Transcript Li-ion batteries

Li-ion batteries
• Positive electrode: Lithiated form of a transition metal oxide (lithium cobalt
oxide-LiCoO2 or lithium manganese oxide LiMn2O4)
• Negative electrode: Carbon (C),
usually graphite (C6)
• Electrolyte: solid lithium-salt electrolytes
(LiPF6, LiBF4, or LiClO4)
and organic solvents (ether)
http://www.fer.hr/_download/repository/Li-ION.pdf
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© Alexis Kwasinski, 2012
Li-ion batteries
• Chemical reaction (discharge)
• Positive electrode
Li1-xCoO2 + xLi+ + xe-
LiCoO2
Through electrolyte
• Negative electrode
•Overall
xLi+ + xe- + 6C
LiCoO2 + C6
LixC6
Through load
Li1-xCoO2 + C6Lx
• In the above reaction x can be 1 or 0
• With discharge the Co is oxidized from Co3+ to Co4+. The reverse process
(reduction) occurs when the battery is being charged.
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© Alexis Kwasinski, 2012
Li-ion batteries
• Contrary to lead-acid batteries, Li-ion batteries do not accept well a high initial
charging current.
• In addition, cells in a battery stack needs to be equalized to avoid falling below
the minimum cell voltage of about 2.85 V/cell.
• Thus, Li-ion batteries need to be charged at least initially with a constantcurrent profile. Hence they need a charger
• Typical float voltage is above 4 V
(typically 4.2 V).
Saft Intensium 3 Li-ion battery
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“Advanced Lithium Ion Battery Charger”
V.L. Teofilo, L.V. Merritt and R.P. Hollandsworth
© Alexis Kwasinski, 2012
Li-ion batteries
• Effects of temperature:
http://www.gpbatteries.com/html/pdf/Li-ion_handbook.pdf
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Li-ion batteries
• Controlled charging has 2 purposes:
• Limiting the current
• Equalizing cells
“Increased Performance of Battery Packs by Active Equalization”
Jonathan W. Kimball, Brian T. Kuhn and Philip T. Krein
Saft Intensium 3 Li-ion battery
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“Advanced Lithium Ion Battery Charger”
V.L. Teofilo, L.V. Merritt and R.P. Hollandsworth
© Alexis Kwasinski, 2012
Li-ion batteries
• Factors affecting life:
• Charging voltage.
• Temperature
• Age (time since manufacturing)
• Degradation process: oxidation
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© Alexis Kwasinski, 2012
Li-ion batteries
• Advantages with respect to lead-acid batteries:
• Less sensitive to high temperatures (specially with solid electrolytes)
• Lighter (compare Li and C with Pb)
• They do not have deposits every charge/discharge cycle (that’s why the
efficiency is 99%)
• Less cells in series are need to achieve some given voltage.
• Disadvantages:
• Cost
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© Alexis Kwasinski, 2012
Ni-MH batteries
• Negative electrode: Metal Hydride such as
AB2 (A=titanium and/or vanadium, B=
zirconium or nickel, modified with chromium,
cobalt, iron, and/or manganese) or AB5
(A=rare earth mixture of lanthanum, cerium,
neodymium, praseodymium, B=nickel,
cobalt, manganese, and/or aluminum)
• Positive electrode: nickel oxyhydroxide
(NiO(OH))
• Electrolyte: Potassium hydroxide (KOH)
Cobasys batteries
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© Alexis Kwasinski, 2012
Ni-MH batteries
• Chemical reaction (discharge)
• Positive electrode
NiO(OH) + H2O + e-
Ni(OH)2 + OHThrough electrolyte
•Negative electrode
•Overall
MH + OH-
NiO(OH) + MH
Through load
M + H2O + e-
Ni(OH)2 + M
• The electrolyte is not affected because it does not participate in the reaction.
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© Alexis Kwasinski, 2012
Ni-MH batteries
• It is not advisable to charge Ni-MH batteries with a constant-voltage method.
Ni-MH batteries do not accept well a high initial charging current.
• Float voltage is about 1.4 V
• Minimum voltage is about 1 V.
Cobasys Nigen battery
Saft NHE module battery
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© Alexis Kwasinski, 2012
Ni-MH batteries
• Effects of temperature:
Saft NHE module battery
http://www.panasonic.com/industrial/battery/oem/images/pdf
/panasonic_nimh_overview.pdf
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Ni-MH batteries
• Advantages:
• Less sensitive to high temperatures than Li-ion and Lead-acid
• Handle abuse (overcharge or over-discharge better than Li-ion bat
• Disadvantages:
• More cells in series are need to achieve some given voltage.
• Cost
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© Alexis Kwasinski, 2012
Ni-Cd batteries
• Negative electrode: Cadmium (Cd) – instead of the MH in Ni-MH batteries
• Positive electrode: nickel oxyhydroxide (NiO(OH)) – the same than in Ni-MH
batteries
• Electrolyte: Potassium hydroxide
(KOH) solution
Saft batteries
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© Alexis Kwasinski, 2012
Ni-Cd batteries
• Chemical reaction (discharge)
• Positive electrode 2NiO(OH) + 2H2O + 2e-
2Ni(OH)2 + 2OHThrough electrolyte
• Negative electrode
•Overall
Cd +
2OH-
2NiO(OH) + Cd + 2H2O
Through load
Cd(OH)2 + 2e-
2Ni(OH)2 + Cd(OH)2
• The electrolyte is not affected because it does not participate in the reaction.
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© Alexis Kwasinski, 2012
Ni-Cd batteries
• It is not advisable to charge Ni-Cd batteries with a constant-voltage method.
Ni-Cd batteries do not accept well a high initial charging current, but they can
withstand it sporadically.
• Float voltage is about 1.4 V
• Minimum voltage is about 1 V.
Saft Ultima plus
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http://www.saftbatteries.com/doc/Documents/telecom/Cube788/tel
_tm_en_0704.26962445-6b1b-44fb-aea7-42834c32be40.pdf
© Alexis Kwasinski, 2012
Ni-Cd batteries
• Effects of temperature:
http://www.saftbatteries.com/doc/Documents/telecom/Cube788/tel
_tm_en_0704.26962445-6b1b-44fb-aea7-42834c32be40.pdf
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© Alexis Kwasinski, 2012
Ni-Cd batteries
• Due to their better performance at high temperatures, Ni-Cd batteries are replacing
Lead-acid batteries in outdoor stationary applications. But, they do not resist hurricanes
very well, yet……(AT&T’s DLC at Sabine Pass CO, Saft NCX batteries)
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© Alexis Kwasinski, 2012
Ni-Cd batteries
• Advantages:
• Less sensitive to high temperatures than all the other batteries
• Handle some abuse (overcharge or over-discharge better than Li-ion
bat)
• Disadvantages:
• More cells in series are need to achieve some given voltage.
• Cost
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© Alexis Kwasinski, 2012
Ni-Cd batteries
• Comparison with Ni-MH batteries (not much of a difference)
Portable NiCd- and Ni-MH-Batteries for Teiecom Applications
J. Heydecke and H.A. Kiehne
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Battery technologies
Cobasys: “Inside the Nickel Metal Hydride Battery”
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