Synthesis, characterization and electrochemical performance of Al-substituted Li2MnO3

Abstract

a b s t r a c tLi 2 MnO 3 is known to be electrochemically inactive due to Mn in tetravalent oxidation state. Several compositions such as Li 2 MnO 3 , Li 1.5 Al 0.17 MnO 3 , Li 1.0 Al 0.33 MnO 3 and Li 0.5 Al 0.5 MnO 3 were synthesized by a sol-gel Pechini method. All the samples were characterized with XRD, Raman, XPS, SEM, Tap density and BET analyzer. XRD patterns indicated the presence of monoclinic phase for pristine Li 2 MnO 3 and mixed monoclinic/spinel phases (Li 2 − x Mn 1 − y Al x + y O 3 + z ) for Al-substituted Li 2 MnO 3 compounds. The Al substitution seems to occur both at Li and Mn sites, which could explain the presence of spinel phase. XPS analysis for Mn 2p orbital reveals a significant decrease in binding energy for Li 1.0 Al 0.33 MnO 3 and Li 0.5 Al 0.5 MnO 3 compounds. Cyclic voltammetry, charge/discharge cycles and electrochemical impedance spectroscopy were also performed. A discharge capacity of 24 mAh g −1 for Li 2 MnO 3 , 68 mAh g −1 for Li 1.5 Al 0.17 MnO 3 , 58 mAh g −1 for Li 1.0 Al 0.33 MnO 3 and 74 mAh g −1 for Li 0.5 Al 0.5 MnO 3 were obtained. Aluminum substitutions increased the formation of spinel phase which is responsible for cycling.Published by Elsevier B.V.

Probing room-temperature reactivity of H2S, SO2, and NO on the Li2MnO3 crystal surface by experimental and first-principles studies

“…The specific surface area calculated from the BET model ( S BET ) is 1.0 m 2 g −1 , which is in good agreement with the solid-state synthesis method. 44 The recorded XRD pattern of the sample fits well with the 01-081-1953 file from the Joint Committee Powder Diffraction Standards (JCPDS) database, corroborating the formation of the monoclinic Li 2 MnO 3 crystal phase. The presence of any secondary phase at least over the XRD detection limit (∼3 wt%) can be ruled out.…”

Electrochemical Investigations on the Effect of Mg-Substitution in Li2MnO3Cathode

“…Based on our observations and previous neutron diffraction studies of Al substitutions in the Li site of Li 2 MnO 3 , we believe that Mg is occupying the Mn site as well as the Li site. 12 Further neutron diffraction studies have to be performed to confirm the distribution of Mg in the lattice.…”

“…Such dual substitution of aluminum in the lithium and manganese sites provided a path to decrease the oxidation state of Mn, activating the material to improve its cycle performance. 12 In this study, we investigated the electrochemical and structural properties of Li 2 MnO 3 at room temperature by partially substituting lithium with magnesium using the sol-gel Pechini method.…”

Alleviating oxygen evolution from Li-excess oxide materials through theory-guided surface protection

“…Hence, these results directly support that (1) the Ru dopant preferentially occupy the surface, and (2) the Ru doping prevents surface oxygen evolution. Conversely, Al doping of Li 2 MnO 3 26 , was actually found to enhance degradation and structural transformation as compared to the original material 27 .…”