Course notes
211
L Primary and secondary batteries
The most studied systems are primary and secondary batteries that combine
lithium in metallic form or in solid solution (lithium-ion) as negative electrode
and an insertion material as positive electrode; the two are separated by a lithium-ion solid electrolyte conductor. The objective is to create generators that
deliver voltages on the order of 3 V with specific capacities around 300 mA h g
−1
.
We limit ourselves to the two following examples:
2 Li / V 2 O 5 , with 0 < x < 1
xLi + V 2 O 5 m Li x V 2 O 5
2 LiMVO 4 / LiMn 2 − y M y O 4 , with M = Ni, Co, Cd, Zn
LiMVO 4 + LiMn 2−y M y O 4 m Li 1−x MVO 4 + Li 1+x Mn 2−y M y O 4
A promising positive electrode is LiFePO 4 .
L Fuel cells
Unlike the majority of the classic primary and secondary batteries, fuel cells are
“open” systems where the electrodes are continuously supplied with an active
substance while in operation. We can cite as an example polymer-electrolyte
fuel cells, such as Nafion-type fuel cells, which are proton-exchange membrane
fuel cells (PEMFCs), and solid oxide fuel cells (SOFCs), such as those that use
stabilized zirconia. The fuel in question is hydrogen and is generally obtained by
external or internal reforming of methane, and the oxidizer is oxygen from the
ambient air. The overall reaction in a fuel cell is the formation reaction of water
H 2 + 2
1
O 2 $ H 2 O
The elementary cell may be considered as an oxygen concentration cell whose
emf is given by the Nernst equation.
PEMFCs operate around 80 °C and presently use Nafion as electrolyte. The
electrodes are made of carbon that encloses Pt nanoparticles, which act as
electrocatalysts for the cathodic and anodic reactions.
SOFCs operate between 600 and 800 °C. The electrolyte consists of yttria-stabilized
zirconia, with the formula (ZrO 2 ) 0.92 (Y 2 O 3 ) 0.08 . The cathode material is a solid
solution of strontium-doped lanthanum manganite with the formula La 1−x Sr x MnO 3−δ . The anode is made of an yttria stabilized nickel-zirconia cermet containing
40% nickel by volume. It operates at high temperature, which is exploited for
cogeneration; in other words, to simultaneously produce electricity and heat.
211
L Primary and secondary batteries
The most studied systems are primary and secondary batteries that combine
lithium in metallic form or in solid solution (lithium-ion) as negative electrode
and an insertion material as positive electrode; the two are separated by a lithium-ion solid electrolyte conductor. The objective is to create generators that
deliver voltages on the order of 3 V with specific capacities around 300 mA h g
−1
.
We limit ourselves to the two following examples:
2 Li / V 2 O 5 , with 0 < x < 1
xLi + V 2 O 5 m Li x V 2 O 5
2 LiMVO 4 / LiMn 2 − y M y O 4 , with M = Ni, Co, Cd, Zn
LiMVO 4 + LiMn 2−y M y O 4 m Li 1−x MVO 4 + Li 1+x Mn 2−y M y O 4
A promising positive electrode is LiFePO 4 .
L Fuel cells
Unlike the majority of the classic primary and secondary batteries, fuel cells are
“open” systems where the electrodes are continuously supplied with an active
substance while in operation. We can cite as an example polymer-electrolyte
fuel cells, such as Nafion-type fuel cells, which are proton-exchange membrane
fuel cells (PEMFCs), and solid oxide fuel cells (SOFCs), such as those that use
stabilized zirconia. The fuel in question is hydrogen and is generally obtained by
external or internal reforming of methane, and the oxidizer is oxygen from the
ambient air. The overall reaction in a fuel cell is the formation reaction of water
H 2 + 2
1
O 2 $ H 2 O
The elementary cell may be considered as an oxygen concentration cell whose
emf is given by the Nernst equation.
PEMFCs operate around 80 °C and presently use Nafion as electrolyte. The
electrodes are made of carbon that encloses Pt nanoparticles, which act as
electrocatalysts for the cathodic and anodic reactions.
SOFCs operate between 600 and 800 °C. The electrolyte consists of yttria-stabilized
zirconia, with the formula (ZrO 2 ) 0.92 (Y 2 O 3 ) 0.08 . The cathode material is a solid
solution of strontium-doped lanthanum manganite with the formula La 1−x Sr x MnO 3−δ . The anode is made of an yttria stabilized nickel-zirconia cermet containing
40% nickel by volume. It operates at high temperature, which is exploited for
cogeneration; in other words, to simultaneously produce electricity and heat.