WO2001033658A2

WO2001033658A2 - Metal-air battery

Info

Publication number: WO2001033658A2
Application number: PCT/CA2000/001261
Authority: WO
Inventors: Alexander M. Iarochenko; Evgeny B. Kulakov; Oleg I. Krakhin; Stanislavs D. Seruk
Original assignee: Eontech Group Inc.
Priority date: 1999-10-29
Filing date: 2000-10-26
Publication date: 2001-05-10
Also published as: WO2001033658A3; AU1014401A

Abstract

An improved metal anode-oxygen diffusion cathode battery having an anode; an oxygen diffusion cathode; an aqueous electrolyte containing metal cations selected from the group consisting of alkali metal cations and alkaline earth cations; the improvement wherein said electrolyte comprises an additive selected from the group consisting of (a) metal cations of Pb, Sn, Ga and In at a cumulative concentration of 0.001 to 1 M; provided that when Pb, Ga and In is absent the concentration of Sn is greater than 0.2M; and provided that in the presence of both of Mg and Sn together, the concentration of In is greater than 0.2M; (b) an organic additive selected from the group consisting of 1-15 % W/W of a D-glucose polysaccharide, 0.5 - 5 % W/W of a polyester, 0.5 % of an aliphatic alcohol selected from ethyl alcohol and propyl alcohol, and mixtures thereof; and (c) a halide anion selected from the group consisting of F?-, Cl-, Br-, I-¿ and mixtures thereof.

Description

METAL - AIR BATTERY

FIELD OF THE INVENTION The invention relates to the area of metal-air batteries and fuel cells, particularly, aluminum-air batteries suitable for electronic devices, including radio-telephones, portable audio and video players, video cameras, and personal computers.

BACKGROUND OF THE INVENTION

There are known metal-air batteries and fuel cells, which contain a series of basic components including a cathode, an anode, and an electrolyte. There are known electrical rechargeable batteries comprising a housing with a pack of solid state cells, with a converter (controller) for stabilization of the output operating voltage when during the discharge cycle the voltage deeps almost to one-half. In U.S. Pat. No. 5,656,876, a battery pack of lithium or Nl-Cd solid-state cells is shown, where a DC/DC converter provides a stable operating voltage, possibly also different voltages upon request. U.S. Pat. No. 5,286,578 shows a flexible electrochemical cell having an air cathode, a metallic anode and an electrolyte chamber. The electrolyte chamber is collapsed when the battery is shipped (without electrolyte) to save space. U.S. Pat. No. 5,554,918 shows a mechanically rechargeable battery of a cylindrical shape having a replaceable zinc anode, an air electrode (one option) and housing. A non-spillable electrolyte is contained in the housing. When necessary, the anode can be removed and replaced with a new anode. The energy density of these cells is up to 100 to 180 Wh/L. Further related battery art is found in U.S. Patent Nos.

3,798,527; 3,876,471; 3,801,376 ; 3,876,471; 3,915,745; 4,091,174; 4,477.539; 4,871,627; 4,925,744; 4,950,560; 4,950,561; 5,004,654; 5,049,457; 5,024,904; 5,032,474; 5,415,949; 5,424,147; 5,525,895; 5,318,861, 5,569,551 and 6,060,196.

There is, however, a need for a metal-air battery and fuel cells having improved power characteristics. SUMMARY OF THE INVENTION

It is an object of the present invention to provide batteries and fuel cells having reduced anode corrosion when stored and improved electrical characteristics. Accordingly, the invention provides in one aspect an improved metal-oxygen battery having an anode; an oxygen diffusion cathode; an aqueous electrolyte containing metal cations selected from the group consisting of alkali metal cations and alkaline earth cations; the improvement comprising said electrolyte consisting of (a) metal cations of Pb, Sn, Ga and In at a cumulative concentration of 0.001 to 1 M; provided that when Pb, Ga and In is absent the concentration of Sn is greater than >0.2M; and provided that in the presence of both of Mg and Sn, the concentration of In is greater than 0.2M; (b) an organic additive selected from the group consisting of 1-15% W/W of a D-glucose polysaccharide, 0.5 - 5% W W of a polyester, 0.5% of an aliphatic alcohol selected from ethyl alcohol and propyl alcohol and mixtures thereof: and (c) a halide anion selected from the group consisting of F^", Cl^", Br^", I^" and mixtures thereof.

The electrolytes of use in the practise of the invention provide a decrease in anode corrosion during discharge, an increase in electric capacity and electrical conductivity of the electrolyte, a decrease of freezing temperature of the electrolyte, transforming the products of the chemical reaction into microcrystalline and dissolved form and stabilization of the composite electrolyte during storage.

The electrolyte preferably comprises 1% to 30% W/W of KOH up to about 0.1 mol/L of Sn, up to about 0.1 mol/L of Pb, up to about 0.1 mol/L of Ga, up to about 0.1 mol/L of In, up to about 10% by mass of starch, up to 5% by mass of ethyl alcohol, and up to about 20% by mass of NaCl.

The electrolyte more preferably comprises 20% of KOH, 0.06 mol L of Sn, 0.02 mol/L of Pb, 0.01% mol/L of Ga, 0.02 mol/L of In, 5% by mass of starch, 2% by mass of alcohols, and 15% by mass of NaCl.

The electrolyte alternatively comprises 0.02 mol/L of Pb, 0.06 mol/L of Sn, 0.01 mol/L of Ga, 0.02 mol/L of In, 5% by mass of starch, 2% by mass of ethyl alcohols, 2% by mass of polyester, and 15% by mass of NaCl. Advantageously, the cathode includes additives selected from the group consisting of lead oxides and silver-indium alloys, to provide stabilization of properties during extended storage of the positive electrode and increase in electrochemical activity while the battery is in use. At least one of the additives is advantageously incorporated into the cathode comprising less than about 200 mg/cm³ of a total surface area of cathode.

In a preferred aspect, the invention provides an improved metal anode-oxygen diffusion cathode battery having an anode; an oxygen diffusion cathode; an aqueous electrolyte containing metal cations selected from the group consisting of alkali metal cations and alkaline earth cations; the improvement wherein said anode comprises a metal selected from the group consisting of aluminium, zinc, magnesium, and alloys thereof and further comprising (i) at least 0.02 W/W % Fe and

(ii) a metal selected from the group consisting of Ga, In, Th, Sn, Pb, Mn and mixtures thereof, at a cumulative concentration of 0.01 - 5 W/W %; provided that if

Fe is at a concentration of less than 0.15% W/W Mn may only be present at a concentration greater than 0.3 W/W %; and Ga may only be present at a concentration greater than 0.07 W/W %.

The anode, preferably, comprises 0.02 - 0.05 W/W % Fe, 0.4 - 0.6W/W % Sn and 0.4 - 0.7W/W % In, and the balance is aluminum.

Thus, we have found that in one aspect of the invention relatively high concentration of Fe, preferably, 0.05-0.15%) w/w, in the anode reduce the rate of corrosion, when the battery is stored.

The effective amount of additives improve the electrochemical characteristics of the anode, reduce corrosion and preserve the anode during storage.

Preferably, the battery is as defined hereinabove wherein said electrolyte comprises a metal cation of Pb, Sn, Ga and In at a cumulative concentration of 0.001 to 1M. Preferably, the battery is as defined hereinabove wherein said anode additives are present in the following concentrations: Ga 0.01 % by mass, In 0.5 % by mass, Tl 0.015 % by mass, Sn 0.15 % by mass, Cd 0.01 % by mass, Pb 0.02 % by mass, Mn 0.03 % by mass and Fe 0.05% by mass. Preferably, the battery is as hereinabove defined wherein the thickness of said anode is in the range of 0.05 mm to 10 mm, and a volume of said electrolyte is selected to achieve balanced and synchroneous consumption of both electrolyte and anode during the discharge of said battery.

The battery or fuel cell particularly comprise a body, a cathode and a replaceable unit (cartridge) that, in turn, comprises an anode and electrolyte wherein recharging is by mechanical replacement of the cartridge to assure a self-contained source of current.

Accordingly, the battery comprises at least one non-consumable gas-diffusion cathode; at least one consumable anode; an aqueous electrolyte containing metal ions; a housing enclosing said electrolyte, said at least one cathode and said at least one anode; a first unit comprising said housing and said at least one cathode; a second unit comprising said at least one anode and said electrolyte wherein said electrolyte is contained within an electrolyte impermeable container, said second unit is adapted to be replaceably received in sealing engagement within said first unit, and puncture means to effect puncture of said electrolyte impermeable container and allow said electrolyte to make contact between said at least one anode and said at least one cathode when said second unit is received within said first unit.

The battery further advantageously comprises at least one first conduit for connecting to and distributing ambient air, at least one second conduit for distributing the electrolyte, and at least one third conduit for collecting reaction products in cooperation with the at least one first conduit and the at least one second conduit.

The puncture element advantageously comprises a substantially U-shaped element having sharp ends, the puncture element being arranged inside the electrolyte impermeable container, and the battery further comprises a biasing means for pressing the electrolyte impermeable container against the sharp ends, to cause the electrolyte impermeable container to break.

The puncturing means preferably comprises a thread, which is attached to the electrolyte impermeable container. The puncturing means alternatively comprises a push bar having a foot end, which contacts the electrolyte impermeable container.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be more clearly understood, the preferred embodiment thereof will now be described in detail by way of example, with reference to the accompanying drawings, in which:

Fig. 1 is a schematic representation of a metal-air battery according to the prior art; Fig. 2A is a schematic side view of a gas-diffusion cathode assembly according to a first embodiment of the invention;

Fig. 2B is a schematic side view of an anode/electrolyte assembly according to a first embodiment of the invention;

Fig. 3 is a graph showing the relative anode potential HqO as a function of the mount of an additive D_a in the anode composition;

Fig. 4 is a graph showing the relative anode potential as a function of the current density J and amount of additive D_a in the anode composition;

Fig. 5 is a graph showing the load density Q as a function of the amount of additive

D_a in the anode composition; Fig. 6 is a graph showing the density of the corrosion current of the anode as a function of the amount of additive B_e in the electrolyte composition;

Fig. 7 is a schematic side view of a hermetic seal according to a second embodiment of the invention; Fig. 8 is a corrosion diagram of an aluminium anode in the alkali electrolyte;

Fig. 9 is a graph showing the battery voltage-ampere characteristics for different types of cathode compositions;

Fig. 10 is a graph showing the battery voltage-ampere characteristics for different types of anode compositions;

Fig. 11 is a graph showing the battery discharge characteristics for different types of anode compositions;

Fig. 12 is a graph showing the battery energy as a function of the discharge current density for different types of anode compositions;

FFiigg.. 1133 is a graph showing the battery volt-ampere characteristics for different types of electrolyte compositions;

Fig. 14 is a graph showing the battery energy as a function of the current density for different types of electrolyte compositions;

Fig. 15 is a graph showing the battery energy as a function of the current characteristics for two embodiments of the invention;Fig. 16 is a graph showing discharge characteristics of a battery according to the invention;

Fig. 17 is a graph showing the current density and power output of a battery according to the invention;

Fig. 18A is a schematic side view of an anode/electrolyte assembly according to a third embodiment of the invention, showing the width of the assembly;

Fig. 18B is a schematic side view of an anode/electrolyte assembly according to a further embodiment of the invention, showing the thickness of the assembly;

Fig. 19A is a schematic side view of an anode/electrolyte assembly according to a further embodiment of the invention, showing the width of the assembly; Fig. 19B is a schematic side view of an anode/electrolyte assembly according to a further embodiment of the invention, showing the thickness of the assembly;

Fig. 19C is a schematic top view of an anode/electrolyte assembly according to a further embodiment of the invention; Fig. 20A is a schematic side view of an anode/electrolyte assembly according to a further embodiment of the invention, showing the width of the assembly;

Fig. 20B is a schematic side view of an anode/electrolyte assembly according to a further embodiment of the invention, showing the thickness of the assembly;Fig. 21 is a schematic side view of an electrolyte bag depressing assembly according to a Fig. 20A;

Fig. 22A is a schematic side view of a battery according to Fig. 20A, showing a starting position of the electrolyte bag in a sequence of compression; Fig. 22B is a schematic side view of a battery according to Fig. 20A, showing a first intermediate position of the electrolyte bag in a sequence of compression;

Fig. 22C is a schematic side view of a battery according to Fig.20A, showing a second intermediate position of the electrolyte bag in a sequence of compression;

Fig. 22D is a schematic side view of a battery according to Fig. 20A, showing a third intermediate position of the electrolyte bag in a sequence of compression;

Fig. 22E is a schematic side view of a battery according to Fig. 20A, showing an end position of the electrolyte bag in a sequence of compression;

Fig. 23 is a schematic perspective view of a replaceable cartridge according to an embodiment of the invention; Fig. 24A is a schematic side view of a replaceable cartridge according to Fig. 23, showing the thickness of the cartridge;

Fig. 24B is a schematic side view of a replaceable cartridge according to Fig. 23, showing the width of the cartridge and the electrolyte bags in an initial state;

Fig. 24C is a schematic side view of a replaceable cartridge according to Fig. 23, showing the width of the cartridge and one electrolyte bag in its fully emptied state;

Fig. 25A is a schematic side view of a replaceable cartridge battery according to the invention, showing the width of the cartridge; Fig. 25B is a schematic side view of a replaceable cartridge battery according to the invention, showing the thickness of the cartridge;

Fig. 26A is a schematic side view of a replaceable cartridge battery according to the invention, showing the width of the cartridge, Fig. 26B is a schematic side view of a replaceable cartridge battery according to the invention, showing the thickness of the cartridge; and

Fig. 27 is a diagram showing the discharge characteristics of a battery according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The basic electrochemical process of an air-metal current source can be demonstrated using the aluminum-air battery i.e. fuel cell as an example.

Aqueous solutions of alkali and salts are utilized as electrolytes in aluminum-air current sources. The following electrochemical reactions occur in the alkali solutions:

Anode dissipation of aluminum at the anode (negative electrode) according to equations (1) and/or (2):

A1 + 4OH^" → AlO₂ ^" + 2H₂O + 3e (1) or

Al + 4OH^" → Al (OHy + 3e (2)

The cathode recovery of the oxygen at the positive electrode (gas- diffusion cathode) according to equation (3):

0₂ + 2H₂O + 4e o 4OH^" (3)

Inasmuch as aluminum is thermodynamically unstable in water, the electrochemical corrosion takes place at the anode that is denoted by the same equations (1) and (2) and the conjugate process is the cathodic recovery of hydrogen from water at the cathode:

H₂ + 2OH^" o2H₂O + 2e (4)

Summing up the current generation and the corrosion reaction is described by respective equations (5) and (6) below:

4A1 + 3O + 6H₂O + 4NaOH → 4NaAl(OH)₄ (current generation) (5) 2Al + 6H₂0 + 2NaOH → 2NaAl(OH)₄ + 3H₂ t (corrosion) (6)

The solubility of the reaction product is limited, therefore, when the solubility limit is reached, decomposition process of the solution begins according to reaction (7):

NaAl(OH)₄ → NaOH + Al(OH)₃ (7)

As a result of which the final reaction product is formed: e.g crystalline aluminum hydroxide. This simplified scheme can be represented as a summation of equations for the current formation process: 4Al + 3O₂ + 6H₂O- 4Al(OH)₃ (8) and for the corrosion reaction:

2A1 + 6H₂O-*2Al(OH)₃ + 3H₂ T (9)

Fig. 1 presents reactions, which are shown at their place of origin in the aluminum-air battery.

Although the reaction mechanism in neutral salt electrolytes differs from reaction mechanism in an alkali solution, the summarising processes are adequately represented by equations (8) and (9). A battery 100 comprises a housing 1, an anode (negative electrode) 12 and a cathode (positive electrode) 2. A load 60 is connected to the anode and the cathode during use of the battery. Oxygen (or air) has access to the cathode via an oxygen inlet 20 and an oxygen outlet 30. An electrolyte chamber is located within the housing, so that ions of an electrolyte 16 may flow freely between the two electrodes. Often, the electrolyte may be added to the housing via an electrolyte inlet 40 and removed from the housing via an electrolyte outlet 50. The electrolyte inlet and outlet may be one and the same, i.e. only one opening in the housing. A first embodiment of the invention is shown in Figs. 2A and 2B. The air-metal power source has a body 1 containing a cathode 2 and a replaceable unit (cartridge) 200, containing anode 12 and electrolyte 16. Thus, power supply recharging is accomplished with mechanical recharging (by replacing the cartridge) thereby assuring a self-contained power source. Figs. 2A and 2B thus illustrate a basic embodiment of the proposed mechanically rechargeable air-metal battery, containing one anode and two cathodes. The battery consists of two main parts, a cathode unit (Fig.2A) and the replacement cartridge (Fig. 2B). The battery includes one body 1, two gas-diffusion cathodes 2, and a voltage regulator 3, which may optionally include a stabilizer, a support 4 for a hermetic seal, and a sealing ring or gasket 5. The gas- diffusion cathode preferably has a current conducting mesh 6 serving as a current collector, a gas impermeable layer 7, and a gas permeable layer 8. The body of the battery contains special grooves 9 for holding the cartridge and guides 10 for maintaining alignment of the components during assembly and mechanically reinforcing the battery body. During the corrosion of the anode, hydrogen gas is exiting to the atmosphere through the porous cathode.

The cartridge has a cover 11, an anode 12, a water impermeable membrane 13, valves 14, a brush for cleaning the cathodes 15, and an electrolyte 16. When using a dense electrolyte, the cartridge may include an additional cavity 17 for water. The cover has flexible elements 18 for sealing and attaching the cartridge to the body of the battery. When charging the battery, the cartridge is inserted through the opening to the support, whereupon the fixture 18 guides the cartridge along the grooves 9 and guides 10 and onto the sealing supports 4, thereby opening valves 14 to release the electrolyte and activate the battery of the cartridge. After this process the battery is ready for use (Fig. 2B). During connection to the power source, battery starts to produce electric current, based on the scheme on Fig. 1 and equations (1) to (9). The fixture 18 also includes sealing elements that form a liquid-tight seal with the body of the battery (Fig. 2A) to contain the electrolyte solution. After the cartridge and battery body have been properly engaged, when the battery is activated electrical current is produced according to the electrochemical reaction sequence previously outlined in equations (1) to (9).

Moreover, the battery body unit and cartridge are isolated from each other during the inactive mode, while for activation of the source it is necessary to mechanically place the cartridge into the battery body. The expended materials (anode and electrolyte) and reaction products formed from the use of the source are extracted during the mechanical removal of the cartridge from the battery body unit.

As the used-up cartridge is removed from the battery body in preparation for recharging the battery by inserting a new cartridge, the valves 14 are released and again seal the cartridge to contain the used-up electrolyte. Also, as the used-up cartridge is removed, and as the replacement cartridge is inserted, the built-in brushes 15 clean deposits that may have formed on the cathodes.

The consumable materials, which are used in the current source according to the present invention, are ecologically clean during the production of electric current, through its use, and through its disposition through either recycling or disposal. Based on the Bayra process (regeneration to produce the anode metal), metal oxide hydrate, for instance aluminum, serves as an initial source to produce the anode material. Furthermore, the used-up electrolyte and the aluminum oxide hydrate can be used for recycling.

The optimum sizes are selected so that the thickness of the anode is between 0.04 to 0.5 of the spacing between the cathode and anode (T_K) of the volume of an active part of the cartridge, V, (not considering the cartridge cover 11, Fig. 2B) and are expressed with the following mathematical expressions: V = V_e+V_a;

V_e = q_eQkP i;

V_a = (qax + qakor) QkPtt.

Where V_e = is the volume of the electrolyte capacity, cm³ V_ezh = volume of the liquid electrolyte composition, cm

V_ez = volume of the dense electrolyte composition, cm q_e = specific consumption of water from the electrolyte, cm³/A-hr; Q_k= energy capacity (electrical capacity) active part of the cartridge, A-hr; Pki = (0.35-1.8) - construction parameter V_a = volume of used-up anode material cm³ ; qax = specific expenditure of abode material for the electrochemical reaction cm³/A hr; qakor ⁼ specific expenditure of anode material during corrosion cm³/A hr; pa = (1.3-2.0) - second construction parameter;

Ratios between the clearance dimensions of the cartridge length (L_k) width (T_k) and height (H ) is within the range of l:(0.17-0.35):(1.7-4).

In order to attain the required volt-ampere characteristics, the battery can contain 1,2 □ N (N is any positive integer) of cathodes and N+l or N-1 of anodes connected to each other in series, in parallel, or combinations thereof.

The consumable metallic anode, preferably aluminum or aluminum alloy anode, inside the cartridge, is located inside the cathode assembly between gas- diffusion electrodes (cathodes) at a specified distance for placement of electrolyte, during use of the battery. The electrolyte and anode used are ecologically safe when decomposed, allowing the chemical reaction products to be discarded or, preferably, recycled to extract the anode metal. Fig. 16 shows that the cartridge does not have a negative effect on the electrical characteristics of the battery. The curves without separator and with separator are essentially identical, the separator being part of the cartridge. In Figs. 18A and 18B, an embodiment of an anode 12' is shown. The anode comprises a metal plate 19, which has an elongated negative terminal 20 at one end. The negative terminal has a holder 21 fastened to the negative terminal by a fastening means 22. The holder fastens a first sealing means 23 to the anode 12', which first sealing means seals the passage between the anode and the battery housing (not shown) when the anode is inserted into the battery housing. The holder 21 further clamps an anode membrane 24 to the anode, so that the metal plate 19 is covered by the anode membrane. The anode membrane is made of a material which is electrically conducting, ion permeable but impermeable to the products of the chemical reactions taking place in the electrolyte on the anode plate surface. A preferred material is polypropylene. Thus, any products from the anode reactions will be kept inside the anode membrane.

Figs. 19A to 19C show a battery body 1 having two cathodes 2, and two tightening straps 36. The cathodes are preferably glued to the body, using a hermetically sealing glue, and are further fixed by the straps. The straps are preferably covered with a hermetically sealing agent. The straps are advantageously held to the body with holding screws (not shown). A jumper 38 electrically connects the two cathodes. The jumper is preferably soldered to the current carrier of the cathodes. A free end of the jumper serves as the positive current output. The anode 2 has a free end serving as the negative current output. A second sealing means 30 is arranged between the anode assembly (the cartridge 200) and the battery body 1, to create a hermetic seal between them when necessary. A fourth sealing means 37 is arranged to further seal around the anode free end. Sealing is accomplished when the cartridge cover 11 is tightened to the battery body using a set screw 31 and a vantage screw 39. The vantage screw has an opening for removing hydrogen from the inner cavity 35, the opening having a liquid impermeable separation membrane 41 preventing any electrolyte from escaping via the vantage screw. The hydrogen is formed by the electrochemical reaction of aluminium corrosion at the anode.

In Figs. 20A, 20B and 21, a further embodiment of a system for activation of the cartridge, after insertion into the cathode assembly, is shown. This embodiment has a two-part cartridge cover comprising an upper cover 11a and a lower cover lib. The upper cover is fitted to the lower cover by a set screw 31, which engages threads in the lower cover and pushes the upper cover towards the lower cover via pressure from the screw head. Between the two covers is a second sealing means 30, which is expanded when the covers are fitted together, to provide a hermetic seal between the two covers and the battery housing 1. Further, the upper cover 11a has a first push hole 33 and the lower cover lib has a second push hole 34 for slidingly accommodating a push bar 26. The push bar has a foot end 27, which is larger than the diameter of the push bar, to compress a bag 24 filled with electrolyte when the push-bar "pedestal-type" end is moving away from the upper cover and the lower cover. The electrolyte bag 24 is preferably contained in a U-shaped anode 12 held at the lower cover lib. Inside the electrolyte bag is a puncture element 25, preferably a U-shaped flat piece having sharp points at its ends and running substantially the whole length of an inner cavity 35 of the battery housing. As the foot end 27 of the push bar 26 is pressed onto the electrolyte bag 24, the points of the puncture element 25 will make holes in the bag, thereby allowing electrolyte to flow into the internal space of the battery housing 1 and make contact with both the anode 12 and the cathode (not shown). Preferably, an extension rod 28 is arranged at the end of the push bar 26 which is opposite the foot end 27, to make it possible to press the pedestal-type end of the push bar all the way down in order to empty the electrolyte bag. When the cartridge is in its storage state, the push-bar pedestal end is in a position adjacent the lower cover lib. The end of the push bar 26 which is opposite the pedestal-type end 27 protrudes out from the upper cover 11a in the storage state. A third elastic hermetic sealing means 32 is arranged between the pedestal-type end 27 and the electrolyte bag 24 and held to the lower cover lib by a fixture means 29, such as a metal neck. The third elastic hermetic sealing means prevents electrolyte from leaking out from the battery housing 1 via the first push hole 33 and the second push hole 34.

In Figs. 22A to 22E is shown the sequence of emptying the electrolyte bag 24 inside the inner chamber 35 of the battery housing 1. The battery housing (cathode assembly) is located in a vertical position. Then, the cartridge 200 is fully inserted into the housing, until the lower cover lib is seated against the battery housing (Fig. 22A). The extension rod 28 is attached to the push bar 26, and the push bar is pressed down into the cartridge (Fig. 22B) until the extension bar 28 has almost reached the top of the upper cover 11a. Thus, when the push bar 26 is pressed into the cartridge, the electrolyte bag is compressed and initially punctured, allowing electrolyte to flow out from the bag. The bag is pressed into an (accordion bellows-like??) shape, whilst the third elastic hermetic sealing means 32 is expanded into the inner cavity 35. The set screw 31 is tighten until it cannot be turned further, making the second sealing means 30 seal the gap between the battery housing and the cartridge (Fig. 22C). After this, the battery can be held in any position, without any risk of electrolyte leaking out. The push bar 26 is pressed further down until the foot end 27 stops against the crumpled up, empty electrolyte bag 24 (Fig. 22D). During this stage, the third elastic hermetic sealing means 32, together with the push rod 26, creates an over-pressure in the inner chamber 35, by displacing all existing air from inside the inner cavity. This eliminates any decrease in the level of electrolyte inside the inner cavity. The used-up battery is shown in Fig. 22E, where the electrolyte volume has decreased as the anode material is being used- up. The cartridge should now be replaced by unscrewing the set screw 31 until the second sealing means 30 no longer seals the gap between the battery housing and the cartridge.

Figs. 23 to 24C show a replaceable cartridge 200 according to a further embodiment of the invention. The anode 2 has a negative terminal 20 at one end. On each side of the anode is a bag 24 of electrolyte arranged. There are two bags, one on each side of the anode. A cartridge cover 11 is holding the negative terminal of the anode, and a second sealing means 30 provides a hermetic seal between the cartridge and the battery body (not shown), when the cartridge is inserted into the battery body. An activation thread 42 is arranged through thread holes 43 in the cover 11. Fifth sealing means 45 are arranged in the thread holes 43, to prevent any electrolyte from leaking out via the thread holes. The activation thread preferably forms a loop outside the cover, and runs through the thread holes into the electrolyte bag compartment of the cartridge, formed by a first protective liquid permeable membrane 44 over both electrolyte bags and the anode. The ends of the activation thread 42 are attached to bottom ends of the electrolyte bags, i.e. the end that is further away from the cartridge cover 11. Thus, when a battery operator pulls on the loop of the activation thread 42, the bottom of each electrolyte bag 24 is pulled towards the cartridge cover and against electrolyte bag puncture elements 25 arranged inside the electrolyte bags. The bags are punctured and electrolyte will flow from the bags out into the inner cavity (not shown) of a battery housing and through both the first liquid membrane 44 and a second liquid permeable membrane 46 arranged around the anode 2. This operation should only be performed when the cartridge is sealingly seated in a battery housing (cathode assembly). The second liquid permeable membrane 46 will not let any reaction products from the anode reaction through, thereby effectively containing these by-products until the cartridge is replaced with a fresh one.

Figs. 25A and 25B show yet a further embodiment of a battery according to the invention. A battery body 1 has two cathodes 2, and a cartridge 200. The cartridge has a cover 11 with a sealing means arranged around a negative terminal end 20 of an anode 12. The cathodes are preferably screwed to the body, using a hermetically sealing agent to seal any leaks in the screw holes. A jumper 38 electrically connects the two cathodes. The jumper is preferably soldered to the current carrier of the cathodes. A free end of the jumper serves as the positive current output. The anode 12 has a free end serving as the negative current output (negative terminal) 20. A second sealing means 30 is arranged between the anode assembly (the cartridge 200) and the battery body 1, to create a hermetic seal between them when necessary. A fourth sealing means 37 is arranged to further seal around the anode free end. Sealing is accomplished when the cartridge cover

11, together with the anode 12, is fully pressed into the inner cavity 35 of the battery body 1, via the second sealing means 30. Figs. 26A and 26B show still a further embodiment of a battery according to the invention. A battery body 1 has two cathodes 2, and a cartridge 200. The cartridge has a cover 11 with a sealing means arranged around a negative terminal end 20 of an anode

12. The cathodes are preferably screwed to the body, using a hermetically sealing agent to seal any leaks in the screw holes. A jumper 38 electrically connects the two cathodes. The jumper is preferably soldered to the current carrier of the cathodes. A free end of the jumper serves as the positive current output. The anode 12 has a free end serving as the negative current output (negative terminal) 20. A second sealing means 30 is arranged between the anode assembly (the cartridge 200) and the battery body 1, to create a hermetic seal between them when necessary. A fourth sealing means 37 is arranged to further seal around the anode free end. Sealing is accomplished when the cartridge cover 11, together with the anode 12, is fully pressed into the inner cavity 35 of the battery body 1, via the second sealing means 30.

The cathode is preferably a gas- diffusion, multi-layered electrode (that can be provided in disc, coil, flat, cylindrical, or other form), containing a conducting mesh and gas-permeable and gas impermeable layers, the structure and technology of which assures the required electrical characteristics and necessary resource. The cathode may also incorporate additives, in quantities up to 200 mg/cm² of cathode area, such as lead oxides (PbO-Pb0₂, up to 99% PbO2) and/or alloys of silver and indium (containing up to 99% of silver) to improve the cathode performance. CHART 1

The anode is preferably made from a metal, preferably Al, Zn, Mg, or their alloys, with one or more of the additives A_a (Ga), B_a (In), C_a (Tl), D_a (Sn), E_a (Cd), F_a (Pb), G_a (Mn), and H_a (Fe) (Chart 1) to improve the electrochemical characteristics of the battery and lower self-discharge (Fig. 4 and Fig. 5). The anode thickness is preferably selected in the range of 0.05 mm to 10 mm, so that the anode and the electrolyte are used up at the same time.

The electrolyte (Chart 2) is preferably made of a dense composition of salts and alkali with additives A_e (a Sn⁺⁴ compound), B_e (a Pb⁺⁴ compound), C_e (a Ga⁺³ compound), D_e (an In⁺³ compound), E_e (a polysaccharide based on D-glucose), F_e (polyesters including amides), G_e (2-3 carbon alcohols), H_e (halides or hydroxides of alkaline metals) in order to increase the electrical load, the electrical capacitance, electrical conductance, freeze-stability and assurance of the required potential.

CHART 2

It is known that, when using solutions of salt as an electrolyte, for example NaCl, in aluminum-air batteries, the reaction product forms a gel. For the present invention, however, which, preferably, utilizes a cartridge, it is desirable to maintain the reaction products in a crystalline form. As reflected in the experimental data provided in Table 2, the use of additives B_e and H_e achieve this desired result.

Example 1

Two electrolytes were prepared, the first comprising an aqueous solution of NaCl and the second comprising an aqueous solution of NaCl with additive E_e. These electrolytes were poured into aluminum-air batteries consisting an anode with additive A_a and a gas-diffusion cathode. The batteries were then discharged at current density (j) of 400A m² for eight hours. Comparison of experimental results show that in both cases when B_e and H_e were used as additives and a gel was absent, the effectiveness of the power sources is conserved, the voltage in the elements is increased by 0.3-0.5 V (Fig. 3) and the corrosion rate of the anode is the same or less (Fig. 6). These results demonstrate that a battery according to the present invention has improved energy, working characteristics, and an improved anode depletion coefficient.

Experimental results obtained from embodiments of the proposed aluminum-air battery are shown in Tables 1 and 2. As it is seen from these tables, the proposed source is providing both high performance and stability in means of electro-energetic characteristics. The use of the complex of additives allows improved qualities for the battery.

Tables 1 and 2 and Figs. 3 to 6 show the effect from the use of these additives. For instance, the use of the additive Da, in a quantity up to 0.8 % by mass increases the battery energy capacity up to 1.4 times. The use of the additive Be (Fig. 6), in quantity 0.01 - 0.1 % by mass will decrease by more than 10 times the speed of parasitic reaction of anode corrosion in the above mentioned battery. The individual use of each additive separately improves just one of the selective parameters. However, the combined use of the proposed additives (anode, electrolyte and gas-diffusion cathode complexes of the additives) improves the overall characteristics of the battery. The selective use of individual additives allows high volt-ampere, power, and efficiency characteristics during the initial period of battery use to be achieved particularly in radio-electronic battery use. The combined use of the complexed additives maintains the optimal characteristics constant during the whole period of battery use. Fig. 12 illustrates the battery discharge characteristics with anode and electrolyte, using a combined complex of the additives.

The additives may be considered to be catalytic.

Curve 1 - without additives

Curve 2 - additive Ag (5mg/cm²);

Curve 3 - additives Pt-Pd (0.5 mg/cm²); Curve 4 - additive Pb ( 10 mg/cm²)

The optimum use of combined complex of additives in anode, electrolyte, and cathode increase the energy capacity of the battery (Fig. 15). The electric capacity of the battery increases more than twice at the medium and high density current (more than 100 mA cm², temperature - 20° C). Fig. 9 illustrates experimental volt-ampere characteristics of a battery with the use of an air-diffusion electrodes according to the invention with hydro-phobic, catalytic, and hydrophilic layers, and current collector of the metallic mesh.

Table 1. Electrolytic Characteristics of An Aluminum-Air Battery with Alkali Electrolyte

T Electrolyte Volume V=32ml

Cross section S=22.1 cm²

Specific capacitance C - = 0.159A-hr/ml - 0.138A-hr/gr

Temperature T° = 293°K

Current density I

Anode potential F_ia

Cathode potential F_ik

Battery voltage V

Time of experiment t

Experiment number N

Table 2.

Electrolyte: 4M aqueous salt solution Anode: aluminum alloy with a base additive D_a (Sn) Discharge Current Density: 452.56 A/m²

Table 3. Metallic additives (inhibitors) and the high level of hydrogen over-voltage

φ_p = Thermodynamic equilibrium potential

The principal electrochemical processes in an air-aluminum source take place in the electrolyte, as well as on the surfaces of the aluminum anode and the gas-diffusion cathode. On account of this, the invention herein makes use of three complexes of multi- parameter additives for optimizing the battery's performance, namely:

- an electrolyte additive complex;

- an anode additive complex; - a cathode additive complex.

The composition of all three additive complexes is directed at achieving optimal characteristics the battery. The choice of the optimal complexes and their compositions is aimed at reducing corrosion rate in the presence of an aqueous alkali electrolyte solution, while at the same time ensuring effective anode activity in the current- generating reaction.

Referring to the polarization chart represented in Fig. 8, an analysis of the summarizing expression for electrochemical corrosion rate can be formulated:

(φp - φ_pa)

Icor = X K,(10) (dφ_k/dl_k - dφ_a/dI_a+R_ei)

Here, the value (φ_pk - φ_pa) is the EMF of the corrosion element and is proportional to the reduction of the system's free energy during the corrosion process. The denominator of the above expression represents the general deceleration of the corrosion process and has the dimension of ohm. It is expressed by three values characterizing the kinetics (polarization ability) of the cathode (dφ_k/dl_k) and the anode (dφ_a/dl_a) processes and the ohmic resistance Rei between the anode and cathode areas.

Figs. 9 to 15 show the data obtained by experiments conducted with the purpose of determining the optimal composition of the complexes of multi-parameter additives for the anode, cathode and electrolyte, as well as their compositions.

It is worth noting that the above description relates to the preferred embodiments by way of examples only. Many variations on the invention will be obvious to those knowledgeable in the field, and such obvious variations are within the scope of the invention as described and claimed, whether or not expressly described. Although this disclosure has described and illustrated certain preferred embodiments of the invention, it is to be understood that the invention is not restricted to those particular embodiments. Rather, the invention includes all embodiments which are functional or mechanical equivalents of the specific embodiments and features that have been described and illustrated.

Claims

1. An improved metal anode-oxygen diffusion cathode battery having an anode; an oxygen diffusion cathode; an aqueous electrolyte containing metal cations selected from the group consisting of alkali metal cations and alkaline earth cations; the improvement wherein said electrolyte comprises an additive selected from the group consisting of i) metal cations of Pb, Sn, Ga and In at a cumulative concentration of 0.001 to 1 M; provided that when Pb, Ga and In is absent the concentration of Sn is greater than >0.2M; and provided that in the presence of both of Mg and Sn together, the concentration of In is greater than 0.2M; ii) an organic additive selected from the group consisting of 1-15% W/W of a D-glucose polysaccharide, 0.5 - 5% W/W of a polyester, 0.5% of an aliphatic alcohol selected from ethyl alcohol and propyl alcohol, and mixtures thereof: and iii) a halide anion selected from the group consisting of F^", Cl^", Br^", I^" and mixtures thereof.

2. A battery as defined in claim 1 wherein said electrolyte comprises a metal cation of Pb, Sn, Ga and In at a cumulative concentration of 0.001 to IM and an organic additive in an amount as defined in claim 1.

3. A battery as defined in claim 1 wherein said electrolyte comprises a metal cation of Pb, Sn, Ga and In at a cumulative concentration of 0.001 to IM; and a halide anion selected from the group consisting of F^", Cl^", Br^', I^" and mixtures thereof.

4. A battery as defined in claim 1 wherein said electrolyte composition comprises an organic additive in an amount as defined in claim 1.

5. A battery as defined in claim 2 wherein said electrolyte further comprises a halide anion selected from the group consisting of F^", Cl^", Br^", I^" and mixtures thereof.

6. A battery as defined in any one of claims 1 to 5 wherein said polysaccharide is rectified starch.

7. A battery as defined in any one of claims 1 to 6 wherein said polyester is a polyacrylamide.

8. A battery as defined in any one of claims 1 to 7 wherein said electrolyte comprises 0.5 ml./L of Sn, 0.5 mol L of Pb, 0.5 mol/L of Ga, 0.5 mol./L of In, 10%) by mass of starch, 2.5% by mass of polyacrylamide, 10% by mass of ethyl alcohol and 0.5 mol/L sodium hydroxide.

9. An improved metal anode-oxygen diffusion cathode battery having an anode; an oxygen diffusion cathode; an aqueous electrolyte containing metal cations selected from the group consisting of alkali metal cations and alkaline earth cations; the improvement wherein said anode comprises a metal selected from the group consisting of aluminium, zinc, magnesium, and alloys thereof and further comprising i) at least 0.02 W/W % Fe and ii) a metal selected from the group consisting of Ga, In, Th, Sn, Pb, Mn and mixtures thereof, at a cumulative concentration of 0.01 - 5 W/W %; provided that if Fe is at a concentration of less than 0.15% W/W Mn may only be present at a concentration greater than 0.3 W/W %; and Ga may only be present at a concentration greater than 0.07 W/W %.

10. A battery as claimed in claim 9 wherein said anode comprises 0.02 - 0.05 W/W % Fe, 0.4 - 0.6W/W % Sn and 0.4 - 0.7W/W % In, and the balance is aluminium.

11. An improved metal anode-oxygen diffusion cathode battery having an anode; an oxygen diffusion cathode; an aqueous electrolyte containing metal cations selected from the group consisting of alkali metal cations and alkaline earth cations; the improvement comprising said electrolyte comprises an additive as defined in any one of claims 1 to 8 and said anode is as defined in claim 9 or claim 10.

12. A battery as defined in any one of claims 1 to 11 comprising at least one non-consumable gas-diffusion cathode; at least one consumable anode; an aqueous electrolyte containing metal ions; a housing enclosing said electrolyte, said at least one cathode and said at least one anode; a first unit comprising said housing and said at least one cathode;

5 a second unit comprising said at least one anode and said electrolyte wherein said electrolyte is contained within an electrolyte impermeable container, said second unit is adapted to be replaceably, received in sealing engagement within said first unit, and puncture means to effect puncture of said electrolyte impermeable container and allow said electrolyte to make contact between said at least one o anode and said at least one cathode when said second unit is received within said first unit.

13. A battery as defined in claim 12 wherein said container is formed of a plastics material.

14. A battery as defined in claim 12 or claim 13 further comprising at least one first 5 conduit for connecting to and distributing ambient air, at least one second conduit for distributing said electrolyte, and at least one third conduit for collecting reaction products in cooperation said at least one first conduit and said at least one second conduit.

15. A battery according to any one of claims 12 to 14 wherein said puncture means 0 comprises a substantially U-shaped element having sharp ends, said puncture element being arranged inside said electrolyte impermeable container, and said battery further comprises puncturing means for pressing said electrolyte impermeable container against said sharp ends, to cause said electrolyte impermeable container to break. 5 16. A battery according to claim 15 wherein said puncturing means comprises a thread, which is attached to said electrolyte impermeable container. 17. A battery according to claim 15 wherein said puncturing means comprises a push bar having a pedestal-type end, which contacts said electrolyte impermeable container. 0