Nanoconfined NaAlH Conversion Electrodes for Li Batteries

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