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NewellCrazy · 01-27-2013, 05:29 PM

Lithium iron phosphate battery

The lithium iron phosphate (LiFePO[SUB]4[/SUB]) battery, also called LFP battery (with "LFP" standing for "lithium ferrophosphate"), is a type of rechargeable battery, specifically a lithium-ion battery, which uses LiFePO[SUB]4[/SUB] as a cathode material. LiFePO[SUB]4[/SUB] batteries have somewhat lower energy density than the more common LiCoO[SUB]2[/SUB] design found in consumer electronics, but offers longer lifetimes, better power density (the rate that energy can be drawn from them) and are inherently safer. LiFePO[SUB]4[/SUB] is finding a number of roles in vehicle use and backup power.

Most lithium-ion batteries (Li-ion) used in consumer electronics products use lithium cobalt oxide cathodes (LiCoO[SUB]2[/SUB]). Other varieties of lithium-ion batteries include lithium manganese oxide (LiMn[SUB]2[/SUB]O[SUB]4[/SUB]) and lithium nickel oxide (LiNiO[SUB]2[/SUB]). The batteries are named after the material used for their cathodes; the anodes are generally made of carbon and a variety of electrolytes are used.[SUP][citation needed][/SUP]

The LiFePO[SUB]4[/SUB] battery uses a lithium-ion-derived chemistry and shares many advantages and disadvantages with other Lithium-ion battery chemistries. However, there are significant differences.

LFP chemistry offers a longer cycle life than other lithium-ion approaches.[SUP][6][/SUP]

The use of phosphates avoids cobalt's cost and environmental concerns, particularly concerns about cobalt entering the environment through improper disposal.[SUP][6][/SUP]
LiFePO[SUB]4[/SUB] has higher current or peak-power ratings than LiCoO[SUB]2[/SUB].[SUP][7][/SUP]

The energy density (energy/volume) of a new LFP battery is some 14% lower than that of a new LiCoO[SUB]2[/SUB] battery.[SUP][8][/SUP] Also, many brands of LFPs have a lower discharge rate than lead-acid or LiCoO[SUB]2[/SUB]. Since discharge rate is a percentage of battery capacity a higher rate can be achieved by using a larger battery (more ampère-hours).

LiFePO[SUB]4[/SUB] cells experience a slower rate of capacity loss (aka greater calendar-life) than lithium-ion battery chemistries such as LiCoO[SUB]2[/SUB] cobalt or LiMn[SUB]2[/SUB]O[SUB]4[/SUB] manganese spinel lithium-ion polymer batteries or lithium-ion batteries.[SUP][9][/SUP][SUP][10][/SUP] After one year on the shelf, a LiFePO[SUB]4[/SUB] cell typically has approximately the same energy density as a LiCoO[SUB]2[/SUB] Li-ion cell, because of LFP's slower decline of energy density. Thereafter, LiFePO[SUB]4[/SUB] likely has a higher density.

Safety
One important advantage over other lithium-ion chemistries is thermal and chemical stability, which improves battery safety.[SUP][6][/SUP] LiFePO[SUB]4[/SUB] is an intrinsically safer cathode material than LiCoO[SUB]2[/SUB] and manganese spinel. The Fe-P-O bond is stronger than the Co-O bond, so that when abused, (short-circuited, overheated, etc.) the oxygen atoms are much harder to remove. This stabilization of the redox energies also helps fast ion migration.[SUP][citation needed][/SUP]

As lithium migrates out of the cathode in a LiCoO[SUB]2[/SUB] cell, the CoO[SUB]2[/SUB] undergoes non-linear expansion that affects the structural integrity of the cell. The fully lithiated and unlithiated states of LiFePO[SUB]4[/SUB] are structurally similar which means that LiFePO[SUB]4[/SUB] cells are more structurally stable than LiCoO[SUB]2[/SUB] cells.[SUP][citation needed][/SUP]

No lithium remains in the cathode of a fully charged LiFePO[SUB]4[/SUB] cell—in a LiCoO[SUB]2[/SUB] cell, approximately 50% remains in the cathode. LiFePO[SUB]4[/SUB] is highly resilient during oxygen loss, which typically results in an exothermic reaction in other lithium cells.[SUP][4][/SUP]

As a result, lithium iron phosphate cells are much harder to ignite in the event of mishandling especially during charge, although any battery, once fully charged, can only dissipate overcharge energy as heat. Therefore failure of the battery through misuse is still possible. It is commonly accepted that LiFePO4 battery does not decompose at high temperatures.[SUP][6][/SUP] The difference between LFP and the LiPo battery cells commonly used in the aeromodeling hobby is particularly notable.[SUP][citation needed][/SUP]

Specifications

Cell voltage = min. discharge voltage = 2.8 V. Working voltage = 3.0 V – 3.3 V. Max. charge voltage = 3.6 V.
Volumetric energy density = 220 Wh/dm[SUP]3[/SUP] (790 kJ/dm[SUP]3[/SUP])
Gravimetric energy density = >90 Wh/kg[SUP][11][/SUP] (>320 J/g)
100% DOD cycle life (number of cycles to 80% of original capacity) = 2,000–7,000[SUP][12][/SUP]
Cathode composition (weight)
- 90% C-LiFePO4, grade Phos-Dev-12
- 5% Carbon EBN[SUP][disambiguation needed][/SUP]-10-10 (superior graphite)
- 5% PVDF
Cell Configuration
- Carbon-coated aluminium current collector 15
- 1.54 cm[SUP]2[/SUP] cathode
- Electrolyte: Ethylene carbonate-Dimethyl carbonate (EC-DMC) 1-1 LiClO[SUB]4[/SUB] 1M
- Anode: Graphite or Hard Carbon with intercalated Metallic lithium
Experimental conditions:
- Room temperature
- Voltage limits: 2.0 – 3.65 V
- Charge: Up to C/1 rate up to 3.6 V, then constant voltage at 3.6 V until I < C/24

Lithium iron phosphate battery - Wikipedia, the free encyclopedia

01-27-2013, 05:29 PM	#5
NewellCrazy Senior Member Join Date: Sep 2006 Location: Sugarland, TX or Salida,CO Posts: 1,867	Lithium iron phosphate battery The lithium iron phosphate (LiFePO[SUB]4[/SUB]) battery, also called LFP battery (with "LFP" standing for "lithium ferrophosphate"), is a type of rechargeable battery, specifically a lithium-ion battery, which uses LiFePO[SUB]4[/SUB] as a cathode material. LiFePO[SUB]4[/SUB] batteries have somewhat lower energy density than the more common LiCoO[SUB]2[/SUB] design found in consumer electronics, but offers longer lifetimes, better power density (the rate that energy can be drawn from them) and are inherently safer. LiFePO[SUB]4[/SUB] is finding a number of roles in vehicle use and backup power. Most lithium-ion batteries (Li-ion) used in consumer electronics products use lithium cobalt oxide cathodes (LiCoO[SUB]2[/SUB]). Other varieties of lithium-ion batteries include lithium manganese oxide (LiMn[SUB]2[/SUB]O[SUB]4[/SUB]) and lithium nickel oxide (LiNiO[SUB]2[/SUB]). The batteries are named after the material used for their cathodes; the anodes are generally made of carbon and a variety of electrolytes are used.[SUP][citation needed][/SUP] The LiFePO[SUB]4[/SUB] battery uses a lithium-ion-derived chemistry and shares many advantages and disadvantages with other Lithium-ion battery chemistries. However, there are significant differences. LFP chemistry offers a longer cycle life than other lithium-ion approaches.[SUP][6][/SUP] The use of phosphates avoids cobalt's cost and environmental concerns, particularly concerns about cobalt entering the environment through improper disposal.[SUP][6][/SUP] LiFePO[SUB]4[/SUB] has higher current or peak-power ratings than LiCoO[SUB]2[/SUB].[SUP][7][/SUP] The energy density (energy/volume) of a new LFP battery is some 14% lower than that of a new LiCoO[SUB]2[/SUB] battery.[SUP][8][/SUP] Also, many brands of LFPs have a lower discharge rate than lead-acid or LiCoO[SUB]2[/SUB]. Since discharge rate is a percentage of battery capacity a higher rate can be achieved by using a larger battery (more ampère-hours). LiFePO[SUB]4[/SUB] cells experience a slower rate of capacity loss (aka greater calendar-life) than lithium-ion battery chemistries such as LiCoO[SUB]2[/SUB] cobalt or LiMn[SUB]2[/SUB]O[SUB]4[/SUB] manganese spinel lithium-ion polymer batteries or lithium-ion batteries.[SUP][9][/SUP][SUP][10][/SUP] After one year on the shelf, a LiFePO[SUB]4[/SUB] cell typically has approximately the same energy density as a LiCoO[SUB]2[/SUB] Li-ion cell, because of LFP's slower decline of energy density. Thereafter, LiFePO[SUB]4[/SUB] likely has a higher density. Safety One important advantage over other lithium-ion chemistries is thermal and chemical stability, which improves battery safety.[SUP][6][/SUP] LiFePO[SUB]4[/SUB] is an intrinsically safer cathode material than LiCoO[SUB]2[/SUB] and manganese spinel. The Fe-P-O bond is stronger than the Co-O bond, so that when abused, (short-circuited, overheated, etc.) the oxygen atoms are much harder to remove. This stabilization of the redox energies also helps fast ion migration.[SUP][citation needed][/SUP] As lithium migrates out of the cathode in a LiCoO[SUB]2[/SUB] cell, the CoO[SUB]2[/SUB] undergoes non-linear expansion that affects the structural integrity of the cell. The fully lithiated and unlithiated states of LiFePO[SUB]4[/SUB] are structurally similar which means that LiFePO[SUB]4[/SUB] cells are more structurally stable than LiCoO[SUB]2[/SUB] cells.[SUP][citation needed][/SUP] No lithium remains in the cathode of a fully charged LiFePO[SUB]4[/SUB] cell—in a LiCoO[SUB]2[/SUB] cell, approximately 50% remains in the cathode. LiFePO[SUB]4[/SUB] is highly resilient during oxygen loss, which typically results in an exothermic reaction in other lithium cells.[SUP][4][/SUP] As a result, lithium iron phosphate cells are much harder to ignite in the event of mishandling especially during charge, although any battery, once fully charged, can only dissipate overcharge energy as heat. Therefore failure of the battery through misuse is still possible. It is commonly accepted that LiFePO4 battery does not decompose at high temperatures.[SUP][6][/SUP] The difference between LFP and the LiPo battery cells commonly used in the aeromodeling hobby is particularly notable.[SUP][citation needed][/SUP] Specifications Cell voltage = min. discharge voltage = 2.8 V. Working voltage = 3.0 V – 3.3 V. Max. charge voltage = 3.6 V. Volumetric energy density = 220 Wh/dm[SUP]3[/SUP] (790 kJ/dm[SUP]3[/SUP]) Gravimetric energy density = >90 Wh/kg[SUP][11][/SUP] (>320 J/g) 100% DOD cycle life (number of cycles to 80% of original capacity) = 2,000–7,000[SUP][12][/SUP] Cathode composition (weight) 90% C-LiFePO4, grade Phos-Dev-12 5% Carbon EBN[SUP][disambiguation needed][/SUP]-10-10 (superior graphite) 5% PVDF Cell Configuration Carbon-coated aluminium current collector 15 1.54 cm[SUP]2[/SUP] cathode Electrolyte: Ethylene carbonate-Dimethyl carbonate (EC-DMC) 1-1 LiClO[SUB]4[/SUB] 1M Anode: Graphite or Hard Carbon with intercalated Metallic lithium Experimental conditions: Room temperature Voltage limits: 2.0 – 3.65 V Charge: Up to C/1 rate up to 3.6 V, then constant voltage at 3.6 V until I < C/24 Lithium iron phosphate battery - Wikipedia, the free encyclopedia __________________ Sean If Ain't a Newell, It Ain't Wurt Oonin!