A lithium ion manganese oxide battery (LMO) is a lithium-ion cell that uses manganese dioxide, MnO
2, as the cathode material. They function through the same intercalation/de-intercalation mechanism as other commercialized secondary battery technologies, such as LiCoO
2. Cathodes based on manganese-oxide components are earth-abundant, inexpensive, non-toxic, and provide better thermal stability.[1]

Compounds

Spinel LiMn
2O
4

One of the more studied manganese oxide-based cathodes is LiMn
2O
4, a cation ordered member of the spinel structural family (space group Fd3m). In addition to containing inexpensive materials, the three-dimensional structure of LiMn
2O
4 lends itself to high rate capability by providing a well connected framework for the insertion and de-insertion of Li+
 ions during discharge and charge of the battery. In particular, the Li+
 ions occupy the tetrahedral sites within the Mn
2O
4 polyhedral frameworks adjacent to empty octahedral sites.[2][3] As a consequence of this structural arrangement, batteries based on LiMn
2O
4 cathodes have demonstrated a higher rate-capability compared to materials with two-dimensional frameworks for Li+
 diffusion.[4]

A significant disadvantage of cathodes based on LiMn
2O
4 is the surface degradation observed when the average oxidation state of the manganese drops below Mn+3.5. At this concentration, the formally Mn(III) at the surface can disproportionate to form Mn(IV) and Mn(II) by the Hunter mechanism.[5] The Mn(II) formed is soluble in most electrolytes and its dissolution degrades the cathode. With this in mind many manganese cathodes are substituted or doped to keep the average manganese oxidation state above +3.5 during battery use or they will suffer from lower overall capacities as a function of cycle life and temperature.[6]

Layered Li
2MnO
3

Li
2MnO
3 is a lithium rich layered rocksalt structure that is made of alternating layers of lithium ions and lithium and manganese ions in a 1:2 ratio, similar to the layered structure of LiCoO
2. In the nomenclature of layered compounds it can be written Li(Li0.33Mn0.67)O2.[7] Although Li
2MnO
3 is electrochemically inactive, it can be charged to a high potential (4.5 V v.s Li0) in order to undergo lithiation/de-lithiation or delithiated using an acid leaching process followed by mild heat treatment.[8][9] However, extracting lithium from Li
2MnO
3 at such a high potential can also be charge compensated by loss of oxygen from the electrode surface which leads to poor cycling stability.[10] New allotropes of Li
2MnO
3 have been discovered which have better structural stability against oxygen release (longer cycle-life).[11]

Layered LiMnO
2

The layered manganese oxide LiMnO
2 is constructed from corrugated layers of manganese/oxide octahedra and is electrochemically unstable. The distortions and deviation from truly planar metal oxide layers are a manifestation of the electronic configuration of the Mn(III) Jahn-Teller ion.[12] A layered variant, isostructural with LiCoO2, was prepared in 1996 by ion exchange from the layered compound NaMnO2,[13] however long term cycling and the defect nature of the charged compound led to structural degradation and cation equilibration to other phases.

Layered Li
2MnO
2

The layered manganese oxide Li
2MnO
2 is structurally related to Li
2MnO
3 and LiCoO2 with similar transition metal oxide layers separated by a layer containing two lithium cations occupying the available two tetrahedral sites in the lattice rather the one octahedral site. The material is typically made by low voltage lithiation of the parent compound, direct lithiation using liquid ammonia, or via use of an organic lithiating reagent.[14] Stability on cycling has been demonstrated in symmetric cells although due to Mn(II) formation and dissolution cycling degradation is expected. Stabilization of the structure using dopants and substitutions to decrease the amount of reduced manganese cations has been a successful route to extending the cycle life of these lithium rich reduced phases. These layered manganese oxide layers are so rich in lithium.

x Li
2MnO
3 • y Li
1+aMn
2-aO
4 • z LiMnO2 composites

One of the main research efforts in the field of lithium-manganese oxide electrodes for lithium-ion batteries involves developing composite electrodes using structurally integrated layered Li
2MnO
3, layered LiMnO2, and spinel LiMn
2O
4, with a chemical formula of x Li
2MnO
3 • y Li
1+aMn
2-aO
4 • z LiMnO2, where x+y+z=1. The combination of these structures provides increased structural stability during electrochemical cycling while achieving higher capacity and rate-capability. A rechargeable capacity in excess of 250 mAh/g was reported in 2005 using this material, which has nearly twice the capacity of current commercialized rechargeable batteries of the same dimensions.[15][16]

See also

References

  1. ↑ Thackeray, Michael M. (1997-01-01). "Manganese oxides for lithium batteries". Progress in Solid State Chemistry. 25 (1): 1–71. doi:10.1016/S0079-6786(97)81003-5. ISSN 0079-6786.
  2. ↑ Thackeray, M. M.; Johnson, P. J.; de Picciotto, L. A.; Bruce, P. G.; Goodenough, J. B. (1984-02-01). "Electrochemical extraction of lithium from LiMn2O4". Materials Research Bulletin. 19 (2): 179–187. doi:10.1016/0025-5408(84)90088-6. ISSN 0025-5408.
  3. ↑ Thackeray, Michael M.; Shao‐Horn, Yang; Kahaian, Arthur J.; Kepler, Keith D.; Skinner, Eric; Vaughey, John T.; Hackney, Stephen A. (1998-07-01). "Structural Fatigue in Spinel Electrodes in High Voltage ( 4 V ) Li / Li x Mn2 O 4 Cells". Electrochemical and Solid-State Letters. 1 (1): 7. doi:10.1149/1.1390617. ISSN 1944-8775. S2CID 97239759.
  4. ↑ Lanz, Martin; Kormann, Claudius; Steininger, Helmut; Heil, Günter; Haas, Otto; Novák, Petr (2000). "Large-Agglomerate-Size Lithium Manganese Oxide Spinel with High Rate Capability for Lithium-Ion Batteries". Journal of the Electrochemical Society. 147 (11): 3997. Bibcode:2000JElS..147.3997L. doi:10.1149/1.1394009. ISSN 0013-4651.
  5. ↑ Hunter, James C. (1981-09-01). "Preparation of a new crystal form of manganese dioxide: λ-MnO2". Journal of Solid State Chemistry. 39 (2): 142–147. Bibcode:1981JSSCh..39..142H. doi:10.1016/0022-4596(81)90323-6. ISSN 0022-4596.
  6. ↑ Du Pasquier, A.; Blyr, A.; Courjal, P.; Larcher, D.; Amatucci, G.; Gérand, B.; Tarascon, J‐M. (1999-02-01). "Mechanism for Limited 55°C Storage Performance of Li1.05Mn1.95 O 4 Electrodes". Journal of the Electrochemical Society. 146 (2): 428–436. Bibcode:1999JElS..146..428D. doi:10.1149/1.1391625. ISSN 0013-4651.
  7. ↑ Thackeray, Michael M.; Johnson, Christopher S.; Vaughey, John T.; Li, N.; Hackney, Stephen A. (2005-06-07). "Advances in manganese-oxide 'composite' electrodes for lithium-ion batteries". Journal of Materials Chemistry. 15 (23): 2257–2267. doi:10.1039/B417616M. ISSN 1364-5501.
  8. ↑ Kalyani, P.; Chitra, S.; Mohan, T.; Gopukumar, S. (1999-07-01). "Lithium metal rechargeable cells using Li2MnO3 as the positive electrode". Journal of Power Sources. 80 (1): 103–106. Bibcode:1999JPS....80..103K. doi:10.1016/S0378-7753(99)00066-X. ISSN 0378-7753.
  9. ↑ Lim, Jinsub; Moon, Jieh; Gim, Jihyeon; Kim, Sungjin; Kim, Kangkun; Song, Jinju; Kang, Jungwon; Im, Won Bin; Kim, Jaekook (2012-05-22). "Fully activated Li2MnO3 nanoparticles by oxidation reaction". Journal of Materials Chemistry. 22 (23): 11772–11777. doi:10.1039/C2JM30962A. ISSN 1364-5501.
  10. ↑ Robertson, Alastair D.; Bruce, Peter G. (2003-05-01). "Mechanism of Electrochemical Activity in Li 2 MnO 3". Chemistry of Materials. 15 (10): 1984–1992. doi:10.1021/cm030047u. ISSN 0897-4756.
  11. ↑ Wang, Shuo; Liu, Junyi; Sun, Qiang (2017-08-15). "New allotropes of Li2MnO3 as cathode materials with better cycling performance predicted in high pressure synthesis". Journal of Materials Chemistry A. 5 (32): 16936–16943. doi:10.1039/C7TA04941B. ISSN 2050-7496.
  12. ↑ Koetschau, I.; Richard, M. N.; Dahn, J. R.; Soupart, J. B.; Rousche, J. C. (1995-09-01). "Orthorhombic LiMnO2 as a High Capacity Cathode for Li‐Ion Cells". Journal of the Electrochemical Society. 142 (9): 2906–2910. Bibcode:1995JElS..142.2906K. doi:10.1149/1.2048663. ISSN 0013-4651.
  13. ↑ Armstrong, A. Robert; Bruce, Peter G. (1996). "Synthesis of layered LiMnO2 as an electrode for rechargeable lithium batteries". Nature. 381 (6582): 499–500. Bibcode:1996Natur.381..499A. doi:10.1038/381499a0. ISSN 0028-0836. S2CID 4330960.
  14. ↑ Johnson, Christopher S.; Kim, Jeom-Soo; Jeremy Kropf, A.; Kahaian, Arthur J.; Vaughey, John T.; Thackeray, Michael M. (2002-06-01). "The role of Li2MO2 structures (M=metal ion) in the electrochemistry of (x)LiMn0.5Ni0.5O2·(1−x)Li2TiO3 electrodes for lithium-ion batteries". Electrochemistry Communications. 4 (6): 492–498. doi:10.1016/S1388-2481(02)00346-6. ISSN 1388-2481.
  15. ↑ Johnson, C. S.; Li, N.; Vaughey, J. T.; Hackney, S. A.; Thackeray, M. M. (2005-05-01). "Lithium–manganese oxide electrodes with layered–spinel composite structures xLi2MnO3·(1−x)Li1+yMn2−yO4 (0". Electrochemistry Communications. 7 (5): 528–536. doi:10.1016/j.elecom.2005.02.027. ISSN 1388-2481.
  16. ↑ C. S. Johnson, J. T. Vaughey, M. M. Thackeray, T. E. Bofinger, and S. A. Hackney "Layered Lithium-Manganese Oxide Electrodes Derived from Rock-Salt LixMnyOz (x+y=z) Precursors" 194th Meeting of the Electrochemical Society, Boston, MA, Nov. 1–6, (1998)
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