Atomic-Layer-Deposition Oxide Nanoglue for Sodium Ion Batteries

Atomic-layer-deposition (ALD) coatings
have been increasingly used
to improve battery performance. However, the electrochemical and mechanistic
roles remain largely unclear, especially for ALD coatings on electrodes
that undergo significant volume changes (up to 100%) during charging/discharging.
Here we investigate an anode consisting of tin nanoparticles (SnNPs)
with an ALD-Al2O3 coating. For the first time,
in situ transmission electron microscopy unveiled the dynamic mechanical
protection of the ALD-Al2O3 coating by coherently
deforming with the SnNPs under the huge volume changes during charging/discharging.
Battery tests in coin-cells further showed the ALD-Al2O3 coating remarkably boosts the cycling performance of the
Sn anodes, comparing with those made of bare SnNPs. Chemomechanical
simulations clearly revealed that a bare SnNP debonds and falls off
the underlying substrate upon charging, and by contrast the ALD-Al2O3 coating, like ion-conductive nanoglue, robustly
anchors the SnNP anode to the substrate during charging/discharging,
a key to improving battery cycle performance.