6.2 Lithium Batteries and Lithium-Ion Batteries
127
Layered LiV 3 O 8 Cathode Material
In 1957, Wadsley first reported the layered Li 1+x V 3 O 8 and proposed its application
potential as cathode materials for lithium-ion batteries (Wadsley 2010). Until the
1980s, Besenhard et al. confirmed that Li 1+x V 3 O 8 has excellent lithium insertion
capability and found that Li 1+x V 3 O 8 as a lithium-ion battery cathode material has
the advantages of high Li-storage capacity and to a large extent overcomes Disulfide
clusters that cannot withstand deep discharges and moisture absorption in the air.
Since then, a group of people represented by Rome and Sofia have conducted indepth studies on the electrochemical properties of LiV 3 O 8 . Later, Picciotto and Zhang
used modern instrumental analysis techniques to systematically analyze the crystal
structure of Li 1+x V 3 O 8 (x = 0 ∼ 0.2) respectively.
LiV 3 O 8 is a typical layered compound belonging to the monoclinic space group
P2 1 /m (Picciotto et al. 1993). The crystal structure of LiV 3 O 8 is a layered structure
composed of octahedron and deformed trigonal bipyramid, and the (V 3 O 8 )
− layer
of the B–C plane is arranged in an orderly arrangement along a-axis. In the LiV 3 O 8
crystal, there are two types of structural units, the deformable VO 5 trigonal bipyramids and the VO 6 octahedra, and the two are connected to each other through a
common-angle oxygen atom to form a V–O layer. There are different octahedral and
tetrahedral voids between the V–O layers for lithium ion occupation. Interestingly,
Li 1+x V 3 O 8 crystal materials are fixedly connected by some of the interlayer lithium
ions, in contrast to other layered compounds interconnected by weak Van der Waals
forces. Lithium ions (Li 1 ) pre-existing in the material occupy octahedral sites. Due
to the high energy barrier at this location, lithium ions cannot easily escape. This
part of “dead lithium” (Li 1 ) takes on the role of structural support by a strong ionic
bond (V 3 O 8 )
− layer. Excess lithium (corresponding to x in Li 1+x V 3 O 8 occupies the
interlaminar tetrahedral gap, and this portion of lithium is a movable “live lithium”
(Li 2 ). Studies have shown that lithium ions at the octahedral sites do not block the
migration and diffusion of lithium ions at the tetrahedral sites. Therefore, this part
of the lithium can be freely embedded/de-embedded.
Since the pre-existing lithium of the LiV 3 O 8 basically occupies the interlaminar
octahedral position and belongs to the immobile “dead lithium”, when using LiV 3 O 8
as the positive electrode, it is necessary to use a negative electrode material capable of
providing a lithium source. Taking Li
LiV 3 O 8 system as an example, the electrode
reaction during charging and discharging is as follows:
Positive reaction: xLi xLi
+
+ xe
Anodic reaction: LiV 3 O 8 + xLi
+
+ xe Li 1+x V 3 O 8
At 2.63 V, theoretically 1 mol of LiV 3 O 8 can reversibly deintercalate more than
3 mol of lithium, corresponding to a specific capacity of up to 300 m Ah g
−1 .
Jin et al. (1998), through systematic experimental research, found that temperature
and current density had a great influence on the discharge capacity of Li 1+x V 3 O 8
during charging and discharging. When the current density is small, and temperature
is relatively high, the specific capacity is the largest. The lithium insertion process of
127
Layered LiV 3 O 8 Cathode Material
In 1957, Wadsley first reported the layered Li 1+x V 3 O 8 and proposed its application
potential as cathode materials for lithium-ion batteries (Wadsley 2010). Until the
1980s, Besenhard et al. confirmed that Li 1+x V 3 O 8 has excellent lithium insertion
capability and found that Li 1+x V 3 O 8 as a lithium-ion battery cathode material has
the advantages of high Li-storage capacity and to a large extent overcomes Disulfide
clusters that cannot withstand deep discharges and moisture absorption in the air.
Since then, a group of people represented by Rome and Sofia have conducted indepth studies on the electrochemical properties of LiV 3 O 8 . Later, Picciotto and Zhang
used modern instrumental analysis techniques to systematically analyze the crystal
structure of Li 1+x V 3 O 8 (x = 0 ∼ 0.2) respectively.
LiV 3 O 8 is a typical layered compound belonging to the monoclinic space group
P2 1 /m (Picciotto et al. 1993). The crystal structure of LiV 3 O 8 is a layered structure
composed of octahedron and deformed trigonal bipyramid, and the (V 3 O 8 )
− layer
of the B–C plane is arranged in an orderly arrangement along a-axis. In the LiV 3 O 8
crystal, there are two types of structural units, the deformable VO 5 trigonal bipyramids and the VO 6 octahedra, and the two are connected to each other through a
common-angle oxygen atom to form a V–O layer. There are different octahedral and
tetrahedral voids between the V–O layers for lithium ion occupation. Interestingly,
Li 1+x V 3 O 8 crystal materials are fixedly connected by some of the interlayer lithium
ions, in contrast to other layered compounds interconnected by weak Van der Waals
forces. Lithium ions (Li 1 ) pre-existing in the material occupy octahedral sites. Due
to the high energy barrier at this location, lithium ions cannot easily escape. This
part of “dead lithium” (Li 1 ) takes on the role of structural support by a strong ionic
bond (V 3 O 8 )
− layer. Excess lithium (corresponding to x in Li 1+x V 3 O 8 occupies the
interlaminar tetrahedral gap, and this portion of lithium is a movable “live lithium”
(Li 2 ). Studies have shown that lithium ions at the octahedral sites do not block the
migration and diffusion of lithium ions at the tetrahedral sites. Therefore, this part
of the lithium can be freely embedded/de-embedded.
Since the pre-existing lithium of the LiV 3 O 8 basically occupies the interlaminar
octahedral position and belongs to the immobile “dead lithium”, when using LiV 3 O 8
as the positive electrode, it is necessary to use a negative electrode material capable of
providing a lithium source. Taking Li
LiV 3 O 8 system as an example, the electrode
reaction during charging and discharging is as follows:
Positive reaction: xLi xLi
+
+ xe
Anodic reaction: LiV 3 O 8 + xLi
+
+ xe Li 1+x V 3 O 8
At 2.63 V, theoretically 1 mol of LiV 3 O 8 can reversibly deintercalate more than
3 mol of lithium, corresponding to a specific capacity of up to 300 m Ah g
−1 .
Jin et al. (1998), through systematic experimental research, found that temperature
and current density had a great influence on the discharge capacity of Li 1+x V 3 O 8
during charging and discharging. When the current density is small, and temperature
is relatively high, the specific capacity is the largest. The lithium insertion process of