List of Figures
xxix
Fig. 7.5
A partial Li–Mn–Ni oxide phase diagram for bulk samples
synthesized in air at 900
◦ C. The thick solid black lines are
estimates to the boundaries of the layered region when quenched,
the dashed black line is the upper boundary when slow cooled,
and the blue dotted line is the cubic to layered phase transition.
The contour plots shown as thin red lines for the lattice
parameters were obtained using both combinatorial samples (not
shown, from Chap. 6) and bulk samples (red points); all plotted
compositions were determined by elemental analysis (with an
uncertainty of about 0.02 in molar fraction) ......................... 100
Fig. 7.6
Electrochemical data of half cells made from the M, N and R
materials obtained by heating in oxygen at 800
◦ C and quenching
to room temperature. The cells were first cycled between
2.5–4.6 V for two cycles (shown in all panels, with the first cycle
shown as a thick red line in the dQ/dV plots), then between 2–5 V
for ten cycles (for clarity, only a few of these are included in the
voltage versus capacity plots). All measurements were performed
at a constant specific current of 10 mA/g such that the M-layered
material was cycled at a rate of approximately C/24 (i.e., 24 h to
charge or discharge) .................................................... 102
Fig. 8.1
The phase diagram obtained in oxygen by quenching. The red
dotted lines represent constant oxidation number lines, S refers to
spinel compositions Li x Mn y Ni 3−x−y O 4 , R/L denotes rocksalt or
layered structures Li x Mn y Ni 2−x−y O 2 , and R
∗ denotes ordered
rocksalt structures with unoccupied 4b sites. The coordinates
used to label the lines are: (Ni oxidation number, Mn oxidation
number) .................................................................. 106
Fig. 8.2
A partial phase diagram for bulk samples quenched from 900
◦ C,
with compositions indicated for samples discussed throughout
this chapter. The black boundaries are estimates to the boundaries
of the layered region, while the blue dashed line is the
composition line with sufficient vacancies to have Ni
2+ , Mn
4+
and 2/3 of TM filled with Mn
4+ corresponding to the
solid-solution series Li[Li 1/3−x Ni x/2 P x/2 Mn 2/3 ]O 2 with
0 ≤ x ≤ 1/3. The green dashed line is the stoichiometric lithium
rich line discussed in the text .......................................... 107
Fig. 8.3
Monte Carlo results of sample Li 0.6 Mn 0.35 Ni 0.05 : the composition
at the top of the “bump” from the combinatorial studies, as shown
in Fig. 8.2. Two possible structures are included: (a, b) Mn
3+ is
present and (c, d) metal site vacancies (white areas) exist in
sufficient concentrations to maintain Mn
4+ . The diagrams shown
were obtained at high temperature with β T = 0.5 for a, c and a
temperature ten times lower with β T = 5.0 in b, d ................. 108
xxix
Fig. 7.5
A partial Li–Mn–Ni oxide phase diagram for bulk samples
synthesized in air at 900
◦ C. The thick solid black lines are
estimates to the boundaries of the layered region when quenched,
the dashed black line is the upper boundary when slow cooled,
and the blue dotted line is the cubic to layered phase transition.
The contour plots shown as thin red lines for the lattice
parameters were obtained using both combinatorial samples (not
shown, from Chap. 6) and bulk samples (red points); all plotted
compositions were determined by elemental analysis (with an
uncertainty of about 0.02 in molar fraction) ......................... 100
Fig. 7.6
Electrochemical data of half cells made from the M, N and R
materials obtained by heating in oxygen at 800
◦ C and quenching
to room temperature. The cells were first cycled between
2.5–4.6 V for two cycles (shown in all panels, with the first cycle
shown as a thick red line in the dQ/dV plots), then between 2–5 V
for ten cycles (for clarity, only a few of these are included in the
voltage versus capacity plots). All measurements were performed
at a constant specific current of 10 mA/g such that the M-layered
material was cycled at a rate of approximately C/24 (i.e., 24 h to
charge or discharge) .................................................... 102
Fig. 8.1
The phase diagram obtained in oxygen by quenching. The red
dotted lines represent constant oxidation number lines, S refers to
spinel compositions Li x Mn y Ni 3−x−y O 4 , R/L denotes rocksalt or
layered structures Li x Mn y Ni 2−x−y O 2 , and R
∗ denotes ordered
rocksalt structures with unoccupied 4b sites. The coordinates
used to label the lines are: (Ni oxidation number, Mn oxidation
number) .................................................................. 106
Fig. 8.2
A partial phase diagram for bulk samples quenched from 900
◦ C,
with compositions indicated for samples discussed throughout
this chapter. The black boundaries are estimates to the boundaries
of the layered region, while the blue dashed line is the
composition line with sufficient vacancies to have Ni
2+ , Mn
4+
and 2/3 of TM filled with Mn
4+ corresponding to the
solid-solution series Li[Li 1/3−x Ni x/2 P x/2 Mn 2/3 ]O 2 with
0 ≤ x ≤ 1/3. The green dashed line is the stoichiometric lithium
rich line discussed in the text .......................................... 107
Fig. 8.3
Monte Carlo results of sample Li 0.6 Mn 0.35 Ni 0.05 : the composition
at the top of the “bump” from the combinatorial studies, as shown
in Fig. 8.2. Two possible structures are included: (a, b) Mn
3+ is
present and (c, d) metal site vacancies (white areas) exist in
sufficient concentrations to maintain Mn
4+ . The diagrams shown
were obtained at high temperature with β T = 0.5 for a, c and a
temperature ten times lower with β T = 5.0 in b, d ................. 108