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The novelty promises to surpass lithium-ion batteries in terms of energy consumption by three times and at the same time cost half as much.
Note that now zinc-air batteries are produced only in the form of disposable cells or "rechargeable" manually, that is, by changing the cartridge. By the way, this type of battery is safer than lithium-ion, as it does not contain volatile substances and, accordingly, cannot ignite.
The main obstacle to creating rechargeable options from the network - that is, batteries - is the rapid degradation of the device: the electrolyte is deactivated, the oxidation-reduction reactions slow down and stop altogether after just a few recharge cycles.
To understand why this happens, we must first describe the principle of operation of air-zinc elements. The battery consists of air and zinc electrodes and electrolyte. During discharge, the air coming from outside, not without the help of catalysts, forms hydroxyl ions (OH -) in an aqueous electrolyte solution.
They oxidize the zinc electrode. During this reaction, electrons are released, forming a current. During battery charging, the process goes in the opposite direction: oxygen is produced at the air electrode.
Previously, during the operation of a rechargeable battery, the aqueous electrolyte solution often simply dried out or penetrated too deeply into the pores of the air electrode. In addition, the deposited zinc was distributed unevenly, forming a branched structure, due to which short circuits began to occur between the electrodes.
The novelty is devoid of these shortcomings. Special gelling and astringent additives control the moisture and shape of the zinc electrode. In addition, scientists have proposed new catalysts, which also significantly improved the performance of the elements.
So far, the best performance of prototypes does not exceed hundreds of recharge cycles (photo by ReVolt).
ReVolt CEO James McDougall believes that the first products, unlike current prototypes, will be recharged up to 200 times, and will soon be able to reach the mark of 300-500 cycles. This indicator will allow the element to be used, for example, in cell phones or laptops.
The prototype of the new battery was developed at the Norwegian research foundation SINTEF, while ReVolt is commercializing the product (ReVolt illustration).
ReVolt is also developing zinc air batteries for electric vehicles. Such products resemble fuel cells. The zinc suspension in them plays the role of a liquid electrode, while the air electrode consists of a system of tubes.
Electricity is generated by pumping the suspension through the tubes. The resulting zinc oxide is then stored in another compartment. When recharged, it goes through the same path, and the oxide turns back into zinc.
Such batteries can produce more electricity, since the volume of the liquid electrode can be much larger than the volume of the air electrode. McDougall believes this type of cell could be recharged between two and ten thousand times.
The release of compact zinc-air batteries to the mass market can significantly change the situation in the market segment of small-sized autonomous power supplies for portable computers and digital devices.
energy problem
and in recent years, the fleet of portable computers and various digital devices has increased significantly, many of which have appeared on the market quite recently. This process has accelerated markedly due to the increasing popularity of mobile phones. In turn, the rapid growth in the number of portable electronic devices caused a serious increase in demand for autonomous sources of electricity, in particular for different kinds batteries and accumulators.
However, the need to provide a huge number of portable devices with batteries is only one side of the problem. Thus, as portable electronic devices develop, the density of mounting elements and the power of the microprocessors used in them increase - in just three years, the clock frequency of the PDA processors used has increased by an order of magnitude. Tiny monochrome screens are being replaced by color displays with high resolution and larger screen size. All this leads to an increase in energy consumption. In addition, in the field of portable electronics, there is a clear trend towards further miniaturization. Taking into account the above factors, it becomes quite obvious that an increase in the energy intensity, power, durability and reliability of the batteries used is one of the most important conditions for ensuring further development portable electronic devices.
The problem of renewable autonomous power sources is very acute in the segment of portable PCs. Modern technologies allow you to create laptops that are practically not inferior in terms of functionality and performance to full-fledged desktop systems. However, the lack of sufficiently efficient autonomous power sources deprives laptop users of one of the main advantages of this type of computer - mobility. A good indicator for a modern laptop equipped with a lithium-ion battery is a battery life of about 4 hours 1 , but this is clearly not enough for full-fledged work in mobile conditions (for example, a flight from Moscow to Tokyo takes about 10 hours, and from Moscow to Los Angeles). Angeles - almost 15).
One of the solutions to the problem of increasing the time battery life portable PCs is the transition from the now common nickel-metal hydride and lithium-ion batteries to chemical fuel cells 2 . The most promising from the point of view of application in portable electronic devices and PCs are fuel cells with a low operating temperature - such as PEM (Proton Exchange Membrane) and DMCF (Direct Methanol Fuel Cells). An aqueous solution of methyl alcohol (methanol) 3 is used as fuel for these elements.
However, at this stage, it would be too optimistic to describe the future of chemical fuel cells exclusively in pink colors. The fact is that at least two obstacles stand in the way of the mass distribution of fuel cells in portable electronic devices. Firstly, methanol is a rather toxic substance, which implies increased requirements for tightness and reliability of fuel cartridges. Secondly, to ensure an acceptable rate of chemical reactions in fuel cells with a low operating temperature, it is necessary to use catalysts. PEM and DMCF cells currently use catalysts made from platinum and its alloys, but the natural resources of this substance are small and its cost is high. It is theoretically possible to replace platinum with other catalysts, but so far none of the teams involved in research in this direction has been able to find an acceptable alternative. Today, the so-called platinum problem is perhaps the most serious obstacle to the widespread use of fuel cells in portable PCs and electronic devices.
1 This refers to the operating time from a standard battery.
2 More information about fuel cells can be found in the article “Fuel cells: a year of hope”, published in No. 1’2005.
3 Hydrogen gas PEM cells are equipped with a built-in converter to produce hydrogen from methanol.
Air-zinc elements
Although the authors of a number of publications consider zinc-air batteries and accumulators to be one of the subtypes of fuel cells, this is not entirely true. Having become acquainted with the device and principle of operation of zinc-air cells, even in general terms, we can make a completely unambiguous conclusion that it is more correct to consider them as a separate class of autonomous power sources.
The zinc air cell design includes a cathode and an anode separated by an alkaline electrolyte and mechanical separators. A gas diffusion electrode (GDE) is used as a cathode, the permeable membrane of which makes it possible to obtain oxygen from atmospheric air circulating through it. The “fuel” is the zinc anode, which is oxidized during the operation of the element, and the oxidizing agent is oxygen obtained from atmospheric air entering through the “breathing holes”.
At the cathode, an oxygen electroreduction reaction occurs, the products of which are negatively charged hydroxide ions:
O 2 + 2H 2 O + 4e 4OH -.
Hydroxide ions move in the electrolyte to the zinc anode, where the zinc oxidation reaction occurs with the release of electrons, which return to the cathode through an external circuit:
Zn + 4OH – Zn(OH) 4 2– + 2e.
Zn(OH) 4 2– ZnO + 2OH – + H 2 O.
It is quite obvious that zinc-air cells do not fall under the classification of chemical fuel cells: firstly, they use a consumable electrode (anode), and secondly, the fuel is initially placed inside the cell, and is not supplied from the outside during operation.
The voltage between the electrodes of one cell of a zinc air cell is 1.45 V, which is very close to that of alkaline (alkaline) batteries. If necessary, to obtain a higher supply voltage, several series-connected cells can be combined into a battery.
Zinc is a fairly common and inexpensive material, so when mass production of zinc-air elements is deployed, manufacturers will not experience problems with raw materials. In addition, even at the initial stage, the cost of such power supplies will be quite competitive.
It is also important that air-zinc elements are very environmentally friendly products. The materials used for their production do not poison the environment and can be reused after processing. The reaction products of air-zinc elements (water and zinc oxide) are also absolutely safe for humans and the environment - zinc oxide is even used as the main component of baby powder.
Of the operational properties of air-zinc elements, it is worth noting such advantages as low speed self-discharge in the non-activated state and a small change in the magnitude of the voltage as the discharge progresses (flat discharge curve).
A certain disadvantage of air-zinc elements is the influence of the relative humidity of the incoming air on the characteristics of the element. For example, for a zinc-air element designed for operation in conditions of relative humidity of 60%, with an increase in humidity to 90%, the service life decreases by about 15%.
From batteries to accumulators
Disposable batteries are the easiest zinc-air cell to implement. When creating air-zinc elements big size and power (for example, designed to power the power plants of vehicles), zinc anode cassettes can be made replaceable. In this case, to renew the energy reserve, it is enough to remove the cassette with used electrodes and install a new one instead. Spent electrodes can be recovered for reuse by the electrochemical method at specialized enterprises.
If we talk about compact batteries suitable for use in portable PCs and electronic devices, then the practical implementation of the option with replaceable zinc anode cassettes is impossible due to the small size of the batteries. That is why most of the compact zinc air cells currently on the market are disposable. Single-use zinc-air batteries of small size are produced by Duracell, Eveready, Varta, Matsushita, GP, as well as the domestic enterprise Energia. The main scope of such power supplies is hearing aids, portable radios, photographic equipment, etc.
Many companies are now producing disposable zinc air batteries.
Several years ago, AER produced Power Slice zinc-air flat batteries for portable computers. These items were designed for Hewlett-Packard's Omnibook 600 and Omnibook 800 series notebooks; their battery life ranged from 8 to 12 hours.
In principle, there is also the possibility of creating rechargeable zinc-air cells (accumulators), in which, when an external current source is connected, a zinc reduction reaction will occur at the anode. However, the practical implementation of such projects for a long time hampered by serious problems due to the chemical properties of zinc. Zinc oxide dissolves well in an alkaline electrolyte and, in dissolved form, is distributed throughout the volume of the electrolyte, moving away from the anode. Because of this, when charging from an external current source, the geometry of the anode changes to a large extent: the zinc reduced from oxide is deposited on the anode surface in the form of ribbon crystals (dendrites), similar in shape to long spikes. The dendrites pierce through the separators, causing short circuit inside the battery.
This problem aggravated by the fact that to increase the power, the anodes of air-zinc cells are made from crushed zinc powder (this allows you to significantly increase the surface area of the electrode). Thus, as the number of charge-discharge cycles increases, the surface area of the anode will gradually decrease, having a negative impact on cell performance.
To date, Zinc Matrix Power (ZMP) has achieved the greatest success in the field of compact zinc-air batteries. ZMP experts have developed a unique technology Zinc Matrix, which allowed to solve the main problems that arise in the process of charging batteries. The essence of this technology is the use of a polymeric binder, which provides unhindered penetration of hydroxide ions, but at the same time blocks the movement of zinc oxide that dissolves in the electrolyte. Thanks to the use of this solution, it is possible to avoid a noticeable change in the shape and surface area of the anode for at least 100 charge-discharge cycles.
The advantages of zinc-air batteries are a long operating time and a high specific energy intensity, at least twice as high as those of the best lithium-ion batteries. The specific energy intensity of zinc-air batteries reaches 240 Wh per 1 kg of weight, and the maximum power is 5000 W/kg.
According to ZMP developers, today it is possible to create zinc-air batteries for portable electronic devices (mobile phones, digital players, etc.) with an energy capacity of about 20 Wh. The minimum possible thickness of such power supplies is only 3 mm. Experimental prototypes of zinc-air batteries for laptops have an energy capacity of 100 to 200 Wh.
Zinc air battery prototype developed by Zinc Matrix Power
Another important advantage of zinc-air batteries is the complete absence of the so-called memory effect. Unlike other types of batteries, zinc-air cells can be recharged at any charge level without compromising their energy capacity. Moreover, unlike lithium batteries air-zinc elements are much safer.
In conclusion, it is impossible not to mention one important event, which became a symbolic starting point for the commercialization of zinc air cells: on June 9 last year, Zinc Matrix Power officially announced the signing of a strategic agreement with Intel Corporation. In accordance with the clauses of this agreement, ZMP and Intel will join forces in the development of new technology rechargeable batteries for laptops. Among the main goals of these works is to increase the battery life of laptops up to 10 hours. According to the existing plan, the first models of notebooks equipped with zinc-air batteries should appear on sale in 2006.
The release of compact zinc-air batteries to the mass market can significantly change the situation in the market segment of small-sized autonomous power supplies for portable computers and digital devices.
energy problem
and in recent years, the fleet of portable computers and various digital devices has increased significantly, many of which have appeared on the market quite recently. This process has accelerated markedly due to the increasing popularity of mobile phones. In turn, the rapid growth in the number of portable electronic devices has caused a serious increase in demand for autonomous sources of electricity, in particular for various types of batteries and accumulators.
However, the need to provide a huge number of portable devices with batteries is only one side of the problem. Thus, as portable electronic devices develop, the density of mounting elements and the power of microprocessors used in them increase - in just three years, the clock frequency of PDA processors used has increased by an order of magnitude. Tiny monochrome screens are being replaced by high-resolution color displays with larger screen sizes. All this leads to an increase in energy consumption. In addition, in the field of portable electronics, there is a clear trend towards further miniaturization. Taking into account the above factors, it becomes quite obvious that an increase in energy intensity, power, durability and reliability of used batteries is one of the most important conditions for ensuring the further development of portable electronic devices.
The problem of renewable autonomous power sources is very acute in the segment of portable PCs. Modern technologies make it possible to create laptops that are practically not inferior in terms of functionality and performance to full-fledged desktop systems. However, the lack of sufficiently efficient autonomous power sources deprives laptop users of one of the main advantages of this type of computer - mobility. A good indicator for a modern laptop equipped with a lithium-ion battery is a battery life of about 4 hours 1 , but this is clearly not enough for full-fledged work in mobile conditions (for example, a flight from Moscow to Tokyo takes about 10 hours, and from Moscow to Los Angeles). Angeles - almost 15).
One solution to the problem of longer battery life for portable PCs is to move from the now common nickel-metal hydride and lithium-ion batteries to chemical fuel cells 2 . The most promising from the point of view of application in portable electronic devices and PCs are fuel cells with a low operating temperature - such as PEM (Proton Exchange Membrane) and DMCF (Direct Methanol Fuel Cells). An aqueous solution of methyl alcohol (methanol) 3 is used as fuel for these elements.
However, at this stage, it would be too optimistic to describe the future of chemical fuel cells exclusively in pink colors. The fact is that at least two obstacles stand in the way of the mass distribution of fuel cells in portable electronic devices. Firstly, methanol is a rather toxic substance, which implies increased requirements for tightness and reliability of fuel cartridges. Secondly, to ensure an acceptable rate of chemical reactions in fuel cells with a low operating temperature, it is necessary to use catalysts. PEM and DMCF cells currently use catalysts made from platinum and its alloys, but the natural resources of this substance are small and its cost is high. It is theoretically possible to replace platinum with other catalysts, but so far none of the teams involved in research in this direction has been able to find an acceptable alternative. Today, the so-called platinum problem is perhaps the most serious obstacle to the widespread use of fuel cells in portable PCs and electronic devices.
1 This refers to the operating time from a standard battery.
2 More information about fuel cells can be found in the article “Fuel cells: a year of hope”, published in No. 1’2005.
3 Hydrogen gas PEM cells are equipped with a built-in converter to produce hydrogen from methanol.
Air-zinc elements
Although the authors of a number of publications consider zinc-air batteries and accumulators to be one of the subtypes of fuel cells, this is not entirely true. Having become acquainted with the device and principle of operation of zinc-air cells, even in general terms, we can make a completely unambiguous conclusion that it is more correct to consider them as a separate class of autonomous power sources.
The zinc air cell design includes a cathode and an anode separated by an alkaline electrolyte and mechanical separators. A gas diffusion electrode (GDE) is used as a cathode, the permeable membrane of which makes it possible to obtain oxygen from atmospheric air circulating through it. The “fuel” is the zinc anode, which is oxidized during the operation of the element, and the oxidizing agent is oxygen obtained from atmospheric air entering through the “breathing holes”.
At the cathode, an oxygen electroreduction reaction occurs, the products of which are negatively charged hydroxide ions:
O 2 + 2H 2 O + 4e 4OH -.
Hydroxide ions move in the electrolyte to the zinc anode, where the zinc oxidation reaction occurs with the release of electrons, which return to the cathode through an external circuit:
Zn + 4OH – Zn(OH) 4 2– + 2e.
Zn(OH) 4 2– ZnO + 2OH – + H 2 O.
It is quite obvious that zinc-air cells do not fall under the classification of chemical fuel cells: firstly, they use a consumable electrode (anode), and secondly, the fuel is initially placed inside the cell, and is not supplied from the outside during operation.
The voltage between the electrodes of one cell of a zinc air cell is 1.45 V, which is very close to that of alkaline (alkaline) batteries. If necessary, to obtain a higher supply voltage, several series-connected cells can be combined into a battery.
Zinc is a fairly common and inexpensive material, so when mass production of zinc-air elements is deployed, manufacturers will not experience problems with raw materials. In addition, even at the initial stage, the cost of such power supplies will be quite competitive.
It is also important that air-zinc elements are very environmentally friendly products. The materials used for their production do not poison the environment and can be reused after processing. The reaction products of air-zinc elements (water and zinc oxide) are also absolutely safe for humans and the environment - zinc oxide is even used as the main component of baby powder.
Of the operational properties of zinc-air cells, it is worth noting such advantages as a low self-discharge rate in the non-activated state and a small change in the voltage value during the discharge (flat discharge curve).
A certain disadvantage of air-zinc elements is the influence of the relative humidity of the incoming air on the characteristics of the element. For example, for a zinc-air element designed for operation in conditions of relative humidity of 60%, with an increase in humidity to 90%, the service life decreases by about 15%.
From batteries to accumulators
Disposable batteries are the easiest zinc-air cell to implement. When creating zinc-air cells of large size and power (for example, designed to power the power plants of vehicles), the zinc anode cassettes can be made replaceable. In this case, to renew the energy reserve, it is enough to remove the cassette with used electrodes and install a new one instead. Spent electrodes can be recovered for reuse by the electrochemical method at specialized enterprises.
If we talk about compact batteries suitable for use in portable PCs and electronic devices, then the practical implementation of the option with replaceable zinc anode cassettes is impossible due to the small size of the batteries. That is why most of the compact zinc air cells currently on the market are disposable. Single-use zinc-air batteries of small size are produced by Duracell, Eveready, Varta, Matsushita, GP, as well as the domestic enterprise Energia. The main scope of such power supplies is hearing aids, portable radio stations, photographic equipment, etc.
Many companies are now producing disposable zinc air batteries.
Several years ago, AER produced Power Slice zinc-air flat batteries for portable computers. These items were designed for Hewlett-Packard's Omnibook 600 and Omnibook 800 series notebooks; their battery life ranged from 8 to 12 hours.
In principle, there is also the possibility of creating rechargeable zinc-air cells (accumulators), in which, when an external current source is connected, a zinc reduction reaction will occur at the anode. However, the practical implementation of such projects has long been hampered by serious problems caused by the chemical properties of zinc. Zinc oxide dissolves well in an alkaline electrolyte and, in dissolved form, is distributed throughout the volume of the electrolyte, moving away from the anode. Because of this, when charging from an external current source, the geometry of the anode changes to a large extent: the zinc reduced from oxide is deposited on the anode surface in the form of ribbon crystals (dendrites), similar in shape to long spikes. The dendrites pierce through the separators, causing a short circuit inside the battery.
This problem is exacerbated by the fact that to increase the power, the anodes of air-zinc cells are made from crushed zinc powder (this allows a significant increase in the surface area of the electrode). Thus, as the number of charge-discharge cycles increases, the surface area of the anode will gradually decrease, having a negative impact on cell performance.
To date, Zinc Matrix Power (ZMP) has achieved the greatest success in the field of compact zinc-air batteries. ZMP experts have developed a unique technology Zinc Matrix, which allowed to solve the main problems that arise in the process of charging batteries. The essence of this technology is the use of a polymeric binder, which provides unhindered penetration of hydroxide ions, but at the same time blocks the movement of zinc oxide that dissolves in the electrolyte. Thanks to the use of this solution, it is possible to avoid a noticeable change in the shape and surface area of the anode for at least 100 charge-discharge cycles.
The advantages of zinc-air batteries are a long operating time and a high specific energy intensity, at least twice as high as those of the best lithium-ion batteries. The specific energy intensity of zinc-air batteries reaches 240 Wh per 1 kg of weight, and the maximum power is 5000 W/kg.
According to ZMP developers, today it is possible to create zinc-air batteries for portable electronic devices (mobile phones, digital players, etc.) with an energy capacity of about 20 Wh. The minimum possible thickness of such power supplies is only 3 mm. Experimental prototypes of zinc-air batteries for laptops have an energy capacity of 100 to 200 Wh.
Zinc air battery prototype developed by Zinc Matrix Power
Another important advantage of zinc-air batteries is the complete absence of the so-called memory effect. Unlike other types of batteries, zinc-air cells can be recharged at any charge level without compromising their energy capacity. In addition, unlike lithium batteries, zinc air cells are much safer.
In conclusion, it is impossible not to mention one important event, which became a symbolic starting point for the commercialization of zinc air cells: on June 9 last year, Zinc Matrix Power officially announced the signing of a strategic agreement with Intel Corporation. Under the terms of this agreement, ZMP and Intel will join forces to develop new laptop battery technology. Among the main goals of these works is to increase the battery life of laptops up to 10 hours. According to the existing plan, the first models of notebooks equipped with zinc-air batteries should appear on sale in 2006.
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The international company WIDEX has been manufacturing and selling hearing aids since 1956. We are constantly improving devices to provide optimal audibility and comfort for our customers.
WIDEX offers hearing aids in five categories:
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If you have difficulty hearing, contact the WIDEX Hearing Center - we will help you solve the problem. Our experts will select the devices that best suit your individual needs. With our help, you will regain the ability to hear all the variety of sounds.
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The range of our hearing centers includes a complete the lineup devices of modern shapes and colors: miniature in-ear, elegant with a receiver in the ear, classic behind the ear. Widex devices and accessories received international design awards - RED DOT Design, Good Design, IF Design Award
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Widex makes sounds recognizable, speech intelligible, noise non-irritating through a range of patented Widex technologies - Widex amplification formula, speech enhancer, low background noise suppression, Inter Ear compression, wide input range from 5dB to 113dB, HD Locator, TruSound Softner and other technologies.
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We work according to Danish Widex standards. There is a complete set of international and Russian permits, they confirm the reliability and safety of the devices. We regularly monitor quality and user satisfaction.
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Warranty periods for repairs in a certified service center Widex Moscow is 2-3 business days. We deliver devices to Moscow and back on a weekly basis at the expense of our company through Widex regional hearing centers. You can monitor the status of service work.
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Individual housings for in-the-canal, in-the-ear devices and individual inserts are made using CAMISHA Widex 3D technology. They fit comfortably in the user's ears, as they fully correspond to the casts of the ear canals. Tight fit and optimal size of the products ensure the correct operation of the systems of the devices and an attractive appearance of the device.