Building a Stable Plateau-Type Na₂Ti₃O₇ Anode Interface toward Advanced Sodium-Ion Batteries

Layered structure Na2Ti3O7 with a suitable sodiation plateau potential (similar to 0.3 V vs Na+/Na) is a promising anode for highly safe sodium-ion batteries (SIBs). However, the practical use of Na2Ti3O7 is hindered by the unstable interface that forms between the anode and electrolyte leading to issues such as low initial coulombic efficiency (ICE) and cycling instability. Herein, we introduce tetraethyl orthosilicate (TEOS) as an electrolyte additive that can spontaneously and effectively react with the main component of the detrimental surface corrosion layer (sodium hydroxide, etc.) to form a protective film on the Na2Ti3O7 anode. The Na2Ti3O7 anode exhibits an enhanced capacity from 134.8 to 167.1 mAh g(-1) at 0.1 A g(-1), along with an increase in capacity retention from 56.1 to 83.9% after 250 cycles at 0.2 A g(-1). This work provides a straightforward protection strategy to address the unstable interface issues, rendering sodium titanate as a promising anode material to achieve practical application in the future.