Chapter 7
Investigations of Bulk Li–Mn–Ni–O Samples
to Confirm the Combinatorial Studies
7.1 Motivation
Figure 7.1 shows isothermal sections of the Li–Mn–Ni–O phase diagrams obtained
for the milligram-scale combinatorial samples heated in oxygen, the supporting
evidence for which was presented in the last two chapters. Points A 7 and B 7 refer to
compositions studied here in order to confirm that the results of the combinatorial
work are relevant to bulk samples, and to help identify how the phase diagrams change
for bulk samples. The single-phase regions in the combinatorial studies were larger
than previously suspected with an expanded layered region that encompassed areas
both above and below the Li-rich layered line joining Li 2 MnO 3 to LiNi 0.5 Mn 0.5 O 2 .
This has significant consequences both in terms of reinterpreting published data and
obtaining a better overall understanding of the electrochemistry of these materials.
Some of these consequences will be explored in this chapter by studying bulk samples
synthesized at the compositions listed in Table 7.1.
A sample made at point A 7 in Fig. 7.1 should be primarily made up of the N and S
phases when quenched and convert to R and M during slow cooling. Rhines referred
to such a transformation as a ternary four-phase equilibrium [85], though it is of note
that oxygen content is changing here such that it is a more complicated transformation
than that considered by Rhines. Nonetheless, he predicted that such a point would
be present between two three-phase regions transforming during cooling as seen in
Chap. 6. Such a point transforming reversibly would be sufficient to demonstrate
that the three-phase regions exist and transform in the same manner as found in the
combinatorial studies. One objective of this chapter is to demonstrate that such a
point does exist for bulk samples synthesized in either air or oxygen.
It is important to confirm that the combinatorial results hold up well when synthesis of bulk samples is done in a tank reactor. In this chapter, a few preliminary
results obtained by Aaron Rowe will be included in order to discuss how boundaries
change for bulk samples, particularly those heated to higher temperatures.
Data in this chapter are reprinted from Refs. [12] and [84] with permission from the American
Chemical Society and the Electrochemical Society.
95
E. McCalla, Consequences of Combinatorial Studies of Positive Electrodes
for Li-ion Batteries, Springer Theses, DOI 10.1007/978-3-319-05849-8_7,
© Springer International Publishing Switzerland 2014
Investigations of Bulk Li–Mn–Ni–O Samples
to Confirm the Combinatorial Studies
7.1 Motivation
Figure 7.1 shows isothermal sections of the Li–Mn–Ni–O phase diagrams obtained
for the milligram-scale combinatorial samples heated in oxygen, the supporting
evidence for which was presented in the last two chapters. Points A 7 and B 7 refer to
compositions studied here in order to confirm that the results of the combinatorial
work are relevant to bulk samples, and to help identify how the phase diagrams change
for bulk samples. The single-phase regions in the combinatorial studies were larger
than previously suspected with an expanded layered region that encompassed areas
both above and below the Li-rich layered line joining Li 2 MnO 3 to LiNi 0.5 Mn 0.5 O 2 .
This has significant consequences both in terms of reinterpreting published data and
obtaining a better overall understanding of the electrochemistry of these materials.
Some of these consequences will be explored in this chapter by studying bulk samples
synthesized at the compositions listed in Table 7.1.
A sample made at point A 7 in Fig. 7.1 should be primarily made up of the N and S
phases when quenched and convert to R and M during slow cooling. Rhines referred
to such a transformation as a ternary four-phase equilibrium [85], though it is of note
that oxygen content is changing here such that it is a more complicated transformation
than that considered by Rhines. Nonetheless, he predicted that such a point would
be present between two three-phase regions transforming during cooling as seen in
Chap. 6. Such a point transforming reversibly would be sufficient to demonstrate
that the three-phase regions exist and transform in the same manner as found in the
combinatorial studies. One objective of this chapter is to demonstrate that such a
point does exist for bulk samples synthesized in either air or oxygen.
It is important to confirm that the combinatorial results hold up well when synthesis of bulk samples is done in a tank reactor. In this chapter, a few preliminary
results obtained by Aaron Rowe will be included in order to discuss how boundaries
change for bulk samples, particularly those heated to higher temperatures.
Data in this chapter are reprinted from Refs. [12] and [84] with permission from the American
Chemical Society and the Electrochemical Society.
95
E. McCalla, Consequences of Combinatorial Studies of Positive Electrodes
for Li-ion Batteries, Springer Theses, DOI 10.1007/978-3-319-05849-8_7,
© Springer International Publishing Switzerland 2014