creativeadapter1990
10 mW
First of all there a lot of things being called nickle zinc.
Most can be broken into 3 categories:
gen 1: these have conventional separators, normal (slightly impure) zinc, and have a cycle life from 25 to 50 for conventional separators to 100 cycles for plate pocket. most older batteries are of this type.
Gen 2: These have dendrite resistant separators, electrolyte additives such as phosphates, and use refined virgin zinc. cycle life is 150 to 400, sometimes advertized as 500 but that would only be for a pampered shallow cycle use situation.
Powergenix cells and probably xellerion use this technology.
Gen 3, spinel nickle batteries: These are fundamentally different than the previous batteries. The anode is not pure zinc like gen 2 but uses a calcium zinc alloy. when it is oxidized during discharge it forms calcium zincate, which unlike zinc hydroxide is insoluble and stable in the electrolyte. cycle life is from 500 to 1000 cycles. Due to the added calcium they have slightly lower energy density than gen 2. The improvements in separators, electrolytes, and electrode design from gen 2 are usually retained. "Development cells have demonstrated the ability to deliver over 60 Watt-hours per kilogram at the one hour rate. Cycle life has been improved to more than 600 cycles at 80% depth of discharge by using a patented, reduced solubility zinc electrode and an improved sealed cell design. More than 8000 charge/discharge cycles at 10% depth-of-discharge have been completed." (Coates et al, 1997)
A relevant patent by the same group who made the above cells is: http://www.google.com/patents/US586...page&q=calcium zincate battery nickel&f=false which was filed in 1997 and formally issued in 1999. Under American patent law it will expire in 2016.
Why can't you buy them?
According to Prof. Ziyad Salameh of the University of Massachusetts Battery Evaluation Lab there is an interesting story to what happened to Evercell that goes beyond "cycle life was shorter than claimed"
Evercell started by making gen 3 batteries. They were expensive, at first a 14v group 31 size battery cost $1000 usd. With mass production the cost was brought down to $350. Evercel then tried to bring the costs down even further by making gen 2 cells in China. The Chinese factory they contracted failed to use the high purity zinc needed and used lower quality electrolyte additives. The result was gen 1 cells marketed as having better cycle life than most gen 2 cells do, and a lot of unhappy customers who went back to lead acid. The company and all its patents got bought by a Korean firm and no one has since made gen 3 cells.
Evionyx and Reveo promised rechargeable NiZn and ZnAir batteries but appear to be scam operations. They made a small number of stellar prototypes and filed some impressive patents (suckered investors by saying they were almost ready to market them for several years.
There were other crimes likely going on as well;
"Another sign of Sadeg M. Faris’s questionable business ethics can be found when the Malaysian police in 2005 froze the assets of InventQjaya which was founded and a 100% owned subsidiary of Reveo Inc. and moved to seize them under Malaysia’s Money Laundering Act of 2001. Even though Faris was cleared of all charges after 8 months of investigation the Malaysian government did choose to liquidate the company citing a breach of contract and loan agreements."
http://victimadvocates.net/evionyx-reveo-ceo-sadeg-m-faris-rip-off-alert/
Most can be broken into 3 categories:
gen 1: these have conventional separators, normal (slightly impure) zinc, and have a cycle life from 25 to 50 for conventional separators to 100 cycles for plate pocket. most older batteries are of this type.
Gen 2: These have dendrite resistant separators, electrolyte additives such as phosphates, and use refined virgin zinc. cycle life is 150 to 400, sometimes advertized as 500 but that would only be for a pampered shallow cycle use situation.
Powergenix cells and probably xellerion use this technology.
Gen 3, spinel nickle batteries: These are fundamentally different than the previous batteries. The anode is not pure zinc like gen 2 but uses a calcium zinc alloy. when it is oxidized during discharge it forms calcium zincate, which unlike zinc hydroxide is insoluble and stable in the electrolyte. cycle life is from 500 to 1000 cycles. Due to the added calcium they have slightly lower energy density than gen 2. The improvements in separators, electrolytes, and electrode design from gen 2 are usually retained. "Development cells have demonstrated the ability to deliver over 60 Watt-hours per kilogram at the one hour rate. Cycle life has been improved to more than 600 cycles at 80% depth of discharge by using a patented, reduced solubility zinc electrode and an improved sealed cell design. More than 8000 charge/discharge cycles at 10% depth-of-discharge have been completed." (Coates et al, 1997)
A relevant patent by the same group who made the above cells is: http://www.google.com/patents/US586...page&q=calcium zincate battery nickel&f=false which was filed in 1997 and formally issued in 1999. Under American patent law it will expire in 2016.
Why can't you buy them?
According to Prof. Ziyad Salameh of the University of Massachusetts Battery Evaluation Lab there is an interesting story to what happened to Evercell that goes beyond "cycle life was shorter than claimed"
Evercell started by making gen 3 batteries. They were expensive, at first a 14v group 31 size battery cost $1000 usd. With mass production the cost was brought down to $350. Evercel then tried to bring the costs down even further by making gen 2 cells in China. The Chinese factory they contracted failed to use the high purity zinc needed and used lower quality electrolyte additives. The result was gen 1 cells marketed as having better cycle life than most gen 2 cells do, and a lot of unhappy customers who went back to lead acid. The company and all its patents got bought by a Korean firm and no one has since made gen 3 cells.
Evionyx and Reveo promised rechargeable NiZn and ZnAir batteries but appear to be scam operations. They made a small number of stellar prototypes and filed some impressive patents (suckered investors by saying they were almost ready to market them for several years.
There were other crimes likely going on as well;
"Another sign of Sadeg M. Faris’s questionable business ethics can be found when the Malaysian police in 2005 froze the assets of InventQjaya which was founded and a 100% owned subsidiary of Reveo Inc. and moved to seize them under Malaysia’s Money Laundering Act of 2001. Even though Faris was cleared of all charges after 8 months of investigation the Malaysian government did choose to liquidate the company citing a breach of contract and loan agreements."
http://victimadvocates.net/evionyx-reveo-ceo-sadeg-m-faris-rip-off-alert/
