Low Temperature Rapid Interfacial Kinetics Achieved by Sodium Titanate Anode Co‐Intercalation Storage Mechanism and Stable Solid Electrolyte Interface

Abstract

Quasi‐layered sodium titanates have been extensively studied as anode materials for sodium‐ion batteries (SIBs) owing to their quasi‐zero‐strain intercalative storage chemistry and high theoretical capacity. However, their sluggish sodiation kinetics and unstable electrode/electrolyte interface lead to rapid capacity decay at low temperatures. Herein, the local electronic structure and interlayer spacing of Na₂Ti₂O₅ are finely regulated by heteroelement Sn‐doping, oxygen rich vacancies, and carbon‐confined structure (Sn‐HNTO@C) to improve low‐temperature performance. Theoretical calculations and Sn doping concentration control confirm that appropriate concentrations of heteroelement Sn‐doping and vacancy defects can redistribute charge density, enhance Na⁺ adsorption, reduce Na⁺ diffusion energy barriers, and endow Sn‐HNTO@C anode with stable capacity. In addition, optimizing electrolyte systems at low temperatures allows Sn‐HNTO@C to exhibit a Na⁺‐solvent co‐intercalation storage mechanism in ether‐based electrolytes, avoiding high desolvent energy barriers and reducing charge transfer activation energy. Furthermore, the thin, stable solid electrolyte interface rich in organic components promotes the low‐temperature interfacial Na⁺ kinetics. Consequently, Sn‐HNTO@C anode delivers high capacity over 500 cycles (177 mAh g⁻¹) and Sn‐HNTO@C//Na₃(VPO₄)₂F₃ full cell presents 91 mAh g⁻¹ over 200 cycles (−15 °C). This study provides unique guidance for optimizing sodium titanate anodes and emphasizes the importance of the low‐temperature electrode/electrolyte interface for SIBs.