Lithium iron phosphate

• Iron lithium phosphate
• Iron (II) phosphate, lithium-
• Lithium Iron Phosphate
• Lithium iron phosphate
• LFP

Commercial form: gray to black powder

Fixed

0.8 to 1.4 g · cm -3 ( bulk density )

> 300 ° C

Template: Infobox chemical / molecular formula search available

Lithium iron phosphate is an inorganic compound which is used in lithium ion batteries for charge storage. It is a mixed phosphate of iron and lithium and comes mostly as a carbonaceous gray to black powder in the trade.

Designation

According to the rules of inorganic nomenclature are listed in alphabetical order in connections with more cations this; therefore the connection should really be called the iron lithium phosphate. But this is not common. The material, or the so-equipped batteries are sometimes referred to by the abbreviation LFP, which is derived from the molecular formula LiFePO4.

Occurrence

Lithium iron phosphate comes in the form of the rather rare mineral Triphylin also in nature.

History

Lithium iron phosphate was first discovered in the form of the aforementioned Minerals Triphylin. This was found in 1834 by the German mineralogist Johann Nepomuk von Fuchs in the Bavarian Forest. He examined it and discovered that iron, lithium and Phoshphat contained, besides, he was also manganese. He named the new mineral.

Guided by John B. Goodenough working group proposed in 1997 as the first use of lithium iron phosphate as cathode material in lithium - ion batteries are used.

Production and representation

Starting materials for the preparation of lithium iron phosphate are lithium carbonate, lithium hydroxide or lithium phosphate, and iron salts such as ferrous carbonate, ferrous sulfate or iron phosphate. An example of such a reaction is the reaction of

Solid-state syntheses with a calcination at 400-800 ° C, often supplemented by grinding in a ball mill for better mixing, hydrothermal processes in which aqueous solutions warden used under high pressure, so that temperatures: Due to the increasing technical importance of LiFePO4 many different manufacturing methods have been developed can be obtained in excess of 100 ° C, and sol-gel processes. At sufficiently high temperatures, the cheaper the synthesis of iron ( III) salts may be used because it can be reduced by carbon in the Fe3 to Fe2 heat ( carbothermal reduction ), such as:

Lithium iron phosphate is produced industrially, among other things, the company Phostech lithium, which was a subsidiary of Süd-Chemie, which was itself taken over by Clariant 2011. Phostech lithium alone can produce at its plant in Candiac, Quebec 2500 tons per year LiFePO4.

Properties

Physical Properties

The electrical conductivity of LiFePO4 is low.

Lithium iron phosphate crystallizes in the olivine structure.

At low temperatures below 50 K LiFePO4 is antiferromagnetic.

Chemical Properties

Lithium iron phosphate is soluble in hydrochloric acid. Lithium can be extracted from the lithium iron phosphate to obtain the crystal lattice and causes iron (III ) phosphate FePO4.

LiFePO4 is thermodynamically very stable, there is upon heating - in contrast to lithium cobalt oxide - no oxygen from.

Use

Lithium iron phosphate lithium - storage material ( cathode material ) to the positive terminal of the lithium iron phosphate batteries. During charging of the battery is formed of iron ( III ) phosphate, that is during discharging back into lithium iron (II) phosphate transferred:

• Full charge.
• Complete discharge.

The voltage of the lithium iron phosphate, batteries is slightly smaller than the other lithium-ion rechargeable batteries at 3.3V.

Due to the high stability of LiFePO4 batteries are with this material as a particularly safe. Therefore, the corresponding accumulators are used in electric vehicles, such as electric bicycles. Also, in some electric cars lithium iron phosphate is used, eg in the BYD e6.

Safety

Lithium iron phosphate is considered non-toxic and therefore considered environmentally friendly.