Page 267 - Lindens Handbook of Batteries

ALKALINE-MANGANESE DIOXIDE BATTERIES 11.5

FiguRE 11.4 Schematic representation of intergrowth between pyrolusite and ramsdellite
lattices.

TABLE 11.3 Different Manganese Oxide Structures
Mineral Space Group Z a(Å) b(Å) c(Å) β, γ (°) Reference
pyrolusite (β) p4 /mnm 2 4.398 — 2.873 90 Baur, 1976
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Ramsdellite pbnm 4 4.533 9.27 2.866 90 Byström, 1949
Nsutite (γ) [intergrowth] 4 4.45 9.305 2.85 90 De Wolff, 1959
Birnessite p ml 1 2.84 — 7.27 120 Giovanoli et al., 1970
ε-MnO p6 /mmc 1 2.80 — 4.45 120 De Wolff et al., 1978
3
2
Spinel (λ) Fd3m 16 8.029 — — 90 Mosbah et al., 1983
Hollandite (α) I2/m 2 10.026 2.8782 9.729 91.03 post et al., 1982
psilomelane C2/m 2 13.929 2.8459 9.678 92.39 Turner and post, 1988
Todorokite p2/m 8 9.764 2.8416 9.551 94.06 post and Bish, 1988
Manganite (γ) B2 /d 8 8.88 5.25 5.71 90 Dachs, 1963, 1973
1
Groutite (α) pbnm 4 4.560 10.7 2.87 90 Glasser and Ingram, 1968
Groutellite [pbnm] 4 4.7 9.531 2.864 90 JCpDS 42-1316
Feitkneichtite (β) p ml 1 3.32 — 4.71 120 Feitnecht et al., 1962
pyrochroite p ml 1 3.322 — 4.734 120 Christensen, 1965

MnOOH/MnO solid solution can undergo recrystallization into a less active form, resulting in a
2
noticeable loss of cell voltage under certain very slow discharge conditions.
4
Overall, the first half or more of the MnO discharge reaction is a simple proton-electron insertion
2
reaction with no structural change except for expansion and distortion of its lattice. Toward the end
3+
of the first electron discharge, however, the reaction proceeds through a soluble Mn species along
2+
3+
with a variety of Mn and Mn intermediate products, depending on the discharge conditions.
During discharge at the lower voltages, the MnOOH can be further discharged, as depicted by
the following equation:
-
3MnOOH + e → Mn O + OH + H O (11.2)
3
4
2
This reaction produces a flat discharge curve, but it only occurs under low-rate discharge conditions.
No additional volume change occurs during this reaction in the cathode. This step only provides
about one-third of the capacity of the first MnO reaction. During deep discharge, a further reduction
2
to Mn(OH) is possible but seldom occurs.
2