Topic: Lithium iron phosphate batteries

[piersdad]

Li FE P04
these amazing new batteries are just coming out from the mass manufacturers

the method of construction just now being explored actually gives the amature an insight to the construction of these batteries and their problems

The work was more difficult because the material had to be highly conductive in order to be effective and most candidate materials for cathodes are highly insulating.
Virus
The virus picks up a carbon nanotube after being genetically engineered

The virus was coaxed into binding with iron phosphate and then carbon nanotubes to create a highly conductive material.

The batteries have the same energy capacity and power performance as rechargeable batteries used to power plug-in hybrid cars.

The prototype battery is currently the size of a coin but the scientists believe it can be scaled and be used to create flexible batteries that can take the shape of their container, which is perfect for mobile or small devices.

there is a description of how they use genetically engineered virus to construct the electrodes 




 bbc news lithium iron phosphate break through

from the ping battery co
What's LiFePO4

LiFePO4, lithium iron phosphate as cathode, a kind of advancing technology to change the world!

The safety characteristics inherent to LiFePo4 technology result from the incorporation of phosphates as the cathode material. Phosphates are extremely stable in overcharge or short circuit conditions and have the ability to withstand high temperatures without decomposing. When abuse does occur, phosphates are not prone to thermal runaway and will not burn. As a result, LiFePo4 technology possesses safety characteristics that are fundamentally superior to those of Lithium-ion batteries made with other cathode materials.

http://www.storydad.com/forum/index.php/topic,615.0.html
check here for results in a benign explosion in my work shop no damage just a bloody mess
the collected internals
the benign collection of bits alloy foil copper foil and phosphate

LiFePo4 technology does not contain any heavy metals and does not exhibit the "memory effect" of Nickel-Cadmium and Nickel-metal Hydride solutions. LiFePo4 technology demonstrates excellent shelf life, long cycle life and is maintenance free.

Another key benefit of our LiFePo4 technology is its flexibility, both in terms of battery application and cell design. It can be used in wound cylindrical, wound prismatic and polymer battery construction types and manufactured to fit smaller applications.

The advantages of traditional Lithium-ion coupled with the safety features of phosphates, make LiFePo4 technology the Lithium-ion technology for the future. LiFePo4 Lithium-ion technology utilizes natural, phosphate-based material and offers the greatest combination of performance, safety, cost, reliability and environmental characteristics.

      
Featured Product
48V 20AH V2.5 LiFePO4 Battery Pack
48V 20AH V2.5 LiFePO4 Battery Pack
Leadtime: 7 days
It will take about 7 days for us to build and test this new battery pack for you.

Specifications:
Suitable Wattage of Motor: up to 1200 Watt, 800 Watt suggested
Voltage: 48 Volts
Capacity: 20 Amp Hours
Dimension: 195x210x150 mm / 7.7x8.3x5.9 inches
Weight: 9.90 kg / 21.90 lbs
Charging Voltage: 60-61 Volts
Charging Current: <5 Amps
Rated Discharging Amperage: 20 Amps
Max Continuous Discharging Amperage: 40 Amps
Maximum Discharging Current: 60 Amps
Discharging Cut-off Protection: 50 Amps


Lifecycle of the whole pack: >85% capacity after 1000 cycles. Lifecycle of single cell: >85% capacity after 1500 cycles, >70% capacity after 3000 cycles. (<1C discharge rate and <1C charge rate)

 http://www.pingbattery.com/

and another battery company

http://www.desire-power-battery.com/Features.html
from their site

Usage safety:stability at high temperatures can be up to 400-500(and release least heat in case of abuse), no explosion or combustion by overcharging,overheating,short circuit and from collied. Lifpo4 battery is the only absolute safety battery in the world at the moment.

i can  say this is true for me and the lipo4 batteries i have used

AN EXPLANATION of the lithium ion system


from wikipedia
Lithium-ion batteries (sometimes abbreviated Li-ion batteries) are a type of rechargeable battery in which the anode (positive electrode) contains lithium, and the cathode (negative electrode)is made of a type of porous carbon. During normal operation, the current flows (when the external circuit is connected) from the anode to the cathode, as in any type of battery. During this process, the battery is discharged and the internal process occurring within the battery is the movement of Li+ ions through the non-aqueous electrolyte and separator diaphragm to the carbon cathode. The lithium ions become deeply embedded in the carbon cathode in a process known as intercalation. During charging, the current is passed in the reverse direction from an external charging circuit, the positive terminal from the charging circuit has to be connected to the cathode of the Li-battery, and the anode has to be connected to the negative terminal of the external circuit. The current passed to charge the battery back up to 3.7 volts (about 4.2 volts is applied in this manner to take into account certain factors like internal resistance of battery etc.). During the battery recharge process the internal change taking place is the reverse, that is, the lithium ions present in the carbon cathode come out , enter the electrolyte, and travel through the electrolyte and diaphragm and get back to adhere to the anode made of lithium metal. The electrolyte is of such nature that it complexes with the lithium ions, normally manganese or cobalt salts, are used in the non-aqueous electrolyte for this purpose, and these have been patented in several modifications.

Pure lithium, like sodium, is very reactive. It will vigorously react with water to form lithium hydroxide and hydrogen gas is liberated. Thus a non-aqueous electrolyte is used, and water is rigidly excluded from the battery pack by using a sealed container.

Lithium-ion batteries are common in portable consumer electronics because of their high energy-to-weight ratios, lack of memory effect, and slow self-discharge when not in use. In addition to consumer electronics, lithium-ion batteries are increasingly used in defense, automotive, and aerospace applications due to their high energy density.[7] However, certain kinds of mistreatment may cause conventional Li-ion batteries to explode.

The three primary functional components of a lithium-ion battery are the anode, cathode, and electrolyte, for which a variety of materials may be used. Commercially, the most popular material for the anode is graphite. The cathode is generally one of three materials: a layered oxide (such as lithium cobalt oxide), one based on a polyanion (such as lithium iron phosphate), or a spinel (such as lithium manganese oxide), although materials such as TiS2 (titanium disulfide) originally were also used.[8] Depending on the choice of material for the anode, cathode, and electrolyte, the voltage, capacity, life, and safety of a lithium-ion battery can change dramatically. Recently, novel architectures have been employed to improve the performance of these batteries. Lithium-ion batteries are not to be confused with lithium batteries, the key difference being that lithium batteries are primary batteries, containing metallic lithium, while lithium-ion batteries are secondary batteries, containing an intercalation anode material.

wikipedia lithium ion batteries


 
 

 Li2FePO4F    3.6 V    115 mAh/g    0.414 kW·h/kg

 nearly half kilowatt hour  for every kilogram of battery

[piersdad]

trying out a 24v pack
this has 8 cells in series and a battery management system.
at first two tries it was ok but started to give off alarms  when used both in charging and discharging.
so with a bit of trepidation i opened up the seals and looked in
there were some electronics and a set of 8 round cells  linked together.
so i set up a 6 amp discharge  for the batteries and monitored each individual cell as well as the main voltage.
eventually on cell seemed to be the culprit as it would start off at 3.4 volts and gradually drop  to 3.1
 volts while all the rest stayed at 3.4 volts dropping to 3.2 volts
on charge from flat  this cell showed 2.2 volts and climbed to 3.9 volts where it set off the battery management systems alarm.

the batteries are secured with 6mm metric bolts and i noticed what appeared a loose nut and tried it and that was the cause of the alarms.
that super intelligent battery management system had told me that a cell interconnection was loose.
a quick tighten of that cell and check on all the other cells and the battery seems to be back to
normal
just found this  about battery management systems which are very essential for these batteries


The internal BMS controls the charging and takes fantastic
balancing functions. Each battery cell matches a LED light
which is an indicator of charging conditions. When power on,
all the lights are bright. The lights display different
colors red, yellow, and green to indicate the charging
conditions. It makes sure each single cell fully charged,
well balanced with the pack, and prevents any of the cells
from overcharging. Without the BMS, cells become unbalanced
after some cycles, their consistency is damaged and they can
be easily to be overcharged or discharged. With our
BMS/charger, you will never worry about this problem! We
provide the highest edge of technology and this technology
will benefit your whole battery system for a very long time.

http://www.evequipmentsupply.com/page52.html

the problem with this type of battery if they are discharge below 2.6 volts approx thy die permanently
they have an ionic  transfer ?? not a chemical one  hence their long life  and if they over charge and explode they have chemicals that are not harmful to touch and don't burn well
here is the result of lifepo4  explosion in my workshop   
http://www.storydad.com/forum/index.php/topic,615.0.html

[piersdad]

today’s lithium-ion batteries lose capacity over time, largely due to chemical reactions between the electrolytes and electrodes. Mohit Singh of the startup company SEEO is developing a novel electrolyte based on polymers, which are molecules made from long chains of repeating structural units. Singh combined a structurally stable polymer with one that is good at conducting ions to create an electrolyte layer that is both thinner and less chemically reactive than those in use today. Hiroyuki Nishide of Waseda University in Tokyo is developing a totally organic, flexible battery with electrodes made of chains of organic molecules instead of metals. This could avoid problems associated with certain metals, including limited availability and waste disposal. Compared to today’s lithium-ion batteries, Nishide’s offer the potential for faster charging and discharging and longer life, in exchange for, at the moment at least, lower charge densities.

 from  reserch on lifepo4 batterys

still wondering why the bateries collapse if they are discharged beyond 2.4 volts per cell they sem to die if flattened to much

just found this

Innovation Outbreak
Over the past decade, Belcher's laboratory has been exploring how viruses-embodiments of nature's own nanotechnology-can solve problems in materials science and microelectronics.

Previously, the group has shown that a genetically engineered virus called M13 can be used to help rearrange molecules-for example, to make batteries more efficient.

Hoping to solve the nanotube challenge, members of Belcher's lab altered M13 so that pieces of proteins, or peptides, on its surface could bind to carbon nanotubes.

By grabbing onto the nanotubes, the viruses stopped them from clumping, which allowed scientists to verify that the difference in electronic properties alone affected the nanotubes' function. Semiconducting ones raised efficiency, whereas metallic ones degraded it.

Practical Solutions For The Future
The MIT group discovered that using the viruses with semiconducting nanotubes improved the efficiency of dye-sensitized solar cells by almost a third, from eight percent to 10.6 percent. That improvement isn't gigantic in absolute terms, but it helps to make this variety of thin-film cell significantly more practical.

http://www.nanodaily.com/reports/Solar_Power_Goes_Viral_999.html
good explanation of how the virus  helps to modify the carbon to what they want