Nonporous Oxide-Terminated Multicomponent Bulk Anode Enabling Energy-Dense Sodium-Ion Batteries

Sodium-ion batteries (SIBs) are emerging as power sourcesfor large-scalestorage owing to their abundant and inexpensive sodium (Na) source,but their limited energy density hinders their commercialization.High-capacity anode materials, such as antimony (Sb), which are potentialenergy boosters for SIBs, suffer from battery degradation owing tolarge-volume-changes and structural instability. The rational designof bulk Sb-based anodes to enhance the initial reversibility and electrodedensity inevitably requires atomic- and microscale-considered internal/externalbuffering or passivation layers. However, unsuitable buffer engineeringcauses electrode degradation and lowers energy density. Herein, therationally designed intermetallic inner and outer oxide buffers forbulk Sb anodes are reported. The two chemistries in the synthesisprocess provide an atomic-scale aluminum (Al) buffer within the densemicroparticles and an external mechanically stabilizing dual oxidelayer. The prepared nonporous bulk Sb anode maintained excellent reversiblecapacity at a high current density and Na-ion full battery evaluationswith Na3V2(PO4)(3) (NVP)showing negligible capacity decay over 100 cycles. The demonstratedbuffer designs for commercially favorable micro-sized Sb and intermetallicAlSb shed light on the stabilization of high-capacity or large-volume-changeelectrode materials for various metal-ion rechargeable batteries.

Automated summary

Sodium-ion batteries (SIBs) are a promising power source for large-scale storage due to the abundance and low cost of sodium (Na). However, their limited energy density hampers commercialization. This study presents a rational design of intermetallic inner and outer oxide buffers for bulk Sb anodes, which effectively improve the reversibility and electrode density. The prepared nonporous bulk Sb anode shows excellent reversible capacity and negligible capacity decay over 100 cycles when evaluated with Na3V2(PO4)(3) (NVP) cathode.