From Design to Processing of Tin–Germanium Alloy Nanoplatelet Anodes for Li-Ion and Na-Ion Batteries

Advancement of both lithium-ion battery and sodium-ion battery technologies requires identification of electrode materials capable of accommodating both lithium and sodium ions, thereby enabling dual-function anodes and direct performance comparisons. In this study, we demonstrated the growth of Sn x Ge 1– x alloy crystals that are suitable for both battery types. Substantial liquid-phase exfoliation of nonlayered Sn x Ge 1– x material produced quasi-2D nanoplatelets. These nanoplatelets were combined with carbon nanotubes to fabricate porous, conductive, and mechanically robust electrodes. The resulting Sn x Ge 1– x /CNT composite electrodes achieved reversible capacities of 1215 mAh/g for Li-ion storage and 930 mAh/g for Na-ion storage at a current density of 125 mAh/g. Notably, these electrodes retained 99% of their capacity over 500 charge–discharge cycles at high current densities (1250 mAh/g), indicating excellent stability. Comparative analysis reveals that, in lithium-ion cells, reversible capacities are governed by rapid alloying and dealloying reactions, whereas sodium-ion cells benefit from accelerated sodium intercalation and deintercalation, facilitating near-complete utilization of the active material. Additionally, lithium-ion-storing anodes exhibit higher reversible capacities than sodium-ion-storing anodes, likely due to mechanical degradation associated with the larger sodium ion size.