Nanoconfined NaAlH4 Conversion Electrodes for Li Batteries

In the past, sodium alanate, NaAlH 4 , has been widely investigated for its capability to store hydrogen, and its potential for improving storage properties through nanoconfinement in carbon scaffolds has been extensively studied. NaAlH 4 has recently been considered for Li-ion storage as a conversion-type anode in Li-ion batteries. Here, NaAlH 4 nanoconfined in carbon scaffolds as an anode material for Li-ion batteries is reported for the first time. Nanoconfined NaAlH 4 was prepared by melt infiltration into mesoporous carbon scaffolds. In the first cycle, the electrochemical reversibility of nanoconfined NaAlH 4 was improved from around 30 to 70% compared to that of nonconfined NaAlH 4 . Cyclic voltammetry revealed that nanoconfinement alters the conversion pathway, and operando powder X-ray diffraction showed that the conversion from NaAlH 4 into Na 3 AlH 6 is favored over the formation of LiNa 2 AlH 6 . The electrochemical reactivity of the carbon scaffolds has also been investigated to study their contribution to the overall capacity of the electrodes.