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Aluminum Manganese Oxides with Mixed Crystal Structure: High‐Energy‐Density Cathodes for Rechargeable Sodium Batteries
Author(s) -
Han DongWook,
Ku JunHwan,
Kim RyoungHee,
Yun DongJin,
Lee SeokSoo,
Doo SeokGwang
Publication year - 2014
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201301254
Subject(s) - orthorhombic crystal system , manganese , cathode , materials science , phase (matter) , crystal structure , sodium , aluminium , chemical engineering , oxide , inorganic chemistry , chemistry , crystallography , metallurgy , organic chemistry , engineering
We report a new discovery for enhancing the energy density of manganese oxide (Na x MnO 2 ) cathode materials for sodium rechargeable batteries by incorporation of aluminum. The Al incorporation results in NaAl 0.1 Mn 0.9 O 2 with a mixture of tunnel and layered crystal structures. NaAl 0.1 Mn 0.9 O 2 shows a much higher initial discharge capacity and superior cycling performance compared to pristine Na 0.65 MnO 2 . We ascribe this enhancement in performance to the formation of a new orthorhombic layered NaMnO 2 phase merged with a small amount of tunnel Na 0.44 MnO 2 phase in NaAl 0.1 Mn 0.9 O 2 , and to improvements in the surface stability of the NaAl 0.1 Mn 0.9 O 2 particles caused by the formation of AlO bonds on their surfaces. Our findings regarding the phase transformation and structure stabilization induced by incorporation of aluminum, closely related to the structural analogy between orthorhombic Na 0.44 MnO 2 and NaAl 0.1 Mn 0.9 O 2 , suggest a strategy for achieving sodium rechargeable batteries with high energy density and stability.