OA19246A - Metal-airfuel cell - Google Patents

Metal-airfuel cell Download PDF

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Publication number
OA19246A
OA19246A OA1201900240 OA19246A OA 19246 A OA19246 A OA 19246A OA 1201900240 OA1201900240 OA 1201900240 OA 19246 A OA19246 A OA 19246A
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OA
OAPI
Prior art keywords
absorbent material
material layer
air
metal
fuel cell
Prior art date
Application number
OA1201900240
Inventor
Mark DANSIE
Original Assignee
Hydra Light International Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hydra Light International Ltd filed Critical Hydra Light International Ltd
Publication of OA19246A publication Critical patent/OA19246A/en

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Abstract

The application relates to a metal-air fuel cell and uses thereof including use as a long-life, mechanically rechargeable, direct current power source for devices and products.

Description

METAL-AIR FUEL CELL
FIELD
The présent invention relates to a metal-air fuel cell and uses thereof including use as a long-life, mechanically rechargeable, direct-current power source for devices and products. BACKGROUND
Despite numerous advances in metal-air fuel cell technology, there remains an ongoing need to overcome certain disadvantages associated with the technology and to provide new sources of direct current power particularly in the form of batteries, for use in devices and products which are affordable, accessible, environmentally friendly (re-usable, recyclable), hâve a long-life (shelf and/or operation), are reliable and safe.
SUMMARY
Unless the context requires otherwise, the word “comprise” and variations thereof such as “comprises” and “comprising”, will be understood to include the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or groups of integers or steps.
According to a first aspect of the invention, there is provided a metal-air fuel cell comprising:
(a) an anode;
(b) a positionable air cathode;
(c) an absorbent material layer configured to retain electrolyte, the absorbent material layer positioned intermediate the anode and the air cathode such that it contacts the anode;and (d) an elastic air cathode positioning means configured to position the air cathode to ensure that the air cathode remains in contact with the absorbent material layer while accommodating any change in volume of the absorbent material layer;
wherein the absorbent material layer functions as an ionic transfer bridge between the anode and the cathode by retaining electrolyte.
Unless the context otherwise requires, “position” means, when used as a verb, to put or arrange something in a new location or shape, and “positioning” and “positionable” are to be construed accordingly
Preferably, the anode, the absorbent material layer and the air cathode are coaxially arranged such that the air cathode substantially surrounds the absorbent material layer and the absorbent material layer substantially surrounds the anode.
Preferably, the elastic air cathode positioning means is positioned around a cross-sectional perimeter of the cell.
Preferably, the metal-air fuel cell is contained within an open housing unit.
Preferably, the absorbent material layer is pre-impregnated with ions to form electrolyte when the absorbent material layer retains water.
Preferably, the anode comprises a magnésium alloy.
Preferably, the air cathode comprises a sheet layer, preferably formed of a hydrophobie, air-permeable layered-Teflon material.
According to a second aspect of the invention, there is provided a method of using a metalair fuel cell according to a first aspect of the invention to provide a direct current power source for use to power the operation of a product or device.
BRIEF DESCRIPTION OF THE FIGURES
The invention is further described with respect to the accompanying figures which illustrate preferred embodiments of a metal-air fuel cell according to the présent invention but are not to be understood as superseding the generality of the preceding description of the invention.
FIGURE 1A shows a metal-air fuel cell according to the invention to illustrate a concentric layered construction (co-axial arrangement) comprising an internai anode rod, intermediate absorbent material layer, paper separator layer and external air cathode layer held or positioned in place by an elastic air cathode positioning means to accommodate expansion (and contraction) of the absorbent material layer upon uptake/absorption of the adsorbed liquid electrolyte and/or collection of anode waste précipitâtes over time.
FIGURE 1B shows a cutaway front view of the fuel cell of Figure 1A to illustrate the concentric layered construction before expansion of the absorbent material layer.
FIGURE 1C shows a cross-sectional cutaway front view of the fuel cell of Figure 1A to illustrate the concentric layered construction after expansion of the absorbent material layer.
FIGURE 2 shows an exploded view of a magnesium-air fuel cell according to an embodiment of the invention to illustrate its various components.
FIGURE 3 shows a cross-sectional cutaway front view of a magnesium-air fuel cell to illustrate the absorbent material layer according to an embodiment of the invention.
DETAILED DESCRIPTION
FIGURE 1A présents a metal-air fuel cell according to an embodiment of the invention which provides a co-axial arrangement of internai anode magnésium rod 19, substantially surrounded by absorbent material layer 20, which is in turn substantially surrounded by a paper separator layer 20A. The paper separator layer 20A is in turn substantially surrounded by air cathode layer 21. Air cathode layer 21 is positioned by an elastic air cathode positioning means 22, such as an elastic O-ring or mesh, to retain contact with the absorbent material layer 20. The metal-air fuel cell is therefore able to accommodate expansion (and contraction) of the absorbent material layer upon uptake (or déplétion) of the liquid electrolyte and/or collection of anode waste précipitâtes over time. In an alternative arrangement, the elastic air cathode positioning means could be incorporated into the air cathode layer such as by weaving elastic material into the air cathode.
A cross-sectional view of the fuel cell of FIGURE 1A is also presented to illustrate the absorbent material layer 20 before expansion (FIGURE 1B) and after expansion (FIGURE 1C). FIGURES 1B and 1C illustrate uptake of liquid electrolyte by the metal-air fuel cell of FIGURE 11. Electrolyte is absorbed by the absorbent material layer 20 via a wicking action when dipped into the electrolyte. As shown in FIGURES 1B and 1C, the air cathode layer (21) remains positioned in contact with the absorbent material layer 20, and paper separator layer 20A, by virtue of the elastic air cathode positioning means 22.
FIGURE 2 shows an exploded view of a métal air fuel cell according to the invention to illustrate some of its various components. Magnésium anode 28, absorbent material layer 29, paper separator layer 29A and air cathode 30 are co-axially arranged such that the air cathode 30 surrounds the paper separator layer 29A, which surrounds the absorbent material layer 29, which in turn surrounds the magnésium anode 28. Elastic air cathode positioning means 27 - formed of O-rings in the présent embodiment - ensure electrolytic contact between the air cathode 30 and the absorbent material layer 29. The co-axial arrangement of électrodes is positioned within a vented housing 32. Vents within the housing 32 allow for gas exchange (including oxygen intake) and venting of the gas byproducts. The vented housing 32 is closed at respective ends by a top lid 25 and a bottom lid 33, each held in place by a screw 24 secured to the anode 28. A contact ring 23 situated outside the top lid 25 provides a terminal from air cathode 30 and is connected to air cathode 30 by contact tab 31. Rubber or plastic O-rings 27A and plastic washers 26 seal each end of the electrode arrangement and any electrolyte retained therein from other components to protect against corrosion.
As demonstrated by FIGURE 2, components of the metal-air fuel cell may be easily replaced by unscrewing one of the screws 24 holding either the top lid 25 or the bottom lid 33 in place to access the arrangement of électrodes. The magnésium anode 28 and air cathode 30 may therefore easily be replaced, providing an energy source that can be mechanically-recharged in a simple manner.
FIGURE 3 shows a cutaway view of a metal-air fuel cell of the invention to illustrate a preferred embodiment of the absorbent material layer. The metal-air fuel cell comprises in sequence moving inward from the outer circumference: air cathode positioning means 35, air cathode 34, paper separator layer 36 to support and contain the absorbent material layer, and further isolate and protect the cathode from anode waste précipitâtes, pre3 impregnated sub-layer 37 of the absorbent material layer (being pre-impregnated with ions), non-impregnated sub-layer 38 of the absorbent material layer (being not preimpregnated with ions), and anode 39.
While anode 19 is described as a magnésium anode, alternative metals, alloys or combinations of alloys to provide suitable anodes will generally be known to those skilled in the art. Suitable alternative metals include Li, Ca, Al, Zn and Fe. Preferably, the anode comprises a magnésium alloy such as “AZ31B” having the following composition (%): Al: 2.5 - 3.5, Cu: 0.05 - max; Fe: 0.005 - max; Mg: balance; Mn: 0.2 min; Ni: 0.005 - max; Si: 0.1-max; Zn: 0.6 -1.4.
The anode 19 may be adapted to be internally, preferably centrally, located within the metal-airfuel cell, and may therefore generally be formed in the shape of a rod or a cylinder formed by example by extrusion. If, for example, the metal-air fuel cell is alternatively configured in a sandwich-layered (i.e. laminate) arrangement, the anode, the absorbent material layer and the air cathode may each be provided as a substantially fiat layer.
Air cathodes 21 that may be suitable for use in the metal-air fuel cell of the invention will generally be known to those skilled in the art. Suitable properties of the air cathode 21 include hydrophobicity and air-permeability. Preferably the air cathode 21 is in the form of a sheet layer adapted to accommodate the change in volume of the absorbent material layer 20 upon expansion and contraction. Preferably the air cathode 21 is hydrophobie and air-permeable and comprises a layered Teflon material. Still more preferably the air cathode 21 may comprise a layered Teflon material, carbon and nickel plated wire.
The absorbent material layer 21 acts as the ionic bridging System required for operation of the cell and may be made from an absorbent material that is able to absorb and hold or retain electrolyte by a process of wicking, drawing, capillary action, or similar. The absorbent material may be selected based on its possessing one or more of, preferably ail of the following properties: wicking and electrolyte retaining ability; ability to expand to accommodate an increase in volume; ability to encapsulate solid particles so as to capture and/or retain the solid waste; ability to function as an “ionic bridge”; and/or ability to allow for exchange or diffusion of gases (i.e. for oxygen gas diffusion process and release of gas by-products during operation of the cell). Advantageously, anode waste précipitâtes may be captured within the absorbent material layer 21 and are thereby prevented from making direct contact with the air cathode 21.
The absorbent material layer 20 may be made from a combination of air-permeable water absorbing, hydrophilic and/or hydrophobie materials and be conductive or non-conductive. Suitable materials include woven or non-woven materials or combinations thereof produced from microfiber, rayon, cotton, cotton wool, hemp, wool, hessian, natural fiberwood pulp, aerogel composites, bamboo fibre pulp and/or any suitable combination thereof. Preferably the absorbent material layer comprises fibrous cellulose, bamboo fibre pulp or a combination thereof. The performance of the absorbent material layer 20 may be enhanced with additives such as, for example, the addition of sphagnum and polyacrylate as well as other super absorbent gels derived from petroleum which will be familiar to those in the art.
The cell may be activated or re-activated for use when the absorbent material layer comprises an absorbed amount of electrolyte. The absorbent material layer 20 may comprise an absorbed amount of electrolyte following absorption of an electrolyte or water (when the absorbent material layer is pre-impregnated with ions). The types of electrolyte that may be suitable for use in the metal-air fuel cell of the invention will be generally known to those in the art. Suitable examples may include but are not limited to an aqueous solution comprising ions such as NaCI (e.g. sait water, sea water and saline solutions), electrolytes (e.g. sports drinks), urine and alkaline solutions (e.g. KOH) and water (e.g. when the absorbent material is pre-impregnated with ions).
As suggested by the drawings and preceding description, the metal-air fuel cell of the invention advantageously allows for expansion and contraction of the absorbent material layer upon absorption/release of electrolyte and/or capture of anode waste material. Further, potential advantages of the invention may include:
• an affordable, low-cost power source for use in the developing world;
• the metal-air fuel cell may be simply and conveniently activated and re-activated on demand by dipping the absorbent material into electrolyte, and deactivated by being allowed to dry out between uses. This provides a metal-air fuel cell with a “dormant” mode in which components are not consumed, and the associated potential for a long shelf-life without any appréciable or significant loss in performance power of the cell;
• by providing a novel wicking and rétention system for the electrolyte, the invention that may allow for configurations avoiding bulky water vessels and requiring less electrolyte, thereby reducing the weight of the cell while eliminating the potential for electrolyte leakage caused by, for example, tipping the fuel-cell from an upright position;
• by providing the metal-air fuel cell in an open housing unit, the invention may overcome disadvantages présent in closed metal-air fuel cell Systems, such as gas pressure build up and effective sealing of electrolyte, while also improving oxygen intake and venting of by-products;
• convenient replacement and recycling of components. The anode, the absorbent material layer, and the air cathode may be simply and conveniently replaced and recycled to provide an environmentally-friendly mechanically rechargeable device;
and/or • the novel wicking and rétention System for the electrolyte may allow for increased thermal control to prevent a runaway exothermic reaction. Metal-air fuel cells work by creating an exothermic redox reaction between the anode and the cathode. In traditional metal-air fuel cells this créâtes the potential for runaway exothermic reactions, in which pressure and heat within the cell may rise to dangerous levels. The absorbent material layer of the invention allows for improved évaporation and venting of electrolyte as températures increase within the cell. This may in turn control runaway reactions by reducing available electrolyte through évaporation, thereby slowing the reaction.
The metal-air fuel cells of the présent application are, depending on their size, considered to potentially provide a power source équivalent to the use of 90-100 traditional AA batteries. Based on the results of the experiments and observations, it was considered that, the unique design, engineering and operation of metal-air fuel cells according to the invention allows for filtering and/or capturing anode waste précipitâtes within the absorbent material, which in turn:
• protects pores found within the air-cathode from blockage by waste particulates, in turn allowing for critical oxygen gas diffusion across the air cathode;
• effectively prevent the waste précipitâtes otherwise degrading the air-cathode; through sait ingress or corrosion (e.g. sait migration due to “sait creep” i.e. sait crystal migration resulting in sait ingress and/or corrosion), potentially also improving the life of the cathode and other cell components such as contacts, wiring and/or electronics;
• render regular internai cleaning of the cell to remove accumulated waste unnecessary; and/or • may actually enhance the performance of the cell as the waste précipitâtes collect or are captured within the absorbent material.
Modifications and variations as would be deemed obvious to the person skilled in the art are included within the ambit of the présent invention as claimed in the appended daims.

Claims (8)

1. A metal-air fuel cell comprising:
(a) an anode;
(b) a positionable air cathode;
(c) an absorbent material layer configured to retain electrolyte, the absorbent material layer positioned intermediate the anode and the air cathode such that it contacts the anode; and (d) an elastic air cathode positioning means configured to position the air cathode to ensure that the air cathode remains in contact with the absorbent material layer while accommodating any change in volume of the absorbent material layer;
wherein the absorbent material layer functions as an ionic transfer bridge between the anode and the cathode by retaining electrolyte.
2. The metal-air fuel cell according to claim 1, wherein the anode, the absorbent material layer and the air cathode are coaxially arranged such that the air cathode substantially surrounds the absorbent material layer and the absorbent material layer substantially surrounds the anode.
3. The metal-air fuel cell according to either of daims 1 or 2, wherein the elastic air cathode positioning means is positioned around a cross-sectional perimeter of the cell.
4. The metal-air fuel cell according to any one of daims 1 to 3, wherein the metal-air fuel cell is contained within an open housing unit.
5. The metal-air fuel cell according to any one of daims 1 to 4, wherein the absorbent material layer is pre-impregnated with ions to form electrolyte when the absorbent material layer retains water.
6. The metal-air fuel cell according to any one of daims 1 to 5, wherein the anode comprises a magnésium alloy.
7. The metal-air fuel cell according to any one of daims 6, wherein the air cathode comprises a sheet layer, preferably formed of a hydrophobie, air-permeable layered-OTeflon material.
8. The metal-air fuel cell according to any one of daims 1 to 7, when used to provide a direct current power source for use to power the operation of a product or device.
OA1201900240 2016-12-22 2017-12-07 Metal-airfuel cell OA19246A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AU2016905322 2016-12-22
SN62/456,910 2017-02-09

Publications (1)

Publication Number Publication Date
OA19246A true OA19246A (en) 2020-04-24

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