critical interface between the electrodes of the ZBSB apparatus and the external electrical circuit. However, one of the technical challenges with the conventional current collector of the zinc-bromine batteries is corrosion during charging and discharging (i.e., specifically charge and discharging redox couple (Br-/Br2) at the cathode) leading to reduction in coulomb efficiency over a period of time. Further, for conventional zinc-based batteries (e.g., conventional zinc-bromine static batteries), it is observed that the conventional cathode current collector generally corrodes due to oxidation followed by formation of a passivation layer on it, resulting in decrease of ionic conduction and increase of electrical resistance to the flow of electrons and further reduces the operational life of the ZBB apparatus. Typically, the passivation layer is a thin, protective oxide layer formed typically on metals' surface due to oxygen when metals come into contact with oxygen. Furthermore, widespread use of metallic current collectors of the ZBB apparatus is hindered by inherent limitations challenges such as dendrite formation, mechanical stress, and limited conductivity.
Therefore, in light of the foregoing discussion, there exists a need to overcome the aforementioned drawbacks associated with the conventional current collectors and the method of preparation of the same.
SUMMARY
The present disclosure provides a bilayer current collector for a Zinc Bromine Static Battery (ZBSB) apparatus and a method of preparation of the bilayer current collector for the ZBSB apparatus. The present disclosure provides a solution to the technical problem of how to enhance the corrosion resistance and overall performance of current collectors in Zinc Bromine Static Batteries, particularly addressing issues related to coulomb efficiency reduction, passivation layer formation, and operational life limitations. An aim of the present disclosure is to provide a solution that overcomes at least partially the problems encountered in the prior art and provide the bilayer current collector for the ZBSB apparatus that effectively mitigates corrosion during charge and discharge cycles, reduces the formation of passivation layers on the cathode current collector, and enhances the overall efficiency and longevity of the ZBSB apparatus. Further, the aim of the present disclosure is to provide an improved ZBSB apparatus with enhanced performance, and a method of preparation of the bilayer current collector for the ZBSB apparatus that involves adding an electrically conductive filler to a substrate made of a fluoride-based polymer, followed by joining this layer with an electrically conductive polyethylene layer through a hot rolling operation. This method aims to achieve superior adhesion and conductivity, addressing the shortcomings of conventional current collector preparation methods and contributing to the enhanced performance of the ZBSB apparatus.
One or more objectives of the present disclosure are achieved by the solutions provided in the enclosed independent claims. Advantageous implementations of the present disclosure are further defined in the dependent claims.
In one aspect, the present disclosure provides the bilayer current collector for the ZBSB apparatus, the bilayer current collector includes an electrically conductive fluoride-based polymer layer comprising an electrically conductive filler. Further the electrically conductive fluoride-based polymer layer is in contact with a cathode layer and an electrically conductive polyethylene layer is devoid of a fluoride group-containing polymer. Further the electrically conductive polyethylene layer is in contact with an anode layer.
The current collector (e.g. a cathode current collector and an anode current collector), when implemented as the bilayer current collector, enhances the operational efficiency of ZBSB apparatus. The bilayer current collector is combination of the electrically conductive fluoride-based polymer layer and the electrically conductive polyethylene layer devoid of a fluoride group-containing polymer. Beneficially, the electrically conductive fluoride-based polymer layer facing the cathode layer enhances the conductivity of the cathode layer, allowing for efficient electron transfer during the operation of the ZBSB apparatus. During charging and discharging, element bromine/bromide ion species are produced at the cathode layer. The fluorine being the most electronegative element in a periodic table i.e. fluorine has a strong tendency to attract electrons toward itself in the chemical bond and thus remains stable in bromine environment. Further, an electrically conductive filler imparts electrical conductivity to the fluoride-based polymer layer. The electrically conductive polyethylene layer ensures compatibility with the anode layer. Absence of fluoride in electrically conductive polyethylene ensures no unwanted reactions or degradation occurs at anode layer. The arrangement of fluoride-based polymer layer and electrically conductive polyethylene layer synergistically works together to achieve improved performance and stability of the ZBSB apparatus. Further, polymer-based current collectors are not only less expensive but also contribute to increased power density and energy density of ZBSB apparatus.
In accordance with an embodiment, the electrically conductive polyethylene layer is a high-density polyethylene layer having a density of 0.93- 0.97 gram per cubic centimetre. Beneficially, the specific density range ensures compatibility with the anode layers and the ZBSB apparatus achieves improved electrical conductivity without compromising the overall functionality and integrity of the ZBSB apparatus.
In accordance with an embodiment, the electrically conductive fluoride-based polymer layer of the bilayer current collector comprises a polyvinylidene fluoride (PVDF) layer as a substrate containing a fluoride group-containing polymer in which the electrically conductive filler is added to obtain the electrically conductive fluoride-based polymer layer.
The substrate in fluoride-based polymer layer of the bilayer current collector when implemented as PVDF ensures stability in bromine environment at the cathode layer. When PVDF is exposed to a bromine environment, the carbon-fluorine (C-F) bonds in the PVDF molecular structure remain stable. Bromine being less electronegative than fluorine, bromine cannot easily break the strong C-F bonds in the PVDF. The stability of the C-F bonds ensures that the substrate implemented as PVDF maintains its structural integrity and chemical resistance even in the presence of bromine.
In accordance with an embodiment, the electrically conductive filler is a non-metal. The electrically conductive filler when implemented as the non-metal ensures that the stability of the bilayer current collector during the oxidation process on a side of the cathode layer. However, metal-based current collectors prepared using copper, aluminium, and nickel, are not stable during oxidation process.
In accordance with an embodiment, the electrically conductive filler is made of carbon. As the electrically conductive filler is made of carbon which are usually light weight, making the ZBSB apparatus lightweight and compact. Further addition of the electrically conductive filler made of carbon has high thermal conductivity. The high thermal conductivity ensures that carbon-based fillers are valuable in applications where efficient heat dissipation is required, for example, in thermal management of ZBSB apparatus. Further, carbon-based electrically conductive filler exhibits good chemical stability which makes carbon-based fillers resistant to corrosion and degradation, ensuring the longevity and reliability of ZBSB apparatus.
In accordance with an embodiment, the electrically conductive fluoride-based polymer layer comprises 70-90% by weight of polyvinylidene fluoride (PVDF) and 10-30% by weight of Super-P carbon (SPC). The combination of PVDF and SPC provides a synergistic effect, optimizing the electrical conductivity, adhesion, processability, and cost-effectiveness of the the electrically conductive fluoride-based polymer layer. This ultimately leads to a more efficient and reliable bilayer current collector of ZBSB apparatus. The combination minimizes agglomeration of SPC particles, ensuring a homogenous the electrically conductive fluoride-based polymer layer for consistent conductivity and performance.
In accordance with an embodiment, the electrically conductive fluoride-based polymer layer comprises 70% by weight of polyvinylidene fluoride (PVDF) and 30% by weight of Super-P carbon (SPC). Advantageously, mixing 70% by weight of polyvinylidene fluoride (PVDF) and 30% by weight of Super-P carbon (SPC) is more effective in providing conductive pathway when combined with PVDF.
In accordance with an embodiment, the electrically conductive polyethylene layer is joined with the fluoride-based polymer layer at a temperature ranging from 150-250 degree Celsius to obtain the bilayer current collector. The temperature range ensures a strong bond between the electrically conductive polyethylene layer and the fluoride-based polymer layer, ensuring long-term stability and reliable performance of the bilayer current collector. The interconnection between the electrically conductive polyethylene layer and the fluoride-based polymer layer enhances the overall conductivity and durability of the bilayer current collector, enabling effective utilization of the bilayer current collector in the ZBSB apparatus.
In accordance with an embodiment, the electrically conductive fluoride-based polymer layer has a thickness ranging from 30-50 micrometers (µm). The thickness of the electrically conductive fluoride-based polymer layer impacts the performance of the bilayer current collector, particularly in terms of conductivity. Higher than 50 Micrometre (µm) thickness is found to reduce the conductivity and increase electrical resistance whereas less than 30 µm may not provide adequate conductivity, leading to inefficient electron transfer and poor electrochemical performance of the bilayer current collector.
In accordance with an embodiment, the bilayer current collector has a thickness ranging from 200-240 µm. The thickness range of the bilayer current collector layer impacts the performance of ZBSB. The thickness of higher than 75 micrometre of coating is found to reduce tunnelling efficiency and increase electrical resistance whereas the thickness of less than 25 µm may not provide adequate coverage or conductivity, leading to inefficient electron transfer and poor electrochemical performance.
In accordance with an embodiment, the bilayer current collector has a thickness of 220 µm. The bilayer current collector with thickness of 220 µm exhibits highest conductivity among other thickness range of the bilayer current collector. The overall thickness of the bilayer current collector directly influences the interaction and interrelation between various components of the battery system, allowing for seamless integration and efficient operation. By maintaining a specific thickness, the bilayer collector achieves a technical effect that enhances the overall functionality and reliability of the bilayer collector, without compromising its structural integrity or impeding its intended purpose.
In second aspect, the present disclosure provides a ZBSB apparatus comprising a first cell and a second cell. The first cell comprises a first cathode layer, a first anode layer, and a first separator layer disposed between the first cathode layer and the first anode layer. The second cell comprises a second cathode layer, a second anode layer, and a second separator layer disposed between the second cathode layer and the second anode layer. The bilayer current collector is sandwiched between the first cathode layer of the first cell and the second anode layer of the second cell. The bilayer current collector includes the electrically conductive fluoride-based polymer layer comprising an electrically conductive filler. Further the electrically conductive fluoride-based polymer layer is in contact with the first cathode layer; and the electrically conductive polyethylene layer devoid of the fluoride group-containing polymer. Furthermore, the electrically conductive polyethylene layer is in contact with the second anode layer.
The method achieves all the advantages and technical effects of the bilayer current collector of the ZBSB apparatus of the present disclosure.
In third aspect, the present disclosure provides a method of preparation of the bilayer current collector for the ZBSB apparatus. The method comprises adding the electrically conductive filler on the substrate made of the fluoride-based polymer to form the electrically conductive fluoride-based polymer layer; and joining the formed electrically conductive fluoride-based polymer layer with the electrically conductive polyethylene layer devoid of the fluoride group-containing polymer to form the bilayer current collector for the ZBSB apparatus.
The method achieves all the advantages and technical effects of the bilayer current collector of the ZBSB apparatus of the present disclosure.
It has to be noted that all devices, elements, circuitry, units and means described in the present application could be implemented in the software or hardware elements or any kind of combination thereof. All steps which are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external entities is not reflected in the description of a specific detailed element of that entity which performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements, or any kind of combination thereof. It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.
Additional aspects, advantages, features and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative implementations construed in conjunction with the appended claims that follow.
BRIEF DESCRIPTION OF THE DRAWINGS
The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:
FIG. 1A is a diagram illustrating an exploded view of a cell of a zinc bromine static battery (ZBSB) apparatus, in accordance with an embodiment of the present disclosure;
FIG. 1B is a diagram illustrating a cross-sectional view of the ZSBS apparatus, in accordance with an embodiment of the present disclosure;
FIG. 1C is a diagram illustrating a top view of the ZBSB apparatus, in accordance with an embodiment of the present disclosure;
FIG. 2 is a diagram illustrating a process of preparation of a bilayer current collector for the ZBSB apparatus, in accordance with an embodiment of the present disclosure;
FIG. 3A is a diagram illustrating a galvanostatic charge-discharge (GCD) profile of the ZBSB apparatus with the bilayer current collector, in accordance with an embodiment of the present disclosure;
FIG. 3B is a diagram illustrating a GCD profile of the ZBSB apparatus with bilayer current collector with fluoride-based polymer layer composition of 70% by weight of PVDF and 30% by weight of SPC, in accordance with an embodiment of the present disclosure;
FIG. 4 is a diagram illustrating a cross sectional view of a cell of a ZBSB apparatus, in accordance with another embodiment of the present disclosure;
FIG. 5 is a diagram illustrating a GCD profile of the ZBSB apparatus of FIG. 4, in accordance with another embodiment of the present disclosure; and
FIG. 6 is a flowchart of a method of preparation of the bilayer current collector, in accordance with an embodiment of the present disclosure.
In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.
DETAILED DESCRIPTION OF EMBODIMENTS
The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practicing the present disclosure are also possible.
FIG. 1A is a diagram illustrating an exploded view of a cell of a zinc bromine static battery (ZBSB) apparatus, in accordance with an embodiment of the present disclosure. With reference to FIG. 1A, there is shown a ZBSB apparatus 100 includes a plurality of cell layers 102. The plurality of cell layers 102 includes a first cell 102A, a second cell 102B, a third cell 102C…, and an Nth cell 102N. In the illustrated embodiment of FIG. 1A, the second cell 102B includes a second cathode layer 108B, a second anode layer 104B, and a second separator layer 106B disposed between the second cathode layer 108B and the second anode layer 104B. The second anode layer 104B is in contact with an electrically conductive polyethylene layer 110B of a bilayer current collector. The bilayer current collector is sandwiched between two consecutive cells (in this case, the first cell 102A and the second cell 102B).
It should be noted that, for illustration purposes, only the second cell 102B is explicitly shown in FIG. 1A. However, each cell in the ZBSB apparatus 100 is structurally similar, sharing common features and functionalities. The omitted cells (e.g., 102A, 102C to 102N) adhere to the same design principles and components, differing only in their sequential arrangement within the battery stack.
The ZBSB apparatus 100 refers to a type of rechargeable battery that uses zinc and bromine as its active materials in which the static property comes from the fact that zinc-bromine static battery apparatus 100 may not require any pumps or moving parts to circulate the electrolyte, unlike a flow battery. Further, the ZBSB apparatus 100 involves a redox reaction between zinc and bromine ions. During discharge, zinc is oxidized at the anode, releasing electrons, while bromine is reduced at the cathode, accepting electrons. During charging, this process is reversed.
The plurality of cells 102 in the ZBSB apparatus 100 refers to the multiple individual electrochemical cells that are connected together to form the overall battery. The plurality of cells 102 are arranged in a stack within the ZBSB apparatus 100.
Each cell of the plurality of cells 102 (for example, the first cell 102A, the second cell 102B…., and the Nth cell 102N) refers to an individual electrochemical unit within the ZBSB apparatus 100 where the conversion of chemical energy to electrical energy takes place (i.e. through redox reactions). Each cell consists of an anode layer (for example, the second anode layer 104B) and a cathode layer (for example, the second cathode layer 108B) immersed in an electrolyte solution containing zinc and bromine compounds. Further, each cell include a separator layer (for example, the second separator layer 106B) between the anode layer and the cathode layer.
FIG. 1B is a diagram illustrating a cross-sectional view of the ZBSB apparatus, in accordance with an embodiment of the present disclosure. With reference to FIG. 1B, there is shown the ZBSB apparatus 100 which includes the first cell 102A and the second cell 102B of the plurality of cells 102 for illustration purposes. the first cell 102A includes a first cathode layer 108A, a first anode layer 104A, and a first separator layer 106A disposed between the first cathode layer 108A and the first anode layer 104A. As discussed above, the second cell 102B includes the second anode layer 104B, the second separator layer 106B, and the second cathode layer 108B. The ZBSB apparatus 100 further includes a bilayer current collector 110 sandwiched between the first cell 102A and the second cell 102B. Specifically, the bilayer current collector 110 is sandwiched between the first cathode layer 108A of the first cell 102A and the second anode layer 104B of the second cell 102B. The bilayer current collector 110 is composed of two layers, that is a first layer 110A and a second layer 110B. The first layer of the bilayer current collector 110 is an electrically conductive fluoride-based polymer layer (interchangeably referred to as the first layer 110A) comprising an electrically conductive filler. The second layer 110B of the bilayer current collector 110 is an electrically conductive polyethylene layer (interchangeably referred to as the second layer 110B) devoid of a fluoride group-containing polymer. The electrically conductive fluoride-based polymer layer 110A is in contact with the first cathode layer 108A and the electrically conductive polyethylene layer 110B is in contact with the second anode layer 104B. The first anode layer 104A is in contact with an electrically conductive polyethylene layer 112 (similar to the second layer 110B) of another bilayer current collector (not shown for illustration purposes). The second cathode layer 108B is in contact with an electrically conductive fluoride-based polymer layer 114 (similar to the first layer 110A) comprising an electrically conductive filler of another bilayer current collector (not shown for illustration purposes).
The anode layer (for example, the first anode layer 104A and the second anode layer 104B) in the ZSBS battery 100 refers to an electrode where oxidation takes place during the discharge phase of an electrochemical cell. Specifically, in the case of the ZBSB battery 100, zinc (Zn) is used as an anode material, the anode layer is the region or component where metallic zinc undergo oxidation. In case of the first anode layer 104A, during a charging process, zinc ions in the electrolyte flows to the first anode layer 104A and are deposited at the first anode layer 104A in a solid state (i.e., Zn is plated at the first anode layer 104A). Further, two electrons are released from the first cathode layer 108A, travel through the external circuit, and are accepted by the zinc ions at the first anode layer 104A. The acceptance of the electrons by the zinc ions at the first anode layer 104A is known as a zinc plating process. During a discharging process, zinc plated at the first anode layer 104A releases two electrons that forms zinc ions. The zinc ions are then dissolves in the electrolyte. Simultaneously, the released electrons are accepted by element bromine of the first cathode layer 108A to form mobile bromide ions which in turn also dissolves in the electrolyte. In case of the second anode layer 104B, during the charging process, the Zn ions in the electrolyte flows to the second anode layer 104B and are deposited at the second anode layer 104B in a solid state (i.e., the metallic zinc is plated at the second anode layer 104B). Yet again, during the Zn plating process, two electrons released from the second cathode layer 108B travel through the external circuit and are accepted by the zinc ions at the second anode layer 104B. During the discharging process, the zinc plated at the second anode layer 104B releases two electrons that forms the zinc ions. The zinc ions then dissolves in the electrolyte. Further, the released electrons are accepted by the element bromine of the second cathode layer 108B to form the mobile bromide ions which in turn also dissolves in the electrolyte.
The cathode layer (for example, the first cathode layer 108A and the second cathode layer 108B) refers to the electrode where reduction reactions occur during the discharge phase of the electrochemical cell. Specifically, in the case of the ZBSB apparatus 100, the cathode layer is a component where bromine molecules are reduced. In case of the first cathode layer 108A, during the charging process, the bromide ions from the electrolyte are oxidized and forms the element bromine that is generated on the first cathode layer 108A. During formation of the element bromine in the charging process, two electrons are released at the first cathode layer 108A, where the two electrons travel through the external circuit and accepted by the zinc ions at the first anode layer 104A, and where the zinc ions after accepting the two electrons gets plated at the first anode layer 104A of the first cell 102A. During the discharge process, the element bromine generated on the first cathode layer 108A accepts two electrons (received from the first anode layer 104A via the external circuit) and the element bromine is reduced that forms the bromide ions. The bromide ions are then dissolved in the electrolyte. In case of the second cathode layer 108B, during the charging process, the bromide ions from the electrolyte are oxidized and forms the element bromine that is generated on the second cathode layer 108B. During formation of the bromide ion in the charging process, the two electrons are released at the second cathode layer 108B, where the two electrons travel through the external circuit and accepted by the zinc ions at the second anode layer 104B, and where the zinc ions after accepting the two electrons gets plated at the second anode layer 104B of the first cell 102B. During the discharge process, the element bromine generated on the first cathode layer 108B accepts two electrons (received from the first anode layer 104B via the external circuit) and the element bromine are reduced forming bromide ions. The bromide ions are then dissolved in the electrolyte.
The separator layer (for example, the first separator layer 106A and the second separator layer 106B) refers to a component that physically and electrically separates the anode and cathode within a cell. The primary purpose of the separator layer is to prevent direct contact between the positive and negative electrodes while allowing the flow of ions between them. In an example, the first separator layer 106A separates the first anode layer 104A and the first cathode layer 108A. The first separator layer 106A have submicron-sized pores and the pores work as channels where ions move between the first anode layer 104A and the first cathode layer 108A. Examples of the implementation of the first separator layer 106A may include, but are not limited to, an absorption glass Mat (AGM), a polyethylene (PE) or a sulfonated tetrafluoroethylene based fluoropolymer-copolymer. In another example, the second separator layer 106B separates the second anode layer 104B and the second cathode layer 108B. The second separator layer 106B have submicron-sized pores and the pores work as channels where ions move between the second anode layer 104B and the second cathode layer 108B. Examples of the implementation of the second separator layer 106B may include, but are not limited to an absorption glass metal (AGM), a polyethylene (PE) or a sulfonated tetrafluoroethylene based fluoropolymer-copolymer.
The bilayer current collector 110 refers to a specialized structure used in certain types of batteries, including the ZBSB apparatus 100. The bilayer current collector 110 in the ZBSB apparatus 100 act as a conductive pathway for the flow of electrons between the electrochemical reactions (i.e., redox reactions) occurring in the cathode layers and the anode layers of the ZBSB apparatus 100 and an external circuit. The bilayer current collector 110 facilitates the transfer of electrical charges generated during the chemical reactions within the ZBSB apparatus 100.
In some implementations, the bilayer current collector 110 has a thickness ranging from 200-240 µm. In some other implementations, the bilayer current collector 110 has a thickness of 220 µm.
The bilayer current collector 110 consists of two distinct layers with different materials, each serving specific functions within the battery system. The bilayer current collector 110 includes the electrically conductive fluoride-based polymer layer 110A and the electrically conductive polyethylene layer 110B.
The electrically conductive fluoride-based polymer layer 110A includes an electrically conductive filler. The electrically conductive filler refers to a material that possesses the ability to conduct electricity, typically used to enhance the electrical conductivity of a composite or matrix material (for e.g. polymers). In some implementations, the electrically conductive filler is a non-metal. By incorporating the electrically conductive filler made of a non-metal, the electrically conductive fluoride-based polymer layer 110A remains stable during an oxidation process on a side of the cathode layer. However, metal-based current collectors prepared using copper, aluminum, and nickel, may get oxidized during the oxidation process. In some other implementations, the electrically conductive filler is made of carbon. In some examples, the electrically conductive filler is made of Super-P carbon (SPC). For example, other carbon-based fillers may include, but are not limited to carbon fibers and graphene. The carbon-based fillers enhance the strength and stiffness of materials, making them suitable for applications requiring both electrical conductivity and structural integrity.
The electrically conductive fluoride-based polymer layer 110A refers to a type of polymer that contains fluorine atoms in its molecular structure. The fluoride-based polymer is a specific class of polymers that have unique properties due to the presence of fluorine. In some implementations, the electrically conductive fluoride-based polymer layer 110A of the bilayer current collector 110 includes a polyvinylidene fluoride (PVDF) layer as a substrate containing a fluoride group-containing polymer in which the electrically conductive filler is added to obtain the electrically conductive fluoride-based polymer layer 110A. When the PVDF is exposed to a bromine environment, the carbon-fluorine bonds in the PVDF molecular structure remain stable. Bromine being less electronegative than fluorine, bromine cannot easily break the strong (C-F) bonds in the PVDF. The stability of the (C-F) bonds ensures that the PVDF maintains its structural integrity and chemical resistance even in the presence of bromine. The stability of the PVDF in a bromine environment reflects inertness to chemical attack.
In some examples, the electrically conductive fluoride-based polymer layer 110A includes 70-90% by weight of polyvinylidene fluoride (PVDF) and 10-30% by weight of SPC. In some other examples, the electrically conductive fluoride-based polymer layer 110A includes 70% by weight of polyvinylidene fluoride (PVDF) and 30% by weight of SPC. In some other examples, the bilayer current collector 110 may include polytetrafluoroethylene (PTFE) and perfluoro alkoxy (PFA) resin. In some implementations, the electrically conductive fluoride-based polymer layer 110A has a thickness ranging from 30-50 micrometres (µm). The specific thickness range results in stable electrical characteristics of the electrically conductive fluoride-based polymer layer 110A. The controlled thickness range facilitates in preventing excessive stress and degradation of the electrically conductive fluoride-based polymer layer 110A which contributes to an extended lifespan of the bilayer current collector 110, promoting durability and reliability over multiple charge-discharge cycles. In some implementations, the electrically conductive fluoride-based polymer layer 110A is in contact with a cathode layer. In some examples, the electrically conductive fluoride-based polymer layer 110A is in contact with the first cathode layer 108A. The use of the electrically conductive fluoride-based polymer layer 110A enhances the conductivity of the cathode layer, allowing for efficient electron transfer during the operation of ZBSB apparatus 100.
The electrically conductive fluoride-based polymer layer 110A of the bilayer current collector 110 exhibits resistance to chemicals such as solvents and acids present in the electrolyte (i.e. zinc bromide). A substrate is the medium in which a chemical reaction takes place or the reagent in a reaction that provides a surface for absorption. The fluorine being most electronegative element in a periodic table has a strong tendency to attract electrons toward itself in the chemical bond. If PVDF is used as the electrically conductive fluoride-based polymer layer 110A of the bilayer current collector 110, the fluorine atoms form strong bonds with the carbon atoms in the polymer chain. The result is a strong element bromine environment, that is resistant to degradation.
The electrically conductive polyethylene layer 110B is devoid of a fluoride group-containing polymer. The electrically conductive polyethylene layer 110B is the high-density polyethylene layer that serves as the electrically conductive component. The purpose of high-density polyethylene layer purpose is to provide electrical conductivity while maintaining a specific density range. In some implementations, the electrically conductive polyethylene layer 110B is a high-density polyethylene layer having a density of 0.93- 0.97 gram per cubic centimetre. In some implementations, the electrically conductive polyethylene layer 110B is in contact with an anode layer. In some examples, the electrically conductive polyethylene layer 110B is in contact with the first anode layer 104B. The electrically conductive polyethylene layer 110B facilitates a flow of electrons from the anode during the discharge phase of the battery operation.
In some examples, various other feasible polymer layers may be used as an anode side layer of the bilayer current collector 110. Some examples of other feasible polymer layers includes Polyurethane (PU), Poly Tetra Fluoro Ethylene (PTFE). PU and PTFE are commonly employed as the anode side layer of the bilayer current collector 110 but are prone to degradation, leading to suboptimal battery performance. HDPE is better performer, showcasing robust and enduring characteristics. The utilization of HDPE as the anode side layer of the bilayer current collector 110 significantly contributed to a life enhancement of the ZBSB apparatus 100. The distinctive resilience and stability exhibited by the HDPE make it an excellent choice for applications where durability and long-term functionality are paramount.
In some examples, change in thicknesses of the electrically conductive fluoride-based polymer layer 110A and the electrically conductive polyethylene layer 110B (for e.g., HDPE sheet) of the bilayer current collector 110 may offer different electrical properties, as shown in Table 1 provided below.
Table 1: Thickness of the bilayer current collector and the significance of the specific thickness.
Commercial HDPE sheet Fluoride-based polymer layer tthickness
(PVDF:SPC,70:30) Thickness of bilayer current collector Resistance
(Ohm) Resistivity
(Ohm.meter) Conductivity
(per Ohm per meter)
200 µm 10 µm 195 µm 145.5 4.85 2.27 X 10-4
200 µm 30 µm 207 µm 90.7 2.85 3.46 X 10-4
200 µm 50 µm 220 µm 51.0 1.51 5.79 X 10-4
200 µm 70 µm 235 µm 77.5 2.14 3.57 X 10-4
200 µm 100 µm 275 µm 98.4 2.33 2.40 10-4
As enumerated in Table 1, electrically conductive fluoride-based polymer layer 110A with thickness in range of 30-50 µm exhibit good conductivity as compared to other thickness ranges. Further, specific thickness range ensures a resistance, and a resistivity does not increase to large extent for example in case when the fluoride-based polymer layer 110A is of thickness 100 µm, resistance rises to 98.4 ohms (as depicted in Table 1). Controlled resistance is crucial for maintaining good conductivity, reducing energy losses, and preventing excessive heat generation during the operation of the ZBSB apparatus 100. The resistivity remains relatively consistent within the specified thickness range. The advantages include preventing the resistance from increasing to a large extent. Excessive resistance can lead to reduced efficiency and overall performance degradation. Maintaining resistance within reasonable limits ensures that the current collector functions optimally over the operational lifespan of the ZBSB apparatus 100. The controlled resistance and resistivity contribute to enhanced predictability in the performance of the ZBSB apparatus 100. The predictability is beneficial for designing and optimizing the battery system for specific applications, ensuring reliable and consistent operation under varying conditions.
The specific dimension plays a crucial role in the functionality of the bilayer current collector 110 as specific dimension ensures the optimal performance and compatibility with other entities within the ZBSB apparatus 100. With reference to Table 1, it can be predicted that the bilayer current collector 110 with thickness 220 µm gives conductivity of 5.79 X 10-4 per Ohm per meter, highest among all other counterparts. Overall thickness of the bilayer current collector 110 directly influences the interaction and interrelation between various components of the ZBSB apparatus 100, allowing for seamless integration and efficient operation. By maintaining a specific thickness, the bilayer current collector 110 achieves a technical effect that enhances the overall functionality and reliability of the bilayer current collector 110, without compromising its structural integrity.
FIG. 1C is a diagram illustrating top view of the ZBSB apparatus. With reference to FIG.1C there is shown a top view of ZBSB apparatus 100 depicting the plurality of cell layers 102, an electrolyte filling slot 116, additionally a plurality of fixing means 118 (e.g., screw-bolt based fixing means), a first base plate 120 and a second base plate 122.
The electrolyte filling slot 116 facilitate the introduction of the electrolyte into the ZBSB apparatus 100. The electrolyte filling slot 116 allows the easy pouring of gel-based electrolyte into the ZBSB apparatus 100 via this designated slot, avoiding mixing of electrolytes among different cells thus avoiding short circuiting or any other discrepancy which could arise out of mixing of electrolytes of different cells of the ZBSB apparatus 100. Hence increasing operational life of the ZBSB apparatus 100. In an implementation, during the assembly of the ZBSB apparatus 100, the first base plate 130, the plurality of cell layers 102, and the second base plate 132 are compressed together. In an implementation the plurality of fixing means 128 are inserted through peripheral portions of each of the first base plate 130, and the second base plate 132.
FIG. 2 is a diagram illustrating a process of preparation of a bilayer current collector for the ZBSB apparatus, in accordance with an embodiment of the present disclosure. With reference to FIG. 2, there is shown a schematic diagram 200 illustrating the process of preparation of the bilayer current collector 110 for the ZBSB apparatus 100. The electrically conductive polyethylene layer 110B is joined with the fluoride-based polymer layer 110A at a temperature ranging from 150-250 degree Celsius to obtain the bilayer current collector 110. During this thermal treatment, the polymers undergo a controlled bonding, creating a robust interface between the layers. The selected temperature range is crucial for ensuring proper adhesion and structural integrity of the bilayer current collector 110. The joined layers play a pivotal role in addressing challenges associated with conventional current collectors, such as corrosion and passivation, ultimately contributing to the enhanced efficiency, longevity, and overall performance of the ZBSB apparatus 100. The temperature-controlled joining process optimizes the integration of the electrically conductive polyethylene layer 110B and the electrically conductive fluoride-based polymer layer 110A, ensuring their compatibility and functionality in the demanding operational environment of the battery system.
FIG. 3A is a diagram illustrating a galvanostatic charge-discharge (GCD) profile of the ZBSB apparatus with the bilayer current collector, in accordance with an embodiment of the present disclosure. With reference to FIG. 3A, there is shown a graphical representation 300A of a GCD profile of the ZBSB apparatus 100 with the bilayer current collector 110. Capacity is expressed in milli Ampere hour (mAh) at an abscissa axis of the graphical representation 300A. Cell voltage is expressed in Volt (V) at ordinate. The graphical representation 300A includes a first curve 302A depicting a charging profile of the ZBSB apparatus 100, and a second curve 304A depicting a discharging profile of the ZBSB apparatus 100.
FIG. 3B is a diagram illustrating a GCD profile of the ZBSB apparatus having a bilayer current collector with fluoride-based polymer layer composition of 70% by weight of PVDF and 30% by weight of SPC, in accordance with an embodiment of the present disclosure. With reference to FIG. 3B, there is shown a graphical representation 300B of the GCD profile of the ZBSB apparatus 100 having the bilayer current collector with the fluoride-based polymer layer composition of 70% by weight of PVDF and 30% by weight of SPC. Capacity is expressed in milli Ampere hour (mAh) at an abscissa axis of the graphical representation 300B. Cell voltage is expressed in Volt (V) at ordinate. The graphical representation 300B includes a first curve 302B depicting a charging profile of the ZBSB apparatus 100 having the bilayer current collector with the fluoride-based polymer layer composition of 70% by weight of PVDF and 30% by weight of SPC, and a second curve 304B depicting a discharging profile of the ZBSB apparatus 100 having the bilayer current collector with the fluoride-based polymer layer composition of 70% by weight of PVDF and 30% by weight of SPC.
FIG. 4 is a diagram illustrating a cross sectional view of a cell of a ZBSB apparatus, in accordance with another embodiment of the present disclosure. With reference to FIG. 4, there is shown a cell 400 that may be used in the ZBSB apparatus 100. The cell 400 is substantially similar to each cell of the plurality cells 102 (of FIG. 1), in terms of functionality. The cell 400 includes an anode layer 402, a cathode layer 404, and a separator layer 406 sandwiched between the anode layer 402 and the cathode layer 404. The cell 400 further includes a first anode side layer 408 of a bilayer current collector (only shown a side layer of the bilayer current collector in FIG. 4 for illustration purposes) and a first cathode side layer 410 of another bilayer current collector (only shown a side layer of the bilayer current collector in FIG. 4 for illustration purposes). The first anode side layer 408 is in contact with the anode layer 402. Further, the first cathode side layer 410 is in contact with the cathode layer 404. Both the first anode side layer 408 and the first cathode side layer 410 are made of HDPE sheets.
FIG. 5 is a diagram illustrating a GCD profile of the ZBSB apparatus of FIG. 4, in accordance with another embodiment of the present disclosure. With reference to FIG. 5, there is shown a graphical representation 500 of a GCD profile of the ZBSB apparatus 100 with the bilayer current collector having both layers of HDPE. Capacity is expressed in milli Ampere hour (mAh) at an abscissa axis of the graphical representation 500. Cell voltage is expressed in Volt (V) at ordinate of the graphical representation 500. The graphical representation 500 includes a first curve 502 depicting a charging profile of the ZBSB apparatus 100 with the bilayer current collector having both layers of HDPE, and a second curve 504 depicting a discharging profile of the ZBSB apparatus 100 with the bilayer current collector having both layers of HDPE.
FIG. 6 is a flowchart of a method of preparation of a bilayer current collector for a Zinc Bromine Static Battery (ZBSB) apparatus, in accordance with an embodiment of the present disclosure. FIG. 6 is described in conjunction with elements from FIG. 1A to 5. With reference to FIG. 6, there is shown a method 600 for preparation of the bilayer current collector 110 for the ZBSB apparatus 100. The method 600 includes steps 602 to 604.
At step 602, the method 600 includes adding the electrically conductive filler on a substrate made of a fluoride-based polymer to form the electrically conductive fluoride-based polymer layer 110A.
Further, step 602 includes a sub-step 602A which includes adding of the electrically conductive filler on the substrate made of the fluoride-based polymer to form the electrically conductive fluoride-based polymer layer 110A includes mixing 70% by weight of polyvinylidene fluoride (PVDF) and 30% by weight of Super-P carbon (SPC).
At step 604, the method 600 includes joining the formed electrically conductive fluoride-based polymer layer 110A with the electrically conductive polyethylene layer 110B devoid of a fluoride group-containing polymer to form the bilayer current collector 110 for the ZBSB apparatus 100.
Further, step 604 includes a sub-step 604A which include joining of the formed electrically conductive fluoride-based polymer layer 110A with the electrically conductive polyethylene layer 110B devoid of the fluoride group-containing polymer includes disposing the formed electrically conductive fluoride-based polymer layer 110A over the electrically conductive polyethylene layer 110B and applying a hot rolling operation at a temperature ranging from 150-250 degree Celsius for the joining.
Hot rolling operation is a metalworking process in which metal is heated above the recrystallization temperature to plastically deform it in the working or rolling operation. The process is used to create shapes with the desired geometrical dimensions and material properties while maintaining the same volume of metal. The hot metal is passed between two rolls to flatten it, lengthen it, reduce the cross-sectional area, and obtain a uniform thickness.
The steps 602 to 604 are only illustrative, and other alternatives can also be provided where one or more steps are added, one or more steps are removed, or one or more steps are provided in a different sequence without departing from the scope of the claims herein.
EXPERIMENTAL PART:
I. Material Used:
HDPE in form of sheets, PVDF powder, SPC (super p carbon) powder were directly used as the raw material for preparation of bilayer current collector.
II. EXAMPLE OF PREPARATION OF BILAYER CURRENT COLLECTOR
Example 1: preparation of bilayer current collector using HDPE sheets, PVDF powder and SPC powder
a) Preparation of a PVDF layer for bilayer current collector
PVDF powder was dispersed separately in first container in 5 ml of Dimethylformamide (DMF) solvent with magnetic stirring for 2 hours at 30°C which led to formation of solution one. The dried Super P carbon particles, with a size of 60 nm, were dispersed separately in 5 ml of DMF solvent with magnetic stirring for 0.5 hour at 30°C which led to formation of solution two. Finally, solution one and solution two were mixed for 10 hours with magnetic stirring. The resulting nanocomposite solution from mixture of solution one and solution two was then applied to a glass substrate and cast. The layer was left in an oven overnight at 70°C to allow the solvent to evaporate. The process was repeated to create layers with different PVDF and SPC ratios, such as, 80:20, 30:70, and 40:60, respectively.
b) Preparation of the bilayer current collector:
HDPE sheet of a thickness 200 µm was disposed over a PVDF layer with thickness 50 µm. The PVDF layer had PVDF and SPC in ratio of 70:30. The combined layer obtained underwent a hot-rolling pressing process using a custom-built setup. The hot-rolling pressing procedure involved heating up to temperatures ranging from 150 to 250 °C. As a result, a bilayer current collector was obtained, with an overall thickness of 220 µm.
Hot-rolling pressing is a manufacturing process that involves applying heat and pressure to shape or consolidate materials. The Hot-rolling pressing process is commonly used in the fabrication of metal and polymer components, and it often results in the creation of thin sheets, foils, or layers with specific properties.
c) Characterization:
The electrolyte mixture composed of three moles of Zinc Bromide (ZnBr2), one mole of Zinc Chloride (ZnCl2) and equal proportion of N-Methyl-N-Ethyl Pyrrolidinium Bromide (MEP) and N-Methyl-N-Ethyl Morpholinium Bromide (MEM) dissolved in deionized (DI) water, was prepared, and employed for the ZBSB apparatus 100. Galvanostatic charge-discharge (GCD) profile for the cell of ZBSB apparatus 100 were obtained for different configuration of the cells.
A galvanostatic charge-discharge curve is a graphical representation of the electrical behaviour of a battery or electrochemical cell during a controlled current process. In galvanostatic testing, a constant current is applied to the battery during both the charging and discharging phases. The resulting curve depicts how the voltage of the cell changes over time under this controlled current condition.
III. Results:
With reference to FIG. 3A, the GCD performance was conducted using a battery tester. The first cell 102A underwent testing at constant current densities 5 mA·cm?² for the charging-discharging process lasting 5 hours each. During charging the first cell 102A charged to 25 mAh but discharged around 19.45 mAh, due to ohmic resistance 51 ohms. The calculated coulombic efficiency, voltaic efficiency, and energy efficiency were 77.80%, 90.29%, and 70.25%, respectively. Similarly, the performance characteristics of the ZBSB apparatus 100 were evaluated by constructing the first cell 102A, utilizing the bilayer current collector with PVDF and SPC in 70:30 ratio.
The battery tester is a specialized device created to assess and evaluate the performance, health, and characteristics of batteries. The primary purpose of a battery tester is to measure and analyse key electrical parameters of batteries, including voltage, current, capacity, and internal resistance.
With reference to FIG. 3B, the first cell 102A charged to 25 mAh but discharged around 20.75 mAh, due to ohmic resistance 13.4 ohms. The calculated coulombic efficiency, voltaic efficiency, and energy efficiency were 83.00%, 90.50%, and 75.11%, respectively.
With reference to FIG. 5, the GCD performance was conducted using a battery tester. The cell 400 underwent a testing at constant current densities 5 mA·cm?² for a charging-discharging process lasting 5 hours each. The obtained GCD profile as illustrated in FIG. 5 for the cell of ZBSB apparatus 100 with HDPE as a current collector for an anode and a cathode. The GCD profile of the cell 400 depicts that the cell 400 was charged to 25 mAh but discharged at around 19.14 mAh, primarily due to higher ohmic resistance 150 ohms. Further the calculated Coulombic efficiency, voltaic efficiency, and energy efficiency were 76.55%, 90.29%, and 69.26%, respectively.
As inferred from above experimental data the cell with bilayer current collector with PVDF and SPC in 70:30 ratio current collector exhibits the least ohmic resistance 13.4 ohms as compared to another configuration of the cell.
Table 2:
SPC: PVDF CHARGING CAPACITY
(%) DISCHARGING CAPACITY
(%) COULOMBIC EFFICIENCY (%) VOLTAIC EFFICIENCY (%) ENERGY EFFICIENCY (%)
20:80 25 16.34 65.36 89.44 58.45
30:70 25 20.75 83 90.5 75.11
40:60 25 19.19 76.76 92.61 71.08
As enumerated in Table 2 the specific composition of 70% by weight of PVDF and 30% by weight of SPC exhibits the higher discharging capacity 20.75% (FIG. 2C) as compared to other compositions for example as enlisted in table 2 for .80% by weight of PVDF and 20% by weight of SPC discharging capacity is 16.34% and for 60% by weight of PVDF and 40% by weight of SPC discharging capacity is 19.19%. Actual discharging capacity is the amount of charge (in coulombs or ampere-hours) delivered by the battery during discharging cycle of the battery. Higher discharging capacity represents less amount of resistance offered by the current collector higher coulombic efficiency and hence in totality increases the columbic efficiency of the ZBSB apparatus 100.
Coulombic efficiency represents the ratio of the actual amount of charge delivered during discharging cycle of the battery to the theoretically calculated charge that was supplied during the preceding charging cycle of the battery. Coulombic efficiency is expressed as a percentage and is calculated using the following formula:
Coulombic Efficiency = [(Actual Discharging Capacity/Charging Capacity)] ×100
where the charging capacity is the theoretical amount of charge that was supplied to the battery during the preceding charge cycle.
Modifications to embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as "including", "comprising", "incorporating", "have", "is" used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural. The word "exemplary" is used herein to mean "serving as an example, instance or illustration". Any embodiment described as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or to exclude the incorporation of features from other embodiments. The word "optionally" is used herein to mean "is provided in some embodiments and not provided in other embodiments". It is appreciated that certain features of the present disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable combination or as suitable in any other described embodiment of the disclosure.
,CLAIMS:Claims
We claim:
1. A bilayer current collector (110) for a Zinc Bromine Static Battery (ZBSB) apparatus (100), the bilayer current collector (110) comprising:
an electrically conductive fluoride-based polymer layer (110A) comprising an electrically conductive filler, wherein the electrically conductive fluoride-based polymer layer (110A) is in contact with a cathode layer; and
an electrically conductive polyethylene layer (110A) devoid of a fluoride group-containing polymer, wherein the electrically conductive polyethylene layer (110B) is in contact with an anode layer.
2. The bilayer current collector (110) as claimed in claim 1, wherein the electrically conductive polyethylene layer (110B) is a high-density polyethylene layer having a density of 0.93- 0.97 gram per cubic centimetre.
3. The bilayer current collector (110) as claimed in claim 1, wherein the electrically conductive fluoride-based polymer layer (110A) of the bilayer current collector (110) comprises a polyvinylidene fluoride (PVDF) layer as a substrate containing a fluoride group-containing polymer in which the electrically conductive filler is added to obtain the electrically conductive fluoride-based polymer layer (110A).
4. The bilayer current collector (110) as claimed in claim 1, wherein the electrically conductive filler is a non-metal.
5. The bilayer current collector (110) as claimed in claim 1, wherein the electrically conductive filler is made of carbon.
6. The bilayer current collector (110) as claimed in claim 1, wherein the electrically conductive fluoride-based polymer layer (110A) comprises 70-90% by weight of polyvinylidene fluoride (PVDF) and 10-30% by weight of Super-P carbon (SPC).
7. The bilayer current collector (110) as claimed in claim 1, wherein the electrically conductive fluoride-based polymer layer (110A) comprises 70% by weight of polyvinylidene fluoride (PVDF) and 30% by weight of Super-P carbon (SPC).
8. The bilayer current collector (110) as claimed in claim 1, wherein the electrically conductive polyethylene layer (110B) is joined with the fluoride-based polymer layer (110A) at a temperature ranging from 150- 250 degree Celsius to obtain the bilayer current collector (110).
9. The bilayer current collector (110) as claimed in claim 1, wherein the electrically conductive fluoride-based polymer layer (110A) has a thickness ranging from 30-50 micrometers (µm).
10. The bilayer current collector (110) as claimed in claim 1, wherein the bilayer current collector (110) has a thickness ranging from 200-240 µm.
11. The bilayer current collector (110) as claimed in claim 1, wherein the bilayer current collector (110) has a thickness of 220 µm.
12. A Zinc Bromine Static Battery (ZBSB) apparatus (100), comprising:
a first cell (102A) that comprises a first cathode layer (108A), a first anode layer (104A), and a first separator layer (106A) disposed between the first cathode layer (108A) and the first anode layer (104A);
a second cell (102B) that comprises a second cathode layer (108B), a second anode layer (104B), and a second separator layer (106B) disposed between the second cathode layer (108B) and the second anode layer (104B); and
a bilayer current collector (110) sandwiched between the first cathode layer (108A) of the first cell (102A) and the second anode layer (104B) of the second cell (102B),
wherein the bilayer current collector (110) comprises:
an electrically conductive fluoride-based polymer layer (110A) comprising an electrically conductive filler, wherein the electrically conductive fluoride-based polymer layer (110A) is in contact with the first cathode layer (108A); and
an electrically conductive polyethylene layer (110B) devoid of a fluoride group-containing polymer, wherein the electrically conductive polyethylene layer (110B) is in contact with the second anode layer (104B).
13. A method (300) of preparation of a bilayer current collector (110) for a Zinc Bromine Static Battery (ZBSB) apparatus (100), the method comprising:
adding an electrically conductive filler on a substrate made of a fluoride-based polymer to form an electrically conductive fluoride-based polymer layer (110A); and
joining the formed electrically conductive fluoride-based polymer layer (110A) with an electrically conductive polyethylene layer (110B) devoid of a fluoride group-containing polymer to form the bilayer current collector (110) for the ZBSB apparatus (100).
14. The method (300) as claimed in claim 13, wherein the adding of the electrically conductive filler on the substrate made of the fluoride-based polymer to form the electrically conductive fluoride-based polymer layer (110A) comprises mixing 70% by weight of polyvinylidene fluoride (PVDF) and 30% by weight of Super-P carbon (SPC).
15. The method (300) as claimed in claim 13, wherein the joining of the formed electrically conductive fluoride-based polymer layer (110A) with the electrically conductive polyethylene layer (110B) devoid of the fluoride group-containing polymer comprises disposing the formed electrically conductive fluoride-based polymer layer (110A) over the electrically conductive polyethylene layer (110B) and applying a hot rolling operation at a temperature ranging from 150-250 degree Celsius for the joining.