Sodium titanium phosphate nanocube decorated on tablet-like carbon for robust sodium storage performance at low...

Sodium-ion batteries, featuring resource abundance and similar working mechanisms to lithium-ion batteries, have gained extensive interest in both scientific exploration and industrial applications. However, the extremely sluggish reaction kinetics of charge carrier (Na⁺) at subzero temperatures significantly reduces their specific capacities and cycling life. Herein, this study presents a novel hybrid structure with sodium titanium phosphate (NaTi₂(PO₄)₃, NTP) nanocube in-situ decorated on tablet-like carbon (NTP/C), which manifests superior sodium storage performances at low temperatures. At even -25 °C, a stable cycling with a specific capacity of 94.3 mAh/g can still be maintained after 200 cycles at 0.5 A/g, delivering a high capacity retention of 91.5 % compared with that at room temperature, along with an excellent rate capability. Generally, the superionic conductor structure, flat voltage plateaus, as well as the conductive carbonaceous framework can efficiently facilitate the charge transfer, accelerate the diffusion of Na⁺, and decrease the electrochemical polarization. Moreover, further investigations on diffusion kinetics, solid electrolyte interface layer, and the interaction between NTP and carbonaceous skeleton reveal its high Na⁺ diffusion coefficient, robust solid electrolyte interface, and strong electronic interaction, thus contributing to the superior capacity retentions at subzero temperatures.