Nickel-zinc battery
Encyclopedia
The nickel–zinc battery (sometimes abbreviated to the chemical symbols for the elements "NiZn") is a type of rechargeable battery
that may be used in cordless power tools, cordless telephones, digital cameras, battery operated lawn and garden tools, professional photography, flashlight
s, electric bikes, and light electric vehicle
sectors.
Larger nickel
–zinc
battery systems have been known for over 100 years. Since 2000, development of a stabilized zinc electrode
system made this technology viable and competitive with other commercially available rechargeable battery systems.
was awarded for a rechargeable nickel–zinc battery system.
The battery was later developed by an Irish chemist, Dr. James J. Drumm (1897–1974) and installed in four 2-car Drumm railcar sets between 1932 and 1948 for use on the Dublin–Bray line. Although successful they were then withdrawn when the batteries wore out. Early nickel–zinc batteries were plagued by limited number of discharge cycles. In the 1960s, nickel–zinc batteries were investigated as an alternative to silver–zinc batteries for military applications, and in the 1970s were again of interest for electric vehicles. A company called Evercel Inc. formerly developed and patented several improvements in nickel–zinc batteries but withdrew from that area in 2004.
cells—but with a higher 1.6 V nominal voltage.
Presently this battery technology has limited consumer availability, with only AA
cells offered for the digital camera market in some camera stores, or other outlet stores. Both D
-cells and sub-C cells are currently used in commercial applications.
Nickel–zinc batteries perform well in high-drain applications, and may have the potential to replace lead–acid batteries because of their higher energy-to-mass ratio and higher power-to-mass ratio (up to 75% lighter for the same power). NiZn are also lower in cost, compared to nickel-cadmium batteries (expected to be priced somewhere in between NiCd and lead–acids). NiZn may be used as a substitute for nickel
-cadmium
. The European Parliament has supported bans on cadmium-based batteries; nickel–zinc offers the European power tool industry an alternative.
Note that the stoichiometry above is different than below, but the reactions are identical. Water is consumed and generated on the charge and discharge cycles.
Discharge Reaction: H2O + Zn + 2NiOOH ↔ ZnO +2Ni(OH)2.
Electrochemical open circuit voltage potential: ~1.73 V.
or whiskers
, which may reduce the cell discharging performance or eventually short out the cell, resulting in low cycle life.
Recent advancements have enabled manufacturers to prevent this problem. These advancements include improved electrode separator materials, zinc material stabilizers, and electrolyte improvements (using phosphate
s). One manufacturer (PowerGenix
), which has developed 1.6V batteries, has claimed battery cycle life comparable to NiCd batteries.
Battery cycle life is most commonly specified at a discharge depth of 80 percent of rated capacity and assuming a one-hour discharge current rate. If the discharge current rate is reduced, or if the depth of discharge is reduced, then the number of charge-discharge cycles for a battery increases.
When comparing NiZn to other battery technologies, it is important to note that cycle life specifications may vary with other battery technologies, depending on the discharge rate and depth of discharge that were used.
NiCd and NiMH both have nominal cell voltages of 1.2 V, which may cause some electronic equipment to shut off prior to a complete discharge of the battery because the minimal operating voltage is not provided.
Due to their higher voltage, fewer cells are required (compared to NiCd and NiMH) to achieve a given battery-pack voltage, reducing pack weight, size and improving pack reliability. They also have low internal impedance
(typically 5 milliohms), which allows for high battery discharge rates.
NiZn batteries do not use mercury, lead or cadmium, or metal hydrides that are difficult to recycle. Both nickel and zinc are commonly occurring elements in nature. Zinc and nickel can be fully recycled.
NiZn cells use no flammable active material or organic electrolyte.
Properly designed NiZn cells can have very high power density and low temperature discharging performance.
Compared with other secondary systems, nickel–zinc cells have lower volumetric energy density. Nickel is also more costly than the lead used in lead-acid batteries.
Known charging regimes include constant current of C or C/2 to cell voltage = 1.9 V. Maximum charge time is 2½ hours. Trickle charging
is not recommended, as recombination is not provided for, and excess hydrogen
will eventually vent, adversely affecting battery cycle life. Charge is reinitiated after cell voltage has fallen below 1.6 V.
Rechargeable battery
A rechargeable battery or storage battery is a group of one or more electrochemical cells. They are known as secondary cells because their electrochemical reactions are electrically reversible. Rechargeable batteries come in many different shapes and sizes, ranging anything from a button cell to...
that may be used in cordless power tools, cordless telephones, digital cameras, battery operated lawn and garden tools, professional photography, flashlight
Flashlight
A flashlight is a hand-held electric-powered light source. Usually the light source is a small incandescent lightbulb or light-emitting diode...
s, electric bikes, and light electric vehicle
Electric vehicle
An electric vehicle , also referred to as an electric drive vehicle, uses one or more electric motors or traction motors for propulsion...
sectors.
Larger nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
–zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
battery systems have been known for over 100 years. Since 2000, development of a stabilized zinc electrode
Electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...
system made this technology viable and competitive with other commercially available rechargeable battery systems.
History
In 1901, Thomas EdisonThomas Edison
Thomas Alva Edison was an American inventor and businessman. He developed many devices that greatly influenced life around the world, including the phonograph, the motion picture camera, and a long-lasting, practical electric light bulb. In addition, he created the world’s first industrial...
was awarded for a rechargeable nickel–zinc battery system.
The battery was later developed by an Irish chemist, Dr. James J. Drumm (1897–1974) and installed in four 2-car Drumm railcar sets between 1932 and 1948 for use on the Dublin–Bray line. Although successful they were then withdrawn when the batteries wore out. Early nickel–zinc batteries were plagued by limited number of discharge cycles. In the 1960s, nickel–zinc batteries were investigated as an alternative to silver–zinc batteries for military applications, and in the 1970s were again of interest for electric vehicles. A company called Evercel Inc. formerly developed and patented several improvements in nickel–zinc batteries but withdrew from that area in 2004.
Applications
Nickel–zinc batteries have a charge/discharge curve similar to 1.2 V NiCd or NiMHNIMH
NIMH or NiMH may refer to:*Nickel-metal hydride battery, a type of rechargeable battery*National Institute of Mental Health, a part of the United States National Institutes of Health...
cells—but with a higher 1.6 V nominal voltage.
Presently this battery technology has limited consumer availability, with only AA
AA battery
An AA battery is a standard size of battery. Batteries of this size are the most commonly used type of in portable electronic devices. An AA battery is composed of a single electrochemical cell...
cells offered for the digital camera market in some camera stores, or other outlet stores. Both D
D battery
A D battery is a size of dry cell. A D cell is cylindrical with electrical contacts at each end; the positive end having a nub or bump...
-cells and sub-C cells are currently used in commercial applications.
Nickel–zinc batteries perform well in high-drain applications, and may have the potential to replace lead–acid batteries because of their higher energy-to-mass ratio and higher power-to-mass ratio (up to 75% lighter for the same power). NiZn are also lower in cost, compared to nickel-cadmium batteries (expected to be priced somewhere in between NiCd and lead–acids). NiZn may be used as a substitute for nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
-cadmium
Cadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...
. The European Parliament has supported bans on cadmium-based batteries; nickel–zinc offers the European power tool industry an alternative.
Electrochemistry
Charge Reaction: 2Ni(OH)2(s) + Zn(OH)2(s) ↔ 2Ni(OH)3(s) + Zn(s).Note that the stoichiometry above is different than below, but the reactions are identical. Water is consumed and generated on the charge and discharge cycles.
Discharge Reaction: H2O + Zn + 2NiOOH ↔ ZnO +2Ni(OH)2.
Electrochemical open circuit voltage potential: ~1.73 V.
Battery life
The tendency of the zinc electrode to dissolve into solution and not fully migrate back to the cathode during recharging has, in the past, presented challenges to the commercial viability of the NiZn battery. The zinc's reluctance to fully return to the same location of the solid electrode adversely manifests itself as shape change and dendritesDendrite (crystal)
A crystal dendrite is a crystal that develops with a typical multi-branching tree-like form. Dendritic crystal growth is very common and illustrated by snowflake formation and frost patterns on a window. Dendritic crystallization forms a natural fractal pattern...
or whiskers
Whisker (metallurgy)
Metal whiskering is a crystalline metallurgical phenomenon involving the spontaneous growth of tiny, filiform hairs from a metallic surface. The effect is primarily seen on elemental metals but also occurs with alloys....
, which may reduce the cell discharging performance or eventually short out the cell, resulting in low cycle life.
Recent advancements have enabled manufacturers to prevent this problem. These advancements include improved electrode separator materials, zinc material stabilizers, and electrolyte improvements (using phosphate
Phosphate
A phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...
s). One manufacturer (PowerGenix
PowerGenix
PowerGenix is a San Diego-based company developing rechargeable batteries, Nickel-zinc and recycling batteries. Nickel-Zinc are generally viewed much safer than Nickel-cadmium. Cadmium is banned in the EU, Toys R Us and Mattel...
), which has developed 1.6V batteries, has claimed battery cycle life comparable to NiCd batteries.
Battery cycle life is most commonly specified at a discharge depth of 80 percent of rated capacity and assuming a one-hour discharge current rate. If the discharge current rate is reduced, or if the depth of discharge is reduced, then the number of charge-discharge cycles for a battery increases.
When comparing NiZn to other battery technologies, it is important to note that cycle life specifications may vary with other battery technologies, depending on the discharge rate and depth of discharge that were used.
Advantages
Nickel–zinc cells have an open circuit voltage of 1.8 volts when fully charged and a nominal voltage of 1.65 V. This makes NiZn an excellent replacement for electronic products that were designed to use alkaline primary cells (1.5 V).NiCd and NiMH both have nominal cell voltages of 1.2 V, which may cause some electronic equipment to shut off prior to a complete discharge of the battery because the minimal operating voltage is not provided.
Due to their higher voltage, fewer cells are required (compared to NiCd and NiMH) to achieve a given battery-pack voltage, reducing pack weight, size and improving pack reliability. They also have low internal impedance
Impedance
Impedance may refer to:*Electrical impedance, the ratio of the voltage phasor to the electric current phasor, a measure of the opposition to time-varying electric current in an electric circuit**Characteristic impedance of a transmission line...
(typically 5 milliohms), which allows for high battery discharge rates.
NiZn batteries do not use mercury, lead or cadmium, or metal hydrides that are difficult to recycle. Both nickel and zinc are commonly occurring elements in nature. Zinc and nickel can be fully recycled.
NiZn cells use no flammable active material or organic electrolyte.
Properly designed NiZn cells can have very high power density and low temperature discharging performance.
Disadvantages
Currently, only Sub C, AA and AAA NiZn cells are available.Compared with other secondary systems, nickel–zinc cells have lower volumetric energy density. Nickel is also more costly than the lead used in lead-acid batteries.
Charging
NiZn technology is well suited for fast recharge cycling as optimum charge rates of C or C/2 are preferred.Known charging regimes include constant current of C or C/2 to cell voltage = 1.9 V. Maximum charge time is 2½ hours. Trickle charging
Trickle charging
Trickle charging, or float charging, means charging a battery at a similar rate as its self-discharging rate, thus maintaining a full capacity battery. Most rechargeable batteries, particularly nickel-cadmium batteries or nickel metal hydride batteries, have a moderate rate of self-discharge,...
is not recommended, as recombination is not provided for, and excess hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
will eventually vent, adversely affecting battery cycle life. Charge is reinitiated after cell voltage has fallen below 1.6 V.
External links
- PowerGenix Batteries - homepage of PowerGenixPowerGenixPowerGenix is a San Diego-based company developing rechargeable batteries, Nickel-zinc and recycling batteries. Nickel-Zinc are generally viewed much safer than Nickel-cadmium. Cadmium is banned in the EU, Toys R Us and Mattel...
(retrieved 2011-02-12)